Towards the potential of cyano and amino acid-based ionic liquid mixtures for facilitated CO2 transport membranes

Aiming at developing improved liquid phases for facilitated CO2 separation from post-combustion processes through supported ionic liquid membranes (SILMs), this work explores the use of binary equimolar IL mixtures containing a common imidazolium cation combined with tricyanomethane and five amino acid-based anions, glycinate, L-alaninate, taurinate, t-serinate and L-prolinate. The CO2 and N-2 permeation properties of the prepared SILMs were determined at T=318.15 K and several trans-membrane pressure differentials. The results indicate that as the trans-membrane pressure differential decrease, the CO2 permeability through the SILMs containing the IL mixtures approaches or even surpasses that of the pure [C(2)mim][C(CN)(3)]. Similarly, the CO2/N-2 permselectivity significantly increases, meaning that the prepared IL mixtures work as CO2 carriers under low trans-membrane pressure differentials, facilitating the flux of CO2 through SILMs. In particular, large CO2 permeabilities and high CO2/N-2 permselectivities were obtained for the IL mixtures containing L-alaninate and taurinate anions, indicating that they can be considered as promising and efficient liquid phases for facilitated CO2 separation. (C) 2016 Elsevier B.V. All rights reserved.