A method for preparing iron oxide with controllable grain morphology

Abstract

The invention provides a method for preparing iron oxide with controllable grain morphology, which belongs to the field of nano inorganic materials. The method comprises the following steps: preparing Fe(OH)3 precipitation, growing crystal particles, washing and baking. The method of the invention obtains iron oxide with desired morphology and grain size by controlling the growth rate and growth mode of iron oxide, thereby improving one or more performance indicators of iron oxide such as specific surface area, fluidity, and bulk density. In addition, the grain size distribution of iron oxide is concentrated and has good uniformity, which can meet the different needs of different industries for the use of iron oxide.

Description

Technical Field

[0001] The invention relates to a method for preparing iron oxide with controllable grain morphology, belonging to the technical field of inorganic nano materials. Background Art

[0002] Iron oxide is widely used in the fields of pigments and coatings, biomedicine, electronic materials, catalysts, etc. Different fields of application have different requirements for the performance indicators of iron oxide. Therefore, by changing the morphology and grain size of iron oxide to change one or more performance indicators such as the specific surface area, fluidity, and bulk density of iron oxide, the performance requirements of iron oxide in different application scenarios can be met.

[0003] CN117511251A discloses a method for preparing a surface hydrophobically modified nano iron oxide, which comprises adding nano iron oxide to a solvent and then adding 3-aminopropyltriethoxysilane to react to obtain a graft-modified nano iron oxide, and adding the graft-modified nano iron oxide and lauric acid to dichloromethane to react to obtain a surface hydrophobically modified nano iron oxide. The principle of this method is that the reaction between the nano iron oxide and the solvent and the additive changes its surface characteristics.

[0004] CN111825123A discloses a method for preparing iron oxide with different crystal forms, which prepares an Fe precursor by using an Fe salt and an alkaline compound aqueous solution containing an alkali metal, and adjusts the content of α crystal form and γ crystal form in the iron oxide after calcination by controlling the content of the alkali metal remaining in the Fe precursor. The principle of this method is to control the content of the alkali metal in the Fe precursor to change the crystal form of the iron oxide after calcination.

[0005] Of the two mentioned above, the former studies the surface hydrophobic properties of iron oxide, while the latter studies the crystal structure of iron oxide. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing iron oxide with controllable grain morphology.

[0007] The present invention provides a method for preparing iron oxide with controllable grain morphology, comprising the following steps: step a, preparing Fe(OH)3 precipitate

[0008] (a1) Impurity removal: Fe 2+ The salt solid dissolves in water to obtain Fe 2+ Salt solution, Fe 2+ The concentration of the salt solution is 1-5 mol / L. Add flocculant and stir evenly. Filter the particles in the solution to obtain Fe 2+ Saline solution;

[0009] (a2) Oxidation: placing the solution obtained in (a1) in a water bath at a temperature of 75-95° C., and introducing air or oxygen into the solution to oxidize it;

[0010] (a3) Filtration: Filter the liquid obtained in (a2) to obtain Fe(OH)3 precipitate;

[0011] Step b: growing crystal particles

[0012] (b1) Mixing and slurrying: taking Fe(OH)3 precipitate and adding solvent to stir and slurry and mix evenly, the solvent includes water or ethanol, and obtaining a mixed solution of solvent and Fe(OH)3, the density of the mixed solution of solvent and Fe(OH)3 is 0.8-3.0g / ml;

[0013] (b2) Hydrothermal reaction: Pour the mixture obtained from (b1) or (a2) into a hydrothermal reactor, control the reaction temperature to be 80-210°C, and the reaction time to be 6-24h;

[0014] Step c: washing and baking

[0015] (c1) Filtration and washing: filtering the mixture obtained in (b2), and washing the solid obtained by filtration with water or alcohol;

[0016] (c2) Calcination: The solid obtained in (c1) is placed in a kiln and calcined at a temperature of 100-800°C for 0.3-3h to obtain iron oxide.

[0017] In the step (a1), Fe 2+ Salts include but are not limited to FeSO4, FeCl2, Fe(NO3)2, two or more mixed Fe 2+ Salt.

[0018] In the step (a2), the methods of introducing air or oxygen include but are not limited to aeration and spraying.

[0019] In the step (c2), the kiln includes but is not limited to a tubular furnace, a muffle furnace, a rotary kiln, and a push plate kiln.

[0020] The specific methods for controlling different grain morphologies are as follows.

