Enhanced detection of toxicity in wastewater using a 2D smooth anode based microbial fuel cell toxicity sensor

As the biological recognition element of microbial fuel cell (MFC) toxicity " shock" sensors, the electrode biofilm is perceived to be the crucial issue that determines the sensing performance. A carbon felt and indium tin oxide (ITO) film anode were utilized to examine the effects of anodic biofilm microstructure on MFC toxicity sensor performance, with Pb2+ as the target toxicant. The carbon felt anode based MFC (CF- MFC) established a linear relationship of Pb2+ concentration (CPb2+) vs. voltage inhibition ratio (IR2h) at a CPb2+ range of 0.1 mg L-1 to 1.2 mg L-1. The highest IR2h was only 38% for CF- MFC. An ITO anode based MFC (ITO- MFC) also revealed a linear relationship between CPb2+ and IR2h at CPb2+ of 0.1 mg L-1 to 1.5 mg L-1 but better sensing sensitivity compared with the CF- MFC. The IR2h of ITO- MFC gradually approached 100% as CPb2+ further increased. The enhanced sensing sensitivity for the ITO anode possibly originated from the thin biofilm that resulted in the efficient exposure of exoelectrogens to Pb2+. The employment of 2D conductive metal oxide with a smooth surface as the anode was able to increase the MFC sensing reliability in real wastewater.