Separation Of Th Research Articles

A novel strategy for sequential separation of Th(IV) from highly acidic wastewater based on solid phase extraction

The potential applications and advantages of thorium(Th) in the development of the nuclear industry make the effective separation of Th(IV) crucial for depleted fuel management and environmental safety. However, selectively capturing of Th(IV) from high-concentration nitric acid remains a challenging task. In this work, a novel solid-phase extraction resin (TOPO/XAD-7) was successfully synthesized by vacuum impregnation of trioctylphosphine oxide (TOPO) into an acrylic-based polymer (XAD-7 resin). It exhibited excellent adsorption abilities for Th(IV), including wide highly concentration acid tolerance (0.01–6 mol L−1 HNO3), high adsorption capacity of 59.79 mg g−1, fast adsorption kinetic (< 60 min) and super elevated selectivity. The adsorption mechanism of the resin involves neutral chelation extraction, with the PO group being the main adsorption binding site. Additionally, the resin was demonstrated good reusability and stability under extreme conditions (high acidity, high temperature and high radiation). Furthermore, dynamic column experiments conducted using an automated separation system validated the practical application of TOPO/XAD-7 resin for the separation of Th(IV) and U(VI)/Th(IV) in wastewater, achieving high element recovery (> 99.5%) and a high U(VI) decontamination factor (3.5 × 105). This work confirms the excellent potential of TOPO/XAD-7 resin for the separation and enrichment of Th(IV) in nuclear wastewater.

Study of the Chemical Recovery and Selectivity against U in the Radiochemical Separation of Th with Tri-n-butyl Phosphate by Varying the Proportion of Xylene and HCl Concentration.

Thorium is a radionuclide used in various environmental studies such as dating, sediment movement, soil-plant transfer studies, and contamination of waste from the natural fuel cycle. The liquid-liquid extraction method using tri-n-butyl phosphate (TBP) allows for the separation of Th from the accompanying actinides. However, the separation of Th and U present in the same sample is not trivial. This separation is influenced by the starting acid (HCl or HNO3), the concentration of TBP in an organic solvent, and the concentration of the acid used for re-extracting Th, which is typically HCl. Therefore, it is necessary to study these factors to ensure that the method has sufficient chemical yield and selectivity in complex matrices. This study presents a systematic investigation of the aforementioned parameters, making the necessary variations to select an optimal method for the radiochemical separation of Th. The ideal conditions were obtained using 4 M HCl as the acid prior to extraction, a 1:4 solution of TBP in xylene, and 4 M HCl as the re-extracting agent. The accuracy and precision were studied in four intercomparison exercises conducted in quadruplicate, using the parameters Enumbers, RB(%), and RSD(%) for 232Th and 230Th. The sensitivity of the method was experimentally studied and the limit of detection (LoD) was determined according to ISO 11929:2005. Additionally, the linearity of the method showed that the experimental and theoretical activity concentrations of 232Th and 230Th had slopes of 1 with an intercept close to 0.

Selective adsorption of actinides and rare earth elements from leach liquor using metal oxide-polymer nanocomposites

Utilization of actinides and rare earth elements is only possible by separating these metals with high purity. The materials used in separation must have thermal, chemical, mechanical, and radiation resistance. In the present study, separation experiments of actinides and rare earth elements (REEs) were carried out using purified H2SO4 leach liquor. Polyacrylonitrile (PAN)-supported Ti, Zr, and Si oxide nanocomposites were tested for the selective separation of Th, U, Gd, Eu, Sm, Pr, Nd, La, Ce, and Y. The effects of pH, contact time, adsorbent/solution ratio, and temperature on distribution coefficient (KD) and adsorption capacity (Q) were investigated. The synthesized nanocomposites tend to separate the elements into two main groups: Th, U, Gd, Eu and Sm, Pr, Nd, La, Ce. Notably, it was observed that the separation of Th and U from the remaining elements is promising at 15 °C. Additionally, the separation can be further improved depending on the differences in desorption efficiency.

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.

Functionalization of Zr@FMA with phosphonic acid groups for efficient separation of Th(iv) from aqueous solutions

A phosphonate-functionalized Zr@FMA material was prepared as an adsorbent for efficient Th(iv) recovery from aqueous solutions. The adsorbent demonstrates a large surface area, enhanced adsorption capacity, and excellent selectivity for Th(iv).

