Photoassisted Degradation of a Herbicide Derivative, Dinoseb, in Aqueous Suspension of Titania

The titanium dioxide (TiO2) photoassisted degradation of herbicide dinoseb has been examined in aqueous suspensions under UV light irradiation. The degradation kinetics were studied under various conditions such as substrate concentration, type of catalyst, catalyst dosage, pH, and light intensity as well as in presence of electron acceptors such as hydrogen peroxide, potassium bromate, and potassium persulphate under continuous air purging, and the degradation rates were found to be strongly influenced by these parameters. The Degussa P25 was found to be more efficient photocatalyst as compared to other photocatalysts tested. Dinoseb was found to degrade efficiently in acidic pH and all the electron acceptors studied enhanced the degradation rate. The results manifested that the photocatalysis of dinoseb followed pseudo-first-order kinetics. A qualitative study of the degradation products generated during the process was performed by GC-MS, and a degradation mechanism was proposed.

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Titanium Dioxide-Mediated Photcatalysed Degradation of Two Herbicide Derivatives Chloridazon and Metribuzin in Aqueous Suspensions

International Journal of Chemical Engineering ◽

10.1155/2012/850468 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8 ◽

Cited By ~ 10

Author(s):

A. Khan ◽

N. A. Mir ◽

M. Faisal ◽

M. Muneer

Keyword(s):

Advanced Oxidation Process ◽

Degradation Kinetics ◽

Atmospheric Oxygen ◽

Environmental Pollutants ◽

Electron Acceptors ◽

Initial Reaction ◽

Efficient Catalyst ◽

Potassium Persulphate ◽

Aqueous Suspensions ◽

Degussa P25

The aim of this paper is to find out the optimal degradation condition for two potential environmental pollutants, chloridazon and metribuzin (herbicide derivatives), employing advanced oxidation process using TiO2photocatalyst in aqueous suspensions. The degradation/mineralization of the herbicide was monitored by measuring the change in pollutant concentration and depletion in TOC content as a function of time. A detailed degradation kinetics was studied under different conditions such as types of TiO2(anatase/anatase-rutile mixture), catalyst concentration, herbicide concentration, initial reaction pH, and in the presence of electron acceptors (hydrogen peroxide, ammonium persulphate, potassium persulphate) in addition to atmospheric oxygen. The photocatalyst, Degussa P25, was found to be more efficient catalyst for the degradation of both herbicides as compared with two other commercially available TiO2powders like Hombikat UV100 and PC500. Chloridazon (CHL) was found to degrade more efficiently under acidic condition, whereas metribuzin (MET) degraded faster under alkaline medium. All three electron acceptors tested in this study were found to enhance the degradation rate of both herbicides.

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Photocatalytic Degradation of Monolinuron and Linuron in an Aqueous Suspension of Titanium Dioxide Under Simulated Solar Irradiation

Revue des sciences de l eau ◽

10.7202/015810ar ◽

2007 ◽

Vol 20 (2) ◽

pp. 163-172 ◽

Cited By ~ 3

Author(s):

Razika Zouaghi ◽

Abdennour Zertal ◽

Bernard David ◽

Sylvie Guittonneau

Keyword(s):

Photocatalytic Degradation ◽

Degradation Rate ◽

Ph Value ◽

Degradation Kinetics ◽

Aqueous Suspension ◽

Operating Conditions ◽

Solar Irradiation ◽

Point Of Zero Charge ◽

Degradation Rates ◽

Simulated Solar Irradiation

Abstract The photocatalytic degradation of two phenylurea herbicides, monolinuron (MLN) and linuron (LN), was investigated in an aqueous suspension of TiO2 using simulated solar irradiation. The objective of the study was to compare their photocatalytic reactivity and to assess the influence of various parameters such as initial pesticide concentration, catalyst concentration and photonic flux on the photocatalytic degradation rate of MLN and LN. A comparative study of the photocatalytic degradation kinetics of both herbicides showed that these two compounds have a comparable reactivity with TiO2/simulated sun light. Under the operating conditions of this study, the photocatalytic degradation of MLN and LN followed pseudo first-order decay kinetics. The kobs values indicated an inverse dependence on the initial herbicide concentration and were fitted to the Langmuir-Hinshelwood equation. Photocatalytic degradation rates increased with TiO2 dosage, but overdoses did not necessarily increase the photocatalytic efficiency. The degradation rate of MLN increased with radiant flux until an optimum at 580 W m‑2 was reached and then decreased. Under these conditions, an electron-hole recombination was favored. Finally, the photocatalytic degradation rate depended on pH, where an optimum was found at a pH value close to the pH of the point of zero charge (pH = 6).

