CO
2
capture
at the production site represents one of
the accessible ways to reduce
its emission in the atmosphere. In this context, CO
2
chemisorption
is particularly advantageous and is often based on exploiting a liquid
containing amino groups that can trap CO
2
due to their
propensity to react with it to yield carbamic derivatives. A well-known
class of ionic liquids based on amino acid anions might represent
an ideal medium for CO
2
capture because, at difference
with present implementations, they are known to be fully biocompatible.
One of the problems is however the relatively low molar ratio of CO
2
absorption. Increasing this ratio turns out to be possible
by choosing appropriate anions. We present here a set of accurate
computations to elucidate the possible reaction paths that allow the
anion to absorb two CO
2
molecules, thus effectively doubling
the overall intake. An extensive exploration of some reaction mechanisms
suggests that some of them might be quite efficient even under mild
conditions.