In-situ degradation of organic pollutants by bioelectrical-Fenton reaction with a metal-free polyaniline-derived nitrogen-doped carbon nanofibre electrode

Polyaniline (PANI)-derived nitrogen-doped carbon nanofibres used as cathode electrodes in situ generate and activate H 2 O 2 to form •OH without metal catalysts. The degradation rates of ciprofloxacin hydrochloride (CIP) and methyl orange (MO) were 99.64% and 100%, respectively, and the mineralisation rates were 54.24% and 62.56% at the modified metal-free Fenton system for microbial fuel cells (MFC-Fenton) cathode. Micropores were introduced into the electrode to provide active sites such as pyridinic N and graphitic N, which improves the electron transfer rate and redox activity, as well as exhibiting excellent power generation capacity (783.48 ± 10.52 mV and 33.57 ± 0.14 W m − 3 ) in comparison with a single MFC process (543.14 ± 3.56 mV and 11.02 ± 1.03 W m − 3 ). The degradation intermediates and mechanisms of this process were studied in detail. This study provides a new understanding of MFC-Fenton systems for removing practical organic pollutants in wastewater. • Efficient metal-free PANI electrode was synthesized by a electrodeposited method. • H 2 O 2 in-situ generated and activated for efficient degradation of CIP. • The prepared electrode firstly used as reusable metal-free MFC-Fenton cathode. • ESR confirmed the existence of •OH and the mechanism of degradation process. • Taking CIP as a pollutant, the three degradation path of intermediates was studied.