Recovery and separation of uranium in a microbial fuel cell using a titanium dioxide nanotube array cathode

Uranium is a common radionuclide contaminant in groundwater. Recovery of uranium from uranium-containing water can achieve the dual purposes of uranium remediation and uranium resource utilization. However, very few studies have successfully achieved this task. In this study, we developed a microbial fuel cell (MFC) system with a titanium dioxide nanotube array (TNTA) cathode, which could efficiently remove (over 95%) and recover (over 97%) uranium from uranium-containing water. Results demonstrated that the removal of U(vi) in the MFC was through an adsorption-reduction-deposition mechanism. U(vi) was adsorbed by the TNTA cathode, and the adsorbed U(vi) was further electroreduced to U(iv)O-2 and deposited on the surface of the TNTA cathode. The reduction of adsorbed U(vi) initiated re-equilibration of the desorption reaction of adsorbed U(vi) and induced re-adsorption of U(vi). The re-adsorbed U(vi) could be further electroreduced to U(iv)O-2, which resulted in the continuous removal of U(vi). Finally, 2.95 mu mol U(vi) was reduced and deposited as U(iv)O-2 on the surface of the TNTAs (1476.22 mu mol m(-2)) without observing capacity saturation. Moreover, the deposited U(iv)O-2 can be easily separated from the TNTA cathode with dilute nitric acid, and the TNTA cathode can be used repeatedly with stable performance.

Automated summary

In this study, a microbial fuel cell system with a titanium dioxide nanotube array cathode was developed to efficiently remove and recover uranium from groundwater. The removal of U(vi) was achieved through an adsorption-reduction-deposition mechanism, demonstrating that the adsorbed U(vi) could be further electroreduced to U(iv)O-2 and deposited on the cathode surface, allowing for continuous uranium removal.