Adsorption of UO2+2 by polyethylene adsorbents with amidoxime,carboxyl, and amidoxime/carboxyl group

The polyethylene (PE) adsorbents were prepared by a radiation-induced grafting of acrylonitrile (AN), acrylic acid (AA), and the mixture of AN/AA onto PE film, and by subsequent amidoximation of cyano groups of poly-AN graft chains. With an increase of AA composition in AN/AA monomer mixture, the water uptake of the grafted polyethylene film increased. In AN/AA mixture, the maximum adsorption of UO²⁺₂ was observed in the adsorbent with a ratio of AN/AA (50/50, mol%) in copolymer. The amidoxime, carboxyl, and amidoxime/carboxyl groups onto PE acted as a chelating site for the selected UO²⁺₂. The complex structure of polyethylene with three functional groups and UO²⁺₂ was confirmed by Fourier Transform Infrared (FTIR) spectroscopy.     

用含偕胺肟基螯合纤维吸附、还原Au^3＋的研究（Ⅱ）：—氧化还原过程的初步研究

讨论了含偕胺肟基螯合纤维对Au^3 的还原过程及螯合与还原反应间的关系。结果表明，含偕胺肟基螯合纤维在吸附Au^3 的过程中，功能基螯合Au^3 之后再将其部分还原成单质金，而偕胺肟基则先被氧化成酰氨基进而变成羧基，吸附了Au^3 的纤维经径高温灼烧后合理使可得到海绵金。     

Adsorption of UO2 2+ from aqueous solution onto copolymers of styrene and maleic anhydride

The copolymers of styrene and maleic anhydride resin (PSt/MA) was synthesized by free radical polymerization and characterized by means of FTIR. It is shown that the PSt/MA copolymer has rather strong coordination ability to UO₂ ²⁺ ions by chelation with the carboxylate group, and the microstructures of the U(VI)-PSt/MA complexes can be well controlled. The influence factors on UO₂ ²⁺ ions were also investigated and described in detail, such as contact time, solid/liquid ratio, pH value, ethanol content, and initial concentration. It was found that the maximum adsorption quantity of UO₂ ²⁺ was 831 mg/g. Experiments show that PSt/MA can recover UO₂ ²⁺ ions with high adsorption selectively from a simulated industry solution containing Ca²⁺ and Mg²⁺ as impurities. The adsorption kinetic data were best described by the pseudo-second-order equation, indicating that the chemical adsorption was the rate-limiting step. And there are very good correlation coefficients of linearized equations for Langmuir model, which indicated that the sorption isotherm of the PSt/MA for UO₂ ²⁺ can be fitted to the Langmuir model. After five times of repeated tests for the hydrogel it still remained its excellent adsorption.     

Photoinduced Multiple Effects to Enhance Uranium Extraction from Natural Seawater by Black Phosphorus Nanosheets

Based on the photoinduced photothermal, photoelectric, and photocatalytic effects of black phosphorus (BP) nanosheets, a BP‐PAO fiber with enhanced uranium extraction capacity and high antibiofouling activity is fabricated by compositing BP nanosheets into polyacrylamidoxime (PAO). The photothermal effect increases the coordination interaction between UO₂²⁺ and the functional amidoxime group, and the photoelectric effect produces the surface positive electric field that exhibits electrostatic attraction to the negative [UO₂(CO₃)₃]^4?, which all increase the capacity for uranium adsorption. The photocatalytic effect endows the adsorbent with high antibiofouling activity by producing biotoxic reactive oxygen species. Owing to these three photoinduced effects, the photoinduced BP‐PAO fiber shows a high uranium adsorption capacity of 11.76 mg g^?1, which is 1.50 times of the PAO fiber, in bacteria‐containing natural seawater.     

A uranyl sulfate cluster in Na10[(UO2)(SO4)4](SO4)2·3H2O

Decasodium uranyl hexa­sulfate trihydrate, Na₁₀[(UO₂)(SO₄)₄](SO₄)₂·3H₂O, contains an unusual uranyl sulfate cluster with the composition [(UO₂)(SO₄)₄]^6?. The cluster is composed of a uranyl pentagonal bipyramid and four sulfate tetrahedra. Three sulfate tetrahedra are linked to the uranyl pentagonal bipyramid by the sharing of vertices, and the other shares an equatorial edge of the uranyl pentagonal bipyramid. The uranyl sulfate clusters occur in layers parallel to (010). The structure also contains two isolated symmetrically distinct sulfate tetrahedra, which also occur in layers parallel to (010). The uranyl sulfate clusters and isolated sulfate tetrahedra are linked through bonds to Na⁺ cations, and by hydrogen bonding involving the water molecules.     

