One of the challenges of implementing a sustainable Partitioning and Transmutation (P&T) strategy in the nuclear fuel cycle is the development of a solvent extraction system for the selective separation of Am. One of the latest developments is the Americium Selective (AmSel) extraction system, a two-step process based on a lipophilic diglycolamide and a hydrophilic, sulfonated bistriazinyl bipyridine. However, this process has as a drawback the presence of sulfur in the hydrophilic complexant, making it unsuitable within a CHON strategy. This study presents a sulfur-free "CHON" variant of the AmSel process, replacing TODGA with N,N-dipentyl-N',N'-didodecyldiglycolamide (PnDdDGA), and replacing SO3-Ph-BTBP with either 3,3 '-([2,2 '-bipyridine]-6,6 '-diylbis(1H-1,2,3-triazole-4,1-diyl))bis(propan-1-ol) (PrOH-BPTD) or 3,3 '-((1,10-Phenanthroline-2,9-diyl)bis(1H-1,2,3-triazole-4,1-diyl))bis(propane-1,2-diol) (BTrzPhen-tetraol). The latter two molecules are a hydrophilic bipyridine and phenanthroline, respectively. Both the organic and aqueous phases were optimized, and extraction tests were performed with a simulated highly active raffinate solution. Efficient separation of Am(III) from Cm(III) was feasible with both ligands, with SFCm/Am values of around 2.2. although the limited solubility of PrOH-BPTD requires lowering of the DGA concentration for stripping to occur. Demonstration on a simulated PUREX HAR lowered SFCm/Am values to around 1.9, and showed separating Am(III) from most fission products was possible. Separating Am(III) from La(III), Ce(III), and Pr(III) was not feasible in the stripping step, and necessitated an intermediary scrubbing step for the (light) lanthanides.
Solvent extraction involves coupled phenomena that strongly affect the performance at large scale. Given the urgent need to reduce process development costs and time in the hypercompetitive context of recycling, it is essential to adapt our R&D methodology, historically based on large-scale pilot tests. In this context, we have proposed to predict the drop size distribution in liquid-liquid contactors based on small-scale instrumented experiments, and proper numerical simulations. This method was tested on a case of industrial interest, the recovery of copper, considering the actual process fluids (although mass transfer was not considered) and a scale jump of 40 in volume. Tests carried out in a semi-industrial mixer-settler at Umicore's facilities in Olen revealed a quite satisfactory agreement between measurements and predictions, hence validating the relevance of the proposed approach in order to guide industrial transposition and provide early stage-evaluation of relevant performance criteria such as interfacial area and phase entrainment due to tiny droplets. The benchmark also highlighted the need to reduce the empiricism of the models used in population balance equations to describe droplet breakup and coalescence under real conditions, in order to facilitate the transposition from one chemical system to another.
A novel polydentate neutral organophosphorus ligand N,N'-(2,2-dimethylpropane-1,3-diyl)bis(2-(diphenylphosphoryl)acetamide) containing two Ph2P(O)CH2C(O)NH- bidentate moieties connected by a 2,2-dimethylpropyl bridge through amide nitrogen atoms was synthesized and studied as an extractant for lanthanides(III) ions from HNO3 solutions. The extraction ability of this compound is significantly higher than that of its analogue with a trimethylene bridge between the coordinating CMPO groups and several orders of magnitude higher than that of its monoanalogue. The influence of composition of aqueous and organic phases on the Ln(III) extraction was elucidated and stoichiometry of the complexes extracted was determined. The extraction of Ln(III) by compound I increases in the series of acids HCl << HNO3 < HClO4 < HTf2N in accordance with the increasing hydrophobicity of their anions. At an equal aqueous concentration of HNO3, the D-Ln values in the system with bis(trifluoromethylsulfonyl)imide based ILs are higher than those obtained with molecular diluents. The D-Ln values at the Ln(III) extraction with a bisCMPO solution in the presence of an additive of 0.05 M [C(4)mim][Tf2N] increase by more than three orders of magnitude, whereas when using undiluted IL, this increase is significantly less. The synergic enhancement of the Ln(III) extraction produced by bisCMPO - [C(4)mim][Tf2N] mixtures may be associated with the participation of hydrophobic Tf2N- anions in the formation of extractable Ln(III) complexes.
