Uranium Extraction Efficiency Research Articles

Kevlar Aerogel‐Confined Functional Liquid‐Based Composite Membrane Enables Dynamic Uranium Capture

AbstractSolid–liquid composite materials that confine a functional liquid within a porous solid have appeared in a wealth of emerging applications. However, creating dynamic liquid interfaces for efficient ion capture while stably retaining functional liquid in porous confinements is challenging. Here, an aerogel‐confined liquid‐based composite membrane (ALCM) for dynamic and highly efficient uranium capture is reported. As a proof of concept, Kevlar aerogel membrane is selected as the nanoporous solid, and calix[6]arene/tributyl phosphate (C6/TBP) is used as the guest liquid. The obtained ALCMs possess high stability, optimum adhesion between solid‐liquid interface, and high selectivity for uranyl ions (250–6510 times over other competing ions). Different dynamic interface regulating approaches are explored for ALCMs, and uranium extraction efficiency under alternating pressures can be up to 258.48 mg g−1 h−1, outperforming many reported uranium capture materials. This strategy can be applicable to develop a rich family of solid‐liquid composite materials and may spearhead a new paradigm for uranium capture from sustainable seawater resources.

Development of Technology for the Bioleaching of Uranium in a Solution of Bacterial Immobilization

This study presents findings regarding the kinetics of ferrous iron oxidation in solution mediated by Acidithiobacillus ferrooxidans bacteria within a continuous-flow bioreactor employing diverse types of immobilizers. The objective is to augment the rate of ferrous iron oxidation in solutions utilizing an immobilizer for Acidithiobacillus ferrooxidans strains. Immobilization represents a promising avenue for enhancing the efficiency of Fe2⁺ oxidation via acidophilic ferrooxidizing bacteria, leading to a several-fold increase in oxidation rate. A comparative analysis was conducted to evaluate the efficacy of different types of immobilizer in facilitating iron oxidation within a continuous-flow bioreactor, including the application of wood chips coated with Fe(OH)3. The results indicate that wood chips coated with iron hydroxide serve as effective type of immobilizer, facilitating the robust attachment of Acidithiobacillus ferrooxidans via electrostatic interactions between negatively charged bacteria and positively charged surfaces. Experimental investigations were conducted using novel immobilization matrices in pilot-scale tests simulating the underground borehole leaching (UBL) of uranium. The bioactivation of leaching solutions enhances the efficiency and environmental compatibility of UBL compared to conventional chemical oxidation methods. The relationships between redox potential and ferric iron content in bioactivated solutions during the UBL of uranium were delineated. The significance of this study lies in its elucidating the pivotal role of Fe2⁺ oxidation in uranium extraction processes, particularly in the context of UBL. By employing bioactivation mediated by Acidithiobacillus ferrooxidans, the study demonstrates not only enhanced uranium extraction efficiency, but also markedly improved environmental sustainability compared to traditional chemical oxidation methods. The findings reveal crucial correlations between redox potential and ferric iron concentration in bioactivated solutions.

Co-precipitation synthesis of carbonic anhydrase-embedded magnetic zeolitic imidazolate framework-8 nanocomposite enzyme for enzymatic CO2 conversion and utilization in facilitating uranium extraction

Carbonic anhydrase (CA)-mediated carbon conversion and utilization (CCU) technology is recognized as an eco-friendly and cost-effective strategy for carbon reduction. However, the broader application of this technology is significantly constrained by the operational instability and challenging recyclability of free CA. Fortunately, nano-integrated biocatalysis has emerged as an effective solution to these challenges. In this study, we immobilized CA for the first time as a CA-embedded ferriferous oxide-zeolite imidazolium framework-8 (Fe3O4@ZIF-8@CA) nanocomposite enzyme through a one-pot co-precipitation strategy, integrating both the in-situ growth of ZIF-8 around the Fe3O4 core and the immobilization of CA within a single step. Subsequently, this nanocomposite was employed as a nano-integrated biocatalyst to facilitate an innovative CCU pathway. This pathway leverages bicarbonate, produced from the enzymatic hydration of carbon dioxide (CO2), as a substantive uranyl complexing agent to facilitate the neutral leaching of sandstone uranium ore. Systematic characterization techniques, including SEM, TEM, XRD, FTIR, TGA, CLSM, and MPMS, confirmed that Fe3O4@ZIF-8@CA, which possesses a core–shell structure and excellent magnetic responsiveness, has been successfully synthesized. Enzymatic assays revealed that Fe3O4@ZIF-8@CA retains approximately 79% of the activity compared to its free counterparts while demonstrating significantly enhanced thermal and storage stability. The outcome of CO2 hydration conversion for facilitating uranium extraction indicated that, compared with the non-enzymatic reaction group, the bicarbonate yield increased up to 1.5 times, and the uranium extraction efficiency was nearly 10% higher in the Fe3O4@ZIF-8@CA-mediated reaction group. These findings suggest that Fe3O4@ZIF-8@CA possesses excellent catalytic properties for CO2 hydration and can achieve multiplied decarbonization by mediating this innovative CCU pathway. Furthermore, Fe3O4@ZIF-8@CA demonstrated superb reusability and durability, experiencing no significant degradation in its catalytic performance after eight consecutive hydration regeneration cycles. Our research is anticipated to be a viable option for advancing the goals of carbon neutrality and sustainable development.

