Influence of the Exchangeable Cations of Montmorillonite on Gas Adsorptions

Abstract

Montmorillonites, before and after being saturated with Na+, K+, H+, Ca2+ and Al3+ ions, were studied to analyse their O2, N2, CO, CH4, C2H2 and CO2 gas retentions at 25 °C and 0.1 MPa, previously degassed at 100 °C. The homoionic-montmorillonites were characterized by interlayer spacing measurements and BET surface area. The levels of gas adsorptions for C2H2 (0.184–0.218 mmolg−1) and CO2 (0.170–0.208 mmolg−1) by original and homoionic montmorillonites were higher than those for N2 (0.068–0.074 mmolg−1), O2 (0.070-0.076 mmolg−1), CO (0.070–0.080 mmolg−1) and CH4 (0.082–0.086 mmolg−1). The C2H2 and CO2 gas adsorptions by different cation-exchanged forms of montmorillonite follows the following order: H- > K- > Ca- > Al- > Na-montmorillonite. The ionic radius of the exchangeable cations, the interlayer separation and surface area of the montmorillonite influenced the gas adsorption.