2020, Volume 66(70), Issue 4 (December)

Contents

pages 1- 8   Download

Multiple linear regression (MLR) models used for the prediction of excess thermodynamic properties based on experimental determination of refractive index

IULIANA BÎRGĂUANU, "Gheorghe Asachi" Technical University, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection, iuliana.birgauanu@yahoo.com
CĂTĂLIN LISA, "Gheorghe Asachi" Technical University, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection
SILVIA CURTEANU, "Gheorghe Asachi" Technical University, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection
GABRIELA LISA, "Gheorghe Asachi" Technical University, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection

pages 9 - 21   Download
Abstract
In engineering, it is very important to have thorough knowledge of the thermodynamic and conveying properties of fluid mixtures, as they are mainly used to study the interactions that occur in fluids with several components, as well as to design various equipment for separation by distillation, fractional distillation and solvent extraction, and to achieve a scientific approach of the risk factors that affect separation processes. Our research group used the statistical processing of experimental data by the multiple linear regressions (MLR) method in order to estimate the excess molar volume starting from the experimental values of the refractive index for ternary systems. In this paper we will prove that this type of experimental data processing could also be used to predict other excess thermodynamic properties such as excess viscosity and excess surface tension (PE). In order to achieve this goal, we will use both the literature data and experimental data obtained in our laboratory on the thermodynamic properties of certain fluid mixtures. The created mathematical models correlate the excess thermodynamic properties with the refractive index, the standard temperature and the fluid mixture composition: PE= A0 + A1X1 + A2X0 + A3(T/298.15) + A4n, where X1 and X2 are the molar fractions, T is the temperature expressed in Kelvin and n is the refractive index. These models are extremely useful in practice. The refractive index can be easily determined, with rather good accuracy and low substance consumption. These mathematical models also allow the determination of other properties, such as density, viscosity and surface tension, which are more difficult to determine by experimental methods.
Keywords: MLR models, density, viscosity, surface tension, refractive index, multicomponent systems

Stabilization of w/o emulsions using ecofriendly emulsifiers

EMIL IOAN MUREȘAN, "Gheorghe Asachi" Technical University of Iasi, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection, Romania, eimuresan@yahoo.co.uk
ANGELA DĂNILĂ, "Gheorghe Asachi" Technical University of Iasi, Faculty of Industrial Design and Business Management, Department of Chemical Engineering, Romania

pages 23 - 30   Download
Abstract
An ecological emulsifier, containing a mixture of fatty acid esters was prepared by the transesterification reaction of sunflower oil with ethanol. The reaction was catalysed by CaO resulted from the calcination of the eggshells. Several emulsions consisting of sunflower oil and water, which differ from each other by the ratio between phases (70% U / 30% A, 60% U / 40% and 50% U / 50% A) and by the concentration of emulsifier (2%, 4% and 6% respectively with respect to the vegetable oil mass), were prepared. The influence of the emulsifier concentration and of the ratio between phases on the stability of the emulsions were studied. The microscopic images, the stability index values and the turbidity's values showed that the most stable is the emulsion containing 60% U / 40% A and 4% emulsifier.
Keywords: emulsion stability, turbidity, vegetable oil, eggshell, microscopic image

Natural dye extraction from Pelargonium roseum plants using ultrasound method

DOINA SIBIESCU, "Gheorghe Asachi" Technical University of Iași, România, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection, dsibiesc@ch.tuiasi.ro
MIHAELA VIZITIU, "Gheorghe Asachi" Technical University of Iași, România, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection

