A method for preparing Fe3O4 magnetic nanoparticles using aerosol technology

Abstract

The present invention discloses a method for preparing Fe3O4 magnetic nanoparticles by aerosol technology, which belongs to the technical field of material preparation. The method comprises the following steps: (1) preparing a precursor solution: preparing Fe3O4 magnetic nanoparticles by aerosol technology; 2+ and Fe 3+ The iron salt solution is prepared according to a certain molar ratio, which is a precursor solution; (2) atomization: atomizing the precursor solution into an aerosol; (3) evaporation and drying: removing the residual solvent by evaporation, and drying to form solid particles; (4) sintering and filtering: sintering the particles at high temperature in a heating chamber to form nanoparticles with high crystallinity; filtering the tail gas, and cooling to obtain the final product, Fe3O4 magnetic nanoparticles. The present invention is a method for preparing Fe3O4 magnetic nanoparticles under gas phase conditions, which has the advantages of high efficiency, low cost, continuous production and green and pollution-free production process. The particle size of the prepared Fe3O4 nanoparticles meets the requirements of magnetic fluid and medical nuclear magnetic resonance (MRI).

Description

Technical Field

[0001] The invention relates to the technical field of material preparation, and in particular to a method for preparing Fe3O4 magnetic nanoparticles using aerosol technology. Background Art

[0002] Nanomaterials have unique and excellent mechanical, electromagnetic, optical and chemical material properties, and have shown broad application prospects in the fields of chemical engineering, metallurgy, environment, electronics, biology, medicine, aerospace, etc. Magnetic nanoparticles (NPs) have the characteristics of nanomaterials, and also have the characteristics of biocompatibility and biodegradability, which makes them widely used in magnetic fluids, biological separation detection, targeted drugs and medical imaging.

[0003] There are many methods for synthesizing Fe3O4 magnetic nanoparticles, including coprecipitation, thermal decomposition, microemulsion and sol-gel methods. However, these methods are all synthesized in liquid phase. The manufacturing difficulty through these chemical processes is large and will cause environmental pollution. The obtained nanoparticles are large in size and uneven in particle size distribution. There are some defects in practical application. For example, in the medical field, magnetic nanoparticles are used for targeted therapy. If the particle size is too large, it may cause blood vessel blockage and thrombosis, which seriously endangers the patient's life. Therefore, there is an urgent need for a method for synthesizing Fe3O4 magnetic nanoparticles with smaller nanoparticle size and uniform particle size distribution. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing Fe3O4 magnetic nanoparticles by aerosol technology to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The technical solution of the present invention provides a method for preparing Fe3O4 magnetic nanoparticles using aerosol technology, comprising the following steps:

[0007] (1) Precursor solution configuration: Fe 2+ and Fe 3+ The iron salt solution is prepared according to a certain molar ratio to form a precursor solution;

[0008] (2) Atomization: atomizing the precursor solution into an aerosol;

[0009] (3) Evaporative drying: removing excess solvents such as water by evaporation and drying to form solid particles;

[0010] (4) Sintering and filtration: The particles are sintered at high temperature in a heating chamber to form nanoparticles with high crystallinity; the exhaust gas is filtered and cooled to obtain the final product, Fe3O4 magnetic nanoparticles.

[0011] Based on the above technical solution, the present invention has the following technical effects:

[0012] The present invention discloses a method for preparing Fe3O4 magnetic nanoparticles under gas phase conditions, which has the advantages of high efficiency, low cost, continuous production and green and pollution-free production process. The average particle size of the prepared Fe3O4 nanoparticles is 8-10nm, and the particle size distribution is uniform. The particle size and particle size distribution meet the requirements of magnetic fluid and medical nuclear magnetic resonance (MRI) at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 Flow chart for the preparation of Fe3O4 magnetic nanoparticles using a novel aerosol method;

[0015] Figure 2 Detailed steps of the experiment;

[0016] Figure 3 It is a schematic diagram of the atomization process structure;

[0017] Figure 4 This is the SEM image of Fe3O4 nanoparticles. DETAILED DESCRIPTION

[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0019] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0020] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0021] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0022] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0023] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or are publicly available.

