Three-level structure titanium dioxide microspheres and preparation method thereof

Abstract

The present invention relates to a tertiary structure titanium dioxide microsphere and a preparation method thereof. The preparation method comprises: preparing a dispersion of titanium dioxide nanospheres by an alkoxide hydrolysis method; preparing secondary structure titanium dioxide microspheres by electrostatic spraying the dispersion of titanium dioxide nanospheres, wherein the secondary structure titanium dioxide microspheres are composed of stacked titanium dioxide nanospheres; mixing an inorganic titanium salt with water at 120°C-140°C for a first hydrothermal treatment, cooling to 30°C-50°C after the reaction, adding glycerol monostearate and mixing to obtain a precursor solution; mixing the precursor solution with the secondary structure titanium dioxide microspheres and heating to 160°C-190°C for a second hydrothermal treatment to obtain tertiary structure titanium dioxide microspheres. The tertiary structure titanium dioxide microspheres obtained by the preparation method have a hierarchical porous interconnected network and can achieve an excellent water-conducting effect.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium dioxide nanomaterials, in particular to a titanium dioxide microsphere with a tertiary structure and a preparation method thereof. Background Art

[0002] Traditionally, additives are added to modify the hydrophilicity or hydrophobicity of a material. However, this approach essentially only improves the surface polarity of the material and cannot achieve water conductivity. Although one-dimensional materials with varying hydrophilicity or hydrophobicity can be stacked layer by layer to achieve a gradient of hydrophilicity or hydrophobicity, thereby achieving directional water conduction, such layer stacking often results in interlayer separation due to a lack of interlayer interaction. This leads to a loss of negative pressure due to air intrusion, reducing sustained water conductivity. Furthermore, the layer stacking process for one-dimensional materials is cumbersome and expensive, making it difficult to achieve widespread application. Summary of the Invention

[0003] Based on this, it is necessary to provide a tertiary structure titanium dioxide microsphere and a preparation method thereof to address the above problems; the tertiary structure titanium dioxide microspheres prepared by the preparation method have a hierarchical porous interconnected network, which can achieve an efficient and long-lasting water-conducting effect.

[0004] A method for preparing tertiary structure titanium dioxide microspheres comprises the following steps:

[0005] The dispersion of titanium dioxide nanospheres was prepared by alkoxide hydrolysis method;

[0006] preparing secondary structure titanium dioxide microspheres by electrostatic spraying the dispersion of the titanium dioxide nanospheres, wherein the secondary structure titanium dioxide microspheres are formed by stacking the titanium dioxide nanospheres;

[0007] Mixing an inorganic titanium salt with water and performing hydrothermal treatment at 120°C-140°C, cooling the mixture to 30°C-50°C after the reaction, adding glyceryl monostearate while maintaining the temperature and mixing the mixture to obtain a precursor solution;

[0008] The precursor solution is mixed with the secondary structure titanium dioxide microspheres and the temperature is raised to 160° C.-190° C. for secondary hydrothermal treatment, so that titanium dioxide grains grow on the surface of the titanium dioxide nanospheres to obtain tertiary structure titanium dioxide microspheres.

[0009] In one embodiment, the particle size of the titanium dioxide nanospheres is 40nm-80nm;

[0010] In one embodiment, the particle size of the titanium dioxide grains is less than or equal to 10 nm.

[0011] In one embodiment, in the step of mixing the inorganic titanium salt with water and performing a hydrothermal treatment, the concentration of the inorganic titanium salt in the water is 10 mg / L-55 mg / L.

[0012] In one embodiment, the mass ratio of the inorganic titanium salt to the glyceryl monostearate is 1:100-11:20;

[0013] And / or, the mass ratio of the inorganic titanium salt to the secondary structure titanium dioxide microspheres is 1:800-11:2000.

[0014] In one embodiment, the inorganic titanium salt is selected from at least one of titanyl sulfate and titanium tetrachloride.

[0015] In one embodiment, in the step of subjecting the dispersion of titanium dioxide nanospheres to electrostatic spraying, the spraying rate of the dispersion of titanium dioxide nanospheres is 0.3 mL / h-0.7 mL / h.

