Biomedical Engineering Reference
In-Depth Information
Concrete example of platinum recovery is presented by Won et al. (
2010
) by
means of biosorption and subsequent incineration of PEI modified biomass (pre-
pared by attaching PEI onto the surface of inactive
E. coli
biomass). Wastewater
containing platinum used for the recovery study was obtained from an industrial
laboratory for inductively coupled plasma (ICP). Recovery efficiency of platinum
in ash after incineration was over 98.7%. Similar study with gold solution and eas-
ily accessible biomass of
Sargassum sp.
(Sathishkumar et al.
2010a
) confirms
recovery efficiency more than 90%.
3.2
Catalysis Applications
Based on the basic knowledge of inorganic catalysis, noble metal NP catalysts are
very attractive when compared to bulk catalyst - they have a high surface to volume
ratios and their surface atoms are very active. For more knowledge and information
about the noble metal nanocatalysists in colloidal solutions or adsorbed on different
supports, we recommend numerous review articles, which have been published for
many different types of organic and inorganic reactions (Narayanan
2010
;
Narayanan and El-Sayed
2008
; Roucoux et al.
2008
; Thibault-Starzyk et al.
2008
;
Kumar et al.
2004
; Shiju and Guliants
2009
).
3.2.1
Biosorption and Biosynthesis of Palladium Nanoparticles
in Organic and Inorganic Catalysis
The first large group of biosynthesized nanomaterials with catalytic activity is rep-
resented by palladium NPs. Baxter-Plant et al. (
2003
;
2004
) reported usage of cell
surface of three different species of
Desulfovibrio
(G− sulfate-reducing bacteria)
for manufacturing the novel bioinorganic catalyst via reduction process of Pd(II) to
Pd(0). Although the presence of reducing agent is necessary (e.g. in form of H
2
) for
the Pd(0) genesis, reduction process is critically influenced by the bacteria presence
and we can indicate this biosorption process as a biosynthesis. On the other hand,
reduction in the absence of cells does not lead to the formation of Pd(0) NPs
(Bunge et al.
2010
). This catalyst on “palladised cells” was used for reductive deha-
logenation of chlorophenol (CP) and selected polychlorinated biphenyl (PCB)
types. The same organism was used for dehalogenation of the other environmen-
tally prevalent PCBs and polybrominated diphenyl ether (Harrad et al.
2007
). The
versatility of “bioPd” catalyst is also demonstrated in various reactions including
dehalogenation of flame retardants such polybrominated diphenyl ether (PBDE) or
tris(chloroisopropyl)phosphate (TCPP). Authors also compare effectiveness
between biocatalyst, chemically reduced Pd(II) and commercial Pd(0) catalysts.
Although chemically reduced Pd(II) and commercial Pd(0) were more effective
debromination agents, “bioPd” dechlorinated TCPP was five times more effective
than using commercial Pd(0) catalyst (Deplanche et al.
2009
) (Table
2
).
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