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Title: Radiation chemistry of the branched-chain monoamide di-ethylhexyl-isobutyramide

Abstract

The radiolytic degradation rate of DEHiBA is similar to that of TBP and malonamides, and slow compared to the DGAs, and is unaffected by contact with an aqueous phase or aeration. However, product distributions vary with irradiation conditions. Based on these results, DEHiBA apparently undergoes degradation via two pathways: an acid promoted pathway, Scheme 1, and an acid independent pathway, Scheme 2. It is clear that the monoamide degrades when irradiated in the presence of an aqueous phase to form a series of lower molecular weight species generated from the cleavage of the C-N amide bond or C-N amine bond. As this is the active site during synthesis, it is not surprising that this is the weak point in the ligand structure. The main degradation products appear to be DEHA and EHiBA. These species, and the smaller fragments produced by their radioysis have increased solubility in the aqueous phase. Another product common to all irradiation conditions was the species at m/z 310.2, which is identified as an unsaturated derivative of DEHiBA, resulting from the loss of two H-atoms. In contrast, when an aqueous phase is not present, higher molecular weight products are generated via carbon radical addition reactions under themore » more reducing conditions. These products have maximum abundance at 750 kGy, and then decrease with increasing absorbed dose. Their significance to a biphasic solvent extraction process is probably inconsequential. Solvent extraction results show that DEHiBA radiolytic degradation had little effect on uranium distribution ratios even at absorbed doses as high as 1 MGy. The build-up of degradation products in the aqueous phase apparently decreased stripping distribution ratios, which is not adverse to a process application. Thus, these findings for DEHiBA are in agreement with previous work that claimed good radiation stability and generation of inoffensive radiolysis products for the monoamides. This, in addition to their CHON nature suggests that they will be good candidates for the development of advanced fuel cycles. Interesting future work would include a comparison study on the n-alkane monoamide DEHBA.« less

Authors:
ORCiD logo [1]
  1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
Publication Date:
Research Org.:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1406976
Report Number(s):
INL/EXT-16-39882
TRN: US1800528
DOE Contract Number:
AC07-05ID14517
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; RADIOLYSIS; ABSORBED RADIATION DOSES; RADIATION CHEMISTRY; monoamides; radiation chemistry; solvent extraction; tributyl phosphate; uranium

Citation Formats

Mincher, Bruce Jay. Radiation chemistry of the branched-chain monoamide di-ethylhexyl-isobutyramide. United States: N. p., 2016. Web. doi:10.2172/1406976.
Mincher, Bruce Jay. Radiation chemistry of the branched-chain monoamide di-ethylhexyl-isobutyramide. United States. doi:10.2172/1406976.
Mincher, Bruce Jay. Thu . "Radiation chemistry of the branched-chain monoamide di-ethylhexyl-isobutyramide". United States. doi:10.2172/1406976. https://www.osti.gov/servlets/purl/1406976.
@article{osti_1406976,
title = {Radiation chemistry of the branched-chain monoamide di-ethylhexyl-isobutyramide},
author = {Mincher, Bruce Jay},
abstractNote = {The radiolytic degradation rate of DEHiBA is similar to that of TBP and malonamides, and slow compared to the DGAs, and is unaffected by contact with an aqueous phase or aeration. However, product distributions vary with irradiation conditions. Based on these results, DEHiBA apparently undergoes degradation via two pathways: an acid promoted pathway, Scheme 1, and an acid independent pathway, Scheme 2. It is clear that the monoamide degrades when irradiated in the presence of an aqueous phase to form a series of lower molecular weight species generated from the cleavage of the C-N amide bond or C-N amine bond. As this is the active site during synthesis, it is not surprising that this is the weak point in the ligand structure. The main degradation products appear to be DEHA and EHiBA. These species, and the smaller fragments produced by their radioysis have increased solubility in the aqueous phase. Another product common to all irradiation conditions was the species at m/z 310.2, which is identified as an unsaturated derivative of DEHiBA, resulting from the loss of two H-atoms. In contrast, when an aqueous phase is not present, higher molecular weight products are generated via carbon radical addition reactions under the more reducing conditions. These products have maximum abundance at 750 kGy, and then decrease with increasing absorbed dose. Their significance to a biphasic solvent extraction process is probably inconsequential. Solvent extraction results show that DEHiBA radiolytic degradation had little effect on uranium distribution ratios even at absorbed doses as high as 1 MGy. The build-up of degradation products in the aqueous phase apparently decreased stripping distribution ratios, which is not adverse to a process application. Thus, these findings for DEHiBA are in agreement with previous work that claimed good radiation stability and generation of inoffensive radiolysis products for the monoamides. This, in addition to their CHON nature suggests that they will be good candidates for the development of advanced fuel cycles. Interesting future work would include a comparison study on the n-alkane monoamide DEHBA.},
doi = {10.2172/1406976},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 2016},
month = {Thu Sep 01 00:00:00 EDT 2016}
}

