Voltammetric Study On The Cd2+ - Pb2+
- Cu2+ Ternary System
DOINA BEJAN, AL. DUCA
pages 9 - 19
Abstract The present paper is aimed to report the
qualitative and quantitative study on the voltammetric behaviour of the Cd2+
- Pb2+ - Cu2+ ternary system in slightly acid (10-1 mol/L,
acetate buffer, pH = 4.5) solutions of (2 - 5) 10-6
mol/L concentrations, on the
carbon paste electrode (CPE) and CPE electrodes modified with NAFION (NAFION
coated carbon paste electrodes (NC-CPE), and NAFION entrapped carbon paste
electrodes (NE-CPE)). The influence of the electrode nature, the
pre-concentration and ion-exchange pre-concentration time, the potential
scanning rate, on the ternary system voltammetric behaviour were followed.
The intensity of the anodic current, as a signal of analytical interest,
increases rather proportionally with the increasing of ions concentration
and concentration time, and depends on the electrode nature. The method can
be applied for identifying and estimating the low concentrations of Cd2+,
Pb2+ and Cu2+ ions in complex environmental and biologicalsystems. Keywords: Cd2+-Pb2+-Cu2+ ternary system, ion-exchange
voltammetry, NAFION-ionomer, CPE, NAFION-CPEs
Biosorption Of Heavy Metals From The Environment Using
Yeasts As Biosorbents
RALUCA MARIA HLIHOR, MARIA GAVRILESCU
pages 21 -
37
Abstract Pollution with heavy metal is one of the
most important environmental problems today, since various industries and
human activities produce and discharge wastes containing different heavy
metals into the environment. Thus, metal as a kind of resource is becoming
shortage, it also brings about serious environmental pollution, threatening
human and ecosystem health. Biosorption is considered as a feasible
alternative for removing heavy metals from the environment, which utilizes
various natural materials of biological origin, including bacteria, fungi,
yeast, algae as sorbents. The first major challenge for the biosorption
field was to select the most promising types of biomass from an extremely
large pool of readily available and inexpensive biomaterials. In the field
of biosorption, yeasts have proved to be efficient sorbents and many
researches are reported and reviewed findings on the removal of heavy metal
ions. Due to their unicellular nature and high growth rate, the studies have
clearly demonstrated that yeasts can be used for trace enrichment of metal
ions in aquatic environments. The paper analyses some theoretical and
practical aspects on the topic of biosorption and specifies the main
features involved in the biosorption of heavy metals when yeasts are used as
sorbent, also providing some practical examples. Keywords: environmental pollution, biosorption,
sorbents, heavy metal removal, yeast
A New Coordination Compound Of Cd(II) With Ligand
Derived From N,N-bis (Salicylidene) - Methylenediamine
DOINA SIBIESCU, IRINA SPĂTĂRESCU, IOAN ROŞCA, MIHAELA VIZITIU
pages 39 -
47
Abstract A new coordination compound of cadmium (II)
with ligand derived from N,N-bis (salicylidene) – methylenediamine (Salmen)
of molar ratio 1:1 was synthesised and studied. The studies were made using
the methods: chemical analysis, IR absorption spectroscopy, thermogravimetry
and X-ray diffraction. The new compound presented a crystalline structure in
triclinic lattice with central atom Cd(II) tetracoordinated in tetrahedrical
structures. The obtaining reaction of the new compound is important for
gravimetric determination of Cd(II) with an error of ±0,25%. Keywords: Cadmium(II), N,N-bis (salicylidene) -
methylenediamine (Salmen), precipitating reagent, gravimetric determination.
Role Of Microorganisms In Organic Compounds Degradation
LAURA CARMEN APOSTOL, MARIA GAVRILESCU
pages 49 -
64
Abstract In recent years the ability of
microorganisms to metabolize organic compounds has received much attention
for environmental protection purposes due to the environmental persistence
and toxicity of these pollutants. The degradation of organic compounds can
take place with in the presence of bacteria, fungi, yeast and other
organisms under aerobic and anaerobic conditions and depends on the
biodegradability of organic compounds. This paper describes some
biodegradation processes of organic compounds originating from the activity
of microorganisms in the environment. The processes are considered in the
context of using these processes in natural and anthropic ways, which are
introduced to technological practice in order to clean up particular
environmental compartments. Keywords: organic compounds, bacteria, fungi, yeasts,
bioreactors.
A Regression Analysis Study Of Gas Drying By Adsorption
On Composite Materials
MARIUS SEBASTIAN SECULA, RODICA DIACONESCU, STELIAN
PETRESCU
pages 65 -
77
Abstract The purpose of this paper lies in the study
by regression analysis of gas drying by adsorption in fixed bed of composite
materials. The experimental investigations were carried out at two values of
relative humidity and three values of air flow rate respectively. The
evolution in time of some adsorption parameters, such as adsorption rate,
water concentration in the bed, water vapour concentration in air at the
exit from the fixed bed, drying degree and rate respectively is studied by
regression analysis. Based on these adsorption parameters, two composite
adsorbent materials having porous matrices were compared. Keywords: gas-drying, adsorption, mathematical
modelling, mass transfer, Silica gel.
2009, Volume
LV (LIX), Issue 2
Reduction of Energy Consumption for Nickel
Electroplating Process
FLORIN BANDRABUR, LILIANA LAZĂR
pages 9 - 19
Abstract In this paper, an analysis of the influence
of the parameters upon the energy consumption needed for nickel
electroplating process onto steel supports is performed. Reduced energy
consumption leads to a great energy yield, diminishing in the same time, the
cost of the final product, fact that satisfies the financial calculus of any
economic agent. The practical energy consumption is directly proportional
with the terminal voltage of the electrolyser. This depends on the
electrolyte composition and the operating parameter and is significantly
influenced by the voltage drop through the electrolyte. For an
electro-chemical reactor that functions at a certain temperature, the proper
selection of the distance between the electrodes, in order to decrease the
voltage drop through the electrolyte and, consequently, the energy
consumption, is essential. Keywords: nickel electroplating, energy yield, energy
consumption.
Kinetic and Thermodynamic Aspects of the Cationic Dye
Removal from Aqueous Solutions onto Fibrous Materials
DANIELA ŞUTEU, DOINA BÎLBĂ, TEODOR MĂLUŢAN
pages 21 - 30
Abstract In order to find new materials with
sorptive properties, the alkaline hydrolyzed polyacrylonitrile fibres
(Melana, Romania) (HPAN fibres) were tested in removal of some textile
cationic dyes from aqueous solutions. Kinetic and thermodynamic studies were
carried out to establish the favorable conditions for removal of dyes and to
understand the sorption mechanism. The kinetics of the sorption of Methylene
Blue and Crystal Violet dyes was analyzed using the pseudo-first order and
pseudo-second order kinetic models. The kinetic data fitted well to the
pseudo-second order kinetics, indicating the chemisorption of dyes onto
fibrous sorbent. The thermodynamic parameters ΔG, ΔH and ΔS were determined;
the obtained values show that the sorption of the studied dyes on HPAN
fibres is a spontaneous, endothermic and entropy-driven process. The
sorption mechanism of the cationic dyes onto hydrolyzed fibres was confirmed
by FTIR spectroscopy. The results of this study evidenced that the
hydrolyzed polyacrilonitrile fibres may be an inexpensive and efficient
sorbent for textile dyes removal from aqueous media Keywords: hydrolyzed polyacrylonitrile fibres, cationic
dyes, sorption, kinetics, thermodynamic study, FT-IR analysis.
Study of a New Complex of Cu(II), with 1-(3,5 Diiodo, 4
Methyl, 2 Hydroxy, Phenyl)- 2 Phenylsulfanyl Ethanone Ligand
IRINA SPĂTĂRESCU, DOINA SIBIESCU, IOAN ROŞCA , MARIUS
SEBASTIAN SECULA
pages 31 - 39
Abstract In this paper are presented the synthesis
and study of a new complex obtained from the reaction of Cu(II) with 1-(3,5
diiodo, 4 methyl, 2 hydroxy, phenyl)-2 phenylsulfanyl ethanone. The novel
complex, Cu(C15H11O2SI2)2, crystallizes in orthorhombic systems having as
central atom Cu(II) tetracoordinated with oxygen atoms from the groups >C=O
and •OH (phenolic). The obtaining reactions of this complex can be used in
the gravimetric determination of Cu(II), with an error of ± 0.21%. Keywords: Copper(II), precipitating reagent,
gravimetric determination..
Bioreactors of "Basket" Type with Immobilized
Biocatalysts
ROXANA BALTARU, ANCA-IRINA GALACTION, DAN CAŞCAVAL
pages 41 - 53
Abstract The spectacular applications of the
immobilized biocatalysts determined the design and construction of some
proper bioreactors, specific or derived from the "classical" ones. Among
them, the bioreactors with immobilized biocatalysts are some of the most
studied and applied bioreactors. The biocatalyst could be disposed around
the stirrer in a fixed bed with cylindrical geometry. This type of
bioreactor is known as "basket bioreactor". In this context, the aim of the
paper is to briefly review the recent literature on the main types of the
"basket" bioreactors with immobilized biocatalysts, from the viewpoint of
their construction and applications, by analyzing their
advantages/disadvantages comparatively to the other types of bioreactors Keywords: bioreactor, immobilized cells, biocatalyst,
fixed bed, basket bioreactors
Studies Regarding the Influence of Separation Method on
Physico-Chemical Properties of Microfibrillated Cellulose Structures
PETRONELA NECHITA, TEODOR MĂLUŢAN, DANIELA MANEA
pages 55 - 65
Abstract In the conditions of shortage of resources
reserves and their use in the open cycle, it is necessary to identify the
alternatives of raw materials. In this context, the cellulose micro
fibrillated structures extracted from plant tissues is a new way for
processing and using of annual plants and wood products. Due to the
economical and environmental advantages that are emphasized, these
structural elements facilitate the obtaining of composite materials with
high strength and durability that can be used in the high industrial fields,
such as: electronics, communications, buildings, medicine, etc. In this
paper are analyzed the results obtained after chemical (acid and alkaline
extraction) and chemical- mechanical treatments (wet refining in the
laboratory Hollander and colloidal mill combined with acid hydrolysis)
aiming to obtain the cellulose micro-structural elements, using as raw
material bleached softwood pulp. Keywords: Fibres, Microfibrilar structures, Composites,
Chemical preparation, Mechanical processing, Electronic microscopy, Optical
microscopy.
Life Cycle Impact Assessment of Pesticides: Current
Issues and Perspectives
LAURA CARMEN APOSTOL, RALUCA MARIA HLIHOR, CAMELIA
SMARANDA, VASILE LUCIAN PAVEL, BRINDUSA MIHAELA ROBU, FLORENTINA ANCA
CĂLIMAN , MARIA GAVRILESCU
pages 67 - 83
Abstract The paper analyses some aspects concerning
the Life Cycle Assessment as a tool for assessing the comprehensive
environmental impacts of products, processes and activities within
environmental management and decision making process. A special emphasis has
been paid to pesticides impacts, risks and toxicity for environment and
human health. Pesticides are biologically active substances that are
directly released to the environment during the use phase of their life
cycle. Pesticides are widely used and play an important role in the
production of vital goods such as food, feedstuffs and others, so that
pesticide life cycle analysis (PLCA) as a new procedure to discover concrete
deficiencies in the production, international trade, national distribution,
local application and storage. PLCA can be used for accounting the effects
of application and lack of application of pesticides. Keywords: environment, human health, impact, inventory
analysis, modelling, pesticides, risk.
Vegetal Fibers in Composite Materials - Advantages and
Limitations
DAN GAVRILESCU, BOGDAN MARIAN TOFĂNICĂ, ADRIAN CĂTĂLIN
PUIŢEL, PUIU PETREA
pages 85 - 104
Abstract Transition to a more sustainable economy
and the consequences of the Kyoto protocol on global climate changes
determine a shift of feedstock for energy and chemical industries from
fossil fuels and petrochemicals to renewable resources. The use of vegetal
fibers as major source of renewable resources represents a valuable
alternative both from economical and environmental points of view.
Traditionally, vegetal fibers are widely used in textile industry, paper
manufacture, and packaging. Due to their specific properties, vegetal fibers
are gained increased attention in obtaining composite materials. This paper
reviews the advantages and limitations of vegetal fibers that can be
potentially used as reinforcements in composite materials. The properties of
wood and annual plant fibers are briefly discussed. Some considerations
regarding environmental impact of using vegetal fibers in composites are
underlined. Keywords: vegetal fibers, nonwoods, composites,
renewable resources, environment.
2009, Volume
LV (LIX), Issue 3
Lead(II) Extraction in Aqueous PEG(1550) – (NH4)2SO4
Two-Phase Systems Using Iodide
Ions As Extracting Agent
LAURA BULGARIU, DUMITRU BULGARIU
pages 9 - 18
Abstract The extraction behaviour of lead(II) ions
was studied in aqueous polyethylene glycol (PEG) – (NH4)2SO4 two-phase
systems, in absence and in presence of iodide extractants, as a function of
several experimental parameters. The aqueous two-phase system, obtained by
mixing equal volumes of phase-forming components (PEG and (NH4)2SO4)
solutions, is composed by two immiscible phases and can be used for the
extraction studies. In absence of suitable extractant, the lead(II)
extraction is insignificant, and the variation of salt stock solution pH
does not change too much the extraction efficiency. The addition of iodide
ions determined a quantitative partition of lead(II) into PEG-rich phase.
The lead(II) extraction efficiency depends by the acidity of salt stock
solution and by the concentration of iodide added in extraction system. Keywords: lead(II), iodide extractant, extraction,
aqueous two-phase system.
Overview on Chromium Occurrence in the Environment and
Its Remediation
RALUCA MARIA HLIHOR, LAURA CARMEN APOSTOL, VASILE
LUCIAN PAVEL, CAMELIA SMARANDA, BRÎNDUŞA MIHAELA ROBU, FLORENTINA ANCA
CĂLIMAN, MARIA GAVRILESCU
pages 19 - 35
Abstract This paper first reviews the different forms of Cr present
in the environment as a function of environmental conditions. There are also
discussed the transport and fate of Cr(VI) as well as other forms of Cr in
the environment, most notably Cr(III). These forms or species of Cr are
inevitably linked by many environmental transport and fate processes. The
form of the Cr determines toxicity, mobility, and treatment strategy
applicability. Subsequently, a summary of common chemical processes
(reduction/oxidation, adsorption/desorption and precipitation/dissolution),
biological processes (reduction/oxidation, biosorption) and physical
processes utilized in remediation technologies were presented. Finally,
treatment technologies will be organized into three different categories:
toxicity reduction methods, removal treatments, and containment technologies
and discussed. Keywords: contamination, environment, heavy metals,
human health, modelling, oxidation state, persistence, remediation,
speciation.
Synthesis And Thermal Behavior of Some Mesogenic
Compounds Containing Azo Linkage
ELENA-RALUCA CIOANCĂ, CĂTĂLINA CIOBANU, GABRIELA LISA,
DAN SCUTARU
pages 37 - 48
Abstract The synthesis and thermal characterization
of some mesogenic groups containing azo likage are reported. Compounds were
prepared by Williamson alkylation reaction or esterification of
4’-hydroxy-4-formylazobenzene with linear alkyl bromides with 6 - 10 and 18
carbon atoms or carboxylic acids containing 5 - 10 and 18 carbon atoms. The
thermal stability of these compounds was established by using
thermogravimetric analysis. The reported compound do not present liquid
crystalline properties, but they may be used in the synthesis of new classes
of Schiff bases by reaction with specific diamino cores for formation of
bent core liquid crystals. Keywords: thermal behavior, mesogenic groups, azo
derivatives
Optimization Of W/O Emulsions Based on Polysaccharides
MIHAELA IANCU, MARCEL POPA, THIERRY HAMAIDE
pages 49 - 56
Abstract This paper tries to optimize the
preparation of stable w/o emulsions based on starch and
2-hydroxyethylcellulose as gelling agents for the aqueous phase. The
emulsification could be achieved at 70◦C in spite of the high viscosity of
the aqueous phase; the internal phase gelled upon cooling to room
temperature. The high viscosity of the aqueous phase limited the possible
concentration range of polysaccharide in the aqueous phase for a correct
emulsification. The presence of polysaccharides made the surfactant demand
larger for both the emulsification and the stabilization of the w/o
emulsions. Certain formulation variables, such as polysaccharide nature and
concentration, phase ratio, surfactant concentration and mixing regimen,
were investigated in order to obtain stable w/o emulsions Keywords: starch and 2-hydroxyethylcellulose, water/oil
emulsion
1,4-Disubstituted Thiosemicarbazides With Potential
Tuberculostatic Action
Abstract New thiosemicarbazides derived from
N-(p-nitrobenzoyl)-phenylalanine with potential tuberculostatic action were
obtained through the reaction of the N-(p-nitrobenzoyl)-phenylalanine
hydrazide with aromatic isothiocyanates. The chemical structure was
confirmed by elemental and spectral (FT-IR, 1H-NMR) analysis. The tests
performed on the toxicity and tuberculostatic activity recommends such
compounds as a possible clinical alternative to the drugs now in use. Keywords: thiosemicarbazides, tuberculostatic
inhibitors, hydrazides, phenylalanine derivatives.
Synthesis Of Cephalosporin Glutamic Acid Derivative: Its Immobilization On Microbial
Polysaccharides
DANIELA DUMITRAS, MARCEL POPA, VALERIU SUNEL
pages 65 - 87
Abstract This paper studies the synthesis and the
dicyclohexyl carbodiimide activated immobilization reaction through
ester-type covalent bonds of an oxazolone derived from
N-(m-nitrobenzoyl)-L-glutamic acid, ring opened with 7-
aminodesacetoxicephalosporanic acid (A7ADC) on polysaccharides (gellan and
xanthan). The maximal efficiency of coupling reaction was obtained for the
active principle – gellan system. For both systems was realised an
experimental program varying the following parameters: molar ratios
DCCI/medicament and medicament/support as well as the reaction time. To
achieve a maximum content of biologically active product in the
immobilization compounds, the highest values of the parameters are used. The
kinetics of the drug release process are studied in alkaline hydrolyse
conditions. Keywords: cephalosporin, aminoacid derivative, gellan,
xanthan, drug delivery.
