WO2023238635A1 - Lithium recovery agent, lithium recovery method, lithium recovery system, method for producing lithium-containing manganese oxide, and method for producing positive electrode active substance for lithium ion battery - Google Patents
Lithium recovery agent, lithium recovery method, lithium recovery system, method for producing lithium-containing manganese oxide, and method for producing positive electrode active substance for lithium ion battery Download PDFInfo
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- WO2023238635A1 WO2023238635A1 PCT/JP2023/018793 JP2023018793W WO2023238635A1 WO 2023238635 A1 WO2023238635 A1 WO 2023238635A1 JP 2023018793 W JP2023018793 W JP 2023018793W WO 2023238635 A1 WO2023238635 A1 WO 2023238635A1
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- lithium
- lithium recovery
- recovery agent
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- reaction
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 303
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 302
- 238000011084 recovery Methods 0.000 title claims abstract description 174
- 239000003795 chemical substances by application Substances 0.000 title claims description 113
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 title claims description 49
- 238000000034 method Methods 0.000 title claims description 48
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims description 42
- 229910001416 lithium ion Inorganic materials 0.000 title claims description 42
- 238000004519 manufacturing process Methods 0.000 title claims description 14
- 239000013543 active substance Substances 0.000 title 1
- 239000007788 liquid Substances 0.000 claims abstract description 67
- 241000894006 Bacteria Species 0.000 claims abstract description 60
- 238000009830 intercalation Methods 0.000 claims abstract description 57
- 230000002687 intercalation Effects 0.000 claims abstract description 57
- 239000000463 material Substances 0.000 claims abstract description 50
- 238000006243 chemical reaction Methods 0.000 claims description 103
- 239000002994 raw material Substances 0.000 claims description 66
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 claims description 23
- 239000011572 manganese Substances 0.000 claims description 21
- 239000002244 precipitate Substances 0.000 claims description 20
- 239000002245 particle Substances 0.000 claims description 18
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- 238000005341 cation exchange Methods 0.000 claims description 10
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- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 8
- 229910052748 manganese Inorganic materials 0.000 claims description 8
- 230000007246 mechanism Effects 0.000 claims description 8
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- 150000001875 compounds Chemical class 0.000 claims description 7
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- 150000003624 transition metals Chemical class 0.000 claims description 5
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- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 3
- 230000005611 electricity Effects 0.000 claims description 3
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- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 3
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- -1 Mn 3 O 4 Chemical class 0.000 description 8
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- QEXMICRJPVUPSN-UHFFFAOYSA-N lithium manganese(2+) oxygen(2-) Chemical compound [O-2].[Mn+2].[Li+] QEXMICRJPVUPSN-UHFFFAOYSA-N 0.000 description 3
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- 239000003463 adsorbent Substances 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
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- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical class [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 1
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- ZJTJUVIJVLLGSP-UHFFFAOYSA-N lumichrome Chemical class N1C(=O)NC(=O)C2=C1N=C1C=C(C)C(C)=CC1=N2 ZJTJUVIJVLLGSP-UHFFFAOYSA-N 0.000 description 1
- 229910001437 manganese ion Inorganic materials 0.000 description 1
- PPNAOCWZXJOHFK-UHFFFAOYSA-N manganese(2+);oxygen(2-) Chemical class [O-2].[Mn+2] PPNAOCWZXJOHFK-UHFFFAOYSA-N 0.000 description 1
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- 229910052760 oxygen Inorganic materials 0.000 description 1
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical class [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 1
- 239000008363 phosphate buffer Substances 0.000 description 1
- 229920000747 poly(lactic acid) Polymers 0.000 description 1
- 239000004626 polylactic acid Substances 0.000 description 1
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- 238000010248 power generation Methods 0.000 description 1
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- 239000001632 sodium acetate Substances 0.000 description 1
- 235000017281 sodium acetate Nutrition 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
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- 125000001424 substituent group Chemical group 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
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- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910001935 vanadium oxide Inorganic materials 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G45/00—Compounds of manganese
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/34—Biological treatment of water, waste water, or sewage characterised by the microorganisms used
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
- C12N1/20—Bacteria; Culture media therefor
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P3/00—Preparation of elements or inorganic compounds except carbon dioxide
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
- C22B26/10—Obtaining alkali metals
- C22B26/12—Obtaining lithium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/18—Extraction of metal compounds from ores or concentrates by wet processes with the aid of microorganisms or enzymes, e.g. bacteria or algae
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/54—Reclaiming serviceable parts of waste accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
Definitions
- the present invention relates to a lithium recovery agent, a lithium recovery method, a lithium recovery system, a method for producing a lithium-containing manganese oxide, and a method for producing a positive electrode active material for a lithium ion battery.
- a lithium recovery method comprising bringing the lithium recovery agent according to any one of [1] to [11] into contact with the raw material liquid.
- the lithium recovery method according to [14] wherein the raw material liquid contains lithium ions introduced from the outside via a cation exchange membrane.
- a lithium recovery system comprising a reaction vessel and the lithium recovery agent according to any one of [1] to [11] disposed in the reaction vessel, wherein , a lithium recovery system in which the raw material liquid and the lithium recovery agent are in contact with each other; [17] The lithium recovery system according to [16], which does not have a mechanism for applying electricity to the lithium recovery agent. [18] The lithium recovery system according to [16], wherein the reaction vessel includes a cation exchange membrane for introducing lithium ions into the raw material liquid from outside the reaction vessel. [19] A method for producing a lithium-containing manganese oxide, comprising the lithium recovery method according to any one of [12] to [15], wherein the lithium intercalation material is manganese dioxide. [20] A method for producing a positive electrode active material for a lithium ion battery, comprising the lithium recovery method according to any one of [12] to [15].
- FIG. 4 is a diagram showing the results of X-ray diffraction (XRD) measurement of the powder (after reaction) obtained in Experiment 4-4. It is a conceptual diagram explaining the lithium recovery system of other embodiments. This is an image showing the setup for a demonstration test of a lithium recovery system. This is a comparison of an image of a screw vial before being immersed in a LiCl/PBS (10 mM) solution (left) and an image of a screw vial after being immersed and reacted for 24 hours (right).
- FIG. 6 is a diagram showing the results of X-ray diffraction (XRD) measurement of the powder (after reaction) obtained in Experiment 6-1.
- FIG. 4 is a diagram showing the results of X-ray diffraction (XRD) measurement of the powder (after reaction) obtained in Experiment 4-4.
- XRD X-ray diffraction
- the lithium recovery agent of this embodiment mainly includes power-generating bacteria and a lithium intercalation material.
- the lithium recovery agent of this embodiment comes into contact with a raw material liquid containing lithium and recovers lithium in the raw material liquid.
- Examples of current-generating bacteria include iron-reducing bacteria.
- Specific examples of iron-reducing bacteria include bacteria of the genus Shewanella and bacteria of the genus Geobacter. These power-generating bacteria are safe because they are not pathogenic bacteria, and because they multiply rapidly, sufficient effects can be obtained even when the initial input amount is small, which is preferable.
- Species of Shewanella bacteria include S. oneidensis, S. loihica, S. putrefaciens, S. algae, etc. .
- Species of Geobacter bacteria include Geobacter sulfurreducens, Geobacter metallireducens, and the like.
- the power-generating bacteria may be known or unknown. These power-generating bacteria may be used alone or in a mixture of two or more types, within the range where the effects of this embodiment are achieved.
- the type of lithium intercalation material (composition, crystal structure, shape, etc.) is not particularly limited, and may be appropriately selected within the range that provides the effects of this embodiment.
- the lithium intercalation material may be a compound containing a first transition metal, such as manganese (Mn), vanadium (V), titanium (Ti), and iron (Fe). There are many things that can be mentioned.
- the lithium recovery agent of this embodiment may be formed only from power-generating bacteria and a lithium intercalation material, or may contain other components as long as the effects of this embodiment are achieved.
- the electron donor may be a substance that can be decomposed (metabolized) by the power-generating bacteria contained in the lithium recovery agent and/or the bacteria contained in the raw material solution and donate electrons to the power-generating bacteria. , its type, state, etc. are not particularly limited.
- the electron donor may be solid, liquid, gaseous, or a mixture thereof, and may be arbitrarily selected depending on the specific form of the lithium recovery method. For example, when seawater is used as a raw material liquid (or when a raw material liquid is prepared from it), the original lithium (ion) content is small, for example, about 0.2 ppm.
- Examples of the material of such a solid substance include metals such as magnesium and iron, and organic substances such as cellulose and polylactic acid. Its form is not particularly limited and may be particulate or lumpy. When it is in the form of particles, the reaction tends to proceed more efficiently, and when it is in the form of lumps, it is easier to fix in the vicinity of the lithium recovery agent, which is preferable.
- the gas when using a gaseous electron donor, the gas may be supplied near the lithium recovery agent.
- an electrode may be installed near the lithium recovery agent, and hydrogen may be generated by electrolysis of cooling water.
- An example of a gaseous electron donor is hydrogen. Note that among the solid electron donors mentioned above, metals (iron, magnesium, etc.) can generate hydrogen in the raw material solution (reaction solution), so they themselves can act as electron donors, and they also contribute to the system. It can also become an indirect electron donor by releasing hydrogen into the molecule.
- organic substances include lactate salts such as sodium lactate, acetate salts such as sodium acetate, and the like. It is preferable to appropriately select an electron donor that increases power generation efficiency based on the type of current-generating bacteria (power-generating bacteria).
- the electron donor is preferably lactate
- the power-generating bacterium is a Geobacter bacterium
- the electron donor is preferably acetate.
- one type of electron donor may be used alone, or two or more types may be used in combination as long as the effects of this embodiment are achieved.
- the above organic substance may be provided as a solid, a liquid (solution), or a mixture thereof.
- a polymer gel swollen with a solution containing the above-mentioned organic substance can also be used as an electron donor. Since the swollen polymer gel releases the organic substance into the reaction solution in a sustained manner, the reaction can proceed more efficiently.
- the lithium recovery agent may further include an electron mediator. Electrons generated by power-generating bacteria are transferred to electron acceptors (lithium intercalation material) outside the bacterial cells via electron transfer proteins present in the extracellular membrane. The electron mediator activates electron transfer proteins to further facilitate electron transfer to the lithium intercalation material. As a result, lithium recovery efficiency is improved and, for example, recovery time (reaction time) can be shortened.
- electron mediators include flavins and quinones. Flavins is a general term for derivatives of 7,8-dimethylisoalloxazine having a substituent at the 10th position, and includes riboflavin (vitamin B2), FAD, and FMN.
- Quinones are aromatic organic compounds having a cyclic diketone structure having a double bond and containing six carbon atoms, such as p-benzoquinone, o-quinone, anthraquinone, and the like. These electronic mediators may be used singly or in combination of two or more types, within the range where the effects of this embodiment are achieved.
- the lithium recovery agent further contains a liquid (hereinafter referred to as "liquid component") including various inorganic salt buffers such as boric acid, phosphoric acid, and carbonic acid, water, physiological saline, and cell culture medium. It's okay.
- liquid component including various inorganic salt buffers such as boric acid, phosphoric acid, and carbonic acid, water, physiological saline, and cell culture medium. It's okay.
- the lithium recovery agent includes a cell culture medium, power-generating bacteria can be cultured and expanded within the lithium recovery agent.
- One type of liquid component may be used alone, or two or more types may be used as a mixture within a range where the effects of this embodiment are achieved.
- the lithium recovery agent of this embodiment may be composed of a first agent containing power-generating bacteria and the above-mentioned liquid component, and a second agent containing a lithium intercalation material.
- the second agent may be composed only of the lithium intercalation material, or may further include the above-mentioned liquid component.
- these components may be contained in the first agent and/or the second agent, or may be contained in a separate other agent (for example, the second agent). It may be used as a third agent and/or a fourth agent).
- the first agent, second agent, and other agents can be stored in separate containers, and when using the lithium recovery agent, the first agent, second agent, and other agents are mixed with the raw material liquid. You may.
- the raw material liquid is not particularly limited as long as it is a liquid containing lithium, and may be appropriately selected as long as it achieves the effects of this embodiment.
- Examples of raw material liquids include seawater, salt lake brine, geothermal water, lithium-containing aqueous solutions obtained by recycling lithium ion batteries, mine drainage, industrial wastewater, etc., but lithium recovery agents include Preferably, it is not cytotoxic to power-generating bacteria.
- seawater has a low lithium concentration of about 0.025 mM, seawater is an important lithium supply source because it is easily available in large quantities. Since the lithium recovery agent of this embodiment can efficiently recover lithium even from a raw material liquid with a low lithium concentration, seawater is suitable for the raw material liquid of this embodiment.
- the lithium concentration of the raw material solution is not particularly limited, and the lithium recovery agent of this embodiment can be used with raw material solutions having a wide range of lithium concentrations, for example, from 0.01 mM to 50 mM, and for example, from 0.01 mM to 1 mM. Lithium can be efficiently recovered even from raw material liquids with low lithium concentration. Further, the raw material liquid may contain an organic substance that can serve as an electron donor and can be decomposed by power-generating bacteria. When the raw material liquid contains a sufficient amount of an electron donor (organic substance), the lithium recovery agent does not need to contain an electron donor, or the content of the electron donor can be reduced.
- an electron donor organic substance
- FIG. 1 shows a schematic diagram of a lithium recovery agent 100 in contact with a raw material liquid 200 containing lithium.
- the electron donor 20 is decomposed (metabolized) within the power generating bacteria 10 contained in the lithium recovery agent 100, and electrons e.sup.- are generated.
- the generated electron e - is transferred to an electron acceptor (lithium intercalation material) 40 outside the bacterial body via an electron transfer protein 30 present in the outer cell membrane of the power-generating bacterium 10. This promotes electrochemical intercalation in which lithium ions in the raw material liquid are incorporated into the lithium intercalation material 40, and lithium (lithium ions Li + ) is recovered from the raw material liquid 200.
- the inventors discovered for the first time that lithium intercalation is significantly promoted by power-generating bacteria, leading to the present invention. Furthermore, in the lithium recovery agent of this embodiment, particles of the lithium intercalation material tend to form aggregates due to components derived from power-generating bacteria during lithium recovery (during reaction). It is presumed that this improves the conductivity and adhesion between particles and further increases the lithium recovery efficiency.
- the lithium recovery agent of this embodiment can efficiently recover lithium by a simple method of contacting with a raw material liquid containing lithium (for example, dispersing the lithium recovery agent in the raw material liquid). Therefore, compared to the conventional methods disclosed in Non-Patent Documents 1 to 3, there is no need for a paint preparation (kneading) process or coating process, and the equipment necessary for that process (kneader, coater, dryer, etc.) is also unnecessary. Further, electrochemical devices such as electrodes, wiring, and potentio-galvanostat are not required. Furthermore, in the present embodiment, the lithium intercalation material incorporating lithium forms aggregates and precipitates with components derived from power-generating bacteria, and therefore can be easily separated from the reaction solution. As described above, the lithium recovery agent of the present embodiment is advantageous in terms of time and money, requires fewer steps and equipment, has a lower environmental impact, and is highly applicable to mass production equipment.
- manganese oxide when used as a lithium intercalation material, at least a portion of the manganese oxide is reduced by electrons transferred from power-generating bacteria.
- manganese dioxide e.g., MnO 2
- the average oxidation number of manganese (Mn) in the manganese oxide lithium insertion compound is not particularly limited, but is, for example, +3 to +4. Note that lithium ions incorporated into manganese oxide are not reduced.
- the lithium recovery agent of this embodiment has a metal recovery mechanism that is significantly different from a recovery agent that directly reduces and recovers metal ions in the raw material liquid.
- metal ions in the raw material liquid are directly reduced and recovered, there is a risk that metals other than the target metal contained in the raw material liquid may also be reduced and recovered at the same time.
- the lithium recovery agent of the present embodiment electrons supplied by the power-generating bacteria are transferred to the lithium intercalation material, and lithium ions in the raw material liquid are selectively taken into the lithium intercalation material. Therefore, even when metal ions other than lithium ions are contained in the raw material liquid, the lithium recovery agent of this embodiment can selectively recover lithium ions.
- the lithium recovery system 1000 shown in FIG. 1 will be described.
- the lithium recovery system 1000 includes a reaction vessel 300 and the lithium recovery agent 100 of this embodiment placed in the reaction vessel 300, and the raw material liquid 200 and the lithium recovery agent 100 come into contact within the reaction vessel 300.
- lithium ions in the raw material liquid are taken into the lithium intercalation material 40 (intercalation), and lithium (lithium ions Li + ) is recovered from the raw material liquid 200.
- the lithium recovery system 1000 does not need to have an energizing mechanism (for example, a power source, wiring, electrodes, etc.) for energizing the lithium recovery agent 100. This is because the power-generating bacteria 10 contained in the lithium recovery agent 100 can supply sufficient electrons to the lithium intercalation material for the lithium recovery reaction. Since it does not have a current supply mechanism, the lithium recovery system 1000 can be manufactured and operated at low cost, and has a low environmental load.
- an energizing mechanism for example, a power source, wiring, electrodes, etc.
- FIG. 8 is a conceptual diagram of another embodiment of the lithium recovery system.
- the lithium recovery system 1100 includes a reaction vessel 300 and a lithium recovery agent 100 disposed in the reaction vessel 300, and further includes a reaction vessel 300 for introducing lithium ions 130 into the raw material liquid 200 from the outside.
- a cation exchange membrane 400 is provided.
- the cation exchange membrane 400 is disposed in a pipe that communicates the secondary cooling water pipe 110 of the power plant with the reaction vessel 300, and transfers lithium ions 130 contained in the cooling water 210 in the external pipe 110 to the reaction vessel 300 side. to be introduced.
- the reaction vessel 300 is installed in the middle of the secondary cooling water piping 110 of the power plant, but the installation location of the lithium recovery system of this example is not limited to the above.