[0021] Take FeSO4 solid and dissolve it in water to prepare 1 mol / L FeSO4 solution, add flocculant to the solution and stir it evenly, then filter the particles in the solution to obtain pure FeSO4 solution, put the obtained solution in a 75°C water bath, use an aeration head to pass air into the solution to oxidize it, filter the liquid to obtain Fe(OH)3 precipitate;

[0022] Take a small amount of Fe(OH)3 precipitate and add a certain amount of ethanol to stir and slurry and mix evenly to obtain a Fe(OH)3 ethanol mixed solution with a density of 0.8g / ml. Pour it into a hydrothermal kettle and control the temperature of the hydrothermal kettle to 80℃ for 6h.

[0023] The obtained liquid was filtered, and the filtered solid was washed with deionized water, placed in a muffle furnace and baked at 100° C. for 3 hours to obtain needle-rod-shaped iron oxide crystals.

[0024] Take FeCl2 solid and dissolve it in water to prepare a 2.5 mol / L FeCl2 solution, add a flocculant to the FeCl2 solution and stir it evenly, then filter the particles in the solution to obtain a pure FeCl2 solution, place the obtained solution in a water bath at 80°C, use an aeration head to pass air into the solution to oxidize it, filter the liquid to obtain Fe(OH)3 precipitation;

[0025] Take the Fe(OH)3 precipitate, add a certain amount of water, stir and slurry, mix evenly, and obtain a mixture of Fe(OH)3 and water with a density of 1.5g / ml. Pour it into a hydrothermal kettle, control the temperature of the hydrothermal kettle to 120℃, and react for 12h.

[0026] The obtained liquid was filtered, and the filtered solid was washed with deionized water, placed in a muffle furnace and baked at 300° C. for 2 h to obtain oval-shaped iron oxide crystals.

[0027] Take FeCl2 solid and dissolve it in water to prepare a 4 mol / L FeCl2 solution, add a flocculant to the solution and stir it evenly, then filter the particles in the solution to obtain a pure FeCl2 solution, place the obtained solution in a 90°C water bath, use an aeration head to pass air into the solution to oxidize it, filter the liquid to obtain Fe(OH)3 precipitate;

[0028] Take the Fe(OH)3 precipitate, add a certain amount of water, stir and slurry, mix evenly, and obtain a mixture of Fe(OH)3 and water with a density of 2.2g / ml. Pour it into a hydrothermal kettle, control the temperature of the hydrothermal kettle to 170℃, and react for 18h.

[0029] The obtained liquid is filtered, and the filtered solid is washed with deionized water, placed in a tube furnace and baked at 600° C. for 1 hour to obtain square-shaped iron oxide crystals.

[0030] Take FeCl2 solid and dissolve it in water to prepare a 5 mol / L FeCl2 solution, add a flocculant to the solution and stir it evenly, then filter the particles in the solution to obtain a pure FeCl2 solution, place the obtained solution in a 95°C water bath, use an aeration head to pass air into the solution to oxidize it, filter the liquid to obtain Fe(OH)3 precipitation;

[0031] Take the Fe(OH)3 precipitate, add a certain amount of water, stir and slurry, mix evenly, and obtain a mixture of Fe(OH)3 and water with a density of 3.0 g / ml. Pour it into a hydrothermal kettle, control the temperature of the hydrothermal kettle to 210°C, and react for 24 hours.

[0032] The obtained liquid was filtered, and the filtered solid was washed with deionized water, placed in a tubular furnace and baked at 800° C. for 0.3 h to obtain capsule-shaped crystals of iron oxide.

[0033] The present invention provides a method for preparing morphology-controllable iron oxide, which can stably control the morphology and grain size of the iron oxide, and has a simple operation process. The method of the present invention obtains iron oxide with a desired morphology and grain size by controlling the growth rate and growth mode of the iron oxide, thereby improving one or more performance indicators of the iron oxide, such as specific surface area, fluidity, and bulk density, and the iron oxide has a concentrated grain size distribution and good uniformity, and can meet different needs of different industries for the use of iron oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a scanning electron microscope image of the iron oxide prepared in Example 1.

[0035] Figure 2 This is a scanning electron microscope image of the iron oxide prepared in Example 2.

[0036] Figure 3 This is a scanning electron microscope image of the iron oxide prepared in Example 3.

