Trihexyl(tetradecyl)phosphonium bromide: Liquid density, surface tension and solubility of carbondioxide

Vapour–liquid equilibria of ionic liquid – carbon dioxide systems, as well as thermo-physical properties of the system components are very important to design and optimize various separation and reaction processes. In this work the solubility of carbon dioxide (CO2) in trihexyl(tetradecyl)phosphonium bromide([THTDP][Br]) was measured using a high-pressure sapphire cell, in pressure range of 8–22 MPa and at two temperatures, 313.2 K and 323.2 K. The thermophysical properties, namely liquid density and surface tension of the ionic liquid were determined in temperature range of 293.2–343.2 K.The densities predicted by Gardas and Coutinho model showed good agreement with the experimental data obtained in this work. The critical temperature of [THTDP][Br] was estimated using the Eötvos correlation. Moreover, these experimental and calculated data gave an opportunity to apply the Peng–Robinson equation of state (PR-EoS) in order to predict/correlate the behaviour of the studied system, ([THTDP][Br] + CO2) with satisfactory results.