Resin to remove groundwater contaminant

Perchlorate anions form when perchlorate salts, such as ammonium perchlorate and lithium perchlorate which are used in solid rocket fuel and oxygen candle in spacecraft respectively, dissolve in water. They occur naturally, but are also manufactured, and are known to contaminate groundwater used for drinking, possibly disrupting the activity of the hormone-secreting thyroid gland.

A team of researchers led by Mamadou S. Diallo from the Korea Advanced Institute of Science and Technology (KAIST) in Daejeon and the California Institute of Technology, California, has developed a new type of resin bead capable of removing perchlorate from water more effectively than any available method. The researchers built the resin beads from large organic molecules of polyethyleneimine (PEI) with a highly branched structure.

To test the PEI resin beads, the team, which includes Jean Frechet, a chemist at the King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia, prepared a perchlorate-contaminated solution mimicking the contaminated groundwater of Redlands, California. The test solution also contained other anions, including sulfate, nitrate, chloride, and carbonate, each usually found in contaminating groundwater.

The new PEI resin beads selectively extracted trace amounts of perchlorate anions from the test solution in the presence of competing ions, which could often decrease the efficiency of previous filters. The ion exchange capacity of the PEI resin beads was 2.3 times higher than those of commercial styrene divinylbenzene (STY-DVB) resin beads.

"The successful scale-up and commercialization of these new resins could have a broad range of applications including water treatment, mining, biofuel processing and biopharmaceutical separations," says Diallo.

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