State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, P.R. China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, P.R. China.
Department of Safety, Health and Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 824, Taiwan, R.O.C.
Water Res. 2021 Apr 1;193:116851. doi: 10.1016/j.watres.2021.116851. Epub 2021 Jan 19.
This study investigated the mechanisms of mixed IO/I system under UV irradiation in drinking water and compared the iodinated trihalomethanes (I-THMs) formation of a mixed IO/I system to that of single I and IO systems during subsequent chloramination. The effects of initial I/IO molar ratio, pH, and UV intensity on a mixed IO/I system were studied. The introduction of I enhanced the conversion rate of IO to reactive iodine species (RIS). Besides, IO degradation rate increased with the increase of initial I concentration and UV intensity and the decrease of pH value. In a mixed IO/I system, IO could undergo direct photolysis and photoreduction by hydrated electron (e). Moreover, the enhancement of I-THM formation in a mixed IO/I system during subsequent chloramination was observed. The I-THM yields in a mixed IO/I system were higher than the sum of I-THMs produced in a single IO and I systems at all the evaluated initial I concentrations and pH values. The difference between I-THM formation in a mixed IO/I system and the sum of I-THMs in a single IO and I systems increased with the increase of initial I concentration. As the initial pH decreased from 9 to 5, the difference of I-THM yields enhanced, while the total I-THM yield of a mixed IO/I system and single I and IO systems decreased slightly. Besides, IO-I-containing water with DOC concentration of 2.5-4.5 mg-C/L, which mainly contained humic-acid substances, had a higher risk in I-THMs formation than individual I-containing and IO-containing water.
本研究考察了饮用水中混合 IO/I 体系在紫外辐射下的作用机制，并比较了后续氯胺化过程中混合 IO/I 体系与单一 I 和 IO 体系的碘代三卤甲烷（I-THMs）生成情况。考察了初始 I/IO 摩尔比、pH 值和紫外强度对混合 IO/I 体系的影响。结果表明，I 的存在会提高 IO 向反应性碘物种（RIS）的转化率。此外，随着初始 I 浓度和紫外强度的增加以及 pH 值的降低，IO 降解速率增加。在混合 IO/I 体系中，IO 可以通过水合电子（e）发生直接光解和光还原。此外，在后续氯胺化过程中观察到混合 IO/I 体系中 I-THM 生成增强。在所有评估的初始 I 浓度和 pH 值下，混合 IO/I 体系中的 I-THM 产率均高于单一 IO 和 I 体系中产生的 I-THM 之和。在混合 IO/I 体系中 I-THM 生成与单一 IO 和 I 体系中 I-THM 生成之间的差异随着初始 I 浓度的增加而增加。随着初始 pH 值从 9 降低到 5，I-THM 产率的差异增加，而混合 IO/I 体系以及单一 I 和 IO 体系的总 I-THM 产率略有降低。此外，DOC 浓度为 2.5-4.5 mg-C/L 的含有 IO 的水，主要含有腐殖酸物质，其 I-THMs 生成风险高于单独含有 I 和 IO 的水。