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Photolytic and Photocatalytic Treatment of Linear Alkylbenzene Sulfonate in Water

10.32920/ryerson.14660337.v1 ◽

2021 ◽

Author(s):

Sarah Rebecca Hatfield Venhuis

Keyword(s):

Linear Alkylbenzene Sulfonate ◽

Uv Light ◽

Order Rate Constant ◽

Batch Reactors ◽

Linear Alkylbenzene ◽

First Order ◽

Batch Tests ◽

Degradation Rates ◽

Alkylbenzene Sulfonate ◽

Degussa P25

Treatment of linear alkylbenzene sulfonate using various photolytic and photocatalytic processes is described. Based on first order rates, it is shown that 5,000 mg/L of H²O² for degradation of a 100 mg/L solution of linear alkylbenzene sulfonate is optimum. Two different photocatalysts, Degussa P25 and Hombikat UV 100 TiO², are used to degrade LAS in slurry batch reactors. The optimum photocatalyst loading for Degussa P25 is higher than UV 100 for treatment of LAS since >20% adsorbs to the surface of the UV 100 photocatalyst. Combination of photocatalysts does not improve degradation rates in batch tests. Combination of Degussa P25 and 600 mg/L H²O² and irradiation with either UV light at 254 or 365 nm does not improve degradation rates over the photocatalytic or photolytic processes individually. Photolysis of LAS with UV light at 254 nm and 600 mg/L H²O² added at different time intervals was not successful and no improvement in the first order rate constant was observed. For optimum results, the hydrogen peroxide was added at the beginning of irradiation.

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Electrochemical degradation of diclofenac by boron doped diamond anode: degradation mechanism, pathways and influencing factors

Water Science & Technology ◽

10.2166/wst.2021.231 ◽

2021 ◽

Author(s):

Huimin Qiu ◽

Pingping Fan ◽

Xueying Li ◽

Guangli Hou

Keyword(s):

Influencing Factors ◽

Wastewater Treatment Plants ◽

Degradation Products ◽

Degradation Kinetics ◽

Degradation Mechanism ◽

Electrochemical Process ◽

Sodium Sulphate ◽

Boron Doped Diamond ◽

Quenching Effect ◽

Boron Doped

Abstract Nonsteroidal anti-inflammatory drugs (NAIDS) have been widely detected in wastewater and surface water, which indicates the removal of NAIDS by wastewater treatment plants was not efficiency. Electrochemical advanced oxidation technology is considered to be an effective process. This study presents an investigation of the kinetics, mechanism and influencing factors of Diclofenac (DCF) degradation by an electrochemical process with the boron doped diamond anodes. Relative operating parameters and water quality parameters are examined. It appears that the degradation follows the pseudo-first-order degradation kinetics. DCF degradation was accelerated with the increase of pH from 6 to 10. The degradation was promoted by the addition of electrolyte concentrations and current density. HA and HCO3− significantly inhibited the degradation, whereas Cl− accelerated it. According to the inhibition tests, hydroxyl radicals (•OH) and sulfate radicals (SO4•–) contributed 76.5% and 6.5%, respectively, to the degradation. Sodium sulphate remains a more effective electrolyte, compared to sodium nitrate and sodium phosphate, suggesting the quenching effect of nitrate and phosphate on •OH. Major DCF transformation products were identified. According to the degradation products detected by liquid chromatography-mass spectrometry, hydroxylation and decarboxylation are the main pathways to DCF degradation; meanwhile, dechlorination, chlorination and nitro substitution are also included.

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Kinetics and mechanisms of EDTA photocatalytic degradation with TiO2

Water Science & Technology ◽

10.2166/wst.2001.0281 ◽

2001 ◽

Vol 44 (5) ◽

pp. 179-185 ◽

Cited By ~ 33

Author(s):

P.A. Babey ◽

C.A. Emilio ◽

R.E. Ferreyra ◽

E.A. Gautier ◽

R.T. Gettar ◽

...

Keyword(s):

