Modified silicon dioxide nano-powder, nano-fluid and preparation method thereof

Abstract

The invention provides modified silicon dioxide nano-powder, nano-fluid and a preparation method of the modified silicon dioxide nano-powder and the nano-fluid. The preparation method comprises the following steps: modifying silicon dioxide nano-powder to obtain sodium alkylol amine modified silicon dioxide nano-powder; and dispersing the sodium alkanolamide modified silicon dioxide nano-powder in a base solution to obtain the sodium alkanolamide modified silicon dioxide nano-fluid. The sodium alkanolamide modified silicon dioxide nano-powder obtained by the preparation method is high in yield and good in dispersity, and the nano-fluid based on sodium alkanolamide modified silicon dioxide has excellent anti-rust performance.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials, specifically to a modified silica nanopowder, a nanofluid, and a method for preparing the same. Background Technology

[0002] Nano-silica has demonstrated broad application potential in multiple fields. In biomedical engineering, nano-silica is used in cell separation technology, utilizing its high absorption and dispersibility to quickly and effectively separate cells without contaminating the biological cellular environment. In optics, nano-silica exhibits excellent light transmittance and high reflectivity as an infrared reflective material, significantly improving energy efficiency in industries such as light bulbs. In electronic packaging materials, its high dielectric properties, heat resistance, and low expansion make it an ideal material for integrated circuit packaging, significantly improving the performance of epoxy resins. In coatings, nano-silica, through its unique optical properties and three-dimensional network structure, not only enhances the aging resistance and heat insulation performance of coatings but also improves color retention and coating quality. In cosmetics, nano-silica powder exhibits strong chemical stability and is not easily decomposed under ultraviolet light irradiation, meeting the requirements of cosmetics and sunscreens for shielding against solar ultraviolet rays. Furthermore, its white particle color allows it to achieve both sun protection and whitening effects when added to cosmetics. In addition, antibacterial fibers and deodorizing fibers also utilize nano-silica. Antibacterial fibers and deodorizing fibers are functional fibers that incorporate nano-titanium dioxide, nano-silica, nano-zinc oxide (JSO3) ​​and other micro-powders into natural or artificial polymers or filaments, and then spin them into various antibacterial and deodorizing fibers.

[0003] Nanoparticles possess excellent heat transfer properties, kinematic viscosity, antibacterial properties, and long service life, exhibiting superior performance compared to general heat dissipation media. Therefore, nanoparticles are widely used in industrial production for heat transfer, thermal conductivity, durability, and antibacterial applications. However, nanoparticles suffer from poor dispersibility and a tendency to agglomerate, which significantly limits their applications. Therefore, modification of nanoparticles is necessary to improve their applicability. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a modified silica nanopowder, a nanofluid, and a method for preparing the same.

[0005] According to one aspect of the present invention, a method for preparing modified silica nanopowder is provided, which may include: a first step: mixing silica nanopowder, anhydrous ethanol and APTES, and then centrifuging to obtain amino-modified silica nanopowder; a second step: mixing the obtained amino-modified silica nanopowder, anhydrous ethanol and a sodium amide solution of amide amino acids, and then centrifuging to obtain sodium amide modified silica nanopowder.

[0006] Furthermore, in the first step, anhydrous ethanol and APTES can be mixed at a volume ratio of 145-155:1.

[0007] Furthermore, in the first step, anhydrous ethanol and APTES can be mixed at a stirring speed of 150-250 rpm.

[0008] Furthermore, in the first step, the mixing time of anhydrous ethanol and APTES can be 3-6 hours.

[0009] Furthermore, the second step may include: ultrasonically dispersing amino-modified silica nanoparticles in anhydrous ethanol to obtain a transparent solution with a bluish tint; adjusting the pH of the transparent solution to alkaline; and adding a pre-prepared sodium amide solution of amide amino acids for mixing.

[0010] Furthermore, in the second step, the amino-modified silica nanoparticles, anhydrous ethanol, and sodium ethanolamine solution of acyl amino acids can be mixed at a stirring speed of 450-550 rpm.

[0011] Furthermore, in the second step, the mixing time of the amino-modified silica nanoparticles, anhydrous ethanol, and sodium ethanolamine solution can be 1-5 hours.

[0012] According to another aspect of the present invention, a sodium amide modified silica nanopowder prepared according to the above-described method for preparing modified silica nanopowder is provided.

