Adsorption Of Uranyl Ions Research Articles

Application of magnetic polyaniline nanocomposite for separation of uranyl ions from aqueous solutions

ABSTRACTPolyaniline (PANI) was synthesized chemically, and then modified with magnetic iron oxide nanoparticles (Fe3O4 NPs). PANI and PANI-Fe3O4 NPs were used for removal of uranyl ions (UO22+) from aqueous solutions using a batch system. The synthesized adsorbents were characterized using FT-IR, SEM, BET and XRD techniques. From isotherm investigation, the maximum adsorption capacities (qm) were 150.0 and 108.0 mg g−1 for PANI and PANI-Fe3O4NPs, respectively. The kinetics and equilibrium adsorptions were well-described by the pseudo-second-order kinetic and Langmuir model, respectively. Thermodynamic studies depicted that the adsorption of uranyl ions by PANI is a spontaneous exothermic process and in the case of PANI-Fe3O4 NPs, adsorption process is endothermic; therefore, the spontaneity is controlled by entropy.

Adsorption-assistant detection of trace uranyl ion with high sensitivity and selectivity in the presence of SBA-15

A new strategy adsorption-assistant detection of trace uranyl ion is developed in this work employing fluorescence techniqe. Specifically, mesoporous molecular sieve SBA-15 is introduced in the process of determination of uranyl by esculin to enhance the sensitivity and selectivity. A linear detecting range of 0.001–0.05 μM and a limit of detection of 6 nM are achieved, which is probably due to the adsorption of both esculin and uranyl ion onto SBA-15. The KSV value is 8.69 × 106 mol−1 L, which was ca. 40 times of that without SBA-15.

Uranyl ion adsorption studies on synthesized phosphoryl functionalised MWCNTs: a mechanistic approach

A novel and efficient sorbent: phosphoryl multiwalled carbon nanotubes (PS-MWCNTs) were synthesized by modifying MWCNTs with phosphoryl functional groups. PS-MWCNTs possessed excellent uranium adsorption capacity (194.17 mg g−1) with a wide range of pH values (> 2) and short adsorption equilibrium time (10 min). The isotherm models revealed that the U(VI) adsorption mechanism of PS-MWCNTs mainly belonged to chemical adsorption. Furthermore, the XPS analysis showed that the main forces between uranium ions and PS-MWCNTs were attributed to the phosphoryl functional groups.

Uranium Recovery from Aqueous Solutions Using Amidoxime Modified Cellulose Derivatives. II. Uranium Uptake Behavior of Amidoximated Ethyl Cellulose

Amidoxime modified ethyl cellulose (EC-g-AO) was used for the recovery of uranyl ions from aqueous solutions by a complexation process. Adsorption trials were carried out in different concentrations of UO22+ solutions (100 – 1000 mg/L) and at temperatures ranging from 25 to 50°C. The kinetics and the thermodynamics of the adsorption of uranyl ions (UO22+) by EC-g-AO were investigated. The adsorption capacity was found as 240 mg UO22+/g dry copolymer. The thermodynamic parameters for the interaction of UO22+ with EC-g-AO were calculated from thermodynamic relations. Calculations showed that adsorption occurred through strong electrostatic interactions with an enthalpy of -23.6 kJ/mol. The desorption of UO22+ was investigated by desorption agents like EDTA, HCl, NaHCO3, and NaOH. 52 % of desorption yield was found for NaHCO3.

Synthesis of Anionic Hydrogels for Uranyl Ion Adsorption

In this study, the anionic hydrogels were prepared in existence of crosslinker (N, N’-methylenebisacrylamide) by free radical addition reaction in aqueous solutions of neutral acrylamide and 2-hydoxyethyl methacrylate monomers and anionic comonomers such as mesaconic acid with 2 carboxyl groups or aconitic acid with 3 carboxyl groups. Hydrogels were characterized by FT-IR and DSC analysis. The effects of temperature, pH, adsorbent mass and concentration on uranyl ion adsorption onto the anionic hydrogels were investigated. It was determined that adsorption of UO 2 2+ ions to prepared hydrogels did not change with temperature and increased with increasing pH. The adsorption of u ranyl ion from aqueous solutions onto the anionic hydrogels was evaluated by applying Giles, Langmuir and Temkin isotherms to experimental results. According to the Giles adsorption isotherms classification of hydrogels UO 2 2+ ions adsorption prepared from adsorption isotherms formed, L type was determined and Langmuir parameters were calculated. It was determined that adsorption of UO 2 2+ ions to hydrogels prepared from R L values calculated for 1000 mg L -1 UO 2 2+ ion concentration is favorable.

