Extraction of lanthanide ions with N,N,N′,N′-tetrabutyl-3-oxa-diglycolamide from nitric acid media

Extractability and extraction mechanism of lanthanide ions were investigated by using a new extractant, N,N,N′,N′-tetrabutyl-3-oxa-diglycolamide (TBDGA), in toluene from nitric acid media. The effects of HNO₃ and TBDGA concentrations, and temperature, on extraction of lanthanide ions were studied. Stoichiometries of the main extracted species were HNO₃·TBDGA and M(NO₃)₃-3TBDGA (M = Er, Dy, Tb, Gd, La, Ce, Nd, Sm and Eu). The extracted species for metal ions were established to be ionic complex. In this complex, nitrate anion was not coordinated to the central ion. The extraction pattern increased gradually across the lanthanide ions series, showing enhanced affinity of TBDGA toward heavy lanthanide ions. Thermodynamic parameters were investigated for the exothermic extraction reaction. (authors)