A kind of fluff-shaped nano-tungstic acid and its preparation method and application

Abstract

The present invention belongs to the technical field of tungsten metallurgy, and particularly relates to a flocculent spherical nano tungsten acid, a preparation method thereof and an application. The preparation method includes: S1. Add hydrochloric acid into a container, continuously stir during the addition process and keep the temperature in the container stable; S2. Drop 2-5 mL of ammonium tungstate solution B into the container, continuously stir during the addition process and keep the temperature in the container stable; S3. Add 0.6-1.0 L of ammonium tungstate solution A into the container, continuously stir during the addition process and keep the temperature in the container stable; the amount of hydrochloric acid added in step S1 is 1.5-2.0 times the theoretical amount of hydrochloric acid required for preparing tungstic acid according to the tungstate ion concentration in ammonium tungstate solution A; S4. Repeat steps S1 and S3; S5. Filter the prepared tungstic acid, wash it with hydrochloric acid and then dry it to obtain flocculent spherical nano tungstic acid. The prepared tungstic acid has good grain uniformity and is in a flocculent spherical shape, has porous characteristics, and the specific surface area is ≥80 m 2 / g.

Description

Technical Field

[0001] The present invention belongs to the technical field of tungsten metallurgy, and particularly relates to a flocculent spherical nano-tungstic acid, a preparation method thereof and an application thereof. Background Art

[0002] As a nano-scale inorganic material, nano-tungstic acid (H2WO4) exhibits broad application potential in multiple fields due to its high specific surface area, excellent optoelectronic properties, catalytic activity, and chemical and thermal stability. In the field of catalysis, it is used for photocatalytic degradation of pollutants and water splitting for hydrogen production; in energy storage, as an electrode material for supercapacitors and lithium / sodium batteries, it can improve efficiency; its sensitive gas sensing ability and antibacterial properties also make it highly concerned in the fields of sensors, environmental protection and biomedicine.

[0003] However, the large-scale preparation of nano-tungstic acid still faces many challenges: Although traditional methods such as hydrothermal method and sol-gel method can control the morphology and purity, they have high costs, complex processes, poor particle uniformity, and serious agglomeration; although the chemical precipitation method is simple and inexpensive, it is difficult to avoid impurity residues. In addition, the environmental toxicity, long-term stability and uniformity control problems in large-scale production of nano-materials still need further research. With the technological progress and update iteration in the application fields of nano-materials in recent years, the performance requirements for nano-materials are getting higher and higher. Therefore, it is crucial to develop nano-tungstic acid with high purity, high specific surface area and good uniformity. Summary of the Invention

[0004] To solve the problems existing in the prior art, the main object of the present invention is to propose a flocculent spherical nano-tungstic acid, a preparation method thereof and an application thereof.

[0005] According to one aspect of the present invention, the present invention provides the following technical solution:

[0006] A preparation method of a flocculent spherical nano-tungstic acid, comprising the following steps:

[0007] S1. Add hydrochloric acid to a container, and continuously stir during the addition process to keep the temperature in the container stable;

[0008] S2. Drop 2-5 mL of ammonium tungstate solution B into the container, and continuously stir during the addition process to keep the temperature in the container stable;

[0009] S3. Add 0.6-1.0 L of ammonium tungstate solution A to the container, and continuously stir during the addition process to keep the temperature in the container stable; the amount of hydrochloric acid added in step S1 is 1.5-2.0 times the theoretical amount of hydrochloric acid required to prepare tungstic acid according to the tungstate ion concentration in ammonium tungstate solution A;

[0010] S4. Repeat steps S1 and S3;

[0011] S5. Filter the obtained tungstic acid, wash it with hydrochloric acid, and then dry it to obtain fluffy spherical nano-tungstic acid.

[0012] According to another aspect of the present invention, the present invention provides the following technical solution:

[0013] A kind of fluffy spherical nano-tungstic acid is prepared by using the preparation method of the above-mentioned fluffy spherical nano-tungstic acid. The fluffy spherical nano-tungstic acid has good grain uniformity and is in a fluffy spherical shape, has porous characteristics, and the specific surface area ≥ 80m 2 / g.

