Separation Of Thorium Research Articles

Advancing towards technology readiness: Continuous-flow electrosorption for thorium separation from rare earth processing by-products

This study focuses on the development of a curated separation system aimed at separating thorium ions as part of a recovery plan for managing the thorium radionuclide in the rare earth element (REE) processing industry. As a step towards advancing technology readiness, the separation system employs the electrosorption technique, which involves the migration and storage of thorium ions in the electrical double layers on the porous surface of a carbon-based electrode. Using a prototype electrosorption cell operated at an applied voltage of 1.0 V, the system successfully achieved a thorium ion recovery rate of 84.5 ± 0.29 %, with an impressive electrosorption capacity of 105.26 mg-Th/1 g-carbon. Notably, despite the presence of higher concentrations of REE as competing ions, greater selectivity towards thorium was observed which likely attributable to its larger ionic radius, higher electron affinity, and greater distribution coefficient. These findings highlight the efficacy of the curated separation system and its potential to balance between REE economic significance as well as a protection to the environment.

Ultrahigh-Efficient N,O-Functionalized covalent organic framework towards thorium adsorption from uranium and rare earth elements

The development of novel porous materials as adsorbents for highly effective separation of thorium from ore or nuclear wastewater co-existing with uranium and rare earth elements is one of the most desirable methods but remains challenging. In this work, we prepare a N,O-functionalized two-dimensional covalent organic framework (2D COF), namely TAPT-DHTA, with a permanent porous structure and plenty of nitrogen and oxygen adsorption sites throughout the skeletons, which displays an ultrahigh Th(IV) saturated adsorption capacity of 1394 mg g−1 (at pH = 4.0), higher than all adsorbents reported so far. Moreover, the TAPT-DHTA COF has a large distribution coefficient (Kd) of up to 5.2 × 104 mL g−1, implying its extremely strong affinity for Th(IV) due to the collaborative coordination interactions between N/O atoms and Th(IV) as well as their specific binding mechanism. The distinguished adsorption behavior of the TAPT-DHTA COF affords an important platform for highly selective separation of Th(IV) from uranium and rare earth elements, thereby shedding some light on the design of novel adsorbents for thorium separation in the thorium fuel cycle.

Neutronic optimization of thorium-based fuel configurations for minimizing slightly used nuclear fuel and radiotoxicity in small modular reactors

Effective management of slightly used nuclear fuel (SUNF) is crucial for both technical and public acceptance reasons. SUNF management, radiotoxicity risk, and associated financial investment and technological capabilities are major concerns in nuclear power production. Reducing the volume of SUNF can simplify its management, and one possible solution is utilizing small modular reactors (SMR) and advanced fuel designs like those with thorium. This research focuses on studying the neutronic performance and radionuclide inventory of three different thorium fuel configurations. The mass of fissile material in thorium-based fuel significantly impacts Kinf, burn-up, and neutron energy spectrum. Compared to uranium, thorium as a fuel produces far fewer transuranic elements and less long-lived fission products (LLFPs) at the end of the core cycle (EOC). However, certain fission product elements produced from thorium-based fuel exhibit higher radioactivity at the beginning of the core cycle (BOC). Physical separation of thorium and uranium in the fuel block, like seed-and-blanket units (SBU) and duplex fuel designs, generate less radioactive waste with lower radioactivity and longer cycle lengths than homogeneous or mixed thorium-uranium fuel. Furthermore, the SBU and duplex feel designs exhibit comparable neutron spectra, leading to negligible differences in SUNF production between the two.

Highly efficient adsorption of thorium(iv) from aqueous solutions by functionalized UiO-66 with abundant phosphonic acid active sites

UiO-66-PO3, a novel functionalized metal–organic framework, exhibits high adsorption capacity and regeneration performance for efficient thorium separation and enrichment from wastewater.

