Photocatalytic degradation kinetics and mechanism of pentachlorophenol based on superoxide radicals  

作　　者：Yang Li Junfeng Niu Lifeng Yin Wenlong Wang Yueping Bao Jing Chen Yanpei Duan 

机构地区：[1]State Key Laboratory of Water Environment Simulation, School of Environment, Beifing Normal University, Beijing 100875, China.

出　　处：《Journal of Environmental Sciences》2011年第11期1911-1918,共8页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.21077010);the Na-tional Key Technology R&D Program of China(No.2008BAC32B06-3);the National High Technology Research and Development Program (863) of China(No.2009AA05Z306);the Program for Changjiang Schol-ars and Innovative Research Team in University(No.IRT0809)

摘　　要：The micron grade multi-metal oxide bismuth silicate （Bi 12 SiO 20,BSO） was prepared by the chemical solution decomposition technique.Photocatalytic degradation of pentachlorophenol （PCP） was investigated in the presence of BSO under xenon lamp irradiation.The reaction kinetics followed pseudo first-order and the degradation ratio achieved 99.1% after 120 min at an initial PCP concentration of 2.0 mg/L.The pH decreased from 6.2 to 4.6 and the dechlorination ratio was 68.4% after 120 min at an initial PCP concentration of 8.0 mg/L.The results of electron spin resonance showed that superoxide radical （O 2 · ） was largely responsible for the photocatalytic degradation of PCP.Interestingly,this result was different from that of previous photocatalytic reactions where valence band holes or hydroxyl radicals played the role of major oxidants.Some aromatic compounds and aliphatic carboxylic acids were determined by GC/MS as the reaction intermediates,which indicated that O 2 · can attack the bond between the carbon and chlorine atoms to form less chlorinated aromatic compounds.The aromatic compounds were further oxidized by O 2 · to generate aliphatic carboxylic acids which can be finally mineralized to CO 2 and H 2 O.The micron grade multi-metal oxide bismuth silicate （Bi 12 SiO 20,BSO） was prepared by the chemical solution decomposition technique.Photocatalytic degradation of pentachlorophenol （PCP） was investigated in the presence of BSO under xenon lamp irradiation.The reaction kinetics followed pseudo first-order and the degradation ratio achieved 99.1% after 120 min at an initial PCP concentration of 2.0 mg/L.The pH decreased from 6.2 to 4.6 and the dechlorination ratio was 68.4% after 120 min at an initial PCP concentration of 8.0 mg/L.The results of electron spin resonance showed that superoxide radical （O 2 · ） was largely responsible for the photocatalytic degradation of PCP.Interestingly,this result was different from that of previous photocatalytic reactions where valence band holes or hydroxyl radicals played the role of major oxidants.Some aromatic compounds and aliphatic carboxylic acids were determined by GC/MS as the reaction intermediates,which indicated that O 2 · can attack the bond between the carbon and chlorine atoms to form less chlorinated aromatic compounds.The aromatic compounds were further oxidized by O 2 · to generate aliphatic carboxylic acids which can be finally mineralized to CO 2 and H 2 O.

关 键 词：photocatalytic degradation PENTACHLOROPHENOL bismuth silicate superoxide radicals reaction mechanisms 

分 类 号：X703[环境科学与工程—环境工程] Q945.11[生物学—植物学]