Photocatalytic Degradation ◽

Ethylenediaminetetraacetic Acid ◽

Uv Light ◽

Degradation Products ◽

Glyoxylic Acid ◽

Iminodiacetic Acid ◽

Order Kinetic ◽

Kinetic Regime ◽

Complete Study ◽

Degussa P25

A complete study on the photocatalytic degradation of ethylenediaminetetraacetic acid (EDTA) over TiO2 has been initiated, to establish the influence of several parameters on the reaction rate, the nature of the intermediates and the kinetic regime. TiO2 (Degussa P25) suspensions containing EDTA at pH 3 at different concentrations were irradiated under near UV light. A Langmuirian behavior was observed, from which kinetic constants have been obtained. Experiments with 5.0 mM EDTA (zero order kinetic regime) were performed for 3 hours irradiation under different conditions. Under N2 bubbling, depletion of EDTA was very low. Under O2 bubbling, the concentration of EDTA decreased around 90%. However, the corresponding decrease of TOC ranged only between 4.5% and 9%. A higher TOC reduction (22% or more) was obtained by keeping the pH constant by HClO4 addition, or by hydrogen peroxide addition. Addition of 0.5 mM Fe(III) caused a dramatic increase on the initial rate of EDTA depletion and approximately a 32% TOC decrease. Analysis of the filtered solution was performed by ion chromatography and capillary electrophoresis to monitor the disappearance of EDTA and the formation of degradation products after different irradiation times. So far, glycine, ethylenediamine, formic acid, ammonium, iminodiacetic acid, oxalic acid and glyoxylic acid have been identified.

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Semiconductor-mediated photocatalysed degradation of two selected pesticide derivatives, terbacil and 2,4,5-tribromoimidazole, in aqueous suspension

Water Science & Technology ◽

10.2166/wst.2001.0319 ◽

2001 ◽

Vol 44 (5) ◽

pp. 331-337 ◽

Cited By ~ 17

Author(s):

M. Muneer ◽

D. Bahnemann

Keyword(s):

Hplc Analysis ◽

Model Compound ◽

Vibrio Fischeri ◽

Degradation Kinetics ◽

Irradiation Time ◽

Aqueous Suspension ◽

Toxicity Tests ◽

Tio2 Photocatalyst ◽

Degradation Rates ◽

Ph Stat

The photocatalysed degradation of two selected pesticide derivatives, namely 3-tert-butyl-5-chloro-6-methyluracil (terbacil) and 2,4,5-tribromoimidazole (TBI) has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions employing a pH-stat technique. The degradation was studied by monitoring the change in substrate concentration of the model compound employing HPLC analysis, and the decrease in total organic carbon (TOC) content, respectively, as a function of irradiation time. The degradation kinetics were studied under different conditions such as reaction pH, substrate and photocatalyst concentration, type of TiO2 photocatalyst and the presence of alternative additives such as H2O2, KBrO3 and (NH4)2S2O8 besides molecular oxygen. The degradation rates and the photonic efficiencies were found to be strongly influenced by the above parameters. Toxicity tests for the irradiated samples of the pesticide derivatives measuring the luminescence of bacteria Vibrio fischeri after 30 minutes of incubation were also performed.

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Photo-degradation ibuprofen by UV/H2O2 process: response surface analysis and degradation mechanism

Water Science & Technology ◽

10.2166/wst.2017.149 ◽

2017 ◽

Vol 75 (12) ◽

pp. 2935-2951 ◽

Cited By ~ 11

Author(s):

Mingguo Peng ◽

Huajie Li ◽

Xu Kang ◽

Erdeng Du ◽

Dongdong Li

Keyword(s):

Aqueous Solution ◽

Response Surface ◽

Ph Value ◽

Uv Light ◽

Degradation Products ◽

Degradation Mechanism ◽

Oh Radical ◽

Initial Ph ◽

Rsm Model ◽

Degradation Intermediates

The removal of ibuprofen (IBP) in aqueous solution using UV/H2O2 process was evaluated. The response surface methodology (RSM) and Box–Behnken design were employed to investigate the effects of process parameters on IBP removal, including the initial IBP concentration, H2O2 dosage, UV light intensity, and initial pH value of solution. The RSM model developed herein fits well with the experiments, and provides a good insight into the OH radical irritated degradation mechanisms and kinetics. High resolution accurate mass spectrometry coupled with liquid chromatography was used to identify the degradation intermediates. A total of 23 degradation products were identified, including mono-hydroxylated products and dihydroxylated products. A series of OH radical-initiated reactions, including hydroxylation, dihydroxylation, decarboxylation, demethylation, ring break, lead to the final mineralization of IBP to CO2 and H2O. UV/H2O2 technology could be a promising technology for IBP removal in aqueous solution.

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Empirical Kinetic Modelling and Mechanisms of Quercetin Thermal Degradation in Aqueous Model Systems: Effect of pH and Addition of Antioxidants

Applied Sciences ◽

10.3390/app11062579 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2579

Author(s):

Abdessamie Kellil ◽

Spyros Grigorakis ◽

Sofia Loupassaki ◽

Dimitris P. Makris

Keyword(s):

