Uranyl Sorption

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Bi-functionalization of silica particles increases Sr(II) sorption properties. • Methacrylic (80%)/amidoxime (20%) substitution ratio is optimum. • Maximum sorption capacity reaches 1.57 mmol Sr g −1 at pH 8. • Total Sr(II) desorption and weak loss in sorption properties at the fifth recycling.

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Bi-functionalization of silica particles increases Sr(II) sorption properties. • Methacrylic (80%)/amidoxime (20%) substitution ratio is optimum. • Maximum sorption capacity reaches 1.57 mmol Sr g −1 at pH 8. • Total Sr(II) desorption and weak loss in sorption properties at the fifth recycling.

This study may open a new way to obtain the coloration of a polymer during functionalization. Two polyacrylonitrile (PAN) polymers in the form of textile fibers (Melana and Dralon L) were subjected to functionalization treatments in order to improve the dyeing capacity. The functionalizations determined by an organo-hypervalent iodine reagent developed in situ led to fiber coloration without using dyes. KIO3 was formed in situ from the interaction of aqueous solutions of 3–9% KOH with 3–9% I2, at 120 °C. The yellow-orange coloration appeared as a result of the transformations in the chemical structure of each functionalized polymer, with the formation of iodinehydrin groups. The degree of functionalization directly influenced the obtained color. The results of the Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Map and Temogravimetric Analysis (TG) plus Differential Thermal (DTA) analyses indicated the p...

The Polymers of Intrinsic Microporosity (PIM-1) is considered as one of the most promising polymer candidates for adsorption applications owing to its high surface area and the ability to tailor the functionality for the targeted species. This study reports a facile method for the preparation of amidoxime functionalized PIM-1 fibrous membrane (AF-PIM-FM) by electrospinning technique and its practical use for the extraction of U(VI) ions from aqueous systems via column sorption under continuous flow. Fibrous membrane form of amidoxime functionalized PIM-1 (AF-PIM-FM) was prepared by electrospinning method owing to its excellent processability in dimethylformamide. Bead-free and uniform fibers were obtained as confirmed by SEM imaging and average fiber diameter was 1.69 ± 0.34 μm for AF-PIM-FM. In addition, electrospun PIM-1 fibrous membrane (PIM-FM) was prepared as a control group. Structural and thermal characterization of powder and membrane forms of the materials were performed using FT-IR, 1 H NMR, XPS, Elemental analyses, TGA, and DSC. The porosity of the samples was measured by N 2 sorption isotherms confirming amidoxime PIM-1 still maintain their porosity after functionalization. Amidoxime functionality along with membrane structure makes AF-PIM-FM a promising material for uranyl adsorption. First, a comparison between powder and membrane form of amidoxime functionalized PIM-1 was investigated using batch adsorption process. Although membrane form has shown slightly lower adsorption performance in the batch adsorption process, the advantage of using the membrane in column adsorption processes makes membrane form more feasible for real applications. In addition, amidoxime modification enhanced the uranium adsorption ability of PIM-FM up to 20 times. The effect of initial concentration and pH were investigated along with regeneration of the adsorbents. AF-PIM-FM was successfully used for five adsorption-desorption cycles without having any damage on the fibrous structure.

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Redox polymerization of poly(acrylonitrile-co-acrylic acid) (poly(AN-co-AA)) is performed at 40 °C under N2 gas by varying the ratio of acrylonitrile (AN) and acrylic acid (AA) in the feed. The yield production of poly(acrylonitrile) (PAN) is 73% and poly(AN-co-AA) with a feed ratio of 93:7 is the highest yield (72%). The PAN and poly(AN-co-AA) are further chemically modify with hydroxylamine hydrochloride. The FTIR spectroscopy is used to confirm the copolymerization of poly(AN-co-AA) and chemical modification of poly(AN-co-AA). Elemental microanalysis shows that the overall trend percentage of carbon, hydrogen, and nitrogen for all feed ratios are slightly decreasing as the feed ratio of AA is increasing except for poly(AN-co-AA) 93:7. The SEM images shows that spherical diameter of poly(AN-co-AA) is smaller compared to the PAN and amidoxime (AO)

Removal of toxic metals from aqueous solutions is of high priority in environmental chemistry. Most of the available techniques for this task are considered expensive; however, the adsorption process has been considered the easiest and the cheapest way of removing toxic metals from aqueous solution. The performance of adsorption setup largely depends on the characteristic of adsorbents. One of these characteristic is availability of large surface area. The more the available sites for chelation, the more the amount of metals removed. Therefore, the production of materials of nanoscale is expedient for adsorption purposes. Electrospinning process is one of the technologies that have been employed to produce polyacrylonitrile nanofibres (PAN-nfs). Moreover, PAN-nfs surfaces have also been chemically modified so as to introduce chelating groups such as amine, carboxyl, imines, etc. Here we review PAN-nfs as metal ion adsorbent. With characteristics such as high surface area as well as good mechanical strength, modified PAN-nfs are considered good adsorbents and have been used to remove toxic metals such as cadmium, lead, chromium, mercury, uranium, silver and copper in different ion states from their aqueous solutions. The ease of immobilization of metal-specific ligands on PAN-nfs has been of great interest in selective extraction of metal ions from their aqueous solutions. Also, toxic metals adsorbed on modified PAN-nfs can be recovered through desorption process using acids or bases of various concentrations.