[0014] According to another aspect of the present invention, the present invention provides the following technical solution:

[0015] The application of the fluffy spherical nano-tungstic acid in photocatalytic degradation of organic pollutants.

[0016] The beneficial effects of the present invention are as follows:

[0017] The present invention provides a fluffy spherical nano-tungstic acid, its preparation method and application. By using the method of pre-preparing seeds and adding materials in segments, nano-tungstic acid with a high specific surface area and good uniformity is prepared. Alternately adding hydrochloric acid and ammonium tungstate solution A can keep the concentration of hydrochloric acid in the reaction system within a relatively stable range all the time, can control the reaction rate and the concentration of solutes in the solution, and make the particle size of the formed tungstic acid more uniform. The prepared tungstic acid grains have good uniformity and are in a fluffy spherical shape, have porous characteristics, and the specific surface area ≥ 80m 2 / g. Description of the drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0019] Figure 1 It is the electron microscope image of the fluffy spherical nano-tungstic acid prepared in Example 1 of the present invention;

[0020] Figure 2 It is the electron microscope image of the fluffy spherical nano-tungstic acid prepared in Example 2 of the present invention;

[0021] Figure 3 It is the electron microscope image of the fluffy spherical nano-tungstic acid prepared in Example 3 of the present invention;

[0022] Figure 4 It is the electron microscope image of the tungstic acid prepared in Comparative Example 1 of the present invention;

[0023] Figure 5Electron micrograph of tungstic acid prepared in Comparative Example 2 of the present invention;

[0024] Figure 6 Electron micrograph of tungstic acid prepared in Comparative Example 3 of the present invention;

[0025] Figure 7 Electron micrograph of tungstic acid prepared in Comparative Example 4 of the present invention.

[0026] The realization, functional features and advantages of the object of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0027] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] The present invention provides a method for preparing a flocculent nanoscale tungstic acid, its preparation method and application. By using the method of pre-preparing seeds and adding materials in segments at a certain temperature, a nanoscale tungstic acid with a high specific surface area and uniformity can be prepared, which can solve the problems of generally low specific surface area, poor particle uniformity and serious agglomeration of current nanoscale tungstic acid. Alternately adding hydrochloric acid and ammonium tungstate solution A can keep the concentration of hydrochloric acid in the reaction system within a relatively stable range, control the reaction rate and the concentration of solutes in the solution, and make the particle size of the formed tungstic acid more uniform. If hydrochloric acid is not added alternately in batches, the concentration of hydrochloric acid will become lower and lower, resulting in tungstic acid with greatly different sizes and morphologies.

[0029] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0030] A method for preparing a flocculent nanoscale tungstic acid, comprising the following steps:

[0031] S1. Add hydrochloric acid to a container, continuously stir during the addition process and keep the temperature in the container stable;

[0032] S2. Drop 2-5 mL of ammonium tungstate solution B into the container, continuously stir during the addition process and keep the temperature in the container stable;

[0033] S3. Add 0.6-1.0 L of ammonium tungstate solution A to the container, continuously stir during the addition process and keep the temperature in the container stable; the amount of hydrochloric acid added in step S1 is 1.5-2.0 times the theoretical amount of hydrochloric acid required to prepare tungstic acid according to the concentration of tungstate in ammonium tungstate solution A;

[0034] S4. Repeat steps S1 and S3;

[0035] S5. Filter the prepared tungstic acid, wash it with hydrochloric acid, and then dry it to obtain fluffy spherical nano-tungstic acid.

[0036] Preferably, in the steps S1 - S3, the temperature inside the container is 80 - 110 °C, and the stirring speed is 100 - 400 r / min. If the temperature is too high, it will lead to high energy consumption, a large amount of hydrochloric acid volatilization, large acid loss, and a low specific surface area of the prepared tungstic acid; if the temperature is too low, the nucleation rate is slow, the deposition and growth effect is obvious, the tungstic acid is severely agglomerated, and the uniformity is poor. Specifically, the temperature inside the container can be, for example, any one of 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C or the range between any two of them. If the stirring speed is too low, the tungstic acid is likely to deposit and grow, resulting in a low specific surface area; if the stirring speed is too high, the tungstic acid is easily broken, with poor crystal form and uniformity. Specifically, the stirring speed can be, for example, any one of 100 r / min, 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min or the range between any two of them.

