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 sulfa-methoxazole (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.