Preparation method of bio-friendly sphere-like nano manganous-manganic oxide and product of bio-friendly sphere-like nano manganous-manganic oxide

Abstract

The invention discloses a preparation method of bio-friendly sphere-like nano manganous-manganic oxide and a product, and relates to the technical field of functional nano materials. The method comprises the following steps: mixing manganese salt with ultrapure water to obtain a manganese salt solution; the catalyst is selected from monoethanolamine, diethanolamine and triethanolamine, and the modifier is selected from polyethylene glycol, sodium alginate and derivatives thereof, chitosan and derivatives thereof, and water-soluble cellulose and derivatives thereof; dropwise adding an alkaline solution and an acidic solution to adjust the pH value of the manganese salt solution, adding ultrapure water, uniformly stirring, and pouring into a hydrothermal reaction kettle; putting the hydrothermal reaction kettle into a drying box, and heating and reacting completely to obtain manganous-manganic oxide slurry; filtering, rinsing and drying to obtain a manganous-manganic oxide powder product; the biotoxicity of the manganous-manganic oxide nano-particles is effectively reduced, strict biomedical application requirements are met, the preparation method is simple, process conditions are mild, expensive equipment is not needed, and cost control is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of functional nanomaterials, and in particular to a preparation method and product of bio-friendly spherical nano manganese tetroxide. Background Art

[0002] Manganese tetraoxide (Mn3O4) is a metal oxide that is widely used in scientific research and production, especially in traditional hot fields. It can be used as a raw material for manganese-zinc ferrite, anode material for lithium-ion batteries, catalyst for nitrogen oxides, and material for gas sensors. In addition, manganese oxides and their derivatives are attracting attention in the fields of bioimaging, biosensing, gene delivery, and cancer therapy due to their stability, elemental richness, and adjustable structure.

[0003] Traditional natural enzymes have limitations such as high price, low yield, low stability and potential immunogenicity. "Nanozymes" provide a solution. Among many nanomaterials, manganese tetraoxide nanoparticles have a unique Mn 2+ / Mn 3+ The mixed oxidation state, high irreversible oxidation stability and large specific surface area show significant multiple enzyme-like activities and can quench reactive oxygen species (ROS).

[0004] However, manganese tetraoxide has potential toxicity risks in the body and is difficult to meet strict biomedical requirements. In the biological environment, manganese ions (Mn 2+ ), manganese ions are essential trace elements at low concentrations, but at higher concentrations they may have toxic effects on the nervous system and other organs, leading to cellular oxidative stress, DNA damage and inflammatory responses. Therefore, a bio-friendly spherical nano-manganese tetraoxide preparation method and product are urgently needed to solve this problem. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation method and product of bio-friendly spherical nano manganese tetraoxide to solve the problems mentioned in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing bio-friendly spherical nano manganese tetraoxide, comprising the following specific steps:

[0007] S1: mixing manganese salt with ultrapure water to obtain a manganese salt solution;

[0008] S2 adding an appropriate amount of catalyst and modifier to the manganese salt solution and stirring evenly, wherein the catalyst is one or more of monoethanolamine, diethanolamine, and triethanolamine, and the modifier is one or more of polyethylene glycol, sodium alginate and its derivatives, chitosan and its derivatives, and water-soluble cellulose and its derivatives;

[0009] S3 prepares an alkaline solution of a certain concentration;

[0010] S4 prepares an acid solution of a certain concentration;

[0011] S5: adding alkaline solution and acidic solution to adjust the pH value of the manganese salt solution, adding an appropriate amount of ultrapure water, stirring evenly and pouring into the hydrothermal reaction kettle;

[0012] S6: placing the hydrothermal reactor in a drying oven, setting a certain heating and insulation curve, and obtaining manganese tetraoxide slurry after the reaction is complete;

[0013] S7: filtering, rinsing and drying the manganese tetraoxide slurry to obtain a manganese tetraoxide powder product.

[0014] Preferably, the manganese salt in the above step S1 is one or more of manganese chloride, manganese acetate, and manganese gluconate, and the concentration of manganese ions in the manganese salt solution is 0.5 to 1 mol / L.

[0015] Preferably, in the above step S2, the amount of catalyst added is 1-10% of the mass of manganese ions, and the amount of modifier added is 5-15% of the mass of manganese ions.

