Degradation Characteristics of Carbon Tetrachloride by Granular Sponge Zero Valent Iron

Granular sponge zero valent iron (ZVI) was employed to degrade carbon tetrachloride (CCl4). The effects of acidic washing, initial solution pH, and ZVI dosage on CCl4 degradation were investigated. Results showed that CCl4 was effectively removed by ZVI and approximately 75% of CCl4 was transformed into chloroform through hydrogenolysis. The rate of chloroform transformation was slower compared to that of CCl4, resulting in chloroform accumulation. CCl4 degradation was a pseudo first-order process. The observed pseudo first-order reaction rate constant (kobs) for CCl4 and chloroform were 0.1139 and 0.0109 h−1, respectively, with a ZVI dosage of 20 g/L and an initial CCl4 concentration of 20 mg/L. Surface acidic washing had a negligible effect on CCl4 degradation with ZVI. The kobs for CCl4 degradation increased linearly with increasing ZVI dosage and the optimal dosage of ZVI was 20 g/L based on the surface area-normalized rate constants. The negative relationship between kobs and the solution pH indicated that the degradation of CCl4 by ZVI performed better under weakly acidic conditions.

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Pyrolysis Modeling in a Woodstove

Heat Transfer: Volume 3 ◽

10.1115/ht2008-56083 ◽

2008 ◽

Author(s):

Rajesh Gupta

Keyword(s):

Rate Constant ◽

Empirical Model ◽

Reaction Rate ◽

Packed Bed ◽

Reaction Rate Constant ◽

Order Reaction ◽

Pseudo First Order Reaction ◽

First Order ◽

Pseudo First Order ◽

Simple Empirical Model

A simple empirical model for predicting the pyrolysis rate of fuel packed bed of a woodstove has been presented. The thermolytic behavior of the fuel bed has been approximated by a pseudo-first order reaction. The reaction rate constant has been determined as function of temperature. The effect of orientation of twigs in the fuel bed arrangement and twig diameter on the reaction rate constant has been analyzed. It has been concluded that the effect of twig orientation is insignificant while the peak magnitude of reaction rate constant increased with increasing twig diameter.

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Pseudo first-order reaction rate constant for the formation of hydroxymethylhydroperoxide from formaldehyde and hydrogen peroxide

Atmospheric Environment (1967) ◽

10.1016/0004-6981(88)90494-5 ◽

1988 ◽

Vol 22 (11) ◽

pp. 2603-2605 ◽

Cited By ~ 5

Author(s):

W.H. Benner ◽

Mirko Bizjak

Keyword(s):

Hydrogen Peroxide ◽

Rate Constant ◽

Reaction Rate ◽

Reaction Rate Constant ◽

Order Reaction ◽

First Order Reaction ◽

Pseudo First Order Reaction ◽

First Order ◽

Pseudo First Order

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The effect of the textile industry dye bath additive EDTMPA on colour removal characteristics by ozone oxidation

Water Science & Technology ◽

10.2166/wst.2007.317 ◽

2007 ◽

Vol 55 (10) ◽

pp. 145-153 ◽

Cited By ~ 12

Author(s):

T. Ölmez ◽

I. Kabdaşlı ◽

O. Tünay

Keyword(s):

Organic Matter ◽

Textile Industry ◽

Reaction Rates ◽

Textile Dye ◽

Pseudo First Order Reaction ◽

Ozone Oxidation ◽

Reactive Dyeing ◽

First Order ◽

Organic Matter Oxidation ◽

Pseudo First Order

In this study, the effects of the phosphonic acid based sequestering agent EDTMPA used in the textile dye baths on colour and organic matter removal by ozone oxidation was experimentally investigated. Procion Navy HEXL dyestuff that has been commonly used for the reactive dyeing of cellulose fibers was selected as the model component. The organic matter oxidation by ozone was determined to obey the pseudo-first order kinetics as they are treated singly or in combination. COD removal rates obtained from pseudo-first order reaction kinetics showed that oxidation of Navy HEXL alone (0.0947 L/min) was faster than that of EDTMPA (0.0171 L/min) and EDTMPA with dye (0.0155 L/min) at pH 3.0. It was also found that reaction rates of single EDTMPA removal and EDTMPA and dye mixture removal increased as the reaction pH was increased from 3.0 to 10.5.

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Multifactorial optimization of the decolorisation parameters of wastewaters resulting from dyeing flowers

Water Science & Technology ◽

10.2166/wst.2009.114 ◽

2009 ◽

Vol 59 (7) ◽

pp. 1361-1369 ◽

Cited By ~ 3

Author(s):

Edison Gil Pavas ◽

Miguel Ángel Gómez-García

Keyword(s):

Hydrogen Peroxide ◽

Organic Matter ◽

Experimental Design ◽

Order Reaction ◽

Pseudo First Order Reaction ◽

First Order ◽

Effluent Standards ◽

Degradation Of Dyes ◽

Pseudo First Order ◽

Dyes Mixture

This work deals with the treatment of the wastewaters resulting from the process of dyeing flowers. In some local cases for growing flowers near to Medellín (Colombia), wastewater color was found to be one of the main problems in meeting local effluent standards. Wastewaters were treated by photodegradation process (which includes photocatalysis) to achieve the degradation of dyes mixture and organic matter in the wastewater. A multifactorial experimental design was proposed, including as experimental factors the following variables: pH, and the concentration of both catalyst (TiO2) and hydrogen peroxide (H2O2). According to the obtained results, at the optimized variables values, it is possible to reach a 99% reduction of dyes, a 76.9% of mineralization (TOC) and a final biodegradability of 0.834. Kinetic analysis allows proposing a pseudo first order reaction for the reduction, the mineralization, and the biodegradation processes.

