[en] In the natural waters of mining regions, for example, Karelia, there are uranium and noble-metal ions, whose concentration amounts to 10^-8-10^-10 g/liter, which is close to or above the sensitivity threshold of methods employed for their analysis. Existing methods of concentration are laborious to carry out and require transportation of large volumes of samples and do not always guarantee detection of elements of interest. It was of interest to carry out studies using Vion chemisorptive fibers, which have high values for specific surface and static-exchange capacity. Thanks to this, a considerable shortening in duration of the process for sorbing the elements and a more complete trapping of these from low-concentration solutions was expected. As chemisorbents the authors used the fibrous materials Vion KN-1 (in the Na-form), AN-1, and AN-3, which are characterized by static-exchange capacities of 5.3; 2.3; and 2.7 meq/g, respectively. Investigations of the sorption of uranium and of noble metals by the indicated chemisorbents was carried out under laboratory and field conditions

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[en] Short communication

[en] Sorption capacity of some natural, technogeneous, and industrial materials (carbonic and mineral) and also of composite sorbents based on them with respect to radionuclide mixtures has been determined. These materials are promising for decontamination of natural and industrial waters wastewaters and for the removal of corresponding nonradioactive impurities from these waters

[en] The sorption of copper on synthetic hydroxyapatite was investigated using a batch method and radiotracer technique. The hydroxyapatite sample prepared by a wet precipitation process was of high crystallinity with Ca/P ratio of 1.688. The sorption of copper on hydroxyapatite was pH independent ranging from 4 to 6 as a result of buffering properties of hydroxyapatite. The adsorption of copper was rapid and the percentage of Cu sorption was >98% during the first 15-30 min of the contact time. The experimental data for sorption of copper have been interpreted in the term of Langmuir isotherm. The sorption of Cu²⁺ ions was performed by ion-exchange with Ca²⁺ cations on the crystal surface of hydroxyapatite under experimental conditions. The competition effect of Zn²⁺, Fe²⁺ and Pb²⁺ towards Cu²⁺ sorption was stronger than that of Co²⁺, Ni²⁺ and Ca²⁺ ions. The ability of the bivalent cations to depress the sorption of copper on hydroxyapatite was in the following order Pb²⁺ > Fe²⁺ > Zn²⁺ > Co²⁺ ∼ Ni²⁺. (author)

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[en] The surface and sorption properties of kaolinite were analyzed as a function of silicate. Batch experiments indicate that the U(VI) sorption is promoted by the addition of silicate at low pH while is depressed at high pH. The sorption was acceptably predicted by the formation of a ternary silicate surface complex under the experimental conditions. The pseudo-second order kinetic model fit the sorption kinetics better. The sorption isotherms are more in accordance with Langmuir model and the thermodynamic parameters indicate a spontaneous and endothermic sorption process. (author)

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