[en] Effect of changes in pH environment on the adsorption of Sr²⁺ has been studied by radioisotope indications, using of radioisotope ⁸⁵Sr with energy γ-rays 0.514 MeV, in a static arrangement of the experiment, under aerobic conditions. The concentration range was 1 · 10^-5 - 5 · 10^-2 mol dm^-3. The samples of bentonite from Lieskovec deposit were tested which could be assigned into the Fe-montmorillonite group. (Author)

[en] Effect of changes in pH environment on the adsorption of Sr²⁺ has been studied by radioisotope indications, using of radioisotope ⁸⁵Sr with energy γ-rays 0.514 MeV, in a static arrangement of the experiment, under aerobic conditions. The concentration range was 1 · 10^-5 - 5 · 10^-2 mol dm^-3. The samples of bentonite from Lieskovec deposit were tested which could be assigned into the Fe-montmorillonite group. (Author)

[en] In this work sorption of strontium-85 on Slovak bentonites was studied. Sorption experiments that were conducted at four different values of pH = 2, 4, 6 and 8 showed that by increasing of pH in the solution an increasing of values of percentage of sorption and of distribution relationships occur. Value approaching 99% was achieved during the sorption of strontium cations from the bentonite deposits Kopernica only at pH = 8. It can be concluded that in addition to the basic mechanism of sorption, which is ion exchange, complex-forming reactions with surface groups of bentonite take place there at higher values. The increase in value attributable to R 'hydrolytic' adsorption, because there is a reaction between Sr(OH)⁺ and OH-groups and H⁺ ion competition is stifled. At pH = 2 in the whole studied range of concentrations low values of sorption percent, distribution ratio and adsorbed amount of strontium were observed. It can be attributed to a significant competitive impact of hydrogen ions and disruption of the structure of bentonite.

[en] In this presentation The sorption of strontium on bentonite from different Slovak deposits - Jelsovy potok, Kopernica and Lieskovec has been investigated under various experimental conditions, such as contact time, sorbate concentrations, presence of complementary cation. Sorption was studied using the batch technique. The uptake of Sr was rapid and equilibrium was reached almost instantaneously. The instantaneous uptake may be due to adsorption and/or exchange of the metal with some ions on the surface of the adsorbent. The best sorption characteristics distinguish bentonite Kopernica, sorption capacity for Sr of the fraction under 45 mm is 0,48 mmol·g^-1 for Sr. The highest values of distribution coefficient were reached for the bentonite Jelsovy potok. Radiation stability has been investigated, the higher sorption parameters were observed for the irradiated bentonites, which can be explained by the increase of specific surface of the bentonite samples. The presence of complementary cations depresses the sorption of Sr on bentonite. Cations Ca²⁺ exhibit higher effect on cesium sorption than the Na²⁺ ions. Results indicate that the sorption of Sr²⁺ on bentonite will be affected by the presence of high concentrations of various salts in the waste water effluents

[en] Sorption on bentonite from different Slovak deposits / Jelsovy potok, Kopernica and Lieskove has been investigated under various experimental conditions, such as contact time, pH, sorbate concentrations, presence of complementary cation. The sorption of strontium from aqueous solutions was investigated using a radiometric determination of distribution coefficient, Kd. The individual solutions were labelled with radiotracer. Radiation stability has been investigated, the higher sorption parameters were observed for the irradiated bentonites /tab.l/ , which can be explained by the increase of specific surface and change of solubility of the irradiated samples of bentonite. The presence of complementary cations, Na⁺, K⁺, NH₄⁺, Ca²⁺, Mg²⁺ and Ba²⁺ depresses the sorption of Sr on bentonite. In the case of bentonite Kopernica the effectiveness in reducing the sorption of strontium by cations followed the order K⁺ < NH₄⁺ < Na⁺ < Mg²⁺ < Ca²⁺ < Ba²⁺. Results indicate that the sorption of Sr⁺ on bentonite will be affected by the presence of high concentrations of various salts in the waste water effluents. (author)

[en] In this chapter the classification and nomenclature of elements in Slovak language is described. This chapter consists of following parts: (1) Basic definitions; (2) Symbols and names of elements; Periodic system of elements. Control tasks are included.

[en] Bentonite is a natural clay and one of the most promising candidates for use as a buffer material in the geological disposal systems for high-level radioactive waste and spent nuclear fuel. It is intended to isolate metal canisters with highly radioactive waste products from the surrounding rocks because of its ability to retard the movement of radionuclides by adsorption. Slovak Republic avails of many significant deposits of bentonite. Adsorption of Cs and Sr on five Slovak bentonite of deposits (Jelsovy potok, Kopernica, Lieskovec, Lastovce and Dolna Ves) and montmorillonite K10 (Sigma-Aldrich) has been studied with the using batch of radiometric techniques. Natural, irradiated and natrified samples, in three different kinds of grain size: 15, 45 and 250 μm have been used in the experiments. The adsorptions of Cs and Sr on bentonite under various experimental conditions, such as contact time, adsorbent and adsorbate concentrations, pH after adsorption and effect of pH change, chemical modification, competitive ions and organic agents on the adsorption have been studied. The K_d have been determined for adsorbent-Cs/Sr solution system as a function of contact time and adsorbate and adsorbent concentration. The data have been interpreted in terms of Langmuir isotherm. The adsorption of Cs and Sr has increased with increasing metal concentrations. Adsorption of Cs and Sr has been suppressed by presence of organic agents; and of bivalent cations more than univalent cations. By adsorption on natrified samples colloidal particles and pH value increase have been formed. Adsorption experiments carried out show that the most suitable materials intended for use as barriers surrounding a canister of spent nuclear fuel are bentonite of the Jelsovy potok and Kopernica deposits. (author)

[en] The aim of this work was to study the influence of mineralogical composition of bentonite adsorbents of Jelsovy potok bearing and standards of montmorillonite SAz-1 and STx-1 on adsorption behavior of strontium cations. In the experiment, Jelsovy potok bentonite showed good adsorption behavior compared with montmorillonite standards. Based on demonstration of the impact of mineralogical composition of adsorbents on adsorption percentage of strontium cations Jelsovy potok bentonite may be considered to be utilizable for multi-barrier system of a deep geological repository for high-level waste and spent nuclear fuel.

[en] An influence of monovalent and divalent cations and anions on an liquid extraction of pertechnetate anion from aqueous media using ionic liquids solubilized in various organic solvents has been studied. Suppression of extraction percentage was obtained with a divalent cations in a compare with monovalent cations showing almost no influence on extraction percentage. In a case of anions, perchlorate anion suppressed the extraction percentage in a highest degree. (authors)

[en] Studied and compared each other sorption properties of natural (J250), irradiated (J250ir) and chemically modified forms (BJ250) bentonite deposits of alder creek. Sorption capacity of samples decreased in the order: BJ250 > J250ir > J250. Irradiated samples show slight increase in sorption capacity. For natrified forms at lower concentrations of Cs in solution reached a low value of the partition ratios - evidence of colloids. While increasing the weight of natrified forms were also observed in liquid gel form, for its natural analogue has not been observed a significant change in the values of partition ratios. (authors)