饮用水中总N-亚硝胺消毒副产物的生成及控制原理

N-nitrosamine disinfection by-products have high toxicity and carcinogenicity, which seriously threaten the safety of drinking water, and have raised great concerns at home and abroad. Compared with specific N-nitrosamines, it is more valuable to establish a total N-nitrosamine (TONO) index to evaluate the total amount of N-nitrosamine disinfection by-products. Therefore, establishing accurate determination and efficient control method of TONO for application is an urgent problem to be solved in the field of drinking water safety. In this project, TONO is determined by UV-photolysis coupled with chemiluminescence system, and the relationship between TONO formation and key water quality parameters (such as dissolved organic nitrogen) in chloramine/chlorine disinfection process is determined. TONO precursors will be identified systematically and quantitative structure-activity relationship between functional group characteristic parameters of TONO precursors (such as Hammett constant, highest occupied molecular orbital energy) and TONO formation rate and molar yield will be established. The mechanism of TONO formation in chloramine disinfection process will be revealed. During pre-ozonation of precursors regulated by interfacial interactions, enhanced control efficiency of TONO formation during post-chloramine/chlorine disinfection process will be studied. This project will finally provide theoretical basis and technical support for the control of TONO in drinking water treatment.

N-亚硝胺消毒副产物具有高毒性及致癌性严重威胁饮用水安全，一直是国内外关注的焦点。相比于特定N-亚硝胺，建立总N-亚硝胺（TONO）指标来评价所有N-亚硝胺消毒副产物总量更具价值，因此在工程上建立TONO准确测定方法和高效控制技术是饮用水安全保障领域中亟待解决的问题。本项目通过构建紫外光解耦合化学发光体系测定TONO，探明TONO在氯胺/氯消毒过程中的生成规律与关键水质参数（如溶解性有机氮）的关系；系统识别TONO前驱物，建立前驱物官能团特征参数（如哈米特常数、最高占据分子轨道能量等）与TONO生成速率及摩尔产率的定量构效关系，揭示TONO在氯胺消毒过程中的生成原理；从控制前驱物的角度出发，研究界面调控臭氧氧化工艺预处理对后续氯胺/氯消毒过程中TONO生成的强化控制作用，最终为TONO在饮用水处理过程中的控制提供理论依据与技术支持。

N-亚硝胺消毒副产物具有高毒性及致癌性已被列入我国地方饮用水标准中。本研究通过紫外光解耦合化学发光体系建立了测定总N-亚硝胺消毒副产物TONO的方法，采用SPE耦合萃取法进行样品预处理，即反相固相萃取柱耦合碳质萃取剂柱，将回收率提高到35-55%。研究中发现不同实际水体通过氯胺消毒后N-亚硝基二甲胺（NDMA）生成量占TONO生成量的12.71-25.30%，证明了TONO生成势对反映实际水中总亚硝胺更有意义，同时实际水体中的溶解性有机氮的含量在一定程度上能够反映消毒过程中TONO生成量。考察了不同模型前驱物与氯胺、臭氧反应生成TONO、NDMA的摩尔产率及反应机制。以叔胺、季胺模型化合物和含氮微污染有机物为前驱物时，TONO摩尔产率在pH 7条件下为0.01-5.13%。臭氧预氧化能够快速氧化降解部分含氮前驱物进而大幅削减后续氯胺消毒过程中N-亚硝胺消毒副产物的生成，但臭氧与含有二甲基肼基团的前驱物能够快速反应生成NDMA及TONO，并具有很高的生成产率（60%-100%）。进一步探究过氧化氢、过一硫酸盐、介孔铝氧化物、铁锰负载介孔铝氧化物催化臭氧的方法控制二甲基肼类前驱物转化成N-亚硝胺副产物的效能及机理。本研究所开发的臭氧催化氧化方法能够同步控制臭氧氧化过程及后续氯胺消毒过程中NDMA及TONO的生成，具有一定的工程意义。