[0037] Preferably, in the step S1, the concentration of hydrochloric acid is 16 - 22 wt%; there is no special requirement for the addition speed of hydrochloric acid, and it can be added as soon as possible; for example, each time hydrochloric acid is added, it can be added within 5 - 10 s. If the concentration of hydrochloric acid is too high, the volatilization amount is large at high temperature, resulting in large acid loss, and local over-acidity, large nucleation amount, and severe agglomeration and caking, which is not conducive to the preparation of uniform tungstic acid; if the concentration of hydrochloric acid is too low, the total volume of the solution is large, reducing the reaction efficiency, increasing the equipment energy consumption, and having a high production and preparation cost. Specifically, the concentration of hydrochloric acid can be, for example, any one of 16 wt%, 16.5 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, 19.5 wt%, 20 wt%, 20.5 wt%, 21 wt%, 21.5 wt%, 22 wt% or the range between any two of them.

[0038] Preferably, in the step S2, based on WO3, the concentration of ammonium tungstate solution B is 220 - 250 g / L; in the step S3, based on WO3, the concentration of ammonium tungstate solution A is 220 - 250 g / L. Specifically, the concentration of ammonium tungstate solution B and the concentration of ammonium tungstate solution A can be the same or different. The concentration of ammonium tungstate solution A can be, for example, any one of 220 g / L, 225 g / L, 230 g / L, 235 g / L, 240 g / L, 245 g / L, 250 g / L or the range between any two of them; the concentration of ammonium tungstate solution B can be, for example, any one of 220 g / L, 225 g / L, 230 g / L, 235 g / L, 240 g / L, 245 g / L, 250 g / L or the range between any two of them.

[0039] Preferably, in step S2, after dropping 2-5 mL of ammonium tungstate solution B into the container, stir for 8-12 min, and then proceed to step S3; the dropping rate of ammonium tungstate solution B is 20-30 mL / min. The purpose of dropping 2-5 mL of ammonium tungstate solution B in this step is to first form a small amount of tungstic acid as the seed for the subsequent growth of tungstic acid crystals. The dropping amount of ammonium tungstate solution B enables the amount of seeds to be controlled within a certain range. Too much or too little will lose the meaning of adding seeds, resulting in the inability to stably obtain spherical nano-tungstic acid. Specifically, the dropping amount of ammonium tungstate solution B can be any one of 2 mL, 3 mL, 4 mL, 5 mL or the range between any two of them. At the same time, controlling the dropping rate of ammonium tungstate solution B to be 20-30 mL / min and stirring for 8-12 min after dropping ammonium tungstate solution B is beneficial to the uniform formation of seeds. Specifically, the dropping rate of ammonium tungstate solution B can be, for example, any one of 20 mL / min, 21 mL / min, 22 mL / min, 23 mL / min, 24 mL / min, 25 mL / min, 26 mL / min, 27 mL / min, 28 mL / min, 29 mL / min, 30 mL / min or the range between any two of them; the stirring time after dropping ammonium tungstate solution B can be any one of 8 min, 9 min, 10 min, 11 min, 12 min or the range between any two of them.

[0040] Preferably, in step S3, the adding rate of ammonium tungstate solution A is 40-80 mL / min; after the addition of ammonium tungstate solution A is completed, stir for 10-30 min and then proceed to step S4. If the adding rate of ammonium tungstate solution A is too fast, there will be many nuclei of tungstic acid and it is easy to agglomerate and cake; if the adding rate of ammonium tungstate solution A is too slow, it is easy to deposit and grow, and the particle size of tungstic acid is coarse. Specifically, the adding rate of ammonium tungstate solution A can be, for example, any one of 40 mL / min, 45 mL / min, 50 mL / min, 55 mL / min, 60 mL / min, 65 mL / min, 70 mL / min, 75 mL / min, 80 mL / min or the range between any two of them; the stirring time after the addition of ammonium tungstate solution A is completed can be, for example, any one of 10 min, 15 min, 20 min, 25 min, 30 min or the range between any two of them. The volume of ammonium tungstate solution A can be, for example, any one of 0.6 L, 0.65 L, 0.7 L, 0.75 L, 0.8 L, 0.85 L, 0.9 L, 0.95 L, 1.0 L or the range between any two of them. The amount of hydrochloric acid used can be any one of 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times of the theoretical amount of dilute hydrochloric acid required to prepare tungstic acid according to the tungstate ion concentration in ammonium tungstate solution A or the range between any two of them.

