Modification of graphite anode with chitosan loaded with iron oxide and carbon nanotubes nanocomposite for boosting the bioelectricity generation in microbial fuel cells.

Enhancing the perfomance of the anode materials is critical for improving the efficiency and stability of microbial fuel cells (MFCs) for sustainable bioenergy production and wastewater treatment. In this study, a multi-component nanocomposite consisting of chitosan (CS), iron oxide (Fe2O3), and carbon nanotube (CNT) was synthesized and applied to graphite anodes in dual-chamber MFCs to enhance biofilm formation, electron transfer, and system performance using the drop casting method. Five different wastewater types, agricultural, pharmaceutical (mixed with municipal), partially treated domestic, textile, and sludge, were utilized as substrates to evaluate the system under realistic conditions. The application of the CS/Fe2O3/CNTs nanocomposite significantly improved both energy generation and organic matter removal. MFCs equipped with coated anodes fueled by sludge wastewater achieved a high voltage output of 636 mV and a maximum power density of 3073 mW/m2. The chemical oxygen demand (COD) removal efficiency also improved substantially, with values reaching 72 % for pharmaceutical wastewater and 94 % for textile wastewater, compared to 50-81 % in unmodified systems. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) confirmed that the nanocomposite coating reduced charge transfer resistance and enhanced electrochemical kinetics across all wastewater types. Moreover, biofilm analysis revealed significantly higher bacterial densities and electrogenic species diversity on coated anodes, including dominant strains such as Pseudomonas aeruginosa, Alcaligenes faecalis, and Brevibacillus sp. These findings demonstrate that nanocomposite-modified anodes substantially enhance the bioelectricity generation, microbial colonization of electrogenic species, and wastewater treatment efficiency, underscoring their potential to advance MFC technology for practical, real-world environmental applications.