New Hydrazones of 5-nitroindazol-1-Yl– Acethydrazide
With Pharmacological Potential
Abstract The actual concern for the preparation of new substances
with drug action involved – among others – the synthesis of hydrazones
derived from 5-nitroindazol-1-yl-acethydrazide. In this point of view, the
ethyl ester of the 5-nitroindazol-1- yl acetic acid was synthesized, then
subjected to the reaction with hydrazine hydrate, when 5-nitroindazol-1yl-
acethydrazide was obtained. Further on, its condensation with various
aromatic aldehydes gave a new series of N-acyl- hydrazones. The chemical
structure of the new synthesized compounds was confirmed through elemental
and spectral (FT-IR, 1H-NMR) analysis. Toxicological tests were also
performed and the obtained results recommend hydrazones as potential
therapeutical candidates. Keywords: hydrazones, hydrazidones, antimicrobial
activity, anti-tuberculosis activity
Studies Regarding the Influence of Reaction Conditions
on the Synthesis of Silver Nanoparticles
GABRIELA APOSTOLESCU, GABRIELA CARJA, NICOLAE
APOSTOLESCU, MOHAMED CHIBAN, ELENA HUSANU
pages 97 - 107
Abstract The paper explores the influence of process
parameters for synthesis of silver nanoparticles. Obtained nanoparticles
were characterized by UV-Vis spectroscopy and transmission electron
microscopy. Average particle diameter obtained ranged from 50 to 10 nm and
is depending on the used reducing agent nature, the type of surfactant and
its concentration. Keywords: silver nanoparticles, PVA and APA surfactant.
2009, Volume
LV (LIX), Issue 4
Convective Drying Kinetics of Porous Granules Support
Based Catalytic –Al2O3
LILIANA LAZĂR, MARCEL VRÂNCEANU, ION BALASANIAN,
STELIAN PETRESCU
pages 11 - 22
Abstract In this paper, the researches regarding the
kinetics of the convective drying of the porous granules based on –Al2O3,
manufactured by extruding and used as support for synthesis of the catalyst
through impregnation without interaction are presented. Within this
technology, the drying process that allows the removal of water from pores
and crystallization of the active component exhibits a determinant role for
achieving good catalytic properties. The drying curves were gravimetrically
determined at the atmospheric pressure, in the temperature range of 313 and
343 K, at different velocities of the drying agent (0.67 – 2.52 m/s). The
analysis of the experimental data shows that the process is favourably
influenced by the increase of the process temperature and the increase of
the drying agent velocity as well. Using the experimental data, the drying
rate was calculated and its dependence of the humidity of the material was
plotted. Kinetic equations for the stages of the drying process have been
proposed and the kinetic constants were determined from these models. Keywords: catalytic support, alumina, convective
drying, kinetic analysis.
CD and FT-IR Study of Some Adducts of Albumin with
Toxic Dinitrophenyl Derivatives
GABI DROCHIOIU, ADRIANA ADOCHIŢEI, LAURA HĂBĂSESCU,
GHEORGHIŢĂ ZBANCIOC, AUREL PUI, ROBERT GRĂDINARU, ELENA RUSU
pages 23 - 28
Abstract Conformational alterations of biomolecules
are very important in biological systems, forming part of the chain of
interactions leading to signal transduction. The CD spectra in the far-UV
region show that albumin has a slightly altered conformation if
dinitrophenyl derivatives are present in protein solution. The CD signal
becomes more complex in the positive region around 190-197 nm; the strong
negative peak at 227 nm changed both the position and the intensity upon
dinitrophenol binding. Although the spectrum is slightly different, probably
because of the interaction between the peptide/protein and DNP, no evidence
for an ordered structure such as helix or β-sheets can be found. FT-IR
measurements also confirmed conformational changes on binding dinitrophenols
to albumin and other proteins. Our results suggest that albumin could be a
protective agent against pesticide dinitrophenols. Keywords: peptide synthesis, metal-affinity, peptide
conformation, circular dichroism.
Sawdust as Biosorbent for Removal of Dyes from
Wastewaters. Equilibrium Study
DANIELA ŞUTEU, CARMEN ZAHARIA
pages 29 - 37
Abstract The sawdust, the waste from the wood
industry was study as alternative low cost biosorbent in removal of reactive
dye Orange 16 from aqueous solutions. In this paper we study the equilibrium
process to determine the quantitative characteristic parameters. In this
context Freundlich, Langmuir, Dubinin-Radushkevich and Tempkin isotherm
models were investigated at three temperatures. According to Langmuir
isotherm, the maximum sorption capacity was estimated as 8.554 mg g-1
(20ºC). Dubinin-Radushkevich equation was used to determine the energy of
sorption and to estimate the nature of the sorption process. The sorption
energy determined in the Dubinin-Radushkevich equation (9.45 kJ mol-1 at
20ºC) revealed an ion exchange mechanism for the reactive dye sorption onto
sawdust. Keywords: sorption, reactive dye, sawdust wastes,
sorption isotherms.
Cellulose Acetate Membrane: Preparation and
Characterisation
GABRIELA CIOBANU, DORINA IGNAT, GABRIELA CÂRJĂ,
CONSTANTIN LUCA
pages 39 - 46
Abstract Cellulose acetate membranes are used
extensively in reverse osmosis for the removal of salt from water. In this
study asymmetric membranes were fabricated from a ternary system consisting
of cellulose acetate, acetone and formamide or water using a phase inversion
process. These membranes were asymmetric-hydrophilic type with thickness
less than 200 tm. Keywords: cellulose acetate membranes, phase inversion
process.
Environmental Impact Assessment for an Industrial Unit
of Bricks Production
CARMEN ZAHARIA
pages 47 - 57
Abstract The environmental impact (EIA) for the
studied industrial unit of bricks production is assessed using both
alternative method of global pollution index (I*PG) and the
well-known method of global pollution index (IPG). The evaluated
environment components are considered to be: air, water resources (i.e.
ground water and final industrial effluent) and soil. The experimental
results correspond to the situation of ‘environment modified by
industrial/economic activities into admissible limits’ (I*GP =
1.53, and IGP= 1.85). In this context, the industrial company was
implementing monitoring actions in order to prevent/control environment
pollution. Keywords: bricks production, environment pollution,
environmental impact assessment (EIA), global pollution index
Study Regarding the Modification of Some Lignins from
Annual Plant Through Epoxydation
ADINA-MIRELA CĂPRARU, VALENTIN I. POPA, GABRIELA LISĂ,
TEODOR MĂLUŢAN
pages 59 - 68
Abstract In this paper are presented the results
obtained by modification of annual plant lignins through epoxydation: L1
(lignin of wheat straw), L2 (lignin of grass), and commercial products
(Pb1000 Pb2000, Pb3000), offered by GRANIT company. Reaction with
epichlorohydrin was performed in basic catalysis, aiming at increase
functionality. The resulting products were characterized in terms of
functionality (content of epoxy groups) and by FTIR and UV-VIS spectroscopy.
It was also performed a study of lignin derivatives by thermogravimetry
which allowed to establish a correlation between modification degree and
thermal stability. Keywords: lignin, epoxydation, FTIR, UV-VIS, thermal
analysis.
Chestnuts (Castanea Sativa) Extracts − A Potential
Plant Growth Regulator
ALINA STÎNGU, IRINA VOLF, VALENTIN I. POPA
pages 69 - 77
Abstract The valorization of waste products
represents an increasing challenge of economically sustainable and
environmentally friendly industrial processes. Chestnuts could be considered
an important raw material in those regions where these trees are growing,
not only for the fruit, but also for the wood. The aim of this paper was to
investigate the potential of chestnuts (Castanea sativa) shell aqueous
extract as plant growth regulator. Growth regulator potential of this
extract was evaluated in rape and oat seeds germination test by biometric
measurements of seedling plantlet and quantitative determination of fresh
biomass. Germination capacity, chlorophyll - and total chlorophyll content
were estimated for both rape and oat plantlets. Keywords: chestnuts shell, aqueous extract, rape, oat,
chlorophyll.
Biomechanical Factors in Living Tissues Growth
OCTAVIAN CIOBANU, GABRIELA CIOBANU
pages 79 - 88
Abstract Biomechanical factors influence the
processes of tissue growth, development, degeneration, and repair.
Regenerative strategies to restore damaged tissues in vivo and to create
living tissue replacements in vitro have begun to exploit advances in
understanding of how cells and tissues adapt to their mechanical
environment. All tissues from the body are living under pressure, due to
gravity, due to blood pressure and due to other organs pressure. If a tissue
is removed from the body, the obtained unloaded state is not naturally
stress free. This stress state within an unloaded body is called residual
stress. The residual stress may help the tissue to optimize its functions.
The paper reviews the present state of art in residual stress evaluation in
living tissues using several examples. Biomechanical factors are a keystone
to the successful application of therapies based on principles of tissue
engineering in biomedical researches. Keywords: living tissue, biomechanical factors,
residual stress.
Conformational Changes of Peptides on Binding Metals:
CD & FT-IR Studies
Abstract Two 19-residues alanine-rich peptides
containing histidine residues in various positions, namely
AAAAHAAAAHAAAAHAAAA (P1), and AAAHAAAHAAAHAAAAAAA (P2) have been synthesized
by Fmoc strategy and treated with heavy metal ions, such as Ag+, Hg2+, Pb2+,
Ni2+, Cu2+, Zn2+, Fe2+, etc. Both peptides and metal ion-complexes have been
characterized by Fourier transform infrared (FT-IR) spectroscopy,
electrospray ion trap mass spectrometry (ESI-MS) and circular dichroism
(CD). CD and FT-IR spectra showed that P1 and P2 have completely different
conformations and that only P1 is able to bind easily metal ions to form
complexes with an altered conformation. Because of rigid conformation as
revealed by CD, P2 is less able to accommodate metal ions. Consequently,
P2-metal ion spectra proved to be similar to those of pure P2. Keywords: peptide synthesis, metal-affinity, peptide
conformation, circular dichroism.
Study Regarding the Influence of Asclepias Syriaca
Aqueous Extracts in the Development of a Strain of Yeast (Rhodotorula SPP.)
ANCA-ROXANA HAINAL, IRINA VOLF, VALENTIN I. POPA
pages 95 - 101
Abstract This paper presents the results obtained in
the study of Rhodotorula spp. yeast cultivation in a culture medium
containing aqueous extract of Asclepias syriaca at different dry substance
concentration levels. The fermentation process was followed through
quantification of wet and dry biomass. After the wet biomass was recovered,
residual sugar and polyphenol concentration (by Folin-Ciocâlteu method) was
analyzed in the culture medium. Also the pH was determined every 24 hours
along the nine days period of the experiment. Keywords: Asclepias syriaca, Rhodotorula spp., biomass,
residual sugar, polyphenols pH, Folin-Ciocâlteu method.
Optimization Study of Orange 16 Dye Sorption Onto
Sawdust Wastes
CARMEN ZAHARIA, DANIELA ŞUTEU
pages 103 - 113
Abstract The application of sawdust wastes as
adsorptive materials into a textile wastewater treatment based on sorption
technology followed by solid/liquid separation using mechanical operations
such as sedimentation and filtration was indicated to be studied into last
years taking into account the recycling requirements of treated
wastewater/final effluent or "zero" effluent discharge into aquatic
environment. All kinetic experiments were performed on a laboratory scale
set- up in order to establish the optimal operational conditions (e.g.,
sawdust quantity, pH, sorption time, temperature) for high removal
efficiencies of Orange 16 dye. Variables concerning the sawdust quantity
(0.1-0.3 g per 25 mL), pH (1-4), and sorption time (5-160 min) are
considered in order to appreciate the treatment efficiency. An empirical
model was proposed by a third order compositive rotatable design,
considering these variables as independent ones, while dye removal was
chosen as optimization criteria. The local optimum values correspond to a
sawdust quantity of 0.15 g per 25 mL dye solution, a pH of 1, and a sorption
time of 50 min for a maximum dye removal of 57.3 8%. Keywords: optimization, experimental design, sorption,
Orange 16 dye.
Study of Radish (Raphanus Sativus L.) Response to
Elevated Level of Cadmium and Copper Ions
ALINA STÎNGU, IRINA VOLF, VALENTIN I. POPA
pages 115 - 124
Abstract Human activities release pollutants in the
environment; heavy metals, in particular, originated from industrial
emissions, mining activity, disposal of wastes and fertilizer and pesticide
use. Phytoextraction can provide an effective in situ technique for removing
heavy metals from polluted soils. The experiment reported in this paper was
undertaken to study the basic potential of phytoextraction of Raphanus
sativus (radish) grown in a elevated levels of copper and cadmium
contaminated sandy soil using a vegetative pots-experiment. Biometric
measurements of root, steam, leaf length and quantitative determination of
fresh mass were carried out to point out the morphological changes induced
by the presence of heavy metals in the growth medium. The heavy metal
content and bioaccumulation coefficient of radish plant were also determined
and the degree of recovery for each metal was calculated. The obtained data
indicated that radish plants are moderately tolerant to heavy metals. Keywords: radish, heavy metals, bioaccumulation
coefficient, degree of recovery.
General Aspects of Life Cycle Assessment for Paper and
Board Products
ALINA IOSIP, ELENA BOBU
pages 125 - 138
Abstract The paper presents the four basic stages of
Life Cycle Assessment (LCA) as a tool to evaluate the environmental impact
of processes and products and some aspects concerning the application of LCA
in pulp and paper industry. A special emphasis was put on the types of waste
generated in the pulp and paper manufacture and ecological and human health
effects, which define impact categories that could be assessed by LCA
studies. Keywords: life cycle assessment (LCA), environmental
impact, waste management, pulp, paper.
The Alcoholic Fermentation Study of the Saccharose
NECULAI CĂTĂLIN LUNGU, MARIA ALEXANDROAEI
pages 139 - 148
Abstract The aim of the present work is to evidence
what are the technological- economic parameters which characterize the
alcoholic fermentation of the saccharose in the presence of the
Saccharomyces cerevisiae yeast to different mean temperatures. The study was
carried out using a saccharose substrate with/no admixture of nutritive
substances, in a glass bioreactor. The experimental results conducted us to
the conclusion that the introduction of the nutritive substances containing
N,P,S,K and Mg elements, along with the growing factors from the
Saccharomyces cerevisiae yeast influence the enhancement of the cellular
metabolic processes and the decreasing of the fermentation total time. Keywords: alcoholic fermentation,
technological-economic parameters, saccharose.
UV Laser Applicability in Study of Accelarated Ageing
of Cellulosic Supports
NARCISA VRÎNCEANU, DIANA COMAN, ION SANDU, AURELIA
GRIGORIU, VIORICA VASILACHE
pages 149 - 155
Abstract The aim of this research was to
comparatively determine the immediate effects of irradiation treatment, of
two types of lasers (excimer pulsed laser and Nd: YAG pulsed laser), on
paper. The long-term impact of UV laser treatments performed onto the
stability of cellulose, by means of accelerated aging method, has been
evaluated as well. UV laser treatments disrupt long-term stability of paper
(highlighted by degree of polymerization –DP changes in GP and brightness of
the substrate). Accelerated aging tests have shown that the effect of Nd:
YAG pulsed laser emitting at 532 nm is more attenuated than that of excimer
laser operating at 308 nm. Keywords: ageing, cellulose, UV laser treatments.
The Influence of Some Chemical Agents Based on Natural
Products on the Conservation of Some Lignocellulose Composite Structures
ELENA UNGUREANU, OVIDIU UNGUREANU, VALENTIN I. POPA
pages 157 - 166
Abstract The analysis is made on the effect of some
chemical substances based on natural products: unmodified/modified straw
lignin chemically modified through hydroxymethylation, furan resin, as well
as solutions that contain copper ions (copper chloride and tetraamminocopper
hydroxide) on the conservation of some composite lignocellulose materials
represented by fir wood and beech wood samples. The study has been made on
the variety of humidity, the fluctuation of mass increase, the absorption
variation of the protective product, as well as the water absorption in the
membrane of the treated wood, with substance in three concentrations: 1, 3
and 5%. As a result of the analyses made, it has been noticed that the
degree of conservation of the composites is influenced by a range of
factors: the wood species, the type and the concentration of the chemical
agent that has been used, as well as the mechanism of interaction of the
chemical substances with the main components of the wood. Keywords: conservation, lignocellulose composite
structures, biocides systems, natural products, biodegradation.
Interaction of Proteins with Cross-Linked Poly(Vinyl
Amine) Multilayers
ECATERINA STELA DRĂGAN, FLORIN BUCATARIU
pages 167 - 173
Abstract Novel multilayer films consisting solely of
cross-linked single component layers were generated by a selective cross-
linking of the poly(vinyl amine) (PVAm) layers in [PVAm/poly(acrylic acid)
(PAA)]n films constructed on silica microparticles or silicon wafers,
followed by the removal of PAA. The adsorption of human serum albumin (HSA)
on the single component multilayers was followed by UV-Vis spectroscopy,
when the (PVAm)n films were deposited on silica microparticles. The surface
topography of the (PVAm)n multilayer thin films deposited on silicon wafers,
before and after the adsorption of HSA, has been studied by atomic force
microscopy. Keywords: poly(vinyl amine), layer-by-layer, human
serum albumin.
