Superhydrophilic PVDF Membrane Modified by Norepinephrine/Acrylic Acid via Self-Assembly for Efficient Separation of an Oil-in-Water Emulsion

With the continuous production of kitchen wastewater, the treatment of oily wastewater has become a worldwide challenge. Here, we propose a novel superhydrophilic poly(vinylidene fluoride)-g-poly-(norepinephrine) (PVDF-g-PNE) membrane with superhigh water permeability and excellent oil rejection via simple self-assembly. The chemical composition of the modified membrane was successfully confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) techniques. It was confirmed that the PVDF-gPNE membrane had both superhydrophilicity and underwater superoleophobicity with a water contact angle (WCA) of 0 degrees and an underwater oil contact angle (UOCA) of 162.8 degrees. Moreover, the PVDF-g-PNE membrane had excellent wetting stability under the environment of acid, alkali, and salt. The PNE coating on the membrane surface showed complete repellency to edible oil and good antiprotein adhesion performance. The prepared membrane possessed an ultrahigh pure water permeability of 32 000 L.m(-2).h(-1).bar(-1). The highest permeability of the prepared membrane was 7348 L.m(-2).h(-1).bar(-1) with an oil rejection of 99.21% when used to treat a surfactant-stabilized edible oil-in-water emulsion. The proposed PVDF-g-PNE membrane was capable of efficiently treating oily wastewater.