Solubility and solution enthalpy of a cesium-selective calixarene in supercritical carbon dioxide

Adrien Dartiguelongue (1, 2) , Antoine Leybros (1, 2) , Agnès Grandjean (1, 2)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 SPDE - Service des Procedés de Décontamination et d'Enrobage des Déchets

This paper investigates the solubility of the cesium-selective extractant 25,27-Bis(1-octyloxy)calix[4]arene-crown-6, 1,3-alternate (CalixOctyl) in supercritical CO$_2$ (SC-CO$_2$). A dynamic setup with a solvent loop was used, avoiding any plugging of the solute and allowing precise quantification by UV/visible spectrophotometry. The solubility measurements were carried out between 10.3 and 27.4 MPa at 314, 324 and 334 K. The solubility of CalixOctyl in SC-CO$_2$ ranged from (0.20 $\pm$ 0.02)·10$^{−6}$ mol·mol$^{−1}$ at 334 K and 10.4 MPa to (72.78 $\pm$ 0.31)·10$^{−6}$ mol·mol$^{−1}$ at 324 K and 27.4 MPa, approximately 100 times higher than that of simple $p-t$-butylcalix[4,6,8]arenes and calix[4]arene. The solution enthalpy of CalixOctyl in SC-CO$_2$ was also studied. The heat flow during solubilization at 24.0 MPa and 314, 324 and 334 K was measured by differential scanning calorimetry. The temperature dependence of the solution enthalpy and its extrapolation to any pressure are discussed.

Mots clés: CalixOctyl; cesium extraction; solution enthalpy; Supercritical CO2; solubility

Domaines: Physique Nucléaire Théorique [nucl-th]; Physique Nucléaire Expérimentale [nucl-ex]

Adrien Dartiguelongue, Antoine Leybros, Agnès Grandjean. Solubility and solution enthalpy of a cesium-selective calixarene in supercritical carbon dioxide. Journal of Supercritical Fluids, 2017, 125, pp.42-49. ⟨10.1016/j.supflu.2017.01.017⟩. ⟨cea-02380589⟩