ASSOCIATIVE REPLICA ORNSTEIN-ZERNIKE EQUATIONS AND THE STRUCTURE OF CHEMICALLY ASSOCIATING FLUIDS IN DISORDERED POROUS-MEDIA

A two-dimensional model for a chemically associating fluid adsorbed in a disordered porous media has been investigated. The model is studied by means of the associative Replica Ornstein-Zernike equations, with Percus-Yevick and hypernetted chain approximations, extended for assoc iating fluids. The effects of disordered media density and strength of association interaction on the adsorption isotherms and structural pr operties of adsorbed fluid are explored. To investigate the effect of association interaction on the liquid-gas phase transition, the additi onal out-core interparticle interaction in the form of square-well att raction is included. This term is considered ih the mean field approxi mation. It permits us to analyze qualitative trends of the behavior of the critical density and temperature dependence on the combined effec t of association and of quenched disorder in the model of dimerizing d iscs with square-well attraction. Our preliminary conclusion concernin g this unexplored problem is that the presence of disorder and of asso ciation have opposite effect on the critical temperature. Manipulating the matrix density and bonding between particles may keep almost unal tered the critical temperature. (C) 1998 Elsevier Science B.V.