This latter application could be instrumental in tracking environmental perchlorate, finding its source and resolving resulting liability issues, said ORNL scientist Baohua Gu, who headed development of the treatment system.

Perchlorate, or ClO4-, disrupts the thyroid gland that regulates metabolism in adults and physical development in children and is increasingly being found in soil and water. It is used to make solid rocket propellant and explosives but also occurs naturally, as in nitrate soils from Chile used to make fertilizers, making the source sometimes difficult to trace.

Conventional treatments use tiny resin beads to trap the perchlorate, but the spent resin becomes contaminated, and disposal is costly or impractical.

The ORNL system removes and breaks down perchlorate into harmless chloride and water and recharges the resin so it can be reused many times. The process costs up to 80 percent less than conventional methods and is one of R&D Magazine's top 100 inventions for 2004.

But Gu and ORNL colleagues Jusuke Horita and Gilbert Brown along with others from Louisiana State University, University of Illinois, and USGS have found another benefit: the process of removing perchlorate also purifies it, allowing the scientists to isolate trace quantities and examine the compound more closely than ever before.

Using isotopic analysis, they compared naturally-occurring perchlorate from Chile's Atacama Desert to synthetic or manufactured samples and found the natural type had a much higher value of the oxygen-17 isotope (an oxygen atom with 8 protons and 9 neutrons in the nucleus) but a lower chlorine-37 value (a chlorine atom with 17 protons and 20 neutrons in th
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Contact: Mike Bradley
bradleymk@ornl.gov
865-576-9553
DOE/Oak Ridge National Laboratory
20-Oct-2004