Selective recovery of Th(IV) from radioactive rare earth waste residue by utilizing MoS2-modified ion-absorbed type rare earth tailings

In the process of extracting ion-absorbed rare earth ore (IREO), the production of radioactive waste is a major environmental concern. To address this issue, MoS2 was used to modify ion-absorbed rare earth tailings (RET) to synthesize a novel MoS2@RET composite material for the effective handling of radioactive waste generated in IREO separation industry. The composite material was thoroughly characterized using various analytical techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and energy dispersive spectroscopy (EDS). By optimizing the operating parameters, the optimal experimental conditions were determined to be pH = 3, contact time = 60 min, liquid-solid ratio = 6 g/L, and initial concentration = 150 mg/L. The adsorption data fitted well with the pseudo second-order rate model. The thermodynamic parameters concerning the adsorption of Th(IV) were analyzed and computed. Langmuir isotherm model is a more fitting choice for the adsorption process compared to the Freundlich isotherm model. MoS2@RET was used in the acid leachate of IREO waste residue, achieving the separation of Th and rare earth successfully. The mechanism of Th(IV) adsorption by MoS2@RET was investigated, revealing that the adsorption process involves electrostatic interactions, chemical bonding, and redox reactions. The above research results indicate that MoS2@RET composite materials have application potential in the sustainable treatment of IREO radioactive waste.

Effective adsorption of thorium ion by novel self-crosslinking polyamide acid-grafted magnetic nanocomposites

A novel self-crosslinking polymer-coated magnetic nanosorbent (Fe3O4@PAA) was prepared to remove thorium ions from aqueous solutions. The grafting-polymerization method was employed to graft polyamide acid (PAA) onto amino-activated magnetic nanoparticles (Fe3O4@SiO2-NH2) via an amidation reaction using pyromellitic dianhydride (PMDA) and tris(2-aminoethyl)amine (TA) as monomers. The adsorption results show that the adsorption process of Th(IV) by Fe3O4@PAA is significantly pH-sensitive, and the theoretical maximum adsorption capacity can reach 122.5 mg/g at pH 3.0. Furthermore, Fe3O4@PAA exhibits a high adsorption rate and the adsorption equilibrium could be reached within 60 min. After 5 cycles of reuse, the adsorption capacity was still retained at more than 80 % of the initial value. In addition, the extraction mechanism of Fe3O4@PAA for Th (IV) ions was analyzed in detail by FT-IR and XPS. This work provides valuable insights into the design and preparation of novel, acid-resistant, easily separable and fast magnetic separation adsorbents for the highly effective separation of Th () from aqueous solutions.

Separation of Thorium from Light Rare Earth Elements from Monazite Chloride Leach Liquor

Monazite is one of the main light rare earth element (REE) minerals and is associated with the presence of Th. This poses challenges in processing due to the strong radiation present in this mineral. However, the use of Th as a nuclear fuel, after the transformation of 232Th into 233U, has been considered a better option than the currently more widespread use of 235U. Therefore, the separation of Th from the REE after leaching is an essential step that requires optimization. In this study, the treatment of a leach solution in a hydrochloric medium from dephosphorized monazite is addressed. The separation of Th from light REEs was performed by solvent extraction with Cyanex 572 or 272. The tests considered included (1) the ratio of the monazite leaching liquor and organic solution, (2) the initial pH values, and (3) the concentration of the extractants. The aqueous-phase samples were analyzed by Inductively Coupled Plasma Optical Emission spectroscopy (ICP-OES). It was observed that at low pH, 60% of the Th was extracted by Cyanex 272 and 90% by Cyanex 572 in one single step. Acidity had little effect on Th extraction. The extractions of light REEs by Cyanex 272 and 572 were negligible in most cases, but for pH values greater than 2, Cyanex 272 extracted a considerable fraction of these elements, which did not occur with Cyanex 572. The results show that Th can be easily separated from light REEs in an acidic and hydrochloric medium by both Cyanex 272 and Cyanex 572.

