Adsorption of non-swelling vapours on the surface of cellulose

Abstract

Isotherms have been obtained for the sorption of n-decane, 1,4-dioxan and a number of alkan-1-ols on cotton and ramie fibres at several temperatures, using the gas chromatographic “peak maxima” elution method. The predominant sorption mechanism is concluded to be surface adsorption, and the B.E.T. monolayer capacities, Γ_m, are reported. For Γ < 2Γ_m, the Polanyi adsorption potential of the cellulose surface decreases in the order alkan-1-ols > dioxan > decane. Variations of the partial molar enthalpies and entropies with surface coverage are interpreted in terms of sorbate-sorbent and sorbate-sorbate interactions. In addition, both the thermodynamic parameters and a Frenkel–Halsey–Hill treatment indicate that the adsorbed phase of decane is liquid-like at coverages above 1.5Γ_m while, for butan-1-ol and dioxan, liquid-like behaviour does not appear until at least 2.5Γ_m.