Search Results (33)

Microbial fuel cells (MFCs) generate electricity through the microbial oxidation of organic waste. However, the inherent electrochemical performance of carbon felt (CF) electrodes is relatively poor and requires enhancement. In this study, nickel oxide (NiO) was successfully loaded onto CF to improve its electrode performance, thereby enhancing the electricity generation capacity of MFCs during the degradation of treated wastewater. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy diffusion spectrometer (EDS) analyses confirmed the successful deposition of NiO on the CF surface. The modification enhanced both the conductivity and capacitance of the electrode and increased the number of microbial attachment sites on the carbon fiber filaments. The prepared CF–NiO electrode was employed as the anode in an MFC, and its electrochemical and energy storage performance were evaluated. The maximum power density of the MFC with the CF–NiO anode reached 0.22 W/m², compared to 0.08 W/m² for the unmodified CF anode. Under the C1000-D1000 condition, the charge storage capacity and total charge output of the CF–NiO anode were 1290.03 C/m² and 14,150.03 C/m², respectively, which are significantly higher than the 452.9 C/m² and 6742.67 C/m² observed for the CF anode. These results indicate notable improvements in both power generation and energy storage performance. High-throughput gene sequencing of the anodic biofilm following MFC acclimation revealed that the CF–NiO anode surface hosted a higher proportion of electroactive bacteria. This suggests that the NiO modification enhances the biodegradation of organic matter and improves electricity generation efficiency. Full article

Water pollution is an alarming and critical environmental challenge that demands immediate attention. In addition to this, the world is also facing an energy crisis of ever-increasing proportions. Managing these issues through a sustainable approach is the need of the hour. In this context, microbial fuel cell (MFC) technology, with its dual capability to treat wastewater with simultaneous power generation, is gaining recognition as a sustainable solution. The current study was designed to evaluate the impact of a modified MFC anode, i.e., CoFe₂O₄@CF, Nb₂C-MXene@CF, and CoFe₂O₄/Nb₂C-MXene@CF, on the performance of MFC technology. A hydrothermal technique was used to synthesize CoFe₂O₄ and Nb₂C-MXene, followed by characterization using XRD, SEM, and EDX tools. The results demonstrated that CoFe₂O₄/Nb₂C-MXene@CF significantly enhanced the working performance of a MFC as compared to CoFe₂O₄@CF and Nb₂C-MXene@CF. The MFC with this configuration produces a stable voltage (699.8 mV), coulombic efficiency (23.8%), COD removal (84%), and power density (394.272 mWm⁻²), with corresponding current density (888 mAm⁻²). These improvements were possibly due to the excellent electrocatalytic activity and strong biocompatibility of the modifier. Conclusively, the CoFe₂O₄/Nb₂C-MXene composite is ascertained to be an emphatic anode material for MFCs with superior characteristics. Full article

Microbial fuel cells (MFCs) are a candidate for green energy sources due to microbes’ ability to generate charge in their metabolic processes. The main problem in MFCs is slow charge transfer between microorganisms and electrodes. Several methods to improve charge transfer have been used until now: modification of microorganisms by conductive polymers, use of lipophilic mediators, and conductive nanomaterials. We created an MFC with a graphite anode, covering it with 9,10-phenatrenequinone and polypyrrole-modified Saccharomyces cerevisiae with and without 10 nm sphere gold nanoparticles. The MFC was evaluated using cyclic voltammetry and power density measurements. The peak current from cyclic voltammetry measurements increased from 3.76 mA/cm² to 5.01 mA/cm² with bare and polypyrrole-modified yeast, respectively. The MFC with polypyrrole- and nanoparticle-modified yeast reached a maximum power density of 150 mW/m² in PBS with 20 mM Fe(III) and 20 mM glucose, using a load of 10 kΩ. The same MFC with the same load in wastewater reached 179.2 mW/m². These results suggest that this MFC configuration can be used to improve charge transfer. Full article

A nanocomposite of multi-walled carbon nanotubes (MWCNTs) decorated with molybdenum dioxide (MoO₂) nanoparticles is fabricated through the reduction of phosphomolybdic acid hydrate on functionalized MWCNTs in a hydrogen–argon (10%) atmosphere in a tube furnace. The MoO₂/MWCNTs composite is proposed as an anodic modification material for microbial fuel cells (MFCs). MWCNTs have outstanding physical and chemical peculiarities, with functionalized MWCNTs having substantially large electroactive areas. In addition, combined with the exceptional properties of MoO₂ nanoparticles, the synergistic advantages of functionalized MWCNTs and MoO₂ nanoparticles give a MoO₂/MWCNTs anode a large electroactive area, excellent electronic conductivity, enhanced extracellular electron transfer capacity, and improved nutrient transfer capability. Finally, the power harvesting of an MFC with the MoO₂/MWCNTs anode is improved, with the MFC showing long-term repeatability of voltage and current density outputs. This exploratory research advances the fundamental application of anodic modification to MFCs, simultaneously providing valuable guidance for the use of carbon-based transition metal oxide nanomaterials in high-performance MFCs. Full article

