the water passes through but the oil is repelled and blocked A UNIVERSITY of Pittsburgh chemical engineer has developed a simple filter made from polymer-coated cotton fabric which effectively separates crude oil from water.

Di Gao, an assistant professor at Pittsburgh’s chemical and petroleum engineering department, successfully tested the filter off the coast of Louisiana. Gao soaked cotton cloth in a solution of the specialised polymer. The cloth was then oven-dried or left to dry naturally. The polymer is both hydrophilic and oleophobic, so when an oil-water emulsion passes through the filter, the water passes through but the oil is repelled and blocked.

The idea could be adapted for the current spill in the Gulf of Mexico by incorporating the coated cotton into large, trough-shaped filters which could be towed by ships to remove surface oil. Gao says the oil could be recovered and the filters reused.