Adsorption Of Uranyl Ions Research Articles

Constructing yeast-modified polypropylene amidoxime membrane toward highly-selective adsorption of U(VI) from seawater

To extract uranium from seawater, the adsorbent needs to have high selectivity for uranium and good hydrophilicity, and could resist biological pollution and prevent Marine microorganisms from blocking chelate sites. For effective uranium extraction, a straightforward crosslinking technique is used to create a highly selective and biofouling-resistant poly(amidoxime) (PAO-Y) membrane. PAO-Y is characterized by FT-IR, SEM, EDS, XPS, BET, WCA and NMR techniques. The effects of solution acidity, concentration, and adsorption time on its adsorption of uranyl ions and vanadyl ions are investigated. The composite material (PAO-Y) exhibits higher selective adsorption and affinity towards U(VI) compared to V(V). In simulated marine environment experiments, the material exhibited an adsorption capacity of 10.39 mg·g−1 for U(Ⅵ), which is five times higher than that for V(V). Furthermore, the adsorption partition constant for U(Ⅵ) is 1.44 × 105 mL·g−1, two orders of magnitude greater than that for V(V). The DFT calculations revealed specific coordination modes between PAO-Y and uranyl/vanadyl ions, elucidating the selective adsorption mechanism of uranium. The pentadentate coordination mode is shown by DFT calculations to be the most stable one. DFT calculations also show that the increase in the number of amino acid groups increases the interaction between the coordinating ligands and uranyl, but decreases the interaction between the coordinating ligands and vanadyl. These findings suggest that PAO-Y effectively enhance the selectivity and affinity towards uranyl ions during uranium extraction from marine environments and may find practical applications. After 15 days of continuous flow of 30 L natural seawater, PAO-Y obtained a total uranium capture capacity of 1.969 mg·g−1 in the fixed-bed adsorption system, making it a suitable candidate for uranium extraction from natural seawater.

Redox-active sp2-c connected metal covalent organic frameworks for selective detection and reductive separation of uranium

It is economically desirable to develop a material that can simultaneously detect and recover uranium. Herein, a CC-bridged two-dimensional metal-covalent organic framework (Cu-BTAN-AO MCOF) was constructed by condensation of metal single crystals with a rigid structure (Cu3(PyCA)3) and cyano monomers (BTAN) via Knoevenagel reaction for simultaneous detection and adsorption of uranium. The amidoxime group within the pore and the presence of unsaturated Cu(I) in the framework facilitate the adsorption of uranyl ions onto the amidoxime group, leading to fluorescence quenching via the photoinduced electron transfer (PET) mechanism, achieving a detection limit of as low as 167 nM uranyl ions. Furthermore, Cu-BTAN-AO demonstrates exceptional efficiency in capturing uranium from wastewater characterized by rapid kinetics and superior selectivity. It is noteworthy that Cu-BTAN-AO is the first example of simultaneous detection, adsorption and chemical reduction of uranium using metal centers and functional groups in MCOF, indicating that Cu-BTAN-AO has great potential for the detection and recovery of uranium-containing wastewater. This design strategy may also be applicable to advancing sensing and energy materials for other important metal ions.

Overcoming Chemical Dissociation Processes: Electrochemical Modulation of High‐Affinity Binding Sites for Rapid Uranium Extraction from Seawater

