Simultaneous production and separation of no-carrier-added 111In, 109Cd from alpha particle induced silver target

A natural silver foil was bombarded by 30 MeV α-particles which produced ¹¹¹In, ¹⁰⁹Cd and ^106mAg in the target matrix. ¹¹¹In and ¹⁰⁹Cd were separated from the Ag target matrix employing ion-exchange chromatography and liquid–liquid extraction (LLX). In the chromatographic separation, the active solution containing the NCA products were adsorbed in the column containing Dowex 50 and were eluted with HNO₃. Bulk silver and ¹⁰⁹Cd were sequentially eluted with 1 M HNO₃. After complete elution of ¹⁰⁹Cd and the bulk, ¹¹¹In was eluted with 1.5 M HNO₃. In the LLX, the NCA ¹¹¹In was extracted to 1 % HDEHP (di-2(ethylhexyl)phosphoric acid) from 10^?2 M HNO₃ solution, leaving cadmium and bulk silver quantitatively in the aqueous phase. The NCA ¹⁰⁹Cd was separated from the bulk Ag by precipitating Ag as AgCl. NCA ¹¹¹In was stripped back quantitatively from HDEHP phase using 8 M HNO₃.     

Separation of no-carrier-added 109Cd from natural silver target using RTIL 1-butyl-3-methylimidazolium hexafluorophosphate

The room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate [C₄mim][PF₆] has various applications in the separation of a range of metal ions replacing volatile and toxic traditional organic solvents in liquid–liquid extraction systems. In this study, the RTIL [C₄mim][PF₆] was used to separate no-carrier-added (NCA) ¹⁰⁹Cd from α-particle irradiated Ag target. A natural Ag foil was bombarded by 30 MeV α-particles to produce ¹⁰⁹Cd. After the decay of all co-produced short-lived products, NCA ¹⁰⁹Cd was separated from the bulk Ag using [C₄mim][PF₆] as extractant from HNO₃ medium. Ammoniumpyrrolidine dithiocarbamate (APDC) was used as a complexing agent. At the optimum condition, 3 M HNO₃, 0.01 M APDC in presence of [C₄mim][PF₆], ~99 % bulk Ag was extracted to the IL phase, leaving NCA ¹⁰⁹Cd in the aqueous phase. The amount of Ag became negligibly small after re-extraction in the same condition. The ionic liquid was recovered by washing it with 1 M HCl.     

Radiochemical separation of 109Cd from a silver target

A radiochemical separation method was developed for the separation of ¹⁰⁹Cd from a ^nat.Ag target (6.6 g, pressed into a 19 mm disc). The method comprised of two stages. In the first stage, after dissolution of the target in nitric acid, silver was separated from Cd by precipitation into the metallic form using 20 g of Cu turnings for the reduction of Ag⁺ ions. In the second stage, ¹⁰⁹Cd in the filtrate, that contained trace amount of silver and substantial quantity of Cu(I), was purified by use of a Bio-Rad AG1-X10 anion-exchange resin. The ion-exchange chromatography employed a column with (1.6 cm i.d. and 4 cm length) with a flow rate of 2 ml/min throughout the separation. ¹⁰⁹Cd was quantitatively recovered from the first stage and the recovery yield from the ion-exchange chromatography was greater than 96%. 2M HCl containing H₂O₂ was used for the adsorption of ¹⁰⁹Cd and elution of Cu. ¹⁰⁹Cd was eluted by 50 ml 1M HNO₃. The concentrations of stable isotopes of Ag and Cu in the final solution (5 ml 0.05M HCl) were measured by an ICP-OES method and found to be <1 ppm.     

