KR20170031352A - Method for manufacturing a renewable energy storage and utilization equipment using microbial fuel cells - Google Patents

Abstract

The present invention relates to a new and renewable energy generation system which dramatically improves generation and storage of electricity by connecting a renewable energy generation system such as solar power to a microorganism fuel cell system using organic wastewater and heavy metal wastewater. The present invention has a novel advantage of electricity production together with organic wastewater treatment in comparison with an existing storage system capable of only charge and discharge. In addition, an energy recovery system of a microorganism cell connected with a heavy metal regeneration system can be used, and also heavy metal wastewater contaminated with complex heavy metal ions can be used.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a storage and use device for renewable energy using a microbial fuel cell,

The present invention relates to a method of storing power of photovoltaic power generation in an oxidized form of heavy metals such as hexavalent chromium, cobalt cobalt and manganese, and using the stored heavy metals as an electron absorber to develop microbial high power, .

Oxygen microbial fuel cells (O ₂ -MFCs) have been studied extensively in domestic and foreign fields for the potential of improvement of power output. However, since they are still weak in energy output, they are difficult to commercialize because they are weaker in competitiveness with other energy production technologies. In the reductive electrode chamber of the microbial fuel cell, when the heavy metal ion having a high reduction potential as the final electron acceptor is used, the electron transfer rate is faster than that of oxygen, and the concentration can be increased. For this reason, not only the microbial fuel cell can be efficiently used for the removal or recovery of heavy metals, but also the heavy metal ions in the industrial wastewater can be efficiently used for producing the output of the battery for electric power production. A paper with remarkably improved power output was published. Therefore, it is very advantageous to construct a microbial fuel cell by continuously passing single wastewater or mixed wastewater directly to the reduction electrode chamber of a microbial fuel cell.

Another problem that limits the performance of microbial fuel cells is that the reduction type nicotin amide dinucleotide (NADH) and flavin adenosine dinucleotide (FADH ₂ ), which are produced by anaerobic electron-emitting microorganisms such as metal-reducing bacteria in the oxidizing electrode chamber metabolize organic matter, The catalyst is reduced by transferring electrons to the catalyst of the extracellular membrane, and the electrons of the catalyst are transferred to the underlying oxidation electrode. The electron / hole generation rate of the electrocatalyst is accelerated by the catalytic reaction to increase the concentration of electrons / holes. The obstacle in accelerating the electron transfer to the oxidation electrode is only the electron transfer resistance between the electrode and the catalyst interface. In order to increase power production, the generated electrons must be transferred to the reduction electrode through an external lead connected to the background oxide electrode conductor at a high rate.

If these electrons are moved away from the background oxide electrode at high speed, the electrons will recombine with the holes in the catalyst sites, and the electrons will disappear. The result of this recombination of the positive and negative amounts is heat and light and disappears again, so that the drift velocity of the electron decreases and the electron migration rate and the amount of current decrease. Conversely, as the amount of current decreases due to various factors, the recombination of electrons and holes accelerates and the energy output to be obtained will also decrease. This output reduction is due to the fact that the total current is determined by the low current density of one of the two electrodes, so that if the reaction at the reductive electrode is slower than that of the oxidized electrode, the energy production of the battery may be severely limited. For example, an electrochemical reduction reaction of oxygen molecules in a carbon reduction electrode is a slow reaction of an organic substance oxidation reaction such as acetate in an oxidation electrode coated with a microbial catalyst without a catalyst, so that the reaction rate of the reduction electrode is increased, Several efforts have been made to increase the current density both domestically and externally.

Recent researches at home and abroad have attempted to improve the output of microbial fuel cells by using heavy metal ions that do not use oxygen as an electron acceptor in a reductive electrode chamber and have a high reduction potential and reversibly and rapidly accept electrons . In the case of chromium microbial fuel cells (Cr (VI) -MFC), where the resistance was measured by electrochemical impedance spectroscopy (EIS) in order to measure the electron transfer rate of the oxidizing electrode and the reducing electrode, the reducing electrode was several thousand times slower And the output of the whole microbial cell is greatly restricted by the electron transfer rate of the reducing electrode (FIG. 1 and Table 1). The function of the oxygen molecule as an electron acceptor is even lower than that of Cr (VI). In the O ₂ -MFC, the limitation of the total cell output by the reduction electrode is larger than that of the Cr (VI) -MFC. Therefore, functional groups such as platinum and phosphate are added domestically to the reduction electrode, There was a steady effort to increase.

