Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC V6T 1Z3, Canada.
Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC V6T 1Z3, Canada.
Sci Total Environ. 2021 Mar 15;760:143325. doi: 10.1016/j.scitotenv.2020.143325. Epub 2020 Nov 5.
The impact of chloride ion and chlorine radical on the formation of nitrite was investigated under Vacuum-UV (VUV) photolysis of nitrate contaminating water. An increase in chloride concentration reduced nitrite formation in part due to the relatively high VUV absorption of chloride. The use of various radical scavengers, such as acetate and acetone, helped delineate the specific roles of hydroxyl radical (HO) and chlorine radical (Cl) in oxidation and VUV photolysis of nitrate, and the subsequent formation of nitrite. HO reduced nitrite formation due to its high reaction rate constant with nitrite. Nitrite formation in both chloride and dissolved organic carbon (DOC) containing solution depended primarily on their relative concentrations. Carbamazepine (CBZ) was also used to analyze the effect of Cl on both the degradation of CBZ and the formation of nitrite. Cl showed to significantly increase the degradation of CBZ, but it had little impact on the formation of nitrite. This paper, utilizing detailed experimental data combined with kinetic modeling and mechanistic analysis of VUV photolysis in the presence of chloride and nitrate, provides the necessary scientific guidance towards more effective and optimized applications of VUV technology for drinking water treatment.
研究了氯离子和氯自由基对硝酸盐污染水中亚硝酸盐形成的影响。由于氯离子对真空紫外线（VUV）具有较高的吸收，因此增加氯离子浓度会部分降低亚硝酸盐的生成。使用各种自由基清除剂（如乙酸盐和丙酮）有助于阐明羟基自由基（HO）和氯自由基（Cl）在硝酸盐氧化和 VUV 光解中的具体作用，以及随后亚硝酸盐的形成。由于其与亚硝酸盐的高反应速率常数，HO 会减少亚硝酸盐的形成。在含有氯离子和溶解有机碳（DOC）的溶液中，亚硝酸盐的形成主要取决于它们的相对浓度。卡马西平（CBZ）也被用于分析 Cl 对 CBZ 的降解和亚硝酸盐形成的影响。Cl 表现出对 CBZ 降解的显著促进作用，但对亚硝酸盐形成的影响较小。本文利用详细的实验数据，结合 VUV 光解在存在氯离子和硝酸盐时的动力学模型和机理分析，为更有效地优化 VUV 技术在饮用水处理中的应用提供了必要的科学指导。
