Studies on hydrolysis and radiolysis of N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide

Abstract

Diglycolamide / Hydrolysis / Radiolysis / Sensitization effect / n-dodecane / Nitric acidSummary. Hydrolytic and radiolytic stabilities of a promising extractant, N,N,N ,N -tetraoctyl-3-oxapentane-1,5-diamide (TODGA), for actinides in high-level radioactive liquid waste from nuclear fuel reprocessing were investigated in air at room temperature. Hydrolysis by nitric acid was not observed, whereas radiolysis by gamma irradiation was notably observed. The radiolysis study showed that an amide-bond, an ether-bond, and a bond adjacent to the ether-bond tended to be broken by gamma irradiation, and dioctylamine and various N,N-dioctylmonoamides were identified as the main degradation products by GC/MS and NMR analyses. The G-value for degradation of neat TODGA was 8.5 ± 0.9, which value was higher than those for N,N -dioctyl-N,N -dimethyl-2-(3 -oxapentadecyl)-propane-1,3-diamide and N,N-dioctylhexanamide. It was obvious that n-dodecane, which was used for a diluent, had a sensitization effect on the radiolysis of these amidic extractants. In a TODGA-n-dodecane-HNO 3 system, the coexisting nitric acid showed an insignificant effect on the radiolysis of TODGA.

Complexation of Np(v) with N,N-dimethyl-3-oxa-glutaramic acid and related ligands: thermodynamics, optical properties and structural aspects

“…12 Thermodynamic parameters and the crystal structure of an Np(V) complex with DMOGA were obtained in this work. As shown in Figure 1, DMOGA is structurally related to TMOGA and ODA.…”

Separation of Am, Cm and Lanthanides by Solvent Extraction with Hydrophilic and Lipophilic Organic Ligands

“…complexes by DOODA and DGA [1,3] and a previous study reports a high stability for TODGA in contact with HNO 3 [11]. The effect of alkyl chain length on Ln extraction can be seen particularly in the behavior of the heavy Ln in DOODA extractions.…”

Adsorption Characteristics of Trivalent Rare Earths and Chemical Stability of a Silica-Based Macroporous TODGA Adsorbent in HNO3Solution

“…On the other hand, because the amide bonds and the bonds in the vicinity of the ether oxygen are relatively weak, a small portion of TODGA is presumed to be destroyed by HNO 3 at elevated temperature (323 K) and decomposed to amines and monoamides as reported in the case of the radiolytic degradation of TODGA in the HNO 3 solution. 12,23) This result suggests that the chromatographic operation for the HLLW partitioning using TODGA/SiO 2 -P adsorbent should be carried out at around 298 K other than the elevated temperature. Concerning the decay heat of HLLW, which would result in a temperature increase, a coolant jacket should be equipped for the adsorbent-packed column in a practical process.…”

“…According to the literature, 12,23) the octyl chain attached to the N atoms gives enough lipophilicity to prevent the TODGA molecules from dissolving in water. The very low leakage amount of TODGA observed at 298 K in this work shows a good agreement with this predication.…”