Development of an Osmium Redox Polymer Mediated Bioanode and Examination of its Performance in Gluconobacter oxydans Based Microbial Fuel Cell

Gluconobacter oxydans (G. oxydans) cells together with an osmium redox polymer (ORP) [Osmium (2,2’-bipyridine)2(poly-vinylimidazole)10Cl]Cl were combined with a glassy carbon paste electrode (GCPE) to form a bioanode for a microbial fuel cell (MFC) based on G. oxydans. Although there are G.oxydans/ ORP combined bioanode in the literature, as far as it is known, this system is the first one where G.oxydans/ORP bioanode is combined with a cathode and a MFC is formed. After the optimization of experimental parameters, analytical characteristics of ORP/G. oxydans/GCPE bioanode were investigated. ORP/G. oxydans/GCPE showed two linear ranges for ethanol substrate as 1.0–30 mM (R²=0.902) and 30–500 mM (R²=0.997) and analytical range as 1.0–1000 mM. Limit of detection (3.0 s/m) and limit of quantification (10 s/m) values were calculated as 1.29 mM and 4.30 mM respectively where the RSD value was 1.16 % for n=5. Combining the developed bioanode in the presence of 5.0 mM K₃Fe(CN)₆ mediator with a Pt wire cathode a double compartment MFC was obtained via a salt bridge. G. oxydans/GCPE bioanode based MFC had maximum power density of 0.133 μW cm⁻² (at 33.5 mV), maximum current density as 8.73 μA cm⁻² and OCP value of 156 mV. On the other hand, ORP/G. oxydans/GCPE based MFC showed maximum power density as 0.26 μW cm⁻² (at 46.8 mV), maximum current density as 15.079 μA cm^-2 and OCP value of 176 mV.