Selective separation of thorium and uranyl in phases of different polarity using novel benzoxazole-based ligands: A DFT study

The separation of thorium and uranium is an important guarantee for the fuel cycle of thorium-based molten salt reactors. Benzoxazole-based ligands have a wide range of applications and are also potential ligands for actinide separation. In this work, density functional theory (DFT) calculations were used to study the intrinsic properties of two ligands, 2,6-bis(benzo[d]oxazole-2-yl)pyridine (ligand a) and 1-(6-(4-acetylbenzo[d]oxazol-2-yl)pyridin-2-yl)ethan-1-one (ligand b), revealing the structural characteristics and complexation behavior of their complexes with Th4+/UO22+. Quantum theory of atoms in molecules (QTAIM) and extended transition state - natural orbitals for chemical valence (ETS-NOCV) analyses show that the ligands form classical coordination bonds with Th4+/UO22+, with M−Noz bonds stronger than M−Npy bonds and partial electron acceptance by carbonyl O. The thermodynamic properties were used to evaluate the separation performance of these ligands for Th4+/UO22+ in four solvents (water, 1-hexanol, n-octanol and n-dodecane), with La more suitable for back extraction process and Lb having stronger binding with Th4+/UO22+. This work provides valuable theoretical insights into Th4+/UO22+ separation based on benzoxazole.

Ionic liquid - melamine foam composites for capture of thorium under high acidity conditions

Thorium has received much attention for potential application as nuclear fuel, but its capture at high acidity still requires more research. Ionic liquids (ILs) have been used to capture and separate various metal elements, but ionic liquid-containing composites have little been studied for thorium separation under high acidity conditions. A novel ionic liquid-foam composite (SIL-M) was prepared by loading stimuli-responsive ionic liquid (SIL) onto melamine foam (MF), and applied to separate thorium under high acid conditions. Under experimental conditions, SIL-M showed maximum adsorption capacity for thorium was 269 mg g−1 with an excellent selectivity for thorium over transition metals and lanthanide metals in 1 M HNO3 (S > 2 × 103). Studies revealed that PO was complexed with thorium, which also explained the high adsorption capacity and selectivity of SIL-M for thorium under high acidity within 4 cycles. Theoretical calculations were used to reveal that the reason why SIL can maintain high separation efficiency of thorium under high acidity conditions is due to the electrostatic potential of SIL is more positive. This study explored the possibility of using ionic liquid composite materials to capture thorium under strong HNO3 media, and provided ideas for designing thorium capture materials under high acidity conditions.

Efficient and selective capture of thorium ions by a covalent organic framework

The selective separation of thorium from rare earth elements and uranium is a critical part of the development and application of thorium nuclear energy in the future. To better understand the role of different N sites on the selective capture of Th(IV), we design an ionic COF named Py-TFImI-25 COF and its deionization analog named Py-TFIm-25 COF, both of which exhibit record-high separation factors ranging from 102 to 105. Py-TFIm-25 COF exhibits a significantly higher Th(IV) uptake capacity and adsorption rate than Py-TFImI-25 COF, which also outperforms the majority of previously reported adsorbents. The selective capture of Py-TFImI-25 COF and Py-TFIm-25 COF on thorium is via Th-N coordination interaction. The prioritization of Th(IV) binding at different N sites and the mechanism of selective coordination are then investigated. This work provides an in-depth insight into the relationship between structure and performance, which can provide positive feedback on the design of novel adsorbents for this field.

A sulfonated ligand-aqueous two-phase system for selective extraction of thorium from mining wastewater: Process optimization, structural characterization and mechanism exploration

As a potential nuclear fuel, the recovery of thorium with high efficiency, high selectivity and high extraction capacity from thorium-containing wastewater is considered to be one of the effective ways to reduce pollution and solve the shortage of thorium resources. However, the problem of efficient and selective separation of thorium from the complex environment has not been completely solved. Herein, a functional ligand called arsenazo (ASA), polyethylene glycol, and sodium sulphate were used to construct an aqueous two-phase system (ATPs) for the selectivity extraction and separation of thorium from mining wastewater. Furthermore, the complex agent, pH value, temperature, equilibrium time, coexisting substances, and other conditions for the extraction and separation of thorium were optimized, indicating that 98.7 % of thorium was efficiently and precisely separated from the acid-leaching solution to the pH of 2–3 or 5–6 with 0.08 g/L of ASA within 10 min, and the interference with multiple coexisting ions and organic substances was avoided. Importantly, the analysis of water quality parameters, thermogravimetry, infrared spectroscopy, and ultraviolet–visible spectroscopy revealed the coordination relationship between thorium ions and complex agents, indicating that the extraction of thorium in the aqueous two-phase system was a cation exchange mechanism. More importantly, SEM, TEM, EDX, and XRD verified that thorium was efficiently and selectively separated by a sulfone acid ligand-aqueous two-phase system, providing quantitative information on thorium-containing product distribution of relatively high accuracy and avoiding the interference with coexisting substance. Therefore, this work provided theoretical guidance on treating and reusing thorium in wastewater and enriched the content of functional ligand-aqueous two-phase extraction systems in green production technology.

