Thermodynamic characteristics of the adsorption of benzene derivatives from water—organic eluents on porous graphite-like adsorbent under conditions of equilibrium HPLC

• Published in: Russian chemical bulletin Vol. 69; no. 5; pp. 909 - 919
• Main Authors: Yashkin, S. N., Yashkina, E. A., Svetlov, D. A., Solovova, N. V.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-05-2020; Springer Nature B.V
• Subjects: Acetonitrile; Adsorbates; Adsorbents; Adsorption; Benzene; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Compensation; Data acquisition; Derivatives; Eluents; Enthalpy; Entropy; Full Articles; Functional groups; Graphite; Hydrocarbons; Inorganic Chemistry; Methanol; Organic Chemistry; Parameters; Phase composition; Solvation; Surface chemistry; Thermodynamic equilibrium; Vapor phases; adsorption; benzene derivatives; enthalpy—entropy compensation; solvatation effects; graphite-like adsorbent Hypercarb; entropy of solvatation; HPLC; heat of adsorption; entropy of adsorption
• ISSN: 1066-5285; 1573-9171
• DOI: 10.1007/s11172-020-2848-x

Thermodynamic characteristics of the adsorption of benzene and its derivatives on the surface of a porous graphite-like Hypercarb adsorbent from binary polar eluents have been experimentally determined under the conditions of equilibrium HPLC at various temperatures. The retention on Hypercarb columns is generally maintained by non-specific intermolecular interactions with the flat graphite-like surface and depends on the size of their molecular area. The contributions of various functional groups to the heat and entropy of adsorption were determined. The influence of solvation effects on the values of adsorption parameters was demonstrated. The replacement of methanol in the mobile phase composition with acetonitrile leads to an increased influence of the solvatation effects, while for the water-acetonitrile eluent, there were no any observed correlations of parameters of the adsorption on Hypercarb from a water-methanol medium with the data acquired on gas phase adsorption on graphite. The entropy values of adsorbates in their solvated state have been for the first time determined for eluents of the different polarities and compared with the entropy values for the state of pure liquid, which allowed us to clarify the nature of solvatation of the considered compounds in the polar eluent. Using the adsorption of compounds at issue as an example, the effect of enthalpy-entropy compensation was investigated, and the values of compensation temperatures were estimated.