Studies on Ion Exchange Resins for the Removal of Radionuclides from Milk

Abstract

Polystyrene and phenol-formaldehyde sulfonic acid ion exchange resins containing identical milliequivalent quantities of exchange capacity were compared for relative removal efficiencies of ⁸⁵Sr, ¹³⁴Cs and ¹³³Ba from in vivo labeled raw whole milk. An inorganic exchanger was also compared for ⁸⁵Sr removal. The optimum cross-linkages and mesh sizes were determined for polystyrene sulfonic acid resins for ⁸⁵Sr removal. The inorganic silicate exchanger gave very poor ⁸⁵Sr removal and was therefore deleted from further study. The low cross-linkage (high porosity) polystyrene sulfonic acid resins gave the highest ⁸⁵Sr removal for the 16–50 mesh size. The 50–100, 100–200 and 200–400 mesh polystyrene sulfonic acid resins were found to be statistically equivalent for ⁸⁵Sr removal and superior to the 20–50 mesh. The optimum divinylbenzene cross-linkage for the former meshes was found to be 12%. The phenolformaldehyde resins gave the highest ¹³⁴Cs removal. There was very little difference in ¹³³Ba removal for all the resins tested. For 8 min milk-resin contact time the polystyrene sulfonic acid resins gave a maximum ⁸⁵Sr and ¹³³Ba removal of 84.5 and 88%, respectively. The phenol-formaldehyde sulfonic acid resins gave a maximum ¹³⁴Cs removal of 85%.