Adsorption of cyclic amines on graphitized thermal carbon black

Thermodynamic characteristics of adsorption (TCA) for aniline and its methyl derivatives on the surface of graphitized thermal carbon black (GTC, Carbopack C HT trade mark) were determined using equilibrium gas adsorption chromatography in the range of the lowest adsorbate concentrations in the gas phase. A series of relationships relating the TCA of the studied amines to their physicochemical parameters was obtained. The theoretical values of entropy of adsorption were calculated in the framework of the model of two-dimensional ideal gas and compared with the corresponding experimental values, which allowed one to reveal specific features of the molecular structure of the adsorbates. A similarity between the thermal component of entropy of the studied compounds in the adsorbed state and that of the entropy of the pure liquid adsorbates made it possible to refine the physical state and mobility of the adsorbate molecules in the force field of the adsorbent. The regression equation relating the heats of adsorption on the GTC to such molecular constants of adsorbates as polarizability, molecular surface area, and molecular weight were proposed for the first time. A high predictive power of the equations derived in the work for the preliminary estimation of the adsorption characteristics of alkylanilines and alkylbenzenes on the GTC was shown.