Sulfonated Fe3O4/PES nanocomposites as efficient separators in microbial fuel cells

In this paper, different self-made membranes based on polyethersulfone (PES) with sulfonated nano-Fe3O4 (Fe3O4-SO3H) were tested in H-Type Microbial Fuel Cell system. The nanomaterials were characterized by FTIR, SEM, TEM and TGA, while the nanocomposite membranes by tensile tests, TGA, SEM, and profilometry. The presence of sulfonic groups (-SO3H) within the polymer matrix allowed a better dispersion of nanoparticles and prevented oxygen permeation from the cathodic compartment. Different amounts of filler, ranging from 5 wt% to 20 wt%, were adopted to establish an optimal content for enhancing the electrochemical performances as Power density (PD), Current intensity (CI) and Open Circuit Voltage (OCV), without altering the mechanical and thermal stability of the synthesized materials. PES with 10 wt% of sulfonated Fe3O4 resulted the best formulation among those analyzed with properties superior to commercial Nafion 117 membrane, with an OCV and a Coulombic efficiency equal to 868.09 mV and 29.58%, respectively. The maximum power and current densities improved by 270% and 117% compared to Nafion 117, respectively.