Sonocatalytic degradation of Reactive Yellow 39 using synthesized ZrO2 nanoparticles on biochar

ZrO2-biochar (ZrO2-BC) nanocomposite was prepared by a modified sonochemical/sol–gel method. The physicochemical properties of the prepared nanocomposite were evaluated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray fluorescence, Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller model. The sonocatalytic performance of ZrO2-BC was investigated in sonochemical degradation of Reactive Yellow 39 (RY39). The high observed sonocatalytic activity of the ZrO2-BC sample could be interpreted by the mechanisms of sonoluminescence and hot spots. Parameters including ZrO2-BC dosage, solution pH, initial RY39 concentration and ultrasonic power were selected as the main operational parameters and their influence on RY39 degradation efficiency was examined. A 96.8% degradation efficiency was achieved with a ZrO2-BC dosage of 1.5 g/L, pH of 6, initial RY39 concentration of 20 mg/L and ultrasonic power of 300 W. In the presence of OH radical scavengers, RY39 degradation was significantly inhibited, providing evidence for the key role of hydroxyl radicals in the process. The sonodegradation intermediates were identified using gas chromatography-mass spectroscopy and the possible decomposition route was proposed.