Microbial Nanobiotechnology in Nanocatalysis: Degradation …
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lowered by Chlorella vulgaris silver nanoparticles (66.10%), Nannochloropsis sp.
silver nanoparticles (68.86%), Chlorella vulgaris gold nanoparticles (57.41%), and
Nannochloropsis sp. gold nanoparticles (66.53%) (Adenigba et al. 2020). The
improved performance of both gold and silver nanoparticles compared to their
biomass could be attributed to the increased reaction surface area, increasing binding
sites that are available for the metals to adhere to the cells (Taman et al. 2015).
Iron sulfide material, which is formed via sulfate-reducing bacteria, is considered
to be best adsorbent for many heavy metals. It has the ability to adsorb between 100
and 400 mg g
−1 , and residual levels in solutions can be of the order of pg per liter. Iron
sulfide material has strong magnetic forms which could be produced and removed
from the suspension with the adsorbate through magnetic separation. Before drying,
the surface area of both the strongly magnetic and weakly magnetic iron sulfides
is of the order of 400–500 m
2 g
−1 as reported by the neutron scattering, magnetic
characters, and the adsorption of several heavy metals. The strongly magnetic and
weakly magnetic iron sulfides are considered to be effective adsorbents for heavy
metals (Watson et al. 2000).
4 Additional Catalytic Applications
Multiple other applications of biosynthesized nanoparticles have been reported.
Hydrogen was produced from hypophosphite using biosynthesized Pd nanoparticles
as a catalyst. The resulting release of hydrogen was taken as a measure to estimate
the catalytic effect. The Pd nanoparticles in this project were procured by bacteria
biomass and cell-free methods. Immediately after adding hypophosphite to bioPd
nanoparticles, hydrogen was liberated with a high initial release rate. The percentage
of release of hydrogen however leveled off after roughly 10 min. It was seen that the
cell-free Pd nanoparticles exhibited a higher hydrogen release rate and performed
better than the bacteria biomass control. Researchers that carried out this study believe
that the difference was supposedly because a fraction of bioPd nanoparticles fixed
in the cell envelope was unreachable (Bunge et al. 2010).
Cu nanoparticles were biosynthesized intracellularly using Shewanella oneidensis
MR-1 by a group. For the assessment of the catalytic azide-alkyne cycloadditions
performance of Cu nanoparticles, the production of multiple triazole derivatives was
done via Cu
+ -catalyzed cycloaddition of benzyl azide (Kimber et al. 2018). It was
suggested by the authors that when Cu nanoparticles came in direct contact with
air, a partially oxidized Cu 2 O thin shell will be developed. The Cu nanoparticles
showed good catalytic effect toward copper catalyzed azide-alkyne cycloaddition
suggesting it as a green and simple synthesis approach for production of reactive Cu
nanocatalysts. Also, stabilizing compounds or inorganic substances could be another
contributing factor toward this significant catalytic activity (Velmurugan et al. 2017).
It was proven in another study that the electro-catalytic oxidation of hydrazine
was notably upheld by bio-Ag nanoparticles. Through AgNO 3 precursor reduction
389
lowered by Chlorella vulgaris silver nanoparticles (66.10%), Nannochloropsis sp.
silver nanoparticles (68.86%), Chlorella vulgaris gold nanoparticles (57.41%), and
Nannochloropsis sp. gold nanoparticles (66.53%) (Adenigba et al. 2020). The
improved performance of both gold and silver nanoparticles compared to their
biomass could be attributed to the increased reaction surface area, increasing binding
sites that are available for the metals to adhere to the cells (Taman et al. 2015).
Iron sulfide material, which is formed via sulfate-reducing bacteria, is considered
to be best adsorbent for many heavy metals. It has the ability to adsorb between 100
and 400 mg g
−1 , and residual levels in solutions can be of the order of pg per liter. Iron
sulfide material has strong magnetic forms which could be produced and removed
from the suspension with the adsorbate through magnetic separation. Before drying,
the surface area of both the strongly magnetic and weakly magnetic iron sulfides
is of the order of 400–500 m
2 g
−1 as reported by the neutron scattering, magnetic
characters, and the adsorption of several heavy metals. The strongly magnetic and
weakly magnetic iron sulfides are considered to be effective adsorbents for heavy
metals (Watson et al. 2000).
4 Additional Catalytic Applications
Multiple other applications of biosynthesized nanoparticles have been reported.
Hydrogen was produced from hypophosphite using biosynthesized Pd nanoparticles
as a catalyst. The resulting release of hydrogen was taken as a measure to estimate
the catalytic effect. The Pd nanoparticles in this project were procured by bacteria
biomass and cell-free methods. Immediately after adding hypophosphite to bioPd
nanoparticles, hydrogen was liberated with a high initial release rate. The percentage
of release of hydrogen however leveled off after roughly 10 min. It was seen that the
cell-free Pd nanoparticles exhibited a higher hydrogen release rate and performed
better than the bacteria biomass control. Researchers that carried out this study believe
that the difference was supposedly because a fraction of bioPd nanoparticles fixed
in the cell envelope was unreachable (Bunge et al. 2010).
Cu nanoparticles were biosynthesized intracellularly using Shewanella oneidensis
MR-1 by a group. For the assessment of the catalytic azide-alkyne cycloadditions
performance of Cu nanoparticles, the production of multiple triazole derivatives was
done via Cu
+ -catalyzed cycloaddition of benzyl azide (Kimber et al. 2018). It was
suggested by the authors that when Cu nanoparticles came in direct contact with
air, a partially oxidized Cu 2 O thin shell will be developed. The Cu nanoparticles
showed good catalytic effect toward copper catalyzed azide-alkyne cycloaddition
suggesting it as a green and simple synthesis approach for production of reactive Cu
nanocatalysts. Also, stabilizing compounds or inorganic substances could be another
contributing factor toward this significant catalytic activity (Velmurugan et al. 2017).
It was proven in another study that the electro-catalytic oxidation of hydrazine
was notably upheld by bio-Ag nanoparticles. Through AgNO 3 precursor reduction