Page 27 - Plastics News June 2017

FEATURES

Polymer that removes highly toxic pollutant PFOA from water

An inexpensive and renewable material that rapidly removes PFOA from water. The novel treatment
effectively eliminates the micropollutant to below 10 parts per trillion, far below Environmental
Protection Agency and all state health advisory limits.

highly toxic water pollutant, known as perfluorooctanoic sized swimming pools. Negative
A acid (PFOA), last year caused a number of U.S. health effects have been noted
communities to close their drinking water supplies. at lower concentrations than the
Because of its historical use in Teflon production and EPA advisory limit in extensive
other industrial processes as well as its environmental studies of PFOA exposure. At
persistence, PFOA contamination is a pervasive problem least four states -- Minnesota,
worldwide. A Northwestern University-led research team New Hampshire, New Jersey and
now reports an inexpensive and renewable material that Vermont -- have implemented
rapidly removes PFOA from water. The novel treatment limits of at least half the EPA limit.
effectively eliminates the micropollutant to below 10 parts The polymer can be regenerated and reused multiple
per trillion, far below Environmental Protection Agency times. Only a modest amount of the material is needed
and all state health advisory limits. to capture and remove PFOA to less than 10 parts per
trillion. “Our findings demonstrate the selectivity of this
“Our material fully extracts the pollutant out of water,”
said William Dichtel, an expert in organic and polymer type of polymer can be tailored to target pollutants of
chemistry who led the study. “The polymer contains sites interest, in this case PFOA,” Dichtel said. “The material
that bind PFOA strongly, which strips this pollutant out of has more than 10 times higher affinity for PFOA than
water even when present at extremely low concentrations. activated carbon, a conventional treatment method with
The binding sites are joined together by linkers that several known deficiencies.”
further enhance the affinity for PFOA.” Dichtel, The networked polymer is made from joining smaller
the Robert L. Letsinger Professor of Chemistry at molecules with tiny pores, and selectivity is programmed
Northwestern’s Weinberg College of Arts and Sciences, into the material through a crosslinked monomer.
believes the material can support water purification The main component, beta-cyclodextrin, is a naturally
efforts to rid drinking water of PFOA and perhaps other occurring bio-renewable sugar molecule derived from
per- and polyfluorinated alkyl substances (PFASs), such as cornstarch.In many communities -- often those near
perfluorooctanesulfonic acid (PFOS).
industrial sites, military installations and airports -- PFOA
The PFOA material and Dichtel’s polymer technology are levels exceed the EPA’s advisory limit.
being developed for commercial use by CycloPure, Inc., In 2016, Hoosick Falls, New York, and Bennington,
a company co-founded by Dichtel. The study, co-authored Vermont, declared states of emergency because of
by Dichtel, Damian Helbling, assistant professor of civil PFOA-contaminated drinking water. As testing of drinking
and environmental engineering at Cornell University, and water supplies for PFOA and PFOS becomes broadly
members of their research groups at Northwestern and mandated, as recently legislated in the state of New
Cornell, recently was published by the Journal of the York, the detection of trace amounts of PFOA, PFOS and
American Chemical Society.
other PFASs is expected to be widespread in the years
The EPA’s 2016 advisory limit for the combined concentration ahead. The National Science Foundation through the
of PFOA and PFOS in drinking water is 70 parts per trillion, Center for Sustainable Polymers (grant CHE-1413862)
which is equal to one teaspoon of PFOA in 14 Olympic- supported the research.

27 June 2017 | Plastics News