Pitt professor wants BP to try his filter

Tested oil cleaning method off Louisiana coast

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Di Gao, an assistant engineering professor at the University of Pittsburgh, spent most of his Memorial Day weekend off the Louisiana coast, testing a technique he and his research team have developed for separating oil and water.

The technique, which involves capturing the oil in a cotton filter treated with a chemical polymer, worked. The water, now clean, passed through the filter that he had fashioned out of a big T-shirt, while the oil was repelled by the polymer and preserved.

He has suggested that the companies and government agencies trying to contain the massive oil spill in the Gulf of Mexico caused by the April 20 explosion of BP's Deepwater Horizon drilling platform give his filter a try.

On a large scale, Dr. Gao envisions the booms on skimming boats being replaced with trough-like cotton filters of 20 to 30 yards or longer. The oil would stay in the trough while the water passed through and then be recovered into a tanker. The filters could be reused.

Because plain T-shirt-style cotton is inexpensive, "we estimate the cost at 10 cents per square foot, so the cost is very low," he said. "We can make a lot of these filters."

The cotton would be dipped in the chemical polymers, then air-dried before the material is shaped into filters, he explained.

Dr. Gao said if the consortium decides it wants to try his filters, the project "could be really fast. It depends on their willingness. We could coat the cotton really fast, and we have a lot of chemicals available."

So far, all Dr. Gao has heard back was a form letter acknowledgement, but he is not surprised.

"They originally got 7,000 [ideas] -- that's what I was told, and it's probably more than that by now," he said Monday. "That number was a week ago. They need to review each one."

The Pitt research group, which besides Dr. Gao comprises two graduate students and one undergraduate, was working on an oil-water separation technique before the drilling rig explosion.

For almost four years, the team worked on surfaces that repelled both water and oil. "Then starting early this year, we began looking for chemicals that repel oil but like water," Dr. Gao said.

The original motivation was to find a way to clean oily substances with water and without chemicals. "It was kind of like a chemical-free cleaning ... environmentally friendly," he said.

"One application is to do oil-water separation, and we did it before. We knew even before this oil spill in the Mexico Gulf. It was kind of obvious -- once you put it on a filter, it will allow water to pass through."

Other research groups had found chemicals that did just the opposite -- repel water but not oil.

Dr. Gao said it was harder to do what his team has done. "It's actually a very interesting phenomenon that people don't usually observe."

And it would have numerous uses around the world, he added.

"There are oil spills every year. It's just a matter of how much. The problem is worldwide, not just in America," he said. "Usually it's tankers. This time it's a rig."

It also would be useful in oil refinery plants, he suggested. "There are a lot of places [in a refinery] where you want to separate oil from water."

But Dr. Gao would like very much to help out with the current environmental crisis.

"If someone can employ it in the Mexico Gulf and help clean up the oil, it's really something," he said.

Pohla Smith: psmith@post-gazette.com or 412-263-1228. First Published June 8, 2010 4:00 AM


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