Kinetics of Reductive Dechlorination of DDT in Soil with Zero-Valent Iron

2011 ◽  
Vol 295-297 ◽  
pp. 1236-1239
Author(s):  
Yin Hai Lang ◽  
Min Jie Wang ◽  
Nan Nan Wang
Keyword(s):  
Kinetic Model ◽  
Reductive Dechlorination ◽  
Reaction Rate ◽  
Zero Valent Iron ◽  
Order Kinetic ◽  
First Order ◽  
Reaction Rate Constants ◽  
Order Kinetic Model ◽  
Pseudo First Order ◽  
Kinetics Of

In this study, reductive dechlorination of DDT compounds by zero-valent iron in Jiangxi red soil was investigated. DDT compounds were effectively dechlorinated by zero-valent iron. The pseudo-first-order kinetic model for 2,4¢-DDT and 4,4¢-DDT reduction with zero-valent iron was proposed. The reaction rate constants for 2,4¢-DDT and 4,4¢-DDT were 1.19´10-2(min-1) and 1.44´10-2(min-1), respectively. The dechlorination of 2,4¢-DDT and 4,4¢-DDT were mainly affected by the specific surface area of iron. The data from the variable-pH experiments (between 3.6 and 8.8) suggested that pH does not play a role in the rate-determination step.

Kinetics of the Ozonation of Tetrabromobisphenol-A in Wastewater

2011 ◽  
Vol 383-390 ◽  
pp. 2945-2950 ◽  
Author(s):  
Jie Zhang ◽  
Shi Long He ◽  
Mei Feng Hou ◽  
Li Ping Wang ◽  
Li Jiang Tian
Keyword(s):  
Rate Constants ◽  
Apparent Rate Constant ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Kinetic Studies ◽  
Tetrabromobisphenol A ◽  
First Order ◽  
Reaction Rate Constants ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of TBBPA degradation by ozonation in semi-batch reactor was studied. The reaction rate constants of TBBPA with O3 and •OH were measured by means of direct ozone attack and competition kinetics, and the values of which were 6.10 l/(mol•s), 4.8×109 l/(mol•s), respectively. Results of kinetic studies showed that TBBPA degradation by ozonation under the different conditions tested followed the pseudo-first-order. The values of apparent rate constant of TBBPA degradation increased with the increase of ozone dosage and pH, but decreased with the increase of initial TBBPA concentration.

Characteristics and kinetics of hexavalent chromium reduction by gallic acid in aqueous solutions

2015 ◽  
Vol 71 (11) ◽  
pp. 1694-1700 ◽  
Author(s):  
ZiFang Chen ◽  
YongSheng Zhao ◽  
Qin Li
Keyword(s):  
Kinetic Model ◽  
Gallic Acid ◽  
Hexavalent Chromium ◽  
Ph Value ◽  
Order Kinetic ◽  
First Order ◽  
Molar Ratios ◽  
Wide Range ◽  
Order Kinetic Model ◽  
Pseudo First Order

Gallic acid (GA) is a naturally occurring plant polyphenol compound. Experiments were conducted to study the kinetics and effects of pH, temperature, irradiation, and initial hexavalent chromium (Cr(VI)) concentration on Cr(VI) reduction by GA. Results indicated that Cr(VI) could be reduced to chromium oxide (Cr(III)) with GA in a wide range of pH values from 2.0 to 8.5. The reaction followed a pseudo-first-order kinetic model with respect to Cr(VI) and GA in acid conditions (pH 2.0–5.0). However, the reaction did not follow the pseudo-first-order kinetic model at pH 6.5 and 8.5. Removal efficiencies and reaction rate constants of Cr(VI) significantly increased with decreasing pH value and increasing temperature. The effect of irradiation on Cr(VI) reduction increased with increasing pH, and irradiation improved the removal efficiency of Cr(VI) by 11.29% at pH 6.5. At pH 2.0, nearly all molar ratios of GA required for the reduction of Cr(VI) were 1:2 (±0.1) under different initial Cr(VI) concentrations; however, the molar ratios of GA required for the reduction of Cr(VI) were 1:1.29, 1:1.43, and 1:1.69, respectively, when the initial Cr(VI) concentrations were 10, 25, and 50 mg/L at pH 5.5.

