Deposition of Iron on Graphite Felts by Thermal Decomposition of Fe(CO)(5) for Anodic Modification of Microbial Fuel Cells

In this paper, a new efficient anodic modification method for microbial fuel cells (MFCs) was developed. Fe was deposited on graphite felt by thermo decomposition of Fe(CO)(5) and then oxidized to Fe(III) oxides. Fe(III) oxides were proved Fe2O3 and FeOOH. The unmodified and Fe modified graphite felts were utilized as anode in MFCs. Fe(III) oxides on anode promoted the power generation of MFCs. The maximum power density of 18W/m(3) and the internal resistance of 51 Omega were obtained by the MFC with Fe modified anode, which was significantly superior to the performance of the MFC with unmodified anode. The electrochemical activity and attached bacterial density of Fe modified graphite felts were significantly higher than those of the unmodified graphite felts. This new method for anodic preparation promoted power generation, replaced manual brushing and Nafion solution, and reduced the cost

Int. J. Electrochem. Sci.

In this paper, PANI was electrochemically synthesized on graphite felt by cyclic voltammetry (CV), and PANI modified and unmodified graphite felts were utilized as anode of MFCs. The power generation of MFCs, electrochemical activity of graphite felts and anodic cell mass were compared. The maximum power density and the internal resistance of MFC with PANI modified anode were 4 W/m(3) and 156 Omega respectively, yet those of MFC with unmodified anode were 1.7 W/m(3) and 358 Omega. The startup time of MFC with PANI modified anode shortened and the electrochemical activity and cell mass of PANI modified graphite felt were significantly higher than that of the unmodified graphite felt. With no use of manual brushing and Nafion solution, the electrochemical synthesis of PANI by CV on graphite felt for anodic modification improved power generation and reduced the cost of MFCs.In this paper, PANI was electrochemically synthesized on graphite felt by cyclic voltammetry (CV), and PANI modified and unmodified graphite felts were utilized as anode of MFCs. The power generation of MFCs, electrochemical activity of graphite felts and anodic cell mass were compared. The maximum power density and the internal resistance of MFC with PANI modified anode were 4 W/m(3) and 156 Omega respectively, yet those of MFC with unmodified anode were 1.7 W/m(3) and 358 Omega. The startup time of MFC with PANI modified anode shortened and the electrochemical activity and cell mass of PANI modified graphite felt were significantly higher than that of the unmodified graphite felt. With no use of manual brushing and Nafion solution, the electrochemical synthesis of PANI by CV on graphite felt for anodic modification improved power generation and reduced the cost of MFCs

Biomimetic Nucleation and Morphology Control of CaCO_3 in PAAm Hydrogels Synthesized from Lyotropic Liquid Crystalline Templates

Hydrogels have been thought to be the material which can provide appealing replacements of biological organisms. Pores of hydrogeis synthesized from lyotropic liquid crystalline (LLC) templates were smaller in size and more uniform than those of traditional hydrogels. LLC poly-acrylamide (PAAm) hydrogels were used as the growth media of CaCO_3. After copolymerized with acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS),LLC hydrogels were modified with COOH and SO_3H, respectively. The effect of functional groups on the biomitactic mineralization of CaCO_3 was studied. Most of crystals from traditional hydrogels are rhombohedral and could not form aggregates. Only a few could aggregate and have a particular morphology with irregular orientation of subcrystal. Compared with crystals separated from traditional hydrogels, crystals growing in the LLC hydrogels were much more regulated and could form aggregates with particular morphology and regular orientation, that is,face (104) of rhombohedral subcrystals parallel to the surface of the macrocrystals. Modification of COOH and SO_3H groups made CaCO_3 subcrystal align more tightly. COOH had minor influences on the crystal orientation and small modification to the aggregate morphology. SO_3H groups could change the crystal orientation and morphology effectively. The aggregates are pseudo-spherical and the face perpendicularity to the face (104) parallels to the surface of the aggregates

Prog. Chem.

Microbial electrolysis cells (MEC) invented on the basis of microbial fuel cells (MFC) provide a novel method for biohydrogen production. This paper reviews the research progress of MEC ever since its invention in 2005. The principle of MEC and the evaluating parameters of the system are briefly introduced. Hydrogen production performance of MEC in different system architectures and electrode materials are compared. The existing problems and limiting factors of MEC for its practical utilization are discussed and the future research trends, as well as research approaches of MEC are proposed. Finally, the prospective applications of MEC in hydrogen production from biomass and energy recovery from organic wastewater are also stated.Microbial electrolysis cells (MEC) invented on the basis of microbial fuel cells (MFC) provide a novel method for biohydrogen production. This paper reviews the research progress of MEC ever since its invention in 2005. The principle of MEC and the evaluating parameters of the system are briefly introduced. Hydrogen production performance of MEC in different system architectures and electrode materials are compared. The existing problems and limiting factors of MEC for its practical utilization are discussed and the future research trends, as well as research approaches of MEC are proposed. Finally, the prospective applications of MEC in hydrogen production from biomass and energy recovery from organic wastewater are also stated

Deposition of Fe on graphite felt by thermal decomposition of Fe(CO)(5) for effective cathodic preparation of microbial fuel cells

In this paper, an efficient and cost-effective method to prepare cathodes for microbial fuel cells (MFCs) was developed. Fe(CO)(5) was decomposed and Fe was deposited on graphite felts for cathodic preparation. The unmodified, Pt modified and Fe modified graphite felts were utilized as cathodes in MFCs and power generation was compared. The maximum power density of MFCs with unmodified, Pt modified and Fe modified cathodes were respectively 288, 866 and 925 mW/m(3). The internal resistance of MFCs with unmodified, Pt modified and Fe modified cathodes were respectively 505, 384 and 278 Omega. The results of multiple analyses confirmed that Fe on cathode was Fe2O3 and FeOOH and Fe(III) oxides as cathodic catalysts improved the electrochemical activity and promoted power generation. The greatest advantage of new method for cathodic preparation was the replacing manual brushing and Nafion solution and decreasing the cost. (C) 2013 Elsevier Ltd. All rights reserved

Int. J. Electrochem. Sci.

