Thermal stability study of a new guanidine suppressor for the next-generation caustic-side solvent extraction process

Hill, Talon G.; Ensor, D.D.; Delmau, Lætitia H.; Moyer, Bruce A.

doi:10.1080/01496395.2016.1143509

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…A similar study with the current guanidine suppressor TiDG showed similar suppressor degradation when the NGS solvent is in contact with a caustic solution at 36°C for at least a month. 7 These studies were focused on solvent stability and performance over time and were not analyzed for hydrogen formation.…”

Section: Thermal Stability Of the Ngs Solventmentioning

confidence: 99%

Literature Review on the Impact of Thermolytic Hydrogen Generation Rate from the Next Generation Solvent

HUNTER

2021

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A literature review was undertaken to assess the thermolytic hydrogen generation potential of the Next Generation Solvent (NGS) system, which is planned to replace the Original Caustic-Side Solvent Extraction (CSSX) Solvent at the Salt Waste Processing Facility. NGS uses a new extractant and suppressor and the same modifier and organic carrier solvent as the Original CSSX Solvent at different concentrations.The major components of the two CSSX solvent compositions remain the same while the calix[4]arene extractants should have similar properties, and as such, the solvent systems should have a similar thermal stability. The well-studied Original CSSX Solvent was found to have no process-significant energetic events up to evaporator temperatures in Accelerated Rate Calorimetry experiments. Revision vi

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Section: Thermal Stability Of the Ngs Solventmentioning

confidence: 99%

Literature Review on the Impact of Thermolytic Hydrogen Generation Rate from the Next Generation Solvent

HUNTER

2021

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“…It is central to the function of a variety of biological molecules such as amino acids, proteins, enzymes, , medicines, , and toxins . Industrially, it has proven useful for polymers, , catalysts, , disinfectants, , fungicides, ,, and solvent extraction reagents. − In many of these cases, guanidines often suffer from a limited resistance to hydrolysis resulting in the formation of ureas and amines. − Decreasing the hydrolytic susceptibility of the guanidine group would thus be expected to increase the longevity of guanidines in applications such as solvent extraction or in guanidine-based medicines and disinfectants. Here, the effect of adding alkyl groups of varying steric hindrance at all three of the guanidine nitrogen atoms has been examined to determine if branching close to the guanidine N atom can slow the rate of guanidine hydrolysis.…”

Section: Introductionmentioning

confidence: 99%

“…27 Unfortunately, TiDG is prone to hydrolysis over the course of several months of exposure to the highly alkaline waste and other process aqueous solutions, which necessitates regular additions of additional TiDG to maintain acceptable performance. 29 A previously considered guanidine, N,N′-dicyclohexyl-N″-isotridecylguanidine (DCiTG), Figure 2, has shown comparable or somewhat more resistance to this degradation, 21 but it is not as lipophilic as desired, 23 causing it to be washed out of the solvent too quickly. Its greater stability is thought to be caused by the greater steric hindrance to nucleophiles afforded by the bulky cyclohexyl groups.…”

Section: ■ Introductionmentioning

confidence: 99%

Lipophilic Guanidine with Enhanced Stability for Use in Cesium Separation from Legacy High-Level Nuclear Waste

Bessen

Ivanov

Stamberga

et al. 2023

Ind. Eng. Chem. Res.

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Guanidine functional groups are found in a variety of biologically active molecules and specialized molecules used in industrial applications but often suffer from instability because of their tendency to hydrolyze. Here, guanidines with differently structured alkyl groups were synthesized and their stabilities tested to determine if there is a relationship between the locus of branching in the alkyl groups attached to a guanidine and its hydrolytic stability under the hypothesis that increased steric hindrance to hydrolytic attack will increase stability. The guanidines examined in this work are pertinent to the next-generation caustic-side solvent extraction (NG-CSSX) process, which was developed for the removal of radioactive cesium from highly radioactive and complex alkaline solutions. In the NG-CSSX process, a lipophilic alkylguanidine solvent component is highly important to maintain the effectiveness of the Cs + stripping of the loaded organic solvent putatively by sequestering extractable anions. Currently used for this purpose, N,N′,N″-tri(3,7-dimethyloctyl)guanidine (TiDG) succumbs to slow hydrolysis under process conditions. Guided by quantum chemical calculations, two new guanidines with large, sterically bulky alkyl substituents have been designed, synthesized, and tested. More sterically hindering alkyl groups were found to increase the stability of guanidines, particularly for the guanidine with branching closest to the guanidine N atom: N,N′-dicyclohexyl-N″-(10-nonadecyl)guanidine (DCNDG). DCNDG was found to have a stability toward hydrolysis 8 to 44 times greater than that of TiDG under different simulated NG-CSSX process conditions, making it one of the most hydrolysisresistant guanidine molecules reported to date.

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18-Crown-6-ether assembly of cesium ion-imprinted polymer enabling efficiently selective separation of cs(I) from aqueous solution

Ma,

Qi,

Gao

et al. 2024

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Thermal stability study of a new guanidine suppressor for the next-generation caustic-side solvent extraction process

Cited by 5 publications

References 10 publications

Literature Review on the Impact of Thermolytic Hydrogen Generation Rate from the Next Generation Solvent

Literature Review on the Impact of Thermolytic Hydrogen Generation Rate from the Next Generation Solvent

Lipophilic Guanidine with Enhanced Stability for Use in Cesium Separation from Legacy High-Level Nuclear Waste

18-Crown-6-ether assembly of cesium ion-imprinted polymer enabling efficiently selective separation of cs(I) from aqueous solution

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