Bioanodes containing catalysts from onion waste and Bacillus subtilis for energy generation from pharmaceutical wastewater in a microbial fuel cell

• Published in: New journal of chemistry Vol. 45; no. 28; pp. 12634 - 12646
• Main Authors: Duarte-Urbina, O. J., Rodríguez-Varela, F. J., Fernández-Luqueño, F., Vargas-Gutiérrez, G., Sánchez-Castro, M. E., Escobar-Morales, B., Alonso-Lemus, I. L.
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 28.07.2021
• Subjects: Anodes; Biochemical fuel cells; Biofilms; Catalysts; Configuration management; Fuel cells; Graphene; Heating; Maximum power density; Microorganisms; Microwave heating; Onions; Pharmaceuticals; Pyrolysis; Substrates; Wastewater
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/D1NJ01726H

We propose the integration of bioanodes composed of onion waste (OW)-derived biocarbon catalysts + Bacillus subtilis ( B. subtilis ) for application in a microbial fuel cell (MFC). OW is activated by pyrolysis and the resulting catalysts are functionalized with methanol by intermittent microwave heating (IMH). The functionalized-activated onion waste (FAOW) catalysts are labeled as FAOW4, FAOW6, and FAOW8 after treatment at 400, 600, and 800 °C, respectively. As a comparison, an N-doped graphene catalyst (FNSG) is also studied. The substrate in the anode chamber of the MFC is highly recalcitrant pharmaceutical wastewater (PWW, pH = 9.2). The XRD results show that the FAOW catalysts have an amorphous structure, contrasting with the crystalline pattern of FNSG. It is shown that microwave heating has only a slight effect on the structural order of the FAOW series while promoting disorder at FNSG. Testing in half-cells show that the current density ( j ) increases at anodes in the order FAOW8 > FAOW6 > FAOW4. The j values increase even more at full bioanodes after growing a biofilm of B. subtilis on the catalyst layer of FAOW8 and FAOW6. In MFC tests, the FAOW8 + B. subtilis bioanode can produce a maximum power density ( P cell ) of 30.72 mW m −2 , sustaining high performance during a 14-day long-term test. Therefore, FAOW8 and B. subtilis are proposed as a highly performing catalyst–biofilm configuration to generate energy from PWW in an MFC.