Wetting, swelling and sediment volumes of organophilic clays

Abstract

Sediment volumes and basal spacings of hydrophilic and organophilic montmorillonites were measured in parallel with adsorption isotherms and immersion enthalpies of these clays. The sediment volumes of hydrophilic montmorillonites in apolar media grow parallel with the amount of adsorbed water and with the water—organic liquid interfacial tension. From excess isotherms of benzene—alcohol mixtures on organophilic clays, the adsorption capacities for the apolar and polar components are given separately. By measuring the basal spacings, the distribution of the interlamellar liquid between the adsorption and the swelling phases is calculated. The total heat of immersion measured by microcalorimetric method is composed of exothermic wetting and endothermic swelling heats. For swelling, work should be directed against the forces acting between the layers, and entropy changes play a decisive role. Sediment volumes of organophilic montmorillonites change with adsorption and swelling in a complex manner.