Antifouling modification of PVDF membranes via incorporating positive-charge tuned quaternized chitosan magnetic particles

Membrane separation technology often suffers from fouling during operation and undergoes a trade-off effect between permeability and selectivity. We report a new strategy for fabricating antifouling poly(vinylidene fluoride) (PVDF) ultrafiltration membrane by incorporating hydrophilic, positive-charge tuned quaternized chitosan magnetic particles (QCMP). Fe3O4-chitosan particles were synthesized by co-precipitation and cross-linked by glutaraldehyde, and further quaternization modification was applied to obtain a series of QCMP with different charge densities. Then, the QCMP were incorporated into the matrix of PVDF to prepare hybrid membrane via the non-solvent-induced phase separation method. The effect of incorporated QCMP on the membrane morphology and properties was determined using scanning electron microscopy, water contact angle, surface free energy, membrane pore size and porosity. The incorporation of QCMP into the PVDF membrane effectively increased the surface hydrophilicity. Results of bovine serum albumin (BSA) solution filtration showed a higher flux recovery ratio (FRR) and a lower total fouling ratio(Rt) of the QCMP/PVDF hybrid membranes than those of the PVDF pristine membrane, indicating the addition of QCMP was helpful to enhance antifouing performance for BSA via improving hydrophilicity and neutralizing the surfaces of negatively charged PVDF membranes. Furthermore, the permeability flux of BSA was increased by 53 % and the rejection rate was also increased by 26 %, indicating the hybrid membranes have the potential to break the permeability-selectivity trade-off. Therefore, this study provided a green, simple and effective method for the rational design and construction membranes with enhanced the permeability and selectivity as well as antifouling performance.