Direct lithium extraction from aqueous solutions is essential for the valorization of primary resources and the recycling of secondary sources, yet conventional methods raise environmental and efficiency concerns. This study investigates lithium solvent extraction using a neat hydrophobic ionic liquid, 1-butyl-3-methylimidazolium nonafluorobutanesulfonate ([Bmim][NfO]), without any added extractants. Lithium distribution ratios were measured as a function of contact time, initial lithium concentration, and aqueous acidity. Extraction kinetics were found to be rapid, and lithium recovery reached up to 50% under optimized conditions. The ionic liquid anion was identified as the key factor governing extraction efficiency. Analysis of experimental trends indicates that lithium extraction proceeds predominantly via ion pairing with the IL anion, with additional but smaller contribution from cation exchange, while neutral lithium chloride extraction occurs only at high aqueous lithium concentrations. A chemical equilibrium model accurately reproduces the experimental data and confirms the dominant role of ion pairing through the corresponding equilibrium constant. Owing to its ability to extract lithium without molecular extractants, [Bmim][NfO] serves as a valuable reference system for mechanistic and thermodynamic analysis. These results provide new insights into direct lithium extraction with neat ionic liquids and offer guidance for the rational design of more sustainable extraction systems.
Four commercially available resins, Bio-Rad AG (R) MP-1 M, Lewatit (R) MonoPlus MP 500, Reillex (TM) 425, and Reillex (TM) HP were examined alongside Reillex (TM) HPQ, which is no longer commercially available at the time of this publication, for their ability to remove Pu(IV) from HNO3 solutions. Batch Pu(IV) distribution ratios (K-d) of the five resins were measured in 0.35 M, 3.0 M, and 8.0 M HNO3 after a 24-h contact period. Lewatit (R) MonoPlus MP 500, Reillex (TM) HP, and Reillex (TM) HPQ exhibited high uptake of the analyte at 8.0 M HNO3. AG (R) MP-1 M had a K-d > 10(2) in the 0.35 M HNO3 solution. The Reillex (TM) resins demonstrate no detectable uptake at 0.35 M HNO3, while Lewatit (R) MonoPlus MP 500 exhibits low uptake (K-d ca. 10(1)) under the same conditions. Distribution ratios in 8.0 M HNO3 for Lewatit (R) MonoPlus MP 500, Reillex (TM) HP, and Reillex (TM) HPQ were further determined after 1-h of contact. Lewatit (R) MonoPlus MP 500 and Reillex (TM) HP had similar distribution ratios under these conditions. Finally, Reillex (TM) HP was directly compared against Reillex (TM) HPQ to determine Pu(IV) capacity. The capacity of Reillex (TM) HP for Pu(IV) was found to be approximately 84% of the capacity of Reillex (TM) HPQ, 84-87 and 101-103 g Pu/L resin, respectively.
The removal of radiocesium from Hanford tank waste supernate is a critical step in preparing feed for low-activity waste immobilization and directly impacts downstream processing efficiency and waste acceptance criteria. This study evaluated cesium ion exchange performance using crystalline silicotitanate (CST) media through a series of targeted experiments designed to quantify the influence of waste matrix variability on both equilibrium capacity and mass transfer behavior. Tank waste supernate subsampled from five Hanford double-shell tanks encompassed a range of sodium, hydroxide, nitrate, and nitrite concentrations in order to assess the impact of feed variability on the performance of the ion exchange performance under relevant process conditions. Both equilibrium batch contact tests and dynamic column experiments were conducted to determine cesium distribution coefficients, effective sorption capacity, and breakthrough behavior under prototypic operating conditions. Results indicated that effective cesium capacity varied by up to a factor of five across the matrices tested, with elevated sodium concentrations significantly suppressing cesium uptake due to competitive ion exchange effects. Kinetic behavior was similarly matrix-dependent, with solution viscosity contributing to a two-fold variation in mass-transfer rates. These results demonstrate the strong dependence of CST ion exchange performance on waste composition and must be incorporated into predictive models for future treatment system design and optimization.
