Transformation of diazepam in water during UV/chlorine and simulated sunlight/chlorine advanced oxidation processes
Transformation of diazepam in water during UV/chlorine and simulated sunlight/chlorine advanced oxidation processes
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紫外线/氯和模拟阳光/氯高级氧化过程中地西泮在水中的转化
DOI：
10.1016/j.scitotenv.2020.141332
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发表时间：
2020
影响因子：
9.8
通讯作者：
Guang-Guo Ying
中科院分区：
文献类型：
--
作者：
Bin Yang;Tao Peng;Wen-Wen Cai;Guang-Guo Ying
精神活性药物地西泮是临床上广泛使用的苯二氮卓类药物之一。已发现它对氯化和光解具有相对抵抗力。本文研究了地西泮在水溶液中通过紫外光/氯气和模拟阳光/氯气处理的转化机理。结果表明，紫外光/氯和太阳光/氯处理显著提高了水中地西泮的降解率。这些观察到的降解可以解释由原位生成的活性物种，包括羟基自由基（HO自由基点），活性氯物种（RCS）和臭氧（O3）在光解过程中。在紫外光/氯气处理中，HO自由基点、氯气、紫外光和RCS反应在90 min时对地西泮的降解率分别为62.1%、3.8%、11.9%和12.3%。在模拟的阳光/氯气处理中，HO自由基点、氯气和RCS反应的降解率分别为53.1%、8.1%和11.2%，O3反应和阳光照射的降解率可以忽略不计。在紫外线/氯和阳光/氯处理中，使用高分辨率TripleTOF质量系统检测到总共70种转化产物。初步提出地西泮的6种转化途径，包括羟基化、氯化、水解、N-脱甲基、苯基丢失、苯二氮杂环重排和缩环。根据毒性预测工具，所获得的大部分转化产物对包括鱼类、水蚤和绿色藻类在内的水生生物的毒性低于地西泮本身，并且对发光细菌的毒性没有引起显著变化。
Psychoactive drug diazepam is one of benzodiazepines widely used in human medicine. It has been found to be relatively resistant to chlorination and photolysis. Here we investigated the transformation mechanism of diazepam in aqueous solution through UV/chlorine and simulated sunlight/chlorine treatments. The results showed that the UV/chlorine and sunlight/chlorine processes significantly increased the degradation of diazepam in water. These observed degradations can be elucidated byin-situgeneration of reactive species including hydroxyl radical (HOradical dot), reactive chlorine species (RCS) and ozone (O3) during photolysis of chlorine. In the UV/chlorine treatment, the degradation efficiency of diazepam for HOradical dot, chlorine, UV and RCS reaction at 90 min was calculated to be 62.1%, 3.8%, 11.9% and 12.3%, respectively. In the simulated sunlight/chlorine treatment, the calculated degradation of 53.1%, 8.1% and 11.2% was attributed to HOradical dot, chlorine and RCS reaction, with negligible loss by O3reaction and sunlight irradiation. In the UV/chlorine and sunlight/chlorine treatments, a total of 70 transformation products was detected using a high-resolution TripleTOF mass system. Six transformation pathways have been tentatively proposed for the diazepam, which includes hydroxylation, chlorination, hydrolyzation,N-demethylation, loss of phenyl group, benzodiazepine ring rearrangement and contraction. Most of the obtained transformation products were less toxic to aquatic organisms including fish, daphnia and green algae than diazepam itself according to the toxicity prediction tool, and did not cause significant changes in toxicity to luminescent bacteria.