[0037] Figure 4 This is a scanning electron microscope image of the iron oxide prepared in Example 4. DETAILED DESCRIPTION

[0038] Example 1

[0039] (1) Preparation of Fe(OH)3 precipitate

[0040] (1-1) Impurity removal: Take FeSO4 solid and dissolve it in water to prepare a 1 mol / L FeSO4 solution. Add flocculant to the solution and stir it evenly. Then filter the particulate matter in the solution to obtain a pure FeSO4 solution.

[0041] (1-2) Oxidation: The solution obtained in (1-1) was placed in a water bath at 75°C and air was introduced into the solution using an aeration head to oxidize it.

[0042] (1-3) Filtration: Filter the liquid obtained in (1-2) to obtain Fe(OH)3 precipitate.

[0043] (2) Growth of crystal particles

[0044] (2-1) Mixing and slurrying: Take a small amount of Fe(OH)3 precipitate and add a certain amount of ethanol to stir and slurry and mix evenly to obtain a Fe(OH)3 ethanol mixed solution with a density of 0.8 g / ml.

[0045] (2-2) Hydrothermal reaction: Pour the liquid obtained in (2-1) or (1-2) into a hydrothermal reactor, control the temperature of the hydrothermal reactor to 80°C, and react for 6 hours.

[0046] (3) Washing and drying

[0047] (3-1) Filtration and washing: The liquid obtained in (2-2) is filtered, and the solid obtained by filtration is washed with deionized water.

[0048] (3-2) Calcination: The solid obtained in (3-1) was placed in a muffle furnace and calcined at 100°C for 3 h to obtain needle-shaped iron oxide with a grain size of 0.161-0.810 μm. Figure 1 shown.

[0049] Example 2

[0050] (1) Preparation of Fe(OH)3 precipitate

[0051] (1-1) Impurity removal: Take FeCl2 solid and dissolve it in water to prepare a 2.5 mol / L FeCl2 solution. Add flocculant to the solution and stir it evenly. Then filter the particulate matter in the solution to obtain a pure FeCl2 solution.

[0052] (1-2) Oxidation: The solution obtained in (1-1) was placed in a water bath at 80°C and air was introduced into the solution using an aeration head to oxidize it.

[0053] (1-3) Filtration: Filter the liquid obtained in (1-2) to obtain Fe(OH)3 precipitate.

[0054] (2) Growth of crystal particles

[0055] (2-1) Mixing and slurrying: Take the Fe(OH)3 precipitate, add a certain amount of water, stir and slurry and mix evenly to obtain a mixture of Fe(OH)3 and water with a density of 1.5 g / ml.

[0056] (2-2) Hydrothermal reaction: Pour the liquid obtained in (2-1) or (1-2) into a hydrothermal kettle, control the temperature of the hydrothermal kettle to 120°C, and react for 12 hours.

[0057] (3) Washing and baking

[0058] (3-1) Filtration and washing: The liquid obtained in (2-2) is filtered, and the solid obtained by filtration is washed with deionized water.

[0059] (3-2) Calcination: The solid obtained in (3-1) was placed in a muffle furnace and calcined at 300°C for 2 h to obtain an oval iron oxide with a grain size of 0.989-1.11 μm. Figure 2 shown.

[0060] Example 3

[0061] (1) Preparation of Fe(OH)3 precipitate

[0062] (1-1) Impurity removal: Take FeCl2 solid and dissolve it in water to prepare a 4 mol / L FeCl2 solution. Add flocculant to the solution and stir it evenly. Then filter the particulate matter in the solution to obtain a pure FeCl2 solution.

[0063] (1-2) Oxidation: The solution obtained in (1-1) was placed in a water bath at 90°C and air was introduced into the solution using an aeration head to oxidize it.

[0064] (1-3) Filtration: Filter the liquid obtained in (1-2) to obtain Fe(OH)3 precipitate.

[0065] (2) Growth of crystal particles

[0066] (2-1) Mixing and slurrying: Take the Fe(OH)3 precipitate, add a certain amount of water, stir and slurry and mix evenly to obtain a mixed solution of Fe(OH)3 and water with a density of 2.2 g / ml.

[0067] (2-2) Hydrothermal reaction: Pour the liquid obtained in (2-1) or (1-2) into a hydrothermal reactor, control the temperature of the hydrothermal reactor to 170°C, and react for 18 hours.

[0068] (3) Washing and baking

[0069] (3-1) Filtration and washing: The liquid obtained in (2-2) is filtered, and the solid obtained by filtration is washed with deionized water.

