Single-phase limit for mixtures of tri-n-butyl phosphate plus CO2 and bis(2-ethylhexyl)phosphoric acid plus CO2

With a high-pressure variable-volume view cell, the single-phase limit for binary mixtures of tri-n-butyl phosphate (TBP) + CO2 and bis(2-ethylhexyl)p hosphoric acid (DEHPA) + CO2 was determined at conditions applicable to sup ercritical fluid extraction of metal extractants (313.15-353.15 K, 4-30 MPa , 0-0.19 mole fraction of TBP, and 0-0.60 mole fraction of DEHPA). For each binary TBP + CO2 and DEHPA + CO2 system, the locus of the P-T-x limit of t he single-phase region was measured.