Preparation method of eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material

Abstract

The present invention discloses a method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material, comprising the following steps: 1) pretreatment of eucalyptus; 2) hydrolysis; 3) semi-carbonization; 4) preparation of a precursor; 5) carbonization; and 6) post-treatment. The eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material is prepared using a phosphoric acid carbonization process. Phosphoric acid has five effects during the carbonization process: hydrolysis, dehydration, aromatization, cross-linking, and pore formation. Simultaneously, phosphoric acid penetrates and disperses into the cell walls of the plant fiber raw material, undergoing a process of rapid diffusion, hydrolysis, and re-diffusion. The hydroxyl groups of phosphoric acid can form phosphate ester bonds with the hydroxyl groups of biopolymers. Phosphoric acid can also significantly promote the aromatization reaction of newly formed carbon atoms, making the composite material more stable.

Description

Technical Field

[0001] The invention relates to the technical field of composite photocatalyst preparation, and in particular to a method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material. Background Art

[0002] Nano-titanium dioxide is a typical photocatalyst, but its traditional preparation and application processes have disadvantages such as low photocatalytic efficiency and difficulty in recycling, which limit its industrial application. In recent years, in order to improve the photocatalytic effect and recycling rate of nano-titanium dioxide, people have used various carriers to prepare fixed titanium dioxide photocatalysts. Among them, activated carbon has been widely used as a catalyst carrier. Activated carbon as a carrier has the following advantages: low price, acid and alkali resistance, stable properties, a developed pore structure, a large specific surface area and excellent adsorption properties, and it can be recycled. Recently, the method for preparing activated carbon-supported nano-titanium dioxide has gradually shifted from the sol-gel method to activated carbon-supported nano-titanium dioxide composite materials. Although this method has effectively solved the problem of easy shedding of nano-titanium dioxide on the carrier surface, there is still much room for improvement in recent methods: the process flow is not streamlined enough, the preparation time is too long, and the product degradation efficiency is still insufficient.

[0003] Chinese patent CN102145280A discloses a method for preparing a rice husk activated carbon / silica / titanium dioxide composite material. The method comprises the following steps: first, pickling rice husk powder, adding NaOH solution to the pickled rice husk powder and alkaline boiling to obtain a mixed slurry consisting of rice husk and sodium silicate; then, preparing a rice husk / silica / titanium dioxide precursor; and finally, carbonizing and activating the mixture to obtain the rice husk activated carbon / silica / titanium dioxide composite material.

[0004] However, the main shortcomings of this method are: complex preparation process, harsh reaction conditions, complex post-processing, and the composite material is not stable enough. There is no cross-linking reaction between the three materials and no stable chemical bond coordination.

[0005] Therefore, there is an urgent need to provide a method for preparing a composite material with a simple preparation process and a more stable composite material to solve the above-mentioned problems. Summary of the Invention

[0006] The present invention aims to solve the problems of complex preparation process and low photocatalytic efficiency of composite photocatalysts in the prior art. A method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material using a phosphoric acid carbonization process is proposed. This method has a high raw material utilization rate, and the generated activated carbon has more pores and well-developed micropores, which can form a closer contact and bond with titanium dioxide.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:

[0008] A method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material comprises the following steps:

[0009] 1) Eucalyptus wood pretreatment: crush the eucalyptus wood blocks and pass them through a 100-500 mesh sieve to obtain eucalyptus wood chips;

[0010] 2) Hydrolysis: adding anhydrous hydrochloric acid chlorosilane mixture and water to the eucalyptus sawdust described in step 1), and hydrolyzing the mixture at room temperature for 8 to 10 hours under constant stirring to obtain a mixed slurry of eucalyptus sawdust and silicate, and drying the mixed slurry to remove water and hydrogen chloride to obtain a mixture;

[0011] 3) Semi-carbonization: The mixture of step 2) is calcined at 400-550° C. for 2-4 hours under a nitrogen atmosphere, and then naturally cooled to room temperature to obtain slag ash;

[0012] 4) Preparation of a precursor: butyl titanate, a macromolecular surfactant, and a phosphoric acid solution are sequentially added to the slag ash in step 3) under stirring, and the mixture is allowed to stand and mature for 8 to 10 hours to obtain a precursor material;

[0013] 5) Carbonization: calcining the precursor material in step 4) at 400-550° C. for 2-4 hours under a nitrogen atmosphere, and then naturally cooling to room temperature;

[0014] 6) Post-processing: After natural cooling, the mixture is washed multiple times, dried, and crushed to obtain a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material.

