Fabrication, characterisation and magneto-responsive performance of manganese ferrite nanospheres for fast separation of oil slicks from water surfaces

The achievement of oil/water separation, characterised by easy operation, low cost and low energy consumption, significantly impacts environmental protection and economic loss reduction. However, industry practitioners still face a considerable challenge. In this study, we reported an efficient, recyclable and environmentally friendly material that facilitates the rapid separation of oil slicks from water surfaces. This material, known as magnetorheological (MR) fluid, demonstrates promising capabilities. The manganese ferrite (MnFe₂O₄) nanospheres were synthesised through a simple solvothermal method, employing oleic acid for hydrophobic modification. The resulting MnFe₂O₄ nanospheres exhibited a hierarchical morphology, rough surface, well-defined mesostructure, high saturation magnetisation and superparamagnetic characteristics. These unique properties make the MnFe₂O₄ nanospheres suitable for incorporation into MR fluid and effective oil removal. The MnFe₂O₄ nanospheres-based MR fluid demonstrated magnetic field-dependent rheological properties, excellent sedimentation stability, remarkable oil-removal efficiency and favourable recycling performance. Thus, the developed MnFe₂O₄ nanospheres-based MR fluid can serve as an effective tool for removing oil slicks from water surfaces.