Electrochemical Impedance Spectroscopy (EIS) analysis of the individual electrodes of the MFC was performed at a reducing electrolyte containing 100 ppm Cr (VI) at pH 2 and open circuit voltage. The oxidized electrode coated with the biofilm and the oxidized electrolyte were an acetate solution of carbon brush electrode and phosphate buffer.

FIGS. 1A and 1B show the Bodegas, and FIG. 1C shows a schematic diagram of an equivalent circuit for one time constant model (OTCM) of the individual electrodes and two time constant models (TTCM) Show Nyquist City. In FIG. 1B, the phase angle in Bodegau's low frequency band is closer to -90 ° at the oxidation electrode than at the reduction electrode, indicating that there is a higher bilayer capacity (C _dl ) at the oxidation electrode than at the reduction electrode. This means that the oxidized electrode has a much higher active surface area due to charge accumulation than the reduced electrode. Interestingly, it has been found that the C _dl of the oxidized electrode is 3 orders of magnitude larger than that of the reducing electrode by the Nyquist plot (Fig. 1C and Table 1), again indicating that the biooxidized electrode has a much higher active surface area .

C _dl can be obtained as a derivative of the charge density with respect to the voltage at the electrode surface. This means that even under open-circuit potential conditions where no net current flows, large charge accumulation occurs at the oxidation electrode from the electron-releasing metabolizable material due to the large C _dl as compared to the reduction electrode. This may be due to the fact that there is actually negative charge transfer from the lowest unoccupied molecular orbital (LUMO) of the catalytic region to the oxidation electrode and that the catalytic region is attached to the microorganism. However, according to electrochemical measurements such as cyclic voltammograms performed in solutions near the biocatalytic oxidation electrode, no current was found from the mediocre at the solution side. It is therefore more likely that the mechanism by which the electron transport occurs by the catalyst bound to the outer membrane rather than by the mediator in the solution.

1A, the charge transfer resistance (R _ct ) of the carbon brush electrode is lower than that of the carbon nanotube electrode electrode by a factor of 2.5, which indicates that the rate of acetate oxidation at the oxidizing electrode is lower than that of the Cr Lt; RTI ID = 0.0 > VI). ≪ / RTI > The shape of the R _ct and phase angle of the whole cell is close to those of the reduction electrode (Fig. 1A and Fig. 1B), mainly because of the contribution from the reduction electrode. The fitting factors obtained by adapting the impedance to the equivalent circuit (FIG. 1C) are shown in Table 1. The ohmic resistance R _Ω was about 4.8 times lower than that in the oxidizing electrode chamber in the reducing electrode chamber due to the high solution conductivity of the oxidizing electrode chamber. The R _ct of the oxidized electrode was found to be 50.8 times lower than that of the reducing electrode of Nyquist.

Oxide electrode and the reduction electrode in the R _ct 'the sum of s was 1.94 x 10 ⁴ Ω to exactly match the former cell value (1.94 x 10 ⁴ Ω) which R _ct' indicates that the contribution from which most of the s of the reduction electrode (Table 1). However, the values from the sum of the reciprocal of the individual bilayer capacities for the C _dl and the series connection of the entire cell were 2.79 × 10 ^-5 F and 7.66 × 10 ^-5 F, respectively. The internal resistance (R _int ), defined as the sum of each contribution, was 1.94 x 10 ⁴ Ω for both the total cell and the individual contribution. On the other hand, the R _int obtained from the slope of the polarization curve in the kinetic region under the same conditions (100 ppm Cr (VI)) was 1.14 x 10 ² Ω (Table 1). This indicates that R _int by the EIS is higher by 2 orders of magnitude than the value obtained by Ohm's law. This shows that there is a big difference between the two methods. The latter method deviates much from the ohmic resistance method, so it can be seen that some of the charge transfer resistance can be included with the ohmic resistor. This fact suggests that the EIS results represent the true internal resistance of the MFC.

