Showing papers in "Solvent Extraction and Ion Exchange in 2001"
TL;DR: In this paper, six diglycolamide molecules were used for actinide extraction from nitric acid into n-dodecane, and the dependence of the distribution coefficients of Eu(III) and Am(III), on the length of alkyl chain in the extractants was examined.
Abstract: The novel extractants, six diglycolamides synthesized in our laboratory, were investigated for actinide extraction from nitric acid into n-dodecane. The dependence of the distribution coefficients of Eu(III) and Am(III) on the length of alkyl chain in the extractants was examined. Among the diglycolamides studied, N,N,N′,N′-tetraoctyl-3-oxapentanediamide (TOOPDA) and N,N,N′,N′-tetradecyl-3-oxapentanediamide (TDOPDA) showed a sufficient solubility in n-dodecane, due to their appropriate lipophilicity modified by increasing the length of the alkyl chain attached to amidic N atoms. The distribution coefficients, D M, of actinides obtained by TOOPDA increased with an increase in HNO3 concentration. The number of diglycolamide molecules coordinated to the actinide ions was estimated to be three for Th(IV), U(VI), Pu(IV), and four for Am(III) and Cm(III) by slope analysis. The order of D M for the actinides at high nitric acid concentrations is An(III), An(IV) > An(VI) > An(V) and that for lanthanides, heavier ...
620 citations
TL;DR: In this paper, a review of the state-of-the-art reagents and methods for hydrometallurgical partitioning of actinides from different types of transuranium wastes and dissolved fuels is presented.
Abstract: Reagents and methods that have been developed during the past 20 years for hydrometallurgical partitioning of actinides from different types of transuranium (TRU) wastes and dissolved fuels are reviewed. Emphasis is placed on the extraction performance of the fully-optimized reagents rather than on the structural iterations that were undertaken (and in some cases are still being conducted) to identify the optimum species. Particular attention is paid to separation processes that have been demonstrated in batch and counter-current solvent extraction, and batch and column mode extraction chromatography. The salient features of the various techniques and reagents for actinide recycle are compared. Sections of the review focus on neptunium behavior in hydrometallurgy and on characterization of those reagents best suited to the separation of trivalent actinides from fission product lanthanides. Selected flowsheets that have been reported for the separation and recovery of actinides from TRU wastes are presented.
457 citations
TL;DR: A synergistic extraction mixture containing chlorinated cobalt dicarbollide (CCD), carbamoylmethyl phosphine oxide (CMPO), and polyethylene glycol (PEG) has been investigated for the simultaneous recovery of cesium, strontium, lanthanides, and actinides from highly acidic media as discussed by the authors.
Abstract: A synergistic extraction mixture containing chlorinated cobalt dicarbollide (CCD), carbamoylmethyl phosphine oxide (CMPO), and polyethylene glycol (PEG) has been investigated for the simultaneous recovery of cesium, strontium, lanthanides, and actinides from highly acidic media. The extraction properties of this mixture depend on the concentration ratio of the components. For recovery of all major radionuclides, the optimal ratio of [CCD]:[PEG]: [CMPO] = 5:1:1 should be used. The use of diphenyl-N,N-dibutylcarbamoylmethyl phosphine oxide and PEG-400 provides the most efficient recovery of cesium, strontium, lanthanides, and actinides. The possibility of using polyfluorinated ethers, esters, ketones, and sulfones as diluents was examined. Phenyltrifluoromethyl sulfone was the most suitable diluent tested. The use of this diluent allows good extraction properties, chemical and radiation stability, excellent explosion/fire-safety properties, and favorable hydrodynamic characteristics. The extraction of radio...
311 citations
TL;DR: The Universal Extraction (UNEX) process as mentioned in this paper was developed for the simultaneous separation of cesium, strontium, and the actinides from acidic waste solutions.