Technical Report:

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  • Respirators fitted with high-efficiency particulate (HEPA) cartridge filters are designed to remove dust, fumes, mists, and airborne particulate radionuclides. If these filters are to be reused, a Quality Assurance (QA) program must be established to ensure that filter efficiency remains greater than 99.97%. The standard method for performing QA testing is to challenge the filter with a thermally generated aerosol of 0.3-..mu..m-diam di-2-ethylhexyl phthalate (DEHP). Because of potential toxicological and other problems associated with the use of monodisperse DEHP, an investigation to study measured filter efficiencies on a HEPA respirator filter population, using several recommended replacement aerosols, has been conducted.more » Aerosols compared in this study were thermally generated di-2-ethylhexyl sebecate (DEHS), thermally generated DEHP, air-jet-generated DEHS, and air-jet-generated salt (NaCl). The study also focused on determining compatibility for parallel use of aerosols generated for respirator-fit testing for use in QA filter testing. Results indicate that a polydisperse air-jet-generated aerosol of DEHS can substitute for thermally generated DEHP as a method of providing QA testing of HEPA respirator filters and that equipment used in the study designed for respirator quantitative-fit testing can easily be modified to perform this function. 30 refs., 28 figs., 11 tabs.« less
  • The extraction behavior of di-2-ethylhexyl isobutyramide (D2EHIBA) in dodecane medium for U(VI), Th(IV), and fission products such as Zr, Ce, Eu, and Cs, and the structural material Fe, has been investigated over a wide range of nitric acid concentrations. It has been observed that whereas D{sub U} varies from <10{sup {minus}3} (pH 2.0)to 4.4 (6 M HNO{sub 3}) with 1 M ligand, the corresponding D{sub Th} values are 1.5 {times} 10{sup {minus}3} and 4 {times} 10{sup {minus}2}. In the presence of 250 g/L of Th, D{sub U} values are 8.6 (pH 2.0) and 2.2 (6 M HNO{sub 3}).D2EHIBA has beenmore » found to be a promising extractant of trace concentrations of U in the presence of macro amounts of Th. The extraction of fission products and Fe is found to be negligible. D2EHIBA is found to extract nitric acid predominantly as a 1:1 species (K{sub H} = 0.156 {+-} 0.048). U(VI) is extracted as a disolvate UO{sub 2}(NO{sub 3}){sub 2}{center_dot}2D2EHIBA (K{sub ex} = 0.87 {+-} 0.08).« less
  • The selective separation of uranium(VI) in the first cycle of the GANEX process is operated by a hydrometallurgical process using a monoamide extractant DEHiBA (N,N-di-(2-ethylhexyl)isobutyramide). Distribution ratios of uranium(VI) and nitric acid in 1 M DEHiBA/HTP were determined with macro-concentrations of uranium, and the experimental data were modelled by taking into account the activity coefficients of the constituents in aqueous phases. A flowsheet was designed and tested in a countercurrent process in laboratory-scale mixer-settlers on a surrogate U(VI)/HNO 3 feed. More than 99.999% of the uranium was recovered. (authors)
  • For the system uranyl-ion--tri(n-octyl)phosphine oxide (TOPO) -excess di (2-ethylhexyi)phosphoric acid (D2EHPA) in kerosene the ratio U: TOPO of the complex formed was investigated spectrophotometrically using the method of continuous variations. In solutions 0.1M in D2EHPA and 10/sup -/2 to 10/sup -3/M in hexavalent uranium and TOPO, a complex with the molar ratio U: TOPO = 1: 1 was identified. The order of magnitude of the dissociation constant of this complex was found to be 10/sup -4/. The applicability of the method of continuous variations to the investigation of this system complicated by side reactions was demonstrated theoretically. The calculations refermore » to the following types of reactions: AC/sub 2/ + n8 = AC/sub 2/B/sub n/ and AC/sub 2/ + nB = BC and B + 1/2 C = BC/sub 1/2/. (auth)« less