Ruthenium nanoparticles convert captured perchlorate into harmless chloride in water treatment waste Sadie Harley Scientific Editor Robert Egan Senior Editor For decades, water utilities have relied on giant tanks filled with ion-exchange resin beads to remove perchlorate, a harmful industrial pollutant, from drinking water. The system works by attracting negatively charged perchlorate ions to positively charged resin beads, allowing purified water to flow out of the tanks. But the process leaves behind a difficult problem: resin beads loaded with perchlorate that must be regenerated or disposed of as hazardous waste.

Now, researchers at UC Riverside have developed a catalyst made from tiny ruthenium nanoparticles that effectively breaks down perchlorate at high concentrations. The breakthrough study, published in the journal ACS Central Science, could make it possible to destroy perchlorate after it has been captured on ion-exchange resin. This could potentially reduce the hazardous waste generated during drinking water treatment and allow resin beads to be reused, said Jinyong Liu, UCR associate professor of chemical and environmental engineering, who oversaw the research led by UCR postdoctoral research scientist Jinyu Gao.

The advance comes as the U.S. Environmental Protection Agency moves toward establishing the first national drinking water standard for perchlorate, as California did nearly two decades ago. Perchlorate is a chemical used in rocket propellants, explosives, fireworks and other energetic materials.

It also occurs naturally in some environments. The compound has contaminated groundwater below military installations, defense manufacturing sites and other industrial locations throughout the United States. Health risks and tighter rules If ingested, perchlorate interferes with the thyroid gland's ability to absorb iodine, disrupting the production of hormones that regulate growth, metabolism and brain development.

Infants, young children and pregnant women are considered especially vulnerable. California has regulated perchlorate in drinking water for years and set a maximum contaminant level, or MCL, at no more than 6 parts per billion. Meanwhile, the EPA recently resumed efforts to establish a national drinking water standard, a move expected to increase demand for treatment technologies.

Liu said current treatment systems remove perchlorate effectively but do not destroy it. A catalyst built for neutral water Previous catalysts developed by Liu's laboratory could destroy perchlorate in either acidic or alkaline conditions. The new catalyst is the first the group has developed that works rapidly at a neutral pH at room temperature, the condition found in most drinking water treatment systems.

"This gives us a complete toolbox," Liu said. "We now have catalyst systems that work under acidic, alkaline and neutral conditions, allowing us to address a much wider range of real-world water treatment applications." The catalyst uses ruthenium nanoparticles enhanced with an organic nitrogen-containing compound known as cis-DACH. Together, they rapidly convert perchlorate into harmless chloride, the same ion found naturally in table salt, at room temperature and under normal atmospheric pressure.