Abstract:

The solubilities of CHI3(s) and CI4(s) in near-critical fluid SF6 have been spectrophotometrically determined. Due to the solubilities of the two solids in SF6, a new sampling and analytical procedure had to be developed to enable their measurement in the low solvent-density region, because they were below the detection limit of the previously developed spectrophotometric method. Isothermal solubility measurements were carried out under subcritical conditions in the dense liquid phase at temperature (302.20±0.01) K for CHI3 and (303.57±0.04) K for CI4, and under supercritical conditions at (322.76±0.03) K for CHI3 and (322.92±0.02) K for CI4; two isobaric runs were done for CHI3 at pressures of (3.818±0.003) MPa and (4.478±0.001) MPa. Solubilities depend strongly on p and T close to the thermodynamic state where the compressibility or thermal expansivity of the solvent pass, respectively, through a maximum. It is observed that CI4 is almost ten times less soluble than CHI3 in near-critical SF6. Moreover, the solubilities in SF6 are about ten times lower than in ethene. © 1993 Academic Press Ltd.