This study may open a new way to obtain the coloration of a polymer during functionalization. Two polyacrylonitrile (PAN) polymers in the form of textile fibers (Melana and Dralon L) were subjected to functionalization treatments in order to improve the dyeing capacity. The functionalizations determined by an organo-hypervalent iodine reagent developed in situ led to fiber coloration without using dyes. KIO3 was formed in situ from the interaction of aqueous solutions of 3–9% KOH with 3–9% I2, at 120 °C. The yellow-orange coloration appeared as a result of the transformations in the chemical structure of each functionalized polymer, with the formation of iodinehydrin groups. The degree of functionalization directly influenced the obtained color. The results of the Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Map and Temogravimetric Analysis (TG) plus Differential Thermal (DTA) analyses indicated the p...

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

" Submicron diameter PAN fibers were successfully prepared by electrospinning. " PAN fiber mat was found to be promising in sorption of U(VI) ions by column method. " The surface of PAN fibers were postfunctionalized by amidoximation reaction. " The surface modification remarkably enhanced U(VI) sorption capacity of PAN fibers.

This study may open a new way to obtain the coloration of a polymer during functionalization. Two polyacrylonitrile (PAN) polymers in the form of textile fibers (Melana and Dralon L) were subjected to functionalization treatments in order to improve the dyeing capacity. The functionalizations determined by an organo-hypervalent iodine reagent developed in situ led to fiber coloration without using dyes. KIO3 was formed in situ from the interaction of aqueous solutions of 3–9% KOH with 3–9% I2, at 120 °C. The yellow-orange coloration appeared as a result of the transformations in the chemical structure of each functionalized polymer, with the formation of iodinehydrin groups. The degree of functionalization directly influenced the obtained color. The results of the Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Map and Temogravimetric Analysis (TG) plus Differential Thermal (DTA) analyses indicated the p...

" Submicron diameter PAN fibers were successfully prepared by electrospinning. " PAN fiber mat was found to be promising in sorption of U(VI) ions by column method. " The surface of PAN fibers were postfunctionalized by amidoximation reaction. " The surface modification remarkably enhanced U(VI) sorption capacity of PAN fibers.

Hexavalent chromium (Cr(VI)) ions are toxic and carcinogenic. Their presence in environmental media such as soil, groundwater, sediment, or surface water, leads to negative impacts on the human health and the environment. Therefore, environmental remediation, consisting in the removal of the chromium ions from aquatic environmental media, is of paramount importance. The present work deals with highlighting the efficient removal of ion chromium (VI) from aqueous solutions using chelating acrylic fibers. Thus, polyacrylonitrile fibers (PAN) were amidoximated, and then used as adsorbent in batch experiments to remove chromium ions from water. Prior to batch adsorption experiments, preliminary FTIR spectroscopy and Scanning Electron Microscopy (SEM) investigations have shown that chemical structure and morphological modifications of the PAN occur as resulting from the fiber amidoximation. Further, the ability of fibers as adsorbent to eliminate Cr (VI) ions from aqueous solutions was as...

This study may open a new way to obtain the coloration of a polymer during functionalization. Two polyacrylonitrile (PAN) polymers in the form of textile fibers (Melana and Dralon L) were subjected to functionalization treatments in order to improve the dyeing capacity. The functionalizations determined by an organo-hypervalent iodine reagent developed in situ led to fiber coloration without using dyes. KIO3 was formed in situ from the interaction of aqueous solutions of 3–9% KOH with 3–9% I2, at 120 °C. The yellow-orange coloration appeared as a result of the transformations in the chemical structure of each functionalized polymer, with the formation of iodinehydrin groups. The degree of functionalization directly influenced the obtained color. The results of the Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Map and Temogravimetric Analysis (TG) plus Differential Thermal (DTA) analyses indicated the p...

