Adsorption and immobilization of radioactive ionic-corrosionproducts using magnetic hydroxyapatite and cold-sintering for nuclear waste management applications

Abstract

A simple and efficient method for the adsorption and immobilization of the radioactive ionic-corrosionproducts Co2+, Cr3+, Mn2+, Fe2+, Ni2+, Cu2+ and Zn2+ generated in nuclear reactor coolant has been developed using a magnetic hydroxyapatite nanocomposite (MA-HAP) and a cold-sintering technique. The structure, morphology, magnetic properties and zeta potential of synthesized MA-HAP adsorbent were studied to evaluate its suitability for cationic uptake. The incorporated magnetic nanoparticles significantly improved the Co2+ adsorption capacity of MA-HAP to 68.95 mg/g under optimized conditions such as a pH of 6, a contact time of 120 min and an adsorbent dosage of 4 g/L. More than 92% of Co2+ was removed from the simulated aqueous solution in the presence of other ionic-corrosionproducts. Densification of the nanocomposite loaded with the corrosion product was carried out using a pressure-assisted cold-sintering technique at 200 degrees C for 10 min. The sintered waste form showed high relative density (>95%) and hardness (>2.5 GPa). The results of a product consistency test indicated a low normalized leaching rate in the range 10(-6) to 10(-7)g/m(2)/day for all ions adsorbed by the MA-HAP. Thus, the material and methods introduced here are highly capable of adsorbing and immobilizing radioactive waste. (C) 2018 Elsevier B.V. All rights reserved.