Due to metabolic activity of bacteria, microbial fuel cells (MFCs) can directly generate electricity by converting chemical energy of a biodegradable substrate to electrical energy. Simultaneous production of clean energy and wastewater treatment can be accomplished in these systems. In this study, phenol (100 ‐ 1,000 ppm) as a toxic model of wastewater pollutant compounds was used as the sole source of carbon and energy for growth of bacteria and concomitant power generation in a dual‐chamber MFC. Experiments were conducted in two lab‐scale systems including an air‐cathode and a bio‐cathode MFC operating in continuous mode. Anode and bio‐cathode chambers were inoculated with aerobic activated sludge from an industrial wastewater treatment plant. The highest output power was obtained at a phenol concentration of 700 ppm in both air‐cathode (25 mW m−2) and bio‐cathode (5 mW m−2) MFCs without using any co‐substrate for the first time confirming the higher performance of the air‐cathode electrode in oxygen reduction reaction. Phenol removal efficiency for an influent concentration of 700 ,ppm with an HRT of 125 min was 59.0% and 71.8% in bio‐cathode and air‐cathode MFCs, respectively. Cyclic voltammetry results confirmed involvement of both soluble and membrane‐bound mediator components in electrochemical activity of anodic biofilm.
In this work, heteroatom‐doped porous graphene was synthesized by pyrolysis method using microalgae Synechococcus elangatus as a biomass resource. The prepared samples were characterized by X‐ray diffraction (XRD), N2 sorption‐desorption, field emission scanning electron microscopy (FESEM) and X‐ray photoelectron spectroscopy (XPS). The electrochemical behavior of the synthesized samples was investigated for oxygen reduction reaction (ORR) and evaluated using microbial fuel cell (MFC).
The results revealed that the catalytic activity of the prepared sample including N, S and P atoms on porous graphene (PG) was close to the Pt/C 20 wt.%. According to the linear sweep voltammetry (LSV) measurements, the onset potential of optimal sample (0.97 V versus RHE) was close to the Pt/C 20 wt.% (0.99 V versus RHE). Furthermore, the stability test demonstrated much better tolerance to the methanol crossover effects for the optimal sample in comparison to the Pt/C 20 wt.%.
Moreover, the microbial fuel cell (MFC) test showed that the cell potential of the optimal sample is close to Pt/C 2 wt.%, and represented a high peak power density of 31.5 mW m−2, which is comparable to the Pt/C 20wt.% (38.6 mW m−2) cathodes, because of synergistic effect of N, S and P co‐doped carbon structure, which leads to improvement in catalytic activity.
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