Sorption of Pb2+ on Mg-Al-Fe Hydrotalcite-Like Compounds

2012 ◽  
Vol 573-574 ◽  
pp. 86-91
Author(s):  
Xue Feng Liang ◽  
Wan Guo Hou ◽  
Ying Ming Xu ◽  
Lin Wang ◽  
Yue Bing Sun
Keyword(s):  
Kinetic Model ◽  
Rate Increase ◽  
Freundlich Isotherm ◽  
Order Kinetic ◽  
Sorption Mechanism ◽  
Chemical Binding ◽  
First Order ◽  
Maximum Sorption ◽  
Order Kinetic Model ◽  
Pseudo First Order

Hydrotalcite-like compounds containing Mg2+, Al3+ and Fe3+ with a constant M2+/M3+ ratio but varying Al3+/Fe3+ ratios have been prepared. The effects of iron contents on the structural and sorption of Pb2+ by Mg-Al-Fe HTlc samples were investigated. The maximum sorption amounts were about 88-201 mg/g for Mg-Al-Fe HTlc samples. The sorption isotherm and kinetic processes can be described with Freundlich isotherm and pseudo first order kinetic model, respectively. The sorption amounts and rate increase with the increase of iron contents in HTlc samples. The sorption mechanism of Pb2+ on Mg-Al-Fe HTlcs may be the surface-induced precipitation and chemical binding adsorption.

scholarly journals Stability of tetracycline residues in honey

2012 ◽  
Vol 77 (7) ◽  
pp. 879-886 ◽  
Author(s):  
Cara Cristina ◽  
Dumitrel Gabriela-Alina ◽  
Glevitzky Mirel ◽  
Perju Delia
Keyword(s):  
Life Time ◽  
Order Kinetic ◽  
First Order ◽  
Reaction Rate Constants ◽  
Veterinary Medicines ◽  
West Region ◽  
Tetracycline Degradation ◽  
Order Kinetic Model ◽  
Tetracycline Residues ◽  
Kinetics Of

The problem of availability of veterinary medicines to treat honeybees is discussed extensively worldwide. An uncontrolled administration of antibiotics may lead to contamination of beehive products and contributes to the problem of food safety. In this study, the kinetics of tetracycline (TC) degradation in honey was studied for samples provided by four sideline beekeepers located in the west region of Romania. The samples of honey were stored in the dark at room temperature for 30 days and subsamples were analyzed every 3 days by Elisa method. The results of the study revealed that the level of tetracycline decreases in time for all honey samples. The tetracycline degradation follows a first-order kinetic model with reaction rate constants between 1.2?10-3 - 2?10-3 days-1. The half-life time of tetracycline in monofloral honeys: acacia and lime was 251 and 232 days respectively. Tetracycline degradation in polyfloral honey was accelerated since ?1/2 of TC was 151 days.

Kinetic Study of the Adsorption of Dye onto Cotton in SDS-CTAB Reverse Micelles

2015 ◽  
Vol 723 ◽  
pp. 591-595
Author(s):  
Zu Lan Liu ◽  
Lan Qian Li ◽  
Yi Ping Liu ◽  
Ming Lu
Keyword(s):  
Kinetic Study ◽  
Adsorption Kinetics ◽  
Reverse Micelles ◽  
Adsorption Kinetic ◽  
Order Kinetic ◽  
First Order ◽  
Reactive Blue 19 ◽  
Order Kinetic Model ◽  
Pseudo First Order ◽  
Kinetics Of

Adsorption kinetic study of C.I. reactive blue 19 onto cotton was carried out in SDS-CTAB reverse micelles. The data of adsorption kinetics were examined using pseudo first-and second-order kinetic models. It was found that the adsorption kinetics of dye on cotton with diffusion controlling follows the pseudo first-order kinetic model.

Effects of ultraviolet intensity and wavelength on the photolysis of triclosan

2007 ◽  
Vol 55 (1-2) ◽  
pp. 209-216 ◽  
Author(s):  
H.-S. Son ◽  
S.-B. Choi ◽  
K.-D. Zoh ◽  
E. Khan
Keyword(s):  
Kinetic Model ◽  
Hydroxyl Radicals ◽  
Direct Photon ◽  
Order Kinetic ◽  
First Order ◽  
Photodegradation Rate ◽  
Order Kinetic Model ◽  
Pseudo First Order ◽  
First Time ◽  
Subordinate Role

The effects of ultraviolet (UV) intensity and wavelength on triclosan (TCS) photodegradation kinetic, efficiency, mechanisms and pathway were studied. The TCS photodegradation followed the pseudo-first order kinetic model at all UV intensities examined at the wavelengths of 254 and 365 nm and the photodegradation rate increased with increasing UV intensity. TCS photodegradation efficiencies of 90 to 98% and 79 to 90% were obtained at the wavelengths of 254 and 365 nm, respectively. TCS was degraded mainly by photon induced hydroxyl radicals while the direct photon reaction with TCS played a subordinate role. Chlorophenol, dichlorophenol and phenol were the intermediates detected in all experiments conducted. Dibenzodichloro-p-dioxin and dibenzo-p-dioxin were observed as the intermediates only at lower UV intensities investigated at the wavelength of 365 nm. Based on these intermediates, a complete TCS photolysis pathway was proposed for the first time.

