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Inqui r y I s sue
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afer. Sustainable. Customizable. Multi-functional.
Ames Laboratory and Critical Materials Institute
materials chemist Anja Mudring is harnessing these
promising qualities of ionic liquids, salts in a liquid
state, to optimize processes for critical materials.
“Ionic liquids have a lot of useful qualities, but most
useful for materials processing is that ionic liquids are made
up of two parts: the cation and the anion. We can play around
with the chemical identities of each of those components
and that opens the doors to huge amount of options,” says
Mudring. “That means we can really engineer ionic liquids
with specific functions in mind.”
One such function is improving the rare-earth separation
process, either for use extracting rare earths from ore or
recycling rare earths from discarded magnets.
“We are tuning the ionic liquids in such a way that
they dissolve rare-earth oxides, and then we’re using
electrodeposition, where electricity is run through a liquid
to create a chemical change to get the rare earth in metal
form,” says Mudring, who is also a professor of materials
science and engineering at Iowa State University.
Traditionally, electrodeposition processes are extremely
high temperature and often require corrosive chemicals. But
Mudring’s process requires much lower temperatures and
ionic liquids are less hazardous, so less energy is needed and
the process is safer and greener.
Mudring’s group is also using ionic liquids to create
phosphors for compact fluorescent light bulbs.
“We’re using ionic liquids, putting them in a microwave,
energizing them, and creating a phosphors material. The
phosphors particles are less than 10 nanometers, which
means they do not scatter light, key for optical applications
like for compact fluorescent light bulbs,” says Mudring.
Better yet, Mudring’s process also reduces the amount
of rare-earth materials required in the process, and may
someday make it possible to replace mercury vapor with less-
hazardous noble gases in CFLs. And looking farther down
the road, the new phosphors could also be used in LEDs as
they continue to replace CFLs.
“Ionic liquids are the key to the improvements in this
material synthesis,” says Mudring. “They function as the
solvent, a safer one than an alcohol or other combustible
solvent. And they are also the reaction partner. Here, the
ionic liquid is the fluoride source, so we can omit hazardous
hydrofluoric acid from the process. Again, that makes the
process safer and cleaner. And they even function to stabilize
the nanoparticles created in the process, eliminating the
need for an additional stabilizer. Three functions in one!
Add to that how efficiently ionic liquids take up microwave
energy and there’s just huge potential there for improving
materials synthesis.”
IonicLiquids,HighHopes
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