Tailoring the current density to enhance photocatalytic activity of CuO/HY for decolorization of malachite green

Abstract

CuO supported on HY zeolite (CuO/HY) catalyst was prepared via a simple electrolysis method under different levels of current density, and its properties and photoactive performance were investigated. The physicochemical properties of the catalyst were examined using X-ray Diffraction (XRD), surface area analysis, Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV–Vis DRS), Fourier Transform Infrared (FTIR) spectroscopy, and pyridine adsorption FTIR. The analyses indicated that CuO/HY catalyst contains both CuO nanoparticles and incorporation of copper into the HY framework. In parallel with the formation of Cu0 in the electrolysis system, the Cu2+ ions also underwent isomorphous substitution subsequent to dealumination to form a Si–Cu–O bond, as confirmed by the FTIR result. The formation of the Si–Cu–O bond was found to decrease at elevated current density and this lowered the photocatalytic decolorization of malachite green (MG) by CuO/HY. The CuO/HY prepared at 10mAcm−2 was the optimum catalyst and produced complete and 50% decolorization of 10 and 15mgL−1 of MG, respectively. The results indicating the decrease in chemical oxygen demand (COD) and total organic carbon (TOC) demonstrated the degradability of MG molecules. The CuO/HY is also stable and showed no leaching effect even after six reaction cycles, with just small decreases in the decolorization percentage (<89%). The catalyst has the potential to be applied in textile wastewater treatment which is always in low concentration level. It is also believed that this study will be useful for synthesis of other catalysts that necessitate a degree of isomorphous substitution of metal ions in a zeolite network.