New strategy of grafting hydroxyethyl acrylate (HEA) via γ ray radiation to modify polyvinylidene fluoride (PVDF) membrane: Thermodynamic mechanisms of the improved antifouling performance

Membrane fouling represents one of the greatest challenges for widespread applications of polyvinylidene fluoride (PVDF) membranes. This study proposed a new strategy regarding grafting hydroxyethyl acrylate (HEA) via γ ray radiation to improve the antifouling ability of PVDF membranes. The grafted membrane possessed improved antifouling ability for filtration of sodium alginate (SA) solution which was experimentally evidenced by the 92.03% flux recovery ratio (69.68% for the pristine membrane) and 11.54% irreversible fouling ratio (32.76% for the pristine membrane). When subjected to filtration of bovine serum protein (BSA) solution, the grafted membrane showed lower flux decline rate than the pristine membrane, and interestingly, higher BSA solution flux than pure water flux. Thermodynamic analyses indicated that the improved hydrophilicity and the reduced strength of thermodynamic interactions between the grafted membrane and foulants were mainly responsible for the improved antifouling performance. Meanwhile, thermodynamic swelling process affected by ionic strength induced higher BSA solution flux than pure water flux. The revealed thermodynamic mechanisms facilitated to optimize the grafting strategy. This study not only proposed a grafting strategy, but also provided interesting PVDF membranes whose flux can be adjusted by ionic strength, giving important implications for membrane fouling research.