Polyaniline-modified iron oxide nanoparticles to improve the overall performance of MFC-BOD sensors

Biochemical oxygen demand (BOD) has attracted considerable attention as an important indicator of water pollution. Microbial fuel cells (MFC) are considered a promising method for BOD detection. In this work, the MFC-based BOD sensor was proposed considering the performance and cost factors, and the anode material was modified by iron oxide nanoparticles (IONPs) to improve the detection performance of the sensor and enable targeted selection of microorganisms, resulting in the dominant bacterial group accounting for 92.39 % of the total bacterial group. Polyaniline (PANI) was used as an adhesive to enhance the electrical performance of the anode material. The composite anode (CE) has superior electrical properties and biocompatibility compared to traditional carbon felt materials. The modified MFC sensor ensures the accuracy of detection and can detect BOD within 20 min with a detection limit of 73.3–440 mg/L. In addition, a good correlation (R 2  = 0.9969) was obtained between the BOD concentration and the actual performance, which proved the suitability of the system for real wastewater. The whole BOD detection system has the advantages of fast sensing speed, large detection range and easy operation while ensuring accuracy, which has high potential for engineering applications.