Study the radiation effects on 4-vinylpyridine-based porous resins in 99Tc adsorption

The 4-vinylpyridine-based porous resins (4VP–DVB and 4VP–DVBQ) were synthesized to adsorb ⁹⁹Tc from radioactive waste. The radiation stability of the synthesized resins were investigated in air, water, HCl, and HNO₃ mediums. The radiolytic degradation of resins was evaluated by the total organic carbon analysis. The weakly basic resin (4VP–DVB) and strongly basic resin (4VP–DVBQ) showed a remarkable resistance to radiation in HCl and HNO₃ solutions respectively. Moreover, adsorption behavior of irradiated 4VP–DVB and 4VP–DVBQ resins toward ⁹⁹Tc was studied by the batch experimental method.

     

Stability of polyvinylpolypyrrolidone against gamma-ray irradiation in HNO3 media

Polyvinylpolypyrrolidone (PVPP) is a resin with adsorption selectivity for U(VI) in HNO₃ media. The stability of this resin has been examined against gamma-ray irradiation using HNO₃ solutions of various concentrations. Samples of PVPP immersed in HNO₃ solutions up to 6 mol·dm^?3 (=M) were irradiated by a ⁶⁰Co source at 3.6 kGy·h^?1 to reach 0.90 MGy at room temperature under ambient atmosphere. As a result, no clear decrease in the capacity for U(VI) when added in 3 M HNO₃ was observed for any samples, or rather the capacity was found to increase by approximately 50 % for PVPP irradiated in 6 M HNO₃. It was indicated from some spectroscopic analyses of the irradiated samples that the irradiation causes the cleavage of the pyrrolidone ring of PVPP. This occurs by the addition of an oxygen atom originating from HNO₃, followed by the formation of straight-chain groups with multiple coordinative atoms by the successive addition of oxygen, finally leading to the generation of a primary-amine-type weakly-basic anion exchange resin. The increase in the U(VI) capacity would be due to the formation of the straight-chain groups. However, such structural changes were not observed by heating at 323 K in up to 6 M HNO₃ for 20 days. Thus, it was shown that PVPP is a heat-resistant resin.     

Extraction of99Mo-molybdophosphate and99mTc-pertechnetate from various acid solutions by bis/2-ethylhexyl/ phosphoric acid

The extractability of⁹⁹Mo-molybdophosphoric acid H₃/PMo₁₂O₄₀/ and^99mTc-pertechnetic acid /PTcO₄/ in 20% (v/v) bis /2-ethylhexyl/ phosphoric acid /HDEHP/ in benzene has been investigated at different concentrations of HCl, HBr and HNO₃ acids. The effect of extractant concentration and diluent on the extractability of molybdophosphoric and pertechnetic acids with 20% (v/v) HDEHP in benzene from different concentrations of HCl acid has also been studied.⁹⁹Mo-molybdo-phosphoric acid was found to be selectively extracted and separated from^99mTc-pertechnetic acid with 20% HDEHP in benzene at an acidity of about 0.49M HCl, HBr and HNO₃. The extractability of H₃/PMo₁₂O₄₀/ from these acids generally follows the decreasing order HBr>HCl>HNO₃. The separation factors /K_d molybdophosphoric/K_d pertechnetic/ were found to be 12.9×10⁵ and 7.6×10⁵ for HBr and HCl, respectively. The extractability of pertechnetic acid follows the order HCl>HBrHNO₃. Benzene is the diluent due to its radiation stability. A new procedure for the separation of^99mTc from⁹⁹Mo was suggested.     

Prevention of loss of mercury(II) during storage of dilute solutions in various containers

Summary Losses of ionic mercury from various solutions of 30 ng Hg/ml and 1 g Hg/ml concentration stored in polyethylene, polypropylene, quartz and glass were studied for storage periods up to 57 days by means of the radiotracer technique. Distilled water solutions and solutions treated with HCl and HNO₃ lost substantial fractions of their mercury, whereby both adsorption and volatilization were involved. The largest losses (of up to 98%) occurred after the storage of water and nitric acid solutions in polyethylene. A combination of hydrochloric acid and hydrogen peroxide, also in the presence of nitric acid, proved to be excellently suited for preventing the loss of mercury. No detectable changes of mercury concentration were observed for solutions treated with 2% HCl + 2% H₂O₂ and stored in polyethylene for up to two months. After this storage period, the losses were < 2.5% for quartz, < 5% for glass and < 7% for polypropylene.

