Title: A theoretical study on the mechanism and kinetics of toxic PCDD destruction by OH radicals

Authors: Zhengcheng Wen; Shengji Li; Heping Li; Yuan Li

Addresses: College of Science, Hangzhou Dianzi University, Hangzhou, 310018, China ' College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018, China ' College of Science, Hangzhou Dianzi University, Hangzhou, 310018, China ' College of Science, Hangzhou Dianzi University, Hangzhou, 310018, China

Abstract: The mechanism and kinetics of toxic PCDDs destruction by OH radicals is investigated in detail by employing quantum chemistry. Results show that the OH radical degrades toxic PCDDs via substituting chlorine at the 2, 3, 7, 8 positions. The kinetic parameters are calculated by adopting transition state theory. The rate constant of OCDD destruction by OH is in agreement with the experimental result, especially at 298 K. The rate constants of 2, 3, 7, 8-TCDD destruction are obviously lower than those of other toxic PCDDs. The reason is discussed by using the NBO charge analysis. Owing to the activation effect of Cl atoms at 1, 4, 6, 9 positions, C atoms at 2, 3, 7, 8 positions have more negative charge. At aromatic rings, if the carbon has more negative charge, the carbon is more easily attacked by OH and the adjacent Cl is more easily substituted.

Keywords: PCDDs; OH radical; quantum chemistry; destruction mechanism; kinetic.

DOI: 10.1504/IJEP.2019.103749

International Journal of Environment and Pollution, 2019 Vol.65 No.4, pp.337 - 349

Received: 30 Jun 2018
Accepted: 14 May 2019
Published online: 26 Nov 2019 *

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