Renewable Carbon Dioxide Sponge - Promising Material For Carbon Fixation!
Concerned about adding too much carbon dioxide to the
atmosphere? Consider a roof top coating on your car with this new
material!
Researchers report the development of a strong and reversible
sponge-like material to capture and store gaseous carbon dioxide.
Carbon dioxide is considered a green house gas and its control is a
pressing environmental problem.
According to the research report, the new material, in its porous
crystalline state, is very efficient at adsorbing carbon dioxide.
These porous crystals -- known as metal-organic frameworks (MOFs) --
are made from all-natural ingredients and are simple to prepare, giving
them a huge advantage over other MOFs. Conventional MOFs, which also are
effective at adsorbing carbon dioxide, are usually prepared from
materials derived from crude oil and often incorporate toxic heavy
metals. They are also non-renewable.
Other features of the Northwestern MOFs are they turn red when
completely full of carbon dioxide, and the carbon capture process is
reversible.
When a yellow dye, called pH indicator, is placed within the voids of the metal-organic frameworks (MOFs), the crystals turn yellow. However, upon exposure to carbon dioxide, the pH indicator switches to a red color, indicating that the MOF has both reacted and filled up with carbon dioxide. If the crystals are placed away from high concentrations of carbon dioxide, the gas leaves, and the crystals once again turn yellow. Image provided to ScienceDebate.com by Dr.J Fraser Stoddart.
The findings, made by scientists working in the laboratory of Sir
Fraser Stoddart, Board of Trustees Professor of Chemistry in the
Weinberg College of Arts and Sciences, are published in the Journal of the American Chemical Society (JACS).
“We are able to take molecules that are themselves sourced from
atmospheric carbon, through photosynthesis, and use them to capture even
more carbon dioxide,” said Ross S. Forgan, a co-author of the study and
a postdoctoral fellow in Stoddart’s laboratory. “By preparing our MOFs
from naturally derived ingredients, we are not only making materials
that are entirely nontoxic, but we are also cutting down on the carbon
dioxide emissions associated with their manufacture.”
The main component, gamma-cyclodextrin (CD), is a naturally occurring
biorenewable sugar molecule that is derived from cornstarch.
The sugar molecules are held in place by metals taken from salts such
as potassium benzoate or rubidium hydroxide, and it is the precise
arrangement of the sugars in the crystals that is vital to their
successful capture of carbon dioxide.
“It turns out that a fairly unexpected event occurs when you put that
many sugars next to each other in an alkaline environment -- they start
reacting with carbon dioxide in a process akin to carbon fixation,
which is how sugars are made in the first place,” said Jeremiah J.
Gassensmith, lead author of the paper and also a postdoctoral fellow in
Stoddart’s laboratory. “The reaction leads to the carbon dioxide being
tightly bound inside the crystals, but we can still recover it at a
later date very simply.”
The fact that the carbon dioxide reacts with the MOF, an unusual
occurrence, led to a simple method of detecting when the crystals have
reached full capacity. The researchers place an indicator molecule,
which detects changes in pH by changing its color, inside each crystal.
When the yellow crystals of the MOFs are full of carbon dioxide they
turn red.
The simplicity of the new MOFs, allied with their low cost and green
credentials, have marked them as candidates for further
commercialization. Ronald A. Smaldone, also a postdoctoral fellow in
Stoddart’s group and a co-author of the paper, added, “I think this is a
remarkable demonstration of how simple chemistry can be successfully
applied to relevant problems like carbon capture and sensor technology.”
The authors conclude that "the fact that CD-MOFs can be made from
environmentally benign materials whose synthesis is essentially
carbon-neutral and have the demonstrated ability to absorb carbon
dioxide from the atmosphere makes them promising materials for carbon
fixation."
Source Article: Strong and Reversible Binding of Carbon Dioxide in a Green Metal–Organic Framework.
JJ Gassensmith, H Furukawa, R. Smaldone, RS Forgan, YY Botros, OM
Yadhi and JF Stoddart. Journal of the American Chemical Society.
Published online September 2011.
