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硫酸根自由基(·
$\rm SO_4^- $ )氧化还原电位较高,相对于羟基自由基(·OH)具有更长的半衰期[1-3]. 因此基于·$\rm SO_4^- $ 的深度氧化处理技术已经广泛地运用于水体环境中有机污染物处理研究,然而基于·$\rm SO_4^- $ 的深度氧化处理技术对有机污染物进行降解过程中,存在多种活性氧化物种共存的情况,从而难以区分不同种类的活性氧物种对目标有机污染物的降解机制和降解贡献[4-6]. 非质子极性溶剂环境则有利于单一·$\rm SO_4^- $ 的稳定存在[7-8],因此,构建非质子极性溶剂中过硫酸盐活化反应体系对探索有机污染物和·$\rm SO_4^- $ 的反应机制和降解动力学具有重要的意义.茜素类染料是一种典型的媒介染料,也是印染废水常见组份之一. 其主要分为茜素类蒽醌染料、茜素类染料等[7]. 茜素类染料作为染料型配位剂广泛地运用于在分光光度分析、电化学分析等方面. 可以大大提高检测的灵敏度和选择性[9-10]. 随着茜素类染料在工业上广泛应用,其不可以避免的流入到水体环境中[11]. 然而关于茜素类染料在水体环境中降解动力学,特别是转化的共性机制还未见相关文献报道.
本文以茜素类染料为目标化合物,采用低压汞灯为光源,活化非质子极性溶剂中PDS. 使得有效产生单一的·
$\rm SO_4^- $ 和茜素类染料直接作用. 从而探索茜素类染料在UVC/PDS/非质子极性溶剂体系中单因素对其降解动力学的影响及其该体系中·$\rm SO_4^- $ 对茜素类染料反应机制和降解途径,试图为环境介质中茜素类染料在活性氧物种(ROSs)作用下的迁移、转化、归趋和光活化降解提供理论和实验依据.
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
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摘要: 为探索水体环境中有机污染物在硫酸根自由基(·
$\rm SO_4^-$ )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·$\rm 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(H2O)) >100%H2O>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%H2O)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. ·$\rm 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.Abstract: In order to investigate the transformation mechanism of organic pollutants under the attack of ·$\rm SO_4^- $ . The system of UVC/persulfates/aprotic solvents was constructed and applied to produce single ·$\rm SO_4^- $ , and then ·$\rm 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%H2O)>100%H2O>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 •$\rm 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.-
Key words:
- mordant orange 1 /
- alizarin yellow GG /
- sulfate radical /
- degradation kinetics /
- reaction mechanism /
- aprotic solvents
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表 1 媒染橙1和茜素黄GG可能的降解中间产物
Table 1. Proposed degradation intermediates for alizarin dyes
保留时间
Retention time质荷比m/z 分子式
Molecular formula产物结构式
Product structure备注
Remark实际值
Actual value理论值
Theoretical value0.84 122.92 123 C6H5NO2 硝基苯 A,B 0.93 302.16 303 C13H9N2O6 单羟基化媒染橙1 A 0.93 152.92 153 C7H7NO3 2-羟基-5-氨基苯甲酸 A,B 1.05 287.83 287 C13H9N2O5 2-羟基-5-(4-硝基偶氮苯)苯甲酸 A 4.94 257.64 257 C13H11N3O3 2-羟基-5-(4-氨基偶氮苯)苯甲酸 A 4.96 138.02 138 C6H6N2O2 对硝基苯胺 A 4.96 138.02 138 C7H6O3 邻羟基苯甲酸 A,B 5.93 242.18 242 C13H10N2O3 2-羟基-(4-偶氮苯)苯甲酸 A,B 5.93 244.19 243 C12H9N3O3 4-(4-硝基偶氮苯)苯酚 A,B 6.69 288.06 287 C13H9N2O5 2-羟基-5-(3-硝基偶氮苯)苯甲酸 B 7.51 212.84 213 C12H11N3O 4-(4-氨基偶氮苯)苯酚 A 8.44 139.66 138 C6H6N2O2 间硝基苯胺 B 8.52 109.23 109 C6H7NO 对氨基苯酚 B 注释: A是指媒染橙1乙腈反应体系,B为茜素黄GG乙腈反应体系. -
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