Uptake Of Uranyl Ions Research Articles

Synthesis and characterization of gum ghatti grafted chelating copolymer for an effective removal of uranyl ions

In this report, we intended to synthesize chelating grafted copolymer of gum ghatti with acrylonitrile (Gg-g-An) by gamma irradiation as proficient and influential adsorbent for removal of uranyl ions. These grafted and modified copolymers were characterized using different techniques viz. FTIR, Elemental analysis, TGA and FESEM. Maximum grafting was accomplished with 5% gum ghatti solution and 1:3 ratio of acrylonitrile to backbone at 25 kGy total radiation dose. Surface area of grafted copolymer was calculated by BET analysis. Adsorption experiments reveal the adsorption capacity was effectively influenced at pH 6 with maximum adsorption 94% which substantiated Gg-g-AO surface engross excellent potential as chelating agent for adsorption of uranyl ions. Uptake of uranyl ions by Gg-g-AO was confirmed using spectroscopic and EDX analysis. The result showed that the pseudo second order reaction and Langmuir adsorption isotherms had remarkable conformity through linear fit statistics with r2 0.998 and 0.978 respectively. Furthermore, the thermodynamic parameters illustrated that the uranyl ions adsorption process by Gg-g-AO was endothermic and spontaneous. Desorption studies of Gg-g-AO confirmed the reusability up to three cycles in 0.1 M HCl. This study substantiated that the synthesized Gg-g-AO has impending use in environmental remediation.

Hydrothermal carbon superstructures enriched with carboxyl groups for highly efficient uranium removal

Carbon superstructures with graphitized lamellar microstructures were fabricated through a modified hydrothermal method. The dual oxidation process combining acrylic acid functionalization and air thermal treatment introduced plentiful carboxyl groups on the surface of the carbon superstructures. Adsorption capacity of U(VI) on the as prepared carbon superparticles reached 197.7 mg g−1, which was 9-fold higher than that of raw glucose-derived hydrothermal carbon microspheres. The thermo-dynamic and kinetic studies demonstrated that the uptake of uranyl ions was a spontaneous and endothermic chemisorption dominated process with the abundant carboxyl groups acting as main binding sites. Impressively, the carbon superstructure adsorbents showed excellent recycling performance. To sum up, this paper proposed a novel high-performance U(VI) adsorbent from hydrothermal carbon, which exhibited potential in real application due to their outstanding reusability and scale-up capability.

Application of highly swollen novel biosorbent hydrogels in uptake of uranyl ions from aqueous solutions

The aim of this study was to investigate the equilibrium swelling and uranyl ion sorption properties of chemically crosslinked copolymeric hydrogels as biopotential sorbent consisting of acrylamide (AAm), sodium acrylate (SA), gelatin (GEL) and poly(ethylene glycol) (PEG). Semi-interpenetrating polymer network (semi IPNs) hydrogel, composed of AAm with SA as co-monomer, with PEG and GEL and a multifunctional crosslinker such as poly(ethylene glycol) diacrylate (PEGDA) was prepared by free radical solution polymerization by using ammonium persulphate (APS)/N,N,N′,N′-tetramethylethylenediamine (TEMED) as redox initiating pair. Swelling experiments were performed in water at 25 °C, gravimetrically. The hydrogels showed enormous swelling in water and displayed swelling characteristics that were highly depended on the chemical composition of the hydrogels. For characterization, FT-IR, thermogravimetric analysis (TG and DTG) and surface morphology (SEM) studies have been realized. FTIR spectroscopy was used to identify the presence of different repeating units in the semi IPNs. Some swelling and diffusion characteristics were calculated for different semi IPNs and hydrogels prepared under various formulations. For sorption studies, uranyl ion into the hydrogels was studied by batch sorption technique at 25 °C. Sorption capacity, removal effiency and partition coefficient of the hydrogels was investigated. Swelling and uranyl ion sorption properties of AAm/SA, AAm/GEL/SA, AAm/PEG/SA and AAm/GEL/PEG/SA hydrogel systems were investigated as a function of chemical composition of the hydrogels.

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%.