[0070] (3-2) Calcination: The solid obtained in (3-1) was placed in a tube furnace and calcined at 600°C for 1 h to obtain a block-shaped iron oxide with a grain size of 1.68-1.93 μm. Figure 3 shown.

[0071] Example 4

[0072] (1) Preparation of Fe(OH)3 precipitate

[0073] (1-1) Impurity removal: Take FeCl2 solid and dissolve it in water to prepare a 5 mol / L FeCl2 solution. Add flocculant to the solution and stir it evenly. Then filter the particulate matter in the solution to obtain a pure FeCl2 solution.

[0074] (1-2) Oxidation: The solution obtained in (1-1) was placed in a water bath at 95°C and air was introduced into the solution using an aeration head to oxidize it.

[0075] (1-3) Filtration: Filter the liquid obtained in (1-2) to obtain Fe(OH)3 precipitate.

[0076] (2) Growth of crystal particles

[0077] (2-1) Mixing and slurrying: Take the Fe(OH)3 precipitate, add a certain amount of water, stir and slurry and mix evenly to obtain a mixture of Fe(OH)3 and water with a density of 3.0 g / ml.

[0078] (2-2) Hydrothermal reaction: Pour the liquid obtained in (2-1) or (1-2) into a hydrothermal kettle, control the temperature of the hydrothermal kettle to 210°C, and react for 24 hours.

[0079] (3) Washing and baking

[0080] (3-1) Filtration and washing: The liquid obtained in (2-2) is filtered, and the solid obtained by filtration is washed with deionized water.

[0081] (3-2) Calcination: The solid obtained in (3-1) was placed in a tube furnace and calcined at 800°C for 0.3 h to obtain capsule-shaped iron oxide with a grain size of 3.42-5.12 μm. Figure 4 shown.

[0082] Summary of the Examples

[0083] The iron oxide prepared in Example 1 is needle-rod-shaped, with a grain size of about 0.161-0.810 um, and is a nano-scale iron oxide particle. Iron oxide of this size and shape has a very high specific surface area and adhesion, but its loose density and fluidity are relatively small.

[0084] The iron oxide prepared in Example 2 is in the shape of an egg, and the grain size is about 0.989-1.11um. The iron oxide of this morphology and size has a higher specific surface area, better fluidity and greater bulk density than the needle-shaped iron oxide, and is an iron oxide with relatively balanced indicators.

[0085] The iron oxide prepared in Example 3 is in a block shape with a grain size of about 1.68-1.93 um. The specific surface area of ​​the iron oxide of this size is small, but its fluidity is good and it has a very high bulk density because the block shape enables it to be densely packed.

[0086] The iron oxide prepared in Example 4 is in the shape of a capsule, with a grain size of about 3.42-5.12 um. The specific surface area of ​​the iron oxide of this size is very small, but it has excellent fluidity and a high bulk density.

[0087] The method for preparing iron oxide provided by the present invention can not only achieve the effect of changing the morphology and grain size of iron oxide by controlling the growth rate and mode of iron oxide, thereby improving one or more performance indicators of iron oxide such as specific surface area, fluidity, and loose density, but also the grain size distribution of iron oxide is concentrated and has good uniformity, which can meet the different needs of different industries for the use of iron oxide.

Claims

1. A method for preparing iron oxide with controllable grain morphology, characterized in that: The steps include: Step a: Preparation of Fe(OH)3 precipitate (a1) Impurity removal: Fe 2+ The salt solid dissolves in water to obtain Fe 2+ Salt solution, Fe 2+ The concentration of the salt solution is 1-5 mol / L. Add flocculant and stir evenly. Filter the particles in the solution to obtain Fe 2+ Saline solution; (a2) Oxidation: placing the solution obtained in (a1) in a water bath at a temperature of 75-95° C., and introducing air or oxygen into the solution to oxidize it; (a3) Filtration: Filter the liquid obtained in (a2) to obtain Fe(OH)3 precipitate; Step b: growing crystal particles (b1) Mixing and slurrying: taking Fe(OH)3 precipitate and adding solvent to stir and slurry and mix evenly, the solvent includes water or ethanol, and obtaining a mixed solution of solvent and Fe(OH)3, the density of the mixed solution of solvent and Fe(OH)3 is 0.8-3.0g / ml; (b2) Hydrothermal reaction: Pour the mixture obtained from (b1) or (a2) into a hydrothermal reactor, control the reaction temperature to be 80-210°C, and the reaction time to be 6-24h; Step c: washing and baking (c1) Filtration and washing: filtering the mixture obtained in (b2), and washing the solid obtained by filtration with water or alcohol; (c2) Calcination: The solid obtained from (c1) is placed in a kiln and calcined at a temperature of 100-800°C for 0.3-3 hours to obtain iron oxide.

