Membranes of a copolymer of vinylpyridine and styrene are more permeable to hydrogen chloride dissolved in water than to other dissolved salts. The hydrogen chloride flux varies linearly with the hydrogen chloride concentration difference across the membrane, which is inconsistent with facilitated diffusion. The membrane apparently operates by a diffusion-solubility mechanism, with a diffusion coefficient around 2.2 × 10-10cm2/sec and a partition coefficient of 450. Earlier claims of facilitated diffusion in this solid membrane probably result from artifacts like lag times and like chemical degradation of the membrane, though they may also result from relaxation of copolymer chains.
Bibliographical noteFunding Information:
This work was largely supported by the National Science Foundation (CTS 89-12634). Other support came from the Hoechst Ce-lanese Corporation, and from the University of Minnesota Graduate School. E.L. Cussler held the Amundson Professorship while on sabbatical leave at the Massachusetts Institute of Technology, where he was graciously received.
- carrier mediated diffusion
- facilitated transport