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Verhinderung von Quecksilber(II)-Verlusten bei der Lagerung verdünnter Lösungen in verschiedenen Behältern

     

Evaluation of high-pressure microwave digestion methods for hydride generation atomic absorption spectrometric determination of total selenium and arsenic in sediment

Five closed-vessel microwave digestion methods were compared for the accurate determination of arsenic and selenium in NIST SRM 1645 River Sediment by flow-injection hydride-generation atomic absorption spectrometric methods. The digestion methods using five different acid mixtures (HNO₃/ H₂SO₄, HNO₃/HCl0₄, HNO₃/HCl, HNO₃/HCl/HF, HNO₃/H₂SO₄/HClO₄) were all found to be reliable for the determination of the analytes. Taking into consideration the safety and suitability for the analysis of other metals, the methods based on the use ofaqua regia are recommended for closed vessel microwave digestion with pressure control. Using the quick digestion program, the presence of up to 10% organic content in soil samples did not adversely affect the closed vessel digestion and did not cause the loss of volatile analytes. After digestion, opening the vessel under an inner pressure of below 345 kPa (50 psi) had no effect on the accuracy of the results. The recommended digestion methods (HNO₃/HCl and HNO₃/ HCl/HF) for the reliable determination of arsenic and selenium in different sediment samples were demonstrated. The calculated detection limits (3 _b ) were less than 0.030 g/g and 0.033 g/g for arsenic and selenium, respectively. All analytical results for arsenic and selenium in SRM 1645 River sediment, NRCC BCSS-1 Marine Sediment and NIES CRM Pond Sediment were within or near the certified and reported ranges, with the exception of selenium in NIES CRM No. 2 Pond Sediment.     

Mössbauer Spectroscopic Studies of K2SnCl6 and SnCl4·5H2O in Frozen Aqueous Solutions and in Ion Exchange Resins

Concentration dependence of isomer shift of K₂SnCl₆ and tin(IV) chloride was studied. Tin was hydrolyzed in both cation and anion exchange resins after water washing. Two pairs of these two solutions showing the same isomer shift values, and therefore the same , were selected for further studies in HCl solutions and in anion exchange resins. The first pair was 0.04 M K₂SnCl₆ and tin(IV) chloride solutions (δ=0.00 mm/s; =0): Their δ-[HCl] curves coincided each other. Tin was sorbed on anion exchange resin as pentachlorstannate(IV) at (HCl)≤6 N, and chiefly as hexachlorostannate(IV) at [HCl]≥7 N. The both complexes were sorbed when 6 N < [HCl] < 9 N. The δ-[HCl] curves of the second pair, 0.4 M K₂SnCl₆ and 3 M tin(IV) chloride(δ =0.23 mm/s; =3), also coincided each other, and tin was sorbed as pentachlorostannate(IV) from K₂SnCl₆ solutions in the HCl concentration range studied (≥5 N).     

Application of Metalfix Chelamine prior to the determination of noble metals by the inductively coupled plasma atomic emission spectrometry

Metalfix Chelamine chelating resins of two different bead sizes (150-300 and 40-80 μm) were examined and compared regarding their application for sorption of Au, Ir, Pd, Pt, Rh and Ru ions from medium of HCl, HNO₃ and mixtures of HCl and HNO₃. The quantitative enrichment of Au, Ir, Pd and Pt was established for the resin of 150-300 μm particle size and for solutions acidified with HCl and HNO₃ (3:1) up to the concentration of 0.50 mol l⁻¹. In the case of Rh and Ru, the uptake of these metals by the resin was lower than 50%. For the elution, solutions of different reagents, i.e. HCl, HNO₃, KCN, KI, KSCN and (NH₂)₂CS, were studied with respect to the complete release of the analytes retained by the resin. In addition, influence of various base metals, i.e. Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, on the retention of the noble metals was investigated. Under the selected conditions for the retention and elution of Au, Ir, Pd and Pt, the analytical performance of the proposed pre-concentration procedure was evaluated and it was applied to the determination of these noble metals in anodic sludge sample.     

