The investigations of photocatalytic degradation and defluorination of perfluorooctanoic acid using palm kernel shell activated carbon and Fe-Sn binary oxides nanocomposite under visible light irradiation

Perfluorooctanoic acid (PFOA) is a persistent pollutant in the environment that does not break down easily because its strong CF bonds strong. Current methods for degrading organic pollutants such as PFOA often have low mineralization efficiency, need a lot of energy, and cause pollution in other ways. In response to these challenges, this study presents an innovative palm kernel shell activated carbon-supported binary oxide, Fe₂O₃/SnO₂ (PKSAC-Fe₂O₃/SnO₂), as a heterojunction and multifunctional photocatalyst for the decomposition of PFOA under visible light. This research presents an innovative PKSAC-Fe₂O₃/SnO₂ nanocomposite that used the synergistic interaction among the large surface area and adsorption capacity of bio-derived activated carbon, the redox reactivity of Fe₂O₃, and the potent oxidative characteristics of SnO₂. The photocatalytic degradation performance of PKSAC-Fe₂O₃/SnO₂ nanocomposite was tested by irradiation of visible light on it. The optimum conditions were found to be pH 5, a catalyst dose of 5.0 mg, and an initial PFOA concentration of 20 ppm. After 6  of irradiation, the nanocomposite reached an impressive PFOA degradation efficiency of 92.40 % and a defluorination rate of 51.23 %, showing that the fluorinated compound had been mineralized significantly. Mechanistic investigations showed that the hydroxyl radical (•OH) and direct electron were the main species involved in the partial mineralization of PFOA with five shorter-chain intermediates identified. The catalyst's potential reusability coupled with its low-cost, biomass-derived support, present a sustainable solution for PFAS remediation. This work advanced the design of efficient, solar-driven catalysts for persisting pollutant degradation, bridging critical gaps in energy efficiency, cost-effectiveness, and environmental safety.