HOUSTON -- (Nov. 25, 2013) -- Chemical engineers at Rice University have found a new catalyst that can rapidly break down nitrites, a common and harmful contaminant in drinking water that often results from overuse of agricultural fertilizers.
Nitrites and their more abundant cousins, nitrates, are inorganic compounds that are often found in both groundwater and surface water. The compounds are a health hazard, and the Environmental Protection Agency places strict limits on the amount of nitrates and nitrites in drinking water. While it's possible to remove nitrates and nitrites from water with filters and resins, the process can be prohibitively expensive.
"This is a big problem, particularly for agricultural communities, and there aren't really any good options for dealing with it," said Michael Wong, professor of chemical and biomolecular engineering at Rice and the lead researcher on the new study. "Our group has studied engineered gold and palladium nanocatalysts for several years. We've tested these against chlorinated solvents for almost a decade, and in looking for other potential uses for these we stumbled onto some studies about palladium catalysts being used to treat nitrates and nitrites; so we decided to do a comparison."
Catalysts are the matchmakers of the molecular world: They cause other compounds to react with one another, often by bringing them into close proximity, but the catalysts are not consumed by the reaction.
In a new paper in the journal Nanoscale, Wong's team showed that engineered nanoparticles of gold and palladium were several times more efficient at breaking down nitrites than any previously studied catalysts. The particles, which were invented at Wong's Catalysis and Nanomaterials Laboratory, consist of a solid gold core that's partially covered with palladium.
Over the past decade, Wong's team has found these gold-palladium composites have faster reaction times for breakin
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