Abstract: A novel solvent extraction process, the Universal Extraction (UNEX) process, has been developed for the simultaneous separation of cesium, strontium, and the actinides from acidic waste solutions. The UNEX process solvent consists of chlorinated cobalt dicarbollide for the extraction of 137Cs, polyethylene glycol for the extraction of 90Sr, and diphenyl-N,N-dibutylcarbamoyl phosphine oxide for the extraction of the actinides and lanthanides. A nonnitroaromatic polar diluent consisting of phenyltrifluoromethyl sulfone has been developed for this process. A UNEX flowsheet consisting of a single solvent extraction cycle has been developed as a part of a collaborative effort between the Khlopin Radium Institute (KRI) and the Idaho National Engineering and Environmental Laboratory (INEEL). This flowsheet has been demonstrated with actual acidic radioactive tank waste at the INEEL using 24 stages of 2-cm diameter centrifugal contactors installed in a shielded cell facility. The activities of 137Cs, 90Sr, and th...
231 citations
TL;DR: In this paper, the authors investigated the mechanism of M(III) extraction using mixtures of purified Cyanex 301 with neutral O-bearing co-extractants from the standpoint of theoretical chemistry.
Abstract: The mechanism of M(III) extraction (M = Am, Eu) using mixtures of purified Cyanex 301 with neutral O-bearing co-extractants is investigated from the standpoint of theoretical chemistry. The strong coordination of M(III) to soft donor S atoms of Cyanex 301 is shown to be caused by a covalent effect that is significantly greater for Am(III)─S than for Eu(III)─S bonds. The M(III) extractabilities are correlated with the calculated effective charge on O atom in neutral organophosphorous co-extractant molecules. Synergism is explained by the formation of mixed ligand complexes which changes the nature of the M─S bonds due to O → M electron density transfer. Co-extractants which are weak donors strengthen M─S bonds but strong donors weaken them. The 31P NMR chemical shifts of the neutral O-bearing organophosphorous co-extractants, which are correlated with the M(III) extractabilities, confirm the synergism mechanism. Shifts in charge transfer energy in UV-visible absorption spectra of Eu(III) synergistic mixed ...
83 citations
TL;DR: In this article, the extraction behavior of four N,N-dialkylamides with varying alkyl substituents on the α carbon atom with respect to carbonyl group has been investigated.
Abstract: Extraction behavior of four N,N-dialkylamides with varying alkyl substituents on the α carbon atom with respect to carbonyl group, viz. di-(2-ethylhexyl)acetamide (D2EHAA), di-(2-ethylhexyl)propionamide (D2EHPRA), di-(2-ethylhexyl)isobutyramide (D2EHIBA), and di-(2-ethylhexyl)pivalamide (D2EHPVA) toward nitric acid, U(VI), and Th(IV) has been investigated. The conditional acid uptake constant (K H) values for 1:1 species predominant in the acidity range 0.5–3 M HNO3 are in the following order: D2EHAA (0.28±0.03) > D2EHPRA (0.20±0.01) > D2EHIBA (0.15±0.04) > D2EHPVA (0.06±0.002). The stoichiometry of the extracted species of uranium conforms to UO2(NO3)2·2A (where A = amide). The conditional extraction constants (K ex.) for uranium were found to vary in the following order: 34.0±2.0 (D2EHAA) > 5.6±0.4 (D2EHPRA) > 1.2±0.1 (D2EHIBA)>0.51±0.03 (D2EHPVA). Third phase has been observed in the case of D2EHAA (≥1 M HNO3) and D2EHPRA (≥3 M HNO3) in the presence of macro concentration of thorium (220 g/L). The sepa...
67 citations
TL;DR: In this article, the solvent extraction of cerium(IV) and fluorine(I) from simulated sulphuric acid leaching of bastnasite by Cyanex 923 was studied.
Abstract: The solvent extraction of cerium(IV) and fluorine(I) from simulated sulphuric acid leaching of bastnasite by Cyanex 923 was studied. The results showed that Cyanex 923 can extract not only Ce(IV) as Ce(HSO4)2 (SO4) · 2(Cyanex 923) and F(I) as HF · (Cyanex 923) respectively but them together. The extraction mechanism of Ce(IV) together with F(I) can be related to the formation of Ce(HF)(HSO4)2 (SO4) · 2(Cyanex 923). It was also showed that boric acid in the leaching liquor which was added to chelate F(I) wasn't extracted alone by Cyanex 923 and didn't influence the Cerium(IV) extraction. Boric acid can enhance the extraction of HF and came into organic phase in form of (HF)(H3BO3) · (Cyanex 923). Hydrofluoric acid was extracted from the bastnasite leaching mainly together with Ce(IV). The results also showed that temperature didn't affect the extraction process. IR spectra of purified Cyanex 923 saturated with Ce(IV), HF and H3BO3 were discussed.
