Industrial & Engineering Chemistry Research, Vol.55, No.15, 4195-4207, 2016
Nanostructured Metal Oxide Sorbents for the Collection and Recovery of Uranium from Seawater
The ability to collect uranium from seawater offers the potential for a long-term green fuel supply for nuclear energy. However, extraction of uranium, and other trace minerals, is challenging because of the high ionic strength and low mineral concentrations in seawater. Herein we evaluate the use of nanostructured metal oxide sorbents for the collection and recovery of uranium from seawater. Chemical affinity, chemical adsorption capacity, and uptake kinetics of sorbent materials were evaluated. Materials with higher surface area clearly produced better sorbent performance. Uptake kinetics showed that the materials could rapidly equilibrate in a few hours with effective solution contact. Manganese, iron oxide, and especially Mn-Fe nanostructured composites provided the best performance for uranium collection from seawater. The preferred materials were demonstrated to extract uranium from natural seawater with up to 3 mg U/g-sorbent in 4 h of contact time. Inexpensive nontoxic carbonate solutions were demonstrated to be an effective and environmentally benign method of stripping the uranium from the metal oxide sorbents. Various formats for the utilization of the nanostructured metals oxide sorbent materials are discussed, including traditional methods and nontraditional methods such as magnetic separation.