[0016] In one embodiment, the hydrothermal reaction time is 8h-16h;

[0017] And / or, the secondary hydrothermal reaction time is 8h-24h.

[0018] In one embodiment, the step of preparing a dispersion of titanium dioxide nanospheres by an alkoxide hydrolysis method comprises:

[0019] mixing the organic titanium salt with ethanol to obtain a first mixed solution;

[0020] mixing acetone and water to obtain a second mixed solution;

[0021] The first mixed liquid and the second mixed liquid are mixed and aged to obtain a dispersion of titanium dioxide nanospheres.

[0022] The preparation method of the present invention first adopts an alkoxide hydrolysis method to prepare titanium dioxide nanospheres as a primary structure, and then uses electrostatic spraying to make the titanium dioxide nanospheres accumulate and agglomerate to form titanium dioxide microspheres with a secondary structure, and the surface and interior of the titanium dioxide microspheres with the secondary structure have interconnected pores formed by the accumulation of titanium dioxide nanospheres.

[0023] At the same time, the inorganic titanium salt forms titanium dioxide seed crystals in a hydrothermal reaction at 120°C-140°C, and glyceryl monostearate is uniformly mixed with the reaction solution containing the titanium dioxide seed crystals at 30°C-50°C to form a precursor solution. Furthermore, after the precursor solution is mixed with the secondary structure titanium dioxide microspheres, the titanium dioxide seed crystals are fully anchored on the surface of all titanium dioxide nanospheres through the interconnected pores and the large specific surface area of ​​the secondary structure under high temperature conditions of 160°C-190°C, and continue to grow to form titanium dioxide grains. At the same time, the surface anchoring growth of the titanium dioxide seed crystals can limit the self-aggregation and spherical growth of the titanium dioxide seed crystals, thereby, with the cooperation of glyceryl monostearate, the titanium dioxide grains are densely and evenly distributed on the surface of the titanium dioxide nanospheres.

[0024] Therefore, the preparation method of the present invention constructs tertiary structure titanium dioxide microspheres during the preparation process. In addition, the preparation process is simple and the conditions are easy to control, which is conducive to large-scale industrial production and has great market application potential.

[0025] A tertiary structure titanium dioxide microsphere is prepared by the preparation method of the tertiary structure titanium dioxide microsphere as described above, wherein the tertiary structure titanium dioxide microsphere comprises a secondary structure titanium dioxide microsphere and titanium dioxide grains, wherein the secondary structure titanium dioxide microsphere is composed of an accumulation of titanium dioxide nanospheres, and the titanium dioxide grains are distributed on the surface of the titanium dioxide nanospheres.

[0026] In the tertiary structure titanium dioxide microspheres described in the present invention, nanometer-scale pores are formed between titanium dioxide grains, submicrometer-scale pores are formed between titanium dioxide grains and titanium dioxide nanospheres, and micrometer-scale pores are formed between titanium dioxide nanospheres. Therefore, the tertiary structure titanium dioxide microspheres have a regular pore size distribution structure with continuous progression from nanometer to submicrometer to micrometer. By utilizing the progressive capillary tension in the structure, the transmission resistance of all pores in the tertiary structure titanium dioxide microspheres is minimized to a certain extent, thereby enabling liquid media to be efficiently transferred and exchanged in the tertiary structure titanium dioxide microspheres, which is beneficial to improving the water conduction effect.

[0027] Therefore, the tertiary structure titanium dioxide microspheres have a hierarchical porous interconnected network structure, and based on their unique structure, can be applied to multiple technical fields, especially suitable for technical fields such as water conduction and moisture absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a transmission electron microscopy image of titanium dioxide nanospheres prepared in Example 1 of the present invention;

[0029] Figure 2 This is a scanning electron microscope image of the secondary structure titanium dioxide microspheres prepared in Example 1 of the present invention;

[0030] Figure 3 This is a scanning electron microscope image of the tertiary structure titanium dioxide microspheres prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] To facilitate understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments or embodiments and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, including any two related listed items, any more related listed items, or the combination of all related listed items.