[0015] Furthermore, the anhydrous hydrochloric acid chlorosilane mixture in step 2) is an anhydrous hydrochloric acid chlorosilane waste liquid mixture from the polysilicon industry chain; the waste material mainly comes from the hydrogen reduction and distillation purification steps in the polysilicon industry chain. Since chlorosilane will undergo hydrolysis and exotherm when it comes into contact with water, there is no water in the mixture.

[0016] Furthermore, in step 2), the mass ratio of the eucalyptus sawdust to the anhydrous hydrochloric acid chlorosilane mixture is 3 to 10:1. This is because the eucalyptus sawdust contains hydroxyl groups. Through the dehydration reaction of chlorosilane with hydroxyl groups, if the amount of the anhydrous hydrochloric acid chlorosilane mixture exceeds this range, the experimental safety will be reduced due to hydrolysis and dehydration reactions. If the amount is too low, the content of silicon dioxide hydrolyzed from the chlorosilane mixture is small, resulting in a relatively high content of titanium dioxide. The titanium dioxide structure agglomerates itself, and the titanium atoms cannot react with other reagents, which is specifically manifested as uneven mixing of the materials and low photocatalytic performance.

[0017] Furthermore, in step 2), the mass ratio of eucalyptus sawdust to water is 1.11 to 1.43:1. If the water dosage exceeds this range, the drying time before carbonization will be too long; if the water dosage is too low, the chlorosilane cannot be completely hydrolyzed and the semi-carbonization effect will be weakened.

[0018] Furthermore, in step 4), the mass ratio of slag ash to butyl titanate is 0.25 to 1.6:1. If the amount of butyl titanate exceeds this range, the hydrolyzed titanium dioxide structure will agglomerate, and the titanium atoms will not be able to react with other reagents, which will specifically manifest as uneven material mixing and low photocatalytic performance; if the amount of butyl titanate is too low, there will be too few photocatalytic material particles per unit mass in the material.

[0019] Furthermore, in step 4), the mass ratio of slag ash to macromolecular surfactant is 20-40:1. If the amount of surfactant exceeds this range, the viscosity of the material will be too high; if it is too low, the particle size of titanium dioxide cannot be effectively reduced.

[0020] Furthermore, in step 4), the mass percentage concentration of the phosphoric acid solution is 50%, and the mass ratio of slag ash to phosphoric acid solution is 0.2-0.6:1. The main function of phosphoric acid is to help carbonize and activate the raw materials. If the amount of phosphoric acid exceeds this range, it will lead to waste of raw materials; if it is too low, the carbonization and activation effects will be reduced.

[0021] Furthermore, in step 4), the macromolecular surfactant is one or more of dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide and octadecyltrimethylammonium chloride.

[0022] Beneficial effects of the present invention:

[0023] 1. In the present invention, eucalyptus is used as the raw material to prepare the photocatalyst. Eucalyptus is heated evenly and has a high utilization rate. The generated activated carbon has more pores and well-developed micropores, which can form a closer bond with titanium dioxide.

[0024] 2. In the present invention, the silicon dioxide raw material is a mixture of anhydrous hydrochloric acid and chlorosilane waste liquid from the polysilicon industry chain, in which impurities such as Al and B are fully utilized. The newly formed Ti-O-Al, Ti-OB and other chemical bonds further enhance the photocatalytic activity of titanium dioxide, shorten the photodegradation time, and increase the product degradation rate. The present invention fully utilizes the composition and properties of chlorosilane waste liquid from the polysilicon industry and chlorosilane as a renewable resource, solving the environmental problems caused by the accumulation of waste liquid from the polysilicon industry.

