Desorption Of Uranium Research Articles

Enhancing uranium ion adsorption in wastewater: The role of PEI-PVA/CS xerogel

In the process of recovering uranium resources from uranium-containing wastewater (UCW) via adsorption methods, it is imperative to address challenges related to the stability and selectivity of adsorbents in the separation of uranium ions. Xerogel porous adsorbents have garnered significant research interest for their potential application in uranium ion adsorption, owing to their high porosity, robust plasticity, and abundant functional groups. Based on the efficient separation of uranium by acid-resistant polyvinyl alcohol/chitosan (PVA/CS) xerogel, polyethyleneimine (PEI) was selected to adjust its pores. By examining the characteristics of the modified xerogel both prior to and following U(VI) adsorption, optimizing the conditions for its U(VI) adsorption, and analyzing the separation mechanism of U(VI), the results demonstrate that PEI can effectively modify the pore environment of PVA/CS xerogel. Furthermore, PEI-PVA/CS xerogel maintains consistent U(VI) separation efficacy in UCW across a pH range of 2–7. After five cycles of uranium desorption and adsorption, the adsorption recovery capacity exceeds 97.7 %, with minimal interference from cations. The synergistic effect of -NH2 and -OH functional groups is responsible for the efficient separation of U(VI) by PEI-PVA/CS xerogel. This xerogel demonstrates the stability and selectivity required for U(VI) adsorbents, indicating its potential for engineering applications in UCW treatment.

In-situ Assembly of Polyoxometalate-Based Metal-Organic Framework for High-Efficiency Recovery of Uranium

Extracting uranium from water is crucial for environmental protection and the sustainable nuclear power industry. However, high-efficiency extraction and mild desorption condition still poses significant challenges. Herein, a polyoxometalate-based metal-organic framework (POMOF) for high-performance uranium extraction is prepared by in situ confined encapsulating H3[PW12O40] (PW12) into MIL-101(Cr). The highly dispersed PW12 enables adsorption sites to be sufficiently exposed, supports the pore structure of MIL-101(Cr), while being protected by spatial confinement. Furthermore, its abundant oxygen groups form high-affinity coordination with uranium and provide the pH-dependent conformation switch to achieve selective adsorption and instantaneous structural transformation. The assembly of structure and function makes POMOF exhibit substantial synergistic stability and adsorption capacity. Consequently, the constructed MIL-101(Cr)@PW12 exhibits excellent uranium adsorption ability of 461.88mg/g, as well as superior selectivity towards a wide variety of metal ions. Remarkably, instantaneous desorption can be achieved in 2s under mild desorption conditions of 0.005mol/L HCl, and the adsorption capacity remained at 94.30% after 8 adsorption cycles. POMOF demonstrates the vast potential for uranium capture from water and offers new insight into designing structure and functional synergistic materials for the selective adsorption and instantaneous desorption of uranium.

Microplastics (PN6) as secondary pollutants: The desorption of radionuclides in simulated human digestive fluids

Plastic pollution, particularly in the form of microplastics (MPs), poses a significant threat to both, the environment and human health. Despite extensive research, gaps still exist in understanding the behavior of MPs as carriers of toxic pollutants, including radionuclides. This study investigates the desorption of uranium (U-232) and americium (Am-241) from polyamide nylon 6 (PN6) MPs under various conditions, including acidic environments and simulated human digestive systems. Results demonstrate that PN6-MPs can absorb radionuclides from contaminated waters and extensively desorb them in simulated digestive systems. The desorption efficiency is higher for Am-241 compared to U-232 across different pH ranges, suggesting a nuanced interplay between pH and desorption efficiency. Specifically, PN6-MPs can desorb up to 80 % of bound radionuclides in simulated digestive systems within 24 h and almost quantitatively after 120 h. These findings highlight the potential of PN6-MPs to act as covert carriers of waterborne pollutants, underscoring the need for further research to mitigate the risks posed by plastic pollution to both, the environment and human health.

