Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China.
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China.
Water Res. 2017 Apr 1;112:1-8. doi: 10.1016/j.watres.2017.01.025. Epub 2017 Jan 16.
Peroxymonosulfate (PMS) is a promising alternative for drinking water disinfection; also many organic micropollutants may be present in drinking water sources nowadays. However, pipe corrosion products (PCPs) may impact the reactions between a disinfectant and organic micropollutants in water distribution systems. This study investigated iopamidol (IPM) degradation by PMS under catalysis of two PCPs (i.e., CuO and δ-MnO). The pseudo-first-order rate constant of IPM degradation in the CuO/PMS system (CuPS) was 3.7 times of that in the δ-MnO/PMS system (MnPS), with values of 0.218 and 0.059 min, respectively. Sulfate radical (SO) was the major contributor to IPM degradation in the CuPS, while hydroxyl radical (HO) also played an important role in the MnPS. The radical yield ratio was 0.89 and 0.69 mol/mol in the CuPS and MnPS, respectively. The IPM degradation rate increased with increasing PMS dose, and reached a maximum with a PCP dose of 1.0 and 1.5 g L in the CuPS and MnPS, respectively. The highest degradation efficiency was achieved at pH 7.0 in the two systems. The water matrix (i.e., natural organic matter, alkalinity and chloride) had detrimental effects on IPM degradation to different degrees. The majority of the iodine released from IPM was oxidized to iodate (IO) and a small fraction of the initial total organic iodine was transformed to iodoform (CHI). The IPM degradation by PMS mainly proceeded through two pathways: (1) amide hydrolysis of side chain A, amino oxidation, and amide hydrolysis of side chains B and B' in sequence; and (2) deiodination reactions.
过一硫酸盐（PMS）是饮用水消毒的一种很有前途的替代物；如今，许多有机微量污染物也可能存在于饮用水源中。然而，管道腐蚀产物（PCPs）可能会影响消毒剂和水中有机微量污染物在配水系统中的反应。本研究考察了两种 PCP（氧化铜和 δ- 氧化锰）催化下过一硫酸盐（PMS）对碘海醇（IPM）的降解。在氧化铜/过一硫酸盐（CuPS）体系中，IPM 的降解符合准一级动力学，其反应速率常数为 0.218 min，是 δ- 氧化锰/过一硫酸盐（MnPS）体系（0.059 min）的 3.7 倍。在 CuPS 体系中，硫酸根自由基（SO）是 IPM 降解的主要贡献者，而在 MnPS 体系中，羟基自由基（HO）也起着重要作用。CuPS 和 MnPS 中的自由基产率比分别为 0.89 和 0.69 mol/mol。在 CuPS 和 MnPS 中，随着过一硫酸盐剂量的增加，IPM 的降解速率增加，当 PCP 剂量分别为 1.0 和 1.5 g/L 时达到最大值。在这两个体系中，pH 值为 7.0 时，降解效率最高。水基质（即天然有机物、碱度和氯离子）对 IPM 降解有不同程度的不利影响。从 IPM 释放的大部分碘被氧化为碘酸（IO），初始总有机碘的一小部分转化为碘仿（CHI）。PMS 对 IPM 的降解主要通过两条途径进行：（1）侧链 A 的酰胺水解、氨基氧化以及侧链 B 和 B'的酰胺水解依次进行；（2）脱碘反应。