Preparation and Swelling Behavior of Chitosan-Based
Composite Hydrogels
ECATERINA STELA DRĂGAN, MARIA MARINELA PERJU
pages 175 - 180
Abstract In an attempt to obtain fully cationic
hydrogels with a good stability and high water uptake irrespective of pH,
the simultaneous cross-linking of two polycations, one natural (chitosan)
and another one synthetic, both bearing primary amine groups able to react
with glutaraldehyde in aqueous medium was performed. The main parameters
which controlled the properties of the composite hydrogels were: the molar
ratio between polycations, and the concentration of the cross-linking agent.
Information on the swelling mechanism of the gels was obtained from the
study of the swelling kinetics. Keywords: chitosan, cationic hydrogel, swelling ratio.
Ferrocene Containing Liquid Crystals
ROXANA MARIA AIOANEI, IRINA CÂRLESCU, DAN SCUTARU
pages 181 - 190
Abstract The paper presents synthesis and structural
characterization of some new ferrocenomesogens containing azo and ester
linking groups. The compounds were obtained by reacting 4-alkoxybenzoic acid
with 4-ferrocenyl-4’- hydroxyazobenzene. Keywords: ferrocene, esters, azo aromatic compounds,
ferrocenomesogens.
Thermosensitive Copolymers Obtained by Living Radical
Polymerization
ANCA DANIELA HODOROG (RUSU), IULIAN NOR, NICOLAE
HURDUC, CONSTANŢA IBĂNESCU
pages 191 - 198
Abstract Living radical polymerization is one of the
few methods that are available, in order to synthesize polymers with complex
architectures and a narrow polydispersity index. The present paper describes
few aspects concerning the synthesis and characterization of amphiphilic
polymers such as poly (dimethyl acrylamide)-g- polysiloxane. Because the
macromolecular chains contain both sequences of poly (dimethyl acrylamide)
which has a hydrophilic character, together with a hydrophobic polysiloxane
chain, these polymers has an amphiphilic character. Poly (dimethyl acrylic
amides) sequences have indeed a special property, being able to react in the
presence of thermal stimuli. Thus, depending on the existing conditions in
the external environment, these sequences may adopt a linear or entangled
conformation. If we associate these conformations with micelles structures,
this could lead to an aggregation/disaggregation phenomenon, under thermal
stimulation. The polymers were obtained by living radical polymerization
using a polysiloxane macro-initiator containing chlorobenzyl groups in the
macromolecular side chain. The used catalytic system was based on Cu (0) and
2, 2 '- bipyridyl. The reaction was performed in the presence of DMSO at
80°C. Polymers were characterized by 1H-NMR spectroscopy, thermal
gravimetric analysis and differential scanning calorimetry. The
conformational changes were revealed by rheological tests by studying the
variation of loss and accumulation modules depending on temperature. Keywords: thermo-sensitivity, self-assembly, living
radical polymerization.
Study on Isolation and Characterization of Some
Polyphenols from Agro-Industrial by-Products
IOANA IGNAT, H. FAUDUET, S. BOSTYN, M.I. POPA, IRINA
VOLF, V.I. POPA
pages 199 - 207
Abstract Phenolics are ubiquitous compounds found in
all plants as their secondary metabolites. These compounds represents one of
the most widely occurring groups of phytochemicals and they may act as
phytoalexins, antifeedants, attractants for pollinators, contributors to
plant pigmentation, antioxidants and protective agents against UV light,
among others. For these reasons, a great effort has been made to provide
highly sensitive and selective analytical methods for the determination and
characterization of polyphenols occurring in different plant tissues. The
aim of the present study is to ascertain the phenolic profile of two
different agro-industrial by-products (olive oil waste water and vinasse) Keywords: polyphenols, isolation, HPLC, ionic exchange.
Overview of the Water Footprint Concept Applied for the
Efficient Use of Water Resources
SIMONA-ANDREEA ENE, CORINA PETRONELA MUSTEREŢ, CARMEN
TEODOSIU
pages 209 - 218
Abstract This paper analyses the concept of water
footprint which has been developed in order to have an indicator of water
use in relation to human consumption. The water footprint of a country is
defined as the volume of water needed for the production of the goods and
services consumed by the inhabitants of that country. The concept of water
footprint is helpful for understanding human impacts on freshwater systems
and also may serve as a basis for strategies adequately tailored for
improving water balances between stakeholders (industry, agriculture and
other types of water users). Issues such as local water shortages and
pollution are better addressed by considering production and supply chains
as a whole, and by addressing the water cycles problems especially those
related to human consumption. This study presents an assessment of the major
issues posed by the implementation of the water footprint concept for the
river basin management, especially considering the actual challenges posed
by the Romanian context. Keywords: water footprint, water use, river basin
management.
Assessment of Water Quality Evolution in the
Prut-Bârlad River Basin
CLAUDIA COJOCARIU, IONUŢ CARAENE, GEORGE BARJOVEANU,
CARMEN TEODOSIU
pages 219 - 228
Abstract The need to approach in an integrated
manner the water resources issues in the river basin came due to the related
shortcomings of the limited and increasingly polluted water resources,
unable to sustain an ecosystem and which must be divided between the needs
and requirements of the society, many citizens still not having access to
sufficient and safe water supply. This paper presents an assessment of water
quality evolution in the Prut-Bârlad river basin between 2005 and 2007. The
assessment considers 5 major water quality classes (I, II, III, IV and V) as
defined by national legislation (Law no. 310/2004). Water quality analysis
was realized by monitoring physico-chemical, hydro- morphological and
biological parameters of the priority pollutants, considering the length of
the river afferent to each quality class. The water quality parameters were
monitored in relation to the main sources of pollution and included in a
specific water quality class of each monitoring section. The study showed
how the water quality in the Prut-Bârlad river basin evolved over the period
of analysis in terms of water quality, river length of the associated class
V being drastically reduced. Keywords: Prut River, Bârlad River, river basin, water
quality classes, water quality assessment.
2008, Volume
LIV (LVIII), Issue 1
Use Polyethylene Glycol-Based Aqueous Two-Phase Systems
for Selective Extraction of Zn(II) from Cobalt, Nickel, Iron (III) and Lead
LAURA BULGARIU, D. BULGARIU
pages 7 - 16
Abstract An aqueous two-phase system of polyethylene
glycol (PEG) and (NH4)2SO4 mixture using
thiocyanate ions as extractants, is proposed for the selective extraction of
Zn(II), from Co(II), Ni(II), Fe(III) and Pb(II). The aqueous two- phase
systems are prepared by mixing equal volumes of 40% [w/w] PEG(1,500)
solution and 40% [w/w] (NH4)2SO4 solutions
with different pH, and are composed from a polymer-rich phase and a
salt-rich phase. The experimental results showed that Zn(II) is
quantitatively extracted into PEG-rich phase in the pH range 1.5...3.5, at a
SCN- concentration higher than 0.04 mol/L, while the others ions
(Co(II), Ni(II), Fe(III) and Pb(II)) were little extracted in these
conditions. Cobalt and iron (III) ions were extracted to PEG-rich phase by
about 23% and 27%, respectively, but they did not interfere the extraction
of Zn(II). The competitive interactions between metal ions and extractant
(SCY) or phase forming anion (SO42-) plays an
important role in the extraction process. This method was used for the
selective zinc extraction from zinc polluted soils samples from industrial
zone of Jassy city (Romania). After extraction about 67% from Zn(II) was removed. Keywords: aqueous two-phase systems, polyethylene
glycol, selective extraction, zinc.
Analysis of Hydrodynamics and Mixing Behaviour of
Liquid Phase in External-Loop Airlift Reactors
MARIA GAVRILESCU,
RADU Z. TUDOSE
pages 17 - 38
Abstract In order to obtain further information on
the behavior and optimal design of external-circulation-loop airlift
bioreactors, the liquid circulation velocity, gas holdup and mixing
characteristics were studied using water and highly viscous pseudoplastic
solutions in two external-loop airlift rectors on bench and pilot scale,
considering various values of downcomer to riser cross sectional ratio, AD/AR
as well as the presence of static mixers. The analysis of EALRs showed that
hydrodynamic parameters, such as liquid circulation velocity and gas hold-up
are interdependent and highly determined by the gas superficial velocity,
which generate the circulation driving force in the contactors. Also, mixing
time and axial dispersion are dependent on the circulation intensity as well
as operating scale. It was concluded that the scale up process has to
consider process, geometric and material variables. Keywords: airlift, heterogeneous system, liquid
velocity, mixing time.
Abstract A study of axial mixing in pulsed
extraction column with sieve plates at a single liquid flow was presented in
this paper. The distribution of residence time, P6clet number and axial
dispersion coefficient were determined experimentally in the presence or
absence of pulsations at different values of liquid flow rate. The obtained
results emphasize how the pulsating amplitude and frequency as well as the
liquid flow rate influence the distribution function of residence time,
P6clet number and axial dispersion coefficient. Based on the experimental
values of distribution dispersion and cellular model, distribution function
of residence time was calculated. Comparing the calculated values with
experimental data of E(θ) function, it can be concluded that these are in a
good agreement. Keywords: axial dispersion coefficient, extraction
column with pulsations, extraction column with sieve plate, distribution of
residence time.
Influence of UV Radiation on the Paracetamol Ozonation
in Water
ILIE SIMINICEANU, MARIA BOBU, AYFER YEDILER
pages 53 - 66
Abstract The degradation of a paracetamol solution
(C0P =5 mmol.L-1) was studied in a
bench-scale setup by means of simple ozonation (O3) as well as by
the ozonation catalyzed with UV light (O3/UV) in order to
quantify the influence of UV light on the degradation process. The
efficiency was evaluated through five performance indicators: the conversion
of paracetamol ( XP );
the degree of mineralization ( XToc );
the apparent first- order rate constant (kap); Hatta number ( Ha)
and the enhancement factor (E). A kinetic assessment has been performed for
both processes. The main advantage of the photo-ozonation compared to the
simple ozonation can be described as an increased conversion (92% vs. 79%
after 90 minutes). Despite the fact that a superior rate constant (> 54%)
and a higher Hatta number (+ 24%) could be calculated, the process was still
in the slow reaction kinetic regime (Ha
< 0.3), with an enhancement factor which was not significantly increased.
The obtained results are useful for the design and scale-up of the
gas–liquid ozonation reactor. Keywords: conversion, mineralization, rate constant,
Hatta number, enhancement factor.
Synthesis and Thermal Behaviour of Brush and Star
Polymers Obtained by Atom Trasfer Radical Polymerization Reactions
IULIAN NOR, GABRIELA LISA, N. HURDUC, VIOREL SANDU
pages 67 - 76
Abstract Herein, we report the synthesis and thermal
stability study of some brush and star polymers starting from polysiloxanes
with chloro-benzyl groups in the side chain. The polymers that we have
prepared are cyclic and linear polysiloxanes grafted with styrene,
respectively copolymers (styrene-butyl acrylate) and
styrenechloromethylstyrene. We tried further to observe how these
macromolecular architectures influence the thermal stability of these
polymers by using a combination of Thermogravimetric Analysis (TGA) and
Differential Scanning Calorimetry (DSC). Keywords: ATRP, polysiloxanes, thermal analysis,
differential scanning calorimetry
Biotechnological Processes in Pulp and Paper Industry
Enzyme Treatment of Chemical Pulp
MIHAELA-ALINA BORDEIANU, DAN GAVRILESCU
pages 77 - 86
Abstract This paper presents the evolution of
biological catalysts use in pulp and paper industry, especially xylanases
which improve the conditions of less pollutant reactants use, assure less
aggressive bleaching parameters (lower temperature and pressure, less
aggressive pH) and advantageous conditions to treat pulp mill effluents. The
use of biological catalysts in pulp bleaching processes justifies the
concept of sustainable development in which a successful development is due
to the reorientation of the industry to renewable resources and natural
processes in order to pollution prevention, resource conservation and cost reduction. Keywords: biodelignification, enzymes, pulp bleaching,
environment.
Contaminated Sites Management. Case Study in Sălaj
County
AURICA GREG
pages 87 - 96
Abstract The soil is the aerated upper part of the
lithosphere, found in continuous evolution under the influence of several
pedo- genetic factors, being the superficial layer of the Earth in which the
vegetal life develops. Unlike other environmental factors, the soil has a
diminished self-cleaning capacity, and the residual time of the soil
contaminants is relatively high. The research and practical experiences
described in this paper refer to those terrain surfaces affected by the
chemical pollution from the industrial waste storage zones. The activities
in the industrial sector exert a continuous pressure upon the soil through:
pollutant emissions, landfills - these can increase the soil acidity,
overfertilize it, accumulate various types of heavy metals in it, such as
Ph, Cu, Zn, Cd, all of these lowering the soil quality. Experimental results
obtained performing studies and researches conducted in two metallurgic
industry landfills are presented as follows. We assayed heavy metal
concentrations and other indicators specific to this area through laboratory
atomic absorption spectrophotometric methods as well as other analysis
methods. The optimal solution for the elimination of the specific pressures
exerted on the environmental factors by these facilities can be done not
only putting to good use the valuable materials within the waste content,
but also reintroducing the surfaces occupied by landfills into the economic
circuit through ecological reconstruction works. Keywords: soil, heavy metals, landfills,
automonitoring, contaminated sites.
Abstract A new iron-based promoted catalyst,
designed to be charged into the industrial radial–axial flow reactor, was
investigated in an Accelerated Surface Area and Porosity
Analyser-Micrometrics ASAP 2020. The primary experimental curve was
identified as an adsorption/desorption isotherm of type IV with H1
hysteresis. The main textural parameters (surface area, pore
volume/porosity, pore size distribution (PSD) and average pore diameter)
have been assessed usind six calculation methods: Langmuir model, BET
equation, Single point method, t-Plot method, BJD adsorption, and BJH
desorption. The surface area was between 12.33 m2/g (single point method)
and 17.48 m2/g (Langmuir model). From BET surface area the t-Plot has shown
that about 9% was due to micro-pores. The average pore diameter derived from
BJH adsorption model was of 16.72 nm. The determined parameters predict a
better activity of the new catalyst compared to the traditional one.
Waste Management and Pollution Prevention. I. Waste
Electrical and Electronic Equipment
ANA-MARIA SCHIOPU, MARIA GAVRILESCU
pages 21 - 35
Abstract Some aspects regarding waste electrical and
electronic equipment collection and recycling are highlighted in the paper.
Waste electrical and electronic equipment recycling is considered important
subject not only from the point of waste management, but also from the
recovery of valuable materials. European and national regulatory issues are
revealed and then actual features of WEEE management are presented,
considering Iasi city as a case study. Waste Electrical and Electronic
Equipment (WEEE) Directive was shortly refereed along with the related
Directive on Restrictions of the use of certain hazardous substances in
electrical and electronic equipment (RoHS). In Romania, Governmental
Decision 448/2005 is presented as the main regulatory act concerning WEEE.
For the management of waste electrical and electronic equipment,
manufacturers may be associated or can act as individual organizations
(according to Ministry Order 1225/2005 for approval of the procedure and
criteria for evaluation and authorization of collective organizations in
taking over responsibility for achieving annual targets for the collection,
reuse, recycling and recovery of waste electrical and electronic equipment).
In Iasi City, the door-to-door collecting system was successful, as well as
WEEE collecting at established points.
Chlorophenols Degradation – an Overview
CAMELIA SMARANDA, LAURA–CARMEN APOSTOL, FLORENTINA–ANCA
CĂLIMAN, MARIA GAVRILESCU
pages 37 - 48
Abstract The degradation of chlorophenols has been
shortly reviewed in this paper, including the combined electrochemical
reduction and oxidation, photochemical transformations in aqueous solutions
as well as biodegradation. Dechlorination is the first critical step in the
bacteria degradation of many chlorinated pollutants. The
chlorophenols-degrading microbes, with special emphasis on degradation
mechanisms, were highlighted. The mechanism of biodegradation depends on the
process conditions. Under the aerobic condition, degradation of mono- and
dichlorophenols was shown to be initiated by oxygenation. Anaerobic
biodegradation of chlorophenols occurs by reductive dechlorination, a
process by which chlorines were replaced with hydrogen. Some systems for
buodegradation were presented, as well.
Surface Tension and Excess Thermodynamic Properties of
Binary Mixtures Isopropanol–Water and n-Butanol-Water
GABRIELA LISĂ, DANIELA APREUTESEI, CĂTĂLIN LISĂ
pages 49 - 54
Abstract Surface tensions, σ, of liquid binary
mixtures iso-propanol – water and nbutanol – water were measured at 294.15,
304.15 and 311.15 K and normal atmospheric pressure. Based on these
experimental data we calculated the excess surface tension of the studied
systems. The results were fitted to a Redlich-Kister type polynomial
relation, and the corresponding parameters have been derived. The results
are discussed in terms of molecular interactions
Characterization of Layered Double Hydroxides as a
Delivery Vehicle for Oxacillin
SOFRONIA DRANCA, GABRIELA CARJA, N. APOSTOLESCU
GABRIELA CIOBANU, I. BALASANIAN
pages 55 - 62
Abstract Intense research interests have carried on
layered double hydroxides (LDHs) mainly due to the ability of the anionic
clay matrices to incorporate, to transport and targeted various bio–and
organic molecules. The ensemble: clay matrix – therapeutic agent is able not
only to join the properties of its components but also to develop its own
characteristics in a single material. We present in this work the controlled
synthesis and physical–chemical characterization of a new drug delivery
system based on oxacillin incorporated in the layered matrix of
hydrotalcite-like anionic clays. The structural properties of the drug–clay
assembly are described by using the results of X-ray diffraction (XRD),
infrared spectroscopy (FTIR) and thermal analysis (TG-DTA). The antibiotic
release from the clay matrix points out that a rapid release of the drug
during the first 30 min is followed by a more sustained one. The results
suggest that the oxacillinlayered double hydroxides can be used as an
effective drug delivery system with improved drug stability.
