Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

Solubility of dialkylalkyl phosphonates in supercritical carbon dioxide: experimental and modeling approach

Pitchaiah, K. C., Brahmananda Rao, C. V. S., Sivaraman, N., Joseph, M., Brondz, I.[Ilia]
Fluid Phase Equilib. 2017, 435, 88-97
ABSTRACT
Dialkylalkyl phosphonates have found renewed interest in the selective extraction of actinides from different matrices. In this context, two dialkylalkyl phosphonates, dibutylbutyl phosphonate (DBBP) and diamylamyl phosphonate (DAAP) were synthesised and their solubilities in supercritical carbon dioxide (SCCO2) medium were determined in the pressure range of 10 to 25 MPa at 313 to 333 K. Solubility studies were carried out to examine their utility as ligands during supercritical fluid extraction of actinides. Solubilities of dialkylalkyl phosphonates ranged from 0.06 to 0.12 mole fraction. Experimental solubilities were correlated using Mendez- Santiago, Chrastil, solution theory with Wilson activity coefficient model and association model based on van Laar activity coefficient model. Comparison among these models revealed that the association model with van Laar activity coefficient model provides better solubility predictions. SCCO2 containing DAAP was employed for the (i) selective extraction of uranium in the presence of simulated fission products and (ii) extraction of uranyl nitrate from acidic medium.
Compounds
# Formula Name
1 CO2 carbon dioxide
2 C12H27O3P dibutyl butanephosphonate
3 C15H33O3P dipentyl pentylphosphonate
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 2
  • 1
  • Mole fraction - 2 ; Fluid (supercritical or subcritical phases)
  • Temperature, K; Fluid (supercritical or subcritical phases)
  • Pressure, kPa; Fluid (supercritical or subcritical phases)
  • Fluid (supercritical or subcritical phases)
  • Crystal - 2
  • gravemetric
  • 15
  • POMD
  • 1
  • 3
  • Mole fraction - 3 ; Fluid (supercritical or subcritical phases)
  • Temperature, K; Fluid (supercritical or subcritical phases)
  • Pressure, kPa; Fluid (supercritical or subcritical phases)
  • Fluid (supercritical or subcritical phases)
  • Crystal - 3
  • gravemetric
  • 15