Extraction and separation of thorium from cerium and lanthanum by Cyphos® IL 101 ionic liquid

Extraction and separation of thorium from cerium and lanthanum by Cyphos® IL 101 ionic liquid

Synergistic extraction and separation of thorium from rare earths in chloride media using mixture of Cextrant 230 and Cyanex 923

In order to lower the usage of expensive Cyanex 923 and increase the extraction capacity of the system of Cextrant 230, the synergistic extraction of thorium from chloride media by a mixture of Cextrant 230 and Cyanex 923 was investigated. The maximum synergistic enhancement coefficient (R) of 1.53 is obtained at 1:1 molar ratio of Cextrant 230/ Cyanex 923. The synergistic extracted species of Th4+ is determined as ThCl4·2Cextrant 230·Cyanex 923. The synergistic extraction of Th4+ is an entropy-driven exothermic process. The loading capacity of 0.60 mol/L mixed extractant for thorium is about 17.10 g/L (calculated as ThO2), and the loaded thorium in the organic phase can be effectively stripped by distilled water. For comparison, rare earth cations are barely extracted under the similar conditions, suggesting that the mixtures can be applied to separate thorium from rare earths. A cascade extraction process was developed based on the synergistic extraction system to separate thorium from the hydrochloric acid leaching of bastnaesite. The content of thorium in the leaching solution decreases obviously from 19.90 mg/L to 1.4 μg/L by 3 stages of extraction, which is superior to sole Cextrant 230 or Cyanex 923. The introduction of Cextrant 230 into the extraction system not only lowers the usage of Cyanex 923 but also enhances the selective extraction of thorium at low acidity, implying that the synergistic extraction system can selectively extract thorium more efficiently and economically than the sole systems.

Separation of thorium from radioactive rare-earth waste residue using aminophosphonate-functionalized polymer resin

Separation of thorium from radioactive rare-earth waste residue using aminophosphonate-functionalized polymer resin

Separation of thorium from uranium in support of particle reference material production

Separation of thorium from uranium in support of particle reference material production

Synthesis of a novel environmental-friendly biocarbon composite and its highly efficient removal of uranium(VI) and thorium(IV) from aqueous solution

The development and utilization of nuclear energy produced a large amount of uranium(VI)/thorium(IV)-containing wastewater, which would be harmful to the environment. The enrichment of the radioactive ions from wastewater using a green and environmentally friendly technology was great important to the protection of water environment and the resource utilization of energy materials. In this work, a novel cow manure-derived biocarbon-based composite was prepared by impregnation-carbonization technology for the separation of thorium(IV) and uranium(VI) from water. The composite could efficiently separate the target ions under acidic condition (pH = 4.5) with high saturated separation capacities (675.1 mg/g for uranium(VI) and 710.4 mg/g for thorium(IV)), high removal percentages (97.5% for uranium(VI) and 99.8% for thorium(IV)), fast separation rates in the initial stage of separation process (10.3 mg/(g·min) for thorium(IV) and 4.6 mg/(g·min) for uranium(VI) and good reusability after five cycles. Even in 1.0 g/L of NaCl solution, the removal efficiencies still exceeded 88.4% for uranium(VI) and 93.1% for thorium(IV). These results exposed the perfect performance of the cow manure-derived biochar-based composite in thorium(IV) and uranium(VI) separation. Moreover, various models were used to fit the experimental data, which revealed that the uranium(VI)/thorium(IV) separation on the biocarbon composite was monolayer chemical adsorption and the complexation was mainly the way for capturing uranium(VI) and thorium(IV). This work might offer a new perspective for the resource management of animal manure and a prospect for the practical application of biochar in thorium(IV) and uranium(VI) recovery.

