Immobilization of radioactive waste in cement: Iodine binding by cementitious materials under highly alkaline conditions

Abstract

This work is directed to assess iodine interactions with hardened cement paste (HCP) under highly alkaline conditions (pH > 12) with/without a reductant. For this purpose, a series of K_d (distribution coefficient) experiments using ¹²⁷I as a tracer were performed. The K_d values of iodine were in the order of 172–1095 mL g^–1 in the batch experiment without a reductant, and in the order of 83–92 mL g^–1 in the experiment with a reductant. The percentage of iodine leached out from HCP throughout the experiment suggested its very strong binding with cementitious materials. The obtained results allow supposing that chemical speciation of iodine has influence on the interaction of iodine with HCP under highly alkaline conditions.