Therefore, in summary of the above-mentioned discussion of R _ct and C _dl , it is expected that the charge transfer will be about two orders of magnitude faster at the electrode than at the reduction electrode for the current system. (1) increase the concentration of Cr (VI), (2) increase the area of the reducing electrode, (3) decrease the activation energy for the reduction reaction, and .

First, according to the EIS analysis of the entire cell for different Cr (VI) concentrations, R _int decreases stepwise, but saturates at concentrations higher than 1000 ppm (FIG. 2). The peak current density (J _peak ) is inversely proportional to R _int and the magnitude of the peak current is mainly determined by the internal resistance under the charge transfer control process prior to the peak voltage. At voltages after the current peaks, the current is limited by mass transfer (diffusion in this case) (Fig. 2A). However, the increase of Cr (VI) from 1000 ppm to 2000 ppm did not significantly increase the extreme current. This can be explained by the oxidation reaction freeze. Second, increasing the reductive electrode area effect is not high because the power does not increase much. In this previous study, using a smaller area of the reducing electrode increased the power density compared to the larger area, but the total power was similar between the two. There will be a limit to power improvement by this factor.

Third, a large improvement in current density is expected to be achieved by the reduced electrode with catalyst until freezing by the oxidation electrode occurs. This results in decreasing R _ct . R _ct reduction is expected to increase with good catalysts that need to be developed even though there is a limit to the increase in the concentration. This development will result in an increase in maximum power density. In the previous study, the maximum power density of Cr (VI) -MFC was 1 / R _ct ^cell (slope 1.14 x 10 ⁵ Wm ^-2 Ω; fit R ² = 0.975), 1 / R _int ^{ce 11} (slope 1.14 x 10 ⁵ It is more interesting to know that a linear relationship can be predicted with Wm ^-2 Ω; R ² = 0.975) and 1 / R _slope (slope 4.52 × 10 ² Wm ^-2 Ω; R ² = 0.990). The value can also be predicted from a linear relationship such as peak current density (slope 0.768 W / A; R ² 0.982) and maximum current density (slope 0.774 W / A; R ² = 0.957) from the voltage versus current density curve.

When the high output power of the chromium microbial fuel cell as described above is applied to the redox flow microbial fuel cell and continuous operation is performed, the discharge material Cr ³⁺ is generated. Therefore, in order to obtain high continuous power, Cr ³⁺ should be electrochemically oxidized and converted into Cr ⁶⁺ , which is an electron absorbing material of the reducing electrode chamber of the microbial fuel cell, and continuously regenerated and supplied. For this regeneration, an oxidizing electrode chamber in which chromium is oxidized, a reductive electrode chamber in which a reduction reaction is to be made in a pair with the electrode, and an electrochemical electrolytic cell using a separation membrane so as not to mix the solution between the electrode and the electrode chamber should be used. Here, external power must be supplied to cause the reaction to occur, and this power uses photovoltaic power, which is renewable energy. Of course, it is possible to use electricity at night or at night, such as thermal power generation, small hydro power generation, and nuclear power generation. However, FIG. 2 shows a detailed energy circulation system that links solar power generation. FIG. 2 is a side view (A) of a solar cell chromium microbial fuel cell, and FIG. 2 (B) shows a cross-sectional view of a generator storage device. Note the reservoir storing the electron absorber produced using solar power. A practical example of the device shows how to independently control the microbial oxidation electrode in the bathtub. 3 is a conceptual diagram of a continuous and batch type heavy metal microbial fuel cell in which a regenerative electron absorber electrolytic cell of photovoltaic power generation is connected. 4 is a conceptual diagram of a continuous and batch device having a composite electrode for high energy storage and production. The design of an energy storage and regeneration system that links such a microbial fuel cell has not been disclosed until now.

It is an object of the present invention to provide a lead-acid battery capable of storing electricity for a specific period of time, To provide a method of storing and reusing solar energy in combination with solar energy. It also purifies organic wastewater in large-scale power generation systems as well as small-scale households, while providing a paradigm for practical energy production, storage and reuse.

