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

• Synthesis pH had great influence on morphology and catalytic performance of CaMoO 4. • CaMoO 4 -7 had excellent sonocatalytic performance to the removal of Acid Orange 7. • CaMoO 4 -7 had good stability and reusability during the degradation process. Herein, a series of CaMoO 4 microspheres were prepared at different pH values by the hydrothermal method. The sonocatalytic performances of the prepared CaMoO 4 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 CaMoO 4. The CaMoO 4 microspheres prepared at pH = 7 (CaMoO 4 -7) exhibited superior sonocatalytic performance. The removal ratio of AO7 using CaMoO 4 -7 as a sonocatalyst was 97.02 ± 0.65%. The sonocatalytic removal of AO7 in the presence of CaMoO 4 -7 was mainly attributed to the generation of hydroxyl radical (•OH), superoxide anion radical (•O 2 −) and holes (h +). The optimized operational conditions, such as CaMoO 4 -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, CaMoO 4 -7 had excellent reusability and stability in the sonocatalytic removal process. These results indicated that CaMoO 4 -7 had the potential as the sonocatalyst to apply in the environmental remediation. [ABSTRACT FROM AUTHOR]