Application of radiotracer technique to study the ion-isotope exchange reactions using a strongly basic anion-exchange resin duolite A-113

Short-lived radioactive ¹³¹I and ⁸²Br tracers were used to study the kinetics of ion-isotope exchange reaction. The experiments were performed in the temperature range 26.0–43.0°C, ion concentration in solution in the range 0.0025–0.020 M, and amount of labeled ion-exchange resin varying from 0.250 to 1.250 g. For bromide ion-isotope exchange reactions, the calculated values of specific reaction rate, initial rate of bromide ion exchange, and amount of bromide ions exchanged were obtained higher than those for iodide ion-isotope exchange reactions under identical experimental conditions. The observed difference is attributed to the difference in the ionic size of bromide and iodide ions in solution. Published in Russian in Radiokhimiya, 2007, Vol. 49, No. 5, pp. 455–457. The text was submitted by the authors in English.     

Application of radioactive tracer technique to study the kinetics and mechanism of reversible ion-isotope exchange with strongly basic anion-exchange resin Indion-850

The kinetics of reversible bromide ion-isotope exchange with Indion-850 resin was studied in the concentrations range from 0.0025 to 0.100 M and the temperature varied from 27.0 to 48.0°C. Two sets of experiments were performed: exchange of the inactive resin in the bromide form with the bromide solution spiked with ⁸²Br tracer and exchange of the labeled resin with an inactive bromide solution. For both forward and reverse bromide ion-isotope exchange reactions, the rate constants, amount of bromide ions exchanged, and initial rate of bromide ion exchange were calculated. The rate constants of the forward and reverse reactions are essentially equal. In both cases, the amount of bromide ion exchanged and the initial rate of bromide ion exchange increase with temperature. Published in Russian in Radiokhimiya, 2008, Vol. 50, No. 6, pp. 555–557. The test was submitted by the authors in English.     

Application of radioactive tracer technique to study the kinetics of iodide ion-isotope exchange with strongly basic anion-exchange resin Duolite A-116

The kinetics of iodide ion-isotope exchange with strongly basic anion-exchange resin Duolite A-116 was studied. The temperature was varied from 25.0 to 40.0°C, and the iodide ion concentration in solution, from 0.0025 to 0.020 M. Two sets of experiments were performed: exchange of the inactive resin in the iodide form with an iodide solution spiked with ¹³¹I and exchange of the labeled resin with an inactive iodide solution. In both cases, the rate constants, amounts of iodide ions exchanged, and initial rate of iodide ion exchange were calculated. For both forward and reverse exchange, the rate constants are essentially similar. Published in Russian in Radiokhimiya, 2008, Vol. 50, No. 6, pp. 558–560. The test was submitted by the authors in English.     

Kinetics of bromide ion-isotope exchange with weakly basic macroporous resin Indion-860

Kinetics of bromide ion-isotope exchange with weakly basic macroporous resin Indion-860 was studied. Two sets of experiments were performed. In the first set, inactive ion-exchange resin samples in the bromide form were equilibrated with a radioactive bromide solution spiked with ⁸²Br tracer, and in the second set of experiments, labeled radioactive ion-exchange resin samples in the bromide form were equilibrated with an inactive bromide solution. The temperature was varied from 25.0 to 40.0°C, and the concentration of bromide ions in solution, from 0.005 to 0.100 M. In separate experiments, performed at a fixed temperature of 25.0°C using 0.0100 M bromide ion solution, the amount of the labeled radioactive ion-exchange resin was varied from 0.250 to 1.000 g. Essentially similar rate constants were obtained for the forward and reverse reactions. Published in Russian in Radiokhimiya, 2008, Vol. 50, No. 6, pp. 551–554. The test was submitted by the authors in English.     