Synthesis of new extractant P113 for cerium(IV) extraction and higher separation over thorium from bastnaesite

Cyanex923 (a mixture of four trialkyl (hexyl and octyl) phosphine oxides) has been extensively employed in the recovery of cerium (Ce(IV)) and fluorine (F), as well as the separation over thorium (Th(IV)) from bastnaesite. However, rigorous production conditions and involvement of highly toxic raw materials (PH3) have been critical problems to be solved during the synthesis of Cyanex923. Meanwhile, its extraction performance remains to be improved. Therefore, we attempted to adjust the feed ratio to increase the proportion of short carbon chain components, successfully synthesized a novel extractant (P113, a mixture of four trialkyl (hexyl and octyl) phosphine oxides) with contents of each component different from Cyanex923 using an environmentally benign method. The comparison with Cyanex923 revealed obvious improvement of P113 in terms of extraction efficiency, selectivity and saturation capacity. The extraction efficiency and saturation capacity of Ce(IV) were increased by 10% and 10 g L-1, respectively. Separation factor of Ce(IV)/Th(IV) was increased from 16 to 27 at 2 mol L-1 H2SO4. Furthermore, P113 presented excellent regenerability. The superiority of P113 was theoretically explored using the density functional theory (DFT) and polarizable continuum model (PCM), and the results indicated that THPO (trihexyl phosphine oxide) had lower extraction phase transfer energy than TOPO (trioctyl phosphine oxide) from aqueous phase to organic phase. The comprehensive evaluation of P113 demonstrated the feasibility employed in the recovery of Ce(IV)-F and the separation of Th(IV) from bastnaesite, which advanced industrial application of the novel extractant, and held significant value for the utilization of resources and environmental protection.

Superefficient separation of Th(IV) and U(VI) by lignin-derived magnetic biochar via competitive adsorption mechanism

Thorium (Th) and uranium (U) separation remains a huge challenge due to their high similarity in chemical behavior. In this study, lignin-derived magnetic biochar (AL-Fe/BC), which can provide functional sites for adsorbing Th(IV) and U(VI), was synthesized for the selective extraction of Th(IV) from the binary U(VI)-Th(IV) matrix. Characterizations results confirm the successful zero-valent iron loading, and the AL-Fe/BC exhibited a developed polyporous structure, high surface area, stable crystallinity, high defects degree, and advantageous magnetic feature of expedient recovery from water without energy consumption. The optimist AL-Fe/BC-800 showed an outstanding adsorption capacity with a maximal Th(IV) uptake of 2000 mg/g, and a small absorption of 3 mg/g of U(VI) (Th(IV) = 180 mg/L, U(VI) = 20 mg/L, AL-Fe/BC-800 = 0.05 g/L). Moreover, the separation factor of Th(IV) from the Th(IV)-U(VI) matrix reached 90,000 even concomitant with high a concentration of co-existing ions. The active adsorption sites on AL-Fe/BC-800, such as COOH, C-OH, C=O, pyridinic N, graphitic N, and pyrrolic N, exhibited a stronger binding affinity with Th(IV) than U(VI), achieving selective Th(IV) adsorption via a chemisorption process on the basis of competitive adsorption. In summary, AL-Fe/BC-800 is a potential adsorbent in industrial application for the superefficient separation of Th(IV) and U(VI) with high-performance magnetic recovery, promoting the sustainable development of nuclear industry, especially considering the necessary development of Th(IV) fuel.

Two-step separation of Th, La and Ba using combined chromatographic columns

Two-step separation of Th, La and Ba using combined chromatographic columns

Synthesis of Zn-Al layered double oxides using eucalyptus leaf extract as template for efficient and ultrafast thorium(IV) removal

Efficient capture of Th(IV) from aqueous solution is of importance to both solve the radioactive pollution for environmental safety and provide clean energy for sustainable development. However, it still faces huge challenge. In this study, eucalyptus leaf extract was applied as template agent to fabricate Zn/Al-bimetallic layered double oxides (ZnAlLDO), providing more active sites for Th(IV) removal. The removal process of Th(IV) onto ZnAlLDO could reach equilibrium within 5 min and the maximum removal capacity calculated from the Langmuir model was 1153.71 mg g−1 at pH = 4.0 and 298 K. Over 97 % Th(IV) could be removed by ZnAlLDO during the dynamic adsorption process and the removal efficiency still remained at a high level (85 %) after 5 cycles. The Th(IV) removal process on ZnAlLDO was ascribed to electrostatic attraction, complexation and ion exchange. It could be believed that the ZnAlLDO with large removal capacity (1155.5 mg g−1), fast equilibrium time (5 min) and easy desorption (91.76 %) with high recovery (85 %) might be a promising adsorbent for the separation of Th(IV).

