Liquid–Liquid Extraction of Actinides from Nitric Acid Feeds Using Two Hexa-n-alkylnitrilotriacetamides

ABSTRACT

Solutions of two nitrilotriacetamide (NTA) ligands, viz., N,N,N’,N’,N”,N”-hexa-n-butylnitrilotriacetamide (HBNTA) and N,N,N’,N’,N”,N”-hexa-n-hexylnitrilotriacetamide (HHNTA) in 20% isodecanol–80% n-dodecane were employed for the extraction of U(VI), Np(IV), Pu(IV), and Am(III) from nitric acid feed solutions. Limitations of ligand solubility and third-phase formation when contacted with nitric acid solutions led to the choice of the diluent composition of 20% isodecanol and 80% n-dodecane. The results of the solvent extraction studies indicated poor extraction of the metal ions with HBNTA as compared to that with HHNTA as the extractant and hence, major part of this work involved HHNTA. Slope analysis suggested extraction of 1:1 (ML) species with Np(IV) and Pu(IV) at 3 M HNO₃ and mixed 1:2 (ML₂) and 1:3 (ML₃) species with U(VI) at pH 2. At 0.5 M HNO₃, the observed trend for extraction was Pu(IV) > Np(IV) >> Am(III) > U(VI).

KEYWORDS:

• Nitrilotriacetamide
• actinides
• solvent extraction
• separation

Acknowledgments

AK, TPV, and DBS wish to thank Mr. K.V. Ravi, Chief Executive, Nuclear Recycles Board for his constant encouragement, while BNM and PKM acknowledge Dr. P.K. Pujari, Head, Radiochemistry Division and Director, Radiochemistry and Isotope Group, BARC for his keen interest.

Disclosure statement

There are no conflicts of interest to declare.