A preparation method of water-soluble nitrogen-doped titanium dioxide dispersion and its product and application

Abstract

The invention discloses a preparation method of a water-soluble nitrogen-doped titanium dioxide dispersion, a product and an application thereof, wherein a titanate is added to a short-chain alcohol, and stirred at room temperature to obtain a premix; the premix is ​​added to an acidic aqueous solution, heated to 60-90°C and stirred for reaction to obtain a titanium dioxide dispersion; the temperature is lowered to 40-45°C and a nitrogen source triethylamine is added to the titanium oxide dispersion, and stirred for reaction to obtain a water-soluble nitrogen-doped titanium dioxide dispersion. The nitrogen-doped titanium dioxide dispersion of the invention has mild preparation conditions, does not require high temperature and high pressure, has high production process safety, low preparation cost, and significantly improves product stability, has high transparency, and does not precipitate in an aqueous solution environment with a pH of 1-14.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and specifically relates to a preparation method of a water-soluble nitrogen-doped titanium dioxide dispersion, a product thereof and an application thereof. Background Art

[0002] Titanium dioxide (TiO2) is widely used in cosmetics due to its excellent physical and chemical properties. First, titanium dioxide is a physical sunscreen that can reflect ultraviolet rays and protect the skin from UVA and UVB. It is widely used in sunscreens and other sunscreen products, usually in the form of nano-scale particles to provide effective UV protection. Secondly, titanium dioxide is often used as a white pigment due to its excellent hiding power, giving products an opaque or whitening effect, and is widely used in many fields such as cosmetics (such as foundation, eye shadow), personal care products (such as toothpaste, soap) and coatings.

[0003] Nitrogen-doped titanium dioxide exhibits higher photosensitivity and photostability than titanium dioxide. At the same time, nitrogen-doped titanium dioxide can absorb a wider spectrum. Therefore, nitrogen-doped titanium dioxide has very high application value in the fields of cosmetics, coatings and environmental governance. At present, nitrogen-doped titanium dioxide is mainly prepared by high pressure method or high temperature calcination method, and the preparation process is low in safety and high in production cost. On the other hand, highly stable water-dispersible nitrogen-doped titanium dioxide is rarely reported. The water-dispersible nitrogen-doped nano-titanium dioxide prepared by low-temperature hydrothermal method described in patent application number 200510011165.3 still requires secondary dispersion during actual use. A visible light responsive photocatalytic spray described in patent application number 201410298480.4 still uses nitrogen-doped nano-titanium dioxide prepared by patent number 200510011165.3 in its preparation. Therefore, the preparation of water-dispersible nitrogen-doped nano-titanium dioxide at normal pressure and low temperature is still a challenging task. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and to briefly introduce some preferred embodiments.

[0005] As one aspect of the present invention, the present invention provides a method for preparing a water-soluble nitrogen-doped titanium dioxide dispersion, which comprises the following steps: (1) adding a titanate ester to a short-chain alcohol and stirring at room temperature to obtain a premix; the titanate ester includes tetrabutyl titanate; (2) adding the premix into an acidic aqueous solution, heating to 60-90° C. and stirring to react, thereby obtaining a titanium dioxide dispersion; (3) Cooling the mixture to 40-45° C. and adding the nitrogen source triethylamine to the titanium dioxide dispersion obtained in step (2), stirring the mixture to react and obtaining a water-soluble nitrogen-doped titanium dioxide dispersion.

[0006] A preferred embodiment of the method for preparing the water-soluble nitrogen-doped titanium dioxide dispersion of the present invention is as follows: in step (2), the acidic aqueous solution is a hydrochloric acid aqueous solution, and the mass concentration of the salt water aqueous solution is 0.6-3%.

[0007] A preferred embodiment of the method for preparing the water-soluble nitrogen-doped titanium dioxide dispersion of the present invention is as follows: in step (1), the short-chain alcohol comprises one or more of methanol, ethanol, propanol or butanol.

[0008] A preferred embodiment of the method for preparing the water-soluble nitrogen-doped titanium dioxide dispersion of the present invention is as follows: in step (1), the mass ratio of titanate to short-chain alcohol is 0.3-0.7:1.

[0009] A preferred embodiment of the method for preparing the water-soluble nitrogen-doped titanium dioxide dispersion of the present invention is as follows: in step (1), the stirring at room temperature to obtain the premix is ​​performed at 200-800 r / min for 0.1-2 hours.

