Investigation of radionuclide <Superscript>63</Superscript>Ni(II) sorption on ZSM-5 zeolite

The sorption of ⁶³Ni(II) from aqueous solution using ZSM-5 zeolite was investigated by batch technique under ambient conditions. ZSM-5 zeolite was characterized by point of zero net proton charge (PZNPC) titration. The sorption was investigated as a function of shaking time, pH, ionic strength, foreign ions, humic acid (HA), fulvic acid (FA) and temperature. The results indicate that the sorption of ⁶³Ni(II) on ZSM-5 zeolite is strongly dependent on pH. The sorption is dependent on ionic strength at low pH, but independent of ionic strength at high pH values. The presence of HA/FA enhances ⁶³Ni(II) sorption at low pH values, whereas reduces ⁶³Ni(II) sorption at high pH values. The sorption isotherms are simulated by Langmuir model very well. The thermodynamic parameters (i.e., ∆H ⁰, ∆S ⁰ and ∆G ⁰) for the sorption of ⁶³Ni(II) are determined from the temperature dependent sorption isotherms at 293.15, 313.15 and 333.15 K, respectively, and the results indicate that the sorption process of ⁶³Ni(II) on ZSM-5 zeolite is spontaneous and endothermic.     

Impact of environmental conditions on the sorption behavior of radionuclide <Superscript>60</Superscript>Co(II) on MnO<Subscript>2</Subscript>

The fate and transport of toxic metal ions and radionuclides in the environment is generally controlled by sorption reactions. The removal of ⁶⁰Co(II) from wastewaters by MnO₂ was studied as a function of various environmental parameters such as shaking time, pH, ionic strength, foreign ions, and humic substances under ambient conditions. The results indicated that the sorption of ⁶⁰Co(II) on MnO₂ was strongly dependent on pH and ionic strength. At low pH, the sorption of ⁶⁰Co(II) was dominated by outer-sphere surface complexation and ion exchange with Na⁺/H⁺ on MnO₂ surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The presence of HA/FA enhances ⁶⁰Co(II) sorption at low pH values, whereas reduces ⁶⁰Co(II) sorption at high pH values. The Langmuir and Freundlich models were used to simulate the sorption isotherms of ⁶⁰Co(II) at three different temperatures of 298.15, 318.15 and 338.15 K. The thermodynamic parameters (ΔH ⁰, ΔS ⁰ and ΔG ⁰) calculated from the temperature dependent sorption isotherms indicated that the sorption process of ⁶⁰Co(II) on MnO₂ was endothermic and spontaneous.     

Effect of pH,ionic strength,foreign ions,humic acid and temperature on sorption of radionuclide <Superscript>60</Superscript>Co(II) on illite

In this article, a series of batch experiments were carried out to investigate the effect of various environmental factors such as contact time, solid content, pH, ionic strength, foreign ions, temperature and coexisting humic acid on the sorption behavior radionuclide ⁶⁰Co(II) on illite. The results indicated that the sorption of Co(II) was strongly dependent on pH, ionic strength and temperature. At low pH, the sorption was dominated by outer-sphere surface complexation and ion exchange on illite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were used to simulate the sorption isotherms at three different temperatures of 303.15, 323.15 and 343.15 K. The thermodynamic data (∆G ⁰, ∆S ⁰, ∆H ⁰) were calculated from the temperature dependent sorption isotherms and the results suggested that the sorption process of Co(II) on illite was an endothermic and spontaneous process. The sorption test revealed that the illite can be as a cost-effective adsorbent suitable for pre-concentration of Co(II) from large volumes of aqueous solutions.     

