Bioelectricity Harvesting via a Microbial Fuel Cell with Sulfonated Hypercrosslinked Polyphenols and Polyethersulfone Composite Proton-Conducting Membrane

Abstract

International audienceIn this research, a novel polyelectrolyte composite membrane was developed by combining sulfonated polyethersulfone (sPES) and sulfonated hypercrosslinked polymers (sHCP) to enhance microbial fuel cell (MFC) performances. Various characterization strategies confirmed that the incorporation of sulfonic groups boosted proton conductivity and hydrophilicity, with sHCP further enhancing these properties. The sulfonation degrees were measured at 51.80 % for sPES, 48.54 % for sHCP, and 66.05 % for the sPES/sHCP0.8 composite. Key physical properties included a water uptake (WU) of 54.30 %, surface roughness (SR) values of 21.53 % and 33.25 %, and ion-exchange capacity (IEC) measurements of 1.97 and 2.38 meq/g for sPES and sPES/sHCP0.8, respectively. Proton conductivity (PC) reached 4.03 mS/cm for sPES and 5.53 mS/cm for sPES/sHCP0.8. In contrast, Nafion-117 exhibited a high O 2 diffusion coefficient of 1.44 cm 2 /s and a transport rate coefficient of 0.123 cm/s, while sPES/sHCP0.8 demonstrated minimal O 2 migration, with diffusion coefficients of 1.73 × 10 -2 cm 2 /s and a transport rate of 2.45 × 10 -3 cm/s. The sPES/sHCP0.8 membrane displayed superior tensile stress, elastic modulus, and strain at break compared to PES, sPES, and Nafion-117, measuring 73.48 MPa, 7.49 %, and 15.80 MPa, respectively. Findings indicated that membrane selection is crucial for COD removal efficiency and energy generation. The MFC with the sPES/sHCP0.8 polyelectrolyte achieved a coulombic efficiency of 0.8 %, a COD reduction of 84.37 %, and an energy density of 80.96 mW/m 2 , outperforming Nafion-117 (28.56 mW/m 2 ) and sPES20 (28.56 mW/m 2 ) in batch mode over five days. Additionally, bioelectricity was harvested at 32.38 Wh/m 3 (NERv) and 10.9 kW/kg COD (NERs). However, the highest COD removal of 96.54 % was attained with MFCs using sPES20/sHCP160-0.8 and sPES20/sHCP180-0.4. The maximum I max was 690 mA/m 2 (1150 mA/ m 3 ) with sPES20/sHCP180-0.6, which also achieved the highest CE of 0.88 %. This study demonstrates that integrating sHCP enhances membrane properties while maintaining thermal and mechanical stability, significantly improving MFC performance