Photocatalytic Fenton-like degradation of Acid Green 25 by novel aluminum nanoferrites with persulfate: Optimization by response surface methodology

Magnetic nanomaterials are gaining increasing attention for their catalytic properties and ease of recovery, making them promising candidates for the degradation of various organic pollutants. In this study, AlFe₂O₄ nanoparticles were employed for the first time in photocatalytic wastewater treatment. The study focused on removing Acid Green 25 anthraquinone dye through persulfate activation under UV-Visible light. AlFe₂O₄ nanoparticles were synthesized via sol-gel auto-combustion method and characterized by various techniques (XRD, SEM, EDX, VSM, Raman and FTIR). Moreover, statistical analysis of the experimental data confirmed the strong performance of the RSM model in accurately representing the photocatalytic process. Under optimal conditions including persulfate and catalyst concentrations of 0.3 g/L and 0.83 g/L respectively, a solution pH of 3 and 45 minutes of contact time, a 96 % dye removal rate was achieved. The remaining persulfate concentration was 60 % and fully depleted within 90 minutes, indicating efficient activation by AlFe₂O₄ photocatalyst. The activation process effectively suppressed electron-hole recombination, enhancing the overall efficiency. Scavenger experiments further identified surface-bound radicals and photogenerated holes as the main reactive species. A degradation mechanism for AG25 dye via a photocatalytic Fenton-like process was proposed, highlighting dual synergistic catalysis in the dye degradation. Ecotoxicity assessments using Vibrio fischeri bioassay revealed a significant reduction in toxicity after treatment with AlFe₂O₄/PS/UV-Vis system. The stability of AlFe₂O₄ was demonstrated over five degradation cycles. The findings open new perspectives for the use of AlFe₂O₄ in advanced wastewater treatment technologies, positioning it as a promising material for the degradation of persistent pollutants.