Sorption Isotherms of Aromatic Compounds in Organophilic Polymer Membranes Used in Pervaporation

The sorption isotherms of seven aromatic compounds and some mixtures of them in soft-segment elastomeric polyether-polyamide block-copolymer (PEBA) have been measured at 25 and 50°C using UV-VIS spectroscopic and gas chromatographic analysis. The solubility in PEBA depends significantly on the molecular size of the aromatic compound. Sorption coefficients have been determined. The temperature dependence of the sorption coefficient has been used to determine also the sorption enthalpy of the aromatic compounds from the aqueous solution to the polymer phase. Ternary mixtures consisting of two aromatics in dilute aqueous solution have been investigated in order to study possible synergistic solubility effects. The sorption coefficients can be used for the prediction of the permeation rate across the nonporous PEBA membrane in the so-called pervaporation process. An example is presented.