New filtering technology has environmental and industrial applications

Washington, Nov 19 : Material engineers have developed a new filtering technology, in the form of a membrane that separates oil from water and, if perfected, might be used for environmental cleanup, water purification and industrial applications.

The new technology, developed by Purdue University researchers, would last longer than conventional filters for separating oil from water and works by attracting water while beading oil, traits that are usually mutually exclusive.

Researchers attached the material to a glass filter commonly used in laboratory research.

"We take mixtures of oil dispersed in water and run them through these filters, and we are getting 98 percent separation," said Jeffrey Youngblood, an assistant professor of materials engineering at Purdue University.

"This is pretty good because if you don't modify the glass filters with our material, essentially all the oil goes through. If you modify it with our material, then almost none of the oil goes through," he added.

The findings demonstrate how an oily substance called hexadecane beads up on the membrane while water passes through.

The membrane consists of a layer of material called polyethylene glycol, and each molecule is tipped with a Teflon-like "functional group" made with fluorine.

Water molecules are attracted to the polyethylene glycol, yet pass through the Teflon-like layer, which acts as a barrier to the oil molecules.

The researchers have tested the material with solutions containing oil suspended in water, similar to concentrations existing in oil spills and other environmental cleanup circumstances.

"To clean up an oil spill, for example, you could run contaminated water through a bunch of these filters to remove the oil," Youngblood said.

Such filters also might be used in other cleanup applications, such as removing oil from a ship's bilge water or cleaning wastewater contaminated with oil.

The technology might also be used in a water-purification technology called reverse osmosis, which now requires a "pre-filter" to remove oil.

The new technology would not need to be replaced as frequently because oil does not stick to the filtration material. Instead, the oil droplets could be skimmed off through a commonly used industry technique called cross-flow filtration.

A key advantage of the new approach over some conventional methods is that it separates oil from water without using "nanoporous" filters.

The new material contains pores between 10 and 174 microns, or millionths of a meter. Because the pores are relatively large, oil-contaminated water would not have to be pumped through.

According to Youngblood, thought the pores are large, the new material can efficiently separate oil from water.

ANI