Solubilities of CO₂ in, and Densities and Viscosities of, the Piperazine + 1-Ethyl-3-methyl-imidazolium Acetate + H₂O System

Densities and viscosities of hybrid absorbents piperazine (PZ) (1) + 1-ethyl-3-methyl-imidazolium acetate ([Emim][Ac]) (2) + H 2 O (3) were respectively measured with different mass compositions ( w 1 / w 2 / w 3 = 0.3/0/0.7, 0.3/0.1/0.6, 0.3/0.2/0.5, 0.3/0.3/0.4, 0.2/0.3/0.5, 0.1/0.3/0.6, 0/0.3/0.7) at temperatures ranging from 313.15 K to 343.15 K, and correlated with proper models. The density declines slightly while the viscosity decreases greatly with the increase of temperature. It is effective to lessen the viscosities of hybrid absorbents as the increase of [Emim][Ac] concentration and decrease of PZ concentration with constant water content, and densities are vice versa. Solubilities of CO 2 in hybrid absorbents at T = 313.15 K to 343.15 K were measured by using an isothermal synthetic method under pressures of 0 MPa to 1.0 MPa. The results show that solubilities ascend with a decrease of temperature and increase of pressure. The addition of PZ highly improves the absorption ability of hybrid absorbent, while [Emim][Ac] has little effect on the CO 2 absorption ability of a highly concentrated PZ aqueous solution. Furthermore, CO 2 loading of 0.3 PZ + 0.1 [Emim][Ac] + 0.6 H 2 O is superior when it is compared with literature data, showing it is a potential CO 2 absorbent deserving further research. The viscosity of the hybrid absorbent is much lower than that of pure [Emim][Ac], which improves the practical significance of hybrid absorbents.