[0041] Preferably, in step S4, after repeating 4 to 8 times, step S5 is carried out. Specifically, the number of repetitions can be 4, 5, 6, 7, or 8.

[0042] Preferably, in step S5, the concentration of hydrochloric acid is 3 wt%, washing is carried out 2 to 4 times, and the drying temperature is 100 to 120 °C. Using a higher drying temperature is beneficial to the volatilization of the residual hydrochloric acid in tungstic acid at this drying temperature. However, if the temperature is too high, the water evaporates too quickly and it is not easy to obtain loose tungstic acid. Specifically, the drying temperature can be, for example, any one of 100 °C, 105 °C, 110 °C, 115 °C, 120 °C or the range between any two of them.

[0043] According to another aspect of the present invention, the present invention provides the following technical solution:

[0044] A kind of fluffy nano-tungstic acid is prepared by using the above-mentioned preparation method of fluffy nano-tungstic acid. The fluffy nano-tungstic acid has good grain uniformity and is in a fluffy shape, has porous characteristics, and the specific surface area is ≥ 80 m 2 / g. Specifically, the specific surface area of the fluffy nano-tungstic acid can be, for example, any one of 80 m 2 / g, 85 m 2 / g, 90 m 2 / g, 95 m 2 / g, 100 m 2 / g or the range between any two of them.

[0045] According to another aspect of the present invention, the present invention provides the following technical solution:

[0046] The application of the fluffy nano-tungstic acid in photocatalytic degradation of organic pollutants.

[0047] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0048] Example 1

[0049] A preparation method of fluffy nano-tungstic acid includes the following steps:

[0050] S1. Add hydrochloric acid to the container, and continuously stir during the addition process to keep the temperature in the container stable;

[0051] S2. Drop 2 mL of ammonium tungstate solution B into the container, and continuously stir during the addition process to keep the temperature in the container stable;

[0052] S3. Add 0.6 L of ammonium tungstate solution A to the container, and continuously stir during the addition process to keep the temperature in the container stable; the amount of hydrochloric acid added in step S1 is 1.5 times the theoretical amount of hydrochloric acid required to prepare tungstic acid according to the tungstate ion concentration in ammonium tungstate solution A;

[0053] S4. Repeat steps S1 and S3;

[0054] S5. Filter the prepared tungstic acid, wash it with hydrochloric acid, and then dry it to obtain fluffy spherical nano-tungstic acid.

[0055] In steps S1 - S3, the temperature in the container is 80 °C and the stirring speed is 400 r / min; in step S1, the concentration of hydrochloric acid is 16 wt%; in step S2, based on WO3, the concentration of ammonium tungstate solution B is 250 g / L; in step S3, based on WO3, the concentration of ammonium tungstate solution A is 250 g / L; in step S2, after dropping 2 mL of ammonium tungstate solution B into the container, stir for 10 min, and then proceed to step S3; the dropping speed of ammonium tungstate solution B is 20 mL / min; in step S3, the adding speed of ammonium tungstate solution A is 40 mL / min; after the addition of ammonium tungstate solution A is completed, stir for 10 min and then proceed to step S4; in step S4, repeat 8 times and then proceed to step S5. In step S5, the concentration of hydrochloric acid is 3 wt%, wash 3 times, and the drying temperature is 110 °C.

[0056] The fluffy spherical nano-tungstic acid obtained in this example is as Figure 1 shown, and its specific surface area is 95 m 2 / g.

