Improved performance of microbial fuel cells using sulfonated polyether ether ketone (SPEEK) TiO2-SO3H nanocomposite membrane

The microbial fuel cell (MFC) is a new technology for simultaneous electricity generation and wastewater treatment. An enhancement in the proton exchange membrane (PEM) of MFCs is essential for their scale-up and commercialization. In this work we demonstrate, for the first time, the use of sulfonated inorganic fillers in polyelectrolyte nanocomposite membranes as an effective approach to improve the MFC performance. A new nanocomposite membrane based on a sulfonated polyether ether ketone (SPEEK) hybrid with sulfonated TiO2 particles (TiO2-SO3H) was fabricated and evaluated in a microbial fuel cell. To authenticate the advantages of a SPEEK-TiO2-SO3H composite membrane, the IEC value, water uptake, proton conductivity, oxygen crossover, microbial fuel cell (MFC) performance and internal resistance were compared with a SPEEK-TiO2 membrane and a SPEEK membrane. The SPEEK-TiO2-SO3H membrane (7.5 wt%) exhibited the highest peak power density of 1202.5 mW m(-2) compared with the power densities of 766 mW m(-2) and 676 mW m(-2) obtained for the SPEEK-TiO2 membrane and the SPEEK membrane, respectively, in the single chamber microbial fuel cell (SCMFC) membrane. The electrochemical behaviour of the membrane was improved by adding different amounts of TiO2-SO3H into the membrane to enhance the proton conductivity and also to reduce biofouling. Higher power was achieved with the 7.5 wt% TiO2-SO3H incorporated SPEEK-TiO2-SO3H membrane. In comparison to previously reported work with Nafion 117 (300 mW m(-2)) in MFCs, the composite membrane delivers a 4-fold higher power density. The oxygen mass transfer coefficient (K-O) of the nanocomposite membranes decreased with incorporation of the sulfonated titanate in the nanocomposite membranes. The internal resistance for the SPEEK-TiO2-SO3H and SPEEK membranes were estimated to be 37 Omega and 74 Omega, respectively. The improved performance was attributed to the introduction of TiO2-SO3H particles, whose high proton conductivity and good water adsorbing/retaining function could facilitate effective proton transfer in the membrane. To the best of our knowledge, this new hybrid SPEEK-inorganic sulfonated nanocomposite is fabricated for the first time and applied to MFCs.