Efficient Adsorption and Desorption of Uranium(VI) Using a Polymeric Adsorbent: A Combined Theoretical and Experimental Approach with Real-Life Alkaline Leach Liquor

Efficient Adsorption and Desorption of Uranium(VI) Using a Polymeric Adsorbent: A Combined Theoretical and Experimental Approach with Real-Life Alkaline Leach Liquor

Recovery of uranium from conversion production sludge by leaching with nitric acid and subsequent ion-exchange concentration

Physicochemical studies of the sludge of uranium conversion production were carried out to determine the possibility of its processing and return of uranium to the nuclear fuel cycle. It has been established that the sludge was mainly represented by calcium compounds: CaSO4·2H2O (60.1 wt%), CaCO3 (25.1 wt%), CaF2 (13.7 wt%), and silicon dioxide (1.2 wt%). The content of uranium in the sludge was 0.15 wt%. It was shown that it was possible to achieve high degrees of uranium extraction from the sludge using nitric acid as a leaching agent. The use of phosphorus-containing ion-exchanger Tulsion CH93 ensured the effective concentration of uranium from highly acidic pregnant leach solutions. The full dynamic exchange capacity achieved 15.7 kg m−3. The degree of uranium desorption by ACBM (ammonium carbonate/bicarbonate mixture) solutions was 83%. The final product was ammonium uranyl phosphate hydrate NH4UO2PO4∙3H2O with a uranium content of 52.5 wt%.

Uranium desorption from microplastic surfaces

Uranium desorption from microplastic surfaces

Advances in Desorption of Uranium From Loaded Amidoxime Chelating Materials

Advances in Desorption of Uranium From Loaded Amidoxime Chelating Materials

Elucidating mobilization mechanisms of uranium during recharge of river water to contaminated groundwater

The recharge of stream water below the baseflow water table can mobilize groundwater contaminants, particularly redox-sensitive and sorptive metals such as uranium. However, in-situ tracer experiments that simulate the recharge of stream water to uranium-contaminated groundwater are lacking, thus limiting the understanding of the potential mechanisms that control the mobility of uranium at the field scale. In this study, a field tracer test was conducted by injecting 100 gal (379 l) of oxic river water into a nearby suboxic and uranium-contaminated aquifer. The traced river water was monitored for 18 days in the single injection well and in the twelve surrounding observation wells. Mobilization of uranium from the solid to the aqueous phase was not observed during the tracer test despite its pre-test presence being confirmed on the aquifer sediments from lab-based acid leaching. However, strong evidence of oxidative immobilization of iron and manganese was observed during the tracer test and suggested that immobile uranium was likely in its oxidized state as U(VI) on the aquifer sediments; these observations ruled out oxidation of U(IV) to U(VI) as a potential mobilization mechanism. Therefore, desorption of U(VI) appeared to be the predominant potential mobilization mechanism, yet it was clearly not solely dependent on concentration as evident when considering that uranium-poor river water (<0.015 mg/L) was recharged to uranium-rich groundwater (≈1 mg/L). It was possible that uranium desorption was limited by the relatively higher pH and lower alkalinity of the river water as compared to the groundwater; both factors favor immobilization. However, it was likely that the immobile uranium was associated with a mineral phase, as opposed to a sorbed phase, thus desorption may not have been possible. The results of this field tracer study successfully ruled out two common mobilization mechanisms of uranium: (1) oxidative dissolution and (2) concentration-dependent desorption and ruled in the importance of advection, dispersion, and the mineral phase of uranium.

