Selective adsorption of Ba2+ using chemically modified alginate beads with enhanced Ba2+ affinity and its application to 131Cs production

The Cs-131 radioisotope with a short half-life time and high average radiation energy can treat the cancer effectively in prostate brachytherapy. The typical Cs-131 production processes have a separation step of the cesium from Ba-131 to obtain a high specific radioactivity. Herein, we suggested a novel Cs-131 separation method based on the Ba2+ adsorption of alginate beads. It is necessary to reduce the affinity of alginate beads to cesium ions for a high production yield. The carboxyl group of the alginate beads was replaced by a sulfonate group to reduce the cesium affinity while reinforcing their affinity to barium ions. The modified beads exhibited superior Ba2+ adsorption performances to native beads. In the fixed-bed column tests, the saturation time and adsorption capacity could be estimated with the Yoon-Nelson model in various injection flow rates and initial concentrations. In terms of the Cs elution, the modified alginate showed better performance (i.e., an elution over 88%) than the native alginate (i.e., an elution below 10%), indicating that the functional group modification was effective in reducing the affinity to cesium ions. Therefore, the separation of cesium from the barium using the modified alginate is expected to be an additional option to produce Cs-131. (C) 2022 Korean Nuclear Society, Published by Elsevier Korea LLC.