Pub Date : 2021-08-06DOI: 10.1080/07366299.2021.1953259
S. Gourdin-Bertin, J. Dufrêche, M. Duvail, T. Zemb
ABSTRACT We consider here the extraction of metals in the form of salts transferred from an aqueous to a solvent phase. Extraction is triggered by complexation and quenched by the associated necessary reorganization of the structured solvent phase. The extraction of ions changes the relative fraction of extractant molecules that is not part of the highly curved surfactant monolayer and is dispersed molecularly in the oil, and also the polar volume fraction including co-extracted water. The free energy and corresponding microstructures of the water-poor microemulsions are modelled in the frame of the Gaussian random fields (GRF) model. The curvature frustration energy significantly contributes to the free energy of extraction. A typical example of predicted isotherm using the GRF model is compared to the classically considered supramolecular complex formation, together with a minimal Langmuir model and an explicit monomer-to-film equilibrium of amphiphilic extractant. The corresponding small-angle scattering spectra and morphology changes are shown. One implication is that selectivity between a hydrated and a non-hydrated species is concentration dependent and cannot be considered as a constant as a function of the extractant concentration.
{"title":"Microemulsion as Model to Predict Free Energy of Transfer of Electrolyte in Solvent Extraction","authors":"S. Gourdin-Bertin, J. Dufrêche, M. Duvail, T. Zemb","doi":"10.1080/07366299.2021.1953259","DOIUrl":"https://doi.org/10.1080/07366299.2021.1953259","url":null,"abstract":"ABSTRACT We consider here the extraction of metals in the form of salts transferred from an aqueous to a solvent phase. Extraction is triggered by complexation and quenched by the associated necessary reorganization of the structured solvent phase. The extraction of ions changes the relative fraction of extractant molecules that is not part of the highly curved surfactant monolayer and is dispersed molecularly in the oil, and also the polar volume fraction including co-extracted water. The free energy and corresponding microstructures of the water-poor microemulsions are modelled in the frame of the Gaussian random fields (GRF) model. The curvature frustration energy significantly contributes to the free energy of extraction. A typical example of predicted isotherm using the GRF model is compared to the classically considered supramolecular complex formation, together with a minimal Langmuir model and an explicit monomer-to-film equilibrium of amphiphilic extractant. The corresponding small-angle scattering spectra and morphology changes are shown. One implication is that selectivity between a hydrated and a non-hydrated species is concentration dependent and cannot be considered as a constant as a function of the extractant concentration.","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"40 1","pages":"28 - 63"},"PeriodicalIF":2.0,"publicationDate":"2021-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46815147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-30DOI: 10.1080/07366299.2021.1954323
Nitesh Kumar, Michael J. Servis, A. Clark
ABSTRACT Uranyl (UO ) speciation at the liquid/liquid interface is an essential aspect of the mechanism that underlies its extraction as part of spent nuclear fuel reprocessing schemes and environmental remediation of contaminated legacy waste sites. Of particular importance is a detailed perspective of how changing ion concentrations at the liquid interface alter the distribution of hydrated uranyl ion and its interactions with complexing electrolyte counterions relative to the bulk aqueous solution. In this work, classical molecular dynamics simulations have examined uranyl in bulk LiNO and in the presence of a hexane interface. UO is observed to have both direct coordination with NO and outer-sphere interactions via solvent-separated ion-pairing (SSIP), whereas the interaction of Li with NO (if it occurs) is predominantly as a contact ion-pair (CIP). The variability of uranyl interactions with nitrate is hypothesized to prevent dehydration of uranyl at the interface, and as such the cation concentration is unperturbed in the interfacial region. However, Li loses waters of solvation when it is present in the interfacial region, an unfavorable process that causes a Li depletion region. Although significant perturbations to ion–ion interactions, solvation, and solvation dynamics are observed in the interfacial region, importantly, this does not change the association constants of uranyl with nitrate. Thus, the experimental association constants, in combination with knowledge of the interfacial ion concentrations, can be used to predict the distribution of interfacial uranyl nitrate complexes. The enhanced concentration of uranyl dinitrate at the interface, caused by excess adsorbed NO , is highly relevant to extractant ligand design principles as such nitrate complexes that are the reactants in ligand complexation and extraction events.
