Influence of the magnetite synthesis pathway on the photo-Fenton degradation of sulfamethoxazole

Abstract Three magnetites were synthesized using different coprecipitation routes, designated S1, S2 and S3. The aim was to investigate the effect of catalyst surface properties on the efficiency of the photo-Fenton process and compared with a commercial magnetite. The synthesis started with Fe(II) and Fe(III) in the case of S1, with Fe(III) and potassium iodide as the reducing agent for S2, and with Fe(II), citrate and nitrate for S3. Characterization by X-ray diffraction (XRD), zeta potential (ZP), scanning electron microscopy (SEM), nitrogen adsorption (BET), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spctroscopy (XPS) confirmed the formation of magnetite in all three materials. However, the materials exhibited differences in nucleation behavior due to the iron ratios, resulting in variations in particle size and specific surface area. The catalytic efficiency of the materials in the photo-Fenton process at different initial pH values (4.5, 5.5 and 6.5) was evaluated through the degradation of sulfamethoxazole (SMZ), an antibiotic frequently found in wastewater from sewage treatment plants which poses a risk to human health. The highest SMZ degradation was achieved with S1 at pH 4.5, reaching 94% demonstrating that this material effectively acts as a catalyst in the photo-Fenton reaction to remove the SMZ. The specific surface area (153 m 2 g −1 ) and pore volume (0.24 cm 3 g −1 ) of the catalyst S1 influenced positively the hydroxyl radical (HO · ) generation and, consequently the degradation rates of SMZ. Overall, the study demonstrated that magnetite S1, with its higher surface area and pore volume, is the most efficient catalyst for mitigating SMZ pollution under acidic conditions. Graphical abstract