Synthesis of bulk ion-imprinted polymers (IIPs) embedded with oleic acid coated Fe<sub>3</sub>O<sub>4</sub> for selective extraction of hexavalent uranium

A selective and reliable method for the extraction of trace quantities of U(VI) by the use of a magnetic U(VI) ion-imprinted polymer (IIP) was developed. In this study, oleic acid (OA) coated magnetite nano-particles were incorporated into the cross-linked polymeric matrix of the selective sorbent, in order to gain the physical advantages of separating the polymers. Many physico-chemical factors influence the adsorption process; uranyl ion uptake ability based on these parameters was investigated. The optimum parameters obtained were sample pH 4,50 mg of the magnetic polymer, a contact time of 45 min and an initial U(VI) concentration of 2 mg·ℓ-1. The adsorption capacities for the magnetic NIP and IIP were found to be 0.95 mg·g1 and 1.21 mg·g-1, respectively. The adsorption behaviour of U(VI) in the presence of other competing metal ions onto the cross-linked magnetic polymers was also examined in binary mixtures and the order of selectivity was found to be U(VI) > Pb(VI) > Ni(II). The resulting magnetic nano-composite polymers were found to be stable up to the sixth cycle of use and reuse. The Freundlich adsorption model was used for the mathematical description of the adsorption equilibrium and the adsorption kinetic data fitted the pseudo-first-order model with R2 > 0.92.Keywords: Bulk, magnetic imprinted polymers, oleic acid, uranium

Fast and High Amount of Uranyl Ion Uptake by p(Vinyl Phosphonic Acid) Microgels Prepared by UV Irradiation Technique

Micrometer-size poly(vinyl phosphonic acid) (p(VPA)) hydrogel was synthesized by employing UV irradiation of an emulsion containing vinyl phosphonic acid (VPA) and crosslinker, prepared using lecithin as surfactant and gasoline as solvent. The p(VPA) microgels were employed in absorption of UO2 2+ ions from aqueous environments and have very high and fast absorption capacity. In about 20 min, 670 mg UO2 2+ ions were absorbed per gram of p(VPA) microgel from the prepared UO2 2+ ion solution, and the absorption capacity increased up to 900 mg at pH 6. Various parameters affecting UO2 2+ absorption characteristics of p(VPA) were investigated. It was found that the Langmuir isotherm fitted the absorption characteristics of p(VPA) better than the Freundlich isotherm. Moreover, magnetic ferrite can be prepared within p(VPA) and used as a magnetically responsive p(VPA) microgel composite for externally controlled absorption of UO2 2+ ions with little decrease in the absorption capacity of the p(VPA) microgel.

Biosorption of uranyl ions from aqueous solution by Saccharomyces cerevisiae cells immobilized on clinoptilolite

This study deals with the uptake of uranyl ions from aqueous solution using bio-modified natural clinoptilolite. The biosorption experiments were carried out in a batch system. Cell immobilization process and sorption of uranyl ions were confirmed by scanning electron microscopy and inductively coupled plasma-optical emission spectroscopy techniques, respectively. The adsorption equilibrium was reached in 4 h, the optimum pH was 4.5 and the temperature had no significant effect on the uranyl biosorption. The experimental data were well fitted with Langmuir isotherm and pseudo-second-order kinetic models. The maximum sorption capacity of cell immobilized clinoptilolite was 0.148 mmol (\( {\text{UO}}_{2}^{2 + } \)) g−1 dry sorbent.

Seawater Uranium Sorbents: Preparation from a Mesoporous Copolymer Initiator by Atom‐Transfer Radical Polymerization

