The story twists and turns a bit and some of the details are a little indistinct but it seems there’s new technology, PGClear, has been developed for cleaning up water and soil. From the Apr. 16, 2013 news item on Nanowerk,
Researchers from Rice University [Texas], DuPont Central Research and Development and Stanford University [California] have announced a full-scale field test of an innovative process that gently but quickly destroys some of the world’s most pervasive and problematic pollutants. The technology, called PGClear, originated from basic scientific research at Rice during a 10-year, federally funded initiative to use nanotechnology to clean the environment.
PGClear uses a combination of palladium and gold metal to break down hazardous compounds like vinyl chloride, trichloroethene (TCE) and chloroform into nontoxic byproducts.
“Chlorinated compounds were widely used as solvents for many decades, and they are common groundwater contaminants the world over,” said Rice’s Michael Wong, professor of chemical and biomolecular engineering and the lead researcher on the PGClear project. “These compounds are also extremely difficult to treat inexpensively with conventional technology. My lab began its work to solve this problem more than a decade ago.”
The Apr. 15, 2013 Rice University news release, which originated the news item, provides more detail about Wong’s work and how it came to be applied to remediation of chlorine-based contaminants (Note: Links have been removed),
Wong began working on the catalytic remediation technology shortly after arriving at Rice in 2001, the same year Rice won a grant from the National Science Foundation for the Center for Biological and Environmental Nanotechnology (CBEN). CBEN, a 10-year, $25 million effort, was the world’s first academic research center dedicated to studying the interaction of nanomaterials with living organisms and ecosystems. CBEN was one of the first six U.S. academic research centers funded by the National Nanotechnology Initiative.
“Prior research had shown that palladium was an effective catalyst for breaking down TCE, but palladium is expensive, so it was thought to be impractical,” Wong said. “At CBEN, we used nanotechnology to design particles in which every atom of palladium was used to catalyze the reaction. We also found that adding a tiny bit of gold enhanced the reaction.”
DuPont contacted Wong about the award-winning research in 2007 and proposed developing a scalable process to use the palladium-gold catalysts to treat other chlorinated pollutants like chloroform and vinyl chloride. With additional support from the World Gold Council in London, researchers from Rice and DuPont worked to refine the catalyst and the process. They also worked with the South African mineral research organization MINTEK, which produced the catalytic pellets for the first PGClear unit. Gold and palladium make up only about 1 percent of material in each of the purple-black pellets.
Rice has supplied a video of the researchers discussing their work with palladium-gold pellets,
Here’s the plan for the unit that will be used by Dupont (from the Rice University news release),
The first large-scale PGClear unit, which is designed to treat groundwater contaminated with chloroform, is scheduled for installation at a DuPont site in Louisville, Ky., in June [2013?]. The 6-by-8-foot unit contains valves and pipes that will carry groundwater to a series of tubes that each contain thousands of pellets of palladium-gold (PG) catalyst. The pellets, which are about the size of a grain of rice, spur a chemical reaction that breaks down chloroform into nontoxic methane and chloride salt. [emphasis mine]
“The palladium-gold catalyst has so far performed well for remediating groundwater samples collected at DuPont,” said Brad Nave, director of the DuPont Remediation Project. “While the project is not yet full-scale, our next step will subject the technology to the rigors of real-world field conditions. Rice, Stanford and DuPont have been working on the details of the field pilot for several years, and we’re looking forward to a successful test.”
While it’s good to note that the pollutants are broken down into nontoxic materials, it would have been interesting to find out what happens to the pellets over time (presumably they become less effective and need to be replaced with new pellets while the old ones are disposed of) and to find out how the groundwater is being captured for purification.
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