66 citations
TL;DR: In this article, small angle neutron scattering and visible absorption spectroscopy were used to study the neodymium complexes of a series of acidic organophosphorus extractants in deuterated toluene at high (≥33% theoretical capacity) metal loading.
Abstract: Small angle neutron scattering and visible absorption spectroscopy were used to study the neodymium complexes of a series of acidic organophosphorus extractants in deuterated toluene at high (≥33% theoretical capacity) metal loading. Organic phases containing 0.10 M bis(2-ethylhexyl)phosphoric acid (HDEHP), bis(2,4,4-trimethylpentyl)oxothiophosphinic acid (HC302), or bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HC301) were used. Under these conditions, the neutron scattering experiments show that HDEHP and HC302 exist as dimeric species in the absence of Nd. Extraction of Nd disrupts the dimeric structure of the extractants to form dinuclear complexes with the formula Nd2(DEHP)6 or Nd2(C302)6. In contrast, 0.10 M HC301 is not dimeric in deuterated toluene. At 86% of the theoretical Nd capacity, the extracted complex is also dinuclear with the average formula Nd2(C301)6, but at 46% of the theoretical Nd capacity only the mononuclear complex, Nd(C301)3, is formed. The Nd hypersensitive transitions in th...
63 citations
TL;DR: In this paper, infrared spectra for the TBP n-octane system were analyzed and two extracted species, TBP · HNO3 and TBP· 2HNO3, were identified in the organic phase.
Abstract: Infrared studies for the HNO3/0.73 M TBP n-octane system are reported. Two extracted species, TBP · HNO3 and TBP · 2HNO3, were identified in the organic phase. The concentration of the individual species was determined by the analysis of the vibrational band at ∼1650 cm−1. The band at 1648 cm−1 was assigned to the monosolvate TBP · HNO3 and the band at 1672 cm−1 to the hemisolvate TBP · 2HNO3. The infrared spectra revealed that with respect to the P═O bond, as well to each other, the HNO3 molecules in the hemisolvate are spectrally non-equivalent. The predominant structure of TBP · 2HNO3 involves the chain HNO3 dimer. Some ionic NO3 − and hydronium ions were identified in this system but only during formation of the monosolvate. The analyses performed in this system can serve for the characterization of HNO3 in related systems in the presence of metal species. *Work performed under the auspices of the office of Basic Energy Sciences, Division of Chemical Sciences, Department of Energy, under contract W-31...
55 citations
TL;DR: In this article, an extraction mechanism for V(V) is proposed for primary amine in acidic media, verifying the influence of pH on the process and an industrial multistage process for the treatment of these effluents.
Abstract: Recovery of vanadium from a spent catlaysts leaching process has been studied using primary amine PRIMENE 81R, resulting in an industrial multistage process for the treatment of these effluents. An extraction mechanism for V(V) is proposed for this amine in acidic media, verifying the influence of pH on the process. Adequate ranges for the variables: O/A ratio, organic phase composition, pH, stirring speed and phase separation speed were fixed and simulated in industrial conditions. Vanadium is finally recovered by means of precipitation as ammonium metavanadate and later calcination to obtain vanadium pentoxide of commercial grade.
51 citations
TL;DR: In this paper, the partitioning of long-lived alpha-emitting actinides, present in high-level radioactive waste (HLW) solutions from PUREX reprocessing of spent nuclear fuels, has been carried out using a commercially available, reasonably inexpensive, trialkylphosphine oxide (TRPO), Cyanex®-923 alone or its mixture with tri-n-butylphophosphate (TBP) in dodecane.
