Uranium Adsorption Properties Research Articles

Polyethyleneimine assisted zeolitic imidazolate frameworks foam embed silver to enhance the uranium recovery from seawater

The powder structure, poor surface wettability and biofouling significantly limited the application potential of ZIFs (zeolitic imidazolate frameworks) in uranium extraction from seawater. Herein, a superhydrophilic polyethyleneimine assisted zeolitic imidazolate frameworks foam embed silver (CPEZ8A) was successfully prepared by simple chemical cross-linking and in-situ growth methods to explore the effects of hydrophilic matrix and silver antimicrobial agent on the uranium adsorption properties of ZIFs materials. The mechanical property and water contact angle test of CPEZ8A foam were performed to confirm its higher compression stress (with 1.314 MPa) and surface superhydrophilic. Moreover, CPEZ8A foam displayed an excellent resistance to biological attachment after 7 days in algae solution. Importantly, CPEZ8A showed the maximum U (VI) uptake capacity (775.19 mg/g) with 4.37 times of pure ZIF-8 at nearly seawater pH and retained relative high U-uptake amount during the broad pH range (4.0–9.0). Ion competition experiments were also investigated to verify the CPEZ8A foam excellent selectivity (Kd = 15,072.1 mL/g). Notably, the removal rate of CPEZ8A foam reach 81.31 % in natural seawater and remain nearly 80 % in simulated contaminated seawater. Therefore, this work provides an effective strategy to develop highly efficient ZIFs adsorbents for uranium capture.

Zwitterionic functionalized chitosan with dual-antifouling for selective uranium extraction

Uranium adsorbents deployed in natural water environments rich in microorganisms for a long time are inevitably affected. Biofouling severely reduces the uranium adsorption performance and damages the structure of the adsorbents. Therefore, antifouling performance is necessary for adsorbents that extract uranium from seawater and uranium-containing groundwater. Previously reported antifouling uranium adsorbents mainly have two types: single antibacterial or anti-adhesion, and few studies have developed dual-antifouling adsorbents that combine the two antifouling pathways. In this study, a dual-antifouling adsorbent CS-MPC with both anti-adhesion and antibacterial properties was constructed. The synergistic effect of the superhydrophilic 2-methylacryloxyethyl phosphocholine (MPC) and the natural bactericidal chitosan (CS) enabled the inhibition rate of dual-antifouling CS-MPC against various bacteria to exceed 99 %. Furthermore, the uranium adsorption capacity of CS-MPC was 579 mg/g in simulated uranium-containing groundwater and 8.28 mg/g after immersion for 42 days in real seawater. The SA/CS-MPC composite beads prepared to solve powder defects also exhibited good dual-antifouling activity and uranium adsorption properties, making them potential candidates for uranium extraction. The construction of dual-antifouling adsorbents provides a new strategy for effective biofouling control.

Construction mechanism of gellan gum/chitosan/calcium ion multiple‐network hydrogel by self‐assembly strategy and its regulation

AbstractRecently, double‐network or multiple‐network hydrogel constructed by physical methods has been considered a green method to improve the comprehensive properties of biomass hydrogel. Herein, a novel physically cross‐linked hydrogel with multiple network of gellan gum/chitosan/calcium ion (GG–CS–Ca) was constructed by self‐assembly to accomplish the synergistic improvement of mechanical strength and uranium adsorption property compared to adsorbents GG–Ca and carboxymethyl konjac glucomannan/GG–Al originated from gellan gum previously prepared. Moreover, the driving mechanism of self‐assembly of GG–CS–Ca was deduced by 13C solid state nuclear magnetic resonance spectroscopy (13C‐SSNMR), rheological analysis, and phase transition analysis. The results indicated electrostatic interaction was dominant during the self‐assembly of GG–CS–Ca. The self‐assembly mechanism was also illustrated by investigating the x‐ray photoelectron spectrometer (XPS) combined with the analysis of the phase transition process. Comprehensively, the self‐assembly constructed GG–CS–Ca hydrogel network contained three kinds of network including the GG–CS network constructed by electrostatic action of protonated CS with negative charged GG, the GG–Ca network constructed by ionic cross‐linking of COO− in GG and Ca2+, and the GG network formed after the phase transformation of GG hot sol by cooling. It explored a new method for constructing biomass‐based physical hydrogels with both favorable mechanical strength and uranium adsorption capacity in uranium removal.Highlights A novel physically cross‐linked hydrogel (GG–CS–Ca) with multiple network was constructed by self‐assembly. The GG–CS–Ca hydrogel accomplished the synergistic improvement of mechanical strength and uranium adsorption properties. The self‐assembly mechanism of constructing the GG–CS–Ca hydrogel network contained three aspects. The electrostatic interaction was the dominant action during the self‐assembly of GG–CS–Ca.