Fabrication and Photocatalytic Decolorization Performance of ZnO

2011 ◽  
Vol 396-398 ◽  
pp. 823-826
Author(s):  
Jie Cheng ◽  
Jian Zhang Li ◽  
Jun Bo Zhong ◽  
Wei Hu
Keyword(s):  
Methyl Orange ◽  
Kinetic Model ◽  
Uv Irradiation ◽  
Precipitation Method ◽  
Order Kinetic ◽  
First Order ◽  
Photocatalytic Decolorization ◽  
Langmuir Hinshelwood Mechanism ◽  
Order Kinetic Model ◽  
Pseudo First Order

Paralled flaw precipitation method has been employed to synthesize nanostructured ZnO. The prepared photocatalyst was characterized by BET, XRD. The paper reveals that Methyl Orange (MO) can be decolorized effectively in ZnO suspension system under UV irradiation. The optimal loading of photocatalyst in our experimental condition for the decolorization of MO is 1g/L. The present study, on the base of Langmuir-Hinshelwood mechanism, illustrates that the decolorization reaction is a pseudo first order kinetic model with the limiting rate constant of 8.48×10-2 mgL-1min-1 and equilibrium adsorption constant 0.335 L/mg, respectively.

scholarly journals Kinetics and reaction mechanism of photochemical degradation of diclofenac by UV-activated peroxymonosulfate

RSC Advances ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 6804-6817
Author(s):  
Yunlan Peng ◽  
Hongle Shi ◽  
Zhenran Wang ◽  
Yongsheng Fu ◽  
Yiqing Liu
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Model ◽  
Order Kinetic ◽  
Photochemical Degradation ◽  
First Order ◽  
Order Kinetic Model ◽  
Pseudo First Order

Compared to UV alone and PMS alone systems, diclofenac was removed more efficiently in UV/PMS system at pH 7.0 due to the contribution of SO4˙− and HO˙ and its degradation followed the pseudo-first order kinetic model.

Enhanced Cr(VI) Removal from Landfill Leachates Using Nanoscale Zero-Valent Iron

2014 ◽  
Vol 905 ◽  
pp. 12-18
Author(s):  
Ting Yi Liu ◽  
Zhong Liang Wang ◽  
Xiao Xing Yan
Keyword(s):  
Citric Acid ◽  
Reaction Rate ◽  
Irreversible Process ◽  
Zero Valent Iron ◽  
Landfill Leachates ◽  
X Ray ◽  
First Order ◽  
Reaction Rate Constants ◽  
Nanoscale Zero Valent Iron ◽  
Pseudo First Order

Nanoscale zero-valent iron modified by citric acid (m-NZVI) was used to remove hexavalent chromium (Cr (VI)) from landfill leachates. Citric acid was useful to enhance the dispersion of NZVI. The results demonstrated that the m-NZVI particles were uniform with a mean diameter of 45.6 nm and the specific surface area was about 22.8 m2/g. The Cr (VI) removal rates increased as an increase of the dosage of m-NZVI and the temperature but decreased as an increase of pH and the initial concentration of HA. Cr (VI) adsorption kinetics followed a pseudo-first-order rate expression and the reaction rate constants ranged from 0.05 to 0.32 min-1. X-ray photoelectron spectroscope (XPS) analysis confirmed that the Fe (III)-critic acid and/or Cr (III)-HA compounds were formed on the m-NZVI surface, which could hinder the formation of Fe (III)-Cr (III) compounds. It was also shown that removing Cr (VI) by m-NZVI was a chemical controlled and irreversible process.

scholarly journals Utilization of copper plating effluents in the degradation of the dye Sanodure Green in the presence of H2O2

Chemija ◽  
2021 ◽  
Vol 32 (1) ◽  
Author(s):  
Edita Sodaitienė ◽  
Danutė Kaušpėdienė ◽  
Audronė Gefenienė ◽  
Vladas Gefenas ◽  
Romas Ragauskas ◽  
...  
Keyword(s):  
Reaction Time ◽  
Kinetic Model ◽  
Oxidative Degradation ◽  
Order Kinetic ◽  
Nanostructured Catalyst ◽  
Copper Plating ◽  
First Order ◽  
Order Kinetic Model ◽  
Degradation Reaction ◽  
Pseudo First Order

Oxidative degradation of metal complex dye Sanodure Green (SG) in the presence of H2O2 and nanostructured catalyst CuO prepared from copper plating effluents has been investigated. The activity of the CuO catalyst in the oxidative degradation reaction depended on the SG concentration, reaction time and temperature. The reaction followed a pseudo-first order kinetic model, and the rate constant was highly dependent on the increase in temperature, but only slightly on the SG concentration. Thermodynamic studies have shown that the degradation reaction of SG is endothermic. The use of copper plating effluents for the preparation of nanostructured catalyst CuO makes it possible to avoid the accumulation of difficult-to-recycle copper oxide sludge formed during effluent neutralization, and to manage copper plating and aluminum dyeing effluents more economically.

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