Coal fly ash supported Ag@Bi2WO6: A novel heterogeneous nanocomposite for effective sunlight driven photocatalytic degradation of dye

Abstract

Water contamination is a serious environmental issue. It has detrimental effects on the living habitat. This contaminated water is treated with numerous physicochemical techniques. Presently, adsorption-enhanced photo-catalysis is considered among the most efficient method advanced oxidation methods for pollution alleviation. In this study, the novel Ag-doped Bismuth Tungstate and its composite with CFA were successfully synthesized using the hydrothermal-assisted ultra-sonication treatment. The Ag@Bi2WO6 and CFA-based Ag@Bi2WO6 composite samples were well characterized by FTIR, SEM, EDX, and XRD techniques. The characterization analysis supports the successful fabrication of catalysts including key functionalities observed in FTIR, structural morphology, and elemental analysis by SEM-EDX, and perfect crystallinity by XRD analysis. The efficient photocatalytic degradation of methylene blue dye was studied by optimizing several factors, including catalyst dose, pH, oxidant dose concentration, M.B dye concentration, and contact time. The CFA-based Ag@Bi2WO6 composite shows more than 98% photo-catalytic degradation of M.B dye under optimal conditions such as pH 8, oxidant dose 10 mM, catalysts dose 10 mg/100 mL, and reaction time 80 min. The catalyst's surface charge was determined using pH drift method and an effective correlation between the working pH and surface charge was observed to achieve maximum dye degradation efficiency. The effective radicals in promoting the dye degradation were estimated using a radical scavenging experiment and OH radicals were found to be the key radicals in promoting photocatalysis. The reaction kinetics were studied by using pseudo 1st and 2nd order reactions.