Densities of hydrocarbons (heptane; C7H16, isooctane; C8H18, benzene; C6H, toluene; C7H8), aromatic sulfur compound (thiophene; C4H4S), aromatic nitrogen compounds (pyrrole; C4H5N, pyridine; C5H5N, indoline; C8H9N, quinoline; C9H7N) and deep eutectic solvent from the mixture of tetrabultyl ammonium bromide and decanoic acid ([TBAB:2 DA]) at 1:2 molar ratio were measured at temperatures from 298.15 K to 343.15 K. Similarly, the density of the binary mixture of toluene (1) + heptane (2), thiophene (1) + heptane (2), pyridine (1) + heptane (2), [TBAB:2 DA] (1) + heptane (2), thiophene (1) + isooctane (2), isooctane (1) + [TBAB:2 DA] (2), [TBAB:2 DA] (1) + thiophene (2), toluene (1) + isooctane (2), pyridine (1) + isooctane (2), thiophene (1) + toluene (2), and isooctane (1) + benzene (2) were measured over the whole mole fractions at temperatures from 298.15 K to 343.15 K. Further, liquid-liquid extraction (LLE) was conducted to remove thiophene from heptane, and isooctane using {[TBAB:2 DA]} at 298.15 K. The extraction performance of [TBAB:2 DA] was characterized by the distribution coefficient (D), and selectivity (S). [TBAB:2 DA] gave D and S for both the systems as 17.42 and 1322.98 and 74.21 and 370551.92, respectively. Finally, the extraction mechanisms were analyzed and confirmed that [TBAB:2 DA] could extract thiophene from straight chain and branched chain hydrocarbons during the desulphurization process.
The extraction of Co from an industrially treated solution produced from spent NMC9.5.5 lithium-ion batteries was investigated using saponified Cyanex 272. The phase behavior of a NaOH (2, 5 or 10 M)-Cyanex 272-Isopar L system was studied to select suitable conditions for saponification. A Winsor II region, a monophasic microemulsion area, and a zone with a biphasic system composed of a diluent-rich and a diluent-depleted phase were identified. Both the extractant and NaOH concentration were found to impact the self-assembly of the system, whereas increasing the temperature from 21 to 40 degrees C did not result in any noticeable macroscopic effect. 10 M NaOH solution was selected for saponification. About 95% of Co was extracted from the feed solution using 45% saponified 0.3 M Cyanex 272 in single-stage extraction (pH = 5.5 +/- 0.1). The McCabe-Thiele method showed to be inaccurate in determining the number of counter-current stages when the saponified solvent was used. Two stages were instead predicted for extracting Co using a non-saponified solvent maintaining the pH equal to 5.5 in each stage. Pseudo counter-current tests were performed using both saponified and non-saponified solvents. The results showed similar Co extraction (>99%) but different pH profiles in the cascades.
Efficient separation of Sr from multi-element mixtures is crucial in various industrial processes, including nuclear waste management. In this study, the solvent extraction behavior of Sr using a crown ether extractant, DtBuCH18C6, was systematically investigated with particular emphasis on controlling acid co-extraction using a 1-octanol/dodecane mixed solvent. The results revealed that increasing the 1-octanol volume ratio enhanced Sr extraction, which is attributed to improved solvation of the extractant and stabilization of extracted Sr species in the organic phase. However, this also led to the co-extraction of nitric acid, significantly hindering back-extraction of Sr due to acid accumulation in the organic phase. In contrast, reducing the 1-octanol content suppressed acid loading of the organic phase and facilitated efficient Sr back-extraction. Slope analysis indicated that the apparent dependence of Sr extraction on nitric acid concentration varied with solvent composition, reflecting changes in the extraction environment. Moreover, separation factors of Sr against various coexisting metals, including Ba, Mo, and Ag were evaluated. Back-extraction experiments under multi-element conditions demonstrated that a 1-octanol content of 10% provided high Sr stripping efficiency ( > 90%) in the recovered aqueous phase. The findings highlight solvent composition control as a complementary design parameter for achieving high Sr selectivity and recovery in separation systems treating complex multi-element solutions.
The CHALMEX (Grouped ActiNide Extraction) process, derived from the GANEX process, aims to improve upon existing nuclear fuel recycling methods by co-extracting all the actinides in one step. In this study, the use of dibutyl octanamide (DBOA) as an alternative extractant to Tributyl phosphate (TBP) in the CHALMEX process is demonstrated. A solvent extraction system composed of DBOA, FS-13, and CyMe4-BTBP was tested. Promising performance of DBOA in extracting tetravalent Pu(IV) and hexavalent U(VI) was observed. The distribution ratios for Pu(IV) were significantly higher than those achieved with TBP, indicating improved actinide recovery efficiency. Future investigation of this behavior under high loading conditions would provide valuable insights into the applicability of this system for Pu-rich raffinate in the GANEX second cycle. The radiolytic stability of DBOA was investigated up to 300 kGy, and distribution ratios showed dose-dependent changes. However, some challenges remain, notably the slight increase in co-extraction of lanthanides by CyMe4-BTBP compared with the TBP system, as well as the need for further optimization of hydrodynamic properties to ensure efficient phase separation. Despite these issues, the results build upon existing research by showing the strong potential of DBOA to address key limitations of conventional extractants, particularly in the CHALMEX process.
