Promotion and mechanism of defective hematite on the power generation and phenanthrene degradation of soil microbial fuel cells

Abstract

Iron minerals can significantly impact the performance of soil microbial fuel cells (Soil-MFCs) through extracellular electron transfer (EET). Introducing defects into iron minerals has been shown to reinforce the microbial dissolution process. In this study, oxygen-rich vacancy defects were successfully incorporated into hematite (DHem), resulting in enhanced Soil-MFCs performance. Voltage measurement and Polarization curves demonstrated that the addition of DHem yielded the highest electricity output of 408.96 mV and the highest power density of 324.97 mW/m2. Liquid chromatography revealed that the system with DHem exhibited the most effective phenanthrene degradation at 61.42%, with a 40.70% increase in degradation near cathode areas. The introduction of defects led to increased dissolution of Fe(II) in hematite. The dissolved Fe(II) showed a significant positive correlation with both electricity generation and phenanthrene degradation, confirming that the introduction of defects strengthened the long-distance electron transfer capability by enhancing the dissolution of hematite. In addition, after adding iron minerals, the abundance of Petrimonas, Pseudomonas, Trichococcus, and Azoarcus was increased, which were all important function microorganisms in the system. We concluded that the introduction of defects in hematite can enhance the overall performance of Soil-MFCs by enhance electron transfer and microbial community structure.