Indian American develops efficient carbon capture method

Seema Hakhu Kachru

Houston, Jul 25 (PTI) An Indian American scientist has
developed a new screening method to separate carbon dioxide
from its source more efficiently.

Amitesh Maiti, a researcher at the Lawrence Livermore
National Laboratory (LLNL), has devised a computational
screening method using ionic liquid solvent to enhance the
process of carbon dioxide (CO2) separation, a step known as
'carbon capture'.

Ionic liquids, a type of salt that melts at 100 degrees
Celsius, have advantages over traditional solvents for the
separation of CO2 from its polluting source such as flue gas
because they are highly stable, non-corrosive and do not
evaporate even at high temperature.

Current carbon capture technology is based on a general
purpose solvent monoethanolamine (MEA), which chemically
absorbs CO2. However, it is a non-selective corrosive which
requires large-scale equipment and it works only under low to
moderate partial pressure of CO2.

"With ionic liquids serving as the solvent, the process
could be a lot cleaner and more accessible than that used
today," says Amitesh.

There is also a huge choice of ions, which could
potentially be optimised for CO2 capture.

"By creating a computational tool that can decipher ahead
of time which ionic liquids work best to separate CO2, it can
be a much more efficient process when field tests are
conducted," he added.

"It's a great advantage to have a method that can quickly
and accurately compute CO2 solubility in any solvent,
especially under the range of pressures and temperatures as
would be found in a coal-fired power plant," Amitesh said.

Advantages include high chemical stability, low
corrosion, almost zero vapor pressure, supportable on
membranes and a huge library of ion choices which can be
potentially optimised for CO2 solubility.

Originally from Kolkata, Amitesh has earned his Ph.D in
Condensed Matter Physics, University of California, Berkeley,
1992, MS, Physics, University of North Carolina, Chapel Hill,
1988 and B.Sc, Physics (honors), University of Calcutta,
India, 1986.

Amitesh' s work involved devising a computational
strategy that can reliably screen any solvent, including an
ionic liquid, for high CO2 capture efficiency.

Over the last few years several ionic liquids have been
tested to be efficient solvents, providing data that could be
useful in optimising the choice of ionic liquids for CO2
capture. "But each new experiment costs time and money and is
often hindered because a specific ionic liquid may not be
readily available," he said.

Amitesh developed a quantum-chemistry-based thermodynamic
approach to compute the chemical potential of a solute (CO2 in
this case) in any solvent at an arbitrary dilution.

He found that this result coupled with an experimentally
fitted equation-of-state data for CO2 can yield accurate
solubility values in a large number of solvents, including
ionic liquids.

He confirmed this by directly comparing the computed
solubility with experimental values that have been gradually
accumulating over the last few years.

He used this method to predict new solvent classes that
would possess CO2 solubility nearly two times as high as the
most efficient solvents experimentally demonstrated.

"With the vast choices of ions, we have barely scratched
the surface of possibilities," Amitesh said.

He hopes that the accuracy of the computational method
will allow scientists to see useful trends, which could
potentially lead to the discovery of practical solvents with
significantly higher CO2 capture efficiency. PTI