High-density immobilization of potassium copper hexacyanoferrate in poly(acrylic acid)/laponite hydrogel for enhanced Cs+ removal

As the risk of radioactive waste generated in large quantities is emerging, rapid and selective removal and decontamination of cesium ions (Cs + ) from nuclear waste have become a significant issue for environmental protection and human health. Herein, a novel potassium copper hexacyanoferrate (KCuHCF)-embedded poly(acrylic acid)/laponite (PAAc/Lap-HCF) hydrogel has been developed by a facile and low-cost fabrication route for highly effective and selective Cs + adsorption. The diffusion-derived KCuHCF formation in the nanocomposite hydrogel via layer-by-layer (LBL) assembly can facilitate the preservation of the 3D-interconnected hydrogel structure and the dispersion of KCuHCF particles, which contribute to high-density immobilization of stable KCuHCF (~57.73 wt%) in the matrix. The adsorbent shows enhanced Cs + removal properties in terms of fast kinetics (>90% removal for 20 mg/L of Cs + within 1 h), stability (>115 mg/g in wide pH value of 2–11), high adsorption capacity (146.22 mg/g) and selectivity ( K d = 1.3 ×10 5 mL/g, 1 mg/L Cs + in highly competitive seawater). Such excellent characteristics with fast kinetics are mainly due to the high ion accessibility from the inherent nature of hydrogels and the highly loaded KCuHCF particles in the composites. The adsorption kinetics and isotherm obey the pseudo-second-order model and the dual-site Langmuir adsorption model, respectively. This nanocomposite hydrogel prepared in our work shows enhanced performance on removal of Cs + in aqueous solution, which has a good application prospect in treating radioactive wastewater .