Oil and water mix and un-mix on demand

Oil and water can for the first time be mixed and separated on demand thanks to a new, reversible surfactant.

The liquid molecule could prove invaluable in mitigating the environmental damage caused by oil spills, such as the one currently spreading along the coasts of Lebanon and Syria.

Such a chemical could also simplify commercial oil extraction from currently inaccessible deposits, its designers say. And it would prove equally valuable in the food and cosmetics industries, simplifying processes and products which rely on the mixing or separation of oily and watery components.

The genius of the new surfactant lies in its reversibility. Unlike existing ones, it can be switched "on" or "off" repeatedly. The switches are very simple too: carbon dioxide and air.
Bubbling away

"Bubble carbon dioxide through a solution and the surfactant switches on, leading the oil-and-water mix to form an emulsion," explains Philip Jessop at Queen's University in Kingston, Ontario, Canada, who led the research team that developed the new surfactant.

"To switch it off again, you bubble air through it, and the oil and water separate again," he says.

Surfactants must have two ends – a water-repelling hydrophobic bit that binds to the oily substance; and a water-attracting hydrophilic bit, which has an ionic charge that binds to water.

Oil and Water Mix and Un-Mix on Demand

newscientisttech.com

Thu Aug 17

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