[0025] 3. The eucalyptus activated carbon-silica-titania composite material prepared in this invention utilizes a phosphoric acid carbonization process. During the carbonization process, phosphoric acid exerts five effects: hydrolysis, dehydration, aromatization, crosslinking, and pore formation. Simultaneously, phosphoric acid penetrates and disperses into the cell walls of the plant fiber raw material, undergoing a process of rapid diffusion, hydrolysis, and re-diffusion. Compared to the zinc chloride activation method, due to the different interactions of zinc chloride and phosphoric acid with the cell wall structure and polymer compounds of the plant fiber raw material, the hydroxyl groups of phosphoric acid can form phosphate ester bonds with the hydroxyl groups of biopolymers, enabling crosslinking reactions with biopolymers that zinc chloride lacks. Furthermore, phosphoric acid significantly promotes the aromatization of newly formed carbon atoms, resulting in a more stable composite material.

[0026] 4. The present invention performs semi-carbonization before preparing the precursor. The highly corrosive nature of chlorosilane dehydrates and carbonizes the eucalyptus sawdust, but the carbonization is incomplete. The lignin structure is well preserved, which increases the rigidity of the material for further carbonization. The reaction process includes both dehydration and hydrolysis, which can more rationally utilize energy. Phosphoric acid can be used for further carbonization and activation, increasing the material's specific surface area and pore structure, and increasing the number of contact sites with titanium dioxide.

[0027] 5. The present invention adds a macromolecular surfactant to modify the surface of the composite material, thereby reducing the particle size of titanium dioxide and enhancing the photocatalytic effect.

[0028] 6. The pH of the solution in the present invention does not need to be regulated. The acidity of the hydrolysis is provided by the anhydrous hydrochloric acid chlorosilane waste liquid mixture as the raw material, and can be subsequently neutralized by evaporating the volatilized hydrogen chloride and washing with water, without the need for alkaline washing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a scanning electron microscope image of the product of Example 1;

[0030] Figure 2 This is the product picture of Example 1;

[0031] Figure 3 This is the product picture of Example 2;

[0032] Figure 4 This is the product picture of Example 3;

[0033] Figure 5 This is the product picture of Example 4;

[0034] Figure 6 This is the product picture of Example 5;

[0035] Figure 7 This is the product picture of Example 6;

[0036] Figure 8 This is the product picture of Comparative Example 1. DETAILED DESCRIPTION

[0037] The present invention will be further described in detail below with reference to the examples, but the embodiments of the invention are not limited thereto.

[0038] Note: The anhydrous hydrochloric acid chlorosilane mixture involved in the following examples and comparative examples is anhydrous hydrochloric acid chlorosilane waste liquid mixture from the polysilicon industry chain; the waste material mainly comes from the hydrogen reduction and distillation purification steps in the polysilicon industry chain.

[0039] Example 1

[0040] A method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material comprises the following steps:

[0041] 1) Eucalyptus pretreatment: 30 g of eucalyptus wood was crushed and passed through a 200-mesh sieve to obtain eucalyptus sawdust;

[0042] 2) Hydrolysis: adding 10 g of anhydrous hydrochloric acid chlorosilane waste liquid and 27 g of water to the eucalyptus sawdust under constant stirring, and hydrolyzing at room temperature for 8 hours to obtain a mixed slurry consisting of eucalyptus sawdust and silicate, and drying the mixed slurry to remove water and hydrogen chloride to obtain a mixture;

[0043] 3) Semi-carbonization: The mixture of step 2) is calcined at 550° C. for 3 hours under a nitrogen atmosphere, and then naturally cooled to room temperature to obtain slag ash;

[0044] 4) Precursor Preparation: 4 g of the slag ash from step 3) was taken and 2.5 g of butyl titanate was added to the mixed slurry under continuous stirring; 0.1 g of the surfactant dodecyltrimethylammonium bromide was then added, followed by 6.7 g of a 50% by mass phosphoric acid solution, and the mixture was allowed to stand and mature for 8 hours to obtain a precursor material;

[0045] 5) Carbonization: calcining the precursor material in step 4) at 550° C. for 3 hours under a nitrogen atmosphere and naturally cooling to room temperature;

[0046] 6) Post-processing: After natural cooling, washing, drying, crushing, etc. Figure 2 The eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material shown in the electron microscope scanning image is as follows Figure 1 shown.