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Photocatalytic degradation of sulfamethazine in aqueous solution using ZnO with different morphologies

Royal Society Open Science ◽

10.1098/rsos.171457 ◽

2018 ◽

Vol 5 (4) ◽

pp. 171457 ◽

Cited By ~ 12

Author(s):

Zhigang Yi ◽

Juan Wang ◽

Tao Jiang ◽

Qiong Tang ◽

Ying Cheng

Keyword(s):

Aqueous Solution ◽

Photocatalytic Degradation ◽

Reaction System ◽

Degradation Pathway ◽

Order Reaction ◽

Pseudo First Order Reaction ◽

First Order ◽

Different Shapes ◽

Pseudo First Order ◽

Release Ratio

In this study, photocatalytic experiments of 20 mg l −1 sulfamethazine (SMN) in aqueous solution containing ZnO with different morphologies, tetra-needle-like ZnO (T-ZnO), flower-like ZnO (F-ZnO) and nanoparticles ZnO (P-ZnO), were performed. The results indicated that photocatalytic degradation of SMN was effective and followed the pseudo-first-order reaction, but the degree of SMN mineralization showed obvious differences using ZnO with different shapes. After 12 h irradiation, 86%, 71% and 50% of the initial total organic carbon was eliminated in SMN suspension containing T-ZnO, F-ZnO and P-ZnO, respectively. The release ratio of sulfur was close to 100% in the presence of T-ZnO, but reached to 86% and 67% in the presence of F-ZnO and P-ZnO, respectively. The release ratio of nitrogen was about 76%, 63% and 40% using T-ZnO, F-ZnO and P-ZnO as photocatalyst, respectively. The morphology of ZnO played an important role in determining its catalytic activity. Seven intermediates were observed and identified in the UV/T-ZnO reaction system by LC-MS/MS analysis, and a possible degradation pathway was proposed.

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On the Chemical Reactivity of the Phytochrome Chromophore in the Pr and Pfr Form

Zeitschrift für Naturforschung C ◽

10.1515/znc-1985-3-413 ◽

1985 ◽

Vol 40 (3-4) ◽

pp. 215-218 ◽

Cited By ~ 27

Author(s):

Fritz Thümmler ◽

Peter Eilfeld ◽

Wolfhart Rüdiger ◽

Doo-Khil Moon ◽

Pill-Soon Song

Keyword(s):

Reaction Kinetics ◽

Rate Constants ◽

Chemical Reactivity ◽

Order Reaction ◽

First Order Reaction ◽

Limiting Factor ◽

Pseudo First Order Reaction ◽

First Order ◽

Pseudo First Order ◽

The Difference

The reactivity of the phytochrome chromophore and related tetrapyrroles towards ozone and tetranitromethane was investigated. Both oxidizing reagents cause bleaching of the main absorption band of the pigment. The rate constants for this bleaching were determined under conditions of pseudo first order reaction kinetics. The rate constants for the reaction with ozone are similar for native phytochrome and for freely accessible tetrapyrroles (biliverdin, small chromopeptides from phytochrome) indicating that accessibility is not the limiting factor for the reaction with ozone. Under a variety of conditions, the Pfr chromophore reacts by about 10% faster than the Pr chromophore. This may reflect the true difference in reactivity. The rate constants for the reaction with tetranitromethane are much larger for biliverdin, bilirubin and small chromopeptides from phytochrome than for native phytochrome. The limiting factor for this reaction in native phytochrome therefore is the accessibility of the chromophore by the reagent. Previous conclusions on the difference in exposure of the tetrapyrrole chromophore in Pr and Pfr are confirmed.

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FIBRINOPEPTIDE B RELEASE FROM NORMAL FIBRINOGEN AND FIBRINOGEN LONDON I IN THE PRESENCE OF INHIBITORS OF FIBRIN POLYMERIZATION

10.1055/s-0038-1643341 ◽

1987 ◽

Author(s):

W Ruf ◽

A Bender ◽

K T Preissner ◽

D A Lane ◽

G Müller-Berghaus

Keyword(s):

