abstract
Ionic liquids are attracting great attention nowadays due to their interesting properties which make them useful in a broad range of applications including reaction media or separation/capture of environmentally hazardous gases such as carbon dioxide. In many cases, for practical and/or economical reasons, the use of aqueous solutions of Its would be preferable to their use as pure compounds. In this work, high pressure equilibrium data for the {carbon dioxide (CO(2))+tri-iso-butyl(rnethyl)phosphonium tosylate [iBu(3)MeP][TOS] + water system were measured at temperatures ranging from (276 to 370) K and pressures up to 100 MPa. Measurements were performed using a high-pressure cell with a sapphire window that allows direct observation of the liquid-vapour transition. Mixtures with different IL concentrations were studied in order to check the influence of the amount of IL on the solubility of CO(2) in the aqueous mixture. The results show that the presence of IL enhances the solubility of CO(2) in the (IL + water) system revealing a salting-in effect of the IL on the solubility of CO(2). The appearance of a three phase region was observed for IL concentrations higher than 4 mol% of IL in water when working at pressures between 4 and 8 MPa and temperatures between (280 and 305) K. In this range, the upper limit of the VLE region observed is shown to increase with the temperature being almost independent of the IL initial concentration in the mixture. (C) 2008 Elsevier Ltd. All rights reserved.
keywords
IONIC LIQUID/ORGANIC MIXTURES; PHASE-BEHAVIOR; PARTITION-COEFFICIENT; ELEVATED PRESSURES; GAS SOLUBILITY; LIQUIDS; CO2; HEXAFLUOROPHOSPHATE; SEPARATION; SOLVENTS
subject category
Thermodynamics; Chemistry
authors
Ventura, SPM; Pauly, J; Daridon, JL; da Silva, JAL; Marrucho, IM; Dias, AMA; Coutinho, JAP
our authors
Sónia Patrícia Marques Ventura
Assistant Professoracknowledgements
This work was supported by FEDER and Fundacao para a Ciencia e a Tecnologia (Project POCI/EQU/58152/2004). S.P.M. Ventura thanks CICECO, University of Aveiro, for a young researcher grant. The authors acknowledge the help of P.J. Carvalho on the viscosity measurements.