Synthesis, characterization and application of S-TiO2/PVDF-g-PSSA composite membrane for improved performance in MFCs

Abstract Sulfonated titanium dioxide (S-TiO2) was prepared by the grafting of sulfonic groups onto TiO2, and doped into the PVDF-g-PSSA as a highly efficient inorganic additive, thus achieving simultaneous improvement of the proton conductivity and anti-fouling property of the synthesized S-TiO2/PPSSA proton exchange membrane (PEM). The S-TiO2/PPSSA membrane was implemented in microbial fuel cell (MFC) for the first time, and its physicochemical properties and performance in MFC were studied. A new technique of combining Quartz crystal microbalance with dissipation with membrane spin-coated sensors made by a spin coating method was utilized to provide an insight into the anti-fouling property of the prepared membranes. The implementation of Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy demonstrated TiO2 was successfully introduced into the sulphonic groups. The S-TiO2/PPSSA-5.0 membrane has a significant increase in the water uptake (40.9%) and proton conductivity (0.067 S/cm) compared with the PVDF-g-PSSA membrane. QCM-D results indicated that it has better anti-fouling property than pristine membrane and Nafion 117. Moreover, the MFC with the S-TiO2/PPSSA-5.0 membrane exhibited a maximum power density of 130.54 mW/m2, very close to that of Nafion 117 (132.02 mW/m2), but had the highest COD removal of 91% and least bio-fouling adsorption. These results demonstrate that the blending of sulfonated organic polymers and sulfonated inorganic additives can improve the electrochemical and anti-fouling properties of the composite membranes, which is a new concept for the preparation of PEM suitable for MFC. The S-TiO2/PPSSA-5.0 composite PEM is an appropriate candidate separator for the large-scale application of MFCs.