PHYSICAL AND CHEMICAL FOUNDATIONS OF THE EXTRACTION REFINING OF NATURAL URANIUM

The paper presents the results of studies of the physicochemical processes of the extraction and nitric acid purification of uranium salts obtained by the method of precipitation of ammonium uranyl carbonate (AUC) from ore solutions of leaching of uranium and polymetallic ores with their subsequent dissolution in nitric acid. It is shown that the process of extraction on a mixture of tributyl phosphate (TBP) in kerosene makes it possible to obtain high-purity uranium oxide. For the selective extraction of impurities, the process of uranium extraction from the nitric acid medium was carried out with a mixture of TBP and di(2-ethylhexyl) phosphoric acid (DEHPA) in kerosene. The first uranium concentration 40…50 g/L simulated the process of uranium desorption, the second ≤ 100 g/L simulated the process of dissolution of uranium oxide. The study of the uranium extraction made it possible to determine the required number of extraction stages to achieve the minimum uranium content in the raffinate and the maximum extractant capacity, which ensured the specified coefficients of uranium purification from metal impurities (V, Mo, etc.). After extraction, the nitric acid raffinate served as a raw material for the production of a mineral fertilizer – sodium nitrate.

The effect of EDTA on the desorption of uranium from calcium silicate hydrate matrices

The effect of EDTA on the desorption of uranium from calcium silicate hydrate matrices

Simple and facile preparation of tunable chitosan tubular nanocomposite microspheres for fast uranium(VI) removal from seawater

The seawater contains 4.5 billion tons of uranium(VI), which is quite enough to provide a continuous supply of infinite nuclear energy. However, it is a sudden need to develop adsorbents from abundant available source, easy collect property, large durability and high uranium(VI) adsorption capacity from seawater. In this work, a single-step process was developed for the preparation of chitosan (Cs) functionalized tubular carbon nanocomposite microspheres (CsFTnCM) for efficient uranium(VI) adsorption from seawater. The application of newly synthesized adsorbent for uranium(VI) removal from seawater is explored. Thus prepared adsorbent (CsFTnCM2) is found to adsorb 99.5% uranium(VI) from seawater. The CsFTnCM2 (Cs/FTn,1:1) comprising NH2 and COOH content approximately 0.61 mmol/g and 0.23 mmol/g, respectively. This kind of adsorbent possessed a uranium(VI) loading capacity of 0.660 (mg/g) from seawater. The adsorption kinetics not only dependent on the physical structure of the adsorbent but depends on the proportion of FTn in the Cs-matrix. However, the kinetics of uranium(VI) adsorption was increased by increasing the content of FTn up to a certain limit. The adsorption efficiency of uranium(VI) was not affected by the presence of coexisted ions, whose concentration is 1000 times greater than uranium(VI) in seawater. The desorption of uranium(VI) from the seawater exposed adsorbents were investigated and the results showed the uranium(VI) strip from the adsorbents found to be efficiently using Na2CO3.

Processing technology for carbonate ore from the Argun deposit

Priargun Mining and Chemical Association has been producing uranium in the Streltsov ore field for more than 50 years. The main ore bodies with high content of uranium have been mined out during this period of time, and the uranium content has dropped in ore which is currently extracted. In connection with this, appraisal of the mineral resources and mineral reserves of Priargun MCA has been accomplished. The Argun ore is composed of a few process types—iron silicate and uranium, silicate–uranium–molybdenum, carbonate and uranium, carbonate and molybdenum, carbonate–uranium–molybdenum and rebellious ore (contains zirconium and brannerite). It is required to undertake technology-based rating and certification of the Argun ore. The autoclave leaching technology is found to be higher economically efficient as against the atmospheric leaching technology due to lower operating expenses. From the preliminary studies, four samples of anion-exchange resins are recommended for further testing: A500Y, BM77-14, D299 and Ambersep 920UXL SO4. These ion-exchangers were used to analyze their influence on sorption–desorption of uranium and molybdenum. All these ion exchangers had preserved their sorption capacity in 10 sorption–desorption cycles. Based on the studies into adsorption of uranium and molybdenum from leached slurry at the Argun deposit, the optimal sorbent for extraction and separation of uranium and molybdenum is Ambersep 920UXL SO4. Producibility of natural uranium to meet ASTM C 967-13 standards is analyzed on a laboratory scale. The produced uranium concentrate contains much less impurities than it is stipulated by International Standard Specification ASTM С 967-13. The action chart of processing of carbonate ore from the Argun and Zherlovoe deposits is developed and economically justified.