[0033] The present invention provides a method for preparing tertiary structure titanium dioxide microspheres, comprising the following steps:

[0034] S1, preparing a dispersion of titanium dioxide nanospheres by alkoxide hydrolysis method;

[0035] S2, preparing secondary structure titanium dioxide microspheres by electrostatic spraying the dispersion of the titanium dioxide nanospheres, wherein the secondary structure titanium dioxide microspheres are composed of stacked titanium dioxide nanospheres;

[0036] S3, mixing an inorganic titanium salt with water at 120° C.-140° C. and performing a hydrothermal reaction, cooling the mixture to 30° C.-50° C. after the reaction, adding glyceryl monostearate while maintaining the temperature and mixing the mixture to obtain a precursor solution;

[0037] S4, mixing the precursor solution with the secondary structure titanium dioxide microspheres and heating the mixture to 160° C.-190° C. for secondary hydrothermal treatment to grow titanium dioxide grains on the surface of the titanium dioxide nanospheres to obtain tertiary structure titanium dioxide microspheres.

[0038] In step S1, the titanium dioxide nanospheres prepared by the alcohol salt hydrolysis method have uniform sizes, which can make the secondary structure titanium dioxide microspheres prepared subsequently have more regular shapes.

[0039] Preferably, the particle size of the titanium dioxide nanospheres is 40 nm to 80 nm, which is conducive to obtaining titanium dioxide microspheres with a secondary structure and an appropriate stacking pore size.

[0040] In one embodiment, the step of preparing a dispersion of titanium dioxide nanospheres by an alkoxide hydrolysis method comprises:

[0041] S11, mixing an organic titanium salt with ethanol to obtain a first mixed solution;

[0042] S12, mixing acetone and water to obtain a second mixed solution;

[0043] S13, mixing the first mixed liquid and the second mixed liquid and aging them to obtain a dispersion of titanium dioxide nanospheres.

[0044] In step S11, in the first mixed solution, the volume ratio of the organic titanium salt to the ethanol is preferably 1:200-3:10, which can make the distribution concentration of titanium ions in the first mixed solution appropriate, which is beneficial to controlling the hydrolysis reaction rate in the subsequent preparation process, thereby regulating the particle size of titanium dioxide nanospheres.

[0045] Specifically, the organic titanium salt includes at least one of tetrabutyl titanate, tetraethyl titanate, and tetraisopropyl titanate.

[0046] In one embodiment, the organic titanium salt and ethanol are mixed at room temperature for 6 hours to 12 hours, which is conducive to the organic titanium salt and ethanol being fully mixed.

[0047] In step S12, by mixing water and acetone, the hydrolysis reaction rate in the subsequent preparation process can be effectively controlled, so that the prepared titanium dioxide nanospheres are more uniform.

[0048] Preferably, the volume fraction of water in the second mixed liquid is 0.01%-0.1%.

[0049] Specifically, since acetone and water have good compatibility, acetone and water can be mixed for 3 minutes to 5 minutes.

[0050] In step S13, the first mixed solution is preferably added to the second mixed solution for mixing. Considering that if the first mixed solution is added too slowly, the reaction time of the titanium ions added first will be too long, resulting in a large difference in the particle size of the titanium dioxide nanospheres generated by the reaction with the later addition, it is preferred to add the first mixed solution to the second mixed solution for mixing in one step. At the same time, the volume ratio of water to organic titanium salt is preferably 1:200-3:5, which can effectively balance the problem of excessive hydrolysis reaction rate caused by the one-step addition, and is conducive to regulating the uniform growth of titanium dioxide nanospheres.

[0051] Specifically, the first mixed liquid is added to the second mixed liquid in one step, and stirred at a stirring speed of 1200 r / min-2000 r / min for 0.5 h-3 h.

[0052] Preferably, by aging for 0.5 h to 12 h, the titanium dioxide nanospheres can grow more uniformly, thereby making the size of the prepared titanium dioxide nanospheres more uniform.

[0053] It should be noted that the above-mentioned method for preparing a dispersion of titanium dioxide nanospheres by the alkoxide hydrolysis method is only an example of a specific implementation method of step S1. The present invention does not limit the specific preparation scheme for preparing a dispersion of titanium dioxide nanospheres by the alkoxide hydrolysis method, and those skilled in the art can make their own selection according to actual preparation requirements.

