Crosslinked inter penetrating network of sulfonated styrene and sulfonated PVdF-co-HFP as electrolytic membrane in a single chamber microbial fuel cell

Abstract

In the present study, semi-IPN membranes of sulfonated styrene (SS) and sulfonated PVdF-co-HFP membranes have been analyzed as a polymer electrolyte membrane in single chamber microbial fuel cells (MFCs). 5%, 10%, 20% and 30% sulfonated styrene (SS) with varying concentrations of divinyl benzene (DVB) have been polymerized in the presence of sulfonated PVdF-co-HFP to prepare SPS-0 (0% SS), SPS-5 (5% SS), SPS-10 (10% SS), SPS-20 (20% SS) and SPS-30 (30% SS) membranes, respectively. Progressive improvements in membrane properties were observed with increasing SS and DVB concentrations, where excess DVB (<0.8 wt% of SS) resulted in increased crosslinks within the membrane structure. This eventually impeded the membrane properties and altered their rigidity. The membranes were characterized for their ion exchange capacity (IEC) and proton conductivity; IEC value of 0.39 meq g⁻¹, 0.42 meq g⁻¹, 0.47 meq g⁻¹, 0.54 meq g⁻¹ and 0.63 meq g⁻¹ and proton conductivity of 3.23 × 10⁻³, 1.06 × 10⁻², 1.87 × 10⁻², 2.47 × 10⁻² and 1.61 × 10⁻² S cm⁻¹ were observed for SPS-0 (0% SS), SPS-5 (5% SS), SPS-10 (10% SS), SPS-20 (20% SS) and SPS-30 (30% SS) membranes. The membranes were sandwiched as membrane electrode assemblies (MEA) and employed in single chamber MFCs with open air cathode to analyze their overall performance outputs. It was observed that amongst these membranes, the MFC with SPS-20 membrane showed the maximum power and current density of 447.42 ± 22 mW m⁻² and 1729.63 ± 87 mA m⁻² with an overall ∼91.27% COD removal in 28 days of operation, using electrogenic mixed firmicutes as biocatalysts. Overall, this study reveals the relevance of semi-IPN membranes of sulfonated styrene (SS) and sulfonated PVdF-co-HFP in MFC applications for harvesting bio-energy.