Magnetic copper hexacyanoferrate core–shell nanoparticles for effective cesium removal from aqueous solutions

Abstract

The commercial operation of nuclear power remains a challenge due to the contamination of ¹³⁷Cs in the release of radioactive waste. Herein, we developed an efficient strategy of ion exchange for the selective adsorption and magnetic recovery of Cs in the solution based on copper hexacyanoferrate (CuHCF) deposited on Fe₃O₄ nanoparticles (NPs). The superparamagnetic CuHCF@Fe₃O₄ NPs will make it easier to be separated from the solution. In addition, the diffusion of alkali ions in the CuHCF lattice can be controlled by modulating the chemical valence of iron centers in CuHCF. In the reduced type, CuHCF@Fe₃O₄ NPs possess a high Cs adsorption capacity of up to 273 mg g⁻¹ in 500 mg L⁻¹ CsCl solution. Even in the presence of an alkaline ion, CuHCF@Fe₃O₄ NPs exhibit a high Cs selectivity of 0.2 L mg⁻¹ as well as a high Cs removal efficiency of 98% in 100 g L⁻¹ NaCl solution. The excellent Cs removal performance of CuHCF@Fe₃O₄ NPs can be comparable to or was even better than that shown by most of the transition-metal hexacyanoferrates reported recently. Moreover, CuHCF@Fe₃O₄ NPs were favorably stable with a Cs removal efficiency of 74% after 100 loops of adsorption and regeneration.