In order to achieve the above object, the present invention provides a charge absorber of a reducing electrode of a microbial fuel cell by oxidizing heavy metals such as chromium by using solar photovoltaic power. If necessary, it is circulated to a reduction electrode chamber having a reduction electrode of a material such as carbon, titanium, or stainless steel of a microbial fuel cell, and an oxidizing electrode of a microbial fuel cell is provided with a graphite brush as a carbon material having as large a specific surface area as possible for growth of anaerobic microorganisms , Graphite felt, carbon foam, porous nano carbon film, and the organic electrode wastewater is circulated in the electrode electrode room to supply organic matter necessary for the metabolism of microorganisms, thereby achieving power generation simultaneously with removal of organic matter Device.

An example of a solution is to use the Cr (VI) as the electron absorber with a high reduction potential to reuse the stored electrical energy, to achieve 23 Wm ^-2 at an operating maximum voltage of 0.95 V, a current of 38 Am ^-2 (3.8 mA cm ^-2 ), But the formation of Cr (III) occurs in the reductive electrode chamber of this cell, and it is necessary to oxidize it and regenerate it as Cr (VI). This is due to the fact that the oxidation of Cr (III) after the discharge of Cr (VI) -MFC, which is a battery system using the storage material of PV system, And an electrode chamber containing Cr (III) as an oxidizing electrode and an electrode chamber containing no Cr (III) as a reducing electrode. By using the photovoltaic cells, the required voltage and power can be regenerated and stored in the Cr (VI) during the daytime power generation and supplied to the reductive electrode chamber of Cr (VI) -MFC during the power generation to enable continuous development of the connected microbial fuel cell. Do.

In the present invention, Cr (III), which is a reducing material of HPCMFC, is oxidized to produce Cr (VI), which can be used for a long time, which is supported by high reduction potential such as Cr (VI) and excellent reversibility. ). It is desirable to use solar energy, which is sustainable renewable energy, as a link system. The raw material of the electron absorber such as Cr (VI) is preferably obtained from the waste water from the viewpoint of solving environmental problems. In terms of wastewater treatment, heavy metals are often generated by mixing. In this case, if heavy metal ions having a high reduction potential are present and the waste water mixed with heavy metal ions having a low reduction potential is directly passed through the HRT electrode in the reduction electrode chamber, heavy metal ions having a high reduction potential once are precipitated in the reducing electrode Or it is reduced to a low oxidation state and it is possible to generate voltage and power at this time.

In the present invention, a design that changed the two-chamber cell design was used. The reduction electrode was passed through the right reducing electrode chamber while maintaining the proper hydraulic retention time (HRT) controlled, and the anaerobic bacteria It provides a system that obtains high power with a battery design that uses an organic material as fuel while maintaining the proper HRT of an organic material as an oxidation electrode.

The heavy metals returned from the reductive electrode chamber of the microbial fuel cell to the heavy metal oxidizing vessel are returned to a high oxidation state through the oxidation reaction using the photovoltaic power and the voltage to prepare for the reuse. However, it may be necessary to keep the pH constant by rotating the electrolyte with a continuous flow. This allows the pH to be kept constant by taking advantage of the design of the flow-type redox microbial fuel cell.

In the present invention, the organic matters required for the microorganisms are supplied as a continuous stream of the organic wastewater in the practical microbial fuel cell when the organic organic wastewater, which is an infinite resource, is applied. In the final stage, the organic matter does not significantly affect the environment. It would be ideal if it could be the final discharge with continuous flow to the level. This can be accomplished by allowing the wastewater to pass through the microbial oxidation electrode chamber in a stepwise fashion, thereby prolonging the residence time. Therefore, compared with the conventional storage system capable of only charging and discharging, there is an advantage that the conventional storage system of electricity production together with the treatment of organic wastewater is not available. In addition, since the conventional lead storage system can be charged only for a limited time during the daytime by the photovoltaic power generation system, the microbial battery energy recovery system connected with the heavy metal recovery system is likely to be developed as a highly promising system. Heavy metal wastewater contaminated with complex heavy metal ions can also be used. This is an interesting device that synergizes with two or more technologies. As microbial fuel cells are metabolized and generate electrons, only the reducing materials that absorb the electrons and the electrons are continuously supplied. It can be developed into an electric production system with environmentally friendly practicality that can generate electricity and supply electricity even at night when sunlight can not be achieved and remove organic matter at the same time.

