Comparative study of photocatalytic activity of nanocomposites prepared from biological wastes and ZnO nanoparticles

In this study, binary chitosan/zinc oxide (CS/ZnO) nanocomposite, ternary chitosan/activated carbon prepared from apricot stones/zinc oxide (CS/ACAS/ZnO) and chitosan/activated carbon prepared from animal bones/zinc oxide (CS/ACAB/ZnO) nanocomposites were synthesized for the comparative photocatalytic study of methylene blue dye in simulated contaminated water. The prepared CS/ZnO, CS/ACAS/ZnO and CS/ACAB/ZnO nanocomposites were systematically characterized using X-ray diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy. High rates of degradations were observed for CS/ACAS/ZnO (97%, 40 min) followed by CS/ACAB/ZnO (92%, 80 min) at initial pH, with an adsorbent dose of 100 mg at room temperature and for an initial concentration of 10 mg/L methylene blue. After comparison, the CS/ ACAS/ZnO and CS/ACAB/ZnO nanocomposites exhibited the best photocatalytic performance for the methylene blue degradation under visible light irradiation. The kinetics of pseudo-first-order and pseudo-second-order models were checked to evaluate the photocatalytic performances of the considered nanocomposites. The results confirmed the successful incorporation of ZnO nanoparticles onto CS/ZnO, CS/ACAS/ZnO and CS/ACAB/ZnO and demonstrated that the use of activated carbons as a support for ZnO is a viable alternative and present a great interest for photocatalysis.