Abstract: The partitioning of long-lived alpha-emitting actinides, present in high-level radioactive waste (HLW) solutions from PUREX reprocessing of spent nuclear fuels, has been carried out using a commercially available, reasonably inexpensive, trialkylphosphine oxide (TRPO), Cyanex®-923 alone or its mixture with tri-n-butylphosphate (TBP) in dodecane. The studies have been carried out from nitric acid as well as from three types of synthetic HLW solutions. With 30% TRPO alone, third-phase formation was observed when HLW in 3.0 M HNO3 was taken as such. With the mixture of TRPO and TBP, it has been shown that the HLW need not be diluted 10 times, but only the acidity has to be reduced from ∼3 to ∼1 M (without substantial dilution) to achieve an efficient separation of the minor actinides. The results thus obtained using TRPO has been compared with those already reported while using dihexyl-N,N-diethylcarbamoylmethyl phosphonate, diisodecyl phosphoric acid, and octyl(phenyl)N,N-diisobutylcarbamoylmethylphosphine ...
TL;DR: A series of disubstituted aliphatic amides have been prepared with different substituting groups and the extracting ability for U(VI), Th(IV) and some fission products like Am(III), Zr(IV), Eu(III) and Cs from nitric acid solutions has been studied as mentioned in this paper.
Abstract: A series of long chain disubstituted aliphatic amides have been prepared with different substituting groups and the extracting ability for U(VI), Th(IV) and some fission products like Am(III), Zr(IV), Eu(III) and Cs from nitric acid solutions has been studied. All results were compared with those obtained by using TBP under the same conditions. All prepared amides exhibit higher U-Th separation factors than TBP. Distribution ratios of U(VI) as function of nitric acid concentration, extractants concentration and salting-out agent have been measured by using N,N-dihexyloctanamide (DHOA) and N,N-dihexyl(2-ethyl)hexylhexanamide (DHEHA), which were chosen for further studies. The extraction behviour of U(VI), Th(IV) and Zr(IV) with gamma irradiated DHOA, DHEHA and TBP in toluene from 3 M HNO3 has been studied as a function of absorbed doses. Back extraction of U(VI), Th(IV) and Zr(IV) from organic phases was also studied.
TL;DR: The TRPO process for partitioning actinides from Chinese high saline HLLW was studied in this paper, where the 30% (v/v) TRPO-kerosene was used as extractant.
Abstract: The TRPO process for partitioning of actinides from Chinese high saline HLLW was studied. A hot test was carried out in a countercurrent mode with actual HLLW by using a miniature centrifugal contactor set. This highly saline HLLW was obtained from a reprocessing plant. The 30%(v/v) TRPO-kerosene was used as extractant. The feed solution was the 2.7 times diluted HLLW and its HNO3 concentration was 1.08 mol/L. The results of the hot test were very attractive. Actinides as well as 99Tc were effectively separated from the HLLW by TRPO extraction. The decontamination factors (D.F) for total α and 99Tc activities are 588 and 125 respectively. Am, Np/Pu, and U were well stripped by 5.5 mol/L HNO3, 0.6 mol/L H2C2O4 and 5% Na2CO3, respectively. Their separation was very efficient, and cross contamination was very low. After partitioning the HLLW become a non-α waste.
TL;DR: In this article, the authors focused on the recent advances, mainly achieved during the past ten years on the solvent extraction separation of mercury from aqueous solutions using macrocyclic ligands such as calix[n]arene derivatives and crown ethers.
Abstract: This work is focused on the recent advances, mainly achieved during the past ten years on the solvent extraction separation of mercury from aqueous solutions using macrocyclic ligands such as calix[n]arene derivatives and crown ethers.
TL;DR: In this paper, the authors studied the recovery of phenol from aqueous solutions with CYANEX® 923 and three membrane extraction-stripping systems (bulk liquid membranes, three-phase hollow fiber contactor and two hollow fiber modules set-up).
