Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

We report experimental results for the melting of eutectic mixtures confined in nanoporous matrices. Dielectric relaxation spectroscopy and differential scanning calorimetry were used to determine the solid/liquid phase diagram of C6H4Br2/CCl4 mixtures confined in controlled pore glasses (CPG) with an average pore diameter of 7.5 nm, and C6H5Br/CCl4 mixtures confined in activated carbon fibers (ACF) with a mean pore diameter of 1.4 nm. We find that the phase diagram of the confined mixtures are of the same type as that for the bulk mixture (eutectic). However, in the case of mixtures in carbon nanopores the solid/liquid coexistence lines are located at higher temperatures than for the bulk mixtures, whereas they are at lower temperatures than the bulk for mixtures confined in silica pores. These results are compared with those previously obtained for azeotropic mixtures in ACF. The results suggest that the melting temperatures, Tmp, of confined mixtures decrease relative to the bulk when the fluid wall interactions are weaker than the fluid fluid interaction (silica glasses), and increase in the case of fluid wall interactions that are stronger than the fluid fluid interaction (nanoporous carbons).