[0057] Example 2

[0058] A method for preparing fluffy spherical nano-tungstic acid, comprising the following steps:

[0059] S1. Add hydrochloric acid to the container, continuously stir during the addition process, and keep the temperature in the container stable;

[0060] S2. Drop 5 mL of ammonium tungstate solution B into the container, continuously stir during the addition process, and keep the temperature in the container stable;

[0061] S3. Add 1.0 L of ammonium tungstate solution A to the container, continuously stir during the addition process, and keep the temperature in the container stable; the amount of hydrochloric acid added in step S1 is 2.0 times the theoretical amount of hydrochloric acid required for preparing tungstic acid according to the tungstate ion concentration in ammonium tungstate solution A;

[0062] S4. Repeat steps S1 and S3;

[0063] S5. Filter the prepared tungstic acid, wash it with hydrochloric acid, and then dry it to obtain fluffy spherical nano-tungstic acid.

[0064] In the steps S1 - S3, the temperature inside the container is 110 °C and the stirring speed is 100 r / min; in step S1, the concentration of hydrochloric acid is 22 wt%; in step S2, based on WO3, the concentration of ammonium tungstate solution B is 220 g / L; in step S3, based on WO3, the concentration of ammonium tungstate solution A is 220 g / L; in step S2, after dropping 5 mL of ammonium tungstate solution B into the container, stir for 10 min and then proceed to step S3; the dropping speed of ammonium tungstate solution B is 30 mL / min; in step S3, the adding speed of ammonium tungstate solution A is 80 mL / min; after the addition of ammonium tungstate solution A is completed, stir for 30 min and then proceed to step S4; in step S4, repeat 4 times and then proceed to step S5. In step S5, the concentration of hydrochloric acid is 3 wt%, wash 3 times, and the drying temperature is 100 °C.

[0065] The wool ball-like nano-tungstic acid obtained in this example is as Figure 2 shown, and its specific surface area is 82.1 m 2 / g.

[0066] Example 3

[0067] A preparation method of wool ball-like nano-tungstic acid includes the following steps:

[0068] S1. Add hydrochloric acid to the container, continuously stir during the adding process and keep the temperature inside the container stable;

[0069] S2. Drop 4 mL of ammonium tungstate solution B into the container, continuously stir during the adding process and keep the temperature inside the container stable;

[0070] S3. Add 0.8 L of ammonium tungstate solution A to the container, continuously stir during the adding process and keep the temperature inside the container stable; the amount of hydrochloric acid added in step S1 is 1.8 times the theoretical amount of hydrochloric acid required to prepare tungstic acid according to the concentration of tungstate in ammonium tungstate solution A;

[0071] S4. Repeat steps S1 and S3;

[0072] S5. Filter the prepared tungstic acid, wash it with hydrochloric acid, and then dry it to obtain wool ball-like nano-tungstic acid.

[0073] In the steps S1 - S3, the temperature inside the container is 95 °C and the stirring speed is 300 r / min; in the step S1, the concentration of hydrochloric acid is 19 wt%; in the step S2, the concentration of ammonium tungstate solution B is 230 g / L in terms of WO₃; in the step S3, the concentration of ammonium tungstate solution A is 230 g / L in terms of WO₃; in the step S2, after dropping 4 mL of ammonium tungstate solution B into the container, stir for 10 min and then proceed to step S3; the dropping speed of ammonium tungstate solution B is 25 mL / min; in the step S3, the adding speed of ammonium tungstate solution A is 60 mL / min; after the addition of ammonium tungstate solution A is completed, stir for 20 min and then proceed to step S4; in the step S4, repeat 6 times and then proceed to step S5. In the step S5, the concentration of hydrochloric acid is 3 wt%, wash 3 times, and the drying temperature is 120 °C.

[0074] The woolly - ball - shaped nano - tungstic acid obtained in this example is as Figure 3 shown, and its specific surface area is 89.4 m 2 / g.

[0075] Comparative Example 1

[0076] The difference from Example 3 is that hydrochloric acid and ammonium tungstate solution A are not added in a segmented and alternating manner: that is, first add all the hydrochloric acid, then drop ammonium tungstate solution B and then add all the ammonium tungstate solution A.

[0077] The tungstic acid obtained in this comparative example is as Figure 4 shown, which is flaky, and its specific surface area is 40 m 2 / g.

[0078] Comparative Example 2

[0079] The difference from Example 3 is that step S2 is not carried out.

[0080] The tungstic acid obtained in this comparative example is as Figure 5 shown, which is in irregular flaky shape, and its specific surface area is 64.7 m 2 / g.

