Liquid–liquid equilibria of water/1-propanol/methyl ethyl ketone/potassium chloride

The liquid–liquid equilibrium of water/1-propanol/methyl ethyl ketone (MEK) at 25°C was significantly modified by the presence of dissolved potassium chloride. Water is salted out of the organic phase while MEK is more preferentially salted out of the aqueous phase than 1-propanol. These results in considerable enlargement of the two-phase region and enhancement of the extractive efficiency of MEK for the separation of 1-propanol from its aqueous mixture. Good correlation of the liquid–liquid equilibria (LLE) of the system in the presence of potassium chloride up to saturation was obtained with Tan’s modified NRTL phase model for multicomponent solute–solvent mixtures with the solute–solvent interaction parameters expressed as a third-order polynomial function in salt concentration. Similar to the observation reported for vapour–liquid equilibrium (VLE) of solvent–solute mixtures, salting-in and salting-out of the solvent components from the respective phases can be predicted according to the relative solute–solvent interaction parameters of the solvent components in the two phases.