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engineering. Helbling¡¯s areas of study include
water quality as it relates to human and eco-
system health. ¡°My role at that initial stage,
last January or February, was a consultant,¡±
said Helbling, a co-author of the paper. ¡°They
said, ¡®We have this polymer that can do this;
what are the water quality issues to which
this could be applied?¡¯¡±
Helbling noted that his group challenged the
polymer in a way that Dichtel¡¯s group hadn¡¯t,
to see if it would adsorb various pollutant
mixtures at lower concentrations relevant for
real-world water purification.
¡°[Our contribution was] proving that even un-
der environmentally relevant conditions, the
phenomena that they were observing were
repeatable. And they were,¡± Helbling said.
Recyclability is another advantage of the
cyclodextrin polymer, Dichtel said. Whereas
activated carbon filters must undergo intense
heat-treating for regeneration, cyclodextrin filters could be washed at room
temperature with methanol or ethanol. And a drop-off in performance follow-
ing regeneration wasn¡¯t observed, Dichtel said.
Dichtel, whose MacArthur Foundation ¡°Genius Award¡± will total $625,000
over five years, said part of that award will go to further research into cyclo-
dextrin water purification, ultimately setting the stage for a product that can
be manufactured on large scales. ¡°Traditionally, that gap between the labo-
ratory discovery and getting something out in the world where it can help
people is difficult to bridge,¡± he said. ¡°So to have support that is totally unre-
stricted, that can be used pragmatically in that space, is really valuable.¡±
Dichtel is excited about the potential his group¡¯s results show in terms of the
water-purification industry. ¡°There are a lot of things going for it,¡± he said.
¡°There are still some unknowns, but everything looks pretty promising.¡±
Other co-authors of the paper, ¡°Instant Removal of Organic Micropollutants
From Water by a Porous beta-Cyclodextrin Polymer,¡± are postdoctoral schol-
ars Alaaeddin Alsbaiee and Brian Smith and graduate students Leilei Xiao in
chemistry and chemical biology and Yuhan Ling in civil and environmental
engineering.
The research made use of Cornell¡¯s Center for Materials Research User Facili-
ties, which are supported by the NSF. Dichtel¡¯s group has filed a provisional
patent application related to the cyclodextrin polymers reported in the Na-
ture article.
(By Tom Fleischman, Cornell Chronicle, www.news.cornell.edu)
Instant Removal of Organic Micropollutants From Water
Polymer breakthrough could revolutionize water purification
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A team of Cornell researchers has used cyclo-
dextrin, a derivative of corn starch, to develop a
technique that could revolutionize the water-puri-
fication industry. Cyclodextrin is the same mate-
rial employed by Febreze air fresheners to trap
invisible air pollutants in the home and remove
unwanted odors.
The team is led by Will Dichtel, associate pro-
fessor of chemistry and chemical biology and a
2015 MacArthur Foundation Fellowship winner.
His group invented a porous form of cyclodextrin
that has displayed uptake of pollutants through
adsorption at rates vastly superior to traditional
activated carbon, 200 times greater in some
cases.
Activated carbons have the advantage of larger
surface area than previous polymers made from
cyclodextrin, ¡°more sites for pollutants to stick
to,¡± Dichtel said, but they don¡¯t bind pollutants as
strongly as cyclodextrin.
2016 FEB/MAR #7-1
¡°What we did is make the first high-surface-area material made of cyclo-
dextrin,¡± explained Dichtel, ¡°combining some of the advantages of the ac-
tivated carbon with the inherent advantages of the cyclodextrin. When you
combine the best features of those two materials, you get a material that¡¯s
even better than either class.
¡°These materials will remove pollutants in seconds, as the water flows by,¡±
he said, ¡°so there¡¯s a potential for really low-energy, flow-through water
purification, which is a big deal.¡± What¡¯s more, the cyclodextrin-containing
polymer features easier, cheaper regeneration, so it can be reused many
times with no observed loss in performance.
The results of approximately 18 months of work are published online in
Nature on Dec. 21. Support for the work came from the National Science
Foundation through the Center for Sustainable Polymers, which brings
together a diverse team of researchers from Cornell, the University of Min-
nesota and the University of California, Berkeley, to discover high-perfor-
mance materials from sustainable, non-petroleum-based sources.
Following the discovery of the cyclodextrin polymer, additional support
to scale up and build prototype filtration systems has been provided by
Cornell¡¯s Atkinson Center for a Sustainable Future. Research began shortly
after the NSF grant was awarded. It wasn¡¯t long before Dichtel¡¯s team iden-
tified the cyclodextrin polymer as showing promise in water purification.
After spending a few more months analyzing the material, Dichtel reached
out to Damian Helbling, assistant professor of civil and environmental
A porous material made from cup-shaped cyclodextrins,
which rapidly bind pollutants and remove them from
contaminated water. Image: Dichtel Group