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Tunichrome-Inspired Gold-Enrichment Dispersion Matrix and Its Application in Water Treatment: A Proof-of-Concept Investigation
journal contribution
posted on 2017-05-23, 00:00 authored by Amarendra Dhar Dwivedi, Rega Permana, Jitendra Pal Singh, Hakwon Yoon, Keun Hwa Chae, Yoon-Seok Chang, Dong Soo HwangTunicate,
a filter-feeder in seawater, is able to accumulate high amount of
metals using intracellular polymer matrices. The woven pyrogallol
structures of tunichrome, a small peptide contained in tunicate’s
blood cells, is believed to be responsible for selective metal sequestration
in tunicates from seawater. However, the intriguing tunichrome matrix
is difficult both to harvest from the tunicate and to synthesize massively
due to the extreme oxidation sensitivity of the pyrogallol moiety
which limits the study scope. Here, we succeeded to mimic tunichrome
by conjugating two cheap and naturally occurring components: pyrogallol-5-carboxylic
acid (gallic acid) and chitin nanofiber. A tunicate-mimetic infiltration
matrix of surface-tailored chitin nanofibers with pyrogallol moieties
(CGa) demonstrated the versatility of this strategy in generation
of ingenious filtration material, especially for unprecedented fine
and clean gold recovery inside of the tunicate-mimetic infiltration
matrix (>99%, 533 mg gold per gram weight), which exceeds that
of the presently most popular materials. Complexation between pyrogallol
on the nanofiber and gold was similar to that of a tunichrome’s
metal sequestration. Extended X-ray absorption fine structure (EXAFS)
spectroscopy and data-fitting elucidated the decreased coordination
numbers for Au–Au nearest neighbors, demonstrating that gold
coordinated to pyrogallol units, followed by an intramolecular association
of Au0. A catalytic reduction of 4-nitrophenol mediated
by the tunicate-mimetic matrix with harvested gold revealed excellent
recyclability up to 30 cycles (∼95% reduction), which together
with methylene blue reduction and antimicrobial performances indicates
the versatile characteristics of sustainable processes by the tunichrome
mimetics. This strategy opens the door for fast-developing new biomimetic
alternatives for precious metal recovery, which is not restricted
to gold and can offer a tool for multifaceted soft/hard nanomaterials.
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Keywords
surface-tailored chitin nanofibersEXAFSfiltration materialgallic acidpyrogallol moietymetal recoveryExtended X-ray absorptionProof-of-Concept Investigation Tunicatepyrogallol -5-carboxylic acidpyrogallol structuresoxidation sensitivitytunicate-mimetic matrixtunicate-mimetic infiltration matrixintracellular polymer matricesbiomimetic alternativesintramolecular associationpyrogallol unitsantimicrobial performanceschitin nanofiberpyrogallol moietiesstudy scopemetal sequestrationcoordination numberstunichrome mimeticsgold recoverytunichrome matrix4- nitrophenolTunichrome-Inspired Gold-Enrichment Dispersion MatrixWater Treatment
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