Evolution of Actinyl Peroxide Clusters U28 in Dilute Electrolyte Solution: Exploring the Transition from Simple Ions to Macroionic Assemblies

Actinyl peroxide clusters, a unique class of uranyl‐containing nanoclusters discovered in recent years, are crucial intermediates between the (UO₂)²⁺ aqua‐ion monomer and bulk uranyl minerals. Herein, two actinyl polyoxometalate nanoclusters of Cs₁₅[(Ta(O₂)₄)Cs₄K₁₂(UO₂(O₂)_1.5)₂₈] ? 20 H₂O (CsK U₂₈ ) and Na₆K₉[(Ta(O₂)₄)Rb₄Na₁₂(UO₂(O₂)_1.5)₂₈] ? 20 H₂O (RbNa U₂₈ ) were synthesized by incorporating a central Ta(O₂)₄^3? anion that templates a hollow shell of 28 uranyl peroxide polyhedra. When dissolved in aqueous solutions with additional electrolytes, those 1.8 nm‐size macroanions self‐assembled into spherical, hollow, blackberry‐type supramolecular structures, as was characterized by laser‐light scattering (LLS) and TEM techniques. These clusters are the smallest macroions reported to date that form blackberry structures in solution, therefore, can be treated as valuable models for investigating the transition from simple ions to macroions. Kinetic studies showed an unusually long lag phase in the initial self‐assembly process, which is followed by a rapid formation of the blackberry structures in solution. The small cluster size and high surface‐charge density are essential in regulating the supramolecular structure formation, as was shown from the high activation energy barrier of 51.2±2 kJ mol^?1. Different countercations were introduced into the system to investigate the effect of ion binding to the length of the lag phase. The current research provides yet another scale of self‐assembly of uranyl peroxide complexes in aqueous media.     

Synthesis of a new ionic imprinted polymer for the extraction of uranium from seawater

The ionic imprinted polymer (IIP) of uranyl ion (UO₂ ²⁺) as the template was synthesized by the formation of binary complexes of UO₂ ²⁺ with 2,4-dioxopentan-3-yl methacrylate as functional monomer followed by thermal copolymerization with ethylene glycol dimethacrylate as cross-linking monomer in the presence of 2,2′-azobisisobutyronitrile as initiator and 1,4-dioxane as porogenic solvent. 50 mmol L^?1 HCl solution was used to leach out UO₂ ²⁺ ions from the IIP. Similarly, the control polymer was prepared under identical experimental conditions without using UO₂ ²⁺ ions. The above synthesized polymers were characterized by infra-red spectroscopy, thermo-gravimetric analysis and Barrett–Emmett–Teller surface area measurement. The maximum adsorption capacities of IIP and CP in (NH₄)₄[UO₂(CO₃)₃] solution were 15.3 and 11.2 mg U g^?1, respectively. The kinetics of adsorption followed a pseudo-second-order rate equation. The prepared IIP was successfully used to extract uranium from real seawater sample.     

Adsorption and Equilibrium Isotherm Study of Removal of Copper (II) Ions from Aqueous Solution by Chemically Modified Abelmoschus esculentus Fibers

The present study explores surface modification of Abelmoschus esculentus by graft copolymerization reaction using acrylonitrile as a monomer and ascorbic acid/H₂O₂ as a redox initiator. Further, polyacrylonitrile grafted fibers were treated with hydroxylamine to convert the nitrile group of the grafted fiber into the amidoxime group to enhance adsorption of copper ions from wastewater. The graft copolymers and amidoximated fibers were characterized by FT-IR and FE-SEM. The effects of physicochemical parameters such as pH of the solution, initial metal ion concentration, and time on Cu(II) adsorption were studied to optimize condition for maximum adsorption. In addition, Langmuir, Freundlich, and Tempkin models were applied to describe the adsorption isotherm of Cu²⁺ ions.     

Adsorption isotherm for uranyl biosorption by Saccharomyces cerevisiae biomass

Biosorption of uranyl ions from aqueous solution by Saccharomyces cerevisiae was studied in a batch system. The influence of contact time, initial pH, temperature and initial concentration was investigated. The optimal conditions were found to be 3.5?h of contact time and pH?=?4.5. Temperature had no significant effect on adsorption. The uptake of uranyl ions was relatively fast and 85?% of the sorption was completed within 10?min. The experimental data were well fitted with Langmuir isotherm model and pseudo-second order kinetic model. According to this kinetic model, the sorption capacity and the rate constant were 0.455?mmol UO₂ ²⁺/g dry biomass and 1.89?g?mmol^?1?min^?1, respectively. The Langmuir isotherm indicated high affinity and capacity of the adsorbent for uranyl biosorption with the maximum loading of 0.477?mmol UO₂ ²⁺/g dry weight.     

