Improvement of radioactive liquid waste treatment efficiency by sequential cationic and anionic ion exchangers

摘要

Various types of liquid radioactive wastes are released from different nuclear activities. The treatment efficiencies of these wastes depend highly on the physical and chemical composition of each waste such as pH, TDS and electrical conductivity. The treatment efficiency of some radionuclides with different valency states (such as "Ts, (65) Zn, Co-60 and Eu152+154) was tested based on the absorption capacity of cationic exchanger (KY-2) functionlized with polystyrene sulphonic group. The competitive adsorption on cationic exchanger was investigated by mono radionuclide and multi radionuclides wastes. The influence of the presence of various anionic complexants in the rad-waste on the adsorption capacity and hence the treatment efficiency was quantitatively studied using weakly base aminated anionic exchanger (AN-31). The enhancement in decontamination factor of each radionuclide is mostly attributed to the high adsorption capacity of the cationic resin in addition to the complexation capability of the radionuclide with the different complexant existed in the waste solution. The complex formation improved the decontamination factor through indirect adsorption of the anionic species on the subsequent anionic exchanger during the treatment process. The results showed that the removal percentages are around 50% for Cs-134, Co-60, Zn-65 and (152,154) Eu, without complexant compound. Significant enhancements of the removal percentages > 85% were obtained for Co-60, Zn-154 and Eu-152,Eu-154, respectively, on addition of manganese sulphate while maximum removal percentage (75.3 +/- 0.7%) is obtained for Cs-134 when using 0.1 M citric acid as a complexing agent.