Investigations on synthesis, coordination behavior and actinide recovery of unexplored dicyclohexylphosphinic acid

Abstract

Dicyclohexylphosphinic acid (DcyHPA) and some of its metal complexes with lanthanides (La, Ce, Gd, Sm and Nd) and actinides (U and Th) were prepared and subsequently the structural composition was elucidated. The single crystal XRD data and theoretical analysis revealed that the ligand (DcyHPA) exists as a dimer in solid state. DcyHPA showed dual nature for the extraction of U(VI), Th(IV) and Am(III) from nitric acid medium i.e. at lower acidity, the ligand behaves as an acidic extractant and extracted the metal through cation exchange mechanism while solvation mechanism played a major role for extraction at higher acidity. Additionally, density functional theory (DFT) calculations were demonstrated to understand the electronic structure of thorium-DcyHPA metal complex formed during the extraction process.