Superhydrophilic nanoporous membrane for highly efficient and stable separation of organic molecules

Fabricating nanoporous membranes with superhydrophilic properties to overcome fouling from organic foulants is a challenge in membrane separation processes for organic molecules. Recently, researchers demonstrated that membranes with distinct hydrogel features exhibit superhydrophilicity and outstanding antifouling capacity. However, hydrogel membranes have low mechanical strength, which can lead to pore deformation and potential membrane rupture during pressure-driven separation processes. Herein, we report a whole-membrane crosslinking strategy to fabricate a superhydrophilic and robust nanoporous membrane in which polyethyleneimine is blended and crosslinked in a carboxylated polyacrylonitrile hydrogel membrane in situ. Whole-membrane crosslinking improves membrane strength, with crosslinking occurring both in the membrane interior and on the membrane surface. Efficient molecular separation with a water flux of 220 L m⁻² h⁻¹ bar⁻¹, a Coomassie brilliant blue (CBB) rejection of ∼99.9%, and a CBB/Na₂SO₄ selectivity of 747 was achieved with this membrane. The membrane also showed excellent antifouling capacity, with a flux recovery of ∼100% during molecular separation with humic acid as a foulant. At transmembrane pressures up to 8 bar, the membrane exhibited stable molecular separation. Our work provides a new route for fabricating superhydrophilic nanoporous membranes for the separation of organic molecules in wastewater.