Time-resolved and steady-state irradiation of hydrophilic sulfonated bis-triazinyl-(bi)pyridines - modelling radiolytic degradation

Radiolytic Evaluation of 3,4,3-LI(1,2-HOPO) in Aqueous Solutions

The octadentate hydroxypyridinone ligand 3,4,3-LI(1,2-HOPO) (abbreviated as HOPO) has been identified as a promising candidate for both chelation and f-element separation technologies, two applications that require optimal performance in radiation environments. However, the radiation robustness of HOPO is currently unknown. Here, we employ a combination of time-resolved (electron pulse) and steady-state (alpha self-radiolysis) irradiation techniques to elucidate the basic chemistry of HOPO and its f-element complexes in aqueous radiation environments. Chemical kinetics were measured for the reaction of HOPO and its Nd(III) ion complex ([Nd^III(HOPO)]^-) with key aqueous radiation-induced radical transients (e_aq^-, H^• atom, and ^•OH and NO₃^• radicals). The reaction of HOPO with the e_aq^- is believed to proceed via reduction of the hydroxypyridinone moiety, while transient adduct spectra indicate that reactions with the H^• atom and ^•OH and NO₃^• radicals proceeded by addition to HOPO's hydroxypyridinone rings, potentially allowing for the generation of an extensive suite of addition products. Complementary steady-state ²⁴¹Am(III)-HOPO complex ([²⁴¹Am^III(HOPO)]^-) irradiations showed the gradual release of ²⁴¹Am(III) ions with increasing alpha dose up to 100 kGy, although complete ligand destruction was not observed.

Stability of Different BTBP and BTPhen Extracting or Masking Compounds against γ Radiation

The radiolytic stability of hydrophobic extracting compounds CyMe₄-BTBP and CyMe₄-BTPhen and a hydrophilic masking agent (PhSO₃H)₂-BTPhen, widely employed for trivalent minor actinoid and lanthanoid separation, against γ radiation was tested. Even though the solvent with a promising fluorinated diluent BK-1 provides better extraction properties compared to octan-1-ol, its radiation stability is much lower, and no extraction was observed already after an absorbed dose of 150 kGy (CyMe₄-BTBP) or 200 kGy (CyMe₄-BTPhen). For the (PhSO₃H)₂-BTPhen hydrophilic masking agent, the results showed that the rate of radiolytic degradation was significantly higher in 0.25 M HNO₃ than in 0.5 M HNO₃. For both the hydrophobic and hydrophilic agents, degradation was slower in the presence of both organic and aqueous phases during irradiation.

Gamma radiolysis of hydrophilic diglycolamide ligands in concentrated aqueous nitrate solution

Advanced analytical techniques and predictive multi-scale modeling calculations show that gamma radiolysis of hydrophilic diglycolamides in concentrated, aqueous nitrate solutions is significantly slower and less structurally sensitive than under pure water conditions.