Interface coupling induced built-in electric fields accelerate electro-assisted uranium extraction over Co3O4@FeOx nanosheet arrays

Revealing the nature of enhanced electro-assisted uranium extraction activity by hetero-interface and M-O-H coordination bonds is an important and challenging task. Hence, Co3O4@FeOx nanosheet arrays with abundant M-O-H coordination bonds is fabricated as a binder-free and self-supporting electrocatalyst for electro-assisted uranium extraction from fluorine-containing uranium wastewater. As revealed by self-consistent energy band calculations and in-situ Kelvin Probe Force Microscopy (KPFM) analysis, the p-n heterojunction formed by Co3O4@FeOx provides a well-designed built-in electric field (BIEF), triggering the interfacial accumulation of uranium and accelerating the electro reduction kinetics of uranium. Consequently, Co3O4@FeOx shows remarkable U(VI) extraction ability (>95 %) in fluorine-containing uranium wastewater. By virtue of the XAFS spectra, free uranyl ions are captured by M-O-H on Co3O4@FeOx to form a sturdy 2 Oax-1 U-3 Oeq configuration, confirming the electrically driven separation of uranium and fluorine. Furthermore, DFT calculation indicates that the existent of M-O-H enhances the adsorption energy of uranium species, thus promoting uranium extraction efficiency.

An imidazole-based covalent-organic framework enabling a super-efficiency in sunlight-driven uranium extraction from seawater.

Uranium extraction from seawater represents an effective way to solve the difficulty of the insufficient uranium supply chain. However, this route is still restricted by the low extraction efficiency of reported adsorbents. Here, we find that reversing the donor-acceptor in imidazole-based COFs (covalent-organic frameworks) would be effective for enhancing the extraction efficiency of uranium. As a result, the TI-COF is found to enable a uranium extraction efficiency up to 8.8 mg g-1 day-1 from seawater under visible light irradiation, exceeding all established adsorbents for such use, and an unprecedented uranium extraction efficiency up to 6.9 mg g-1 day-1 from seawater under natural sunlight.

Achieving ultrahigh uranium/vanadium selectivity of poly(amidoxime) via coupling MXene-enabled strong intermolecular interaction and separated photothermal interface.

Poly(amidoxime) (PAO) has been recognized as the most potential candidate for extracting uranium from seawater, owing to its merits of outstanding uranium affinity, low cost, and large-scale production. Despite remarkable achievements, existing PAO sorbents suffer from unsatisfactory uranium extraction efficiency and selectivity, as imposed by the inherently sluggish uranium adsorption kinetics and inevitable spatial configuration transition of amidoxime, which diminishes uranium affinity. Herein, we discover a facile and integrated design to elaborate a PAO/MXene nanocomposite that delivers ultrahigh and durable uranium/vanadium (U/V) selectivity. The key to our design lies in harnessing MXene-enabled strong intermolecular interactions to PAO to minimize the spatial configuration transition of amidoxime and stabilizing its superior uranium affinity, as well as creating a separated photothermal interface to maximize temperature-strengthened affinity for uranium over vanadium. Such a synergetic effect allows the nanocomposite to acquire over a 4-fold improvement in U/V selectivity compared to that of pure PAO as well as an unprecedented distribution coefficient of uranium compared to most state-of-the-art sorbents. We further demonstrate that our nanocomposite exhibits durable U/V selectivity with negligible attenuation and good antibacterial ability even in long-term operation. The design concept and extraordinary performance in this study bring PAO-based sorbents a step closer to practical uranium extraction from seawater.