Chemically modified kapok fiber for fast adsorption of Pb2+, Cd2+, Cu2+ from aqueous solution

Kapok fiber, a natural hollow fiber with thin shell and large cavity, has rarely been used as adsorbent for heavy metal ions. In this paper, kapok fibers were modified with diethylenetriamine pentaacetic acid (DTPA) after hydrophilicity treatment. The adsorption behavior of the resultant kapok-DTPA influenced by pH, adsorption time and initial concentration of metal ion was investigated. The results demonstrate that adsorption equilibrium was reached within 2 min for Pb²⁺ and Cd²⁺. Adsorption kinetics showed that the adsorption rate was well fitted by pseudo-second-order rate model. The adsorption isotherms were studied, and the best fit was obtained in the Langmuir model. The maximum adsorption capacities of kapok-DTPA were 310.6 mg g^?1 for Pb²⁺, 163.7 mg g^?1 for Cd²⁺, 101.0 mg g^?1 for Cu²⁺, respectively. After eight desorption and re-adsorption loops, the lost adsorption capacities for Pb²⁺ and Cu²⁺ were less than 10 %. Because of the large specific area derived from the hollow fiber structure, kapok-DTPA exhibited much better adsorption capacity compared with many other reported adsorbents based on natural materials.     

Equilibrium and kinetics study of uranium(VI) from aqueous solution by Citrus limetta peels

The potential of the biowaste Citrus limetta peels (CLP) was assessed for adsorption of uranium(VI) from uranyl nitrate solution. Maximum adsorption capacity of 75.33 mg g^?1 was achieved at pH 4, showing drastic falls thereafter. This was attributed to the presence of UO₂ ²⁺, UO₂OH⁺, (UO₂)₃(OH)⁵⁺ and (UO₂)₂(OH) ₂ ²⁺ ions. The peels were characterized for elucidating the role of functional groups and morphology on the sorption capacity. The isotherm studies revealed that Langmuir, Freundlich as well as Sips models give the best fit for the experimental data observing pseudo second order kinetics. The equilibrium was achieved in 90 min. The adsorption shows complex mechanism, took place by both physical and ion-exchange mechanism.     

Synergistic coupled transport of uranyl ion across bulk liquid membrane mediated by dioxa-diazamacrocycle and oleic acid

Synergistic coupled transport of uranyl ion across a bulk liquid membrane of chloroform has been investigated using a dioxa-diazamacrocycle and oleic acid as carrier and synergistic agents, respectively. Quantitative transport of uranyl ion was achieved within 4 h when the pH of source solution was kept at 5.0–6.0 and mole ratio of carrier to synergistic agent was 1/15. It was found that overall rate and selectivity of the transport is governed by the stripping step. Finally, the influence of some foreign competitor ions including Al³⁺, Ca²⁺, CO₃^2?, Cu²⁺, Mg²⁺, Pb²⁺, Zn²⁺ and Th⁴⁺ and also the ionic strength on the transport efficiency has been evaluated.     

Adsorptive features of polyacrylic acid hydrogel for UO2 2+

Polyacrylic acid hydrogel was synthesized by Free Radical polymerization and characterized by means of FTIR. The FTIR results show that the carboxylic groups in the complexes coordinated to the metal ions in the form of two dentate. The effects of contact time, solid/liquid ratio, pH value, and initial concentration on the adsorption of UO₂ ²⁺ ions onto polyacrylic acid were investigated. The adsorption of UO₂ ²⁺ ions was highly dependent on the initial pH of metal ions solution and initial metal ions concentration. The adsorption kinetic data indicated that the chemical adsorption was the swiftness processes, the adsorption equilibrium could be achieved within 15 min. And there are very good correlation coefficients of linearized equations for Freundlich model, which indicated that the sorption isotherm of the hydrogel for UO₂ ²⁺ can be fitted to the Freundlich model. It was found that the maximum adsorption quantity of UO₂ ²⁺ was 1,179 mg/g. After five times of repeated tests for the hydrogel it still remained its excellent adsorption.     