[0024] The embodiment of the present invention provides a method for preparing Fe3O4 magnetic nanoparticles using aerosol technology, comprising the following steps:

[0025] (1) Precursor solution configuration: Fe 2+ and Fe 3+ The iron salt solution is prepared according to a certain molar ratio to form a precursor solution;

[0026] (2) Atomization: atomizing the precursor solution into an aerosol;

[0027] (3) Evaporative drying: removing residual solvent by evaporation and drying to form solid particles;

[0028] (4) Sintering and filtration: The particles are sintered at high temperature in a heating furnace to form nanoparticles with high crystallinity; the exhaust gas is filtered and cooled to obtain the final product, Fe3O4 magnetic nanoparticles.

[0029] In some specific embodiments, the precursor solution contains Fe 2+ with Fe 3+ The molar ratio is 1:1.75-2; the precursor solution also contains ammonia water and tetramethylammonium hydroxide.

[0030] In some specific embodiments, the precursor solution is an iron salt solution in which a molar ratio of FeCl2 solution to FeCl3 solution is 1:1.75-2.

[0031] In some specific embodiments, the mixed solution contains Fe 2+ The concentration of Fe is 0.5 mol / L. 3+ It is 0.875~1.0mol / L.

[0032] In some specific embodiments, the pH of the precursor solution is 9-10; the precursor solution further comprises tetramethylammonium hydroxide.

[0033] In some specific embodiments, the pH of the precursor solution is adjusted to 9-10 using aqueous ammonia.

[0034] In some specific embodiments, the concentration of ammonia water NH3·H2O is 25%, and the amount of tetramethylammonium hydroxide used is 1 ml.

[0035] For strong and weak bases of the same concentration, the pH of the strong base is greater, and the OH - Too high a concentration will lead to faster reaction speed and larger particle diameter. - The consumption is faster, while the weak base will slowly ionize and form particles with smaller diameters. Therefore, the use of ammonia water is more conducive to the formation of particles with smaller particle sizes.

[0036] In some specific embodiments, the tetramethylammonium hydroxide and Fe 2+ The molar ratio is 1:1.

[0037] In some specific embodiments, the atomization is specifically: atomizing the precursor solution into small droplets, and the atomization pressure is 0.1 MPa.

[0038] In some specific embodiments, the precursor solution is processed by a nebulizer to obtain an aerosol gas flow, including: the precursor solution is placed in a beaker, entering through a feed tube and compressed by a peristaltic pump, reaching the nebulizer for atomization to form uniform aerosol particles, and the aerosolized particles are carried by a carrier gas to form aerosol droplets.

[0039] In some specific embodiments, the evaporative drying is carried out at a temperature of 60° C. and for 30 minutes.

[0040] In some specific embodiments, the high temperature sintering is specifically: raising the temperature of the heating chamber to 300° C. at a heating rate of 2° C. / min, and sintering at 300° C. for 2 hours.

[0041] Example 1

[0042] A novel method for preparing Fe3O4 magnetic nanoparticles using aerosol technology, the flow chart and structural schematic diagram are as follows Figure 1-3 As shown, the following steps are included:

[0043] Step 1: Take 5.56g of ferrous sulfate heptahydrate (FeSO4·7H2O) and 10.8g of ferric chloride hexahydrate (FeCl3·6H2O) and dissolve them in deionized water to obtain Fe 2+ :Fe 3 =1:2 mixed solution. 25%wt ammonia water and 1 ml tetramethylammonium hydroxide as a dispersant were added dropwise to the mixed solution, and the mixture was stirred evenly during the process until the pH value of the solution was 9 and the solution gradually changed from brown to black. Finally, ultrasonic dispersion was performed for 30 minutes to obtain a precursor solution;

[0044] Step 2: The precursor solution enters from the feed pipe, is compressed and accelerated by the peristaltic pump to reach the atomizer, and is atomized and dispersed into small droplets. The atomization pressure is 0.1MPa, the atomization carrier gas is nitrogen, the carrier gas A inlet flow rate is 120sccm, and the carrier gas B dilution flow rate is 90sccm.

