Method for preparing core-shell hollow-structured nanoparticles with micro-nano bubbles

Abstract

Disclosed is a method for preparing core-shell hollow nanoparticles with micro-nano bubbles. It includes: (1) mixing titanium tetrachloride and water mist to obtain a titanium dioxide solid / hydrochloric acid droplet mixture; (2) shearing and mixing the titanium dioxide solid / hydrochloric acid droplet mixture with tetraethyl orthosilicate liquid through a micro-nano bubble generator to obtain micro-nano bubbles; (3) separating, drying the precipitate, and calcining to obtain core-shell hollow structure nanoparticles. The obtained core-shell hollow structure broadens the active surface of the catalytic reaction, improves the activity, and the method is simple and easy for large-scale industrial production.

Description

Technical Field

[0001] The present disclosure relates to the field of polymer materials, and particularly to a method for preparing core-shell hollow structure nanoparticles by micro-nano bubbles. Background Art

[0002] Titanium dioxide is a common semiconductor photocatalytic material. Under the irradiation of light, it can convert light energy into chemical energy and decompose toxic and harmful organic substances in a relatively short time. In addition, it also has the characteristics of high stability, light corrosion resistance, non-toxicity, and does not produce secondary pollution during the treatment process. Therefore, it has attracted more and more attention in the fields of antibacterial, deodorization, oil decomposition, mildew and algae prevention, air purification, etc. However, since the catalytic reaction is essentially a surface contact reaction and only occurs on the surface of the material, for the catalyst, the limited surface area has to be used for catalytic reactions and at the same time undertake the task of particle loading and fixation, which often greatly affects the catalytic effect.

[0003] The core-shell structure is a nano-scale ordered assembly structure formed by coating one nano material with another nano material through chemical bonds or other forces. It plays an important role in maintaining the functional stability of the catalyst, regulating the physical and chemical properties of the material to achieve complementary advantages, preventing nanoparticle aggregation, and controlling the interfacial reaction of the particles, and has broad application prospects in photocatalysis, batteries, gas storage and separation. However, for nano-catalytic materials that rely on the surface area to promote reactions, how to solve the problem that the shell covers the surface of the core and interferes with the catalytic activity of the core has always been an unavoidable obstacle on the road to the application of nano-catalysts.

[0004] How to obtain nano materials with high catalytic activity still needs further improvement. Summary of the Invention

[0005] The present disclosure aims to solve at least one of the technical problems in the related art to some extent. The present disclosure utilizes the characteristic that titanium tetrachloride, the precursor of titanium dioxide, is unstable in water and will emit smoke in the air to generate a mixture of titanium dioxide solid / hydrochloric acid droplets. Through a micro-nano bubble generator, the smoke generated by mixing titanium tetrachloride with water mist is mixed with a pure solution of tetraethyl orthosilicate to form bubbles, and the bubbles are subjected to cyclical shear and crushing to form micro-nano bubbles. At the same time, the hydrochloric acid by-product generated after titanium tetrachloride reacts with water can promote the hydrolysis of tetraethyl orthosilicate on the gas-liquid surface of the micro-nano bubbles to form a stable silica shell, and finally obtain photocatalytic core-shell hollow structure nanoparticles with a hollow structure between the core and the shell.

[0006] Specifically, the present disclosure provides the following technical solutions:

[0007] In a first aspect of the present disclosure, there is provided a method for preparing core-shell hollow structure nanoparticles by micro-nano bubbles, including:

[0008] (1) Mix titanium tetrachloride and water mist to obtain a titanium dioxide solid / hydrochloric acid droplet mixture;

[0009] (2) Through a micro-nano bubble generator, shear and stir the titanium dioxide solid / hydrochloric acid droplet mixture with tetraethyl orthosilicate liquid to obtain micro-nano bubbles;

[0010] (3) Separate, dry and calcine the precipitate to obtain core-shell hollow structure nanoparticles.

[0011] According to an embodiment of the present disclosure, the above-described method may further include the following technical features:

[0012] Further, step (1) further includes: adding 8-15 parts by weight of titanium tetrachloride into a 10-15 L closed container with internal air circulation, introducing air with a humidity of 5-30%, and performing closed circulation for 1-4 hours.

[0013] Further, based on the amount of titanium tetrachloride being 8-15 parts by weight in step (2), the addition amount of the tetraethyl orthosilicate liquid is 80-120 parts by weight, preferably 90-110 parts by weight.

[0014] Further, the diameter of the micro-nano bubbles in step (2) is 200-1000 nanometers.

