Poly(vinyl pyrrolidone) modified poly(vinylidene fluoride) ultrafiltration membrane via a two-step surface grafting for radioactive wastewater treatment

Abstract Poly(vinylidene fluoride) (PVDF) ultrafiltration (UF) membranes were modified with poly(vinyl pyrrolidone) (PVP) through a two-step surface grafting method in order to enhance the antifouling properties. PVP of small molecular was used to modify the membrane pores and cross-linked PVP modified the membrane surface. The pore modification enhanced the membrane flux from 130.0 L·m -2 ·h -1 to 170.7 L·m -2 ·h -1 , and the surface modification increased the membrane hydrophilicity (i.e., the contact angle decreases from 93° to 83°). During the fouling tests with bovine serum albumin (BSA) solution and laboratory simulation low-level radioactive wastewater (LLRW), the modified membrane had a much slower flux reduction compared with the raw membrane. After water wash, the flux recovery rates of the BSA fouled membranes were 98% for the modified membrane and 46% for the raw membrane, respectively. Additionally, the modified membrane had the same rejection on nuclide and surfactant as the raw membrane. Based on these results, the two-step modified membrane is suitable to be used in LLRW treatment with advantages of less frequent membrane cleaning and longer membrane lifetime.