Synthesis of Zinc Oxide Nanocatalyst and Its Application in Photodegradation of Rhodamine B

Abstract

We synthesized zinc oxide nanoparticles (ZnO-NPs) by the co-precipitation method for the catalytic degradation of Rhodamine B. The obtained nanoparticle was characterized by a UV-visible spectrophotometer, FTIR (Fourier Transform Infra-Red), EDX (Energy Dispersive X-ray), and XRD crystallography. The ZnO-NPs have shown maximum absorbance intensity at 365 nm, and an optical band gap of 3.29 eV based on Tauc plot. The FTIR spectra reveal strong stretching of Zn-O at 779.11 cm^-1. The EDX spectra depicted 81.90 % zinc (Zn), and 17.99 % oxygen (O) as an elemental composition. The XRD spectra show hexagonal wurtzite geometry. Solving Scherrer’s equation, we obtained the average size of the particle 23.9 nm, and the crystallinity 75.43%. The solar light intensity 5.74±0.14 kWh/m²/day was used to degrade Rhodamine B completely within 140 minutes with ≈80% catalytic efficiency, and in the dark medium, the degradation is found prolonged up to 220 minutes with ≈15% efficiency. The degradation in heat and light is achieved in 110 minutes at 110 °C. The degradation of dye obeys pseudo-first-order kinetics and the rate constant is obtained at 0.01274 min^-1 in light. The finding reveals that photocatalytic degradation under controlled temperature is superior to the degradation achieved in light and dark. The mineralization of Rhodamine B demonstrates the potential application of ZnO-NPs as a photocatalyst.