[0015] Further, the shearing time in step (2) is 3-9 hours.

[0016] Further, the calcination temperature in step (3) is 400-500 degrees Celsius, and the calcination time is 1-3 hours.

[0017] Further, the drying temperature in step (3) is 70-90 degrees Celsius, and the drying time is 10-15 hours.

[0018] Further, the separation in step (3) is performed by centrifugation.

[0019] The second aspect of the present disclosure provides a method for preparing core-shell hollow structure nanoparticles through micro-nano bubbles, including:

[0020] (1) Add 8-15 parts by weight of titanium tetrachloride into a closed container, introduce air with a humidity of 5-30%, and perform closed circulation for 1-4 hours to obtain a titanium dioxide solid / hydrochloric acid droplet mixture;

[0021] (2) Through a micro-nano bubble generator, shear and mix the titanium dioxide solid / hydrochloric acid droplet mixture with 80 - 120 parts by weight of tetraethyl orthosilicate liquid for 3 - 9 hours to obtain micro-nano bubbles with a particle size of 200 - 1000 nanometers;

[0022] (3) Centrifugally separate, dry the precipitate at 70 - 90 °C, and calcine it at 400 - 500 °C to obtain core-shell hollow structure nanoparticles.

[0023] Further, the method includes:

[0024] (1) Add 10 parts by weight of titanium tetrachloride to a closed container, introduce air with a humidity of 5 - 30%, and perform a closed circulation for 1 - 4 hours to obtain a titanium dioxide solid / hydrochloric acid droplet mixture;

[0025] (2) Through a micro-nano bubble generator, shear and mix the titanium dioxide solid / hydrochloric acid droplet mixture with 100 parts by weight of tetraethyl orthosilicate liquid for 3 - 9 hours to obtain micro-nano bubbles with a particle size of 200 - 1000 nanometers;

[0026] (3) Centrifugally separate, dry the precipitate at 80 °C, and calcine it at 400 - 500 °C to obtain core-shell hollow structure nanoparticles.

[0027] The third aspect of the present disclosure provides a core-shell hollow structure nanoparticle prepared by the method according to any embodiment of the first aspect or any embodiment of the second aspect.

[0028] The beneficial effects achieved by the present disclosure are as follows: Photocatalytic core-shell hollow structure nanoparticles are obtained through the method provided by the present disclosure. Moreover, the provided core-shell hollow structure broadens the active surface of the catalytic reaction, improves the activity, and can also save raw materials. The preparation process of this product is relatively simple, the conditions are easy to control, and it is easy to mass-produce industrially. Description of the Drawings

[0029] Figure 1 It is an electron microscope image of the core-shell hollow structure nanoparticle provided by Embodiment 1 of the present disclosure.

[0030] Figure 2 It is an XRD pattern of the core-shell hollow structure nanoparticle provided by Embodiment 1 of the present disclosure.

[0031] Figure 3 It is a catalytic activity result graph of the core-shell hollow structure nanoparticle provided by Embodiment 1 of the present disclosure.

[0032] Figure 4 It is a diagram showing the antibacterial effect results of the core-shell hollow structure nanoparticles provided in Embodiment 1 of the present disclosure.

[0033] Figure 5 、 Figure 6 、 Figure 7 It is an electron microscope image of the sample provided in Comparative Example 1 of the present disclosure. Detailed Description of Specific Embodiments

[0034] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that the illustrated embodiments are exemplary and are intended to explain the present disclosure, and should not be construed as a limitation to the present disclosure. In this article, unless otherwise specified, the contents mentioned such as content are all in mass percentage.

[0035] Titanium tetrachloride, also known as titanium(IV) chloride, is an inorganic compound with the chemical formula TiCl4. Titanium tetrachloride is an important intermediate in the production of titanium dioxide. At room temperature, titanium tetrachloride is a colorless liquid. When exposed to air, titanium tetrachloride will quickly react with water in the air: TiCl4 + 2H2O → TiO2 + 4HCl. Micro-nano bubbles are a special gas state existing at the gas-liquid interface and can stably exist in the liquid for a long time. Currently, common micro-nano bubble generators on the market all belong to high-shear generators, generally using dynamic or static high-speed shearing equipment to obtain micro-nano bubbles by crushing large gas-liquid mixed bubbles. The present disclosure utilizes the property that titanium tetrachloride, the precursor of titanium dioxide, is unstable in water and will emit smoke in the air to generate a mixture of titanium dioxide solid / hydrochloric acid droplets. By using a commercially available micro-nano bubble generator, the smoke generated after mixing titanium tetrachloride with water mist is mixed with a pure solution of tetraethyl orthosilicate to form bubbles, and the bubbles are subjected to swirling shear crushing to form micro-nano bubbles. At the same time, the hydrochloric acid by-product generated after titanium tetrachloride reacts with water can promote the hydrolysis of tetraethyl orthosilicate on the gas-liquid surface of the micro-nano bubbles to form a stable silica shell, and finally obtain photocatalytic core-shell hollow structure nanoparticles with a hollow structure between the core and the shell.

