Adsorption of Uranium by Carbon Materials from Aqueous Solutions

Uranium is both the major constituent of nuclear fuel and one of the key nuclides in spent fuel reprocessing. Separation of uranium in various aqueous effluent streams via adsorption or solid-phase extraction can not only recycle this precious resource, but also reduce the cost for the final disposal of radioactive wastes. Carbon based sorbents, at least potentially, should play a correspondingly important role for this purpose. Carbon materials were chosen as the adsorbing material because of their large specific surface area, better acid and alkaline stability and higher radiation and thermal resistance. The adsorption capacity of carbon materials can be improved by surface oxidization and other chemical or physical modifications, such as impregnating, coating, or grafting functional molecules or groups that can extract uranium selectively from liquid solution. Comparing with other modification methods, grafting technology is a promising method because of its excellent affinity and high selectivity. Uranium in aqueous wastes can be effectively removed by electrosorption onto electrode made of carbon fibers. It seems that electrosorption process for the removal of uranium has a prospect of industrialization because of the high electrosorption efficiency and the low-cost regeneration of carbon fiber electrode.