A description of the EXTREQ-2 software package for the MS Windows XP/Windows 7 operating system is presented. This package is designed for the mathematical modeling of extraction isotherms for a single component using mixtures of two extractants. The EXTREQ-2 program can automatically evaluate up to 6 extracted complex compositions simultaneously. The software allows selection of the composition of extracted complexes in synergistic and binary extraction, calculation of thermodynamic extraction constants and hydration parameters for each extracted complex, as well as determination of the equilibrium concentrations of the extracted complexes and extractants in the organic phase. The organic phase compositions obtained from all examined systems were found to be entirely consistent with the independent physicochemical analyses of the extracted complexes documented in previous studies in the literature. The EXTREQ-2 software suite employs a hybrid optimization approach to improve both user-friendliness and computational accuracy. Several optimization methods, including a Genetic Algorithm, Simulated Annealing, and "Pattern Searching", were independently evaluated and tested. The following results were obtained: Simulated Annealing: 3.67% (calculation speed comparable to Nelder-Mead); Pattern Search: 7.74% (the fastest method); Genetic Algorithm: 3.38% (the slowest); Our utilized Nelder-Mead method: 3.29%. The EXTREQ-2 software package is capable solely of determining the composition of extractable substances within a given extraction system and calculating the thermodynamic parameters associated with every extraction reaction taking place in that system.
The recovery of valuable vanadium (V) and molybdenum (Mo) from spent residue hydrogenation catalysts is crucial due to their high content. However, their efficient separation from the catalyst leaching solution remains challenging. This study investigates a single-stage extraction and stripping process for V and Mo recovery. Under the optimal conditions with 20 vol% of the extractant Aliquat 336, 10 vol% of the phase modifier n-octanol, and an initial aqueous phase pH of 1.0, V and Mo could be effectively extracted, with a distribution ratio of V being 7.02 and that of Mo greater than 1000. The separation factors of V relative to other impurity elements exceeded 360, while those of Mo with respect to impurity elements were greater than 10,000. Afterwards, selective stripping of V was achieved based on its valence state change using an ascorbic acid (VC)-H2SO4 solution. Mo was subsequently stripped with an NH4HCO3 solution. Applied to an actual leaching solution, this process achieved extraction efficiencies over 99.9% for both metals via a four-stage extraction process, with the co-extraction of impurities below 4.50%. A three-stage stripping with 0.3 mol/L VC-0.5 mol/L H2SO4 yielded V stripping efficiency over 99.9% andminimal Mo costripping efficiency of 1.22%. Subsequently, 99.9% of the retained Mo was recovered using NH4HCO3. Therefore, this study provides an efficient strategy for V and Mo recovery, which has significant practical implications for the sustainable management of spent catalysts.
The extraction behavior of rare earth elements (RE) with 4-isopropyltropolone (Hipt) into toluene was systematically investigated by distribution ratio measurements and electrospray ionization mass spectrometry (ESI-MS) analysis. A clear ion-size dependence was observed: Sc(III), Lu(III), and La(III) were predominantly extracted as monomeric, dimeric, and trimeric complexes, respectively. Based on equilibrium analysis and ESI-MS data, the extracted species were identified, and the equilibrium constants determined for these species successfully reproduced the experimental distribution data, confirming the validity of the proposed extraction models. A comparison with a previously reported chloroform system revealed that trimeric La(III) complexes, which were not observed in chloroform, were stabilized in toluene. This result highlights the strong influence of the organic solvent environment on extraction equilibria and the stabilization of polynuclear species. Although adduct complexes such as Sc(ipt)3Hipt and Lu(ipt)3Hipt were clearly observed in the ESI-MS spectra, their extraction constants could not be determined from equilibrium analysis, suggesting that they are artifacts formed during the ionization process. Quantitative evaluation further indicated that polynuclear complexes partially decomposed upon ionization, leading to an apparent enrichment of monomeric species in the spectra. These findings highlight the ion-size-dependent nature of RE(III) extraction with Hipt, the solvent-dependent stabilization of polynuclear complexes, and the need to account for ionization effects when interpreting ESI-MS data in solvent extraction studies.
