Superoleophobic and Superhydrophilic Fabric Filters for Rapid Water-Oil Separation

In response to the massive oil leak in the Gulf of Mexico University of Pittsburgh investigators have developed a technique for separating oil from water via a cotton filter coated with a chemical that blocks oil while allowing water to pass through. The filter was successfully tested off the coast of Louisiana and shown to simultaneously clean water and recover the oil. A video of testing our filter with oil and water samples from the Gulf of Mexico spill is available on YouTube at http://www.youtube.com/watch?v=kfRKjiOXVWE The filter hinges on a chemical that is both hydrophilic and oleophobic meaning that it likes water but repels oil. On the surface of ordinary cotton treated with the chemical water easily spreads while oil forms beads. When used as a filter such cotton allows water to pass through but not oil. The filter can be produced by submerging the cotton in an aqueous solution containing the chemical then drying it in an oven or in open air. For the massive slick off the Gulf Coast we envision large trough-shaped filters that could be dragged through the water to capture surface oil. The oil could be recovered and stored and the filter reused. The cost for treating the fabric is very low estimated to be less than $0.1 per square foot fabric. Only very small amount of chemical is needed to treat the cotton. We estimate that 1 pound of the chemical is enough to treat more than 2000 square foot cotton or fabric. The chemical binds strongly to the cotton. We have submerged the treated cotton in water-oil mixture for more than a month without noticing significant change in either the oil-repellency of the cotton or the separation efficiency of the filter. The chemical can be prepared by one of the 3 methods. This method may also find use in many other applications where water needs to be separated from oil including separating gross amounts of oil from the wastewater effluents of oil refineries petrochemical plants chemical plants natural gas processing plants and other industrial sources and separating oil from the bilge water accumulated in ships as required by the international MARPOL Convention.