Stability against oxidation of a type-I anion exchanger. I. The effect of persulfate ion on capacity and swelling

The effect of the strong anionic oxidant persulfate, S₂O₈²⁻, on the ion exchange capacity of Bio-Rad AG1-X4 100–200 mesh anion exchange resin was investigated when present as the counterion, i.e., with the exchanger in the reactive persulfate form. The decrease of ion exchange capacity as a function of time and the increase in swelling due to scission of polymer chains by the oxidant were determined. It was found that very little (dry) capacity loss occurred during storage of air-dried S₂O₈²⁻-form resins at ambient temperature. However, a progressive decrease in capacity was noted when the resin samples were kept fully water swollen. The potential effect of initial pH was briefly examined. Some experiments with chromate- and vanadate-form resins were also carried out.