Novel Fabrication of Photoactive CuO/HY Zeolite as an Efficient Catalyst for Photodecolorization of Malachite Green

Abstract

Copper oxide loaded on HY zeolite (CuO/HY) catalyst was prepared via a facile electrochemical method, and its photoactivity was evaluated by the decolorization of malachite green (MG) under fluorescent light irradiation. The physicochemical properties of catalysts were characterized by X-ray diffraction (XRD), nitrogen (N2) adsorption–desorption, 27Al and 29Si magic-angle-spinning nuclear magnetic (MAS NMR), transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). The results showed that CuO nanoparticles are well-distributed on HY support. Besides, the isomorphous substitution of Al3+ with Cu2+ was occurred to form Si–O–Cu bond, as confirmed by the 27Al and 29Si MAS NMR, FTIR and XPS analysis. The catalyst activity towards on decolorization of MG was ranked in the following order: 3 wt% CuO/HY (99%) > 5 wt% CuO/HY (86%) > 1 wt% CuO/HY (80%) > HY (41%) > CuO (17%). The highest decolorization by 3 wt% CuO/HY is due to the well distribution of CuO nanoparticles on the HY surface of as well as the Cu incorporated into HY frameworks. In terms of turnover frequency, the 1 wt% CuO/HY showed a higher value (7.95 × 10−4 min−1) compared to the 3 wt% CuO/HY (3.13 × 10−4 min−1) and 5 wt% CuO/HY (1.64 × 10−4 min−1). The decreased of chemical oxygen demand demonstrated that the relationship between decolorization and degradability exists. A kinetic study indicated that the photocatalytic process follows a pseudo-first-order kinetics represented by the Langmuir–Hinshelwood model with the rate determining step as a surface reaction.