Catalytic Oxidation of Phenol Using Iron-Supported Illite: Optimization of Parameters for Efficient Wastewater Treatment

This study investigates the catalytic oxidation of phenol using an iron-supported purified natural illite clay catalyst, focusing on optimizing operational parameters and elucidating the degradation mechanism to achieve high efficiency and minimize environmental impact. The effects of pH (2–10), initial phenol concentration (20–100 mg/L), temperature (30–90°C), iron content (3–7%), catalyst dosage (0.5–1.5 g/L), and H₂O₂ concentration (4.75–12 mM) were systematically studied. Optimal conditions were determined at pH 3, a phenol concentration of 50 mg/L, 50°C, 5% iron content, a catalyst dosage of 1 g/L, and 8.7 mM H₂O₂, enhancing hydroxyl radical formation and reaction kinetics. Under these conditions, the catalyst achieved a 99% degradation rate for phenols and an 83% reduction in chemical oxygen demand (COD), with minimal iron leaching. The identification of intermediate by-products using HPLC enabled the construction of a detailed stepwise degradation mechanism, shedding light on the oxidative pathways and confirming the effectiveness of the process. The purified illite catalyst demonstrated excellent stability and reusability over multiple cycles, maintaining performance with minimal activity loss. Comprehensive material characterization (XRD, TGA, BET, SEM, FTIR, and laser granulometry) confirmed the structural and morphological integrity of the catalyst and provided insights into its active sites. This study underscores the potential of iron-impregnated purified natural clays as sustainable, cost-effective catalysts for treating phenolic pollutants in wastewater.