This study is based on experimental data from the elution of Co-60(2+) ions with Na+ ions in mixed-bed columns packed with resins used in the cleaning system of a research nuclear reactor. The operational parameters for conditioning the resins were obtained by washing, separating cationic resins from anionic resins, and eluting radioactive ions from the cationic resins with a solution of 2 N NaCl. The ion-exchange behavior of Co-60(2+)-Na+ was analyzed by measuring the variation of the activity or concentration of radioactive cobalt in a column as a function of the amount of saline solution required to desorb the radioactive cobalt from the column. The linear model was applied to obtain the constants that describe the Co-60 desorption process. (c) 2012 Elsevier B.V. All rights reserved.