亚硝酸盐对硫酸根自由基降解卤代酚的影响  

Influence of nitrite on the degradation of halogenated phenols in sulfate radical oxidation processes

作　　者：桂静婧 刘佳婷 杨培增 陈静 季跃飞[1] 陆隽鹤[1] GUI Jing-jing;LIU Jia-ting;YANG Pei-zeng;CHEN Jing;JI Yue-fei;LU Jun-he(College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China)

机构地区：[1]南京农业大学资源与环境科学学院,江苏南京210095

出　　处：《中国环境科学》2024年第6期3395-3407,共13页China Environmental Science

基　　金：国家自然科学基金资助项目(22076079,22076080);江苏省基础研究计划自然科学基金青年基金项目(BK20231005);江苏省双创博士项目(JSSCBS20210264)。

摘　　要：系统研究了亚硝酸盐(NO_(2)^(-))对硫酸根自由基(SO_(4)^(•-))降解溴酚和氯酚的影响.结果表明,NO_(2)^(-)的加入明显促进了溴酚的降解,而氯酚的降解仅受到轻微促进;此外,两者都转化生成了有毒硝基产物.研究发现,卤代酚在SO_(4)^(•-)氧化过程中发生脱卤反应,脱下来的卤离子被SO_(4)^(•-)氧化为卤自由基和自由卤.其随后和中间产物甚至母体反应,生成卤代副产物,如卤仿和卤乙酸.若反应过程中存在NO_(2)^(-),首先,原位生成的活性卤物质能够被NO_(2)^(-)迅速捕获,生成强氧化性的硝酰卤.硝酰卤进攻卤代酚,导致其加速降解并生成硝基副产物.其次,NO_(2)^(-)被SO_(4)^(•-)氧化生成二氧化氮自由基(NO2•),其随后与卤代酚转化生成的酚氧自由基中间体结合,同样产生大量硝基卤代产物.数据显示,硝基溴酚的种类更多且产量更高.当加入200μmol/L NO_(2)^(-),溶液中硝基溴酚和硝基氯酚的总生成量最高分别可至9.2和5.7μmol/L.这是因为在SO_(4)^(•-)氧化过程中,溴酚较氯酚更容易发生脱卤反应,因此NO_(2)^(-)对溴酚转化行为的影响更显著.研究揭示了SO_(4)^(•-)氧化技术应用于地下环境中降解卤代污染物时的潜在风险,并对该过程中氮素和卤素的相互转化提供了新的见解.The influence of nitrite(NO_(2)^(-))on the degradation of bromophenol and chlorophenol by sulfate radical(SO_(4)^(•-))oxidation was systematically investigated in this work.Results showed that the presence of NO_(2)^(-)accelerated the degradation of bromophenol,while posed a weak effect on the degradation of chlorophenol.Meanwhile,NO_(2)^(-)led to a series of toxic nitrated byproducts.Upon SO_(4)^(•-)oxidation,halophenols underwent dehalogenation and the released halides can be further oxidized by SO_(4)^(•-)to form reactive halogen species,which rapidly react with some intermediates and the parent compounds to form halogenated byproducts,such as haloform and haloacetic acid.Once NO_(2)^(-)was co-present,these reactive halogen species can be scavenged by NO_(2)^(-)to form a strong oxidizing agent,nitryl halide.Then nitryl halide reacts with the parent halophenol,promoting their degradation and resulting in the formation of nitrated byproducts.Besides,NO_(2)^(-)can be oxidized to nitrogen dioxide radicals(NO2•)by SO_(4)^(•-),which further couple with phenoxy radicals generated from the oxidation of halophenols by SO_(4)^(•-),yielding nitrated byproducts as well.Note that,the formation of nitrated byproducts from bromophenol(9.2μmol/L)was significantly higher than those generated from chlorophenol(5.7μmol/L)with 200μmol/L NO_(2)^(-)present.In SO_(4)^(•-)oxidation process,bromophenol is more prone to dehalogenation than chlorophenol.Therefore,the influence of NO_(2)^(-)on the transformation of bromophenol was more drastic than that of chlorophenol by SO_(4)^(•-).These findings reveal potential risks of the application of SO_(4)^(•-)oxidation technologies for the remediation of halogenated contaminants in the subsurface environment,and provide new insights into the interaction of nitrogen and halogen in SO_(4)^(•-)oxidation processes.

关 键 词：溴酚 氯酚 硫酸根自由基 亚硝酸盐 硝酰卤 硝基副产物 

分 类 号：X703.5[环境科学与工程—环境工程]