Selectivity of glassy type mixed zirconium-titanium phosphate toward rare earth metal ions

The selectivity of glass type mixed Zr+Ti phosphates with various Ti contents has been investigated toward rare earth metal ions. The k_d values were determined by radiotracer technique both in HCl and HNO₃ solutions of various concentrations. At room temperature and at pH=4 the following selectivity orders were found: Yb>TmEu>Sm>La (HCl) and Eu>La>Sm>Yb>Tm (HNO₃).     

Solvent extraction of hafnium(IV) by TBP and topo from acidic organic-aqueous solutions

Tracer concentrations of Hf(IV) were extracted by 60% TBP solution in benzene from 5M HClO₄, 5M HCl, 6M HNO₃ and 8M H₂SO₄ solutions, and by 1·10^?4 M TOPO solution in benzene from 2M HClO₄ and 2M HCl solutions in the presence of a variety of organic solvents miscible with the aqueous phase. Whereas for TBP these solvents caused an increase of HF(IV) extraction, an opposite effect was observed for TOPO. The results were discussed from the point of view of various solute-solvent and solvent-solvent interactions.     

Reduction of Ruthenium(IV) to Ruthenium(III) in Aqueous Alcohol Solutions of Hydrochloric Acid under Microwave Radiation

The behavior of a kinetically inert form of ruthenium(IV), the -oxo-bis-[pentachlororuthenate(IV)] ion [Ru₂OCl₁₀]^4–, was studied in aqueous alcohol solutions of hydrochloric acid under microwave radiation and upon the heating of the solutions. The conditions were selected for the quantitative reduction of ruthenium(IV) to ruthenium(III) with alcohols in 0.6–10 M HCl solutions in a microwave field. The maximum time it takes to reduce ruthenium(IV) under microwave radiation (30 min) was an order of magnitude shorter than that for heating the solutions in a boiling water bath. Regardless of the type of alcohol, the most rapid reduction of ruthenium(IV) was observed at the boundaries of the studied range of hydrochloric acid concentrations. It was found that, under microwave radiation, thermal effects were the driving force of the process in a 0.6 M HCl solution at 98°C, whereas, in 8–10 M HCl solutions, the contributions of nonthermal and thermal effects were comparable. It was shown that the reducing ability of saturated monoatomic C₁–C₄ alcohols increases with the number of carbon atoms and is also due to specific features of microwave radiation.     

210Pb and210Po in tobacco-with a special focus on estimating the doses of210Po to man

Studies have been carried out on the solubility of Pu(III) oxalate by precipitation of Pu(III) oxalate from varying concentrations of HNO₃/HCl (0.5–2.0M) solutions and also by equilibrating freshly prepared Pu(III) oxalate with solutions containing varying concentrations of HNO₃/HCl, oxalic acid and ascorbic acid. Pu(III) solutions in HNO₃ and HCl media were prepared by reduction of Pu(IV) with ascorbic acid. 0.01–0.10M ascorbic acid concentration in the aqueous solution was maintained as holding reductant. The solubility of Pu(III) oxalate was found to be a minimum in 0.5M–1M HNO₃/HCl solutions containing 0.05M ascorbic acid and 0.2M excess oxalic acid in the supernatant.     

Separation of Ga(III) from Cu(II), Ni(II) and Zn(II) in aqueous solution using synthetic polymeric resins

Poly (acrylamide-acrylic acid-dimethylaminoethylmethacrylate), p(AM-AA-DMAEM) and Poly(acrylamide-acrylic acid)-ethylenediaminetetracetic acid disodium, p(AM-AA)-EDTANa₂ were prepared by gamma radiation-induced template polymerization technique and used for the separation of Ga (III) from Cu (II), Ni (II), and Zn (II) in aqueous media. The effect of pH and contact time on the separation process was studied. The optimum pH value for the separation process is 3–3.5. The result shows that Ga (III) is first extracted while Cu (II), Ni (II) and Zn(II) are slightly extracted at this pH value. The recovery of metals using HCl, HNO₃ and H₂SO₄ has been studied. The resins may be regenerated using 2M HCl solutions.      

