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

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.