Synthesis and performance of a cathode catalyst derived from Bauhinia accuminata seed pods in single and stacked microbial fuel cell.

Abstract

The cathode catalyst in microbial fuel cell (MFC) plays a crucial role in scaling up. Activity of biomass-derived activated carbon catalysts with appropriate precursor selection in a natural clay membrane-based MFC of 250 mL was studied. The performance of scaled up MFC of 1.5 L capacity with two different configurations was monitored. Rod-shaped particles with slit-type pores and amorphous graphitic nature with a surface area of 800.37 m²/g was synthesized. The intrinsic doping of heteroatoms N and P in the catalyst was with atomic weight percentages of 4.5 and 3.5, respectively and the deconvolution of N1 spectra confirmed pyridinic N and graphitic N content of 17.3% and 34.1% validating its suitability as a cathode catalyst. Electrochemical characterization of the catalyst coated SS mesh electrode confirmed that a loading of 5 mg/cm² rendered higher catalytic activity compared to bare SS mesh. The maximum power density in catalyst modified cell was 0.91 W/m³ compared to 0.02 W/m³ as obtained in a plain stainless steel electrode cell at a COD removal efficiency of 93.3%. Series, parallel, and parallel-series combinations of 6 cells showed a maximum voltage of 4.15 V when connected in series and a maximum power density of 1.54 W/m³ when connected in parallel. System with multielectrode assembly achieved better power and current density (0.84 W/m³ and 1.97 A/m³) than the mixed parallel series circuitry (0.7 W/m³ and 0.57 A/m³). These performance results confirm that the catalyst is effective in both stacked and hydraulically connected system.

Key findings

• ▸The catalyst showed higher catalytic activity when loaded at 5 mg/cm² on a SS mesh electrode.
• ▸The maximum power density in the catalyst modified cell was 0.91 W/m³, a significant improvement over the plain stainless steel electrode cell.
• ▸The catalyst was found to be suitable for use as a cathode catalyst in MFCs, with a high surface area and intrinsic doping of heteroatoms N and P.

Keywords

Identifiers

DOI

10.1007/s11356-023-27845-x

Journal

Environmental Science and Pollution Research

Year

2023