ZnIn2S4可见光催化降解氟伐他汀的性能与机理

以氟伐他汀为目标污染物，以功率为500 W的长弧氙灯为光源，通过水热法制备可见光催化剂ZnIn2S4，研究ZnIn2S4对氟伐他汀的光催化降解性能，考察了氟伐他汀初始浓度、ZnIn2S4投加量、溶液pH对ZnIn2S4光催化降解氟伐他汀性能的影响。通过原位捕获实验确定ZnIn2S4可见光催化降解氟伐他汀过程中产生的自由基，通过液相色谱-离子阱-飞行时间质谱(LCMS-IT-TOF)来鉴别降解过程的中间产物，提出氟伐他汀可能的降解路径及机理。结果表明：ZnIn2S4光催化降解氟伐他汀的最佳条件为氟伐他汀初始浓度10 mg·L-1、催化剂投加量0.2 g·L-1、pH接近5，在最佳条件下氟伐他汀的降解率可达到83.6%，矿化率可达到45.8%。原位捕获实验结果表明，超氧自由基是在ZnIn2S4可见光催化降解氟伐他汀过程中起主要氧化作用的活性自由基，羟基自由基和过氧化氢对氟伐他汀的降解起到了辅助作用。氟伐他汀的降解机理是超氧自由基为主、羟基自由基和过氧化氢为辅联合攻击环状结构与直链相连的C—N键、C—C键以及直链和环状结构中的C＝C键，生成小分子的环状有机物、直链有机物以及羟基化衍生物，中间产物进一步被氧化并最终被分解成CO2和H2O。

Performance and mechanism of photocatalytic degradation of fluvastatin by ZnIn2S4 under visible-light irradiation

ZnIn2S4 was prepared by hydrothermal method and used to study the photocatalytic degradation of fluvastatin under a 500 W xenon lamp. The effects of operational parameters such as initial concentration of fluvastatin, photocatalyst concentration and pH on photocatalytic degradation of fluvastatin were investigated. The active radicals produced during the degradation of fluvastatin by ZnIn2S4 were determined by in situ capture experiments. The intermediate products of the degradation process were identified by LCMS-IT-TOF and the possible degradation pathways and mechanisms of fluvastatin were proposed. The the optimal conditions of degradation of fluvastatin were that the concentration of ZnIn2S4 and fluvastatin was 0.2 g·L-1 and 10 mg·L-1, respectively, and the optimal pH was close to 5. The degradation rate of fluvastatin reached 83.6%, and the mineralization rate reached 45.8% under optimal condition. The results of in situ capture experiments showed that the superoxide radicals play a major role in the degradation of fluvastatin, hydroxyl radical and hydrogen peroxide, which play auxiliary roles during photocatalytic process. Degradation of fluvastatin was achieved through cleavage of C—N bond, C—C bond and C＝C bond to generate small molecules which were further mineralized into CO2 and H2O.