INFLUENCE OF SURFACE ENERGETICAL HETEROGENEITY ON CAPILLARY CONDENSATION IN SLIT-LIKE PORES - A MONTE-CARLO STUDY

The results of a Monte Carlo simulation of capillary condensation in slit-like model pores with walls composed of parallel strips characterized by different surface potential strengths are presented. The mechanism of capillary condensation in such nonuniform pores is discussed and compared with the results obtained by other methods. It is demonstrated that for sufficiently high differences in the gas-solid interactions in different parts of a pore, the formation of a liquid phase proceeds in two steps, corresponding to condensation in different parts of the pore. The first step, precondensation, leads to the formation of a thin liquid layer over the pore part with higher energy of adsorption. The second step of capillary condensation appears to be very similar to the condensation observed in pores closed at one end.