The Biodegradation of Some Composite Structures in the
Presence of Some Biocides Systems Based on Natural Products
ELENA UNGUREANU, OVIDIU UNGUREANU, VALENTIN I. POPA
pages 63 - 72
Abstract The paper analyses the biodegradation of
some natural composite structures represented by fir and beech wood,
investigated in both treated and untreated state, on the surface of the
samples. The treatment has been applied through brushing in both directions.
The products used for the treatment, in different concentrations (1%, 3%,
5%), are both of organic (unmodified and modified straw lignin, furan resin)
and inorganic origin (copper chloride and copper–ammonia solution).
Biodegradation, followed in several variants, selected according to their
aspect, illustrate the standard classes of biological risk to the biological
attack. The biodegradation and the bioprotection levels were tested in
different environments, namely indoors, outdoors, buried in the soil (in the
absence of plants) and in a soil cultivated with bean plants (Vera variety).
The role of these tests was to establish the efficiency of the treatment
applied on the wooden material depending on the type of the product used.
The main parameters followed in these experiments were: mass loss and
wetting angle.
Synergistic Reactive Extraction - Alternative for
Carboxylic Acids Extraction
LENUŢA KLOETZER, ANCA–IRINA GALACTION, DAN CASCAVAL
pages 73 - 87
Abstract Extraction of the carboxylic acids using
one extractant or diluent is costly and laborious without obtaining high
extraction efficiency. The extraction systems with combined extractants and
diluents had lead to major increase of extraction yield compared with
systems using single extractant or solvent. This paper presents a review of
the extraction studies of some carboxylic acids (lactic, succinic, propionic
and tartaric) with synergistic combinations. The influence of different
extractants and diluents indicated that usually synergistic reactive
extraction with mixed tertiary amine and polar solvents leads to high
extraction efficiency for the studied acids. Also, high extraction
efficiency was obtained for the system with mixed tertiary amine with long
chain / tertiary amine with short chain and for mixture of polar and non-
polar diluents. The study of extraction mechanism and characterization of
different components of the extraction system (carboxylic acid, diluents,
extractants) represents an important step for designing the optimal
synergistic reactive extraction system for a given solute.
2008, Volume
LIV (LVIII), Issue 3
Sources of green energy in pulp and paper industry. I.
Pulp mill solid wastes
D. GAVRILESCU, GR. CRĂCIUN, GH. DUŢUC
pages 7 - 16
Abstract Pulp and paper industry expresses an
interest in adapting and integrating advanced biomass energy conversion
technologies into its mill operations. Industrial adoption of these new
technologies has the potential for higher efficiency, lower capital cost,
and safer operation than conventional operations that burn fossil fuels for
energy. Incineration with energy recovery has the advantage of hygienic
disposal, volume reduction, and the recovery of thermal energy by means of
steam or super heated water that can be used for heating and power
generation. Pulp mills generate various quantities of energy-rich biomass as
wastes, depending on technological level, pulp grades and wood quality.
These wastes are produced in all stages of the process: wood preparation,
pulp manufacture, chemical recovery. Energy recovery from wastes of
different origin, has become a generally accepted alternative to their
disposal. The paper reviews the current state and tendencies in using as a
fuel of solid wastes generated in pulp mills. A description of
biomass-derived wastes regarding their opportunity to be used for energy
recovery is presented. The heating properties of wood wastes as a fuel are
also presented.
Contributions regarding reducing of the atmospheric air
pollution by retaining the gas pollutants from the process of sulphur
extraction
A. GREC
pages 17 - 26
Abstract The present work proposes to bring a
solution regarding the problem of SO2 şi H2S
atmosphere pollution, extremely toxic gases resulted from the process of
extracting the technical sulphur from the bedding of E. M. Călimani. The
research has started from laboratory stage (lab experiences of the gas
absorption methods) being consequently extended to pilot scale and in the
end to the building of the presented industrial installation. The
installation was built and experienced in the above mentioned technological
flow, with the following performances: decrease of the pollution level
through the withhold of the SO2 and H2S in absorbant
solution (the iron – soda method), the retain efficiency values being in average ηabSO2 = 72,69% and ηabH2S
= 61.06%. At a production of around 150 – 200.000 t/year extracted ore
results a decrease of the SO2 and H2S emitted in the
atmosphere of around 1,565.8 kg/year SO2, respectively 412.62
kg/year H2S, thus considerably reducing the pollution of the
influence zones and the risk of the nearby population diseases. Besides the
ecological aspect, they can benefit from economic advantages such as: fuel
saving up to 2,5 –3,5 tones fuel oil/a day (through increasing the energy
efficiency) and last but not least, obtaining the secondary product, Na2SO3,
around 9,5 t/year, used as raw matter in other industrial processes
(medicine, leather goods, photographic industry, etc.). Another advantage is
the simultaneous retaining of the two pollutants (SO2 şi H2S)
from the pollutant emitted. We consider that the method presented hereby,
although a small step in the horrendous fight with the destructions provoked
by pollution, consists in a "step forward" and can be applied as well in
other pollutant industrial processes.
A survey of thermal behaviour of some hetero-organic
polymers with controlled architecture
V. HURDUC, G. LISĂ, M. LUNGU
pages 27 - 38
Abstract The present research is focused on thermal
analysis in dynamic conditions of some new polymers based on polysiloxanes
grafted with a binary copolymer based on styrene – butyl acrylate and a
tertiary copolymer based on styrene-butyl acrylate–methyl methacrylate.
Thermal analysis in dynamic conditions (TG, DTG and DTA) was performed and
STARe software was used. The results confirm a high thermal stability up to
350°C. The mechanism of degradation is radical by depolymerisation and
transfer of intermolecular chains, the degree of depolimerization being
determined by the nature of the components.
Aspects concerning some biocides systems based on
natural aromatic compounds and their copper complexes
E. UNGUREANU, A.-M. CĂPRARU, V. I. POPA
pages 39 - 46
Abstract This work shows the results regarding the
biological stability of the birch veneer in the presence of some natural
compounds having different levels of chemical modification and of their
copper complexes. The products used for the treatment in a 5% concentration
in 0.1N ammonia solution have been: the chemically modified/unmodified straw
lignin, along with copper compounds (copper chloride and copperammonia
solution) unbound or combined with natural compunds. The biostability tests
have been perfomed by burying the samples treated with the mentioned
products in the soil. The level of biostability has been estimated through
burial in the soil for six months and through the values of the wetting
angle. The obtained data have emphasized that the effectiveness of the
applied treatment depends on the character of the utilized product, on the
modifying method and on the capacity of complexing with the copper ions.
Decorative protection of carbon steel through black
finishing at low temperatures. 1. Technological parameters
L. LAZĂR, F. BANDRABUR, A. SZÉP
pages 47 - 58
Abstract Black finishing is a decorative-protecting
process of the carbon steel based supports, prepared from alkaline
solutions, in the presence of some oxidizing agents. The achieved thin film
may be bright or lustreless, exhibiting a colour that varies from black to
brown due to the formed iron oxides. The technologic regime changes in
function of the nature and composition of the solution, as well as the
nature and the surface state of the metallic support. In this paper, it was
studied the influence of the factors that may affect the quality of the thin
film formed by black finishing of the steel at temperatures lower than
100°C, avoiding thus the vaporization of water and the concentration of the
solution. The quality of the oxides thin film was investigated considering
the nature of the metallic support and the quality of mechanical finishing
previously to black finishing process, the nature and quality of black
finishing solution (unsaturated /saturated with iron ions); temperature and
duration of the process; solution hydrodynamic regime. It was demonstrated
that the oxides thin film formed through black finishing of OLC meets the
quality requirements if the process is operated by stirring of the solution
for 35 minutes at temperatures between 85…88°C.
Qualitative and quantitative aspects of voltammetric
behaviour of the Cd2+ ion
D. BEJAN, A. DUCA
pages 59 - 68
Abstract The present paper deals with qualitative
and quantitative study on the voltammetric behaviour of the Cd2+
ion (CCd2+ = 10-6…5·10-6 mol/L) on
different electrodes: carbon paste electrode (CPE) and carbon paste
electrodes modified with cation exchanger (NAFION) either deposited as thin
film on the surface (NAFION coated carbon paste electrodes – NC-CPE) or
entrapped within the carbon paste (NAFION entrapped carbon paste electrode –
NE-CPE). The following parameters have been taken into account: the
electrode type, the Cd2+ ion concentration, the concentration
time by electrodeposition and the ion-exchange pre-concentration time at a
constant potential (Econc. = -1.1 V and -1.3 V) by using a non-complexing
support electrolyte (10-1 mol/L acetate buffer, pH = 4.5). The
obtained cyclic and ion-exchange voltammograms were supple, showing clear
anodic and cathodic peaks. The process electrochemistry is quasi-
reversible. The intensity of the anodic current, as a signal of analytical
interest, increases rather proportionally with the increasing concentration
of Cd2+ ion (within the concentration range under consideration)
and concentration time (no longer than 5 minutes) and depends on the
electrode nature. The method can successfully be applied for estimating the
low Cd2+ concentration in waters, animal and vegetal tissues as
well as in food.
Quality initial analysis of the ground waters of the
metallurgical platform area in Cordun
E.-D. CÂRLIG, M. MACOVEANU
pages 69 - 80
Abstract The goal of the present article is the
study of the ground waters of the Cordun area – the waste dump. It is about
the characteristics of the analyzed site (general considerations, climate
elements, temperature and precipitations, hydrological elements, region
hydrogeology) and at the establishment of the pollution rate of the ground
water in the studied area (the pressures to which the water body is forced,
experimental data, results and debates). The conclusion drawn at the end of
this article is that the studied area presents a significant pollution rate
of the ground waters.
Studies regarding onto solid materials based on coal
ashes
D. ŞUTEU, C. ZAHARIA
pages 81 - 90
Abstract Some batch sorption experiments were
carried out to remove Methylene Blue cationic dye from aqueous systems using
industrial coal ash and other solid materials based on ash and lime as a low
cost sorbent (e.g., Ads 1h, Ads 2h, Ads
3h and Ads 4h). To establish the most suited type of solid materials
to be used as sorbent for this dye, the data were analyzed using the
Langmuir, Freundlich and Dubinin-Radushkevich models for the sorption
isotherms. The results of this experimental study show that all tested solid
materials have a limited capacity for dye molecules uptake but we also
observed that the sorbent named Ads 1h presents the best values for the
sorption capacity.
Voltammetric study on the Cd2+ - Cu2+ and Cd2+ - Pb2+
Binary Systems
D. BEJAN, A. DUCA
pages 91-104
Abstract The present paper is aimed to report the
qualitative study on the voltammetric behaviour of the Cd2+ - Cu2+
and Cd2+ - Pb2+ binary systems in slightly acid (10-1mol/L
acetate buffer, pH = 4.5) solutions of 10-6…10-4 mol/L
concentrations, on carbon paste electrode (CPE) and CPE electrodes modified
with NAFION (NAFION coated carbon paste electrode: NC-CPE, and NAFION
entrapped carbon paste electrode: NP-CPE). The influences of ion
concentrations, the ionomer presence within the electrode material, and the
interferences of the Cu2+ and Pb2+ ions on the Cd2+voltammetric
behaviour were followed. Qualitative and quantitative information on the Cd2+
voltammetric behaviour on the same electrodes and under similar experimental
conditions is to be found in a previous paper [19]. The obtained
experimental results are in good agreement with literature data.
2008, Volume
LIV (LVIII), Issue 4
Airlift Bioreactors
ROXANA BALTARU, ANCA-IRINA GALACTION, DAN CAŞCAVAL
pages 9 - 28
Abstract Biotechnology is currently a rapidly
expanding field of interdisciplinary research. This is evident from the
development of a large number of new types of bioreactors. The traditional
stirred tank bioreactor is no longer a
priori the standard bioreactor, mainly because of economic
considerations and the intrinsic properties of the bio-phase used. Air-lift
bioreactors are a relatively new type of fermentor, offering several
advantages for large-scale aerobic bioprocesses, for animal and cell culture
in particular. In many cases, the immobilized biocatalysts or microorganisms
are used. This paper presents a general approach of the pneumatic
bioreactors, and of the airlift ones in particular, from the viewpoint of
the transfer processes and of the main domains in which they could be use.
Keywords: pneumatic bioreactor, airlift bioreactor,
oxygen transfer, hydrodynamics
The Evolution In Time Of The Quality Of Ground Waters
From The Area Of The Metallurgical Platform Cordun
ELENA – DOINITA CARLIG, MATEI MACOVEANU
pages 29 - 42
Abstract This article is intended to study the
quality in time of the ground waters from the region Cordun – the waste
dump. It refers to the characteristics of the location studied (climate
elements, temperature, precipitation, the hydrogeology of the region),
establishing the degree of pollution of the ground water from the area
studied (the pressures the water surface has been subject to in time,
experimental data, results and discussions). The conclusion of this article
is that the area we studied presents a significant pollution of the ground
waters.
Sources Of Green Energy In Pulp And Paper Industry.
Part II: Paper Mill Solid Wastes
DAN GAVRILESCU, GRIGORE CRACIUN, GHEORGHE DUTUC
pages 43 - 54
Abstract Paper mills generate various quantities of
energy-rich biomass as wastes, depending on technological level, and paper
grades. These wastes are produced in all stages of the process: pulp
processing, paper manufacture, recycled paper processing, waste water
treatment. Energy recovery from wastes of different origin, has become a
generally accepted alternative to their disposal. The paper reviews the
current state and tendencies in using as a fuel of solid wastes generated in
paper mills. The heating properties of rejects from recycled paper
processing, paper sludge, and low- quality recovered paper grades are also
discussed. Some aspects of emission of greenhouse gases (GHG) are also
presented. Keywords: paper mill, solid wastes, rejects, recovered
paper environment
The Viscosity and Density of The Aqueous Solutions Used
For The Absorption Accompanied By Chemical Reaction
MARIA HARJA, LACRAMIOARA RUSU, MARINELA BARBUTA
pages 55 - 62
Abstract This paperwork based on a large number of
experimental data suggest mathematical relations obtained by the regress
with a view to calculate the viscosity the solutions like Na2SO4
(sodium sulfate), KOH-K2CO3 (hydroxide caustic potash-
carbonate potash) and KHCO3-K2CO3
(carbonate – bicarbonate potash). For potash and bicarbonate potash we
establish mathematics relations of densities. By calculating the viscosity
with these equations the maximum error is 3.93%, and for the density the
error is below 2%.
Corrosion Behaviour Of A HSLA Steel As A Function Of
Immersion Time In Natural Seawater
MARIA LUNGU, NECULAE. AELENEI, DANIEL MARECI, ROMEO
CHELARIU
pages 63 - 74
Abstract The corrosion behaviour of a high strength
low-alloyed (HSLA) steel in seawater has been studied as a function of
immersion time over a period of 90 days. Electrochemical and microscopic
studies relieve a general no uniform corrosion, the corrosion rate depending
on immersion time. The corrosion product is a porous and not very protective
layer of iron oxy-hydroxide. A maximum protection there was pointed out for
the sample held 45 day in seawater. The linear polarization curves point out
that the thermodynamic tendency of corrosion is higher when the sample is
maintained in natural aerated seawater. The cyclic polarization curves
reflect a direct dependence between corrosion rates and applied over
potential. The slopes of the linear portions depend sensible on immersion
time in seawater and generally reflect the same tendency of variation as the
instantaneous corrosion currents Keywords: HSLA steel, seawater corrosion, corrosion
potential, linear polarization, cyclic polarization
Biophysico-chemical processes of heavy metals in soil
environments
VASILE LUCIAN PAVEL, RALUCA MARIA HLIHOR, FLORENTINA
ANCA CĂLIMAN, MARIA GAVRILESCU
pages 75 - 87
Abstract Considering the complexity of soils and the
interactions generates between soil components and other elements, like
heavy metals coming from polluting sources, this paper reveals some aspects
referring to biotic and abiotic interactions of metals with soil mineral and organic
colloids, which have a major impact on the physics, chemistry, and biology
of soil and surrounding ecosystems. The cleanup of soils polluted by
hazardous metal contaminants has become a matter of urgent public concern
since metal contaminants in soils affect their production potential and
biodiversity. Sorption is considered as a major process controlling the
partitioning of metals between the aqueous and solid phases in soils. As a
method for remediation, biosorption is based on the fact that large
concentrations of metals are frequently associated not only with living
microbial biomass but also with dead cells, for example microbial
biopolymers that have the ability to bind metals. Keywords: bacteria, biosorption, contamination,
interfacial interactions metals, organics, remediation
New Composite Materials Used As Adsorbents For Water
Vapours
STELIAN PETRESCU, MARIUS SEBASTIAN SECULA
pages 89 - 96
Abstract Several investigations approaching the
achievement and characterization of some composite adsorbent materials for
water vapours are presented in this paper. Thus, eight new types of
composite materials were synthesized by impregnating silica gel, active
carbon and alumina respectively with aqueous solutions of calcium chloride
or lithium bromide. Then, the composite materials were characterized using
high-accuracy equipment. Keywords: composite adsorbent material, water vapour
adsorption, silica gel, active carbon, alumina.
New Complex Compound Of Cu(Ii) With Ligand Derived From
1-(5-bromo-2-hydroxy-4 methyl phenyl)-2 naphtylsulphanyl)-ethanone
DOINA SIBIESCU, IOAN ROSCA, TURCUMAN (ANTIGHIN) SIMONA
pages 97 - 104
Abstract In this paper it is presented the obtaining
reaction of a new complex from interaction of Cu(II) with 1-(5-bromo-2-
hidroxy-4 methyl phenyl-2 naphtylsulphanyl)-ethanone in molar ratio of 1:2
and it's characterization by different methods as: chemical analysis,
thermo-gravimetry, IR absorption spectroscopy, RES, and X-ray diffraction.
