Radzi abas department of chemistry faculty of science

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Unformatted text preview: inking water have been extensively reported. This study was undertaken in order to study the removal of DEET in water by ozonation. In this study, the operating parameters affecting the degradation of DEET in the ozonation process were evaluated by varying the applied ozone doses, pH values of solution, initial concentrations of DEET, and solution temperatures. The degradation of DEET by ozonation followed the pseudo -first order model that is derived from two-film theory. The rate of DEET degradation increased exponentially with temperature in the range studied (20 to 50 °C) and in proportion with the ozone dosage applied. The ozonation of DEET under different pH conditions in the presence of phosphate buffer occurred in two stages. During the first stage, the rate constant, kobs, increased with increasing pH, whereas in the second stage, the rate constant, kobs2, increased from pH 2.3 up to 9.9; however, it decreased when the pH value exceeded 9.9. In the case where buffers were not employed, the kobs were found to increase exponentially with pH from 2.5 to 9.2 and the ozonation was observed to occur in one stage. The rate of degradation decreased exponentially with the initial concentration of DEET. The degradation by products generated during the ozonation of DEET were identified to be N,N-diethyl-formamide, N,Ndiethyl-4-methylpent-2-enamide, 4-methylhex-2-enedioic acid, N-ethyl-m-toluamide, N,N-diethyl-otoluamide, N-acetyl-N-ethyl-m-toluamide, N-acetyl-N-ethyl-m-toluamide 2-(diethylamino)-1-mtolylethanone and 2-(diethylcarbamoyl)-4-methylhex-2-enedioic acid. These by-products resulted from ozonation of the aliphatic chain as well as the aromatic ring of DEET during the degradation process. ENV-O24 COMPETITIVE ADSORPTION OF 4-CHLOROPHENOL AND 2,4-DICHLOROPHENOL ONTO ACTIVATED CARBON Oh Wen Da, *Lim Poh Eng, Seng Chye Eng and Amat Ngilmi Ahmad Sujari School of Chemical Sciences, Universiti Sains Malaysia, 11800 Pulau Pinang, Malaysia E-mail: [email protected] The objective of this study is to investigate the single and binary adsorption of 4 -chlorophenol and 2,4dichlorophenol onto activated carbo...
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This note was uploaded on 02/17/2011 for the course CHEMISTRY 101 taught by Professor Csr during the Spring '11 term at University of Louisville.

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