Gold as a possible detergent to clean up polluted groundwater

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Washington, Oct 24 (UNI) A chemical engineer in the United States is in the process of developing a detergent based on gold to clean up highly polluted groundwater.

''I admit it does sound crazy,'' said Michael Wong of his idea to use gold to clean up toxic waste.

Wong plans to combine gold with palladium-- an even more precious metal-- to treat polluted groundwater beneath waste dumps and contaminated factories and military sites.

''It not only works faster [than current methods], but a hundred times faster and I bet it will be cheaper too,''Wong said, according to an article in the Smithsonian magazine.

Wong's trick creates nanoparticles of gold. In his realm, the work product is measured not in carats but in atoms. A thimbleful of coffee-colored solution contains 100 trillion gold spheres-- each only 15 atoms wide, or about the width of a virus. Upon every golden nanosphere, Wong and his team dust a dash of palladium atoms.

The 35-year-old California tech and MIT graduate said he had not given toxic waste much thought until three years ago when one of his colleagues at Rice University (where he is a recently tenured professor of chemical engineering) came to him to say he had something interesting to work on.

The problem concerned the suspected carcinogen trichloroethene, or TCE, ''one of the most ubiquitous pollutants out there,'' said Wong, and ''a really nasty molecule.'' The clear, sweet-smelling solvent has been used for decades to degrease metal parts in factories and government facilities. ''It's everywhere,'' Wong adds. ''We used TCE in our own labs.'' NASA assembly plants are contaminated with it, as are some of the most advanced research laboratories in the nation.

The magazine quoted the Environmental Protection Agency as saying that 60 per cent of Superfund cleanup sites harbor TCE; the Department of Defence says 1,400 of its facilities do. Estimated cleanup costs run to 5 billion dollars just for the Defence sites.

TCE lingers like a bad houseguest, especially if handled carelessly.

It accumulates in soil and can persist for years in groundwater.

In a report last year, the National Research Council found that TCE was a potential cause of kidney cancer; it's also associated with liver problems, autoimmune disease and impaired neurological function.

Currently, the most common method of removing TCE from groundwater is to ''pump and treat,'' Wong said-- to pump the water out of the ground and run it through a filter made of activated carbon. The carbon grains soak up TCE like a sponge, but the process leaves behind TCE-laden filters that have to be stored or burned. ''So you haven't really gotten rid of anything,'' Wong said. ''You've just moved it from one place to another.'' This is where Wong comes in. He began thinking about using nanoparticles as a catalyst to react with the TCE and break it down into what he calls ''happy byproducts.'' Then followed a series of scientific experiments and after six months his team reached a eureka moment when it sculpted a palladium-covered core of gold atoms.

Wong said, ''We didn't believe it at first, because the gold-palladium nanoparticles were just so much more efficient, like a hundred times more efficient. You see, gold itself doesn't do anything to TCE.'' But something very interesting happens at the interface where gold, palladium and TCE meet.

He and his team are now working with engineers to build a real-sized reactor to field-test the nanoparticles at a polluted site. They hope to be scrubbing TCE in about a year, and then they'll see whether they have the cost-efficient cleaner they seek.

''It's very nice research,'' says Galen Stucky, a chemistry professor at the University of California at Santa Barbara, where Wong did his postdoctoral studies. ''Mike is a very creative guy with good insights, and what he is doing is going to have a major impact on the much bigger issue of water and water purification over the next ten years.'' UNI

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