[0054] In step S2, electrostatic spraying is used to cause titanium dioxide nanospheres to accumulate and agglomerate to form secondary structure titanium dioxide microspheres, and the surface and interior of the secondary structure titanium dioxide microspheres have interconnected pores formed by the accumulation of titanium dioxide nanospheres, which is beneficial to solving the problem of self-agglomeration of nano-scale titanium dioxide during use.

[0055] It should be noted that the present invention does not limit the particle size of the secondary structure titanium dioxide microspheres, and those skilled in the art can choose the particle size according to actual application requirements.

[0056] Preferably, in the step of subjecting the dispersion of titanium dioxide nanospheres to electrostatic spraying, the spraying rate of the dispersion of titanium dioxide nanospheres is 0.3 mL / h-0.7 mL / h.

[0057] In one embodiment, a syringe is used as the main device for electrostatic spraying, wherein the stainless steel needle at one end of the syringe is connected to a positive high-voltage power supply to provide a high-voltage electrostatic field condition for spraying, and the distance between the stainless steel needle and the roller receiver is 20 cm-30 cm. By recovering the titanium dioxide particles sprayed onto the roller receiver, secondary structure titanium dioxide microspheres are obtained.

[0058] In step S3, the primary hydrothermal reaction temperature is controlled to 120°C-140°C. Due to the low primary hydrothermal reaction temperature, the inorganic titanium salt forms titanium dioxide seeds during the primary hydrothermal reaction and does not grow to form grains or nanospheres. Furthermore, after the reaction, the temperature is lowered to 30°C-50°C before adding glyceryl monostearate, ensuring that the glyceryl monostearate is evenly mixed with the reaction solution containing the titanium dioxide seeds to form a precursor solution.

[0059] Preferably, in the step of mixing the inorganic titanium salt with water for a hydrothermal reaction, the concentration of the inorganic titanium salt in water is 10 mg / L-55 mg / L, which is conducive to the formation of a titanium dioxide seed dispersion with an appropriate concentration of titanium ions at a hydrothermal reaction temperature of 120°C-140°C, and is conducive to the formation of compact and uniform titanium dioxide grains on the surface of the titanium dioxide nanospheres in the subsequent preparation process.

[0060] Preferably, the mass ratio of the inorganic titanium salt to the glyceryl monostearate is 1:100-11:20, which can anchor the titanium dioxide seeds on the surface of the titanium dioxide nanospheres through chemical bonds, while enhancing the binding force between the titanium dioxide seeds and the titanium dioxide nanospheres through glyceryl monostearate, which is beneficial to improving the structural stability of the tertiary structure titanium dioxide microspheres.

[0061] Specifically, the inorganic titanium salt is selected from at least one of titanyl sulfate and titanium tetrachloride.

[0062] In one embodiment, the inorganic titanium salt is first mixed with water for 20 minutes to completely dissolve the inorganic titanium salt, and then hydroheated at 120°C to 140°C. After reacting for 8 hours to 16 hours, the temperature is lowered to 30°C to 50°C. Glyceryl monostearate is added under the heat preservation state and the mixture is kept warm and mixed for 1 hour to 3 hours to obtain a precursor solution.

[0063] It should be noted that the present invention does not limit the order of preparation of steps 1-2 and 3. Those skilled in the art may prepare step 1-2 first and then step 3; may prepare step 3 first and then step 1-2; or may prepare step 1-2 and step 3 simultaneously.

[0064] In step S4, after the precursor solution is mixed with the secondary structure titanium dioxide microspheres, under high temperature conditions of 160°C-190°C, the titanium dioxide seeds can be fully anchored on the surface of all titanium dioxide nanospheres through the interconnected pores and the large specific surface area of ​​the secondary structure, and continue to grow to form titanium dioxide grains. At the same time, the surface anchored growth of the titanium dioxide seeds can limit the self-aggregation of the titanium dioxide seeds into spheres, thereby making the titanium dioxide grains tightly and evenly distributed on the surface of the titanium dioxide nanospheres with the cooperation of glycerol monostearate.

[0065] Among them, nanoscale pores are formed between titanium dioxide grains, submicron pores are formed between titanium dioxide grains and titanium dioxide nanospheres, and micron pores are formed between titanium dioxide nanospheres. Therefore, the tertiary structure titanium dioxide microspheres have a regular pore size distribution structure with continuous progression from nanometer to submicron to micron, that is, a hierarchical porous interconnected network structure.

