Bioelectrochemical behavior of Ordered Mesoporous Carbon + B. subtilis as bioanode for the production of bioenergy in a Microbial Fuel Cell (MFC)

Abstract

The bioelectrochemical behavior of non-functionalized Ordered Mesoporous Carbon (OMC) and functionalized with methanol at di ff erent concentrations (0.15, 0.5 and 1 M, labeled as OMC015, OMC05, and OMC1, respectively), forming bioanodes with Bacillus subtilis ( B. subtilis ) as the electrochemically active microorganism (EAM), was evaluated in a dual-chamber Microbial Fuel Cell (MFC). OMC015 showed the highest surface area (550.0 m 2 g − 1 ) with a total pore volume of 0.270 cm 3 g − 1 (those of OMC were 410.6 m 2 g − 1 and 0.191 cm 3 g − 1 , respectively). Cyclic voltammograms (CVs) in pharmaceutical wastewater (PWW, pH = 7.1) showed an enhanced bioelectrochemical behavior of the OMC + B. subtilis and OMC015 + B. subtilis bioanodes compared to OMC05 + B. subtilis and OMC1 + B. subtilis . Therefore, the two former bioanodes were evaluated in the MFC containing PWW as substrate in the anode chamber. The results showed di ff erences in the behavior of the bioanodes in long-term tests (7 days) in the MFC. OMC + B. subtilis showed a decrease in Open Circuit Voltage (OCV) and current density (j) values from Day 0 to Day 3, followed by a slight increase in j and a higher OCV at Day 7 (compared to Day 3). Meanwhile, OMC015 + B. subtilis showed a more stable bioelectrochemical behavior, with slight variations in OCV and j at Days 0, 3 and 7. The maximum power density (P cell ) of the MFC was 12.3 mW m − 2 with OMC015 + B. subtilis at Day 3 of operation. The results showed the biocompatibility between the OMC015 catalysts and B. subtilis as EAM, and their catalytic activity to oxidize organic matter contained in PWW, generating bioenergy from the MFC.