Effect of the surface hydration of clay minerals on the adsorption of cesium and strontium from dilute solutions
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Effect of the surface hydration of clay minerals on the adsorption of cesium and strontium from dilute solutions Yuriy Zabulonov1 · Vadym Kadoshnikov1 · Halyna Zadvernyuk1 · Tetyana Melnychenko1 · Valeriy Molochko1 Received: 28 March 2020 / Revised: 21 August 2020 / Accepted: 2 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The use of clay minerals for the decontamination of liquid radioactive waste generated during the work of nuclear energy enterprises remains currently relevant. The effect of the surface hydration of a montmorillonite nanocrystal on the adsorption of cesium and strontium ions from dilute solutions was studied. As opposed to the generally accepted mechanism of the adsorption of cesium and strontium ions on active sites of clay mineral crystals, we considered the adsorption of radiocesium and radiostrontium by montmorillonite taking into account its colloidal chemical properties. When montmorillonite nanocrystals interact with water, a double electric layer with a mobile diffuse ionic atmosphere forms on the surface of the solid phase. The adsorption of cesium and strontium ions from dilute aqueous solutions confines itself to ion-exchange reactions of cesium and strontium ions of a dispersion medium with exchange cations of the diffuse ionic atmosphere of montmorillonite. Enhanced adsorption of cesium ions compared with strontium ions was explained by low charge density on the outer shell of cesium ions and the ability of cesium ions to overcome the diffuse ionic atmosphere easily and to be fixed firmly on the outer surface of the montmorillonite nanocrystal. Keywords Cesium adsorption · Strontium adsorption · Clay minerals · Ion exchange · Zeta potential
1 Introduction The widespread use of nuclear energy in the national economy requires the development of effective methods for the removal of hazardous radionuclides along with the development of new modern technologies for the production of energy and radioactive materials. For these purposes, various sorbents are widely used that make it possible to extract radionuclides from contaminated solutions with a view to their further compaction. The low cost and high adsorption activity of smectites contribute to their widespread use for the extraction of radionuclides from aqueous solutions. In recent decades much attention has been paid to the study of the mechanism of adsorption of cesium and strontium since an understanding of the main patterns of adsorption allows us to develop effective and relatively inexpensive decontamination methods. * Halyna Zadvernyuk [email protected] 1
State Institution “The Institute of Environmental Geochemistry of National Academy of Sciences of Ukraine”, 34a, Palladin Avenue, Kyiv 03680, Ukraine
Experimental data on the adsorption kinetics of stable Cs (I), Sr (II), and Eu (III) isotopes in natural soils (Qiu et al. 2018) showed that the adsorption of these cations was described by second-order equations. The adsorption equilibrium of Cs (I) followed the Freund
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