Enhancing Uranium Extraction Efficiency Using Protonated Amines and Quaternary Ammoniums-Based Ionic Liquids: Mechanistic Insights and Nonlinearities Analysis

This study investigates uranium solvent extraction under AMEX process conditions. The use of pure extractants without diluents or phase modifiers allows us not only to reduce the use of volatile organic compounds but also to provide higher extraction yields without third-phase formation. Pure extractants are protonated amines or quaternary ammoniums with suitable counter ions, which act at the interface between ion pairs and protic ionic liquids. The mixture of sulphates anion (SO42−) and bis(trifluoromethanesulfonyl)imide anion (NTf2−) revealed unexpected nonlinear extraction behaviors, which appear highly important to rationalize for optimized application. A spectroscopic analysis (NMR, UV-vis, FT-IR, and EXAFS) showed that uranium extraction occurs via a protonated amine and three sulphates. A nonlinear extraction could further be interpreted by considering a water and acid transfer between the two phases: at lower sulphate ratios, the release of acid from the organic phase into the aqueous phase was shown to influence the number of protonated amines in the organic phase, affecting uranium extraction before its enhancement. Furthermore, the extraction loss at higher sulphate ratios was assigned to the destabilization of bidentate uranium–sulphate complexes due to a competition between water and sulphates.

Polydopamine/β-cyclodextrin/coal fly ash composite for the highly efficient extraction of uranium from water environment

To obtain a green, low-cost and efficient adsorbent, polydopamine (PDA) and β-cyclodextrin (β-CD) were adopted to modify coal fly ash (CFA) to prepare polydopamine/β-cyclodextrin/coal fly ash composite (PDA/β-CD/CFA). The successful introduction of PDA and β-CD was proved by FT-IR, XRD and XPS. The uranium extraction efficiency on PDA/β-CD/CFA reached 95.6% (pH = 5.0, T = 298 K, C0 = 10 mg/L and m/V = 0.2 g/L) and the whole adsorption process was perfectly fitted by the Pseudo-second-order model (R2 = 0.999), illustrating that uranium was extracted via chemisorption. The correlation coefficient R2 of Langmuir model was 0.999, which was higher than other models, meaning that uranium extraction behavior on PDA/β-CD/CFA was uniform monolayer adsorption. The maximum extraction capacity of uranium on PDA/β-CD/CFA calculated by Langmuir model was 537.6 mg/g, which was larger than most of reported adsorbents, indicating that PDA/β-CD/CFA was a potential candidate for uranium extraction from water environment. Moreover, PDA/β-CD/CFA performed excellent uranium extraction properties with the existence of coexisting ions and the desorption efficiency of uranium by PDA/β-CD/CFA was higher to 95.8% at the fifth cycles, fully suggesting that PDA/β-CD/CFA possessed good selectivity and cycle stability. Characterization results demonstrated that uranium was immobilized on PDA/β-CD/CFA through chelation, complexing action, electrostatic interaction and hydrogen bonding.

Tuning Local Charge Distribution in Multicomponent Covalent Organic Frameworks for Dramatically Enhanced Photocatalytic Uranium Extraction

AbstractOptimizing the electronic structure of covalent organic framework (COF) photocatalysts is essential for maximizing photocatalytic activity. Herein, we report an isoreticular family of multivariate COFs containing chromenoquinoline rings in the COF structure and electron‐donating or withdrawing groups in the pores. Intramolecular donor‐acceptor (D‐A) interactions in the COFs allowed tuning of local charge distributions and charge carrier separation under visible light irradiation, resulting in enhanced photocatalytic performance. By optimizing the optoelectronic properties of the COFs, a photocatalytic uranium extraction efficiency of 8.02 mg/g/day was achieved using a nitro‐functionalized multicomponent COF in natural seawater, exceeding the performance of all COFs reported to date. Results demonstrate an effective design strategy towards high‐activity COF photocatalysts with intramolecular D‐A structures not easily accessible using traditional synthetic approaches.

Tuning Local Charge Distribution in Multicomponent Covalent Organic Frameworks for Dramatically Enhanced Photocatalytic Uranium Extraction.

