Evaluation of three novel benzene-centered tripodal diglycolamide ligands for the pertraction of americium(III) through flat sheet membranes for nuclear waste remediation applications

Three benzene-centered tripodal diglycolamide (Bz-T-DGA) ligands were evaluated for the pertraction of Am³⁺ across PTFE flat sheet membranes. The feed phase contained a tracer spiked nitric acid solution (3 M), while the receiver phase contained 1 M α-hydroxyisobutyric acid (AHIBA). The transport of Am³⁺ was quantitative with ligand L_I, with ethyl groups appended to the benzene ring at the 1,3,5-positions and two spacer atoms between the ring and the DGA group. Ligand L_III, with a butoxy tether between the ring and the DGA unit, displayed a much better transport efficiency than ligand L_II having an ethylamide linkage, although in both cases the transport rates are lower than that of L_I. The transport efficiency of the actinide ions was Am³⁺ > Pu⁴⁺ ≫ UO₂²⁺ suggesting that Am and Pu can be easily decontaminated from U in a mixture. The membrane stability was reasonably good with L_I, while it was poor for the other two ligands.