Efficacy evaluation of the antifouling magnetite–PES composite membrane through QCM-D and magnetophoretic filtration performances

This study presents the surface interactions and macromolecular properties of magnetic responsive polyethersulfone (PES) membranes in relation to their potent antifouling behavior. Polyelectrolytes, polyanion poly(sodium-4-styrene-sulfonate) (PSS) and/or polycation poly(diallyldimethylammonium chloride) (PDDA), were alternately adsorbed on the surface of a PES microfiltration membrane using the polyelectrolyte multilayer modification method. Subsequently, the magnetic responsive Fe₃O₄ functional layer was end-capped to the polyelectrolytes-assembled-PES membrane. By using a quartz crystal microbalance with dissipation (QCM-D), the viscoelastic properties (ΔD) and adsorption kinetics (Δf) of the adsorbed adlayers were investigated. The QCM-D results demonstrated an exponential growth of Fe₃O₄nanoparticles on the polyelectrolytes-assembled-PES polymer. The changes in the dissipation factor (ΔD) show greater motional freedom of the deposited multilayers (PSS, PDDA and Fe₃O₄) on the surface of the PES, where the surface morphology for the PES–Fe₃O₄ membrane was elucidated using FESEM/EDS. In this study, the synthesized magnetic responsive PES–Fe₃O₄ membrane demonstrated significantly improved permeability and selectivity. The membrane was shown to have a higher resistance to fouling based on the actuation motions of the magnetic nano-colloid under an oscillating external magnetic field. Subsequent exposure to a twisting effect promoted the detachment of humic acid from the membrane.