[0016] Preferably, the alkaline solution in the above step S3 is one or more of sodium hydroxide solution, potassium hydroxide solution, and ammonia solution, and the concentration of the alkaline solution is 1 to 6 mol / L; the acidic solution in step S4 is one or more of phosphoric acid, formic acid, acetic acid, and citric acid, and the concentration of the acidic solution is 1 to 6 mol / L.

[0017] Preferably, in the above step S5, the pH value of the manganese salt solution is adjusted to 4-6.

[0018] Preferably, in the above step S5, after the ultrapure water is added, the manganese ion concentration in the solution is 0.25-0.5 mol / L, and the volume of the solution is 20-50% of the total volume of the lining of the hydrothermal reactor.

[0019] Preferably, in the above step S6, the heating and insulation curve is to heat to 150°C at a rate of 1-5°C / min and then keep warm for 8-10 hours.

[0020] Preferably, in the above step S7, rinsing refers to repeated washing with ultrapure water for 3 times or more to remove other free ions in the object to be washed; the drying temperature is 60 to 80° C., and the drying time is 8 to 16 hours.

[0021] Another technical solution provided by the present invention is a bio-friendly spherical nano manganese tetraoxide product prepared by the above-mentioned preparation method, which, when added to the environmental system where biological cells are located, does not inhibit the growth of biological cells and does not reduce the survival rate of biological cells.

[0022] Preferably, the impurity content of Pb in the above-mentioned trimanganese tetraoxide product is less than 500 ppb, the impurity content of Cd is less than 500 ppb, the impurity content of Sn is less than 50 ppm, the impurity content of Ni is less than 1 ppm, the impurity content of Cr is less than 1 ppm, and the impurity content of Cu is less than 10 ppm. The particle size D50 of the trimanganese tetraoxide product is 50 to 500 nm, and the specific surface area is 10 to 20 m 2 / g.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The preparation method and product of the bio-friendly spherical nano manganese tetraoxide effectively reduce the biological toxicity of manganese tetraoxide nanoparticles by introducing polyethylene glycol, sodium alginate and its derivatives, chitosan and its derivatives and / or water-soluble cellulose and its derivatives as modifiers during the preparation process. The product obtained after modification can significantly reduce the biotoxicity of Mn 2+ The release amount is reduced, thereby reducing the toxic risks such as cellular oxidative stress, DNA damage and inflammatory response caused by manganese ions, meeting the strict requirements of biomedical applications.

[0025] 2. The preparation method and product of the bio-friendly spherical nano manganese tetraoxide can reduce the introduction of heavy metal elements by controlling the content of heavy metal elements in the main raw materials, thereby further controlling the reduction of product toxicity.

[0026] 3. The preparation method and product of the bio-friendly spherical nano-manganese tetroxide, through precise control of the reactant concentration and pH value and optimization of the preparation conditions, make the prepared manganese tetroxide nanoparticles more uniform in morphology and concentrated in particle size distribution, and improve the repeatability and stability of the product, making it suitable for mass production and application.

[0027] 4. The preparation method of the bio-friendly spherical nano-manganese tetraoxide is simple, uses ultrapure water as a solvent, and adopts a non-toxic modifier, which reduces the burden on the environment. In addition, the raw materials and process conditions used in the method are relatively mild, and do not require expensive equipment or extreme conditions, further reducing energy consumption and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a SEM image of manganese tetraoxide prepared in Example 1;

[0029] Figure 2 The XRD pattern of manganese tetraoxide prepared in Example 1;

[0030] Figure 3 The OD value changes over time in the culture dish of Example 1 under different concentration treatments. DETAILED DESCRIPTION

[0031] In order to provide a new feasible solution to the problem of potential toxicity risk of manganese tetraoxide in vivo, the present invention proposes a method for preparing bio-friendly spherical nano manganese tetraoxide, specifically:

[0032] S1: mixing manganese salt with ultrapure water to obtain a manganese salt solution;

[0033] Optionally, the manganese salt is manganese chloride (MnCl2), manganese acetate (generally hydrated Mn(CH3COO)2·4H2O), manganese gluconate (Mn(C6H 11 O7) one or more of 2), further optionally, the concentration of manganese ions in the manganese salt solution is preferably controlled at 0.5-1 mol / L;

