Thermochromatography / Gas-solid chromatography I Chromatographie Zone Profites /Monte Carlo simulations fEnthalpy of adsorptionSummaiy A simplifled microscopic model is proposed for the gas-solid thermochromatography in open columns with the laminar flow of the carrier gas. This model describes the downstream migration of a sample molecule as a rather small number of some effective random displacements, and sequences of adsorptiondesorption events that occur without changing the coordinates. The relevant probability density distributions are thereby derived, Based on this model, a versatile Computer program has been developed for simulating the profiles of thermochromatographic zones by employing the Monte Carlo technique. Some results of these simulations are given to demonstrate the influence of several parameters on the zone profile.

By the experimental measurement of deposition temperatures as a function of time and/or the gas flow rate in a column with constant negative longitudinal temperature gradient one can evaluate the differential molar standard enthalpies and entropies of adsorption by the second law method. On the basis of model conceptions with respect to the adsorbed state the differential molar standard adsorption entropy can be estimated. This allows the enthalpy of adsorption to be evaluated only from the deposition temperature by a quasi-third law method. Pertinent formulae are deduced.

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