Magneto-enhanced g-C3N4/Fe3O4 Nanostructures for Photocatalytic Degradation of Amoxicillin and Polystyrene Adsorption in Water

Abstract

The increasing occurrence of microplastics and antibiotics in aquatic environments has become a global concern. Therefore, there is a growing need to development the efficient and cost-effective treatment technologies. This study provides a novel technique that uses synergetic effect of heterojunction and an external magnetic field to enhance both photocatalytic degradation of AMX antibiotic and adsorption of PS microplastics. The Fe₃O₄/g-C₃N₄ magnetic nanostructures (NSs) were synthesized via thermal polymerization followed by the co-precipitation method. The crystal structure, morphology, chemical composition, optical and electrochemical properties of the materials were characterized using X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and Ultraviolet-visible (UV-DRS), and electrochemical characterization, which confirmed the successful formation of the g-C₃N₄/Fe₃O₄ heterojunction. The prepared Catalystes were tested for the photodegradation of AMX under visible light irradiation and adsorption of PS. Compared to Pristine Fe₃O₄, and g-C₃N₄ the 0.5 T external magnetic field enhanced g-C₃N₄/Fe₃O₄ MNSs showed greatly improved photocatalytic performances 94.7% at optimum conditions, and the synergetic effect also show boosted adsorption capacity 464.625 mg/g against PSMPS adsorption. The enhancement could be related to the formed n–n heterojunction, magnetic field promoted charge separation, spin polarization, and mass transfer, which can suppress the recombination of charge carriers and extend the photoresponsive range. The PS adsorption process followed a pseudo first order kinetics and fitted well with the Langmuir isotherm model. The AMX photodegradation also followed pseudo-first-order kinetics, with a rate constant of 0.0220 min–1. After exposing g-C₃N₄/Fe₃O₄ to 0.5T magnetic field in 150W UV light, the rate constant increased to 0.02368 min-1. These findings highlight the potential of magneto-enhanced Fe₃O₄/g-C₃N₄ NSs as multifunctional catalysts for the effective removal of antibiotic and microplastic pollutants from water systems