The isobaric decrease of the solubility of liquid solutes in SCCO2
as temperature increases is commonly observed in many systems
of interest in SCCO2 fractionation applications, depending on
the pressure–temperature operating ranges. Besides ethyl esters,
this phenomenon has been observed in phase equilibrium studies
for several other liquid solutes, such as fatty acids and glycerides
[35], citrus oil terpenic components [36–38], lemon oil [39],
crude palm oil and soy oil deodorizer distillate [40], and liquid
perfluoropolyethers [41]. In the case of FOEE, this effect is very
strong, especially between 42 ◦C and 70 ◦C, and can be conveniently
exploited to generate a large internal reflux inside a multistage
separation column, operating at increased temperature at the top
stage.