Effect of substituents in hydroxyl radical-mediated degradation of azo pyridone dyes: Theoretical approaches on the reaction mechanism  

作　　者：J.Dostanic M.Hus D.Loncarevic 

机构地区：[1]Institute of Chemistry,Technology and Metallurgy,University of Belgrade(National Institute),Department of Catalysis and Chemical Engineering,Njegoševa 12,Belgrade,Republic of Serbia [2]Department of Catalysis and Chemical Reaction Engineering,National Institute of Chemistry,Hajdrihova 19,Ljubljana,Slovenia

出　　处：《Journal of Environmental Sciences》2020年第12期14-21,共8页环境科学学报（英文版）

基　　金：supported by the Ministry of Education,Science and Technological Development of the Republic of Serbia and the Slove-nian Research Agency (research core funding No. P2-0152)。

摘　　要：Understanding the degradation behavior of azo dyes in photocatalytic wastewater treatment is of fundamental and practical importance for their application in textile-processing and other coloration industries. In this study, quantum chemistry, as density functional theory, was used to elucidate different degradation pathways of azo pyridone dyes in a hydroxyl radical(HO ·)-initiated photocatalytic system. A series of substituted azo pyridone dyes were synthesized by changing the substituent group in the para position of the benzene moiety, ranging from strong electron-donating to strong electron-withdrawing groups. The effect of dye molecular structure on the photocatalytic degradation reaction mechanism was analyzed and quantification of substituent effects on the thermodynamic and kinetics parameters was performed. Potential energy surface analysis revealed the most susceptible reaction site for the HO ·attack. The calculated reaction barriers are found to be strongly affected by the nature of substituent group with a good correlation using Hammett σp constants and experimentally determined reaction rates. The stability of pre-reaction complexes and transition state complexes were analyzed applying the distortion-interaction model. The increased stability of the transition state complexes with the distancing from the substituent group has been established.

关 键 词：Quantum chemical calculation Density functional theory Azo dye Reaction mechanism Photocatalytic degradation Hydroxyl radical Hammett equation Substituent effect 

分 类 号：X703[环境科学与工程—环境工程]