Investigation uncovered the impact of anions on CO2 absorption by low viscous ether functionalized pyridinium ionic liquids

Ionic liquids, which are designable and nonvolatile, have become a hot topic in the field of CO2 separation from industrial gases. In order to utilize the nonvolatile and low heat capacity of ionic liquids, it is necessary to solve the problem of high viscosity of pure ionic liquids. In the present study, ether functionalized pyridinium ion [E1Py](+) with good biodegradability and low viscosity was selected as cation. Ions containing cyano groups were used as anions, such as thiocyanate ion [SCN]-, dicyanamide ion [N (CN)(2)](-), tricyanomethanide ion [C(CN)(3)](-). Three ionic liquids with low viscosity were synthesized and characterized by (HNMR)-H-1, (CNMR)-C-13 and FTIR. The physiochemical properties of ionic liquids such thermal decomposition temperature, density and viscosity were tested. The CO2 absorption capacity was systematically studied by using intelligent gravimetric analyzer at the pressure range between 0 and 15 bars and the temperature range from 303.15 to 333.15 K. The results showed that the order of CO2 absorption capacity of these three ionic liquids is [E1Py][C(CN)(3)] > [E1Py] [N(CN)(2)] > [E1Py][SCN], which showed that the solubility increased by increasing more cyano groups in ionic liquids. Thermodynamic properties such as enthalpy, entropy, and Gibbs free energy were also calculated for CO2 absorption. (C) 2021 Elsevier B.V. All rights reserved