The degradation of ibuprofen in a novel microbial fuel cell with PANi@CNTs/SS bio-anode and CuInS2 photocatalytic cathode: Property, efficiency and mechanism

Abstract

Microbial fuel cell is an energy-saving bioelectrochemical method for degrading organic pollutants, but it has some limitations in practical application due to the high cathode overpotential, low power output and slow degradation efficiency. Here, a novel photo-catalytic microbial fuel cell (Photo-MFC) coupling with a bioanode and a photocatalytic cathode, is used for ibuprofen (IBU) degradation and simultaneous power generation. Bioanode polyaniline@carbon nanotubes/stainless steel (PANi@CNTs/SS) is synthesized through an in-situ polymerization method, and the properties of PANi@CNTs and CNTs are characterized via BET, XRD, SEM and CV techniques. Photocatalytic cathode CuInS2 is characterized by techniques including the XRD, SEM and UV–Vis diffuse reflectance spectroscopy. And the kinetic data confirmed that the degradation process of IBU under different initial concentrations and different pH conditions conforms to the pseudo-first-order kinetic model. Under optimal conditions, IBU removal rate is 75.94% corresponding to the maximum power density 0.119 W/m2, current density 0.75 A/m2, voltage 950 mV, columbic efficiency (EC) 31%, energy conversion recovery (εE) 11%, cathodic H2O2 efficiency (Rcat) 52%, mineralization current efficiency (MCE) 65.1%. Additionally, •O2− and •OH are proved to be the main reactive oxidative species by trapping experiments, thus electron transfer mechanism of the system and IBU degradation pathway are speculated. Finally, it is verified that the new Photo-MFC could improve the separation of semiconductor photocarriers and enhance the cathode reduction of pollutants, which is a new long-term stable eco-friendly treatment technology for refractory pollutants and provides an experimental basis for the future engineering application.