The new complex crystallizes in the triclinic system with hexacoordinated
central atoms Cu(II) with octahedral structures. The obtaining reaction of
the new complex can be used in gravimetric determination of Cu(II) with an
error of ± 0,31%. Keywords: Cu(II), 1-(5-bromo-2-hidroxy-4 methyl)-2
naphtylsulphanyl)-ethanone, reagent of precipitation
2007, Volume
LIII (LVIII), Issue 1-2
Analytical evaluation of the composition - quality
correlation in wines
D. BEJAN
pages 7 - 18
Abstract The aim of this paper is to accomplish a
chemical-analytical characterization of several wine samples (white, red,
rose) obtained under different technological conditions as well as ascertain
the composition-quality correlations. The following parameters were taken
into account: pH, rH, redox potential, electrical conductivity, content of
tanning compounds, concentration of macro- (Na, K, Ca) and micro- (Fe)
elements. As made evident by the experimental run, all the samples under
study showed normal chemical characteristics in agreement with literature
data. Different modifications (clearness, colour, taste) in function of the
wine type, were noticed along the preservation time. The wines of high iron
content, where Fe3+ percentage is higher, with lower acidity and
inadequately treated with SO2, showed the most-significantly modifications.
The colour variations in time were estimated qualitatively and
quantitatively by means of VIS molecular absorption spectra, both with white
and red wines.
Studies on the kinetics and the mechanism for the
synthesis process of some coordination polymers of Cr(III).
I. ROSCA, D. SIBIESCU, G. CARJA
pages 19 - 24
Abstract The paper presents the mechanism and the
kinetics of the reactions between the Cr(III) acetyl-acetonates with ethyl-
naphtyl-phosphinic, ethyl-naphtyl-thiophosphinic and
ethylnaphtyl-dithiophosphinic acids. The possible reaction mechanism assumes
the substitution of acetyl-acetonate ligands with the anions of the reacted
acids. In the beginning we assumed this process as a first order
nucleophilic substitution (SN1); this corresponds to the lowering of the
central atom's coordination number with a unity, due to the removal of one
ligand of the CrAcac3 molecule. Next step is to study this process as a
second order nucleophilic substitutions (SN2); this means the increasing the
number of the ligands through the coordination of the substituted ligands to
the central atom followed by the quick elimination of the substituted
ligand. The obtained results point out that the mechanism of the studied
reactions is of type SN2.
The Zn(II) extraction in peg-based aqueous two-phase
systems using tiocyanate ions as extracting agents.
L. BULGARIU, D. BULGARIU
pages 25 - 32
Abstract The Zn(II) extraction behaviour was studied
in aqueous polyethylene glycol (PEG)- (NH4)2SO4 two-phase system in presence
of SCN- ions, as a function of several experimental parameters. For a system
prepared by mixing equal volumes of 40% (w/w) PEG (1,550) with 40% (w/w)
(NH4)2SO4 aqueous solutions, Zn(II) remain almost exclusively in the
salt-rich phase. The variation of salt stock solution pH does not change too
much the Zn(II) extraction efficiency. The addition of tiocyanate ions to
these systems determined a quantitative Zn(II) extraction to the PEG-rich
phase. The Zn(II) extraction efficiency depends on the salt stock solution
acidity and on the concentration of tiocyanate ions added into system.
Coordination compounds of Ni(II) tetracoordinates with
organic ligands
M. FLONDOR, I. ROSCA, D. SIBIESCU
pages 33 - 38
Abstract The synthesis and study of some
coordination compounds derived from the interaction of Ni(II) with
2-(4-chloro- phenylsulfanyl)-1-(2-hydroxy-3,5-diiodo-phenyl)-ethanone (L1),
1-(5-bromo-2-hydroxy-4-methyl-phenyl)-2-4-chloro- phenylsulfanyl)-ethanone
(L2) and
2-(4-chloro-phenylsulfanyl)-l-(3,5-dibromo-2-liydroxy-pbenyl)-ethanone (L3)
is performed. The applied methods in this study are: chemical analysis,
IR-absorption spectra and ESR spectroscopy. Based on experimental data and
on literature indications, the structural formulas of these compounds are
assigned.
Mathematical modelling of anodic processes with soluble
electrode in diffusional regime.
M. S. SECULA, S. PETRESCU
pages 39 - 52
Abstract A mathematical model valid in diffusional
regime for anodic dissolution processes by rotating disk technique is
proposed. The model was used to determine the distribution of copper ion
concentration in the diffusion boundary layer at the dissolution of copper
disks in copper sulphate solutions. Copper disks of 0.01 m in diameter,
angular speed values situated in 10...3,000 rot/min range, copper ion
solution concentration C∞Cu2+ from 1.587 to 62.5 g/L, and temperature
between 20° and 60°C were considered in calculations. Based on the
mathematical model the copper anodic dissolution rate and limiting current
density were determined. The mathematical model obtained was validated using
Levich equation.
The activity of a heterogeneous photo- fenton catalyst
at different thermal aging regimes
B. IURASCU, I. SIMINICEANU, M. VICENTE
pages 53 - 58
Abstract A new photo-Fenton catalyst has been
manufactured from synthetic layered clay laponite (Laponite RD) by the
pillaring technique Eight different catalyst samples were prepared: four
without thermal aging (WTA), calcined at 523 K, 623 K, 723 K and 823 K, and
other four with thermal aging (TA), calcined at the same temperatures. The
samples were characterized by XRD and SEM/EDS techniques, and through the
bulk chemical analysis. The activity of catalyst samples was evaluated in
the phenol degradation by the photo-Fenton process, using an aqueous
solution of 0.1 mM concentration in phenol by the phenol conversion (XPh)
and phenol mineralization (XTOC) versus reaction time in the presence of 5
mM H2O2, 1 g/L catalyst, pH = 3, and 303 K. A new kinetic model has been
proposed and tested, and the corresponding two kinetic constants have been
identified. The other operating factors have been kept constant at optimal
values previously found: 5 mM H2O2, 1 g/L catalyst, pH = 3, and a
degradation temperature of 303 K. The activity of each catalyst sample was
evaluated through the apparent first order rate constant derived from the
experimental kinetic curves. The best results were obtained with the TA-623
catalyst.
Preparation and characterization of mgal layered double
hydroxides containing interlayer organic p-methoxybenzoate.
A. BOTOMEI, E. DUMITRIU, V. HULEA, A. NASTRO
pages 59 - 66
Abstract Layered organic-inorganic hybrid
composites, containing anisic acid (AA) as guest within the interlayer
gallery of MgAl-layered double hydroxide, were prepared by three different
synthesis techniques: (i) direct synthesis by coprecipitation of the metal
nitrates and sodium AA, (ii) direct ion exchange of the LDH nitrate with the
organic anion and (iii) by the structure reconstruction of the LDH
previously calcined at 500°C. In all the cases, direct evidence for the
intercalation is obtained from XRD data, when a noticeable increase of the
interlayer distance was observed. Thus, powder X-ray diffractograms of these
materials show that the basal spacing of MgAl-layered double hydroxide with
carbonate as the counter anions expanded from 7.71 to around 18 Ain the
resulting hybrid material. Also, IR studies show that the absorption bands
of the resulting materials correspond to both the characteristic functional
groups of the host and the guest. Therefore, when the two results are taken
together, the expansion can be evidently attributed to the intercalation of
the AA anions in the inorganic interlamella for the formation of the hybrid
material. The intercalation of AA is also confirmed by thermogravimetric
analysis (TG).
Synthesis of 1-[n-(m-nitrobenzoyl)-a-l-glutamil]- 5’,6’-dimethyl-benzimidazole and its immobilization by esteric bonds
on polysaccharides.
D. DUMITRAS, M. POPA, V. SUNEL
pages 67 - 84
Abstract This paper studies the synthesis and the
dicyclohexyl carbodiimide activated immobilization reaction through
ester-type covalent bonds of an oxazolone derived from
N-(m-nitrobenzoyl)-L-glutamic acid, ring opened with 5,6-dimethyl-
benzimidazole on polysaccharides (gellan, xanthan and alginic acid sodium
salt). The maximal efficiency of coupling reaction was obtained for the
active principle-gellan system. For this system was realized an experimental
program varying the following parameters: molar ratios DCCI/medicament and
medicament /gellan as well as the reaction duration. To achieve a maximum
content of biologically active product in immobilization compounds, the
parameters' highest values are used. The kinetics of the drug's release from
the supports are studied under alkaline hydrolyse conditions.
Slurry reactor for heterogenous photocatalytic
degradation of reactive orange 16.
A. F. CĂLIMAN, A. ANTONIADIS, I. POULIOS, M. MACOVEANU
pages 85 - 94
Abstract The degradation of textile dye Reactive
Orange 16 by the use of heterogeneous (TiO2- mediated) photocatalytic method
under artificial irradiation has been studied into a slurry photoreactor
with recirculation of suspension. Influence of few different conditions was
first tested in order to find the proper amounts of dye and catalyst
concentrations, as well as of the oxidizing agent, to be used for the
further experiments. Effect of reused catalyst was also described. Electric
energy consumption was calculated and compared for two different systems.
Chemischer Zerfall von Alten Kollagenträgermaterialien.
N. MELNICIUC PUICA, D. DOROHOI, A. CECAL
pages 95 - 102
Abstract This paper deals about collagenic material
chemical degradation. Atmospheres rich in sulphur dioxide have a proven
noxious influence upon the lastingness of old parchment and leather.
Absorption of water vaporous vs. time exposure for different samples
(exposed to different concentrations in SO2 during different periods of
time) was studied. Experimental results were processed according to
polynomial models and correlation between variables was graphically
represented.
Some aspects regarding the use of near infrared
analysis of Apple fruit
A-S. SERBAN, E. BOBELYN, B. NICOLAI, M. NICU
pages 103 - 108
Abstract For the quality measurements, post-harvest
apples (Halos dornestica Borkh.) of different varieties and origins were
studied: Golden (Belgium, South Africa, Italy and France), Royal Gala
(Chile, Argentina and New Zeeland), Jonagold (Belgium - different
producers), Braeburn (South Africa, Chile, France and New Zeeland), Pink
Lady (Chile, Argentina, France, South Africa and New Zeeland) and Fuji
(China). A NIR spectrum was collected from the red and green side of each
apple and the reference quality parameters Magness Taylor firmness and
soluble solids content (SSC) were measured destructively. The spectral data
were analysed by means of partial least squares regression. The best
correlation for the sugar content was obtained in Golden apples (RMSEP =
0.63°Brix) and the best correlation for firmness was observed in Braeburn
apples (RMSEP = 6.35 N). The measurements will continue on other apples
origins in order to obtain a highest variability of the experiment.
On lignin reactions in oxygen based kraft pulp
bleaching.
A. C. PUITEL, A. BORDEIANU, D. GAVRILESCU
pages 109 - 122
Abstract Kraft pulp bleaching consists both in
delignification and removal of chromophores. Lignin removal represents the
most important objective in bleaching, since lignin is the most important
contributor to the cellulose kraft pulp colour. Industrial scale bleaching
is performed with the help of chlorine (Cl2), chlorine dioxide (ClO2) and
oxygen based bleaching agents - molecular oxygen (O2), hydrogen peroxide
(H2O2), ozone (O3) and peracids. Chlorine bleaching has been considered
polluting, since it has produced large quantities of chlorinated organics.
Chlorine has been replaced with chlorine dioxide, which has the advantage of
being highly selective delignifying agent. The disadvantage of using ClO2
for bleaching and delignification, besides production costs for ClO2, is
that chlorinated organics are still produced, even if at lower levels. This
is the reason why, from an environmental point of view totally chlorine free
(TCF) bleaching seems more attractive. Lignin reactions with the oxygen
based bleaching agents are the primary condition for lignin fragmentation
and further removal from the ligno-cellulosic complex. Lignin fragmentation
is a direct result of species present in the oxygen based bleaching systems
including ozone (O3), molecular oxygen (O2), superoxide radical (O2.-),
hydrogen peroxide (H2O2), perhydroxyl radical (HOO.) and hydroxyl radical
(HO.). The action of oxygen based delignification and bleaching reagents
over lignin involves: hydroxylation, hydroxyl substitution, side chain
oxidation, side chain cleavage, cleavage of the ether linkage, aromatic ring
cleavage, and oxidative coupling. Oxygen based bleaching is a very sensitive
process towards the presence of 'transition metal ions, which can catalyse
the formation of hydroxyl radical, responsible for cellulose degradation
during bleaching.
Aspects of the impact on the environment induced by
industrial activities in Vaslui City 2. The impact owed to S.C. ILVAS S.A.
VASLUI.
L. CEZAR, M. NICU, C. HUŢUPAŞ, F. APOSTU
pages 123 - 130
Abstract In the context in which the evaluation of
the impact of the industrial activities on the Environment became a main
objective of the Environmental Politics, the discovery of more objective
methods of the impacts quantification is highly requested. This paper is
part of a cycle which stands for the thoroughness of some ways to make the
impact evaluation more objective. It studies the problems specific to a milk
industry unit and explains the impact up and down the river.
A novel computer-assisted approach using geographic
information system and digital image analysis to estimate differences in
concentrations of heterogeneous dispersed particles in solutions.
A-I. PETRIŞOR, A. W. DECHO
pages 131 - 136
Abstract Quantification of heterogeneous dispersed
particles in solutions or within a matrix has been a challenging task,
especially those involving microscopic particles. An approach was developed
here, that utilizes Geographical Information Systems (GIS) and digital image
analysis, coupled with confocal scanning laser microscopy (CSLM) to estimate
concentrations of microscopic particles (fluorescent polymeric microspheres
and bacterial cells). We propose that the area occupied by particles within
each image can be used as an alternative to traditional counting to estimate
concentrations of homogeneously sized particles. Results indicate that the
new approach performs as well as the traditional one, and represents the
only methodology in special situations.
CONSTANTIN CALISTRU in memoriam
by I. SIMINICEANU
pages 137 - 138
2007, Volume
LIII (LVII), Issue 3-4
Densities, viscosities, refractive indices and excess
thermodynamic properties of binary mixtures propionic acid –toluene
G. LISA, D. APREUTESEI, C. LISĂ
pages 7 - 14
Abstract Density, viscosity and refractive index
have been experimentally determined for binary liquid mixtures toluene +
propionic acid at 292.15, 299.15, 305.15, 311.15 and 317.15 K and normal
atmospheric pressure. Based on these experimental data, we calculated the
excess thermodynamic properties: the excess molar volume, viscosity
deviations and the refractive indices deviation of the studied system. The
obtained results have been discussed and interpreted in terms of the type
and nature of the specific intermolecular interactions between the
components.
Mass transfer study at gas separation by adsorption.
S. PETRESCU, I. MĂMĂLIGĂ, I. GALBEN
pages 15 - 24
Abstract A mathematical model for the gas—solid
adsorption in fixed bed of solid. in dynamic regime, is proposed. This model
is valid for isothermal adsorption and allows to calculate the distribution
of the water concentration in solid and gaseous phases as a function of time
and the fixed bed height. On the basis of proposed model and of the
experimental values of mass transfer coefficient, the water content in
silica gel spheres was calculated. It was also presented the distribution of
the water concentration on the height of a fixed bed of adsorbent at
different times of adsorption. The obtained results allow to elucidate the
kinetics of adsorption in a fixed bed and to calculate the local sorption
rate.
Equilibrium and diffusion close to glass transition
temperature in toluene – polystyrene systems.
I. MĂMĂLIGĂ
pages 25 - 32
Abstract The results of an experimental
investigation concerning the estimation of phase equilibrium and diffusion
coefficients of toluene in polystyrene close the glass-transition
temperature is presented. From successive differential sorption experiments
it was found that close the glass-transition temperature "anomalous"
non-Fickian diffusion of organic solvents in polymers occurs. This behaviour
can be caused by the difference between the time scale for molecular
reconfiguration (relaxation time) and the time scale of diffusion.
Investigation of the kinetic parameters of the VOCs
oxidation process on SCR-DeNOx commercial catalyst. 2. Estimation of
apparent activation energy.
L. LAZĂR, H. KÖSER, I. BALASANIAN, F. BANDRABUR
pages 33 - 42
Abstract In this paper, the study concerning the
kinetic of the VOCs oxidation process in the presence of the SCR-DeNOx
(0.53% V2O5) commercial catalyst is continued in order to establish the
dependence between the temperature and effective kinetics, as well as to
assess the apparent activation energy of the reaction. In a previous paper,
the experimental data, which allowed the assessment of the reaction order
and effective rate constant for the process of benzene catalytic oxidation,
in the presence of an excess of oxygen, were presented. It was demonstrated
that, at the temperature of 523 K and for space velocities ranged between
2,700...13,100 h-1, the benzene catalytic oxidation in humid air stream (5%
vol. H2O) occurs following a first order reaction. For establishing the
dependence relationship between the temperature and rate constant, the
influence of the temperature upon the benzene catalytic conversion was
investigated. The benzene oxidation reaction was carried-out in air stream,
both in absence and presence of water vapours (5% vol. H2O), for
temperatures ranged between 423...623 K and a space velocity equal to 6,388
h-1. Based on the kinetic analysis it was concluded that the benzene
catalytic oxidation process occurs after a combined kinetic mechanism,
transport through pores–transformation.
Thermal degradation kinetics of some phosphorus
containing aromatic polyesters.
