Bioanodes In Microbial Fuel Cells Research Articles

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) bioanodes in Co-doped modified microbial fuel cell promote sulfamethoxine degradation with high enrichment of electroactive bacteria and extracellular electron transfer

Microbial fuel cell (MFC) is a new renewable energy technology, which has a wide range of applications. In this paper, the refractory organic matter sulfamethoxazole (SMX) was degraded by MFC technology, and the electricity generation performance was analyzed in detail. Since Ni and Fe ions can promote electron transfer, the presence of S ions can enhance the biocompatibility of the material, in this study, nano-ferro nickel sulfide (NiFe2S4) was prepared by hydrothermal method, and co-doped with ferro oxide (Fe3O4) nanoparticles to modify the poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) hydrogel served as the bioanode of MFC. Through high throughput results, we found the enriched electro producing bacteria Desulfuromonas and Fe-S cluster oxidoreductase, proving that bimetallic sulfides have good synergistic effect with metal oxides, which can provide more active sites and accelerate the EET process. The maximum power density obtained as a bioanode in MFC was 3.67 W/m3. During degradation of SMX, the maximum power density was 2.39 W/m3. At the same time, the degradation efficiency of SMX reached 93.78 %, and the chemical oxygen demand (COD) removal rate was 32.52 %. This provides a valuable reference for the degradation of refractory organic compounds such as antibiotic SMX, and also provides multi-dimensional thinking for renewable energy technologies.

Enhancing microbial fuel cell performance through microbial immobilization.

Bio-electrochemical Systems (BES), particularly Microbial Fuel Cells (MFC), have emerged as promising technologies in environmental biotechnology. This study focused on optimizing the anode bacterial culture immobilization process to enhance BES performance. The investigation combines and modifies two key immobilization methods: covalent bonding with glutaraldehyde and inclusion in a chitosan gel in order to meet the criteria andrequirements of the bio-anodes in MFC. The performance of MFCs with immobilized and suspended cultures was compared in parallel experiments. Both types showed similar substrate utilization dynamics with slight advantage of the immobilized bio-anode considering thelowerconcentration of biomass. The immobilized MFC exhibited higher power generation and metabolic activity, as well. Probably, this is due to improved anodic respiration and higher coulombic efficiency of the reactor. Analysis of organic acids content supported this conclusion showing significant inhibition of the fermentation products production in the MFC reactor with immobilized anode culture.

Bio-electrocatalyst Fe3O4/Fe@C derived from MOF as a high-performance bioanode in single-chamber microbial fuel cell

As a promising green and storage/conversion technology, the microbial fuel cell (MFC) was generally restricted by the lower power density in application. Three carbonized derivatives of the same precursor metal organic framework (MOF) MIL-53(Fe) were prepared via carbonization at 385 ℃, 600 ℃ and 750 ℃ in argon atmosphere. Experiments showed that carbonized MIL-53(Fe) (CM53) derivative at 750 ℃ produced Fe3O4/Fe@C structure and revealed the best performance as bioanode in MFC. As anticipated, the MFC with CM53–750/Ti anode demonstrated superb maximum power density of 1179.08 mW/m2, which was 88.04% and 36.24% higher than that of MFC with CM53–385/Ti and CM53–600/Ti anode. Moreover, the charge transfer resistance of CM53–750/Ti (0.23 Ω) bioanode in MFC was 90.49% and 87.29% lower than that of CM53–385/Ti (2.42 Ω) and CM53–600/Ti (1.81 Ω) in MFC. The BCA method and high-throughput sequencing proved that CM53–750/Ti bioanode exhibited good biocompatibility and the function of screening the dominant bacteria for electricity generation. The results were mainly attributed to the synergistic effect of derived carbon, iron and Fe3O4 nanoparticles (NPs). Fe3O4 NPs and porous rod-like carbon promoted the enrichment and cultivation of microorganisms on the anode surface, while Fe NPs provided an efficient path for the transmission of extracellular electrons. This article proved that the carbonized derivatives of MOF have application potential in MFC.

