KR20230057856A - Electrochemical bioreactor for Hydrogen or Polyhydroxybutyrate production using carbon dioxide conversion and method for processing using thereof - Google Patents

Abstract

The present invention relates to a bioelectrochemical reactor for producing hydrogen or polyhydroxybutyrate through carbon dioxide conversion and a processing method using the same, and more specifically, to a bioelectrochemical reactor, in which electrons required for a bioconversion reaction, that is, the reducing power, is sufficiently supplied to reduce carbon dioxide, thereby generating useful substances such as hydrogen or polyhydroxybutyrate on the electrode surface and being capable of cultivating microorganisms that catalyze the useful substances at the same time, and a processing method using the same.

Description

Electrochemical bioreactor for Hydrogen or Polyhydroxybutyrate production using carbon dioxide conversion and method for processing using it}

The present invention relates to a bioelectrochemical reactor for producing hydrogen or polyhydroxybutyrate through carbon dioxide conversion and a process method using the same. It relates to a bioelectrochemical reactor capable of producing useful substances such as hydrogen or polyhydroxybutyrate on a surface and simultaneously culturing microorganisms that catalyze the same, and a process method using the same.

In preparation for a hydrogen society, such as the commercialization of hydrogen fuel cell vehicles and eco-friendly power generation systems through the establishment of new renewable energy supply policies and hydrogen economy roadmaps, the need for sustainable green hydrogen generation technology is rapidly emerging. Currently, it is known that hydrogen generation by reforming reaction of natural gas or fossil fuel is the most price-competitive, but carbon neutral or carbon negative eco-friendly hydrogen production technology that does not emit carbon dioxide due to problems such as carbon dioxide emission due to the use of fossil fuel. The need for is rapidly emerging. In particular, the chemical catalyst process has been pointed out as a problem of catalyst poisoning and process performance degradation due to carbon deposition. For the realization of the hydrogen economy roadmap, hydrogen generation methods such as fossil fuel reforming, refinement of petrochemical processes, and electrolysis using renewable energy are being considered, but at the same time, various technologies are being developed to generate hydrogen economically and stably. need.

Existing water electrolysis hydrogen generation is a method of generating hydrogen at the cathode by applying a voltage of about 2V or higher to the anode and cathode, and has the advantage of producing high-purity hydrogen. The use of and durability of the system are pointed out as problems, and the price of hydrogen generation considering the amount of power input is reported to be about twice that of reformed hydrogen.

Anode: 2H ₂ O → 4H ⁺ + 4e ^- + O ₂

Cathode: 4H ⁺ + 4e ^- → 2H ₂

Although platinum and non-platinum catalysts are used for water electrolysis, the durability and stability of the system are low due to poisoning and deterioration of catalyst activity, and it is difficult to further lower the price of hydrogen generation through water electrolysis. On the other hand, the economic and industrial necessity for greenhouse gas reduction has recently been rapidly increasing, and the axis of technology development and commercialization has been developed from a simple reduction technology that captures and stores carbon dioxide to a high value-added process that uses carbon dioxide as a raw material and converts it into useful chemicals. is being moved

In order to change carbon dioxide, the most oxidized form of carbon, into a useful material, reducing power in the form of electrons must be supplied from the outside. There is (Patent Document 002).

The photoautotrophic bioelectrochemical reactor newly proposed in the present invention can produce useful substances such as hydrogen or polyhydroxybutyrate from carbon dioxide and at the same time develop a carbon negative process that cultivates microorganisms that catalyze this reaction, thereby reforming existing fossil fuels. It is more effective in realizing a low-carbon society and reducing greenhouse gases than water electrolysis hydrogen generation process.

Anode: 2H ₂ O → 4H ⁺ + 4e ^- + O ₂

Cathode: 4H ⁺ + 4e ^- + CO ₂ → 2H ₂ + Microbial catalyst, polyhydroxybutyrate, etc.

The bioconversion process using microorganisms as a catalyst is highly reactive to low-concentration carbon dioxide, so it can be applied to industrial exhaust gases such as steel and power plants containing low-concentration carbon dioxide or impurities that are difficult to apply in existing chemical catalyst processes. Compared to chemical processes operated at high temperatures and high pressures, biological processes can be operated at room temperature and normal pressure, so operation costs can be reduced. In addition, since the microbial catalyst is a catalyst capable of self-replication, the stability and economy of the process are high.

