Water Effect on Acid-Gas Capture Using Choline Lactate: A DFT Insight beyond Molecule–Molecule Pair Simulations

The suitability of CO₂ and SO₂ 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 CO₂/SO₂) 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 CO₂/SO₂ affinity and solubility dramatically, mainly due to the dominated affinity between the ionic pair and water molecule rather than the CO₂/SO₂ molecule. Moreover, our studies also showed that affinity between ionic liquid and CO₂ is hindered by more than ionic liquid and SO₂ rich system with the presence of water in the environment