Uranium Adsorption Properties and Mechanisms of the WRK Bentonite at Different pH Condition as a Buffer Material in the Deep Geological Repository for the Spent Nuclear Fuel

Uranium Adsorption Properties and Mechanisms of the WRK Bentonite at Different pH Condition as a Buffer Material in the Deep Geological Repository for the Spent Nuclear Fuel

Microwave hydrothermal synthesis, characterization and excellent uranium adsorption properties of CoFe2O4@rGO nanocomposite

Microwave hydrothermal synthesis, characterization and excellent uranium adsorption properties of CoFe2O4@rGO nanocomposite

Efficient removal of uranium (VI) by nano-manganese oxide materials: A synthetic experimental and mechanism studies

• Three manganese oxide materials with recyclability was prepared. • The MnO-600 presented wonderful adsorption property for U(VI). • The adsorption capacity of U(VI) on the MnO-600 was 635.4 mg/g. • The removal efficiency remained above 90% after five cycles. Three kinds of nano-manganese oxide materials were prepared at different temperature (500, 600 and 700 °C) using chitosan as the template agent. The results showed that there was no sintering and agglomeration in the calcination of nano-manganese oxide at 600 °C, while the manganese oxide material calcined at 700 °C showed pore collapse and agglomeration and the template agent was incompletely removed in the manganese oxide material calcined at 500 °C. The adsorption properties of uranium (VI) on the three manganese oxide materials were investigated. The experimental results showed that the adsorption behavior conformed to the pseudo-second-order kinetics and Langmuir isotherm models, revealing that the adsorption behavior of uranium (VI) on manganese oxide materials was a uniform and monolayer chemical adsorption process. The adsorption capacity of MnO-600 was 635.4 mg/g and the adsorption efficiency was above 90% after five cycles. In conclusion, the novel manganese oxide materials would have a prospect for application in wastewater treatment.

A convenient one-step synthesis of mesoporous ZrO2/SBA-15 and its uranium adsorption properties

Mesoporous ZrO2/SBA-15 materials were prepared for the first time by a one-step method using ZrO2 as zirconium source and their uranium (U(VI)) adsorption behavior were studied. The influence of ZrO2 content on the structure, morphology and hydrothermal stability of the obtained ZrO2/SBA-15 was investigated. It was found that the structural order of ZrO2/SBA-15 decreased with increasing ZrO2 content. The hydrothermal stability of SBA-15 was improved by loading of ZrO2. Furthermore, the effects of pH, initial U(VI) concentration, contact time, temperature and ZrO2 content on the U(VI) adsorption capacity were studied. The results demonstrated that the U(VI) adsorption capacity decreased with increasing ZrO2 content and temperature. The adsorption process was found to be well fitted to the Langmuir and pseudo-second-order model. The calculated maximum adsorption capacities were 326 and 294 mg·g−1 for 0.4ZrO2/SBA-15 and 0.8ZrO2/SBA-15 samples at 283 K, respectively. Furthermore, the analysis of thermodynamic parameters (ΔG, ΔH, and ΔS) revealed that the process of U(VI) adsorption onto ZrO2/SBA-15 was feasible, spontaneous and exothermic.

