Tailoring the PVDF membrane surface with polyoxypropylene-polyoxyethylene brush via in-situ grafting for enhanced oil/water emulsion separation

Membrane technology has been widely applied in oil-water separation owing to low energy consumption and high separation efficiency, but membrane fouling is a fatal factor affecting membrane performance and service life. Inspired by polyether nonionic detergents, a liquid surfactant polymer with polyoxypropylenepolyoxyethylene (PPO-PEO) segments was tailored to the surface of polyvinylidene fluoride (PVDF) membrane via in-situ grafting to improve its antifouling and oil-water separation properties. Firstly, in order to activate the inert surface of the PVDF membrane, poly(styrene-co-maleic anhydride) (SMA) was blended with PVDF to prepare the MA@PVDF as membrane substrate. Then, PPO-PEO brushes were grafted onto the surface of the substrate by an alcoholysis reaction to fabricate the PPO-PEO@PVDF membrane. The chemical structure and the surface morphology of the PPO-PEO tailored PVDF membrane surface were characterized, and the separation performance for oil/water emulsion was explored. The results show that the optimized grafting amount of PPOPEO on the PVDF membrane is up to 476.2 +/- 3.0 mg center dot g(-1), and the pure water flux of the corresponding PPO PEO@PVDF membrane is 191.3+4.0 L center dot m(-2)center dot h(-1), which is more than 20 times higher than that of the control PVDF membrane (around 7 L center dot m(-2)center dot h(-1)). The water wetted PPO-PEO brushes on the surface of the PVDF membrane can hinder the adhesion of oily substances, and the separation efficiency of the PPO-PEO@PVDF membrane for kerosene/water emulsion reaches 91.7+0.6 %, which is much higher than that of the MA@PVDF membrane without PPO-PEO brushes. The PPO-PEO tailored PVDF membrane provides useful strategies for the surface modification of membranes with enhanced performances of antifouling and oil-water separation.