The microbial fuel cell seems to have a low competitiveness due to the lack of power production, but the present invention is expected to break through this. This high-performance flow-type microorganism continuous fuel cell is the first in the world, not only in Japan, but also as a fuel cell, one approach to commercialization. However, in order to maintain the activity of the oxidation electrode of the high-performance flow MFC in the present invention, it is desired that the pH of the oxidation electrode chamber is adjusted to 7, which is suitable for living anaerobic microorganisms. The hexavalent chromium, which is an electronic absorber, is advantageously reacted with a pH of 2 with a sulfuric acid buffer.

According to the present invention, even in the case of Cr (VI) -MFC, which has a strong reduction energy level of Cr (VI) as an electron acceptor and electron transfer rate, The peak power of 23 Wm ^-2 , the maximum current of 38 Am ^-2 and the maximum voltage of 0.61 V are the basic factors of maximum power, As a matter of fact, the selection of heavy metals such as Co ³⁺ , Ce ⁴⁺ , S ₂ O ₈ ^2- , Mn ³⁺ , MnO ₂ , NiO ₂ and VO ₂ ⁺ In the case of Cr (VI) -MFC, for example, the discharge material in the reductive electrode chamber is Cr (III), which is continuously supplied and oxidized by hexavalent chromium so that the battery can be used as an almost permanent storage system of solar power generation, Waste water is treated. This new high performance power generation system and solar power generation storage system linkage apparatus according to the present invention provide a paradigm of use of renewable energy linkage because there is no example of domestic or foreign invention invention.

Microbial fuel cells have not been developed for commercialization at home and abroad because a system for producing sufficient power and current has not been developed. By optimizing the reducing electrode of the heavy metal ion mixed MFC for industrial wastewater treatment such as the continuous flow type Cr (VI) -MFC of the present invention, the flow type redox microorganism fuel cell is more economical than existing devices such as flow type vanadium redox batteries There was a device available.

Most of the storage systems for generating electricity by solar power generation are those that charge electricity to rechargeable batteries such as lead-acid batteries for the time of solar power generation and supply electric power to the load, so that charging is performed efficiently and economically As the development of electric energy storage batteries is critical, it may be necessary to replace them with continuous-flow microbial fuel cells. The present invention has been developed as a model of a storage system capable of linking photovoltaic power generation systems of 150 W and 500 W, which are commercial solar cells.

As shown in FIG. 2, in the present invention, Cr (VI) -MFC generates Cr (III) as a discharge material. In order to regenerate Cr (III) By re-supplying Cr (VI) to the reductive electrode chamber of MFC, it is possible to regenerate electric energy accumulated in photovoltaic power generation by flow-type photocatalytic cyclic microbial fuel cell. Thus, by combining the two systems, energy can be used in a mass-eco-friendly manner. The development of such convergence has not been developed in the domestic as well as internationally, so it has the effect of raising it to a competitive stage in the international energy.

In the present invention, the construction of a new microbial fuel cell using the existing surplus solar power is performed by using an anaerobic sludge of an anaerobic digestion tank of a wastewater treatment plant and inoculating an oxidizing electrode of a material such as a carbon electrode and using a carbon, titanium, or stainless steel Which is very cheap and has a maintenance cost effect. This is in line with domestic efforts to increase the share of total energy supply and demand for alternative energy use in Korea by pursuing the practicality of alternative energy linked with the storage function of PV system in the field of microbial fuel cells.

In the present invention, it is possible to mass-produce hydrogen and transfer it to a necessary place in the photovoltaic power generation, but the limit of transportation storage and the use of a high-pressure vessel are disadvantageous. However, oxidized Cr (VI) The cost of transportation is reduced, and it is possible to supply and receive high-density energy rather than transporting gas. Cr (VI) electron acceptors, which require regeneration in the proposed flow-type redox microbial fuel cell, are available with alternate electron acceptors such as vanadium or Co (III), which is flexible in material use. Since the metabolites of anaerobic microorganisms are organic matter, they can contribute greatly to the energy conversion of domestic food waste, which is environmentally friendly.

