Separation of azeotropic organic liquid mixtures by pervaporation

Authors

  • Binay K. Dutta,

    1. Center for Chemical Technology, National Institute of Standards and Technology, Boulder, CO 80303
    Search for more papers by this author
    • B. K. Dutta is on leave from the Department of Chemical Engineering, Calcutta University, Calcutta 700 009, India.

  • Subhas K. Sikdar

    1. Center for Chemical Technology, National Institute of Standards and Technology, Boulder, CO 80303
    Search for more papers by this author

Abstract

We have shown that ionomeric membranes of perfluorosulfonic acid (PFSA) polymer allow selective pervaporation of polar organic compounds from their azeotropic mixtures with less polar compounds. A composite membrane of a thin PFSA polymer film, cast on a porous Teflon support, provided desirable permeant fluxes with good selectivity. Model binary azeotropes, composed of alcohols and hydrocarbons, were separated with total pervaporation fluxes of up to 9.5 kg/h·m2 using a stirred membrane permeation cell, the product side of which was exposed to vacuum. Fluxes increased with increasing alcohol content of the feed and with temperature. But the selectivity of the more permeating component remained reasonably constant around the azeotropic point and also over the range of temperature used in the study (25–55°C). Total pervaporation fluxes depended little on downstream pressure up to 6.66 kPa (50 torr). These separation data were explained by a mathematical model based on a solution-diffusion mechanism.

Ancillary