Ionic liquid-salt based aqueous biphasic system for separation of 109Cd from silver target

Aqueous biphasic system (ABS) is greener alternative to the conventional liquid liquid extraction as ABS does not involve any organic or volatile reagents. Generally ABS systems are composed of polymer and salt rich phases. In this paper a new ABS system is proposed replacing polymer rich phase by water soluble room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium Chloride ([bmim]Cl) and kosmotropic salt K₂HPO₄. The system has been applied to separate the no-carrier-added (NCA) ¹⁰⁹Cd (T _1/2 = 462.6 days) from the α-particle irradiated bulk Ag target. The optimum separation condition was achieved with the addition of 6 M HNO₃ to the ABS, where ~87 % of the bulk Ag was extracted in the IL phase, leaving ~96 % NCA ¹⁰⁹Cd in the salt rich phase. The salt rich phase was re-extracted twice with the RTIL to free from bulk Ag. This process achieved an overall separation of 91 % NCA ¹⁰⁹Cd free from bulk Ag. The developed method demonstrates minimum requirement of RTIL to carry out the separation. The method is environmentally benign and cost effective.     

Sorption behavior of hydroxyapatite for 109Cd(II) as a function of environmental conditions

In this work, hydroxyapatite (HAP) was prepared by aqueous precipitation technique and was characterized by using FT-IR to determine its chemical functional groups. A series of batch experiments were carried out to investigate the effect of various environmental factors such as contact time, pH, ionic strength, foreign ions, fulvic acid (FA) and temperature on the sorption behavior of HAP towards radionuclide ¹⁰⁹Cd(II). The results indicated that the sorption of ¹⁰⁹Cd(II) on HAP was strongly dependent on pH and ionic strength. A positive effect of FA on ¹⁰⁹Cd(II) sorption was found at pH <7.0, whereas a negative effect was observed at pH >7.0. The Langmuir, Freundlich and D-R models were used to simulate the sorption isotherms at three different temperatures of 298.15, 323.15 and 343.15 K. The thermodynamic parameters (ΔH⁰, ΔS⁰ and ΔG⁰) calculated from the temperature dependent sorption isotherms indicated that the sorption process of ¹⁰⁹Cd(II) on HAP was spontaneous and endothermic. At low pH, the sorption of ¹⁰⁹Cd(II) was dominated by outer-sphere surface complexation and ion exchange on HAP surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. From the experimental results, it is possible to conclude that HAP has good potentialities for cost-effective treatments of ¹⁰⁹Cd(II)-contaminated wastewaters.     

Separation of the no-carrier-added 109Cd from Ag, Cu and 65Zn by use of a precipitation and AG1-X8 resin

The ¹⁰⁹Cd radionuclide was produced in the cyclotron via ^natAg(p,n)¹⁰⁹Cd reaction. The radiochemical separation of ¹⁰⁹Cd from silver and non-isotopic impurities comprised of two stages. The optimum conditions of the ¹⁰⁹Cd separation methods were: Ag precipitation with 0.015 M HCl and Cu and ⁶⁵Zn by use of 0.015 M HCl on AG1-X8 strong anion-exchange resin. Chemical and radionuclidic purity of ¹⁰⁹Cd were measured by ICP-AES and gamma-ray spectrometry respectively. Recovery yield and radionuclidic purity were obtained 99.7% and 99%, respectively.     

Synthesis of maghemite nano-particles and its application as radionuclidic adsorbant to purify <Superscript>109</Superscript>Cd radionuclide

Maghemite nano-particles were synthesized by a solid-state chemical reaction for its highly selective use as, cyclotron-produced, ¹⁰⁹Cd (462.9 days) purification method of choice. ¹⁰⁹Cd radiochemical separation starts with Ag activities precipitated with HCl 0.0015 M followed by, on a second step, ¹⁰⁹Cd separation from Cu carrier and ⁶⁵Zn (243.8 days) using Ca (NO₃)₂ 0.01 M. Experimental parameters such, pH and sorbent concentration, on ¹⁰⁹Cd extraction efficiency were investigated. Phase morphology, nanostructure and size of nano-particles were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A 10–20 nm average grain size was derived from XRD line broadening and SEM data. Heat treatment on Fe³⁺:Fe²⁺ ratios equal to 2:1, produced powders, resulting in tetragonal (maghemite) structure at 300 °C and rhombohedra (hematite) at 600 °C. ¹⁰⁹Cd chemical and radionuclidic purity were determined by ICP-AES and HPGe detector gamma-ray spectrometry. The overall recovery and radionuclide purity were 80.0% from obtained 129.63 kBq/C MeV (70 kBq/μAh) initial activity and 91.4%, respectively.     

