ZnIn_2S_4可见光催化降解水中的双氯芬酸

Photocatalytic degradation of aqueous diclofenac by ZnIn_2S_4 under visible light

通过水热法制备了可见光下响应的光催化剂ZnIn_2S_4,研究了水中痕量医药类物质双氯芬酸的光解和光催化降解效果与降解途径,同时对催化剂进行了扫描电镜、X射线衍射、紫外可见漫反射、氮吸附和羟基自由基捕获的测试。结果表明,ZnIn_2S_4的比表面积为91.3 m2·g-1,且在可见光照射下具有良好光催化性能。以卤钨灯模拟太阳光,在双氯芬酸初始浓度100μg·L^(-1),ZnIn_2S_4投加浓度10 mg·L^(-1)条件下反应5 h可降解水中98%的双氯芬酸。卤钨灯直接光解5 h可降解91%的双氯芬酸。光解和光催化反应均符合假一级反应动力学,光催化反应速率是光解反应速率的1.5倍。双氯芬酸光解过程中主要发生光环化反应,生成了2-(1-氯-9H-咔吧唑-8-基)-乙酸;光催化过程则主要通过羟基自由基氧化降解双氯芬酸,中间产物主要有1-氯-8-甲基-9H-咔吧唑及2,6-二氯-N-邻甲苯基苯胺。

The visible-light-responsive catalyst ZnIn_2S_4 was prepared by the hydrothermal method and applied to degrade trace levels of the aqueous pharmaceutical compound diclofenac（ DCF） under visible-light irradiation.The photocatalytic efficacy and degradation pathway of DCF were investigated. The catalyst was characterized by scanning electron microscopy（ SEM）,X-ray diffraction（ XRD）,ultraviolet-visible diffuse reflectance spectroscopy（ UV-vis DRS）,and nitrogen adsorption. The trapping of hydroxyl radicals was also determined in this study. The findings indicated that ZnIn_2S_4 catalyst has a specific surface area of 91. 3 m2·g^-1and shows excellent photocatalytic performance under visible light irradiation. DCF removal reached 98% under conditions of100 μg·L^-1initial concentration,10 mg·L^-1dosage of ZnIn_2S_4,and 5 h of reaction time. In comparison,91% of the DCF was removed after 5 h reaction under light irradiation without the catalyst. Both the photodegradation and photocatalytic degradation of DCF were fit well by a pseudo-first-order kinetic model,and the photocatalytic degradation rate was 1. 5 times greater than the photodegradation rate. The photodegradation of DCF mainly occurred via photocyclization,and 2-（ 8-chloro-9H-carbazoL^-1-yl） acetic acid was the main intermediate product. More active intermediate products were produced by the oxidation of hydroxyl radicals during the photocatalysis,and main degradation products included 1-chloro-8-methyl-9H-carbazole and 2,6-dichloro-N-o-tolylbenzenamine.