The world s oceans, where uranium is found quite uniformly at a concentration of 3.3 mgL , present an alternative source of uranium to terrestrial mining for nuclear fuel. Environmental concerns associated with mining will undoubtedly increase as reserves are depleted, thus increasing the utility of more environmentally friendly feedstocks. Hence, before terrestrial resources become scarce, the development of sorbents designed for seawater extraction is of strategic importance to guarantee future uranium resources. From the first inorganic adsorbents, which showed poor selectivity and mechanical resistance, to the most recent polyethylene-fiberbased sorbents containing amidoxime–carboxylic acid copolymers, and more recently layered metal sulfides and metal– organic frameworks, interest in uranium seawater extractions has continuously increased among governments worldwide. Because the concentration of uranium in the oceans is relatively low, maximization of the adsorption properties of sorbents, for example, through changes in their surface area and pore structure, can greatly improve the kinetics of uranium extraction and the adsorption capacity simultaneously. To facilitate the uptake of uranyl ions with fast kinetics, various sorbents containing the amidoxime group, such as hydrogels, particles and beads, membranes, macroporous fibers, and composites, have been prepared by suspension polymerization, radiation-induced grafting, and even sonochemical functionalization. However, silica beads and most carbon materials have a relatively small accessible surface area for the growth of large polymers or a low number of surface sites available for the grafting of functional groups. Thus, the design of substrates with large numbers of accessible reactive sites for the grafting of polymeric surface groups is necessary for the development of materials with improved uranium-adsorption capacity. Recently, porous polymers based on divinylbenzene (DVB) have been developed for applications in separations and catalysis. For example, the copolymerization of p-styrene sulfonate with divinylbenzene led to a catalytically active porous polymer. This method has the additional advantage that polymers can be obtained with controlled porosity and high surface areas without porogens. It is thus timeand cost-effective, as well as more environmentally friendly than the templated synthesis of carbonaceous materials. Motivated by these findings, we report herein nanoporous polymers based on the vinylbenzyl chloride (VBC) monomer and the DVB cross-linking agent. As well as a well-developed nanoporous structure of microand mesopores, the obtained polymers contain large numbers of accessible chlorine species, which can be used as initiators for atom-transfer radical polymerization (ATRP). These materials are the first examples of ATRP initiators in which the initiator species is located within the framework of the mesoporous support. The accessible framework and surface chlorine species were used to grow polyacrylonitrile chains, which were then converted into polyamidoxime for uranium adsorption from seawater with tailorable adsorption and surface properties. Three copolymer monoliths were synthesized by freeradical polymerization; that is, the monomer 4-vinylbenzyl chloride was cross-linked by divinylbenzene with 2,2’-azobisisobutyronitrile (AIBN, 98%) as the initiator to give copolymers hereafter referred to as p(xDVB-VBC) (in which x stands for the molar ratio of DVB to VBC). By varying the ratio of the monomer and the cross-linking reactant, it was possible to adjust the pore structure, that is, the surface area and pore volume (Figure 1). Since these adjustments arose from changes in the DVB to VBC ratio, the initiator concentration (i.e. the amount of chloride substituents present) was also varied. The nitrogen isotherms measured at 196 8C for the samples show that nonporous materials as well as materials with tailorable mesopore volumes can be [*] Dr. Y. Yue, Dr. R. T. Mayes, Dr. P. F. Fulvio, Dr. X.-G. Sun, Prof. Dr. S. Dai Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge, TN 37831 (USA) E-mail: dais@ornl.gov

Separation of uranyl ion using polyaniline

Polyaniline (Pani) was synthesized by the chemical oxidation of aniline. The use of persulphate instead of dichromate was desired in order to avoid the incorporation of chromium in the polymer matrix. The presence of chromium in the matrix, when dichromate was used as an oxidant, was confirmed by various techniques. The batch mode experiments showed that Pani could be used for separation of different metal ions. These ions were converted into their anionic complexes using suitable complexing agents. It was found that EDTA was used as a suitable reagent for the separation of Cu2+ from Zn2+ whereas the uranyl ion uptake could be increased to about 95 % when carbonate was used instead of EDTA as complexing agent. A possible application of the above exchange system to preconcentration of uranyl ion from seawater has also been examined.

Uranium uptake onto Magnox sludge minerals studied using EXAFS

AbstractAround the world large quantities of sludge wastes derived from nuclear energy production are currently kept in storage facilities. In the UK, the British government has marked sludge removal as a top priority as these facilities are nearing the end of their operational lifetimes. Therefore chemical understanding of uranium uptake in Mg-rich sludge is critical for successful remediation strategies. Previous studies have explored uranium uptake by the calcium carbonate minerals, calcite and aragonite, under conditions applicable to both natural and anthropogenically perturbed systems. However, studies of the uptake by Mg-rich minerals such as brucite [Mg(OH)2], nesquehonite [MgCO3·3H2O] and hydromagnesite [Mg5(CO3)4(OH)2·4H2O], have not been previously conducted. Such experiments will improve our understanding of the mobility of uranium and other actinides in natural lithologies as well as provide key information applicable to nuclear waste repository strategies involving Mg-rich phases. Experiments with mineral powders were used to determine the partition coefficients (Kd) and coordination of UO22+ during adsorption and co-precipitation with brucite, nesquehonite and hydromagnesite. The Kd values for the selected Mg-rich minerals were comparable or greater than those published for calcium carbonates. Extended X-ray absorption fine structure analysis results showed that the structure of the uranyl-triscarbonato [UO2(CO3)3] species was maintained after surface attachment and that uptake of uranyl ions took place mainly via mineral surface reactions.

