Preparation of CuO_x@ZnFe-LDH composites and photocatalytic degradation of 4-nitrophenol by activated persulfate

In order to meet the current challenges of wastewater treatment, a novel, environment-friendly, efficient and economical treatment method has always been an ideal choice for the degradation of organic pollutants. In this work, active and stable CuO_x@ZnFe-LDH composite was prepared via co-precipitation method. A series of characterization methods were used to investigate the structural characteristics of the obtained products. The photocatalytic performance of the prepared composites were evaluate by degrading 4-nitrophenol under mild conditions. Besides, with the addition of persulfate, the photocatalytic degradation activity was greatly enhanced due to the synergistic effect of catalysts and ultraviolet light on persulfate activation. The results showed that CuO_x@ZnFe-LDH composite obtained the best photocatalytic performance compared with ZnFe-LDH and ZnFe-CLDH, which could completely degrade 10 mg/L of 4-nitrophenol in less than 60 min. After four consecutive cycles CuO_x@ZnFe-LDH composite could still remain remarkable reusability and stability. In addition, a possible photocatalytic degradation mechanism was proposed according to the characterization and experimental results. The CuO_x@ZnFe-LDH composite was expected to be an efficient catalyst for energy conversion and environmental treatment. This work also was expected to provide a new idea for designing new type of catalysts for organic pollutants treatment.