Advanced solid-phase extraction of tetravalent actinides using a novel hierarchically porous functionalized silica monolith

Separation of actinides is of great concern from the perspective of nuclear energy development and environmental issues, and the development of a highly efficient solid-phase extraction (SPE) process holds significant promise for actinide separation. However, the slow mass transfer kinetics in the currently available SPE separation media limited the throughput and efficiency, rendering the separation process more challenging. Hierarchically porous structures with well-organized and highly interconnected pore systems have been shown to provide efficient mass transfer and enhanced performance in nature. Herein, this paper reports the synthesis of a crack-free diglycolamic acid-functionalized silica monolith with hierarchical macro and meso porous structure for SPE. The hierarchically porous structures were retained upon mild modifications, which favored the convective mass transport and provided more binding sites, resulting in fast kinetics and high throughput. The separation ability was evaluated based on the separation and recovery of Th(IV) from a complex matrix. A superior Th(IV) separation performance (Kd > 2.6 × 104 mL/g) was achieved in the presence of alkaline earth metals, rare earth elements, and uranium within 1 min by batch sorption, and the maximum separation coefficients of Th(IV)/Ln(III) and Th(IV)/U(VI) exceed 1000 and 140, respectively. Particularly, the synthesized material allowed the separation of Th from monazite leachates with highly efficient recovery (> 96%) at a high flow rate (5 mL/min) by column study. Investigation of the binding mechanism revealed the formation of a stable coordination complex (Th(NO3)L3) via Th−O bonds. The material was also employed for the extraction of Pu(IV), and satisfactory sorption was achieved. Thus, this new functionalized material has potential application prospects for an improved actinide separation process.

Stability Indicating HPLC Method for Estimation of Thymoquinone in Nasal Simulated Fluid: Method Development and Validation

Introduction: A simple rapid and precise HPLC method was developed for estimation of TH in nasal simulated fluid and stability was assessed in various stressed conditions.&#x0D; Methods: Chromatographic separation of TH in nasal simulated fluid was done using HPLC AS-4050 coupled with Jasco UV 2075 Plus detector, Jasco LC-Net 11/ADC valve, Jasco PU-2080 pump and hypersil gold C18 (250x6x5 µm) column, ChromNAV 2.0 Chromatography Data System software with mobile phase as acetonitrile: water (65:35) and acetonitrile: NSF (60:40) at a flow rate of 1ml/min and having run time of 10 min with loop volume of 20 µl and detection wavelength of 252 nm. The method was validated for accuracy, precision, linearity, specificity, and sensitivity in accordance with ICH (Q2B) guidelines.&#x0D; Results: The results of all the validation parameters were found to be within the acceptable limits. The calibration plots were linear over the concentration ranges from 2 to 14µg/ml. The accuracy and precision were found to be between 97.04±0.112 to101.081±0.0191and ≤2% for three drugs. Developed method was successfully applied for the determination TH in nasal simulated fluid and recovery was found to be &gt;98% for three drugs. The degradation products produced as a result of stress studies did not interfere with drug peak.&#x0D; Conclusion: The developed method was found to be simple, specific, economic, reliable, accurate, precise, and reproducible used as a quality control tool for analysis of pure thymoquinone in nasal simulated fluid.

Non-conventional recovery of uranium and associated valuable metals from Rosetta monazite mineral concentrate

ABSTRACT Citric acid has a very important role in the extraction process of uranium from the matrix such as hydrous oxide cake formed after alkali breakdown of Egyptian Rosetta monazite mineral concentrate. This manner involved leaching of uranium selectively (94%) using 150 g L−1 citric acid concentration at solid liquid (S/L) ratio of 1:5 at room temperature for 120 min. The kinetics of the concerning leaching process and the reaction mechanism between citric acid and uranium have been discussed in detail. From the latter, it was found that the reaction was diffusion controlled and the calculated apparent activation energy value was 12.724 KJ mole−1. The work then explained the separation of Th and REEs from hydrous oxide as conventional techniques in published data.