- the reaction container 300 may be immersed in a larger container containing water containing lithium ions (for example, some type of water treatment tank), a lake, the ocean, or the like.
- the lithium recovery system of this embodiment can easily maintain the inside of the reaction vessel 300 in a state suitable for lithium recovery (for example, an anaerobic state), and can more efficiently recover lithium even from low-concentration lithium ions.
- the lithium recovery method may be implemented using the lithium recovery system 1000 (see FIG. 1) described above.
- the lithium recovery method includes a step of bringing a lithium recovery agent into contact with a raw material liquid (step S1 in FIG. 2).
- An example of a lithium recovery method will be described below according to the flowchart of FIG. 2.
- a reaction solution containing a raw material solution and a lithium recovery agent is prepared (step S1 in FIG. 2). This brings the lithium recovery agent into contact with the raw material liquid.
- a precipitate is generated in the reaction solution (step S2 in FIG. 2).
- a reaction (intercalation) occurs in which lithium ions in the raw material solution are incorporated into the lithium intercalation material.
- a precipitate containing the lithium recovery agent and lithium incorporated into the lithium recovery agent is generated, and the lithium in the raw material liquid is recovered in the precipitate.
- reaction time the time from when the reaction solution is prepared (step S1 in FIG. 2) to when the precipitate is separated from the reaction solution (step S3 in FIG. 2), which will be described later, is defined as "reaction time.”
- the reaction time can be adjusted as appropriate within the range that produces the effects of this embodiment, and may be, for example, 10 minutes to 3 days, or 1 hour to 3 hours. If the reaction time is within the above range, the intercalation reaction will proceed sufficiently and a precipitate containing a sufficient amount of lithium will be obtained.
- the temperature of the reaction solution during the reaction (reaction temperature) may be, for example, 4°C to 40°C or 25°C to 30°C. When the reaction temperature is within the above range, the activity of the power-generating bacteria becomes more active, resulting in improved lithium recovery efficiency. Further, during the reaction (during the reaction time), the reaction solution may be left standing, or may be shaken, stirred, etc.
- a lithium intercalation material containing lithium ions (for example, the above-mentioned lithium-containing manganese oxide) can be used as a positive electrode active material of a lithium ion battery. That is, the lithium recovery method of this embodiment can be applied to a method for manufacturing a positive electrode active material of a lithium ion battery. In this production method, it is possible to use seawater etc. as a lithium source (raw material liquid), and by using power-generating bacteria, it is possible to produce positive electrode active materials for lithium-ion batteries in a low-cost and simple manner. be. Among these, lithium-containing manganese oxide is attracting attention as a positive electrode material for lithium ion batteries because Mn is cheaper than Co, has large reserves, and can be expected to have a stable supply in the future.
- Lithium was recovered from the raw material liquid (lithium aqueous solution) using a lithium recovery agent containing the following components. Note that the ⁇ -MnO 2 particles were produced by acid-treating LiMn 2 O 4 having a spinel structure. ⁇ Lithium recovery agent component> Power-generating bacteria: Schwanella bacteria Electron donor: Sodium lactate Intercalation material: Manganese dioxide with spinel structure ( ⁇ -MnO 2 particles, average particle size: 100-300 nm)
- reaction solution an aqueous solution in which lithium chloride and sodium lactate were dissolved in a phosphate buffer was prepared (lithium chloride concentration: 50 mM, sodium lactate concentration: 50 mM). 0.05 g of manganese oxide particles were mixed into 50 mL of the prepared solution. Next, dissolved oxygen in the solution was removed by nitrogen bubbling, Shewanella bacteria were introduced, and the container was sealed to obtain a reaction solution. The Schwanella bacteria were added in an amount adjusted so that the optical density (OD value) would be 0.3 when dispersed in 50 mL of the reaction solution.
- OD value optical density
- Example 2 A powder, the final product, was obtained in the same manner as in Experiment 1, except that the Schwanella bacterium was not used (it was not introduced into the container).
- ⁇ Crystal structure evaluation> The powder obtained in Experiment 2 was subjected to X-ray diffraction (XRD) measurement using the same method as in Experiment 1. The results are shown in FIG. 5 as “after reaction”. For comparison, the profile of ⁇ -MnO 2 is also shown in FIG. 5 as “before reaction ( ⁇ -MnO 2 )”. In contrast to the results of Experiment 1 (FIG. 3), the profile after the reaction showed a large attenuation of peak intensity and a broad peak shape. This suggests that the crystallinity of manganese oxide has decreased, and there is a possibility that side reactions other than the lithium insertion reaction that occur while maintaining the crystal skeleton structure are occurring.
- XRD X-ray diffraction
- the lithium concentration in the reaction solution was 20 mM, 10 mM, 5 mM, 2 mM, 1 mM, and 0.5 mM, respectively.
- the final product, a powder was obtained in the same manner as in Experiment 1.
- Experiments 4-1 and 4-2 the reaction time was shortened to 3 hours, except for Experiment 3-3 (lithium concentration in the reaction solution: 5 mM) and Experiment 3-2 (lithium concentration in the reaction solution: 10 mM). An experiment was conducted under the same conditions as above, and the final product, a powder, was obtained. In Experiments 4-3 and 4-4, experiments were conducted under the same conditions as Experiments 4-1 and 4-2, except that the lithium recovery agent contained riboflavin, which is an electron mediator. Obtained. The riboflavin concentration in the reaction solution was 2 ⁇ M.
- ⁇ Crystal structure evaluation> Using the same method as in Experiment 1, X-ray diffraction (XRD) measurements were performed on the powders obtained in Experiments 4-1 to 4-4. The results of X-ray diffraction (XRD) measurements are shown in FIGS. 7A to 7D. For comparison, the peak position of ⁇ -MnO 2 is shown in FIGS. 7A to 7D by a vertical broken line with a subscript " ⁇ -MnO 2 ".
- Li concentration measurement The Li concentration of the seawater before the reaction (raw material liquid) and the seawater after the reaction (the reaction liquid after Li recovery) used in Experiment 5 was measured by ICP emission spectrometry. The results are shown below.
- the lithium recovery rate can be calculated to be approximately 96 to 98% by weight.
- the results of Experiment 5 confirmed that lithium could be recovered at a high recovery rate even when seawater was used as the raw material liquid.
- FIG. 9A is an image representing the setup.
- a glass screw vial is immersed upside down in a container (glass beaker) containing a LiCl/PBS (10, 50 mM) solution.
- a LiCl/PBS (10, 50 mM) solution For illustrative purposes, some of the images have been altered, such as removing the background.
- FIG. 9B is a comparison of an image of a screw vial before immersion in LiCl/PBS (10 mM) solution (left) and an image of a screw vial after 24 hours of reaction after immersion (right).
- the solution before immersion was reddish brown, whereas the solution after reaction changed to a brown color closer to black. This suggested an interaction between lithium and ⁇ -MnO 2 .
- the shading of red is actually represented as the shading of black.
- the lithium recovery agent of the present invention can recover lithium simply and efficiently.
- the recovered lithium can be used as a raw material for lithium ion secondary batteries, fuel for nuclear fusion reactors, etc.
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Abstract
In the present invention, lithium can be easily and efficiently recovered from a lithium-containing starting liquid, using a lithium recovery agent containing an electricity-generating bacterium and a lithium intercalation material.
Description
本発明は、リチウム回収剤、リチウム回収方法、リチウム回収システム、リチウム含有マンガン酸化物の製造方法、及びリチウムイオン電池の正極活物質の製造方法に関する。
The present invention relates to a lithium recovery agent, a lithium recovery method, a lithium recovery system, a method for producing a lithium-containing manganese oxide, and a method for producing a positive electrode active material for a lithium ion battery.
リチウム（Ｌｉ）は、リチウムイオン二次電池や核融合炉の燃料等の原料として需要の高い資源であり、安定供給可能かつより安価な採取方法が求められている。Ｌｉの安定供給源としては、陽イオンＬｉ＋の形で溶存する海水等がある。また、バッテリー寿命等により廃棄されたリチウム二次電池からの安価な回収技術も期待されている。
Lithium (Li) is a resource in high demand as a raw material for lithium ion secondary batteries, fuel for nuclear fusion reactors, and the like, and a method for extracting it that can be stably supplied and is cheaper is required. Stable sources of Li include seawater dissolved in the form of cationic Li + . There are also expectations for inexpensive recovery technology for lithium secondary batteries that have been discarded due to battery life.
海水等からのＬｉの回収技術の１つとして、非特許文献１～３では、以下に説明する電気化学的なリチウム回収法が報告されている。まず、リチウムを選択的に吸蔵できるスピネル型構造の酸化マンガン等のリチウム吸着剤と、カーボン等の導電助剤と、ポリフッ化ビニリデン等の結着剤とを混練した塗料（混練物）を調製する。この塗料を電極に塗布して合剤電極を作製する。そして、ポテンショ・ガルバノスタット等の電気化学装置を用いて電極に通電を行うことにより、リチウム吸着剤中にリチウムを回収する。
As one of the techniques for recovering Li from seawater and the like, Non-Patent Documents 1 to 3 report the electrochemical lithium recovery method described below. First, a paint (kneaded material) is prepared by kneading a lithium adsorbent such as manganese oxide with a spinel structure that can selectively absorb lithium, a conductive agent such as carbon, and a binder such as polyvinylidene fluoride. . This paint is applied to the electrode to produce a mixture electrode. Then, by applying electricity to the electrode using an electrochemical device such as a potentio-galvanostat, lithium is recovered into the lithium adsorbent.
しかし、非特許文献１～３に開示される従来のリチウム回収方法は、塗料調製（混練）工程、や塗布工程が必要であり、更に、電極に通電を行うための電気化学装置も必要である。このように、従来のリチウム回収方法では、複雑な工程や設備に要する時間やコストが課題となっていた。
However, the conventional lithium recovery methods disclosed in Non-Patent Documents 1 to 3 require a paint preparation (kneading) process and a coating process, and also require an electrochemical device to energize the electrodes. . As described above, conventional lithium recovery methods have problems with the time and cost required for complicated processes and equipment.
本発明は、上記課題を解決するものである。即ち、本発明は、簡便、且つ効率的にリチウムを回収可能なリチウム回収剤を提供することを目的の１つとする。
The present invention solves the above problems. That is, one of the objects of the present invention is to provide a lithium recovery agent that can simply and efficiently recover lithium.
発明者らは、上記課題を達成すべく鋭意検討した結果、以下の構成により上記課題を達成することができることを見出した。
As a result of intensive studies to achieve the above-mentioned problems, the inventors found that the above-mentioned problems can be achieved with the following configuration.
［１］ リチウムを含む原料液から前記リチウムを回収するためのリチウム回収剤であって、発電細菌と、リチウムインターカレーション材料と、を含むリチウム回収剤。
［２］ 前記発電細菌が鉄還元菌である、［１］に記載のリチウム回収剤。
［３］ 前記発電細菌が、シュワネラ属細菌、又はジオバクター属細菌である、［２］に記載のリチウム回収剤。
［４］ 前記リチウムインターカレーション材料が、第１遷移金属を含む化合物である、［１］～［３］のいずれかに記載のリチウム回収剤。
［５］ 前記第１遷移金属が、マンガン（Ｍｎ）、バナジウム（Ｖ）、チタン（Ｔｉ）、及び鉄（Ｆｅ）からなる群から選択される少なくとも１つである、［４］に記載のリチウム回収剤。
［６］ 前記リチウムインターカレーション材料が、スピネル型構造の二酸化マンガンである、［５］に記載のリチウム回収剤。
［７］ 前記リチウムインターカレーション材料が粒子である、［１］～［６］のいずれかに記載のリチウム回収剤。
［８］ 電子供与体を更に含む、［１］～［７］のいずれかに記載のリチウム回収剤。
［９］ 前記発電細菌がシュワネラ属細菌であり、且つ前記電子供与体が乳酸塩であるか、又は、前記発電細菌がジオバクター属細菌であり、且つ前記電子供与体が酢酸塩である、［８］に記載のリチウム回収剤。
［１０］ 電子メディエータを更に含む、［１］～［９］のいずれかに記載のリチウム回収剤。
［１１］ 前記電子メディエータがフラビン類である、［１０］に記載のリチウム回収剤。
［１２］ ［１］～［１１］のいずれかに記載の前記リチウム回収剤と、前記原料液とを接触させることを含むリチウム回収方法。
［１３］ 前記発電細菌の発生する電子が、前記リチウムインターカレーション材料に伝達される、［１２］に記載のリチウム回収方法。
［１４］ 前記原料液と、前記リチウム回収剤とを含む反応液を調製することと、前記反応液中に、前記リチウム回収剤及び前記リチウムを含有する沈殿物を生成させることと、前記反応液から、前記沈殿物を分離すること、を含む、［１２］または［１３］に記載のリチウム回収方法。
［１５］ 前記原料液は、カチオン交換膜を介して外部から導入されたリチウムイオンを含む、［１４］に記載のリチウム回収方法。
［１６］ リチウム回収システムであって、反応容器と、前記反応容器内に配置された、［１］～［１１］のいずれかに記載の前記リチウム回収剤と、を備え、前記反応容器内において、前記原料液と前記リチウム回収剤とが接触する、リチウム回収システム。
［１７］ 前記リチウム回収剤に電気を通電するための機構を有さない、［１６］に記載のリチウム回収システム。
［１８］ 前記反応容器は、リチウムイオンを前記原料液に前記反応容器の外部から導入するためのカチオン交換膜を備える、［１６］に記載のリチウム回収システム。
［１９］ ［１２］～［１５］のいずれかに記載のリチウム回収方法を含み、前記リチウムインターカレーション材料が二酸化マンガンである、リチウム含有マンガン酸化物の製造方法。
［２０］ ［１２］～［１５］のいずれかに記載のリチウム回収方法を含む、リチウムイオン電池の正極活物質の製造方法。 [1] A lithium recovery agent for recovering lithium from a raw material liquid containing lithium, which includes power-generating bacteria and a lithium intercalation material.
[2] The lithium recovery agent according to [1], wherein the power-generating bacteria are iron-reducing bacteria.
[3] The lithium recovery agent according to [2], wherein the power-generating bacteria is a Shewanella bacterium or a Geobacter bacterium.
[4] The lithium recovery agent according to any one of [1] to [3], wherein the lithium intercalation material is a compound containing a first transition metal.
[5] The lithium according to [4], wherein the first transition metal is at least one selected from the group consisting of manganese (Mn), vanadium (V), titanium (Ti), and iron (Fe). Collection agent.
[6] The lithium recovery agent according to [5], wherein the lithium intercalation material is manganese dioxide having a spinel structure.
[7] The lithium recovery agent according to any one of [1] to [6], wherein the lithium intercalation material is a particle.
[8] The lithium recovery agent according to any one of [1] to [7], further comprising an electron donor.
[9] The power-generating bacterium is a Shewanella bacterium, and the electron donor is lactate, or the power-generating bacterium is a Geobacter bacterium, and the electron donor is acetate. [8] The lithium recovery agent described in ].
[10] The lithium recovery agent according to any one of [1] to [9], further comprising an electron mediator.
[11] The lithium recovery agent according to [10], wherein the electron mediator is a flavin.
[12] A lithium recovery method comprising bringing the lithium recovery agent according to any one of [1] to [11] into contact with the raw material liquid.
[13] The lithium recovery method according to [12], wherein the electrons generated by the power-generating bacteria are transferred to the lithium intercalation material.
[14] preparing a reaction solution containing the raw material solution and the lithium recovery agent; generating a precipitate containing the lithium recovery agent and the lithium in the reaction solution; The lithium recovery method according to [12] or [13], which comprises separating the precipitate from.
[15] The lithium recovery method according to [14], wherein the raw material liquid contains lithium ions introduced from the outside via a cation exchange membrane.
[16] A lithium recovery system, comprising a reaction vessel and the lithium recovery agent according to any one of [1] to [11] disposed in the reaction vessel, wherein , a lithium recovery system in which the raw material liquid and the lithium recovery agent are in contact with each other;
[17] The lithium recovery system according to [16], which does not have a mechanism for applying electricity to the lithium recovery agent.
[18] The lithium recovery system according to [16], wherein the reaction vessel includes a cation exchange membrane for introducing lithium ions into the raw material liquid from outside the reaction vessel.
[19] A method for producing a lithium-containing manganese oxide, comprising the lithium recovery method according to any one of [12] to [15], wherein the lithium intercalation material is manganese dioxide.
[20] A method for producing a positive electrode active material for a lithium ion battery, comprising the lithium recovery method according to any one of [12] to [15].