Potential use of tungstocerate matrices on the separation of <Superscript>113m</Superscript>In from <Superscript>110m</Superscript>Ag relevant to the separation of the cyclotron-produced <Superscript>111</Superscript>In from its silver target

A procedure for separation of no-carrier-added ^113mIn(III) radioisotope from a bulk of ^110mAg has been developed. The sorption behavior of ^113mIn(III) and ^110mAg(I) ions in HNO₃ acid solutions on different tungstocerate matrices showed high affinity of ^110mAg(I) ions towards tungstocerate(IV) gel matrices compared with ^113mIn(III) ions. No-carrier-added ^113mIn radionuclide was separated from ^110mAg on 12-tungstocerate(IV) column matrix. 11 mL 0.3M HNO₃ acid solution was enough for eluting the ^113mIn from the column bed. ^110mAg was recovered from the column by eluting the column bed with 12 mL 2M HNO₃ acid solution.     

The production of 103Pd and 109Cd from a proton irradiated tandem natAg/natAg targets

This paper describes a new method for the production of ¹⁰³Pd and ¹⁰⁹Cd using the 66 MeV proton beam of iThemba LABS on a tandem natural silver target (Ag/Ag). The radiochemical separation of the Pd radionuclides (¹⁰³Pd, ¹⁰⁰Pd) from the bulk ^natAg was done using a Chelex-100 chelating resin column. The recovery of ¹⁰³Pd from the irradiated ^natAg target was found to be >98 % without any Ag or Rh impurities detected. The radiochemical separation of ¹⁰⁹Cd from the bulk ^natAg target was done by the precipitation of Ag ions by Cu followed by the separation of ¹⁰⁹Cd, traces of Ag, Cu²⁺ and Rh using a AG1-X10 anion exchange resin column. The recovery yield of ¹⁰⁹Cd was >99 % without any Ag or Rh impurities detected.     

Cadmium-109 sources for trace analysis by X-ray fluorescence

Procedures for preparing¹⁰⁹Cd sources suitable for use in trace-element analysis by the X-ray fluorescence method were investigated. Sources were prepared from¹⁰⁹Cd in a 0.1N HCl solution by three different techniques: (a) electrodeposition of¹⁰⁹Cd onto a silver plate, which was then enclosed in a silver housing; (b) electrodeposition onto a lead foil, enclosed in a lead housing; (c) sorption of the¹⁰⁹Cd on a Permutit anionic exchange membrane, which was then enclosed in a silver housing. Using identical test conditions, the best results were obtained with the last-mentioned source, which was used successfully for the determination of Br and Pb in organic materials at concentration levels of ppm.     

Effect of environmental conditions on 109Cd(II) sorption to MnO2

The sorption of Cd(II) from aqueous solution on MnO₂ was investigated under ambient conditions. Experiments were carried out as a function of contact time, solid content, pH, ionic strength, foreign ions, fulvic acid and temperature. The results indicated that the sorption of Cd(II) was strongly dependent on pH and ionic strength. At low pH, the sorption of Cd(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 Langmuir, Freundlich and Dubinin–Radushkevich models were used to simulate the sorption isotherms at three different temperatures. The thermodynamic data (ΔG ⁰, ΔS ⁰, ΔH ⁰) calculated from the temperature dependent sorption isotherms suggested that the sorption of Cd(II) on MnO₂ was an spontaneous and endothermic process.     