Synthesis of a Novel Composite Hydrous Titanium Oxide- Hydroxyapatite for Adsorbing Uranium from Waste Effluents

In this paper; a novel composite (HAP@HTO)derived from hydrous titanium oxide (HTO) extracted from Rosetta ilmenite mineral and hydroxyapatite (HAP) was formed by co-precipitation method,specified and used for uranium preconcentration from its solutions. Batch tests were performed to investigate its selectivity towards uranium; maximum adsorption efficiency reached at pH 2.5, 120 minutes contact time, 900 mg L–1 uranium concentration and adsorbent ratio (0.1g/75 mL). The equilibrium data fitted well with Langmuir adsorption isotherm. From Kinetics and thermodynamics data; process was fast, fitted well with pseudo-second order, spontaneous and exothermic. The percentage desorption of uranium reached its maximal at 15 minutes equilibrium time using 1 mol L-1 H2SO4. Thereby, (HAP@HTO)composite has promising potential applications in extracting U (VI) from its aqueous solutions in nuclear fuel field and environmental pollution cleanup.

Understanding Contaminant Migration Within a Dynamic River Corridor Through Field Experiments and Reactive Transport Modeling

The behavior of a persistent uranium plume within an extended river corridor at the DOE Hanford site is dominantly controlled by river stage fluctuations in the adjacent Columbia River. The plume behavior is further complicated by substantial heterogeneity in physical and geochemical properties of the host aquifer sediments. Multi-scale field and laboratory experiments and reactive transport modeling were integrated to understand the complex plume behavior influenced by highly variable hydrologic and geochemical conditions in time and space. In this paper, we (1) describe multiple data sets from field-scale uranium adsorption and desorption experiments performed at our experimental well-field, (2) develop a reactive transport model that incorporates hydrologic and geochemical heterogeneities characterized from multi-scale and multi-type datasets and a surface complexation reaction network based on laboratory studies, and (3) compare the modeling and observation results to provide insights on how to refine the conceptual model and reduce prediction uncertainties. The experimental results revealed significant spatial variability in uranium adsorption/desorption behavior, while modeling demonstrated that ambient hydrologic and geochemical conditions and heterogeneities in sediment physical and chemical properties both contributed to complex plume behavior and its persistence. This research underscores the great challenges in adequately characterizing this type of site to model the reactive transport processes over scales of 10 m or more. Our analysis provides important insights into the characterization, understanding, modeling, and remediation of groundwater contaminant plumes influenced by dynamic surface water and groundwater interactions.

Synthesis of α-aminophosphonate based sorbents – Influence of inserted groups (carboxylic vs. amine) on uranyl sorption

A one-pot synthesis procedure is designed for preparing three α-aminophosphonates (R-H, R-COOH, and R-NH2); through the reaction of amine precursors (aniline, anthranilic or o-phenylene diamine, respectively) with salicylaldehyde and triphenylphosphite, under controlled conditions. These materials are first characterized by elemental analysis, FTIR, 1H NMR, 31P NMR, BET, DLS, pHzpc, TGA and titration. In a second step, the sorption properties are compared for U(VI) recovery from mildly acidic solutions. At the optimum pH (i.e., pH 4) the sorbents can be ranked according the series: R-H (1.057 mmol U g−1) > R-NH2 (0.746 mmol U g−1) > R-COOH (0.533 mmol U g−1). The isotherms are fitted by the Langmuir equation. Uranium uptake is relatively fast: under selected experimental conditions, the equilibrium is reached within 90 min of contact. The kinetic profiles are indistinctly fitted by the model of resistance to intraparticle diffusion and the pseudo-first order rate equation. The study of sorption thermodynamics shows substantial changes between the sorbents: uranyl uptake is endothermic with R-H and R-NH2 sorbents, while the reaction is exothermic with R-COOH sorbent. The diversity in functional groups and the speciation of uranyl in sulfuric acid solutions induce metal-binding through a combination of chelation and anion-exchange mechanisms (in function of pH). Sodium bicarbonate solutions achieve complete desorption of uranium from loaded-sorbents; the resins can be recycled for a minimum of 4–5 cycles with limited loss in efficiencies. The successful application of these resins for uranium recovery from acidic ore leachates demonstrates their promising properties for valorization of low-grade ores.

