Novel ionic liquid analogs formed by triethylbutylammonium carboxylate-water mixtures for CO2 absorption

► Ten ionic liquid analogs of triethylbutylammonium carboxylate and water have been used as CO2 absorbents. ► Physical properties of [N2224][carboxylate]-nH2O mixtures were reported. ► [N2224][butyrate]-1H2O was reused for four cycles with no obvious loss of its capacity. ► The initial absorption rate constants of all [N2224][CA]-nH2O were calculated. ► The CO2 absorption capacities of all [N2224][CA]-nH2O at a certain equilibrium partial pressure of CO2 were described.