Synthesis of CaMoO4 microspheres with enhanced sonocatalytic performance for the removal of Acid Orange 7 in the aqueous environment

Abstract Herein, a series of CaMoO4 microspheres were prepared at different pH values by the hydrothermal method. The sonocatalytic performances of the prepared CaMoO4 microspheres were estimated by the removal of Acid Orange 7 (AO7) as a model of organic pollutants. The results showed that the synthesis pH had a great influence on the morphology and the sonocatalytic performance of CaMoO4. The CaMoO4 microspheres prepared at pH = 7 (CaMoO4-7) exhibited superior sonocatalytic performance. The removal ratio of AO7 using CaMoO4-7 as a sonocatalyst was 97.02 ± 0.65%. The sonocatalytic removal of AO7 in the presence of CaMoO4-7 was mainly attributed to the generation of hydroxyl radical (•OH), superoxide anion radical (•O2−) and holes (h+). The optimized operational conditions, such as CaMoO4-7 dose, initial concentration of AO7, initial pH of AO7, ultrasonic power and ultrasonic time were 1.0 g/L, 5 mg/L, pH = 5, 200 W and 120 min, respectively. In addition, CaMoO4-7 had excellent reusability and stability in the sonocatalytic removal process. These results indicated that CaMoO4-7 had the potential as the sonocatalyst to apply in the environmental remediation.