In order to supplement the problems of hydrogen generation through reforming or water electrolysis currently commercialized and to develop a process method capable of reducing and converting hydrogen and carbon dioxide at the same time, the present inventors are trying to achieve hydrogen and polyhydroxybutyrate production through carbon dioxide conversion. A photoautotrophic bioelectrochemical reactor capable of

Photoautotrophic hydrogen production of Rhodobacter sphaeroides in a microbial electrosynthesis cell. Bioresource Technology. 320 (2021) 124333

Republic of Korea Patent Registration No. 10-2193010

An object of the present invention is to produce useful substances such as hydrogen or polyhydroxybutyrate on the electrode surface by reducing carbon dioxide by sufficiently supplying electrons necessary for the bioconversion reaction, that is, reducing power, and at the same time, microorganisms synthesizing these useful substances on the electrode surface. It is to provide a bioelectrochemical reactor that can be cultured in and a process method using the same.

Another object of the present invention is to provide a bioelectrochemical reactor and a process method using the same for converting carbon dioxide, one of greenhouse gases, into high value-added compounds rather than simply capturing or storing carbon dioxide through a carbon dioxide conversion process.

The technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description of the present invention.

In order to achieve the above object, the present invention provides a bioelectrochemical reactor for generating hydrogen or polyhydroxybutyrate through carbon dioxide conversion and a process method using the same.

The present invention includes an oxidation chamber in which an oxidation electrode is located and electrons and hydrogen ions are generated through electrolysis;

a reduction chamber in which a reduction electrode in which microorganisms are inoculated is located, and carbon dioxide gas is continuously supplied to apply a reduction potential to the reduction electrode so that photoreactive microorganisms convert carbon dioxide;

an ion exchange membrane positioned between the oxidation chamber and the reduction chamber to transfer hydrogen ions generated in the oxidation chamber to the reduction chamber; and

The oxidation electrode and the reduction electrode are connected through an external circuit to supply power to the oxidation chamber and the reduction chamber, and an electricity supply device for applying a reduction potential or reduction current to the reduction electrode; includes,

The oxidation chamber and the reduction chamber are

The inert gas and carbon dioxide gas are continuously supplied to maintain absolute anaerobic conditions,

The inert gas is nitrogen or argon gas,

The carbon dioxide gas is a bioelectrochemical reactor that is pure carbon dioxide or a mixed gas of carbon dioxide and an inert gas.

In the present invention, the oxidation chamber or reduction chamber

a gas supply unit for supplying the inert gas or carbon dioxide gas into the oxidation chamber and the reduction chamber;

a gas inlet for injecting the gas supplied by the gas supply unit into the oxidation chamber and the reduction chamber;

a micro-bubble diffuser for injecting the supplied gas into the liquid phase of the reactor in a bubble state;

a gas outlet for discharging the gas supplied through the gas inlet or gas generated by electrolysis; and

An oxygen removal trap for removing trace amounts of oxygen present in the inert gas may be additionally included.

In the present invention, the cathode or anode includes a device for supplying light such as an LED lamp or a fluorescent lamp.

In the present invention, the microorganism inoculated on the cathode is of the genus Rhodobacter or Rhodopseudomonas,

The microorganism generates hydrogen or polyhydroxybutyrate by receiving electrons through the cathode.

In the present invention, the microorganism is an electrochemically active strain capable of photosynthesis under anaerobic conditions.

In the present invention, the anode or cathode is formed of a carbon material, a metal material, or a polymer material in the form of a carbon felt, brush, granule, or carbon rod. do.

In the present invention, the ion exchange membrane is a hydrogen ion exchange membrane, a cation exchange membrane, an anion exchange membrane, a bipolar membrane, or a ceramic separator.

In the present invention, the bioelectrochemical reactor is a photoautotrophic bioelectrochemical reactor.

the present invention

(1) inoculating microorganisms on the cathode of the bioelectrochemical reactor;

(2) continuously supplying the inert gas or carbon dioxide gas to the oxidation chamber and the reduction chamber of the bioelectrochemical reactor to maintain absolutely anaerobic conditions;

(3) adding electricity to the bioelectrochemical reactor;

(4) attaching microorganisms to the cathode of the bioelectrochemical reactor;

(5) confirming that the microorganisms are colored red while attaching to the electrode surface; and

(6) generating hydrogen or polyhydroxybutyrate by supplying light to the bioelectrochemical reactor and performing carbon dioxide conversion;

A carbon dioxide conversion method using a bioelectrochemical reactor comprising a.