[0034] S2: adding an appropriate amount of catalyst and modifier to the manganese salt solution and stirring evenly, wherein the catalyst is one or more of monoethanolamine, diethanolamine, and triethanolamine, and the modifier is one or more of polyethylene glycol (such as PEG3000, PEG6000, etc.), sodium alginate and its derivatives, chitosan and its derivatives, and water-soluble cellulose and its derivatives;

[0035] For reference, the amount of catalyst added can be 1-10% of the mass of manganese ions, and the amount of modifier added can be 5-15% of the mass of manganese ions;

[0036] S3 prepares an alkaline solution of a certain concentration;

[0037] Optionally, the alkaline solution is one or more of a sodium hydroxide solution, a potassium hydroxide solution, and an ammonia solution, and the concentration of the alkaline solution is 1 to 6 mol / L;

[0038] S4 prepares an acid solution of a certain concentration;

[0039] Optionally, the acidic solution is one or more of phosphoric acid, formic acid, acetic acid, and citric acid, and the concentration of the acidic solution is 1 to 6 mol / L;

[0040] The order of the above steps S3 and S4 can be adjusted arbitrarily, and existing reagents can be prepared in advance or purchased;

[0041] S5: adding alkaline solution and acidic solution to adjust the pH value of the manganese salt solution, adding an appropriate amount of ultrapure water, stirring evenly and pouring into the hydrothermal reaction kettle;

[0042] In a preferred embodiment, the pH value of the manganese salt solution is adjusted to 4-6;

[0043] In addition, optionally, after the ultrapure water is added, the manganese ion concentration in the solution can be 0.25-0.5 mol / L, and the volume of the solution can be 20-50% of the total volume of the lining of the hydrothermal reactor;

[0044] S6: placing the hydrothermal reactor in a drying oven, setting a certain heating and insulation curve, and obtaining manganese tetraoxide slurry after the reaction is complete;

[0045] For reference, the heating and insulation curve can be at a rate of 1 to 5°C / min, specifically, the temperature can be raised to 150°C and then kept for 8 to 10 hours;

[0046] S7: filtering, rinsing and drying the manganese tetraoxide slurry to obtain a manganese tetraoxide powder product.

[0047] Among them, rinsing can be repeated with ultrapure water for 3 times or more to remove other free ions in the items to be washed; the drying temperature should be 60-80°C, and the drying time should be 8-16 hours.

[0048] It has been verified by experiments that the product prepared by the preparation method of the present invention, when added to the environment system where biological cells are located, will not inhibit the growth of the biological cells, nor will it reduce the survival rate of the biological cells.

[0049] In order to further improve the safety of the above products, the impurity content can be controlled from the raw material end, and the following high-purity manganese tetraoxide product can be obtained: wherein the Pb impurity content is less than 500ppb, the Cd impurity content is less than 500ppb, the Sn impurity content is less than 50ppm, the Ni impurity content is less than 1ppm, the Cr impurity content is less than 1ppm, and the Cu impurity content is less than 10ppm; specifically, it can be achieved by controlling the raw material end, that is, the Pb impurity content in the manganese salt is less than 500ppb, the Cd impurity content is less than 500ppb, the Sn impurity content is less than 50ppm, the Ni impurity content is less than 1ppm, the Cr impurity content is less than 1ppm, and the Cu impurity content is less than 10ppm; in actual production, according to production requirements, a suitable manganese salt can be selected, for example, the Pb impurity content is less than 1ppm, the Cd impurity content is less than 1ppm, the Sn impurity content is less than 100ppm, the Ni impurity content is less than 10ppm, the Cr impurity content is less than 10ppm, and the Cu impurity content is less than 10ppm, then the impurity content of the manganese tetraoxide product is also within this range.

[0050] In addition, in a preferred embodiment, the particle size of the manganese tetraoxide product prepared by the present invention can be controlled to be less than 1 μm in D50 and the specific surface area is 10 to 50 m 2 / g, and further preferably, the particle size can be controlled within the range of D50 of 50 to 500 nm, and the specific surface area of ​​10 to 20 m 2 / g.

