Preparation Of Ion Exchange Membrane And Modifition Of Cathode Electrode For Microbial Fuel Cell

The microbial fuel cell (MFC) is becoming a promising technology for both wastewater treatment and electricity generation simultaneously. The ion exchange membrane and cathode electrode are the important components in an MFC system, and have the great influences on the MFC electrochemical performance. In this thesis, we successfully prepared a series of cation exchange membranes based on multiblock sulfonated poly(ether sulfone)s, a series of anion exchange membranes based on quaternized poly(ether sulfone)s. In the meanwhile, the modification of cathode electrode by manganese dioxide was also investigated.A series of cation exchange membranes with different block length based on multiblock suflonated poly(arylene ether sulfone)s (bSPAES) was prepared successfully and used as the separators in the microbial fuel cell (MFC) systems. bSPAES membranes exhibited significant dimensional stability and hydrolytic stability, and isotropic performance in water in the range of10～20%of size change. bSPAES membranes showed water uptake of36～73%and conductivity of81～140mS/cm, while the commercial membrane ULTREX CMI-7000was25%and20mS/cm respectively. bSPAES membranes showed good mechanical properties for the introduction of the rigid fluorenyl in the hydrophilic moieties, and the Young’s modulus reached nearly1GPa. After1000h MFC operation, almost no changes were observed for the conductivity of bSPAES membranes. Hydrolytic stability test in100℃water for24h showed that the weight loss was between1.5to6.3%. The maximum power density of MFC increased with the block length increasing. Comparing with the ULTREX CMI-7000membrane, the bSPAES membranes exhibited much better MFC performances, and the maximum power density for bSPAES(30/30)reached to705mW/m2.A series of anion exchange membranes based on quaternized poly(ether sulfone)s (QPAES-OH) were prepared successfully, while the membrane IEC was controlled by the reaction time in chloromethylation. The chemical structures of the PAESs and the CMPAESs polymers were confirmed by1H NMR spectra. The IEC levels were controlled from1.35mmol/g to1.73mmol/g with the increasing of reaction time. QPAES-OH membranes showed water uptake of12.9～35.9%and conductivity of6.5～13.1mS/cm Hydrolytic stability test in80℃water for24h showed that the weight loss was between0.2～3.3%. The maximum power density of MFC increased with the IEC increasing, which were much higher than that from AMI-7001membrane (175.3mW/m2), and the maximum power density reached to326.2mW/m2when the QPEAS-OH membrane with IEC of1.73mmol/g used as the separator.Three types of manganese dioxide (α-,β-,γ-) were prepared by redox reactions and hydrothermal method and as catalysts for oxygen reduction reaction (ORR) in air-cathode microbial fuel cells. The manganese dioxide nanoparticles were confirmed by SEM and XRD, and electrodes were tested by CV, respectively. The results indicated that β-MnO2had the highest catalytic activity for ORR. In the applications of dual-chamber MFC, the maximum output power density of β-MnO2-MFC was183.1mW/m2, which was much higher than the others, and the resistance was only91Ω.