Separation Of Uranyl Ions Research Articles

MoS2 decorated heteroatoms doped carbon microspheres for efficient separation of uranium from wastewater

Uranium serves as a fundamental element for sustainable nuclear reactor energy. Hence, the extraction and enrichment of uranium from radioactive wastewater is of considerable significance for both nuclear power utilization and environmental protection. In this study, carbon microspheres (TAC) doped with nitrogen, phosphorus and sulfur were derived from ternary polyphosphazene. Subsequently, molybdenum disulfide (MoS2) was integrated using hydrothermal method to fabricate the TAC/MoS2 composite, which is designed for the efficient enrichment and separation of uranyl ions. Owing to the unique two-dimensional structure of MoS2 and its strong affinity towards uranyl ions, the adsorption capacity of the composite was significantly enhanced to 399.6 mg/g within 80 min at pH 5 and 298.15 K. Additionally, the composite exhibited commendable thermal stability and hydrophilicity, declaring that it is an outstanding candidate for the efficient enrichment and separation of uranyl ions. Further mechanism studies through XPS analysis and DFT calculations suggested that the vacancies introduced by MoS2 can generate electrostatic interactions and coordination effects with uranyl ions, thereby improving the adsorption performance of the composite. Due to its straightforward preparation process and exceptional adsorption performance, TAC/MoS2 possesses broad application prospects in the extraction of uranium from wastewater.

Synthesis of a New Amberlite 7HP Sorbent Impregnated by Nano Manganese Dioxide and Its Applications for Uranium Separation

ABSTRACT In this work, a commercially available Amberlite 7HP has been modified using nano-flakes MnO2 prepared by a simple reduction method. The characterization of the new sorbent impregnated by nano manganese dioxide was performed by scanning electron microscope, transmission electron microscope, energy-dispersive X-ray, X-ray diffraction, and Fourier transformation infrared spectrometric analyses. The performance of the new sorbent for ion separation in aqueous medium was studied in detail by varying the pH, contact time, initial concentration, bed height, and flow rate. The maximum sorption has been achieved at a solution of pH 3.1. Sorbed ions were desorbed with 10 mL of 1.5 M HCl solution. The kinetics and isothermal parameters of the sorption of ions onto the new sorbent have been studied. The kinetic experimental data properly correlate with the second-order kinetic model and the time required to reach sorption equilibrium is 240 min. The sorption data could be well interpreted by the Langmuir sorption isotherm and the monolayer sorption capacity was found to be 56.3 mg · g−1. The sorption data were fitted to two well-established fixed-bed sorption models, namely, Thomas and Yoon–Nelson models, with a correlation coefficient, R2, ≥0.993. The separation performance of the new sorbent was demonstrated by using different real samples. Consequently, the developed sorbent resin was successfully utilized for the separation of uranyl ions in safeguard applications.

Separation of Uranyl Ions on Starch-Based Functional Hydrogels: Mechanism and Kinetics

In this article, we report the mechanism and kinetics of adsorption of uranyl ions on starch-based functional hydrogels. The hydrogels were prepared from starch in native or hydrolyzed/oxidized form by crosslinking with N,N-methylenebisacrylamide. The hydrogels synthesized from the oxidized starch have carboxylic groups at C-6 position. The effect of the structure and external environmental factors, i.e., contact time, temperature, ion strength, and simulated seawater (0.55 M NaCl and 3 mM NaHCO3), was investigated on the uranyl adsorption behavior of hydrogels. The adsorption of uranyl ions was rapid as the highest adsorption was observed after 6 h and at 40°C. The sorbents also exhibited appreciable ion uptake even from the simulated seawater. The equilibrium data was analyzed using Langmuir and Freundlich adsorption isotherms and pseudo-first order and pseudo-second order kinetic models. Evidence of adsorption was obtained by characterization of the uranyl ions-loaded hydrogels by FTIR spectroscopy and also by elution with 0.1 N HCl.

