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- Author or Editor: P. Rajec x
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Abstract
The possibility of simultaneous extraction of palladium and technetium from nitrate solutions was investigated using tri-n-octylamine (TOA) solutions in carbon tetrachloride as a heavy, non-flammable diluent. Conditions of technetium extraction being essentially known, the main attention was focussed on the extraction of palladium which was studied in dependence on the concentration of nitric acid, salts (nitrates, chlorides, nitrites), urea and palladium. A strong decrease of Pd extraction with 10% TOA in CCl4 has been found above a palladium concentration of 10−4M but in the presence of chlorides and nitrites a satisfactory high distribution can be preserved. Both Tc and Pd extracted with TOA/CCl4 can be stripped into dilute ammoniacal solutions. An extraction procedure for the simultaneous isolation of Pd (80% yield) and Tc (99%) from fission product waste solutions (0.20 g Tc and 0.17 g Pd/dm3 0.5–1.0M HNO3) is proposed.
Abstract
The extraction of reduced99mTc with 5,7-dichloroxine, tributyl phosphate (TBP) and 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMBP) from HCl−LiCl mixtures has been studied. A mechanism of extraction is proposed and the stability of the chlorocomplexes of technetium (V) in a hydrochloric and—lithium chlorid—perchloric acid mixture has been established using extraction data of99mTc and spectrophotometric measurements with99Tc.
Abstract
An extraction chromatographic material based on Aliquat-336 anchored on hydrophobized silica gel support was prepared as an ion exchanger. The prepared material appeared to be suitable for the separation of 99Tc from environmental matrices in column application. The properties of the material, sorption characteristic and distribution coefficient of 99mTcO4 -in various media were studied. The prepared sorbent was conditioned by washing with nitric acid. The solution containing 99mTcO4 - in 0.1M HNO3 was passed through the column. Tc was eluted from the column by 8M HNO3. The flow rate was 0.4 ml/min. The chemical yield of technetium during the separation process was determined using 99mTc tracer and gamma measurement. The sorption recovery of Tc from the prepared sorbent with 0.1M HNO3 solution was more than 98%, and the desorption recovery from the column using 8M HNO3 varied between 92-96%. It was found that the prepared sorbent is suitable for the separation of technetium from environmental matrices and radioactive wastes.
Abstract
Nickel is a constituent of wide range of construction materials in nuclear industry and their corresponding activation products are often encountered in low level solid radioactive waste and effluents. The article presents the radiochemical analytical method for determination of 63Ni in the concrete samples originated from Nuclear Power Plant Mochovce, Slovakia. The sample of concrete was ashed and leached with aqua regia thereafter hydroxides were precipitated with ammonia solution, leaving Ni in aqueous phase. The next purification steps included a precipitation as Ni–dimethylglyoxime (DMG) complex, an anionic exchange column and an extraction chromatography on Nickel resin. The purified 63Ni fraction was mixed with the scintillation cocktail and the mixture was measured by liquid scintillation counting (LSC). The radiochemical yield of the separation procedure was determined by atomic absorption measurement of stable Ni in the range of 49–71%. Up to the sample amount of 50 g the detection limit was 0.002 Bq g−1 at counting time 180 min and 95% confidence level.
Abstract
The distribution of strontium between the milk components, i.e., serum, casein micelles, whey and hydroxyapatite was determined. The sorption on hydroxyapatite was investigated using batch method and radiotracer technique. The aqueous phase comprised of either milk or whey. The sorption of strontium on hydroxyapatite depended on the method of its preparation and on the composition of the aqueous phase. The sorption of strontium was increased with an increase of pH. The presence of citrate species resulted in decrease of the sorption of strontium on hydroxyapatite. The sorption of 85Sr on hydroxyapatite decreased with the increasing concentration of Ca2+ ions. Addition of Ca2+ ions to milk resulted in milk pH decrease. The decrease in pH value after calcium addition to milk is related to exchanges between added calcium and micellar H+. The average value of strontium sorption on casein micelles in milk with presence of hydroxyapatite was (47.3 ± 5.6) %. The average value of sorption of 85Sr on casein micelles in milk without the addition of hydroxyapatite was (68.9 ± 2.2) %.