Azido chelating fiber: synthesis,characterization and adsorption performances towards Hg2+ and Pb2+ from water

Herein, we report the synthesis and adsorption property of a novel chelating fiber containing azido group. Firstly, the brominated fiber (PP‐St‐DVB‐Br) was obtained via the reaction of polypropylene‐(g)‐styrene‐divinylbenzene fiber (PP‐St‐DVB) with bromine in CH₂Cl₂ solution. Then, azido chelating fiber (PP‐St‐DVB‐N₃) was prepared by azidation of PP‐St‐DVB‐Br fiber. Its structure and properties were characterized by Fourier transform infrared, elemental analysis, thermogravimetric analysis, and chemical titration, respectively. The micromophology and functional group distribution in fibrous matrix were investigated by scanning electron microscopy‐energy dispersive spectroscopy. The results show that the chelating fiber has high functional group contents (2.11 mmol/g for PP‐St‐DVB‐N₃) and uniform distribution. Different from granulate chelating resin, the novel fibrous adsorbent possesses excellent adsorption ability for Hg(II) and Pb(II) ions (408.9 mg/g for Hg²⁺ and 334.4 mg/g for Pb²⁺), and the adsorption capacity of the fiber has no loss until five cycles. The novel absorbent material shows the potential application prospect in the treatment of heavy metal wastewater. Copyright © 2017 John Wiley & Sons, Ltd.     

Heat of adsorption of carbon dioxyde and ethene on zeolites a exchanged with Li+, Ni2+ and Cu2+

Various contents of Li⁺, Ni²⁺ or Cu²⁺ were introduced in zeolite NaA by conventional cation exchange. Crystal damages are observed on samples having suffered the lowerpH. The heat of adsorption of CO₂ and C₂H₄ was determined by isothermal calorimetry. Very high initial heats (100–120 kJ mol^?1) are found in NaA as well as in Li⁺ exchanged samples, perhaps due to chemisorption on alkaline cations; they vanish when Ni²⁺ or Cu²⁺ replaces more than 20% of Na⁺, in like manner with Co²⁺ or ZnI²⁺. For the adsorption of C₂H₄, high initial heats are absent in the case of NaA, but gradually appear when divalent cations are introduced. Apart from these strong initial values, the heats of adsorption present a plateauvs. the adsorbed amount. Abnormal low values at the plateau are indicative of crystal damages.     

Synthesis and applications of poly(acryl<Emphasis Type="Italic">p</Emphasis>-aminobenzenesulfonamideamidine-<Emphasis Type="Italic">p</Emphasis>-aminobenzenesulfonylamide) chelating fiber for pre-concentrating and separating trace Bi(III), Hg(III), Au(III) and Pd(IV) from solution samples

Poly(acrylp-aminobenzenesulfonamideamidine-p-aminobenzenesulfonylamide) chelating fiber containing "S", "N", and "O" elements was synthesized from polyacrylonitrile fiber and p-aminobenzene sulfonamide and used to enrich and separate trace Bi(III), Hg(III), Au(III), and Pd(IV) ions from wastewater and ore sample solution. The enrichment acidity, flow rate, elution conditions, reuse, interference ions, saturated adsorption capacity, constant of adsorption rate, analytical accuracy, and actual samples on chelating fiber were investigated by means of inductively coupled plasma optical emission spectrometry (ICP-OES) with satisfactory results. Solutions of 100 ng mL^–1 of Bi(III), Hg(III), Au(III), and Pd(IV) ions can be enriched quantitatively by this chelating fiber at a rate of 1.0 mL min^–1 at pH 4 and desorbed quantitatively with 20 mL of 0.25 M HCl and 2% CS(NH₂)₂ solution at 50 °C (with recovery 97%). When the chelating fiber was reused for 20 times, the recoveries of the analyzed ions enriched by the fiber were still over 95% (except for Hg(III)). One thousand-fold excesses of Mn²⁺, Ca²⁺, Zn²⁺, Mg²⁺, Fe³⁺, Cu²⁺, Ni²⁺, Al³⁺, and Ba²⁺ ions and thousands-fold excesses of Na⁺ and K⁺ cause little interference in the pre-concentration and determination of the analyzed ions. The saturated adsorption capacity of Bi(III), Hg(III), Au(III), and Pd(IV) was 4.850×10^–4, 3.235×10^–4, 2.807×10^–4, and 3.386×10^–4 mol g^–1, respectively. The constants of adsorption rate were 0.409 min^–1 for Bi, 0.122 min^–1 for Hg, 0.039 min^–1 for Au, and 0.080 min^–1 for Pd. The relative standard deviations (RSDs) for the enrichment and determination of 10 ng mL^–1 Bi(III), Hg(III), Au(III), and Pd(IV) were lower than 2.3%. The results obtained for these ions in actual samples by this method were basically in agreement with the given values with average errors of less than 1.0%. FT-IR spectra shows that the existence of –SO₂–Ar, –H₂N–Ar, O=C–NH–, HN=C–NH–, and –HN–SO₂ functional groups are verified in the chelating fiber. From the FT-IR spectroscopy, we can see that Hg(III), Au(III), and Pd(IV) are mainly combined with nitrogen and sulfur (or oxygen), and Bi(III) is mainly combined with nitrogen (or oxygen) of the groups to form a chelating complex.     

