Transcript ASE presentation

WELCOME
Allison
Mentor: Dr. Tratnyek
Frontline Mentor: Jim Nurmi
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Reduced Forms of Manganese
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• Manganese Metal (Mn0)
– Atomic Number 25
– Second most abundant
transition metal in the
Earth’s crust.
– Physical and chemical
properties similar to iron
metal.
http://en.wikipedia.org/wiki/Manganese
• Aq Manganese (Mn2+)
– Bioavailable form of
manganese.
– Found in soils, sediments,
and natural waters.
– Occurs as a cation in
solution.
Photo from Wendy Smythe
Oxidized Forms of Manganese
• Manganese Dioxide (MnO2)
– Plays a key role in the
biogeochemical cycles of
metals and organic carbon.
– Can degrade pollutants
through oxidation.
– Used as a cathode in dry http://en.wikipedia.org/wiki/Manganese_dioxide
cells and batteries.
• Permanganate (MnO4-)
– Powerful oxidizer used for
water treatment.
– Violet color
www.liboxgoa.com/potassium%20permanganate.html
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Areas of Manganese Research
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Biogeochemistry
• Naturally abundant
• Bacteria can oxidize Mn(II) in natural
aqueous environments
Remediation
• Soil and sediment remediation
• Metal removal and recovery
Toxicology
• Environmental impact
• Overexposure can lead to permanent,
neurodegenerative damage, with
symptoms of Parkinson’s disease
Energy Storage
• Accumulate charges at the
electrode/electrolyte interface.
• Power supply
Purpose: Capacitance of Biogenic Manganese
Compare the electrical potential of
synthetic MnO2 and biogenic manganese
oxides by fabricating electrodes and
measuring current vs. potential by cyclic
voltammetry.
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Electrochemical Setup
• Potentiostat
• Glassy carbon
rotating disk
electrode
• Ag/AgCl reference
electrode
• Platinum wire
counter electrode
• Na2SO4 electrolyte
solution
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Source of Materials
• Self Made
– Precipitate KMnO4 and polyethelyne glycol
• Adapted from Ragupathy, P., et al, “Remarkable
Capacity Retention of Nanostructured Manganese
Oxide upon Cycling as an Electrode Material for
Supercapacitor”
• Manufactured
– Mn2O3 from Fisher Scientific
• Biogenic manganese from P. Putida GB-1
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Comparison of Methods: Mao’s Method
• Ethanol
• 5 wt % Nafion solution
iAdapted
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• MnO2 particles
Mao, L., et al. “Electrochemical Characterization of Catalytic Activities of Manganese
Oxides to Oxygen Reduction in Alkaline Aqueous Solution.” Journal of The Electrochemical
Society, 149 (2002): 504-507.
Comparison of Methods: Liu’s Method
• MnO2
• Acetylene black
iiAdapted
• Polyvinylidene fluoride
(PVDF)
• N-methyl-2-pyrrolidone
(NMP)
from Liu, E., et al. “Potentiodynamical deposition of nanosized manganese oxides
as high capacitance electrochemical capacitors.” Journal of Materials Science: Materials in
Electronics 18 (2007): 1179–1182.
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Method Experimentation Results
• Liu’s Method is used in because of better
electrode coverage
• Electrode tip must be heated in so MnO2
slurry adheres to electrode
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Results
Fig. 1a
Cyclic voltammetry,
Various types of manganese on
electrode surface
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Fig. 1b
Differential CV,
ΔI vs. Potential Manganese
Conclusions
• Reproducible electrochemical results
• CVs of synthetic manganese oxides and
biogenic manganese produce different results,
which demonstrates that they have different
electrochemical characteristics.
• Larger capacitance differences are observed
at intermediate potentials
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Thank you Dr. Paul Tratnyek, Dr. Jim Nurmi,
Karen Wenger, Dr. Antonio Baptista, Elizabeth
Woody, CMOP, and the Apprenticeships in
Science and Engineering program for making
my internship possible.