Uptake of uranyl ions from uranium ores and sludges by means of Spirulina platensis, Porphyridium cruentum and Nostok linckia alga

In this paper was studied the uranyl ions biosorption on three types of alga: Nostok linckia, Porphyridium cruentum and Spirulina platensis. These ions were supplied either from a pure solution of uranyl nitrate, or after leaching process of uranium ore, or from the sludge resulting in the output of pure UO2 technology.It was investigated the retention degree versus contact time and afterwards the Langmuir and Freundlich biosorption isotherms of uranyl ions on the three alga types.The retention of UO22+ ions on alga was proved through FTIR spectra plotted before and after biosorption processes.From the experimental data it was found that regardless of origin of uranyl ions, the retention degree on alga decreased in the series.Spirulinaplatensis>Porphyridiumcruentum⩾Nostoklinckia.

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.

Investigation of 7-((dioctylamino)methyl)quinoline-8-ol for uptake and removal of uranyl ions

A new 8-hydroxyquinoline derivative extractant was synthesized via the Mannich reaction from a secondary amine. Various analytical techniques (1H, 13C NMR, FTIR, mass spectroscopy) were used to characterize our product. The use of this new extractant for the uptake and removal of uranyl ions in aqueous solution was investigated. Conditions for an effective sorption were optimized with respect to different experimental parameters in batch process. The results showed that the extraction rate increases for solutions with a pH in the range [0.65–1.13]. The total sorption capacity was 105 (mg g−1) under optimum experimental conditions. The extraction of UO2 2+ was found to be quantitative (100 %) at initial uranyl concentration less than or equal to 41.59 mg/L. Thermodynamic parameters showed the adsorption of an endothermic process and a spontaneous nature, respectively.

Uranyl ion uptake capacity of poly (N-isopropylacrylamide/maleic acid) copolymeric hydrogels prepared by gamma rays

The effect of gel composition, absorbed dose and pH of the solution on the uranyl ion uptake capacity of N-isopropylacrylamide/maleic acid copolymeric hydrogels containing 0–3mol% of maleic acid at 48kGy have been investigated. Uranyl uptake capacity of hydrogels are found to increase from 18.5 to 94.8mg [UO22+]/g dry gel as the mole % of maleic acid content in the gel structure increased from 0 to 3. The percent swelling, equilibrium swelling and diffusion coefficient values have been evaluated for poly(N-isopropylacrylamide/maleic acid) hydrogels at 500ppm of uranyl nitrate solution.

Highly Porous Acrylonitrile-Based Submicron Particles for UO22+ Absorption in an Immunosensor Assay

Our laboratory has previously reported an antibody-based assay for hexavalent uranium (UO(2)(2+)) that could be used on-site to rapidly assess uranium contamination in environmental water samples (Melton, S. J.; et al. Environ. Sci. Technol. 2009, 43, 6703-6709). To extend the utility of this assay to less-characterized sites of uranium contamination, we required a uranium-specific adsorbent that would rapidly remove the uranium from groundwater samples, while leaving the concentrations of other ions in the groundwater relatively unaltered. This study describes the development of hydrogel particles containing amidoxime groups that can rapidly and selectively facilitate the uptake of uranyl ions. A miniemulsion polymerization technique using SDS micelles was employed for the preparation of the hydrogel as linked submicrometer particles. In polymerization, acrylonitrile was used as the initial monomer, ethylene glycol dimethacrylate as the crosslinker and 2-hydroxymethacrylate, 1-vinyl-2-pyrrolidone, acrylic acid, or methacrylic acid were added as co-monomers after the initial seed polymerization of acrylonitrle. The particles were characterized by transmission electron spectroscopy, scanning electron microscopy (SEM) and cryo-SEM. The amidoximated particles were superior to a commercially available resin in their ability to rapidly remove dissolved UO(2)(2+) from spiked groundwater samples.

Behaviors of polyelectrolyte AAm/AMPS/bentonite composite hydrogels in uptake of uranyl ions from aqueous solutions

Uranyl ion (UO22+) sorption properties of polyelectrolyte composite hydrogels made by the polymerization of acrylamide (AAm) with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and clay such as bentonite (Bent) were investigated as a function of composition to find materials with swelling and uranyl ion sorption properties. Highly swollen AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels were prepared by free radical solution polymerization in aqueous solutions of AAm with AMPS as co-monomer and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4 butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. The influence of AMPS content in hydrogels was examined. Uranyl ion adsorption from aqueous solutions was studied by batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of AMPS on the uranyl ion adsorption were examined. Finally, adsorption capacity (the amount of sorbed uranyl ion per gram of dry hydrogel) (q) was calculated to be 0.67 × 10−3–2.11 × 10−3 mol uranyl ion per gram for the hydrogels. Removal effiency of uranyl ions (RE%) was changed range 9.05–29.92%. The values of partition ratio (Kd) of uranyl ions was calculated to be 0.10–0.43 for AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels, respectively. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Effect of metal ions on the lysis of yeast cells by cationic dyes and surfactants.

