Du Ye, Wang Wen-Long, Wang Zhi-Wei, Yuan Chang-Jie, Ye Ming-Qi, Wu Qian-Yuan
College of Architecture and Environment, Sichuan University, Chengdu 610000, China.
Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Environ Sci Technol. 2023 Feb 28;57(8):3311-3322. doi: 10.1021/acs.est.2c06965. Epub 2023 Feb 14.
Byproduct formation (chlorate, bromate, organic halogen, etc.) during sulfate radical (SO)-based processes like ultraviolet/peroxymonosulfate (UV/PMS) has aroused widespread concern. However, hypohalous acid (HOCl and HOBr) can form via two-electron transfer directly from PMS, thus leading to the formation of organic halogenated byproducts as well. This study found both PMS alone and UV/PMS can increase the toxicity to mammalian cells of wastewater, while the UV/HO decreased the toxicity. Cytotoxicity of two wastewater samples increased from 5.6-8.3 to 15.7-29.9 mg-phenol/L, and genotoxicity increased from 2.8-3.1 to 5.8-12.8 μg 4-NQO/L after PMS treatment because of organic halogen formation. Organic halogen formation from bromide rather than chloride was found to dominate the toxicity increase. The SO-based process UV/PMS led to the formation of both organic halogen and inorganic bromate and chlorate. However, because of the very low concentration (<20 μg/L) and relatively low toxicity of bromate and chlorate, contributions of inorganic byproducts to toxicity increase were negligible. PMS would not form chlorate and bromate, but it generated a higher concentration of total organic halogen, thus leading to a more toxic treated wastewater than UV/PMS. UV/PMS formed less organic halogen and toxicity because of the destruction of byproducts by UV irradiation and the removal of byproduct precursors. Currently, many studies focused on the byproducts bromate and chlorate during SO-based oxidation processes. This work revealed that the oxidant PMS even needs more attention because it caused higher toxicity due to more organic halogen formation.
在基于硫酸根自由基（SO）的过程（如紫外光/过一硫酸氢钾复合盐（UV/PMS））中副产物（氯酸盐、溴酸盐、有机卤化物等）的形成已引起广泛关注。然而，次卤酸（HOCl和HOBr）可通过过一硫酸氢钾复合盐直接进行双电子转移形成，进而也会导致有机卤化副产物的形成。本研究发现，单独的过一硫酸氢钾复合盐以及UV/PMS都会增加废水对哺乳动物细胞的毒性，而UV/HO会降低毒性。由于有机卤化物的形成，两个废水样品经PMS处理后细胞毒性从5.6 - 8.3 mg苯酚/L增加到15.7 - 29.9 mg苯酚/L，遗传毒性从2.8 - 3.1 μg 4 - NQO/L增加到5.8 - 12.8 μg 4 - NQO/L。发现由溴化物而非氯化物形成的有机卤化物主导了毒性的增加。基于硫酸根自由基的UV/PMS过程导致了有机卤化物以及无机溴酸盐和氯酸盐的形成。然而，由于溴酸盐和氯酸盐的浓度极低（<20 μg/L）且毒性相对较低，无机副产物对毒性增加的贡献可忽略不计。过一硫酸氢钾复合盐不会形成氯酸盐和溴酸盐，但它产生的总有机卤化物浓度更高，因此导致处理后的废水毒性比UV/PMS更高。UV/PMS形成的有机卤化物和毒性较少，这是因为紫外光辐射破坏了副产物以及去除了副产物前体。目前，许多研究聚焦于基于硫酸根自由基的氧化过程中的副产物溴酸盐和氯酸盐。这项工作表明，氧化剂过一硫酸氢钾复合盐甚至更值得关注，因为它因形成更多有机卤化物而导致更高的毒性。