[0036] The present disclosure provides a method for preparing core-shell hollow structure nanoparticles through micro-nano bubbles, including: (1) mixing titanium tetrachloride and water mist to obtain a mixture of titanium dioxide solid / hydrochloric acid droplets;

[0037] (2) using a micro-nano bubble generator to shear and crush-mix the mixture of titanium dioxide solid / hydrochloric acid droplets with tetraethyl orthosilicate liquid to obtain micro-nano bubbles;

[0038] (3) separating, drying the precipitate, and calcining to obtain core-shell hollow structure nanoparticles.

[0039] According to the specific embodiment, step (1) further includes: adding 8-15 parts by weight of titanium tetrachloride into a 10-15 L closed container with internal air circulation, introducing air with a humidity of 5-30%, and performing closed circulation for 1-4 hours. Titanium tetrachloride reacts only when it meets water vapor to generate titanium dioxide nanoparticles, and white smoke will appear on the surface. The formed white smoke is titanium dioxide particles. TiCl4 is extremely active and easily hydrolyzes, forming smoke with water vapor in the air, so the reaction with water is extremely intense; the reaction TiCl4 + H2O ----> TiCl3(OH) + HCl occurs; and it hydrolyzes step by step to finally form TiO2.

[0040] According to the specific embodiment, based on the amount of titanium tetrachloride being 8-15 parts by weight, the addition amount of the tetraethyl orthosilicate liquid is 80-120 parts by weight. When mixing and shearing and crushing the titanium dioxide solid / hydrochloric acid droplet mixture with tetraethyl orthosilicate, if the amount of tetraethyl orthosilicate is too small, it is not easy to form core-shell hollow structure nanoparticles; if the amount of tetraethyl orthosilicate is too large, to a certain extent, it will affect the catalytic activity of the formed core-shell hollow structure nanoparticles. According to the specific embodiment, based on the amount of titanium tetrachloride being 8-15 parts by weight, the addition amount of the tetraethyl orthosilicate liquid is 90-110 parts by weight, such as 90 parts by weight, 95 parts by weight, 100 parts by weight, 105 parts by weight, 110 parts by weight, etc.

[0041] According to the specific embodiment, the diameter of the micro-nano bubbles in step (2) is 200-1000 nanometers. For example, the diameter of the micro-nano bubbles is 300-900 nanometers, such as 300 nanometers, 400 nanometers, 500 nanometers, 600 nanometers, 700 nanometers, 800 nanometers, 900 nanometers, etc.

[0042] According to the specific embodiment, the shearing time in step (2) is 3-9 hours.

[0043] According to the specific embodiment, the calcination temperature in step (3) is 400-500 degrees Celsius, and the calcination time is 1-3 hours.

[0044] According to the specific embodiment, the drying temperature in step (3) is 70-90 degrees Celsius, and the drying time is 10-15 hours.

[0045] The present disclosure provides a method for preparing core-shell hollow structure nanoparticles through micro-nano bubbles, including:

[0046] (1) Adding 8-15 parts by weight of titanium tetrachloride into a closed container, introducing air with a humidity of 5-30%, and performing closed circulation for 1-4 hours to obtain a titanium dioxide solid / hydrochloric acid droplet mixture;

[0047] (2) Through a micro-nano bubble generator, shear and mix the titanium dioxide solid / hydrochloric acid droplet mixture with 80 - 120 parts by weight of tetraethyl orthosilicate liquid for 3 - 9 hours to obtain micro-nano bubbles with a particle size of 200 - 1000 nanometers;

[0048] (3) Centrifugally separate, dry the precipitate at 70 - 90 °C, and calcine it at 400 - 500 °C to obtain core-shell hollow structure nanoparticles.

