Glycine-hydrochloric acid buffer promotes simultaneous U(VI) reduction and bioelectricity generation in dual chamber microbial fuel cell

Abstract

BackgroundA large amount of uranium-containing wastewater (UCW) is produced in the mining and smelting of uranium ore and the use of uranium. If UCW is not properly treated, it will pose a huge threat to ecology and human health. MethodsHere, microbial fuel cell (MFC) technology was introduced to removal uranium from UCW and generate bioelectricity simultaneously. To solve the low efficiency of MFC in separation uranium from UCW and to improve MFC's performance, carbon brush cathode was immersed in a new type of catholyte composed of only UCW and a glycine-hydrochloric acid buffer (GHAB). COD, pH, initial U(VI) concentration, and external resistance were all involved to obtain optimal operating conditions. SEM, EDS and XPS analyzes were conducted to investigate the removal mechanism. Significant findingsThe results indicate that the U(VI) removal efficiency was maintained above 99.0%, which was at least 22.0% higher than that without the addition of GHAB to the catholyte. Even when the U(VI) concentration in the catholyte was relatively low (20.0 mg/L), the maximum power density (Pmax) of the MFC reached to 269.5 ± 20.0 mW/m2. A high U(VI) removal efficiency and a high steady-stable performance were also achieved by the MFC even though the catholyte was extremely acidic (pH=2). Furthermore, the reduction of dissolved U(VI) to precipitated U(IV) and/or U(V) was proved to be the main reason for the removal of uranium. The present study has successfully verified that MFC with GHAB in UCW catholyte is a suitable technology for UCW treatment with high electricity generation and high U(VI) removal rate.