Construction of gel-like swollen-layer on Polyacrylonitrile Surface and Its Swelling Behavior and Uranium Adsorption Properties

In this study, a hyperbranched chelated hydrophilic swollen-layer was constructed on the surface of polyacrylonitrile (PAN) fiber with amino trimethylene phosphoric acid (ATMP) as a terminal group, which applied as an adsorbent for seawater uranium U(VI) extraction. This shows that U(VI) enter the gel-like swollen-layer to form a more complex body structure. The molecular chain conformational extension in the swollen-layer reduces the resistance of the uranyl ion to enter the swollen-layer, which is conducive to the adsorption behavior. The adsorption performance on the U(VI) by the adsorption experiment were found to be consistent with the Langmuir isotherm adsorption model and the pseudo-second-order kinetics, indicating that the adsorption of U(VI) by this material is uniform single-layer chemical adsorption. Ion competition experiments and cyclic adsorption experiments verify the practical application potential of the materials. In the dynamic simulation of seawater adsorption experiments, the adsorption capacity of the adsorbent reached 7.4 mg/g. Studies on the adsorption mechanism have found that a large number of hydroxyl groups in the swollen-layer and ATMP as an end machine have a chelation effect on U(VI).

Microplasma electrochemistry (MIPEC) strategy for accelerating the synthesis of metal organic frameworks at room temperature

Metal organic frameworks (MOFs) are a kind of promising materials in many applications, while the fast and controllable synthesis of MOFs is still challenging. Here, taking HKUST-1 as illustration, a micro-plasma electrochemistry (MIPEC) strategy was developed to accelerate the synthesis process of MOFs with micro-plasma acting as cathode. Treating the HKUST-1 precursor solution with micro-plasma cathode could not only transfer the electrons into the solution leading to the deprotonation effect, but also generate radical species to trigger and accelerate the nucleation and growth of MOFs at the plasma-liquid interface. Thus, uniform and nanosize MOFs could be prepared within minutes. The obtained MOFs show similar excellent uranium adsorption properties compared with those obtained by other method, with a highly adsorption capability of uranium with 550 mg/g in minutes. The novel MIPEC strategy developed in this work provides an alternative for controllable synthesis of MOFs, and especially has potential application in accelerating traditional organic synthesis.

Uranium adsorption on two-dimensional irradiation resistant MXenes from first-principles calculations

DFT calculation has been employed to study the adsorption properties of uranium on 2D MXene materials, including Ti2C, V2C and Cr2C, along with the influence of surface functional groups. These MXenes exhibit excellent uranium adsorption capabilities, especially the theoretical capacity of U on Ti2CO2 can approach to 1890 mg/g. Their binding energies and adsorption capacities are sensitive to the type of surface decorations, indicating that this behavior might be controllable. Our calculations also imply that these MXenes have excellent irradiation tolerance, which makes them more promising to be used as potential candidates in the technique of nuclear fuel enrichment and reprocessing.

Carboxymethyl konjac glucomannan mechanically reinforcing gellan gum microspheres for uranium removal

Biosorbents have been a promising adsorbent to remove uranium while their poor mechanical properties prevent them from being widely used in practice. In this study, carboxymethyl konjac glucomannan (CMKGM) was incorporated to gellan gum to form a double-network gel micro spheres (CMKGM/GG-Al) for uranium removal with its mechanical strength fairly being reinforced. The compressive strength of the CMKGM/GG-Al microspheres was about 6 times than that of GG-Ca microspheres we prepared before while the adsorption capacity still be at a better value with the fitting maximum adsorption capacity being of 97.94 mg/g. Its uranium adsorption properties were investigated by considering the influence of pH, the adsorbent dosage, temperature, initial uranium concentration, time and coexisting ions. The adsorption mechanism was also investigated according to the SEM, EDX, FT-IR and XPS data analysis. The isotherm equilibrium data which were best fitted with Langmuir model and the kinetics data which were best fitted with pseudo-second-order model. It was inferred that the adsorption process was mainly the ion-exchange and the coordination with hydroxyl groups on the adsorbent surface and the adsorption process was endothermic and spontaneous. The CMKGM/GG-Al microspheres prepared in this study would be more conducive to practical application for uranium removal.

