Effect of Carbonate Concentration on The Adsorption of Uranium (VI) onto Amberlite IRA-402 Resin

Uranium liquid waste is generated from various nuclear energy utilization, such as uranium ore mining, fuel fabrication, spent fuel reprocessing, and 99Molybdenum production. Because of its radioactivity and toxicity, this type of waste requires effective treatment to ensure safety for human and environment. Among various technologies that have been studied, treatment of uranium liquid waste with ion exchange resins has attracted a lot of interest. Strong base anion exchange resins were found to be the most suitable option for the adsorption of liquid uranium. In this study, batch experiments of adsorption of uranium from carbonate solution were carried out using Amberlite IRA-402 resin. PHREEQC code was used for the initial modeling to determine the uranium speciation in carbonate solution with respect to pH. Adsorption kinetics of uranium on the resin was studied by determining adsorption percentage of uranium with respect to contact time of the solution with the resin. Furthermore, effect of pH of the solution to the adsorption of uranium in carbonate solution was also studied. The result of PHREEQC calculation shows that uranium predominantly formed uranium (VI) carbonate complexes, of which the speciation depends on the pH of the solution. Under the batch experimental condition, uranium (VI) carbonate complexes adsorption onto Amberlite IRA-402 was found to follow the pseudo-second-order kinetics model. The adsorption of uranium (VI) carbonate complexes increased with the increase of the pH of the solution. It suggests that the adsorption mechanism of uranium in carbonate solution was affected by the speciation of uranium (VI) carbonate complexes.