Novel carbon-ceramic composite membranes with high cation exchange properties for use in microbial fuel cell and electricity generation

Abstract

Actually, there are different configurations used in microbial fuel cells (MFCs) with presence or absence of an ion exchange membrane between their electrodes. Specifically, MFCs that use membranes have the objective of avoiding the diffusion of oxygen and substrate between the anodic and cathodic compartment, and to achieve a correct transfer of protons from one chamber to another. In this regard, the current study seeks to prepare and characterize new composite membranes using as precursors three types of carbonaceous materials such as bone char, coconut shell activated carbon and bituminous activated carbon and natural clay. The composite membranes of bituminous activated carbon and clay showed more promising specific conductivity (42%) than the one made with pure clay. The physicochemical properties of the membranes and their precursors were elucidated by SEM/EDX analysis, IR spectroscopy, nitrogen adsorption isotherms at 77 K and optical microscopy. Further, membranes performance was assessed using microbial fuel cells (MFCs) where the composite membranes prepared with clay-bituminous carbon reached the highest voltage values (0.95–1.02 V) in open circuits, while that reached a maximum power density of 0.699 W/m3 at a current density of 4.012 A/m3 in closed circuit. This behavior is associated with the high content of silicon and aluminum in bituminous activated carbon, which favored the proper functioning of membranes in the MFCs. Specifically, with this type of cells, energy recovery of 0.0057 kWh/m3 and 0.1322 kWh/kg chemical oxygen demand (COD) removed, which indicates an extra economic income of the order of $0.0025/kg COD. Finally, the produced power was demonstrated in prototypes to power LED and four digital clocks. This novel clay-bituminous activated carbon showed promising cost-effectiveness and sustainable energy generation, which may be suitable for wastewater treatment.