Preparation and properties of modified spherically granulated chitosan for sorption of <Superscript>137</Superscript>Cs from solutions

A composite sorbent based on spherically granulated chitosan modified with a mixed ferrocyanide K₂Cu₃[Fe(CN₆)]₂ (SGC-FC) was prepared. The sorbent is highly effective toward ¹³⁷Cs. The physicochemical parameters of ¹³⁷Cs⁺ sorption by this sorbent were determined: total and equilibrium static exchange capacity, dynamic exchange capacity, sorption equilibrium constants, etc. The influence of the chemical composition of the solution on the ¹³⁷Cs⁺ sorption by SGC-FC was examined in detail. Based on the calculated value of the dimensionless Biot number Bi, a conclusion was made that the kinetics of ¹³⁷Cs⁺ sorption on SGC-FC is mainly determined by external diffusion of ¹³⁷Cs⁺ ions to reaction centers of the sorbent. The possibility of using the sorbent in monitoring of sea areas was considered.     

Optimization of CdO nanoparticles by Zr<Superscript>4+</Superscript> doping for better photocatalytic activity

Chemically controlled co-precipitation method has been adopted for the fabrication of pure and different wt% Zr doped CdO photocatalysts. Conventionally, the crystallite size and crystalline phase of CdO are in the midst of the parameters involved in the control of the photocatalytic activity. Aiming utterly at the size effect that modifies other attributes which are important to assess the photocatalytic activity of nanometric CdO, it was explored to synthesize CdO nanoparticles with controlled size, highly comparable morphology and analogous phase. The crystal structure and the crystallite size were estimated from the X-ray diffraction patterns and were confirmed through transmission electron microscope. The degree of crystallinity varied on Zr doping and the calculated crystallite sizes were in the range of 16–81 nm. The dopant ion Zr⁴⁺ have been detected through X-ray photoelectron spectroscopy (XPS) analysis signifying the dopant to substitute for cadmium (Cd²⁺) in the lattice of CdO. Particle size dependent optical band gaps calculated in the range 2.02–2.57 eV informed the viability of the materials to initiate photocatalytic reaction in the visible light region. Lesser recombination rate of the generated electrons and holes under light irradiation produced low intense photoluminescence peaks that displayed the appropriateness as photocatalysts. Zr⁴⁺ doping resulted in the enhancement of photocatalytic activity, evaluated by monitoring the degradation of methylene blue solution. 0.5 wt% Zr doped CdO nanoarticles calcined at 400 °C exhibited the highest photocatalytic activity with better percentage of color abatement (80.95%). The pseudo-first-order reaction rate became faster on Zr doping such that the rate constant is ~?0.4–0.5 h^?1 for Zr doped CdO while that for pure CdO is ~?0.3 h^?1.     

<Superscript>211</Superscript>At-Rh(16-S4-diol) as a starting complex for preparing an astatine-labeled radiopharmaceutical

A new procedure for preparing an ²¹¹At-labeled radiopharmaceutical is suggested. The ²¹¹At^? anion forms a strong bond with the Rh³⁺ cation incorporated in the complex with a thiother ligand, 1,5,9,13-tetrathiacyclohexadecane-3,11-diol (16-S4-diol). The reaction conditions are optimized with ¹³¹I as astatine analog. The complexes are studied by paper electrophoresis, ion exchange, and thin-layer chromatography. The kinetics of the addition of the ¹³¹I^? anion to Rh(16-S4-diol) and the dependence of the yield of the forming complex ¹³¹I-Rh(16-S4-diol) on the temperature, solution acidity, and reactant concentrations are examined. Taking into account the results obtained, the complex ²¹¹At-Rh(16-S4-diol) is prepared by adding astatide (²¹¹ At^?) to equivalent amounts of RhCl₃ and the tetrathioether (16-S4-diol). the behavior of the astatine complex is studied.     

Near-infrared downconversion in Ce<Superscript>3+</Superscript>–Yb<Superscript>3+</Superscript> co-doped YAG

The phosphors YAG co-doped with Ce³⁺–Yb³⁺ ion pair were successfully synthesized by solid state reaction method varying the concentration of Yb³⁺ ions from 1 to 15 % mol. The phosphors were characterized by powder X-ray powder diffraction and surface morphology was studied by scanning electronic microscope. The photoluminescence (PL) properties were studied by spectrophotometers in near infra red (NIR) and ultra violet visible region. The synthesized phosphors can convert a photon of blue region (469 nm) into photons of NIR region (979 and 992 nm). The co-operative energy transfer was studied by time decay curve and PL spectra. The theoretical value of quantum efficiency was calculated from steady time decay measurement and the maximum efficiency approached up to 145.19 %. Hence this phosphor could be used as a downconversion luminescent convertor in front of crystalline silicon solar cell (c-Si) panels to reduce thermalization loss due to spectral mismatch of the solar cells.     