Materials 1-Vinylimidazole (Aldrich 99 %) was purified by vacuum distillation. 4,4'-Azobis(4cyanovaleric acid (Aldrich 98 %), poly(4-vinylpyridine) (Aldrich, average M w ~ 160,000 g/mol), 1-allyl bromide (Aldrich 97 %), 2,6-di-tert-butyl-4-methylphenol (BHT) (Aldrich 99 %) and trimethylolpropane tris(3-mercaptopropionate (Aldrich) were received without purification. All solvents used were of analytic degree. Silver dicyanamide was prepared similarly according to

Copolymer membranes were fabricated into DMP and copolymer was treated with HA in aqueous solution at 60-80°C. In the amidoximation process, a part of nitrile groups of copolymer is converted into amidoxime groups. The characterization of virgin and amidoximated acrylic copolymer membranes were carried out by using various techniques as Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, Scanning electron microscope etc. With the amidoximation process various significant changes in the copolymer properties such as functionality, crystallinity, thermal behavior, hydrophilicity, elemental composition and surface morphology were observed.

Removal of toxic metals from aqueous solutions is of high priority in environmental chemistry. Most of the available techniques for this task are considered expensive; however, the adsorption process has been considered the easiest and the cheapest way of removing toxic metals from aqueous solution. The performance of adsorption setup largely depends on the characteristic of adsorbents. One of these characteristic is availability of large surface area. The more the available sites for chelation, the more the amount of metals removed. Therefore, the production of materials of nanoscale is expedient for adsorption purposes. Electrospinning process is one of the technologies that have been employed to produce polyacrylonitrile nanofibres (PAN-nfs). Moreover, PAN-nfs surfaces have also been chemically modified so as to introduce chelating groups such as amine, carboxyl, imines, etc. Here we review PAN-nfs as metal ion adsorbent. With characteristics such as high surface area as well as good mechanical strength, modified PAN-nfs are considered good adsorbents and have been used to remove toxic metals such as cadmium, lead, chromium, mercury, uranium, silver and copper in different ion states from their aqueous solutions. The ease of immobilization of metal-specific ligands on PAN-nfs has been of great interest in selective extraction of metal ions from their aqueous solutions. Also, toxic metals adsorbed on modified PAN-nfs can be recovered through desorption process using acids or bases of various concentrations.

), the predominant aerobic form of uranium, is present in the ocean at a concentration of ∼3.2 parts per 10 9 (13.7 nM); however, the successful enrichment of uranyl from this vast resource has been limited by the high concentrations of metal ions of similar size and charge, which makes it difficult to design a binding motif that is selective for uranyl. Here we report the design and rational development of a uranyl-binding protein using a computational screening process in the initial search for potential uranyl-binding sites. The engineered protein is thermally stable and offers very high affinity and selectivity for uranyl with a K d of 7.4 femtomolar (fM) and >10,000-fold selectivity over other metal ions. We also demonstrated that the uranyl-binding protein can repeatedly sequester 30-60% of the uranyl in synthetic sea water. The chemical strategy employed here may be applied to engineer other selective metal-binding proteins for biotechnology and remediation applications.

The complex formation of uranyl ions (UO 2+ 2 ) with poly(methacrylic acid) (PMAA) was investigated by potentiometric, conductometric, UV-visible, luminescence and FTIR spectroscopic, and thermal analysis methods. The stoichiometric ratio at complexation between polymer and uranyl ions was found to be equal to 2 polymer base units per uranyl ion. FTIR spectra of the PMAA-UO 2+ 2 complex confirmed incorporation of metal ions into the polymer and showed that the electrostatic interactions play a major role in complexation. An increase of emission intensity in luminescence spectra of uranyl ions suggests influence of conformation peculiarity of the poly(methacrylic acid) chain. The thermal degradation of polycomplex starts at lower temperature as compared to pristine PMAA that is due to the lower thermal stability of PMAA-UO 2+ 2 complex.

Practical application of chitosan as a sorbent is limited due to its low sorption rates and insufficient mechanical stability to use in filtering systems. In order to improve the sorption properties the chemical modification with citrate has been performed. The sorption rates and capacities were evaluated by determination of the sorbed heavy metal ion amounts. The heavy metal uptake by chitosan increases with decrease in particle size and introduction of citrate. Citrate also enhances sorption capacity. The quantities of citrate introduced into chitosan determine its sorption behavior. The sorption onto chitosan or chitosan containing small amounts of citrate proceeds according to the pseudo-second order kinetic equation and fits the Freundlich equation under equilibrium conditions. The sorption onto chitosan containing high amounts of citrate (>0.1 mol g -1 ) is more complicated.