All matters mentioned in the bioelectrochemical reactor and the method for converting carbon dioxide using the same are equally applied unless contradictory.

The bioelectrochemical reactor and the process method using the same of the present invention is a microorganism capable of producing useful substances such as hydrogen or polyhydroxybutyrate on the surface of an electrode by reducing carbon dioxide by sufficiently supplying electrons necessary for a bioconversion reaction, that is, reducing power. It can provide a composite effect.

In addition, the bioelectrochemical reactor of the present invention increases the number of microbial catalysts that can convert carbon dioxide to produce hydrogen or polyhydroxybutyrate, and attaches microorganisms that convert carbon dioxide to the electrode surface to improve electron transfer efficiency and target products. can increase the production yield of

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a schematic diagram showing a bioelectrochemical reactor of the present invention.
2 is a schematic diagram showing that microbial cells attached to an electrode generate H ₂ or polyhydroxybutyrate (PHB) when glutamate (L-glutamic acid) or ammonium chloride (NH ₄ Cl) is added as a nitrogen source to a reducing solution.
FIG. 3 is a diagram showing the current consumption (a) of the system according to the potential applied to the reduction electrode of the bioelectrochemical reactor and the resulting value of the average hydrogen production rate (b) accordingly.
Figure 4 is -0.9V applied to the reduction electrode of the bioelectrochemical reactor, and hydrogen production (A), carbon dioxide consumption (B) and hydrogen production under light-free conditions (C) under light incubation conditions of 6000 lux light intensity It is a drawing comparing the result values.
5 is a diagram showing electrons consumed in the entire system and electrons recovered as hydrogen among them when ammonium chloride (NH ₄ Cl) or glutamate is added as a nitrogen source to the reducing solution.
Figure 6 shows the results of changes in the amount of planktonic cell density and attached cells to the electrode over time when ammonium chloride (NH ₄ Cl) or glutamate is added to the reducing solution as a nitrogen source. it is a drawing
7 is a bioelectrochemical reactor (A) when -0.9V vs Ag / AgCl voltage was applied to the culture solution containing ammonium chloride (NH ₄ Cl), (B) -0.9V vs Ag / AgCl to the culture solution containing glutamate When voltage is applied, and (C) when operating in an open circuit without supplying power from an external electric supply device or potentiometer, microbes are attached to the electrode during inoculation of microorganisms and show different growth patterns.
8 is a view showing comparison result values of polyhydroxybutyrate (PHB) production and biomass sugar content according to the gas composition supplied to the bioelectrochemical reactor, ammonium chloride (NH ₄ Cl) and glutamate.
9 is a view showing the attachment of microorganisms on the electrode surface.

The terms used in this specification have been selected from general terms that are currently widely used as much as possible while considering the functions in the present invention, but these may vary depending on the intention of a person skilled in the art, precedent, or the emergence of new technologies. In addition, in a specific case, there is also a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the invention. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, not simply the name of the term.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this application, it should not be interpreted in an ideal or excessively formal meaning. don't

Bioelectrochemical reactor for production of hydrogen or polyhydroxybutyrate through carbon dioxide conversion

1 is a schematic diagram showing a bioelectrochemical reactor of the present invention.

The present invention provides a bioelectrochemical reactor that produces hydrogen or polyhydroxybutyrate through conversion of carbon dioxide by supplying electrons necessary for a bioconversion reaction.

More specifically, the bioelectrochemical reactor of the present invention includes an oxidation chamber in which an oxidation electrode is located and electrons and hydrogen ions are generated through electrolysis; a reduction chamber in which a reduction electrode in which microorganisms are inoculated is located, and carbon dioxide gas is continuously supplied to apply a reduction potential to the reduction electrode so that photoreactive microorganisms convert carbon dioxide; an ion exchange membrane positioned between the oxidation chamber and the reduction chamber to transfer hydrogen ions generated in the oxidation chamber to the reduction chamber; and an electric supply device connected through an external circuit of the oxidation electrode and the reduction electrode to supply power to the oxidation chamber and the reduction chamber and to apply a reduction potential or reduction current to the reduction electrode.

