Magnetically separable NiFe₂O₄ nanoparticles: synthesis and photocatalytic activity

Current research addresses the successful development of magnetic NiFe₂O₄ nanoparticles (NPs) by green method using cabbage (Brassica oleracea L.) leaf extract as a capping agent. Obtained NiFe₂O₄ NPs were calcined at 500, 600, and 700 °C for characterization and acted as photocatalyst. The NiFe₂O₄ NPs are crystalline in nature with FCC cubic spinel structure. The XPS analysis confirmed the oxidation states of Ni²⁺ and Fe³⁺, respectively. Prepared NiFe₂O₄ NPs are in a spherical shape with a particle size of 10–12 nm is confirmed by SEM. FT-IR spectrum exhibits major bands of phytocompounds and Fe–O. The band gap energy of NiFe₂O₄ is observed around 1.76 eV. Super-paramagnetic nature of NiFe₂O₄ is observed by VSM and the saturation magnetization is around 20 emu/g. Using NiFe₂O₄ NPs as a photocatalyst accomplished 94% photodegradation of Methyl Orange (MO) under UV–Vis. light (max-365 nm) within 135 min with 1.5 g/dm³ photocatalyst loading. NiFe₂O₄ NPs are easily separable by a bar magnet; hence the small nanoparticles can separate for reuse. Also, there is no significant change in photodegradation efficiency after time that indicates a photocatalyst is photostable and reusable.