Using computer simulation techniques to design a tellurium-123 target for <Superscript>123</Superscript>I production

The production of ¹²³I from ¹²³Te by the ^l23Te(p, n)¹²³I reaction at various target enrichments (99.9, 91, 85.4, and 70.1%) was simulated using ALICE and SRIM programs. The ¹²³I production feasibility by the above reaction was evaluated. The calculations give more accurate results for proton beam energy of less than 30 MeV. The cross sections of all tellurium reactions with proton were calculated at 0–30 MeV proton beam energy with ALICE program, and the yield of ¹²³I was calculated by analytical methods. Our prediction for ¹²³I production via bombardment of ¹²³Te (99.9%) with a proton beam energy of 5–15 MeV is about 7.2 mCi μA⁻¹ h⁻¹. Published in Russian in Radiokhimiya, 2008, Vol. 50, No. 5, pp. 460–463. The text was submitted by the authors in English.     

A modified electrochemical procedure for isolating <Superscript>177</Superscript>Lu radionuclide

A cell for isolating ¹⁷⁷Lu from a neutron-irradiated ¹⁷⁶Yb target was developed. The procedure involves a combination of two processes: contact reduction of Yb from acetate–chloride solution on sodium amalgam, followed by electrolysis of the solution on a mercury cathode. The process conditions were chosen so that the adjustment of the working solution characteristics (composition, pH, etc.) in going from contact reduction to electrolysis was not required. Both processes are performed in one cell, which reduces the ¹⁷⁷Lu loss. On an installation consisting of two cells, the decontamination factor of the ¹⁷⁷Lu solution from Yb of up to 10⁶ was reached, which is necessary for obtaining a ¹⁷⁷Lu preparation of high specific activity.     

Preclinical evaluation of <Superscript>99<Emphasis Type="Italic">m</Emphasis> </Superscript>Tc-histidine as a possible tumor imaging agent

Radiolabeling of histidine (Hist), an essential amino acid, with ^99mTc was performed. The radiochemical yield higher than 95% was achieved with stannous chloride as a reducing agent. Factors affecting the radiochemical yield (histidine amount, stannous chloride amount, reaction time, pH of the reaction mixture) were studied in detail, and the reaction conditions were optimized. In vitro stability of the radiolabeled complex was checked, and it was found to be stable for up to 6 h. ^99mTc-Hist was injected intravenously into normal and tumor-bearing mice. Biodistribution studies revealed that the ^99mTc-Hist uptake in tumor sites was 10 and 16% ID/g in ascites and 7 and 9.2% ID/g in thigh solid tumor at 60 and 120 min post injection, respectively. The amount of ^99mTc-Hist in ascites and solid tumor increased with time and then decreased slowly. Thus, ^99mTc-Hist can be used as a potential agent for imaging tumor sites.     

The study of various parameters affecting the ion exchange of Cu2+, Zn2+, Ni2+, Cd2+, and Pb2+ from aqueous solution on Dowex 50W synthetic resin

A gel resin containing sulfonate groups (Dowex 50W) was investigated for its sorption properties towards copper, zinc, nickel, cadmium and lead metal ions. The use of selective ion exchange to recover metals from aqueous solution has been studied. The ion exchange behavior of five metals on Dowex 50W, depending on pH, temperature, and contact time and adsorbate amount was studied. Experimental measurements have been made on the batch sorption of toxic metals from aqueous solutions using cation exchanger Dowex 50W. The maximum recoveries (about 97%) Cu(2+), Zn(2+), Ni(2+), Cd(2+) and (about 80%) Pb(2+) were found at pH ranges 8-9. The amount of sorbed metal ion was calculated as 4.1, 4.6, 4.7, 4.8, and 4.7mequiv./gram dry resin for Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+), respectively. The precision of the method was examined at under optimum conditions. Selectivity increased in the series: Pb>Cd>Cu>Zn>Ni. It has been observed that, selectivity of the -SO(3)H group of the resin increases with atomic number, valance, degree of ionization of the exchanged metals. The equilibrium ion exchange capacity of resin for metal ions was measured and explored by using Freundlich and Langmuir isotherms. Langmuir type sorption isotherm was suitable for equilibrium studies.     

