Effect of Sediment Porosity on Electrochemical Performance of Marine Sediment Microbial Fuel Cells and Analysis of Organic Matter Diffusion

During the long-term operation of marine sediment microbial fuel cell (MSMFC) on the ocean floor, the sediment porosity affects the horizontal diffusion coefficient of organic matter near the anode,which finally influences the anodic electrochemical performance and the power output of cells. In this paper, the sediment with different sediment porosities is established in lab by artificially adjusting sediment porosity to investigate its influence on the performance of MSMFC, so as to creatively build the mathematical relationship between the energy production of MSMFC and the horizontal diffusion coefficient. With the increase of sediment porosity, the anode kinetic activity decreases and then increases, the highest kinetic activity is 3.85 times higher than the lowest kinetic activity. When the sediment porosity is 45.2%, the maximum power output reaches 206.8 mW/m2. Horizontal diffusion coefficient of organic increases with an increase in sediment porosity, and it has a linear relationship with the energy production of MSMFC. When the sediment porosity is 45.2%, the horizontal diffusion coefficient is 0.48 m2/s, and the energy production of MSMFC reaches 804.04 J. These results render a technological base for the site choice of MSMFC deploying in different marine sediments, anode design and battery operation for long term.