This research sought to enhance the efficiency and biocompatibility of anodes in bioelectrochemical systems (BESs) such as microbial fuel cells (MFCs), with an aim toward large-scale, real-world applications. The study focused on the effects of acid-heat treatment and chemical modification of three-dimensional porous pristine carbon felt (CF) on power generation. Different treatments were applied to the pristine CF, including coating with carbon nanofibers (CNFs) dispersed using dodecylbenzene sulfonate (SDBS) surfactant and biopolymer chitosan (CS). These processes were expected to improve the hydrophilicity, reduce the internal resistance, and increase the electrochemically active surface area of CF anodes. A high-resolution scanning electron microscopy (HR-SEM) analysis confirmed successful CNF coating. An electrochemical analysis showed improved conductivity and charge transfer toward [Fe(CN)6]^3−/4− redox probe with treated anodes. When used in an air cathode single-chamber MFC system, the untreated CF facilitated quicker electroactive biofilm growth and reached a maximum power output density of 3.4 W m⁻², with an open-circuit potential of 550 mV. Despite a reduction in charge transfer resistance (R_ct) with the treated CF anodes, the power densities remained unchanged. These results suggest that untreated CF anodes could be most promising for enhancing power output in BESs, offering a cost-effective solution for large-scale MFC applications. Full article

Microbial fuel cells (MFCs) have exhibited potential in energy recovery from waste. In this study, an MFC reactor with a polyaniline–sodium alginate–graphene oxide (PANI–SA–GO)/carbon brush (CB) hydrogel anode achieved maximum power density with 4970 mW/m³ and produced a corresponding current density of 4.66 A/m², which was 2.72 times larger than the MFC equipped with a carbon felt film (CF) anode (1825 mW/m³). Scanning electron microscopy indicated that the PANI-SA-GO/CB composite anode had a three-dimensional macroporous structure. This structure had a large specific surface area, providing more sites for microbial growth and attachment. When the charging-discharging time was set from 60 min to 90 min, the stored charge of the PANI-SA-GO/CB hydrogel anode (6378.41 C/m²) was 15.08 times higher than that of the CF (423.05 C/m²). Thus, the mismatch between power supply and electricity consumption was addressed. This study provided a simple and environment-friendly modification method and allowed the prepared PANI–SA–GO/CB hydrogel anode to markedly promote the energy storage and output performance of the MFC. Full article

The development of MFC using electroactive industrial microorganisms has seen a surge of interest because of the co-generation for bioproduct and electricity production. Vibrio natriegens as a promising next-generation industrial microorganism chassis and its application for microbial fuel cells (MFC) was first studied. Mediated electron transfer was found in V. natriegens MFC (VMFC), but V. natriegens cannot secrete sufficient electron mediators to transfer electrons to the anode. All seven electron mediators supplemented are capable of improving the electronic transfer efficiency of VMFC. The media and carbon sources switching study reveals that VMFCs have excellent bioelectricity generation performance with feedstock flexibility and high salt-tolerance. Among them, 1% glycerol as the sole carbon source produced the highest power density of 111.9 ± 6.7 mW/cm². The insight of the endogenous electronic mediators found that phenazine-1-carboxamide, phenazine-1-carboxylic acid, and 1-hydroxyphenazine are synthesized by V. natriegens via the shikimate pathway and the phenazine synthesis and modification pathways. This work provides the first proof for emerging industrial biotechnology chassis V. natriegens as a novel high salt-tolerant and feedstock flexibility electroactive microorganism for MFC, and giving insight into the endogenous electron mediator biosynthesis of VMFC, paving the way for the application of V. natriegens in MFC and even microbial electrofermentation (EF). Full article

A three-dimensional (3D) anode is essential for high-performance microbial fuel cells (MFCs). In this study, 3D porous carbon monoliths from a wax gourd (WGCM) were obtained by freeze-drying and carbonization. Nano-TiO₂ was further coated onto the surface of WGCM to obtain a nano-TiO₂/WGCM anode. The WGCM anode enhanced the maximum power density of MFCs by 167.9% compared with the carbon felt anode, while nano-TiO₂/WGCM anode additionally increased the value by 45.8% to achieve 1396.2 mW/m². WGCM enhancement was due to the 3D porous structure, the good conductivity and the surface hydrophilicity, which enhanced electroactive biofilm formation and anodic electron transfer. In addition, nano-TiO₂ modification enhanced the enrichment of Acinetobacter, an electricigen, by 31.0% on the anode to further improve the power production. The results demonstrated that the nano-TiO₂/WGCM was an effective anode for power enhancement in MFCs. Full article