Optimizing the electronic structure of covalent organic framework (COF) photocatalysts is essential for maximizing photocatalytic activity. Herein, we report an isoreticular family of multivariate COFs containing chromenoquinoline rings in the COF structure and electron-donating or withdrawing groups in the pores. Intramolecular donor-acceptor (D-A) interactions in the COFs allowed tuning of local charge distributions and charge carrier separation under visible light irradiation, resulting in enhanced photocatalytic performance. By optimizing the optoelectronic properties of the COFs, a photocatalytic uranium extraction efficiency of 8.02 mg/g/day was achieved using a nitro-functionalized multicomponent COF in natural seawater, exceeding the performance of all COFs reported to date. Results demonstrate an effective design strategy towards high-activity COF photocatalysts with intramolecular D-A structures not easily accessible using traditional synthetic approaches.

Intrinsically morphological effect of perovskite BaTiO3 boosting piezocatalytic uranium extraction efficiency and mechanism investigation

Developing a convenient, efficient and eco-friendly approach for the recovery of U(VI) ion is a key measure to solve the environmental problems arising from the utilization of nuclear energy. Herein, the high efficiency of uranium extraction is realized by the piezo property of perovskite BaTiO3, revealing the intrinsically morphological engineering effect on the piezocatalytic performance. Especially, BaTiO3 nanowires (BTO NWs) exhibit not only an excellent piezocatalytic activity with U(VI) extraction rate of 96.8% in a UO2(NO3)2 aqueous solution compared to 71.3% of BaTiO3 nanoparticles (BTO NPs), but also a promising piezocatalyst for U extraction in a real U-mining wastewater with various pH ranges. Piezo response force microscopy and finite elemental simulation show that the piezo response of BTO NWs is much higher than BTO NPs. Additionally, some factors (pH, various ions, different powers) are explored on piezocatalytic efficiency for U(VI) extraction. The results from electron spin resonance and the charge/radical capture experiments confirm that the active species (e-, •O2-, •OH) stemmed from the piezo induction of BTO NWs and BTO NPs in the piezocatalytic U(VI) reduction process. The present work reveals the structure-performance correlation during piezocatalysis and highlights the crucial role of piezocatalysis in dealing with environmental problems.

Ultrafast extraction of uranium from seawater using photosensitized biohybrid system with bioinspired cascaded strategy

The highly effective utilization of uranium resources in global seawater is a viable method to satisfy the rising demands for fueling nuclear energy industry. Herein, inspired by the multi-mechanisms of the marine bacteria for uranium immobilization, CdS nanoparticles are deposited on the cell of marine bacterial strain Bacillus velezensis UUS-1 to create a photosensitized biohybrid system UUS-1/CdS. This system achieves high uranium extraction efficiency using a cascaded strategy, where the bacterial cells guarantee high extraction selectivity and the photosensitive CdS nanoparticles realize cascading photoreduction of high soluble U(VI) to low soluble U(IV) to enhance extraction capacity. As one of the fastest-acting adsorbents in natural seawater, a high extraction capacity for uranium of 7.03 mg g−1 is achieved with an ultrafast extraction speed of 4.69 mg g−1 d−1. The cascaded strategy promisingly improves uranium extraction performance and pioneers a new direction for the design of adsorbents to extract uranium from seawater.

Effects of Impregnated Amidophosphonate Ligand Concentration on the Uranium Extraction Behavior of Mesoporous Silica.

A series of solid-phase uranium extractants were prepared by post-synthesis impregnation of a mesoporous silica support previously functionalized with octyl chains by direct silanization. Five materials were synthesized with 0, 0.2, 0.3, 0.4 and 0.5 mmol of the amidophosphonate ligand DEHCEBP per gram of functionalized solid, and the effect of the ligand concentration on the uranium extraction efficiency and selectivity of the materials was investigated. Nitrogen adsorption–desorption data show that with increasing ligand loadings, the specific surface area and average pore volume decrease as the amidophosphonate ligand fills first the micropores and then the mesopores of the support. Acidic uranium solutions with a high sulfate content were used to replicate the conditions in ore treatment leaching solutions. Considering the extraction kinetics, the equilibration time was found to increase with the ligand concentration, which can be explained by the clogging of micropores and the multilayer arrangement of the DEHCEBP molecules in the materials with their highest ligand contents. The fact that the equilibrium ligand/uranium ratio is about 2 mol/mol regardless of the ligand concentration in the material suggests that all the ligand molecules remain accessible for extraction. The maximum uranium extraction capacities ranged from 30 mg∙g−1 at 0.2 mmol∙g−1 DEHCEBP to 54 mg∙g−1 in the material with 0.5 mmol∙g−1 DEHCEBP. These materials could therefore potentially be used as solid-phase uranium extractants in acidic solutions with high sulfate concentrations.