［２］ 前記発電細菌が鉄還元菌である、［１］に記載のリチウム回収剤。
［３］ 前記発電細菌が、シュワネラ属細菌、又はジオバクター属細菌である、［２］に記載のリチウム回収剤。
［４］ 前記リチウムインターカレーション材料が、第１遷移金属を含む化合物である、［１］～［３］のいずれかに記載のリチウム回収剤。
［５］ 前記第１遷移金属が、マンガン（Ｍｎ）、バナジウム（Ｖ）、チタン（Ｔｉ）、及び鉄（Ｆｅ）からなる群から選択される少なくとも１つである、［４］に記載のリチウム回収剤。
［６］ 前記リチウムインターカレーション材料が、スピネル型構造の二酸化マンガンである、［５］に記載のリチウム回収剤。
［７］ 前記リチウムインターカレーション材料が粒子である、［１］～［６］のいずれかに記載のリチウム回収剤。
［８］ 電子供与体を更に含む、［１］～［７］のいずれかに記載のリチウム回収剤。
［９］ 前記発電細菌がシュワネラ属細菌であり、且つ前記電子供与体が乳酸塩であるか、又は、前記発電細菌がジオバクター属細菌であり、且つ前記電子供与体が酢酸塩である、［８］に記載のリチウム回収剤。
［１０］ 電子メディエータを更に含む、［１］～［９］のいずれかに記載のリチウム回収剤。
［１１］ 前記電子メディエータがフラビン類である、［１０］に記載のリチウム回収剤。
［１２］ ［１］～［１１］のいずれかに記載の前記リチウム回収剤と、前記原料液とを接触させることを含むリチウム回収方法。
［１３］ 前記発電細菌の発生する電子が、前記リチウムインターカレーション材料に伝達される、［１２］に記載のリチウム回収方法。
［１４］ 前記原料液と、前記リチウム回収剤とを含む反応液を調製することと、前記反応液中に、前記リチウム回収剤及び前記リチウムを含有する沈殿物を生成させることと、前記反応液から、前記沈殿物を分離すること、を含む、［１２］または［１３］に記載のリチウム回収方法。
［１５］ 前記原料液は、カチオン交換膜を介して外部から導入されたリチウムイオンを含む、［１４］に記載のリチウム回収方法。
［１６］ リチウム回収システムであって、反応容器と、前記反応容器内に配置された、［１］～［１１］のいずれかに記載の前記リチウム回収剤と、を備え、前記反応容器内において、前記原料液と前記リチウム回収剤とが接触する、リチウム回収システム。
［１７］ 前記リチウム回収剤に電気を通電するための機構を有さない、［１６］に記載のリチウム回収システム。
［１８］ 前記反応容器は、リチウムイオンを前記原料液に前記反応容器の外部から導入するためのカチオン交換膜を備える、［１６］に記載のリチウム回収システム。
［１９］ ［１２］～［１５］のいずれかに記載のリチウム回収方法を含み、前記リチウムインターカレーション材料が二酸化マンガンである、リチウム含有マンガン酸化物の製造方法。
［２０］ ［１２］～［１５］のいずれかに記載のリチウム回収方法を含む、リチウムイオン電池の正極活物質の製造方法。 [1] A lithium recovery agent for recovering lithium from a raw material liquid containing lithium, which includes power-generating bacteria and a lithium intercalation material.
[2] The lithium recovery agent according to [1], wherein the power-generating bacteria are iron-reducing bacteria.
[3] The lithium recovery agent according to [2], wherein the power-generating bacteria is a Shewanella bacterium or a Geobacter bacterium.
[4] The lithium recovery agent according to any one of [1] to [3], wherein the lithium intercalation material is a compound containing a first transition metal.
[5] The lithium according to [4], wherein the first transition metal is at least one selected from the group consisting of manganese (Mn), vanadium (V), titanium (Ti), and iron (Fe). Collection agent.
[6] The lithium recovery agent according to [5], wherein the lithium intercalation material is manganese dioxide having a spinel structure.
[7] The lithium recovery agent according to any one of [1] to [6], wherein the lithium intercalation material is a particle.
[8] The lithium recovery agent according to any one of [1] to [7], further comprising an electron donor.
[9] The power-generating bacterium is a Shewanella bacterium, and the electron donor is lactate, or the power-generating bacterium is a Geobacter bacterium, and the electron donor is acetate. [8] The lithium recovery agent described in ].
[10] The lithium recovery agent according to any one of [1] to [9], further comprising an electron mediator.
[11] The lithium recovery agent according to [10], wherein the electron mediator is a flavin.
[12] A lithium recovery method comprising bringing the lithium recovery agent according to any one of [1] to [11] into contact with the raw material liquid.
[13] The lithium recovery method according to [12], wherein the electrons generated by the power-generating bacteria are transferred to the lithium intercalation material.
[14] preparing a reaction solution containing the raw material solution and the lithium recovery agent; generating a precipitate containing the lithium recovery agent and the lithium in the reaction solution; The lithium recovery method according to [12] or [13], which comprises separating the precipitate from.
[15] The lithium recovery method according to [14], wherein the raw material liquid contains lithium ions introduced from the outside via a cation exchange membrane.
[16] A lithium recovery system, comprising a reaction vessel and the lithium recovery agent according to any one of [1] to [11] disposed in the reaction vessel, wherein , a lithium recovery system in which the raw material liquid and the lithium recovery agent are in contact with each other;
[17] The lithium recovery system according to [16], which does not have a mechanism for applying electricity to the lithium recovery agent.
[18] The lithium recovery system according to [16], wherein the reaction vessel includes a cation exchange membrane for introducing lithium ions into the raw material liquid from outside the reaction vessel.
[19] A method for producing a lithium-containing manganese oxide, comprising the lithium recovery method according to any one of [12] to [15], wherein the lithium intercalation material is manganese dioxide.
[20] A method for producing a positive electrode active material for a lithium ion battery, comprising the lithium recovery method according to any one of [12] to [15].
本発明は、簡便、且つ効率的にリチウムを回収可能なリチウム回収剤を提供する。
The present invention provides a lithium recovery agent that can simply and efficiently recover lithium.
以下、本発明について詳細に説明する。
以下に記載する構成要件の説明は、本発明の代表的な実施形態に基づいてなされることがあるが、本発明はそのような実施形態に制限されるものではない。なお、本明細書において、「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。 The present invention will be explained in detail below.
Although the description of the constituent elements described below may be made based on typical embodiments of the present invention, the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as the lower limit and upper limit.
以下に記載する構成要件の説明は、本発明の代表的な実施形態に基づいてなされることがあるが、本発明はそのような実施形態に制限されるものではない。なお、本明細書において、「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。 The present invention will be explained in detail below.
Although the description of the constituent elements described below may be made based on typical embodiments of the present invention, the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as the lower limit and upper limit.
［リチウム回収剤］
本実施形態のリチウム回収剤は、主に、発電細菌と、リチウムインターカレーション材料とを含む。本実施形態のリチウム回収剤は、リチウムを含む原料液に接触して、原料液中のリチウムを回収する。 [Lithium recovery agent]
The lithium recovery agent of this embodiment mainly includes power-generating bacteria and a lithium intercalation material. The lithium recovery agent of this embodiment comes into contact with a raw material liquid containing lithium and recovers lithium in the raw material liquid.
本実施形態のリチウム回収剤は、主に、発電細菌と、リチウムインターカレーション材料とを含む。本実施形態のリチウム回収剤は、リチウムを含む原料液に接触して、原料液中のリチウムを回収する。 [Lithium recovery agent]
The lithium recovery agent of this embodiment mainly includes power-generating bacteria and a lithium intercalation material. The lithium recovery agent of this embodiment comes into contact with a raw material liquid containing lithium and recovers lithium in the raw material liquid.
＜発電細菌＞
本明細書において、「発電細菌（電流発生菌）」とは、菌体内での電子供与体（有機物）の分解（代謝）によって発生した電子を菌体外の電子受容体（本実施形態では、リチウムインターカレーション材料）に伝達する能力、すなわち、細胞外電子移動（ＥＥＴ：Ｅｘｔｒａｃｅｌｌｕｌａｒ Ｅｌｅｃｔｒｏｎ Ｔｒａｎｓｐｏｒｔ）を行う能力（細胞外電子伝達能）を有する菌をいう。 <Power-generating bacteria>
In this specification, "power-generating bacteria (current-generating bacteria)" refers to electrons generated by decomposition (metabolism) of electron donors (organic substances) within the bacterial body to electron acceptors outside the bacterial body (in this embodiment, lithium intercalation material), that is, the ability to perform extracellular electron transport (EET).
本明細書において、「発電細菌（電流発生菌）」とは、菌体内での電子供与体（有機物）の分解（代謝）によって発生した電子を菌体外の電子受容体（本実施形態では、リチウムインターカレーション材料）に伝達する能力、すなわち、細胞外電子移動（ＥＥＴ：Ｅｘｔｒａｃｅｌｌｕｌａｒ Ｅｌｅｃｔｒｏｎ Ｔｒａｎｓｐｏｒｔ）を行う能力（細胞外電子伝達能）を有する菌をいう。 <Power-generating bacteria>
In this specification, "power-generating bacteria (current-generating bacteria)" refers to electrons generated by decomposition (metabolism) of electron donors (organic substances) within the bacterial body to electron acceptors outside the bacterial body (in this embodiment, lithium intercalation material), that is, the ability to perform extracellular electron transport (EET).
電流発生菌としては、例えば、鉄還元菌が挙げられる。鉄還元菌としては、具体的には、シュワネラ（Ｓｈｅｗａｎｅｌｌａ）属細菌、ジオバクター（Ｇｅｏｂａｃｔｅｒ）属細菌等が挙げられる。これらの発電細菌は、病原性細菌ではないため安全であり、また、増殖が速いため当初の投入量が少ない場合でも、十分な効果を得られる点で好ましい。シュワネラ属細菌の種としては、シュワネラ・オネイデンシス（Ｓ．ｏｎｅｉｄｅｎｓｉｓ）、シュワネラ・ロイヒカ（Ｓ．ｌｏｉｈｉｃａ）、シュワネラ・プトレファシエンス（Ｓ．ｐｕｔｒｅｆａｃｉｅｎｓ）、シュワネラ・アルガ（Ｓ．ａｌｇａｅ）等が挙げられる。ジオバクター属細菌の種としては、ジオバクター・サルフレドゥセンス（Ｇ．ｓｕｌｆｕｒｒｅｄｕｃｅｎｓ）、ジオバクター・メタリレドゥセンス（Ｇ．ｍｅｔａｌｌｉｒｅｄｕｃｅｎｓ）等が挙げられる。発電細菌は、既知のものであってもよく、未知のものであってもよい。これらの発電細菌は、本実施形態の効果を奏する範囲において、１種類を単独で用いてもよいし、２種類以上を混合して用いてもよい。
Examples of current-generating bacteria include iron-reducing bacteria. Specific examples of iron-reducing bacteria include bacteria of the genus Shewanella and bacteria of the genus Geobacter. These power-generating bacteria are safe because they are not pathogenic bacteria, and because they multiply rapidly, sufficient effects can be obtained even when the initial input amount is small, which is preferable. Species of Shewanella bacteria include S. oneidensis, S. loihica, S. putrefaciens, S. algae, etc. . Species of Geobacter bacteria include Geobacter sulfurreducens, Geobacter metallireducens, and the like. The power-generating bacteria may be known or unknown. These power-generating bacteria may be used alone or in a mixture of two or more types, within the range where the effects of this embodiment are achieved.
＜リチウムインターカレーション材料＞
本願明細書において、「リチウムインターカレーション材料」とは、リチウムイオン（ゲスト）がインターカレーション可能な材料（ホスト、母体）を意味する。インターカレーションとは、分子、分子集団、又は結晶（本願明細書では、リチウムインターカレーション材料）の空隙に、他の元素（本願明細書では、リチウムイオン）が侵入する可逆的な化学反応である。 <Lithium intercalation material>
As used herein, the term "lithium intercalation material" refers to a material (host, matrix) in which lithium ions (guest) can be intercalated. Intercalation is a reversible chemical reaction in which another element (herein, lithium ions) invades the voids of molecules, molecular groups, or crystals (herein, lithium intercalation material). be.
本願明細書において、「リチウムインターカレーション材料」とは、リチウムイオン（ゲスト）がインターカレーション可能な材料（ホスト、母体）を意味する。インターカレーションとは、分子、分子集団、又は結晶（本願明細書では、リチウムインターカレーション材料）の空隙に、他の元素（本願明細書では、リチウムイオン）が侵入する可逆的な化学反応である。 <Lithium intercalation material>
As used herein, the term "lithium intercalation material" refers to a material (host, matrix) in which lithium ions (guest) can be intercalated. Intercalation is a reversible chemical reaction in which another element (herein, lithium ions) invades the voids of molecules, molecular groups, or crystals (herein, lithium intercalation material). be.
リチウムインターカレーション材料の種類（組成、結晶構造、形状等）は、特に限定されず、本実施形態の効果を奏する範囲内において、適宜選択してよい。例えば、リチウムインターカレーション材料は、第１遷移金属を含む化合物であってもよく、第１遷移金属としては、マンガン（Ｍｎ）、バナジウム（Ｖ）、チタン（Ｔｉ）、及び鉄（Ｆｅ）等が挙げあれる。具体的な化合物としては、例えば、Ｍｎ３Ｏ４、Ｍｎ２Ｏ３、ＭｎＯ２（二酸化マンガン）、ＭｎＯ３、Ｍｎ２Ｏ７等の酸化マンガン、Ｆｅ３Ｏ４、Ｆｅ２Ｏ３等の酸化鉄、Ｖ２Ｏ５、ＶＯ２等の酸化バナジウム、ＴｉＯ２等の酸化チタン、更に、ＴｉＳ２、ＦｅＰＯ４等が挙げらる。また、リチウムインターカレーション材料の結晶構造としては、例えば、層状岩塩型、スピネル型、オリビン型等が挙げられる。リチウムインターカレーション材料としては、二酸化マンガン、特に、スピネル型構造の二酸化マンガン（λ型ＭｎＯ２）が、リチウム吸着の選択性が高いため好ましい。尚、リチウムインターカレーション材料は、本実施形態の効果を奏する範囲において、１種類を単独で用いてもよいし、２種類以上を混合して用いてもよい。
The type of lithium intercalation material (composition, crystal structure, shape, etc.) is not particularly limited, and may be appropriately selected within the range that provides the effects of this embodiment. For example, the lithium intercalation material may be a compound containing a first transition metal, such as manganese (Mn), vanadium (V), titanium (Ti), and iron (Fe). There are many things that can be mentioned. Specific compounds include, for example, manganese oxides such as Mn 3 O 4 , Mn 2 O 3 , MnO 2 (manganese dioxide ), MnO 3 and Mn 2 O 7 ; Examples include iron, vanadium oxides such as V 2 O 5 and VO 2 , titanium oxides such as TiO 2 , and furthermore TiS 2 and FePO 4 . Furthermore, examples of the crystal structure of the lithium intercalation material include a layered rock salt type, a spinel type, and an olivine type. As the lithium intercalation material, manganese dioxide, particularly manganese dioxide having a spinel structure (λ-type MnO 2 ), is preferable because it has high selectivity in lithium adsorption. Note that the lithium intercalation material may be used alone or in a mixture of two or more types within a range that produces the effects of this embodiment.
リチウムインターカレーション材料は、リチウム回収効率を高める観点から、粉体（粒子）であることが好ましい。粒子の平均粒子径は、特に限定されず、例えば、５ｎｍ～５００μｍ、５０ｎｍ～９０００ｎｍ、または１００ｎｍ～３００ｎｍとしてもよい。尚、「平均粒径」は、例えば、電子顕微鏡観察によってランダムに１００個の粒子の粒径を測定して平均すること（算術平均）によって求めることができる。
The lithium intercalation material is preferably a powder (particles) from the viewpoint of increasing lithium recovery efficiency. The average particle diameter of the particles is not particularly limited, and may be, for example, 5 nm to 500 μm, 50 nm to 9000 nm, or 100 nm to 300 nm. Note that the "average particle size" can be determined, for example, by randomly measuring the particle sizes of 100 particles using an electron microscope and averaging them (arithmetic mean).
＜その他の成分＞
本実施形態のリチウム回収剤は、発電細菌と、リチウムインターカレーション材料のみから形成されてもよいし、本実施形態の効果を奏する限りにおいて、他の成分を含有してもよい。 <Other ingredients>
The lithium recovery agent of this embodiment may be formed only from power-generating bacteria and a lithium intercalation material, or may contain other components as long as the effects of this embodiment are achieved.
本実施形態のリチウム回収剤は、発電細菌と、リチウムインターカレーション材料のみから形成されてもよいし、本実施形態の効果を奏する限りにおいて、他の成分を含有してもよい。 <Other ingredients>
The lithium recovery agent of this embodiment may be formed only from power-generating bacteria and a lithium intercalation material, or may contain other components as long as the effects of this embodiment are achieved.
例えば、リチウム回収剤は、更に、発電細菌が分解可能な電子供与体（電子ドナー）を含有してもよい。上述のように、発電細菌は有機物（電子供与体）の分解（代謝）によって電子を発生するが、原料液が海水やその他の環境サンプルである場合、原料液中に既に、電子供与体となる有機物が含まれている場合がある。このような場合であっても、リチウム回収剤が電子供与体を更に含有することにより、リチウムの回収効率を向上させることができる。
For example, the lithium recovery agent may further contain an electron donor that can be decomposed by power-generating bacteria. As mentioned above, power-generating bacteria generate electrons by decomposing (metabolizing) organic matter (electron donors), but when the raw material solution is seawater or other environmental samples, electron donors are already present in the raw material solution. May contain organic matter. Even in such a case, the lithium recovery efficiency can be improved by further containing an electron donor in the lithium recovery agent.
電子供与体（電子ドナー）としては、リチウム回収剤に含有される発電細菌、及び／又は、原料液に含まれる細菌等によって分解（代謝）され、発電細菌に電子を供与可能な物質であれば、その種類、及び、状態等は特に限定されない。電子供与体は、固体状、液体状、気体状、及び、これらの混合物等であってよく、リチウム回収方法の具体的な形態に応じて任意に選択され得る。
例えば、海水を原料液とする場合（又はここから原料液を調製する場合）、元々のリチウム（イオン）の含有量は少なく、一例として０．２ｐｐｍ程度となる。 The electron donor may be a substance that can be decomposed (metabolized) by the power-generating bacteria contained in the lithium recovery agent and/or the bacteria contained in the raw material solution and donate electrons to the power-generating bacteria. , its type, state, etc. are not particularly limited. The electron donor may be solid, liquid, gaseous, or a mixture thereof, and may be arbitrarily selected depending on the specific form of the lithium recovery method.
For example, when seawater is used as a raw material liquid (or when a raw material liquid is prepared from it), the original lithium (ion) content is small, for example, about 0.2 ppm.
