A naturally inspired, reusable system that purifies water and builds
itself

Date:
July 27, 2021
Source:
Penn State
Summary:
In nature, the interaction of molecules at the boundary of different
liquids can give rise to new structures. These self-assembling
molecules make cell formation possible and are instrumental to the
development of all life on Earth. They can also be engineered to
perform specific functions -- and now, a team of researchers has
leveraged this opportunity to develop a material that could remove
persistent pollutants from water.



FULL STORY ==========================================================================
In nature, the interaction of molecules at the boundary of different
liquids can give rise to new structures. These self-assembling molecules
make cell formation possible and are instrumental to the development of
all life on Earth.


==========================================================================
They can also be engineered to perform specific functions -- and now, a
team of Penn State researchers has leveraged this opportunity to develop
a material that could remove persistent pollutants from water. The
researchers recently published their findings in Advanced Functional
Materials.

"We took inspiration from biological systems to see if we can get similar phenomena to emerge with non-biological molecules," said Scott Medina, assistant professor of biomedical engineering and corresponding author
on the paper.

For their experiment, the researchers opted to incorporate fluorine, an
element not commonly found in nature, into an amino acid and mix it with
a fluorinated oil to guide its molecular organization. The team added the fluorinated oil to water, where it formed a bead comprised of the fluorine droplet surrounded by an amino acid coating. When the researchers inverted
the vial to expose the bead to air, the bead's components rearranged to
form a film. Composed of a thin layer of fluorinated oil surrounded by
two layers of microscopic amino acid crystalline structures, this film
could rearrange itself into the bead when agitated -- and take other fluorinated molecules with it.

"Fluorines don't play well with others, so if you put them together there
are very strong interactions," Medina said. "Fluorinated contaminants
in water want to separate themselves from the water and find other fluorine-rich matter." This phenomenon, and the compound's capacity to
switch between a film state and the bead shape, sparked the researchers' interest in possible pollutant capture. Per- and polyfluoroalkyl
substances (PFAS) are artificial chemicals containing fluorine typically
used in manufacturing of water- or grease- repellent products. Their
molecular structure allows them to accumulate in environments and the
human body -- permanently.

"Nature hasn't evolved ways to break down fluorine-containing molecules efficiently, so these compounds stick around for a long time," Medina
said.

"They enter wastewater and soil, make their way into drinking water
and food, and we consume them -- and our bodies don't degrade them very
well, either." To test the new compound's potential for PFAS capture,
the researchers added contaminated water to a plastic container coated
with their fluorinated amino acid film. The film captured PFAS substances within two hours and was able to hold them for up to 24 hours. From this
stage, the film containing PFAS could be agitated to reform itself into a cohesive bead that could be easily collected from the now-purified water.

The researchers plan to further explore these pollutant extraction capabilities, investigating not only water purification but also the
potential to harvest compounds from air. With further research into
its applications, the fluorinated compound could become a multi-use
contaminant removal tool for use in a variety of settings.

"There's a lot of effort being placed into investigating the toxicology
of PFAS and how to regulate them," Medina said. "This material could be implemented to remove PFAS from drinking water -- and we think it could
have a lot of utility in other areas as well." Other paper contributors include Janna Sloand, a biomedical engineering doctoral candidate;
Enrique Gomez, professor of chemical engineering and materials science
and engineering; Tyler Culp, a chemical engineering doctoral alumnus and Gomez's former student; and Nichole Wonderling, a staff scientist and
X-ray scattering manager with Penn State's Materials Research Institute.

The National Science Foundation supported this research.

========================================================================== Story Source: Materials provided by Penn_State. Original written by
Gabrielle Stewart. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Janna N. Sloand, Tyler E. Culp, Nichole M. Wonderling, Enrique
D. Gomez,
Scott H. Medina. Mechanomorphogenic Films Formed via Interfacial
Assembly of Fluorinated Amino Acids. Advanced Functional Materials,
2021; 2104223 DOI: 10.1002/adfm.202104223 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210727171639.htm

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