Redox-Functionalized Deep Eutectic Solvents Boost Efficient Actinide Group Separation

Developing green technologies capable of single-step multivalent actinide separation represents a critical imperative for overcoming the significant waste management challenge inherent to sustainable nuclear energy. Targeting the critical bottleneck of ineffective neptunium(V) (Np(V)) capture from nuclear waste, this study innovatively constructed a series of hydrophobic deep eutectic solvents (DESs) integrating extraction and reduction functionalities, composed of trioctylphosphine oxide (TOPO) and different dihydroxybenzenes (catechol, CC; resorcinol, RC; hydroquinone, HQ). Among them, TOPO-CC DES enables highly efficient in situ reduction of Np(V) to the more extractable Np(IV) species through the synergistic interplay of TOPO complexation and CC-mediated reduction, thereby achieving the simultaneous and efficient removal of all target actinides (uranium, U; Np; plutonium, Pu; americium, Am). This system demonstrates outstanding extraction stability and adaptability across broad ranges of acidity (0.001−2 M HNO3), temperature (293−318 K), salinity (0.5−5 M NaNO3), and varying irradiation doses (0−60 kGy). Mechanistic studies indicate that the efficient group separation of actinides is governed by a synergistic mechanism combining reverse micellar “encapsulation” and direct coordination by TOPO. This work not only provides an environmentally benign and integrated strategy for actinide group separation but also boosts the application prospects of functionalized DESs in advanced nuclear fuel cycle technologies.