例えば、海水を原料液とする場合（又はここから原料液を調製する場合）、元々のリチウム（イオン）の含有量は少なく、一例として０．２ｐｐｍ程度となる。 The electron donor may be a substance that can be decomposed (metabolized) by the power-generating bacteria contained in the lithium recovery agent and/or the bacteria contained in the raw material solution and donate electrons to the power-generating bacteria. , its type, state, etc. are not particularly limited. The electron donor may be solid, liquid, gaseous, or a mixture thereof, and may be arbitrarily selected depending on the specific form of the lithium recovery method.
For example, when seawater is used as a raw material liquid (or when a raw material liquid is prepared from it), the original lithium (ion) content is small, for example, about 0.2 ppm.
このような場合、原料液（反応液）に対して、液体（液剤）として電子供与体を供給するよりも、固体状、又は、ガス状の電子供与体を供給する方が、回収Liあたりの使用量を削減でき経済的により優位であることがある。
具体的には、リチウム回収剤の近傍に、電子供与体となり得る固形物やガスを用いると、海水と微生物やリチウム回収剤と分離が可能になり、且つ局所的（かつ連続的に）リチウム回収をより効率的に行うことができる。 In such cases, it is better to supply a solid or gaseous electron donor to the raw material solution (reaction solution) than to supply the electron donor as a liquid (liquid agent). It may be economically advantageous because the amount used can be reduced.
Specifically, if a solid substance or gas that can serve as an electron donor is used near the lithium recovery agent, it becomes possible to separate the seawater from microorganisms and the lithium recovery agent, and to recover lithium locally (and continuously). can be done more efficiently.
具体的には、リチウム回収剤の近傍に、電子供与体となり得る固形物やガスを用いると、海水と微生物やリチウム回収剤と分離が可能になり、且つ局所的（かつ連続的に）リチウム回収をより効率的に行うことができる。 In such cases, it is better to supply a solid or gaseous electron donor to the raw material solution (reaction solution) than to supply the electron donor as a liquid (liquid agent). It may be economically advantageous because the amount used can be reduced.
Specifically, if a solid substance or gas that can serve as an electron donor is used near the lithium recovery agent, it becomes possible to separate the seawater from microorganisms and the lithium recovery agent, and to recover lithium locally (and continuously). can be done more efficiently.
このような固形物の材質としては、例えば、マグネシウム、及び、鉄等の金属、並びに、セルロース、及び、ポリ乳酸等の有機物等が挙げられる。その形態は特に限定されず、粒子状であっても、塊状であってもよい。粒子状である場合、より効率的に反応が進行しやすく、塊状である場合、リチウム回収剤の近傍に、より固定しやすく好ましい。
Examples of the material of such a solid substance include metals such as magnesium and iron, and organic substances such as cellulose and polylactic acid. Its form is not particularly limited and may be particulate or lumpy. When it is in the form of particles, the reaction tends to proceed more efficiently, and when it is in the form of lumps, it is easier to fix in the vicinity of the lithium recovery agent, which is preferable.
また、気体状の電子供与体を用いる場合、リチウム回収剤の近傍に当該気体を供給すればよい。一例として、上述の二次冷却系であれば、リチウム回収剤の近傍に電極を設置し、冷却水の電気分解により水素を発生させればよい。気体状の電子供与体の例としては、水素が挙げられる。
なお、上述の固体状の電子供与体のうち、金属（鉄、及び、マグネシウム等）は、原料液（反応液）中で水素を発生し得るため、それ自身が電子供与体となり得るとともに、系中に水素を放出することで、間接的な電子供与体ともなり得る。 Furthermore, when using a gaseous electron donor, the gas may be supplied near the lithium recovery agent. As an example, in the case of the above-mentioned secondary cooling system, an electrode may be installed near the lithium recovery agent, and hydrogen may be generated by electrolysis of cooling water. An example of a gaseous electron donor is hydrogen.
Note that among the solid electron donors mentioned above, metals (iron, magnesium, etc.) can generate hydrogen in the raw material solution (reaction solution), so they themselves can act as electron donors, and they also contribute to the system. It can also become an indirect electron donor by releasing hydrogen into the molecule.
なお、上述の固体状の電子供与体のうち、金属（鉄、及び、マグネシウム等）は、原料液（反応液）中で水素を発生し得るため、それ自身が電子供与体となり得るとともに、系中に水素を放出することで、間接的な電子供与体ともなり得る。 Furthermore, when using a gaseous electron donor, the gas may be supplied near the lithium recovery agent. As an example, in the case of the above-mentioned secondary cooling system, an electrode may be installed near the lithium recovery agent, and hydrogen may be generated by electrolysis of cooling water. An example of a gaseous electron donor is hydrogen.
Note that among the solid electron donors mentioned above, metals (iron, magnesium, etc.) can generate hydrogen in the raw material solution (reaction solution), so they themselves can act as electron donors, and they also contribute to the system. It can also become an indirect electron donor by releasing hydrogen into the molecule.
電子供与体のうち、有機物としては、他にも例えば、乳酸ナトリウム等の乳酸塩、酢酸ナトリウム等の酢酸塩等が挙げられる。電流発生菌（発電細菌）の種類に基づいて、発電効率が高まる電子供与体を適宜選択することが好ましい。例えば、発電細菌がシュワネラ属細菌である場合は、電子供与体は乳酸塩が好ましく、発電細菌がジオバクター属細菌である場合は、電子供与体は酢酸塩が好ましい。また、電子供与体は、本実施形態の効果を奏する範囲において、１種類を単独で用いてもよいし、２種類以上を混合して用いてもよい。
上記の有機物は、固体として提供されてもよいし、液体（溶液）として提供されてもよいし、これらの混合物として提供されてもよい。また、上記有機物を溶解した溶液によって膨潤した高分子ゲルを電子供与体として使用することもできる。膨潤した高分子ゲルは、上記有機物を反応液中に徐放するため、より効率的に反応を進行させることができる。 Among the electron donors, other examples of organic substances include lactate salts such as sodium lactate, acetate salts such as sodium acetate, and the like. It is preferable to appropriately select an electron donor that increases power generation efficiency based on the type of current-generating bacteria (power-generating bacteria). For example, when the power-generating bacterium is a Shewanella bacterium, the electron donor is preferably lactate, and when the power-generating bacterium is a Geobacter bacterium, the electron donor is preferably acetate. In addition, one type of electron donor may be used alone, or two or more types may be used in combination as long as the effects of this embodiment are achieved.
The above organic substance may be provided as a solid, a liquid (solution), or a mixture thereof. Furthermore, a polymer gel swollen with a solution containing the above-mentioned organic substance can also be used as an electron donor. Since the swollen polymer gel releases the organic substance into the reaction solution in a sustained manner, the reaction can proceed more efficiently.
上記の有機物は、固体として提供されてもよいし、液体（溶液）として提供されてもよいし、これらの混合物として提供されてもよい。また、上記有機物を溶解した溶液によって膨潤した高分子ゲルを電子供与体として使用することもできる。膨潤した高分子ゲルは、上記有機物を反応液中に徐放するため、より効率的に反応を進行させることができる。 Among the electron donors, other examples of organic substances include lactate salts such as sodium lactate, acetate salts such as sodium acetate, and the like. It is preferable to appropriately select an electron donor that increases power generation efficiency based on the type of current-generating bacteria (power-generating bacteria). For example, when the power-generating bacterium is a Shewanella bacterium, the electron donor is preferably lactate, and when the power-generating bacterium is a Geobacter bacterium, the electron donor is preferably acetate. In addition, one type of electron donor may be used alone, or two or more types may be used in combination as long as the effects of this embodiment are achieved.
The above organic substance may be provided as a solid, a liquid (solution), or a mixture thereof. Furthermore, a polymer gel swollen with a solution containing the above-mentioned organic substance can also be used as an electron donor. Since the swollen polymer gel releases the organic substance into the reaction solution in a sustained manner, the reaction can proceed more efficiently.
また、例えば、リチウム回収剤は、更に、電子メディエータを含んでもよい。発電細菌が発生する電子は、細胞外膜に存在する電子伝達タンパク質を介して、菌体外の電子受容体（リチウムインターカレーション材料）に伝達される。電子メディエータは、電子伝達タンパク質を活性化し、リチウムインターカレーション材料への電子伝達を更に促進する。この結果、リチウム回収効率が向上し、例えば、回収時間（反応時間）を短縮できる。電子メディエータとしては、例えば、フラビン類、キノン類等が挙げられる。フラビン類は７，８‐ジメチルイソアロキサジンの１０位に置換基を持つ誘導体の総称であり、リボフラビン（ビタミンＢ２）、ＦＡＤ、ＦＭＮなどがある。キノン類は、二重結合を有し且つ六つの炭素原子を含有する環状ディケトン構造を備える芳香族有機化合物であり、例えば、ｐ－ベンゾキノン、o－キノン、アントラキノン等が挙げられる。これらの電子メディエータは、本実施形態の効果を奏する範囲において、１種類を単独で用いてもよいし、２種類以上を混合して用いてもよい。
Also, for example, the lithium recovery agent may further include an electron mediator. Electrons generated by power-generating bacteria are transferred to electron acceptors (lithium intercalation material) outside the bacterial cells via electron transfer proteins present in the extracellular membrane. The electron mediator activates electron transfer proteins to further facilitate electron transfer to the lithium intercalation material. As a result, lithium recovery efficiency is improved and, for example, recovery time (reaction time) can be shortened. Examples of electronic mediators include flavins and quinones. Flavins is a general term for derivatives of 7,8-dimethylisoalloxazine having a substituent at the 10th position, and includes riboflavin (vitamin B2), FAD, and FMN. Quinones are aromatic organic compounds having a cyclic diketone structure having a double bond and containing six carbon atoms, such as p-benzoquinone, o-quinone, anthraquinone, and the like. These electronic mediators may be used singly or in combination of two or more types, within the range where the effects of this embodiment are achieved.
また、リチウム回収剤は、更に、ホウ酸、リン酸、炭酸等各種無機塩緩衝液、水、生理食塩水、細胞培養地等を含む液体（以下、「液体成分」と記載する）を含有してもよい。例えば、リチウム回収剤が細胞培養地を含む場合、リチウム回収剤内で発電細菌を培養して数を増やすことができる。液体成分は、本実施形態の効果を奏する範囲において、１種類を単独で用いてもよいし、２種類以上を混合して用いてもよい。
In addition, the lithium recovery agent further contains a liquid (hereinafter referred to as "liquid component") including various inorganic salt buffers such as boric acid, phosphoric acid, and carbonic acid, water, physiological saline, and cell culture medium. It's okay. For example, if the lithium recovery agent includes a cell culture medium, power-generating bacteria can be cultured and expanded within the lithium recovery agent. One type of liquid component may be used alone, or two or more types may be used as a mixture within a range where the effects of this embodiment are achieved.
本実施形態のリチウム回収剤は、発電細菌、及び上述の液体成分を含む第１剤と、リチウムインターカレーション材料を含む第２剤とから構成されてもよい。第２剤は、リチウムインターカレーション材料のみから構成されもよいし、更に、上述の液体成分を含んでもよい。また、リチウム回収剤が電子供与体、電子メディエータ等を含有する場合、これらの成分は、第１剤、及び／又は第２剤に含有されてもよいし、別個のその他の薬剤（例えば、第３剤、及び／又は第４剤）としてもよい。尚、第１剤、第２剤、その他の薬剤は、別々の容器に保管可能であり、リチウム回収剤の使用時に、第１剤、第２剤、及びその他の薬剤と、原料液とを混合してもよい。
The lithium recovery agent of this embodiment may be composed of a first agent containing power-generating bacteria and the above-mentioned liquid component, and a second agent containing a lithium intercalation material. The second agent may be composed only of the lithium intercalation material, or may further include the above-mentioned liquid component. Further, when the lithium recovery agent contains an electron donor, an electron mediator, etc., these components may be contained in the first agent and/or the second agent, or may be contained in a separate other agent (for example, the second agent). It may be used as a third agent and/or a fourth agent). The first agent, second agent, and other agents can be stored in separate containers, and when using the lithium recovery agent, the first agent, second agent, and other agents are mixed with the raw material liquid. You may.
尚、本実施形態のリチウム回収剤における各成分の比率（割合）は特に限定されず、本実施形態の効果を奏する範囲において適宜、調整が可能である。
Note that the ratio (proportion) of each component in the lithium recovery agent of this embodiment is not particularly limited, and can be adjusted as appropriate within a range that provides the effects of this embodiment.
＜原料液＞
原料液は、リチウムを含有する液体であれば特に限定されず、本実施形態の効果を奏する範囲で適宜選択してよい。原料液としては、例えば、海水、塩湖かん水、地熱水、リチウムイオン電池等をリサイクルすることによって得られたリチウム含有水溶液、鉱山排水、工業廃水等が挙げられるが、リチウム回収剤に含まれる発電細菌に対して細胞毒とならないものが好ましい。海水は、リチウム濃度は０．０２５ｍＭ程度と低いが、大量且つ容易に入手できるため、重要なリチウム供給源である。本実施形態のリチウム回収剤は、リチウム濃度が低い原料液からも効率的にリチウムを回収できるため、海水は本実施形態の原料液に適している。 <Raw material liquid>
The raw material liquid is not particularly limited as long as it is a liquid containing lithium, and may be appropriately selected as long as it achieves the effects of this embodiment. Examples of raw material liquids include seawater, salt lake brine, geothermal water, lithium-containing aqueous solutions obtained by recycling lithium ion batteries, mine drainage, industrial wastewater, etc., but lithium recovery agents include Preferably, it is not cytotoxic to power-generating bacteria. Although seawater has a low lithium concentration of about 0.025 mM, seawater is an important lithium supply source because it is easily available in large quantities. Since the lithium recovery agent of this embodiment can efficiently recover lithium even from a raw material liquid with a low lithium concentration, seawater is suitable for the raw material liquid of this embodiment.
原料液は、リチウムを含有する液体であれば特に限定されず、本実施形態の効果を奏する範囲で適宜選択してよい。原料液としては、例えば、海水、塩湖かん水、地熱水、リチウムイオン電池等をリサイクルすることによって得られたリチウム含有水溶液、鉱山排水、工業廃水等が挙げられるが、リチウム回収剤に含まれる発電細菌に対して細胞毒とならないものが好ましい。海水は、リチウム濃度は０．０２５ｍＭ程度と低いが、大量且つ容易に入手できるため、重要なリチウム供給源である。本実施形態のリチウム回収剤は、リチウム濃度が低い原料液からも効率的にリチウムを回収できるため、海水は本実施形態の原料液に適している。 <Raw material liquid>
The raw material liquid is not particularly limited as long as it is a liquid containing lithium, and may be appropriately selected as long as it achieves the effects of this embodiment. Examples of raw material liquids include seawater, salt lake brine, geothermal water, lithium-containing aqueous solutions obtained by recycling lithium ion batteries, mine drainage, industrial wastewater, etc., but lithium recovery agents include Preferably, it is not cytotoxic to power-generating bacteria. Although seawater has a low lithium concentration of about 0.025 mM, seawater is an important lithium supply source because it is easily available in large quantities. Since the lithium recovery agent of this embodiment can efficiently recover lithium even from a raw material liquid with a low lithium concentration, seawater is suitable for the raw material liquid of this embodiment.
原料液のリチウム濃度は特に限定されず、本実施形態のリチウム回収剤は、例えば、０．０１ｍＭ～５０ｍＭの広範囲のリチウム濃度を有する原料液に対応可能であり、例えば、０．０１ｍＭ～１ｍＭの低リチウム濃度の原料液からも効率よくリチウムを回収できる。また、原料液は、電子供与体（電子ドナー）となり得る、発電細菌が分解可能な有機物を含有していてもよい。原料液が十分な量の電子供与体（有機物）を含有する場合、リチウム回収剤は電子供与体を含有する必要がないか、又は電子供与体の含有量を少なくできる。
The lithium concentration of the raw material solution is not particularly limited, and the lithium recovery agent of this embodiment can be used with raw material solutions having a wide range of lithium concentrations, for example, from 0.01 mM to 50 mM, and for example, from 0.01 mM to 1 mM. Lithium can be efficiently recovered even from raw material liquids with low lithium concentration. Further, the raw material liquid may contain an organic substance that can serve as an electron donor and can be decomposed by power-generating bacteria. When the raw material liquid contains a sufficient amount of an electron donor (organic substance), the lithium recovery agent does not need to contain an electron donor, or the content of the electron donor can be reduced.
＜リチウム回収のメカニズム＞
図１に、リチウムを含む原料液２００と接触しているリチウム回収剤１００の模式図を示す。まず、リチウム回収剤１００に含まれる発電細菌１０内で、電子供与体２０の分解（代謝）が行われ、電子ｅ－が発生する。発生した電子ｅ－は、発電細菌１０の細胞外膜に存在する電子伝達タンパク質３０を介して、菌体外の電子受容体（リチウムインターカレーション材料）４０に伝達される。これにより、原料液中のリチウムイオンがリチウムインターカレーション材料４０に取り込まれる、電気化学的なインターカレーションが促進され、原料液２００からリチウム（リチウムイオンＬｉ＋）が回収される。発明者らは、発電細菌により、リチウムのインターカレーションが顕著に促進されることを初めて見出し、本発明に至った。更に、本実施形態のリチウム回収剤は、リチウム回収時（反応時）に、発電細菌由来の成分によりリチウムインターカレーション材料の粒子が凝集体を形成する傾向がある。これにより、粒子間の導電性及び接着性が向上し、リチウム回収効率が更に高まると推測される。 <Mechanism of lithium recovery>
FIG. 1 shows a schematic diagram of alithium recovery agent 100 in contact with a raw material liquid 200 containing lithium. First, the electron donor 20 is decomposed (metabolized) within the power generating bacteria 10 contained in the lithium recovery agent 100, and electrons e.sup.- are generated. The generated electron e - is transferred to an electron acceptor (lithium intercalation material) 40 outside the bacterial body via an electron transfer protein 30 present in the outer cell membrane of the power-generating bacterium 10. This promotes electrochemical intercalation in which lithium ions in the raw material liquid are incorporated into the lithium intercalation material 40, and lithium (lithium ions Li + ) is recovered from the raw material liquid 200. The inventors discovered for the first time that lithium intercalation is significantly promoted by power-generating bacteria, leading to the present invention. Furthermore, in the lithium recovery agent of this embodiment, particles of the lithium intercalation material tend to form aggregates due to components derived from power-generating bacteria during lithium recovery (during reaction). It is presumed that this improves the conductivity and adhesion between particles and further increases the lithium recovery efficiency.
