Carbon brush electrodes have been used to provide high surface areas for bacterial growth and high power densities in microbial fuel cells (MFCs). A high-temperature ammonia gas treatment has been used to enhance power generation, but less energy-intensive methods are needed for treating these electrodes in practice. Three different treatment methods are examined here for enhancing power generation of carbon fiber brushes: acid soaking (CF-A), heating (CF-H), and a combination of both processes (CF-AH). The combined heat and acid treatment improve power production to 1370 mW m−2, which is 34% larger than the untreated control (CF-C, 1020 mW m−2). This power density is 25% higher than using only acid treatment (1100 mW m−2) and 7% higher than that using only heat treatment (1280 mW m−2). XPS analysis of the treated and untreated anode materials indicates that power increases are related to higher N1s/C1s ratios and a lower C–O composition. These findings demonstrate efficient and simple methods for improving power generation using graphite fiber brushes, and provide insight into reasons for improving performance that may help to further increase power through other graphite fiber modifications.

Treatment of carbon fiber brush anodes for improving power generation in air-cathode microbial fuel cells

A novel anode fabricated by three-dimensional printing for use in urine-powered microbial fuel cell

An experimental system consisting of a dual chamber microbial fuel cell was constructed using simulated molasses wastewater as the inoculum and anode substrate, carbon cloth or carbon felt as the cathode base, and MnO2 as the oxygen reduction catalyst for cathode. By testing and analyzing the output voltage, power density, and COD removal rate of the microbial fuel cell, the effects of the MnO2-modified cathode on power generation and wastewater treatment of microbial fuel cells were studied. The steady output power density of the microbial fuel cell with carbon cloth cathode were 6.8 and 10.33 mW/m2, respectively, before and after modification by MnO2, that is, the power density of the microbial fuel cell with MnO2-modified carbon cloth was increased by 51.91% more than that of unmodified carbon cloth. The stable output power density of the microbial fuel cells with carbon felt were 3.6 and 31.37 mW/m2, respectively, before and after modification by MnO2, that is, the power density of the microbial fuel cell with MnO2-modified carbon felt was increased by 771.4% more than that of unmodified carbon felt. The results show that the electricity generation capacity and the wastewater treatment effect of the microbial fuel cell using molasses wastewater as the anode substrate can be improved significantly by using inexpensive MnO2 as the cathode modifier.

http://www.pjoes.com/pdf-64197-23878?filename=Molasses Wastewater.pdf

Molasses Wastewater Treatment by Microbial FuelCell with MnO 2 -Modified Cathode

Urine-powered microbial fuel cells (UMFCs) can recover energy from urine, a typical constituent of urban wastewater. Three-dimensional (3D) structure is advantageous for improving the anode perform...

Carbon nanotube sponge 3D anodes for urine-powered microbial fuel cell

Foam graphite is a novel anode material and its modification is one important way to increase the performance of marine benthic microbial fuel cell.The electrochemical performance of mixed-acid modified foam graphite anode was investigated.The results showed that the hydroxyl and carboxyl groups were introduced on foam graphite surface after modification.The contact angle of modified anode decreased 24.5°,resulting in higher wettability and better attachment for bacteria.Its exchange current density reached 6760.8 mA/m2 and the kinetic activity was improved 53.7-fold higher than the original one.Additionally,the present study also found that the anode potential of modified decreased 100 mV,and its open circuit potential reached 865 mV(plain anode 750 mV).The power density of modified cell reached 358.1 mW/m2,2.4-fold higher than unmodified foam.Three months discharge showed that the modified anode and its cell have relatively stable performance.Meanwhile,the paper primarily analyzed the reasons why the anode potential was lower and kinetic activity was higher after modification.The results gave some enlightenments to constructing a novel marine benthic microbial fuel cell with higher output voltage and power.

Application of Modified Foam Graphite Anode with Low Potential in Marine Benthic Microbial Fuel Cell

Oxidants of nitric acid and acidic potassium dichromate were used to modify anode carbon cloths. Modification was completed by first putting the carbon cloth into nitric acid or acidic potassium dichromate at a given temperature, soaking for 30 min and then rinsing with de-ionized water until no variation in pH and finally putting into a vacuum dryer, drying for 12 h. Fourier transform infrared spectroscopy measurements indicated that many hydroxyls and carboxyls were attached on the carbon cloth surface after modification. SEM results showed that the surface of carbon cloth became rougher than the unmodified one. In addition, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements demonstrated that both modified anodes had excellent electrochemical properties. Using the modified carbon cloths as microbial fuel cell (MFC) anodes respectively, such MFCs yielded maximum power densities of 291.11 mW·m −2 and 438.08 mW·m −2 , 21% and 82% higher than that of the MFC with unmodified carbon cloth anode respectively.

Microbial fuel cell anode modified by chemical oxidation

The kinetics of oxygen reduction of cathode catalyst is a critical factor that limits the performance of microbial fuel cells (MFCs). The composite catalyst of three composite proportion(1:3, 1:1 and 3:1), which were prepared by reacting KMnO4 with supercapacitor activated carbon (S-AC),were tested as air-cathode catalyst of microbial fuel cells (MFCs) for oxygen reduction. X-ray diffraction (XRD) was used to characterize the catalysts, energy dispersive X-Ray Spectroscopy to estimate the quality of MnO2, scanning electron microscopy (SEM) to observe the surface morphology, and BET method to examine surface area and pore distribution characteristics, to analyze the factors affecting the performance of the composite catalyst. With increasing of composite proportion, the MnO2 sheets gathered into nano-particles (300—500 nm) on the surface of S-AC. At the same time, there is the decrease of the internal and external surface area MnO2/S-AC. Nickel foam air-cathode was made with different catalysts, and tested in air-cathode MFCs to study the effect on MFC performance by linear sweep voltammetry (LSV), polarization curves and power density curve. When the feeding ratio of KMnO4: S-AC is 1:3,

Liu Zhongliang

Papers

Microbial fuel cell anode modified by chemical oxidation

Preparation and properties of nickel foam air cathode with MnO2/S-AC catalyst for microbial fuel cells