Development of cysteine amide reduced graphene oxide (CARGO) nano-adsorbents for enhanced uranyl ions removal from aqueous medium

The affinity of uranyl ions for binding with nitrogen bearing ligands has led to development of several amine/amide reduced graphene oxides as adsorbent for uranyl ion removal. We have developed a novel nano-adsorbent (referred as CARGO) with an aim of increasing nitrogen groups in reduced graphene oxide (GO) for enhanced uranyl ion removal. There are two important stages in this work: (a) synthesis of CARGO, which comprises of GO reduction by the as synthesized l-cysteine amide and (b) optimization of uranyl ion adsorption by CARGO. The synthesis of l-cysteine amide (precursor) is confirmed by FT-IR and 1H NMR. Reduction of GO by l-cysteine amide is revealed from decrease in the acidic functionalities of GO and characterized by XRD, UV-vis, Raman and FT-IR spectroscopy techniques. The FE-SEM and TEM studies CARGO revealed flake like morphology. The uranyl ion adsorption on CARGO surface was confirmed from EDX analysis and supported by two dimensional elemental maps of uranium and carbon. The regeneration, re-usability and selectivity of uranium adsorption by CARGO have been studied. The uranyl adsorption was kinetically and thermodynamically favorable, which accounted for 88.9% uranyl ion removal in 60min at an optimized pH 5 via chemisorption mechanism and the corresponding qmax derived from Langmuir adsorption isotherm was 337.93mg/g. Such high uranyl ion adsorption capacity is attributed to more amine and/or amide binding sites on CARGO, high BET surface area (57.086m2/g) and negative zeta potential values of the adsorbent.

Synthesis and characterization of a composite polymeric material including chelating agent for adsorption of uranyl ions

In this study, a versatile polymeric material was synthesized by grafting Calcon Carboxylic Acid (CCA), which is known as a chelating agent for some metal ions, to polyacrylamide (PAA) structure. Thus, the adsorptive properties of inert PAA polymer were significantly improved owing to this procedure. The obtained new material, CCA-g-PAA, was characterized by point zero charge (PZC), FTIR, SEM, and UV–VIS–NIR analysis. The adsorption properties of new material were investigated comprehensively and experimental variables were optimized such as pH, temperature, time, and concentration. Experimental data were evaluated by using theoretical adsorption models. The maximum adsorption capacity of material was calculated as 0.079molkg−1 by considering Langmuir equation. The constants calculated from Freundlich and DR model were found as 6.98 and 0.441, respectively. Adsorption kinetic was also explained with pseudo second order and intra particular diffusion models. Experimental studies were showed that adsorption was endothermic and occurred spontaneously. The developed material has important advantages such as reusability, cost-effective synthesis procedure, high adsorption capacity, and selectivity.

Efficient removal of uranium(VI) from aqueous medium using ceria nanocrystals: an adsorption behavioural study

Ceria nanocrystals were synthesized by template free and cost effective method for highly efficient adsorption of U(VI) from aqueous solutions. In this study we investigated the factors influencing the adsorption behavior of U(VI) onto the ceria nanocrystals like pH, dosage, time of contact and initial metal ion concentration. The mechanism of adsorption was elucidated based on the isothermal and kinetic studies. A monolayer surface adsorption of uranyl ions onto the ceria nanocrystals with an adsorption capacity of 270 mg/g involving adsorptive pore filling and electrostatic interactions was indicated. The ceria nanocrystals could be regenerated and reused without significant reduction of adsorption capacities.

