Biosynthesis of Metallic Nanoparticles and Their Applications - Intracellular Delivery: Fundamentals and Applications - page 382

S. oneidensis bacterial strain was also used for removal of the pesticide lindane
(g-hexachlorocyclohexane or g-HCH) by catalytic reduction of g-HCH to benzene
(as more efficient than with commercial powdered Pd(0) - Mertens et al. 2007 ). The
same study introduces a membrane reactor technology suitable for dechlorination of
g-HCH polluted wastewater at a low-flux synthetic dialysis membrane. Similar
implementation of membrane reactor was introduced for degradation process of
diatrizoate - iodinated contrast media (ICM). Although currently applied techniques
such as advanced oxidation processes exhibit only limited removal efficiencies of
ICM, work by Hennebel et al. ( 2010 ) showed that membrane contactors with encap-
sulated biogenic NPs can be effective for contaminated water treatment. Topic of
reactor technology for “bioPd” catalysts is further pursued in works dealing with
dechlorination of trichloroethylene (TCE) in a pilot-scale membrane reactor
(Hennebel et al. 2009b ) and dechlorination of TCE by encapsulated palladium NPs
in a fixed bed reactor (Hennebel et al. 2009c ). Polyurethane cubes empowered with
“bio-Pd” were implemented in a fixed bed reactor for the treatment of water contain-
ing TCE. This study shows that the influent recycle configuration resulted in a
cumulative removal of 98% TCE after 22 h (with ethane as main reaction product).
The same reactor in a flow through configuration achieved removal rates up to
1,059 mg TCE g (Pd) −1 . day −1 .
Feasibility of another organisms for reduction of Pd(II) to Pd(0) for organic
catalysis was also demonstrated by other studies. Bacterial strains Rhodobacter
capsulatas and Arthrobacter oxidans were employed in “bioPd” formation for par-
tial hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol (Wood et al. 2010 ).
This “bioPd” was proven to be a highly selective catalyst for partial hydrogenation
reactions. Bunge et al. ( 2010 ) tested possibilities of three bacterial strains
( Cupriavidus necator, Pseudomonas putida, Paracoccus denitrificans ) on bioPd(0)
catalysis of hydrogen production from hypophosphite and further discuss the hypo-
thetical mechanism of bacterial reduction of Pd(II) to Pd(0). Remarkably, Pd(0)
catalysts fabricated by the organisms mentioned above were used also for catalysis
of Suzuki-Miyaura and Mizoroki-Heck reactions (briefly C―C bond formation)
by Sobjerg et al. ( 2009 ) and Gauthier et al. ( 2010 ). The enormous importance of
these reactions for organic synthesis may be confirmed by the long-anticipated
Nobel prize in Chemistry 2010 for their discoverers - Richard F. Heck, Ei-ichi
Negishi and Akira Suzuki (more about these reactions and NPs in review article by
Narayanan ( 2010 )). Moreover, aforementioned studies also contribute to the hot
issue of metal waste management and waste recovery.
Interestingly, Jia et al. ( 2009 ) published bioreduction method - reduction of pal-
ladium chloride by water crude extract - with plant Gardenia jasminoides Ellis'.
Abilities of this “bioPd(0)” nanocatalyst were tested and documented on hydroge-
nation reaction of p-nitrotoluene. The catalysts showed a conversion of 100% under
conditions of 5 MPa, 150°C for 2 h. The selectivity of the product - p-methyl-
cyclohexylamine - achieved 26.3%. The “bioPd(0)” catalyst was recycled five
times without any agglomeration and with highly maintained activity.
It is also well known that aforementioned bacterial species such as Shewanella
alga , Pseudomonas putida or Desulfovibrio vulgaris (Mabbett et al. 2002 ) may be