Pertraction of Np(IV) and Pu(IV) across a flat sheet supported liquid membrane containing two N-pivoted tripodal diglycolamides

Two tripodal diglycolamide (DGA) ligands with a central N atom, dissolved in a mixture of 5% isodecanol and 95% n-dodecane, were evaluated for the liquid-liquid extraction and the pertraction across a flat sheet PTFE membrane of tetravalent Np(IV) and Pu(IV) from dilute nitric acid medium. The ligand with an isopropyl group substituted at the inner amidic N atom of the tripodal DGA ligand (termed as i-Pr₃-TREN-DGA) showed higher extraction for the tetravalent actinides than the other ligand with no substitution but with a C3 instead of a C2 spacer (termed as TRPN-DGA). Although the extraction studies indicated higher extraction of Pu(IV) than Np(IV) for both the ligands, an unusual reversal in the pertraction efficiency across the supported liquid membrane was observed in nitric acid feeds. Transport parameters such as the diffusion coefficients (D_o) and the permeability coefficients (P) were determined for the metal ion transport with both the ligands. The liquid membranes membrane showed poor stability, limiting their long term use.