[0051] In order to facilitate those skilled in the art to understand the present invention, the present invention will be described in detail below with reference to the accompanying drawings and through specific embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0052] Embodiment 1:

[0053] (1) 6.127 g of manganese acetate (Mn(CH3COO)2·4H2O) was mixed with 50 ml of ultrapure water to obtain a manganese salt solution;

[0054] (2) Add 0.07 g triethanolamine and 0.11 g polyethylene glycol (PEG3000) to the manganese acetate solution in step (1) above and stir evenly.

[0055] (3) Prepare 6 mol / L sodium hydroxide solution,

[0056] (4) preparing 6 mol / L acetic acid solution;

[0057] (5) The pH value of the solution in step (2) is adjusted to 5 by dropwise adding the acid-base solution in step (3) or (4), and ultrapure water is added to 100 ml, stirred evenly and added to a 200 ml hydrothermal reactor;

[0058] (6) Add the hydrothermal reaction kettle of step (5) above into a drying oven, set the heating rate to 2°C / min, heat to 150°C and keep warm for 8h to obtain manganese tetraoxide slurry after the reaction is complete;

[0059] (7) filtering the manganese tetraoxide slurry after step (6), rinsing it with ultrapure water for 3 times and drying it at 70° C. for 10 hours to obtain a manganese tetraoxide powder product;

[0060] The SEM and XRD patterns of the manganese tetraoxide product prepared in Example 1 are shown in Figure 1 and Figure 2 .

[0061] Cytotoxicity test: 4×10 5 L929 cells were inoculated at a density of 100 mg / mL in a culture dish. After the cells adhered to the wall, different concentrations of crushed bio-friendly spherical nano-manganese tetraoxide Example 1 were added and cultured at 37°C and 5% CO2. The cells were cultured continuously and the cell survival rate was determined using a cell counting kit (CCK8) on days 1, 3 and 7. The changes in OD values ​​over time (day 1, day 3, day 7) under different concentrations (PBS, 0.2, 0.5, 0.8, 1, 2 mg / mL) were shown in Table 1. Figure 3, where the vertical axis reflects the cell survival rate results. The concentration of bio-friendly spherical nano manganese tetroxide gradually increases in each group of data in the direction of the arrow. It can be seen from the figure that bio-friendly spherical nano manganese tetroxide has no obvious cytotoxicity, does not inhibit the growth of biological cells, and the survival rate of biological cells is basically maintained at the same level, with no effect.

[0062] Embodiment 2:

[0063] (1) 3.677 g of manganese acetate (Mn(CH3COO)2·4H2O) was mixed with 30 ml of ultrapure water to obtain a manganese salt solution;

[0064] (2) Add 0.04 g triethanolamine and 0.066 g polyethylene glycol (PEG3000) to the manganese acetate solution in step (1) above and stir evenly.

[0065] (3) Prepare 6 mol / L sodium hydroxide solution,

[0066] (4) preparing 6 mol / L acetic acid solution;

[0067] (5) The pH value of the solution in step (2) is adjusted to 5 by dropwise adding the acid-base solution in step (3) or (4), and ultrapure water is added to 60 ml, stirred evenly and added to a 200 ml hydrothermal reactor;

[0068] (6) Add the hydrothermal reaction kettle of step (5) above into a drying oven, set the heating rate to 5°C / min, heat to 150°C and keep warm for 10 hours to obtain manganese tetraoxide slurry after the reaction is complete;

[0069] (7) filtering the manganese tetraoxide slurry after step (6), rinsing it with ultrapure water for 3 times and drying it at 70° C. for 10 hours to obtain a manganese tetraoxide powder product;

[0070] Embodiment 3:

[0071] (1) 3.677 g of manganese acetate (Mn(CH3COO)2·4H2O) was mixed with 30 ml of ultrapure water to obtain a manganese salt solution;

[0072] (2) Add 0.04 g triethanolamine and 0.066 g polyethylene glycol (PEG3000) to the manganese acetate solution in step (1) above and stir evenly.