図１に、リチウムを含む原料液２００と接触しているリチウム回収剤１００の模式図を示す。まず、リチウム回収剤１００に含まれる発電細菌１０内で、電子供与体２０の分解（代謝）が行われ、電子ｅ－が発生する。発生した電子ｅ－は、発電細菌１０の細胞外膜に存在する電子伝達タンパク質３０を介して、菌体外の電子受容体（リチウムインターカレーション材料）４０に伝達される。これにより、原料液中のリチウムイオンがリチウムインターカレーション材料４０に取り込まれる、電気化学的なインターカレーションが促進され、原料液２００からリチウム（リチウムイオンＬｉ＋）が回収される。発明者らは、発電細菌により、リチウムのインターカレーションが顕著に促進されることを初めて見出し、本発明に至った。更に、本実施形態のリチウム回収剤は、リチウム回収時（反応時）に、発電細菌由来の成分によりリチウムインターカレーション材料の粒子が凝集体を形成する傾向がある。これにより、粒子間の導電性及び接着性が向上し、リチウム回収効率が更に高まると推測される。 <Mechanism of lithium recovery>
FIG. 1 shows a schematic diagram of a
本実施形態のリチウム回収剤は、リチウムを含む原料液と接触する（例えば、原料液中にリチウム回収剤を分散させる）という簡便な方法により、効率的にリチウムを回収できる。このため、非特許文献１～３に開示される従来の方法と比較して、塗料調製（混練）工程や塗布工程が不要であり、その工程に必要な装備（ニーダー、コーター、乾燥機等）も不要である。更に、電極、配線、ポテンショ・ガルバノスタット等の電気化学装置も不要である。また、本実施形態では、リチウムを取り込んだリチウムインターカレーション材料は、発電細菌由来の成分により凝集体を形成して沈殿するため、応液からの分離も容易である。このように、本実施形態のリチウム回収剤は、時間的、金銭的に優れており、必要とする工程及び設備が少ないため環境負荷も低く、量産設備への適用性が高い。
The lithium recovery agent of this embodiment can efficiently recover lithium by a simple method of contacting with a raw material liquid containing lithium (for example, dispersing the lithium recovery agent in the raw material liquid). Therefore, compared to the conventional methods disclosed in Non-Patent Documents 1 to 3, there is no need for a paint preparation (kneading) process or coating process, and the equipment necessary for that process (kneader, coater, dryer, etc.) is also unnecessary. Further, electrochemical devices such as electrodes, wiring, and potentio-galvanostat are not required. Furthermore, in the present embodiment, the lithium intercalation material incorporating lithium forms aggregates and precipitates with components derived from power-generating bacteria, and therefore can be easily separated from the reaction solution. As described above, the lithium recovery agent of the present embodiment is advantageous in terms of time and money, requires fewer steps and equipment, has a lower environmental impact, and is highly applicable to mass production equipment.
例えば、リチウムインターカレーション材料として酸化マンガンを用いた場合、発電細菌から伝達される電子により、酸化マンガンの少なくとも一部は還元される。例えば、リチウム回収剤中の二酸化マンガン（例えば、ＭｎＯ２）は、リチウムイオンを回収することにより、酸化マンガンリチウム挿入化合物（例えば、ＬｉｘＭｎ２Ｏ４、ｘ＝０．４～２．０）となる。酸化マンガンリチウム挿入化合物におけるマンガン（Ｍｎ）の平均酸化数は、特に限定されないが、例えば、＋３～＋４である。尚、酸化マンガンに取り込まれる、リチウムイオンは還元されない。
For example, when manganese oxide is used as a lithium intercalation material, at least a portion of the manganese oxide is reduced by electrons transferred from power-generating bacteria. For example, manganese dioxide (e.g., MnO 2 ) in a lithium recovery agent can be converted into a manganese oxide lithium insertion compound (e.g., Li x Mn 2 O 4 , x=0.4-2.0) by recovering lithium ions. becomes. The average oxidation number of manganese (Mn) in the manganese oxide lithium insertion compound is not particularly limited, but is, for example, +3 to +4. Note that lithium ions incorporated into manganese oxide are not reduced.
本実施形態のリチウム回収剤は、原料液中の金属イオンを直接還元して回収する回収剤とは、上述のように、金属回収メカニズムが大きく異なる。原料液中の金属イオンを直接還元して回収する場合、原料液中に含まれる、目的とする金属以外の金属も同時に還元して回収してしまう虞がある。これに対して本実施形態のリチウム回収剤では、発電細菌が供給する電子はリチウムインターカレーション材料に伝達され、リチウムインターカレーション材料に原料液中のリチウムイオンが選択的に取り込まれる。したがって、原料液中にリチウムイオン以外の金属イオンが含有されている場合でも、本実施形態のリチウム回収剤は、選択的にリチウムイオンを回収できる。
As described above, the lithium recovery agent of this embodiment has a metal recovery mechanism that is significantly different from a recovery agent that directly reduces and recovers metal ions in the raw material liquid. When metal ions in the raw material liquid are directly reduced and recovered, there is a risk that metals other than the target metal contained in the raw material liquid may also be reduced and recovered at the same time. In contrast, in the lithium recovery agent of the present embodiment, electrons supplied by the power-generating bacteria are transferred to the lithium intercalation material, and lithium ions in the raw material liquid are selectively taken into the lithium intercalation material. Therefore, even when metal ions other than lithium ions are contained in the raw material liquid, the lithium recovery agent of this embodiment can selectively recover lithium ions.
尚、以上説明したメカニズムは推測であり、本発明の範囲に何ら影響を与えるものではない。
Note that the mechanism explained above is speculation and does not affect the scope of the present invention in any way.
［リチウム回収システム］
図１に示す、リチウム回収システム１０００について説明する。リチウム回収システム１０００は、反応容器３００と、反応容器３００内に配置された本実施形態のリチウム回収剤１００とを備え、反応容器３００内において、原料液２００とリチウム回収剤１００とが接触する。これにより、原料液中のリチウムイオンがリチウムインターカレーション材料４０に取り込まれ（インターカレーション）、原料液２００からリチウム（リチウムイオンＬｉ＋）が回収される。 [Lithium recovery system]
Thelithium recovery system 1000 shown in FIG. 1 will be described. The lithium recovery system 1000 includes a reaction vessel 300 and the lithium recovery agent 100 of this embodiment placed in the reaction vessel 300, and the raw material liquid 200 and the lithium recovery agent 100 come into contact within the reaction vessel 300. As a result, lithium ions in the raw material liquid are taken into the lithium intercalation material 40 (intercalation), and lithium (lithium ions Li + ) is recovered from the raw material liquid 200.
図１に示す、リチウム回収システム１０００について説明する。リチウム回収システム１０００は、反応容器３００と、反応容器３００内に配置された本実施形態のリチウム回収剤１００とを備え、反応容器３００内において、原料液２００とリチウム回収剤１００とが接触する。これにより、原料液中のリチウムイオンがリチウムインターカレーション材料４０に取り込まれ（インターカレーション）、原料液２００からリチウム（リチウムイオンＬｉ＋）が回収される。 [Lithium recovery system]
The
リチウム回収システム１０００は、リチウム回収剤１００に通電するための通電機構（例えば、電源、配線、電極等）を有する必要がない。リチウム回収剤１００に含有される発電細菌１０により、リチウム回収反応に必要十分な電子をリチウムインターカレーション材料に供給できるためである。通電機構を有さないため、リチウム回収システム１０００は、低コストで作製及び運転が可能であり、環境負荷も低い。
The lithium recovery system 1000 does not need to have an energizing mechanism (for example, a power source, wiring, electrodes, etc.) for energizing the lithium recovery agent 100. This is because the power-generating bacteria 10 contained in the lithium recovery agent 100 can supply sufficient electrons to the lithium intercalation material for the lithium recovery reaction. Since it does not have a current supply mechanism, the lithium recovery system 1000 can be manufactured and operated at low cost, and has a low environmental load.
［リチウム回収システムの他の実施例］
図８は、リチウム回収システムの他の実施例の概念図である。リチウム回収システム１１００は、反応容器３００と、反応容器３００内に配置されたリチウム回収剤１００と、を備え、更に、反応容器３００には、リチウムイオン１３０を原料液２００に外部から導入するためのカチオン交換膜４００を備える。 [Other examples of lithium recovery system]
FIG. 8 is a conceptual diagram of another embodiment of the lithium recovery system. Thelithium recovery system 1100 includes a reaction vessel 300 and a lithium recovery agent 100 disposed in the reaction vessel 300, and further includes a reaction vessel 300 for introducing lithium ions 130 into the raw material liquid 200 from the outside. A cation exchange membrane 400 is provided.
図８は、リチウム回収システムの他の実施例の概念図である。リチウム回収システム１１００は、反応容器３００と、反応容器３００内に配置されたリチウム回収剤１００と、を備え、更に、反応容器３００には、リチウムイオン１３０を原料液２００に外部から導入するためのカチオン交換膜４００を備える。 [Other examples of lithium recovery system]
FIG. 8 is a conceptual diagram of another embodiment of the lithium recovery system. The
カチオン交換膜４００は、発電プラントの二次冷却水の配管１１０と反応容器３００とを連通する配管に配置され、外部の配管１１０中の冷却水２１０に含まれるリチウムイオン１３０を、反応容器３００側へと導入する。
なお、本実施例では、反応容器３００は、発電プラントの二次冷却水の配管１１０の中途に設置されているが、本実施例のリチウム回収システムの設置場所は上記に限定されない。例えば、リチウムイオンを含有する水が収容されたより大きな容器（例えば、何らかの水処理槽等）、及び、湖沼・海洋等に、反応容器３００ごと浸漬されてもよい。
本実施例のリチウム回収システムは、反応容器３００内をリチウム回収に適した状態（例えば、嫌気状態）に保ち易く、かつ、低濃度のリチウムイオンからもより効率よくリチウム回収を行うことができる。 Thecation exchange membrane 400 is disposed in a pipe that communicates the secondary cooling water pipe 110 of the power plant with the reaction vessel 300, and transfers lithium ions 130 contained in the cooling water 210 in the external pipe 110 to the reaction vessel 300 side. to be introduced.
In addition, in this example, thereaction vessel 300 is installed in the middle of the secondary cooling water piping 110 of the power plant, but the installation location of the lithium recovery system of this example is not limited to the above. For example, the reaction container 300 may be immersed in a larger container containing water containing lithium ions (for example, some type of water treatment tank), a lake, the ocean, or the like.
The lithium recovery system of this embodiment can easily maintain the inside of thereaction vessel 300 in a state suitable for lithium recovery (for example, an anaerobic state), and can more efficiently recover lithium even from low-concentration lithium ions.
なお、本実施例では、反応容器３００は、発電プラントの二次冷却水の配管１１０の中途に設置されているが、本実施例のリチウム回収システムの設置場所は上記に限定されない。例えば、リチウムイオンを含有する水が収容されたより大きな容器（例えば、何らかの水処理槽等）、及び、湖沼・海洋等に、反応容器３００ごと浸漬されてもよい。
本実施例のリチウム回収システムは、反応容器３００内をリチウム回収に適した状態（例えば、嫌気状態）に保ち易く、かつ、低濃度のリチウムイオンからもより効率よくリチウム回収を行うことができる。 The
In addition, in this example, the
The lithium recovery system of this embodiment can easily maintain the inside of the
［リチウム回収方法］
本実施形態のリチウム回収剤を用いたリチウム回収方法について説明する。リチウム回収方法は、上述したリチウム回収システム１０００（図１参照）を用いて実施してもよい。リチウム回収方法は、リチウム回収剤と、原料液とを接触させる工程（図２のステップＳ１）を含む。以下に、リチウム回収方法の一例について、図２のフローチャートに従って説明する。 [Lithium recovery method]
A lithium recovery method using the lithium recovery agent of this embodiment will be described. The lithium recovery method may be implemented using the lithium recovery system 1000 (see FIG. 1) described above. The lithium recovery method includes a step of bringing a lithium recovery agent into contact with a raw material liquid (step S1 in FIG. 2). An example of a lithium recovery method will be described below according to the flowchart of FIG. 2.
本実施形態のリチウム回収剤を用いたリチウム回収方法について説明する。リチウム回収方法は、上述したリチウム回収システム１０００（図１参照）を用いて実施してもよい。リチウム回収方法は、リチウム回収剤と、原料液とを接触させる工程（図２のステップＳ１）を含む。以下に、リチウム回収方法の一例について、図２のフローチャートに従って説明する。 [Lithium recovery method]
A lithium recovery method using the lithium recovery agent of this embodiment will be described. The lithium recovery method may be implemented using the lithium recovery system 1000 (see FIG. 1) described above. The lithium recovery method includes a step of bringing a lithium recovery agent into contact with a raw material liquid (step S1 in FIG. 2). An example of a lithium recovery method will be described below according to the flowchart of FIG. 2.
まず、原料液と、リチウム回収剤とを含む反応液を調製する（図２のステップＳ１）。これにより、リチウム回収剤と、原料液とが接触する。
First, a reaction solution containing a raw material solution and a lithium recovery agent is prepared (step S1 in FIG. 2). This brings the lithium recovery agent into contact with the raw material liquid.
反応液は、原料液と、リチウム回収剤とのみから構成されてもよいし、本実施形態の効果を奏する範囲において、その他の成分を含んでもよい。その他の成分としては、例えば、ホウ酸、リン酸、炭酸等各種無機塩緩衝液、水、生理食塩水、細胞培養地等を含む液体（上述した「液体成分」）が挙げられる。
The reaction liquid may be composed only of the raw material liquid and the lithium recovery agent, or may contain other components as long as the effects of this embodiment are achieved. Examples of other components include liquids (the above-mentioned "liquid components") including various inorganic salt buffers such as boric acid, phosphoric acid, and carbonic acid, water, physiological saline, and cell culture media.
反応液中の各成分の含有量（濃度）は、特に限定されず、本実施形態の効果を奏する範囲において適宜、調整が可能である。例えば、反応液の初期濃度は、以下の範囲としてもよい。発電細菌（ＯＤ値）：０．００１～１、リチウムインターカレーション材料：０．００１～１０ｇ／Ｌ、電子供与体：０～１００ｍＭ、電子メディエータ：０～０.１ｍＭ、リチウムイオン：０．０１～１００ｍＭ。
The content (concentration) of each component in the reaction solution is not particularly limited, and can be adjusted as appropriate within the range that provides the effects of this embodiment. For example, the initial concentration of the reaction solution may be in the following range. Power-generating bacteria (OD value): 0.001-1, lithium intercalation material: 0.001-10g/L, electron donor: 0-100mM, electron mediator: 0-0.1mM, lithium ion: 0.01 ~100mM.
反応液のｐＨは、例えば、５～８、又は、６～８としてよい。反応液のｐＨを上記範囲内とすれば、発電細菌の活動が活発化し、結果としてリチウム回収効率が向上する。
The pH of the reaction solution may be, for example, 5 to 8 or 6 to 8. When the pH of the reaction solution is within the above range, the activity of the power-generating bacteria becomes active, and as a result, the lithium recovery efficiency improves.
反応液の調製方法は特に限定されず、例えば、原料液、リチウム回収剤、必要に応じてその他の成分を公知の方法により、均一に混合してよい。
例えば、より低濃度のリチウムイオンを含む溶液から（すなわち、外部から）、カチオン交換膜を介してリチウムイオンを原料液中に連続的に移動させ、反応液を調製してもよい。 The method for preparing the reaction liquid is not particularly limited, and for example, the raw material liquid, the lithium recovery agent, and other components as necessary may be uniformly mixed by a known method.
For example, the reaction solution may be prepared by continuously transferring lithium ions from a solution containing a lower concentration of lithium ions (ie, from the outside) into the raw material solution via a cation exchange membrane.
例えば、より低濃度のリチウムイオンを含む溶液から（すなわち、外部から）、カチオン交換膜を介してリチウムイオンを原料液中に連続的に移動させ、反応液を調製してもよい。 The method for preparing the reaction liquid is not particularly limited, and for example, the raw material liquid, the lithium recovery agent, and other components as necessary may be uniformly mixed by a known method.
For example, the reaction solution may be prepared by continuously transferring lithium ions from a solution containing a lower concentration of lithium ions (ie, from the outside) into the raw material solution via a cation exchange membrane.
次に、反応液中に沈殿物を生成させる（図２のステップＳ２）。反応液中では、原料液中のリチウムイオンが、リチウムインターカレーション材料に取り込まれる反応（インターカレーション）が生じる。この結果、リチウム回収剤と、リチウム回収剤に取り込まれたリチウムとを含有する沈殿物が生じ、原料液中のリチウムは沈殿物中に回収される。
Next, a precipitate is generated in the reaction solution (step S2 in FIG. 2). In the reaction solution, a reaction (intercalation) occurs in which lithium ions in the raw material solution are incorporated into the lithium intercalation material. As a result, a precipitate containing the lithium recovery agent and lithium incorporated into the lithium recovery agent is generated, and the lithium in the raw material liquid is recovered in the precipitate.
