Preparation, structural and functional characterization of modified porous PVDF membranes by γ-irradiation

This work describes the synthesis of charged poly(vinylidene fluoride) (PVDF) membranes. Cationic membranes were prepared by graft modification using radiation-induced polymerization. Glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EDMA) were used as monomers and after graft polymerization the former was sulfonized with sodium sulfite. Membrane characterizations were carried out by FTIR-ATR, SEM-EDS, ionic exchange capacity, hydraulic permeability and liquid–liquid displacement. FTIR-ATR and SEM-EDS analysis revealed that increasing grafting degree increased the amount of the sulfonic group in the membranes. Sulfonated membranes showed smaller pore sizes and higher pore density than the original PVDF membrane. Oil/water ultrafiltration tests with the charged PVDF membranes showed interesting permselectivity performance; high oil retention values (R > 98%), low chemical oxygen demand in the permeate solution (COD < 59 mg L−1). In addition, low fouling (<16.6%) and negligible irreversible fouling of the charged membranes was observed during the ultrafiltration tests.

► PVDF membranes can be modified with glycidyl methacrylate (GMA) by gamma-rays induce graft polymerization method.
► The grafted membrane can be sulfonated by an epoxy opening reaction.
► Modified membranes have a higher number of pores and with smaller size than the unmodified one.
► Grafted membranes do not show irreversible fouling.
► Grafted membrane permeates can be directly discharged into the rivers due to the low values of COD measured.