Study of <Superscript>63</Superscript>Ni(II) sorption on CMC-bound bentonite from aqueous solutions

Bentonite was investigated to remove Ni(II) from aqueous solutions because of its strong sorption ability. Herein, bentonite was modified with sodium carboxymethylcellulose (CMC) and used as an adsorbent to remove Ni(II) from aqueous solutions. The results indicated that CMC-bentonite had higher sorption capacity than bare bentonite in the sorption of Ni(II) from aqueous solutions. Sorption of Ni(II) on CMC-bentonite was mainly dominated by ion exchange or outer-sphere surface complexation at low pH values, but by inner-sphere surface complexation or surface precipitation at high pH values. The thermodynamic data calculated from temperature dependent sorption isotherms indicated that the sorption of Ni(II) to CMC-bentonite hybrids was an spontaneous process and enhanced with increasing temperature.     

PC-controlled radiochemistry system for preparation of no-carrier-added <Superscript>64</Superscript>Cu

A homemade modular PC-controlled radiochemistry system, used to separate the no-carrier-added ⁶⁴Cu from irradiated electroplated solid cyclotron target ⁶⁴Ni layers was developed. Upon irradiation the target layer is dissolved in diluted nitric acid, followed by selective liquid–liquid extraction of the ⁶⁴Cu. The final purification step is achieved making use of an anion exchange column. All the separation procedures can be carried out remote-controlled with a minimized risk of operator errors within less than 2 h, with excellent processing yield (>95%).     

Impact of environmental conditions on sorption of <Superscript>210</Superscript>Pb(II) to NKF-5 zeolite

The sorption of Pb(II) from aqueous solution using NKF-5 zeolite was investigated by batch technique under ambient conditions. The NKF-5 zeolite sample was characterized by using FTIR and X-ray powder diffraction in detail. The sorption of Pb(II) was investigated as a function of pH, ionic strength, foreign ions, and humic substances. The results indicated that the sorption of Pb(II) on NKF-5 zeolite was strongly dependent on pH. The sorption was dependent on ionic strength at low pH, but independent of ionic strength at high pH. At low pH, the sorption of Pb(II) was dominated by outer-sphere surface complexation and ion exchange with H⁺ on NKF-5 zeolite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. From the experimental results, one can conclude that NKF-5 zeolite has good potentialities for cost-effective preconcentration of Pb(II) from large volumes of aqueous solutions.     

Development of [<Superscript>64</Superscript>Cu]-DOTA-anti-CD20 for targeted therapy

Copper-64 was produced as a by-product of ⁵⁵Co via ⁶⁴Ni(p,n)⁶⁴Cu by 15 MeV proton bombardment of ^natNi resulting in a thick target yield of 5.31 MBq/μAh (143.5 μCi/μAh) and a radiochemical separation yield of 95% (radionuclide purity >97% after 25 hours of bombardment). Rituximab was successively labeled with [⁶⁴Cu]-CuCl₂. N-succinimidyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA-NHS) was prepared at 25 °C using DOTA and N-hydroxy succinimide (NHS) in CH₂Cl₂ followed by the addition of 1 ml of a Rituximab pharmaceutical solution. Radiolabeling was performed at 37 °C in 3 hours. Radio thin-layer chromatography showed an overall radiochemical purity of 90–95% at optimized conditions (specific activity=30 GBq/mg, labeling efficacy; 82%) using various chromatography systems. The final isotonic ⁶⁴Cu-DOTA-Rituximab complex was passed through a 0.22 μm filter and checked by gel electrophoresis for radiolysis control. Stability of the final product was checked in the formulation and in presence of human serum at 37 °C.     

