scholarly journals Preparation of Cellulose/Chitin Blend Materials and Influence of Their Properties on Sorption of Heavy Metals

2021 ◽  
Vol 13 (11) ◽  
pp. 6460
Author(s):  
Dao Zhou ◽  
Hongyu Wang ◽  
Shenglian Guo
Keyword(s):  
Mechanical Properties ◽  
Heavy Metals ◽  
Water System ◽  
Tensile Tests ◽  
Atomic Absorption Spectrophotometry ◽  
Scanning Electron Micrographs ◽  
Mesh Structure ◽  
Chitin Content ◽  
Sorption Ability ◽  
Kinetics Of

A series of biodegradable cellulose/chitin materials (beads and membranes) were successfully prepared by mixing cellulose with chitin in an NaOH/thiourea–water system and coagulation in a H2SO4 solution. The effects of chitin content on the materials’ mechanical properties, morphology, structure, and sorption ability for heavy metal ions (Pb2+, Cd2+, and Cu2+) were studied by tensile tests, scanning electron micrographs, Fourier transform infrared spectroscopy, and atomic absorption spectrophotometry. The results revealed that the cellulose/chitin blends exhibited relatively good mechanical properties, a homogeneous, microporous mesh structure, and the existence of strong hydrogen bonds between molecules of cellulose and chitin when the chitin content was less than 30 wt%, which indicated a good compatibility of the cellulose/chitin materials. Furthermore, in the same chitin content range, Pb2+, Cd2+, and Cu2+ can be adsorbed efficiently onto the cellulose/chitin beads at pH0 = 5, and the sorption capacity of the beads is more than that of chitin flakes. This shows that the hydrophilicity and microporous mesh structure of the blends are favorable for the kinetics of sorption. Preparation of environmentally friendly cellulose/chitin blend materials provides a simple and economical way to remove and recover heavy metals, showing a potential application of chitin as a functional material.

Waste cooking oils as processing aids for eco-sustainable elastomeric compounding

2021 ◽  
pp. 147776062110289
Author(s):  
Valeria Cherubini ◽  
Francesca Romana Lamastra ◽  
Mario Bragaglia ◽  
Francesca Nanni
Keyword(s):  
Mechanical Properties ◽  
Good Practice ◽  
Tensile Tests ◽  
Rheological Characterization ◽  
Mineral Oils ◽  
Waste Oils ◽  
Waste Cooking Oils ◽  
Cooking Oils ◽  
Kinetics Of ◽  
Processing Aids

This work focuses on the replacement of mineral oils with bio-based waste cooking oils in rubber compounding. Two different waste cooking oils from potatoes and chicken frying process were analyzed by means of chemical and rheological tests to evaluate the chemical composition, the oxidative stability and the viscosity. Waste oils have been introduced in elastomeric compounds as substitute for typical processing aids (i.e. lubricants). Cure kinetics of rubber compounds was studied by rheological characterization. Mechanical properties of vulcanized samples were determined by means of tensile tests, hardness tests and dynamic mechanical analysis. The waste oils showed a rheological behavior very similar to the mineral oils conventionally employed in rubber manufacturing leading to almost the same processability of the resulting compound. The waste oils did not significantly affect the vulcanization kinetics of the rubber compound, as expected for conventional lubricants. Waste cooking oils and mineral oil show analogous influence on mechanical properties of cured compounds. At increasing oil content, the elongation at break and the tensile strength increased whereas the values of Elastic Modulus at 100% strain, the Storage Modulus and Shore A Hardness decreased with respect to the oil-free sample. These results are very promising, confirming the possibility to replace the mineral oils, in a good practice of circular economy.

scholarly journals Use of The Eggshells in Removing Heavy Metals from Waste Water - The Process Kinetics and Efficiency

2019 ◽  
Vol 26 (1) ◽  
pp. 165-174 ◽  
Author(s):  
Joanna Makuchowska-Fryc
Keyword(s):  
Waste Water ◽  
Heavy Metals ◽  
Flue Gas ◽  
Waste Product ◽  
Atomic Absorption Spectrophotometry ◽  
Main Element ◽  
Flame Atomic Absorption Spectrophotometry ◽  
Heavy Metal Cations ◽  
Flame Atomic Absorption ◽  
Kinetics Of

