Analysis of Extraction behavior of Nd (III), Sm (III) and Eu (III) from EDTA solution using [TOA-D2] in kerosene: Thermophysical properties, Process parameters and Extraction mechanism

In this present investigation, the solvent extraction of Nd (III), Sm (III) and Eu (III) by using a bifunctional ionic liquid, tri-n-octyl amine-di-2-ethylhexyl phosphate ([TOA-D2]), as extractant has been performed in the presence of a complexing agent EDTA. Density, dielectric constant and refractive index of [TOA-D2] have been recorded in the temperature range 298 to 328 K. The extraction profile has been sketched by studying the impact of several influential parameters such as shaking time, pH of the aqueous feed, EDTA concentration, organic-to-aqueous phase volume ratio, diluents and temperature. The analysis of speciation diagram has been performed to find the available metal species under the existing experimental conditions. Cent percent stripping was achieved using either 0.8 M HCl or 0.8 M HNO3. The extraction efficiency did not change much even after four extraction-stripping cycles. The extracted species has been proposed as MHEDTA(TOA - D2) elucidated from slope analysis and speciation studies. FTIR spectra of the [TOA-D2] and extractant loaded with Nd (III), Sm (III) and Eu (III) have been recorded. The equilibrium data modeling also confirm the formation of solvated species with one extractant moiety. The predicted values of percentage extraction were found quite close to the experimental ones in case of involvement of one extractant species. This is also supported by small standard deviation values. The correlation between the observed variation in thermophysical properties and extraction trend has been established.