pages 31 - 38   Download
Abstract
Dyes derived from natural sources have been used since ancient times in households and in various fields. Subsequently, synthetic dyes were synthesized, but in terms of toxicity, the variant in which the existence of substances harmful to the environment is not a problem is the first category. The aim of this paper is to discover a better solid-liquid extraction technique to avoid the infiltration of dyes found in groundwater following the discharge of wastewater in which they are contained. A source of natural dyes is represented by plant materials that are used in plant research applications, in food, as well as in the paint industries. These could be Green wattle bark, Marigold flowers, Pomegranate rinds, Pelargonium roseum, 4’o clock plant flowers, Cocks Comb flowers and more like these. We used Pelargonium roseum plants. The influence of ultrasound on the extraction of natural dyes from this material plant as a source of dyes has been studied in comparison with the process of magnetic stirring. Analytical studies, such as UV-VIS spectrophotometry and gravimetric analysis, were performed on the extract. In this regard, the present paper aims at screening the locally available natural dye yielding plants for dyeing purpose. The effect of power ultrasound in the extraction of natural dyes has been studied. Improving the efficiency of dye extraction from plant materials with 87.5% by using ultrasound has led to the conclusion that this method is much faster and more efficient than magnetic stirring.
Keywords: Pelargonium roseum, dye solid–liquid extraction, ultrasound sonochemistry

Biosorbents based on microorganisms

ALEXANDRA CRISTINA BLAGA, "Gheorghe Asachi" Technical University of Iași, Romania, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection
IOANA LUIZA HORCIU, "Gheorghe Asachi" Technical University of Iași, Romania, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection
CARMEN ZAHARIA, "Gheorghe Asachi" Technical University of Iași, Romania, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection
LĂCRĂMIOARA RUSU, "Vasile Alecsandri" University of Bacău, Faculty of Engineering
CRISTINA GRIGORAS, "Vasile Alecsandri" University of Bacău, Faculty of Engineering
DANIELA ȘUTEU, "Gheorghe Asachi" Technical University of Iași, Romania, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection, danasuteu67@yahoo.com

pages 39 - 53   Download
Abstract
Biosorption is a technique used for the removal of not easily biodegradable pollutants from waters (especially metals and dyes), that can use a variety of biomaterials with adsorptive properties including microbial microorganism (algae, bacteria, fungi), but also industrial and agricultural wastes. The biosorption abilities of microbial biomass towards dyes and metal ions have been extensively studied, as these biosorbents are low-cost and ecofriendly materials for water/wastewater treatment applications, and can be chemically modified, via various techniques, or genetically engineered to enhance their biosorption capacity. The functional groups, such as carboxyl, amine and phosphonate of the cell wall constituents (peptidoglycan, manan, chitin and chitosan), offer increase biosorption potentials.
Keywords: biosorption, dyes, immobilization, metals ions, microbial biosorbents, wastewaters

Particle air pollution (PM10) monitoring and public opinion on air quality. A case study in northeastern Romania

BRANIȘTE MIHAELA-VICTORIA, "Gheorghe Asachi" Technical University of Iași, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection, Romania
ȘTEFAN IULIANA, "Gheorghe Asachi" Technical University of Iași, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection, Romania
ANA MELANIA, "Gheorghe Asachi" Technical University of Iași, Faculty of Hydrotechnical Engineering, Geodesy and Environmental Engineering, Romania
UNGA FLORIN, The Cyprus Institute, Climate & Atmosphere Research Center, Nicosia, Cyprus
MARIUS MIHAI CAZACU, "Gheorghe Asachi" Technical University of Iasi, Department of Physics, Romania, cazacumarius@gmail.com

pages 55 - 67   Download
Abstract
Air pollution continues to be a concern for both the scientific community and the general population. Promoting pollution events and the impact they could have on the environment and human health must be an ongoing challenge. This paper presents a case study on ambient air quality by monitoring particle concentrations (PM10) in the northeastern part of Romania. The analysis of a survey on the opinion of the general population regarding air quality is also presented. The research began with our concern about the data issued by the WHO (World Health Organization) which shows that tens of thousands of people are lost, annually, prematurely due to pollution. Experimental data show that in some areas the concentration of PM10 is much exceeded. Moreover, in some areas this concentration is exceeded no less than 82 times in 7 months. At the same time, the survey shows that people believe they are responsible for the well-being of the environment but are not sufficiently informed about the quality of the air they breathe.
Keywords: PM10, air quality, survey

Habilitation thesis summary
Micro- and nanostructured materials with applications in medicine and environmental protection

MARGARETA GABRIELA CIOBANU, "Gheorghe Asachi" Technical University of Iaşi, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection, gciobanu@ch.tuiasi.ro

pages 69 - 72   Download