Thirdly, graft polymerization with PVP
was carried out by soaking the membranes in PVP (0.5 wt.%) aqueous
liquid for 5 min. Finally, the modified PVDF membranes,
denoted as PVDF70K–PVP and PVDF100K–PVP membrane, respectively,
were repeatedly washed with DI water to remove residual
PVP.