More specifically, the oxidation chamber and the reduction chamber are maintained under absolute anaerobic conditions by continuously supplying inert gas and carbon dioxide gas, respectively, the inert gas is nitrogen or argon gas, and the carbon dioxide gas is pure carbon dioxide or a combination of carbon dioxide and inert gas. It can be a mixed gas.

As used herein, the term “photoautotrophic bioelectrochemical system” refers to a microbial catalyst that biologically converts CO ₂ through electron transfer between a specific photosynthetic microorganism having electrochemical activity and an electrode to which a potential is applied. It means a reactor capable of producing useful chemicals simultaneously with the growth of the population.

As used herein, the term "absolute anaerobic" means an environmental condition in which the oxygen concentration is 5 ppm or less.

In the present invention, the oxidation chamber electrolyzes the electrolyte to produce electrons and positive ions (H ⁺ ).

In the present invention, the anode and cathode are made of a carbon material such as a carbon felt, a carbon brush or carbon granule, a carbon rod, a metal material, or a polymer material. can be configured.

In the present invention, the reduction electrode is made of carbon granule, carbon felt, carbon brush, carbon rod, indium tin oxide, and titanium mesh, and connects them to an external power source. can be formed from copper or titanium wire.

The carbon material, metal material, or polymer material may have an electrical conductivity of 2×10 ⁵ to 3×10 ⁵ (S/m).

The term "pure microorganism" used in the present invention means a single microorganism, and "complex microorganism" means a mixed microorganism of two or more species.

In the present invention, the reduction chamber may include a reference electrode, preferably an Ag/AgCl reference electrode, but is not limited thereto. Also, the reference electrode may be located near the reduction electrode.

In the present invention, the oxidation chamber or reduction chamber includes a gas supply unit for supplying the inert gas or carbon dioxide gas into the oxidation chamber and the reduction chamber; a gas inlet for injecting the gas supplied by the gas supply unit into the oxidation chamber and the reduction chamber; a micro-bubble diffuser for injecting the supplied gas into the liquid phase of the reactor in a bubble state; a gas outlet for discharging the gas supplied through the gas inlet or gas generated by electrolysis; and an oxygen removal trap for removing trace amounts of oxygen present in the inert gas.

In the present invention, the gas supply unit supplies carbon dioxide so that the oxygen concentration can be maintained at 5 ppm or less, so that the inside of the reduction chamber can be maintained under absolutely anaerobic conditions.

In the present invention, the gas outlet is for discharging gas generated by electrolyte electrolysis in the oxidation chamber, and preferably, the location of the gas outlet can be appropriately adjusted according to the type of reactor.

In the present invention, the external electricity supply device or potentiometer is connected to the oxidation electrode, the reduction electrode, and the reference electrode through a circuit to supply power to the oxidation electrode and the reduction electrode, thereby generating a specific potential at the reduction electrode. can be authorized.

In the present invention, the external electricity supply device or potentiometer may move electrons generated at the anode to the cathode through an external circuit.

In the present invention, a reduction electrode that can be formed of carbon felt, carbon brush, carbon granule, carbon rod, indium tin oxide, titanium mesh carbon material, metal material, or polymer material may be located inside the reduction chamber, Preferably, the reduction electrode may be made of a carbon material having a large surface area and excellent electrical conductivity. When the reduction electrode is made of a carbon material, effects of current and applied voltage may be maximized.

In the present invention, microorganisms may be inoculated into the reduction chamber, preferably, the microorganisms to be inoculated may be pure cultures or mixed microorganisms, and more preferably, the microorganisms to be inoculated may be It may belong to the genus Rhodobacter or Rhodopseudomonas, or it may be an electrochemically active strain capable of photosynthesis under anaerobic conditions, and the microorganism receives electrons through the reducing electrode to produce hydrogen or polyhydroxybutyrate can do.

The size of the cathode may be in the range of 20 to 40 cm 2 , preferably in the range of 25 to 30 cm 2 . In addition, the thickness of the cathode may be in the range of 0.20 to 0.50 cm, preferably in the range of 0.25 to 0.45 cm.

