2022, Volume 68(72), Issue 4 (December)

Contents

pages 1- 8   Download

Bubble Shape Influence on Slug Flow Acceleration Mechanism

EUGENIA TEODORA IACOB-TUDOSE, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Department of Chemical Engineering, Iaşi, Romania, etudose@ch.tuiasi.ro
MASAHIRO KAWAJI, The City College of New York, Grove School of Engineering, USA

pages 9 – 20   Download
DOI: 10.5281/zenodo.7539788
Abstract
A 7.5 cm long solid Taylor bubble with normal (nondeformed) and distorted nose forms was placed in a liquid flowing downward in a vertical tube and the total drag force was measured. For both normal and deformed bubbles, variations in drag force with solid bubble displacement from the tube axis were evaluated and compared. Aside from the steady decrease in drag force from the tube axis to the wall, the deformed nose bubble experienced less drag than the conventional nose bubble, as expected. Changes in the bubble nose shape result in a reduction in drag force. This concept, when combined with the reduction in drag force caused by the bubble's lateral displacement from the vertical pipe axis as described previously (Tudose and Kawaji, 1999; Tudose, 2004), can explain the acceleration of a trailing bubble following another.
Keywords: two-phase flow, pre-coalescence phenomena, Taylor bubble, nose, deformation

Optimization of Process Parameters for Retention of Cd(II) Ions Adsorption from Aqueous Solutions on Clay Materials

BIANCA AZANFIRE, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
LAURA BULGARIU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania, lbulg@ch.tuiasi.ro

pages 21 – 30   Download
DOI: 10.5281/zenodo.7539797
Abstract
Globally, heavy metal pollution is classified as serious environmental problem. Cd(II) ions are commonly encountered pollutants that are toxic to human life, even at low concentration and adsorption is one of the most suited process for this heavy metal ions removal from aqueous solutions. Clay materials have risen as potential options in contrast to conventional adsorbents. The adsorption properties of clay in retention of Cd(II) from aqueous solutions have been studied in batch technique. The amount of adsorbed heavy metal ions was determined for the adsorption systems as a function of adsorbent dose, initial solution pH, initial ion concentration, contact time and temperature. Based on the obtained experimental results, the optimal values of the process parameters are: initial solution pH 7.0, 4.0 g·L-1 adsorbent, 60 minutes of contact time and ambient temperature. These conditions ensure a maximum removal efficiency of Cd(II) ions of 93%.
Keywords: water pollution, heavy metals, cadmium ions, clay materials, adsorption      

Aloe Vera Gel as a Biomordant in the Finishing of Vegetable Textiles: A Review

ABDOURAMANE NSANGOU, Department of Mechanical Engineering, ENSET, University of 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 EFEZE NKEMAJA, HTTTC Bambili-University of Bamenda, Cameroon
PIERRE MARCEL ANICET NOAH, Department of Mechanical Engineering, ENSET, University of Douala, Cameroon
FABIEN EBANDA BETENE, Department of Mechanical Engineering, ENSET, University of Douala, Cameroon
VALERY HAMBATÉ GOMDJÉ, Departments of Textile and Leather Engineering, ENSPM, University of Maroua, Cameroon

pages 31 – 36   Download
DOI: 10.5281/zenodo.7539811
Abstract
During the dyeing process, the color is maintained over time due to the mordant that creates a strong bond between the dye and the fiber. The most common chemical mordants are potassium alum, tartar cream, tin chloride, cupric sulfate, ferrous sulfate and potassium dichromate. The current trend of increasing nature protection requires the use of clean products for the textile finishing sector and the biodegradability of textiles. Aloe vera is known to be a natural mordant. Based on data from the literature, the authors of this paper aimed to identify several behaviors between aloe vera gel and textiles. Aloe vera gel macerated on sida rhombifolia shows (with the residue in the oven) after IR analysis a disappearance of peak 1029 cm-1 which indicated the degree of C-O-C bonds of cellulose present in the modification of sida rhombifolia. The active ingredients of Aloe vera have also been shown to bind to the hydroxyl groups of cotton, which is a crosslinking agent for macromolecules.
Keywords: Aloe vera gel, finishing, vegetable textile, biomordant    

Application of Response Surface Method for Optimization of Eriochrome Black T Removal by Adsorption

LOREDANA PINTILIE, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania, pintilie.loredana88@yahoo.com
ANDREEA-EMA SAVA, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
ELENA NICULINA DRĂGOI, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
CARMEN TEODOSIU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania

pages 37 – 52   Download
DOI: 10.5281/zenodo.7539854
Abstract
This study used Response Surface Methodology (RSM) to optimize Eriochrome Black T adsorption on activated carbon. Based on the Design of Experiments approach, static and static-stirred experiments were planned and conducted. Each set had 15 experiments and three replications at the center point. Experiments were conducted at room temperature with no pH adjustments. In static conditions, the maximum removal efficiency was 63.01%, while in static-stirred conditions, it was 78.18%. MINITAB 17.1.0 was used to analyze and interpret the experimental results. Linear, factorial, quadratic, and cubic statistical models were developed to describe static and static-stirred process parameter interactions. In addition, 3-D response surface plots and 2-D contour plots were used to show parameter efficiency. The RSM analysis of process parameters and their influence on retention yield increased removal efficiencies up to 85.20% in the static regime and to complete removal in the static-stirred regime, demonstrating optimization's ability to improve process performances.
Keywords: adsorption, activated carbon, Eriochrome Black T, optimization, Response Surface Methodology    