FIG. 1 shows an electrochemical impedance spectroscopy of the MFC: (A) logarithm of modulus of impedance lZl vs. logarithm of frequency, (B) phase angle (degree), etc. logarithm of frequency f, and (C) Nyquist plots. Catholyte; 100 ppm HClO ₄ ^- at pH 2.
2 is a side view of a solar cell chromium microbial fuel cell.
3 is a cross-sectional view of the microbial fuel cell generator.
4 reproduces an electronic absorber using solar power generation power. Here, a conceptual view of a continuous and batch heavy metal microbial fuel cell connected with an electrolysis tank containing an electron absorber.
5 is a conceptual diagram of continuous and batch devices having composite electrodes for high energy storage and production.
Figure 6 ^{_{Effects of initial concentration of HCrO 4 -}} at pH 2 on (A) peak currents and (B) maximum power densities: the anolyte was 1.0 g (12.2 mM) sodium acetate with phosphate buffer at pH 7.
FIG. 7 illustrates Peak current densities and maximum power densities vs.. Cr (VI) concentrations.
Figure 8 shows the discharging curves: (A) Buffer A; 0.1 MH ₃ BO ₃ , 0.2 M NaCl, (B) Buffer B; _{0.1 M NaHSO 4, 0.2 M Na} 2 SO 4, (C) Buffer C; _{0.1 M NaHSO 4, 0.2 M NaCl} , and (D) Buffer D; _{0.1 M NaHSO 4, 0.1 M Na} 2 SO 4. The Cr (VI) concentration was 500 ppm at pH 2. The load resistor was 1000 Ohms.

Hereinafter, the present invention will be described in more detail by way of examples. In the following examples, the continuous-flow type microbial fuel cell using the heavy metal contained in the wastewater is combined with the photovoltaic power generation and the storage heavy metal oxidation process, and the recovery of the power using the heavy metal microbial fuel cell And the scope of the present invention is not limited to these examples.

Example 1; Photovoltaic-linked microbial fuel cell

In the present invention, the microbial fuel cell contains a carbon electrode together with Cr (VI) (1.33 V vs. NHE), Co (III) (1.82 V vs. NHE) or VO ₂ ⁺ (0.9994 V vs. NHE) electron acceptor (VI), Co (III) or VO ₂ ⁺ having a high reduction potential by adding a reducing electrolyte. When the reduction electrolyte is improved by using sulfur hexafluoroborate (Cr (VI)) solution, development of a method of maintaining a low pH change and high conductivity is the first in the world to be prominent in creativity and conductivity.

FIG. 2 to FIG. 4 illustrate the pattern of regenerating Cr (VI) using photovoltaic power and adjusting the amount of discharge material by HRT to make Cr (VI) It shows high capacity according to battery connection. By controlling the amount of reaction by the amount of microorganism by allowing organic wastewater to pass through the microorganism catalyst chamber, the level of organic matter treatment can be creatively controlled. This creative system is used as a storage system for solar power generation. High-performance flow-type microbial fuel cells are also used as a power source to remove other heavy metals that are difficult to remove from wastewater.

Example 2: Improvement of the power of microbial fuel cell using hexavalent chrome electron absorber

5A and 5B show the current density vs. voltage curve (work curve) and the maximum power density curve according to the change of the initial concentration of HCrO ₄ ^- . Electrochemical factors are summarized in Table 2. PCD and MPD increased as the initial concentration of HCrO ₄ ^- increased, maximized, and then increased again (Fig. 5). The reason for the initial maximization of these factors is unknown; However, it is possible that a resistive film for the current of the Cr ₂ O ₃ film is formed on the electrode surface in the range of low HCrO ₄ ^- . A SEM / EDS micrograph confirmed the presence of this membrane.