[0013] According to another aspect of the present invention, a method for preparing modified silica nanofluid is provided, which may include: dispersing sodium amide modified silica nanopowder prepared according to the above-described method for preparing modified silica nanopowder in a base liquid to form modified silica nanofluid.

[0014] According to another aspect of the present invention, a sodium amide modified silica nanofluid prepared according to the above-described method for preparing modified silica nanofluids is provided.

[0015] According to the present invention, a modified silica nanopowder, a nanofluid, and a method for preparing the same are provided. The method involves modifying silica nanopowder to obtain sodium alkanoate-modified silica nanopowder, and then dispersing the sodium alkanoate-modified silica nanopowder in a base liquid to obtain a sodium alkanoate-modified silica nanofluid. The sodium alkanoate-modified silica nanopowder obtained by this method exhibits high yield and good dispersibility, and the nanofluid based on sodium alkanoate-modified silica possesses excellent rust-preventive properties. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating an example of a method for preparing silica nanopowder.

[0017] Figure 2 This is a flowchart of a method for preparing modified silica nanopowder according to an embodiment of the present invention.

[0018] Figure 3 This is a diagram illustrating the rust prevention test of silica nanoparticles according to an embodiment of the present invention.

[0019] Figure 4 The images show the infrared spectra of silica nanopowder before and after modification according to an embodiment of the present invention.

[0020] Figure 5 This is a diagram illustrating the rust prevention test of modified silica nanoparticles according to an embodiment of the present invention. Detailed Implementation

[0021] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0022] It should be noted that in this invention, silica nanopowders (also referred to as silica nanoparticles) can be prepared by various methods. In the following text, the precipitation method will be used as an example to prepare silica nanopowders, but this invention is not limited to this; other preparation methods can also be used, such as physical methods (including mechanical pulverization) and chemical methods (including chemical vapor deposition, liquid phase method, ion exchange method, sol-gel method, etc.).

[0023] Figure 1 This is a flowchart illustrating an example of a method for preparing silica nanopowder. (Refer to...) Figure 1 The example method for preparing silica nanopowder includes the following steps.

[0024] In S101, tetraethyl orthosilicate (TEOS) and anhydrous ethanol are mixed to obtain the first solution.

[0025] In S103, anhydrous ethanol, deionized water and concentrated ammonia are mixed to obtain a second solution.

[0026] In S105, the first and second solutions obtained above are mixed and then centrifuged to obtain silica nanopowder.

[0027] According to the above operation steps S101, S103, and S105, silica nanopowder can be obtained.

[0028] As described above, the preparation method of silica nanopowder in this invention is not limited to the above precipitation method, and other physical or chemical methods can also be used.

[0029] Figure 2 This is a flowchart of a method for preparing modified silica nanopowder according to an embodiment of the present invention.

[0030] Reference Figure 2 The method for preparing modified silica nanopowder according to an embodiment of the present invention includes the following steps.

[0031] In step S201, silica nanoparticles (e.g., silica nanoparticles obtained according to the above steps S101, S103, and S105), anhydrous ethanol, and APTES are mixed, and then centrifuged to obtain amino-modified silica nanoparticles. It should be noted that the modification of silica nanoparticles in this invention is not limited to silica nanoparticles obtained by the above precipitation method, but can be applied to silica nanoparticles obtained by different methods (e.g., physical methods, chemical methods).

[0032] In the embodiment, the silica nanoparticles obtained according to the above operation steps S101, S103, and S105 are ultrasonically dispersed in anhydrous ethanol, APTES is added, and the mixture is stirred at a certain speed for a certain time. Then, the resulting mixed solution is centrifuged at high speed. After centrifugation, the mixture is washed twice in sequence with acetone, anhydrous ethanol, and tetrahydrofuran solvent to obtain amino-modified silica nanoparticles, namely SiO2@NH2.

[0033] In the embodiments, anhydrous ethanol and APTES can be mixed at a volume ratio of 145-155:1, for example, anhydrous ethanol and APTES can be mixed at a volume ratio of 150:1, but the present invention is not limited thereto, and the volume of anhydrous ethanol and APTES can be increased or decreased as needed.

