(117ae) Zinc Hexacyanoferrate Composite from Temperature-Controlled Pyrolyzed ZIF: Electrochemical Adsorption of Cesium Ions in Aqueous Solutions

137-Cesium is a significant radioactive isotope that requires removal from the nuclear waste that is produced after nuclear power generation. The aim of this research is to selectively remove cesium ions using a zinc hexacyanoferrate (ZnHCF) composite electrode, which has been designed using ZIF-8 based carbon (ZDC) as support. This study primarily focuses on the influence of the decomposition temperature of ZIF-8 on the formation of the composite and the performance of removing non-radioactive cesium ions selectively. The synthesis of highly conductive and uniformly distributed ZDC was achieved at an optimized temperature of 700 ℃, and it exhibited a remarkable cesium adsorption capacity of 204.9 mg g^-1. To evaluate the practical performance of the electrode, selectivity tests were conducted in the presence of competing ions. The selectivity of the electrode remained high under Na⁺ rich (Na/Cs = 1330, K_d (mL g^-1) = 1.04 x 10⁵) and K⁺ rich (K/Cs = 133, K_d (mL g^-1) = 7.24 x 10⁴) conditions, with over 95 % of cesium ions removed under groundwater conditions. The adsorption of cesium ions was found to be reversible over five cycles, with complete desorption achieved after the fourth cycle. Moreover, the cesium ion adsorption mechanism was proven to be structural adsorption through oxidation-reduction and phase changes of ZnHCF-ZDC. and it was also shown to be a stable adsorption system. This research is significant as it is the first to apply a composite electric adsorbent using ZIF-based carbon support to remove cesium.