Considerations about the correct evaluation of sorption thermodynamic parameters from equilibrium isotherms

This is a comparative analysis of popular methods currently in use to derive sorption thermodynamic parameters from temperature dependence of sorption isotherms. It is emphasized that the standard and isosteric thermodynamic parameters have sharply different meanings. Moreover, it is shown with examples how the sorption model adopted conditions the standard state and consequently the value of ΔG° and ΔS°. These trivial but often neglected aspects should carefully be considered when comparing thermodynamic parameters from different literature sources. An effort by the scientific community is needed to define criteria for the choice of the standard state in sorption processes.

• Different methods to derive sorption thermodynamic parameters have been discussed.
• ΔG° and, ΔS° values depend on the selected standard states.
• Isosteric heat values help in evaluating the applicability of the sorption models.