Preparation of novel porous Al2O3–SiO2 nanocomposites via solution-freeze-drying-calcination method for the efficient removal of uranium in solution

In this work, the efficient extraction of uranium in solution using Al2O3–SiO2-T was reported. Kinetics and isotherm models indicated that the removal process of uranium on Al2O3–SiO2-T accorded with pseudo-second-order kinetic model and Langmuir isotherm model, which showed that the adsorption process was a uniform mono-layer chemical behavior. The maximum adsorption capacity of Al2O3–SiO2-T reached 738.7 mg g−1, which was higher than AlNaO6Si2 (349.8 mg g−1) and Al2O3–SiO2-NT (453.1 mg g−1), indicating that the addition of template could effectively improve the adsorption performance of Al2O3–SiO2 to uranium. Even after five cycles of adsorption–desorption, the removal percentage of uranium on Al2O3–SiO2-T remained 96%. Besides, the extraction efficiency of uranium on Al2O3–SiO2-T was 72.5% in simulated seawater, which suggested that the Al2O3–SiO2-T was expected to be used for uranium extraction from seawater. Further, the interaction mechanism between Al2O3–SiO2-T and uranium species was studied. The results showed that the electrostatic interaction and complexation played key roles in the adsorption process of Al2O3–SiO2-T to uranium.

The effects of amidophosphonate ligand immobilization method on the uranium extraction efficiency of functionalized silica

The effects on the uranium extraction efficiency of the functionalization method of three kinds of functionalized silica materials were evaluated in low sulfate (pH = 2) and high sulfate (pH = 1) solutions, with compositions representative of typical effluents from uranium mines and leaching solutions from uranium ore treatment, respectively. Silica supports were functionalized with amidophosphonate moieties either by peptide grafting or by non-covalent impregnation. Prior to impregnation, the surface of the silica supports was modified with either alkyl chains or ionic liquid groups. The selectivity of the modified silica supports for uranium was determined in the presence of iron and molybdenum as competing cations. Our results show that both incorporation methods yield materials with good extraction efficiency and selectivity in low sulfate solutions. EXAFS data indicate that uranyl species have to first be desulfurized to be extracted by the phosphonate ligand. This process appears more energetically favorable for the impregnated ligands than for the grafted ones under high sulfate conditions; likely because the grafted ligands compete less efficiently with the bidentate sulfates coordination in uranyl coordination sphere.

Development of a rapid method for extraction of uranium from uranium bearing materials using ionic liquid as extracting agent from basic media

The paper presents the development of a rapid method for the direct determination of uranium using liquid scintillation analysis in uranium bearing materials with different uranium concentrations and with different impurity levels (U-ore, Uranium ore concentrate (UOC) and U-metal). Uranium extraction was carried out using hydrophobic ionic liquid Aliquat-336 thiosalicylate, ([A-336][TS]) from diluted samples in basic medium followed by liquid scintillation counting (LSC). Extraction efficiencies for uranium from aqueous medium was studied with very small volumes of ionic liquid under varying volume, pH and uranium concentration of the aqueous medium. Maximum extraction efficiency was achieved near pH 8–11. Uranium was successfully re-extracted from organic medium with nitric acid and electroplated onto stainless steel planchette for alpha spectrometry determination. Maximum re-extraction efficiency with 1 M HNO3 combined with electroplating efficiency observed was 80%. The methodology was applied for real samples. The uranium extraction efficiency using ionic liquid was about 85% for U-metal and UOC samples with comparatively low impurity level; whereas extraction efficiency for U-ore samples was found to be less than 40%. The technique can be applied for nuclear forensic applications as well as nuclear emergency scenarios for a quick initial assessment and isotopic analysis of uranium in the samples.

Accelerated Chemical Thermodynamics of Uranium Extraction from Seawater by Plant-Mimetic Transpiration.

