Photocatalytic degradation and kinetic investigations of ZnO-SnO2 heterostructures for treatment of methyl violet using non-conventional approach

Abstract

Humans and wildlife alike are threatened by the ever-increasing levels of organic pollutants exist in the world's water bodies. Nanomaterials based on metal oxides have been considered strong alternatives for the elimination of organic pollutants. In the present study, ZnO-SnO2 nanocomposites were synthesized via non-conventional microwave and ultrasonic method using fruit extract of Carissa edulis as capping agent. The synthesized nanocomposites were studied using X-ray diffraction (XRD), Diffuse reflectance spectroscopy (UV–Vis-DRS), X-ray photoelectron spectroscopy (XPS), Fourier Infrared spectroscopy (FT-IR), Photoluminescence spectroscopy (PL), and Field emission scanning electron microscope (FE-SEM). Under UV light irradiation, photo-catalytic degradation of methyl violet (MV) was investigated by examining the influence of photocatalyst dosage, initial pollutant concentration, and pH of the reaction medium. The ideal conditions for MV degradation were at initial MV concentration of 10 mg/L, a 20 mg catalyst dose, and a pH of 7. The MV degradation of the synthesised ZnO-SnO2 nanocomposite was 91 % after 120 min. Scavenging experiments demonstrated that hydroxyl radicals (.OH) acts as a key role in the photo-degradation of MV. The reusability studies demonstrate that the synthesised ZnO-SnO2 has good stability for four cycles.