Hybrid PK-P/Fe3O4 Catalyst Derived from Pumpkin Peel (Bio-Waste) for Synozol Red KHL Dye Oxidation Under Photo-Fenton Reaction

This study introduces a novel photocatalyst derived from pumpkin peel bio-waste, calcined at 200 °C and incorporated with magnetite nanoparticles to form a hybrid PK-P/Fe3O4 catalyst. The material was characterized using X-ray diffraction (XRD), diffuse reflectance spectra (DRS), and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) mapping to confirm its structure and elemental distribution. The catalyst was applied for the photo-Fenton degradation of Synozol Red KHL dye under natural solution conditions (pH 5.7). Optimal parameters were achieved with a 20 mg/L catalyst and 200 mg/L H2O2, resulting in complete dye removal within 25 min of irradiation. The PK-P/Fe3O4 catalyst exhibited excellent reusability, retaining 72% removal efficiency after 10 successive cycles. Kinetic analysis confirmed a first-order model, while thermodynamic evaluation revealed a non-spontaneous, endothermic process with a low activation energy barrier, indicating energy-efficient dye degradation. These findings highlight the potential of bio-waste-derived PK-P/Fe3O4 as a sustainable, low-cost, and highly effective catalyst for treating dye-polluted wastewater under photo-Fenton conditions.