Magnetically recoverable Fe3O4-chitosan/PVA hydrogel for photo-Fenton degradation of diazinon

Fe 3 O 4 magnetic nanoparticles were fabricated in situ within chitosan/ polyvinyl alcohol (CS/PVA) as a semi-interpenetrating polymer network ( semi -IPN) composite hydrogel. CS was derived from shrimp shells. Various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunaeur-Emmett-Teller (BET) analysis, Transmission electron microscopy (TEM), Vibrating sample magnetometery (VSM), Fourier transform infrared spectroscopy (FTIR), and UV–vis diffuse reflectance spectroscopy (DRS) were used to characterize the composite hydrogel. The catalytic activity of the CS/PVA-Fe 3 O 4 hydrogel was evaluated for photo-Fenton degradation of diazinon. The results exhibited that the CS/PVA-Fe 3 O 4 hydrogel possesses noticeable degradation performance in the photo-Fenton process, with a percentage of removal up to 98.7% than the pure Fe 3 O 4 (61%) and homogeneous Fenton (73%) for diazinon under optimal reaction conditions (reaction time of 120 min, pH 9, oxidant amount of 1.5 mL, initial diazinon concentration of 10 mg L − 1 , temperature of 50 °C, and catalyst dosage of 1 g L − 1 ). The composite hydrogel demonstrated approprate reusability, as it could be recycled for ten runs without a noticeable loss in removal efficiency. Based on kinetic studies, the photodegradation of diazinon was adapted to a pseudo-first-order model, and apparent activation energy was acquired to be 71.31 kJ/mol. Besides, photodegradation mechanisms and pathways were investigated.