Efficacy of Cu(II) as an electron-shuttle mediator for improved bioelectricity generation and Cr(VI) reduction in microbial fuel cells

Cu(II) ion was employed as an electron-shuttle mediator to enhance bioelectricity output and accelerate reduction rate of Cr(VI) in a dual-chamber microbial fuel cell (MFC). In the presence of Cu(II), power density and the Cr(VI) reduction rate were 1235.53 mW m −2 and 1.191 g m −3  h −1 , respectively, which were 1.44 times and 1.17 times than that of MFC in the absence of Cu(II). A series of electrochemical analysis confirmed the presence of Cu(II) can diminish overpotential and diffusional resistance of MFC, further accelerating electrochemical reduction process of Cr(VI) via an indirect mechanism. After reduction, Cr(VI) and Cu(II) in this work were mainly deposited on cathode electrodes in the form of Cr(OH) 3 and little Cu, thus wastewater containing Cr(VI) was successfully treated by bio-electrochemical technology. The aim of this work was to study the efficacy of Cu(II) as an electron-shuttle mediator for improved bioelectricity generation and Cr(VI) reduction in MFCs.