SORPTION AND DIFFUSIVITY MEASUREMENTS OF CYCLOHEXANE PLUS BENZENE AND CYCLOHEXENE PLUS TOLUENE MIXTURES IN POLYURETHANE MEMBRANES - MODEL-CALCULATIONS OF THE PERVAPORATION PROCESS

Data of vapor sorption measurements of the solvents cyclohexane, benzene and toluene in polyurethane (PU) membranes are presented. Vapour sorption isotherms have been obtained from equilibrium data. Kinetic sorption data have been used for determining diffusion coefficients of the solvents in the membrane material. Further measurements of the individual solubilities of liquid cyclohexane+benzene and cyclohexane+toluene mixture components in PU-membrane material have been carried out using the so-called swelling density method and a gaschromatographic analytical method. Vapor sorption isotherms as well as solubility data of the liquid mixtures can be described with the UNIQUAC-model in good agreement with experiments. All results obtained for solubilities and diffusion coefficients are used for predictive calculations of fluxes and separation diagrams in the pervaporation process of cyclohexane + benzene and cyclohexane + toluene mixtures through PU-membranes. The basis of these model calculations is the solution-diffusion model. Predicted results of pervaporation agree well with experimental data taken from literature provided diffusion coupling of the components permeating the membrane is taken into account.