Sustainable green synthesis of ZnFe₂O₄@ZnO nanocomposite using Oleaster tree bark methanolic extract for photocatalytic degradation of aqueous humic acid in the presence of UVc irradiation

One of the most important humic substances in water is humic acid. These substances enter water sources through soils, sediments of aquatic animals, plants and sewage. Therefore, removing them from water sources is very important. In this study, the photocatalytic removal of humic acid was investigated using zinc ferrite nanoparticles loaded with zinc oxide (ZnFe₂O₄@ZnO). This research was conducted in an experimental-interventional way in a batch reactor on a laboratory scale. A novel and facile method was applied for catalyst synthesis in different conditions, and it was structurally and morphologically characterized by XRD, FT-IR, SEM, DLS and EDS mapping techniques. The effects of pH (3–11), nanoparticle dose (0.005–0.1 g/L), and humic acid concentration (2–15 mg/L) were examined up to 120 min of time. The results showed that the efficiency of humic acid degradation by ZnFe₂O₄@ZnO reached 95% in optimal conditions. Also, it was found that this nanocomposite has an acceptable reusability and recovery after being tested in five stages.