Magnetic field-augmented coagulation bath during phase inversion for preparation of ZnFe₂O₄/SiO₂/PES nanofiltration membrane: A novel method for flux enhancement and fouling resistance

Nanocomposite polyethersulfone (PES) nanofiltration membranes were prepared using self-synthesized magnetic ZnFe₂O₄/SiO₂ nanofiller by the phase inversion method. The main aim of this paper was to investigate effect of magnetic field in coagulation step on characteristics of the prepared membranes. The performance of the fabricated mixed matrix membranes was studied by measuring pure water flux, salt retention and fouling parameters. As a result, coagulation bath under magnetic field significantly enhanced pure water flux of the membranes from about 12 kg/m² h (without magnetic field) to 38 kg/m² h in the presence of 1 wt.% ZnFe₂O₄/SiO₂ nanoparticles. This described by amount of magnetic nanofillers on the membrane morphology coagulated under the magnetic field of 0.1 T, which changed the skin-layer structure. EDX mapping showed that the magnetic nanoparticles migrated to the membrane surface, when the membrane coagulated under magnetic field. The water contact angle measurement showed the excellent hydrophilicity of 0.5 wt.% ZnFe₂O₄/SiO₂ embedded membranes under magnetic field, which resulted in the superior antifouling properties against powder milk solution. The salt retention sequence for 0.5 wt.% nanoparticle under magnetic field was in sequence of R (Na₂SO₄) > R (MgSO₄) > R (NaCl).