Dual Approach for Effective Photodegradation and Mineralization of Carbamazepine Using a Ternary ZnFe ₂ O ₄ /(P,S)- g -C ₃ N ₄ /Two-Dimensional TiO ₂ Composite

This study proposes a dual strategy for the efficient degradation of carbamazepine through combining a photocatalytic reaction with persulfate (PS) activation. To improve the physicochemical properties, two magnetic materials with ratios of 50:50 and 70:30 of ZnFe₂O₄ to (P,S)-g-C₃N₄ were combined with TiO₂ nanosheets prepared through a fluorine ion-free lyophilization method. The presence of (P,S)-g-C₃N₄ in a heterojunction with 2D TiO₂ mitigated rapid charge carrier recombination, while the magnetic properties improved the photocatalyst recyclability and supported PS activation. Surface properties, phase identification, and structural and chemical composition of materials were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Optical properties of photocatalysts were determined by UV-vis diffuse reflectance spectroscopy (DR/UV-vis) and photoluminescence spectroscopy (PL). The effect of PS addition in the photocatalytic system was correlated with the observed generation of hydroxyl radicals. The highest concentration of hydroxyl radicals was observed during the first 15 min of the process. The mechanism investigation confirmed that superoxide and hydroxyl radicals were the primary contributors in the case of photocatalysis. In contrast, for PS-assisted photocatalysis, the major reactive species, depending on the pH, were hydroxyl radicals and sulfate radicals. Six common transformation intermediates were identified, and a degradation pathway was proposed. Overall, this investigation emphasizes the potential and effectiveness of the PS-assisted photodegradation process using a cost-effective ternary ZnFe₂O₄/(P,S)-g-C₃N₄/2D TiO₂ composite for improved degradation of carbamazepine, a persistent organic pollutant frequently present in water.