Membrane-based separation technologies are the cornerstone of remediating unconventional water sources including brackish and industrial or municipal wastewater, as they are relatively energy-efficient and versatile. However, membrane fouling by dissolved and suspended substances in the feed stream remains a primary challenge. In this work, we directly address this challenge by introducing a superhydrophilic and oleophobic membrane that can be utilized to separate and desalinate an oil and saline water mixture. It can also catalytically degrade the organic substances with visible-light irradiation without its wettability and integrity being affected. We fabricated this membrane by coating a commercial filter with an ultraviolet (UV) light-curable adhesive. Then, we sprayed it with a mixture of photocatalytic nitrogen-doped titania (N-TiO2) and perfluoro silane-grafted silica (F-SiO2) nanoparticles. The membrane was placed under UV light which resulted in a chemically heterogeneous surface with intercalating high and low surface energy regions (i.e., N-TiO2 and F-SiO2, respectively) that were securely bound to the membrane. We also developed a mathematical model to describe the time-dependent evolution of the permeate flux within an oil fouling environment under visible light irradiation. Finally, we demonstrated that the membrane was able to remove trace amounts of contaminants dissolved in water more efficiently from the permeate with visible light irradiation compared to the membrane that was placed in the dark

Wettability and photocatalysis decoupled membranes for desalination and separation of oil-saline water mixture

ACS Fall 2021

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