Mitigating cathode biofouling in membrane-less MFCs using CuO-doped activated carbon: a comparative study of batch...

Area of Science:

• Electrochemistry
• Environmental Science
• Materials Science

Background:

• Microbial fuel cells (MFCs) offer a sustainable approach to wastewater treatment and energy generation.
• Biofouling of cathode materials remains a significant challenge, hindering long-term MFC performance.
• Developing cost-effective cathode materials with enhanced catalytic activity and anti-biofouling properties is crucial for MFC commercialization.

Purpose of the Study:

• To develop and evaluate a membrane-less microbial fuel cell (MFC) system utilizing CuO-incorporated activated carbon (CuO/AC) cathodes.
• To assess the dual functionality of CuO/AC cathodes for improved oxygen reduction reaction (ORR) activity and antibacterial performance.
• To compare the performance and stability of CuO/AC cathodes against pristine AC and AC-CNTs cathodes in both batch and continuous MFC operations.

Main Methods:

• Synthesis of CuO/AC composite cathodes via wet impregnation and thermal treatment.
• Performance evaluation of MFCs with different cathode materials (CuO/AC, AC, AC-CNTs) in batch and continuous modes.
• Analysis of power density, current density, open cell potential (OCP), chemical oxygen demand (COD) removal efficiency, and biofouling resistance.
• Microscopic examination of cathode surfaces to assess microbial colonization.

Main Results:

• The 10wt% CuO/AC cathode demonstrated optimal performance, achieving a maximum power density of ~1.25 W/m² and a peak current density of ~5.2 A/m².
• CuO/AC cathodes exhibited superior long-term stability (~0.85-1.0 V OCP for >40 days) and effectively prevented biofouling compared to AC-CNTs cathodes.
• Continuous mode MFC operation showed enhanced stability and higher COD removal efficiency (~85.3%) compared to batch mode (~76.0%).

Conclusions:

• CuO incorporation into activated carbon cathodes synergistically enhances ORR activity and provides significant biofouling resistance in membrane-less MFCs.
• The developed CuO/AC cathode material shows great promise for stable and efficient wastewater treatment coupled with energy recovery.
• Continuous mode operation is advantageous for achieving superior operational stability and efficiency in MFC applications for wastewater treatment.