CHEN Feifan, CHEN Hu, WANG Ying, LIU Shilong, ZHANG Hailong, LYU Yongkang
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ZnO is widely applied in the photocatalytic degradation of organic pollutants. Currently, the removal rate of target pollutants and chemical oxygen demand (COD) are often used as indicators in the research, which are difficult to truly reflect the mineralization effect of pollutants. This paper first prepares ZnO catalysts through three methods: direct precipitation, sol-gel method, and controlled precipitation. The structure, morphology, and optical properties of the prepared photocatalysts are analyzed by various characterization methods such as XRD, SEM, FT-IR, XPS, BET, UV-Vis, and PL. The results show that the ZnO synthesized by the controlled precipitation method has a larger specific surface area, uniform particle morphology, and stronger ultraviolet light absorption ability. Then, the photocatalytic mineralization effect of ZnO catalysts on phenol was systematically studied using total organic carbon (TOC) removal as the index. It was found that the ZnO catalyst synthesized by the controlled precipitation method exhibited excellent photocatalytic activity and stability under ultraviolet light irradiation. Under the optimal conditions of catalyst dosage of 3 g/L, initial phenol concentration of 40 mg/L, and solution pH=7, an 83% TOC removal was achieved after 5 h of xenon light irradiation. Finally, GC-MS method was used to detect the intermediate products of photodegradation of phenol such as methyl butyrate and benzoquinone, and a possible degradation mechanism was proposed. This catalyst shows good photocatalytic performance in a wide range of phenol concentrations and in neutral, acidic, and alkaline environments, presenting a promising application prospect in the mineralization of organic pollutants.