Natural Extracts Used to Prevent Microbial Contamination of Cosmetic Products

MIHAIL VÎNAGĂ, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
СORINA СERNATESСU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania
ALEXANDRA СRISTINA BLAGA, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Iaşi, Romania, aсblaga@tuiasi.ro

pages 53 – 68   Download
DOI: 10.5281/zenodo.7539881
Abstract
The antimicrobial effect of some plants has been known since ancient times and is the subject of scientific investigations even today, being sometimes the reason for their use in cosmetics. Over the years, a deeper understanding of the behavior of skin and plants has become available, drawing increasingly complex images. Plants are complex organisms that produce different metabolites as response to the environment in which they live, and plant extracts and essential oils (when applied to the skin) interact with skin cells and increase the well-being and appearance of the skin. Ethnobotanical studies and physiсo-сhemiсal analyzes have presented a rich inventory of plants with the potential to enrich and improve modern cosmetics. Recently, a number of laboratory studies have revealed the efficiency of plant extracts and phytochemicals as antimicrobials. The most used plant materials that provide antimicrobial protection includes: essential oils (rosemary, tea tree, turmeriс and rosehip seed oil), plant extraсts (rosemary, rosehip, sage, lemon balm, green tea, Kaempferia galanga, Neem leaf and Horseradish extract), isolated oil and phytoсhemiсals such as cinnamate, benzoate, eugenol.
Keywords: Natural extracts, cosmetics, bioactive compounds, antimicrobial effect, plants

An Overview of Natural Organic Matter Removal by Coagulation in Drinking Water Treatment

RAMONA CIOBANU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Department of Environmental Engineering and Management, Iaşi, Romania
MARCELA MIHAI, “Petru Poni” Institute of Macromolecular Chemistry, Iaşi, Romania
CARMEN TEODOSIU, “Gheorghe Asachi” Technical University of Iaşi, “Cristofor Simionescu” Faculty of Chemical Engineering and Environmental Protection, Department of Environmental Engineering and Management, Iaşi, Romania, cteo@ch.tuiasi.ro

pages 69 – 92   Download
DOI: 10.5281/zenodo.7539887
Abstract
Natural organic matter (NOM) is equivalent to the total organic substances resulting from bacterial decomposition of animal and vegetal matter. NOM is naturally found in most surface water sources used for drinking water supply, and can have significant impacts on human health if it is not removed. Apart from the fact that they create problems with taste, odour and color of raw water, NOM species are precursors of disinfection by-products, which in turn have a negative effect on human health. Most of the NOM can be removed by coagulation and flocculation followed by sedimentation and filtration, processes that are considered the most common and economically feasible drinking water treatments. This study presents an overview of recently published investigations regarding NOM removal in drinking water treatment with different coagulant types and treatment techniques in relation to coagulation.
Keywords: coagulation, flocculation, natural organic matter    

The Use of Calcium Carbonate as a Foaming Agent of Glass Waste for Unconventional Manufacture of a Light Glass Foam with Adequate Mechanical Strength

LUCIAN PĂUNESCU, Daily Sourcing & Research SRL Bucharest, Romania, lucianpaunescu16@gmail.com
SORIN MIRCEA AXINTE, Daily Sourcing & Research SRL Bucharest, Romania; Department of Applied Chemistry and Materials Science, University “Politehnica” of Bucharest, Romania
FELICIA COSMULESCU, Cosfel Actual SRL Bucharest, Romania
BOGDAN VALENTIN PĂUNESCU, Consitrans SA Bucharest, Romania

pages 93 – 106   Download
DOI: 10.5281/zenodo.7539952
Abstract
The paper presents experimental results of manufacturing a glass foam of glass waste with excellent thermal insulation properties and simultaneously relatively high compressive strength. The foaming agent was calcium carbonate (CaCO3) and borax was used as a fluxing agent. The achievement of the objective involved finding an appropriate correlation between the foaming agent and the fluxing agent to obtain the desired characteristics. The research originality was the use of the own technique of predominantly direct microwave heating that ensures a high energy efficiency of the thermal process. The optimal foam sample was made with 1.1% CaCO3 and 2% borax, by the heat treatment of glass waste at 825ºC. The foamed product characteristics were: apparent density of 0.18 g/cm3, porosity of 91%, thermal conductivity of 0.042 W/m·K and compressive strength of 2.6 MPa. The high energy efficiency of the heating technique led to a very low specific energy consumption (0.67 kWh/kg).
Keywords: glass foam, microwave heating, glass waste, calcium carbonate, borax