Silica sand-supported nano zinc oxide-graphene oxide composite induced rapid photocatalytic decolorization of azo dyes under sunlight and improved antimicrobial activity

Abstract

Here, silica sand-supported heterojunction composite of nano zinc oxide (nZnO) and graphene oxide nanosheet (nZnO-GO@SS) was prepared, and its potential as an efficient photocatalyst for the degradation of methylene blue (MB) and Rhodamine-B (Rh-B) under sunlight was demonstrated. Transmission electron microscopy confirmed the uniform distribution of spherically shaped nZnO of average size of approximately 8 nm over graphene oxide nanosheet (GO) in the composites. Photodegradation yields of 95.3% and 97.5% for 100 ppm of MB and Rh-B dye within 150 and 220 min, respectively, were achieved under sunlight by the prepared nanocatalyst (nZnO-GO), while sand microparticle-supported nanocatalyst (nZnO-GO@SS) demonstrated faster degradation of MB and Rh-B, i.e., within 120 and 160 min, respectively. Furthermore, when the recyclability of the photocatalyst was studied, the nZnO-GO exhibited more than 80% degradation efficiency after five cycles for both the dyes and nZnO-GO@SS demonstrated 10% higher (~90%) removal capability after five cycles of reuse. Furthermore, the antibacterial assay showed complete inactivation of Escherichia coli and Staphylococcus aureus bacterial strain by nZnO-GO@SS. Hence, our proposed strategy for the removal of toxic dyes from the aquatic environment under sunlight proved that sand microparticle-supported nanocatalyst (nZnO-GO@SS) might be a superior, cost-effective, and suitable photocatalytic system for industrial applications toward toxic dye removal and decontamination from industrial wastewater.

Keywords: Graphene oxide; Nano zinc oxide; Nanocomposite; Photodegradation; Silica sand microparticles.