AbstractCurrently reported adsorption (hydroxyl or amidoxime) groups must dissociate hydrogen ions to form ─O− units for the coordination with uranyl ions. However, this process suffers a high energy barrier for bond dissociation, leading to the sluggish uptake speed and low adsorption capacity for uranium extraction from natural seawater. Herein, this study proposes a strategy for electrochemical modulation of adsorption sites, which overcomes the chemical dissociation processes of hydrogen ions. Poly‐2,5‐dihydroxy‐1,4‐benzoquinone containing redox carbonyl groups is intercalated into the channels of a covalent organic framework (COF) through in situ cross‐linking of 2,5‐dihydroxy‐1,4‐benzoquinone. Under electrochemical modulation, the C═O groups are transformed into adjacent phenol–oxygen anions to cooperate with the coordination atoms (O and N) on the COF channel for rapid binding of uranyl ions, which gave an absorption rate of 4.2 mg g−1 d−1 (≈3.3 ppb of uranium in natural seawater). Notably, the COF‐based electrodes delivered an average capacity of ≈20.8 mg‐U per g for uranyl ion adsorption during 5 days of extraction, ≈3000 times larger than that of classical tannin‐based adsorbents. The proposed method for preparing electrochemically modulated binding sites is expected to provide guidance for designing high‐efficiency adsorbents in the future.

In Situ Synthesis of Polyamidoxime Chains Inside the Negative‐Charged Confining Fields for Efficient Adsorption of Uranyl Ions

In Situ Synthesis of Polyamidoxime Chains Inside the Negative‐Charged Confining Fields for Efficient Adsorption of Uranyl Ions

Surface structural transformation and adsorption performance of poly(triazine imide)

Abstract Poly(triazine imide) synthesized by the molten salt route with incorporation of Li+ and Cl‒ ions (PTI/Li+Cl−) was prepared by rational controlling of the washing extent. The surface transformation of the phase-pure PTI framework incurred by thorough washing has been confirmed by a systematic analysis based on x-ray diffraction, Ultraviolet Raman, atomic force microscope, and x-ray photoelectron spectroscopy measurements. Uranyl ion adsorption experiments further support the surface structural transformation from triazine-unit PTI to heptazine-based graphitic carbon nitride. Efforts on the exploration of PTI material application should be mainly directed toward the waterless fields to give good repeatability.

Investigations on the Equilibrium, Kinetics and Thermodynamics of Anionic Polyacrylamide-Based Monolith Adsorption of Uranium (VI) From Aqueous Solution

Our previous work discussed synthesizing and characterizing a macroporous anionic polyacrylamide monolith as a new adsorbent. This monolith showed the potential removal of heavy metals and organic dye molecules in aqueous solutions. In this work, we continue our work and study the effectiveness of the synthesized monoliths in removing uranyl ions (UO22+) from aqueous solutions. Our investigation conclusively determined the impact of pH, contact time, monolith dosage, initial metal concentration and temperature on removing uranyl ions. Several isotherm models, including the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models, were employed to analyze the adsorption data; the Freundlich and Langmuir models were the most suitable for describing the equilibrium data. According to the Langmuir model, the monolith has an adsorption capacity of 111 mg/g of uranyl ions at 25 °C. The pseudo-second-order kinetic model was suitable for describing the uranyl ion adsorption onto the synthesized monolith with an R2 coefficient ³ 0.999. The thermodynamic studies showed that uranyl ions adsorb onto the monolith spontaneously and endothermically.

Porous layered MOFs (Cu-BDC) for highly efficient uranyl-ion adsorption from aqueous solutions

Porous layered MOFs (Cu-BDC) for highly efficient uranyl-ion adsorption from aqueous solutions

Study on Natural Diatomite as an Adsorbent for Uranyl (VI) ions, Using Spectrophotometric Method

