Efficient removal of europium radionuclides from natural and seawater using mesoporous carbon-based material

Abstract

Liquid radioactive waste (LRW) presents the most significant environmental hazard due to its high aggregate activity and rapid distribution in the environment. The paper presents the structure and adsorption characteristics features of a new nanocomposite material namely mesoporous carbon (MPC). Characterization studies depicts that the material obtained consisted of bundles of carbon nanotubes coated with a uniform layer of porous carbon shell. The study on the MPC porous structure disclosed that the resulting material possess a combination of micro and mesopores with a predominant size of 1–6 nm and a specific surface area of 2360 m2 g−1. Adsorption characteristics of the MPC were studied using the sorption of 152Eu radionuclide from natural and seawater. Activated charcoal, coconut charcoal, and a gel-type strong-acidic sulfonic cation exchanger were used as reference materials. The synthesized MPC was found to have the distribution coefficients (Kd) of 152Eu over 3 × 106 cm3 g−1, which was 1–3 orders of magnitude higher than for the reference sorbents. The kinetics study of the 152Eu sorption on the MPC showed that the sorption equilibrium was attained in 5 min, three times less than the activated charcoal. High adsorption of MPC is associated with the colloidal of europium species on the developed surface of the carbon sorbent. Results conclude that the synthesized mesoporous carbon material makes a promising adsorbent for removing europium and other radionuclides, namely, cerium, lanthanum, zirconium, plutonium, and americium, from neutral solutions, where those radionuclides exist in either colloidal or pseudo colloidal form.