969 (2002) 87–92 Journal of Chromatography A, www.elsevier.com / locate / chroma Determination of dependencies between the specific retention volumes and the parameters characterising adsorbent properties * Henryk Grajek , Zygfryd Witkiewicz Institute of Chemistry, Military Technical Academy, 00908 Warsaw, Poland Abstract Propane adsorption isotherms have been chromatographically determined on active carbon for different amounts of the injected adsorbate on column. The dependencies between the specific retention volume corrected to the standard temperature (273.15 K), V , and the molar differential work of adsorption, A, have been calculated on the basis of the propane g(273) isotherms and using the retention times of the peak maxima. The obtained equations: ln V 5 f (A) and dW/dA T, F 5 s d C g(273) 1 f ln V have been used to explain the dependency between the chromatographic peak profile and the distribution s d 2 g(273) function of pore volumes filled with propane with respect to the molar differential work of adsorption at different column temperatures (303–318 K).  2002 Published by Elsevier Science B.V. Keywords: Adsorption isotherms; Nonlinear chromatography; Retention volumes; Dubinin–Radushkevich equation; Thermo- dynamic parameters 1. Introduction the results obtained have involved conditions typical of nonideal, nonlinear chromatography process [6,7]. Gas chromatography is widely used, mainly as an Unlike the situation in static tests, an equilibrium analytical method. Applying chemical compounds state is not always attained during chromatographic with well defined physical properties as chromato- measurements of adsorption processes proceeding graphed substances (adsorbates), also enables this under dynamic conditions. Hence, there is still some technique to be used for investigating the properties doubt as to whether the results obtained on the basis of carbon and noncarbon adsorbents [1] and poly- of chromatographic measurements are plausible. The mers [2]. When used in this context, the technique is observed differences in the adsorption values have known as inverse gas chromatography. In terms of been linked to the similarity between the dimensions the conditions employed for the chromatographic of the adsorbate molecules and the entrances to the process, most studies have employed nonideal, linear micropores as being connected to their not being chromatography [3] and, more rarely, ideal, non- filled with the adsorbate in the chromatographic linear chromatography [4,5]. Only in a few papers process. This leads to the question as to whether the have adsorbent investigations been described where adsorption chromatographic tests can replace the static ones. The Dubinin–Radushkevich (DR) equation has been widely used for over 50 years for the analysis *Corresponding author. Fax: 148-22-666-9041. E-mail address: witkiew@wp.pl (H. Grajek). of vapour adsorption on micropore adsorbents. Its 0021-9673 / 02 / $ – see front matter  2002 Published by Elsevier Science B.V. PII: S0021-9673(02)00236-4