A critical review on recent proton exchange membranes applied in microbial fuel cells for renewable energy recovery

This paper proposes a critical review of the proton exchange membranes currently available or under development for use in batch-mode microbial fuel cell (MFC) systems in order to suggest a suitable cost-effective membrane in terms of energy recovery. To prepare the present review, the relevant papers were identified by searching the Scopus database and extracting papers from 2007 to 2020. There is a wide variety of different membranes, each with its advantages and disadvantages. Perfluorinated and non-fluorinated membranes were evaluated based on different properties, including proton conductivity, power density (PD), water uptake, and ion exchange capacity. Results reveal that non-fluorinated membranes such as sulfonated poly (ether ether ketone) (SPEEK), graphene oxide/SPEEK (GO/SPEEK), polyethersulfone (PES) and polysulfone (PS) and sulfonated polybenzimidazole (S-OPBI) are a good choice to replace the commonly used membrane Nafion (TM) because of their lower cost and higher energy recovery. Sulfonated membranes such as polyethersulfone/SPEEK (PES/SPEEK) and Sulfonated polyethersulfone (SPES) show the highest normalized energy recovery. Although Nafion (TM) has the highest proton conductivity and is an excellent choice as proton exchange membrane (PEM) for MFCs, its energy recovery capacity is lower than that of porous and microfiltration membranes. It can also be very sensitive to biofouling. In the following, different parameters of membrane characterization and also wastewater treatment are discussed. The energy recovery of the membranes and systems studied was measured in order to recommend a suitable membrane for MFCs to improve the efficiency of these systems in terms of clean electricity generation and wastewater treatment. (C) 2020 Elsevier Ltd. All rights reserved.