Adsorptive removal of uranyl ions in aqueous solution using hydrothermal carbon spheres functionalized with 4-aminoacetophenone oxime group

Hydrothermal carbon spheres (HCSs) functionalized with 4-aminoacetophenone oxime group (HCSs-oxime) were prepared by a grafting method and explored to adsorption of uranyl ions from aqueous solution. The results of FT-IR, elemental analysis and zeta potential indicate a successfully modification with oxime group. The adsorbent shows an excellent adsorption capacity (Langmuir, q m = 588.2 mg g−1) and quick adsorption kinetic (equilibrium time of approximately 60 min) at optimal pH of 6.0. The adsorptive selectivity for uranyl ions has been also great improved in present with various co-existing ions. Overall, HCSs-oxime is a potentially promising material for selective removal of uranium in the contaminated solution.

Impact of Pore Size on the Sorption of Uranyl under Seawater Conditions

The extraction of uranium from seawater has received significant interest recently, because of the possibility of a near-limitless supply of uranium to fuel the nuclear power industry. While sorbent development has focused primarily on polymeric sorbents, nanomaterials represent a new area that has the potential to surpass the current polymeric sorbents, because of the high surface areas that are possible. Mesoporous carbon materials are a stable, high-surface-area material capable of extracting various chemical species from a variety of environments. Herein, we report the use of a dual templating process to understand the effect of pore size on the adsorption of uranyl ions from a uranyl brine consisting of seawater-relevant sodium, chloride, and bicarbonate ions. It was found that pore size played a more significant role in the effective use of the grafted polymer, leading to higher uranium capacities than the surface area. Therefore, the pore size must be tailored to meet the demands of the extraction ...

Removal of uranium(VI) ions from aqueous solutions using Schiff base functionalized SBA-15 mesoporous silica materials

Functionalized SBA-15 mesoporous silica particles, bearing N-propylsalicylaldimine and ethylenediaminepropylesalicylaldimine Schiff base ligands, abbreviated as SBA/SA and SBA/EnSA respectively, were prepared and characterized by FT-IR, elemental analysis, TGA, XRD, TEM and SEM techniques. The potentials of these adsorbents were examined by using them in solid phase extraction of U(VI) ions from water samples. It is shown that 20 mg of SBA/SA or SBA/EnSA can remove rapidly (∼15 min) and quantitatively uranium(VI) ions from 10 to 200 mL of water solutions (pH 4) containing 0.2 mg of the ions, at 25 °C. The adsorbed ions were stripped by 1 mL of dilute nitric acid solution (0.1 mol L−1). It means that the studied adsorbents are able to be used for removal and concentration of uranyl ions. This allowed achieving to a concentration factor of 200 for uranyl ions. The variation in the ionic strength in the range 0–1 mol L−1 did not affect the extraction efficiencies of the adsorbents. The adsorbents showed selective separation of uranyl ions from Cd2+, Co2+, Ni2+, Mn2+, Cr3+, Ba2+, Fe3+ and Eu3+ ions. Thermodynamic investigations revealed that the adsorption of uranyl ions by the adsorbents was spontaneous and endothermic. The Langmuir model described suitably the adsorption isotherms. This model determined the maximum adsorption capacity of the adsorbents SBA/SA and SBA/EnSA as 54 and 105.3 mg uranyl/g adsorbent, respectively. The kinetics of the processes was interpreted by using Pseudo-second-order model.

Adsorption of Uranyl ions on Amine-functionalization of MIL-101(Cr) Nanoparticles by a Facile Coordination-based Post-synthetic strategy and X-ray Absorption Spectroscopy Studies.

By a facile coordination-based post-synthetic strategy, the high surface area MIL-101(Cr) nanoparticles was functionallized by grafting amine group of ethylenediamine (ED) on coordinatively unsaturated Cr(III) centers, yielding a series of ED-MIL-101(Cr)-based adsorbents and their application for adsorption of U(VI) from aqueous solution were also studied. The obtained ED-functionallized samples with different ED contents were characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), FTIR, elemental analysis (EA) and N2 adsorption and desorption isothermal. Compared with the pristine MIL-101(Cr) sorbents, the ED-functionallized MIL-101(Cr) exhibits significantly higher adsorption capacity for U(VI) ions from water with maximum adsorption capacities as high as 200 mg/g (corresponding to 100% extraction rate) at pH of 4.5 with ED/Cr ratio of 0.68 and the sorbed U(VI) ions can easily be desorbed at lower pH (pH ≤ 2.0). The adsorption mode of U(VI) ions and effects of grafted ED on the MIL-101(Cr) frameworks were also been studied by X-ray absorption spectroscopy (XAS). We believe that this work establishes a simple and energy efficient route to a novel type of functional materials for U(VI) ions extraction from solution via the post-synthetic modification (PSM) strategy.

