Removal of tetrachloroethylene in an anaerobic fixed-bed reactor immobilized with Clostridium bifermentans DPH-1

2001 ◽  
Vol 1 (2) ◽  
pp. 107-114
Author(s):  
Y.C. Chang ◽  
K. Asanuma ◽  
M. Hatsu ◽  
K. Takamizawa
Keyword(s):  
Continuous Culture ◽  
Degradation Rate ◽  
Cell Mass ◽  
Fixed Bed ◽  
Order Reaction ◽  
Fixed Bed Reactor ◽  
Strictly Anaerobic ◽  
First Order ◽  
Clostridium Bifermentans ◽  
Specific Degradation

An upflow fixed-bed reactor was evaluated for the removal of tetrachloroethylene (PCE) by a strictly anaerobic, PCE dechlorinating bacterium, Clostridium bifermentans DPH-1 immobilized on sterile ceramic beads. The ceramic beads provide a large surface area for development of cell mass in the column. For kinetic experiments, the conventional first-order reaction kinetics was applied to evaluate the batch and continuous immobilized reactors. Velocity constants (KB and KC) under the batch culture and continuous culture were determined to be 1.9 × 10–2 (mg protein–1h–1) and 1.4 × 10–2 (mg protein–1h–1), respectively. Maximum specific degradation rate of PCE was calculated as 0.16 (10–3 μmol mg protein–1h–1 from average influent concentration of PCE (12 μM) in the bioreactor. Simultaneously maximum volumetric degradation rate was also computed as 10.2 μmol l–1h–1. The volumetric degradation rate was relatively higher than those of other reactors. In order to maintain the efficiency of PCE dechlorination, 20 h or more HRT in the reactor system was required.

Study of Co-pyrolysis Characteristics of Lignite and Rice Husk in a TGA and a Fixed-Bed Reactor

2013 ◽  
Vol 11 (1) ◽  
pp. 479-488 ◽  
Author(s):  
Wenju Wang ◽  
Xiaobing Zhang ◽  
Yunhua Li
Keyword(s):  
Synergistic Effect ◽  
Rice Husk ◽  
Fixed Bed ◽  
Kinetic Studies ◽  
Order Reaction ◽  
Fixed Bed Reactor ◽  
First Order Reaction ◽  
First Order ◽  
Pyrolysis Characteristics ◽  
Exponential Factors

Abstract Co-pyrolysis characteristics of lignite and rice husk blend were determined in TGA and a fixed-bed reactor. From TGA results, the weight loss rate of lignite and rice husk blend increases at 250–400°C. In a fixed bed at programmed temperature condition, the synergistic effect to produce more volatiles is appeared at 500–700°C, and the maximum synergistic effect exhibits with a rice husk blending ratio of 0.8. The gas yield of co-pyrolysis of lignite and rice husk blend was higher than that of the sum of lignite and rice husk individually. The kinetic studies were performed according to Coats–Redfern method for first-order reaction. It was found that the pyrolysis process of lignite and rice husk could be described by one first-order reaction and two consecutive first-order reactions, respectively. However, for lignite and rice blends, this process can be described by three consecutive first-order reactions. The estimated kinetic parameters, viz., activation energies and pre-exponential factors for lignite, rice husk and their blends, were found to be in the range of 63.5–477.8 kJ/mol and 1.4 × 103–6.5 × 1047 min−1, respectively.

scholarly journals Decontamination performance of air filter paper impregnated with zirconium hydroxide on sulfur mustard

2021 ◽  
Vol 267 ◽  
pp. 02063
Author(s):  
Xingqi Huang ◽  
Ting Zhao ◽  
Chunxiao Yan ◽  
Yanren Jin ◽  
Yue Wu ◽  
...  
Keyword(s):  
Filter Paper ◽  
Degradation Rate ◽  
Sulfur Mustard ◽  
Filtration Efficiency ◽  
Zirconium Hydroxide ◽  
Order Reaction ◽  
Reaction Products ◽  
Air Filter ◽  
First Order ◽  
Before And After

Using zirconium hydroxide as a decontaminant, a kind of self-decontaminating air filter paper that can effectively degrade HD was successfully prepared by impregnating. The morphology and filtration efficiency of the filter paper before and after immersing were compared. The filtration efficiency increased linearly and slowly, with the regression equation: η=0.0001L+99.971. The liquid-solid decontamination reaction of HD on zirconium hydroxide powder and self-decontaminating filter paper conformed to the kinetic of quasi-first-order reaction and found that half-lives were 0.4 h and 2.1 h respectively. Good degradation performance for HD was exhibited and the degradation rate reached more than 99 % in 12 hours. Reaction products were analysed by GC-MS, which displayed that HD was decomposed through the substitution of chlorine and the elimination of H on α-C. The ultimate decontamination products were thiodiglycol and 2-hydroxyethyl vinyl sulfide without erosive toxicity.

