Abstract

Fundamental thermodynamic relations are formulated based on the equation of physical adsorption on microporous fractal solids, proposed previously and derived from the Polanyi-Dubinin theory of volume filling of micropores. A new adsorption isotherm and corresponding adsorption heat equations are verified using the experimental data published by Dubinin and Polstyanov of benzene and cyclohexane adsorption and adsorption heat on three microporous carbons. The obtained average correlation coefficients are compared with those from the original Dubinin-Astakhov (DA) equation. The correlation between the theoretical and experimental data is satisfactory, especially in the range of relative adsorptive pressures for which, following Stoeckli, the potential theory is accepted as appropriate. It is shown that, for nearly all the cases, micropore volumes are similar to those obtained from the original DA equation. Fractal dimensions calculated from adsorption data of both sorbates on the same carbon are practically equal and can be treated as constants that characterize the micropores of a solid. Average pore diameters, calculated from the obtained fractal dimensions, and also minimal and maximal pore widths are similar to those determined by the methods proposed by other authors, especially those obtained using the equation of McEnaney, developed from the analysis of SAXS data. The explanation of why the approximate adsorption isotherm equation proposed by Avnir and Jaroniec cannot be applied for the correct determination of a micropore fractal dimension is given.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.