C. HAMCIUC, T. VLAD-BUBULAC, O. PETREUŞ, G. LISĂ
pages 43 - 52
Abstract Phosphorus containing aromatic polyesters
were prepared by polycondensation reactions of 2-(6-oxido-6H-
dibenz<c,e><1,2>oxaphosphorin-6-yl)-1,4-riaphthalene diol with different
aromatic dicarboxylic acids, such as terephthalic acid, 2-nitroterephthalic
acid, isophthalic acid and tert-butylisophthalic acid. The thermal
decomposition behavior of the polymers was studied using thermogravimetric
analysis in nitrogen, at several heating rates: 10°C/min, 12°C/min and
15°C/min. The polymers showed good thermal stability with decomposition
temperature corresponding to 10% weight loss above 345°C. The kinetic
processing of data was carried out using Flynn-Wall-Ozawa and Kissinger
methods.
Esterification of stearic acid with epichlorohydrin on
anion exchange resin catalyst.
E. I. MUREŞAN, S. OPREA, E. HOROBA
pages 53 - 64
Abstract The effectiveness of different anion
exchange resins in esterification reaction of stearic acid with
epichlorohydrin was studied. Purolite A-520E resin proved to be the most
effective catalyst in the synthesis of 3-chloro-2-hydroxypropyl stearate.
The effects of certain parameters such as: speed of agitation, catalyst
particle size, catalyst loading, temperature on the rate of reaction, were
studied. It was found that the overall rate is intrinsically kinetically
controlled. The structures of 3-chloro-2-hydroxypropyl stearate and
2,3-epoxypropyl, stearate obtained by dehydrochlorination of chlorohydrin
esters, was confirmed by FTIR analyses.
Microwave - assisted polymerisation applied in
synthesis of acryl amide based three-dimensional networks.
C. MIHĂILESCU, V.
MUŞAT, V. BULACOVSCHI, G. LISA, B. C. SIMIONESCU
pages 65 - 72
Abstract Free radical polymerization of acryl amide
initiated with potassium oxydisulphate under microwave irradiation was
investigated. The polymerization was carried out in presence of
formaldehyde, as cross-linking agent, and the effect of monomer and
initiator concentration, and formaldehyde/monomer ratio upon conversion was
analysed. A significant enhancement of the rates of polymerization was
found.
Optimization of mixing in stirred bioreactors. 4.
Comparative analysis of the shear promoted by the radial impellers for
anaerobic yeasts broths.
E. FOLESCU, A-I. GALACTION, D. CAŞCAVAL
pages 73 - 84
Abstract With the goal to select the optimum
impeller combination for a given broth, the studies on mechanical mixing
performances are continued by comparatively analysing the shear forces
promoted by seven types of radial impellers on Saccharomyces cerevisiae
suspensions of different biomass concentration. The obtained results
indicated the following order of the shear stress magnitude, valid for the
domain of yeasts concentration of 40...150 g/L d.w.: Disperser sawtooth
<<Pitched bladed turbine -- Pumper mixer < Curved bladed turbine << Smith
turbine < Paddle with six blades << Rushton turbine. Unlike to the shear
rate variation, for each studied impeller the shear stress increases with
the increase of S. cerevisiae biomass concentration up to 150 g/L d.w..
The use of PONILIT GT-2 anionic polyelectrolyte as soil
conditioning agent.
C. ZAHARIA, I. IVANOV DOSPINESCU, M. MACOVEANU
pages 85 - 92
Abstract The synthetic PONILIT GT-2 anionic
polyelectrolyte can be used as soil conditioning agent for improving the
soil ability to support vegetation as grassland, different crops and trees.
The increasing values of germination degree for some vegetal species of
grass performed when the polyelectrolyte is applied confirm the possibility
to remediate the soil fertility into some defavorized sites. The
experimental data concludes that the use of low polyelectrolyte
concentration increases more than one and half times the germination degrees
when is applied together with commercial fertilized soil (e.g.< 25 mg
polyelectrolyte/kg soil).
Making functional the white mineral pigments in order
to increase the efficiency of the filling the paper process
R. C. CIOCINTA, M.E. CIOBANU
pages 93 - 100
Abstract The filling is the action of incorporating
mineral particles with fine granularity in the fibrous material, in the
sheet of paper, respectively. The purpose of this process is to improve
paper's optic properties and also other features like the porosity, the
smoothness, the printing performance, etc. The experiments of filling the
fibers' channels have been accomplished in several variants which included
the insertion of calcium carbonate in the celluloid fibers' channels.
Therefore, we referred to fibers' treatment with calcium hydroxide solution
with a 30% consistency of the paste, and with carbon dioxide, with a low
consistency (1.5%, resulting after the treatment with lime cream), with a
high consistency, respectively (30%), resulted after elimination of the
excess of calcium hydroxide solution. The results are influenced by the
paste's consistency as well at the lime cream treatment, as at the carbonate
treatment. The only meaningful changes we observed were the decrease of
density and the drop of the resistance and, respectively, of the resistance
at traction of the paper sheets obtained from the pastes air dried before
the lime cream treatment. These changes are obviously due to the breaking up
of the structure, because after the drying the fibers weren't milled.
Oxygen delignification of softwood kraft pulps. Some
aspects regarding molecular weight of dissolved lignin.
A. C. PUITEL, D. GAVRILESCU
pages 101 - 108
Abstract The paper deals with some aspects regarding
molecular weights (MW) of oxygen delignification (Od) dissolved lignin. The
filtrates containing the resulted Od dissolved lignin were obtained in
laboratory conditions by oxygen delignification of industrial softwood kraft
pulp and subjected to UV-VIS spectrometry analysis and to aqueous gel
permeation chromatography on Sephadex G50 and Sepadex LH20 packed columns.
The obtained elution curves were used to calculate the molecular mass
distributions of the residual lignin present in oxygen delignification
filtrates, mostly lignin fragments as suggested by the UV-VIS spectra. It
was found that the low molecular fraction (LMW<1,000 Da) increases during
oxygen delignification. The lignin contained by the delignification filtrate
was precipitated under acidic conditions and subjected to FT-IR
spectroscopy. The FT-IR spectral data obtained had little differences,
altought pulps with different initial lignin content were used.
Comparative study of environmental impact assessment
using the global pollution method applied in the case of four Moldavian
solid wastes landfills
C. ZAHARIA, M. SURPATEANU
pages 109 - 124
Abstract Comparative study of solid waste deposition
activities on four different Moldavian landfills was performed using the
quantification method of global pollution index in order to assess the
environmental impact and to initiate the safe environment-friendly wastes
deposition. For this study were necessary different environmental analysis
performed for air, water and soil quality during the wastes deposition
activities (in the same season of the year). In this paper there were
presented the main characteristics of the four studied landfills that
corresponded to the conventional deposition process. There were obtained
different values of the global pollution index that vary between 1.751 and
3.194 and concluded the fact that the environment was modified by the
industrial/economic activities generating discomfort effects to life forms.
This fact imposes the necessity of technical and sanitary area ecologization
in order to be non- dangereous to life forms.
CRISTOFOR I. SIMIONESCU in memoriam
by V. I. POPA
pages 125 - 126
2006, Volume
LII (LVI) , Issue 1-2
Studiul spectrofotometric al complecsilor ionilor
Fe2+,Co2+, Ni2+ cu 2,2’-dipiridilul
D. BEJAN, AL. DUCA
pages 7 - 20
Abstract The aim of the present paper is the study
of formation of the [ML3]2+ (M2+: Fe2+, Co2+, Ni2+) complexes with
2,2'-Dipyridyl (Dpy). The study was carried out by molecular absorption
spectrometry in the visible range, in partially aqueous medium
(water-ethanol) with both singular solution of the above mentioned ions and
mixed solutions of binary and ternary mixtures. The reciprocal influence of
the ions on the spectral characteristics (Amax, λmax, ω) of the [M(Dpy)3]2+
complexes would indicate the possibility of dosing one ion in the presence
of the other by means of the calibration curves. The stability constants and
molar absorptivities of the [Ni(Dpy)3]2+ and [Co(Dpy)3]2+ complexes were
estimated and found to be lower than those for [Fe(Dpy)3]2+. The influence
of pH, time and order of reagent addition on the formation and stability of
the above mentioned complexes was evaluated. The VIS [M(Dpy)3]2+ spectra
were compared to those of the [M(Phen)3]2+ complexes (Phen = 1,
10-phenanthroline) and some similarities and differences connected with
structural features of the two ligands were found.
Selective extraction of Hg(II) in aqueous PEG (1550) -
(NH4)2SO4 Two - phase system in presence of iodide ions
L. BULGARIU, D. BULGARIU, I. SÂRGHIE
pages 21 - 30
Abstract The extraction of Hg(II) and of several
interfering metal ions (Cd(II), Zn(II), Co(II) and Ni(II)) has been studied
in aqueous PEG(1550) - (NH4)2SO4 two-phase system using iodide ions as
extracting agents. The distribution studies were carried out at four values
of salt stock solution pH, within the pH range between 2 and 7. Unlike of
interfering metal ions (Cd(II), Zn(II), Co(II) and Ni(II)), Hg(II) is
quantitatively extracted, and the extraction maximum is obtained at lower
iodide concentration with high acidity of salt, stock solution. This
different extraction behaviour of Hg(II) can be attributed to the formation,
in extraction system, of anionic iodide species with high stability. In
these conditions,' the Hg(II) selective extraction can be realized in the
following cases: a) in extraction systems with a high acidity of salt stock
solution (pH = 2.05) and lower concentration of extracting agent (0.02 mol
I-/L) or b) in extraction systems with a lower acidity of salt stock
solution (pH = 7.12) and high concentration of iodide ions (0.06 mol/L). The
values of selectivity coefficients indicate a good separation of Hg(II)
towards to these metal ions.
Excess molar volumes of binary mixtures
etylbenzene-heptane, octane, nonane, decane and dodecane mixtures at 318.15
K
G. BOLAT, J. ORTEGA, G. LISĂ, I.M. POPA
pages 31 - 38
Abstract This paper reports the density of
ethylbenzene-heptane, octane, nonane, decane and dodecane mixtures at 318.15
K throughout the whole concentration range. The excess molar volumes were
calculated from experimental data and fitted to a Redlich-Kister polynomial
function and Zeta equation. Results were analysed in terms of molecular
interactions.
Considerations concernant la reactivite des elements chimiques du
septieme groupe A
S. IFRIM
pages 39 - 44
Abstract Il est bien connu que dans le groupement
des halog6nes la reactivite chimique baisse de fluor very iode, bien que
stir la derniere couche electronique - la couche de valence --les atomes des
halogenes out, chacun, sept electrons. A.fin d'expliquer la difference de
reactivite chimique des elements du septi6ine groupe principal on utilise la
notion de densite electronique peripherique, formulee par Pauteur dans tin
travail anterieur. Dans le cas des halogenes Fatome de fluor et egalement
son ion ont la plus elevee densite electronique peripherique et justement
c'est le halog6ne le plus reactif. Cette densite electronique diminue de
haut en bas et en meme sens baisse egalement la reactivite chimique des
elements de ce groupe principal. Les energies de liaison des balog6nes aver
les autres elements comme le hydrogens, le carbon, quelques metaux, sont
notablerrient plus elevees dans le cas des fluorures et diminuent
graduellenierit dans le cas des autres halogenures. On constate tine
diminution parallels de ces energies de liaison aver la diminution des
densites electroniques peripheriques des elements correspond ants. A l'aide
de cette notion on pent expliquer atissi la variation de quelques
caracteristiques des halog6nes, comme: les points de fusion et d'ebullition,
la densite ou bien l'enthalpie de hydratation, evidemment prenant en
consideration la densite electronique peripherique des molecules et
respectivement, des ions des halogenes.
Kinetics of carbon dioxide absorption into
ethynendiamine aqueous solution
I. SIMINICEANU, R. TĂTĂRU-FĂRMUŞ, J. M. AMANN
pages 45 - 50
Abstract The absorption of CO2 into activated
carbonate buffer solutions is the main process applied in the existing
ammonia plants. The major drawback of this process is the high,
endothermicity of the regeneration step. Therefore, new chemical solvents
must be introduced having not only high absorption rate and capacity but
also low heat of regeneration., The objective of this work was to study the
kinetics of CO2 absorption into aqueous solutions of ethylenediamine (EDA).
A thermo-regulated constant Pinterfacial area,gas-liquid reactor has been
used to measure the carbon dioxide absorption rates into this aqueous amine
solution (3% mol) in the temperature range 298...333 K. The experimental
results have been interpreted using the equations from the two film model.
The enhancement factor was always greater then 3. The pseudo-first order
rate constant, derived from the experimental data; was of the same order of
magnitude as for absorption into mixtures of inonoethanolamine (NIEA) and
N-methyldietanolamine (MDEA).
Modeling the ammonium sulphate solution electro
dialysis
I. SIMINICEANU, I.L. COTEŢ
pages 51 - 58
Abstract A mathematical model was derived to
describe the concentration evolution vs. time in a batch-recirculation
laboratoryscale electrodialyser. The integrated model contains two constants
that have been identified by confronting the computed data with the
experimental ones. The relative errors of the model, including the average
values of the identified constants, have beet) estimated. The validated
model was finally used to extrapolate the electrodialysis (ED) process in
order to determine the necessary time for a complete removal of ammonium
sulfate, equivalent to a final dilute content of less than 1.5 mol/m3
ammonium sulfate.
Magnetic and ultrasonic cooling water treatment for scale prevention
P. PENA, ST. IVĂŞCANU, O. GEORGESCU, V. IACOB, M.
APOSTOLESCU
pages 59 - 66
Abstract It is widely recognized that the heat
transfer is decreasing at the air compression plants due to deposits yielded
by the cooling water. Besides the chemical and mechanical conventional
methods the literature quotes trials of preventing these phenomena using
magnetic and/or ultrasonic methods. The paper presents a case study using a
water-air heat exchanging system in an air compression plant to which a,
magnetic field and ultrasounds were applied. The heat transfer indexes are
computed starting from the equipment's geometry and working conditions.
Correspondingly, deposit microstructures in. various working regimes and
conditions and the treatment method efficiencies are shown as well.
Influence of the conformational parameters on physical properties of
some aromatic poly(1,3,4-oxadiazole-ether)s
C. HAMCIUC, E. HAMCIUC, I. A. RONAVA
pages 67 - 76
Abstract Conformational rigidity parameters of some
aromatic polv(1,3,4-oxadiazole-etlier)s have been calculated by Monte Carlo
method with allowance for hindered rotation. Several physical properties
such as solubility, glass transition temperature initial decomposition
temperature and dielectric constant are discussed in relation with the
structure of the polymers and rigidity of their chains.
Multiobjective optimisation of a free radical polymerization process.
I. Classical solving methods
S. CURTEANU
pages 77 - 90
Abstract The optimal control policies for a,
polymerization process, particularly for the batch bulk free radical
polymerization of methyl methacrylate, have been determined using a
multiobjer-tive optimization technique. The process objectives, weightly
combined in a scalar function, include minimization of the polydispersity
index and the reaction time, maximization of monomer conversion or
achievement imposed values for conversion and number average polymerization
degree. The decision variables were initial concentration of the initiator
and temperature formed by isothermal steps. For solving the optimization
problem, a traditional method based on sequential quadratic programming
(SQP), implemented in MATIAB, was chosen. Two problems are focussed in the
discussion section: the influence of search starting point in the SQP method
and the influence of the weights attached to each objective upon the
optimization results, in order to find the best values. In a some
multlobjective optimization, not the value of the objective function is
relevant (even it is a mininium), but the values of the parameters which
constitute partial objectives. The solution of the problem represents the
result of the user decision which takes into account technological criteria.
Separation of erythromycin by pertraction. Mathematical modelling of
facilitated pertraction
D. CAŞCAVAL, A.I. GALACTION, N. NICUTA
pages 91 - 100
Abstract Using the statistical analysis and a
factorial experiment of second order, two mathematical correlations
describing the influences of the main parameters (pH-value of feed phase,
pH-value of stripping phase, carrier concentration into liquid membrane) on
Ery-thromycin facilitated pertraction have been established. The considered
variables control the separation process in a 94...98.7% extent, the
pH-value of stripping phase exhibiting the most important influence.
Integrating chemistry and biochemistry in papermaking systems
E. BOBU
pages 101 - 118
Abstract This paper summarizes the results of
several years of research concerning the application of the chemical
additives and bio-chemicals in papermaking systems that produce corrugating
medium from old corrugated containers (OCC) waste paper and are working with
a high degree of water circuit closure. First, it is showed that a
multi-component retention system consisting of coagulant/
flocculant/microparticies can be an effective way to optimizing the wet end
chemistry and. paper quality. At a first sight, such a complex additive
system could appears no economical feasible, especially for low paper
grades. However a holistic view of the papermaking system allowed us to
demonstrate a higher cost effectiveness of the three component additive
system comparatively with single or two component systems. In order to
minimize the environmental impact of papermaking chemicals, two solutions
are investigated: enzymatic treatment of the OCC pulp and application of
chitosan, a typical bio-chemical compound, as a substitute of synthetic
polymers in the papermaking additive systems. It was showed that xylanase
enzyme can enhance papermaking potential of recycled fibers by reducing
colloidal dissolved materials and improving the bonding potential of fibers.
A comparative study demonstrated that the effectiveness of chitosan as
papermaking additive is comparable with that of cationic polyethyleneimine.
Potential toxic elements in the food wrappings. I. Methodology and
methods for the determination of organic and inorganic elements
TH. MALUŢAN, N. COTAE, E. POPPEL
pages 119 - 126
Abstract The paper presents the methodology and
methods regarding the determination of toxic organic and inorganic
substances that are present in paper and paperboard to come into contact
with food wrappers. The obtained data of analysis are in concordance with
those obtained in specialized foreign institutes.