[0066] It should be noted that titanium dioxide crystals are distributed on the surface of all titanium dioxide nanospheres, that is, titanium dioxide crystals are distributed on the surface and inside of the secondary structure titanium dioxide microspheres.

[0067] Preferably, the particle size of the titanium dioxide crystals is less than or equal to 10 nm, more preferably 4 nm to 8 nm, which is conducive to forming a hierarchical porous interconnected network structure.

[0068] Preferably, the mass ratio of the inorganic titanium salt to the secondary structure titanium dioxide microspheres is 1:800-11:2000, which is more conducive to the formation of compact and uniform titanium dioxide grains on the surface of the titanium dioxide nanospheres.

[0069] In one embodiment, the precursor solution is mixed with the secondary structure titanium dioxide microspheres, and then hydrothermally heated for a second time at 160° C.-190° C. for 8 h-24 h under stirring. After the reaction, the mixture is washed to obtain the tertiary structure titanium dioxide microspheres.

[0070] Therefore, the preparation method of the present invention constructs tertiary structure titanium dioxide microspheres during the preparation process. In addition, the preparation process is simple and the conditions are easy to control, which is conducive to large-scale industrial production and has great market application potential.

[0071] A tertiary structure titanium dioxide microsphere is prepared by the preparation method of the tertiary structure titanium dioxide microsphere as described above, wherein the tertiary structure titanium dioxide microsphere comprises a secondary structure titanium dioxide microsphere and titanium dioxide grains, wherein the secondary structure titanium dioxide microsphere is composed of an accumulation of titanium dioxide nanospheres, and the titanium dioxide grains are distributed on the surface of the titanium dioxide nanospheres.

[0072] In the tertiary structure titanium dioxide microspheres described in the present invention, nanometer-scale pores are formed between titanium dioxide grains, submicrometer-scale pores are formed between titanium dioxide grains and titanium dioxide nanospheres, and micrometer-scale pores are formed between titanium dioxide nanospheres. Therefore, the tertiary structure titanium dioxide microspheres have a regular pore size distribution structure with continuous progression from nanometer to submicrometer to micrometer. By utilizing the progressive capillary tension in the structure, the transmission resistance of all pores in the tertiary structure titanium dioxide microspheres is minimized to a certain extent, thereby enabling efficient transfer and exchange of media such as gas and liquid in the tertiary structure titanium dioxide microspheres, which is beneficial to improving the water conduction effect.

[0073] In addition, in the hierarchical porous interconnected network structure of the tertiary structure titanium dioxide microspheres, a variety of different functional substances can be filled to give the titanium dioxide microspheres diversified properties, which is conducive to broadening the application value and application scope of titanium dioxide microspheres.

[0074] Preferably, the particle size of the titanium dioxide nanospheres is 40 nm-80 nm; and / or the particle size of the titanium dioxide crystal grains is less than or equal to 10 nm.

[0075] More preferably, the particle size of the titanium dioxide nanospheres is 40 nm to 80 nm, and the particle size of the titanium dioxide grains is 4 nm to 8 nm.

[0076] Hereinafter, the tertiary structure titanium dioxide microspheres and the preparation method thereof will be further described through the following specific examples.

[0077] Example 1

[0078] 0.5 mL of tetrabutyl titanate was added to 10 mL of ethanol and stirred at room temperature for 6 h to obtain a first mixed solution. Deionized water was added dropwise to 150 mL of acetone solution and stirred for 3 min to obtain a second mixed solution, wherein the volume fraction of ionized water in the second mixed solution was 0.01%. The first mixed solution was quickly poured into the second mixed solution and stirred at a stirring speed of 1200 r / min for 0.5 h, and then aged at room temperature for 2 h to obtain a dispersion of titanium dioxide nanospheres. The structure of the prepared titanium dioxide nanospheres was observed using a transmission electron microscope, as shown in FIG. Figure 1 As shown, the titanium dioxide nanospheres are uniform in size, with a particle size of about 60 nm.

