Effect of water activity on carbon dioxide transport in cholinium-based ionic liquids with carbonic anhydrase

•Cholinium-based ionic liquids are extremely selective towards carbon dioxide (CO2).•The highest CO2 solubility was obtained with cholinium hexanoate.•A CO2 diffusion coefficient correlation for the cholinium-based ionic liquids.•CO2 transport enhancement is promoted by carbonic anhydrase enzyme.•The highest CO2 permeability enhancement was observed in cholinium propionate.