研究报告
王广生,付冬彬,刘义青,付永胜.UV/NO3-光化学降解水中的磺胺甲恶唑[J].环境科学学报,2020,40(4):1234-1241
UV/NO3-光化学降解水中的磺胺甲恶唑
- Photochemical degradation of sulfamethoxazole by UV/NO3- in water
- 基金项目：四川省科技厅重点研发项目（No.2017SZ0175）；四川省科技厅重大科技专项（No.2018SZDZX0026）；中央高校基本科研业务费科技创新项目（No.2682018CX32）
- 作者
- 单位
- 王广生
- 西南交通大学地球科学与环境工程学院, 成都 611756
- 付冬彬
- 西南交通大学地球科学与环境工程学院, 成都 611756
- 刘义青
- 西南交通大学地球科学与环境工程学院, 成都 611756
- 付永胜
- 西南交通大学地球科学与环境工程学院, 成都 611756
- 摘要：本文研究了UV/NO3-体系对水中磺胺甲恶唑（SMX）的降解；考察了NO3-用量、pH值、SMX初始浓度、水体成分中常见的无机阴离子（Cl-、SO42-和HCO3-）和天然有机物（NOM）对SMX去除的影响；最后探讨了SMX在该体系中的降解产物和转化机理.结果表明：相比于单独UV，UV/NO3-对SMX的去除效果更优，这可能归因于UV激发NO3-产生的羟基自由基（HO·），通过加入HO·淬灭剂甲醇，有力地证明了体系中HO·的存在及其对SMX的降解作用.SMX在UV/NO3-体系中的降解符合准一级反应动力学.SMX的去除效率随着NO3-浓度的增加而逐渐提高，随着其初始浓度的增大而减小.溶液pH值对UV/NO3-降解SMX的影响显著，SMX去除效率表现为酸性>中性>碱性.向UV/NO3-体系中加入不同浓度的Cl-和SO42-对SMX的降解基本没有影响；HCO3-对SMX的去除有显著的促进作用，这可能归因于HO·同HCO3-反应产生的碳酸根自由基（CO3·-）；NOM的存在会抑制SMX的降解，且NOM浓度越高，抑制越明显.在UV/NO3-降解SMX的反应中，根据检出的5种产物，提出SMX可能的转化机理包括4种不同的反应路径，分别为断键反应、脱氨羟基化、羟基化和亚硝化.
- Abstract：The degradation of sulfamethoxazole (SMX) by UV/NO3- was investigated in this paper. The effects of NO3- dose, pH, initial SMX concentration, common inorganic anions (e.g., Cl-、SO42- and HCO3-) and natural organic matter (NOM) on the removal of SMX were also evaluated. Finally, the degradation products and transformation mechanism of SMX by UV/NO3- were studied. The results showed that compared with UV alone, the degradation of SMX was more efficient in UV/NO3- system due to the role of generated hydroxyl radical (HO·) through the excited NO3- under UV irradiation. The presence of HO· and its role on SMX degradation were confirmed by adding methanol, a scavenger of HO·, in this system. The degradation of SMX in UV/NO3- system followed a pseudo first-order kinetic model. The degradation efficiency of SMX enhanced gradually with the increase in NO3- dose, but decreased with the increase of its initial concentration. The initial pH of solution could significantly influence the degradation of SMX in UV/NO3- system, and the removal of SMX was the best under acidic condition, followed by neutral and alkaline conditions. The common inorganic anions including Cl- and SO42- could hardly affect the removal of SMX, but the presence of HCO3- could significantly enhance SMX degradation in UV/NO3- system, which could probably ascribe to the formation of carbonate radical (CO3·-) through the reaction between generated HO· and HCO3-. NOM could inhibit SMX degradation and the inhibiting effect enhanced with the increase in its concentration. According to five detected products, the possible transformation mechanism of SMX by UV/NO3- was proposed revealing four different degradation pathways, including bond cleavage, deamination-hydroxylation, hydroxylation, and nitrosation.
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