Persulfate: A self-activated cathodic electron acceptor for microbial fuel cells

Potassium persulfate aqueous solution without pH adjustment is used as the cathodic electron acceptor in a two-chamber microbial fuel cell (MFC) in the present study. The performance of the MFC with K2S2O8 solution is evaluated and compared with that of K3Fe(CN)6 solution. The results show that the maximum power density of the K3Fe(CN)6 used MFC doubled that with K2S2O8 solution when fresh aqueous solution is used. However, a significant increase in electrical power generation is observed in the case of the MFC with K2S2O8 solution after 2-day operation under an external resistance of 1000 Ω. This improvement can be attributed mainly to the increased cathode performance as a result of the hydrolysis of the persulfate ion in aqueous solution. It is demonstrated that persulfate can be used as an effective cathodic electron acceptor due to its unique capability of self pH adjustment.