Simplified Crossover Droplet Model for Adsorption of Critical and Supercritical Fluids in Slit Nano-Pores

摘要

In this work, we present a simplified crossover droplet (SCD) model for of pure fluids at a flat solid-liquid interface and in slit pores. The SCD contains size pore, L, as a parameter and at L ζ_b (where ζ_b is a bulk correlation length) is transformed into the generalized crossover model for the excess adsorption in semi-infinite systems. With L=50 nm, the SCD model reproduces all available experimental data for SF_6/graphite, including the critical isochore data at τ → 0, within experimental accuracy. The SCD model also yields excellent description of critical adsorption data for COC_2/silica gel system. Application of the SCD model to the description of experimental adsorption data for N_2O/silicia gel system is also discussed.