This study explores the use of MFCs to anodic dechlorination of aromatic chlorides such as 2,4,6-trichlorophenol (2,4,6-TCP). Mixed microbe, isolated from submarine sediment, was used to detect its dechlorination performance in microbial fuel cells device. Moreover, It was confirmed that exoelectrogen microbe accelerated the 2,4,6-TCP degrading in MFCs. Dechlorination efficiency of 2,4,6-TCP in the anode of MFCs could reach 86.51%, accompanying with power generation. Besides, the pathway of 2,4,6-TCP degradation in MFCs was proved. Dichlorophenol, a major intermediate product for TCP dechlorination, was degraded into CO2. This study explores the use of MFCs to anodic dechlorination of aromatic chlorides such as 2,4,6-trichlorophenol (2,4,6-TCP). Mixed microbe, isolated from submarine sediment, was used to detect its dechlorination performance in microbial fuel cells device. Moreover, It was confirmed that exoelectrogen microbe accelerated the 2,4,6-TCP degrading in MFCs. Dechlorination efficiency of 2,4,6-TCP in the anode of MFCs could reach 86.51%, accompanying with power generation. Besides, the pathway of 2,4,6-TCP degradation in MFCs was proved. Dichlorophenol, a major intermediate product for TCP dechlorination, was degraded into CO2.</p

Polyaniline and iron based catalysts as air cathodes for enhanced oxygen reduction in microbial fuel cells

The catalyst for oxygen reduction in a cathode is vital for power production in microbial fuel cells (MFCs). In this study, non-precious metal catalysts were prepared by a high-temperature treatment of the iron containing polyaniline as both nitrogen and carbon precursor. These catalysts showed very positive onset potentials and less than 3% yield of hydrogen peroxide in the whole potential range, which matched the state-of-the-art Pt/C. The MFC with a bare cathode only produced a maximum power density of 1.32 W m(-3), while the MFCs with a PANI(900), PANI-Fe-700, and PANI-Fe-900 cathode had a maximum power density of 3.00 W m(-3), 7.45 W m(-3), and 12.54 W m(-3), respectively. Physical and chemical characterizations of the catalysts indicated that iron coordinated with pyridinic nitrogen hosted in micropores was responsible for the high catalytic activity. These results demonstrate that these catalysts are excellent cathodes for MFCs due to their high catalytic activity, strong stability and low cost.</p

Removal of chemical oxygen demand (COD) and heavy metals by catalytic ozonation-microbial fuel cell and Acidithiobacillus ferrooxidans leaching in flotation wastewater (FW)

A catalytic ozonation-microbial fuel cell and Acidithiobacillus ferrooxidans leaching process was used in treating flotation wastewater to remove chemical oxygen demand (COD) and heavy metals in this study. The results indicated that when adding 1 g/L of manganese/modified activated carbon catalyst and 1.5 g/min ozone flow, the COD could be degraded from 2,043.67 mg/L to 711.4 mg/L. After that, the COD could continue decreasing down to 72.56 mg/L through an air-cathode single chamber microbial fuel cell (SCMFCs), coated with 0.4 mg/cm(2) platinum catalyst, after 15 days. Meanwhile, the maximum voltages and the ultimate power density of the SCMFCs reached 378.96 mV and 7,608.35 mW/m(2), respectively. For filter residue, when 1.2 g/L Fe3+, 10% (m/v) filter residue, and 10% Acidithiobacillus ferrooxidans were added, the copper leaching rate could reach 92.69% after 7 days if the pH values were adjusted to 1.9. Furthermore, the other heavy metals were also decreased to a level lower than the pollution control standard (Chinese standard GB3838-2002). The leaching parameters in terms of pH, redox potential, and cyclic voltammetry showed that the addition of an appropriate concentration of Fe3+ to the leaching systems was beneficial to copper dissolution

Anodic electron shuttle mechanism based on 1-hydroxy-4-aminoanthraquinone in microbial fuel cells

In microbial fuel cells (MFCs), the electron transfer from microorganisms to the cell anode is a decisive factor on the power output. Though quinone derivatives can function as electron shuttles, the electron shuttle pathways have so far not been demonstrated. In this paper, the mechanism of electron shuttle via an exogenous mediator was studied in MFCs using Geobacter metallireducens (G. metallireducens). 1-hydroxy-4-aminoanthraquinone was labeled by fluorescamine and the product (HAQ-F) showed strong and stable fluorescence. The addition of HAQ-F into MFCs increased cell voltage from 170 mV to 290 mV, suggesting that the redox mediator could facilitate electron transfer from bacteria to anode. Further, confocal laser scanning microscopy imaging indicated that HAQ-F was present in microbial cells, demonstrating that the redox mediator shuttled across the membranes to get reduced within cells. (C) 2010 Elsevier B.V. All rights reserved