Razi University

   In recent years, microbial fuel cells (MFCs) have attracted considerable attention as promising technologies for simultaneous wastewater treatment and bioelectricity generation. However, the performance of proton exchange membranes (PEMs), as one of the key components of MFC systems, is still limited by challenges such as oxygen crossover, low proton conductivity, and high internal resistance. In the present study, eucalyptus plant extract was utilized as an environmentally friendly bio-based additive for the modification of sulfonated polyether sulfone (SPES) membranes in order to improve their physicochemical and electrochemical performance in MFCs. For this purpose, SPES membranes containing different concentrations of eucalyptus extract (EE) including 0.5, 1, and 1.5 wt% were fabricated and compared with the bare membrane. Various characterization techniques including FTIR, ATR-FTIR, SEM, water uptake (WU), cation exchange capacity (CEC), water contact angle (WCA), dissolved oxygen (DO) analysis were employed to investigate membrane properties. Furthermore, electrochemical performance was evaluated using polarization curves, power density (PD), current density (CD), COD removal, and coulombic efficiency (CE). FTIR and ATR-FTIR analyses confirmed the successful incorporation of EE into the membrane structure. SEM images revealed that the modified membranes exhibited more compact and homogeneous morphologies compared to the bare membrane. In addition, incorporation of EE enhanced membrane hydrophilicity, improved CEC, and reduced oxygen crossover. Among all fabricated membranes, the membrane containing 1 wt% EE exhibited the best overall performance. This membrane achieved the highest PD of 193.4 mW m?² and maximum CD of 716.2 mA m?². Moreover, the highest COD removal (89.16%) and CE (76.11%) were also obtained for this membrane. The enhanced performance can be attributed to improved hydrophilicity, enhanced proton tra  ort capability, higher CEC, and lower oxygen permeability. Overall, the obtained results demonstrated that EE can effectively improve the performance of SPES membranes for MFC applications and provides a promising approach for the development of sustainable and environmentally friendly PEMs.