Performance evaluation of a polydopamine-modified carbon cloth bioanode for concurrent bioelectricity generation and ciprofloxacin transformation within a microbial fuel cell.

Ciprofloxacin (CIP) residues are difficult to eliminate using conventional biological treatment, whereas advanced oxidation processes commonly require substantial chemical or energy input. In this study, a dual-chamber microbial fuel cell equipped with a polydopamine-modified carbon cloth bioanode was evaluated for concurrent bioelectricity generation and ciprofloxacin removal. Polydopamine was deposited on carbon cloth by cyclic voltammetry electropolymerization. Scanning electron microscopy confirmed the formation of a conformal nanostructured coating on the carbon fibers. The microbial fuel cell was inoculated with anaerobic granular sludge and operated in fed-batch mode using acetate as the primary electron donor and ferricyanide as the cathodic electron acceptor. Acetate supplementation increased the peak voltage to between 580 and 620 mV, compared with between 320 and 420 mV without acetate. CIP concentration decay followed pseudo-first-order kinetics at initial concentrations of 10, 50, and 100 mg/L, and the corresponding apparent rate constants were approximately 0.088, 0.051, and 0.018 d- 1, respectively. Increasing ciprofloxacin concentrations were also associated with reduced voltage recovery, increased apparent interfacial resistance, and weaker electrochemical responses. High-performance liquid chromatography-mass spectrometry analysis detected 9 transformation-related products that were tentatively associated with piperazine-moiety transformation, hydroxylation, loss of the fluorine-containing functionality, and decarboxylation. This study provides a laboratory-scale basis for evaluating surface-engineered bioanodes for antibiotic-containing wastewater while identifying pollutant loading and transformation-product toxicity as important constraints.