Comparative kinetic desorption of 60Co, 85Sr and 134Cs from a contaminated natural silica sand column: Influence of varying physicochemical conditions and dissolved organic matter
Résumé
In order to determine the mechanisms of the retention of 60Co, 85Sr and 134Cs in natural silica sand columns, desorption experiments were performed by changes of pH and ionic strength and by injection of natural organic matter (NOM). Injection of KCl (0.1 M) resulted in a high release of 60Co (60-100%) and 85Sr (72-100%) but a smaller release of 134Cs (31-66%). Only limited release of 60Co (66%) and 85Sr (71%) and no release of 134Cs were observed by injection of NOM. The different percentages of desorption were related to the chemical characteristics of the organic colloids previously retained in columns before the desorption step. The results evidenced different sorption processes on energetically heterogeneous surface sites. According to the initial conditions, the binding of the radionuclides to the solid phase resulted from weak and easily reversible sorption processes to strong association probably by inner sphere complexes. The rather weak release of 134Cs by KCl was attributed to the strong retention of 134Cs by clay coatings on the natural silica sand surfaces. © 2005 Elsevier Ltd. All rights reserved.
Mots clés
Dissolved organic matter
Kinetic desorption
Silica sand column
Cesium
Desorption
Ionic strength
pH effects
Potassium compounds
Reaction kinetics
Silica sand
Strontium
Cobalt
cesium 134
cobalt 60
dissolved organic matter
potassium chloride
silicon dioxide
strontium 85
cesium
cobalt
desorption
kinetics
physicochemical property
sand
silica
strontium
article
binding affinity
chemical analysis
chemical reaction
colloid
ionic strength
pH
physical chemistry
soil chemistry
solid
Adsorption
Carbon Radioisotopes
Cobalt Radioisotopes
Environmental Monitoring
Environmental Pollution
Humic Substances
Hydrogen-Ion Concentration
Potassium Chloride
Silicon Dioxide
Soil Pollutants