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Exchanges of strontium on clinoptilolite zeolite

Gül, Özkan
Sr-90 and Cs-137, nuclear fission products, are the major sources of medium-level radioactive waste which must be decontaminated. Inorganic ion exchangers are the preferred materials to eliminate radioisotopes from aqueous nuclear waste because of their high selectivity, radiation and thermal stability, low cost and likely compatibility with cement containment. Clinoptilolite and other zeolites are widely used in nuclear industry for the removal of radioisotopes from aqueous nuclear waste. In this study, the performance of local clinoptilolite zeolite from Gördes region has been investigated so as to determine the conditions under which it can be used effectively in the column for strontium and cesium removal. It was found that under different loading conditions, breakthrough capacity varied from 0 to 0.4078 meq/g for strontium removal, breakthrough capacity varied from 0.1178 to 0.7800 meq/g for cesium removal. It was also determined that the increase of the flow rate reduced the exchange capacity of the bed. Effect of cationic form of the zeolite (Na-CLI: Sodium form of clinoptilolite and Original-CLI: Original form of clinoptilolite) on the breakthrough capacity was also searched. It was observed that Na-CLI performed much better for the removal of strontium and cesium with respect to its original form. In addition, effect of presence of calcium in the feed solution on the breakthrough capacity was investigated and it was found that presence of calcium in the feed solution makes strontium removal essentially impossible, in the case of cesium, presence of calcium in the feed solution decreases breakthrough capacity significantly.