Novel approach for removing iron-cyanide complex ions and cesium ions from solutions using hydrogel-like beads

In the process of recycling cyanide leaching solutions, the presence of iron-cyanide complex ions in gold leaching solutions leads to increased cyanide consumption and competition with gold for adsorption onto activated carbon. Consequently, the removal of iron- cyanide complex ions from cyanide leaching solutions is crucial. This study presents a novel strategy for the treatment of metal ions in leaching solutions, achieving effective waste treatment using hydrogel-like beads. To remove iron-cyanide complex ions from cyanide leaching solutions, we synthesized carboxymethyl cellulose‑iron (CMCFe) hydrogel through a crosslinking method. The adsorbent, carboxymethyl cellulose-Prussian blue (CMC-PB) hydrogel, obtained after iron-cyanide complex ion adsorption, can directly remove Cs+ ions from solution without the need for desorption and regeneration. Notably, the CMC-Fe hydrogel exhibits exceptional adsorption performance and high selectivity toward iron-cyanide complex ions. The adsorption process of the CMC-Fe hydrogel follows a pseudo-second-order kinetic model, while the Freundlich isotherm model is more suitable for describing the adsorption equilibrium. Additionally, the CMC-PB hydrogel efficiently adsorbs 83.1% of Cs+ ions at a dosage of 86.5 μg, and desorption and regeneration studies reveal that its adsorption efficiency remains high even after three cycles. Furthermore, the proposed adsorption mechanism of CMC-PB for Cs+ ions involves a combination of chemisorption (K+/Na+ exchange) and physisorption (hole channels of hydrogels).