Biomedical Engineering Reference
In-Depth Information
cell for power production. It was shown to have a maximum power generation
comparable to the commercial catalyst (Ogi et al. 2011 ).
Fusion of waste biorefining and cheap nanocatalyst for fuel cells and power
generation employing D. desulfuricans, E. coli and C. metallidurans , carbon paper
and proton exchange membrane fuel cell was recently published (Yong et al. 2010 ).
Using an E. coli MC4100 strain, a mixed metallic catalyst was manufactured from
an industrial processing waste. This mixed-metal biocatalyst gave approximately
50% of the power output compared to commercial or “bioPd” D. desulfuricans
catalyst. Electrical energy production efficiency of biocatalyst fabricated by afore-
mentioned E. coli (parent) strain and its derived mutant strain IC007 (as well as a
comparison with D. desulfuricans ) is further discussed by Orozco et al. ( 2010 ).
Another electrocatalysis application with modified electrodes is also mentioned
in Sect. 3.5.1 .
3.2.3
Catalysis of 4-Nitrophenol Reduction Reactions
Presence of toxic pollutants such as nitro-aromatic compounds in soil and water is
a result of incomplete combustion of fossil fuels and their usage as chemical feed-
stock for synthesis of explosives, pesticides, herbicides, dyes, pharmaceuticals, etc.
The headlong and reckless utilization of these pollutants in the past has resulted in
wide-ranging environmental pollution. The usage of biosynthesized NPs capable to
catalyze degradation of, among other chemicals, nitro-aromatics (and then together
with microbial remediation), would be a great contribution to this particularly topi-
cal issue (take a look at the following reviews for more information - Kulkarni and
Chaudhari 2007 ; Liotta et al. 2009 ; Lewis et al. 2004 ; Guimarães et al. 2010 ).
As the first report of a NP-bearing biomatrix directly reducing a toxic pollutant
4-nitrophenol ( p -nitrophenol; 4-NP), Sharma et al. ( 2007 ) published experiments of
growth of Sesbania seedlings in chloroaurate Au(III) solution. This procedure
resulted in the accumulation of gold with the formation of stable AuNPs in plant
tissues. The catalytic effectiveness of the biomass with Au(0)NPs was documented
by the reduction of aqueous 4-nitrophenol (4-NP).
Remarkably, extensive research was performed using 21 traditional Chinese
medicinal plant and herb species (Huang et al. 2009 ). After classification into four
categories including leaves, flowers, fruits, and grasses, effectiveness of the proto-
col in producing AuNPs was demonstrated usually after 30 min of incubation with
aqueous HAuCl 4 . Potential application of the these biogenic AuNPs as catalysts
was exhibited in Cacumen Platycladi (which exhibited biosynthesis of very small
and monodisperse NPs). Catalytic reduction of 4-NP showed excellent catalytic
performance compared to the aforementioned study (Sharma et al. 2007 ).
For instance of AgNPs, Jia et al. ( 2008 ) reported the use of a cuttlebone-derived
organic matrix (from Sepia esculenta ) as scaffold and reducer for the formation of
AgNPs. The resulting composite was applied to catalyze the reduction of 4-NP.
Possibilities of separation from the liquid-phase reaction and reusability in more
cycles have been also reported.
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