[0073] (3) Prepare 6 mol / L sodium hydroxide solution,

[0074] (4) preparing 6 mol / L acetic acid solution;

[0075] (5) The pH value of the solution in step (2) is adjusted to 5 by dropwise adding the acid-base solution in step (3) or (4), and ultrapure water is added to 60 ml, stirred evenly and added to a 200 ml hydrothermal reactor;

[0076] (6) Add the hydrothermal reaction kettle of step (5) above into a drying oven, set the heating rate to 2°C / min, heat to 150°C and keep warm for 8h to obtain manganese tetraoxide slurry after the reaction is complete;

[0077] (7) filtering the manganese tetraoxide slurry after step (6), rinsing it with ultrapure water for 3 times and drying it at 70° C. for 10 hours to obtain a manganese tetraoxide powder product;

[0078] Embodiment 4:

[0079] (1) 3.677 g of manganese acetate (Mn(CH3COO)2·4H2O) was mixed with 30 ml of ultrapure water to obtain a manganese salt solution;

[0080] (2) Add 0.04 g triethanolamine and 0.066 g sodium alginate to the manganese acetate solution in step (1) above and stir evenly.

[0081] (3) Prepare 6 mol / L sodium hydroxide solution,

[0082] (4) preparing 6 mol / L acetic acid solution;

[0083] (5) The pH value of the solution in step (2) is adjusted to 5 by dropwise adding the acid-base solution in step (3) or (4), and ultrapure water is added to 60 ml, stirred evenly and added to a 200 ml hydrothermal reactor;

[0084] (6) Add the hydrothermal reaction kettle of step (5) above into a drying oven, set the heating rate to 2°C / min, heat to 150°C and keep warm for 10 hours to obtain manganese tetraoxide slurry after the reaction is complete;

[0085] (7) filtering the manganese tetraoxide slurry after step (6), rinsing it with ultrapure water for 3 times and drying it at 70° C. for 10 hours to obtain a manganese tetraoxide powder product;

[0086] Embodiment 5:

[0087] (1) 3.677 g of manganese acetate (Mn(CH3COO)2·4H2O) was mixed with 30 ml of ultrapure water to obtain a manganese salt solution;

[0088] (2) Add 0.04 g triethanolamine and 0.066 g chitosan to the manganese acetate solution in step (1) above and stir evenly.

[0089] (3) Prepare 6 mol / L sodium hydroxide solution,

[0090] (4) preparing 6 mol / L acetic acid solution;

[0091] (5) The pH value of the solution in step (2) is adjusted to 5 by dropwise adding the acid-base solution in step (3) or (4), and ultrapure water is added to 60 ml, stirred evenly and added to a 200 ml hydrothermal reactor;

[0092] (6) Add the hydrothermal reaction kettle of step (5) above into a drying oven, set the heating rate to 2°C / min, heat to 150°C and keep warm for 8h to obtain manganese tetraoxide slurry after the reaction is complete;

[0093] (7) filtering the manganese tetraoxide slurry after step (6), rinsing it with ultrapure water for 3 times and drying it at 70° C. for 10 hours to obtain a manganese tetraoxide powder product;

[0094] Embodiment 6:

[0095] (1) 6.127 g of manganese acetate (Mn(CH3COO)2·4H2O) was mixed with 50 ml of ultrapure water to obtain a manganese salt solution;

[0096] (2) Add 0.07 g triethanolamine and 0.13 g sodium carboxymethyl cellulose (CMC-Na) to the manganese acetate solution in step (1) above and stir evenly.

[0097] (3) Prepare 6 mol / L sodium hydroxide solution,

[0098] (4) preparing 6 mol / L acetic acid solution;

[0099] (5) The pH value of the solution in step (2) is adjusted to 5 by dropwise adding the acid-base solution in step (3) or (4), and ultrapure water is added to 100 ml, stirred evenly and added to a 200 ml hydrothermal reactor;

[0100] (6) Add the hydrothermal reaction kettle of step (5) above into a drying oven, set the heating rate to 2°C / min, heat to 150°C and keep warm for 10 hours to obtain manganese tetraoxide slurry after the reaction is complete;

[0101] (7) filtering the manganese tetraoxide slurry after step (6), rinsing it with ultrapure water for 3 times and drying it at 70° C. for 10 hours to obtain a manganese tetraoxide powder product;

[0102] The physical and chemical indicators of the trimanganese tetraoxide products obtained in Examples 1 to 6 were tested, and the results are shown in Table 1. The results show that the trimanganese tetraoxide products prepared by the inventive method have high purity, low content of heavy metal impurities, and physical indicators also meet the requirements.

