Microporous nitrogen-rich biomass derived anode catalyst in clay membrane MFC for kitchen wastewater treatment.

Microbial fuel cells (MFC) have emerged as a sustainable wastewater treatment technique that offers simultaneous energy generation; however, the high cost of electrodes and their reduced catalytic activity have hindered their widespread adoption. To overcome this, an activated carbon synthesised from Areca nut husk was coated on different anodes viz. Carbon cloth and Stainless Steel (SS) mesh. Activated carbon was found to be highly porous with a carbon content of 85.39%, and a surface area of 767.98 m2/g, and was found to be amorphous with a high degree of graphitic structure. The electrical conductivities of the catalyst-coated SS mesh and carbon cloth were comparable, and the performance of the MFC was studied using both electrodes as anodes. A batch MFC with modified SS mesh as anode exhibited the highest power density of 155.35 mW/m3 in synthetic wastewater and 101.68 mW/m3 in kitchen wastewater, with COD removal efficiencies of 95.32% and 95.24%, respectively. In a continuous mode, the MFC delivered a maximum current density and power of 52.38 mA/m2 and 21.60 mW, respectively, with a maximum COD removal efficiency of 80.70% for an HRT of 20 hrs. These findings underscore the viability of using biomass-derived activated carbon as an anode catalyst in both batch and continuous modes of MFC.

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

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.

Synthesis and performance of a cathode catalyst derived from areca nut husk in microbial fuel cell.

The role of the cathode catalyst is crucial in a single chamber Microbial Fuel Cell (MFC) to overcome the energy barrier. The present work aims todevelop a metal-free cathode catalyst from anagro-waste, areca nut husk and to evaluate its performance in MFC. Activated carbon with amorphous graphitic structure was synthesised at a pyrolysis temperature of 500 °C from the areca nut husk. The surface area of activated carbon is 1261.6 m2/g with an average particle size of 35.23 µm. The electrochemical characterisation of the cathode in oxygen saturated atmosphere reveals, a loading rate of 5 mg/cm2 possesses an equivalent conductivity to that of Pt catalyst. An Open Circuit voltage of 864 mV with a power density of 590 mW/m2 and a current density of 1.03517 A/m2 at 611.8 Ω was obtained. These results make the novel metal free catalyst a potential alternative to metal-based catalysts.