Incorporating sulfonated MIL-100(Fe) in sulfonated polysulfone for enhancing microbial fuel cell performance

Abstract

This study aims to synthesize a proton exchange membrane (PEM) by incorporating a sulfonated MIL-100(Fe) metal–organic framework (sMILFe MOF) into the sulfonated polysulfone (sPSf), to investigate the maximum capability of microbial fuel cells (MFCs) in organic degradation and electricity generation. The physicochemical properties of the membranes, such as water uptake (WU), ion exchange capacity (IEC), proton conductivity (PC), coulombic efficiency (CE), and performance of MFC with sPSf incorporated with unsulfonated MIL-100(Fe) MOF (sPSf/MILFe), and sulfonated MIL-100(Fe) MOF (sPSf/sMILFe) composite membranes were compared. The prepared (sPSf/sulfonated MIL100(Fe)) membrane showed improved PC of the sPSf membrane and revealed the peak output of power energy of 64.2 mW m−2 in mixed liquor suspended solid (MLSS) concentration 4000 mg L−1, as compared to 29.8 mW m−2 and 50.8 mW m−2 obtained for sPSf, sPSf/MILFe membranes, respectively, in two-chambered MFCs. Furthermore, this composite membrane delivered a higher PC of 40.6 mW m−2 compared to Nafion-117 in the MFC. The remarkably enhanced performance of the composite electrolyte membranes was due to the added sulfonated MIL-100(Fe), which provided effective proton-conducting channels for proton transport in the membrane matrix. Integrating sulfonated polysulfone chains into open channels enables vehicular and Grotthuss (proton hopping) mechanisms across the channels, considerably enhancing PC and coulombic efficiencies.