As part of an effort to develop a combined Cs and actinide (An) extraction process for Caustic High-Level Waste (HLW) for improvement of the Next-Generation Caustic Side Solvent Extraction (NG-CSSX) process, our group has reported o-phenylenediamine-derived sulfonamide (dsa) and o-(sulfonamido)phenol (msa) ligands, as effective Sm(III) extractants from alkaline aqueous solutions. Specifically, recoveries up to 81% at pH 13.0–13.5 (for dsa) and up to 90% at pH = 14.0 (for msa), into chlorinated solvents were achieved after a single loading/stripping cycle. In this study, the highly-lipophilic msa derivatives msa6 and msa7 were synthesized, characterized, and evaluated for Sm(III) extraction from up to 2.5 M NaOH aqueous solutions using a formulated NG-CSSX simulant and the actual NG-CSSX solvent, showing up to 25% recovery of Sm(II) after a single loading/stripping cycle. Extraction experiments with both extractants were also conducted in the presence of the most abundant ions in tank waste; K⁺(0.045 M), Na⁺ (5.6 M), CO₃^2-(0.2 M), NO₂^- (0.5 M), NO₃^-(2.06 M), OH^-(2.06 M), Cl^- (0.01 M) and SO₄^2- (0.14 M), showing up to 8% recovery of Sm(III) and 15% recovery of Cs(I) for msa6 in the listed ion matrix. The extraction efficiency of Am-241 and Eu-154 with msa7 showed D_Eu = 3.0, D_Am = 1.08, and D_Cs = 254.9 when irradiated at 202 kGy, while msa6 showed D_Eu = 1.64, D_Am = 0.79, and D_Cs = 212.83 at 202 kGy. Studies with slope analysis using Sm(III) and other Ln(III) and spectroscopic studies by ¹H-NMR for determination of binding constants will also be presented

Ingrid Lehman-Andino

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