A Spectroscopic Study of Uranium and Molybdenum Complexation within the Pore Channels of Hybrid Mesoporous Silica

Charlot, Alexandre; Dumas, Thomas; Solari, Pier Lorenzo; Cuer, Frédéric; Grandjean, Agnès

doi:10.1002/ejic.201601085

Cited by 8 publications

(8 citation statements)

References 48 publications

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“…In the presence of iron and molybdenum (Figures 6b and 7b), the uranium extraction capacities of the materials are substantially lower (about 75% of the values measured in the absence of competing cations, Table 3) and the equilibrium ligand/uranium ratio is higher (~2.6). The same trend was observed by Charlot et al in solutions with a low sulfate concentration at pH 3 [21] and is probably due to the extraction of some of the iron and/or molybdenum in the solution instead of uranium.…”

Section: Extraction Of Uranium From Sulfuric Acid Solutionssupporting

confidence: 86%

“…Charlot et al [21] measured the same ligand/uranium ratio for materials grafted with DEHCEBP in sulfuric media at pH 3 with a low sulfate/uranium ratio ([SO 4 ] 2− /[U] = 50 mol/mol). We can thus conclude that the extraction mechanism in these impregnated materials with up to 0.5 mmol•g −1 DEHCEBP at high sulfate concentrations is the same as described by Charlot et al [21] for the grafted materials. In the presence of iron and molybdenum (Figures 6b and 7b), the uranium extraction capacities of the materials are substantially lower (about 75% of the values measured in the absence of competing cations, Table 3) and the equilibrium ligand/uranium ratio is higher (~2.6).…”

Section: Extraction Of Uranium From Sulfuric Acid Solutionsmentioning

confidence: 81%

“…We have previously studied the post functionalization of silica with carbamoylalkylphosphonates [ 20 , 21 , 22 , 23 , 24 ], bifunctional amidophosphonate ligands that have also been used for the solvent extraction of uranium from (acidic) phosphate [ 25 , 26 ] and sulfate solutions [ 27 ]. These ligands were attached to the silica surface by chemical bonding (grafting) or by simple physical adsorption (impregnation).…”

Section: Introductionmentioning

confidence: 99%

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Effects of Impregnated Amidophosphonate Ligand Concentration on the Uranium Extraction Behavior of Mesoporous Silica

2022

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A series of solid-phase uranium extractants were prepared by post-synthesis impregnation of a mesoporous silica support previously functionalized with octyl chains by direct silanization. Five materials were synthesized with 0, 0.2, 0.3, 0.4 and 0.5 mmol of the amidophosphonate ligand DEHCEBP per gram of functionalized solid, and the effect of the ligand concentration on the uranium extraction efficiency and selectivity of the materials was investigated. Nitrogen adsorption–desorption data show that with increasing ligand loadings, the specific surface area and average pore volume decrease as the amidophosphonate ligand fills first the micropores and then the mesopores of the support. Acidic uranium solutions with a high sulfate content were used to replicate the conditions in ore treatment leaching solutions. Considering the extraction kinetics, the equilibration time was found to increase with the ligand concentration, which can be explained by the clogging of micropores and the multilayer arrangement of the DEHCEBP molecules in the materials with their highest ligand contents. The fact that the equilibrium ligand/uranium ratio is about 2 mol/mol regardless of the ligand concentration in the material suggests that all the ligand molecules remain accessible for extraction. The maximum uranium extraction capacities ranged from 30 mg∙g−1 at 0.2 mmol∙g−1 DEHCEBP to 54 mg∙g−1 in the material with 0.5 mmol∙g−1 DEHCEBP. These materials could therefore potentially be used as solid-phase uranium extractants in acidic solutions with high sulfate concentrations.