In the present invention, the bioelectrochemical reactor can generate hydrogen or polyhydroxybutyrate while increasing the number of microbial catalysts by converting carbon dioxide in the reduction chamber by applying a specific potential.

In the present invention, the microorganism can generate hydrogen or polyhydroxybutyrate by receiving electrons from the anode by being attached to the surface of the cathode after being inoculated. The microorganisms may be directly attached to the surface of the cathode, thereby increasing cell growth and electron transfer efficiency from the electrode.

Referring to FIG. 2 , when glutamate or NH ₄ Cl is added as a nitrogen source to the reducing solution of the bioelectrochemical reactor of the present invention, it can be confirmed that the microorganism attached to the cathode produces hydrogen or polyhydroxybutyrate.

In the present invention, the ion exchange membrane may be a hydrogen ion exchange membrane, a cation exchange membrane, an anion exchange membrane, a bipolar membrane, or a ceramic separator.

In the present invention, the external electricity supply device or potentiometer is connected to the oxidation electrode, the reduction electrode, and the reference electrode through a circuit to supply power to the oxidation electrode and the reduction electrode, thereby generating a specific potential at the reduction electrode. can be authorized.

In the present invention, the external electricity supply device or potentiometer may move electrons generated at the anode to the cathode through an external circuit.

In the present invention, the bioelectrochemical reactor may be a photoautotrophic bioelectrochemical system.

In addition, in the present invention, the bioelectrochemical reactor can reduce the emission of carbon dioxide, which is a greenhouse gas, and it is possible to search for new strains capable of receiving electrons from electrodes and to develop microorganisms applicable to bioelectrochemical reaction systems. do.

Process method using a bioelectrochemical reactor

The present invention includes (1) inoculating microorganisms on the cathode of the bioelectrochemical reactor;

(2) continuously supplying the inert gas or carbon dioxide gas to the oxidation chamber and the reduction chamber of the bioelectrochemical reactor to maintain absolutely anaerobic conditions;

(3) adding electricity to the bioelectrochemical reactor;

(4) attaching microorganisms to the cathode of the bioelectrochemical reactor;

(5) confirming the development of red color as the microorganisms attach to the electrode surface; and

(6) generating hydrogen or polyhydroxybutyrate by supplying light to the bioelectrochemical reactor and performing carbon dioxide conversion;

It relates to a carbon dioxide conversion method comprising a.

The step (1) is a step of inoculating a microorganism on the cathode of the bioelectrochemical reactor. The microorganism to be inoculated may be a pure culture or a mixed inoculum, preferably the microorganism to be inoculated. may be a genus Rhodobacter, a genus Rhodopseudomonas, or an electrochemically active strain capable of photosynthesis under anaerobic conditions. The microorganisms may be inoculated into a liquid medium.

The medium of the bioelectrochemical reactor may be adjusted to a pH in the range of 6.5 to 7.5, preferably adjusted to a pH in the range of 6.6 to 7.4, and most preferably adjusted to a pH in the range of 6.7 to 7.3. The pH can be performed with a base known in the art such as sodium hydroxide solution.

The medium may be filtered sterilized through a membrane filter having a pore size in the range of 0.15 to 0.45 μm. The membrane filter may be a hydrophilic membrane filter.

The microorganisms may be stored in a deep freezer at a temperature ranging from -75 to -95 °C.

The step (2) is a step in which the inert gas or carbon dioxide gas is continuously supplied to the oxidation chamber and the reduction chamber of the bioelectrochemical reactor to maintain an absolutely anaerobic condition, and the inert gas may be nitrogen or argon. When the inert gas is nitrogen, the nitrogen source may be NH ₄ Cl, glutamate, or a known compound containing nitrogen.

The absolute anaerobic condition may refer to an environmental condition in which the oxygen concentration is in the range of 0 to 5 ppm, preferably an environmental condition in which the oxygen concentration is in the range of 0 to 2 ppm.

Step (3) is a step of adding electricity to the bioelectrochemical reactor, and the potential applied to the reduction electrode is -0.7V vs. Ag/AgCl to -1.1V vs. Ag/AgCl V range. Outside of the above range, -0.7V vs. Shows very low concentration hydrogen production when applied below Ag/AgCl, -1.1V vs. When Ag/AgCl or more is applied, a large amount of electricity can be consumed compared to hydrogen production.

