磺胺二甲嘧啶在水溶液中的光化学降解

Photochemical degradation of sulfamethazine in aqueous solution

为了研究磺胺二甲嘧啶(SM_2)的环境光化学行为,更好地理解磺胺类抗生素在实际环境中的归趋和生态效应,实验研究了SM_2在水溶液中的光降解动力学及环境因素对其光解的影响,探讨了不同初始浓度(1、2、5、10、15、20 mg·L^(-1))、不同光源(1000 W氙灯和300 W汞灯)、不同pH(2.0、3.0、5.0、7.0、8.0、9.0、10.0、11.0)、不同类型腐殖质[腐植酸(HA)和富里酸(FA)]对SM_2光解的影响。结果表明:在300 W汞灯和1000 W氙灯2种光源下,SM_2的光解均符合准一级动力学方程,但其光解速率常数存在明显差异,k(300W汞灯)>k(1000 W氙灯);在同一光源下,SM_2的光解速率常数随着初始浓度的增加而减小。溶液pH显著影响SM_2的光解速率。在300 W汞灯照射下,HA和FA均抑制了SM_2的光解,并且随着HA或FA浓度的增加,抑制效果更为明显;在相同光解条件下,HA对SM2光解的抑制作用大于FA。

As an emerging contaminant, sulfamethazine（SM2） has been widely detected in environmental waters. Investigating the environmental photochemical behavior of SM2 in aqueous solution is of great significance for understanding its environmental fates and ecological effects. In this study, the effects of light sources, initial concentrations, pH and humic acids on the photochemical degradation of SM2 in aqueous solution were investigated. Results indicated that the photolysis of SM2 followed pseudo-first-order kinetics equation, and the photolytic rate constants of SM2 under different light sources were significantly different, k（300 W ML〉k（1000 W XL）. Under the same photolysis conditions, its photolytic rate constants decreased with increasing initial SM2 concentrations. The solution pH significantly influenced the photolysis rates of SM2. With the irradiation of 300 W ML, humic acid（HA） and fulvic acid（FA） could inhibit SM2 photolysis, and the inhibitory effects became more obvious at increased concentrations of HA or FA, mainly because of masking effect of light. The inhibitory effect of HA on SM2 photolysis was greater than that of FA.