Conceptual Process Development for the Separation of Thorium, Uranium, and Rare Earths from Coarse Coal Refuse

ABSTRACT Increasing disruption in the rare earth supply chain creates an urgency to develop alternative resources, in which utilization of coal-based materials presents great potential. Nevertheless, environmental control is a significant challenge in rare earth extraction processes. This study was conducted to contribute to the limited information on removing thorium and uranium from rare earths while coal-based products are used as feedstock. The laboratory studies suggested that the selective precipitation and solvent extraction approach yields the most favorable separation performance. Complete thorium precipitation was achieved around a pH value of 4.8. Due to the close precipitation pH ranges of uranium and rare earths, further separation by solvent extraction was applied to achieve an enhanced separation. Based on a Box-Behnken experimental design, the effect of extractant concentration, pH, strippant concentration, and O/A ratio was investigated. Best separation performance was achieved using 50 v% TBP at a pH of 3.5 with an O/A ratio of 3 and 1 mol/L H2SO4, which resulted in 1.8% uranium and 73.4% rare earth extraction. The extraction and precipitation behavior of the elements were further assessed with the distribution ratio, separation factor, thermodynamic parameters, and species distribution diagrams to provide a thorough understanding of the separation mechanisms. The results were statistically analyzed, and a model was developed to predict uranium recovery. The developed experimental protocol was validated using a rare earth oxalate sample produced at the pilot-scale processing facility. Finally, a conceptual process flowsheet was developed to effectively separate radionuclides while producing rare earth oxide products.

Separation of Thorium from Cerium and Lanthanum by Split Anion Solvent Extraction

Separation of Thorium from Cerium and Lanthanum by Split Anion Solvent Extraction

The application of food/agro-waste and spent household products for the environmentally benign separation of thorium

The cost-effective and environmentally benign separation of thorium from an aqueous acidic medium using spent food/agro-byproducts was studied. The processes followed the Langmuir isotherm model kinetics; were entropic and endothermic nature.

Design a full-scale batch adsorber for separation of thorium(IV) from liquid effluents by Haloxylon persicum leaves

Design a full-scale batch adsorber for separation of thorium(IV) from liquid effluents by Haloxylon persicum leaves

Utilization of ionic liquids for preferential separation of thorium during the determination of trace metallic constituents in thorium matrix using ICP-OES

To avoid spectral interference it is required to separate Th preferentially during the determination of trace metallic constituents from Th matrix using ICP-OES.

Synthesis of “(aminomethyl)phosphonic acid-functionalized graphene oxide”, and comparison of its adsorption properties for thorium(IV) ion, with plain graphene oxide

Abstract The current study presents a simple and scalable method for the synthesis of (aminomethyl)phosphonic acid-functionalized graphene oxide (AMPA-GO) adsorbent. The chemical structure of the new material was disclosed by different instrumental analyses (e.g. FTIR, Raman, XPS, AFM, TEM, XRD, CHN, and UV), and two pertinent mechanisms namely nucleophilic substitution and condensation were suggested for its formation. Adsorption experiments revealed that both AMPA-GO and plain GO have a high affinity toward Th(IV) ions, but the AMPA-GO is superior in terms of adsorption capacity, rate of adsorption, selectivity, pH effect, etc. Indeed, the AMPA-GO can uptake Th(IV) nearly instantaneously, and coexisting Na+ ions have no effect on its adsorption. Thanks to Langmuir isotherm, the maximum adsorption capacities of the GO and AMPA-GO were obtained 151.06 and 178.67 mg g−1, respectively. Interestingly, GO and AMPA-GO both showed a higher preference for thorium over uranium so that the average “K d (Th)/K d (U)” for them was 52 and 44, respectively. This data suggests that chromatographic separation of thorium and uranium is feasible by these adsorbents.

Separation of thorium(IV) from aquatic media using magnetic ferrite nanoparticles

Abstract The separation and recovery of thorium from monazite is critical to the sustainable development of the nuclear industry as well as to environmental safety. Also, the removal of radionuclides from polluted sources is a critical issue in environmental control. Magnetic ferrite nanoparticles (MCMF-NP, Co0.5Mn0.5Fe2O4) were synthesized (4–22 nm in size) and characterized. MCMF-NP was investigated for Th(IV) separation from their aqueous medium under various test conditions of acidity, time, and Th(IV) concentration, in line with the uptake capacity. The amount of thorium adsorbed is improved when pH, time, and initial concentration are increased. The maximum uptake of Th(IV) by MCMF-NP was observed at pH 3.5–4 and a contact time of 180 min. A favorable adsorption mechanism was shown in the pseudo-second-order rate. Isotherm analysis shows an adequate process described by the Langmuir isotherm. MCMF-NP is an adsorbent capable of successful disposal of Th(IV) from waste solutions with a high uptake of 81.3 mg of Th(IV)/g of MCMF-NP. The possibility of re-using the MCMF-NP, adding value to this content as a way of compensating for the disposal costs, was studied and disused. MCMF-NP shows a good separation of thorium(IV) from monazite leach liquor as well as from wastewater samples.