Remarkable anodic performance of lead titanate 1D nanostructures via <Emphasis Type="Italic">in-situ</Emphasis> irreversible formation of abundant Ti<Superscript>3+</Superscript> as conduction pathways

PX-phase PbTiO₃ (PT) nanowires with open channels running along the length direction have been investigated as an anode material for lithium ion batteries. This material shows a stabilized reversible specific capacity of about 410 mAh·g^–1 up to 200 cycles with a charge/discharge voltage plateau of around 0.3–0.65 V. In addition, it exhibits superior high-rate performance, with 90% and 77% capacity retention observed at 1 and 2 A·g^–1, respectively. At a very high current rate of 10 A·g^–1, a specific capacity of over 170 mAh·g^–1 is retained up to 100 cycles, significantly outperforming the rate capability reported for Pb and Pb oxides. The results of X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses along with the cyclic voltammogram results reveal that the PX-phase PT nanowires undergo irreversible structural amorphization and reduction reactions during the initial cycle, which allow them to transform into a composite structure composed of 2–5 nm Pb nanoparticles uniformly dispersed in the 1D amorphous Li₂O·TiO₂·LiTiO₂ matrix. In this composite structure, the presence of abundant amounts of Ti³⁺ in both the charged and discharged states enhances the electrical conductance of the system, whereas the presence of ultrafine Pb nanoparticles imparts high reversible capacity. The structurally stable TiO₂-based amorphous matrix can also considerably buffer the volume variation during the charge/discharge process, thereby facilitating extremely stable cycling performance. This compound combines the high specific capacity of Pb-based materials and the good rate capability of Ti³⁺-based wiring. Our results might furnish a possible route for achieving superior cycling and rate performance and contribute towards the search for next-generation anode materials.

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A comparative study of chelating and cationic ion exchange resins for the removal of palladium(II) complexes from acidic chloride media

The increasing demand for palladium for technological application requires the development of ion exchange chromatography. Recently ion exchange chromatography has developed largely as a result of new types of ion exchangers available on the market of which two types are widely applied. One of them are selective (chelating) and modified ion exchangers and the other one are liquid exchangers. Two types of ion exchange resins such as chelating (Lewatit TP 214, Purolite S 920) and cationic (Chelite S, Duolite GT 73) ion exchangers are used for the recovery of palladium(II) complexes from chloride media (0.1-2.0M HCl-1.0M NaCl-0.0011 M Pd(II); 0.1-2.0M HCl-2.0M NaCl-0.0011M Pd(II)). The influence of concentration of hydrochloric acid, sodium chloride as well as the phase contact time on the degree of recovery of palladium(II) complexes was studied. Moreover, the amount of palladium(II) chlorocomplexes sorbed onto ion exchangers, the working ion exchange capacities and the weight and bed distribution coefficients were calculated in order to judge which of two types of resins possesses the best performance towards palladium(II) complexes.     

A study of ion-exchange behavior of Pb in dilute HBr solutions,aimed to evaluate the possibility of on-line isolation of element 114. <Superscript>228</Superscript>Ra-<Superscript>212</Superscript>Pb generator

Ion-exchange behavior of Pb (homolog of element 114), Ra, some actinides and Hf (homolog of Rf) in aqueous and aqueous-methanolic solutions of HBr was studied as influenced by the solution composition, acid concentration, type of ion exchanger, and other factors. The best conditions for Pb separation from other radionuclides with a high decontamination factor (≥10⁵?10⁶) on a cation exchanger and the conditions for its preconcentration from dilute solutions on an anion exchanger in the continuous (on-line) mode were determined. Based on the operation principle of a radioisotope generator containing a cation exchanger and HBr solutions, an efficient procedure for repeated separation of ²¹²Pb (T _1/2 = 10.6 h) from its parent radionuclides (²²⁸Ra, ²²⁸Ac, and ²²⁸Th) was developed. The possibility of on-line isolation of element 114 formed by the ²⁴²Pu(⁴⁸Ca, 3n) nuclear reaction and its detection by long-lived decay product [²⁶⁷Rf (T _1/2 ～ 3.3 h)] was demonstrated.     