Abstract Studies of the efficiency of Ni, Cu and Cd cations removal from water solutions were carried out, with the use of clay limestone, hen eggshells from eggs for consumption and hen eggshells after hatching, which main element is calcium carbonate. Hen eggshells are a waste product, which can be used as a substitute of clay limestone in removing heavy metals from wet flue gas desulphurisation installation. Mixed solutions of Ni, Cu and Cd were used in the research, with the composition similar to the waste water from wet flue gas desulphurisation installation: Ni (0.009-0.053 mmol/dm3), Cu (0.008-0.057 mmol/dm3) and Cd (0.003-0.008 mmol/dm3). The metals were determined by flame atomic absorption spectrophotometry (F-AAS). Kinetics of the process was analysed and equilibrium parameters were estimated, taking into consideration changes of the solutions pH during the process duration. It was demonstrated that the dominating mechanism of cations removal is their binding in hydroxides and carbonates. The studies demonstrated comparable characteristics of hen eggshells versus clay limestone, in the context of their application in removal of heavy metal cations from solutions.

Effects of Retained Austenite Stability on Mechanical Properties of High Strength TRIP Steel

2012 ◽  
Vol 602-604 ◽  
pp. 287-293
Author(s):  
Zhi Feng Li ◽  
Ren Yu Fu ◽  
Qing Shan Li
Keyword(s):  
Mechanical Properties ◽  
Trip Steel ◽  
Retained Austenite ◽  
Mechanical Stability ◽  
High Strength ◽  
Tensile Tests ◽  
Transformation Kinetics ◽  
Austenite Stability ◽  
Kinetics Of ◽  
Strength And Ductility

Mechanical stability of retained austenite and its effect on mechanical properties of high strength TRIP steel were studied by means of OM, SEM, TEM, XRD, and mechanical testing after various heat treatments. Results revealed that the film-type retained austenite located between bainite laths with high carbon content showed gradual martensitic transformation with strain, demonstrating a good TRIP effect. Samples annealed at 800°C and held at 420°C showed an optimum value of strength and ductility product up to 18381.2MPa%. Transformation kinetics of the retained austenite were evaluated through tensile tests and fitted by the function y=0.86-0.86×exp(-Ax). The fitting results were good.

Polymorphism of p-450 cytochrome detoxication genes in adolescents depending on the degree of contamination of the organism by heavy metals

2020 ◽  
Vol 99 (5) ◽  
pp. 478-482
Author(s):  
N. P. Setko ◽  
A. G. Setko ◽  
Ekaterina V. Bulycheva ◽  
A. V. Tyurin ◽  
E. Yu. Kalinina
Keyword(s):  
Heavy Metals ◽  
Environmental Factors ◽  
Heavy Metal Contamination ◽  
Atomic Absorption Spectrophotometry ◽  
The Body ◽  
Lead And Cadmium ◽  
Cyp2b6 Gene ◽  
Cytochrome P 450 ◽  
Gene Cyp1a1 ◽  
Group 1

Introduction. Changes in the body of children and adolescents aimed at adapting to environmental factors are determined by genetic polymorphism in xenobiotic biotransformation genes, determining the degree of susceptibility of the child’s body to pollutants, which is the basis of modern personalized preventive medicine when managing risks to the health of the child population under the influence of environmental factors. Material and methods. Trace elements, including heavy metals, lead and cadmium, were determined in the hair of 256 practically healthy teenagers by atomic absorption spectrophotometry. Depending on the level of content of the latter, two groups of adolescents were formed to determine six genes of the cytochrome P-450 family. Group 1 consisted of adolescents whose cadmium lead content exceeded the average Russian indices. The second group included adolescents whose heavy metals were above the level of average Russian standards. Results. Studies have shown that in adolescents of the 1st group, compared with the data of adolescents of the 2nd group, an increase in the number of carriers of two mutant alleles at the locus rs 1048943 (gene CYP1A1) is 3.08 times, rs 464621 (gene CYP1A1) is 1. 8 times; locus rs 2069522 (CYP1A2 gene) 3.63 times; locus rs 1799853 (CYP2C9 * 2 gene) 4.5 times; locus rs 1057910 (gene CYP2C9 * 3) 3.8 times and locus rs 2279343 (gene CYP2B6) 4.25 times. Moreover, carriers of two normal alleles in adolescents of the first group at the locus rs 1048943 (gene CYP1A1) were 5.14 times; locus rs 2279343 (CYP2B6 gene) was 6.5 fold less than among adolescents of the 2nd group; and at the locus rs 464621 (gene CYP1A1), rs 2069522 (gene CYP1A2), rs 1799853 (gene CYP2C9 * 2), rs 1057910 (gene CYP2C9 * 3) there were no carriers of normal homozygotes. Conclusion. Group 1 adolescents with heavy metal contamination of the body are carriers significantly in a greater number of pathological mutations in the genes of the cytochrome P-450 detoxification system in comparison with data from group 2 adolescents.