[0010] A preferred embodiment of the method for preparing the water-soluble nitrogen-doped titanium dioxide dispersion of the present invention is as follows: in step (2), the mass ratio of the premix to the acidic aqueous solution is 0.1-0.2:1.

[0011] A preferred embodiment of the method for preparing the water-soluble nitrogen-doped titanium dioxide dispersion of the present invention is as follows: in step (2), the stirring reaction is carried out at 200-800 r / min for 1-5 h.

[0012] A preferred embodiment of the method for preparing the water-soluble nitrogen-doped titanium dioxide dispersion of the present invention is as follows: in step (3), the mass ratio of triethylamine to titanium dioxide dispersion is 0.01-0.05:1; and the stirring reaction is carried out at 200-800 r / min for 2-24 hours.

[0013] Beneficial effects of the present invention: Compared with the prior art, the nitrogen-doped titanium dioxide dispersion of the present invention has mild preparation conditions, does not require high temperature and high pressure, has high production process safety, low preparation cost, and significantly improved product stability. The obtained product has high transparency and will not precipitate in an aqueous solution environment with a pH of 1 to 14. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following briefly introduces the drawings required for describing the embodiment, wherein: Figure 1This is the XRD spectrum of nitrogen-doped titanium dioxide in Example 1.

[0015] Figure 2 This is the antibacterial effect of the product in Example 1.

[0016] Figure 3 This is the antibacterial effect of the titanium dioxide dispersion in Comparative Example 7.

[0017] Figure 4 This is the antibacterial effect of the supernatant of the product in Comparative Example 5.

[0018] Figure 5 This is the antibacterial effect of the supernatant of the product in Comparative Example 6.

[0019] Figure 6 The following are product photos of Example 1 and Comparative Examples 1-6. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0021] Embodiment 1: (1) Add 4.0 g of tetrabutyl titanate to 10 g of ethanol and stir at 500 r / min for 1 hour to obtain a premix; (2) Add 1.8 g of 37% concentrated hydrochloric acid into 100 g of deionized water and stir to obtain a hydrochloric acid solution; (3) adding the premix prepared in step (1) to the hydrochloric acid solution prepared in step (2), heating to 80° C. at 300 r / min while stirring, and reacting for 2 hours to obtain a titanium dioxide dispersion; (4) The titanium dioxide dispersion obtained in step (3) was cooled to 40°C, and then 1.5 g of triethylamine was added thereto. The mixture was stirred at 300 r / min for 10 h to prepare a water-soluble nitrogen-doped titanium dioxide dispersion.

[0022] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the 1.8 g of concentrated hydrochloric acid in step (2) is replaced by 0.5 g of concentrated hydrochloric acid, and the other conditions are the same as those in Example 1.

[0023] Experimental results: A blue transparent water-soluble nitrogen-doped titanium dioxide dispersion could not be obtained, but a milky white product with a large amount of white precipitate was obtained.

[0024] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that in step (4), the titanium dioxide dispersion obtained in step (3) is cooled to 60°C, 1.5 g of triethylamine is added thereto, and the reaction is carried out under stirring at 300 r / min for 10 h. The other conditions are the same as those in Example 1.

[0025] Experimental results: It was not possible to prepare a transparent, blue water-soluble nitrogen-doped titanium dioxide dispersion, but a translucent product containing a white precipitate was obtained. It is speculated that the high temperature may cause the triethylamine to decompose too quickly.

[0026] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the 1.5 g of triethylamine in step (4) is changed to 0.8 g of triethylamine, and the other conditions are the same as those in Example 1.

[0027] Experimental results: It is impossible to prepare a transparent, blue water-soluble nitrogen-doped titanium dioxide dispersion, but a translucent product containing a white precipitate is obtained. This is because the low content of triethylamine results in insufficient surface amino modification.

[0028] Comparative Example 4: (1) Add 4.0 g of tetrabutyl titanate to 10 g of ethanol and stir at 500 r / min for 1 hour to obtain a premix; (2) adding 1.5 g of triethylamine to the premix prepared in step (1), and reacting for 10 h under stirring at 300 r / min to obtain a nitrogen-doped prehydrolysis product; (3) Add 1.8 g of concentrated hydrochloric acid (mass concentration 37%) to 100 g of deionized water and stir evenly to obtain a hydrochloric acid solution; (4) Add the nitrogen-doped pre-hydrolyzed product prepared in step (2) to the hydrochloric acid solution prepared in step (3), heat to 80°C while stirring at 300 r / min, and react for 2 hours to obtain a nitrogen-doped titanium dioxide product.

