scholarly journals Kinetics of Arsenic Removal in Waste Acid by the Combination of CuSO4 and Zero-Valent Iron

Processes ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 401 ◽  
Author(s):  
Yunhao Xi ◽  
Yongguang Luo ◽  
Jingtian Zou ◽  
Jing Li ◽  
Tianqi Liao ◽  
...  
Keyword(s):  
Arsenic Removal ◽  
Reaction Order ◽  
Kinetic Studies ◽  
Zero Valent Iron ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Before And After ◽  
Shrinking Core ◽  
Kinetics Of ◽  
Waste Acid

In this study, we investigated the kinetics of arsenic removal from waste acid by the combination of zero-valent iron (ZVI) and CuSO4. ZVI samples were characterized by X-ray diffraction and scanning electron microscopy before and after arsenic removal; the results showed that after the arsenic removal reaction, As2O3 and magnetite phases were detected on the surface of these samples. Kinetic studies were carried out under different reaction temperatures, with different CuSO4 concentrations, and with different iron to arsenic molar ratios (Fe/As). The kinetic data of the arsenic removal were fitted to different kinetic models. The fitting results showed that the arsenic removal process could be described by the shrinking core model, controlled by residual layer diffusion. The apparent activation energy of the reaction was 9.0628 kJ/mol, the reaction order with the CuSO4 concentrations was −0.12681, and the reaction order with the molar ratio of iron to arsenic (Fe/As) was 3.152.

Vulcanization of Elastomers. 25. Natural Rubber and Synthetic Elastomers with Sulfur and Sulfenamides. I

1960 ◽  
Vol 33 (3) ◽  
pp. 846-856 ◽  
Author(s):  
Walter Scheele ◽  
Horst-Eckart Toussaint ◽  
Yoan-Kun Chai
Keyword(s):  
Reaction Order ◽  
Molar Ratio ◽  
Reactive Intermediate ◽  
Sulfur Concentration ◽  
Kcal Mole ◽  
Experimental Conditions ◽  
Sulfur Vulcanization ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Time Plot

Abstract The sulfur vulcanization of Perbunan N 2818 (acrylonitrile-butadiene) was investigated in the presence of N-cyclohexyl-2-benzothiazolylsulfenamide (CZ) at different temperatures and various concentrations of reactants. The following were found : 1. The decreasing sulfur concentration vs. time plot followed the 0.8th order under all experimental conditions and an activation energy of 28.2 kcal/mole was calculated. 2. When using the cyclohexylammonium salt of MBT as accelerator, sulfur decrease proceeds at the same rate as with CZ. 3. It was concluded from 1 and 2 that even in the presence of CZ, the ammonium salt was the actual accelerator, which forms during the scorch or induction period through reaction of CZ with the rubber. 4. In view of the discrepancy found in the relation of reaction order with respect to time and concentration of reactants, the formation of a reactive intermediate is postulated; the analogy between the kinetics of sulfenamide accelerated sulfur vulcanization, and those accelerated with MBT as well as DPG is pointed out. 5. In connection with 3 the dependence of starting rate as well as rate constant of 0.8th order of the decreasing sulfur concentration on the molar ratio of CZ/S8 and on the sulfur starting concentration is discussed.

scholarly journals Application of the Shrinking-Core Models for Determination of Dissolution Kinetics of Mn and Zn from Spent Zinc–Carbon Battery Powder in Organic Acid Solution

2019 ◽  
Vol 27 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Tevfik Agacayak ◽  
Hasan Ali Taner
Keyword(s):  
Acetic Acid ◽  
Acid Solution ◽  
Acetic Acid Solution ◽  
Dissolution Kinetics ◽  
Kinetic Studies ◽  
Product Layer ◽  
Different Temperatures ◽  
Shrinking Core ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

Abstract In this study, dissolution kinetics of manganese and zinc from spent zinc–carbon batteries in acetic acid solution was investigated. To determine the kinetics of dissolution of manganese and zinc, shrinking core model was applied to dissolution recoveries obtained at different temperatures. As a result of kinetic studies, it was determined that manganese and zinc were dissolved in acetic acid solution by diffusion from product layer and then activation energies (Ea) were calculated.

