A novel PVDF/PFSA-g-GO ultrafiltration membrane with enhanced permeation and antifouling performances

In this work, PFSA-g-GO nanocomposites were firstly prepared by perfluorosulfonic acid (PFSA) grafted on graphene oxide (GO) in various mass ratios through an esterification reaction. Then a series of PVDF/PFSA-g-GO ultrafiltration (UF) membranes were constructed by a non-solvent induced phase separation (NIPS) method using the obtained diverse PFSA-g-GO nanocomposites as additives in different dosages. PFSA-g-GO nanocomposites and PVDF/PFSA-g-GO membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), water contact angle, etc. The UF performance was examined using the separation of bovine serum albumin (BSA) and humic acid (HA) as a model system. The results showed that, compared with those of PVDF membrane, the permeability and the antifouling capacity of proposed PVDF/PFSA-g-GO membranes were enhanced. For example, the pure water flux of membrane M4 (PFSA:GO mass ratio of 2.5:1, fraction of PFSA-g-GO in dope solution of 0.5 wt%) was 1.5 times higher than that of PVDF membrane, but in the meantime, the rejection of BSA and HA was up to 93.9% and 79.6%, respectively. In general, the presence of PFSA-g-GO nanocomposites in dope solutions increased the hydrophilicity and decreased the roughness of membrane surfaces, and meanwhile increased the porosity and the pore size of membranes, which was dependent upon the content and the PFSA to GO mass ratio of nanocomposites in membranes.