Ferroferric oxide loads humic acid doped anode accelerate electron transfer process in anodic chamber of bioelectrochemical system

Abstract

Humic acid as electron shuttle plays an important role in accelerating electron transfer of natural biogeochemical transformation. Exploration of the potential application of humic acid would provide new ideas for the development of bio-electrochemical system. Herein, the electron transfer availability of humic acid was evaluated by microbial fuel cell (MFC) device that has electricity output characteristic. Super-capacitor ferroferric oxide was used to load humic acid to form a stable wrappage (HA@Fe3O4) as the doped materials. The results were proved that humic acid reduced the metabolic overpotential of microorganisms and thus greatly improve electron transfer efficiency between anode and microbes. A maximum power density was produced up to be 1487.06 mW m−2 in the MFC with HA@Fe3O4 doped anode, which has higher chemical oxygen demand removal efficiency and electron utilization rate than undoped anode. Moreover, the existence of Fe3O4 accelerates the electron transfer process between humic acid and the anode, further reducing the energy consumption required for electron transport, HA@Fe3O4 doped anode has good stability could provide a wider substrate utilization range for the growth of microorganisms, providing a high-performance output to MFC. This research provides a basis for the application of humic acid on development of bio-electrochemical system due to its electron shuttle ability.