This work is based on the investigation of uranyl (VI) ion adsorption onto natural diatomite using batch sorption method under different parameters such as pH, initial ion concentration, adsorbent amount and effect of sulfate ion as a foreign ion. 8-hydroxyquinoline is used as a chromogen forming a pale-yellow complex with ions in chloroform, the absorbance was measured spectrophotometrically at λmax 460 nm, obtaining a linear calibration curve with R2=0.998, LOD=3.03 mg/L and LOQ=9.21 mg/L. Prior to the implementation of the batch experiment, the morphology and composition of diatomite was confirmed using XRF (Bruker S8 Tiger), XRD (Bruker D5005), FTIR (Bruker Vector 22), and SEM (JEOL JSM-5610 LV) techniques. From spectrophotometric analysis, the results showed that the maximum uranyl ion adsorption distribution coefficient reached at the initial concentration of 50ppm, pH 4.5, contact time 5hrs and adsorption dosage of 2 g/L. There was no significant effect of sulfate ion on the adsorption affinity. Adsorption isotherm was studied by Langmuir which was favourable model fitting with R2=0.996 and maximum adsorption capacity of 16mg/g, and separation factor RL = 0.0122. Freundlich isotherm model also applied for the same data and give a very straight line with R2= 1.00 and maximum adsorption capacity of 200 mg/g. Temkin model was less fit and gave a negative isotherm curve with R2= 0.78, KT= 0.9405 L/g, bT= 24.724 J/mol. Langmuir and Freundlich isotherms gave exothermic adsorption while Temkin gave an endothermic one.

Adsorption of uranyl ion on hexagonal boron nitride for remediation of real U-contaminated soil and its interpretation using random forest

Acid leaching has been widely applied to treat contaminated soil, however, it contains several inorganic pollutants. The decommissioning of nuclear power plants introduces radioactive and soluble U(VI), a substance posing chemical toxicity to humans. Our investigation sought to ascertain the efficacy of hexagonal boron nitride (h-BN), an highly efficient adsorbent, in treating U(VI) in wastewater. The adsorption equilibrium of U(VI) by h-BN reached saturation within a mere 2 h. The adsorption of U(VI) by h-BN appears to be facilitated through electrostatic attraction, as evidenced by the observed impact of pH variations, acidic agents (i.e., HCl or H2SO4), and the presence of background ions on the adsorption performance. A reusability test demonstrated the successful completion of five cycles of adsorption/desorption, relying on the surface characteristics of h-BN as influenced by solution pH. Based on the experimental variables of initial U(VI) concentration, exposure time, temperature, pH, and the presence of background ions/organic matter, a feature importance analysis using random forest (RF) was carried out to evaluate the correlation between performances and conditions. To the best of our knowledge, this study is the first attempt to conduct the adsorption of U(VI) generated from real contaminated soil by h-BN, followed by interpretation of the correlation between performance and conditions using RF. Lastly, a. plausible adsorption mechanism between U(VI) and h-BN was explained based on the experimental results, characterizations, and a. comparison with previous adsorption studies on the removal of heavy metals by h-BN.

Study on uranium ion adsorption property of porous glass modified with amidoxime group.

In this paper, we prepared three types of porous glasses (PGs) with specific surface areas of 311.60 m2/g, 277.60 m2/g, and 231.38 m2/g, respectively, via borosilicate glass phase separation. These glasses were further modified with amidoxime groups (AO) using the hydroxylamine method, yielding adsorbents named 1.5-PG-AO, 2-PG-AO, and 3-PG-AO. The adsorption performance of these adsorbents under various conditions was investigated, including sorption kinetics and adsorption mechanisms. The results reveal that the number of micropores and specific surface area of PG are significantly reduced after AO modification. All three adsorbents exhibit similar adsorption capabilities. Particularly, pH has a pronounced effect on U (VI) adsorption of PG-AO, with a maximum value at pH = 4.5. Equilibrium adsorption is achieved within 2h, with a maximum adsorption capacity of 129mg/g. Notably, a uranium removal rate of 99.94% is attained. Furthermore, the adsorbents show high selectivity in uranium solutions containing Na+ or K+. Moreover, the adsorbents demonstrate exceptional regeneration ability, with the removal rate remaining above 80% even after undergoing five adsorption-desorption cycles. The adsorption reaction of uranium on PG-AO involves a combination of multiple processes, with monolayer chemisorption being the dominant mechanism. Both the complex adsorption of AO and the ion exchange and physical adsorption of PG contribute to the adsorption of uranyl ions on the PG-AO adsorbents.

