Photocatalytic degradation of azithromycin and ceftriaxone using synthesized Ag/g-C3N4/Fe3O4 nanocomposites in aqueous solution

This study focuses on the synthesis of an Ag/g-C₃N₄/Fe₃O₄ nanocomposite and its application for the photocatalytic degradation of azithromycin and ceftriaxone in aqueous solutions. The g-C₃N₄ was prepared via a two-step calcination method, while the Ag/g-C3N₄/Fe₃O₄ nanocomposite was synthesized using a one-step hydrothermal approach. The physicochemical properties of the nanocomposite were thoroughly characterized using XRD, FTIR, FE-SEM, TEM, and VSM. Process optimization based on the Box-Behnken Design (BBD) identified optimal conditions at pH 5.2, a catalyst dose of 0.42 g/L, reaction time of 107 min, and an initial antibiotic concentration of 10 mg/L. Under these conditions, the nanocomposite achieved degradation efficiencies of 83.3 ± 2.1% for azithromycin and 93.3 ± 1.8% for ceftriaxone. COD and TOC reductions were measured at 65.5% and 52%, respectively, although intermediate products decelerated mineralization. Catalyst reusability was demonstrated with a performance decline of less than 13% after six cycles. Additionally, light intensity and the presence of scavengers and inorganic ions were evaluated, revealing that hydroxyl radicals (OH^•) play a dominant role in the degradation process. The nanocomposite also exhibited enhanced visible light absorption due to its tailored bandgap and electron-hole separation efficiency. The findings confirm that the Ag/g-C₃N₄/Fe₃O₄ nanocomposite is a robust and efficient photocatalyst for antibiotic degradation, offering a sustainable and effective solution for wastewater treatment applications.