[0045] Step 3: Evaporation drying: The Fe3O4 particles enter the drying chamber (initial temperature is 60°C), and the water and organic solvent on the surface will begin to evaporate. Continue drying for 30 minutes, and finally form solid particles and enter the collection bottle;

[0046] Step 4: Collect the Fe3O4 particles in a crucible and place it in a tubular heating furnace (initial temperature is 22°C). Introduce argon to protect the reaction gaseous atmosphere, and raise the temperature of the heating chamber to 300°C at a heating rate of 2°C / min. Sinter at 300°C for 2h to densify the particles and improve the particle crystallinity. Finally, after filtering the tail gas and cooling to room temperature, take out the final product, Fe3O4 magnetic nanoparticles.

[0047] Example 2

[0048] A novel method for preparing Fe3O4 magnetic nanoparticles using aerosol technology, the flow chart and structural schematic diagram are as follows Figure 1-3 As shown, based on Example 1, the Fe content in the solution was changed 2+ and Fe 3+ Ratio. It includes the following steps: +

[0049] Step 1: Take 5.56g of ferrous sulfate heptahydrate (FeSO4·7H2O) and 9.45g of ferric chloride hexahydrate (FeCl3·6H2O) and dissolve them in deionized water to obtain Fe 2+ :Fe 3 =1:1.75 mixed solution. 25%wt ammonia water and 1 ml tetramethylammonium hydroxide as a dispersant were added to the mixed solution, and the mixture was stirred evenly until the pH value of the solution was 9 and the solution gradually changed from brown to black. Finally, ultrasonic dispersion was performed for 30 minutes to obtain a precursor solution;

[0050] Steps 2-4 are the same as in Example 1.

[0051] Example 3

[0052] A novel method for preparing Fe3O4 magnetic nanoparticles using aerosol technology, the flow chart and structural schematic diagram are as follows Figure 1-3 As shown, based on Example 1, the Fe content in the solution was changed 2+ and Fe 3+ The ratio and the pH value of the mixed solution are adjusted, comprising the following steps:

[0053] Step 1: Take 5.56g of ferrous sulfate heptahydrate (FeSO4·7H2O) and 9.45g of ferric chloride hexahydrate (FeCl3·6H2O) and dissolve them in deionized water to obtain Fe 2+ :Fe 3 =1:1.75 mixed solution. 25%wt ammonia water and 1 ml tetramethylammonium hydroxide as a dispersant were added dropwise to the mixed solution, and the mixture was stirred evenly during the process until the pH value of the solution was 10 and the solution gradually changed from brown to black. Finally, ultrasonic dispersion was performed for 30 minutes to obtain a precursor solution;

[0054] Steps 2-4 are the same as in Example 1.

[0055] Example 4

[0056] A novel method for preparing Fe3O4 magnetic nanoparticles using aerosol technology, the flow chart and structural schematic diagram are as follows Figure 1-3 As shown, based on Example 1, a 25% mass fraction NaOH solution is used instead of NH3·H2O to adjust the pH value of the solution to form a precipitate. The following steps are included:

[0057] Step 1: Take 5.56g of ferrous sulfate heptahydrate (FeSO4·7H2O) and 10.8g of ferric chloride hexahydrate (FeCl3·6H2O) and dissolve them in deionized water to obtain Fe 2+ :Fe 3 =1:2 mixed solution. 25%wt NaOH solution and 1 ml tetramethylammonium hydroxide as a dispersant were added dropwise to the mixed solution, and the mixture was stirred evenly until the pH value of the solution was 9 and the solution gradually changed from brown to black. Finally, ultrasonic dispersion was performed for 30 minutes to obtain a precursor solution;

[0058] Steps 2-4 are the same as in Example 1.