As shown in Table 2, it can be seen that J _max increases with increasing Cr (VI) considering the electrochemical factor. However, the open circuit voltage (V _o ) increases from 0 ppm to 800 ppm in the Cr (VI) concentration increase range and J _max is almost constant from 800 ppm to 2000 ppm. In this high concentration range, V _o appears to be affected by the oxidation electrode reaction and was due to the polarization fixation of the oxidation electrode concentration of the MFC performance. The same trends were observed for J _peak and P _max (FIG. 6). V _max and FF did not allow correlation with the concentration increasing effect due to the maximum power point. R (slope) decreased with increasing Cr (VI) concentration and decreased with increasing Cr (VI) concentration. The maximum maximum power density in a 2000 ppm Cr (VI) reducing electrolyte was found to be 10.22 W / m ² with a fill factor (FF) of 0.668.

Data are presented in Table 2 to compare the recent P _max values achieved by several studies. From this table, Li et al. (2008) showed that the graphite redox electrode showed the highest P _max under the same conditions of a 200-mL reducing electrolyte of 200 ppm Cr (VI). The _Pmax value of recent results was 3.4 times higher. However, the ratio of the solution to the area of the reducing electrode applied recently was 3.3 times larger than that of Li et al (0.667 m ³ / m ² vs. 0.200 m ³ / m ² ). If we consider that a larger ratio produces a larger P _max than a smaller ratio at the ratio of the straight line, we can see that the P _max of the recent study is similar to the published value. When the concentration of Cr (VI) to increase from 0 ppm to 2000 ppm P _max is increased from 0 to Wm ^-2 10.22 Wm ^-2. From 1000 ppm to 2000 ppm, P _max hardly changed due to oxidized electron acceptor concentration for voltage freezing. This supports direct electron transfer (DET) to the oxidation electrode in the outer membrane of the bacteria via electron-hole pair formation and recombination in the catalytic region.

Example 3: Effect of Addition of Sulfuric Acid Buffer to Electron Absorber Reducing Solution

It is preferable to construct a reducing electrolyte of Cr (VI) -MFC that can operate well for a long time. In this optimized Cr (VI) -MFC, Cr (VI) can be removed and used as an electronic absorber. Four different types of buffer were tested using discharge experiments (Figure 7).

The discharge voltage of Cr (VI) -MFC with boric acid buffer gradually decreased until 20 hours from the beginning, dropped rapidly and dropped slowly again until 25 hours. However, the remaining buffer solution based on sulfate ion allowed a very slow decrease in the discharge voltage of Cr (VI) -MFC. 0.1 M NaHSO ₄ and 7B with the buffer solution 0.2 M Na ₂ SO ₄ was maintained at the highest voltage, particularly during long periods of time. Figure 7B is the reason that the buffer voltage is higher concentration of the NaHSO higher than the other hand, the Na ₂ SO ₄ concentration in Figure 7C and Figure 7D ₄ is constant. This means that the buffering capacity based on 0.1 M NaHSO ₄ and 0.2 M Na ₂ SO ₄ has a lower pH and conductivity change in the reducing electrolyte of Cr (VI) -MFC even after 48 h of reaction time.

The pH of buffer B rose only 16% of the initial value while the other buffer showed a rise of 98% -31%. Conductivity of buffer B showed a 13% reduction compared to 42% -21% reduction of other buffers. Therefore, according to the experimental results, it can be seen that Buffer B made of 0.1 M NaHSO ₄ and 0.2 M Na ₂ SO ₄ forms the most stable buffer for Cr (VI) -MFC in the experimental range within the four syntheses. Cr (VI) -MFC can be used as a redox flow MFC with long-term stability under the condition that Cr (VI) in the reductive electrode chamber is continuously rotated and the supply of organic matter is continued to sustain energy storage and production. When Cr (VI) is reduced, it is necessary to oxidize it to Cr (VI) in order to generate Cr (III) and to circulate it. This means that the power generated during the day can be converted into Cr (VI) by using solar power, which is an infinite resource of pollution, and can be continuously rotated and stored as a microbial fuel cell, and it can act as a good solar power storage system . It also shows that solar power generation is economically feasible for important solar PV power storage systems, which are only possible during solar PV. Similar MFCs such as Co (III) -MFC and Ag (I) -MFC can be modified for the same purpose.