Uranyl Ion Uptake Properties of Highly Swollen AAm/SA/GEL/PVA Semi IPNs as Novel Biosorbent

ABSTRACTIn this study, uranyl ion adsorption from aqueous solutions has been investigated by highly swollen gelatin and poly(vinyl alcohol) based semi-interpenetrating polymer network systems of acrylamide/sodium acrylate. For this, chemically cross-linked copolymer of acrylamide/sodium acrylate hydrogels with gelatin and/or poly(vinyl alcohol) were prepared by free radical polymerization in an aqueous solution of acrylamide and sodium acrylate using ammonium persulfate/N,N,N′,N′-tetramethylethylenediamine as redox initiating pair in the presence of poly(ethylene glycol)diacrylate as a cross linker. Adsorption studies were investigated by spectrophotometric method at 25°C. Sorption capacity, removal efficiency, and partition coefficient of the hydrogels were investigated. Removal efficiency was changed within a range of 7.06–33.03%.

A facile method of synthesizing ammonia modified graphene oxide for efficient removal of uranyl ions from aqueous medium

Adsorption of uranyl ions on NH3 modified graphene oxide at pH 6.

In situ preparation of magnetic chitosan resins functionalized with triethylene-tetramine for the adsorption of uranyl(II) ions

The magnetic chitosan resins functionalized with triethylene-tetramine (TETA-MCR) were in situ prepared for the adsorption of uranyl(II) ions from aqueous solution. FTIR analysis indicated that the amine groups of TETA-MCR were the main adsorption sites for complex formation. The adsorption process was spontaneous and endothermic in nature and kinetically followed pseudo-second-order model. The equilibrium data were correlated with Langmuir, Freundlich and Temkin models, and the maximum monolayer adsorption capacity obtained from the Langmuir model was 166.6 mg/g at 293 K. The TETA-MCR exhibited some excellent characteristics such as high adsorption capacity, fast adsorption kinetic, easy of magnetic separation and good reusability, and thus could be potentially used as a novel magnetic sorbent for actinide separation.

Enhanced adsorption and recovery of uranyl ions by NikR mutant-displaying yeast.

Uranium is one of the most important metal resources, and the technology for the recovery of uranyl ions (UO22+) from aqueous solutions is required to ensure a semi-permanent supply of uranium. The NikR protein is a Ni2+-dependent transcriptional repressor of the nickel-ion uptake system in Escherichia coli, but its mutant protein (NikRm) is able to selectively bind uranyl ions in the interface of the two monomers. In this study, NikRm protein with ability to adsorb uranyl ions was displayed on the cell surface of Saccharomyces cerevisiae. To perform the binding of metal ions in the interface of the two monomers, two metal-binding domains (MBDs) of NikRm were tandemly fused via linker peptides and displayed on the yeast cell surface by fusion with the cell wall-anchoring domain of yeast α-agglutinin. The NikRm-MBD-displaying yeast cells with particular linker lengths showed the enhanced adsorption of uranyl ions in comparison to the control strain. By treating cells with citrate buffer (pH 4.3), the uranyl ions adsorbed on the cell surface were recovered. Our results indicate that the adsorption system by yeast cells displaying tandemly fused MBDs of NikRm is effective for simple and concentrated recovery of uranyl ions, as well as adsorption of uranyl ions.

