Purification of uranium-contaminated radioactive water by adsorption: A review on adsorbent materials

Environmental pollution, including in particular contamination by radioactive uranium, has become an increasingly important research focus with the expansion of nuclear power plants in efforts to meet growing global energy demand. One of the commonly used methods of water purification for radioactive water is the adsorption process because of its strong points such as fast kinetics, high selectivity, and ease of operation. Based on the importance of purification of contaminated radioactive water, this comprehensive review summarizes purification of U(VI) contaminated radioactive water depending on types of materials, synthetic methods, and adsorption mechanisms. Specifically, we classified the types of materials into four main categories: organic materials, inorganic materials, composite/nanomaterials, and framework materials. In order to maximize the adsorption capacity for U(VI), physical/chemical modifications have been explored, in addition to the manufacture of organic–inorganic hybrids. Enhanced adsorption performance through these efforts has been mainly attributed to electrostatic interaction, surface complexation, and ion exchange mechanisms. On the basis of our present understanding, further research to determine the entire process for purification of contaminated radioactive water is still required.