Abstract: The recovery of phenol from aqueous solutions with CYANEX® 923 was studied. Classical dispersive extraction and three membrane extraction-stripping systems (bulk liquid membranes, three-phase hollow fiber contactor and two hollow fiber modules set-up) were used. It was found that CYANEX® 923 was a convenient carrier for recovery of phenol from aqueous streams in extraction-stripping membrane processes. The problem of emulsion formation, so important in dispersive extraction, was avoided. Both mass transfer experiments in different membrane systems and measurement of the dynamic interfacial tension demonstrated importance of the interfacial phenomena occurring in the stripping stage. A blocking of this interface was observed that resulted in a decrease of phenol mass transfer.
TL;DR: SXFIT as discussed by the authors is the latest in a series of programs designed to model solvent extraction systems of increasing complexity, allowing the user complete freedom to define the constituents from which the composition of each phase is to be specified in the data and from which all species of a model for a system are to be formed.
Abstract: SXFIT is the latest in a series of programs designed to model solvent extraction systems of increasing complexity. Unlike its predecessors, SXFIT permits the user complete freedom to define the constituents from which the composition of each phase is to be specified in the data and from which all species of a model for a system are to be formed. This paper describes the manner in which the physical chemistry of the nonaqueous and aqueous solutions involved has come to be treated in this modelling effort. Included are: (1) solute activity coefficients and solvent activity in the nonaqueous phase, estimated by the Scatchard-Hildebrand-Scott treatment; (2) the effect of ionization on these quantities; (3) solute activity coefficients and water activity in the aqueous phase, estimated by the Pitzer treatment; (4) the effect of non ideal behavior on the total concentration of nonaqueous solute species as rendered by a vapor pressure osmometer; (5) a similar treatment of heats of mixing of nonaqueous solutions;...
TL;DR: In this article, the effect of the alkyl group structure of dialkyldithiophosphinic acid on the separation of Am(III) from Ln(III).
Abstract: As a part of the study on the separation of Am(III) from Ln(III) by using dialkyldithiophosphinic acid as extractant, the method of preparing and purifying several dialkyldithiophosphinic acids was studied and the effect of alkyl group structure of dialkyldithiophosphinic acid on separating Am(III) from Ln(III) was investigated. A three-step process under mild conditions which can be easily performed in the laboratory was developed. By the method with diethyl phosphite and alkylhalide as starting materials, five kinds of dialkyldithiophosphinic acid(alkyl = octyl, 1-methylheptyl, 2-ethylhexyl, heptyl and hexyl) were synthesized. With four kinds of dialkyldithiophosphinic acids (HA) with different alkyl group of C8(alkyl = n-octyl, 1-methylheptyl, 2-ethylhexyl, 2,4,4-trimethylpentyl) as extractants and toluene as diluent, the dependencies of extracting Am(III) and Ln(III) on pH and extractant concentration were determined. The slopes of lgD/pH dependencies are close to 3 and the slopes of lgD/lg[HA] are cl...
TL;DR: In this paper, solvent polarity measurements reveal that the cesium extraction strength afforded by solutions composed of calix[4]arene-bis-(tert-octylbenzocrown-6) at 0.005 M in 1,2-dichloroethane containing a variety of novel alcohol phase modifiers at0.25 M correlates well with the hydrogen-bond donor ability of the alcohol.
Abstract: Solvatochromic solvent polarity measurements reveal that the cesium extraction strength afforded by solutions composed of calix[4]arene-bis-(tert-octylbenzocrown-6) at 0.005 M in 1,2-dichloroethane containing a variety of novel alcohol phase modifiers at 0.25 M correlates well with the hydrogen-bond donor (HBD) ability of the alcohol. The alcohols comprise a small library of derivatives of 2-(4-tert-octylphenoxy)-1-ethanol, in which the alcohol carbon atom contains a substituent of variable electron-withdrawing ability. The betaine dye 4-(2,4,6-triphenylpyridinium)-2,6-diphenylphenoxide, also known as Dimroth-Reichardt dye #30, was used to obtain ET(30) and ET N values. Alcohols containing substituents with fluorine atoms gave rise to both higher ET N values and higher cesium distribution values. The trend observed in HDB parallels the expected trend in alcohol acidity. †This research was sponsored by the Office of Science, Office of Basic Energy Sciences, U.S. Department of Energy, under contract number ...
