Sonocatalytic degradation of methylene blue using biochars derived from sugarcane bagasse

Biochars derived from abundant natural biomasses have a very close and practical application for environmental pollution remediation. In this research, one innovative application of biochar derived from sugarcane bagasse was conducted for sonocatalytic degradation of methylene blue. Surface morphologies of the biochar pyrolized at 600 degrees C (BC600) demonstrate that the biochar mainly consists of thin flakes with a size ranged from 10 mu m to 50 mu m. Although the surface area of BC600 is very limited, its sonocatalytic performance outperformed those bagasse biochars pyrolized at other temperatures. The degradation process was well fitted by pseudo-first-order kinetic model. The pseudo-first-order rate constant (K-app) of the sonocatalytic process was 1.77 times that of the sum of K-app values of both ultrasonication and catalyst adsorption, indicating a significant synergetic effect. Increasing catalyst dosage and ultrasonic power enhanced the degradation efficiency apparently. The highest sonocatalytic degradation efficiency was observed at pH 5.0. Oxidation mechanism was explored through quenching tests by iso-propanol and KBr. It indicates that, during the sonocatalytic degradation of methylene blue using bagasse biochar, a free radical chain reaction was proved to occur predominately in the interfacial region while to a lesser extent in bulk solution.