Biomimetic Silicification on Membrane Surface for Highly Efficient Treatments of Both Oil-in-Water Emulsion and Protein Wastewater

The worldwide water crisis and water pollution have put forward great challenges to the current membrane technology. Although poly(vinylidene fluoride) (PVDF) porous membranes can find diverse applications for water treatments, the inherent hydrophilicity must be tuned for an energy-/time-saving process. Herein, the surface wettability of PVDF membranes transforming from highly hydrophobicity to highly hydrophilicity was realized via one-step reaction of plant-derived phenol gallic acid and γ-aminopropyltriethoxysilane in aqueous solutions. The surface hydrophilicization can be achieved on porous PVDF membranes by virtue of integration of a mussel-inspired coating and in situ silicification via a "pyrogallol-amino covalent bridge" toward excellent antifouling performance and highly efficient infiltration ability for oily emulsion and protein wastewater treatment. The water flux of a surface-manipulated microfiltration membrane can reach ca. 9246 L m^-2 h^-1 (54-fold increment compared to that of pristine membrane), oil rejection >99.5% in a three-cycle emulsion separation; the modified ultrafiltration membrane demonstrated benign performance in bovine serum albumin protein interception (rejection as high as ca. 96.6% with water flux of ca. 278.2 L m^-2 h^-1) and antifouling potential (increase of ca. 70.8%). Our in situ biomimetic silicification under "green" conditions exhibits the great potential of the developed strategy in fabrication of similar multifunctional membranes toward environmental remediation.