TL;DR: In this article, a linear relationship between stirring rate and fluxes was found for both lanthanides and americium and two sets of extraction rates were observed within the lanthanide series.
Abstract: Studies were made on the kinetics of lanthanide(III)/actinide(III) co-extraction with N,N′-dimethyl-N,N′-dibutyltetradecylmalonic diamide (DMDBTDMA), which is an extraction system for partitioning of high level liquid nuclear waste (HLLW). Extraction rates were measured in a stirred cell. A linear relationship between stirring rate and fluxes was found for both lanthanides and americium. This indicates that mass transfer is controlled by diffusion. Two sets of extraction rates were observed within the lanthanide series. The extraction rates for La(III), Ce(III) and Pr(III) are about 50% higher than for the heavier lanthanides investigated (Nd(III), Sm(III), Eu(III)). The Am(III) extraction rate was found near those of the lighter lanthanides.
TL;DR: In this article, the distribution coefficient for alkali-metal cations was determined in a competitive extraction system at different pH levels for caesium from simulated radioactive waste in the presence of a large excess of sodium.
Abstract: Control of the reaction conditions during the alkaline polycondensation of resorcinol with formaldehyde leads to polymeric resins with improved capacity toward caesium. The resins obtained are characterized by determining their moisture regain and ion-exchange capacity. The distribution coefficient (D) for alkali-metal cations are determined in a competitive extraction system at different pH. The alkali-metal cation sorption selectivity series is strongly influenced by the pH of the solution. Two kinds of mechanism can explain these selectivity series. Extraction of caesium from simulated radioactive waste was studied at different pH in the presence of a large excess of sodium. The study also includes the kinetic and the ion-exchange capacity for caesium of the sodium form of the resins.
TL;DR: In this article, the extraction behavior of molybdenum(VI) under the conditions of transuranium extraction (TRUEX) process was studied by using octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide.
Abstract: The extraction behavior of molybdenum(VI) under the conditions of transuranium extraction (TRUEX) process was studied by using octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide. The extraction behavior of molybdenum(VI) under the condition of PUREX process was also investigated for comparison. The extraction of molybdenum with the copresence of uranium(VI), dysprosium(III), and the effect of oxalic acid were examined. Under the PUREX conditions, molybdenum was less extractable, while under the TRUEX process conditions, a higher distribution ratio of molybdenum was observed. Under the TRUEX conditions, the addition of oxalic acid was effective in depressing molybdenum extraction. It was concluded that, at the concentration of nitric acid around 1 mol dm−3 or higher, Mo(VI) is extracted predominantly as cationic species, while at lower concentration of nitric acid, the coextraction of anionic molybdenum as a mixed complex with other metal, that is, UO2 2+, occurs.
TL;DR: In this paper, a new extractant with an NS donor chromophore viz. 2-(1-ethylthiomethyl)-1-decyl imidazole (ETDIMZ) has been synthesized.
Abstract: A new extractant with an NS donor chromophore viz. 2-(1-ethylthiomethyl)-1-decyl imidazole (ETDIMZ) has been synthesized. Its extraction behavior towards each of Co2+, Ni2+, Cu2+, and Zn2+ in each of perchlorate, chloride and thiocyanate media in dilute acid media have been studied. Its behavior was compared with a similar pyridine derivative, viz. 2-(octylthiomethyl)-pyridine (OTMP) under comparable conditions. These behaviors have been interpreted in terms of the coordination chemistry of the metal ions. It was shown how formation constants of simple ligands, symmetry of the complex species and phase transferability can influence extraction behavior and how the above parameters can assist in the development of metal ion specific extractants.
TL;DR: In this paper, the DEHAN was used for the simultaneous separation of neptunium and plutonium from uranium in contactor 2D using N,N-diethylhydroxylamine as a salt-free reductant.