Study of the Cu(II) removal from aqueous solutions by adsorption on titania

2013 ◽  
Vol 12 (3) ◽  
pp. 239-247
Keyword(s):  
Heavy Metals ◽  
Ionic Strength ◽  
Toxic Metals ◽  
Low Cost ◽  
Lateral Interaction ◽  
Tio2 Surface ◽  
High Toxicity ◽  
Removal Of Heavy Metals ◽  
Solution Parameters ◽  
Kinetics Of

The removal of heavy metals from wastewaters is a matter of paramount importance due to the fact that their high toxicity causes major environmental pollution problems. One of the most efficient, applicable and low cost methods for the removal of toxic metals from aqueous solutions is that of their adsorption on an inorganic adsorbent. In order to achieve high efficiency, it is important to understand the influence of the solution parameters on the extent of the adsorption, as well as the kinetics of the adsorption. In the present work, the adsorption of Cu(II) species onto TiO2 surface was studied. It was found that the adsorption is a rapid process and it is not affected by the value of ionic strength. In addition, it was found that by increasing the pH, the adsorbed amount of Cu2+ ions and the value of the adsorption constant increase, whereas the value of the lateral interaction energy decreases.

Assessment of heavy metals in tobacco of cigarettes commonly sold in Ethiopia

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Heavy Metals ◽  
Trace Metals ◽  
Atomic Absorption Spectrophotometry ◽  
Epidemiological Studies ◽  
Cigarette Tobacco ◽  
Absorption Spectrophotometry ◽  
Wet Digestion ◽  
Metal Contents ◽  
Cu And Zn ◽  
Significant Flux

A significant flux of heavy metals, among other toxins, reaches the lungs through smoking. This study reports Cd, Pb, Cu and Zn contents in tobacco of 11 brands of cigarette commonly sold in Ethiopia. The heavy metals were determined by atomic absorption spectrophotometry after wet digestion of cigarette tobacco using HNO3 and H2O2. The concentration of trace metals in the cigarettes ranged (mean) (μg/g), Cd: 1.3−7.6 (2.48±0.32), Pb: 0.50−12.50 (6.24±2.2), Cu: 2.89−25.35 (13.70±4.12) and Zn: 24.40−62.55 (36.22±7.50) while Ni was not detected in all the eleven brands of cigarettes. Comparable levels of trace metals were obtained in the tobacco of both imported and Ethiopian cigarettes. The average trace metal contents of cigarettes available in Ethiopia were Cd 1.82±0.39, Pb 4.23±0.97, Cu 10.2±3.1 and Zn 28.2±7.8 μg/cigarette and a person who smokes 20 cigarettes per day is estimated to increase his/her daily Cd, Pb, Cu and Zn retention by approximately 0.036, 0.085, 0.204, 0.564 mg/day, respectively. The results indicate that smoking and exposure to cigarette smoke is a serious problem to be taken into account when carrying out epidemiological studies on human exposure to trace metals.

Elaboration and Characterization of the Properties of Refractory Cr Base Alloys

2010 ◽  
Vol 72 ◽  
pp. 46-52 ◽  
Author(s):  
Laurent Royer ◽  
Stéphane Mathieu ◽  
Christophe Liebaut ◽  
Pierre Steinmetz
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Molten Glass ◽  
Energy Production ◽  
Creep Properties ◽  
Refractory Alloys ◽  
Industrial Use ◽  
Kinetics Of ◽  
Selection Of

For energy production and also for the glass industry, finding new refractory alloys which could permit to increase the process temperatures to 1200°C or more is a permanent challenge. Chromium base alloys can be good candidates, considering the melting point of Cr itself, and also its low corrosion rate in molten glass. Two families of alloys have been studied for this purpose, Cr-Mo-W and Cr-Ta-X alloys (X= Mo, Si..). A finer selection of compositions has been done, to optimize their chemical and mechanical properties. Kinetics of HT oxidation by air, of corrosion by molten glass and also creep properties of several alloys have been measured up to 1250°C. The results obtained with the best alloys (Cr-Ta base) give positive indications as regards the possibility of their industrial use.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

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