Thermal Degradation ◽

Empirical Model ◽

Degradation Products ◽

Degradation Kinetics ◽

Kinetic Modelling ◽

Degradation Mechanism ◽

Antioxidant Properties ◽

Biological Significance ◽

Model Systems ◽

Molar Ratio

Quercetin (Qt) is a natural flavonoid of high biological significance, and it occurs in a wide variety of plant foods. Although its oxidation by various means has been extensively studied, its behavior with regard to thermal treatments remains a challenge. The study described herein aimed at investigating Qt thermal decomposition, by proposing an empirical sigmoidal model for tracing degradation kinetics. This model was employed to examine the effect of addition of antioxidants on Qt thermal degradation, including ascorbic acid, L-cysteine, and sulfite. Furthermore, degradation pathways were proposed by performing liquid chromatography-tandem mass spectrometry analyses. Upon addition of any antioxidant used, the sigmoidal course of Qt thermal degradation was pronounced, evidencing the validity of the empirical model used in the study of similar cases. The antioxidants retarded Qt degradation in a manner that appeared to depend on Qt/antioxidant molar ratio. No major differentiation in the degradation mechanism was observed in response to the addition of various antioxidants, and in all cases protocatechuic acid and phloroglucinol carboxylic acid were typical degradation products identified. Furthermore, in all cases tested the solutions resulted after thermal treatment possessed inferior antioxidant properties compared to the initial Qt solutions, and this demonstrated the detrimental effects of heating on Qt. The empirical model proposed could be of assistance in interpreting the degradation behavior of other polyphenols, but its validity merits further investigation.

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A multivariate study of the rGO/g-C3N4 composite for the photocatalytic degradation of bisphenol A: Characterization, degradation kinetics, products identification, and ecotoxicity

10.21203/rs.3.rs-415112/v1 ◽

2021 ◽

Author(s):

Chubraider Xavier ◽

Bianca Rebelo Lopes ◽

Caue Ribeiro ◽

Eduardo Bessa Azevedo

Keyword(s):

Bisphenol A ◽

Degradation Products ◽

Degradation Kinetics ◽

Surface Response Methodology ◽

First Order ◽

Surface Areas ◽

First Order Kinetics ◽

Reduced Graphene ◽

Endocrine Disrupting ◽

Oxidation Agent

Abstract Bisphenol A (BPA), a common polymer plasticizer, is a contaminant of emerging concern with endocrine disrupting activity. Among existing abatement methods, photodegradation demands easily fabricated, inexpensive, high photoactive catalysts, leading to non-toxic byproducts after degradation. It is proposed an optimized (surface response methodology) catalyst for those goals: graphitic carbon nitride impregnated with reduced graphene oxide. The method was based on the sonication of preformed particles followed by reduction with hydrazine in reflux, a methodology that allows for better reproducibility and larger specific surface areas. The catalyst removed 90% of BPA (100 mL, 100 µg L− 1) in 90 min under UV irradiation (365 nm, 26 W) compared to 50% with pure g-C3N4 (pseudo-first-order kinetics). Tests with radicals scavengers revealed that superoxide radical was the main oxidation agent in the system. By mass spectrometry, two major degradation products were identified, which were less ecotoxic than BPA towards a series of organisms, according to in silico estimations performed with the ECOSAR 2.0 software.

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Determination of Chemical Stability of Two Oral Antidiabetics, Metformin and Repaglinide in the Solid State and Solutions Using LC-UV, LC-MS, and FT-IR Methods

Molecules ◽

10.3390/molecules24244430 ◽

2019 ◽

Vol 24 (24) ◽

pp. 4430

Author(s):

Anna Gumieniczek ◽

Anna Berecka-Rycerz ◽

Tomasz Mroczek ◽

Krzysztof Wojtanowski

Keyword(s):

High Temperature ◽

Degradation Products ◽

Degradation Kinetics ◽

Magnesium Stearate ◽

Oral Antidiabetics ◽

First Order ◽

First Order Kinetics ◽

Ft Ir ◽

The Stability

Firstly, metformin and repaglinide were degraded under high temperature/humidity, UV/VIS light, in different pH and oxidative conditions. Secondly, a new validated LC-UV method was examined, as to whether it validly determined these drugs in the presence of their degradation products and whether it is suitable for estimating degradation kinetics. Finally, the respective LC-MS method was used to identify the degradation products. In addition, using FT-IR method, the stability of metformin and repaglinide was scrutinized in the presence of polyvinylpyrrolidone (PVP), mannitol, magnesium stearate, and lactose. Significant degradation of metformin, following the first order kinetics, was observed in alkaline medium. In the case of repaglinide, the most significant and quickest degradation, following the first order kinetics, was observed in acidic and oxidative media (0.1 M HCl and 3% H2O2). Two new degradation products of metformin and nine new degradation products of repaglinide were detected and identified when the stressed samples were examined by our LC-MS method. What is more, the presence of PVP, mannitol, and magnesium stearate proved to affect the stability of metformin, while repaglinide stability was affected in the presence of PVP and magnesium stearate.

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