ここで、反応液を調製したとき（図２のステップＳ１）から、後述する反応液から沈殿物を分離するとき（図２のステップＳ３）までの時間を「反応時間」とする。反応時間は、本実施形態の効果を奏する範囲で適宜調整することができ、例えば、１０分～３日、又は１時間～３時間としてよい。反応時間を上記範囲内とすれば、インターカレーション反応が十分に進み、十分な量のリチウムを含有する沈殿物が得られる。反応中の反応液の温度（反応温度）は、例えば、４℃～４０℃、又は、２５℃～３０℃としてよい。反応温度を上記範囲内とすれば、発電細菌の活動が活発化し、結果としてリチウム回収効率が向上する。また、反応中（反応時間中）は、反応液を静置してもよいし、振とう、攪拌等してもよい。
Here, the time from when the reaction solution is prepared (step S1 in FIG. 2) to when the precipitate is separated from the reaction solution (step S3 in FIG. 2), which will be described later, is defined as "reaction time." The reaction time can be adjusted as appropriate within the range that produces the effects of this embodiment, and may be, for example, 10 minutes to 3 days, or 1 hour to 3 hours. If the reaction time is within the above range, the intercalation reaction will proceed sufficiently and a precipitate containing a sufficient amount of lithium will be obtained. The temperature of the reaction solution during the reaction (reaction temperature) may be, for example, 4°C to 40°C or 25°C to 30°C. When the reaction temperature is within the above range, the activity of the power-generating bacteria becomes more active, resulting in improved lithium recovery efficiency. Further, during the reaction (during the reaction time), the reaction solution may be left standing, or may be shaken, stirred, etc.
次に、反応液から沈殿物を分離する（図２のステップＳ３）。分離方法は特に限定されず、濾過、デカンテーション等の汎用の方法を用いることができる。本実施形態では、発電細菌の作用により、リチウムインターカレーション材料は凝集して沈殿物（凝集体）を形成し、更に、その沈殿物（凝集体）は、反応容器の底に密着し易い。このため、沈殿物と上澄み液との分離が容易である。
Next, the precipitate is separated from the reaction solution (step S3 in FIG. 2). The separation method is not particularly limited, and general-purpose methods such as filtration and decantation can be used. In this embodiment, the lithium intercalation material aggregates to form a precipitate (aggregate) due to the action of the power-generating bacteria, and further, the precipitate (aggregate) tends to adhere to the bottom of the reaction vessel. Therefore, it is easy to separate the precipitate and the supernatant liquid.
以上説明したように、本実施形態のリチウム回収方法では、リチウム回収剤と、原料液とを接触させるという簡便な方法により、効率的にリチウムを回収できる。従来の方法（例えば、非特許文献１～３）のように、リチウム回収剤１００に通電する工程は不要である。本実施形態のリチウム回収方法は、時間的、金銭的に優れており、必要とする工程及び設備が少ないため環境負荷も低く、大量生産への適用性が高い。
As explained above, in the lithium recovery method of this embodiment, lithium can be efficiently recovered by a simple method of bringing the lithium recovery agent into contact with the raw material liquid. Unlike conventional methods (for example, non-patent documents 1 to 3), the step of energizing the lithium recovery agent 100 is not necessary. The lithium recovery method of this embodiment is superior in terms of time and money, requires fewer steps and equipment, has less environmental impact, and is highly applicable to mass production.
［リチウム回収方法の応用］
本実施形態のリチウム回収方法では、原料液中のリチウム（リチウムイオン）を回収した結果、リチウムイオンを含有するリチウムインターカレーション材料が生成する。例えば、リチウムインターカレーション材料として酸化マンガンを用いた場合、原料液中のリチウムイオンは、リチウム含有マンガン酸化物（酸化マンガンリチウム挿入化合物）として回収される。即ち、本実施形態のリチウム回収方法は、リチウム含有マンガン酸化物の製造方法に応用できる。本製造方法では、リチウム源（原料液）として海水等を用いることが可能であり、また、発電細菌を用いることで、低コスト且つ簡便な方法により、リチウム含有マンガン酸化物を製造できる。製造されるリチウム含有マンガン酸化物としては、例えば、ＬｉｘＭｎ２Ｏ４（ｘ＝０．４～２．０）が挙げられる。マンガン（Ｍｎ）の平均酸化数は、特に限定されないが、例えば、＋３～＋４である。 [Application of lithium recovery method]
In the lithium recovery method of this embodiment, as a result of recovering lithium (lithium ions) in the raw material liquid, a lithium intercalation material containing lithium ions is generated. For example, when manganese oxide is used as the lithium intercalation material, lithium ions in the raw material liquid are recovered as a lithium-containing manganese oxide (manganese oxide lithium insertion compound). That is, the lithium recovery method of this embodiment can be applied to a method for producing lithium-containing manganese oxide. In this production method, it is possible to use seawater or the like as a lithium source (raw material liquid), and by using power-generating bacteria, lithium-containing manganese oxide can be produced by a low-cost and simple method. Examples of the lithium-containing manganese oxide produced include Li x Mn 2 O 4 (x=0.4 to 2.0). The average oxidation number of manganese (Mn) is not particularly limited, but is, for example, +3 to +4.
本実施形態のリチウム回収方法では、原料液中のリチウム（リチウムイオン）を回収した結果、リチウムイオンを含有するリチウムインターカレーション材料が生成する。例えば、リチウムインターカレーション材料として酸化マンガンを用いた場合、原料液中のリチウムイオンは、リチウム含有マンガン酸化物（酸化マンガンリチウム挿入化合物）として回収される。即ち、本実施形態のリチウム回収方法は、リチウム含有マンガン酸化物の製造方法に応用できる。本製造方法では、リチウム源（原料液）として海水等を用いることが可能であり、また、発電細菌を用いることで、低コスト且つ簡便な方法により、リチウム含有マンガン酸化物を製造できる。製造されるリチウム含有マンガン酸化物としては、例えば、ＬｉｘＭｎ２Ｏ４（ｘ＝０．４～２．０）が挙げられる。マンガン（Ｍｎ）の平均酸化数は、特に限定されないが、例えば、＋３～＋４である。 [Application of lithium recovery method]
In the lithium recovery method of this embodiment, as a result of recovering lithium (lithium ions) in the raw material liquid, a lithium intercalation material containing lithium ions is generated. For example, when manganese oxide is used as the lithium intercalation material, lithium ions in the raw material liquid are recovered as a lithium-containing manganese oxide (manganese oxide lithium insertion compound). That is, the lithium recovery method of this embodiment can be applied to a method for producing lithium-containing manganese oxide. In this production method, it is possible to use seawater or the like as a lithium source (raw material liquid), and by using power-generating bacteria, lithium-containing manganese oxide can be produced by a low-cost and simple method. Examples of the lithium-containing manganese oxide produced include Li x Mn 2 O 4 (x=0.4 to 2.0). The average oxidation number of manganese (Mn) is not particularly limited, but is, for example, +3 to +4.
また、リチウムイオンを含有するリチウムインターカレーション材料（例えば、上述のリチウム含有マンガン酸化物）は、リチウムイオン電池の正極活物質として利用可能である。即ち、本実施形態のリチウム回収方法は、リチウムイオン電池の正極活物質の製造方法に応用できる。本製造方法では、リチウム源（原料液）として海水等を用いることが可能であり、また、発電細菌を用いることで、低コスト且つ簡便な方法で、リチウムイオン電池の正極活物質を生産可能である。中でも、リチウム含有マンガン酸化物は、Ｃｏと比較してＭｎが安価で埋蔵量も多く将来の安定供給が見込める点で、リチウムイオン電池の正極材料として注目されている。
Furthermore, a lithium intercalation material containing lithium ions (for example, the above-mentioned lithium-containing manganese oxide) can be used as a positive electrode active material of a lithium ion battery. That is, the lithium recovery method of this embodiment can be applied to a method for manufacturing a positive electrode active material of a lithium ion battery. In this production method, it is possible to use seawater etc. as a lithium source (raw material liquid), and by using power-generating bacteria, it is possible to produce positive electrode active materials for lithium-ion batteries in a low-cost and simple manner. be. Among these, lithium-containing manganese oxide is attracting attention as a positive electrode material for lithium ion batteries because Mn is cheaper than Co, has large reserves, and can be expected to have a stable supply in the future.
以下に実施例に基づいて本発明を更に詳細に説明する。以下の実施例に示す材料、使用量、割合、処理内容、処理手順等は、本発明の趣旨を逸脱しない限り適宜変更することができる。したがって、本発明の範囲は以下に示す実施例により限定的に解釈されるべきものではない。
The present invention will be described in more detail below based on Examples. The materials, usage amounts, proportions, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the Examples shown below.
［実験１］
下記成分を含有するリチウム回収剤を用いて、原料液（リチウム水溶液）からリチウムを回収した。尚、λ－ＭｎＯ２粒子は、スピネル型構造のＬｉＭｎ２Ｏ４を酸処理することにより作製した。
＜リチウム回収剤成分＞
発電細菌：シュワネラ菌
電子供与体：乳酸ナトリウム
インターカレーション材料：スピネル型構造の二酸化マンガン（λ－ＭｎＯ２粒子、平均粒子径：１００～３００ｎｍ） [Experiment 1]
Lithium was recovered from the raw material liquid (lithium aqueous solution) using a lithium recovery agent containing the following components. Note that the λ-MnO 2 particles were produced by acid-treating LiMn 2 O 4 having a spinel structure.
<Lithium recovery agent component>
Power-generating bacteria: Schwanella bacteria Electron donor: Sodium lactate Intercalation material: Manganese dioxide with spinel structure (λ-MnO 2 particles, average particle size: 100-300 nm)
下記成分を含有するリチウム回収剤を用いて、原料液（リチウム水溶液）からリチウムを回収した。尚、λ－ＭｎＯ２粒子は、スピネル型構造のＬｉＭｎ２Ｏ４を酸処理することにより作製した。
＜リチウム回収剤成分＞
発電細菌：シュワネラ菌
電子供与体：乳酸ナトリウム
インターカレーション材料：スピネル型構造の二酸化マンガン（λ－ＭｎＯ２粒子、平均粒子径：１００～３００ｎｍ） [Experiment 1]
Lithium was recovered from the raw material liquid (lithium aqueous solution) using a lithium recovery agent containing the following components. Note that the λ-MnO 2 particles were produced by acid-treating LiMn 2 O 4 having a spinel structure.
<Lithium recovery agent component>
Power-generating bacteria: Schwanella bacteria Electron donor: Sodium lactate Intercalation material: Manganese dioxide with spinel structure (λ-MnO 2 particles, average particle size: 100-300 nm)
（１）反応液の調製
まず、リン酸緩衝液に、塩化リチウムと乳酸ナトリウムとを溶解させた水溶液を調製した（塩化リチウム濃度：５０ｍＭ、乳酸ナトリウム濃度：５０ｍＭ）。調製した溶液５０ｍＬに０．０５ｇの酸化マンガン粒子を混合した。次に、窒素のバブリングにより溶液中の溶存酸素を取り除き、シュワネラ菌を導入して容器を密閉し、反応液を得た。シュワネラ菌は、５０ｍＬの反応液に分散した際に光学濃度（ＯＤ値）が０．３になるように調整した量を加えた。 (1) Preparation of reaction solution First, an aqueous solution in which lithium chloride and sodium lactate were dissolved in a phosphate buffer was prepared (lithium chloride concentration: 50 mM, sodium lactate concentration: 50 mM). 0.05 g of manganese oxide particles were mixed into 50 mL of the prepared solution. Next, dissolved oxygen in the solution was removed by nitrogen bubbling, Shewanella bacteria were introduced, and the container was sealed to obtain a reaction solution. The Schwanella bacteria were added in an amount adjusted so that the optical density (OD value) would be 0.3 when dispersed in 50 mL of the reaction solution.
まず、リン酸緩衝液に、塩化リチウムと乳酸ナトリウムとを溶解させた水溶液を調製した（塩化リチウム濃度：５０ｍＭ、乳酸ナトリウム濃度：５０ｍＭ）。調製した溶液５０ｍＬに０．０５ｇの酸化マンガン粒子を混合した。次に、窒素のバブリングにより溶液中の溶存酸素を取り除き、シュワネラ菌を導入して容器を密閉し、反応液を得た。シュワネラ菌は、５０ｍＬの反応液に分散した際に光学濃度（ＯＤ値）が０．３になるように調整した量を加えた。 (1) Preparation of reaction solution First, an aqueous solution in which lithium chloride and sodium lactate were dissolved in a phosphate buffer was prepared (lithium chloride concentration: 50 mM, sodium lactate concentration: 50 mM). 0.05 g of manganese oxide particles were mixed into 50 mL of the prepared solution. Next, dissolved oxygen in the solution was removed by nitrogen bubbling, Shewanella bacteria were introduced, and the container was sealed to obtain a reaction solution. The Schwanella bacteria were added in an amount adjusted so that the optical density (OD value) would be 0.3 when dispersed in 50 mL of the reaction solution.
（２）沈殿物の生成
３０℃に設定した恒温器の中で、振とう機に先程の容器を設置し、２４時間、１６０ｒｐｍ程度の回転速度で振とうした。この間に、酸化マンガン粒子とシュワネラ菌から成るシート状の凝集体（沈殿物）が容器の底に形成することが確認された。 (2) Formation of precipitate In a constant temperature chamber set at 30° C., the container was placed in a shaker and shaken at a rotational speed of about 160 rpm for 24 hours. During this time, it was confirmed that sheet-like aggregates (precipitates) consisting of manganese oxide particles and Shewanella bacteria were formed at the bottom of the container.
３０℃に設定した恒温器の中で、振とう機に先程の容器を設置し、２４時間、１６０ｒｐｍ程度の回転速度で振とうした。この間に、酸化マンガン粒子とシュワネラ菌から成るシート状の凝集体（沈殿物）が容器の底に形成することが確認された。 (2) Formation of precipitate In a constant temperature chamber set at 30° C., the container was placed in a shaker and shaken at a rotational speed of about 160 rpm for 24 hours. During this time, it was confirmed that sheet-like aggregates (precipitates) consisting of manganese oxide particles and Shewanella bacteria were formed at the bottom of the container.
（３）沈殿物の分離
２４時間経過後、容器を開封して上澄み液を除去すること（デカンテーション）により、沈殿物を回収した。得られた沈殿物を、界面活性剤を用いて洗浄することで微生物由来の成分を除去し、その後、乾燥機で水分を除去することで粉末を得た。 (3) Separation of precipitate After 24 hours, the container was opened and the supernatant liquid was removed (decantation) to collect the precipitate. The obtained precipitate was washed with a surfactant to remove microbial-derived components, and then water was removed using a dryer to obtain a powder.
２４時間経過後、容器を開封して上澄み液を除去すること（デカンテーション）により、沈殿物を回収した。得られた沈殿物を、界面活性剤を用いて洗浄することで微生物由来の成分を除去し、その後、乾燥機で水分を除去することで粉末を得た。 (3) Separation of precipitate After 24 hours, the container was opened and the supernatant liquid was removed (decantation) to collect the precipitate. The obtained precipitate was washed with a surfactant to remove microbial-derived components, and then water was removed using a dryer to obtain a powder.
＜評価＞
（１）結晶構造評価
実験１で得られた粉末のＸ線回折（ＸＲＤ）測定を行った。結果を図３に「反応後」として示す。比較のため、λ‐ＭｎＯ２のプロファイルも「反応前（λ‐ＭｎＯ２）」として図３に示す。反応後も反応前（λ‐ＭｎＯ２）と同様のピークが観測されるものの、反応後の全てのピークは反応前（λ‐ＭｎＯ２）と比較して低角側にシフトしていた。これは、反応後もスピネル型構造の対称性を保ちつつ、格子サイズが増大していることを示す。このような格子サイズの増大は、リチウムなどの陽イオンが電気化学的に結晶構造内に挿入されたこと（インターカレーション）により、マンガンイオンの価数が低下したことを示唆する。反応後のプロファイルのピーク位置は、参考として図３下部に示しているＬｉＭｎ２Ｏ４(マンガンの平均価数は＋３．５）と一致する。 <Evaluation>
(1) Crystal structure evaluation The powder obtained inExperiment 1 was measured by X-ray diffraction (XRD). The results are shown in FIG. 3 as "after reaction". For comparison, the profile of λ-MnO 2 is also shown in FIG. 3 as “before reaction (λ-MnO 2 )”. Although the same peaks as before the reaction (λ-MnO 2 ) were observed after the reaction, all the peaks after the reaction were shifted to the lower angle side compared to before the reaction (λ-MnO 2 ). This indicates that the lattice size increases while maintaining the symmetry of the spinel structure after the reaction. Such an increase in the lattice size suggests that the valence of the manganese ion has decreased due to electrochemical insertion (intercalation) of cations such as lithium into the crystal structure. The peak position of the profile after the reaction coincides with LiMn 2 O 4 (average valence of manganese is +3.5) shown at the bottom of FIG. 3 for reference.
