Temperature dependence of thermo-osmosis. A solution model

Abstract

A model has been proposed to study the temperature dependence of the permeation and the thermo-osmosis of a single substance through a membrane. The model takes into account the dependence on temperature of the molar volume of permeant, the enthalpy of transfer from the permeant phase to the membrane phase, and the phenomenological coefficients defined for a thin slab of membrane. The empirical phenomenological coefficients, permeability and thermo-osmotic permeability of the discontinuous system are obtained as integral formulae of the abovementioned properties. A method has been proposed to evaluate the transport phenomenological coefficients, true for a thin slab of membrane, from the experimental data of the enthalpies of dissolution of permeant in the membrane, of the permeability and of the thermo-osmotic permeability. The experimental data reported in the literature and those obtained from our previous work fit well with this theoretical model, but it is recognized that new experimental results are needed to apply this model completely.