Mussel-inspired modification of PTFE membranes in a miscible THF-Tris buffer mixture for oil-in-water emulsions separation

Traditional polymer membranes suffer from low flux and oil fouling when utilized for separating oil/wateremulsion. Herein, a novel and simple method is exploited to design a novel polymer composite membrane with superhydrophilic and underwater superoleophobic property for oil in water emulsion separation by depositing polydopamine (PDA) on hydrophobic polytetrafluoroethylene(PTFE) membrane surface in tetrahydrofuran (THF)-Tris buffer mixture. In comparison with the traditional PDA coating on hydrophobic membrane in a Tris buffer solution, a PDA layer with mass of hydrophilic carboxyl groups and nano-microspheres hierarchical structure is formed on hydrophobic PTFE membrane by PDA coating in a miscible THF-Tris buffer mixed solution, and endows PTFE membranes with excellent superhydrophilic and underwater superoleophobic property. Therefore, the as-prepared membranes can be applied in varieties of oil-in-water emulsions separation with ultrahigh permeate flux (above 2250 L/m(2) h) under ultralow operating pressure (only 0.04 MPa) and excellent oil rejection. Finally, thanks to the low oil adhesion of the PDA layer, the resulting membranes display outstanding antifouling performance and reusability for oil water separation. On the whole, a novel rational methodology is provided to tailor PDA coatings with superhydrophilic and underwater superoleophobic property on hydrophobic membrane surface in tetrahydrofuran-Tris buffer mixture.