Graphitized corncob 3D Biomass‒driven anode for high performance batch and continuous modes Air‒Cathode microbial fuel cells working by domestic wastewater

Abstract

Effective 3D anode was prepared by graphitization of corncob biomass at high temperature under an inert atmosphere. As an anode in the microbial fuel cells, the proposed electrode revealed very good performance in both batch and continuous modes when the process parameters were optimized. The physicochemical characterizations indicated that the surface of the prepared anode is decorated by micro porous layers array and composed of SiO2‒incorporated graphite. Moreover, investigation the electrical properties showed very good electrical conductivity dependent on the preparation temperature; 6.9, 8.6 and 8.9 S/m for the electrode prepared at 900, 1000 and 1100 °C, respectively. The performance of the proposed anode was evaluated in air‒cathode single chamber microbial fuel cell driven by domestic wastewater without using exterior microorganisms. The electrochemical measurements, for the batch mode cell, displayed high power density generation upon utilizing the corncob electrode compared to commercial anodes; 100 ± 8, 135 ± 11 and 2010 ± 85 mW/m2 from cells assembled using carbon paper, carbon cloth and corncob‒1100 °C, respectively. Moreover, addition of sodium acetate strongly enhanced the cell performance as the generated power density was increased from 475 ± 30 to 1963 ± 90 mW/m2 after addition of the salt (5 g/l), however the experimental results indicated that 5 g/l is the optimum salt concentration. In a continuous mode cell, the results concluded that the proposed 3D anode can be used fresh or after colonization of a biofilm. Interestingly, the generated power from the continuous mode cell is higher than the batch mode system due to mass transfer resistance elimination.