[0059] Example 5

[0060] A novel method for preparing Fe3O4 magnetic nanoparticles using aerosol technology, the flow chart and structural schematic diagram are as follows Figure 1-3As shown, based on Example 2, a 25% mass fraction NaOH solution is used instead of NH3·H2O to adjust the pH value of the solution to form a precipitate. The following steps are included:

[0061] Step 1: Take 5.56g of ferrous sulfate heptahydrate (FeSO4·7H2O) and 9.45g of ferric chloride hexahydrate (FeCl3·6H2O) and dissolve them in deionized water to obtain Fe 2+ :Fe 3 =1:1.75 mixed solution. 25%wt NaOH solution and 1 ml tetramethylammonium hydroxide as a dispersant were added dropwise to the mixed solution, and the mixture was stirred evenly during the process until the pH value of the solution was 9 and the solution gradually changed from brown to black. Finally, ultrasonic dispersion was performed for 30 minutes to obtain a precursor solution;

[0062] Steps 2-4 are the same as in Example 1.

[0063] Example 6

[0064] A novel method for preparing Fe3O4 magnetic nanoparticles using aerosol technology, the flow chart and structural schematic diagram are as follows Figure 1-3 As shown, based on Example 3, a 25% NaOH solution is used instead of NH3·H2O to adjust the pH value of the solution to form a precipitate, comprising the following steps:

[0065] Step 1: Take 5.56g of ferrous sulfate heptahydrate (FeSO4·7H2O) and 9.45g of ferric chloride hexahydrate (FeCl3·6H2O) and dissolve them in deionized water to obtain Fe 2+ :Fe 3 =1:.1.75 mixed solution. 25%wt NaOH solution and 1 ml tetramethylammonium hydroxide as a dispersant were added dropwise to the mixed solution, and the mixture was stirred evenly during the process until the pH value of the solution was 10 and the solution gradually changed from brown to black. Finally, ultrasonic dispersion was performed for 30 minutes to obtain a precursor solution;

[0066] Steps 2-4 are the same as in Example 1.

[0067] The average particle size of the Fe3O4 magnetic nanoparticles prepared in each example is shown in Table 1.

[0068] Table 1 Average particle size of Fe3O4 magnetic nanoparticles obtained in different experimental examples

[0069] Example <![CDATA[Fe 2+ :Fe 3+ ]]> Adjusting pH pH Adjustment Chemicals <![CDATA[Average particle size of Fe3O4]]> 1 1:2 9 25%wt ammonia water 10nm 2 1:1.75 9 25%wt ammonia water 8.5nm 3 1:1.75 10 25%wt ammonia water 8nm 4 1:2 9 25%wtNaOH 16nm 5 1:1.75 9 25%wtNaOH 15nm 6 1:1.75 10 25%wtNaOH 14nm

[0070] As can be seen from Table 1, the Fe3O4 nanoparticles prepared by the method for Fe3O4 magnetic nanoparticles provided by the present invention have an average particle size of 8-10 nm and a uniform particle size distribution. The particle size and particle size distribution simultaneously meet the requirements of magnetic fluid and medical magnetic resonance imaging (MRI).

[0071] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technical users in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing Fe3O4 magnetic nanoparticles using aerosol technology, characterized in that: The following steps are involved: (1) Precursor solution preparation: Fe 2+ and Fe 3+ The precursor solution is prepared by a molar ratio of 1: (1.75-2) to form an iron salt solution; the precursor solution also contains ammonia water and tetramethylammonium hydroxide; the pH of the precursor solution is adjusted to 9-10 by using ammonia water; the tetramethylammonium hydroxide and Fe 2+ The molar ratio is 1:1; (2) Atomization: atomizing the precursor solution into an aerosol; (3) Evaporation drying: removing the residual solvent by evaporation and drying to form solid particles; the evaporation drying temperature is 60° C. and the time is 30 min; (4) Sintering and filtration: The particles are sintered at high temperature in a heating chamber to form nanoparticles with high crystallinity; the exhaust gas is filtered and cooled to obtain the final product, Fe3O4 magnetic nanoparticles; the high temperature sintering is specifically as follows: the heating chamber temperature is increased to 300°C at a heating rate of 2°C / min, and sintered at 300°C for 2h.

2. The method according to claim 1, characterized in that The atomization specifically includes: atomizing and dispersing the precursor solution into small droplets, and the atomization pressure is 0.1 MPa.

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