Radiochemical separation and quality assessment for the <Superscript>68</Superscript>Zn target based <Superscript>64</Superscript>Cu radioisotope production

The radiochemical separation of the different radionuclides (⁶⁴Cu, ⁶⁷Cu, ⁶⁷Ga, ⁶⁶Ga, ⁵⁶Ni, ⁵⁷Ni, ⁵⁵Co, ⁵⁶Co, ⁵⁷Co, ⁶⁵Zn, ¹⁹⁶Au) induced in the Ni supported Cu substrate — ⁶⁸Zn target system, which was bombarded with the 29.0 MeV proton beam, was performed by ion-exchange chromatography using successive isocratic and/or concentration gradient elution techniques. The overlapped gamma-ray spectrum analysis method was developed to assess the ⁶⁷Ga and ⁶⁷Cu content in the ⁶⁴Cu product and even in the post-⁶⁷Ga production ⁶⁸Zn target solution without the support of radiochemical separation. This method was used for the assessment of ⁶⁴⁺⁶⁷Cu radioisotope separation from ⁶⁷Ga, the quality control of ⁶⁴Cu product and the determination of the ⁶⁸Zn (p,2p)⁶⁷Cu reaction yield. The improvement in the targetry and the optimization of proton beam energy for the ⁶⁸Zn target based ⁶⁴Cu and ⁶⁷Ga production were proposed based on the stopping power and range of the incident proton and on the excitation functions, reaction yields and different radionuclides induced in the target system.     

Solution chemistry effects on sorption behavior of 109Cd(II) on Ca-montmorillonite

The sorption of radiocadmium on Ca-montmorillonite as a function of contact time, pH, ionic strength, foreign ions, humic acid (HA) and fulvic acid (FA) was studied using batch technique. The results demonstrated that the sorption of Cd(II) was dependent on ionic strength at pH < 9, and was independent of ionic strength at pH > 9. Outer-sphere surface complexation and/or ion exchange were the main mechanism of Cd(II) sorption on Ca-montmorillonite at low pH, whereas the sorption at high pH was mainly dominated via inner-sphere surface complexation. The sorption of Cd(II) on Ca-montmorillonite was dependent on foreign ions at low pH values, but was independent of foreign ions at high pH values. A positive effect of HA/FA on Cd(II) sorption was found at low pH values, whereas a negative effect was observed at high pH values. The thermodynamic parameters (i.e., ??H ⁰, ??S ⁰, ??G ⁰) were calculated from the temperature dependent sorption isotherms, and the results indicated that the sorption process of Cd(II) on Ca-montmorillonite was spontaneous and endothermic.     

Preparation and characterization of nickel targets for cyclotron production of <Superscript>64</Superscript>Cu

The reaction route ⁶⁴Ni(p,n)⁶⁴Cu is very popular for the preparation of ⁶⁴Cu because its entrance channel is accessible at low energies and yield of reaction is quite high. However, a high price of the enriched ⁶⁴Ni is a disadvantage of this reaction path; hence, preparation of a chemically pure nickel targets for the production of ⁶⁴Cu using COSTIS (Compact Solid Target Irradiation System) is of a great research interest. In this paper, effects of boric acid, composition of electrolytic bath and electrochemical process conditions on the quality of nickel films deposited on 2 mm thick gold or platinum disc targets were investigated. Chemical purity of the electrodeposited nickel was measured by the Auger electron spectroscopy and the surface quality of targets was studied microscopically (SEM). A SRIM program was used for a thickness target calculation. COSTIS target station was installed at the end of the external beam line of the IBA Cyclone 18/9 cyclotron, and the irradiation surface of target was optimized. The target station has been equipped with Al or Nb window foil in the front of the target to degrade the beam energy to an optimal value.     

Characterisation of a Cu selective resin and its application to the production of <Superscript>64</Superscript>Cu

Cu isotopes (e.g. ⁶⁴Cu) increasingly find use in radiopharmaceutical applications, accordingly fast and reliable methods for the production of these isotopes are needed. The aim of the presented project is the characterization of a Cu selective extraction chromatographic resin for the fast and selective separation of Cu radionuclides, e.g. from irradiated targets. The characterisation of the resin includes the determination of weight distribution factors D _w of Cu, Ni, Zn and other potentially interfering elements and impurities for varying acids and pH values, the influence of macro amounts of Ni and Zn on the extraction of Cu as well as the influence of other potential interferents. Based on the obtained results, a method for the separation of Cu and its purification from irradiated Ni or Zn targets was developed and tested on simulated Ni and Zn targets.     

