Removal of Methyl Orange in Aqueous Solutions Using Hydrochloric Acid-Modified Kaolinite Supported Nanosized Zero-Valent Iron

This study presents an efficient application of the Fenton reaction for the degradation of methyl orange (MO), utilizing a composite of hydrochloric acid-modified kaolinite supported nanosized zero-valent iron (mk-nZVI). The successful loading of Fe⁰ onto the hydrochloric acid–modified kaolinite was confirmed through scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analyses. Key variables, such as solution pH, reaction temperature, mk-nZVI dose, initial MO solution concentration, and H₂O₂ concentration, were manipulated to examine the efficacy of the mk-nZVI/H₂O₂ system in the degradation of MO. The system demonstrated improved degradation performance with decreased pH and increased temperature. Under the following conditions: an initial pH of 5.6, a reaction temperature of 25 °C, an mk-nZVI dose of 2 g/L, an initial MO solution concentration of 100 mg/L, and an H₂O₂ concentration of 74.8 mmol/L, an MO degradation of 96.56% was achieved using the mk-nZVI/H₂O₂-based Fenton-like reaction. This performance was markedly superior to the traditional Fenton method in decolorizing MO solutions. UV–Vis spectroscopy demonstrated the mk-nZVI/H₂O₂-based Fenton-like reaction’s effectiveness in degrading MO’s azo structure. The degradation of MO was primarily attributed to the action of surface-bounded hydroxyl radicals. The findings indicate that the synthesized mk-nZVI composite holds promise for efficient treatment of MO in water, establishing it as a prospective composite material for wastewater remediation.