Green construction of persistently superwettable protein-based membrane for high-efficiency oil/water emulsion separation

Surface hydrophilization is a critical strategy to enhance membranes oil-fouling resistance for the large-scale treatment of oily industrial water, but the current modification strategies suffer from non-persistent wettability, toxic reagents, multiple synthetic procedures and complicated equipment. Moreover, the chemical inertness of widely used hydrophobic membranes makes interfacial modification challenging. To address this issue, we reported a facile and scalable protein-based anti-fouling coating based on interfacial protein self-assembly combined with thiol-ene click chemistry. The super-hydrophilic polyethylene glycol methacrylate (PEGMA) macromolecules were grafted onto reduced thiol-containing bovine serum albumin (BSA) via click chemistry to form conjugates that self-assembled into amyloid-like coatings on polyvinylidene fluoride (PVDF) membranes via hydrophobic interactions. The abundant hydrophilic groups of PEGMA introduced to the membrane can construct a physical hydration layer barrier and steric repulsion that prevents the approach and the adhesion of oil. The method significantly enhanced the wettability and anti-oil-fouling resistance of the commercial PVDF membrane, which achieves a high-efficient permeance of 4679 L·m⁻²·h⁻¹·bar⁻¹ and a rejection of 99.7% for n-octane emulsion, representing a 1139.5% enhancement in flux and a 115.1% improvement in rejection relative to the pristine PVDF membrane. The present investigation provides a versatile and green interfacial engineering approach that simultaneously enhances permeability, selectivity, oil anti-fouling performance, and long-time stability.