scholarly journals Degradation of chlorinated benzaldehydes in aqueous solutions by UV-irradiation

2002 ◽  
Vol 4 (4) ◽  
pp. 133-139 ◽  
Author(s):  
Miray Bekbölet ◽  
Nikola Getoff
Keyword(s):  
Aqueous Solutions ◽  
Hplc Analysis ◽  
Degradation Rate ◽  
Uv Light ◽  
Order Reaction ◽  
Quantum Yields ◽  
Homolytic Cleavage ◽  
First Order ◽  
Probable Reaction Mechanism ◽  
Probable Reaction

Photoinduced degradation of chlorinated benzaldehydes was investigated using UV light with λ = 253.7 nm in aerated aqueous solutions. Substrate degradation rate as expressed by first order reaction kinetics revealed rate constants, k;7.45×10−3min-1,3.90×10−3min-1and3.90×11−2min-1for 2- chlorobenzaldehyde, 3-chlorobenzaldehyde and 4-chlorobenzaldehyde respectively. The decomposition of the substrates was related to the formation of chloride and formaldehyde by homolytic cleavage processes. initial quantum yields and photochemical “GiPH-values” are reported for the degradation of the substrates. Based on the qualitative HPLC analysis, a probable reaction mechanism for the photoinduced degradation of chlorinated benzaldehydes is also presented.

scholarly journals Degradasi Larutan Pewarna Azo Tekstil Menggunakan Sistem Heterogenan O3, O3/UL, O3/TiO2/UL dan O3/H2O2/UL

2012 ◽  
Author(s):  
Razak Ali ◽  
Wan Azelee Wan Abu Bakar ◽  
Azmi Aris ◽  
Pak Yan Mok
Keyword(s):  
Hydrogen Peroxide ◽  
Azo Dye ◽  
Degradation Rate ◽  
Degradation Process ◽  
Order Reaction ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Photocatalytic System ◽  
Degradation Degree ◽  
Oxidation System

Rawatan larutan pewarna azo tekstil, Sumifix Supra Blue BRF 150% Gran (SSBBRF) melibatkan sistem yang berbeza, O3, O3/UL, 03/TiO2/UL dan O3/H2O2/UL telah dikaji. Keputusan yang diperoleh menunjukkan bahawa degradasi larutan SSBBRF melalui sistem pengoksidaan berasaskan ozon adalah lebih efektif berbanding dengan sistem pemangkinanfoto. Darjah degradasi keserapan dan warna yang tinggi serta degradasi COD dan TOC yang ketara, menunjukkan bahawa sistem pengoksidaan yang berasaskan ozon berupaya memecahkan pewarna azo dalam air tercemar kepada spesies yang lebih terbiorawat. Keputusan yang diperoleh juga menunjukkan bahawa sistem pengozonan (O3 sahaja dalam keadaan gelap), dan sistem gandingan pengozonanfoto–pemangkinanfoto (03/TiO2/UL) tidak menunjukkan perbezaan kadar degradasi pewarna azo yang ketara berbanding sistem pengozonanfoto (O3/UL) tetapi penambahan hidrogen peroksida (H2O2) ke dalam sistem 03/UL mampu meningkatkan lagi kadar degradasi pewarna azo. Perbandingan keupayaan sistem yang dikaji bagi degradasi pewarna SSBBRF adalah mengikut urutan: 03/H202/UL > O3/UL > O3/TiO2/UL > O3 > TiO2/UL. Proses pendegradasian pewarna SSBBRF mematuhi kinetik tindak balas tertib pertama pseudo dengan nilai pemalar kadar, k, dari julat 0.20 min–1 hingga 0.24 min–1 untuk 20 minit yang pertama. Kata kunci: Pewarna azo; pengozonanfoto; pemangkinanfoto; hidrogen peroksida Treatment of aqueous textile azo dye, Sumifix Supra Blue BRF 150% Gran (SSBBRF) by different kinds of systems, 03, O3/UV, 03/TiO2/UV and O3/H2O2/UV has been investigated. The results obtained showed that the degradation of SSBBRF solution involving ozone–assisted oxidation system is more superior compared to photocatalytic system. The high degradation degree of Absorbance and colour as well as the significant degradation of COD and TOC indicated that the ozone–assisited system is capable of disrupting the azo dye in the wastewater to more biotreatable species. The results obtained, also showed that ozonation (O3 alone in dark) system and simultaneous photoozonation–photocatalytic (03/TiO2/UV) system do not give significant effect to the degradation rate of azo dye in comparison with photoozonation (O3/UV) system, but addition of hydrogen peroxide (H202) in the O3/UV system may enhance the degradation rate of the azo dye. The degradation potential of these different systems studied towards SSBBRF are in the following the order: O3/H2O2/UV > O3/UV > 03/TiO2/UV > O3 > TiO2/UV. The degradation process of SSBBRF is following the kinetic of pseudo–first order reaction with the rate constants, k, ranging from 0.20 min–1 up to 0.24 min–1 for the first 20 minutes of the reactions. Key words: Azo dye; photoozonation; photocatalysis; hydrogen peroxide

