Microbial fuel cells: enhancement with a polyaniline/carbon felt capacitive bioanode and reduction of Cr(VI) using the intermittent operation

With the increasing concern for energy sources, waste management, the search for novel technological solutions continues. Microbial fuel cell is a new biotechnology that utilizes bacteria as catalysts to decompose organic substrate and simultaneously harvest electricity. Anodes play an important role in deciding the microbial fuel cell. In this paper, the cumulative charge of the polyaniline-modified bioanode from the chronoamperometric experiment with 20 min of charging and 20 min of discharging is 13,930.1 C m(-2), much higher than that of bare carbon felt anode (5908.1 C m(-2)). Then, we investigated two different operations of the microbial fuel cell (intermittent and continuous operations) to remove Cr(VI) in the cathode chamber. Under intermittent operation, 71.1% of Cr(VI) was reduced, which was 1.13-fold greater than under continuous operation. This study suggested that the microbial fuel cell anode containing polyaniline pseudo-capacitive materials has the potential for storing energy from wastewater and releasing the energy in a short time to an electronic device. These favorable Cr(VI) removal results contribute to the capacitive anode in the charging process of intermittent operation, produce and store electricity simultaneously, and release a greater portion of the electricity stored in the anode than under continuous operation in the process of degradation, thereby gaining a larger current. Here we show that a microbial fuel cell containing a pseudo-capacitive material, such as polyaniline, functions as a biocapacitor, stores bioelectrons generated from microbial oxidation of substrate, and releases the accumulated charge simultaneously.