Abstract: Cascade extraction of uranium and cascade extraction-separation of uranium/neptunium and uranium/plutonium with 6 extraction stages and 6 stripping stages have been studied in the presence of N,N-diethylhydroxylamine (abbreviated as DEHAN) in nitric acid medium according to the experimental conditions of the purification cycle of uranium (referred to as contactor 2D) of the second cycle of the Purex Process. The percent recovery and material balance of U(VI) were found to be 99.997% and 101.5%, respectively. The decontamination factors and material balances of neptunium and plutonium from uranium were found to be 32.4, 25.3 and 102.5%, 105.7%, respectively. It suggests that the simultaneous separation of neptunium and plutonium from uranium is technically feasible for contactor 2D using N,N-diethylhydroxylamine as a salt-free reductant.
TL;DR: In this paper, a countercurrent multistage extraction flowsheet was presented extracting with a mixture of purified Cyanex 301 and TBP, which consisted of 12 stages, 7 for extraction, 3 for washing and 2 for stripping the Am from lanthanides.
Abstract: Distribution ratios of Am and lanthanides (Pr, Nd, Eu) increase with pH value and decrease with lanthanide concentrations in aqueous phase, exhibiting a separation factor as high as 200 in presence of macro amount lanthanides. A countercurrent multistage extraction flowsheet was presented extracting with a mixture of purified Cyanex 301 and TBP. It consisted of 12 stages, 7 for extraction, 3 for washing and 2 for stripping the Am from lanthanides. With the flowsheet, >99.998% of the Am was extracted. The product flow was only contaminated <0.04% of the lanthanides.
TL;DR: A prototype information system for solvent extraction of metals including a comprehensive factual database and an expert system to analyse experimental extraction data are designed, using the Substructural Molecular Fragments method.
Abstract: This article concerns the design of a prototype information system for solvent extraction of metals including a comprehensive factual database and an expert system to analyse experimental extraction data. A demonstration version of the solvent extraction database is described. Each database record corresponds to one extraction equilibrium and contains three information parts (bibliographic, extraction system description and extraction properties) including chemical structural 2D and 3D information for extractants, as well as thermodynamic and kinetic data in textual, numerical and graphical forms. As expert system we use the Substructural Molecular Fragments method which models structure-property relationships using information retrieved from the database. Its performance is assessed on the distribution ratios of Hg, In and Pt extracted by 26 phosphoryl-containing monopodands, and of uranium extracted by 32 mono- and tripodands or by 22 monoamides.
TL;DR: The polymeric resins with methylenediphosphonate and carboxymethylphosphonates ligands in the ethyl ester form have been synthesized, characterized and used in the removal of Au(III) from hydrochloric acid solutions as discussed by the authors.
Abstract: The polymeric resins with methylenediphosphonate and carboxymethylphosphonate ligands in the ethyl ester form have been synthesized, characterized and used in the removal of Au(III) from hydrochloric acid solutions. It has been found that they are able to adsorb as much as 130–166 mg Au/g of the resin at high concentration of the external solutions. At low concentrations affinity of resins towards gold is very good and the obtained distribution coefficient logarithm is in the range of 4.0–4.4 for the 1×10−4 M Au(III) in 0.25–6.0 M hydrochloric acid solutions. Other metals chlorocomplexes such as Fe(III), Pd(II), Pt(II) and Ag(I) are removed to a lesser extent and the resins do not recognize Cu(II) chlorocomplexes. This allows for the use of the synthesized resins in the selective removal of Au(III) from the concentrated copper solution typically obtained in the processing of the electronic scrap. It has been possible to treat more than 1900 bed volumes of such solution (1×10−4 M Au(III) and 1×10−2 M Cu(II...
TL;DR: The influence of the molecular structure of amides on the third phase formation in the extraction of uranium and nitric acid was investigated in this article, where nine amides namely, dibutyl hexanamide (DBHA), di iso-octyl butanamide(DiBHA), DBOA, DHHA, DDA, di n-hexanamide, DiOBA, DiBHA, and DOHA were synthesized and used.
