Pertraction of americium(III) through supported liquid membranes containing benzene-centered tripodal diglycolamides (Bz-T-DGA) as an extractant/carrier

Two novel benzene-centered tripodal diglycolamide (Bz-T-DGA) ligands with affinity for actinide ions were employed for the solvent extraction as well as flat sheet supported liquid membrane (SLM) transport of trivalent americium (Am³⁺), considered as one of the most important minor actinide ions in the high level waste (HLW). Bz-T-DGA ligands with isopentyl substituents and varying spacer lengths in the DGA arms, viz. methylene (TPAMTEB) and ethylene (TPAETEB) groups were employed for actinide extraction for possible application in nuclear waste remediation. With both the ligands, the extraction of Am³⁺ increased with the concentration of nitric acid (1–6 M HNO₃), the distribution ratio (D) values being 16.6 and 3.71 at 3 M HNO₃ and 35.1 and 44.4 at 6 M HNO₃ for 6.6 × 10⁻⁴ M TPAMTEB and TPAETEB, respectively taken in a 5% isodecanol and 95% n-dodecane diluent mixture. A stripping study showed a relatively slow stripping of Am³⁺ from the loaded membrane with TPAETEB even in the presence of a complexing agent. Am³⁺ transport rates were rather slow in polypropylene (PP) flat sheets as compared to previous, analogous studies suggesting slow migration of the complexed ions. Am³⁺ transport was 4.8 times slower in TPAETEB than in TPAMTEB with diffusion coefficients of 4.5 × 10⁻⁸ and 2.16 × 10⁻⁷ cm²/s, respectively.