Description and approximation of mass-transfer in pervaporation process on the base of nonequilibrium thermodynamics approach.

Pervaporation is a nonequilibrium membrane process. The pressure or chemical potential gradients are the factors that determine the irreversibility of membrane transfer in pervaporation. In this work, we consider the opportunity of describing and approximating pervaporation data using a nonequilibrium thermodynamic approach. Pervaporation curves for a wide range of feed solution concentrations have been built based on data on a few binary systems. The thermodynamic properties of feed solutions were calculated using vapor–liquid equilibrium data. The sigmoidal Boltzmann function, Gauss function and Praal equation were used to approximate vapor–liquid equilibrium data. Approbation of proposed variants in the construction of pervaporation curves was carried out for five binary systems: ethanol–water at 50°С and 60°С, acetone–water at 30°С, benzene–cyclohexane at 25°С, methanol–methyl-tert-butyl ether at 25°С, and ethanol–butanone at 55°С. The agreement between calculation results and experimental data is in the limits which are sufficient for applied estimations. [ABSTRACT FROM AUTHOR]