[0079] The dispersion of titanium dioxide nanospheres was placed in a syringe and subjected to high-voltage electrostatic field spraying at a voltage of 23kV and an injection rate of 0.5mL / h under the conditions of an ambient temperature of 30±2°C and a humidity of 30±5%. The rotation speed of the roller receiver was set to 15r / min, and the distance between the stainless steel needle of the syringe and the roller receiver was 20cm. After the spraying was completed, the particles on the roller receiver were recovered to obtain secondary structure titanium dioxide microspheres. The structure of the prepared secondary structure titanium dioxide microspheres was observed using a scanning electron microscope, as shown in FIG. Figure 2 As shown, the secondary structure titanium dioxide microspheres are composed of stacked titanium dioxide nanospheres, and the particle size of the secondary structure titanium dioxide microspheres is about 300 nm.

[0080] Add 100 mL of deionized water and 1 mg of TiOSO4 to a hydrothermal reactor and stir magnetically for 20 minutes. Then, perform a hydrothermal reaction at 120°C for 8 hours. After the reaction, cool to 30°C. Immediately after opening the lid, add 10 mg of glyceryl monostearate and maintain stirring at 30°C for 1 hour to obtain a precursor solution.

[0081] 1 g of secondary structure titanium dioxide microspheres was added to the precursor solution, and the temperature was raised to 180° C. again while maintaining magnetic stirring, and the hydrothermal reaction was carried out for 10 hours. After the reaction was completed, the solution was washed with water and alcohol several times, and the tertiary structure titanium dioxide microspheres were obtained after centrifugal separation.

[0082] The structure of the prepared tertiary structure titanium dioxide microspheres was observed using a scanning electron microscope. Figure 3 As shown, the tertiary structure titanium dioxide microspheres include secondary structure titanium dioxide microspheres and titanium dioxide grains, wherein the secondary structure titanium dioxide microspheres are composed of stacked titanium dioxide nanospheres, and the titanium dioxide grains are distributed on the surface of the titanium dioxide nanospheres, and the particle size of the titanium dioxide grains is about 10nm.

[0083] Example 2

[0084] 2 mL of tetrabutyl titanate was added to 50 mL of ethanol and stirred at room temperature for 10 hours to obtain a first mixed solution. Deionized water was added dropwise to 200 mL of acetone solution and stirred for 3 minutes to obtain a second mixed solution, wherein the volume fraction of deionized water in the second mixed solution was 0.05%. The first mixed solution was quickly poured into the second mixed solution and stirred at a stirring speed of 1500 rpm for 1.5 hours, followed by aging at room temperature for 4 hours to obtain a dispersion of titanium dioxide nanospheres with a particle size of approximately 75 nm.

[0085] The dispersion of titanium dioxide nanospheres was placed in a syringe and subjected to high-voltage electrostatic field spraying treatment at an ambient temperature of 30±2°C and a humidity of 30±5% at a voltage of 23kV and an injection rate of 0.6mL / h. The rotation speed of the roller receiver was set to 15r / min, and the distance between the stainless steel needle of the syringe and the roller receiver was 20cm. After the spraying was completed, the particles on the roller receiver were recovered to obtain secondary structure titanium dioxide microspheres.

[0086] Add 100 mL of deionized water and 5 mg of TiOSO4 to a hydrothermal reactor and stir magnetically for 60 minutes. Then, perform a hydrothermal reaction at 140°C for 16 hours. After the reaction, cool to 50°C. Immediately after opening the lid, add 80 mg of glyceryl monostearate and maintain stirring at 50°C for 3 hours to obtain a precursor solution.

[0087] 8 g of secondary structure titanium dioxide microspheres were added to the precursor solution, and the temperature was raised to 180° C. again while maintaining magnetic stirring, and the solution was hydrothermally reacted for 20 h. After the reaction, the solution was washed with water and alcohol several times, and the tertiary structure titanium dioxide microspheres were obtained after centrifugal separation.

[0088] Example 3

[0089] 3 mL of tetraisopropyl titanate was added to 100 mL of ethanol and stirred at room temperature for 12 hours to obtain a first mixed solution. Deionized water was added dropwise to 300 mL of acetone solution and stirred for 3 minutes to obtain a second mixed solution, wherein the volume fraction of deionized water in the second mixed solution was 0.1%. The first mixed solution was quickly poured into the second mixed solution and stirred at a stirring speed of 2000 rpm for 3 hours. The mixture was then aged at room temperature for 10 hours to obtain a dispersion of titanium dioxide nanospheres with a particle size of approximately 50 nm.

