Catalytic degradation of phenol in sonolysis by coal ash and H2O2/O3

This study demonstrated that coal ash, as widely distributed solid waste disposal, would function as a media for organic pollutants removal in the presence or absence of H2O2/O3 under ultrasonic radiation. Coal ash could act as a catalyst to generate OH radicals with the presence of H2O2/O3 and consequently enhance the phenol degradation. Experimental results showed that when using coal ash as a catalyst under ultrasonic irradiation, 83.4% and 88.8% of phenol was degraded in the presence of H2O2 or O3, respectively. The degradation rate of phenol would increase with increasing amount of O3, while there was an optimal concentration of H2O2 (1.5 mM) for phenol degradation. Higher dosage of coal ash could result in higher phenol degradation rates. H2O2/coal ash/ultrasonic system could achieve better performance for phenol degradation under more acidic conditions, while more alkaline condition in O3/coal ash/ultrasonic system favored phenol degradation. This study provides a new approach for wastewater treatment especially when contaminated with phenolic pollutants.