Abstract Uranyl ions and thorium ions are effective in preventing cytolysis by Toluidine Blue and Azure A because they interfere with dye uptake by the cells. Neither uranyl nor thorium ions prevent the uptake of cetrimide or cetylpyridinium chloride. Cetylpyridinium chloride is capable of releasing previously bound uranyl ions from the cell surface. Anionic groups belonging to lipid constituents of the cell membrane may be involved in the uptake of uranyl and thorium ions as well as in the binding of dye and surfactants cations respectively. Possible cytolytic mechanisms involving polar interactions at the cell surface with lytic cations are discussed.

Studies on the Uptake of Uranium(VI) Ions on Polyacrylamidoxime Resins Synthesized by Free Radical Polymerization with Different Crosslinking Ratios and Pore Solvents

Uptake of uranyl ions on polyacrylamidoxime resins synthesized from polymerization of acrylonitrile, and divinylbenzene as crosslinking agent in the presence of different diluents, then conversion of polyacrylonitrile to polyacrylamidoxime by hydroxylamine in basic media were investigated. FTIR on base polymer, functional resins, resins loaded with uranyl ions and that after elution were investigated. The effect of pore solvents on the morphologies of the prepared resins were examined by scanning electron microscope. Loading of uranyl ions performed with respect effects of pH, time of loading, and ratio of crosslinker. Elution of adsorbed ions carried out with different eluent and elution efficiency were determined. Regeneration of resins performed after six cycles and regeneration efficiency were determined.

Uranyl ions uptake on poly(AAc/AAm)-cl-N,N-MBAAm hydrogel

In the present article, we report two well-characterized hydrogels for the adsorption of uranyl ions from 5% NaCl solution. The hydrogel was synthesized by free radical initiation from acrylamide and acrylic acid using N,N-methylenebisacrylamide as crosslinker. In order to improve ion uptake performance, the hydrogel was hydrolyzed to partially convert some of the amide groups into carboxylate groups. The uranyl ion adsorption was studied as a function of hydrogel structure, uranyl ions concentration, pH, temperature, and mass of hydrogel. The partially hydrolyzed hydrogel exhibited the maximum uranyl ion uptake of 236.6 mgg−1 in 480 min at 45 °C and at pH 13. Good reproducibility of results was observed and the evidence of sorption at the optimum pH and ion concentration was obtained by comparison of FTIR spectra of the precursor and uranyl ions loaded hydrogels. The performance of both the hydrogels was found to be higher than that of a commercial resin, Amberlite IRC-718. The experimental data shows good match with Langmuir and Freundlich isotherms and pseudo-first order kinetics.

Behaviors of Chemically Crosslinked CAAMPS Hydrogels in Uptake of Uranyl Ions from Aqueous Solutions

Uranyl ion adsorption from aqueous solutions has been investigated by chemically crosslinked (C) polyelectrolyte acrylamide/2-acrylamido-2-methyl-1-propanesulfonic acid (CAAMPS) hydrogels. CAAMPS hydrogels with various compositions were prepared from ternary mixtures of acrylamide (A), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), and water by free radical polymerization in an aqueous solution using multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4 butanediol dimethacrylate (BDMA). The swelling equilibrium of polyelectrolyte copolymer gels containing of CAAMPS hydrogels has been studied as a function of copolymer composition. Swelling experiments were performed in water at 25°C, gravimetrically. The influence of AMPS content in hydrogels was examined. The weight-swelling ratio of CAAMPS hydrogels was increased up to 127.03 (for 300 mg AMPS and crosslinked by EGDMA) and 93.32 (for 300 mg AMPS and crosslinked by BDMA), while acrylamide hydrogels swelled up to 10.27 (crosslinked by EGDMA) and 10.06 (crosslinked by BDMA). Uranyl ion adsorption from aqueous solutions was studied by batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of AMPS on the uranyl ion adsorption were examined. In the experiments of the sorption, L type sorption in the Giles classification system was found. Finally, the amount of sorbed uranyl ion per gram of dry hydrogel (q) was calculated to be 0.67 × 10−3–2.11 × 10−3 mol uranyl ion per gram for CAAMPS hydrogels. Removal effiency of uranyl ions (RE%) was changed range 9.05–29.92%. The values of partition ratio, (K d ) of uranyl ions was calculated to be 0.10–0.43 for CAAMPS hydrogels.