光电催化氧化处理中各类活性物质的氧化机理

为了深入研究其中各类活性物质氧化机理，以难降解的3，4-二甲基苯胺（3，4-DMA）废水作为研究对象，通过研究不同抑制剂条件下的动力学规律，并以贡献度（k_f/K）来量化各活性物质的作用效果，得出氯类活性物质的贡献度为89.03%，羟基自由基（·OH）的贡献度为6.24%，而空穴和阳极直接氧化贡献度可以忽略.采用三聚氰胺法、二甲亚砜（DMSO）法和DPD法定性定量测定了空穴、·OH和自由氯的含量，结果表明：较高浓度的氯化钠降低了空穴和·OH的贡献度；·OH的产量符合零级动力学规律，其产生速率为0.106mg/（L·min）；自由氯的累积浓度分为3个阶段，第3阶段累积速率为0.159mg/（L·min）.自由氯仅占氯类活性物质氧化体系的一小部分，其他含氯氧化物质和氯类自由基的氧化占重要地位.通过GC-MS、UV-vis和TOC检测，发现在反应10.0min前，主要通过氯类活性物质对侧链的快速攻击，使3，4-DMA转化为苯甲醛等易分解的苯环类物质；10.0min后，主要通过·OH对苯环大π键的攻击，使苯环类物质转化为小分子物质，然后继续被·OH氧化直到矿化.

Oxidation mechanisms of all kinds of active substances by hybrid photoelectrocatalytic treatment

Refractory 3,4-dimethylaniline wastewater was studied for the oxidation mechanisms of various active substances generated in the HPECO process and the contribution degree (k_f/K) based on kinetics was utilized to evaluate the oxidation effect of each active substance. The results showed that the contribution degrees of active chlorines and hydroxyl radicals were respectively 89.03% and 6.24% and the contribution of hole and anode direct oxidation was negligible. The holes, hydroxyl radicals and free chlorine were determined respectively by the ways of melamine, dimethylsulfoxide and DPD and the results showed that the contribution degrees of holes and ·OH were decreased due to high concentration of sodium chloride and ·OH yield followed the zero-order kinetic law with the rate of 0.106mg/(L·min). Moreover, the cumulative concentration regulation of free chlorine was divided into three stages with the rate of 0.159mg/(L·min) in the third stage. Free chlorine only accounted for a small portion in active chlorines, while the oxidation of other chlorinated oxides and chlorinated free radicals played important roles. By GC-MS, UV-vis and TOC determination, it showed that in the initial 10.0min, the active chlorines attacked the side chains rapidly, so that 3, 4-DMA could be converted into benzaldehyde and other benzene derivatives. After 10.0min, the benzene derivatives were attacked towards the π bonds by ·OH and transformed into small molecules which could be finally mineralized.