Novel application of nanoscale zero valent iron and bimetallic nano-Fe/Cu particles for the treatment of cesium contaminated water

Following the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, radioactive cesium was released into the environment in large amounts and heavily contaminated drinking water in Fukushima and neighboring prefectures. In this research, the capability of nanoscale zero valent iron (nZVI) and bimetallic nano-Fe/Cu particles for cesium removal from aqueous solutions was evaluated for the first time. The nanoparticles were characterized by TEM, XRD, SEM-EDS and BET-N₂ adsorption. The effect of several variables such as initial cesium concentration, contact time, pH, temperature, competing cations and dosage of the nanoparticles on the sorption behavior of cesium was studied using a batch technique. The obtained results showed that nZVI and nano-Fe/Cu particles displayed effective performance for removal of cesium. For both nanoparticles, the removal efficiency exceeded 99% at initial cesium concentration of 1mg/L and 1g/L doses. The experimental data were well fitted to the pseudo-second-order kinetic model, which means that the overall rate constant of cesium sorption process was controlled by chemisorption. The rate constant of nano-Fe/Cu particles was larger than that of nZVI, indicating a faster kinetic sorption by nano-Fe/Cu particles. The thermodynamic parameters indicated exothermic and spontaneous nature of the sorption process. The Langmuir, Freundlich and Redlich-Peterson isotherm models were also used to fit the equilibrium data. nZVI and nano-Fe/Cu particles exhibited excellent selective sorption toward cesium in the simulated contaminated water after Fukushima accident. The current work demonstrated that nZVI and nano-Fe/Cu particles can be considered as promising materials for cesium removal from contaminated waters.