[0034] In this embodiment, stirring can be performed at a speed of 150-250 rpm for 3-6 hours, but the invention is not limited thereto, and at least one of the stirring speed and stirring time can be adjusted as needed. For example, the stirring speed can be set to 250 rpm and the stirring time to 3 hours, or the stirring speed can be set to 150 rpm and the stirring time to 6 hours.

[0035] In S203, the obtained amino-modified silica nanoparticles, anhydrous ethanol, and sodium amide solution of amide amino acids are mixed and then centrifuged to obtain sodium amide-modified silica nanoparticles.

[0036] In this embodiment, the amino-modified silica nanoparticles obtained in step S201 are ultrasonically dispersed in anhydrous ethanol to obtain a transparent solution with a bluish tint. The pH of the solution is adjusted to alkaline, and then a pre-prepared sodium amide amino acid solution is added and magnetically stirred. The resulting mixed solution is centrifuged at high speed, and the precipitate after centrifugation is washed three times with ethanol, acetone, and deionized water, respectively, to obtain sodium amide-modified silica nanoparticles.

[0037] In the embodiments, the sodium amide solution of the amide amino acid can be prepared as follows: Glutamic acid powder and sodium hydroxide are placed in a blue-capped bottle at a ratio of 871:237, and reacted with 100-150 mL of deionized water in an ice-water bath using magnetic stirring at 250-350 rpm. After the solution has reacted for a certain time, 60-100 mL of acetone solution and 8-8.1 g of NaOH granules are added, and the reaction is continued for a certain time (e.g., 2 hours) under magnetic stirring at 550-650 rpm in a cold water bath at 10-20°C. The solution is then adjusted to alkalinity, and lauroyl chloride is added to the solution drop by drop every 3-5 seconds using a constant-pressure funnel to carry out the reaction, finally obtaining the sodium amide amino acid solution. Although the above describes a method for preparing the sodium amide amino acid solution, the present invention is not limited thereto. The preparation of the sodium amide amino acid solution is known to those skilled in the art, and therefore it can be prepared in other ways.

[0038] In this embodiment, magnetic stirring can be performed at a speed of 450-550 rpm for 1-5 hours, but the invention is not limited thereto, and at least one of the stirring speed and stirring time can be adjusted as needed. For example, the stirring speed can be set to 450 rpm and the stirring time to 5 hours, or the stirring speed can be set to 550 rpm and the stirring time to 1 hour.

[0039] According to the above operation steps S201 and S203, sodium amide modified silica nanopowder can be obtained.

[0040] According to the method for preparing modified silica nanopowder of the present invention, since sodium amide is used to modify the silica nanopowder, the obtained modified silica nanopowder has anti-rust properties.

[0041] The reason for using sodium amide modification is that sodium triethanolamine, as a rust inhibitor, has good rust prevention properties when its concentration in solution reaches 0.6%, and the rust prevention properties reach their maximum when the concentration reaches 1.2%. Therefore, even if its component is present in trace amounts, good rust prevention performance can be obtained. The concentration of nanoparticles in general nanofluids is about 0.5% to 3%, so this modification can be applied to nanoparticles.

[0042] To test the rust-preventive properties of silica nanopowder according to embodiments of the present invention, the silica nanopowder can be configured into a silica nanofluid for testing. In the embodiments, the silica nanopowder can be dispersed in a certain base liquid (e.g., water, ethanol, machine oil, support fluid) to form a silica nanofluid. (See the following references...) Figure 3 In the description, silica nanopowder was prepared into an aqueous solution with a mass fraction of 2.8-3.2% (i.e., silica nanofluid) for testing.

[0043] Figure 3 This is a diagram illustrating the rust prevention test of silica nanoparticles according to an embodiment of the present invention.

[0044] Rust prevention testing can be conducted as follows: For cast iron spot testing, the test solution (i.e., silica nanofluid) is applied in a plum blossom pattern to five spots on the cast iron surface. The rust condition of the cast iron surface covered by these five liquid spots is observed. Parallel tests are performed using two cast iron pieces. The rust prevention performance is evaluated according to the GB / T 6144-2010 standard. The test piece material is Grade I gray cast iron, the test temperature is (35±2)℃, and the humidity is R (the method can be referenced in industry standard MT 76-2011).

[0045] Reference Figure 3 It can be seen that the solution of silica nanopowder (i.e., silica nanofluid) can prevent further corrosion. After polishing, it was found that the corrosion of the test block only occurred on the surface. Therefore, this corrosion is easy to treat.