Abstract: The influence of the molecular structure of amides on the third phase formation in the extraction of uranium and nitric acid was investigated. Nine amides namely, dibutyl hexanamide (DBHA), diisobutyl hexanamide (DiBHA), dibutyl octanamide (DBOA), dihexyl hexanamide (DHHA), dibutyl dodecanamide (DBDA), diiso-octyl butanamide (DiOBA), di n-octyl isobutanamide (DOiBA), di n-octyl butanamide (DOBA), and di n-octyl hexanamide (DOHA) were synthesized and used. The limiting organic concentration (LOC) of uranium (VI) for third phase formation was studied as a function of nitric acid concentration using 0.5 M solutions of these amides in dodecane. The LOC for extraction from neutral medium (with near zero free acidity) was also measured at four different temperatures. The LOC values were found to increase in general with an increase in the total number of carbon atoms in the amide from 14 to 22. The LOC values of DBHA (C. No. 14), DiBHA (C. No. 14), DBOA (C. No. 16) were lower compared to that of DHHA (C. No. 18...
TL;DR: In this article, the extraction behavior of cobalt and nickel from sulfate solutions with bis(2-ethylhexyl) phosphinic acid (PIA-8) in toluene has been studied.
Abstract: The extraction behaviour of cobalt(II) and nickel(II) from sulfate solutions with bis(2-ethylhexyl) phosphinic acid (PIA-8) in toluene has been studied. Quantitative extraction of Co(II) was observed at pH 5.0–5.9 while that of Ni(II) at pH 6.8–7.0 with 0.03 M PIA-8 in toluene. The difference in pH0.5 for Co(II) and Ni(II) was 1.9. The stoichiometry of the extracted species were determined by slope analysis method. The extraction reaction proceeds by cation exchange mechanism and the extracted species were Co · R2(HR)2 and Ni · R2 · 2(HR)2. Temperature dependance of the extraction equilibrium constants were determined to estimate the apparent thermodynamic functions (ΔG, ΔS and ΔH). The method was used for separation of cobalt(II) and nickel(II). Cobalt(II) was separated from nickel even at 1:20 (Co:Ni) ratio. The separation of cobalt(II) from nickel(II) was favoured with the increase in temperature.
TL;DR: In this paper, the extraction of Am(III, U(III), U(VI), Th(IV), and Fe(III) by P,P′-di(2-ethylhexyl) methylene- (MDP), ethylene- (H2DEH[EDP]), and butylene- diphosphonic acids dissolved in the monomerizing diluent 1-decanol has been investigated.
Abstract: In this work, the extraction of Am(III), U(VI), Th(IV) and Fe(III) by P,P′-di(2-ethylhexyl) methylene- (H2DEH[MDP]), ethylene- (H2DEH[EDP]), and butylene- (H2DEH[BuDP]) diphosphonic acids dissolved in the monomerizing diluent 1-decanol has been investigated. A comparison of the acid dependencies with those observed in o-xylene has revealed a number of novel features which have been ascribed to extraction of metal nitrates through a solvation mechanism made possible by facile transfer of nitrate ions into the 1-decanol phase. The use of 1-decanol as the diluent gives rise to strong suppression of metal extraction, which increases along the series Fe(III)
TL;DR: In this article, the retention of plutonium by irradiated 30% trialkylphosphine oxide (TRPO) in kerosene was investigated and the reasons for plutonium retention were investigated.
Abstract: Extraction and retention of plutonium by irradiated 30% trialkylphosphine oxide (TRPO) in kerosene were investigated. Factors that influence the retention of plutonium are discussed. The experimental results show that when 30% TRPO–kerosene–HNO3 is irradiated above a dose of 2 × 106 Gy, it produces a few Pu-complexing radiolytic degradation products. Radiation dose was the primary factor affecting retention of plutonium in the organic phase. At a radiation dose of 5 × 106 Gy, about 40% of the plutonium extracted by the solvent was left in the organic phase even after five back-extraction contacts with 0.6 mol/L oxalic acid. The reasons for plutonium retention were investigated. The products causing the retention were the polymeric ones with high molecular weight, and these were recovered by vacuum distillation of the irradiated 30% TRPO–kerosene. The phosphonic and phosphinic acids produced by irradiation of TRPO had no effect on the retention of plutonium.