[0049] The present disclosure also provides a method for preparing core-shell hollow structure nanoparticles through micro-nano bubbles, including:

[0050] (1) Add 10 parts by weight of titanium tetrachloride to a closed container, introduce air with a humidity of 5 - 30%, and perform a closed circulation for 1 - 4 hours to obtain a titanium dioxide solid / hydrochloric acid droplet mixture;

[0051] (2) Through a micro-nano bubble generator, shear and mix the titanium dioxide solid / hydrochloric acid droplet mixture with 100 parts by weight of tetraethyl orthosilicate liquid for 3 - 9 hours to obtain micro-nano bubbles with a particle size of 200 - 1000 nanometers;

[0052] (3) Centrifugally separate, dry the precipitate at 80 °C, and calcine it at 400 - 500 °C to obtain core-shell hollow structure nanoparticles.

[0053] The present disclosure will be further elaborated below in conjunction with embodiments. The embodiments are only for illustration and do not limit the content of the present disclosure. The solutions of the present disclosure will be explained below in conjunction with the embodiments. Those skilled in the art will understand that the following embodiments are only for illustrating the present disclosure and should not be regarded as limiting the scope of the present disclosure. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase. Among them, the micro-nano bubble generator used is commercially purchased.

[0054] Example 1

[0055] Example 1 provides a method for preparing core-shell hollow structure nanoparticles, including:

[0056] 1. Lay 10 parts by weight of titanium tetrachloride at the bottom of a 10 L closed container with internal air circulation, introduce air with a humidity of 10%, and perform a closed circulation for 2 hours.

[0057] 2. The flue gas generated in the above process is introduced into a pure solution of 100 parts by weight of tetraethyl orthosilicate through a commercially available micro-nano bubble generator, and micro-nano bubbles are obtained by shearing and crushing the large gas-liquid mixed bubbles. The diameter of the micro-nano bubbles is controlled at about 500 nm, and the shearing time is 6 hours.

[0058] 3. After the reaction, the solution obtained in step 2 is centrifuged, and the precipitate is dried at 80 °C for 12 hours. Finally, it is calcined at 400 °C for 3 hours to obtain the core-shell hollow structure nanoparticles.

[0059] Example 2

[0060] Example 2 provides a method for preparing core-shell hollow structure nanoparticles, including:

[0061] 1. At the bottom of a 10 L closed container with internal air circulation, 15 parts by weight of titanium tetrachloride are laid, and air with a humidity of 20% is introduced, and the closed circulation is carried out for 4 hours.

[0062] 2. The flue gas generated in the above process is introduced into a pure solution of 100 parts by weight of tetraethyl orthosilicate through a commercially available micro-nano bubble generator, and micro-nano bubbles are obtained by shearing and crushing the large gas-liquid mixed bubbles. The diameter of the micro-nano bubbles is controlled at about 800 nm, and the shearing time is 8 hours.

[0063] 3. After the reaction, the solution obtained in step 2 is centrifuged, and the precipitate is dried at 80 °C for 12 hours. Finally, it is calcined at 500 °C for 2 hours to obtain the core-shell hollow structure nanoparticles.

[0064] Taking the core-shell hollow structure nanoparticles prepared in Example 1 as an example, characterization is carried out. The electron microscope image is as Figure 1 shown. Other characterization results are as follows:

[0065] 1. XRD data

[0066] The XRD data shows that the lattice structure of the core-shell hollow titanium dioxide particles has not changed, and all show the anatase phase of titanium dioxide, as Figure 2 shown.

[0067] 2. Catalytic activity data

[0068] The photocatalytic fading experiment of the rhodamine B solution also shows that the core-shell hollow structure nanoparticles with an addition amount of 1-4% of the solution can photocatalytically fade the 5x10-5 mol / L rhodamine B (Rh B) solution within three hours, showing good photocatalytic activity, as Figure 3As shown in a and b. In a, RbB represents a rhodamine B solution without adding any photocatalytic material. Sample 1 represents a rhodamine B solution with the addition amount of core-shell hollow structure nanoparticles being 1% of the total solution amount. Sample 2 represents a rhodamine B solution with the addition amount of core-shell hollow structure nanoparticles being 2% of the total solution amount. Sample 3 is a rhodamine B solution with the addition amount of core-shell hollow structure nanoparticles being 3% of the total solution amount. Sample 4 is a rhodamine B solution with the addition amount of core-shell hollow structure nanoparticles being 4% of the total solution amount. Among them, in b, the absorption peaks from high to low are catalytic time 0h, catalytic time 0.5h, catalytic time 1h, catalytic time 1.5h, catalytic time 2h, catalytic time 2.5h, catalytic time 3h, and the sample solution used is the sample 4 solution in a diagram.