Claims (10)

A microbial fuel cell (MFC) having an oxidation electrode, a reduction electrode, and a separation membrane between both electrode chambers is coated with a carbon brush or a carbon graphite electrode using anaerobic microorganisms from anaerobic sludge, and has a high reduction potential from heavy metal- It is possible to obtain a heavy metal or an inorganic electron absorber which has a fast moving reaction and constitute a reduction electrode together with a material electrode such as carbon cloth, titanium or stainless steel to constitute a microbial fuel cell to obtain electricity by discharging electricity. A method for regenerating electric power by oxidizing a discharge material in a reductive electrode chamber of a fuel cell, returning it to a microbial fuel cell continuously, and discharging the recovered electron-absorbing material. The heavy metal used as an electron absorber according to claim 1, wherein the heavy metal has a high reducing potential such as Cr ⁶⁺ , Co ³⁺ , Ce ⁴⁺ , S ₂ O ₈ ^2- , Mn ³⁺ , MnO ₂ , NiO ₂ or VO ₂ ⁺ Lt; RTI ID = 0.0 > and / or < / RTI > heavy metals. The method according to claim 1, wherein the anaerobic microorganism is at least one selected from among electron-emitting microorganisms not limited to these species: Alpha-proteobacteria, Beta-proteobacteria, Delta-proteobacteria, Clostridia, Shewanella oneidensis MR-1 , Shewanella oneidenisis DSP-10, Shewanella putrefaciens SR-21, IR-1, MR-1, Geobacter sulfurreducens, Geobacter sulfurreducens KN400, Ochrobactrum anthropi YZ-1, Brevibacillus sp. PTHI, E. coli K12 HB101, Aeromonas hydorphila, Corynebacterium sp. MFC03, Leptothrix discophora SP-6, Bacillus licheniformis, Bacillus thermoglucosidasius, Spirulina platenisis, Bacillus subtilis, Enterococcus gallinarum, Acetobacter aceti, Gluconobacter roseus. The method of claim 1, wherein the oxidizing electrode of the microbial fuel cell is an electrode material in which microorganisms such as carbon felt and carbon brush can grow, the reducing electrode is a carbon paper, carbon cloth, graphite, titanium, stainless steel, The electrode material that provides rapid delivery, the separation membrane between the electrode chambers constitutes a microbial fuel cell with a membrane that permits the selective or non-selective transfer of ions without mixing the anion exchange membrane, the cation exchange membrane, the anion cation composite membrane and other solutions ≪ / RTI > In a microbial fuel cell (MFC) having an oxidizing electrode, a reducing electrode and a separator between both electrode chambers, an anaerobic microorganism is used to make heavy metals, noble metals or minerals having a high reduction potential as an electron absorber, and the separator has a cation exchange membrane, A method of producing electricity using a membrane suitable for a microbial fuel cell such as an anion composite membrane or a filter membrane. Heavy metals and the like used for the electron absorption body according to 5, wherein the Cr ^6+, method of _{^{Co 3+, VO 2 +, Mn}} 3+ , etc. characterized in that the reduction potential is high, heavy metals, precious metals, in the mineral. The method for regenerating the discharge material of claim 5, wherein the excess power of the photovoltaic power generation system is regenerated through the oxidation of the discharge material transferred from the reduction chamber of the microbial fuel cell to the reduction electrode chamber of the microbial fuel cell. The electron absorber reproducing apparatus according to claim 7 is an electrolytic cell manufactured by providing an anode chamber, a cathode chamber, and a separator between the both electrode chambers, wherein the cathode chamber is provided with a graphite electrode and a discharge material A cathode electrode chamber using a solid electrode suitable for a negative electrode such as graphite, titanium or stainless steel for the anode chamber and the cathode chamber protected by the membrane of claim 5 or a method for accumulating an electron absorber in an electrolytic cell composed of a cathode using a microbial catalyst . The photovoltaic power generation system is composed of an electronic energy recovery system and a microbial fuel cell power generation system in the existing ones, and the organic carbon material necessary for the microbial fuel cell is treated with food waste A method of generating and using independent energy. The operation of the present invention is both batch or continuous, and the power used for regenerating the electron absorber can be used at night or at an available power of a thermal power plant, a nuclear power plant, a hydroelectric power plant,

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