[0029] Experimental results: It is not possible to prepare a transparent, blue water-soluble nitrogen-doped titanium dioxide dispersion, but a product containing a white precipitate is obtained. Adding triethylamine first will result in a larger particle size of the product.

[0030] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that tetrabutyl titanate is replaced with titanium tetrachloride, and other conditions are the same as those of Example 1.

[0031] Experimental results: It was not possible to prepare a transparent, blue water-soluble nitrogen-doped titanium dioxide dispersion, but instead a product containing a large amount of white precipitate was obtained.

[0032] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that triethylamine is replaced by aqueous ammonia, and other conditions are the same as those of Example 1.

[0033] Experimental results: It is impossible to prepare a transparent, blue water-soluble nitrogen-doped titanium dioxide dispersion, but a product containing a large amount of white precipitate is obtained. Ammonia water cannot effectively modify the surface, and the titanium dioxide particles obtained in the experiment are very large.

[0034] The appearance of the products obtained in Example 1 and Comparative Examples 1 to 6 and the stability test results of the product of Example 1 are shown in Table 1.

[0035] Stability test conditions: A certain amount of sample was placed in a sample bottle, adjusted to different pH values, sealed and stored at high temperature (50°C) for 3 months to examine its stability.

[0036] Comparative Example 7: (1) Add 4.0 g of tetrabutyl titanate to 10 g of ethanol and stir at 500 r / min for 1 hour to obtain a premix; (2) Add 1.8 g of 37% concentrated hydrochloric acid into 100 g of deionized water and stir to obtain a hydrochloric acid solution; (3) The premix prepared in step (1) was added to the hydrochloric acid solution prepared in step (2), and the mixture was heated to 80° C. while stirring at 300 r / min and reacted for 2 hours to obtain a titanium dioxide dispersion.

[0037] The antibacterial effect test of the product of Example 1 and the products of Comparative Examples 5, 6, and 7 is shown in Figures 2~5 .

[0038] Comparative Example 8: (1) Add 4.0 g of tetraethyl titanate to 10 g of ethanol and stir at 500 r / min for 1 hour to obtain a premix; (2) Add 1.8 g of 37% concentrated hydrochloric acid into 100 g of deionized water and stir to obtain a hydrochloric acid solution; (3) adding the premix prepared in step (1) to the hydrochloric acid solution prepared in step (2), heating to 80° C. at 300 r / min while stirring, and reacting for 2 hours to obtain a titanium dioxide dispersion; (4) The titanium dioxide dispersion obtained in step (3) was cooled to 40°C, and then 1.5 g of triethylamine was added thereto. The mixture was stirred at 300 r / min for 10 h to prepare a water-soluble nitrogen-doped titanium dioxide dispersion.

[0039] Experimental results: The prepared water-soluble nitrogen-doped titanium dioxide dispersion produced white precipitate, which may be due to the violent hydrolysis reaction of tetraethyl titanate.

[0040] Comparative Example 9:

[0041] (1) Add 4.0 g of isopropyl titanate to 10 g of ethanol and stir at 500 r / min for 1 hour to obtain a premix; (2) Add 1.8 g of 37% concentrated hydrochloric acid into 100 g of deionized water and stir to obtain a hydrochloric acid solution; (3) adding the premix prepared in step (1) to the hydrochloric acid solution prepared in step (2), heating to 80° C. at 300 r / min while stirring, and reacting for 2 hours to obtain a titanium dioxide dispersion; (4) The titanium dioxide dispersion obtained in step (3) was cooled to 40°C, and then 1.5 g of triethylamine was added thereto. The mixture was stirred at 300 r / min for 10 h to prepare a water-soluble nitrogen-doped titanium dioxide dispersion.

[0042] Experimental results: The transparency of the prepared water-soluble nitrogen-doped titanium dioxide dispersion is obviously not as high as that of Example 1, which may be due to the fast hydrolysis rate of isopropyl titanate.

