Systematic Modifications of BTP-type Ligands and Effects on the Separation of Trivalent Lanthanides and Actinides

In this study the separation of Am(III) from Eu(III) in nitric acid using two BTP-type N-donor ligands, 2,6-bis(6-ethyl-1,2–diazine-3-yl)pyridine (Et-BDP) and 2,6-bis(4-npropyl-2,3,5,6-tetrazine-1-yl)pyridine (nPr-tetrazine) is presented. The extraction and separation properties of both ligands are tested by two phase liquid-liquid extraction at different acid concentrations. In contrast to nPr-BTP the bisdiazinyl ligand Et-BDP is prone to protonation at nitric acid concentrations of 0.2 M and higher. A separation factor of SFAm/Eu ≈ 5 is obtained using Et-BDP as extracting ligand and with nPr-tetrazine a SFAm/Eu of 9.1 is realized. Hereby 2-bromodecanoic acid as lipophilic anion source is needed.