Synthesis of lariat organochalcogenoethers based on azacalix[3]arenes for the potentiometric detection of [UO2] ions

The syntheses of organochalcogen-supported azacalix[3]arenes are described in a one-pot manner in satisfactory yields. A remarkably selective potentiometric response was accomplished for uranyl ions over a variety of other metal ions, including alkali (Na⁺, K⁺), alkaline-earth (Mg²⁺, Ca²⁺, Ba²⁺), transition and heavy metal ions (Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Fe³⁺, Zn²⁺, Cd²⁺ and Pb²⁺) using an ion-selective electrode based on compound 3 incorporated into a polymeric (PVC) membrane.     

Adsorption properties of amine modified lignin-hydrogel composite for uranyl ions: Theoretical and experimental insights

A new modified material was synthesized and characterized as ethylene diamine modified (EA) Polyacrylamide (PAA)-Lignin (L). The adsorption features of EA modified PAA-L were studied for uranyl ions. The characterization experiments were evaluated by FT-IR spectroscopic techniques, scanning electron microscopy (SEM), and PZC analysis. Adsorption of UO₂²⁺ ions as a function of concentration, pH, temperature, and time of adsorption were studied. The adsorption phenomenon of UO₂²⁺ ions onto PAA-L-EA from aqueous medium was successfully evaluated by various equilibrium models such as Langmuir, Freundlich, and Dubinin-Radushkevich (DR). The (Qe) maximum adsorption capacity values for Langmuir model was calculated as 0.792 kg mol^?1 by using experimental data. The constant values of thermodynamic parameters such as (ΔG°), (ΔH°) and (ΔS°) were calculated and it has observed that the mechanism of adsorption was found compatible with endothermic and spontaneous owing to increasing disorderliness at solution/solid system. The adsorption mechanism is compatible with Elovich and intraparticle diffusion models. The power of the interaction between modified lignin and uranyl ?on was explained in the light of Hard and Soft Acid-Base Principle.     

Organoclay modified with lignin as a new adsorbent for removal of Pb2+ and UO2 2+

This study investigated a new adsorbent prepared from lignin modified organoclay for the removal of Pb²⁺ and UO₂ ²⁺ from aqueous solutions. The characterization of new adsorbent was performed by FT-IR and XRD. Adsorption of Pb²⁺ and UO₂ ²⁺ species in aqueous solution as a function of ion concentration, pH, temperature and time of adsorption was investigated in detail. The adsorption data were analyzed by using the Langmuir, Freundlich and Dubinin-Radushkevich models. The monolayer adsorption capacities of organoclay–lignin were 0.12 mol kg^?1 and 0.42 mol kg^?1 for Pb²⁺ and UO₂ ²⁺, respectively. The experimental kinetic data were analyzed by using pseudo-second-order kinetic and intra-particle diffusion models. The proposed adsorption mechanism follows a pseudo-second-order kinetic and endothermic because of increasing disorderliness at adsorbate/adsorbent interface.     

Study of solvent extraction of <Superscript>114m</Superscript>In(III) using quinaldic acid into isoamyl alcohol

A complementary study of hydroxyl radical formation in the depleted uranium (DU)-hydrogen peroxide (H₂O₂) system and the effect of biosubstances on the system were examined using the spin-trapping method. Hydroxyl radical was formed in the uranyl ion (UO₂ ²⁺), 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), and hydrogen peroxide (H₂O₂) mixture solution. The pseudo first order rate constants of DMPO-OH formation were estimated to be 0.033 s⁻¹ for UO₂ ²⁺-H₂O₂-DMPO solution and 0.153 s⁻¹ for UO₂₊-H₂O₂-DMPO solution. The obtained results indicated that the hydroxyl radical formation in the UO₂ ²⁺-H₂O₂ solution could be described as a stepwise reaction process including the reduction of UO₂ ²⁺ to UO₂ ²⁺ by H₂O₂ and the Fenton-type reaction of UO₂ ⁺ with H₂O₂. Biosubstances, such as proteins, amino acids and saccharides, decreased the DMPO-OH formation, which was caused by the direct hydroxyl radical scavenging and the suppression of hydroxyl radical formation by coupling with uranyl ion.