3种不同工艺中莠灭净的去除特性及自由基鉴定

以三嗪类除草剂莠灭净（AMT）为目标污染物，对比研究了紫外（UV）、紫外激活过硫酸盐（UV/PS）与紫外激活过一氧硫酸氢盐（UV/PMS）3种不同工艺对AMT的去除效果以及反应动力学模型。考察了底物初始浓度、氧化剂浓度、溶液初始pH和水中腐殖酸浓度对AMT降解的影响，并对反应中生成的主要自由基进行鉴定。结果表明，3种系统下AMT降解均符合拟一级反应动力学模型（R2 ≥ 0.93）。AMT在3种不同系统下降解效率基本遵循UV/PS > UV/PMS > UV规律。随着底物初始浓度的增加，AMT降解率减小，拟一级速率常数kobs减小；增加氧化剂的投加量可以促进AMT降解；溶液pH的改变对UV系统下AMT的降解影响较小，而在UV/PS系统下，随着pH的增大降解率逐渐减小，在UV/PMS系统中降解率则呈现先减小后增大的趋势；投加腐殖酸会抑制AMT的降解；pH为7时，UV/PS和UV/PMS系统中反应生成的自由基主要是·SO4-。

Comparing the degradation of Ametryn in three different systems and identification of radical species

The effectiveness and the reaction kinetics model of triazine herbicide Ametryn (AMT) degradation by means of UV, UV/persulfate (PS), and UV/peroxymonosulfate (PMS) was investigated. Emphasis was placed on the effect of initial AMT concentration, oxidant concentration, initial pH, and humic acid concentration for the kinetics of AMT degradation by UV, UV/PS and UV/PMS. The main radical generated in the reaction was identified. The results showed that degradation of AMT in these three systems was determined by pseudo-first-order kinetics (R2 ≥ 0.93). The three oxidation processes, in terms of degradation rates of AMT, assumed the order UV/PS > UV/PMS > UV. The degradation rate and the pseudo-first-order constant kobs of AMT decreased with increase of the initial AMT concentration. AMT degradation can be promoted by increasing the dosage of oxidant. The pH has little influence on the oxidation of AMT in the UV system. The degradation rate decreases with increasing pH in the UV/PS system, and decreases initially, but then increases in the UV/PMS system. HA addition has a suppression effect on AMT degradation, and the efficiency is highest in the UV/PMS system. The main radical generated is ·SO4- when pH=7 in the UV/PS and UV/PMS systems.