（１）結晶構造評価
実験１で得られた粉末のＸ線回折（ＸＲＤ）測定を行った。結果を図３に「反応後」として示す。比較のため、λ‐ＭｎＯ２のプロファイルも「反応前（λ‐ＭｎＯ２）」として図３に示す。反応後も反応前（λ‐ＭｎＯ２）と同様のピークが観測されるものの、反応後の全てのピークは反応前（λ‐ＭｎＯ２）と比較して低角側にシフトしていた。これは、反応後もスピネル型構造の対称性を保ちつつ、格子サイズが増大していることを示す。このような格子サイズの増大は、リチウムなどの陽イオンが電気化学的に結晶構造内に挿入されたこと（インターカレーション）により、マンガンイオンの価数が低下したことを示唆する。反応後のプロファイルのピーク位置は、参考として図３下部に示しているＬｉＭｎ２Ｏ４(マンガンの平均価数は＋３．５）と一致する。 <Evaluation>
(1) Crystal structure evaluation The powder obtained in
（２）組成分析
誘導結合プラズマ（ＩＣＰ）発光分析により、実験１で得られた粉末の組成分析を行った。その結果、粉末（反応後の試料）中のマンガンとリチウムのモル比は、Ｍｎ：Ｌｉ＝２：０．６程度であり、プロトンの共挿入等の影響により、ＬｉＭｎ２Ｏ４の場合（Ｍｎ：Ｌｉ＝２：１）よりもリチウム量が少ないものの、十分な量のリチウムが回収されていることが示された。 (2) Composition analysis The composition of the powder obtained inExperiment 1 was analyzed by inductively coupled plasma (ICP) emission spectrometry. As a result, the molar ratio of manganese and lithium in the powder (sample after reaction) was approximately Mn:Li=2:0.6, and due to the influence of co-insertion of protons, it was found that in the case of LiMn 2 O 4 (Mn :Li=2:1), but it was shown that a sufficient amount of lithium was recovered.
誘導結合プラズマ（ＩＣＰ）発光分析により、実験１で得られた粉末の組成分析を行った。その結果、粉末（反応後の試料）中のマンガンとリチウムのモル比は、Ｍｎ：Ｌｉ＝２：０．６程度であり、プロトンの共挿入等の影響により、ＬｉＭｎ２Ｏ４の場合（Ｍｎ：Ｌｉ＝２：１）よりもリチウム量が少ないものの、十分な量のリチウムが回収されていることが示された。 (2) Composition analysis The composition of the powder obtained in
（３）走査型電子顕微鏡（ＳＥＭ）観察、及びエネルギー分散型Ｘ線分析（ＥＤＳ）
実験１でデカンテーションにより回収した、洗浄前の凝集体（沈殿物）に対して、微生物の脱水乾燥処理を施した後に、走査電子顕微鏡（ＳＥＭ）を用いて形態観察を行った。結果を図４に示す。凝集体の大半は酸化マンガン粒子から成り、図４中の矢印は、シュワネラ菌の形が明確に観測された箇所を示している。ＳＥＭ観察と同時に、エネルギー分散型Ｘ線分析（ＥＤＳ）による、マンガンと炭素のマッピングを行った。この結果からも、矢印位置に示されるシュワネラ菌を確認している。また、シュワネラ菌の周囲にも炭素が検出された。これから、微生物由来の成分が凝集体を覆うことで、酸化マンガン粒子間の導電性や接着性が担保されると推測される。 (3) Scanning electron microscopy (SEM) observation and energy dispersive X-ray analysis (EDS)
The unwashed aggregates (precipitates) collected by decantation inExperiment 1 were subjected to microbial dehydration and drying treatment, and then their morphology was observed using a scanning electron microscope (SEM). The results are shown in Figure 4. Most of the aggregates are composed of manganese oxide particles, and the arrows in FIG. 4 indicate locations where the shape of Shewanella bacteria was clearly observed. At the same time as the SEM observation, manganese and carbon were mapped by energy dispersive X-ray analysis (EDS). This result also confirms the Shewanella bacterium indicated by the arrow. Carbon was also detected around the Shewanella bacteria. From this, it is inferred that the microbial-derived components cover the aggregates, thereby ensuring conductivity and adhesion between the manganese oxide particles.
実験１でデカンテーションにより回収した、洗浄前の凝集体（沈殿物）に対して、微生物の脱水乾燥処理を施した後に、走査電子顕微鏡（ＳＥＭ）を用いて形態観察を行った。結果を図４に示す。凝集体の大半は酸化マンガン粒子から成り、図４中の矢印は、シュワネラ菌の形が明確に観測された箇所を示している。ＳＥＭ観察と同時に、エネルギー分散型Ｘ線分析（ＥＤＳ）による、マンガンと炭素のマッピングを行った。この結果からも、矢印位置に示されるシュワネラ菌を確認している。また、シュワネラ菌の周囲にも炭素が検出された。これから、微生物由来の成分が凝集体を覆うことで、酸化マンガン粒子間の導電性や接着性が担保されると推測される。 (3) Scanning electron microscopy (SEM) observation and energy dispersive X-ray analysis (EDS)
The unwashed aggregates (precipitates) collected by decantation in
［実験２］
シュワネラ菌を用いなかった（容器に導入しなかった）以外は、実験１と同様の方法により、最終生成物である粉末を得た。 [Experiment 2]
A powder, the final product, was obtained in the same manner as inExperiment 1, except that the Schwanella bacterium was not used (it was not introduced into the container).
シュワネラ菌を用いなかった（容器に導入しなかった）以外は、実験１と同様の方法により、最終生成物である粉末を得た。 [Experiment 2]
A powder, the final product, was obtained in the same manner as in
＜結晶構造評価＞
実験１と同様の方法により、実験２で得られた粉末のＸ線回折（ＸＲＤ）測定を行った。結果を図５に「反応後」として示す。比較のため、λ‐ＭｎＯ２のプロファイルも「反応前（λ‐ＭｎＯ２）」として図５に示す。実験１の結果（図３）とは対照的に、反応後のプロファイルではピーク強度が大きく減衰し、またブロードなピーク形状を示した。これは、酸化マンガンの結晶性が低下したことを示唆しており、結晶の骨格構造を維持したまま生じるリチウム挿入反応以外の副反応が生じている可能性がある。また、ピーク位置も、参考として図５下部に示しているＬｉＭｎ２Ｏ４のピーク位置とは異なり、反応の進行が不完全であることを示唆している。実験１（図３）と実験２（図５）とのＸＲＤ結果の比較から、シュワネラ菌の添加が電気化学的なリチウム挿入反応（インターカレーション）を顕著に促進することが確認できた。 <Crystal structure evaluation>
The powder obtained inExperiment 2 was subjected to X-ray diffraction (XRD) measurement using the same method as in Experiment 1. The results are shown in FIG. 5 as "after reaction". For comparison, the profile of λ-MnO 2 is also shown in FIG. 5 as “before reaction (λ-MnO 2 )”. In contrast to the results of Experiment 1 (FIG. 3), the profile after the reaction showed a large attenuation of peak intensity and a broad peak shape. This suggests that the crystallinity of manganese oxide has decreased, and there is a possibility that side reactions other than the lithium insertion reaction that occur while maintaining the crystal skeleton structure are occurring. Moreover, the peak position is also different from the peak position of LiMn 2 O 4 shown at the bottom of FIG. 5 as a reference, suggesting that the reaction progresses incompletely. From a comparison of the XRD results of Experiment 1 (FIG. 3) and Experiment 2 (FIG. 5), it was confirmed that the addition of Shewanella bacteria significantly promoted the electrochemical lithium insertion reaction (intercalation).
実験１と同様の方法により、実験２で得られた粉末のＸ線回折（ＸＲＤ）測定を行った。結果を図５に「反応後」として示す。比較のため、λ‐ＭｎＯ２のプロファイルも「反応前（λ‐ＭｎＯ２）」として図５に示す。実験１の結果（図３）とは対照的に、反応後のプロファイルではピーク強度が大きく減衰し、またブロードなピーク形状を示した。これは、酸化マンガンの結晶性が低下したことを示唆しており、結晶の骨格構造を維持したまま生じるリチウム挿入反応以外の副反応が生じている可能性がある。また、ピーク位置も、参考として図５下部に示しているＬｉＭｎ２Ｏ４のピーク位置とは異なり、反応の進行が不完全であることを示唆している。実験１（図３）と実験２（図５）とのＸＲＤ結果の比較から、シュワネラ菌の添加が電気化学的なリチウム挿入反応（インターカレーション）を顕著に促進することが確認できた。 <Crystal structure evaluation>
The powder obtained in
［実験３－１～３－６］
実用上は、リチウム濃度の低い環境中からのリチウム回収が求められるため、実験３－１～３－６では、低リチウム濃度の水溶液からのリチウム回収特性について評価した。 [Experiments 3-1 to 3-6]
In practice, it is required to recover lithium from an environment with a low lithium concentration, so in Experiments 3-1 to 3-6, the characteristics of lithium recovery from an aqueous solution with a low lithium concentration were evaluated.
実用上は、リチウム濃度の低い環境中からのリチウム回収が求められるため、実験３－１～３－６では、低リチウム濃度の水溶液からのリチウム回収特性について評価した。 [Experiments 3-1 to 3-6]
In practice, it is required to recover lithium from an environment with a low lithium concentration, so in Experiments 3-1 to 3-6, the characteristics of lithium recovery from an aqueous solution with a low lithium concentration were evaluated.
実験３－１～３－６では、反応液中のリチウム濃度を、それぞれ、２０ｍＭ、１０ｍＭ、５ｍＭ、２ｍＭ、１ｍＭ、及び０．５ｍＭとした。それ以外は、実験１と同様の方法により、最終生成物である粉末を得た。
In Experiments 3-1 to 3-6, the lithium concentration in the reaction solution was 20 mM, 10 mM, 5 mM, 2 mM, 1 mM, and 0.5 mM, respectively. Other than that, the final product, a powder, was obtained in the same manner as in Experiment 1.
＜結晶構造評価、及び組成分析＞
実験１と同様の方法により、実験３－１～３－６で得られた粉末のＸ線回折（ＸＲＤ）測定、及び組成分析を行った。Ｘ線回折（ＸＲＤ）測定結果を図６Ａ～図６Ｆに示す。また、比較のため、図６Ａ～図６Ｆに、λ‐ＭｎＯ２のピーク位置を「λ－ＭｎＯ２」と添字のある縦破線で示す。 <Crystal structure evaluation and composition analysis>
Using the same method as inExperiment 1, the powders obtained in Experiments 3-1 to 3-6 were subjected to X-ray diffraction (XRD) measurement and compositional analysis. The results of X-ray diffraction (XRD) measurements are shown in FIGS. 6A to 6F. Further, for comparison, the peak position of λ-MnO 2 is shown in FIGS. 6A to 6F by a vertical broken line with a subscript “λ-MnO 2 ”.
実験１と同様の方法により、実験３－１～３－６で得られた粉末のＸ線回折（ＸＲＤ）測定、及び組成分析を行った。Ｘ線回折（ＸＲＤ）測定結果を図６Ａ～図６Ｆに示す。また、比較のため、図６Ａ～図６Ｆに、λ‐ＭｎＯ２のピーク位置を「λ－ＭｎＯ２」と添字のある縦破線で示す。 <Crystal structure evaluation and composition analysis>
Using the same method as in
図６Ａ～図６Ｃに示すように、実験３－１～３－３（リチウム濃度：５～２０ｍＭ）では、各ピーク（添え字のない縦破線）は、ピーク強度を保ったまま、λ‐ＭｎＯ２のピーク位置に対して、明確に低角側へシフトしていた。これは、図３に示す実験１（リチウム濃度：５０ｍＭ）の結果と同様であり、リチウムイオンが電気化学的に酸化マンガン結晶構造内に挿入されたこと（インターカレーション）を示唆する。
As shown in Figures 6A to 6C, in Experiments 3-1 to 3-3 (lithium concentration: 5 to 20 mM), each peak (vertical dashed line without subscripts) was There was a clear shift to the lower angle side with respect to the peak position of No. 2 . This is similar to the result of Experiment 1 (lithium concentration: 50 mM) shown in FIG. 3, and suggests that lithium ions were electrochemically inserted into the manganese oxide crystal structure (intercalation).
一方、実験３－４～３－６（リチウム濃度：０．５～２ｍＭ）の場合、反応液の量が５０ｍＬに制限されているため、反応液中の全てのリチウムを回収できたとしても、酸化マンガンの回収量は限定的となる。実際、図６Ｄに示すように、λ‐ＭｎＯ２のピーク位置からのピークシフトは不完全であった。これは、実験３－１～３－３（リチウム濃度：５～２０ｍＭ）の場合と比較して、リチウム挿入量が減少していることを示唆している。
On the other hand, in the case of Experiments 3-4 to 3-6 (lithium concentration: 0.5 to 2 mM), the amount of reaction solution was limited to 50 mL, so even if all the lithium in the reaction solution could be recovered, The amount of manganese oxide recovered will be limited. In fact, as shown in Figure 6D, the peak shift from the peak position of λ- MnO2 was incomplete. This suggests that the amount of lithium inserted is reduced compared to the cases of Experiments 3-1 to 3-3 (lithium concentration: 5 to 20 mM).
しかし、組成分析の結果、実験３－５（図６Ｅ、リチウム濃度：１ｍＭ）及び３－６（図６Ｆ、リチウム濃度：０．５ｍＭ）の低リチウム濃度の場合において、用意した反応液中のリチウムのほぼ全量が酸化マンガンに回収されていることが明らかとなった（理論値からの誤差は５％以内であった）。これは、例えば、初期のリチウム濃度が１ｍＭ程度の反応液中からもリチウム回収が可能であり、反応が進んでリチウム濃度が更に低下した後においても、同様にインターカレーション反応が十分に進行してリチウム回収が可能であることを示唆している。以上から、低濃度のリチウム水溶液からでも高効率でリチウムを回収できることが確認できた。
However, as a result of compositional analysis, in the case of low lithium concentration in Experiments 3-5 (Fig. 6E, lithium concentration: 1mM) and 3-6 (Fig. 6F, lithium concentration: 0.5mM), lithium in the prepared reaction solution was It became clear that almost all of the amount was recovered as manganese oxide (the error from the theoretical value was within 5%). This means that, for example, lithium can be recovered from a reaction solution with an initial lithium concentration of about 1mM, and even after the reaction progresses and the lithium concentration further decreases, the intercalation reaction will proceed sufficiently. This suggests that lithium recovery is possible. From the above, it was confirmed that lithium can be recovered with high efficiency even from a low concentration lithium aqueous solution.
［実験４－１～４－４］
実験４－１～４－４では、リチウム回収剤が電子メディエータを含む場合のリチウム回収特性について評価した。 [Experiments 4-1 to 4-4]
In Experiments 4-1 to 4-4, lithium recovery characteristics were evaluated when the lithium recovery agent contained an electron mediator.
実験４－１～４－４では、リチウム回収剤が電子メディエータを含む場合のリチウム回収特性について評価した。 [Experiments 4-1 to 4-4]
In Experiments 4-1 to 4-4, lithium recovery characteristics were evaluated when the lithium recovery agent contained an electron mediator.
実験４－１及び４－２では、反応時間を３時間と短くした以外は、実験３－３（反応液中のリチウム濃度：５ｍＭ）及び実験３－２（反応液中のリチウム濃度：１０ｍＭ）と同様の条件で実験を行い、最終生成物である粉末を得た。また、実験４－３及び４－４では、リチウム回収剤が電子メディエータであるリボフラビンを含有すること以外、実験４－１及び４－２と同条件の実験を行い、最終生成物である粉末を得た。反応液中のリボフラビン濃度は、２μＭとした。
In Experiments 4-1 and 4-2, the reaction time was shortened to 3 hours, except for Experiment 3-3 (lithium concentration in the reaction solution: 5 mM) and Experiment 3-2 (lithium concentration in the reaction solution: 10 mM). An experiment was conducted under the same conditions as above, and the final product, a powder, was obtained. In Experiments 4-3 and 4-4, experiments were conducted under the same conditions as Experiments 4-1 and 4-2, except that the lithium recovery agent contained riboflavin, which is an electron mediator. Obtained. The riboflavin concentration in the reaction solution was 2 μM.
＜結晶構造評価＞
実験１と同様の方法により、実験４－１～４－４で得られた粉末のＸ線回折（ＸＲＤ）測定を行った。Ｘ線回折（ＸＲＤ）測定結果を図７Ａ～図７Ｄに示す。また、比較のため、図７Ａ～図７Ｄに、λ‐ＭｎＯ２のピーク位置を「λ－ＭｎＯ２」と添字のある縦破線で示す。 <Crystal structure evaluation>
Using the same method as inExperiment 1, X-ray diffraction (XRD) measurements were performed on the powders obtained in Experiments 4-1 to 4-4. The results of X-ray diffraction (XRD) measurements are shown in FIGS. 7A to 7D. For comparison, the peak position of λ-MnO 2 is shown in FIGS. 7A to 7D by a vertical broken line with a subscript "λ-MnO 2 ".
実験１と同様の方法により、実験４－１～４－４で得られた粉末のＸ線回折（ＸＲＤ）測定を行った。Ｘ線回折（ＸＲＤ）測定結果を図７Ａ～図７Ｄに示す。また、比較のため、図７Ａ～図７Ｄに、λ‐ＭｎＯ２のピーク位置を「λ－ＭｎＯ２」と添字のある縦破線で示す。 <Crystal structure evaluation>
Using the same method as in
図７Ａ～図７Ｄに示すように、リボフラビンを使用した実験４－３（図７Ｃ）及び４－４（図７Ｄ）では、反応時間が３時間と短いのにも関わらず、観測されたピーク（添え字のない縦破線）は、ピーク強度を保ったまま、λ‐ＭｎＯ２のピーク位置に対して、明確に低角側へシフトしていた。これは、リチウムイオンが電気化学的に酸化マンガン結晶構造内に挿入されたこと（インターカレーション）を示唆する。
As shown in Figures 7A to 7D, in Experiments 4-3 (Figure 7C) and 4-4 (Figure 7D) using riboflavin, the observed peak ( The vertical broken line (without a subscript) was clearly shifted to the lower angle side with respect to the peak position of λ-MnO 2 while maintaining the peak intensity. This suggests that lithium ions were electrochemically inserted into the manganese oxide crystal structure (intercalation).
