Removal of radiocobalt from EDTA-complexes using oxidation and selective ion exchange

Methods for the removal of radiocobalt from an ethylenediaminetetraacetic acid (EDTA) complex of Co(II) (aqueous solution containing 10 microM Co(II) and 10 microM or 50 microM EDTA traced with (57)Co) are presented. The studies examined a combination of different oxidation methods and the sorption of (57)Co on a selective inorganic ion exchange material, CoTreat. The oxidation methods used were ultraviolet (UV) irradiation with and without hydrogen peroxide (H(2)O(2)), as well as ozonation alone or in combination with UV irradiation. Also, the possible contribution of Degussa P25 TiO(2) photocatalyst to degradation of EDTA was studied. The best results for the equimolar solution of Co(II) and EDTA were achieved by combining ozonation, UV irradiation, Degussa P25 TiO(2) and CoTreat, with approximately 94% sorption of (57)Co. High values for the (57)Co sorption were also achieved by ozonation ( approximately 88%) and UV irradiation (approximately 90%) in the presence of CoTreat and Degussa P25 TiO(2). A surplus of EDTA over Co(II) was also tested using 10 microM Co(II) and 50 microM EDTA. Only a slight decrease, to approximately 88% sorption of (57)Co, was detected compared to the value (approximately 90%) obtained with 10 microM EDTA.