Differential heats of adsorption of water vapors on the lithium form of clinoptilolite
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The maximum possible lithium form of clinoptilolite (K1) with an ion-exchange capacity of 2.3 mEq/g, corresponding to 85% Kl in nature, was prepared. The isotherm of adsorption of water vapors on LiKl at 25°C in the region of maximally low equilibrium pressures (10−10 torr) was calculated by the adsorption-isostere method and permits determining the complete thermodynamic functions of the system. The adsorption isotherm is completely described by the two-term equation from the theory of volume filling of micropores (TVFM). The wavy-stepwise shape of the curve of the heat of adsorption permitted establishing the stoichiometric correlation between the adsorption values and concentration of Li+ in LiKl. The energy of the Li+-OH2 adsorption complex is 97 kJ/mole for a zero degree of filling. The integral average molar entropy of adsorption is 20 J/(mole·K) less than the entropy of a normal liquid. The state of the H2O molecules in LiKl is ice-like.
KeywordsEntropy Water Vapor Adsorption Isotherm Thermodynamic Function Clinoptilolite
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