Uranium(VI) recovery from acidic leach liquor using manganese oxide coated zeolite (MOCZ) modified with amine

Manganese oxide coated zeolite modified with trioctyl amine (MOCZ/TOA) was tested for adsorption of uranium. Different experiments were performed to evaluate the optimum adsorption conditions; pH, dose, uranium concentration, temperature variation and contact time. Maximum adsorption capacity reached 99 mg/g according to Langmuir model. The study of thermodynamic parameters showed that sorption process is non spontaneous, exothermic and random. Studies on process kinetics showed that the process obeys pseudo-second order model. Uranium desorption was accomplished using 0.3 M H2SO4. Optimum conditions were carried out for uranium recovery from sedimentary geologic sample from Gattar area, North Eastern Desert, Egypt. The final uranium precipitate was characterized by ICP-OES technique.

Sorption of Uranium (VI) Ions by a Sorbent Based on a Copolymer of Maleic Anhydride with Styrene Modified by N, Nand#39;-diphenylguanidine

In this paper the results of a study on the extraction and concentration of micro-quantities of uranium (VI) with a polymeric chelating sorbent with fragments of N, N and#39;diphenylguanidine is discussed. There was studied a static sorption capacity on K+ ions ((SSC = 9.3 mmol / g) and there were determined the ionization constants of ionogenic groups ( =3.97; =8.47) by potentiometric titration. The optimal conditions of the sorption of elements (pHopt, sorption time - τ, the influence of ionic strength - μ) were determined by the dependence of the sorption capacity (SC, mg/g) on the parameter being studied; the sorption capacity of the sorbent (SC) was determined from the saturation curve constructed under optimal sorption conditions. The maximum degree of extraction of uranium by sorbents is achieved from solutions with pH 5. Sorption equilibrium is achieved within 2 hours of contact of the solution with the sorbent. With an increase in the concentration of the uranyl ion in the solution, the amount of the sorbed metal increases, and at a concentration of 8•10–3 mol/l, it becomes maximal (pH = 5, = 8•10–3 mol/l, Vgen = 20 ml, msorb. = 0.05 g, SC = 1258 mg/g). Limits of detection (3, n=20) are 13.9 ng/ml. The effect of various mineral acids(HClО4, H2SО4, HNО3, HCl) with the same concentrations on the desorption of uranium (VI) from the sorbent was studied. The developed technique was applied to determine uranium in oil sludge.

Sorption of Uranium (VI) Ions by a Sorbent Based on a Copolymer of Maleic Anhydride with Styrene Modified by N, Nand#39;-diphenylguanidine