Study of the stereochemistry of silver(I) bis(pyridine-2-carbaldehyde-imine) triflate complexes in solution: application of inept 109Ag and 1H-{109Ag}NMR

[Ag^IL₂](O₃SCF₃) complexes have been obtained from the $\text{2}\text{1}$ reaction of pyridine-2-carbaldehyde-imine (L) with AgO₃SCF₃. Inept ¹⁰⁹Ag and ¹H-{¹⁰⁹Ag} NMR studies of [Ag{(S)(6-Me-2-C₅H₃N)C(H)=NC(H)PhMe}₂](O₃SCF₃) reveal that the tetrahedral Ag^IL₂ cation of this complex exists below 235 K in two diastereoisomeric forms with a strong preference for one of the molecular configurations (probably the A(S)(S)).     

Composite ion exchanger for removal of sodium-24 from mineralizates of biological materials in neutron activation analysis

A composite ion exchanger containing hydrated antimony pentoxide (HAP) in polystyrene-divinylbenzene matrix has been prepared. Its sorption properties with respect to Na, As, Au, Cd, Cu, Ga, Hg, In, K, La, Mn, Mo (Tc), Pd, Pt, Sb, W and Zn have been examined. Sodium is quantitatively retained on the sorbent from 8M HCl solution as well as from a mixture of conc. H₂SO₄+ conc. HNO₃+H₂O (1+1+2). As, W, Cd and Sb are partially retained, while the remaining elements are not retained and can be quantitatively eluted. The composite ion exchanger is stable to oxidizing acid media and it can be directly applied to separation of²⁴Na from mineralizates of neutron-irradiated biological materials.     

Liquid scintillation and Cherenkov counting characteristics of109Cd

When¹⁰⁹Cd is placed in a liquid scintillation counter, 146±1 counts are obtained for every 100¹⁰⁹Cd nuclides which undergo decay. Thus, the average efficiency for each of the two steps in the decay process is 73%. In examining the distribution of energy among the windows available, it was noted that the distribution pattern is quite similar to that of¹⁴C. An average Cherenkov counting efficiency, in water, was found to be 0.0258±0.0005%. Both 0.010M K₂Cr₂O₇ and CHCl₃ quench the count rate, particularly in the lower energy channel, where count rates are suppressed by up to a factor of 20.     

Determination of palladium by chemical neutron activation analysis using low energy photon spectrometry

A chemical neutron activation analysis method to determine trace amounts of palladium present in the uranium ores has been developed. Palladium was concentrated on an anionic exchanger to purify from large amounts of uranium, iron and copper that were present in the ore. The resin in which Pd was adsorbed was neutron irradiated and the activation product¹⁰⁹Pd was assayed through its daughter^109mAg by low energy photon spectrometry to estimate palladium. Both the 88 keV gamma-line and the 22 keV X-ray line (arising out of the internal transition of^109mAg) were used to arrive at the concentration values by a standard comparison technique. A thin window Si(Li) detector and an HPGe detector were used for the radioactive assay. Detection limits and the advantage of using the X-ray line of Ag over that of the gamma-line were discussed. An absolute detection limit of 0.12·10⁻⁹ g could be arrived at by the use of the 22.10 keV X-ray line in an interference-free condition.     

Simultaneous purification of sewage from Cd(II) and nonionic surfactant with cation exchanger

The sorption of nonionic surfactant (alkylmonoethers ALM-10), taking place simultaneously with the sorption of Cd(II) in H-form of polyacrylic cation exchangers KB-2 and KB-2-12P was investigated. Increasing the sorption of surfactant the decrease in both the stability of Cd(II) complex with cation exchanger and the equilibrium sorption of Cd(II) was observed. The isotherms of the sorption were measured; the coefficients of intraparticle diffusion (D) were calculated. The integration of the filter filled with polyacrylic cation exchanger into the system of sewage purification is suggested.     

