Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University , Guangzhou 510275, P. R. China.
Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
Environ Sci Technol. 2017 Sep 19;51(18):10431-10439. doi: 10.1021/acs.est.7b02059. Epub 2017 Aug 31.
The UV/chlorine process is an emerging advanced oxidation process (AOP) used for the degradation of micropollutants. However, the radical chemistry of this AOP is largely unknown for the degradation of numerous structurally diverse micropollutants in water matrices of varying quality. These issues were addressed by grouping 34 pharmaceuticals and personal care products (PPCPs) according to the radical chemistry of their degradation in the UV/chlorine process at practical PPCP concentrations (1 μg L) and in different water matrices. The contributions of HO and reactive chlorine species (RCS), including Cl, Cl, and ClO, to the degradation of different PPCPs were compound specific. RCS showed considerable reactivity with olefins and benzene derivatives, such as phenols, anilines, and alkyl-/alkoxybenzenes. A good linear relationship was found between the RCS reactivity and negative values of the Hammett ∑σ constant for aromatic PPCPs, indicating that electron-donating groups promote the attack of benzene derivatives by RCS. The contribution of HO, but not necessarily RCS, to PPCP removal decreased with increasing pH. ClO showed high reactivity with some PPCPs, such as carbamazepine, caffeine, and gemfibrozil, with second-order rate constants of 9.2 × 10, 1.03 × 10, and 4.16 × 10 M s, respectively, which contributed to their degradation. Natural organic matter (NOM) induced significant scavenging of ClO and greatly decreased the degradation of PPCPs that was attributable to ClO, with a second-order rate constant of 4.5 × 10 (mg L) s. Alkalinity inhibited the degradation of PPCPs that was primarily attacked by HO and Cl but had negligible effects on the degradation of PPCPs by ClO. This is the first study on the reactivity of RCS, particularly ClO, with structurally diverse PPCPs under simulated drinking water condition.
UV/氯工艺是一种新兴的高级氧化工艺（AOP），用于降解微量污染物。然而，对于在不同水质的水中，大量结构多样的微量污染物的降解，该 AOP 的自由基化学性质在很大程度上是未知的。通过根据在实际 PPCP 浓度（1μg/L）和不同水质下 UV/氯工艺中降解的自由基化学性质，将 34 种药物和个人护理产品（PPCP）进行分组，解决了这些问题。HO 和反应性氯物种（RCS），包括 Cl、Cl 和 ClO，对不同 PPCP 的降解的贡献因化合物而异。RCS 对烯烃和苯衍生物（如酚类、苯胺类和烷基/烷氧基苯）具有相当高的反应性。对于芳香族 PPCP，发现 RCS 反应性与哈米特∑σ常数的负值之间存在良好的线性关系，这表明供电子基团促进了 RCS 对苯衍生物的攻击。随着 pH 值的增加，HO 而不是 RCS 对 PPCP 去除的贡献降低。ClO 对一些 PPCP（如卡马西平、咖啡因和吉非贝齐）具有高反应性，其二级反应速率常数分别为 9.2×10、1.03×10 和 4.16×10 M s，这有助于它们的降解。天然有机物（NOM）会大量消耗 ClO，并大大降低归因于 ClO 的 PPCP 降解，其二级反应速率常数为 4.5×10（mg/L）s。碱度抑制了主要由 HO 和 Cl 攻击的 PPCP 的降解，但对 ClO 攻击的 PPCP 的降解几乎没有影响。这是首次在模拟饮用水条件下研究 RCS（特别是 ClO）与结构多样的 PPCP 的反应性。