The extraction of uranium from seawater, which is an abundant resource, has attracted considerable attention as a viable form of energy‐resource acquisition. The two critical factors for boosting the chemical thermodynamics of uranium extraction from seawater are the availability of sufficient amounts of uranyl ions for supply to adsorbents and increased interaction temperatures. However, current approaches only rely on the free diffusion of uranyl ions from seawater to the functional groups within adsorbents, which largely limits the uranium extraction capacity. Herein, inspired by the mechanism of plant transpiration, a plant‐mimetic directional‐channel poly(amidoxime) (DC‐PAO) hydrogel is designed to enhance the uranium extraction efficiency via the active pumping of uranyl ions into the adsorbent. Compared with the original PAO hydrogel without plant‐mimetic transpiration, the uranium extraction capacity of the DC‐PAO hydrogel increases by 79.33% in natural seawater and affords the fastest reported uranium extraction average rate of 0.917 mg g−1 d−1 among the most state‐of‐the‐art amidoxime group‐based adsorbents, along with a high adsorption capacity of 6.42 mg g−1 within 7 d. The results indicate that the proposed method can enhance the efficiency of solar‐transpiration‐based uranium extraction from seawater, particularly in terms of reducing costs and saving processing time.

Computational simulation and modelling of uranium extraction using tributylphosphate through membrane extractor

Non-disperse solvent extraction is an effective technique for the extraction of metal ions from aqueous solution. In this study, uranium extraction using n-dodecane solvent containing tributylphosphate extractant in a membrane contactor was investigated. A 2D mathematical model was developed for the fluid flow and mass transfer in the hollow fibre membrane extractor. The equations of the created model were solved using the finite element method. The uranium concentration distribution in the extractor at different extractant concentrations as well as feed acidity was studied. The results showed that there is reasonable good agreement between experimental uranium extraction and modelling outputs at different extractant concentrations. Increasing extractant concentration from 5 to 30% led to the enhancement of uranium extraction from 2.60 to 34.13%. Also, there was an increase in the uranium extraction with increasing feed acidity in the range of 1–3 M. Furthermore, based on the radial uranium concentration distribution, it was found that the main mass transfer resistance in the system was microporous membrane section. Finally, it was obtained that the uranium extraction efficiency could be improved significantly by increasing porosity-to-tortuosity ratio. It was concluded that the membrane specification plays the most important role as the dominant mass transfer resistant was in the membrane subdomain.

Supercritical carbon dioxide and eutectic solvent in conjunction: Novel method for in-situ solvent preparation-dissolution and uranium extraction from solid matrices

Halide anion free hydrophilic Deep Eutectic Solvent (DES) based on choline dihydrogen citrate and urea (1:2 mol ratio) was prepared and successfully employed for dissolution of uranium compounds. Dissolution study was carried out with oxides viz. UO2, UO3 and crude yellow cakes viz. magnesium diuranate, sodium diuranate. Novel route of in-situ, single step eutectic solvent preparation and U compound dissolution was found to be promising in terms of better dissolution efficiency and process simplification. The resultant systems were probed with electrochemistry and UV–Vis spectrophotometry to get an insight about the uranium species. In all the four systems prepared by in-situ mode, stabilization of uranium in U(VI) oxidation state in the form of oxo species was indicated. This halide anion free eutectic system was amenable to be used in SC CO2 extraction set-up. SC CO2 extraction of uranium dissolved in eutectic solvent was found to be influenced by various extraction conditions viz. pressure, temperature, static and dynamic time. Uranium extraction efficiency of upto 65% for oxide system was achievable by SC CO2 modified with TTA.

Direct extraction of uranium from yellow cake and ore matrices using supercritical carbon dioxide

Abstract The study demonstrates the accomplishment of single step, direct supercritical fluid carbon dioxide (SC CO2) dissolution and extraction of uranium from crude matrices viz. yellow cakes (>90%) and rock phosphate ores (70%) employing adducts of trialkyl phosphates and nitric acid, thus avoiding free acid usage and eliminating number of process steps. Rock phosphate ore was made amenable for supercritical fluid extraction (SFE) system by unique strategy of pyrohydrolytic removal of fluorine. Pressure and temperature conditions, which were found to influence uranium extraction efficiency, were optimized at 150 atm. and 323 K. Two milliliter of adduct amount was found to be adequate. Adducts of branched alkyl phosphate, tri-isoamyl phosphate and tri-ethyl hexyl phosphate (TEHP), yield better purity in comparision to straight chain tri-butyl phosphate (TBP).