Complexation and back extraction of various metals by water-soluble diglycolamide

Water-soluble ligands, N,N,N′,N′-tetramethyldiglycolamide (TMDGA), N,N,N′,N′-tetraethyldiglycolamide (TEDGA), N,N,N′,N′-tetrapropyldiglycolamide (TPDGA) and N,N- dipropyldiglycolamic acid (DPDGAc) were prepared and their abilities to complex with and to back-extract the metal cations were investigated. These results indicate that the DGA series and DPDGAc have a stronger complexing ability with Am(III) and Pu(IV) than comparable carboxylic and aminopolycarboxylic acids. Among these ligands, the trend of the strength of their complexing ability is TPDGA - TEDGA > TMDGA - DPDGAc. TPDGA has significant loss to the extraction solvent due to its high hydrophobicity. It is evident from the present work that TEDGA is the best reagent for the reverse-extraction of not only An(III), (IV) but also Ca(II), Sc(III), Y(III), Zr(IV), La(III), Hf(IV), and Bi(III). 2007