GHEORGHE BURLACU in memoriam
by S. IFRIM
pages 127 - 130
BOOK REVIEW: Polysaccharides - Structural Diversity and Functional Versality, Second
Edition, Edited by Severian Dumitriu, University of Sherbrooke, Quebec,
Canada
review by V.I. POPA
page 131
2006, Volume
LII (LVI), Issue 3-4
Co(II) coordination compounds with oxygen organic
ligands donor
M. FLONDOR, I. ROŞCA, D. SIBIESCU
pages 7 - 14
Abstract As a continuation of our previous research,
a study of the coordination compounds derived from Co(II) and organic
ligands such as: 1-(3,5-dibromo-2-hydroxy-phenyl)-2-phenylsu1fanyl-etharione
(L1); 1-(5-bromo-2-hydroxy-4-methylphenyl)-2-phenylsulfanyl-ethanone (L2)
and 1-(3,5-dibromo-2-hydroxy-4-methyl-phenyl)-2-phenylsulfanyl-ethanone (L3)
are presented in this paper. The used method in this study were: chemical
analysis, IR and RES spectroscopy. The experimental data were to assign the
structural formulas of the studied compounds.
Synthesis and characterization of the 1,5- pentilen
diamin Schiff bases
A. PUI, C. MALUTAN, M. PUI
pages 15 - 20
Abstract A series of four Schiff bases proceed from
derivates of salycilaldehide and 1,5-pentilendiamine were synthesized. These
were characterized by elemental analysis, spectroscopie 1H NTNIR, FT IR and
UVNIS spectroscopy. The 1H NMR spectra obtained and simulated indicated a
very good correlation between chemical shift and intensity of corresponding
picks.
Synthesis and biological activities of new 1,2,4-triazole and
1,3,4-thiadiazole derivatives
V. SUNEL, L. PROFIRE, C. MAFTEI, M. POPA, A. CIOBANU,
R. JUDELE, A. A. POPA
pages 21 - 30
Abstract New 1,2,4-triazole and 1,3,4-thiadiazole
derivatives were synthesized by intramolecular cyclization of some
1,4-disubstituted thiosemicarbazides in acid or in alkali medium. The
chemical structure of the compounds was confirmed by elemental analysis data
and IR, 1H-NMR and 13C NMR spectral measurements. The compounds were
evaluated in vitro for antibacterial activity against Staphylococcus aureus,
Bacillus antracis, Sarcina Luteea, Bacillus cereus, and Escherichia coil.
Some of the obtained compounds showed high antibacterial activity against
Bacillus antracis and Bacillus cereu. The DL50 values for the synthesized
compounds were also established.
Hydrodynamic study of the porous grains fixed bed
I. GALBEN, V. PETRUC, S. PETRESCU
pages 31 - 40
Abstract An equation to calculate the pressure drop
for a fixed bed of porous particles crossed by a gas phase was established.
The equation implies the experimental determination of the modified friction
factor (Fm) and the establishing of a and n parameters with the equation
proposed to calculate the Fm, factor (Fm,= aRe-n). Using spherical silica
gel grains (d = 2.57; 3 57 mm), and spherical molecular sieves (d = 2 82;
3.57 mm), respectively, in fixed bed crossed by dried air, pressure drop and
a and n parameters, were determined. Based on the values of these parameters
there were calculated F, with the relation Fm = f(Re) and the pressure drop
with the proposed equation. The agreement between the calculated and
experimental values of the pressure drop shows that the proposed equation
verifies the experimental data.
Mineralization of crystal violet in water by anodic
oxidation, electro-fenton and photo - electro - fenton
I. SIMINICEANU, C.I. ALEXANDRU
pages 41 - 48
Abstract The paper presents experimental results
concerning the Crystal Violet (CV) mineralization in water by three new
Advanced Electrochemical Oxidation Processes (AEOPs): Anodic Oxidation (AO),
Electro-Fenton (EF), and PhotoElectro-Fenton (PEF).The experiments have been
carried out with an open, undivided and thermostated cell with a carbon-PTFE
cathode and a BDD anode. All the degradation experiments have been done at
pH=3, 308K, 300 mA, and a solution concentration in CV of about 100 ppm
total organic carbon (TOC). The EF and PEF treatments were carried out by
addition of 1 mM FeSO4 to the starting solution. The mineralization degree
has been determined by measuring the residual TOC concentration of the dye
in water. The obtained results have shown that the effectiveness of the
three methods was increasing as follows: AO<EF<PEF. This relative
effectiveness was explained by the specific mechanisms of the hydroxyl
radical generation in each process. The influence of small doses of CuSO4 on
the effectiveness of EF and PEF has also been investigated. The three new
methods investigated proved to be more effective than the TiO2-UV method
previously studied by Sahoo and Saquib.
An investigation of the kinetic parameters of the
volatile organic compounds oxidation process on SCR-DeNOx commercial
catalyst. 1. Evaluation of reaction order and effective constant rate
L. LAZĂR, H. KÖSER, I. BALASANIAN, F. BANDRABUR
pages 49 - 58
Abstract A study regarding the kinetic aspects of
the benzene oxidation process in the presence of the SCR-DeNOx (0.53%wtV205)
commercial catalyst was conducted within this paper. Interpretation of the
results is done in order to establish the influence of parameters on the
equation rate of the benzene oxidation catalytic process. Elimination of the
influence of mass transfer through gas phase and study concerning influence
of benzene concentration upon conversion allow to establish the catalytic
process rate equation. The experimental investigation was carried-out for
low concentration of benzene in gas (14...140 ppm) and for a temperature
equal to 523 K. For spatial velocities ranged between 2,700 and 13,100 h-1,
the rate of the catalytic process is not influenced by reactants mass
transfer through gas phase.
p-Cholorobenzoate intercalated in zinc-aluminum layered double
hydroxide: a new stable organo-mineral hybrid
A. BOTOMEI, E. DUMITRIU, V. HULEA, A. NASTRO
pages 59 - 66
Abstract p-Chlorobenzoic acid anion (p-CBA) was
intercalated between layers of Zn-Al layered double hydroxides (LDHs). In
order to obtain the corresponding hybrid materials three methods of
incorporation were applied: direct synthesis by coprecipitation of metal
nitrates and sodium p-CBA, ion exchange of the LDH nitrate with organic ion
and structure reconstruction of calcined precursor. The solids were
characterized by X-ray diffraction, infrared spectroscopy and thermal
analyses and the collected data proved the forming of intercalated
structures.
Synthesis and characterization of layred double
hydroxides intercalated with 2,4-dichlorophenoxyacetic acid
M. FRUNZĂ, M.I. POPA, V. HULEA
pages 67 - 72
Abstract New organic-inorganic hybrid nanostructures
were synthesized by incorporation 2,4-dichlorophenoxyacetic acid (2,4-D) in
the layered double hydroxides (LDH). Samples are prepared by using direct
co-precipitation of metal nitrates and 2,4-D aqueous solutions. The X-ray
diffraction, Fourier transform infrared spectroscopy (FTIR) and
thermogravimetric (TG-DTG) analysis point out the presence of the organic
compound in the network structure of the samples. Considering together the
pesticide family activity of 2,4-dichlorophenoxyacetic acid and the
biocompatibility of the layered double hydroxides, the new synthesized
materials could open interesting perspectives for obtaining more
environmentally friendly insecticides.
Preparation and characterization of a new photocatalyst from synthetic
laponite clays
B.-L. IURASCU, I. SIMINICEANU, D. VIONE
pages 73 - 82
Abstract Photo-assisted Fenton conversion and
mineralization of phenol in a 0.1 mM aqueous solution was studied using a
new catalyst prepared from synthetic layered clay laponite (Laponite RD) by
the pillaring technique. Eight different catalyst samples were prepared:
four without thermal aging (WTA), calcined at 523 K, 623 K, 723 K and 823 K,
and other four with thermal aging (TA), calcined at the same temperatures.
The samples were characterized by XRD and SEM/EDS techniques, and through
the bulk chemical analysis. The activity of catalyst samples was evaluated
by the phenol conversion (XPh) and phenol mineralization (XTOC) versus
reaction time in the presence of 5 mM H202, 1 g/L catalyst, pH = 3, and 303
K. The conversion was almost complete (99.5%) after only 90 s with the
TA-623. The highest mineralization (86%) after 90 min was observed with the
catalyst TA- 723.
Study of the sulphur dioxide chemosorbtion in slurry of
the calcium carbonate residual
AL. SZEP, M. HARJA
pages 83 - 90
Abstract The paper deals with a study of the
reactive dissolution of sulfur dioxide in different natural, synthetic and
waste calcium carbonate slurry. Using the modified Lewis reactor it was
analysed the influence of nature of carbonate, suspension consistence,
milling time, temperature, contact area/volume of reaction mass,
overpressure of gases on the kinetic of chemosorption of sulfur dioxide. The
IR spectra of the initial, final solids and the crystals formed from
mother-liquor indicate the same evolution of process indifferent of the
nature of initial carbonate and preparative milling of waste calcium
carbonate.
Environmental impact aspects of modern pulp bleaching
techniques
A. C. PUITEL, D. GAVRILESCU
pages 91 - 108
Abstract The environmental impact generated by pulp
industry has been analysed in many studies over the last period. The most
stringent environmental problems associated with pulp bleaching, one of the
most important activity in pulp production, is consume of vi-ater and
generation of waste waters. Bleaching with elemental chlorine leads to
generation of toxic and refractory chlorinated organics, generally expressed
as Adsorbable Organic Halogens (AOX). As consequence to these problems,
elemental chlorine bleaching has been replaced by less pollutant techniques
as Elementary Chlorine Free (ECF) and Totally Chlorine Free (TCF). The paper
reviews the main bleaching stages employed by ECF and TCF, the technological
and environmental problems as well as the performances achieved by using ECF
and TCF techniques. TCF bleaching by not generating AOX. seems to be the
most promising technology even if today it is not as main bleaching
technology in pulp industry.
Is a new oil distribution a major risk environmental components
B. ROBU, V. PETRUC, M. MACOVEANU
pages 109 - 116
Abstract This paper describes a new integrated
method for impacts and risks, induced on environment by a new activity
related to oil distribution. The new method was developed for main
environmental components (surface water, ground water, air and soil), but
taking into account the estimated emissions dust and VOCs in air, and the
fact that the waste waters are discharged in surface water, for evaluated
situation (new activity related to oil distribution) were considered only
tow environmental components in assessment process: air and surface water.
The new integrated method for environmental impact and risk assessment of
new activities or existing activities considers the estimated, respectively
measured concentrations of pollutants, and this makes the method to reflect
the real situation. Also, the integrated method is based on mathematical
steps which loaded to elaboration of a soft designed SAB, and this offers a
higher degree of objectivity, and the lack of evaluators doesn't influence
the final results. The results of the new method applied to evaluate the
environmental impact and risk induced on environment by a new oil
distribution station show that a great impact is induced on air, and
associated risk is moderate at an unacceptable level. So, the air quality is
modified by related activities, and can be dangerous for life forms and this
requires actions of pollution prevention and control.
Kinetic study on degradation of Alcian Blui 86x by heterogeneous
photocatalysis
A. F. CALIMAN, A. ANTONIADIS, I. PONLIAS, M. MACOVEANU
pages 117 - 128
Abstract The present paper proposes an investigation
of the kinetic of photocatalytic degradation of Alcian Blue 8 GX, a copper
phthalocyanine dye, used in biomedical laboratories as stain, in aqueous
suspensions containing the commercial catalyst TiO2 P-25.The heterogeneous
photocatalytic process was studied for different dye initial concentrations
(5...50 mg L-1) and temperatures (293.15 ... 323.15 K). The disappearance of
the organic molecule followed approximately a pseudofirst kinetic order
according to the Langmuir-Hinshelwood model. The apparent activation energy
(Ea), calculated from the Arrhenius' equation, was found to be Ea=19.7
kJ/mol. The small value of activation energy shows that the process of
photocatalytic degradation is not very temperature sensitive.
Natural polyphenolic compounds - modulators of yeast fermentation
activities
M. DĂNĂILĂ, V. I. POPA, I. VOLF
pages 129 - 136
Abstract This paper presents a study concerning the
biological activity of grape seeds polyphenols in a model experiment of
yeast alcoholic fermentation. The observation made is that the polyphenolic
products, depending on the concentration used, have a favourable effect on
yeast fermentative activity.
TIBERIU GOLGOTIU in memoriam
by I. ROSCA
pages 137 - 139
2005, Volume
LI (LV), Issue 1-2
Separation of Cd(II) from Zn(II) by extraction in PEG-based aqueous two
phases systems in presence of iodide ions
L. BULGARIU, I. SÂRGHIE
pages 7-16
Abstract The distribution behavior of Cd(II) and Zn(II) has been
studied in aqueous two-phase system formed from polyethylenglycol (PEG) and
ammonium sulphate, in presence of iodide ions at different pH of inorganic
salt stock solution values. The aqueous. two-phase's system are composed of
a polymer-rich phase and a salt-rich phase, both which have, an average
greater that 70% water content. In absence of iodide ions, both Cd(II) and
Zn(II) remained almost exclusively in the salt-rich phase. The addition of
I- enhances the metal ions partitioning into PEG-rich phase due to the
formation halide complexes. From the distribution ratio, determined as
function of iodide concentration, the extracted species were assumed. The
extractability of the metal ions is determined by the type of the metal ions
complexes, which depends on the pH of salt stock solution. A selective
separation of Cd(II) from Zn(II) was accomplished in the aqueous two-phase
system by using iodide ions, at high acidity of salt stock solution.
Study on the deviation from ideality of then binary
mixtures acetic acid-water, acetic acid-n-hexane and acetic acid-n-heptane
G. BOLAT, G. LISĂ, I.M. POPA
pages 17-24
Abstract Densities (p) and viscosities (q) for binary mixtures
of acetic acid with water, n-hexane and n-heptanes have been measured over
the whole composition range at 296.15, 302.15; 308.15; 314.15 and 319.15 K.
The excess viscosities were calculated, and the results were used to a
Redlich-Kister type polynomial relation. The corresponding parameters have
been derived. The resulting excess viscosities were interpreted in terms of
the interactions between the molecules in the binary mixture
Synthesis of ferrocene derivatives possesing liquid
cristaline properties
I. CÂRLESCU, A.M. SCUTARU, D. APREUTESEI, V. ALUPEI, D.
SCUTARU
pages 25-34
Abstract The preparation of a series of ferrocene containing
Schiff bases, possessing liquid crystalline properties, is described. In
order to induce mesogenic behavior, the structure of the substituent was
systematically varied. Derivatives with no more than two rings in the core
exhibit liquid crystalline properties. The synthesized products were
characterized using NMR, IR and mass spectroscopy, DSC and polarized optical
microscopy.
Benzene oxidation in the presence of halogenated acids
on SCR-DeNOx catalysts
L. LAZĂR, H. KOSER, I. BALASANIAN, F. BANDRABUR
pages 35-42
Abstract Experimentally results achieved from research
concerning the benzene oxidation kinetics on commercial SCR-DeNOx,
(V2O5-WO3/TiO2, 0.53% wt. V2O5), both in the presence and absence of the
halogenated acids (HBr, HCI), in humid air stream (5% vol. H2O) and also in
the absence of halogenated acids but in dry air stream, at temperatures of
423...623 K, are presented in this paper. The catalytic conversion of
benzene increases with temperature and is negatively influenced by
halogenated acids and water vapours. The benzene concentration does not
significantly influence the catalytic conversion. Considering the treated
gas composition, the apparent activation energy of the benzene catalytic
oxidation reaction is ranged between 27...32 W/mol, the oxidation rate being
affected by the mass transfer/diffusion process the catalyst level.
Reduction of nitrogen oxides in the presence of hydrocarbons using
Sr-Mn-perovskites as catalytic materials
L.M. ABORDEOAIEI, H. PAPP, V. SUPRUN, I. BALASANIAN
pages 43-50
Abstract In the present work the characterization and the
testing of perovskites in SCR-HC were investigated. The perovskites were
obtained by Pechini-type method with citric acid and after that
characterized by thermo-analytical methods, X-ray diffraction, temperature
programmed reduction and BET method. The catalytic activity was tested in
SRC-HC equipment using hydrocarbons such as propene and propane as
reductants. The results are promising especially for perovskites obtained by
calcination at 800°C.
Layered double hydroxides intercalated by phenoxyacetic acid
A. BOTOMEI, E. DUMITRIU, Y.L. PAILLAUD
pages 51-58
Abstract This paper reports the synthesis of Mg/Al double
layered hydroxides (LDHs) by coprecipitation, and of theirs phenoxyacetic
acid intercalates by anion exchange, reconstruction and coprecipitation
methods. The resulting, LDH, also known as hydrotalcite-like compounds of
the type [MII1-xMIIIx(OH)2][Anx/n].mH2O, were characterized by various
instrumental techniques, including X-ray diffraction (XRD), IR spectroscopy,
thermogravimetric analysis (TG) and chemical analysis. According to the XRD
technique the phenoxyacetic acid is better intercalated by coprecipitation
method than anion exchange.
Introduction of Aluminium into MCM-22 zeolite structure by two
different methods hydrothermal synthesis and isomorphic substitution
O.A.RUSU, A.S. MASSERON, E. DUMITRIU
pages 59-70
Abstract Deboronating the zeolitic structure of ERB-1 and then,
by hydrothermal treatment in the presence of corresponding precursors, new
metallic cations, especially transition metals, call be inserted in the
vacant tetrahedral framework positions. Thus, isomorphically substituted
MCM-22 zeolites, obviously materials that are difficult or impossible to be
synthesized by direct hydrothermal synthesis, call be obtained. In the
present work we have successfully used this procedure to insert aluminium in
the framework of deboronated ERB-1 in view to obtain high-silica Al-MCM-22,
material difficult to be prepared by a direct hydrothermal synthesis.
A comparative study on the native volcanic tuff and its Na from in the
exchange process with some heavy metal ions
Cl. COBZARU, C. CIBOTARU, S. OPREA, V. HULEA
pages 71-78
Abstract The native volcanic tuff and that modified with sodium
were used for retaining some metallic ions (Cr3+, Fe3+, Cd2+, Ni2+ and Pb2+)
from aqueous solutions. The tuff modified with sodium ions was found to be
much more efficient that the native one for all the metallic ions used in
the exchange process.
