Hydroxypyridinone-based stabilization of Np(IV) enabling efficient U/Np/Pu separations in the Adapted PUREX process

The classical process to recover uranium (U) and plutonium (Pu) from used nuclear fuel using tributyl phosphate (TBP), namely the Plutonium Uranium Redox EXtraction (PUREX) process, is complicated by persistent presence of neptunium (Np) thus requires extra purification steps. concept Adapted PUREX seeks achieve Np recovery adjusting valence metal more effectively, thereby controlling its behavior precisely. This study introduces use an aqueous hydroxypyridinone chelator, 3,4,3-LI(1,2-HOPO) (abbreviated as HOPO), dictate for meanwhile simplify cumbersome reprocessing interactions between HOPO were probed mechanistically way absorption spectrophotometry, in conjunction with cyclic voltammetry. UV–Vis-NIR spectra illustrated reduction NpO22+ Np4+, a fast reaction rate. Cyclic voltammetry revealed quasi-reversible processes oxidized reduced forms ligand complexes. corresponding heterogeneous rate constants (k0) estimated peak-to-peak separation potentials (?Ep), at ~ 4 – 35 ?m/s both NpHOPO, scan rates 0.01 0.4 V/s. Meanwhile, electromotive force (EMF) well change Gibbs free energy (?G) assessed half-wave potential (E1/2), demonstrating completeness Np4+ HOPO. cumulative formation constant resulting NpHOPO complex (log?101) was determined competition titration be 42.0 ± 0.6, corroborating extraordinarily high affinity tetravalent ions. prowess control stability formed resulted enhanced separations U Pu U, maximum factor ~7000 both, nearly 90- 10300-fold higher, respectively, than values obtained conventional formulae.