Palladium is a very promising catalyst for a process of purifying groundwater contaminated by certain toxic substances that have previously been difficult to remove. The contaminents in question are termed halogenated volatile organic compounds (VOCs). VOCs are some of the most pervasive groundwater pollutants in the United States. These tend to be hydrocarbons that are used as solvents, degreasers, and used in the production of paints and adhesives. The United States Geological Survey indicated that in a 2002 study of 1500 drinking water wells, 44% contained at least one VOC.
Trichloroethylene (TCE) and tetrachloroethylene (PCE) are common groundwater contaminants with adverse affects on human health. They are widely used for dry cleaning and degreasing purposes. After leakage from storage or disposal sites, they can leach into aquifers and then become long-lasting groundwater contaminants.
Numerous studies are now underway to pioneer techniques to use palladium as a catalyst to promote the chemical conversion of the contaminants into benign end products in the presence of added hydrogen gas. The reaction essentially replaces the chlorine atoms in the contaminant with hydrogen.
Advantages over existing treatment methods are many.
- Existing technologies do not destroy the contaminates outright, but rather entrap them in another medium where disposal is still an issue.
- The palladium catalytic action is extremely fast; allowing the water to be treated with in-well reactors and eliminating the need to pump to the surface for treatment.
- The technology can be applied where conventional treatment is not currently even feasible, such as deep aquifers with high contaminant concentrations.
Ongoing studies can be found as follows:
Environmental Security Technology Certification Program
A list of current palladium research projects most of which are involved with groundwater treatment.
Western Region Hazardous Substance Research Center (WRHSRC)
One of five university-based hazardous substance research centers in the United States, this page details several studies underway. The Centers are funded by grants from the US EPA Office of Research and Development and Office of Solid Waste and Emergency Response