Study of Photodegradation of Methylene Blue by Microbial Synthesized ZnS Material

2018 ◽  
Vol 917 ◽  
pp. 190-194 ◽  
Author(s):  
Yi Bin Li ◽  
Qi Yuan Gu ◽  
Xing Yu Liu ◽  
Ming Jiang Zhang
Keyword(s):  
Methylene Blue ◽  
Fixed Bed ◽  
Order Rate Constant ◽  
Pilot Scale ◽  
Fixed Bed Reactor ◽  
Excellent Performance ◽  
First Order ◽  
Sulfate Reducing ◽  
First Order Kinetics ◽  
Reducing Bacteria

The microbial synthesized ZnS obtained from a pilot-scale sulfate reducing bacteria (SRB) fixed bed reactor was investigated as photocatalyst. The SRB fixed bed reactor as used to treat the Zinc containing wastewater with the influent concentration of 200~300 mg Zn/L. The microbial synthesized ZnS was used as photocatalyst for methylene blue (MB) photodegradation. The results indicated that the photodegradation process could be promoted when the dosage of microbial synthesized ZnS increased. High initial MB concentration could promote the photodegradation reaction. The excellent performance of microbial synthesized ZnS in photodegradation could be explained as the formation of ZnS nanoparticles. The photodegradation with microbial synthesized ZnS were simulated by pseudo-first-order kinetics model. The apparent first-order rate constant of the ZnS catalyst was 0.15 min-1.

A Novel Kinetics Study on H2O2 Decomposition inthe Propylene Epoxidation System in a Fixed-Bed Reactor

2013 ◽  
Vol 11 (1) ◽  
pp. 265-269 ◽  
Author(s):  
Lina Wang ◽  
Yaquan Wang ◽  
Guoqiang Wu ◽  
Wenping Feng ◽  
Teng Zhang ◽  
...  
Keyword(s):  
Fixed Bed ◽  
Decomposition Reaction ◽  
Fixed Bed Reactor ◽  
Kinetics Equation ◽  
Propylene Epoxidation ◽  
H2o2 Decomposition ◽  
First Order ◽  
First Order Kinetics ◽  
Reaction Activation Energy ◽  
First Time

Abstract H2O2 decomposition in the propylene epoxidation system in a fixed-bed reactor was studied herein for the first time. The decomposition rate of H2O2 increased with increasing reaction temperature. The decomposition reaction followed the first-order kinetics equation at 30–50°C, whereas it did not follow the equation any longer at higher than 50°C. A kinetics equation for the H2O2 decomposition catalyzed by TS-1/SiO2 at 30–50°C was obtained, and the reaction activation energy Ea was calculated as 69.26 kJ/mol.

Heat Transfer in a Fixed Bed Elliptic-Cylindrical Reactor: A Pseudo-Homogeneous Model with First-Order Chemical Reaction Term

2019 ◽  
Vol 24 ◽  
pp. 121-130
Author(s):  
R. Moura da Silva ◽  
A. Santos Pereira ◽  
V.A. Machado de Miranda ◽  
J.M. Freitas de Oliveira ◽  
A.G. Barbosa de Lima
Keyword(s):  
Heat Transfer ◽  
Chemical Reaction ◽  
Fixed Bed ◽  
Temperature Gradients ◽  
Fixed Bed Reactor ◽  
Heating Zone ◽  
Heat Of Reaction ◽  
Radial Temperature ◽  
Exponential Factor ◽  
First Order

In this work a transient three-dimensional mathematical model was developed using cylindrical-elliptic coordinate system and thermo-physical properties as functions of the position or temperature. The aim is to predict heat transfer in an elliptic-cylindrical fixed bed reactor subjected to a chemical reaction of first order whose heat of reaction is given by the power law. The governing equation of the phenomenon is solved using the finite volume method, and the WUDS interpolation scheme, and the fully implicit method. Results are presented and discussed by varying reagent concentration, Arrhenius pre-exponential factor and reagent temperature at the reactor inlet. It was found that: first-order reactions at low molar concentrations have few effect in the temperature distribution and high molar concentrations, from 0.8 kmol/m3, increase the radial temperature gradients; an increase in the inlet temperature of reactor favours the increase in the heating zone in the centre of the equipment, but does not significantly alter the radial temperature gradients; the Arrehnius pre-exponential factor varying in the same order of magnitude as the concentration of reagents practically produces the same field of temperature in the reactor,

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 167-178 ◽  
Author(s):  
Xin Tong ◽  
Jiao Li ◽  
Jun Ma ◽  
Xiaoquan Chen ◽  
Wenhao Shen
Keyword(s):  
Degradation Rate ◽  
Southern China ◽  
Catalytic Degradation ◽  
Pulp And Paper ◽  
Gaseous Pollutants ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

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