Oil Spill Help: New Coating Quickly Separates Oil From Water
by Michael Keller
Scientists at Durham University in the UK have developed a coating that repels oil and attracts water. When applied to stainless steel mesh like that found in screen doors, the material lets water pass through quickly while blocking oil.
The team behind the innovation, which rapidly separates water-oil mixtures with 98 percent efficiency, says it could be used to clean up oil spills and in similar applications.
"Because ot the frequency of offshore oil spillages and the emergence of fracking (where water-based fluids are used to fracture rocks for the release of oil and gas), the separation of oil and water is an important environmental challenge," they write in their paper published recently in the journal ACS Applied Materials & Interfaces.
There are problems with current approaches to separating oil and water. After oil spills, for instance, most of the prevailing recovery methods involve spreading substances like clays, straw or fibers to absorb oil. These materials can absorb water along with the oil, and they then need to be processed to free the oil.
Other techniques push the mixed fluid through membranes with pores big enough to let water pass while blocking larger molecules. These process the fluid slowly, can require lots of energy and lose effectiveness as they become clogged.
The Durham team says their “fast-switching oleophobic–hydrophilic polyelectrolyte–fluorosurfactant surfaces” could be used as the first step to remove most oil before another technology clears the rest. And because their coating is transparent, they say it can also be used as an effective antifogging, antifouling film on glass or other materials that need to be seen through.
(Demonstration of oil-water separation. a) Uncoated mesh lets oil and water through. b) stainless steel mesh dip-coated with the copolymer–fluorosurfactant complex coating. c) An inclined coated mesh allows water to pass into the first beaker while oil that was mixed in slides down into the second. Researchers also so success separating motor and olive oils from water. Courtesy American Chemical Society.)
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