Selective Cesium Uptake Behavior of Insoluble Ferrocyanide Loaded Zeolites and Development of Stable Solidification Method

抄録

Development of Cs selective adsorbents and stable solidification method contributes to the advancement of decontamination system and environmental remediation. This study deals with the preparation of Cs selective composites (insoluble ferrocyanide-loaded zeolites), uptake properties of Cs, stable solidification of composites, and evaluation of Cs leachability. The Cs immobilization (%) for the Cs-saturated composites (Cs-NiFC-SA-5, Cs-CoFC-MC) was above 99% and 96% even after calcination at 1,000℃ and 1,100℃, respectively, indicating that nearly all Cs ions are immobilized in the sintered products. On the other hand, the Cs immobilization (%) for the Cs-saturated composites (Cs-NiFC-A (A51, A51J), Cs-NiFC-LSX) tended to decrease with calcining temperature; for example, the Cs immobilization (%) for NiFC-X at 1,000℃ and 1,100℃ was estimated to be 74.9% and 55.4%, respectively, and many spots concentrating Cs were observed on the surface. The difference in immobilization behavior between natural zeolites and synthetic ones is probably due to the phase transformation and surface morphology at higher temperature above 1,000℃. The increasing order of Cs leaching rate for the sintered products at 1,000℃ was CsNiFC-SA-5(1.60×10⁻⁴ g/(cm²·day)<CsNiFC-A-51J<CsNiFC-LSX. The sintered products of CsNiFC-LSX consisting of CsAlSiO₄ phase at 1,100℃ had a relatively low leaching rate of about 10⁻⁵ g/(cm²· day). The stable solidification of insoluble ferrocyanides was thus accomplished by using the excellent Cs immobilization abilities of zeolite matrices (Cs trapping and self-sintering abilities).