Abstract
Sorption of various radionuclides such as Cs(I), Eu(III)/Am(III), Np(V), U(VI) and others onto iron oxide (goethite, hematite) and clay minerals (montmorillonite, kaolinite) was studied at wide experimental range (pH ionic strength, total radionuclides concentrations). In all case athermodynamic model for describing sorption onto studied minerals was built and successfully applied for all experiments. The required constants were calculated or verified from published data. For modelling sorption in mineral assemblages Component Additivity (CA) approach was successfully applied.
Highlights
Prediction of radionuclides behaviour in the environment in the places of long-term disposal of radioactive waste should include numerical methods for calculating the migration of different radionuclides in addition to instrumental methods of monitoring of the current radiation situation
Different clay samples were studied in order to examine effect of structural features of clay minerals, interlayer cations (Na/Ca/Li-forms of montmorillonite), surface area and presence of the accessory minerals on radionuclide sorption
The most difficult problem in SCMapproach is the lack of knowledge about a structure of sorbent surface and stoichiometry of surface complexes
Summary
Prediction of radionuclides behaviour in the environment in the places of long-term disposal of radioactive waste should include numerical methods for calculating the migration of different radionuclides (fission products, actinides) in addition to instrumental methods of monitoring of the current radiation situation. One of the major chemical processes that determine the behaviour of the radionuclides in geosphere is sorption on engineering barriers and products of its corrosion, host rocks, soil components, microorganisms, and etc.[1, 2]. Thermodynamic modelling using a surface complexation modelling approach is currently the state-of-the art tool for predicting the interaction of radionuclides with different minerals under different geochemical conditions. The aim of this work was improvement of methods of experimental determination of sorption constants by surface complexation modelling (SCM)
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