Factors affecting the sorption behavior of Cs<Superscript>+</Superscript> and Sr<Superscript>2+</Superscript> using biosorbent material

In this study, saw dust has been used as precursor for production of low cost activated carbon using potassium hydroxide (KOH) and steam activation technique. The activated carbon was used to remove Cs⁺ and Sr²⁺ ions from aqueous solutions by batch operation, and the extent of adsorption was investigated as a function of solution pH, temperature, shaking time, and initial concentration. The influence of interfering ions was also investigated. The removal of metal ions was pH dependent and the adsorption capacity reaches its maximum 43% and 61.5% at pH 5.0 and 6.0 for Cs⁺ and Sr²⁺ ions, respectively. Thermodynamic studies showed different behaviours where an endothermic, non-spontaneous process was shown for Cs⁺ while an exothermic, spontaneous process was obtained for Sr²⁺. The kinetic data of both ions was described well by pseudo-second order rate equation. The two equilibrium models (Langmuir and Freundlich) have been also applied. Desorption studies indicated that HCl was the most effective desorbing eluent. The investigated adsorbent showed good results towards cesium and strontium removal from aqueous media that could be a promising method due to its low-cost and good efficiency.     

Selective ion-exchange sorption of K<Superscript>+</Superscript> from aqueous solutions containing Na<Superscript>+</Superscript>-K<Superscript>+</Superscript> mixture on Sn(IV) hydrophosphate

Ion-exchange sorption of K⁺ and Na⁺ from their mixture on X-ray-amorphous and crystalline Sn(IV) hydrophosphates was studied. These sorbents exhibit a high selectivity for K⁺. Amorphous Sn(IV) hydrophosphate can be used for efficient purification of aqueous sodium salt solutions to remove potassium impurity.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 8, 2004, pp. 1275–1278.Original Russian Text Copyright © 2004 by Smirnov, Dimova, Redchenko.     

Production of low and high specific activity <Superscript>64</Superscript>Cu in a reactor

Production of radioactive scandium by irradiating natural titanium metal in Pakistan Research Reactor-1 was evaluated. The production rate of ⁴⁷Sc and other radioactive scandium was estimated. High specific activity ⁴⁷Sc can be produced by irradiating enriched ⁴⁷Ti in sufficient quantities needed for therapeutic applications. A new separation technique based on column chromatography was developed. Neutron irradiated titanium was dissolved in hydrofluoric acid, which was evaporated and taken in distilled water. The resulting solution was loaded on silica gel column. The radioactive scandium comes out first and the inactive titanium is removed with 2 M HCl. More than 95% radioactive scandium was recovered, while chemical impurity of titanium determined by optical emission spectroscopy was less than 0.01 μg/mL in final product.     

Impact of environmental conditions on the sorption behavior of 60Co(II) on illite

In this work, a naturally occurring illite was characterized by using FT-IR and XRD technique to determine its surface functional groups and crystal structure. Sorption of ⁶⁰Co(II) on illite as a function of contact time, pH, ionic strength, foreign ions, humic substances and temperature was studied under ambient condition using batch technique. The results indicated that the sorption of ⁶⁰Co(II) on illite is strongly affected by pH values (2–9) and ionic strength. A positive effect of humic substances on ⁶⁰Co(II) sorption was found at pH < 7.0, whereas a negative effect was observed at pH > 7.0. At low pH, the sorption of ⁶⁰Co(II) was dominated by outer-sphere surface complexation and ion exchange with Na⁺/H⁺ on illite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The Langmuir and Freundlich models were used to simulate the sorption isotherms of ⁶⁰Co(II) at three different temperatures of 298.15, 323.15 and 343.15 K. The thermodynamic parameters (ΔH ⁰, ΔS ⁰ and ΔG ⁰) calculated from the temperature dependent sorption isotherms indicated that the sorption process of ⁶⁰Co(II) on illite was endothermic and spontaneous.     