{"title":"Uranyl Speciation in the Presence of Specific Ion Gradients at the Electrolyte/Organic Interface","authors":"Nitesh Kumar, Michael J. Servis, A. Clark","doi":"10.1080/07366299.2021.1954323","DOIUrl":"https://doi.org/10.1080/07366299.2021.1954323","url":null,"abstract":"ABSTRACT Uranyl (UO ) speciation at the liquid/liquid interface is an essential aspect of the mechanism that underlies its extraction as part of spent nuclear fuel reprocessing schemes and environmental remediation of contaminated legacy waste sites. Of particular importance is a detailed perspective of how changing ion concentrations at the liquid interface alter the distribution of hydrated uranyl ion and its interactions with complexing electrolyte counterions relative to the bulk aqueous solution. In this work, classical molecular dynamics simulations have examined uranyl in bulk LiNO and in the presence of a hexane interface. UO is observed to have both direct coordination with NO and outer-sphere interactions via solvent-separated ion-pairing (SSIP), whereas the interaction of Li with NO (if it occurs) is predominantly as a contact ion-pair (CIP). The variability of uranyl interactions with nitrate is hypothesized to prevent dehydration of uranyl at the interface, and as such the cation concentration is unperturbed in the interfacial region. However, Li loses waters of solvation when it is present in the interfacial region, an unfavorable process that causes a Li depletion region. Although significant perturbations to ion–ion interactions, solvation, and solvation dynamics are observed in the interfacial region, importantly, this does not change the association constants of uranyl with nitrate. Thus, the experimental association constants, in combination with knowledge of the interfacial ion concentrations, can be used to predict the distribution of interfacial uranyl nitrate complexes. The enhanced concentration of uranyl dinitrate at the interface, caused by excess adsorbed NO , is highly relevant to extractant ligand design principles as such nitrate complexes that are the reactants in ligand complexation and extraction events.","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"40 1","pages":"165 - 187"},"PeriodicalIF":2.0,"publicationDate":"2021-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/07366299.2021.1954323","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43474497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-07DOI: 10.1080/07366299.2021.1946999
Ananda Karak, B. Mahanty, P. Mohapatra, R. Egberink, T. Valsala, D. Sathe, R. Bhatt, J. Huskens, W. Verboom
ABSTRACT Solutions of two nitrilotriacetamide (NTA) ligands, viz., N,N,N’,N’,N”,N”-hexa-n-butylnitrilotriacetamide (HBNTA) and N,N,N’,N’,N”,N”-hexa-n-hexylnitrilotriacetamide (HHNTA) in 20% isodecanol–80% n-dodecane were employed for the extraction of U(VI), Np(IV), Pu(IV), and Am(III) from nitric acid feed solutions. Limitations of ligand solubility and third-phase formation when contacted with nitric acid solutions led to the choice of the diluent composition of 20% isodecanol and 80% n-dodecane. The results of the solvent extraction studies indicated poor extraction of the metal ions with HBNTA as compared to that with HHNTA as the extractant and hence, major part of this work involved HHNTA. Slope analysis suggested extraction of 1:1 (ML) species with Np(IV) and Pu(IV) at 3 M HNO3 and mixed 1:2 (ML2) and 1:3 (ML3) species with U(VI) at pH 2. At 0.5 M HNO3, the observed trend for extraction was Pu(IV) > Np(IV) >> Am(III) > U(VI).
