Photocatalytic degradation of Malachite Green dye by modified ZnO nanomaterial

Abstract

In this article we report a chemical sol–gel approach to synthesize zinc oxide nanomaterials capped with ethylene diamine tetra acetic acid (EDTA), citric acid and oleic acid, and to study the effect of the surface modification on their photocatalytic activity and the kinetics for the degradation of Malachite Green (MG) dye. The structural, optical and chemical features were systematically characterized by X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared and UV–vis absorption spectroscopy. The objective of using the capping agents was to confine the size and control the growth and morphology of the nanomaterial. The smallest crystallite size was recorded as 29 nm for EDTA-capped rod-shaped ZnO. A comparison study of the effect of the three different capping surfactants on ZnO nanomaterial for photocatalytic degradation of MG dye under solar light showed that EDTA with higher denticity coordinated efficiently with the surface of ZnO nanocrystalline catalysts and hence demonstrated better decolouration of the dye under solar light. The dye degradation followed the psuedo-first-order kinetics. EDTA proved to be the best capping agent among all the three for ZnO nanomaterial.