Separation of uranium(VI) from tri- and tetravalent elements in phosphoric acid solutions

SummaryA new method of separation of uranyl ions from di-, tri- and tetravalent cations such as thorium, zirconium, cerium(IV) and/or lanthanides(III) involving phosphoric acid medium is described in this paper. The process is based on the difference of solubility between various phosphates: M2(PO4)2(HPO4)·H2O, M(HPO4)2·H2O, M(OH)PO4(where M is a tetravalent cation) or APO4·nH2O (where A is a trivalent cation) on the one hand, and the uranyl phosphate pentahydrate (UO2)3(PO4)2·5H2O, on the other hand. Taking into account the associated solubility constants, the conditions of separation were calculated then experimented for a mixture of Th4+, Ce4+(as a plutonium surrogate), Zr4+, La3+, Ba2+, Sr2+and UO22+. Tetravalent and trivalent cations phosphates were precipitated in 2 mol L−1nitric acid medium while uranyl ion and divalent cations remained in the solution. In a second step, (UO2)3(PO4)2·5H2O was precipitated at pH ≈ 1.5 and thereby separated from divalent cations present in the solution.

Chemical enrichment and separation of uranyl ions in aqueous media using novel polyurethane foam chemically grafted with different basic dyestuff sorbents

The new type of the grafted polyurethane foam sorbents were prepared by coupling polyether polyol, toluene diisocyanate and basic dyestuff (Methylene blue, Rhodamine B and Brilliant green). The Me.B-PUF, Rh.B-PUF and Br.G-PUF were characterized using UV/vis, IR and TGA. The adsorption properties and chromatographic behaviour of these new adsorbents for preconcentration and separation of uranium(VI) ions at low concentrations from aqueous thiocyanate media were investigated by a batch process. The maximum sorption of U(VI) was in the pH ranges 1–4. The kinetics of sorption of the U(VI) by the Grafted-PUF were found to be fast with half life of sorption ( t 1/2) in 2.43 min. The average sorption capacity of different sorbents 0.124 meq g −1 for uranyl ions, enrichment factors ≈40 and the recovery 98–100% were achieved (R.S.D. ≈ 0.73%). The basic dyestuff Grafted-PUF could be used many times without decreasing their capacities significantly. The value of the Gibbs free energy (Δ G) for the sorbents is −7.3 kJ mol −1, which reflects the spontaneous nature of sorption process. The sorption mechanism of the metal ion onto Grafted-PUF was also discussed.

Separation of uranyl ions with amidoximated poly(acrylonitrile/N-vinylimidazole) complexing sorbents

Abstract Acrylonitrile (AN)/N-vinylimidazole (VIm) copolymeric hydrogels were synthesized by irradiating their binary mixtures. The AN moieties of copolymers were amidoximated using hydroxylamine hydrochloride in basic medium. The amidoximated hydrogels were used for separating uranyl ions from aqueous solutions by a complexation process. Uranyl ion adsorption studies were conducted from different UO22+ ion solutions (650–1850 ppm). The result of all UO22+ ion adsorption studies complied with the L-type isotherm. The adsorption capacity was found as high as 0.64 g UO22+ g−1 dry amidoximated copolymer.

Separation of Uranium from Nitric- and Hydrochloric-Acid Solutions with Extractant-Coated Magnetic Microparticles

The magnetically assisted chemical separation (MACS) process utilizes selective magnetic microparticle composites to separate dissolved metals from solution. In this study, MACS particles were coated with neutral and acidic organophosphorus extractants,octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), and bis(2-ethyl-hexyl)phosphoric acid (D2EHPA or HDEHP) and were evaluated for the separation of uranyl ions from nitric- and hydrochloric-acid solutions. The results suggest that a synergistic interaction between the particle surface and solvent coating may explain why the particles display, in some cases, orders of magnitude of higher partitioning coefficients than are estimated from solvent-extraction measurements. Particles coated with TBP and those coated with a combination of TOPO and D2EHPA displayed the most desirable characteristics for removing uranium from dilute acid environments typical of contaminated groundwater. Uranium separation from moderate to highly acidic waste streams typical of Department of Energy (DOE) nuclear wastes is best accomplished using particles coated with a combination of CMPO and TBP. The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-ENG-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.