The step (4) is a step of attaching microorganisms to the cathode of the bioelectrochemical reactor, and the microorganisms can generate hydrogen or polyhydroxybutyrate by receiving electrons from the electrode.

Since the microorganisms are attached to the cathode, the amount of airborne microorganisms may be reduced.

The step (5) is a step of supplying light to the bioelectrochemical reactor and performing carbon dioxide conversion to produce hydrogen or polyhydroxybutyrate. The bioelectrochemical reactor may operate under a light source such as an LED lamp or a fluorescent lamp. there is.

The bioelectrochemical reactor may be operated at a temperature in the range of 30 to 45 ° C, more preferably at a temperature in the range of 32 to 40 ° C.

The bioelectrochemical reactor may operate under a light condition of 5000 to 7000 lx, more preferably under a light condition of 5500 to 6500 lx.

Example

Hereinafter, embodiments of the present invention will be described in detail, but it is obvious that the present invention is not limited by the following examples.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the embodiments described below in detail. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to fully inform the person who has the scope of the invention, and the present invention is only defined by the scope of the claims.

1. Preparation of strains and media

Rhodobacter sphaeroides KCTC 1434 was obtained from Korea Institute of Energy Research. Stored in a deep freezer at -80°C with 15% glycerol. The growth medium had the following composition (L ^-1 ): 2.8 g KH ₂ PO ₄ , 0.2 g NH ₄ Cl, 4 g succinic acid, 0.1 g glutamate (L-glutamic acid), 0.4 g NaCl, 0.2 g nitrilotriacetic acid, 0.24 g MgCl ₂ ****H ₂ O, 0.03 g CaCl ₂ , 2 mg FeSO ₄ ****H ₂ O, 20 mg (NH ₄ ) ₆ Mo ₇ O ₂₄ , 100 μL trace element solution and 100 μL vitamins solution. The bioelectrochemical reactor medium had the following composition (L ^-1 ): 2.8 g KH ₂ PO ₄ , 0.4 g NaCl, 0.2 g MgCl ₂ ****H ₂ O, 0.02 g CaCl ₂ , 0.1 g Na ₂ MoO ₄ , 100 μL of trace element solution and 100 μL of vitamin solution. Pure carbon dioxide was used as the sole carbon source in the hydrogen production experiments. Glutamate or L-glutamic acid (2 mM) was used as a nitrogen source to maintain nitrogenase activity for hydrogen production. As a nitrogen source for producing polyhydroxybutyrate, ammonium chloride (NH ₄ Cl, 0.2 g/l) was used instead of glutamate. The trace element solution had the following composition (100 mL ^-1 ): 2 g of EDTA, 11 g of ZnSO ₄ 7H ₂ O, 5 g of FeSO ₄ 7H ₂ O, 1.6 g of MnSO ₄ 5H ₂ O, 0.4 g of CuSO ₄ 5H ₂ O, 0.3 g of Co(NO ₃ ) ₂ 6H ₂ O, and 0.2 g of H ₃ BO ₃ . The vitamin solution had the following composition (100 mL ⁻¹ ): 1 g of nicotinic acid, 0.5 g of thiamine HCl and 0.03 g of biotin. The medium was adjusted to a pH of 7±0.3 using 10% NaOH solution. All culture media were sterilized by filtration through a hydrophilic membrane filter with a pore size of 0.2 μm.

2. Bioelectrochemical reactor construction and operation

The H-type bioelectrochemical reactor had an oxidation chamber and a reduction chamber with a working volume of 250 mL and a maximum headspace volume of 220 mL, respectively. Oxidation and reduction chambers were connected to a glass tube and separated using an ion exchange membrane (PEM, Nafion 117, Dupont). The cathode was a piece of carbon felt measuring 5 cm x 5 cm. The piece is 0.5 cm thick and is connected to a titanium wire. Carbon granules (80 g) were added to the oxidation chamber and a titanium wire was used as a current collector from the carbon granules. A reference electrode Ag/AgCl (3M KCl) was placed inside the reduction chamber. All bottles and reactors were sterilized at a temperature of 121° C. for 15 minutes by autoclaving. After the autoclaving, the reduction chamber was flushed with 100% carbon dioxide for 30 minutes or more to remove residual oxygen. Using Potentiostat -0.9V vs. Ag/AgCl (3M KCl) was applied. Experiments were performed in batch mode under anaerobic conditions. Headspace gas was replaced with 100% carbon dioxide daily. The bioelectrochemical reactor was placed at 35±3° C. and 6000±500 lx under a white/yellow mixed LED lamp.