[0046] To compare the effects of different modification methods on silica nanopowders, this invention also provides carboxyl-modified silica nanopowders. Carboxyl-modified silica nanopowders can be obtained by: [referring to the above-mentioned...] Figure 2 The amino-modified silica nanopowder obtained in step S201 is ultrasonically dispersed in 45-55 mL of tetrahydrofuran to obtain a pale yellow transparent solution; 0.1-0.3 g of TMA is added to the solution and stirred for eight hours; the mixed solution is centrifuged at high speed, washed three times with ethanol, and dried to obtain carboxyl-modified silica nanopowder, namely SiO2@COOH.

[0047] Figure 4The images show the infrared spectra of silica nanopowder before and after modification according to an embodiment of the present invention.

[0048] like Figure 4 As shown in the three infrared spectra, the range from 1000 to 1300 cm⁻¹ is... -1 The strongest absorption peak at that point is the stretching vibration peak of Si—O—Si.

[0049] The C-N stretching vibration values ​​in the SiO2@NH2 (amino-modified) spectrum are at 1000 cm⁻¹. -1 At times, it may be masked by the stronger stretching vibration peaks of Si—O—Si, while at 696, 1561, and 1629 cm⁻¹... -1 The three absorption peaks at the point correspond to the strong deformation vibration absorption peaks of the amino group, indicating that APTES was successfully attached to the surface of SiO2 nanoparticles, thus forming SiO2@NH2.

[0050] The spectrum of SiO2@COOH (carboxyl-modified) shows that at 1652 cm⁻¹... -1 1714cm -1 The absorption peak at the point corresponds to the shrinkage vibration absorption peak of the oxide group in the amide group and carboxyl group, which indicates that the carboxyl group was successfully attached to the surface of SiO2 nanoparticles, thus forming SiO2@COOH.

[0051] The parameters of silica nanopowder and modified silica nanopowder were tested in this invention, as shown in Tables 1 and 2 below:

[0052] Table 1 Parameters of silica nanopowder

[0053] sample PID Number mean (d.nm) Zp(mv) <![CDATA[SiO2]]> 0.108 79.4 -62.6

[0054] Table 2 Parameters of modified silica nanopowder

[0055] sample PID Number mean (d.nm) Zp(mv) <![CDATA[SiO2@COOH]]> 0.865 654.9 37.8 <![CDATA[SiO2@Sodium alkanolamine]]> 0.299 95 21.8 <![CDATA[SiO2@NH2]]> 0.554 1436 -1.18

[0056] As shown in Tables 1 and 2, after amino modification, the amino groups of SiO2, acting as bridging ligands, are attached to the surface of the SiO2 powder. At this time, the SiO2@NH2 powder formed exhibits obvious agglomeration, which increases the particle size from 79.4 nm (refer to Table 1) to 1436 nm. Furthermore, due to surface modification, the potential changes from -62.6 mV (refer to Table 1) to -1.18 mV, approaching neutrality.

[0057] After carboxyl modification of SiO2@NH2, the resulting SiO2@COOH powder exhibits a significantly smaller particle size compared to SiO2@NH2 (from 1436 nm to 654.9 nm), and a significant change in potential (from -1.18 mV to 37.8 mV). Therefore, carboxyl modification significantly improves the agglomeration of the nanoparticles and enhances their stability.

[0058] After modification with sodium alkanoate in SiO2@NH2, the resulting SiO2@sodium alkanoate nanoparticles showed a significantly reduced particle size (from 1436 nm to 95 nm) compared to SiO2@NH2, and a significant change in potential (from -1.18 mV to 21.8 mV). Therefore, modification with sodium alkanoate significantly improved the agglomeration of the nanoparticles and enhanced their stability.

[0059] To test the rust-preventive properties of the modified silica nanopowder (SiO2@sodium alkanoate nanopowder) according to embodiments of the present invention, the modified silica nanopowder can be configured into a modified silica nanofluid for testing. In the embodiments, the modified silica nanopowder can be dispersed in a certain base liquid (e.g., water, ethanol, machine oil, support fluid, etc.) to form a modified silica nanofluid. (See the following references...) Figure 5 In the description, the modified silica nanopowder was prepared into an aqueous solution with a mass fraction of 3% (i.e., modified silica nanofluid) for testing.

