Performance comparison of activated carbon and Pt/C cathode microbial fuel cells on sulfamethoxazole degradation: Effect of salinity and mechanism study

In this study, activated carbon (AC) and Pt/C cathode microbial fuel cells (MFCs) were constructed respectively to explore the electrochemical performance in different salinity conditions, and further investigation on sulfamethoxazole (SMX) degradation was tested in high salinity. The results showed that the maximum power density of 348 mW/m² was obtained in MFC-AC (MFC reactor with AC as cathode catalyst) with the introduction of 100 mM NaCl, and MFC-AC exhibited the stronger resistance to the salinity effect than MFC-Pt/C (MFC reactor with Pt/C as cathode catalyst). XRD characterization illustrated the crystal form and crystal size of the AC cathode were significantly more stable than those of Pt/C, especially at 600 mM and 800 mM NaCl. More interestingly, the 2-electron reaction occurred on AC cathode was verified using rotating disk electrode (RDE), which contributed to the alleviation of biofouling and stability of electrochemical performance on cathode. MFC-AC showed the better degradation capacity on SMX with degradation efficiency of 95% at 100 mM NaCl. The degradation path was speculated to be oxidized firstly owing to the hydroxyl radicals generated by 2-electron reaction on AC cathode. The results demonstrated that MFC-AC could be considered as a potential alternative for industrial high salinity organic wastewater efficient treatment.