Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha, 410082, China.
Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha, 410082, China.
Water Res. 2020 Jul 1;178:115829. doi: 10.1016/j.watres.2020.115829. Epub 2020 Apr 24.
The presence of nitrite (NO) is inevitable with concentrations of several mg L in some typical water bodies. In this study, UV at wavelength of 365 nm was investigated to degrade contaminants of emerging concern (CECs) in the presence of NO at environmentally relevant concentrations (0.1-5.0 mg L). Six selected CECs with different structures were efficiently removed because of the generation of reactive nitrogen species (RNS) and hydroxyl radical (HO) from photolysis of NO. Contributions of UV photolysis, RNS, and HO to CEC degradation in UV/NO system were calculated, and RNS were found to be the predominant species that are responsible for CEC degradation. The second major contributor is HO for the degradation of selected CECs except for the case of sulfadiazine. Impacts of water matrix components (including dissolved oxygen, solution pH, and natural organic matter) on CEC degradation in UV/NO system were evaluated. Furthermore, evolution profiles of CECs and NO in UV/NO system were tracked when actual water samples were used as background, and a simultaneous removal of CECs and NO was observed. Transformation products of bisphenol A and carbamazepine were proposed according to the results of HPLC/MS and quantum chemistry calculations. Nitration induced by RNS and hydroxylation induced by HO are main reactions occurred during CEC degradation in UV/NO system. Overall, UV is a potential technology to remove CECs and NO in aquatic environment when residual NO is present. Our present study also provides possibility for the application of sunlight to remediate water co-polluted by CECs and NO.
亚硝酸盐（NO）的存在是不可避免的，在一些典型水体中其浓度可达数毫克/升。在这项研究中，研究了波长为 365nm 的紫外线在环境相关浓度（0.1-5.0mg/L）下降解新兴关注污染物（CECs）的情况，同时存在亚硝酸盐。由于 NO 的光解产生了活性氮物种（RNS）和羟基自由基（HO），六种不同结构的选定 CECs 被有效地去除。计算了 UV 光解、RNS 和 HO 对 UV/NO 体系中 CEC 降解的贡献，结果表明 RNS 是主要物种，负责 CEC 的降解。对于所选 CECs 的降解，HO 是仅次于 RNS 的主要贡献者，除了磺胺嘧啶的情况。评估了水基质成分（包括溶解氧、溶液 pH 值和天然有机物）对 UV/NO 体系中 CEC 降解的影响。此外，当实际水样作为背景时，跟踪了 UV/NO 体系中 CECs 和 NO 的演变情况，观察到 CECs 和 NO 的同时去除。根据 HPLC/MS 和量子化学计算的结果，提出了双酚 A 和卡马西平的转化产物。在 UV/NO 体系中，RNS 诱导的硝化和 HO 诱导的羟化是 CEC 降解的主要反应。总体而言，当存在残留的 NO 时，紫外线是去除水生环境中 CECs 和 NO 的一种潜在技术。本研究还为利用阳光修复 CECs 和 NO 共同污染的水提供了可能性。