This study investigated how anode electrode modification with iron affects the microbiome and electricity generation of microbial fuel cells (MFCs) fed with municipal wastewater. Doses of 0.0 (control), 0.05, 0.1, 0.2, and 0.4 g Fe₂O₃ per the total anode electrode area were tested. Fe₂O₃ doses from 0.05 to 0.2 g improved electricity generation; with a dose of 0.10 g Fe₂O₃, the cell power was highest (1.39 mW/m²), and the internal resistance was lowest (184.9 Ω). Although acetate was the main source of organics in the municipal wastewater, propionic and valeric acids predominated in the outflows from all MFCs. In addition, Fe-modification stimulated the growth of the extracellular polymer producers Zoogloea sp. and Acidovorax sp., which favored biofilm formation. Electrogenic Geobacter sp. had the highest percent abundance in the anode of the control MFC, which generated the least electricity. However, with 0.05 and 0.10 g Fe₂O₃ doses, Pseudomonas sp., Oscillochloris sp., and Rhizobium sp. predominated in the anode microbiomes, and with 0.2 and 0.4 g doses, the electrogens Dechloromonas sp. and Desulfobacter sp. predominated. This is the first study to holistically examine how different amounts of Fe on the anode affect electricity generation, the microbiome, and metabolic products in the outflow of MFCs fed with synthetic municipal wastewater. Full article

Bioelectrochemical systems with denitrifying biocathodes have been of interest for the removal of nitrate in decentralized wastewater treatment applications. Only a few studies have directly focused on this application, but the removal rates have been very low. This study evaluated the operational parameters that affect the nitrate removal of two-chambered microbial fuel cells (MFCs) with a biocathode, particularly, the carbon to nitrogen ratio (C:N) and proton diffusivity across electrode chambers. The results show that proton diffusion across a proton exchange membrane is not a limiting step in nitrogen removal performance. At C:N ratios of 4 and 8, biocathodes with a continuously supplied carbon source at the anode were able to achieve complete nitrogen removal at a rate of 0.97 ± 0.21 and 1.15 ± 0.13 mg N L⁻¹ d⁻¹, respectively. However, as the C:N ratio increased from 4, 8, 16, and 32, the electrode potentials decreased accordingly. Ratio 4 C:N had a cathodic reduction potential of +66.1 ± 5.3 mV vs. SHE and dropped to −78.6 ± 9.8 mV vs. SHE at 32 C:N. The cathode electrode potential can be controlled by way of the carbon concentrations at the anode, which can have major indirect implications on the evolution of cathodic microbial communities that have preference to particular ranges of reduction potentials. The cathodic biofilms in this study were dominated by the phyla Proteobacteria, Acidobacteria, Bacteroidetes and Nitrospirae, which are known to have key denitrifying microorganisms. The genus Stenotrophomonas was found in abundance within the attached cathode biofilm and to a lesser extent in the suspended biomass. Vibrio, Acidobacteria_Gp4, Nitrosomonas, and Candidatus Competibacter were also cultivated in both the suspended and attached biomass. Nitrospira was only found in the attached biofilm. Regardless of operational scheme, nitrogen removal was improved at low C:N ratios, with 8 C:N having the best performance overall. This indicates that higher C:N ratios than were previously explored (>4 C:N) provide sufficient coulombs to facilitate denitrification at the cathode even while the anodic CEs remain low. Reactor design modifications should be considered to fully support robust denitrifying communities, enhancing the overall nitrogen removal for decentralized wastewater treatment applications. Full article

Anode modification with carbon nanomaterials is an important strategy for the improvement of microbial fuel cell (MFC) performance. The presence of nitrogen in the carbon network, introduced as active nitrogen functional groups, is considered beneficial for anode modification. In this aim, nitrogen-containing carbon nanostructures (NCNs) with different morphologies were obtained via carbonization of polyaniline and were further investigated as anode modifiers in MFCs. The present study investigates the influence of NCN morphology on the changes in the anodic microbial community and MFC performance. Results show that the nanofibrillar morphology of NCNs is beneficial for the improvement of MFC performance, with a maximum power density of 40.4 mW/m², 1.25 times higher than the anode modified with carbonized polyaniline with granular morphology and 2.15 times higher than MFC using the carbon cloth-anode. The nanofibrillar morphology, due to the well-defined individual nanofibers separated by microgaps and micropores and a better organization of the carbon network, leads to a larger specific surface area and higher conductivity, which can allow more efficient substrate transport and better bacterial colonization with greater relative abundances of Geobacter and Thermoanaerobacter, justifying the improvement of MFC performance. Full article