Biodegradation of carbamazepine and production of bioenergy using a microbial fuel cell with bioelectrodes fabricated from devil fish bone chars

This work focused on developing inexpensive materials with desirable characteristics as bioanodes in Microbial Fuel Cells (MFC) for bioenergy production from the biodegradation of carbamazepine. This pharmaceutical compound is an emerging pollutant in water due to its presence in wastewater, persistence in conventional treatment plants, and widespread occurrence in water bodies. The materials were fabricated from devil fish bone chars synthesized by calcination process using a nitrogen atmosphere (BCN) and an air atmosphere (BCA). Their performances were compared with carbon felt (CF). Three cylindrical-shaped single-chamber MFC were constructed with each material and were operated with 50 mg/L of carbamazepine. Biodegradation efficiencies were estimated from the removal percentage of the carbamazepine and the chemical oxygen demand (COD). MFC electrochemical properties were characterized by linear sweep voltammetry, electrochemical impedance spectroscopy, and chronoamperometry. Biofilm formation on the materials was analyzed by environmental scanning electron microscopy. Results showed that MFC with BCN and BCA had better performance than CF. COD removal and carbamazepine biodegradation efficiencies of 87.5% and 79.58%, 81.1% and 77.88%, and 75.5% and 74.78% were obtained for BCN, BCA, and CF, respectively. Both bioanodes showed a maximum power density of 5.4 mW/m2 and Coulombic efficiency of ~14%, 210%, and ~ 116% higher than CF, an electron transfer resistance up two times lower, and a stable behavior higher than it. Micrographs confirmed the biofilm formation. Hence, these findings provide low-cost alternative materials to be used as bioanode in the sustainable construction of MFC applied to produce bioenergy and biodegrade carbamazepine.

Electrophoretic deposition of graphene oxide on carbon brush as bioanode for microbial fuel cell operated with real wastewater

Microbial fuel cell (MFC) is a promising technology for simultaneous wastewater treatment and energy harvesting. The properties of the anode material play a critical role in the performance of the MFC. In this study, graphene oxide was prepared by a modified hummer's method. A thin layer of graphene oxide was incorporated on the carbon brush using an electrophoretic technique. The deoxygenated graphene oxide formed on the surface of the carbon brush (RGO-CB) was investigated as a bio-anode in MFC operated with real wastewater. The performance of the MFC using the RGO-CB was compared with that using plain carbon brush anode (PCB). Results showed that electrophoretic deposition of graphene oxide on the surface of carbon brush significantly enhanced the performance of the MFC, where the power density increased more than 10 times (from 33 mWm−2 to 381 mWm−2). Although the COD removal was nearly similar for the two MFCs, i.e., with PCB and RGO-CB; the columbic efficiency significantly increased in the case of RGO-CB anode. The improved performance in the case of the modified electrode was related to the role of the graphene in improving the electron transfer from the microorganism to the anode surface, as confirmed from the electrochemical impedance spectroscopy measurements.

Fe3O4 nanospheres decorated reduced graphene oxide as anode to promote extracellular electron transfer efficiency and power density in microbial fuel cells

Fe3O4 nanospheres decorated reduced graphene oxide nanocomposites (Fe3O4-NS/rGO) with various Fe3O4 content are developed via a facile one-pot solvothermal synthetic procedure and applied for anode bio-electrocatalysts of microbial fuel cells (MFCs). Addition of reduced graphene oxide (rGO) nanosheets can effectively overcome the poor electron transportation efficiency of Fe3O4. Additionally, the bioaffinity of Fe3O4-NS/rGO anodes is promoted by incorporating with Fe3O4 nanospheres (Fe3O4-NS). These merits collectively result in the accelerated extracellular electron transfer (EET) efficiency and remarkable power density production on Fe3O4-NS/rGO bioanodes for MFCs. The maximum power outputs of MFCs with all Fe3O4-NS/rGO anodes are superior to that of carbon paper (CP), Fe3O4-NS and rGO anodes under the same regimes and conditions. Especially, the Fe3O4-NS/rGO (1.5:1) anode as the optimized ratio yields the maximum power density 1837.4 mW m−2 at the scan rate of 0.001 V s−1, this is much higher compared to other anodes. The characters of predominant power density output and extraordinary nanospheres morphology combining with the facile fabrication of nanocomposites electrocatalysts together suggest positive implication towards the practical implementation of high performance MFCs.

