Interpretation of high perchlorate generated during electrochemical disinfection in presence of chloride at BDD anodes

文献类型： 外文期刊

第一作者： Long, Yujiao

作者： Long, Yujiao;Jin, Hongmei;Long, Yujiao;Ni, Jinren;Li, Hongna

作者机构：

关键词： Perchlorate; Formation mechanism; Boron-doped diamond electrode; Hydroxyl radical; center dot ClO3

期刊名称：CHEMOSPHERE （ 影响因子：7.086； 五年影响因子：6.956 ）

ISSN： 0045-6535

年卷期： 2021 年 284 卷

页码：

收录情况： SCI

摘要： Perchlorate is a disinfection by-product (DBP) of serious health concern. Herein, the long sought mechanism of high perchlorate production during electrochemical disinfection at boron-doped diamond (BDD) anode in the presence of chloride was elucidated. The generated perchlorate at BDD during electrochemical disinfection (in 10 mM NaCl) in 60 min reached 0.125 mM, which was 830 times higher than the EPA standard. In contrast, perchlorate at PbO2 and SnO2 anodes was below the detection limit. Further experiments employing NaClO3 revealed that the conversion ratio from ClO3- to ClO4- in 10 h at BDD (98%) was considerably higher than PbO2 (13%) and SnO2 (12%). Such significant difference among anodes was fully interpreted with a two-step mechanism. The first step is essential to produce center dot ClO3 by oxidizing ClO3- at electrodes. Otherwise, the conversion to perchlorate would be impossible even with excessive center dot OH, which was verified with the photocatalysis process. The second step is the perchlorate generation with radical reaction between center dot ClO3 and center dot OH, where the primary role of center dot OH was substantiated by scavenging test. Interestingly, the capability of perchlorate production was correlated with free center dot OH instead of the total amount of center dot OH. Despite the similar abilities of electron transfer between anodes and ClO3-, much higher free center dot OH exists at BDD anode than at PbO2 and SnO2 anodes through chronoamperometry experiments and work function characterization, which reasonably provides interpretation of high perchlorate production at BDD anode.

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