Oxidative Degradation and Kinetics of Trichloroethylene by Thermally Activated Persulfate

2014 ◽  
Vol 675-677 ◽  
pp. 547-550
Author(s):  
Jun Jie Yue ◽  
Xiao Qiao Zhu ◽  
Yu Ting Wang ◽  
Yu Qin Zhang ◽  
Li Zhao ◽  
...  
Keyword(s):  
Oxidative Degradation ◽  
Chemical Oxidation ◽  
Molar Ratio ◽  
Pseudo First Order Reaction ◽  
In Situ Chemical Oxidation ◽  
First Order ◽  
Molar Ratios ◽  
Thermally Activated ◽  
Kinetics Of

In situ chemical oxidation with persulfate (PS) anion (S2O82-) is a viable technique for remediation of groundwater contaminants such as trichloroethylene (TCE). This laboratory study investigated the use of the oxidant sodium PS for the chemical oxidation of TCE at different conditions to determine the influence of temperature, pH, and the PS/TCE molar ratio. Experiments revealed that higher temperatures, lower pH, and higher PS/TCE molar ratios were to the benefit of TCE oxidation by PS. By investigating the reaction kinetics, the degradations of contaminant can be described by use of pseudo-first-order reaction. At the temperatures ranging from 25°C to 40°C, the activation energy for the degradation of TCE was determined to be 85.04 KJ/mol.

Kinetic Studies on Oxidation of Veratryl Alcohol by Laccase-Mediator System. Part 1. Effects of Mediator Concentration

Holzforschung ◽  
2000 ◽  
Vol 54 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Mikhail Yu. Balakshin ◽  
Chen-Loung Chen ◽  
Josef S. Gratzl ◽  
Adrianna G. Kirkman ◽  
Harald Jakob
Keyword(s):  
Kinetic Studies ◽  
Veratryl Alcohol ◽  
Alcohol Oxidation ◽  
Order Rate Constant ◽  
Molar Ratio ◽  
Active Centers ◽  
First Order ◽  
System Part ◽  
Kinetics Of

Summary Kinetics of the laccase-catalyzed oxidation of veratryl alcohol with dioxygen in the presence of 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diamonium salt (ABTS), the mediator, were studied to elucidate the possible reaction mechanism and the role of the mediator in this reaction. The reaction follows a pseudo-first order reaction law. The first order rate constant (κ) is dependent on the Mediator/Substrate (M/S) ratio and has a maximum at M/S molar ratio of 0.15. The kinetic studies show that the mechanism of veratryl alcohol oxidation with dioxygen-laccase-ABTS is rather complex and includes different reaction pathways. The mediator is involved in competitive reactions. It has been suggested that at low mediator concentration, the veratryl alcohol is oxidized via the laccase redox cycle. The mediator acts mostly as a laccase activator at a M/S ratio lower than 0.15. With increasing ABTS concentration with respect to the substrate concentration, ABTS acts increasingly as a cosubstrate competing with the original substrate for active centers of the laccase. This results in inhibition of veratryl alcohol oxidation in the enzyme cycle and increases the role of substrate oxidation by an oxidized mediator.

scholarly journals Physicochemical and Adsorption Characteristics of Divinylbenzene-co-Triethoxyvinylsilane Microspheres as Materials for the Removal of Organic Compounds

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2396
Author(s):  
Alicja Bosacka ◽  
Małgorzata Zienkiewicz-Strzalka ◽  
Małgorzata Wasilewska ◽  
Anna Derylo-Marczewska ◽  
Beata Podkościelna
Keyword(s):  
Organic Compounds ◽  
Spherical Shape ◽  
Kinetic Studies ◽  
Inorganic Materials ◽  
Molar Ratio ◽  
Water And Wastewater Treatment ◽  
Molar Ratios ◽  
X Ray Scattering ◽  
Complementary Techniques ◽  
Saxs Analysis

