Journal zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA of Membrane Science, 55 (1991) 257-262 Elsevier Science Publishers B.V.. Amsterdam 251 Investigation of the separation factor between light and heavy water in the liquid/vapor membrane permeation process* Andrez G. Chmielewski** and Grazyna Zakrzewska-Trznadel Institute of Nuclear Chemistry and Technology, 03-195 Warszawa, Dorodna 16 (Poland) Nada R. Miljevic Boris Kidric Institute of Nuclear Science, Vinca, 11001 Belgrade, P.O. Box 522 (Yugoslavia) W. Alexander van Hook** Chemistry Department, University of Tennessee, Knoxville, Tennessee 37996-1600 (U.S.A.) (Received June 8,1989; accepted in revised form December l&1989) zyxwvutsrqponmlkjihgfedcb A bstract Results of measurements of the separation factor between light and heavy water during mem- brane permeation are presented. In these experiments the membrane separated the liquid and vapor phases. Measurements were made between 20 and 90°C at downstream pressures (vapor chamber) of 6,160 and 460 Torr. Two different cellulosic membranes, “Cuprophan 150 M” and “Tomofan I”, were employed. The isotopic composition of hydrogen in the two phases was ana- lyzed by isotope ratio mass spectrometry. The separation factors, (Y, and their temperature depen- dences for both membranes are reported. Keywords: Pervaporation; water sorption and diffusion; solubility and partitioning; cellulosic membranes 1. Introduction The separation factor for a membrane is conveniently defined in terms of eqn. (1): a= (D/H)*/ (D/H), (1) Here A and B denote the enriched and depleted streams, and D and H signify the respective deuterium and hydrogen analyses. In the membrane fractiona- tion experiments described below, stream A was a liquid phase feed solution slightly enriched in heavy water (to ca. 200 ppm of D ) and B was a (vapor phase) permeate. Pervaporation [ 1,2] is a membrane process in which a phase transition takes place. In this case the liquid mixture is in direct contact with *Paper presented at the International Symposium on Membranes for Gas and Vapor Separation, Suzdal, U.S.S.R., February 27-March 5,1989. **To whom correspondence should be addressed. 0376-1388/91/$03.50 0 1991- Elsevier Science Publishers B.V.