Electrospun polystyrene fibres incorporating potassium salts of pyrazole-1-carbodithioate and imidazole-1-carbodithioate were employed as sorbents for heavy metals from aqueous environments. The equilibrating time, initial metal concentrations and sorbent mass for optimal adsorption were 40 min, 5 mg/ℓ and 8 mg, respectively. The optimal pH for metal ion uptake was between 6.3 and 9.0 and was found to be dependent on the basicity of the ligands. Protonation constants for the ligands in aqueous solutions were determined potentiometrically; pK of the imidazole was 6.82 while that of the pyrazole was 3.36. The efficiencies of adsorption and desorption of metals on the imidazolyl-incorporated sorbents were more than 95%, up to the fifth cycle of usage. The limits of quantification were ≤ 0.0145 mg/ℓ for all the metals. Accuracy of the determinations, expressed as relative error between the certified and observed values of certified reference groundwater samples was ≤ 0.2% with relative standard deviations < 3%. Electrospun polystyrene fibres incorporating imidazoles proved to be efficient sorbents for divalent heavy metal ions in aqueous environments as their efficiencies exceeded those of chitosan microspheres, ion-imprinted composites, amino-functionalised mesoporous materials and most of the biomass-based sorbents previously reported on.

Poly(acrylonitrile-co-N-isopropylacrylamide) (p(AN-co-NIPAM)) core–shell hydrogel nanoparticles were synthesized by microemulsion polymerization and their feasibility as a drug carrier was investigated. Highly monodispersed nanoparticles with desired size range – i.e., 50–150 nm – were prepared by adjusting the reaction conditions. The hydrophobic core of the composite which consists primarily of poly(acrylonitrile), can be easily made highly hydrophilic by converting the nitrile groups to the corresponding amidoxime groups. This provides a level of tunability in the hydrophobicity/hydrophilicity balance of the composite nanoparticle. The thermo-responsive feature of the shell was utilized for the release of a model drug, propranolol (PPL). It is shown that the loading/release capacity of nanoparticles was increased almost two-fold by the amidoximation of the core material.

Poly(acrylonitrile-co-N-isopropylacrylamide) (p(AN-co-NIPAM)) coreeshell hydrogel nanoparticles were synthesized by microemulsion polymerization and their feasibility as a drug carrier was investigated. Highly monodispersed nanoparticles with desired size range e i.e., 50e150 nm e were prepared by adjusting the reaction conditions. The hydrophobic core of the composite which consists primarily of poly-(acrylonitrile), can be easily made highly hydrophilic by converting the nitrile groups to the corresponding amidoxime groups. This provides a level of tunability in the hydrophobicity/hydrophilicity balance of the composite nanoparticle. The thermo-responsive feature of the shell was utilized for the release of a model drug, propranolol (PPL). It is shown that the loading/release capacity of nanoparticles was increased almost two-fold by the amidoximation of the core material. Published by Elsevier Ltd.

The applications of chelating fibers are wide ranging and include the separation and preconcentration of rare earth elements, enrichment of uranium from seawater, removal of heavy metal ions from industrial wastes and water, etc. In this study, different amine compounds including hydrazine, hydroxylamine hydrochloride, ethanolamine, ethylene diamine, tetramethylene diamine and diethylene triamine were used to modify commercial acrylic fibers to produce chelating fibers. The chemical and physical changes of modified fibers were investigated using FTIR spectroscopy and mechanical properties measurements. Furthermore, the acrylic micro fibers were electrospun to nanofibers. The nanofibers were modified with diethylene triamine. The ability of the modified micro and nanofibers to remove Cu 2+ ions from aqueous media was determined and compared.

Polyacrylonitrile micro and nano fibers were converted to polyacrylonitrilemonoethanolamine (PAN-MEA) through reaction with ethanolamine. The modified PAN fiber was prepared by conversion nitrile groups into hydroxyle groups using ethanolamine solution with different concentration under refluxing at 91°C. Modified raw acrylic fibers (RAF) with submicrometer diameters ranging from 120 to 300 nm were produced using electrospinning in N,N-dimethyl formamide (DMF). The PAN-MEA micro and nano fibers were examined as chelating material in a series of batch adsorption experiments for removal of Cr (III), Pb (II) and Ni (II) ions. The fiber structure has been investigated by different experimental techniques of characterization such as Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Also, the physical and mechanical properties have been investigated. Nano fibers show more ability to adsorb metal ions than the usual fiber because of high ratio of surface to mass.

), the predominant aerobic form of uranium, is present in the ocean at a concentration of ∼3.2 parts per 10 9 (13.7 nM); however, the successful enrichment of uranyl from this vast resource has been limited by the high concentrations of metal ions of similar size and charge, which makes it difficult to design a binding motif that is selective for uranyl. Here we report the design and rational development of a uranyl-binding protein using a computational screening process in the initial search for potential uranyl-binding sites. The engineered protein is thermally stable and offers very high affinity and selectivity for uranyl with a K d of 7.4 femtomolar (fM) and >10,000-fold selectivity over other metal ions. We also demonstrated that the uranyl-binding protein can repeatedly sequester 30-60% of the uranyl in synthetic sea water. The chemical strategy employed here may be applied to engineer other selective metal-binding proteins for biotechnology and remediation applications.