[0069] 3. Antibacterial effect

[0070] Add the core-shell hollow structure nanoparticles into the bacterial culture solution (the control is the sample added with silica, and S0 - S4 are the core-shell hollow structure nanoparticles with the addition amounts of 0‰, 1‰, 2‰, 3‰, 4‰ respectively). After 24 hours, it can be seen that the samples added with core-shell hollow titanium dioxide particles all have good antibacterial effects. The results are as Figure 4 shown.

[0071] Comparative Example 1

[0072] In the process of preparing the core-shell hollow structure nanoparticles in Comparative Example 1, the difference from Example 1 is that when flowing in air with a certain humidity, the parameters such as the flow rate are not adjusted reasonably, and the flow rate is too large, resulting in samples that cannot form a shell layer. The electron microscope results are as Figure 5 shown. And sometimes samples with an unstable silica layer will be formed. The electron microscope results are as Figure 6 shown. Some samples with a stable silica layer but uneven distribution of titanium dioxide nuclei will be formed. The electron microscope results are as Figure 7 shown.

[0073] The above are only the preferred embodiments of the present disclosure. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present disclosure, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present disclosure.

Claims

1. A method for preparing core-shell hollow-structured nanoparticles by micro-nano bubbles, characterized in that, Comprising: (1) Mix titanium tetrachloride and water mist to obtain a titanium dioxide solid / hydrochloric acid droplet mixture; (2) Through a micro-nano bubble generator, shear and mix the titanium dioxide solid / hydrochloric acid droplet mixture with tetraethyl orthosilicate liquid to obtain micro-nano bubbles; (3) Separate, dry the precipitate, and calcine it to obtain core-shell hollow structure nanoparticles.

2. The method according to claim 1, characterized in that, Step (1) further includes: Add 8-15 parts by weight of titanium tetrachloride to a 10-15 L closed container with internal air circulation, introduce air with a humidity of 5-30%, and perform closed circulation for 1-4 hours.

3. The method according to claim 1, characterized in that, In step (2), based on the amount of titanium tetrachloride being 8-15 parts by weight, the addition amount of the tetraethyl orthosilicate liquid is 80-120 parts by weight.

4. The method according to claim 3, characterized in that, The addition amount of the tetraethyl orthosilicate liquid is 90-110 parts by weight.

5. The method according to claim 1, characterized in that, In step (2), the diameter of the micro-nano bubbles is 200-1000 nanometers.

6. The method according to claim 1, characterized in that, In step (2), the shearing time is 3-9 hours.

7. The method according to claim 1, characterized in that, In step (3), the calcination temperature is 400-500 °C and the calcination time is 1-3 hours.

8. The method according to claim 1, characterized in that, In step (3), the drying temperature is 70-90 °C and the drying time is 10-15 hours.

9. The method according to claim 1, characterized in that, In step (3), the separation is performed by centrifugation.

10. A method for preparing core-shell hollow-structured nanoparticles by micro-nano bubbles, characterized in that, Comprising: (1) Add 8-15 parts by weight of titanium tetrachloride to a closed container, introduce air with a humidity of 5-30%, and perform closed circulation for 1-4 hours to obtain a titanium dioxide solid / hydrochloric acid droplet mixture; (2) Through a micro-nano bubble generator, shear and mix the titanium dioxide solid / hydrochloric acid droplet mixture with 80-120 parts by weight of tetraethyl orthosilicate liquid, with a shearing time of 3-9 hours, to obtain micro-nano bubbles, and the particle size of the micro-nano bubbles is 200-1000 nanometers; (3) Centrifugally separate, dry the precipitate at 70-90 °C, and calcine it at 400-500 °C to obtain core-shell hollow structure nanoparticles.

11. A method for preparing core-shell hollow-structured nanoparticles by micro-nano bubbles, characterized in that, Comprising: (1) Add 10 parts by weight of titanium tetrachloride to a closed container, introduce air with a humidity of 5-30%, and perform closed circulation for 1-4 hours to obtain a titanium dioxide solid / hydrochloric acid droplet mixture; (2) Through a micro-nano bubble generator, shear and mix the titanium dioxide solid / hydrochloric acid droplet mixture with 100 parts by weight of tetraethyl orthosilicate liquid, with a shearing time of 3-9 hours, to obtain micro-nano bubbles, and the particle size of the micro-nano bubbles is 200-1000 nanometers; (3) Centrifugally separate, dry the precipitate at 80 °C, and calcine it at 400-500 °C to obtain core-shell hollow structure nanoparticles.

12. A core-shell hollow-structured nanoparticle, characterized in that, Prepared by the method according to any one of claims 1-11.

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