[0043] Antibacterial test method: Inoculate Malassezia furfur into 200 mL of liquid culture medium, culture at 37°C for 24 h, and culture overnight at 220 r / min. Pour about 20 mL of plate culture medium into the sterilized plate, let it stand horizontally to solidify, and evenly spread Malassezia on the surface of the solid culture medium. Place an Oxford cup sterilized by high pressure on the culture medium, and then add 100 μL of sample solution to the Oxford cup. Place two Oxford cups in each culture medium and perform two repeated parallel experiments. Then place it in an incubator at 37°C and 60% humidity for 48 h to observe the antibacterial effect.

[0044] Table 1

[0045] Figure 1 This is the XRD spectrum of the product in Example 1. Figure 2 The antibacterial effect of the product in Example 1 is: Figure 2 The diameters of the inhibition zones on the left and right sides are 19.8 mm and 16.97 mm respectively. Figure 3 The antibacterial effect of the titanium dioxide dispersion in Comparative Example 7 is shown in FIG. Figure 3 The diameters of the inhibition zones on the left and right sides are 10.53 mm and 6.57 mm respectively. Figure 4 The antibacterial effect of the supernatant of the product in Comparative Example 5 is shown in Table 1. Figure 4 The diameters of the inhibition zones on the left and right sides are 12.76 mm and 10.9 mm respectively. Figure 5The antibacterial effect of the supernatant of the product in Comparative Example 6 is shown in Table 1. Figure 5 The diameters of the inhibition zones on the left and right sides are 10.0 mm and 9.03 mm respectively. Figure 6 The following are product photos of Example 1 and Comparative Examples 1-6.

[0046] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a water-soluble nitrogen-doped titanium dioxide dispersion, characterized in that: The following steps are included: (1) adding a titanate ester to a short-chain alcohol and stirring at room temperature to obtain a premix; the titanate ester includes tetrabutyl titanate; (2) adding the premix into an acidic aqueous solution, heating to 60-90° C. and stirring to react, thereby obtaining a titanium dioxide dispersion; (3) Cooling the mixture to 40-45° C. and adding the nitrogen source triethylamine to the titanium dioxide dispersion obtained in step (2), stirring the mixture to react and obtaining a water-soluble nitrogen-doped titanium dioxide dispersion.

2. The method for preparing a water-soluble nitrogen-doped titanium dioxide dispersion according to claim 1, characterized in that: In step (2), the acidic aqueous solution is a hydrochloric acid aqueous solution, and the mass concentration of the brine aqueous solution is 0.6-3%.

3. The method for preparing a water-soluble nitrogen-doped titanium dioxide dispersion according to claim 1 or 2, characterized in that: In step (1), the short-chain alcohol includes one or more of methanol, ethanol, propanol or butanol.

4. The method for preparing a water-soluble nitrogen-doped titanium dioxide dispersion according to claim 1 or 2, characterized in that: In step (1), the mass ratio of titanate to short-chain alcohol is 0.3-0.7:

1.

5. The method for preparing a water-soluble nitrogen-doped titanium dioxide dispersion according to claim 1 or 2, characterized in that: In step (1), the stirring at room temperature to obtain the premix is ​​performed at 200-800 r / min for 0.1-2 hours.

6. The method for preparing a water-soluble nitrogen-doped titanium dioxide dispersion according to claim 1 or 2, characterized in that: In step (2), the mass ratio of the premix to the acidic aqueous solution is 0.1-0.2:

1.

7. The method for preparing a water-soluble nitrogen-doped titanium dioxide dispersion according to claim 1 or 2, characterized in that: In step (2), the stirring reaction is carried out at 200-800 r / min for 1-5 h.

8. The method for preparing a water-soluble nitrogen-doped titanium dioxide dispersion according to claim 1 or 2, characterized in that: In step (3), the mass ratio of triethylamine to titanium dioxide dispersion is 0.01-0.05:1; and the stirring reaction is carried out at 200-800 r / min for 2-24 hours. 9 . The water-soluble nitrogen-doped titanium dioxide dispersion prepared by the method for preparing the water-soluble nitrogen-doped titanium dioxide dispersion according to claim 1 .

10. Use of the water-soluble nitrogen-doped titanium dioxide dispersion prepared by the method for preparing the water-soluble nitrogen-doped titanium dioxide dispersion according to claim 1 in cosmetics, coatings or environmental management.

Images