Ultrasmooth Silica Nanofilm-Coated Membranes with Enhanced Antifouling and Separation Performance for Oil-Water Emulsions

Despite the efficiency of silica nanocoated membranes in separating oil-water emulsions, the high roughness of the membrane surface readily induces organic fouling due to the physical interlocking of foulants. We developed ultrasmooth (<1 nm r.m.s.) silica nanocoated glass fiber (GF) membranes using a novel vapor-based deposition method. The silica nanocoatings featured superhydrophilicity, high conformality, complete coverage, and tunable thickness. The silica nanocoated membranes demonstrated improvement in both oil rejection rate and permeate flux in emulsion separations. In addition, the membranes achieved versatile antifouling performance against oil, humic acid, and bovine serum albumin, with over 50% decrease in the total fouling ratio and 20-40% increase in the flux recovery ratio. The nanocoated membrane also demonstrated excellent stability against the organic solvent, strong acid, oxidant, boiling, and sonication. The silica nanocoatings stabilized the compact configuration of membrane fibers and thus contributed to high oil rejection rates.