Removal of uranium from aqueous wastes using electrically charged carbon nanofibers

Abstract

The presence of aqueous uranium wastes is a problem in the United States and their treatment/disposal is desirable. Treatment methods have been developed but result in concentration opposed to conversion to a disposable form. This technique involves recovery of uranium as a solid, providing an advantage over other methods. The technique utilizes carbon nanofibers as electrodes which successfully electrosorb uranium ions. Fibers with varying surface characteristics were evaluated in the removal process and all were determined to be equally and extremely effective. Various experimental parameters were evaluated including applied potential, pH, and flow rate. The critical applied potential at which significant removal is achieved is between-0.3 and-0.4 V. Decreasing pH hinders the electrosorption process while increasing it enhances the process. As expected, an increase in flow rates results in decreased removal. It was determined that cyclic loading/unloading increased fiber performance and a capacity of at least 5.45 g uranium /g carbon can be achieved. These results illustrate that this technique can be effectively implemented to solve current waste management problems.