光电催化氧化体系降解苯胺类污染物的同步耦合反应机制研究  

Study on the reaction mechanism of photoelectrocatalytic oxidation of aniline contaminants

作　　者：许入义 李孟 唐建伟 张倩 XU Ruyi;LI Meng;TANG Jianwei;ZHANG Qian(Department of Civil Engineering,Wuhan University of Technology,Wuhan 430070;95338 Troops of the Chinese People′s Liberation Army,Guangzhou 510405)

机构地区：[1]武汉理工大学市政工程系,武汉430070 [2]中国人民解放军95338部队,广州510405

出　　处：《环境科学学报》2019年第8期2525-2534,共10页Acta Scientiae Circumstantiae

基　　金：中央高校基本科研业务费专项资金资助(No.2019-zy-130,2019Ⅲ105CG)

摘　　要：以3,4-二甲基苯胺(3,4-dimethylaniline,3,4-DMA)为苯胺类污染物的代表,通过降解贡献度分析、不同影响因素下动力学公式的建立及中间产物分析来探究其在高盐光电催化氧化体系下的同步耦合反应机制.结果表明,氯类活性物质与羟基自由基对3,4-DMA 10 min降解的贡献率分别为87.55%和7.9%,UV直接氧化、阳极直接氧化、光生空穴直接氧化的作用均可忽略.在不同的初始pH值(A)、初始氯化钠浓度(B)、电流密度(C)、光照强度(D)条件下,光电体系中的光催化与电催化反应均表现出协同效应,且电催化反应占主导.4种影响因素可通过影响氯类活性物质与羟基自由基的产生来对耦合机制产生作用.根据所得动力学公式ln(c0/ct)=0.0042A^-0.2422B^0.3378C^1.4742D0.2300t,4种因素对反应体系的作用强弱顺序为:电流密度(C)>初始氯化钠浓度(B)>初始pH值(A)>光照强度(D).基于GC/MS对中间产物的检测结果,提出3,4-DMA的两种可能降解路径:①3,4-DMA依次降解为3,4-二甲基苯酚、邻二甲苯、邻甲基苯甲酸、甲苯、苯甲醛、烷烃类物质、CO2和H2O;②3,4-DMA依次降解为含N联苯类物质、脂肪酸类物质、CO2和H2O.On the basis of the analysis of degradation contribution,establishment of kinetic formulas under different influencing factors,and analysis of intermediates,the synchronous coupling degradation mechanism of 3,4?dimethylaniline(3,4?DMA),a representative aniline pollutant,in high salt photoelectrocatalytic system was investigated.Results indicated that chlorine active substances and hydroxyl radical respectively contributed 85%and 11%to the degradation rate of 3,4?DMA in 10 minutes,and the degradation of 3,4?DMA by the direct oxidation of UV,anode and photogenerated holes was negligible.Under different conditions of initial pH values(A),initial sodium chloride concentration(B),current density(C),and light intensity(D),both photocatalysis and electrocatalysis posed a synergistic effect on the degradation of 3,4?DMA and the contribution of electrocatalysis was dominant.The four factors could have certain impact on the coupling mechanism through affecting the production of chlorine active substances and hydroxyl radical.According to the obtained kinetic formula ln(c0/ct)=0.0042A-0.2422 B0.3378 C1.4742 D0.2300 t,the influence of the four factors followed the order:current density(C)>initial sodium chloride concentration(B)>initial pH(A)>light intensity(D).The degradation intermediates were detected via GC?MS analysis,and two possible 3,4?DMA degradation pathways were proposed as follows:①3,4?DMA being sequentially degraded to 3,4?dimethylphenol,o?xylene,o?methylbenzoic acid,toluene,benzaldehyde,alkane,CO2 and H2O;②3,4?DMA being sequentially degraded to N-containing biphenyls,fatty acids,CO2 and H2O.

关 键 词：3 4-二甲基苯胺(3 4-DMA) 光电催化氧化 耦合机制 动力学 降解路径 

分 类 号：X703[环境科学与工程—环境工程]