Uranyl ions adsorption by novel metal hydroxides loaded Amberlite IR120

In this work, Ni(OH)2-loaded Amberlite IR120 (Ni–MA) and Co(OH)2-loaded Amberlite IR120 (Co–MA) resins were prepared, characterized and applied for UO22+ removal from aqueous solutions. The adsorption characteristics were investigated in a batch system with respect to effect of contact time, pH, equilibrium isotherms and removal kinetics data. The results indicated that the UO22+ could be efficiently removed from aqueous solutions at pH = 3.5 using Ni–MA and Co–MA resins. The maximum adsorption capacities for the UO22+ of Ni–MA and Co–MA were found to be 439 mg/g and 451 mg/g respectively. The equilibrium data fit well with the Langmuir adsorption isotherm. Kinetics study showed that the adsorption process was fast and reached equilibrium within 60 min and the kinetics data fit well with pseudo-second order and intra-particle diffusion models for both resins. The adsorption mechanism has been proposed and discussed. It was found that both Ni–MA and Co–MA resins could be used effectively for UO22+ removal from aqueous solutions.

Molecular dynamics simulations of uranyl adsorption and structure on the basal surface of muscovite

Anthropogenic activities have led to an increased concentration of uranium on the Earth's surface and potentially in the subsurface with the development of nuclear waste repositories. Uranium is soluble in groundwater, and its mobility is strongly affected by the presence of clay minerals in soils and in subsurface sediments. We use molecular dynamics simulations to probe the adsorption of aqueous uranyl () ions onto the basal surface of muscovite, a suitable proxy for typically ultrafine-grained clay phases. Model systems include the competitive adsorption between potassium counterions and aqueous ions (0.1 M and 1.0 M UO2Cl2, 0.1 M NaCl). We find that for systems with the presence of potassium and uranyl ions, potassium ions dominate the adsorption phenomenon. Potassium ions adsorb entirely as inner sphere complexes associated with the ditrigonal cavity of the basal surface. Uranyl ions adsorb in two configurations when it is the only ion species present, and in a single configuration in the presence of potassium. The majority of adsorbed uranyl ions are tilted < 45° relative to the muscovite surface, and are associated with the Si4Al2 rings near the aluminium substitution sites.

Adsorption of the Uranyl Ion on the Hydroxylated &lt;em&gt;&amp;alpha;&lt;/em&gt;-Quartz (101) Surface

采用周期性密度泛函理论研究羟基化 α -石英（101）面的铀酰离子吸附行为. 通过对铀酰离子的水合作用考虑水溶剂对结构的短程溶剂化效应，并通过类导体屏蔽模型（COSMO）考虑水溶剂对结构的远程溶剂化效应. 吸附能计算结果和电子结构数据均表明水合铀酰离子吸附构型比氢氧化铀酰吸附构型稳定，并且在液相中两种类型的稳定吸附位均为dia-O s1 O s2 位. 两种形式在电子结构上有很大的差异，主要是由于铀与表面作用后成键强弱程度不同，使5 f 轨道宽化和略微红移存在差异. 在铀酰离子吸附的基础上利用卤素离子改变铀酰离子配位环境可调整体系的带隙.

Removal of uranyl ions from aqueous solutions using barium titanate

Remediation of water sources contaminated with radioactive waste products is a major environmental issue that demands new and more efficient technologies. For this purpose, we report a highly efficient ion-exchange material for the removal of radioactive nuclides from aqueous solutions. The kinetic characteristics of adsorption of uranyl ions on the surface of barium titanate were investigated using a spectrophotometric method under a wide range of conditions. By controlling the pH it was possible to exert fine control over the speciation of uranium, and by optimizing the temperature and grain size of the exchanger, almost total removal was achieved in a matter of just hours. The highest efficiency (>90 % removal) was realized at high temperature (80 °C). Moreover, the effect of competitive ion adsorption from a range of different cations and anions was quantified. Adsorption was found to follow first-order kinetics and both Freundlich and Langmuir isotherms could be applied to this system. The results of a mathematical treatment of the kinetic data combined with the observation that adsorption was independent of stirring speed and dependent on the ion-exchanger grain size, indicate that the dominant mechanism influencing adsorption is particle spreading. The adsorption behavior was not influenced by exposure to high-intensity gamma radiation, indicating potential for use of this ion-exchanger in systems containing radioactive material. These results will be of use in the development of uranium extraction systems for contaminated water sources.