Novel Methodology for the Highly Efficient Separation of Oil and Water

J.M. Mabry, A. Tuteja, A.K. Kota, G. Kwon, W. Choi
Air Force Research Laboratory, US

Keywords: superoleophobic, superhydrophilic, polyhedral oligomeric silsesquioxane

Summary:

New energy-efficient solutions for the separation of oil and water are desired. Not only does the production and transport of petroleum products engender environmental risk, but military applications could benefit from more efficient separation techniques. Traditional membrane-based technologies for oil-water separation are energy-intensive and further limited by membrane fouling or the inability of a single membrane to separate all types of oil-water mixtures. The ideal membrane, which would effectively separate all types of oil-water mixtures, is expected to be hydrophilic and oleophobic. Such membranes would allow the higher density water to pass through, while preventing the flow of the lower density oil. However, most membranes that prevent the permeation of oils also prevent the permeation of water. We have prepared the first-ever reconfigurable membranes that, counter-intuitively, are both superhydrophilic and superoleophobic. These membranes were produced through the systematic design of membrane porosity and interfacial tension. These fouling-resistant membranes are, for the first time, able to separate all types of oil-water mixtures with greater than 99.9% efficiency. Further, we have produced the first-ever, gravity-assisted apparatus for the continuous separation of free oil-water mixtures and surfactant-stabilized oil-water emulsions.