In this work, organic-inorganic materials with spherical shape consisting of divinylbenzene (DVB) and triethoxyvinylsilane (TEVS) were synthesized and investigated by different complementary techniques. The obtained microspheres may be applied as sorbent systems for the purification of organic compounds from water. The hybrid microspheres combine the properties of the constituents depending on the morphologies and interfacial bonding. In this work, the influence of the molar ratio composition of crosslinked monomer (DVB) and silane coupling agent (TEVS) (DVB:TEVS molar ratios: 1:2, 1:1 and 2:1) on the morphology and quality of organic-inorganic materials have been examined. The materials were analysed using small angle X-ray scattering (SAXS) analysis, low-temperature nitrogen sorption, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to provide information on their structural and surface properties. Moreover, thermal analysis was performed to characterize the thermal stability of the studied materials and the adsorbent-adsorbate interactions, while adsorption kinetic studies proved the utility of the synthesized adsorbents for water and wastewater treatment.

Arsenic Immobilization by Biological Scorodite Crystallization: Effect of High Ferric Concentration and Foreign Seeds

2009 ◽  
Vol 71-73 ◽  
pp. 629-632 ◽  
Author(s):  
Paula González Contreras ◽  
Jan Weijma ◽  
Cees N.J. Buisman
Keyword(s):  
Arsenic Removal ◽  
Removal Rate ◽  
Molar Ratio ◽  
Biological Oxidation ◽  
High Concentration ◽  
Kinetics Of Crystallization ◽  
Iron Oxidizing Bacteria ◽  
Crystallization Effect ◽  
Kinetics Of ◽  
High Arsenic

Biological scorodite is produced at 80°C and 1g L-1 As5+, using iron oxidizing bacteria Acidianus Sulfidivorans, with a molar ratio Fe/As of 1 and without the use of seeds. We investigated the effect of high ferrous concentration, Fe/As higher than 1, and the use of foreign seeds (gypsum) on biological scorodite crystallization. The use of high ferrous concentrations resulted in a retardation of the time of crystallization due to the high concentration of ferric produced by a high biological oxidation. However, ferrous biological oxidation might be controlled to avoid this effect. The use of seeds did not improve the kinetics of crystallization. Nonetheless, a high arsenic removal rate was observed in the presence of seeds probably as a result of the formation of less stable scorodite.

scholarly journals FABRICATION OF Mg-Zn-Al HYDROTALCITE AND ITS APPLICATION FOR Pb2+ REMOVAL

2019 ◽  
Vol 59 (3) ◽  
pp. 260-271 ◽  
Author(s):  
Eddy Heraldy ◽  
Fitria Rahmawati ◽  
Dwi Ardiyanti ◽  
Ika Nurmawanti
Keyword(s):  
Second Order ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Adsorption Efficiency ◽  
Molar Ratios ◽  
Isotherm Adsorption ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
Co Precipitation ◽  
Kinetics Of

The fabrication of Mg-Zn-Al Hydrotalcite (HT) was carried out by the co-precipitation method at various molar ratios. The Mg-Zn-Al HT compound at the optimum molar ratio was then calcined to determine the effect of calcination on the Pb2+ adsorption. The kinetics of the adsorption type was determined by applying pseudo first order and pseudo second order kinetics models. Meanwhile, to investigate the adsorption process, the Freundlich and Langmuir equations were applied to determine the adsorption isotherm. The results showed that the optimum Mg-Zn-Al HT was at a molar ratio of 3 : 1 : 1 with an adsorption efficiency of 73.16 %, while Mg-Zn-Al HT oxide increased the adsorption efficiency to 98.12 %. The optimum condition of Pb2+ removal using Mg-Zn-Al HT oxide was reached at pH 5 and a contact time of 30 minutes. The adsorption kinetics follows the pseudo second order kinetics model with a rate constant of 0.544 g/mg·min. The isotherm adsorption follows the Langmuir isotherm model with a maximum capacity of 3.916 mg/g and adsorption energy of 28.756 kJ/mol.

scholarly journals Fe-FeS2 adsorbent prepared with iron powder and pyrite by facile ball milling and its application for arsenic removal

