Enhanced photocatalytic degradation of methylene blue from aqueous solution using green synthesized ZnO nanoparticles

Green synthesis has always been the preferred choice for nanoparticles because it uses biological extract from plant sources that are nonhazardous to the environment. Specifically, the physicochemical and optical properties of ZnO nanoparticles (ZnO NPs) make them economically feasible for various industrial applications. In the present study, ZnO NPs were synthesized by using Gomphrena serrata leaf extract (GS-ZnO NPs). Structural characterization of GS-ZnO NPs was performed by XRD and FTIR. The thermal nature of the GS-ZnO NPs was analyzed by DSC and TGA. The agar disc diffusion technique was used to assay the antimicrobial properties of nanoparticles against pathogenic bacterial strains. The efficiency of photocatalytic degradation was assessed by employing methylene blue (MB) as the test dye, with exposure to sunlight. The observed sizes of the metallic nanoparticles were in the range of 20–30 nm. XRD analyses revealed that the GS-ZnO NPs were hexagonal wurtzite structures. SEM analysis exhibited the spherical morphology of the GS-ZnO NPs. Thermal gravimetric analysis showed various phases of percent weight loss of GS-ZnO NPs within the temperature range of 50–460 °C. A photocatalytic efficiency of 90.5% was achieved after 180 min of sunlight irradiation. G. serrata leaf extract could be used as an efficient reductant and capping material in the synthesis of zinc oxide nanoparticles. These findings on the thermal and antimicrobial properties of GS-ZnO NPs may validate their efficacy in pharmaceutical applications. The photocatalytic dye degradation activity of the nanoparticles was explored to determine their significance in wastewater treatment.