Adsorption properties of composite materials (LiCl + LiBr)/silica

This paper presents experimental data on synthesis and the phase composition of novel composites “(LiCl + LiBr) confined to the silica gel pores” as well as their sorption equilibrium with water and methanol vapour. Phase transformation of the composites during methanol sorption was characterized in situ by an X-ray diffraction analysis. The isobars of sorption on the composites were measured in the temperature range T = 303–383 K at the methanol and water pressure P = 107 and 13 mbar, respectively, using a thermo-gravimetric technique. It was shown that the formation of solid solutions of LiCl and LiBr took place in limited ranges of LiBr (CBr = 0–11 mol.%) and LiCl (CCl = 0–36 mol.%) content. These solutions absorbed water (methanol) at temperature that was intermediate between the individual solvation temperatures for confined LiCl and LiBr. In the composites with LiCl/LiBr molar ratio between the ranges of solubility a mixture of two solid solutions was formed. Each solution absorbed water (methanol) independently at a certain temperature. The use of the binary LiCl–LiBr system confined to the silica pores can be an effective tool for designing innovative materials with predetermined sorption properties.