Treatment of m-Cresol Wastewater in an Anaerobic Fluidized Bed Microbial Fuel Cell Equipped with Different Modified Carbon Cloth Cathodes

Carbon nanotubes (CNTs) and graphene (Gr) modified carbon cloth (CC) cathode were prepared by in situ polymerization method using polyaniline (PANI) as an adhesive. Different modified electrodes were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV), and thermogravimetric analysis (TGA) techniques. These different cathodes were used in anaerobic fluidized bed microbial fuel cell (AFB-MFC) to treat the synthetic m-cresol wastewater. The results showed that the maximum power densities of AFB-MFC with the Gr-modified cathode (PANI + Pt/C + Gr), the CNT-modified cathode (PANI + Pt/C + CNTs), and the Pt/C cathode (PANI + Pt/C) were 910.40, 445.14, and 127.07 mW/m2, respectively. In addition, the removal efficiency of m-cresol in AFB-MFC with PANI + Pt/C + Gr is 91.76%, while the corresponding values in AFB-MFC with PANI + Pt/C + CNTs and PANI + Pt/C are 91.72 and 89.26%, respectively. Gas chromatography–mass spectrometer (GC–MS) was used to detect metabolites of m-cresol. It was proved that m-cresol was degraded to protocatechol and then to 2-dimethylsuccinic acid. The energy of m-cresol degradation pathway was analyzed by Materials Studio (MS) software, and the control step of m-cresol degradation was determined.