Novel chitosan-based derivative material loaded with the diethylenetriamine pentamethylene phosphonic acid for efficient adsorption of uranyl ions from weakly acidic wastewater

An ideal adsorption material capable of efficiently and selectively capture uranyl ions from radioactive wastewater remains a serious challenge. In this work, diethylenetriamine pentamethylene phosphonic acid (DTPMP), one of the common metal ion extractants with five negatively charged phosphate groups, was innovatively used to modify chitosan chains for better uranyl adsorption capacity. Two chitosan derivatives were designed, DTPMP protonated chitosan crosslinked with potassium tripolyphosphate (DTPP) and DTPMP reinforced potassium tripolyphosphate crosslinked chitosan (DCTPP), in which DCTPP possessed an excellent maximum adsorption capacity of up to 1316.82 mg/g for uranyl ions at 298 K. Compared to the 60 min taken-for 90 % by DTPP, the time taken to reach same percentage by DCTPP was only about 5 min, indicating its superior uranyl removal efficiency. Outstanding affinity and capture performance could be attributable to the remarkable mesoporous surfaces and abundant P-containing active sites. Influence of initial solution pH on the removal efficiency for uranyl was significantly attenuated due to the C-P bond. The fitting results of kinetic and isotherm models revealed that the uranyl adsorption mechanisms by as-prepared composites were physicochemical processes, mainly including surface complexation/chelation, chemisorption, and intra-particle diffusion. Theory calculations predicted potential binding modes and electrons transfer between the organophosphonic acid molecule and uranyl unit, validating the strong interaction and reduction of phosphorus-oxygen groups on uranyl ions. Furthermore, DCTPP showed great potentials to separate uranyl from simulated uranium-contaminated wastewater. Design and development of novel chitosan derivatives will provide theoretical support and technical reference for an effective treatment of weakly acidic radioactive wastewater.

Hierarchical porous cellulose monolith prepared by thermally induced phase separation for high-efficiency uranium adsorption

The development and application of new and efficient adsorption materials are key issues in the treatment of nuclear wastewater. This paper introduces a novel hierarchical porous amidoxime cellulose monolith synthesized through thermally induced phase separation (TIPS). The inherent hydrophilicity of cellulose, combined with the graded porous structure achieved through TIPS (with a specific surface area of 10.36 m2/g), endows the material with strong mass transfer ability. The adsorption properties of this amidoxime cellulose monolith for uranyl ions were evaluated in both batch and flow-through column adsorption scenarios. Remarkably, the adsorption saturation was achieved within a concise period of 13 h in batch adsorption. The hierarchical porous structure of the amidoxime cellulose monolith exhibited exceptional adsorption performance for uranyl ion, achieving a removal rate of 99.99 %. Moreover, this removal rate was sustained for 200 min, and the monolith proved recyclable for at least 5 cycles in flow-through column adsorption tests involving nuclear wastewater. When used for adsorption in real wastewater environments, the material achieved the removal of over 99.96 % of total α and β radioactivity. These findings underscore the high efficiency of the newly developed hierarchical porous amidoxime cellulose monolith in uranyl ion adsorption. They emphasize its substantial potential for the efficient adsorption and removal of uranyl ion from nuclear wastewater.

Janus photothermal adsorbent for solar-powered simultaneous uranium extraction and co-production of freshwater and sea salt from seawater

Ocean reserves massive water and mineral resources. The success in uranium extraction and desalination from seawater is expected to alleviate the severe situation of energy and freshwater scarcities around the world. Herein, a novel Janus photothermal adsorbent was fabricated via sequential electrospinning for simultaneous uranium extraction and co-production of freshwater and sea salt from seawater. It consisted of a hydrophilic polyamidoxime (PAO) nanofibrous mat as the bottom layer for uranyl ion adsorption and a hydrophobic polyvinylidene fluoride (PVDF)/MXene (Ti3C2Tx) composite nanofibrous mat as the upper layer to capture and convert solar energy to heat. With the assistance of 1-sun illumination, the Janus adsorbent exhibited 6.05 mg g−1 of uranium adsorption capacity within 28 days from natural seawater, resulting in a 30.1 % increase compared to that in dark and achieved 1.36 kg m–2h−1 of water evaporation rate in natural seawater. An outdoor solar-powered adsorption coupling with evaporation test of this Janus adsorbent demonstrates that 6.40 kg m−2 of freshwater, 2.02 mg m−2 of uranium and 0.22 kg m−2 of sea salt were co-produced within 9 h operation. This study on the Janus adsorbent paves a promising way to the comprehensive development of ocean resources in low-carbon and sustainable strategy.