Cation exchange selectivity of some fission products on strongly acidic cation exchanger of sulfonic acid type-nitric acid system

Distribution coefficients of fission products in nitric acid for strongly acidic cation exchanger of sulfonic acid type with different cross-linking and structure were measured by a column method. Uptake of cationic fission products increases with resin cross-linking and decreases of nitric acid concentration. The distribution coefficient of the ion, [Kd_Mn+]^*, in a given system is expressed as log [Kd_Mn+]^*=B·log[Kd_Mn+]+A where [Kd_Mn+] is the distribution coefficient of the ion at 1M nitric acid for 10% crosslinked gel type cation exchanger, while A and B constants. Deviation from the above relation were observed for Y³⁺ and complex ions of ruthenium upward for macroporous type cation exchanger and downward for highly porous type cation exchanger. Upward deviation of Y³⁺ for 10% cross-linked gel type cation exchanger increased with concentration of nitric acid. Consequently, elution sequence varied from Y³⁺–Eu³⁺–Pm³⁺–Ce³⁺⁺ at 1M nitric acid to Eu³⁺–Pm³⁺–Y³⁺–Ce³⁺ for the same cation exchanger at 2M nitric acid. The same elution sequence, Eu³⁺–Pm³⁺–Y³⁺–Ce³⁺, was observed for 8% cross-linked gel type cation exchanger and 10% cross-linking macroporous type cation exchanger at 1M nitric acid.     

Simultaneous Production of 57Co and 109Cd in Cyclotron

⁵⁷Co and ¹⁰⁹Cd simultaneous production was studied, using composite targets of ^natNi and ^natAg. The targets were irradiated at the CV-28 Cyclotron, with proton beams of 24 MeV. The average production yields of ⁵⁷Co and ¹⁰⁹Cd were 1179.93 kBq/A·h, produced by direct and indirect reactions (11.31 days after the EOB) and 71.41 kBq/A·h (EOB), respectively. The chemical separation procedure was developed in order to obtain a mixed calibration source of ⁵⁷Co and ¹⁰⁹Cd, with a separation yield higher than 80%. The gamma spectroscopy technique was used for the radioactive analysis, using a HPGe detector. The stable elements were identified by atomic absorption spectrophotometry.     

Kinetics and mechanism of ion exchange of Fe3+, Cd2+ and Na+/H+ on Lewatite S-100 cation exchanger in aqueous and aqueous-detergent media

Sorption mechanism of Fe (III), Cd (II) and Na (I) on cation exchange resins in H-form was investigated from aqueous and aqueous-detergent media by a modified limited batch technique. The cation exchange studies involved the sorption of metallic ions onto a Lewatite S-100 exchanger. Effects of mesh size of the exchanger, temperature and detergent on the exchange rate have been investigated. The mechanisms of cation exchanges have been determined in the temperature range of 25–65°C. In all cases of the reactions ions, diffusion is found to be the rate determining step in the exchange process. The exchange rate in the exchange process was found to increase with a decrease of particle size and an increase of temperature. However, in case of the influence of detergent, the exchange reactions are dependent on the reaction technique. The effective-diffusion coefficients have been evaluated at three different temperatures. The energy barriers (ΔE_a), entropies of activation (ΔS*), (ΔH*) and (ΔG*) for various sorption systems have also been calculated. The results are discussed in terms of size and valences of the counter ions. No change in the internal structure of Lewatite S-100 is inferred due to the sorption of counter ions.     

Solid-state 31P and 109Ag CP/MAS NMR as a powerful tool for studying of silver(I) complexes with N-thiophosphorylated thiourea and thioamide ligands

A family of three- and four-coordinated silver(I) complexes of formulas [Ag(PPh₃)₂L], [Ag(PPh₃)L], and [AgL]_n with N-thiophosphorylated thiourea and thioamide ligands of general formula RC(S)NHP(S)(OPri)₂ [R = Ph, PhNH, iPrNH, tBuNH, NH₂] have been studied by solid-state ¹⁰⁹Ag and ³¹P CPMAS NMR spectroscopy. ¹⁰⁹Ag NMR spectra have provided valuable structural information about Ag coordination, which is in good accordance with the available crystal structure data. The data presented in this work represent a significant addition to the available ¹⁰⁹Ag chemical shifts and chemical shifts anisotropies. The silver chemical shift ranges for different P,S-environments and coordination state were discussed in detail. The ¹J(³¹P–^107/109Ag) and ²J(³¹P–³¹P) values were determined and analyzed.