4 research outputs found
Indoor Air Purification Using Activated Carbon Adsorbers: Regeneration Using Catalytic Combustion of Intermediately Stored VOC
In this study, we demonstrate a two-step
process where activated
carbon based air purifier systems can be regenerated in situ and eliminate
volatile organic compounds (VOCs) from indoor air in an energy efficient
way. A carbon based adsorber was combined in series with a CeO<sub>2</sub>/TiO<sub>2</sub> oxidative catalyst for total oxidation of
the previously adsorbed and periodically released volatile organic
compounds during regeneration runs. We investigated the adsorption
and desorption behavior of five different VOCs (diethyl ether, limonene,
linalool, hexanoic acid, triethylamine and <i>n</i>-decane)
with thermogravimetric measurements, mass spectrometry and elemental
analysis. Cyclic loading and regeneration experiments were carried
out with selected VOCs (limonene, linalool and <i>n</i>-decane)
for testing regeneration at elevated temperature. We showed that in
situ thermal regeneration and subsequent oxidation of released VOC
is a sustainable and easy applicable technology for indoor air purification.
This two-step approach allows energy saving as the VOCs are eliminated
discontinuously (enriching VOCs; periodic catalytic combustion), and
is of high environmental and economic interest, as much less maintenance
services are required
Efficient Magnetic Recycling of Covalently Attached Enzymes on Carbon-Coated Metallic Nanomagnets
In the pursuit of robust and reusable
biocatalysts for industrial
synthetic chemistry, nanobiotechnology is currently taking a significant
part. Recently, enzymes have been immobilized on different nanoscaffold
supports. Carbon coated metallic nanoparticles were found to be a
practically useful support for enzyme immobilization due to their
large surface area, high magnetic saturation, and manipulatable surface
chemistry. In this study carbon coated cobalt nanoparticles were chemically
functionalized (diazonium chemistry), activated for bioconjugation
(<i>N,N</i>-disuccinimidyl carbonate), and subsequently
used in enzyme immobilization. Three enzymes, β-glucosidase,
α-chymotrypsin, and lipase B were successfully covalently immobilized
on the magnetic nonsupport. The enzyme–particle conjugates
formed retained their activity and stability after immobilization
and were efficiently recycled from milliliter to liter scales in short
recycle times
Efficient Magnetic Recycling of Covalently Attached Enzymes on Carbon-Coated Metallic Nanomagnets
In the pursuit of robust and reusable
biocatalysts for industrial
synthetic chemistry, nanobiotechnology is currently taking a significant
part. Recently, enzymes have been immobilized on different nanoscaffold
supports. Carbon coated metallic nanoparticles were found to be a
practically useful support for enzyme immobilization due to their
large surface area, high magnetic saturation, and manipulatable surface
chemistry. In this study carbon coated cobalt nanoparticles were chemically
functionalized (diazonium chemistry), activated for bioconjugation
(<i>N,N</i>-disuccinimidyl carbonate), and subsequently
used in enzyme immobilization. Three enzymes, β-glucosidase,
α-chymotrypsin, and lipase B were successfully covalently immobilized
on the magnetic nonsupport. The enzyme–particle conjugates
formed retained their activity and stability after immobilization
and were efficiently recycled from milliliter to liter scales in short
recycle times
Magnetic Superbasic Proton Sponges Are Readily Removed and Permit Direct Product Isolation
Workup in organic synthesis can be
very time-consuming, particularly
when using reagents with both a solubility similar to that of the
desired products and a tendency not to crystallize. In this respect,
reactions involving organic bases would strongly benefit from a tremendously
simplified separation process. Therefore, we synthesized a derivative
of the superbasic proton sponge 1,8-bisÂ(dimethylamino)Ânaphthalene
(DMAN) and covalently linked it to the strongest currently available
nanomagnets based on carbon-coated cobalt metal nanoparticles. The
immobilized magnetic superbase reagent was tested in Knoevenagel-
and Claisen–Schmidt-type condensations and showed conversions
of up to 99%. High yields of up to 97% isolated product could be obtained
by simple recrystallization without using column chromatography. Recycling
the catalyst was simple and fast with an insignificant decrease in
catalytic activity