Preparation of solar photo-thermal driven aerogel and clarification of the mechanism for enhanced uranium adsorption

The oceans contain a significant amount of uranium, a valuable resource for nuclear power and fuel applications. However, current technologies for extracting uranium from seawater have limitations, including low efficiency and high energy consumption. Aerogels are promising materials for uranyl ion adsorption due to their high porosity and abundant active sites. This study presents a novel approach for efficient uranium extraction from seawater using a full-fiber-based PAO/PPy aerogel. This aerogel enables rapid diffusion of uranium and accelerated adsorption in the presence of heat generated by sun irradiation, achieving a high adsorption capacity of 69.66 mg g−1 under 1 kW m−2 in 50 mg L−1 solution. The dynamical and thermodynamic simulations indicate the presence of both chemisorption and physisorption throughout the adsorption process. Additionally, the composite aerogel is demonstrated antifouling performance and excellent selectivity of U(VI) in a mixed ionic solution. The present study offers a novel approach for the rational design of aerogel adsorbents that can effectively extract uranium from seawater in outdoor environments, without the need for additional energy input.

Strengthening Fe(II)/Fe(III) Dynamic Cycling by Surface Sulfation to Achieve Efficient Electrochemical Uranium Extraction at Ultralow Cell Voltage.

Electrochemically mediated Fe(II)/Fe(III) redox-coupled uranium extraction can efficiently reduce the cell voltage of electrochemical uranium extraction (EUE). How to regulate the surface structure to enhance the uranium acyl ion adsorption capacity and strengthen the Fe(II)/Fe(III) redox cycle process is crucial for EUE. In this work, we developed surface sulfated nanoreduced iron (S-NRI) for EUE and exhibited improved properties for EUE at an ultralow cell voltage (-0.1 V). Compared with a nanoreduced iron (NRI) adsorbent, S-NRI displayed faster electrochemical extraction kinetics properties and higher extraction efficiency and capacity for uranium. In a more complex seawater electrolyte containing uranyl ion concentration ranging from 1 to 20 ppm, the removal efficiency could reach almost ∼100% after EUE for 24 h. At a higher 50 ppm uranium acyl ion concentration in a seawater electrolyte, S-NRI exhibited higher extraction capacity (755.03 mg/g), which is better than 528.53 mg/g of NRI at a cell voltage of -0.1 V. Outstanding EUE property could be attributed to the fact that sulfate species (M-SO42-) on the S-NRI surface not only enhanced selective adsorption of uranyl ions but also strengthened the Fe(II)/Fe(III) redox cycle, which accelerated electron transfer between Fe(II) and U(VI), promoted the regeneration of Fe(II) active sites, and finally enhanced the EUE property.

Removal of uranium (VI) ion from aqueous solution using kaolinite

In this study, the adsorption of uranyl ion (UO22+) onto kaolinite mineral from its aqueous solutions has been investigated using the batch experiment method under different parameters. Uranyl ions were measured spectrophotometrically using 8-hydroxy quinoline as a chromogen. The effect of contact time, pH, initial ion concentration, adsorbent amount, and ionic strength has been designated to establish this study. The adsorbed percentage increased dramatically as the pH increased from 1 to 5; from 28% to 70% at well-known parameters of contact time, pH value, adsorbent amount, and initial ion concentration. Above pH 5, the adsorption affinity was virtually unchanged. On the other hand, the adsorbed percentage decreased from 68% to 57% when the initial uranyl ion concentration increased from 90 to 120 ​mg/L. The overall results showed that the maximum uranyl ion adsorption percentage reached at the initial concentration of 90 ​ppm, pH 4.5, contact time of 5 ​h, and an adsorbent dosage of 4.0 ​g/L. The adsorption behavior of the uranium ion on kaolinite obeys Langmuir (1918) and Freundlich isotherm models, with R2 value above 0.998 for both.