Synthesis of polyacrylate/polyethylene glycol interpenetrating network hydrogel and its sorption for Fe<Superscript>3+</Superscript> ion

A simple two-step aqueous polymerization method was introduced to synthesize polyacrylate/polyethylene glycol (PAC/PEG) interpenetrating network (IPN) hydrogel. The sorption behaviors and mechanism were studied by the sorption of PAC/PEG IPN hydrogel to Fe³⁺ ion from aqueous solution. The experimental results revealed that the adsoption amount of Fe³⁺ ion using swollen hydrogels was much higher than that using the dried composite, they were 75.69 mg/g and 14.25 mg/g, respectively. The parameters, such as neutralization degree, acrylic acid (AA) dosages and temperature, on the sorption amount of PAC/PEG IPN hydrogel were detailedly investigated.     

A high-performance supercapacitor electrode based on three-dimensional poly-rowed copper hydroxide nanorods on copper foam

Three-dimensional (3D) poly-rowed copper hydroxide [Cu(OH)₂] nanorods nanostructures have been synthesized on copper foam slices, using copper foam as copper source, current collector and 3D substrate, through a facile and scalable one-step anodization method. The synthesized products can be directly used as binder free electrodes of supercapacitors. The synthesized material exhibited a 3D connect and quasi connect network structure which can facilitate ion mobility and increase the amount of active sites for redox reactions. These merits together lead to a high areal specific capacitance of 1.889 F cm^?2 at a scan rate of 2 mV s^?1, excellent rate capability (75.39% retention upon increasing the current density by 15 times), low intrinsic resistance (0.792 Ω cm^?2) and good cycling stability (87.23% capacitance retention after 5000 cycles), demonstrating a good potential for high performance energy storage devices applications.     

Characterization of soft magnetic nano-material deposited with M<Superscript>3</Superscript>D technology

Direct Write Technologies are being utilized in antennas, engineered structures, sensors, and tissue engineering. One form of Direct Write Technology is Maskless Mesoscale Material Deposition (M³D). The M³D process is a process that uses aerosol formation, transport and deposition. Inks for the M³D process utilize nano-particles in suspension for deposition. Soft magnetic material was formulated as an ink suspension, deposited and characterized. This paper will report on the results obtained after depositing the soft magnetic material. The results of the permeability are calculated from magnetic structures created with the deposition. These results are compared to conventional methods of soft magnetic material formation and construction.     

Leaching of<Superscript>60</Superscript>Co and<Superscript>137</Superscript>Cs from spent ion exchange resins in cement-bentonite clay matrix

The leaching rate of⁶⁰Co and¹³⁷Cs from the spent cation exchange resins in cement-bentonite matrix has been studied. The solidification matrix was a standard Portland cement mixed with 290–350 (kg/m³) spent cation exchange resins, with or without 2–5% of bentonite clay. The leaching rates from the cementbentonite matrix for⁶⁰Co : (4,2–7,0) × 10⁻⁵ (cm/d) and¹³⁷Cs : (3,2–6,6) × 10⁻⁴ (cm/d), after 125 days were measured. From the leaching data the apparent diffusivity of cobalt and cesium in cement-bentonite clay matrix with a waste load of 290–350 (kg/m³) spent cation exchange resins, was measured for⁶⁰Co : (1,1−4,0) × 10⁻⁶ (cm²/d) and¹³⁷Cs : (0,5–2,6) x× 10⁻⁴ (cm²/d), after 125 days. The results presented in this paper are part of the results obtained in a 20-year mortar and concrete testing project which will influence the design of radio-active waste management for a future Serbian radioactive waste disposal centre.