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Section: Extraction Of Uranium From Sulfuric Acid Solutionssupporting

confidence: 86%

Section: Extraction Of Uranium From Sulfuric Acid Solutionsmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

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Effects of Impregnated Amidophosphonate Ligand Concentration on the Uranium Extraction Behavior of Mesoporous Silica

2022

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“…Modularity of hybrid frameworks is an attractive and desirable foundation for development of new constituents, motifs, and architectures for efficient storage, separation, and selective sequestration of nuclear waste, which could address current challenges, especially in light of recently reported problems. − Framework versatility, − in combination with its modularity, − can lead to a more homogeneous actinide (An) distribution (e.g., through actinide metal nodes − or anchoring the actinide to organic linkers − ), which decreases the accumulation of possible radiation damage caused by the formation of vacancies and defects. − In addition to actinide inclusion, hybrid frameworks also offer the opportunity for actinide immobilization through covalent bond formation. Furthermore, the solvothermal approach commonly used for preparation of metal–organic frameworks (MOFs) relies on moderate temperatures, which prevents formation of volatile radioactive species, in contrast to the ∼1000 °C temperature regime required for preparation of radionuclide-containing borosilicate glass as contaminant sequesters …”

Section: Introductionmentioning

confidence: 99%

Multifaceted Modularity: A Key for Stepwise Building of Hierarchical Complexity in Actinide Metal–Organic Frameworks

et al. 2017

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Growing necessity for efficient nuclear waste management is a driving force for development of alternative architectures toward fundamental understanding of mechanisms involved in actinide (An) integration inside extended structures. In this manuscript, metal-organic frameworks (MOFs) were investigated as a model system for engineering radionuclide containing materials through utilization of unprecedented MOF modularity, which cannot be replicated in any other type of materials. Through the implementation of recent synthetic advances in the MOF field, hierarchical complexity of An-materials was built stepwise, which was only feasible due to preparation of the first examples of actinide-based frameworks with "unsaturated" metal nodes. The first successful attempts of solid-state metathesis and metal node extension in An-MOFs are reported, and the results of the former approach revealed drastic differences in chemical behavior of extended structures versus molecular species. Successful utilization of MOF modularity also allowed us to structurally characterize the first example of bimetallic An-An nodes. To the best of our knowledge, through combination of solid-state metathesis, guest incorporation, and capping linker installation, we were able to achieve the highest Th wt % in mono- and biactinide frameworks with minimal structural density. Overall, the combination of a multistep synthetic approach with homogeneous actinide distribution and moderate solvothermal conditions could make MOFs an exceptionally powerful tool to address fundamental questions responsible for chemical behavior of An-based extended structures and, therefore, shed light on possible optimization of nuclear waste administration.

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“…This family of molecules has been investigated previously in liquid-liquid extraction processes in sulphuric and phosphoric acid media [11], and for solid phase extraction using functionalized mesoporous silica powders [12]. Its potential as a Ce extractant has remained unexplored to date.…”

Section: Introductionmentioning

confidence: 99%

Amidophosphonate ligands as cerium extractants in supercritical CO2

Bouali

Leybros

Toquer

et al. 2019

The Journal of Supercritical Fluids

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Industrial-scale rare earth extraction is typically performed by liquid-liquid extraction with large amounts of solvents, acids and organophosphorus ligands. An alternative is to use these extractants in supercritical CO 2 (SC-CO 2), where the crucial operating parameter is their solubility. Different molecules with amidophosphonate backbones have been synthesized and investigated in view of improving their solubility in SC-CO 2 and thereby their cerium extraction capacity. The CO 2-philicity of these extractants was adjusted by attaching branched or linear alkyl chains with four, six and eight carbons. Using a dynamic gravimetric setup, the solubility and cerium extraction capacity of these molecules were measured to vary from 1.56 to 2.47 mmol/mol and 0.25 to 0.46 mmol/mol, respectively. The two properties were correlated and in both cases the highest values were obtained with a diisobutylamine chain. The solubility of the corresponding amidophosphonate extractant was found to be optimal at 320 K and 28 MPa.

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A Spectroscopic Study of Uranium and Molybdenum Complexation within the Pore Channels of Hybrid Mesoporous Silica

Cited by 8 publications

References 48 publications

Effects of Impregnated Amidophosphonate Ligand Concentration on the Uranium Extraction Behavior of Mesoporous Silica

Effects of Impregnated Amidophosphonate Ligand Concentration on the Uranium Extraction Behavior of Mesoporous Silica

Multifaceted Modularity: A Key for Stepwise Building of Hierarchical Complexity in Actinide Metal–Organic Frameworks

Amidophosphonate ligands as cerium extractants in supercritical CO2

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