Kinetics and pathways of the degradation of PPCPs by carbonate radicals in advanced oxidation processes
Kinetics and pathways of the degradation of PPCPs by carbonate radicals in advanced oxidation processes
复制标题
高级氧化过程中碳酸盐自由基降解 PPCP 的动力学和途径
DOI：
10.1016/j.watres.2020.116231
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发表时间：
2020
期刊：
影响因子：
12.8
通讯作者：
Jingyun Fang
中科院分区：
文献类型：
--
作者：
Yujie Zhou;Chunyan Chen;Kaiheng Guo;Zihao Wu;Liping Wang;Zhechao Hua;Jingyun Fang
碳酸根(CO3·−)是一种典型的二次自由基，广泛存在于工程体系和天然水体系中。研究了20种药物和个人护理用品(PPCP)在CO_3·−作用下的降解动力学，以及对CO_3·−敏感的典型PPCP(萘普生)的转化途径。CO_3·−对含苯胺基、酚羟基和萘环的化合物，如磺胺甲恶唑、磺胺二甲嘧啶、沙丁胺醇、普萘洛尔、萘普生和大环内酯类抗生素如阿奇霉素具有很高的选择性，其二级反应速率常数范围为5.6M×107M−1S−1~2.96M×108M−1S−1。KCO3·−的自然对数与芳香族PPCPs的HammettΣσp+常数负值呈良好的线性关系，表明给电子基促进了苯衍生物被CO3·−的攻击。在HCO3·−存在下，在UV/H_2O_2、UV/过硫酸盐、UV/氯和UV/一氯胺等不同过程中，CO_3·−对萘普生降解的贡献显著，弥补了初级自由基贡献的降低。特别是，在紫外光/一氯胺体系中，有50 mM HCO3−存在时，生成的CO3·−使萘普生的一级速率常数比无HCO3−时提高了127%。天然有机物(NOM)对CO3·−有微弱的清除作用，减弱了NOM对HCO3·−存在下UV/H2O2降解萘普生的抑制作用。CO3·−转化萘普生的途径包括脱羧基、羟基化、酮化、去甲基化和缩醛。此外，CO3·−降解萘普生过程中的遗传毒性变化可以忽略不计。
The carbonate radical (CO3•−) is a typical secondary radical observed in engineering and natural aquatic systems. This study investigated the degradation kinetics of 20 pharmaceuticals and personal care products (PPCPs) by CO3•−and the transformation pathways of a typical PPCP (naproxen) that is susceptible to CO3•−. CO3•−is highly selective for compounds containing aniline and phenolic hydroxyl groups as well as naphthalene rings, such as sulfamethoxazole, sulfamethazine, salbutamol, propranolol, naproxen, and macrolide antibiotics such as azithromycin, for which the second-order rate constants range from 5.6 × 107M−1s−1to 2.96 × 108M−1s−1. A good linear relationship is observed between the natural logarithms ofkCO3•−and the negative values of the Hammett Σσp+constant for aromatic PPCPs, indicating that electron-donating groups promote the attack of benzene derivatives by CO3•−. The contribution of CO3•−to naproxen degradation is significant in different processes such as UV/H2O2, UV/persulfate, UV/chlorine, and UV/monochloramine, in the presence of HCO3−, which compensates for the decreased contributions of primary radicals. In particular, the formation of CO3•−increases the first-order rate constant of naproxen by 127% in UV/monochloramine in the presence of 50 mM HCO3−compared to that without HCO3−. Natural organic matter (NOM) exerts a slight scavenging effect on CO3•−, decreasing the inhibition effect of NOM on the degradation of naproxen by UV/H2O2in the presence of HCO3−. The pathways involved in the transformation of naproxen by CO3•−include decarboxylation, hydroxylation, ketonization, demethylation and aldolization. In addition, the alteration of the genotoxicity during naproxen degradation by CO3•−was negligible.