Measurements of fast neutron capture cross sections on <Superscript>63</Superscript>Cu and <Superscript>186</Superscript>W

Neutron capture cross sections on ⁶³Cu and ¹⁸⁶W were measured by fast neutron activation method at neutron energies from 1 to 2 MeV. Monoenergetic fast neutrons were produced by ³H(p,n)³He reaction. Neutron energy spread by target thickness, which was assumed to be the main factor of neutron energy spread, was estimated to be 1.5% at neutron energy of 2.077 MeV. Neutron capture cross sections on ⁶³Cu and ¹⁸⁶W were calculated by reference comparison method on those of ¹⁹⁷Au(n,γ). Not only statistical errors of gamma-counts from samples but also systematic errors in the counting efficiency for HP Ge detector and the uncertainty of areal density of samples were considered in calculating neutron capture cross section. Estimated neutron capture cross sections on ⁶³Cu and ¹⁸⁶W were also compared with ENDF-6 data.     

Kinetic aspects of the ion-exchange reactions of Cs<Superscript>+</Superscript>, Na<Superscript>+</Superscript>, Sr<Superscript>2+</Superscript>and Eu<Superscript>2+</Superscript> ions on the H<Superscript>+</Superscript> form of chromium hexacyanoferrate(II)

Summary This paper reports the radiochemical study of the ion-exchange of Cs⁺, Na⁺, Sr²⁺ and Eu³⁺ ions with H⁺ by chromium hexacyanoferrate(II) which was prepared in a granular form using a gel method. The slow steps which determine the rate of exchange of these ions are directly proportional to the particle diameter and this is confirmed from the linearity test of Bt vs. t plots at different particle diameters. Boyed’s equation and Reichenberg’s tables were used for evaluating all the kinetic parameters. The results reveal that the effective particle radii are unchanged for both chromium hexacyanoferrate(II) dried at 60 and 120 °C. The obtained data were analyzed using McKay plots and Arrhenius equation and the kinetic and thermodynamic parameters, e.g., effective diffusion coefficient, activation energies and entropies of activation have been evaluated. The mobility of these ions inside the particles of chromium hexacyanoferrate(II) decrease in the order of Eu³⁺>Sr²⁺>Na⁺⊃Cs⁺.     

Structural organization of mercury(II) and copper(II) dithiocarbamates from EPR and <Superscript>13</Superscript>C and <Superscript>15</Superscript>N MAS NMR spectra and X-ray diffraction analysis

The structures and spectroscopic properties of mononuclear and binuclear mercury(II) and copper(II) complexes with four dithiocarbamate ligands R₂NC(S)S^? (R = CH₃, C₂H₅, or iso-C₃H₇; R₂ = (CH₂)₆) were studied by solid-state ¹³C and ¹⁵N CP/MAS NMR and EPR spectroscopy. Mercury(II) N,N-cyclohexamethylenedithiocarbamate [Hg₂{S₂CN(CH₂)₆}₄] was obtained and characterized in detail by X-ray diffraction analysis at 299 K. The binuclear molecule of the complex is centrosymmetric; the central tricyclic fragment [Hg₂S₄C₂] is in the chair conformation. In the ¹³C and ¹⁵N NMR spectra, the signals were assigned to the dithiocarbamate ligands with different structural functions: bidentate chelating and combined (both chelating and bridging) ones. The differences between the isotropic ¹⁵N chemical shifts for the dialkyldithiocarbamate ligands were interpreted in terms of combination of the mesomeric effect of the =NC(S)S-groups and the inductive effect of the alkyl substituents. According to the EPR data, copper(II) in magnetically diluted systems is mainly found in heterobinuclear molecules [CuHg(S₂CNR₂)₄] and the geometry of the chromophores [CuS₅] approximates to a tetragonal pyramid.