2. The preparation method according to claim 1, characterized in that: In the step (a1), Fe 2+ Salts include but are not limited to FeSO4, FeCl2, Fe(NO3)2, two or more mixed Fe 2+ Salt.

3. The preparation method according to claim 1, characterized in that: In the step (a2), the methods of introducing air or oxygen include but are not limited to aeration and spraying.

4. The preparation method according to claim 1, characterized in that: In the step (c2), the kiln includes but is not limited to a tubular furnace, a muffle furnace, a rotary kiln or a pusher kiln.

5. The preparation method according to claim 1, characterized in that : Take FeSO4 solid and dissolve it in water to prepare 1 mol / L FeSO4 solution, add flocculant to the solution and stir it evenly, then filter the particles in the solution to obtain pure FeSO4 solution, put the obtained solution in a 75°C water bath, use an aeration head to pass air into the solution to oxidize it, filter the liquid to obtain Fe(OH)3 precipitate; Take a small amount of Fe(OH)3 precipitate and add a certain amount of ethanol to stir and slurry and mix evenly to obtain a Fe(OH)3 ethanol mixed solution with a density of 0.8g / ml. Pour it into a hydrothermal kettle and control the temperature of the hydrothermal kettle to 80℃ for 6h. The obtained liquid was filtered, and the filtered solid was washed with deionized water, placed in a muffle furnace and baked at 100° C. for 3 hours to obtain needle-rod-shaped iron oxide particles.

6. The preparation method according to claim 1, characterized in that : Take FeCl2 solid and dissolve it in water to prepare a 2.5 mol / L FeCl2 solution, add a flocculant to the FeCl2 solution and stir it evenly, then filter the particles in the solution to obtain a pure FeCl2 solution, place the obtained solution in a water bath at 80°C, use an aeration head to pass air into the solution to oxidize it, filter the liquid to obtain Fe(OH)3 precipitation; Take the Fe(OH)3 precipitate, add a certain amount of water, stir and slurry, mix evenly, and obtain a mixture of Fe(OH)3 and water with a density of 1.5g / ml. Pour it into a hydrothermal kettle, control the temperature of the hydrothermal kettle to 120℃, and react for 12h; The obtained liquid was filtered, and the filtered solid was washed with deionized water, placed in a muffle furnace and baked at 300° C. for 2 h to obtain oval-shaped iron oxide crystals.

7. The preparation method according to claim 1, characterized in that : Take FeCl2 solid and dissolve it in water to prepare a 4 mol / L FeCl2 solution, add a flocculant to the solution and stir it evenly, then filter the particles in the solution to obtain a pure FeCl2 solution, place the obtained solution in a 90°C water bath, use an aeration head to pass air into the solution to oxidize it, filter the liquid to obtain Fe(OH)3 precipitate; Take the Fe(OH)3 precipitate, add a certain amount of water, stir and slurry, mix evenly, and obtain a mixture of Fe(OH)3 and water with a density of 2.2g / ml. Pour it into a hydrothermal kettle, control the temperature of the hydrothermal kettle to 170℃, and react for 18h. The obtained liquid is filtered, and the filtered solid is washed with deionized water, placed in a tube furnace and baked at 600° C. for 1 hour to obtain square-shaped iron oxide crystals.

8. The preparation method according to claim 1, characterized in that : Take FeCl2 solid and dissolve it in water to prepare a 5 mol / L FeCl2 solution, add a flocculant to the solution and stir it evenly, then filter the particles in the solution to obtain a pure FeCl2 solution, place the obtained solution in a 95°C water bath, use an aeration head to pass air into the solution to oxidize it, filter the liquid to obtain Fe(OH)3 precipitation; Take the Fe(OH)3 precipitate, add a certain amount of water, stir and slurry, mix evenly, and obtain a mixture of Fe(OH)3 and water with a density of 3.0 g / ml. Pour it into a hydrothermal kettle, control the temperature of the hydrothermal kettle to 210°C, and react for 24 hours. The obtained liquid was filtered, and the filtered solid was washed with deionized water, placed in a tubular furnace and baked at 800° C. for 0.3 h to obtain capsule-shaped crystals of iron oxide.

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