2017 ◽  
Vol 76 (1) ◽  
pp. 192-200 ◽  
Author(s):  
Xiaobo Min ◽  
Yangwenjun Li ◽  
Yong Ke ◽  
Meiqing Shi ◽  
Liyuan Chai ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Ball Milling ◽  
Photoelectron Spectroscopy ◽  
Arsenic Removal ◽  
Molar Ratio ◽  
Arsenic Adsorption ◽  
Arsenic Uptake ◽  
X Ray ◽  
Before And After ◽  
High Arsenic

Arsenic is one of the major pollutants and a worldwide concern because of its toxicity and chronic effects on human health. An adsorbent of Fe-FeS2 mixture for effective arsenic removal was successfully prepared by mechanical ball milling. The products before and after arsenic adsorption were characterized with scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The adsorbent shows high arsenic removal efficiency when molar ratio of iron to pyrite is 5:5. The experimental data of As(III) adsorption are fitted well with the Langmuir isotherm model with a maximal adsorption capacity of 101.123 mg/g. And As(V) data were described perfectly by the Freundlich model with a maximal adsorption capacity of 58.341 L/mg. As(III) is partial oxidized to As(V) during the adsorption process. High arsenic uptake capability and cost-effectiveness of waste make it potentially attractive for arsenic removal.

scholarly journals KINETIC MODELING STUDY FOR ACYLATION REACTION OF O-XYLENE TO 3,4-DIMETHYLBENZOPHENONE OVER H-BETA

2015 ◽  
Vol 1 (1) ◽  
pp. 89
Author(s):  
Yusnimar
Keyword(s):  
Reaction Order ◽  
Batch Reactor ◽  
Molar Ratio ◽  
Initial Reaction ◽  
Benzoic Anhydride ◽  
Product Increase ◽  
Reaction Orders ◽  
Adsorption Desorption ◽  
Kinetics Of ◽  
Made In

 ABSTRACTThe reaction of o-xylene with benzoic anhydride has been studied by the changing molar ratio of the reactants (20:1, 10:1, and 5:1) in a batch reactor under reaction temperature 120oC. The reaction carried out without catalyst and also with catalyst Zeolite beta which was activated at 300oC overnight. HPLC analysis results showed that the yield of the product increase with the changing molar ratio of the reactants. An attempt was made in determining the kinetics of the reaction. The results show that the reaction is neither first nor second order in the acylating agent. Obtaining the reaction order even initially is unsuitable for even simple reactions that do not go to completion. It is even less applicable where more than a single process which affects the rate is taking place right from the start. These might be any one or combination of diffusion, adsorption, desorption, inhibition of the reaction by the product and multi step reactions on the surface. Postulated reaction mechanisms may be required in combination with experimental data to determine even initial reaction orders. Key words: o-xylene, catalyst, kinetics, reaction order.

Study on the Kinetics of Calcium Metabolism with the Aid of 46Ca followed by Neutron Activation Analysis

1967 ◽  
Vol 06 (03) ◽  
pp. 285-294
Author(s):  
J. Szymendera ◽  
M. Sieniawska ◽  
W. Lada ◽  
E. Burzyńska ◽  
J. Tołwiński ◽  
...  
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Calcium Metabolism ◽  
Mineral Metabolism ◽  
Kinetic Studies ◽  
Compartment Model ◽  
Before And After ◽  
Single Compartment Model ◽  
Kinetics Of

SummaryPaired kinetic studies in conjunction with balance studies of calcium were carried out in a child aged seven months before and after vitamin D. Stable 46Ca enriched to 6.48 mole per cent was used as tracer. Changes in 46Ca abundance in urinary and faecal calcium samples were determined by neutron activation analysis. Calculations of kinetic parameters of calcium metabolism were done by standard methods using a single-compartment model of calcium metabolism. This type of study does not subject the investigated child to any radiation dose, gives reliable results and seems to be the method of choice for solving problems of bone mineral metabolism in paediatrics.

Sign in / Sign up

Export Citation Format

Share Document