光诱导腐殖酸产生自由基对天然水中雌二醇光降解效能的影响

Influence of free radicals produced by photo-induced humic acid on photodegradation of 17β-estradiol in natural water

以腐殖酸(humic acid,HA)为光敏化剂,采用300 W氙灯模拟太阳光,研究雌二醇(E2)在HA溶液中的光降解动力学。结果表明:E2在HA溶液中的光解反应符合准一级动力学模型,HA对E2光解速率起促进作用,且随着HA浓度的增加(由0增至12 mg·L^(-1))对E2的促进作用增强;当HA继续升高至24 mg·L^(-1)时,HA的光掩蔽作用增强,对E2光解的促进作用减弱。采用电子顺磁共振技术(EPR)直接证明了HA在E2的光解过程中会产生羟基自由基(·OH)。自由基淬灭实验表明·OH和单线态氧(1O2)对E2光解贡献率分别为62%和20%。TOC的去除率远低于E2的去除率,说明E2在光降解过程中并没有被完全矿化。

Under simulated solar irradiation with a 300 W xenon lamp, the photodegradation of 17β-estradiol （E2） was studied in the presence of humic acid （HA）, which acts as a photosensitizer. The results suggested that the photodegradation of E2 followed pseudo-first-order kinetics and the photodegradation rate increased rapidly with increasing the initial concentration of HA from 0 to 12 mg·L-1. While with a further increase in HA concentration to 24 mg·L-1, the promotion of E2 photodegradation would be weakened due to the scavenging of reactive oxygen species. The electron paramagnetic resonance （EPR） analysis revealed that hydroxyl radicals （·OH） were produced during the photolysis of HA process. Quenching experiments results showed that the contribution of ·OH and singlet oxygen （1O2） to E2 degradation was about 62% and 20% , respectively. The mineralization removal efficiency of E2 was significantly lower than the E2 degradation efficiency, indicating that E2 had not been completely mineralized during the photodegradation process.