Preparation of Hawaii nut shell biochar/graphene sponge and study on uranium adsorption properties

The composite sponge of Hawaii nut shell biochar and graphene oxide was prepared by using polyvinyl alcohol as three-dimensional composite carrier (BC/GO/PVA). The characterization analysis found that the composite sponge material has a good specific surface area of pore structure, and improved the plasticity of biochar, overcoming the stacking problem of graphene sheets, and proposed a reasonable material cross-linking composite mechanism. The optimum adsorption capacity and adsorption mechanism were analyzed by batch adsorption experiments. The results showed that the removal of uranium by BC/GO/PVA materials was beneficial under weakly acidic conditions. The maximum adsorption capacity of the experiment is 14.3 mg/g.

Preparation of amino-modified hydroxyapatite and its uranium adsorption properties

The amino-hydroxyapatite (HAP-NH2) was synthesized by grafted amino functional groups onto hydroxyapatite. The uranium adsorption performance of HAP-NH2 was studied under different conditions. The results indicated that HAP-NH2 possessed high adsorption capacity (96 mg g−1), wide pH values range (2–8) and fast adsorption rate (20 min). The adsorption kinetic and adsorption isotherm models of HAP-NH2 revealed that the uranium adsorption process was belonged to chemical adsorption. Furthermore, the main forces between uranium ions and HAP-NH2 were attributed to hydroxyl, amino and phosphorous functional groups.

Synthesis of novel functional hydrothermal carbon spheres for removal of uranium from aqueous solution

A novel chelate sorbent (bis-3,4-dihydroxybenzy)p-phenylen diamine-grafted hydrothermal carbon spheres (HCS-BDBPD) had been successfully synthesized through chemical grafting method. FT-IR and SEM were used to analyze the chemical and microscopy structure of HCS-BDBPD. The batch experiments were carried out to study uranium adsorption properties of HCSs-BDBPD aimed at confirming the optimum condition for removal uranium from waste. The result showed that the sorption process was spontaneous and endothermic in nature and the maximum uranium sorption capacity of 272 mg/g was obtained under the conditions tested, the selectivity of HCSs toward uranium was improved after grafting BDBPD groups on the surface of HCSs.

Synthesis of phosphorus-modified poly(styrene-co-divinylbenzene) chelating resin and its adsorption properties of uranium(VI)

A new phosphorus-modified poly(styrene-co-divinylbenzene) chelating resin (PS–N–P) was synthesized by P,P-dichlorophenylphosphine oxide modified commercially available ammoniated polystyrene beads, and characterized by Fourier transform infrared spectroscopy and elemental analysis. The adsorption properties of PS–N–P toward U(VI) from aqueous solution were evaluated using batch adsorption method. The effects of the contact time, temperature, pH and initial uranium concentration on uranium(VI) uptake were investigated. The results show that the maximum adsorption capacity (97.60 mg/g) and the maximum adsorption rate (99.72 %) were observed at the pH 5.0 and 318 K with initial U(VI) concentration 100 mg/L and adsorbent dose 1 g/L. Adsorption equilibrium was achieved in approximately 4 h. Adsorption kinetics studied by pseudo second-order model stated that the adsorption was the rate-limiting step (chemisorption). U(VI) adsorption was found to barely decrease with the increase in ionic strength. Equilibrium data were best modeled by the Langmuir isotherm. The thermodynamic parameters such as ∆G 0, ∆H 0 and ∆S 0 were derived to predict the nature of adsorption. Adsorbed U(VI) ions on PS–N–P resin were desorbed effectively (about 99.39 %) by 5 % NaOH–10 % NaCl. The synthesized resin was suitable for repeated use.

