2022, Issue 68(72), Fasc. 3 (September)

Contents

pages 1- 8   Download

Modeling of Noncatalytic Gas-Solid Reactions the Reaction Zone Thickness

EUGENIA TEODORA IACOB-TUDOSE, “Gheorghe Asachi” Technical University of Iasi, „Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, etudose@ch.tuiasi.ro

pages 9 – 23   Download
Abstract
A number of physical and mathematical models have been proposed for noncatalytic solid-gas reactions. In such a system, the reaction takes place in a part of the solid that can vary in large limits. Within this study, calculations with respect to the gaseous reactant, for simple isothermal first order reactions, have been carried out. The size of the specific reaction area is established and correlated with a mathematical model characterizing the chemical transformation that takes place. Depending on the specific thickness of the reaction zone, some well-known noncatalytic gas-solid reaction models such as: the shrinking core model (heterogeneous), the limited reaction zone model (general) and the total reaction zone model (homogeneous), have been re-established.
Keywords: gas-solid reaction models, specific thickness of the reaction zone, rectangular coordinates, spherical coordinates

Spectrophotometric Determination of Rifampicin in Aqueous Solution

IUSTINA-DENISA TANASĂ, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environment Protection
ANDREI-EUGEN BULGARIU, Emergency Hospital Professor Doctor Nicolae Oblu of Iaşi, Romania
CĂTĂLINA SIRIŢEANU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environment Protection
LAURA BULGARIU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environment Protection, lbulg@ch.tuiasi.ro

pages 25 - 34   Download
Abstract
In this study, a simple spectrophotometric method was developed for the quantitative determination of rifampicin in aqueous solution. The method is based on the property of rifampicin to modify, in aqueous media at pH of 7.0, the degree of ionization of the functional groups. After ionization, a coloured compound is formed, which can be analysed spectrophotometrically. The visible spectra of the yellow compound were recorded at pH of 7.0, in different buffer solutions (phosphate, hexamethylentetraamine (HMT) and borax) and the qualitative characteristics were determined. The highest absorbance was obtained in phosphate buffer, at λ = 470 nm, against distilled water, and these conditions were selected for quantitative determinations. This procedure allows the quantitative analysis of rifampicin in a wide concentration range (0.01 - 0.16 mmol·L-1), with a detection limit of 0.0002 mmol·L-1. The very good correspondence between the calculated and experimental values of rifampicin concentration shows that this method is valid and can be used for quantitative analysis, at least for laboratory studies.
Keywords: spectrophotometric method, rifampicin, quantitative determination, aqueous solution.

Surface Modification Induced by Aqeous Environment of Nucleobase-Modified Azo-Polysiloxanic Films

CRISTINA-MARIA HERGHILIGIU, “Gheorghe Asachi” Technical University of Iași, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, cristina-maria.herghiligiu@academic.tuiasi.ro
NICOLAE HURDUC, “Gheorghe Asachi” Technical University of Iași, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection

pages 35 - 45   Download
Abstract
Taking into account the use of nucleobase-modified azo-polysiloxanic films as supports for cell cultures but also for the immobilization of biomolecules application (especially DNA, RNA) which involves contact with the aqueous environment, a study of the surface properties of these compounds was carried out by evaluating the contact angle of dry and wet surface of the samples. This study was completed and correlated with AFM behavioural studies of surfaces under aqueous media. The studied samples show a dynamic surface that can be controlled, reorganization of the polymer chains taking place depending on the chemical structure.
Keywords: contact angle, nucleobases, AFM, azo-polysiloxanes, aqueous environment.

Preliminary Study on the Interaction of Skin Microbes in the Development of Cosmetic and Textile Products: A Review

ABDOURAMANE NSANGOU, Department of Mechanical Engineering, ENSET, University of Douala, BP 1872, Douala, Cameroon
DOINA SIBIESCU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania, dsibiesc@tuiasi.ro
DYDIMUS NKEMAJA EFEZE, HTTTC Bambili-University of Bamenda, Cameroon
PIERRE MARCEL ANICET NOAH, Department of Mechanical Engineering, ENSET, University of Douala, BP 1872, Douala, Cameroon
FABIEN EBANDA BETENE, Department of Mechanical Engineering, ENSET, University of Douala, BP 1872, Douala, Cameroon
VALERY HAMBATÉ GOMDJÉ, Departments of Textile and Leather Engineering, ENSPM, University of Maroua, Cameroon

pages 47 - 53   Download
Abstract
This work, which aims at realizing a synthesis of the knowledge on cutaneous microbes, shows that the skin is made up of pathogenic microbes and commensal microbes. The resident or commensal microbes are defenders of the skin and are ready to compete for nutrients and available space. Therefore, pathogenic microorganisms will not be able to settle and grow. The textile designer, in his search for an antimicrobial textile, should not be satisfied with the ability to inhibit skin microbes. He should investigate whether his textile promotes the balance of the commensal flora before testing the inhibition of the transient flora. For this reason, it is desirable to know the skin flora before embarking on the implementation of antimicrobial textiles.
Keywords: textiles, antimicrobial, pathogenic microbes, commensal microbes

