جستجوی مقالات مرتبط با کلیدواژه « microbial fuel cell » در نشریات گروه « مواد و متالورژی »

Microbial Fuel Cells (MFCs) represent an environmentally-friendly approach to generating electricity, but the need to study variation parameters to find improvement conditions has been an important challenge for decades. In this study, a single-chamber MFC was designed to investigate the key parameters such as the concentration and type of bacteria, chamber temperature, electrode spacing, and substrate rotation speed that affected the performance of MFCs. Therefore, two types of bacteria, Shewanella oneidensis (S.one) and Escherichia coli (E. coli), were compared as microorganisms. Then, the function of MFC was investigated under the following condition: three temperatures (30 ℃, 45℃, and 60℃), three bacterial concentrations (0.5% (v/v) (4.5 mg/ml), 1% (v/v) (9mg/ml), and 1.5% (v/v) (13.5mg/ml)), electrode distances (2 cm, 3 cm, 4cm), and substrate speeds (100 rpm, 150 rpm, 200 rpm). Ultimately, (S.one) bacteria, a chamber temperature of 45 ℃, a bacterial concentration of 1% (v/v) (9mg/ml), a cathode-anode spacing of 3 cm, and a rotation speed of 150 rpm proved to be the most efficient parameter settings for the constructed microbial fuel cell. The maximum voltage and highest power density were 486.9 mV and 9.73 mW/ , respectively, with a resistance of 7500 ohms. These results are meaningful for determining and improving important parameters in an MFC device.

Response surface methodology is employed to statistically identify the significance of three parameters of separator assembly arrangement, wastewater flow rate, and relative flow patterns of anode and cathode influencing the generation of power and coulombic efficiency of Microbial Fuel Cells (MFCs). Three different assemblies of Nylon-Cloth (NC), artificial rayon cloth as Absorbent Layer (AL), and J-Cloth (JC) were investigated as proton exchange mediums instead of common expensive polymeric membranes. Statistical analyses (ANOVA) revealed that although the addition of the AL after the JC layer had no significant impact on the enhancement of maximum power density, it could improve the coulombic efficiency of the MFCs by  15 %, owing to the crucial impact of oxygen permeability control between the MFC chambers. In the counter-current flow pattern, higher trans-membrane pressure and more oxygen concentration differences diminished the MFC performance and marked the importance of efficient separator layer arrangement, compared to       co-current influents. The maximum power density of 285.89 mW/m2, the coulombic efficiency of 4.97 %, and the internal resistance of 323.9 Ω were achieved for the NC-JC-Al arrangement in the co-current mode along with the flow rate of 6.9 ml/min. The higher the flow rate of influent wastewater, the higher the performance of the MFCs.

Recently developed man-made structures have caused environmental pollutions, and unfortunately, in spite of the deteriorating affairs and repeated warnings by scientists and experts, the degree of contamination is increasing considerably. One of the natural sources undergoing changes is the coasts. It is mainly due to human activities which have led to a change in the quality and quantity of sediments. These regions can be contaminated by a variety of hazardous pollutants such as heavy metals and hydrocarbons. In this work, a combination of electrokinetic and MFC process was used for Cr removal from contaminated sediments. According to the obtained results, a maximum power density and current of 1.06 W/m3 and 52.05 A/m3 were achieved during the process. Given the presence of chromium in the catholyte, it can be concluded that the chromium migration from sediment sample to the cathode chamber has been taken. In addition, the maximum Cr measured in catholyte was 0.056 mg/l. Overall, the results confirmed the high efficiency of the proposed cell for contaminant removal from sediments.

The effect of the thickness of ceramic membrane on the productivity of microbial fuel cells (MFCs) was investigated with respect to the electricity generation and domestic wastewater treatment efficiencies. The thickest ceramic membrane (9 mm) gained the highest coulombic efficiency (27.58±4.2 %), voltage (681.15±33.1 mV), and current and power densities (447.11±21.37 mA/m2, 63.82±10.42 mW/m2) compared to the 6- and 3-mm thick separators. The results of electrochemical impedance spectroscopy (EIS) analysis were investigated to identify the internal resistance constituents by proposing the appropriate equivalent electrical circuit. The Gerischer element was modeled as the coupled reaction, and diffusion in the porous carbon electrodes and the constant phase element was assimilated into the electrical double-layer capacitance. The thickest ceramic (9 mm) was found to have the largest ohmic resistance; however, owing to its superior barrier capability, it provided more anoxic conditions for better accommodation of exoelectrogenic bacteria in the anode chamber. Therefore, lower charge transfer, fewer diffusional impedances, and higher rates of anodic reactions were achieved. Excessive oxygen and substrate crossover through the thinner ceramics (of 6 and 3 mm) resulted in the suppressed development of anaerobic anodic biofilm and the accomplishment of aerobic substrate respiration without electricity generation.