THERMODYNAMICS OF FLUIDS IN QUENCHED DISORDERED MATRICES

Using the replica method, we derive the thermodynamic relations for a fluid in equilibrium with a quenched porous matrix. In particular, the appropriate Gibbs-Duhem equation is obtained as well as the equivalen ce between grand canonical and canonical ensembles. The exact compress iblity and virial equations are derived. Whereas the compressibility e quation remains a direct and practical way to obtain the adsorption is otherm, the virial equation involves terms which do not relate easily to the properties of the fluid/matrix system. This explains the incons istency between previous theoretical predictions and computer simulati on results.