Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

High-pressure phase behavior of six 1-decanol + n-tetradecane (solute + solute) mixtures in the presence of near- and supercritical CO2 (solvent) were experimentally studied between T = 300 K and T = 358 K using a visual static synthetic method. CO2 free or reduced n-tetradecane mass fractions (wc red) of 0.2405, 0.5000, 0.6399, 0.7698, 0.8162 and 0.9200 g.g 1 were selected for the mixtures and the solute (i.e. combined 1-decanol + n-tetradecane) mass fractions (ws) were varied between 0.015 g.g 1 and 0.65 g.g 1. The ternary system displayed temperature inversions at T = 308 K and T = 318 K for the mixture wc red = 0.2405 g.g 1. For all other wc red mixtures, an increase in temperature leads to an increase in pressure. A liquid-like (bubble-point) isotherm and a vapor-like (dew-point) isotherm were used to graphically define the size and range of isothermal cosolvency effects in the ternary system. The data were used to construct ternary phase diagrams from which cosolvency effects were observed for each set temperature. The large occurrence of cosolvency lead to the penetration of the liquid-liquid-gas (l1l2g) three-phase surface, forming a two-phase liquid-gas (l-g) hole between wc red = 0.7698 g.g 1 and wc red = 0.9200 g.g 1. Closed isobaric miscibility windows were inferred for wc red = 0.8162 g.g 1 to classify the ternary system as Class T-IV phase behavior.