Photocatalytic Removal of Organic Dye Using Green Synthesized Zinc Oxide Coupled Cadmium Tungstate Nanocomposite Under Natural Solar Light Irradiation

Abstract

In this work, zinc oxide coupled cadmium tungstate (ZnO-CT) was prepared as a nano-photocatalyst through a green synthesis route using lemon leaf extract and characterized based on diverse microscopic and spectroscopic techniques. To extend the practical application of the prepared nanocomposite (NC), its photocatalytic activity was investigated against Congo red (CR) dye under natural solar light irradiation. ZnO- CT nano-photocatalyst shows 93% photocatalytic degradation of the CR with quantum yield and figure of merit values of 1.7x10-8 molecules photon-1 and 3.7x10-4 L g-1 h-2 W-1 μ mol, respectively. The photocatalytic degradation kinetics for CR dye was studied using the pseudo-first-order, diffusional, and Singh models. The successful functioning and greater photocatalytic activity of ZnO-CT NC nano-photocatalyst might be associated due to the presence of electron-withdrawing functional groups like acids (COOH) and aldehydes (CHO) on its surface. The photocatalytic degradation of Congo Red was enhanced by the presence of functional groups on ZnO-CT NC surface as they were able to efficiently prolong the recombination of charge carriers.

Keywords: Green Synthesis, Water treatment, Adsorption, Photocatalysis, congo red