Enhancement of microbial fuel cell performance using pure magnesium anode

Abstract

MFCs (Microbial Fuel Cell) are bio-electrochemical devices that use microorganisms as biocatalysts to transform the chemical energy found in organic or inorganic compounds into electric currents. However, one of the limitations of this technology in terms of practical application is its lower electric efficiency, which greatly depends on the selection of anode material and the types of waste water used. In this work, organically rich wastewater and pure magnesium anode materials were utilized. Also, to investigate the effect of electrode size on power generation, five different sizes of coin-shaped anodes were employed for the variation in anode size, whose diameter and thickness were (15 mm × 2 mm), (20 mm × 2 mm), (20 mm × 3 mm), (20 mm × 4 mm), and (25 mm × 2 mm) with corresponding surface areas [2πr(r+h)] are 448 mm 2, 754 mm 2, 817 mm 2, 880 mm 2 and 1139 mm 2, respectively. The maximum obtained current density, power density, and energy densities were 4734.26 mA/m2, 37400.625 mW/m2 and 81.59 kW-h/kg respectively, by the smallest anode of size (15 mm × 2 mm). This investigation showed that a reduction in the size of the anode decreases the loss in the activation zone. As a result, from the smallest anode, maximum power and energy output were obtained. Finally, this analysis outlines the process and approaches for MFC to produce more power at a potentially lower cost. It is noted that same waste water has been used throughout the study where surface area of the samples vary from lowest to highest level.