| Popis: |
A number of different “heats of adsorption” measured in flow calorimetric experiments are related to one another, to other common measurements of heat of adsorption, and to the theoretical surface enthalpy. Theoretical equations have been developed to show the relationships between the values obtained by different methods. These equations apply to the adsorption on solids from binary liquid solutions. The differences between measurements are attributed to the following three effects: (1) mixing between the surface and the bulk phase, (2) mixing in the interface between solutions, and (3) kinetic effects. To account for effect 1, use of our equations requires knowledge of the adsorption isotherm and bulk heats of dilution. Effect 2 requires bulk heats of dilution plus the concentration profile between the “replacing” and “replaced” solution both before and after the flow calorimetry experiment. A method is suggested to test kinetic effects. We have tested our theory against literature data and some of our own. The theory satisfactorily predicts the measured differences between different experimental protocols. |
