Water Effect on Acid-Gas Capture Using Choline Lactate:
A DFT Insight beyond Molecule–Molecule Pair Simulations
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Abstract
The
suitability of CO<sub>2</sub> and SO<sub>2</sub> capture by
using choline lactate ionic liquid as a sorbent and the effect of
water content for acid-gas absorption were investigated through density
functional theory (DFT) simulations in this work. Simulations that
contain model systems considering up to four molecules (cholinium,
lactate, water, and CO<sub>2</sub>/SO<sub>2</sub>) have been analyzed,
and compositional effects on small cluster(s) formed by four ionic
pairs and variable number of water molecules have been studied in
this work. Assessment of the effect of water content on acid-gas capture
that uses exotic ionic liquids is a rare study, and our results showed
that water presence hinders CO<sub>2</sub>/SO<sub>2</sub> affinity
and solubility dramatically, mainly due to the dominated affinity
between the ionic pair and water molecule rather than the CO<sub>2</sub>/SO<sub>2</sub> molecule. Moreover, our studies also showed that
affinity between ionic liquid and CO<sub>2</sub> is hindered by more
than ionic liquid and SO<sub>2</sub> rich system with the presence
of water in the environment
