Improving the performances of Nafion™-based membranes for microbial fuel cells with silica-based, organically-functionalized mesostructured fillers

Microbial Fuel Cells (MFCs) can be conveniently used for wastewater treatment and bioelectricity production. Their efficiency is strongly influenced by the physico-chemical properties of the ion-conducting membrane. In this work we prepare Nafion™-based composite membranes by using mesoscale SBA-15 silica, and organic-inorganic fillers obtained by functionalizing SBA-15 with SO3H groups. The proposed membranes are tested as alternative separators in MFCs for applications in wastewater treatment and their performances compared to those of standard Nafion™ 117. Prolonged (3 months) MFC operation shows that the composite membrane with 5 wt% of SBA-15 functionalized with 10 mol% of SO3H gives maximum power density of 380 mW m−3, namely three times better than that of Nafion™ after 90 days of operation. The same membrane offers a very effective COD removal after 14 days (more than 95%), an impressive coulombic efficiency of 34%, and very high resistance to biofouling. We conclude that the use of silica-based SO3H functionalized fillers is a powerful strategy to improve the performances of Nafion™ membranes in MFCs.