Solubility of Phenylphosphinic Acid in Supercritical Carbon Dioxide and the Influence of Methanol on the Solubility Behavior

The solubility of phenylphosphinic acid (PPA) was measured for the first time in supercritical carbon dioxide (SCCO2) at 313, 323, and 333 K with pressure ranging from 10-20 MPa using a dynamic flow technique. The solubility of PPA in neat SCCO2 ranged from 0.1 X 10(-5) to 18 X 10(-5) mol/mol. The influence of cosolvent, methanol, on solubility behavior was studied by measuring the solubility of PPA in SCCO2 + methanol medium (1 and 4 mol % methanol) at 313 and 323 K with pressure varying from 10-20 MPa. The highest solubility of PPA in the (SCCO2) + methanol mixture is 29.4 X 10(-4) mol/mol at 313 K and 20 MPa with a methanol composition of 4 mol %. The solubilities in neat SCCO2 were correlated using different semiempirical equations (Mendez Teja, Chrastil, and Bartle) with an average deviation of <10%. The solubility in the presence of methanol was correlated with four semiempirical/empirical models (modified Chrastil, modified Mendez Teja, Garlapati model, and Jouyban equation); among these models, Jouyban model resulted in better correlation with an average deviation of 5%.