Efficient Removal of Uranyl Ions Using PAMAM Dendrimer: Simulation and Experiment

In this work, using atomistic molecular dynamics (MD) simulations and polymer-assisted ultrafiltration experiments, we explore the adsorption and removal of uranyl ions from aqueous solutions using poly(amidoamine) (PAMAM) dendrimers. The effects of uranyl ion concentration and the pH of the solution were examined for PAMAM dendrimers of generations 3, 4, and 5. Our simulation results show that PAMAM has a high adsorption capacity for the uranyl ions. The adsorption capacity increases with increasing concentration of uranyl ions for all 3 generations of PAMAM in agreement with experimental findings. We find that the number of uranyl ions bound to PAMAM is significantly higher in acidic solutions (pH < 3) as compared to neutral solutions (pH ∼ 7) for all uranyl ion concentrations. Additionally, we find an increase in the number of adsorbed uranyl ions to PAMAM with the increase in the dendrimer generation. This increase is due to the greater number of binding sites present for higher-generation PAMAM dendrimers. Our simulation study shows that nitrate ions form a solvation shell around uranyl ions, which allows them to bind to PAMAM binding sites, including the amide, amine, and carbonyl groups. In polymer-assisted ultrafiltration (PAUF) experiments, the removal percentage of uranyl ions by G3 PAMAM dendrimer increased from 36.3% to 42.6% as the metal ion concentration increased from 2.1 × 10-5 M to 10.5 × 10-5 M at a pH of 2. Our combined experiment and simulation study suggests that PAMAM is an effective adsorbent for removing uranyl ions from aqueous solutions.

Synthesis and characterization of a new hybrid polymer composite (pollene@polyacrylamide) and its applicability in uranyl ions adsorption

Synthesis and characterization of a new hybrid polymer composite (pollene@polyacrylamide) and its applicability in uranyl ions adsorption

Fabrication of phosphate-containing mesoporous carbon for fast and efficient uranium (VI) extraction

Uranium has been recognized as one of the most desired radionuclides that has long been used in reactor. The efficient extraction of uranyl (VI) ions from radioactive effluents and seawater is an ideal way to collect uranium, however it is always a challenge to develop high-efficiency adsorbents for effective uranium uptake. In this paper, a series of phosphate-containing mesoporous carbon (PC) are fabricated by the carbonization of sucrose and phytic acid upon using nanosized silica as hard template. The obtained PC have high-content phosphate group, large specific surface area and tunable mesoporous structure. The PC can efficiently adsorb uranium at a wide pH conditions. The maximum uptake capacity of PC for uranium reaches 928 mg g −1, ranking as one of the most highly effective adsorbents. The mesopores of PC enables them to quickly reach the adsorption equilibrium within 60 s and meantime PC show excellent adsorption selectivity. Investigations of adsorption mechanism reveals that uranyl (VI) ions tend to bind with the surface P-OH groups to form P-O-U complexes, leading to the effective uranium extraction. Moreover, PC displays good recyclability and can be further used for dynamic column adsorption of uranyl (VI) ion from uranium-containing solution. The excellent adsorption performances of PC highlight their great potential in uranium extraction.

Biosorption of uranyl ions from aqueous solutions by soluble renewable polysaccharides

Polysaccharides derived from natural sources have been offered as environment friendly sorbents for the adsorption of uranyl ions.