Complex phase equilibrium phenomena in fluid mixtures up to 2 GPa-cosvolency, holes, windows, closed loops, high-pressure immiscibility, barotropy, and related effects
Gm. Schneider et al., Complex phase equilibrium phenomena in fluid mixtures up to 2 GPa-cosvolency, holes, windows, closed loops, high-pressure immiscibility, barotropy, and related effects, IND ENG RES, 39(12), 2000, pp. 4476-4480
First, the most important experimental techniques are briefly reviewed, inc
luding the diamond anvil cell (DAC) technique. As a first example, it is de
monstrated that carefully selected type III carbon dioxide binaries exhibit
ing gas-gas-like fluid phase behavior can be combined to give a ternary sys
tem, which might show large cosolvency effects and, as a consequence, two-p
hase holes in the three-phase liquid-liquid-gas sm face and/or one-phase mi
scibility windows surrounded by heterogeneous states (e.g., carbon dioxide
+ 1-decanol + tetradecane). As a second example, type VI binary systems exh
ibiting closed immiscibility loops in isobaric temperature (composition) di
agrams are considered. With increasing pressure, such closed loops can shri
nk or even disappear completely (e.g., tetrahydrofuran + water); have a tub
e-like shape, often with a narrowing at medium pressures (e.g., 3-aminopent
ane + water); or even appear at high pressures only (so-called "high-pressu
re immiscibility", e.g., tetra-n-butylammonium bromide + water). Finally, i
sopycnic and barotropic effects are discussed in relation to the phenomena
described above.