Radiation-induced effects on the extraction properties of hexa-n-octylnitrilo-triacetamide (HONTA) complexes of americium and europium

Abstract

The radiation stability of the candidate An(III)/Ln(III) separation ligand hexa-n-octylnitrilo-triacetamide (HONTA) under envisioned process conditions was investigated using a combination of solvent test loop gamma and pulsed electron irradiation.

Transient Radiation-Induced Berkelium(III) and Californium(III) Redox Chemistry in Aqueous Solution

“…100 ns for the 1.0 mM Cf­(III) solution) across the UV–vis–NIR spectrum range, the reduced Cf­(II) transient absorption spectrum was obtained, as shown in Figure B. The Cf­(II) spectrum is in reasonable agreement with that reported previously, although our data shows an extended absorbance above 420 nm and several small peaks at shorter wavelengths.…”

“…The majority of actinide radiation chemistry knowledge is concentrated toward the beginning of the series, − for which radiation-induced reactions have been demonstrated to significantly impact the accessibility and lifetime of actinide oxidation states at both ultrafast (pico- to microseconds) − and steady-state timescales. − Furthermore, there is precedence for these radiation-induced actinide redox reactions altering the radiolytic integrity of their corresponding complexes, relative to the free ligand, through facilitation of inner- versus outer-sphere reaction pathways. − Concerning the late actinidesamericium (Am) onwardminimal information is available, and yet it remains an area of significant fundamental interest owing to paradigm shifts in the oxidation state metastability from trivalency to divalency in californium (Cf), − and an accessible tetravalent state for berkelium (Bk) . Both of these redox states are at odds to their predominantly trivalent neighbors, Am and curium (Cm) .…”

Effect of metal complexation on diglycolamide radiolysis: a comparison between ex situ gamma and in situ alpha irradiation

“…This could decrease the likelihood that a dodecane radical would interact with a TODGA molecule. However, in a recent paper Toigawa et al 71 measured the coefficient rate for the reaction of the HONTA ligand (hexa- n -octylnitrilo-triacetamide) with a n -dodecane radical cation (R˙ + ); the opposite effect was observed. The coefficient rate increases by over an order of magnitude from 7.6 × 10 9 M −1 s −1 for the free ligand to 7.1 and 9.5 × 10 10 M −1 s −1 for Am–HONTA and Eu–HONTA complexes.…”

“…69 Recently, the effect of the complexation on the reaction kinetics of the dodecane radical cation with organic ligands has been investigated and the effect depends on the metallic ions and the ligands present. 71,72 For comparison sake, we have also irradiated analogous solutions of Nd(III) extracted into TODGA solvents using an external gamma source. Indeed, while the effects of diluent, 33,35 phase modifier, 38,39,48,73 water, 39 and nitric acid 23,33,37,[39][40][41]48,49,73 on TODGA radiolysis have been studied, no studies have yet been published detailing the effects of metal loading on TODGA irradiation.…”

“…69 Recently, the effect of the complexation on the reaction kinetics of the dodecane radical cation with organic ligands has been investigated and the effect depends on the metallic ions and the ligands present. 71,72…”