3D biofilm visualization and quantification on granular bioanodes with magnetic resonance imaging

The use of microbial fuel cells (MFCs) for wastewater treatment fits in a circular economy context, as they can produce electricity by the removal of organic matter in the wastewater. Activated carbon (AC) granules are an attractive electrode material for bioanodes in MFCs, as they are cheap and provide electroactive bacteria with a large surface area for attachment. The characterization of biofilm growth on AC granules, however, is challenging due to their high roughness and three-dimensional structure. In this research, we show that 3D magnetic resonance imaging (MRI) can be used to visualize biofilm distribution and determine its volume on irregular-shaped single AC granules in a non-destructive way, while being combined with electrochemical and biomass analyses. Ten AC granules with electroactive biofilm (i.e. granular bioanodes) were collected at different growth stages (3 to 21 days after microbial inoculation) from a multi-anode MFC and T1-weighted 3D-MRI experiments were performed for three-dimensional biofilm visualization. With time, a more homogeneous biofilm distribution and an increased biofilm thickness could be observed in the 3D-MRI images. Biofilm volumes varied from 0.4 μL (day 4) to 2 μL (day 21) and were linearly correlated (R2 = 0.9) to the total produced electric charge and total nitrogen content of the granular bioanodes, with values of 66.4 C μL−1 and 17 μg N μL−1, respectively. In future, in situ MRI measurements could be used to monitor biofilm growth and distribution on AC granules.

Synthesis of nickel-based layered double hydroxide (LDH) and their adsorption on carbon felt fibres: application as low cost cathode catalyst in microbial fuel cell (MFC)

ABSTRACT Following their successful utilization as novel bioanodes in Microbial Fuel Cells (MFCs), Layered Double Hydroxide (LDH) were tested in the present investigation, as promising cathodes to reduce electrons coming from oxidation of organic matter in the anode compartment, in the presence of oxygen used as successful oxidant. Therefore, the LDH samples Ni3Al-LDH with the ionic ratio Ni2+/Al3+ equal to 3, were synthesized and added by adsorption to Carbon Felt (CF) fibres. They were then stored separately in three electrolyte solutions KCl, NiCl2 and AlCl3 used as catholytes in the MFCs. Effects of the active cationic sites located inside the Ni3Al-LDH on these electrolytes, were discussed in terms of energies produced by these MFCs. The structure and morphology of the synthesized LDH, were studied by using the analytical techniques XRD, FTIRS and SEM, while the electrode performances of the LDH-electrodes were investigated with the electrochemical methods CV and EIS. It was revealed that the CF modified with Ni3Al-LDH cathode and conditioned in the NiCl2 electrolyte solution yielded the highest energy harvesting for the MFC (i.e. 3.2 µW/cm2). This power density output was similar to previous clean one-compartment MFC. However, it was less expensive than an Enzymatic Fuel Cell (45 µW/cm2), making in evidence the highest cost of the material. Thus, by taking into account these encouraging findings, the low cost materials used in MFCs held great promise for practical application in electrochemical power devices and therefore fruit waste treatment. Abbreviations: ACFC: Air Cathode Fuel Cell; ADEFC: Alkaline Direct Ethanol Fuel Cell; AFC: Alcaline Fuel Cell; BET: Brunauer–Emmett–Teller; BFC: Biological Fuel Cell; CF: Carbon Felt; CV: Cyclic Voltammetry; DGFC: Direct Glucose Fuel Cell; DMFC: Direct Methanol Fuel Cell; EFC: Enzymatic Fuel Cell; EIS: Electrochemical Impedance Spectroscopy; FC: Fuel Cell; FTIR: Fourier Transform Infra Red spectroscopy; LDH: Layered Double Hydroxide; MEC: Microbial Electrolysis Cell; MFC: Microbial Fuel Cell; Mg-Al--LDH: Layered Double Hydroxide Magnesium-Aluminium-Carbonate; Ni-Al-LDH: Layered Double Hydroxide Nickel-Aluminium; OCP: Open Circuit Potential; SEM: Scanning Electron Microscope; TG/DTA: ThermoGravimetric and Differential Thermal Analysis; XRD: X-Ray Diffraction.

