Synthesis and properties of sodium vinylbenzene sulfonate-grafted poly(vinylidene fluoride) cation exchange membranes for membrane capacitive deionization process

In this study, a poly(vinylidene fluoride)- graft -sodium 4-vinylbenzene sulfonate copolymer (PVDF- g -PSVBS) was prepared by grafting sodium 4-vinylbenzene sulfonate (SVBS) onto dehydrofluorinated poly(vinylidene fluoride) (PVDF). The PVDF- g -PSVBS cation exchange membranes were prepared using a casting method. The structure of the membranes was investigated with Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Morphology using scanning electron microscope with energy-dispersive X-ray analysis (SEM-EDS) demonstrated as increasing the degree of grafting, the sulfur element is uniformly distributed and increased. The effects annealing temperature on the properties of the PVDF- g -PSVBS membranes were investigated. To prepare the consistent and homogeneous membranes, it was suggested that the annealing temperature of PVDF- g -PSVBS membranes is below 60 °C. The salt removal efficiency for application to the membrane capacitive deionization (MCDI) process was conducted.