[0090] The dispersion of titanium dioxide nanospheres was placed in a syringe and subjected to high-voltage electrostatic field spraying treatment at an ambient temperature of 30±2°C and a humidity of 30±5% at a voltage of 23kV and an injection rate of 0.7mL / h. The rotation speed of the roller receiver was set to 15r / min, and the distance between the stainless steel needle of the syringe and the roller receiver was 30cm. After the spraying was completed, the particles on the roller receiver were recovered to obtain secondary structure titanium dioxide microspheres.

[0091] Add 100 mL of deionized water and 3.5 mg of TiCl₄ to a hydrothermal reactor and stir magnetically for 45 minutes. Then, conduct a hydrothermal reaction at 135°C for 12 hours. After the reaction, cool to 35°C. Immediately after opening the lid, add 50 mg of glyceryl monostearate and maintain stirring at 35°C for 2 hours to obtain a precursor solution.

[0092] 6 g of secondary structure titanium dioxide microspheres were added to the precursor solution, and the temperature was raised to 170° C. again while maintaining magnetic stirring, and the hydrothermal reaction was carried out for 16 hours. After the reaction was completed, the solution was washed with water and alcohol several times, and the tertiary structure titanium dioxide microspheres were obtained after centrifugal separation.

[0093] Comparative Example 1

[0094] Titanium dioxide nanospheres and a precursor solution were prepared using the same preparation method as in Example 1.

[0095] 1 g of titanium dioxide nanospheres was added to the precursor solution, and the temperature was raised to 180° C. again while maintaining magnetic stirring, and the hydrothermal reaction was carried out for 10 hours. After the reaction was completed, a titanium dioxide mixed dispersion was obtained.

[0096] The titanium dioxide mixed dispersion is placed in a syringe and subjected to high-voltage electrostatic field spraying treatment at an ambient temperature of 30±2°C and a humidity of 30±5% at a voltage of 23kV and an injection rate of 0.5mL / h. The rotation speed of the roller receiver is set to 15r / min, and the distance between the stainless steel needle of the syringe and the roller receiver is 20cm. After the spraying is completed, the particles on the roller receiver are recovered to obtain titanium dioxide microspheres.

[0097] Comparative Example 2

[0098] The difference between Comparative Example 2 and Example 1 is that tetrabutyl titanate is used instead of TiOSO4.

[0099] Comparative Example 3

[0100] The difference between Comparative Example 3 and Example 1 is that glyceryl monostearate is not added.

[0101] Comparative Example 4

[0102] The difference between Comparative Example 4 and Example 1 is that the reaction temperature of the first hydrothermal step is 160°C.

[0103] Comparative Example 5

[0104] The difference between Comparative Example 5 and Example 1 is that TiOSO4, glyceryl monostearate and secondary structure titanium dioxide microspheres are directly mixed and then subjected to a hydrothermal reaction at 180°C.

[0105] The performance tests of Examples 1-3 and Comparative Examples 1-5 were conducted in accordance with the national standard GB / T21655.1-2008. The test results are shown in Table 1.

[0106] Table 1

[0107]

[0108] According to Table 1, the tertiary structure titanium dioxide microspheres prepared in Examples 1-3 can achieve excellent water-conducting effect.

[0109] In Comparative Example 1, since the anchor points on the surface of titanium dioxide nanospheres are much smaller than the secondary structure, during the hydrothermal reaction, titanium dioxide grains tend to self-agglomerate to form a microstructure under the action of surface tension. Therefore, the tertiary structure is not prepared by spraying treatment, and the water conduction effect is poor.

[0110] In Comparative Example 2, tetrabutyl titanate was used instead of TiOSO4, resulting in an excessively fast hydrolysis rate, causing irregular and uncontrollable morphology, failure to prepare a tertiary structure, and poor water-conducting performance.

[0111] In Comparative Example 3, since glyceryl monostearate was not added, the nanoparticles could not be spherical, could not form a tertiary structure, and had poor water-conducting performance.