Experimental Example 1 - Measurement of hydrogen production and carbon dioxide consumption according to different nitrogen sources

Referring to Figure 3, the current consumption of the system according to the potential applied to the reduction electrode of the bioelectrochemical reactor of the present invention and the resulting hydrogen production amount are compared, and when -0.9V (vs. Ag / AgCl), the consumption The current range was the widest, and hydrogen production according to the current consumption was the most efficient. At this time, it was confirmed that the current was best transmitted from the electrode to the microorganisms and the average hydrogen production amount was as high as 320 ml/l/day.

Referring to FIG. 4, -0.9V (vs Ag/AgCl) was applied to the reduction electrode of the bioelectrochemical reactor of the present invention, and hydrogen production (A) and carbon dioxide consumption (B) under light culture conditions of 6000 lux light intensity ) is compared, through which the amount of hydrogen produced according to the influence of the nitrogen source can be compared. It can be seen that when glutamate was used as the nitrogen source, the hydrogen production amount was 328 ml/l/day, whereas when ammonium chloride (NH ₄ Cl) was used, the hydrogen production amount was 67 ml/l/day. In addition, when glutamate was used as a nitrogen source, carbon dioxide consumption was 104 ml/L/day, whereas when ammonium chloride (NH ₄ Cl) was used, carbon dioxide consumption was 148 ml/L/day. Hydrogen production of 60 mL/L/day was observed even under dark culture conditions without light supply.

Referring to FIG. 5, when glutamate and ammonium chloride (NH ₄ Cl) are added as nitrogen sources to the reducing liquid of the bioelectrochemical reactor of the present invention, electrons consumed throughout the system and among them, electrons recovered as hydrogen can be confirmed. there is. When glutamate was used as the nitrogen source, the Coulombic efficiency was more than 90%, and it can be inferred that most of the electrons consumed in the system were recovered as hydrogen.

Referring to FIG. 6, when glutamate and NH ₄ Cl were added as nitrogen sources to the reducing solution of the bioelectrochemical reactor of the present invention, the change in the amount of airborne microorganisms and microorganisms attached to the electrodes over time could be confirmed. there is. After 3 days, it can be confirmed that most of the microorganisms are attached to the electrode and the airborne microorganisms are reduced.

Referring to FIG. 8 , it is possible to confirm a result of comparing the amount of polyhydroxybutyrate (PHB) produced according to the composition of the gas supplied to the bioelectrochemical reactor and the nitrogen source. When ammonium chloride (NH ₄ Cl) was used as a nitrogen source under carbon dioxide conditions, the production amount was up to 30.8 mg/L, whereas when glutamate was used as a nitrogen source, the production amount was up to 8.8 mg/L. In addition, when an inert gas such as argon was used instead of carbon dioxide, it was confirmed that there was no difference from the initial inoculation. The difference in polyhydroxybutyrate production amount according to the nitrogen source was confirmed through the fluorescence microscopy analysis results below.

Referring to Table 1 below, it can be confirmed the amount of polyhydroxybutyrate (PHB) produced when ammonium chloride (NH ₄ Cl) and glutamate are added as nitrogen sources.

[Table 1]

Experimental Example 2 - Observation of microorganisms

Referring to FIG. 7 , it can be confirmed that the growth patterns of microorganisms are different when microorganisms are inoculated in a bioelectrochemical reactor under different culture conditions in a medium. (A) is when -0.9V vs Ag/AgCl voltage is applied to the NH ₄ Cl medium, (B) is when -0.9V vs Ag/AgCl voltage is applied to the glutamate medium, and (C) is an external electrical supply Or, it is the case of driving with an open circuit without supplying power to the potentiometer. Through this, the electrode attachment pattern of microorganisms according to the presence or absence of a potential was confirmed, and it was confirmed that the microorganisms adhered well to the electrode and proliferated when the potential was applied. When voltage was applied with an external electric supply device or a potentiometer, it was confirmed that the electrode surface was colored red as microorganisms grew, but there was no change when operated with an open circuit.

