Enhanced water permeance and antifouling performance of gravity-driven ultrafiltration membrane with in-situ formed rigid pore structure

Gravity-driven membrane (GDM) has emerged as a low-energy technique of water treatment. However, low water flux limits the application of GDM, due to membrane fouling and pore deformation. For the first time, gravity-driven Polyvinylidene Fluoride (PVDF) ultrafiltration membrane with rigid pore structure was fabricated by in-situ formed four-arms star polystyrene (FAS-PS) microspheres in an easy one-step phase separation process. The self-assembly of FAS-PS molecular chains caused PVDF chains to shrink, leading to the generation of more porous structure. The tightening effects of in-situ rigid FAS-PS microspheres enhanced the anti-deformation capability of membrane. As a result, water flux decline of PVDF@FAS-PS membrane was significantly inhibited during GDM filtration process. The stable water flux of PVDF@FAS-PS membrane was approximately 5 times than that of the control PVDF membrane. Furthermore, the anti-deformation character of PVDF@FAS-PS membrane was beneficial to reduce membrane fouling, which was demonstrated by the reduced amount of bovine serum albumin (BSA) clogged in rigid pore structure. These enhanced performances were attributed to the simultaneous reduction of plastic and elastic deformation of membrane pore structure in GDM process. This study provides a completely novel strategy to improve the water flux and anti-fouling ability of GDM.