Electrochemical Bioremediation of Uranium (VI) Using Geobacter Sulfurreducens on a Boron Doped Diamond Electrode Surface

Abstract

Developing nuclear science and technology has increased nuclear waste containing uranium. The contamination associated with nuclear activity is a significant concern for human and environmental health. Due to the high toxicity, radioactivity, and extensive half-life of uranium, it is necessary to find means to remediate contaminated environments, bioremediation being an alternative. Microorganisms can reduce, eliminate, contain, or transform hazardous waste such as radionuclides. This work proposes using Geobacter sulfurreducens to reduce uranium (VI) to uranium (IV). The research consists of electrochemical processes for the G. sulfurreducens' immobilization using boron-doped diamond electrodes (BDD) as electron donors. Taking advantage of the microbial metabolic processes and using U (VI) as an electron acceptor, we can reduce the ion to U(IV) - the electrochemical methods involve using a BDD electrode coupled with Geobacter sulfurreducens. First, using the chronoamperometry technique, a potential of -600mV (vs. Ag/AgCl) was applied. In this way, G. sulfurreducens was immobilized on the BDD electrode surface. After the bacteria immobilization process, a 2mM solution of uranyl acetate was added, an applying the reduction potential oof -600mV, the uranyl ion was reduced and removed from the solution. the bacteria electrochemical immobilization was suggested first due to the changes in current with respect time. This process with G. sulfurreducens was demonstrated with scanning electrode microscopy (SEM), where the bacterium was observed modifying the BDD electrode surface. In the same way, the uranium electrochemical reduction process using the immobilized bacteria on the electrode was suggested and corroborated. Moreover, using SEM and energy dispersive X-ray spectroscopy (EDS), the uranium electrochemical remotion using G. sulfurreducens and the presence of this element on the BDD electrode surface were identified. Finally, Raman spectroscopy analysis was used to determine the uranium species present on the electrode surface. The results obtained help in the advancement of the electrochemical bioremediation processes for the treatment of hazardous waste in the environment. Figure 1