In this paper the results of a study on the extraction and concentration of micro-quantities of uranium (VI) with a polymeric chelating sorbent with fragments of N, N and#39;diphenylguanidine is discussed. There was studied a static sorption capacity on K+ ions ((SSC = 9.3 mmol / g) and there were determined the ionization constants of ionogenic groups ( =3.97; =8.47) by potentiometric titration. The optimal conditions of the sorption of elements (pHopt, sorption time - τ, the influence of ionic strength - μ) were determined by the dependence of the sorption capacity (SC, mg/g) on the parameter being studied; the sorption capacity of the sorbent (SC) was determined from the saturation curve constructed under optimal sorption conditions. The maximum degree of extraction of uranium by sorbents is achieved from solutions with pH 5. Sorption equilibrium is achieved within 2 hours of contact of the solution with the sorbent. With an increase in the concentration of the uranyl ion in the solution, the amount of the sorbed metal increases, and at a concentration of 8•10–3 mol/l, it becomes maximal (pH = 5, = 8•10–3 mol/l, Vgen = 20 ml, msorb. = 0.05 g, SC = 1258 mg/g). Limits of detection (3, n=20) are 13.9 ng/ml. The effect of various mineral acids(HClО4, H2SО4, HNО3, HCl) with the same concentrations on the desorption of uranium (VI) from the sorbent was studied. The developed technique was applied to determine uranium in oil sludge.

Field experiments of surface water to groundwater recharge to characterize the mobility of uranium and vanadium at a former mill tailing site

Characterizing the mobility of uranium and vanadium in groundwater with a hydraulic connection to surface water is important to inform the best management practices of former mill tailing sites. In this study, the recharge of river water to the unsaturated and saturated zones of a uranium-contaminated alluvial aquifer was simulated in a series of forced-gradient single- and multi-well injection-extraction tests. The injection fluid (river water) was traced with natural and artificial tracers that included halides, fluorobenzoates, lithium, and naphthalene sulfonate to characterize the potential mass transport mechanisms of uranium and vanadium. The extraction fluid (river water/groundwater mixture) was analyzed for the tracers, uranium, and vanadium. The results from the tracers indicated that matrix diffusion was likely negligible over the spatiotemporal scales of the tests as evident by nearly identical breakthrough curves of the halides and fluorobenzoates. In contrast, the breakthrough curves of lithium and naphthalene sulfonate indicated that sorption by cation exchange and sorption to organic matter, respectively, were potential mass transport mechanisms of uranium and vanadium. Uranium was mobilized in the saturated zone containing gypsum (gypsum-rich zone), the vadose zone (vadose-rich zone), and the saturated zone containing organic carbon (organic-rich zone) whereas vanadium was mobilized only in the saturated gypsum-rich zone. The mechanisms responsible for the mobilization of uranium and vanadium were likely dissolution of uranium- and vanadium-bearing minerals and/or desorption from the gypsum-rich zone, flushing of uranium from the vadose-rich zone, and desorption of uranium from the organic-rich zone due to the natural contrast in the geochemistry between the river water and groundwater. The experimental design of this study was unique in that it employed the use of multiple natural and artificial tracers coupled with a direct injection of native river water to groundwater. These results demonstrated that natural recharge and flooding events at former mill tailing sites can mobilize uranium, and possibly vanadium, and contribute to persistent levels of groundwater contamination.

How the distribution coefficient of 238U in natural soils is affected by the method used to obtain the soil solution and its dependency on structural characteristics.

A systematic study on desorption of uranium in a natural soil has been carried out to reduce the level of uncertainty associated with the method employed to determine the values of the distribution coefficient (Kd). Generally, the operating method used to extract and analyze the soil solution determines the Kd values. Here, the centrifugation method has been used to obtain soil solution extracts. Several procedural parameters have been considered such as incubation time, the level of soil moisture relative to saturation (saturation degree) and centrifugation speed (equivalent to effective suction). In order to analyze the influence of soil structural characteristics, this study considers three grain-size fractions of soil: loamy coarse sand, loamy fine sand, and loam, all of which are obtained from a natural soil collected in a uranium mineralized area. Our results indicate that neither incubation time nor centrifugation speed influence the determination of Kd for uranium. The results also indicate that the level of soil moisture is the most important factor for determining 238U-Kd. It has been shown that the influence of moisture on Kd also depends on the structural characteristic of the soil. For the loamy coarse sand subsample, the moisture level during the incubation period showed a significant influence on the Kd. In addition, through the use of regression analysis, the pH was identified as the cofactor with the greatest influence on Kd of uranium.