Highly efficient removal of radioactive cesium by sodium-copper hexacyanoferrate-modified magnetic nanoparticles

Sodium-copper hexacyanoferrate-modified magnetic nanoparticles were fabricated for the highly efficient removal of radioactive cesium followed by the rapid magnetic separation of the absorbent from water. The Fe3O4 nanoparticles, synthesized using a hydrothermal method, were coated with polyethyleneimine to immobilize Cu ions through metal coordination to amine groups in the PEI. Sodium-copper hexacyanoferrate (NaCuHCF) was subsequently formed on the surfaces of the magnetic nanoparticles as Cu ions coordinated the hexacyanoferrate ions. The resulting NaCuHCF-modified magnetic nanoparticles displayed an excellent saturation magnetization value (45.2 emu/g). Batch experiments revealed that cesium adsorption equilibrium was rapidly achieved within 10 min, and the maximum adsorption capacity of the adsorbent was 125 mg/g. The adsorption kinetics and isotherms fit well to a pseudo-second order model and Langmuir isotherm, respectively. The NaCuHCF-MNPs provided a high removal efficiency exceeding 99.428% of the radioactive cesium present. The adsorbent selectively adsorbed Cs-137, even in the presence of competing cations. (C) 2016 Elsevier B.V. All rights reserved.