Initial Phase ◽

Slow Rate ◽

Order Reaction ◽

Pseudo First Order Reaction ◽

Reaction Conditions ◽

Fibrin Polymerization ◽

First Order ◽

Molar Excess ◽

Pseudo First Order ◽

Fibrinogen Molecule

The fibrinopeptides A and B (FPA and FPB) are cleaved from the fibrinogen molecule with different rates. In the initial phase of the thrombin-fibrinogen reaction, FPB is released with a slow rate, which is enhanced upon polymerization of desA-fi-brin monomers. The aim of the present study was to further characterize the mechanism leading to the enhanced rate of FPB release during polymerization. For this purpose, the release of FPB from normal fibrinogen and from fibrinogen London I, which exhibits a polymerization defect located in the D-domain, was studied in the presence and absence of the fibrinolytic fragment D1 (D1) and of the synthetic tetrapeptide Gly-Pro-Arg-Pro (GPRP). Steady state parameters for fibrinopeptide release were determined under pseudo-first order reaction conditions. In the initial phase of the thrombin-fibrinogen reaction, the release of FPA was unchanged in the presence of D1. Furthermore, the release of FPA from fibrinogen London I did not reveal any difference in comparison to normal fibrinogen. GPRP prevented not only fibrin polymerization, but also the enhanced rate of FPB release. On the contrary, the rate of FPB release in the presence of a 16- and 32-fold molar excess of over fibrinogen did not differ from a reaction mixture with no added D1. Si-miliar to the inhibited rate of FPB release in the presence of GPRP, the release of FPB from fibrinogen London I occurred with a slow rate, which was not enhanced by the addition of a 16-fold molar excess of D1. Since the release neither from normal fibrinogen nor from ribrinogen London I was affected by D1, it was concluded that the D-E contact formed by D1 with an E-domain of a desA-fibrin molecule does not enhance the release of FPB. While GPRP keeps fibrin in monomeric form by inhibiting the polymerization sites in the D-domains, D1 does not prevent the formation of fibrin oligomers. Therefore, acceleration of FPB release is caused by a conformational change, which is induced by binding of reciprocal polymerization sites to an E-as well as a D-domain of the same desA-fibrin molecule.

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Effect of Cyclodextrins on Photodegradation of 4,4-Bis(4-Hydroxyphenyl)Pentanoic Acid under UV Irradiation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.665.455 ◽

2014 ◽

Vol 665 ◽

pp. 455-458

Author(s):

Li Guo ◽

Jin Huang ◽

Jun Wu ◽

Lei Lei Luo

Keyword(s):

Aqueous Solutions ◽

Fluorescence Spectra ◽

High Efficiency ◽

Uv Light ◽

Order Reaction ◽

Pentanoic Acid ◽

Pseudo First Order Reaction ◽

First Order ◽

Inclusion Interaction ◽

Pseudo First Order

The photodegradation of 4,4-bis (4-hydroxyphenyl) pentanoic acid (DPA) with two cyclodextrins (α-CD and β-CD ) in aqueous solutions induced by UV-light was studied in this paper by means of fluorescence spectra and high efficiency liquid chromatography. The result suggested that DPA with α-CD or β-CD formed inclusion compound in aqueous solutions. The photodegradation of DPA with two cyclodextrins or without cyclodextrin was pseudo-first order reaction. The photodegradation of DPA was accelerated by the addition of β-CD in aqueous solutions, but the that of DPA was inhibited in case of adding α-CD. These differences were due to the differences in inclusion interaction of DPA with α-CD or β-CD.

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Enhancement of decomposition of 2-chlorophenol with ultrasound/H2O2 process

Water Science & Technology ◽

10.2166/wst.1996.0173 ◽

1996 ◽

Vol 34 (9) ◽

pp. 41-48 ◽

Cited By ~ 17

Author(s):

Jih-Gaw Lin ◽

Cheng-Nan Chang ◽

Jer-Ren Wu ◽

Ying-Shih Ma

Keyword(s):

Ionic Strength ◽

Reaction Rate ◽

Order Reaction ◽

Pseudo First Order Reaction ◽

Initial Concentration ◽

First Order ◽

Toc Removal ◽

Cp Decomposition ◽

Effects Of Ph ◽

Pseudo First Order

We investigated the effects of pH, ionic strength, catalyst, and initial concentration on both decomposition of 2-chlorophenol (2-cp) and removal of total organic carbon (TOC) in aqueous solution with ultrasonic amplitude 120 μm and H2O2 (200 mg/l). When the initial concentrations of 2-cp was 100 mg/l and the pH was controlled at 3, the rate of 2-cp decomposition was enhanced up to 6.6-fold and TOC removal up to 9.8-fold over pH controlled at 11. At pH 3, the efficiency of decomposition of 2-cp was 99% but the removal of TOC was only 63%; a similar situation applied at pH 7 and 11. Hence intermediate compounds were produced and 2-cp was not completely mineralized. When the concentration of ionic strength was increased from 0.001 to 0.1 M, the rate of 2-cp decomposition was enhanced only 0.3-fold, whereas the TOC removal was not enhanced. In comparison of the effects of pH and ionic strength, pH had greater influence on both 2-cp decomposition and TOC removal than ionic strength. The effect of a catalyst (FeSO4) on decomposition of 2-cp was insignificant comparing with direct addition of H2O2. The reaction rate at a smaller initial concentration of 2-cp (10 mg/l) was more rapid than at a greater one (100 mg/l). The rate of 2-cp decomposition and TOC removal appeared to follow pseudo-first-order reaction kinetics.

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