Soot collected from the exhausts of diesel trucks contained carbon nanoparticles shaped like nano-onion rings which were used to craft a microbial fuel cell. Credit: Shiv Singh
Materials scientists have converted particles from vehicle exhaust soot into electrodes for a microbial fuel cell that can clean up wastewater and generate electricity1.
The electrodes can also be used to make energy storage devices such as capacitors, say researchers at the CSIR-Advanced Materials and Process Research Institute in Bhopal, Madhya Pradesh.
The scientists, led by Shiv Singh, collected soot from the exhausts of diesel trucks. This contained carbon nanoparticles shaped like nano-onion rings. They doped the particles with specific salts, which added nitrogen and sulfur atoms.
They then synthesised electrodes – anode and cathode – using the doped particles. The electrodes were put in separate chambers and connected via an external circuit. Domestic wastewater was added as an electrolyte in the anode chamber and a separate electrolyte in the cathode chamber.
This gave rise to a microbial fuel cell. Bacteria present in the wastewater formed a biofilm and degraded waste organic matter, generating electrons which travelled to the cathode via the external circuit, triggering an oxygen reduction reaction. This process generates electricity.
After 10 days, the fuel cell was able to reduce chemical oxygen demand – a measure of pollutants in the wastewater – by almost 70%, outperforming other microbial fuel cells.
The electrode materials made of the doped soot particles were stable and showed no considerable change in peak currents after repeated use.
