The use of nylon and glass fiber filter separators with different pore sizes in air-cathode single-chamber microbial fuel cells

Abstract

Separators are needed in microbial fuel cells (MFCs) to reduce electrode spacing and preventing electrode short circuiting. The use of nylon and glass fiber filter separators in single-chamber, aircathode MFCs was examined for their effect on performance. Larger pore nylon mesh were used that had regular mesh weaves with pores ranging from 10 to 160 mm, while smaller pore-size nylon filters (0.2-0.45 mm) and glass fiber filters (0.7-2.0 mm) had a more random structure. The pore size of both types of nylon filters had a direct and predictable effect on power production, with power increasing from 443 AE 27 to 650 AE 7 mW m À2 for pore sizes of 0.2 and 0.45 mm, and from 769 AE 65 to 941 AE 47 mW m À2 for 10 to 160 mm. In contrast, changes in pore sizes of the glass fiber filters resulted in a relatively narrow change in power (732 AE 48 to 779 AE 43 mW m À2 ) for pore sizes of 0.7 to 2 mm. An ideal separator should increase both power density and Coulombic efficiency (CE). However, CEs measured for the different separators were inversely correlated with power production, demonstrating that materials which reduced the oxygen diffusion into the reactor also hindered proton transport to the cathode, reducing power production through increased internal resistance. Our results highlight the need to develop separators that control oxygen transfer and facilitate proton transfer to the cathode.

Systematic Study of Separators in Air-Breathing Flat-Plate Microbial Fuel Cells—Part 2: Numerical Modeling

“…The effect of oxygen crossover on the anode potential became less significant as the electrode spacing increased (in the 4 mm and 8 mm FPMFCs), due to the lower concentration of oxygen at the anode. [30,31], and the passive air-breathing MFCs with electrode spacing of 2 cm and larger [32,33]. The extent of the anode depolarization matched that reported for the passive air-breathing MFCs with larger electrode spacing, as a result of the lower susceptibility of the polymeric Nafion ® 117 membrane to oxygen diffusion.…”

“…That could be one reason why mass transfer coefficient of ethanol did not seem to play a significant role on the cathode potential. Ethanol oxidation at the cathode, on the other hand, was most likely limited by its slow Nafion ® 117 gave the lowest anode potential values in all three FPMFCs (ca.´0.3 V vs. standard hydrogen electrode (SHE) at open circuit), similar to the values reported in the MFCs using ferricyanide and ferric iron as the oxidant [30,31], and the passive air-breathing MFCs with electrode spacing of 2 cm and larger [32,33]. The extent of the anode depolarization matched that reported for the passive air-breathing MFCs with larger electrode spacing, as a result of the lower susceptibility of the polymeric Nafion ® 117 membrane to oxygen diffusion.…”

“…The proton transport number of the separators affected the peak power by altering the cathode potential [32,33]. A 60% increase in the proton transport number of Nafion ® 117 (from 0.59 to 0.94) was estimated to increase the peak power similarly in all three FPMFCs by 23%-24%.…”

Fabrication and Operation of a Novel Membrane-less Microbial Fuel Cell as a Bioelectricity Generator

“…Most of the process factors have great effects on electron transfer and bioelectricity generation [12,13]. Two individual chamber in traditional MFCs are separated by special membranes such as proton exchange membrane [11,14] cation exchange membrane and anion exchange membrane [15] but these membranes are high in cost, so some researchers tried to reduce the cost of MFCs by using cheaper membrane (e.g., glass fiber) or by removing of the membrane [16]. However, non-membrane means more oxygen diffusion to the anode chamber that will inhibit anaerobic condition and microbial growth and thus decrease the columbic efficiency [3,17] so using cheaper membrane seems to be an appropriate method.…”

Coaxial Electrospun Cellulose-Core Fluoropolymer-Shell Fibrous Membrane from Recycled Cigarette Filter as Separator for High Performance Lithium-Ion Battery

“…A separator in LIBs is a key component to prevent such failures, because it can isolate the cathode and anode, to prevent electrical short-circuits, while allowing rapid transport of ionic charge carriers. 6,7 Commercial separator materials used in LIBs are polyolefins, for their superior electrochemical stability and considerable mechanical strength. 8,9 However, due to their nonpolar nature, these materials show poor liquid electrolyte retention and do not absorb electrolytes with high dielectric constants, such as cyclic carbonates.…”