Constructing Robust and Superhydrophilic PVDF Composite Membranes via a Stepwise Modification Strategy for Efficient Emulsion Separation

Membrane separation is a crucial technology for oily wastewater treatment owing to its high efficiency, energy efficiency, and environmental friendliness. Polyvinylidene fluoride (PVDF) membranes are widely used but suffer from severe fouling during oil-in-water emulsion separation. Herein, a green stepwise surface modification strategy is developed: a phenol-amine hybrid network is constructed via rapid codeposition of pyrogallol (PG) and 3-aminopropyltriethoxysilane (APTES), followed by TiO 2 nanoparticle immobilization via liquid phase deposition (LPD). The modified membrane retains its porous structure, forms a uniform nanoscale functional layer, and exhibits superhydrophilicity, underwater superoleophobicity, and ultralow oil adhesion. It achieves >99% separation efficiency for four emulsions with a maximum permeability of 4138 L·m –2 ·h –1 ·bar –1, and shows excellent chemical stability and easy permeability recovery. This work provides a new approach for developing efficient oil–water separation membranes.