Investigation of 137Cs and plutonium isotope sorption–desorption in bio- and synthetic materials

Abstract

Investigations on the pre-concentration of radionuclides (¹³⁷Cs and plutonium isotopes) from fresh water on solid matrices are presented in this study. A particular focus was given to an innovative physico-chemical removal process such as adsorption of radionuclides from an aqueous medium on new type adsorbents, environmental-friendly materials. Sorption of the tested radionuclides from the lake water solution by environmental assays and synthetic sorbents was compared. Lake water was analyzed for main anions, micro- and macroelements, using ion and atomic absorption chromatography methods, respectively. Batch type and dynamic flow column laboratory experiments were performed. The sorption–desorption capacity of radionuclides by the tested sorbents was estimated based on the results of α- and γ-spectrometric measurements. According to the removal efficiency results, moss can be considered as the best sorbent for plutonium of the tested environmental-friendly sorbents, whereas the moss sorption capacity exceeded even that of the tested synthetic ones. The highest ¹³⁷Cs removal efficiency from the lake water solution was obtained for granular activated carbon. Application of the dynamic flow method carried out in situ confirmed the reversibility of sorbed background ¹³⁷Cs activity in the moss observed during the batch type experiments, and the method of the moss bed column turned to be unfit for the pre-concentration of ¹³⁷Cs from the lake water. Application of a single moss bed column for the ¹³⁷Cs and plutonium isotope pre-concentration for the first time carried out in situ allowed us to determine the activity concentration of ^239,240Pu and ²³⁸Pu in the lake water – 4.87±0.98 and 0.67±0.21 mBq/m³, respectively. The reversible ¹³⁷Cs and different plutonium sorption in the moss apparently indicates different binding properties of these radionuclides to the moss, therefore further investigations on this issue are foreseen.