Embargoed until 2 P.M. EDT
NSF PR 01-26 - April 11, 2001
Media contact:
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Amber Jones
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(703) 292-8070
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aljones@nsf.gov
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Program contact:
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Thomas Chapman
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(703) 292-8371
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tchapman@nsf.gov
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Synthetic Clay Could Assist Radioactive Waste Cleanup
Researchers from Pennsylvania State University supported
by the National Science Foundation (NSF) have performed
an important step in the drive to remove environmentally
harmful materials from waste streams and drinking
water.
A team led by Sridhar Komarneni, professor of clay
mineralogy demonstrated that a synthetic clay known
as a swelling mica has the ability to separate ions
of radium, a radioactive metal, from water. The scientists
report their results in the April 12 issue of Nature.
The finding could have implications for radioactive
and hazardous waste disposal, particularly in the
cleanup of mill tailings left over from the processing
of uranium for the nation's nuclear industry. The
tailings contain radium and heavy metals that can
leach into groundwater and contaminate drinking water
supplies.
"This result represents significant progress in developing
new ion-separation materials," said Thomas Chapman,
manager of NSF's program for separations and purification
processes, which funded the research. "With more development,
the swelling micas should prove useful in both waste
remediation and metals recovery."
The swelling mica tested by Komarneni's team, known
as Na-4, is one of a group of clays not found in the
natural environment. Created specifically for water
treatment purposes, swelling micas expand as they
absorb metal ions and then, reaching their capacity,
collapse and seal the contaminants inside. The swelling
micas are being explored for potential use in separating
ions of heavy metals such as lead, zinc and copper
as well as other radioactive materials, including
strontium, from waste streams. Because they trap the
ions, the micas can permanently immobilize the pollutants.
They could prove useful for the recovery and recycling
of valuable metals as well.
Komarneni has used x-ray diffraction and nuclear magnetic
resonance spectroscopy to evaluate the chemical properties
of this new class of materials. One of his goals is
to determine whether they have a larger capacity for
metal uptake than currently available materials. In
this recent experiment, he succeeded in synthesizing
Na-4 into a fine powder more useful for practical
applications than the large crystals previously synthesized.
The research was performed at Penn State's Materials
Research Laboratory and Department of Agronomy.
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