Effective solar-based iron oxide supported HY zeolite catalyst for the decolorization of organic and simulated dyes

Abstract

A HY zeolite supported by highly dispersed electrogenerated iron oxide nanoparticles (EGFe₂O₃/HY) was prepared by a facile electrochemical method and has been characterized using XRD, TEM, BET, UV-vis/DRS, and XPS. The formation of EGFe₂O₃ nanoparticles with a size of <30 nm, well distributed on the surface of HY, led to enhanced catalytic activity for the decolorization of organic dyes such as methylene blue (MB), congo red (CR), and methyl orange (MO) under sunlight irradiation. The MB dye shows the highest decolorization (99.9%) followed by CR (96.4%) and MO (91.3%). Kinetics study signifies that the reaction follows pseudo first-order kinetics, and the rate constants was determined using the Langmuir–Hinshelwood model which gave values of K_R = 0.48 mg L⁻¹ h⁻¹, K_LH = 3.83 L mg⁻¹ for MB; K_R = 0.39 mg L⁻¹ h⁻¹, K_LH = 1.78 L mg⁻¹ for CR; and K_R = 0.29 mg L⁻¹ h⁻¹, K_LH = 0.13 L mg⁻¹ for MO. No dissolution of EGFe₂O₃ ions was detected during the photoreaction. The catalyst was stable with a slight decrease of decolorization (<13%) after five cycling runs. Good performance of the decolorization of simulated dyes was observed with nearly complete mineralization as measured by COD and TOC removal.