Separation of thorium and uranium from xenotime leach solutions by solvent extraction using primary and tertiary amines

This study addressed the development of a continuous countercurrent extraction-scrubbing-stripping technique using a mixture of primary and tertiary amines as an effective extractant for both thorium (Th) and uranium (U) to simultaneously separate them from the leach solutions of xenotime concentrate from the Yen Phu mine (Vietnam). Systematic studies determined the optimum parameters of the separation, including the optimum concentrations of the mixture of the primary amine (N1923) and tertiary amine (tri-n-octyl amine), the optimum acidity (pH) of the feed liquor (Yen Phu xenotime leachate), the optimum contact time between phases for extraction, scrubbing and stripping processes, and the most suitable stripping reagent mixture. Using the optimum parameters, the optimum stage number and phase volumetric ratio for extraction, scrubbing, and stripping processes were calculated using the calculus method based on the law of matter conservation. The flow rates of both phases for extraction, scrubbing, and stripping were determined from the results of these studies and calculations. To optimize the separation of uranium and thorium from the Yen Phu xenotime leachate, counter-current simulations of extraction, scrubbing and stripping were done in a series of mixer-settler units. The results indicated that the selective separation of Th and U with almost no loss of rare earths (REs) and a minimal contamination of iron were obtained. The continuous countercurrent extraction-scrubbing-stripping technique shows potential applications in the commercial separation of Th and U from RE leachate after tests using a sequence of mixer-settler units on a pilot scale.

Selectivity of Th(IV) adsorption as compared to U(VI), La(III), Ce(III), Sm(III) and Gd(III) using mesoporous Al2O3

ABSTRACT Herein, we have used mesoporous Al2O3 as adsorbent and compared its efficacy with chromatographic neutral alumina for the selective adsorption and separation of Th(IV). The metal ions form complex with thorin and the Th-thorin complex gets selectively adsorbed on the mesoporous alumina at pH 1 unlike other metal ions. The R2 value of Langmuir isotherm model was found to be the highest and closer to 1. The adsorption capacities at 283, 303 and 328 K were found to be 50, 51.02 and 51.81 µmolg−1 respectively. The adsorbed thorium was desorbed from the adsorber upon treatment with trisodium citrate.

Facile separation of Th(IV) from aqueous solution by graphene hydrogel

In this work, the graphene hydrogel (GH) was fabricated, and its adsorption behavior toward Th(IV) was studied. The GH displayed a porous network structure, with a controllable size and structure. The adsorption experimental results demonstrated that the adsorption of Th(IV) on GH fitted well with pseudo-second-order kinetic model and Freundlich isotherm model, with a maximum adsorption capacity of 190.28 mg/g at pH 3.0. The adsorption of Th(IV) on GH in inner-sphere surface complexation. Solution pH has an important influence on Th(IV) adsorption of GH. In addition, the GH exhibits an excellent reusability in Th(IV) adsorption.

Determination of uranium and thorium isotopes in kaolinitic samples by ICP-MS/MS

The use of natural uranium and thorium long-lived isotopes was applied to study the evolution of kaolinitic materials. To do that, a radiochemical method for separation of Th and U in phyllosilicate samples was developed with the main aim of their analysis by ICP-MS/MS. Given the lack of certified phyllosilicate reference materials with certified isotope abundances, the method was tested using a stepwise approach. First, a preliminary setup was done using a sediment reference sample. Then, the extrapolation of this method to the samples of interest has been tested using a phyllosilicate sample certified for U and Th concentrations. The results showed that an extension of the plateau time of digestion in the used microwave system was peremptory as to get full digestion of the sample. The use of the isotope dilution technique allowed both the quantification of major isotopes (238U and 232Th) simultaneous to the determination of isotope ratios (234U/238U, 235U/238U for quality control and 230Th/232Th). The established method was applied to six kaolinitic samples from the Iberian Range (NE Spain), showing the potential of this isotope approach for the characterization of their time evolution.

A cost-effective process for recovering thorium and rare earths from radioactive residues

Ion-adsorbed rare earth ores radioactive residues (IREORR) are low-level radioactive wastes generated by the production processes of ion-adsorbed rare earth ores (IREO). IREORR were difficult to be managed due to their radioactivity and larger volume. The wastes have caused environmental concerns. In addition, IREORR were rich in rare earth elements (REEs). The contents of REEs in IREORR were much higher than those in IREO. In this study, a separation process based on 2-(4-(2,4,4-trimethylpentan-2-yl) phenoxy) acetic acid (POAA) for the recoveries of REEs and radioactive element Th from IREORR leachate have been developed. The extraction mechanism of POAA for Th was indicated to be cation exchange mechanism. Unsaponified POAA revealed a better selectivity for the separation of Th from mixed REEs. The separation of Th and enrichment of REEs from IREORR leachate were achieved by liquid-liquid extraction and extraction-precipitation, showing that this process may be cost-effective used to deal with IREORR leachate for environmental concerns and resource utilizations.