[0060] Figure 5 This is a diagram illustrating the rust prevention test of modified silica nanoparticles (SiO2@sodium ethanolamine nanoparticles) according to an embodiment of the present invention.

[0061] Based on the above references Figure 3 The rust prevention test method described herein is used for rust prevention testing, but its description is omitted here.

[0062] Reference Figure 5 It can be seen that after the prepared aqueous solution of nanoparticles with a mass fraction of 3% (i.e., modified silica nanofluid) was dropped onto the test block, good rust prevention performance was obtained.

[0063] According to the present invention, a modified silica nanopowder, a nanofluid, and a method for preparing the same are provided. The method involves modifying silica nanopowder to obtain sodium alkanoate-modified silica nanopowder, and then dispersing the sodium alkanoate-modified silica nanopowder in a base liquid to obtain a sodium alkanoate-modified silica nanofluid. The sodium alkanoate-modified silica nanopowder obtained by this method exhibits high yield and good dispersibility, and the nanofluid based on sodium alkanoate-modified silica possesses excellent rust-preventive properties.

[0064] Although the above embodiments describe an example of dispersing modified silica nanoparticles (SiO2@sodium alkanoate nanoparticles) in water to form modified silica nanofluids and the modified silica nanofluids having anti-rust properties, according to the present invention, other base liquids may also be used, such as water, alcohols, aldehydes, olefins, aromatic hydrocarbons, etc., and the present invention does not impose any particular limitation on this.

[0065] In the embodiments, modified silica nanopowder can be prepared according to the above-described method for preparing modified silica nanopowder, and then the modified silica nanopowder can be dispersed in a certain base liquid to form modified silica nanofluid, which can be used as a rust inhibitor.

[0066] For example, in mining hydraulic supports, sodium amine-modified silica nanoparticles can be dispersed in the support fluid of the mining hydraulic support to form sodium amine-modified silica nanofluid, thereby improving the rust prevention performance of the mining hydraulic support.

[0067] Although the present invention has been illustrated above with reference to specific embodiments, those skilled in the art will understand that various modifications and improvements can be made to the present invention without departing from the technical spirit of the invention.

Claims

1. A method for preparing modified silica nanopowder, characterized in that, include: First step: Mix silica nanopowder, anhydrous ethanol and APTES, and then centrifuge to obtain amino-modified silica nanopowder; The second step involves mixing the obtained amino-modified silica nanoparticles, anhydrous ethanol, and sodium amide solution of amide amino acids, followed by centrifugation to obtain sodium amide-modified silica nanoparticles.

2. The method for preparing modified silica nanopowder according to claim 1, characterized in that, In the first step, anhydrous ethanol and APTES are mixed at a volume ratio of 145-155:

1.

3. The method for preparing modified silica nanopowder according to claim 1, characterized in that, In the first step, anhydrous ethanol and APTES are mixed at a stirring speed of 150-250 rpm.

4. The method for preparing modified silica nanopowder according to claim 1, characterized in that, In the first step, anhydrous ethanol and APTES are mixed for 3-6 hours.

5. The method for preparing modified silica nanopowder according to claim 1, characterized in that, The second step includes: ultrasonically dispersing the amino-modified silica nanoparticles in anhydrous ethanol to obtain a transparent solution with a bluish tint; adjusting the pH of the transparent solution to alkaline; and adding a pre-prepared sodium amide solution of amide amino acids for mixing.

6. The method for preparing modified silica nanopowder according to claim 5, characterized in that, In the second step, the amino-modified silica nanopowder, anhydrous ethanol, and sodium ethanolamine solution of acyl amino acids are mixed at a stirring speed of 450-550 rpm.

7. The method for preparing modified silica nanopowder according to claim 5, characterized in that, In the second step, the amino-modified silica nanopowder, anhydrous ethanol, and sodium amide solution of acyl amino acids are mixed for 1-5 hours.

8. Sodium amide modified silica nanopowder prepared by the method of preparing modified silica nanopowder according to claim 1.

9. A method for preparing modified silica nanofluid, characterized in that, include: The sodium amide modified silica nanopowder prepared by the method of preparing modified silica nanopowder according to claim 1 is dispersed in a base liquid to form the modified silica nanofluid.

10. A sodium amide modified silica nanofluid prepared by the method of preparing modified silica nanofluid according to claim 9.

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