A Purdue University (West Lafayette, Ind.) researcher has created a new type of membrane that separates oil from water. Jeffrey Youngblood, an assistant professor of materials engineering at Purdue, has created technology that enables a membrane to allow water but not oil to pass, according to a Purdue news release.
With a higher flow rate than conventional filters that separate oil from water, the new membrane filter results in 98% separation, according to Youngblood. Researchers have tested the materials with solutions containing oil suspended in water, similar to concentrations existing in oil spills and other environmental cleanup circumstances.
To create these membranes, researchers covalently attach perfluorinated end-capped polyethylene glycol (PEG) surfactants to fritted glass membranes, the release says. Fritted glass is finely porous glass through which gas or liquid may pass.
In the 2007 report “Self-cleaning and anti-fog surfaces via stimuli-responsive polymer brushes,” Youngblood found that surfaces with PEG layers were stimuli-responsive. External stimuli led to changes in the surfaces’ inherent properties, allowing the surfaces to act as chemical gates.
“It is possible to control the selectivity of a membrane by taking advantage of differences in polymer-solute interactions,” according to the article “Amphiphile grafted membranes for the separation of oil-in-water dispersions,” published in 2009 in the Journal of Colloid and Interface Science.
The study found that oil suspended in water coalesced at the membrane surface with a small contact area on the membrane, compared to water. The water spread out along the membrane surface, filtering through. Only small amounts of oil were found in permeate from the treated membrane filter. Untreated filters, however, were found to allow between 90% and 98% of the oil to pass through, the article says.
Another unique characteristic of the membrane is that those tested were in the microfiltration pore range of 10 to 174 µm, which is larger than would be expected and increases the speed of filtration. Typical organic separation filters are in the nanofiltration pore range, the article says.
Youngblood’s membrane filter relies on chemical selectivity to optimize the amount of water that can pass through and avoid the common problem of pore clogging from particulates, the article says.
The study resulted in the desired goal: Create a filtration system capable of separating oil from water without a marked decrease in permeability. This technology, licensed through the Purdue Research Foundation’s Office of Technology Commercialization, could be used to help with environmental cleanups, water purification, and industrial filtration, the news release says. Youngblood also is working to develop a coating using the technology that could prevent windshields from fogging up or accumulating oily deposits, the release says.
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