Development of coupled redox active network in Ca-alginate polymer for immobilization of Pseudomonas putida 1046 on electrode surface

Redox activated polymeric gels on the anode surface present an approach for creating artificial biofilms thus ensuring highly effective extracellular electron transfer (EET) of electrogens in microbial fuel cells (MFCs). A new coupled redox reaction network was developed for functionalization of alginate polymerized on carbon felt and fast immobilization of bacteria. For this purpose, four different fabricated polymer-modified materials, consisting of single or mixed redox active dyes have been examined toward electrochemical activity and stability at abiotic as well as biotic conditions. The designed electrodes consisting of thiazolyl blue formazan/phenazine methosulfate (PMS) showed well-defined reduction and oxidation peaks with a formal potential of +91 mV (vs. SHE). The peaks' current exceeded two times those of PMS-alginate and over ten times those of thiazolyl blue formazan-alginate electrodes, while the alginate control did not express any activity. Selected redox polymer matrices on carbon felt supports were used for immobilization of bacteria Pseudomonas putida 1046. The modified bioanodes have been poised continuously at positive potentials +0.605 V and +0.705 V (vs. SHE) and current density of 35 ± 2 mA/m2 has been achieved. The redox activity and charge transfer properties of the modified bioanodes were investigated by means of cyclic voltammetry and electrochemical impedance spectroscopy. The results in this study show that the non-conductivity of the alginate polymer can be overcome by the addition of artificial redox dyes thiazolyl blue formazan and PMS, creating a coupled redox network or by expression of cellular produced redox compound mediating the electron transfer though the polymer, so that the fabricated bioelectrodes can be applied as bioanodes in MFC.

Development of immobilised bioanode for microbial fuel cell

The efficiency of Microbial fuel cell (MFC) performance is based on how well the electron is transferred and finally turned into electrical power in a complete electrical circuit. However, MFC power capacity is still very low compare to similar conceptual fuel cell and one of the major reasons is due to high internal resistance imposed by macro-environment of an MFC. In the present research, the objectives were to develop bio-based anode and its usage in the MFC for power production. The power production was compared using free cells in MFC. The bioanode was developed by mixing cells solution and graphite granules overnight before adding alginate and subjected to homogenisation. The mixture was then immobilised using entrapment method to obtained uniform beads. Initial study was conducted using glucose as fuel and both open circuit voltage (OCV) and closed circuit voltage (CCV) were evaluated using MFC. Results show OCV increased gradually and still increased after 6 h of operation compared to free cells. In CCV profile for free cells show a decrease in voltage generated but then rapidly increased which indicates a ‘power-overshoot’ phenomenon which was not observe on immobilised based bioanode MFC. The maximum OCV was 2-fold higher for immobilised based bioanode compared to free cells. In conclusion, the immobilised based anode or bio-anode produced was proved viable for MFC application.

Influence of the thickness of the capacitive layer on the performance of bioanodes in Microbial Fuel Cells

Earlier it was shown, that it is possible to operate a Microbial Fuel Cell with an integrated capacitive bio-anode with a thickness of 0.5 mm and thereby to increase the power output. The integrated capacitive bioanode enabled storage of electricity produced by microorganisms directly inside an MFC. To increase the performance of this integrated storage system even more; the thickness of the capacitive electrode was varied: 0.2 mm, 0.5 mm and 1.5 mm. Each of these capacitive electrodes was tested in the MFC setup during polarization curves and charge–discharge experiments for the steady-state current density and the maximum charge recovery.The capacitive electrode with a thickness of 0.2 mm outperformed the other electrodes in all experiments: it reached a maximum current density of 2.53 Am−² during polarization curves, and was able to store a cumulative total charge of 96013 cm−² during charge–discharge experiments. The highest relative charge recovery for this electrode was 1.4, which means that 40% more current can be gained from this capacitive electrode during intermittent operation compared to continuous operation of a noncapacitive electrode. Surprisingly it was possible to increase the performance of the MFC through decrease of the thickness of the capacitive electrode.