Referring to FIG. 9 , when the reactor was operated while applying voltage through an external electrical supply device or a potentiometer, it was confirmed that microorganisms were attached to the electrode surfaces of the carbon rod, indium tin oxide, and titanium mesh as the microorganisms grew.

From the above description, those skilled in the art pertaining to the present invention will be able to understand that the present invention can be implemented in other specific forms without changing its technical spirit or essential features. In this regard, the embodiments described above are illustrative in all respects and should be understood as non-limiting.

Claims (9)

an oxidation chamber in which an oxidation electrode is located and electrons and hydrogen ions are generated through electrolysis;
a reduction chamber in which a reduction electrode inoculated with microorganisms is located, and carbon dioxide gas is continuously supplied to apply a reduction potential to the reduction electrode so that photoreactive microorganisms convert carbon dioxide;
an ion exchange membrane positioned between the oxidation chamber and the reduction chamber to transfer hydrogen ions generated in the oxidation chamber to the reduction chamber; and
An electricity supply device connected through an external circuit of the oxidation electrode and the reduction electrode to supply power to the oxidation chamber and the reduction chamber and to apply a reduction potential or reduction current to the reduction electrode;
The oxidation chamber and the reduction chamber are
The inert gas and carbon dioxide gas are continuously supplied to maintain absolute anaerobic conditions,
The inert gas is nitrogen or argon gas,
The carbon dioxide gas is a bioelectrochemical reactor, characterized in that pure carbon dioxide or a mixed gas of carbon dioxide and inert gas.

According to claim 1,
The oxidation chamber or the reduction chamber is a bioelectrochemical reactor, characterized in that it comprises a device for supplying light such as an LED lamp or a fluorescent lamp.
According to claim 1,
The oxidation chamber or reduction chamber
a gas supply unit for supplying the inert gas or carbon dioxide gas into the oxidation chamber and the reduction chamber;
a gas inlet for injecting the gas supplied by the gas supply unit into the oxidation chamber and the reduction chamber;
a micro-bubble diffuser for injecting the supplied gas into the liquid phase of the reactor in a bubble state;
a gas outlet for discharging the gas supplied through the gas inlet or gas generated by electrolysis; and
The bioelectrochemical reactor further comprising an oxygen removal trap for removing trace amounts of oxygen present in the inert gas.
According to claim 1,
The microorganism inoculated on the cathode is a strain of the genus Rhodobacter or the genus Rhodopseudomonas,
The bioelectrochemical reactor, characterized in that the microorganism generates hydrogen or polyhydroxybutyrate by receiving electrons through the reduction electrode.
According to claim 1,
The microorganism is a bioelectrochemical reactor characterized by an electrochemically active strain capable of photosynthesis under anaerobic conditions.
According to claim 1,
Characterized in that the anode or cathode is formed of carbon felt, carbon brush or carbon granule, carbon material of carbon rod, metal material or polymer material bioelectrochemical reactor.
According to claim 1,
The ion exchange membrane is a bioelectrochemical reactor, characterized in that a hydrogen ion exchange membrane, a cation exchange membrane, an anion exchange membrane, a bipolar membrane or a ceramic separator.
According to claim 1,
The bioelectrochemical reactor is a bioelectrochemical reactor, characterized in that the photoautotrophic bioelectrochemical system.
(1) inoculating microorganisms on the cathode of the bioelectrochemical reactor according to any one of claims 1 to 8;
(2) continuously supplying the inert gas or carbon dioxide gas to the oxidation chamber and the reduction chamber of the bioelectrochemical reactor to maintain absolutely anaerobic conditions;
(3) adding electricity to the bioelectrochemical reactor;
(4) attaching microorganisms to the cathode of the bioelectrochemical reactor;
(5) confirming the development of red color as the microorganisms attach to the electrode surface; and
(6) generating hydrogen or polyhydroxybutyrate by supplying light to the bioelectrochemical reactor and performing carbon dioxide conversion;
Carbon dioxide conversion method using a bioelectrochemical reactor comprising a.

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