Abstract
The sorption of strontium on synthetic hydroxyapatite was investigated using batch method and radiotracer technique. The hydroxyapatite samples were prepared by a wet precipitation process followed by calcination of calcium phosphate that precipitated from aqueous solution. Also, commercial hydroxyapatites were used. The sorption of strontium on hydroxyapatite depended on the method of preparation and it was pH independent ranging from 4 to 9 as a result of buffering properties of hydroxyapatite. The distribution coefficient K d was significantly decreased with increasing concentration of Sr2+ and Ca2+ ions in solution with concentration above 1 × 10−3 mol dm−3. The percentage strontium sorption for commercial and by wet method prepared hydroxyapatite was in the range of 83–96%, while calcined hydroxyapatite was ranging from 10 to 30%. The experimental data for sorption of strontium have been interpreted in the term of Langmuir isotherm. The sorption of Sr2+ ions was performed by ion-exchange with Ca2+ cations on the crystal surface of hydroxyapatite. Although calcined hydroxyapatite is successfully used as biomaterial for hard tissues repair, it is not used for the treatment of liquid wastes.
Abstract
Sorption of Sr on five Slovak bentonites of deposits has been studied with the use of batch technique. In the experiments there have been used natural, chemically modified and irradiated samples, in three different kinds of grain size. The pH influence on sorption of strontium on bentonites, pH change after sorption and influence of competitive ions have been studied. Distribution ratios have been determined for bentonite–strontium solution system as a function of contact time, pH and sorbate concentration. The data have been interpreted in term of Langmuir isotherm. The uptake of Sr has been rapid and the sorption of strontium has increased by increasing pH. The percentage sorption has decreased with increasing metal concentrations. The pH value after sorption for the natrificated forms of bentonite starts already in the alkaline area and moves to the higher values. For the natural bentonites the values occur in the neutral or in the acidic area. Sorption of Sr has been suppressed by presence of competitive cations as follows: Ba2+ > Ca2+ > Mg2+ > NH4 + > K+ > Na+. By sorption on natrificated samples colloidal particles and pH value increase have been formed. The bentonite exposure as a result of interaction of γ-rays has led to expansion of the specific surface, increasing of the sorption capacity and to the change in the solubility of the clay materials.
Abstract
The coprecipitation of radium with strontium or calcium, 18C6 and tungstosilicic acid was studied. It was determined that radium is coprecipitated with Ca and Sr and mixed compounds are fomed. It was also find the yield of Ra depends on the ratio of stability constants of metals present in a solution with 18C6. The stability constant of Ra with 18C6 was determined using a precipitation method.
Abstract
Except the nuclear fuel reprocessing and nuclear materials safeguards, at present there are two areas of an increased responsibility of nuclear scientists for their results: radioecology and human medicaments. At both of them, quality and trustfulness of results is of great importance for their end-users and may have serious economical and legal consequences. The trends of implementation of good laboratory and manufacturing practices under umbrella of international quality management standards like ISO 17025:2005 and ISO 9001:2000 in radiochemical and radiopharmaceutical laboratories are discussed as expanding to “good scientific practice”. The case studies of the Comenius University laboratory LARCHA authorized for radiochemical analysis, and the company BIONT producing medical radionuclides and PET radiopharmaceuticals are used as the examples.
Abstract
The high-performance size-exclusion chromatography (HPSEC) and radiochromatography (HPSERC) was used for the identification of radiocesium and radiostrontium interaction with humic acid. It was found that the behavior of humic acid on size-exclusion chromatography is sensitive to the salt concentration and pH of the mobile phase. At lower ionic strength and in acidic region of pH, the Aldrich humic acid exhibited three main fraction within the ranges >760 kDa, 25–100 kDa and <5 kDa. Radiocesium was found in the low-molecular fractions (<1 kDa) of humic acids but radiostrontium interacts preferably with the fractions of humic acid of molecular weight within the range 2–5 kDa.
