INFLUENCE OF CHELATING-AGENTS ON THE ELECTROKINETIC POTENTIAL OF THE CLAY FRACTION OF SODDY PODZOLIC SOILS

Enviromental pollution with the compounds of heavy and radioactive met als is a serious ecological problem. It is extremely difficult to remo ve the pollutants from soils, grounds, and muddy sediments. The main p roblem is to convert the sorbed cations to a water-soluble form [1-3]. The combined treatment of the ground with chemicals and electric fiel ds is one of the promising methods of deactivation in situ [4]. The ch emicals ensure the dissolution of radionuclides, and the electric fiel ds cause electromigration and electroosmotic transport of the dissolve d species to the electrode chambers. The electroosmotic contribution t o this process directly depends on the average electrokinetic potentia l (the zeta-potential) of the solid phase (the particles of sand, clay , etc.). Hence, it is interesting to study how the zeta-potential of t he finest fractions of soil is changed by classical chelating agents, namely, citric acid, ethylenediamine tetraacetic acid (EDTA), and 1-hy droxyethylidene-1,1-diphosphonic acid (HEDPA).