UVC/过硫酸盐/乙腈反应体系的构建及对茜素类染料的降解

Construction the reaction system of UVC/persulfate/aprotic solvents and its application on the degradation of alizarin dyes

为探索水体环境中有机污染物在硫酸根自由基(·SO_(4)-)作用下的迁移转化规律,构建了UVC/过硫酸盐(PDS)/非质子极性溶剂反应体系,模拟了茜素类染料在·SO_(4)-作用下的降解动力学与反应机制.媒染橙1在不同溶剂体系中的降解动力学常数大小为:(90%乙腈(ACN)+10%水(H_(2)O))>100%H_(2)O>100%二甲基亚砜(DMSO)>100%二甲基甲酰胺(DMF).并且媒染橙1比茜素黄GG具有更高的降解反应速率.UVC/PDS/(90%ACN+10%H_(2)O)体系中PDS用量、底物浓度、反应温度和光照强度等因素对茜素类染料降解动力学均有明显的影响.高温和强的光强有利于茜素类染料的降解,而过高PDS用量和底物浓度降低了茜素类染料的反应速率.·SO_(4)-对茜素类染料的降解占据主导作用.而茜素类染料的初始降解途径主要包括单电子转移反应导致的脱磺酸基和偶氮键断裂以及吸氢反应和取代反应等.

In order to investigate the transformation mechanism of organic pollutants under the attack of·SO_(4)-.The system of UVC/persulfates/aprotic solvents was constructed and applied to produce single·SO_(4)-,and then·SO_(4)-was used to react with alizarin dyes.The degradation kinetics and mechanism of azo dyes were also elucidated.The degradation kinetics of Mordant Orange 1 in different aprotic solvents followed this order:(90%ACN+10%H_(2)O)>100%H_(2)O>100%DMSO>100%DMF,and the degradation rate of Mordant Orange 1 was higher than the alizarin yellow GG.The PDS dosage substrate concentration,reaction temperature and light intensity have significantly effects on degradation kinetics of alizarin dyes.Higher temperature and stronger light intensity are favors for the degradation of alizarin dyes.While the higher persulfates dosage and substrate concentration hinder the degradation of alizarin dyes.EPR and reactive oxygen spices scavengers experiments indicated that·SO_(4)-did the major contribution on the degradation of alizarin dyes.The single electron transfer was the main reason which resulted in the degradation of alizarin dyes.And the initial transformation mechanism of alizarin dyes includes 4 pathways,such as the loss of sulfonic acid group,cleavage of azo bonds,H-abstraction and substitution.