Osmotic properties of binary mixtures of 1-butyl-1-methylpyrrolidinium iodide and water

Abstract

In this work the osmotic properties of the binary mixture of an ionic liquid (IL) and water were reported, by using the vapour pressure osmometry (VPO) technique. We have used 1-butyl-1-methylpyrrolidinium iodide as ionic liquid. We have measured the osmotic coefficients of the above IL–water binary mixture at three different temperatures: 313.15, 323.15 and 328.15K. We have calculated several parameters related to vapour–liquid equilibria, such as the activity of water in the IL–water binary mixture and the depression of vapour pressure of water in the mixture. The Archer extension of Pitzer model was used to correlate the experimental osmotic coefficients with molality of the solution. The parameter of this Archer extension of Pitzer model was estimated from this correlation. We have used the pseudophase separation model on the experimental osmotic coefficient value to estimate the critical micellar concentration (cmc) of 1-butyl-1-methylpyrrolidinium iodide in water.