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Kinetics and mechanisms of reactions for hydrated electron with chlorinated benzenes in aqueous solution

Kinetics and mechanisms of reactions for hydrated electron with chlorinated benzenes in aqueous... Abstract The reactions between chlorinated benzenes (CBzs) and hydrated electron (e −aq ) were investigated by the electron beam (EB) and laser flash photolysis (LFP) experiments. Under the EB irradiation, the effects of irradiation dose, initial concentration and the number of Cl atoms on the removal efficiencies were further examined. At 10 kGy, the removal efficiencies of mono-CB, 1,3-diCB, 1,2-diCB and 1,4-diCB were 41.2%, 87.2%, 84.0%, and 84.1%, respectively. While irradiation dose was 50 kGy, the removal efficiencies increased to 47.4%, 95.8%, 95.0%, and 95.2%, respectively. Irradiation of CBzs solutions has shown that the higher the initial concentration, the lower the percentage of CBzs removal. In addition to this, the dechlorination efficiencies of 1,2-dichlorobenzene (1,2-diCB), 1,3-dichlorobenzene (1,3-diCB) and 1,4-dichlorobenzene (1,4-diCB) were much higher than that of chlorobenzene (mono-CB). The kinetics of the reactions was achieved with nanosecond LFP. The rate constants of second-order reaction between e −aq with mono-CB, 1,2-diCB, 1,3-diCB and 1,4-diCB were (5.3±0.4) × 108, (4.76±0.1) × 109, (1.01±0.1) × 1010 and (3.29±0.2) × 109 L·mol−1·s−1, respectively. Density functional theory (DFT) calculations were performed to determine the optical properties of unstable CBzs anion radicals, and the main absorption peaks lied in the range of 300–550 nm. The primary reaction pathway of CBzs with e −aq was gradual dechlorination, and the major products were Cl− and benzene (CBzs(-Cl−)). Furthermore, biphenyl (or chlorobiphenyl) was observed during the LFP, which was probably formed by recombination of benzene radicals. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png "Frontiers of Environmental Science & Engineering" Springer Journals

Kinetics and mechanisms of reactions for hydrated electron with chlorinated benzenes in aqueous solution

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References (34)

Publisher
Springer Journals
Copyright
2014 Higher Education Press and Springer-Verlag Berlin Heidelberg
ISSN
2095-2201
eISSN
2095-221X
DOI
10.1007/s11783-014-0691-8
Publisher site
See Article on Publisher Site

Abstract

Abstract The reactions between chlorinated benzenes (CBzs) and hydrated electron (e −aq ) were investigated by the electron beam (EB) and laser flash photolysis (LFP) experiments. Under the EB irradiation, the effects of irradiation dose, initial concentration and the number of Cl atoms on the removal efficiencies were further examined. At 10 kGy, the removal efficiencies of mono-CB, 1,3-diCB, 1,2-diCB and 1,4-diCB were 41.2%, 87.2%, 84.0%, and 84.1%, respectively. While irradiation dose was 50 kGy, the removal efficiencies increased to 47.4%, 95.8%, 95.0%, and 95.2%, respectively. Irradiation of CBzs solutions has shown that the higher the initial concentration, the lower the percentage of CBzs removal. In addition to this, the dechlorination efficiencies of 1,2-dichlorobenzene (1,2-diCB), 1,3-dichlorobenzene (1,3-diCB) and 1,4-dichlorobenzene (1,4-diCB) were much higher than that of chlorobenzene (mono-CB). The kinetics of the reactions was achieved with nanosecond LFP. The rate constants of second-order reaction between e −aq with mono-CB, 1,2-diCB, 1,3-diCB and 1,4-diCB were (5.3±0.4) × 108, (4.76±0.1) × 109, (1.01±0.1) × 1010 and (3.29±0.2) × 109 L·mol−1·s−1, respectively. Density functional theory (DFT) calculations were performed to determine the optical properties of unstable CBzs anion radicals, and the main absorption peaks lied in the range of 300–550 nm. The primary reaction pathway of CBzs with e −aq was gradual dechlorination, and the major products were Cl− and benzene (CBzs(-Cl−)). Furthermore, biphenyl (or chlorobiphenyl) was observed during the LFP, which was probably formed by recombination of benzene radicals.

Journal

"Frontiers of Environmental Science & Engineering" – Springer Journals

Published: Aug 1, 2015

Keywords: Environment, general

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