抄録
The extraction equilibrium of Eu(NO3)3 from aqueous solution into Versatic acid 911-benzene solution was studied. The vapor pressure of benzene in this binary organic solution was measured by the transpiration method at 15, 25 and 35°C. And the activity coefficient of Versatic acid 911 in this solution was calculated by the Gibbs-Duhem equation.
On the other hand, the distribution equilibrium of Eu3+ ion between aqueous and organic solutions was measured at the above-mentioned temperatures by using a mixture of Eu152 and Eu154 as the radioactive tracer. The composition of extracted species and the equilibrium constant of extraction were determined by taking the calculated values of activity of Versatic acid 911 into consideration. Furthermore, enthalpy and entropy changes of the extraction were calculated in the following way:
Extracted species: EuR3·4RH
ΔH°=15.4(kcal/mol) ΔS°=37.8(e.u.)
