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

Abstract

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 (C_Pb²⁺) vs. voltage inhibition ratio (IR_2h) at a C_Pb²⁺ range of 0.1 mg L⁻¹ to 1.2 mg L⁻¹. The highest IR_2h was only 38% for CF-MFC. An ITO anode based MFC (ITO-MFC) also revealed a linear relationship between C_Pb²⁺ and IR_2h at C_Pb²⁺ of 0.1 mg L⁻¹ to 1.5 mg L⁻¹ but better sensing sensitivity compared with the CF-MFC. The IR_2h of ITO-MFC gradually approached 100% as C_Pb²⁺ 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.