{"title":"Liquid–Liquid Extraction of Actinides from Nitric Acid Feeds Using Two Hexa-n-alkylnitrilotriacetamides","authors":"Ananda Karak, B. Mahanty, P. Mohapatra, R. Egberink, T. Valsala, D. Sathe, R. Bhatt, J. Huskens, W. Verboom","doi":"10.1080/07366299.2021.1946999","DOIUrl":"https://doi.org/10.1080/07366299.2021.1946999","url":null,"abstract":"ABSTRACT Solutions of two nitrilotriacetamide (NTA) ligands, viz., N,N,N’,N’,N”,N”-hexa-n-butylnitrilotriacetamide (HBNTA) and N,N,N’,N’,N”,N”-hexa-n-hexylnitrilotriacetamide (HHNTA) in 20% isodecanol–80% n-dodecane were employed for the extraction of U(VI), Np(IV), Pu(IV), and Am(III) from nitric acid feed solutions. Limitations of ligand solubility and third-phase formation when contacted with nitric acid solutions led to the choice of the diluent composition of 20% isodecanol and 80% n-dodecane. The results of the solvent extraction studies indicated poor extraction of the metal ions with HBNTA as compared to that with HHNTA as the extractant and hence, major part of this work involved HHNTA. Slope analysis suggested extraction of 1:1 (ML) species with Np(IV) and Pu(IV) at 3 M HNO3 and mixed 1:2 (ML2) and 1:3 (ML3) species with U(VI) at pH 2. At 0.5 M HNO3, the observed trend for extraction was Pu(IV) > Np(IV) >> Am(III) > U(VI).","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"40 1","pages":"366 - 386"},"PeriodicalIF":2.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/07366299.2021.1946999","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41761046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-23DOI: 10.1080/07366299.2021.1939177
M. Sarsfield, M. Carrott, C. Maher, C. Mason, R. Sanderson, R. J. Taylor, T. Tinsley, D. Whittaker, D. Woodhead
ABSTRACT The production of 238Pu from 237Np, to the specifications required for space flight, requires the separation of plutonium from neptunium and a range of fission products. The valuable neptunium is then recycled into targets for further irradiation. At Oak Ridge National Laboratory (ORNL), a solvent extraction process has been developed to separate neptunium and plutonium that uses sodium nitrite to control the neptunium oxidation. This results in a neptunium product contaminated with sodium, which needs to be removed prior to recycling. We have developed a separation process that results in a sodium-free neptunium product with very low levels of plutonium contamination, there by reducing the number of purification steps and thus simplifying the process.
{"title":"An Alternative Solvent Extraction Flowsheet for Separating 237Np from 238Pu for Space Power Applications","authors":"M. Sarsfield, M. Carrott, C. Maher, C. Mason, R. Sanderson, R. J. Taylor, T. Tinsley, D. Whittaker, D. Woodhead","doi":"10.1080/07366299.2021.1939177","DOIUrl":"https://doi.org/10.1080/07366299.2021.1939177","url":null,"abstract":"ABSTRACT The production of 238Pu from 237Np, to the specifications required for space flight, requires the separation of plutonium from neptunium and a range of fission products. The valuable neptunium is then recycled into targets for further irradiation. At Oak Ridge National Laboratory (ORNL), a solvent extraction process has been developed to separate neptunium and plutonium that uses sodium nitrite to control the neptunium oxidation. This results in a neptunium product contaminated with sodium, which needs to be removed prior to recycling. We have developed a separation process that results in a sodium-free neptunium product with very low levels of plutonium contamination, there by reducing the number of purification steps and thus simplifying the process.","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"40 1","pages":"349 - 365"},"PeriodicalIF":2.0,"publicationDate":"2021-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/07366299.2021.1939177","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44300529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ion-Exchange Kinetics in Heterogeneous Systems","authors":"K. Bunzl","doi":"10.1201/9781003208846-6","DOIUrl":"https://doi.org/10.1201/9781003208846-6","url":null,"abstract":"","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"51 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2021-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88420793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Recovery of Valuable Mineral Components from Seawater by Ion-Exchange and Sorption Methods","authors":"R. Khamizov, D. Muraviev, A. Warshawsky","doi":"10.1201/9781003208846-3","DOIUrl":"https://doi.org/10.1201/9781003208846-3","url":null,"abstract":"","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"37 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2021-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85813712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ion Exchange in Countercurrent Columns","authors":"V. Gorshkov","doi":"10.1201/9781003208846-2","DOIUrl":"https://doi.org/10.1201/9781003208846-2","url":null,"abstract":"","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"32 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2021-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76668804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Equilibrium Analysis of Complexation in Ion Exchangers Using Spectroscopic and Distribution Methods","authors":"H. Waki","doi":"10.1201/9781003208846-5","DOIUrl":"https://doi.org/10.1201/9781003208846-5","url":null,"abstract":"","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"140 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2021-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79973314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Evaluation of the Electrostatic Effect on Metal Ion-Binding Equilibria in Negatively Charged Polyion Systems","authors":"T. Miyajima","doi":"10.1201/9781003208846-7","DOIUrl":"https://doi.org/10.1201/9781003208846-7","url":null,"abstract":"","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"5 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2021-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72659336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ion-Exchange Selectivities of Inorganic Ion Exchangers","authors":"M. Abe","doi":"10.1201/9781003208846-9","DOIUrl":"https://doi.org/10.1201/9781003208846-9","url":null,"abstract":"","PeriodicalId":22002,"journal":{"name":"Solvent Extraction and Ion Exchange","volume":"411 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2021-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79905070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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