[0103] Table 1 Physical and chemical indicators of manganese tetraoxide products prepared in Examples 1 to 6

[0104]

[0105] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined by the claims.

[0106] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. A method for preparing bio-friendly spherical nano manganese tetraoxide, characterized in that: The specific steps include: S1: mixing manganese salt with ultrapure water to obtain a manganese salt solution; S2 adding an appropriate amount of catalyst and modifier to the manganese salt solution and stirring evenly, wherein the catalyst is one or more of monoethanolamine, diethanolamine, and triethanolamine, and the modifier is one or more of polyethylene glycol, sodium alginate and its derivatives, chitosan and its derivatives, and water-soluble cellulose and its derivatives; S3 prepares an alkaline solution of a certain concentration; S4 prepares an acid solution of a certain concentration; S5: adding alkaline solution and acidic solution to adjust the pH value of the manganese salt solution, adding an appropriate amount of ultrapure water, stirring evenly and pouring into the hydrothermal reaction kettle; S6: placing the hydrothermal reactor in a drying oven, setting a certain heating and insulation curve, and obtaining manganese tetraoxide slurry after the reaction is complete; S7: filtering, rinsing and drying the manganese tetraoxide slurry to obtain a manganese tetraoxide powder product.

2. The method for preparing a bio-friendly spherical nano manganese tetraoxide according to claim 1, characterized in that: In step S1, the manganese salt is one or more of manganese chloride, manganese acetate, and manganese gluconate, and the concentration of manganese ions in the manganese salt solution is 0.5-1 mol / L.

3. The method for preparing a bio-friendly spherical nano manganese tetraoxide according to claim 1, characterized in that: In the step S2, the amount of catalyst added is 1-10% of the mass of manganese ions, and the amount of modifier added is 5-15% of the mass of manganese ions.

4. The method for preparing a bio-friendly spherical nano-manganese tetraoxide according to claim 1, characterized in that: The alkaline solution in step S3 is one or more of sodium hydroxide solution, potassium hydroxide solution, and ammonia solution, and the concentration of the alkaline solution is 1 to 6 mol / L; the acidic solution in step S4 is one or more of phosphoric acid, formic acid, acetic acid, and citric acid, and the concentration of the acidic solution is 1 to 6 mol / L.

5. The method for preparing a bio-friendly spherical nano manganese tetraoxide according to claim 1, characterized in that: In step S5, the pH value of the manganese salt solution is adjusted to 4-6.

6. The method for preparing a bio-friendly spherical nano manganese tetraoxide according to claim 1, characterized in that: In the step S5, after the ultrapure water is added, the manganese ion concentration in the solution is 0.25-0.5 mol / L, and the volume of the solution is 20-50% of the total volume of the lining of the hydrothermal reactor.

7. The method for preparing a bio-friendly spherical nano manganese tetraoxide according to claim 1, characterized in that: In step S6, the heating and heat preservation curve is to heat to 150°C at a rate of 1-5°C / min and then keep the temperature for 8-10 hours.

8. The method for preparing a bio-friendly spherical nano manganese tetraoxide according to claim 1, characterized in that: In step S7, rinsing means repeatedly washing with ultrapure water for 3 times or more to remove other free ions in the object to be washed; the drying temperature is 60 to 80° C., and the drying time is 8 to 16 hours.

9. A bio-friendly spherical nano manganese tetraoxide product prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The manganese tetraoxide product is added to the environment system where biological cells are located, does not inhibit the growth of the biological cells, and does not reduce the survival rate of the biological cells.

10. The bio-friendly spherical nano manganese tetraoxide product according to claim 9, characterized in that: The impurity content of Pb in the manganese tetraoxide product is less than 500 ppb, the impurity content of Cd is less than 500 ppb, the impurity content of Sn is less than 50 ppm, the impurity content of Ni is less than 1 ppm, the impurity content of Cr is less than 1 ppm, and the impurity content of Cu is less than 10 ppm. The particle size D50 of the manganese tetraoxide product is 50 to 500 nm, and the specific surface area is 10 to 20 m 2 / g.

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