Remediation of radioiodine using polyamine anion exchange resins

Abstract Two weak base anion exchange resins, Lewatit A365 and Purolite MTS9850, have been tested for the removal of aqueous iodide from conditions simulating nuclear waste reprocessing streams. pH variation and relevant co-contaminant addition (nitrate, molybdate and iodine) allowed for assessment of iodide extraction behaviour of each resin. Isotherm experiments were performed and maximum uptake capacities obtained exceed current industrial adsorbents, such as silver-impregnated zeolites. Maximum loading capacities, determined by Dubinin–Radushkevich isotherm, were 761 ± 14 mg g −1 for MTS9850 and 589 ± 15 mg g −1 for A365. Uptake for both resins was significantly suppressed by nitrate and molybdate ions. The presence of dissolved iodine in the raffinate however, was found to increase iodide uptake. This was explained by characterisation of the spent resin surface by infrared and Raman spectroscopy, which determined the presence of triiodide, indicating charge-transfer complex formation on the surface. Dynamic studies assessed the effect of co-contaminants on iodide uptake in a column environment. Data was fitted to three dynamic models, with the Dose-Response model providing the best description of breakthrough. In all cases iodide breakthrough was accelerated, indicating suppression of uptake. Two weak base anion-exchange resins, Lewatit A365 and Purolite MTS9850, were assessed for aqueous iodide extraction from simulated nuclear waste reprocessing streams. Effects of pH variation and co-contaminants (nitrate, molybdate and iodine) were studied. Maximum uptake capacities were 761 mg g −1 for MTS9850 and 589 mg g −1 for A365. Capacity for both resins was significantly suppressed by nitrate and molybdate. The presence of iodine however, increased iodide uptake. This was explained by triiodide charge-transfer complex formation on the resin surface. Dynamic behaviour was well-described by the Dose-Response model. Addition of co-contaminants accelerated iodide breakthrough, but capacity was still significant.