Amine-abundant magnetic chitosan beads incorporated with potassium copper hexacyanoferrate for cesium ion removal and facile magnetic recovery

Abstract

Potassium copper hexacyanoferrate (KCuHCF)-incorporated magnetic chitosan bead (HMC) was synthesized for selective $Cs^+$ removal in aqueous solution and facile recovery of the spent adsorbent. The amino-functionalization of the synthesized magnetic chitosan bead was successfully completed by simple grafting methyl acrylate and diethylenetriamine without crosslinking. The additional introduction of amino functionality brought the enriched $Cu^{2+}$ ions on the bead surface to make following sufficient KCuHCF synthesis effective. Consequently, the HMC exhibited high $Cs^+$ capacity calculated to be $136.47 mg g^{-1}$ from the Langmuir model and the equilibrium was established within 4 h. Moreover, the HMC revealed excellent stability in a wide pH range from 4 to 11 and outstanding $Cs^+$ selectivity (>97%) in seawater ($1.11 mg L^{-1} Cs^+$). In the practical point of view, the HMC was stable during five successive adsorption cycles and easily recovered by magnets, guaranteeing the continuous operation to decontaminate large volume of wastewater.