Preparation of CuWO4/CaWO4 n–n heterojunction with enhanced sonocatalytic performance: Characterization, sonocatalytic mechanism and degradation pathways of organic pollutant

Abstract

In this paper, a novel CuWO₄/CaWO₄ n–n heterojunction was prepared by a hydrothermal method and characterized. Using acid orange 7 (AO7) as simulated dye wastewater, the sonocatalytic performance of CuWO₄/CaWO₄ composite was investigated. The results suggested that 15 %CuWO₄/CaWO₄ had the optimum sonocatalytic performance for the removal of AO7. The optimal reaction conditions were as follows: the addition amount of sonocatalyst was 1.0 g/L, the pH value of AO7 was 5, the initial concentration of dye was 5 mg/L, the ultrasonic power was 200 W, the molar ratios of K₂S₂O₈ to AO7 was 70, and the time of ultrasonic irradiation was 120 min, the removal rate of AO7 could reach 93.37 ± 0.76(%). The results showed that the construction of CuWO₄/CaWO₄ heterojunction could significantly improve the production of active components in the sonocatalytic system, which played an important role in the sonocatalytic removal process of AO7. In addition, the CuWO₄/CaWO₄ composite catalyst showed good stability. Moreover, the results of AO7 degradation products and their environmental toxicity evaluation showed that the combined use of sonocatalysis and S-AOPs could achieve effective degradation of AO7 and significantly reduced the environmental toxicity of organic pollutants. These results revealed that the CuWO₄/CaWO₄ composite had potential value in the field of sonocatalysis and provided valuable information for the development of hybrid processes based on sonocatalysis coupled with S-AOPs to remove organic pollutants from wastewater.