[0081] Comparative Example 3

[0082] The difference from Example 3 is that the temperature inside the container is at room temperature.

[0083] The tungstic acid obtained in this comparative example is as Figure 6 shown, which is in irregular flaky shape, has poor uniformity, and its specific surface area is 25.73 m 2 / g.

[0084] Comparative Example 4

[0085] The difference from Example 3 is that a sodium tungstate solution with the same concentration in terms of WO₃ is used instead of ammonium tungstate solution A.

[0086] The tungstic acid obtained in this comparative example is as follows Figure 7 shown, which is in regular flake shape and has a specific surface area of 34.24 m 2 / g.

[0087] The tungstic acid prepared in Example 3 and Comparative Example 4 was used to degrade methylene blue solution with a concentration of 10 -5 mol / L, and the results are as follows:

[0088] After the floccular nano-tungstic acid prepared in Example 3 was used to degrade the methylene blue solution and irradiated under a 500 W xenon lamp for 120 min, the degradation rate was 95.5%.

[0089] However, after the conventional flake tungstic acid prepared in Comparative Example 4 was used to degrade the methylene blue solution and irradiated under a 500 W xenon lamp for 120 min, the degradation rate was only 51.6%.

[0090] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made by using the content of the specification of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A preparation method of pompon-like nano-tungstic acid, characterized in that, It includes the following steps: S1. Add hydrochloric acid into the container, continuously stir during the adding process and keep the temperature in the container stable; S2. Drop 2 - 5 mL of ammonium tungstate solution B into the container, continuously stir during the adding process and keep the temperature in the container stable; the concentration of ammonium tungstate solution B is 220 - 250 g / L in terms of WO3; S3. Add 0.6 - 1.0 L of ammonium tungstate solution A into the container, continuously stir during the adding process and keep the temperature in the container stable; the amount of hydrochloric acid added in step S1 is 1.5 - 2.0 times the theoretical amount of hydrochloric acid required for preparing tungstic acid according to the tungstate ion concentration in ammonium tungstate solution A; the concentration of ammonium tungstate solution A is 220 - 250 g / L in terms of WO3; S4. Repeat steps S1 and S3; S5. Filter the prepared tungstic acid, wash it with hydrochloric acid and then dry it to obtain fluffy spherical nano - tungstic acid; In steps S1 - S3, the temperature in the container is 80 - 110 °C.

2. The preparation method of the fluffy spherical nano tungstic acid according to claim 1, characterized in that, In steps S1 - S3, the stirring speed is 100 - 400 r / min.

3. The preparation method of the fluffy spherical nano-tungstic acid according to claim 1, wherein, In step S1, the concentration of hydrochloric acid is 16 - 22 wt%.

4. The preparation method of the flocculent nano tungstic acid according to claim 1, characterized in that, In step S2, after dropping 2 - 5 mL of ammonium tungstate solution B into the container, stir for 8 - 12 min, and then proceed to step S3; the dropping speed of ammonium tungstate solution B is 20 - 30 mL / min.

5. The preparation method of the pompon-like nano tungstic acid according to claim 1, characterized in that, In step S3, the adding speed of ammonium tungstate solution A is 40 - 80 mL / min; after the addition of ammonium tungstate solution A is completed, stir for 10 - 30 min and then proceed to step S4.

6. The preparation method of the flocculus-like nano tungstic acid according to claim 1, characterized in that, In step S4, repeat 4 - 8 times and then proceed to step S5.

7. The preparation method of the fluffy spherical nano-tungstic acid according to claim 1, characterized in that, In step S5, the concentration of hydrochloric acid is 3 wt%, wash 2 - 4 times, and the drying temperature is 100 - 120 °C.

8. A pompom-shaped nano-tungstic acid, characterized in that: Prepared by the preparation method of the fluffy spherical nano-tungstic acid according to any one of claims 1-7, the fluffy spherical nano-tungstic acid has good grain uniformity, is in a fluffy spherical shape, has porous characteristics, and a specific surface area ≥ 80m 2 / g.

9. Application of the fluffy spherical nano - tungstic acid as described in claim 8 in photocatalytic degradation of organic pollutants.

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