Synergistic Construction of Polyacrylamide Hydrogel-Modified Membranes via a Layer-by-Layer Modification Strategy for Efficient Emulsion Separation

Hydrogel was considered an optimal material for modified oil/water separation membranes due to its exceptional underwater superoleophobicity. However, the challenges of hydrogel modification include an uncontrollable coating degree and membrane pore clogging. This study introduced a novel approach to fabricating hydrogel-modified PVDF membranes by regulating the polymerization degree of polyacrylamide (PAm) through the synergistic effect of tannic acid (TA). PAm hydrogel-modified membranes with a controllable polymerization degree were constructed by using the layer-by-layer design. This approach enhanced the membrane’s wettability while maintaining pore integrity. The modified membrane achieved an average flux of 5250.9 L·m^–2·h^–1·bar^–1 during the cross-flow separation of oil-in-water emulsions containing surfactants, with an oil removal efficiency of 99.8%. Additionally, the membrane demonstrated excellent antifouling and recycling capabilities, making it highly effective in treating complex emulsions. This work provides novel insight into the development of highly fouling-resistant and high-performance hydrogel-modified oil–water separation membranes, which show great potential in the large-scale treatment of oily wastewater.