Green synthesis of ZnO nanoparticles with enhanced photocatalytic and antibacterial activity

Abstract

The study describes a concise and eco-friendly approach for synthesising nano ZnO (nZnO) particles using raw Garcinia Cambogia fruit pulp extract. The remarkable crystallinity, purity, and hexagonal wurtzite structure of nZnO are established by X-ray diffraction (XRD) analysis. The formation of almost spherical nZnO with an average diameter of 32.8 nm is revealed by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The Fourier Transform Infrared (FTIR) spectrum of nZnO outlines the synthesis mechanism. The recombinations of free excitons and oxygen vacancies are responsible for the peaks in the photoluminescence (PL) spectra. UV-Visible Diffuse reflectance spectroscopy (UV-Vis DRS) revealed that the optical bandgap of nZnO is 3.24 eV. nZnO exhibited excellent photocatalytic activity against the degradation of cationic and anionic dyes. The effects of process parameters on the extent of dye removal, such as photocatalyst quantity, solution pH, and time of irradiation, were investigated. The photocatalytic degradations of dyes were modelled by pseudo-first order kinetics, having a strong correlation coefficient (R2>0.95). Statistical assessments of dye degradation using Analysis of Variance (ANOVA) and Least Significant Difference (LSD) were conducted. Antibacterial studies show that nZnO has a substantial bactericidal effect against pathogenic bacteria. Consequently, the green synthesised nZnO might be utilised to eliminate dyes and bacteria from industrial effluent water in an environmentally benign and cost-effective way.