Bmim[OAc]-Cu2O/g-C3N4 as a multi-function catalyst for sonophotocatalytic degradation of methylene blue

In this study, ionic liquid, 1-butyl-3-methylimidazolium acetate (Bmim [OAc]) modified cuprous oxide immobilized over graphitic carbon nitride (Bmim [OAc]-Cu2O/g-C3N4) as an efficient heterogeneous catalyst was successfully prepared by depositing Bmim[OAc]-Cu2O over the surface of g-C3N4. The deposition of cuprous oxide over the surface of g-C3N4 leads to the formation of a heterojunction that promotes the charge separation. Cu2O enhances the degradation capability owing to its dual function where it acts as a photocatalyst and Fenton like catalyst. Bmim[OAc] plays a vital role in trapping the photogenerated electrons, which in turn reduce the chances of electron-hole pairs recombination. Sonophotocatalytic degradation of methylene blue (MB) was investigated using the prepared Bmim[OAc]-Cu2O/g-C3N4 at room temperature and pH = 7 in presence of ultraviolet (UV, 6 W, lambda = 254 nm) and ultrasonic (US, 20 kHz) as a dual irradiation system and H2O2 as an oxidant. Only 30 min of dual irradiation was enough for Bmim[OAc]-Cu2O/g-C3N4 (0.1 gL(-1)) to achieve a complete degradation using 10 mM H2O2 at 25 degrees C and pH = 7. The value of band gap of tested catalyst plays a vital role in boosting the degradation capability of the sonophotocatalytic system through the generated reactive radicals especially the hydroxyl radicals and superoxide radicals, which play a major role in the system. The kinetics of the reaction was investigated and the activation energy was calculated from the slope of the Arrhenius plot and found to be 19.77 kJ/mol.