Sustainable Management, Treatment and Recovery of Waste in an European Context: Urban Mining and the Circular Economy

MIHAELA DAVID, “Gheorghe Asachi” Technical University of Iasi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iasi, Romania
MARIA GAVRILESCU, “Gheorghe Asachi” Technical University of Iasi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iasi, Romania, Academy of Romanian Scientists, Bucharest, Romania, mgav@tuiasi.ro

pages 55 - 77   Download
Abstract
The paper provides an overview of waste management alternatives in the European framework of the circular economy model, with emphasis on the use of waste as secondary sources for the recovery of raw materials and materials, especially critical raw materials and highlighting the importance of economic and environmental impact of this approach. In this context, the following were taken into account: analysis of European urban waste management practices; highlighting the relevance of waste recovery in the context of the circular economy; recovery of critical raw materials (CRM) from specific waste, as secondary sources of raw materials. In the last part of the paper, a series of methods for the recovery of secondary and critical raw materials from waste were highlighted, analyzing the case of recovery of cobalt from secondary resources, such as waste lithium batteries, as important for lithium and a few other critical materials, as well.
Keywords: critical raw materials, recovery, recycling, secondary resources, waste.

An Overview on Phytoremediation as a Promising Technology for Environmental Depollution

RALUCA-MARIA ȚÂBULEAC, “Gheorghe Asachi” Technical University of Iasi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iasi, Romania
MARIA GAVRILESCU, “Gheorghe Asachi” Technical University of Iasi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iasi, Romania, Academy of Romanian Scientists, Bucharest, Romania, mgav@tuiasi.ro

pages 79 - 108   Download
Abstract
The paper develops a succinct analysis of the phytoremediation process of soils polluted with heavy metals. A number of basic aspects regarding the pollution of soils with heavy metals and the consequences of this phenomenon are presented. Also, the mechanisms by which some plants absorb heavy metal ions are described, a series of studies are presented in which different categories of plants were used as hyperaccumulators to remove heavy metals from the soil and possibilities to intensify phytoremediation. Based on information from the literature, the removal of heavy metal ions (or associated with this group of chemical elements) from the soil, such as cadmium, arsenic, mercury, selenium was explored. The analysis presented in the paper could support and justify the application of phytoremediation as an alternative for environmental remediation in friendly conditions, with low costs and without additional negative impacts on the environment.
Keywords: Brassicaceae, heavy metals, hyperaccumulator, rhizosphere, soil.

Natural carriers for bacterial immobilization used in bioremediation

EMANUEL GHEORGHIȚĂ ARMANU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
IRINA VOLF, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania, iwolf@tuiasi.ro

pages 109 - 122   Download
Abstract
In the last few decades, the environment has been drastically polluted due to the fast industrialization and other anthropic activities. As a boomerang effect, different areas around the world started to shift their original state to one where life itself is continuously diminished, mostly resulting from hazardous circumstances. Microorganisms, in particular bacterial strains have a key role in the bioremediation process due to their efficiency, friendly-environment effect and cheap cost of use. Bioremediation started traditionally using just free cells as a decontaminating tool, however, in couple of years, immobilized microorganisms gained a lot of attention due to their higher stability, retention in time and biotransformation efficiency. Aforementioned immobilization can be realized either on natural or synthetic carriers. The main goal of this paper is to summarize and bring in the spotlight some relevant data regarding the microbial immobilization on specific natural carriers (derived from biomass conversion) and its importance for environmental remediation.
Keywords: feedstock, porous materials, persistent organic pollutants, microbial biofilm, bioremediation.

Crystal Violet Dye Adsorption on Raspberry Leaves Powder - Kinetic and Thermodynamic Studies

GIANNIN MOSOARCA, Faculty of Industrial Chemistry and Environmental Engineering, Politehnica University Timisoara, Romania, giannin.mosoarca@upt.ro 
COSMIN VANCEA, Faculty of Industrial Chemistry and Environmental Engineering, Politehnica University Timisoara, Romania
SIMONA POPA, Faculty of Industrial Chemistry and Environmental Engineering, Politehnica University Timisoara, Romania
SORINA BORAN, Faculty of Industrial Chemistry and Environmental Engineering, Politehnica University Timisoara, Romania
MARIA ELENA RADULESCU‑GRAD, “Coriolan Dragulescu” Institute of Chemistry, Romanian Academy, Timisoara, Romania

pages 123 - 136   Download
Abstract
In this study, kinetics and thermodynamics of crystal violet dye adsorption onto raspberry leaves powder was investigated. The effect of contact time, temperature and ionic strength was studied. The values of the equilibrium time and the experimental adsorption capacity were better that values for other similar adsorbents obtained from vegetal wastes. The thermodynamic study showed that the adsorption process is endothermic, spontaneous and favourable, and physical adsorption is the main mechanism implied in the dye retention on the adsorbent surface.
Keywords: adsorption, crystal violet, raspberry leaves, contact time, thermodynamic parameters.