Vapor-Phase Sorption Kinetics for Tetrahydrofuran, Tetrahydropyran, and 1,4-Dioxan by Al3+- and Cr3+-Exchanged Montmorillonite

C. Breen1, A. T. Deane and J. J. Flynn
School of Chemical Sciences, National Institute for Higher Education Glasnevin, Dublin 9, Ireland
1 Current address: Chemistry Department, Sheffield City Polytechnic, Pond Street, Sheffield S1 1WB, United Kingdom.

Abstract: The rate of vapor-phase sorption of tetrahydrofuran (THF), tetrahydropyran (THP), and 1,4-dioxan (DIOX) onto a Wyoming montmorillonite saturated with Al3+ or Cr3+ has been studied by isothermal gravimetry in the temperature range 18° to 105°C using samples of different weights and grain-size distributions. The rate of sorption for all the cyclic ethers increased with decreasing sample and grain size, demonstrating that inter-, rather than intraparticle mass transfer was rate-determining. Optimization of the sample parameters (2 mg sample of <45-µm grain size, pretreated at 120°C yielded integral diffusion coefficients at 18°C of 0.5 × 10−14 m2/s for DIOX for the Cr3+-clay to 3.5 × 10−4 m2/s for THF for the Al3+-clay; however, no temperature or cationic dependence of the cyclic ether uptake was observed. In general, the rate of sorption of the cyclic ethers increased as THF ≥ THP > DIOX indicating that the sorption rate of THF and THP was dependent on concentration or that DIOX sorption was retarded by bidentate coordination to aluminum ions at the edges of the clay platelets.

Key Words: Adsorption • Cyclic ethers • Diffusion • Montmorillonite • Vapor

Clays and Clay Minerals; October 1987 v. 35; no. 5; p. 343-346; DOI: 10.1346/CCMN.1987.0350503
© 1987, The Clay Minerals Society
Clay Minerals Society (www.clays.org)