Magnetic zinc oxide/silica microbeads for the photocatalytic degradation of azo dyes

Photocatalysis is a promising technique for the complete degradation of azo dyes that are present in wastewater. In this work, a new photocatalyst in the form of ZnO/Fe3O4/SiO2 hybrid microbeads was fabricated for the photocatalytic degradation of methylene blue. The microbeads were synthesised through self-assembly and subsequent agglomeration of nanoparticles within an aqueous phase of a water-in-oil emulsion template. Photocatalytic degradation experiments were conducted through exposure of a methylene blue solution to UV light. The hybrid microbeads performed better than ZnO powder at the same initial dye and ZnO concentration because of higher adsorption and degradation. The initial concentration of dye solution and catalyst dosage have a significant impact on the degradation. Higher degradation is seen with lower initial dye concentration and higher catalyst dosage. The presence of magnetic nanoparticles within the beads allows for their full recovery and reuse for degradation experiments. Complete degradation of dye was achieved using the new ZnO/Fe3O4/SiO2 microbeads. [Display omitted] •A new photocatalyst in the form of ZnO/Fe3O4/SiO2 hybrid microbeads was fabricated for the photocatalytic degradation of methylene blue.•The hybrid microbeads performed better than ZnO powder at the same conditions due to higher adsorption and degradation.•Higher degradation is observed with decreasing initial dye concentration and increasing catalyst dosage.•Full recovery of the hybrid microbeads for further degradation experiments was achieved due to the presence of magnetic nanoparticles within the beads.