Although microbial fuel cells (MFCs) have been developed over the past decade, they still have a low power production bottleneck for practical engineering due to the ineffective interfacial bioelectrochemical reaction between exoelectrogens and anode surfaces using traditional carbonaceous materials. Constructing anodes from biomass is an effective strategy to tackle the current challenges and improve the efficiency of MFCs. The advantage features of these materials come from the well-decorated aspect with an enriched functional group, the turbostratic nature, and porous structure, which is important to promote the electrocatalytic behavior of anodes in MFCs. In this review article, the three designs of biomass-derived carbon anodes based on their final products (i.e., biomass-derived nanocomposite carbons for anode surface modification, biomass-derived free-standing three-dimensional carbon anodes, and biomass-derived carbons for hybrid structured anodes) are highlighted. Next, the most frequently obtained carbon anode morphologies, characterizations, and the carbonization processes of biomass-derived MFC anodes were systematically reviewed. To conclude, the drawbacks and prospects for biomass-derived carbon anodes are suggested. Full article

Microbial Fuel Cell (MFC) is a bio-electrochemical system that generates electricity by anaerobic oxidation of substrates. An anode is the most critical component because the primary conversion of wastewater into electrons and protons takes place on the surface of the anode, where a biofilm is formed. This paper describes the essential properties of the anode and classifies its types according to the material used to make it. Anode material is responsible for the flow of electrons generated by the microorganism; hence biocompatibility and conductivity can considered to be the two most important properties. In this paper, the various modification strategies to improve the performance of anodes of MFC are explained through the review of researchers’ published work in this field. The shape and size of the anode turned out to be very significant as the microbial growth depends on the available surface area. The attachment of biofilm on the surface of an anode largely depends on the interfacial surface chemistry. Methods for improving MFC performance by altering the anode material, architecture, biocompatibility, and longevity are discussed with a future perspective giving special importance to the cost. Full article

Electrically conductive polymers are promising materials for charge transfer from living cells to the anodes of electrochemical biosensors and biofuel cells. The modification of living cells by polypyrrole (PPy) causes shortened cell lifespan, burdens the replication process, and diminishes renewability in the long term. In this paper, the viability and morphology non-modified, inactivated, and PPy-modified yeasts were evaluated. The results displayed a reduction in cell size, an incremental increase in roughness parameters, and the formation of small structural clusters of polymers on the yeast cells with the increase in the pyrrole concentration used for modification. Yeast modified with the lowest pyrrole concentration showed minimal change; thus, a microbial fuel cell (MFC) was designed using yeast modified by a solution containing 0.05 M pyrrole and compared with the characteristics of an MFC based on non-modified yeast. The maximal generated power of the modified system was 47.12 mW/m², which is 8.32 mW/m² higher than that of the system based on non-modified yeast. The open-circuit potentials of the non-modified and PPy-modified yeast-based cells were 335 mV and 390 mV, respectively. Even though applying a PPy layer to yeast increases the charge-transfer efficiency towards the electrode, the damage done to the cells due to modification with a higher concentration of PPy diminishes the amount of charge transferred, as the current density drops by 846 μA/cm². This decrease suggests that modification by PPy may have a cytotoxic effect that greatly hinders the metabolic activity of yeast. Full article

The development of high-performance anode materials is one of the greatest challenges for the practical implementation of Microbial Fuel Cell (MFC) technology. Copper (Cu) has a much higher electrical conductivity than carbon-based materials usually used as anodes in MFCs. However, it is an unsuitable anode material, in raw state, for MFC application due to its corrosion and its toxicity to microorganisms. In this paper, we report the development of a Cu anode material coated with a corrosion-resistant composite made of Polydimethylsiloxane (PDMS) doped with carbon nanofiber (CNF). The surface modification method was optimized for improving the interfacial electron transfer of Cu anodes for use in MFCs. Characterization of CNF-PDMS composites doped at different weight ratios demonstrated that the best electrical conductivity and electrochemical properties are obtained at 8% weight ratio of CNF/PDMS mixture. Electrochemical characterization showed that the corrosion rate of Cu electrode in acidified solution decreased from (17 ± 6) × 10³ μm y⁻¹ to 93 ± 23 μm y⁻¹ after CNF-PDMS coating. The performance of Cu anodes coated with different layer thicknesses of CNF-PDMS (250 µm, 500 µm, and 1000 µm), was evaluated in MFC. The highest power density of 70 ± 8 mW m⁻² obtained with 500 µm CNF-PDMS was about 8-times higher and more stable than that obtained through galvanic corrosion of unmodified Cu. Consequently, the followed process improves the performance of Cu anode for MFC applications. Full article