[0112] In Comparative Example 4, since the reaction temperature of the first hydrothermal reaction is too high, the titanium dioxide grains grown in the first hydrothermal reaction are larger, and the mixed liquid after the first hydrothermal reaction is not sufficient to provide sufficient anchoring conditions for the titanium dioxide microspheres. Therefore, it is difficult to form a tertiary structure titanium dioxide microspheres with a hierarchical porous interconnected network, and the water conductivity is not as good as that of Examples 1-3.

[0113] Comparative Example 5 adopts direct mixing hydrothermal reaction, and the titanium dioxide grains fail to grow anchored on the surface of the titanium dioxide microspheres, resulting in the obtained products being independently dispersed titanium dioxide grains and secondary titanium dioxide microspheres. Therefore, the water-conducting effect is not as good as that of Examples 1-3.

[0114] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing tertiary structure titanium dioxide microspheres, characterized in that: The steps include: A dispersion of titanium dioxide nanospheres is prepared by an alkoxide hydrolysis method: an organic titanium salt is mixed with ethanol to obtain a first mixed solution, acetone is mixed with water to obtain a second mixed solution, and the first mixed solution and the second mixed solution are mixed and aged to obtain a dispersion of titanium dioxide nanospheres; preparing secondary structure titanium dioxide microspheres by electrostatically spraying the dispersion of the titanium dioxide nanospheres, wherein the secondary structure titanium dioxide microspheres are formed by stacking the titanium dioxide nanospheres; Mixing an inorganic titanium salt with water and performing hydrothermal treatment at 120°C-140°C, cooling the mixture to 30°C-50°C after the reaction, adding glyceryl monostearate while maintaining the temperature and mixing the mixture to obtain a precursor solution; The precursor solution is mixed with the secondary structure titanium dioxide microspheres and the temperature is raised to 160° C.-190° C. for secondary hydrothermal treatment, so that titanium dioxide grains grow on the surface of the titanium dioxide nanospheres to obtain tertiary structure titanium dioxide microspheres. The tertiary structure titanium dioxide microspheres have a regular pore size distribution structure with continuous progression from nanometer to submicron to micron.

2. The method for preparing tertiary structure titanium dioxide microspheres according to claim 1, characterized in that: The particle size of the titanium dioxide nanospheres is 40nm-80nm.

3. The method for preparing tertiary structure titanium dioxide microspheres according to claim 1, characterized in that: The particle size of the titanium dioxide grains is less than or equal to 10 nm.

4. The method for preparing tertiary structure titanium dioxide microspheres according to claim 1, characterized in that: In the step of mixing the inorganic titanium salt with water and performing a hydrothermal treatment, the concentration of the inorganic titanium salt in the water is 10 mg / L-55 mg / L.

5. The method for preparing tertiary structure titanium dioxide microspheres according to claim 1, characterized in that: The mass ratio of the inorganic titanium salt to the glyceryl monostearate is 1:100-11:20; And / or, the mass ratio of the inorganic titanium salt to the secondary structure titanium dioxide microspheres is 1:800-11:2000.

6. The method for preparing tertiary structure titanium dioxide microspheres according to claim 1, characterized in that: The inorganic titanium salt is selected from at least one of titanyl sulfate and titanium tetrachloride.

7. The method for preparing tertiary structure titanium dioxide microspheres according to claim 1, characterized in that: In the step of subjecting the dispersion of titanium dioxide nanospheres to electrostatic spraying, the spraying rate of the dispersion of titanium dioxide nanospheres is 0.3 mL / h-0.7 mL / h.

8. The method for preparing tertiary structure titanium dioxide microspheres according to claim 1, characterized in that: The primary hydrothermal reaction time is 8h-16h; And / or, the secondary hydrothermal reaction time is 8h-24h.

9. A tertiary structure titanium dioxide microsphere, characterized in that: The tertiary structure titanium dioxide microspheres are prepared by the preparation method of any one of claims 1 to 8, wherein the tertiary structure titanium dioxide microspheres include secondary structure titanium dioxide microspheres and titanium dioxide grains, wherein the secondary structure titanium dioxide microspheres are composed of stacked titanium dioxide nanospheres, and the titanium dioxide grains are distributed on the surface of the titanium dioxide nanospheres.

Images