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- 저자 : Rega PERMANA (검색결과 4 건)
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Dwivedi, Amarendra Dhar,Permana, Rega,Singh, Jitendra Pal,Yoon, Hakwon,Chae, Keun Hwa,Chang, Yoon-Seok,Hwang, Dong Soo Elsevier 2017 Chemical engineering journal Vol.328 No.-
<P><B>Abstract</B></P> <P>Inspired by naturally occurring metal chelation strategy by pyrogallol moiety of tunichromes of marine tunicates, a strong retention of carcinogenic chromium (Cr<SUP>VI</SUP>) is described by mimicking tunichrome matrix as a proof-of-concept investigation in water treatment applications. Harvesting tunichromes tailored with the pyrogallol moiety are extremely difficult owing to aerial sensitivity and purification difficulties, thus proving a challenging synthesis problem. Despite significant interest, knowledge of specific metal coordination in tunicate’s matrix is still ambiguous, hindering study scope. We planned to fabricate a promising tunichrome matrix (TM) tailored with pyrogallol moieties from the Earth-abundant raw materials (gallic acid and chitin nanofiber) at mass scale without artificial aid. Specifically, we aimed at atomistic understanding of contaminant and pyrogallol moiety of TM by examining the structural parameters (redox change, geometrical distortion, coordination bond). Cr <I>K</I>-edge extended X-ray absorption fine structure (EXAFS) corresponds well to nontoxic Cr<SUP>III</SUP> (average four CrO bond lengths of 1.91Å) and a small fraction of Cr<SUP>VI</SUP> (average two CrO bond lengths of 1.62Å). A coupled reductive complexation mechanism was identified by combining near edge X-ray absorption fine structure (NEXAFS) and linear combination fits. From the viewpoint of practical utility and effective performance (nearly 119mg chromium per g weight of TM), the impacts of water chemistry conditions were investigated from a variety of contaminated waters, showing a distinct improvement compared to conventional popular materials. The gained knowledge would be beneficial for utilizing a pyrogallol moiety as an alternative greener and sustainable scavenger, specifically for toxic chromium.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A newly designed nano-bio tool inspired by marine tunicate, a filter feeder. </LI> <LI> Superior retention of Cr<SUP>VI</SUP> by mimicking tunichrome matrix in remediation treatment. </LI> <LI> Pyrogallol – a primary factor in increased efficiency as a proof-of-concept study. </LI> <LI> First comprehensive report on tunichrome’s chromium metal coordination chemistry. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Dwivedi, Amarendra Dhar,Permana, Rega,Singh, Jitendra Pal,Yoon, Hakwon,Chae, Keun Hwa,Chang, Yoon-Seok,Hwang, Dong Soo American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.23
<P>Tunicate, 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 Au-0. A catalytic reduction of 4-nitrophenol mediated by the-tunicate-mimetic matrix with harvested gold revealed excellent recyclability up to 30 cycles (similar to 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..</P>
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