Improvement in Uranium Adsorption Properties of Amidoxime-Based Adsorbent Through Cografting of Amine Group

Amidoxime (AO)/amine co-functionalized polypropylene fiber adsorbents were prepared. The all-polymeric structures were characterized by using Fourier transform infrared spectroscopy (FTIR), optical microscope, contact angle meter and electron spin resonance (ESR) analysis methods, confirming the grafting, modification, and amidoximation stages gravimetrically, spectroscopically, and visually. The properties for the removal of uranyl(VI) from aqueous solutions were investigated. For amidoxime (AO) fiber, high adsorption rate was observed within the first 30 minutes and the plateau value of 40.6% uranium loading (0.0812 mg/g) was reached at around 30 minutes. The adsorption equilibrium for AO/amine fiber was attained within 20 minutes, resulting in the adsorption of 92.6% uranium loading (0.185 mg/g). The percentage of adsorption increases with increasing pH value (2–6), reaches a maximum at pH 6.0 and then remains almost constant for AO/amine fiber, whereas reduces slightly for AO fiber.

Quantifying Differences in the Impact of Variable Chemistry on Equilibrium Uranium(VI) Adsorption Properties of Aquifer Sediments

Uranium adsorption–desorption on sediment samples collected from the Hanford 300-Area, Richland, WA varied extensively over a range of field-relevant chemical conditions, complicating assessment of possible differences in equilibrium adsorption properties. Adsorption equilibrium was achieved in 500–1000 h although dissolved uranium concentrations increased over thousands of hours owing to changes in aqueous chemical composition driven by sediment-water reactions. A nonelectrostatic surface complexation reaction, >SOH + UO22+ + 2CO32- = >SOUO2(CO3HCO3)2–, provided the best fit to experimental data for each sediment sample resulting in a range of conditional equilibrium constants (logKc) from 21.49 to 21.76. Potential differences in uranium adsorption properties could be assessed in plots based on the generalized mass-action expressions yielding linear trends displaced vertically by differences in logKc values. Using this approach, logKc values for seven sediment samples were not significantly different. However, a significant difference in adsorption properties between one sediment sample and the fines (<0.063 mm) of another could be demonstrated despite the fines requiring a different reaction stoichiometry. Estimates of logKc uncertainty were improved by capturing all data points within experimental errors. The mass-action expression plots demonstrate that applying models outside the range of conditions used in model calibration greatly increases potential errors.

Adsorption Properties of Uranium (VI) Ions on Reactive Crosslinked Acrylamidoxime and Acrylic Acid Copolymer Resins

Crosslinked acrylic acid (AA) acrylonitrile (AN) copolymer was prepared by suspension copolymerization in the presence of poly (vinyl alcohol) as suspending agent and N,N-methylenebisacrylamide (MBA) and divinylbenzene (DVB) as crosslinking agents. The molecular ratios between AN and AA was 95: 5 mol%. Different ratios 2, 5, and 10 wt% of crosslinkers was used. The nitrile group of the copolymer was converted to acrylamidoxime in the presence of hydroxylamine. Morphologies of the prepared resins were examined by scanning electron microscope (SEM). Recovery of uranium ions was investigated. The adsorption of uranium was occurred in nitric acid, hydrochloric acid and sulfuric acid solutions. Effect of pH, time of loading, type of acid, ratio, and type of crosslinker were investigated. Regeneration of eluted resins was determined.

Uranium adsorption properties of Allophane

Uranium adsorption properties of Allophane

Adsorption Properties of Uranium on a Banded Fiber Adsorbent Containing Amidoxime Groups in a Stream of Sea Water

Adsorption Properties of Uranium on a Banded Fiber Adsorbent Containing Amidoxime Groups in a Stream of Sea Water