Ennoblement Due to Biofilms: Indicator for Potential Corrosion and Source of Electrical Energy
Brenda J. Little, Jason S. Lee, Richard I. Ray, Shelton Austin and Justin C. Biffinger
Affiliation: Naval Research Laboratory, Code 7303, 1009 Balch Blvd, Stennis Space Center, MS 39529, USA.
Ennoblement, a positive shift in corrosion potential, due to biofilm formation is the basis of patents for biofilm
monitoring and power generating devices. Ennoblement is a global phenomenon that is routinely cited as a mechanism
for microbiologically influenced corrosion of some passive alloys. Increased corrosion is attributed to acceleration of the
oxygen reduction reaction via several potential mechanisms that have been debated for decades. Because the phenomenon
is predictable and reproducible at specific locations, ennoblement is the basis for patented methods and devices for monitoring
biofilm formation and relating ennobled potentials to increased likelihood of corrosion and for evaluating cleaning
and biocide treatments. Furthermore, when anodes and cathodes can be separated, as in a microbial fuel cell, biofilm formation
on the cathode increases the potential difference between the two and the resulting power output. Most patented
fuel cells using metal cathodes do not refer specifically to ennoblement in the disclosures.
Keywords: Biofilms, ennoblement, microbial fuel cell, microbiologically induced corrosion, microbiologically influenced corrosion, oxygen reduction reaction, redox-active compounds, seawater battery, microbial film, MICROBE-BASED POWER SOURCES
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