The effect of oxygen-vectors on vitamin B12
biosynthesis
E. FOLESCU, A.I. GALACTION, A.C. BLAGA, D. CAŞCAVAL
pages 79-88
Abstract The addition of n-dodecane in culture of
Propionibacterium shermanii, the main producer of vitamin B12, leads to the
considerable increase of oxygen transfer rate from air to fermentation
broth. The experiments indicated the existence of a certain value of
hydrocarbon concentration that corresponds to maximum mass transfer rate of
oxygen. The magnitude of the positive effect of oxygen-vector strongly
depends on operational conditions of bioreactor, on broths characteristics
and on Propionibacterium shermanii concentration.
Bilirubin metabolism at fetus and newborn
C. ANTON, D. BOLDUREANU
pages 89-94
Abstract Knowledge of the bilirubin metabolic stages is an
important step for the newborn jaundice prevention. Jaundice is the most
common and one of the most vexing problems that can occur in the newborn.
Although most jaundiced infants are otherwise perfectly healthy, they make
neonatologist anxious because bilirubin is potentially toxic, to the central
nervous system.
Phototherapy in RDH isoimmune hemolysis
C. ANTON, D. BOLDUREANU
pages 95-104
Abstract The RbD isoinimunization (anti-D) is a current problem
for neonatal assistance. Kernicterus represents an important complication,
sometimes even lethal, because of the rise of indirect bilirubin. This study
had the objective to identify the newborn with RhD (anti-D)
isoinimunization, the diagnosis and the therapeutically procedures applied
in order to prevent hyperbilirubin encephalopathy.
Ecological footprint - an instrument of sustainable development
D.M. ILIE, N. PEIU, M. GAVRILESCU
pages 105-112
Abstract A few years ago, a, new concept was for the first time
used in environmental assessment. The term in question was "ecological
footprint", a new method for evaluating the impacts of a human society of
consumption on the environment. The original method, created by Wackernagel
and Rees, uses six types of areas in order to calculate the ecological
footprint of a society, usually for a country or region, but also for the
entire human society, at global level. The result, of this evaluation is
presented as an only figure number and can be used, to compare different
countries with different land and water supplies and different populations,
in order to asses the contribution of each country to the global footprint.
The purpose of the present paper is to asses Romania's ecological footprint
for three consecutive years (1999,..., 2001). The data used for this paper
were taken from the official annual statistics of the state of Romania, from
the Food and Agricultural Organization and other bibliographical sources.
The obtained results have been compared with those of the World Wild Found
for Nature, the single international organism which evaluates periodically
the ecological footprint of all Earth's nations.
Qualitative and quantitative analysis of romanian
propolis samples from different geographical areas
C. LUCA, S. ANDREI, M. PANAIT, M. POPESCU
pages 113-120
Abstract Results of a preliminary study regarding the chemical
composition of propolis performed by the investigation of qualitative and
quantitative parameters are presented. The evaluation of propolis quality
was made by using propolis samples prelevated from different Romanian
geographical areas.
Studies regarding the sorption-desorption processes of permetrine
solutions in various wood essences used as support for cultural patrimony
goods
V. VASILACHE, C. LUCA, I. SANDU, A.I. SANDU
pages 121-126
Abstract A comparison between the sorption/desorption curves of
permetrine solution for four samples of new wood and four samples of old
wood affected by death watch found in a precarious state of conservation,
from the structure of the support or frame of a wood icon is performed.
2005, Volume
LI (LIV) , Issue 3-4
Refractive indices and molar volumes of binary mixtures
n-propanol-water and n-propanol-toluene
C. LISĂ, G. LISĂ
pages 7 - 14
Abstract This paper is aimed to determine the
refractive indices of n-propanol-water and n-propanol-toluene solutions, in
a wide composition range, at various temperatures and atmospheric pressure.
Based on these experimental data, we calculated the excess refractive
indices and we estimated the excess molar volume of the studied systems. The
obtained results were compared with the values of the excess molar volume of
previous studies concerning the density of these binary mixtures.
Corrosion behavior of some dental alloys
D. MARECI, D.M. AELENEI, GH. NEMŢOI, N. AELENEI, C.
BOCANU
pages 15 - 22
Abstract The corrosion behavior of pure titanium,
four titanium alloys and four Ni-Cr and Co-Cr dental alloys in a Ringer type
solution was studied by potentiodynamic method. The main parameters of
corrosion process were determined from linear and cyclic polarization
curves. The most resistant to corrosion seem to be titanium alloys while the
dental alloys containing Fe or Cu show pitting type corrosion. The keeping
for 24 h of these alloys in Ringer solution leads to a relative passivation,
excepting the alloys which present pitting corrosion.
Coordinative compounds of Ni(II) with tetra-chloro
salen and tetra-chloro salophen types ligands
A. PUI, C. MĂLUŢAN
pages 23 - 30
Abstract The Schiff bases with two chlore atoms
graphed on the salicyl-aldehyde or salicylketone molecule and with -H, -CH3
or CH3-CH2- in the imminic-position was synthesized as ligands. The chain
between N-N atoms donors is ethylene or phenylene. The Ni(II) forms with
such ligands complexes with square planar or nearly planar geometry. The
ligands and the complexes were characterized by elemental analysis, UV-VIS,
FT-IR and NMR spectroscopy.
Electrodialysis of ammonium sulfate solutions.
II.Conductivity measurement and correlation
I. SIMINICEANU, L.I. COTEŢ
pages 31 - 36
Abstract The paper deals with the conductivity
measurement of ammonium sulfate solutions
Mass transfer with chemical reaction in single drops
S. PETRESCU, F. UNGUREANU
pages 37 - 44
Mathematical modeling of folic acid separation by reactive extraction
A.I. GALACTION, A.C. BLAGA, D. CAŞCAVAL, E. FOLESCU
pages 45 - 52
Abstract Using the statistical analysis and a
factorial experiment of second order, a mathematical correlation between the
folic acid reactive extraction degree and the main parameters influencing
the process (Amberlite LA-2 concentration, pHvalue, duration) have been
established. The considered variables control the extraction process in a
95.2% extent, the pH-value and the extractant concentration in organic phase
exhibiting the most important influences.
Kinetic study of vitamin C reactive extraction with
Amberlite LA-2
A.C. BLAGA, A.I. GALACTION, D. CAŞCAVAL
pages 53 - 58
Abstract The separation of vitamin C by reactive
extraction with Amberlite LA-2 dissolved in dichloroiriethane represents an
advantageous alternative to the downstream processes applied at industrial
scale. The reactive extraction occurs by interfacial formation of an
ammonium salt solvated by extractant molecules. The corresponding
interfacial equilibrium suggested a chemical reaction of second order
between the solute and the extractant. The corresponding values of
interfacial reaction rates and constant have been calculated. The results
indicated that the value of velocity constant is k2 = 4.884 ·10-4 L/mole.s,
greater than the values obtained for others vitamins extraction with
Amberlite LA-2.
Liquid crystal maleimide monomers
C. HULUBEI, D. BUICEAC
pages 59 - 66
Abstract Two new maleimide monomers containing
azomethine, amide and azo groups were synthesized and structurally
characterized. The new maleimides have been synthesized by solution
polycondensation reaction from the p-aminoazobenzene with
N-(4-formyl-phenoxy-4'-carbonylphenyl) maleimide and 4-maleimido-benzoyl
chloride, respectively. The monomers were characterized by elemental
analysis and infrared and proton nuclear magnetic resonance spectroscopy.
The liquid crystal behavior of these compounds was characterized by
differential scanning calorimetry (DSC) and hot-stage polarized light
microscopy (PLM). The both maleimides exhibited thermotropic liquid
crystalline behavior.
Controlled water delivery systems for dried soils. I.
Copolymer synthesis and water delivery mechanism
T. RUSU, V. BULACOVSCHI
pages 67 - 76
Abstract The possibility of using copolymer systems
for improving soil humidity in dry atmospleric conditions is proposed. The
investigation was made in case of different amphiphilic copolymers, but this
paper presents only the synthesis and characterization of the copolymer
networks made up from poly (dimethylsiloxane) (PDMS) and poly(methacrilic
acid) (PMAA) sequences. Also, the networks were investigated as controlled
water delivery systems in dry soils, being proposed a possible mechanism.
Surface characterisation of free-radical mass
polymerization obtained acrylic copolymers for artificials crystalline
implants
C. LOSPA, M. RUSU, M. VONE, M.H. ADAO, P. SUCKLING, J.
DE CONINK
pages 77 - 82
Abstract The results of a study regarding surface
properties of a series of acrylic copolymers obtained by free-radical mass
copolymerization are presented. The study is part of a research project on
polymeric biomaterials with potential use for a crystalline lens implant to
restore accommodation. The following monomers were used to obtain acrylic
copolymers: metyl metacrylate, cyclohexyl metacrylate, 2ethyl hexyl
acrylate, butyl acrylate. The critical surface tension and wettability of
these copolymers were investigated through measurements of the static
contact angle, using water, alkanes and ethanol/water mixtures as liquids.
Properties of conductive fibres based on polyaniline
L.R. MANEA, A. NECHITA
pages 83 - 88
Abstract The conductive fibers obtained by chemical
coating are studied. Different conductive materials have been used in order
to obtain conductive pol-yethylene terephtalate and Dyneema-based fibres
with specific electrical and mechanical properties. The electric
conductivity of these fibres have been investigated and the obtained results
are discussed. These fibres are intended for use in creating conductive
yarns and realizing connections In smart clothing or producing conductive
fabrics which can be used as electromagnetic shields.
Cellulose dissolution in lithium chloride/N,N-dimethylacetamide system
under microwave irradiation
C. MOCANU, S. CIOVICĂ, A. MURARIU, K. PIELICHOWSCHI
pages 89 - 98
Abstract The importance of cellulose dissolution in
lithium chloride (LiCl)-N,N-dimethylacetamide (DMAc) system is presented.
The mechanism of dissolution is not very well understood even after two
decades of use. There are some models which try to explain the interaction
between LiCI-DMAc and cellulose. The efficiency of the system is associated
with lower degradation rate. A new method for cellulose dissolution by
classical activation combined with microwave irradiation is proposed.
Sources of solid wastes in pulp mills.
D. GAVRILESCU
pages 99 - 106
Abstract The pulp mills generate various quantities
of solid wastes, depending on technological level, pulp grade and wood quality. These wastes are generated in all stages of pulp
manufacturing: wood processing, pulping, pulp washing and screening,
chemicals recovery. The minimizing of solid waste generation and the ways of
their processing are important problems for the pulp producers. These
problems are in strong connection with both the economical and environmental
aspects. Aims of this paper are to identify the sources of solid wastes in
the kraft (sulfate) pulp mills and to discuss the best ways of their
processing. The wood room represents the major area of wood wastes that are
very different regarding their shapes, dimensions and properties. Bark is
the most common wood waste and its volume ranged between 0.4...0.6 m3 /t
o.d. pulp. Besides bark, other wood residues appear in the wood room: fines,
pins, large chips. Their quantities are very different depending on the wood
quality, debarking method, and chipper performance. The most common way for
their valorization is by firing for energy using fluidized bed furnace
boiler. Wood-waste burning allows to obtain 0.8...1.2 t steam (1.2 MPa)/t of
o.d. pulp, depending of the wood losses at pulpwood preparation. Another
source of solid waste is the pulp screening stage where results 2...8% knots
and fine-screen rejects. The third major source of solid wastes in the kraft
pulp mill is the recovery plant, generating sodium salts enriched with NaCI
and KCI from recovery boiler, dregs from green liquor clarifier/filter, and
grit separated at slaker. Land filling is the only way of dregs and grit
disposal. Waste materials for landfill consist of ash, dregs and grit. A
good waste management in pulp manufacturing leads to enhancing of economical
performance as well as to an environmental sound process.
Environment impact and quality control on an old moldavian municipal
wastes landfill
C. ZAHARIA, M. SURPĂŢEANU
pages 107 - 120
Abstract Over more than 30 years, the deposition of
municipal wastes was usually done on special landfill that influenced
negatively the environment quality. To express the pollution level into the
area of deposition and proximity, an environmental impact assessment is
always necessary based on the environment analysis performed for air, water
and soil quality during the whole waste deposition activities. In this
paper, there are discussed the principal aspects of municipal waste
deposition conventional process on an old Moldavian landfill and, also, the
environment impact of the technological deposition process. The environment
quality data were obtained by standard analysis methods of the quality
indicators methods internationally approved (ISO). The environmental impact
of wastes deposition is assessed using the well known method of global
pollution index.
On the behavior of natural polyphenolic products as plant growth
regulators
A. BALAŞ, M. DĂNĂILĂ, V.I. POPA, N. ANGHEL
pages 121 - 126
Abstract This paper presents a study concerning the
biological activity of spruce bark polyphenols in a model experiment of
tomato seeds germination and plant cultivation. The observation made is that
the polyphenolic products have a favourable effect, depending on the
concentration used. Also, it was obvious a similar action to that of the
plant growth hormones, especially to auxines and citokinins.
Activated carbon adsorption for the treatment of the
pulp and paper industrial wastewater
D. TELEMAN, C. TEODOSIU, F. UNGUREANU, I. BALASANIAN
pages 127 - 134
Abstract This paper presents the results of a study
concerning the removal of phenolic compounds from wastewater resulted from
pulp and paper industry on granular activated carbon (GAC) PUROLITE AC 20G
previously thermally regenerated. The wastewater was formerly filtered and
the physical and chemical indicators were determined. The spectrophotometric
method with p-nitroaniline without extraction was used to establish the
phenol concentrations. The influence of the operating parameters was studied
in terms of: flow (Q), contact time between the adsorbent and wastewater
(t,) and the height of the activated carbon bed (H,). The best results
concerning the removal efficiencies were obtained by decreasing the values
of the flow at increased values of the height of the activated carbon bed.
An efficiency of phenol removal of 67% was obtained at Q = 5 ml/min and for
H, = 4 cm. Phenol concentrations in the effluent after 24 h of process
interruption had decreased (as compared to those in the interruption moment)
due to the fact that microorganisms from wastewater consume part of the
organic compounds adsorbed at the GAC surface and thus GAC recovers
partially its adsorption capacity. A comparative study regarding the phenol
adsorption efficiency from synthetic solutions containing phenol on new and
regenerated granular activated carbon was performed. By correlating the
variation of phenol removal efficiencies depending on flow and time for all
the results achieved, the mathematical model of the process using the Table
Curve 3D software was achieved.
2004, Volume
L (LIV), Issue 1-2 (June)
Kinetic study of the reactive dissolution of marble into sulphur dioxide
solution
AL. SZEP, GH. MIHĂILĂ, S. BARTHA, N. CAŞU
Corrosion tendency evaluation by electrochemical methods for some dental
alloys in simulated salivas
D. AELENEI, D. MARECI, GH. NEMŢOI, N. AELENEI
Aromatic polyamides containing acetoxybenzamide pendent groups
I. SAVA
Modified polymers based on PAV designed for stabilization and protection
of patrimony objects
M. NĂNESCU, M. IVĂNOIU, V. BULACOVSCHI
Spectrometric variants for determination of the tannins in wines
D. BEJAN, L. BULGARIU, G. RUSU
Structural analysis of Vanadium mixed oxides derived from substituted
hydrotalcite studied
G. CÂRJĂ, M. IRIMIA
Mathematical modelling of volcanic tuff behaviour in ion exchange process. Ion exchange with Cr3+ and Fe3+
Cl. COBZARU, S. OPREA
Functional polymers based on salicylic acid derivatives
C. HULUBEI, C.D. VLAD
Content of some proteic preparates by ion exchange chromatography with
gradient elution
D. BEJAN
Salt air generator for medicine recovery and environmental sanitation
G. CIOBANU et. al.
Pollution prevention in large volume organic chemical industry
C. MUŞAT, M. GAVRILESCU
Overview on integrated pollution prevention and control for the tanning
of hides and skins sector
O.M. TIMOFTE, M. GAVRILESCU
2004, Volume L (LIV),
Issue 3-4 (December)
Atom transfer radical polymerization. 1. Investigation of
the catalytic system based on Cu(0) and 2,2’-bipyridyl
E. TĂRAN, M. LĂZĂRESCU, B. DONOSE, I. CÂRLESCU, N. HURDUC
The evaluation of rheological characteristics for some better types
controlled-stress rheometry
V. MAIER, S. MAIER, M. COLŢ, V. BULACOVSCHI
Development of the mathematical model of the volcanic tuff behaviour in the ionic exchange process. Ion exchange with Pb2+, Ni2+ and Cd2+
Cl. COBZARU, S. OPREA
Contributions to the mechanism of the thermal decomposition reaction on the ammonia
D. DÂRŢU, L. ODOCHIAN, M. DUMITRAŞ
Neural network based modelling for viscosity of some binary systems
S. CURTEANU, G. LISĂ
Preparation and characterization of bismaleimide-diphenol prepolymers
C. HULUBEI
I. FECHETE, P. CAULLET, E. DUMITRIU, V. HULEA, H. KESSLER
Catalytic activity of the Al-EMT and AlGa-EMT zeolite. Study of gas-solid
heat transfer accompanied by solid phase change
S. PETRESCU, A, FRUNZĂ, M. SECULA
Powder coatings-based organic films
M. RUSU, C.E. MOCANU
Rheological study of film forming mixtures
V. MAIER, S. MAIER, V. BULACOVSCHI, V. BUCEVSCHI
Adhesive compositions based on vinylacetate-acrylic copolymers
C. MIHĂILESCU, M. DĂRÂNGĂ, V. BULACOVSCHI
Study of mass transfer in anodic dissolution process