Study on thermal stability of tertiary pyridine resin

The fundamental properties of tertiary pyridine resin (TPR) and its mixtures with methanol/HCl and HNO₃ were investigated in order to evaluate the thermal stability of TPR and to determine the conditions necessary to avoid runaway reactions. Based on experimental DSC results, it was found that TPR with HCl was thermally stable, but strong decomposition was possible with TPR in the presence of HNO₃. From the results of heating tests on the gram scale, TPR with HNO₃ reacted violently under high temperature regardless of HNO₃ concentration and presence or absence of methanol. However, it was considered that the violent exothermic reaction could be controlled by heating temperature.     

Aqueous solution of terbium as a scintillator for registration of actinoid alpha-radiation

A scintillator, based on the direct effect of a radiation upon a dissolved activator, has been suggested. Concentrated /2–2.5 mol/1/ solutions of Tb³⁺ in D₂O and H₂O, and aqueous solutions of HCl, HNO₃, and HClO₄ have been found to possess a high light output of scintillations affected by -particles of actionoids. The scintillation efficiency of terbium solution in D₂O is higher than that of some well-known organic scintillators. The terbium scintillator is quenched feebly by actinoid salts. Besides, it is of low sensitivity for the - and -radiation. The scintillations in terbium solutions represent groups of separate single-electron pulses with an exponentially decreasing frequency of their occurrence within groups.     

Isolation of iron and strontium from liquid samples and determination of Fe and Sr in liquid radioactive waste

This paper describes the method of isolating iron and strontium from liquid samples with a low concentration of ions that enables simple and rapid determination of and . The method consists of binding (concentrating) Fe and Sr at the cation exchanger Amberlite IR-120, their elution from cation exchanger with 4 M HCl or 8 M HNO₃, isolating Fe on the TRU extraction chromatographic column with 4 M HCl or 8 M HNO₃, and isolating Sr on the Sr.spec column with the mixture of 8 M HNO₃+2 M HCl or 5 M HNO₃. After the isolation, is determined by liquid scintillation counting with scintillation solution, while activity of is obtained by Cherenkov counting in 5 M HNO₃. It was shown that successive counting can be used for simultaneous determination of activity. The activity ratio of (up to 20:1) and vice versa does not impact the determination. is also determined immediately after isolation. The measurements in α,β mode can be used to verify any presence of α-emitter (americium) in the fraction of iron and to correct the result. The method was tested by determining and in model samples and radioactive waste samples. The paper also shows that Fe and Zn can be bound to the TEVA and TRU resins from the solutions of HCl, HNO₃, and mixture of HCl+HNO₃. The binding strength depends on the type of resin and the concentration of the acid or the concentration of acids in the mixture. These resin and acids can be used for mutual separation of Fe and Zn and their separation from other elements.     

Extraction chromatographic separation of iron from complex liquid samples and the determination of <Superscript>55</Superscript>Fe

Summary Iron separation is described from liquid samples with a high concentration of ions that enables simple determination of ⁵⁵Fe. One of the described methods consists of iron precipitation from a large volume seawater by sodium hydroxide and/or ammonium carbonate and separation from other elements (Ca, Sr, Cu, Mg, etc.) on a TRU column with 4M HCl or 8M HNO₃. In the other procedure iron is separated directly from a mixture of seawater samples and HCl on a TRU column. In both methods, the iron recovery is almost 100%. After separation, ⁵⁵Fe is determined by counting with a liquid scintillation counter. The binding of Fe and Zn on TEVA, U/TEVA and TRU resins from seawater solutions of HCl and HNO₃depends on the type of the resin, concentration of acid and other ions. Iron and zinc can be separated from seawater on a U/TEVA column with 2M HCl.     

