水中NO_(2)^(-)诱导典型新污染物的紫外降解机制研究—共存因子协同和拮抗作用、氧化组分数值分析和毒理学评价

UV treatment of typical emerging contaminants induced by nitrite ions in water:Synergistic and antagonistic effects of co-existing substances,numerical analysis of reactive species component and toxicological evaluation

水中亚硝酸根(NO_(2)^(-))能在紫外光(UV)激发下产生羟基自由基(·OH)及氮氧活性物质(RNs),促进有机污染物降解;然而该反应过程中的共存因子影响、氧化组分相关关系及副产物毒理学等方面研究比较有限.基于此,本文采用UV/NO_(2)^(-)体系对典型新污染物(ECs)进行降解,并研究体系反应机制和新污染物环境归趋.实验结果表明,UV/NO_(2)^(-)体系对双酚类、磺胺类、非甾体类、氟喹诺酮类和染料等14种新污染物都具有高效的处理效果,且具有一定浓度依赖关系.以双酚F(BPF)为目标污染物,实验发现在UV/NO_(2)^(-)体系中硝酸根具有明显协同促进作用;腐殖酸、亚铁离子和铜离子通过光掩蔽和猝灭活性物质从而与UV/NO_(2)^(-)体系产生拮抗作用;海水、二沉池水和珠江水等水质对体系活性具有较高的抑制作用.随着pH增大,BPF降解速率显著提高;酸性条件下以·OH和RNs为主要贡献,碱性条件下以单独UV光解为主;·OH和RNs贡献率之间存在显著相关关系.BPF在UV/NO_(2)^(-)体系中降解路径包括羟基化反应和亚硝化反应,生成的亚硝化产物具有一定的毒理学风险;实验发现通过延长反应时间可以基本消除BPF及其转化产物,使得BPF反应液达到深度矿化程度.本研究相关结果有助于深入认识UV/NO_(2)^(-)体系的活性机制,同时为UV处理水中痕量新污染物提供基础理论支撑.

Nitrite(NO_(2)^(-))can produce hydroxyl radicals(·OH)and nitrogen-containing oxygen species(RNs)under ultraviolet(UV)excitation to promote the degradation of organic pollutants in water.However,there are knowledge gaps in the study of the influence of coexistence factors,the correlation of oxidation components and the toxicology of by-products in the reaction process.Based on this,the typical emerging contaminants(ECs)-were degraded by the UV/NO_(2)^(-) system in this study;and the reaction mechanism of the system and the environmental fate of ECs were deeply studied.-The experimental results showed that the UV/NO_(2)^(-) system had an efficient treatment effect on 14 ECs such as bisphenols,sulfonamides,non-steroidal,fluoroquinolones and dyes,which also had a certain concentration dependence.Among the ECs,bisphenol F(BPF)was set as the target pollutant,it-was found that the nitrate had obvious synergistic effect with UV/NO_(2)^(-) system.Humic acid,ferrous ions and copper ions produced antagonism with UV/-NO_(2)^(-) system by masking and quenching the reactive substances;water matrices such as seawater,wastewater effluent and Pearl River water had high inhibitory effect on the activity of the system.The degradation rate of BPF increased significantly with the increase of pH.Under acidic conditions,the·OH and RNs were the main contributions,and UV photolysis had the least effect;under alkaline conditions,UV photolysis was dominant;and there-was a significant strong correlation between the contribution rate of·OH and RNs.The degradation pathway of BPF in UV/NO_(2)^(-) system included hydroxylation reaction and nitrosation reaction,and the nitrosation products had certain toxicological risks.It was found that BPF and its transformation products could be basically eliminated by prolonging the reaction time;thus,BPF basically reached the degree of mineralization.The results of this-study were helpful to understand the activity mechanism of UV/NO_(2)^(-) system and provided basic theoretical support for UV treatment of trace ECs in water.