A simple synthesis of bio-based cathode catalyst of microbial fuel cell with bio-oil recovery through pyrolysis of defatted yeast-biomass

Biomass of plant, yeast and bacterial origin is a promising source of activated biochar or carbon for electrode and catalytic material applications, as it is abundant, diverse, and inexpensive. In this work, the defatted biomass of Meyerozyma caribbica, an oleaginous yeast, was used as the feedstock for biochar production. Activated yeast biochar that was synthesized by using KOH in a single-step one-pot process carried out at 700 °C was found to have a honeycomb-like structure with a surface area of around 412 m2/g. The porous activated-biochar exhibited good electrical properties when applied as a cathode-catalyst material of a microbial fuel cell (MFC). Both coulombic and COD removal efficiencies increased by 1.9 and 1.3 times, respectively, as compared to bare carbon-felt as the cathode. In contrast, the internal resistance of the MFC using activated-biochar-based cathode decreased by 2.6-fold as compared to MFC using carbon felt as cathode. The investigation suggested that defatted yeast-based modified bio-charcoal could be a promising carbon-enriched biomaterial for synthesizing cathode catalyst for application in MFCs. This one-pot process of synthesizing cathode catalyst is based on a net zero-discharge approach with concomitant bio-oil recovery.