染料在TiO_2/UV体系中的光催化氧化降解规律

Rules of Photocatalytic Oxidation Degradation of Dyes in TiO_2/UV System

在TiO2／UV体系中，以10种不同结构的染料作为研究对象，考察溶液的浓度、总有机碳（TOC）、pH值及NO2^-、NO3^-、SO4^2-、Cl^-的浓度变化，探讨染料的光催化氧化降解规律．结果表明：多数染料的降解与矿化程度基本一致，仅吸附性强的阳离子蓝FGL降解率最大但矿化率最小；反应过程中多数染料溶液的pH值均先降后升，而降解最慢的活性艳蓝X-BR溶液的pH值一直降低；反应后转化为NO2^-和NO3^-的N不足5％，有15％～60％的--SO3Na与--Cl分别转化为SO4^2-及Cl^-；萘环及均三嗪结构均比苯环稳定，连接一个偶氮键的萘环比连接两个对称偶氮键的萘环稳定，与偶氮键直接相连的苯环比远离偶氮键的苯环稳定．

Ten dyes with different structures were used to investigate the rules of photocatalytic oxidation degradation of dyes in TiO2/UV system. The concentration, total organic carbon （TOC） and well as the concentration variations of NO2^- , NO3^- , SO4^2- and Cl^- in the solution were that most dyes have the similar degrees of degradation and mineralization, except the pH value of the solution as all tested. The results show cationic blue FGL with the strongest adsorption capability, the highest degradation rate and the lowest mineralization rate, that the pH values of most dyes at first decrease and then increase with the exception that the pH value of the reactive brilliant blue X-BR with the lowest degradation velocity continuously decreases, that less than 5 % of N in the solution turns into NO2^- and NO3^- and 15%-60% of--SO3Na and --Cl respectively turn into SO4^2- and Cl^- after the reaction, that both the naphthalene ring and the striazine structure are more stable than the benzene ring, that the naphthalene ring joined to one azo bond is more stable than that joined to two symmetrical azo bonds, and that the benzene ring joined to the azo bond is more stable than that being far from the azo bond.