一方、リボフラビンを使用しなかった実験４－１（図７Ａ）及び４－２（図７Ｂ）では、λ‐ＭｎＯ２のピーク位置からのピークシフトは不完全であった。これは、リボフラビンを使用した実験４－３及び４－４と比較して、リチウム挿入量が減少していることを示唆している。
On the other hand, in Experiments 4-1 (FIG. 7A) and 4-2 (FIG. 7B) in which riboflavin was not used, the peak shift from the peak position of λ-MnO 2 was incomplete. This suggests that the amount of lithium insertion is reduced compared to Experiments 4-3 and 4-4 using riboflavin.
以上の結果から、電子メディエータ（リボフラビン）を用いることで、より短時間で原料液からリチウムを回収できること、即ち、リチウム回収効率が向上することが確認できた。
From the above results, it was confirmed that by using the electron mediator (riboflavin), lithium could be recovered from the raw material liquid in a shorter time, that is, the lithium recovery efficiency was improved.
［実験５］
実験５では、反応液として海水を用いた以外は、実験１と同様の方法により、最終生成物である粉末を得た。 [Experiment 5]
In Experiment 5, a powder as the final product was obtained in the same manner as inExperiment 1 except that seawater was used as the reaction liquid.
実験５では、反応液として海水を用いた以外は、実験１と同様の方法により、最終生成物である粉末を得た。 [Experiment 5]
In Experiment 5, a powder as the final product was obtained in the same manner as in
＜Ｌｉ濃度測定＞
ＩＣＰ発光分光分析により、実験５で用いた反応前の海水（原料液）と、反応後の海水（Ｌｉ回収後の反応液）のＬｉ濃度を測定した。結果を以下に示す。 <Li concentration measurement>
The Li concentration of the seawater before the reaction (raw material liquid) and the seawater after the reaction (the reaction liquid after Li recovery) used in Experiment 5 was measured by ICP emission spectrometry. The results are shown below.
ＩＣＰ発光分光分析により、実験５で用いた反応前の海水（原料液）と、反応後の海水（Ｌｉ回収後の反応液）のＬｉ濃度を測定した。結果を以下に示す。 <Li concentration measurement>
The Li concentration of the seawater before the reaction (raw material liquid) and the seawater after the reaction (the reaction liquid after Li recovery) used in Experiment 5 was measured by ICP emission spectrometry. The results are shown below.
表１に示す結果から、リチウム回収率は、約９６～９８重量％と計算できる。実験５の結果から、原料液に海水を用いた場合も、高い回収率でリチウムを回収できることが確認できた。
From the results shown in Table 1, the lithium recovery rate can be calculated to be approximately 96 to 98% by weight. The results of Experiment 5 confirmed that lithium could be recovered at a high recovery rate even when seawater was used as the raw material liquid.
［実験６］
図８に示されたリチウム回収システムの実証試験を行った。図９Ａは、そのセットアップを表す画像である。ＬｉＣｌ／ＰＢＳ（１０、５０ｍＭ）溶液が収容された容器（ガラスビーカー）に、ガラス製のスクリューバイアルが倒立状態で浸漬されている。なお、説明のために、背景が削除される等、画像の一部が加工されている。 [Experiment 6]
A demonstration test of the lithium recovery system shown in Figure 8 was conducted. FIG. 9A is an image representing the setup. A glass screw vial is immersed upside down in a container (glass beaker) containing a LiCl/PBS (10, 50 mM) solution. For illustrative purposes, some of the images have been altered, such as removing the background.
図８に示されたリチウム回収システムの実証試験を行った。図９Ａは、そのセットアップを表す画像である。ＬｉＣｌ／ＰＢＳ（１０、５０ｍＭ）溶液が収容された容器（ガラスビーカー）に、ガラス製のスクリューバイアルが倒立状態で浸漬されている。なお、説明のために、背景が削除される等、画像の一部が加工されている。 [Experiment 6]
A demonstration test of the lithium recovery system shown in Figure 8 was conducted. FIG. 9A is an image representing the setup. A glass screw vial is immersed upside down in a container (glass beaker) containing a LiCl/PBS (10, 50 mM) solution. For illustrative purposes, some of the images have been altered, such as removing the background.
スクリューバイアルには、塩化リチウムを含まないこと以外は、実験１と同様にして調整されたリチウム回収剤と、乳酸ナトリウムとを含むＰＢＳ溶液が収容された。上述のとおり、このＰＢＳ溶液には、当初、ＬｉＣｌは含有されなかった（ｗ／ｏ ＬｉＣｌ）。
更に、スクリューバイアルの開口部分は、スクリュー蓋に代えて、カチオン交換膜で密閉された。 A screw vial contained a PBS solution containing a lithium recovery agent prepared in the same manner as inExperiment 1, except that it did not contain lithium chloride, and sodium lactate. As mentioned above, the PBS solution initially contained no LiCl (w/o LiCl).
Furthermore, the opening of the screw vial was sealed with a cation exchange membrane instead of a screw cap.
更に、スクリューバイアルの開口部分は、スクリュー蓋に代えて、カチオン交換膜で密閉された。 A screw vial contained a PBS solution containing a lithium recovery agent prepared in the same manner as in
Furthermore, the opening of the screw vial was sealed with a cation exchange membrane instead of a screw cap.
図９Ｂは、ＬｉＣｌ／ＰＢＳ（１０ｍＭ）溶液浸漬前のスクリューバイアルの画像（左）と、浸漬後２４時間反応させた後のスクリューバイアルの画像（右）の比較である。
浸漬前の溶液は、赤茶色であったのに対し、反応後の溶液は、より黒色に近い茶色に変化した。これは、リチウムと、λ－ＭｎＯ２とのインタラクションを示唆するものであった。なお、図９Ｂでは、実際には赤色の濃淡が、黒色の濃淡として表されている。 FIG. 9B is a comparison of an image of a screw vial before immersion in LiCl/PBS (10 mM) solution (left) and an image of a screw vial after 24 hours of reaction after immersion (right).
The solution before immersion was reddish brown, whereas the solution after reaction changed to a brown color closer to black. This suggested an interaction between lithium and λ-MnO 2 . Note that in FIG. 9B, the shading of red is actually represented as the shading of black.
浸漬前の溶液は、赤茶色であったのに対し、反応後の溶液は、より黒色に近い茶色に変化した。これは、リチウムと、λ－ＭｎＯ２とのインタラクションを示唆するものであった。なお、図９Ｂでは、実際には赤色の濃淡が、黒色の濃淡として表されている。 FIG. 9B is a comparison of an image of a screw vial before immersion in LiCl/PBS (10 mM) solution (left) and an image of a screw vial after 24 hours of reaction after immersion (right).
The solution before immersion was reddish brown, whereas the solution after reaction changed to a brown color closer to black. This suggested an interaction between lithium and λ-MnO 2 . Note that in FIG. 9B, the shading of red is actually represented as the shading of black.
図１０Ａ～１０Ｃは、実験１と同様の方法により行われた粉末のＸ線回折（ＸＲＤ）測定の結果（回折プロファイル）である。各図は、以下の実験に対応する。
・図１０Ａ：実験６－１（浸漬前のλ‐ＭｎＯ２のプロファイル）
・図１０Ｂ：実験６－２（１０ｍＭ ＬｉＣｌ溶液浸漬後のプロファイル）
・図１０Ｃ：実験６－３（５０ｍＭ ＬｉＣｌ溶液浸漬後のプロファイル） 10A to 10C are the results (diffraction profiles) of X-ray diffraction (XRD) measurements of powders performed by the same method as inExperiment 1. Each figure corresponds to the following experiment.
・Figure 10A: Experiment 6-1 (λ-MnO 2 profile before immersion)
・Figure 10B: Experiment 6-2 (profile after immersion in 10mM LiCl solution)
・Figure 10C: Experiment 6-3 (profile after immersion in 50mM LiCl solution)
・図１０Ａ：実験６－１（浸漬前のλ‐ＭｎＯ２のプロファイル）
・図１０Ｂ：実験６－２（１０ｍＭ ＬｉＣｌ溶液浸漬後のプロファイル）
・図１０Ｃ：実験６－３（５０ｍＭ ＬｉＣｌ溶液浸漬後のプロファイル） 10A to 10C are the results (diffraction profiles) of X-ray diffraction (XRD) measurements of powders performed by the same method as in
・Figure 10A: Experiment 6-1 (λ-MnO 2 profile before immersion)
・Figure 10B: Experiment 6-2 (profile after immersion in 10mM LiCl solution)
・Figure 10C: Experiment 6-3 (profile after immersion in 50mM LiCl solution)
実験６－２（図１０Ｂ）、及び、実験６－３（図１０Ｃ）の結果と、実験６－１（図１０Ａ）とを比較すると、λ‐ＭｎＯ２に由来するピークが低角側へシフトした。シフト後のピーク位置は、ＬｉＭｎ２Ｏ４に由来するピーク位置とほぼ一致した。これにより、カチオン交換膜を介して、外部から導入されたリチウムイオンが回収されたことが確認できた。
Comparing the results of Experiment 6-2 (Figure 10B) and Experiment 6-3 (Figure 10C) with Experiment 6-1 (Figure 10A), the peak derived from λ-MnO 2 shifts to the lower angle side. did. The peak position after the shift almost coincided with the peak position derived from LiMn 2 O 4 . This confirmed that lithium ions introduced from the outside were recovered via the cation exchange membrane.
本発明のリチウム回収剤は、簡便、且つ効率的にリチウムを回収可能である。回収したリチウムは、リチウムイオン二次電池や核融合炉の燃料等の原料として利用可能である。
The lithium recovery agent of the present invention can recover lithium simply and efficiently. The recovered lithium can be used as a raw material for lithium ion secondary batteries, fuel for nuclear fusion reactors, etc.
１０ 発電細菌
２０ 電子供与体
３０ 電子伝達タンパク質
４０ インターカレーション材料
１００ リチウム回収剤
２００ 原料液
３００ 反応容器
１０００ リチウム回収システム
１１０ 配管
１３０ リチウムイオン
２１０ 冷却水
３００ 反応容器
４００ カチオン交換膜
１１００ リチウム回収システム
10 Power-generatingbacteria 20 Electron donor 30 Electron transfer protein 40 Intercalation material 100 Lithium recovery agent 200 Raw material liquid 300 Reaction vessel 1000 Lithium recovery system 110 Piping 130 Lithium ion 210 Cooling water 300 Reaction vessel 400 Cation exchange membrane 1100 Lithium recovery system
２０ 電子供与体
３０ 電子伝達タンパク質
４０ インターカレーション材料
１００ リチウム回収剤
２００ 原料液
３００ 反応容器
１０００ リチウム回収システム
１１０ 配管
１３０ リチウムイオン
２１０ 冷却水
３００ 反応容器
４００ カチオン交換膜
１１００ リチウム回収システム
10 Power-generating
Claims (20)
- リチウムを含む原料液から前記リチウムを回収するためのリチウム回収剤であって、
発電細菌と、
リチウムインターカレーション材料と、を含むリチウム回収剤。 A lithium recovery agent for recovering lithium from a raw material liquid containing lithium,
electricity-generating bacteria,
a lithium intercalation material; and a lithium recovery agent. - 前記発電細菌が鉄還元菌である、請求項１に記載のリチウム回収剤。 The lithium recovery agent according to claim 1, wherein the power-generating bacteria are iron-reducing bacteria.
- 前記発電細菌が、シュワネラ属細菌、又はジオバクター属細菌である、請求項２に記載のリチウム回収剤。 The lithium recovery agent according to claim 2, wherein the power-generating bacterium is a Shewanella bacterium or a Geobacter bacterium.
- 前記リチウムインターカレーション材料が、第１遷移金属を含む化合物である、請求項１～３のいずれか１項に記載のリチウム回収剤。 The lithium recovery agent according to any one of claims 1 to 3, wherein the lithium intercalation material is a compound containing a first transition metal.
- 前記第１遷移金属が、マンガン（Ｍｎ）、バナジウム（Ｖ）、チタン（Ｔｉ）、及び鉄（Ｆｅ）からなる群から選択される少なくとも１つである、請求項４に記載のリチウム回収剤。 The lithium recovery agent according to claim 4, wherein the first transition metal is at least one selected from the group consisting of manganese (Mn), vanadium (V), titanium (Ti), and iron (Fe).
- 前記リチウムインターカレーション材料が、スピネル型構造の二酸化マンガンである、請求項５に記載のリチウム回収剤。 The lithium recovery agent according to claim 5, wherein the lithium intercalation material is manganese dioxide with a spinel structure.
- 前記リチウムインターカレーション材料が粒子である、請求項１～６のいずれか１項に記載のリチウム回収剤。 The lithium recovery agent according to any one of claims 1 to 6, wherein the lithium intercalation material is a particle.
- 電子供与体を更に含む、請求項１～７のいずれか１項に記載のリチウム回収剤。 The lithium recovery agent according to any one of claims 1 to 7, further comprising an electron donor.
- 前記発電細菌がシュワネラ属細菌であり、且つ前記電子供与体が乳酸塩であるか、又は、
前記発電細菌がジオバクター属細菌であり、且つ前記電子供与体が酢酸塩である、請求項８に記載のリチウム回収剤。 the power-generating bacterium is a Shewanella bacterium, and the electron donor is lactate, or
The lithium recovery agent according to claim 8, wherein the power-generating bacterium is a Geobacter bacterium, and the electron donor is acetate. - 電子メディエータを更に含む、請求項１～９のいずれか１項に記載のリチウム回収剤。 The lithium recovery agent according to any one of claims 1 to 9, further comprising an electron mediator.
- 前記電子メディエータがフラビン類である、請求項１０に記載のリチウム回収剤。 The lithium recovery agent according to claim 10, wherein the electron mediator is a flavin.
- 請求項１～１１のいずれか１項に記載の前記リチウム回収剤と、前記原料液とを接触させることを含むリチウム回収方法。 A lithium recovery method comprising bringing the lithium recovery agent according to any one of claims 1 to 11 into contact with the raw material liquid.
- 前記発電細菌の発生する電子が、前記リチウムインターカレーション材料に伝達される、請求項１２に記載のリチウム回収方法。 The lithium recovery method according to claim 12, wherein the electrons generated by the power-generating bacteria are transferred to the lithium intercalation material.
- 前記原料液と、前記リチウム回収剤とを含む反応液を調製することと、
前記反応液中に、前記リチウム回収剤及び前記リチウムを含有する沈殿物を生成させることと、
前記反応液から、前記沈殿物を分離すること、を含む、請求項１２または１３に記載のリチウム回収方法。 preparing a reaction solution containing the raw material solution and the lithium recovery agent;
producing a precipitate containing the lithium recovery agent and the lithium in the reaction solution;
The lithium recovery method according to claim 12 or 13, comprising separating the precipitate from the reaction solution. - 前記原料液は、カチオン交換膜を介して外部から導入されたリチウムイオンを含む、請求項１４に記載のリチウム回収方法。 The lithium recovery method according to claim 14, wherein the raw material liquid contains lithium ions introduced from the outside via a cation exchange membrane.
- リチウム回収システムであって、
反応容器と、
前記反応容器内に配置された、請求項１～１１のいずれか１項に記載の前記リチウム回収剤と、を備え、
前記反応容器内において、前記原料液と前記リチウム回収剤とが接触する、リチウム回収システム。 A lithium recovery system,
a reaction vessel;
The lithium recovery agent according to any one of claims 1 to 11, disposed in the reaction vessel,
A lithium recovery system, wherein the raw material liquid and the lithium recovery agent are in contact with each other in the reaction vessel. - 前記リチウム回収剤に電気を通電するための機構を有さない、請求項１６に記載のリチウム回収システム。 The lithium recovery system according to claim 16, which does not have a mechanism for applying electricity to the lithium recovery agent.
- 前記反応容器は、リチウムイオンを前記原料液に前記反応容器の外部から導入するためのカチオン交換膜を備える、請求項１６に記載のリチウム回収システム。 The lithium recovery system according to claim 16, wherein the reaction vessel includes a cation exchange membrane for introducing lithium ions into the raw material liquid from outside the reaction vessel.
- 請求項１２～１５のいずれか１項に記載のリチウム回収方法を含み、
前記リチウムインターカレーション材料が二酸化マンガンである、リチウム含有マンガン酸化物の製造方法。 Including the lithium recovery method according to any one of claims 12 to 15,
A method for producing a lithium-containing manganese oxide, wherein the lithium intercalation material is manganese dioxide. - 請求項１２～１５のいずれか１項に記載のリチウム回収方法を含む、リチウムイオン電池の正極活物質の製造方法。
A method for producing a positive electrode active material for a lithium ion battery, comprising the lithium recovery method according to any one of claims 12 to 15.
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| JP2008177061A (en) * | 2007-01-18 | 2008-07-31 | Okayama Univ | Positive electrode active material, and its utilization |
| CN102560114A (en) * | 2012-02-23 | 2012-07-11 | 北京理工大学 | Method for bioleaching and extracting valuable metal ions in waste batteries |
| JP2014037591A (en) * | 2012-08-20 | 2014-02-27 | Osaka Prefecture Univ | Metal recovery method and metal recovery device therefor |
| US20180034054A1 (en) * | 2016-07-28 | 2018-02-01 | Candace Chan | Oxidation-reduction assisted exfoliation and reassembly of transition metal oxide lithium intercalation compounds |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2008177061A (en) * | 2007-01-18 | 2008-07-31 | Okayama Univ | Positive electrode active material, and its utilization |
| CN102560114A (en) * | 2012-02-23 | 2012-07-11 | 北京理工大学 | Method for bioleaching and extracting valuable metal ions in waste batteries |
| JP2014037591A (en) * | 2012-08-20 | 2014-02-27 | Osaka Prefecture Univ | Metal recovery method and metal recovery device therefor |
| US20180034054A1 (en) * | 2016-07-28 | 2018-02-01 | Candace Chan | Oxidation-reduction assisted exfoliation and reassembly of transition metal oxide lithium intercalation compounds |
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