Rapid nuclear forensics analysis requires elemental separation from complex matrices, including mixed actinide, lanthanide, and transition metal species. While existing methods, such as solvent extraction and ion exchange chromatography, are well-established for separating actinides and lanthanides, the separation of activated transition metals is also crucial. Considerable effort was devoted to developing and optimizing organophosphorus extractants, such as tri-n-butyl phosphate (TBP), to effectively separate and remove actinides and lanthanides from used fuel. This work investigates the fundamental chemistry of iron(III) extraction by TBP system from nitrate and chloride media, using Fe-59. The coordination of the metal species was determined through XAS, IR, and NMR spectroscopy. The stoichiometry of the extracted complex was determined through graphical slope analysis, titrations, and neutron activation analysis. The extraction thermodynamics were determined by a van't Hoff analysis. Results show optimum Fe extraction with concentrated TBP from HNO3 concentrations above 14.5 M or 4-8 M HCl. Data suggest that the extracted species from HNO3 is [Fe(NO3)(3)TBP + 2HNO(3)TBP], with octahedrally coordinated Fe(III). The proposed extracted species from HCl is [HFeCl4TBPHCl], with Fe(III) tetrahedrally coordinated. Both extraction processes are spontaneous and enthalpy-driven in highly acidic conditions. This research improves our ability to predict and optimize separation processes, which can be applied to various fields, including industry, environmental remediation, and nuclear applications, to achieve more efficient outcomes.
Conventional removal of oxalate from plutonium oxalate supernatant is typically carried out through oxidation using potassium permanganate, followed by neutralization with hydrogen peroxide. While effective, this approach results in the generation of large quantities of secondary solid waste and a significant increase in solution volume, posing challenges for downstream waste management. In the present study, an advanced and integrated process strategy is proposed, which combines Mn-2(+)-catalysed oxalate destruction with formaldehyde-mediated denitration, followed by in-situ concentration through evaporation within a single pot-type reactor. This integrated methodology eliminates the need for additional reagents apart from trace levels of Mn-2(+) catalyst and leads to a substantial reduction (approximately 80-90%) in secondary solid waste generation compared to conventional practices. Laboratory-scale experiments were conducted to determine key process parameters such as residence time and steady-state oxalate concentration, and the results were systematically compared with predictions from a Continuous Stirred Tank Reactor (CSTR) model. The strong agreement between experimental observations and model predictions validates the robustness and applicability of the CSTR framework. Model analysis further indicates that, for a recovery (RA) cycle evaporator, operation with 0.005-0.010 M Mn-2(+) enables near-complete oxalate destruction (residual oxalate <= 0.008 M) along with effective volume reduction, offering directly scalable parameters for industrial deployment.
The increasing demand for light rare earth elements (LREEs), including lanthanum (La), cerium (Ce), praseodymium (Pr), and neodymium (Nd), motivates the development of solvent extraction predictive models to design a more efficient separation system. However, LREEs solvent extraction reactions with D2EHPA or PC88A are usually assumed to follow M3++3HA2 & oline; MHA23 & oline;3H+, which is not correct for all cases. By implementing genetic algorithms, the present study concluded that species like MCl2\ bx and MCl2+ (M = La, Ce, Pr, or Nd) have more distinct roles compared to M3+ in a concentrated chloride system using D2EHPA or PC88A, proving the involvement of speciation in solvent extraction reactions. The current study evaluated and offered a genetic algorithm method to model reactions governing LREEs solvent extraction considering either a single-reaction system or a multi-reaction system involving speciation, resulting in the reactions as shown in Eqs. 6, 10, 11, and 9.(6) {LaCl2++3HA2 & oline; LaClA2H2AH2 & oline;+2H+,HA=D2EHPALaCl2++2HA2 & oline; LaCl2A2H & oline;+H+,HA=PC88A(10) {CeCl2++3HA2 & oline; CeClA2H2AH2 & oline;+2H+,HA=D2EHPACeCl2++2HA2 & oline; CeCl2A2H & oline;+H+,HA=PC88A(11) {PrCl2++3HA2 & oline; PrClA2H2AH2 & oline;+2H+,HA=D2EHPAPrCl2++2.5HA2 & oline; PrClA2H2AH2 & oline;+2H+,HA=PC88A(9) NdCl2++2.5HA2 NdClA2H2AH2+2H+,HA=PC88A
