水中典型含氮除草剂在消毒过程的降解机制与高致毒性含氮消毒副产物产生特性

The widely detected nitrogenious herbicides (N-herbicides) compose the major contents of dissolved organic nitrgen in micro-polluted waters. More and more attention has been focused on these chemicals not only due to their strong toxicity, but formation of toxic nitrogenous disinfection by-products (N-DBPs) with very high carcinogenicity, teratogenicity and mutagenicity during disinfection procees in drinking water treatment. Based on the previous research, the widely detected N-herbicides including amino,ureas,nitrophenols were selected in this proposal. Fate and degradation pathys of these typical N-herbicides in disinfection treatment of drinking water will be investigated including (1) kinetics of N-herbicides degradation by ozonation and chlor(am)ination as well as calculation of elementary reaction rate; (2) degradation pathways and identification of degradation byproducts during ozonation and chlor(am)ination; (3) formation of carbonaceous and nitrogenious disinfeciton byproducts during chlor(am)ination as well as the formation potential during ozonation ;(4) fate of the typical N-herbicides in different disinfection units of the water purification process as well as the control methods. As shown above, the reliable and integrated theory of N-herbicides control in depth processing of micro-polluted source water will be presented in this project.

微污染原水中广泛检出的人工除草剂是水中溶解性有机氮（DON）的重要组成部分，这些除草剂（N-herbicides）本身具有较强的致毒特性，同时可与水处理常用消毒剂（氧化剂）发生反应生成强"三致"的含氮消毒副产物（N-DBPs）。课题将在前期研究的基础上，以原水中检出频率较高的氨基类、取代脲类、硝基酚类N-herbicides为研究对象，考察其在饮用水消毒工艺中的转化特性和降解机理；建立N-herbicides在氯（胺）化、臭氧氧化过程中的降解动力学模型，求算基元反应速率；辨析氯(胺)化和臭氧氧化降解途径和产物；探索氯(胺)化过程生成C-DBP和N-DBPs的规律、掌握臭氧氧化后DBPs生成潜能变化规律；明晰N-herbicides在饮用水净水工艺中不同的变趋行为，并探明重要影响因素和削减方法；最终为我国微污染原水处理工艺中N-herbicides与N-DBPs控制，提供可靠的理论支持。

微污染原水中广泛检出的人工除草剂是水中溶解性有机氮的重要组成部分，这些除草剂本身具有较强的致毒特性，同时可与水处理常用消毒剂发生反应生成强“三致”的含氮消毒副产物（N-DBPs）。本项目以广泛存在的典型含氮除草剂N-herbicides（氨基类、取代脲类、硝基类）为主要研究对象，系统开展了其在饮用水自由氯、氯胺、臭氧及组合消毒工艺中的降解特性、转化规律及其相关机理的研究工作。课题建立了自由氯氧化降解含氨基、取代脲、含硝基类等7种含氮除草剂的动力学模型并计算出了理论基元反应速率，获得了详细的氯化降解途径和机制，母体逐步羟基化和氯取代是导致其氯化降解的关键机制；提出并应用基于羟基自由基的紫外/自由氯联合的高级氧化技术大幅提升典型含氮除草剂降解效果，构建了基于紫外、氯化与羟基自由基的多途径降解体系模型，并探索了甲硝咪乙酰胺降解反应影响因素，考察了其中间产物、降解路径和矿化效能等；探明了氯胺消毒过程中含氮除草剂与氯胺反应的活性，考察获得了苄嘧磺隆、灭草松、绿麦隆等3种典型除草剂氯胺化降解特性与动力学规律，掌握了影响降解反应重要的关键因素；解析获得了嗪草酮等7种典型含氮除草剂在氯（胺）化过程中生成高致毒性N-DBPs和常规C-DBPs生成特性，找出了不同官能团类型含氮除草剂氯（胺）化过程中产生DBPs的规律，掌握了不同类型N-DBPs生成的途径与重要影响因素；探明了环莠隆、氟磺胺草醚、草除灵等难氯（胺）化降解含氮除草剂的臭氧氧化特性，建立了相应的臭氧降解动力学模型，也获得了臭氧氧化前后混合产物的C-DBPs 和N-DBPs生成潜能变化规律。研究成果可以为我国微污染原水处理工艺中N-herbicides 与N-DBPs控制，提供可靠的理论支持。