Effect of gamma-irradiation on surface and catalytic properties of Co3O4 doped with NiO

NiO-doped Co₃O₄ samples precalcined at 500 °C were subjected to various doses of -rays within the range 0.2-1.6 MGy. The particle size and BET-surface areas of different samples were determined using XRD and nitrogen adsorption at -196 °C. The catalytic reactions studied were conversion of ethanol and isopropanol at 250-400 °C using a micropulse technique and H₂O₂ decomposition in aqueous solution at 30-50 °C. The results revealed that the -irradiation brought a significant decrease in the particle size of Co₃O₄ phase with subsequent increase in the S_BET surface areas. The treatment brought also a progressive decrease in the total conversion of both alcohol (dehydration and dehydrogenation) falling to a minimum value (about 20% of its initial activity) at a dose of 0.8 MGy. The catalysts retain their initial activity upon exposure to a dose of 1.6 MGy. On the other hand, the catalytic activity in H₂O₂ decomposition of the investigated system decreased progressively by increasing the dose of -rays and the catalysts lost more than 90% of their initial activity upon exposure to a dose of 1.6 MGy.     

Application of ICP-AES to the determination of rare earth elements in phosphate samples

Summary ICP-AES has been used for the determination of rare earth elements (REE) in samples of phosphorite deposits collected from the Western Desert, Egypt. Complete dissolution of the samples was achieved by using acid digestion with HF/HNO₃/HCl in a PTFE closed vessel and subsequent treatment with HClO₄, with the same procedure but with fuming HCl replacing HClO₄ and with HNO₃ and fuming HCl in a quartz vessel and subsequent treatment with HF/HClO₄/HNO₃. Analysis lines for La, Ce, Pr, Nd, Sm, Gd, Dy and Y were selected after study of the spectral interferences for the sample types concerned. Results revealed that the average total content of the REE, which could be directly determined in the present samples, varies between 1.08 and 1.53 mg/g, whereas individual element concentrations range from 40 to 300 g/g. Analysis results obtained with the different dissolution techniques were found to be in good agreement. On leave from the National Research Centre, Physics Department — Spectroscopy Laboratory, Cairo, Egypt     

Sorption characteristics of chelating resins

Chelating resins are used for preconcentrating metal ions in trace analysis. As part of a systematic study of sorption characteristics of the chelating resin Chelex 100, the sorption of Zn(II) and Cd(II) in different aqueous media was investigated. The distribution coefficient (DC) values for both Zn(II) and Cd(II) were extremely low (<4) in 0.5 to 6M HNO₃ and H₂SO₄ solutions. In HCl solution, theDC values for both Zn(II) and Cd(II) were higher, reaching a peak of nearly 40 in 3M HCl solutions. TheDC values for both Zn(II) and Cd(II) increased with increasing pH in chloride, nitrate, and sulfate solutions (0.1M); the value was nearly 10⁴ for both Zn(II) and Cd(II) between pH 5 and 7 and pH 6 and 8, respectively.     

Stability of <Emphasis Type="Italic">iso</Emphasis>Hex-BTP/SiO<Subscript>2</Subscript>-P adsorbent against acidic hydrolysis and γ-irradiation

Separation of trivalent minor actinides (MA(III): Am(III), Cm(III)) from fission products (FP) in high-level liquid waste (HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an advanced aqueous partitioning process based on extraction chromatography method was studied. Because R-BTP extractants (R-BTP: 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine, R = alkyl group) exhibit high selectivity for MA(III) over trivalent rare-earth elements (RE(III)), a novel adsorbent isoHex-BTP/SiO₂-P was prepared by impregnating isoHex-BTP extractant into the macroporous SiO₂-P support with a mean diameter of 60 μm. The stability of isoHex-BTP/SiO₂-P against nitric acid and γ-irradiation was investigated. It was found that isoHex-BTP/SiO₂-P adsorbent shows good adsorption affinity to Dy(III). The hydrolytic and radiolytic stability of isoHex-BTP/SiO₂-P adsorbent in 0.01 mol/L HNO₃ was fairly promising. However, the adsorption amount Q of Dy(III) decreased dramatically in 3 mol/L HNO₃ with the increase of the absorbed dose and became nearly zero at the absorbed dose over 46 kGy. These results suggest that with the synergetic effect of radiation and acidic hydrolysis, the adsorbent instantly loses its efficacy.