[0047] Example 2

[0048] A method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material comprises the following steps:

[0049] 1) Eucalyptus pretreatment: 30 g of eucalyptus wood was crushed and passed through a 100-mesh sieve to obtain eucalyptus sawdust;

[0050] 2) Hydrolysis: adding 3 g of anhydrous hydrochloric acid chlorosilane waste liquid and 21 g of water to the eucalyptus sawdust under constant stirring, and hydrolyzing at room temperature for 8 hours to obtain a mixed slurry consisting of eucalyptus sawdust and silicate, and drying the mixed slurry to remove water and hydrogen chloride to obtain a mixture;

[0051] 3) Semi-carbonization: The mixture of step 2) is calcined at 400° C. for 4 hours under a nitrogen atmosphere, and then naturally cooled to room temperature to obtain slag ash;

[0052] 4) Precursor Preparation: 4 g of the slag ash from step 3) was added to the mixed slurry with constant stirring, 5 g of butyl titanate was added; then, 0.2 g of a surfactant, dodecyltrimethylammonium chloride, and 6.7 g of a 50% by weight phosphoric acid solution were added, and the mixture was allowed to stand and mature for 9 hours to obtain a precursor material;

[0053] 5) Carbonization: calcining the precursor material in step 4) at 400° C. for 4 hours under a nitrogen atmosphere and naturally cooling to room temperature;

[0054] 6) Post-processing: After natural cooling, washing, drying, crushing, etc. Figure 3 Eucalyptus activated carbon-silica-titania composite material shown.

[0055] Example 3

[0056] A method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material comprises the following steps:

[0057] 1) Eucalyptus pretreatment: 30 g of eucalyptus wood was crushed and passed through a 500-mesh sieve to obtain eucalyptus sawdust;

[0058] 2) Hydrolysis: 6 g of anhydrous hydrochloric acid chlorosilane waste liquid and 24 g of water were added to the eucalyptus sawdust under constant stirring, and hydrolyzed at room temperature for 8 hours to obtain a mixed slurry consisting of eucalyptus sawdust and silicate. The mixed slurry was then dried to remove water and hydrogen chloride to obtain a mixture;

[0059] 3) Semi-carbonization: The mixture of step 2) is calcined at 500° C. for 2 hours under a nitrogen atmosphere, and then naturally cooled to room temperature to obtain slag ash;

[0060] 4) Precursor Preparation: 4 g of the slag ash from step 3) was added to the mixed slurry with constant stirring, and 7.5 g of butyl titanate was added; then, 0.1 g of hexadecyltrimethylammonium bromide and 0.05 g of dodecyltrimethylammonium chloride were added as surfactants, and 6.7 g of a 50% by mass phosphoric acid solution was added, and the mixture was allowed to stand and mature for 10 hours to obtain a precursor material;

[0061] 5) Carbonization: calcining the precursor material in step 4) at 500° C. for 2 hours under a nitrogen atmosphere and naturally cooling to room temperature;

[0062] 6) Post-processing: After natural cooling, washing, drying, crushing, etc. Figure 4 Eucalyptus activated carbon-silica-titania composite material shown.

[0063] Example 4

[0064] Compared with Example 1, this embodiment differs in that:

[0065] In step 4), 10 g of butyl titanate was added, and the remaining steps were the same as those in Example 1.

[0066] In this example, the same method as in Example 1 was used to prepare Figure 5 Eucalyptus activated carbon-silica-titania composite material shown.

[0067] Example 5

[0068] Compared with Example 1, this embodiment differs in that:

[0069] In step 4), 12.5 g of butyl titanate was added, and the remaining steps were the same as those in Example 1.

[0070] In this example, the same method as in Example 1 was used to prepare Figure 6 Eucalyptus activated carbon-silica-titania composite material shown.

[0071] Example 6

[0072] Compared with Example 1, this embodiment differs in that:

[0073] In step 4), 15 g of butyl titanate was added, and the remaining steps were the same as those in Example 1.

[0074] In this example, the same method as in Example 1 was used to prepare Figure 7 Eucalyptus activated carbon-silica-titania composite material shown.

[0075] Example 7

[0076] Compared with Example 1, this embodiment differs in that:

[0077] In step 4), 13.4 g of 50% by mass phosphoric acid solution was added, and the remaining steps were the same as in Example 1.

[0078] In this example, a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material was prepared in the same manner as in Example 1.

[0079] Example 8

[0080] Compared with Example 1, this embodiment differs in that:

[0081] In step 4), 20.1 g of 50% by mass phosphoric acid solution was added, and the remaining steps were the same as in Example 1.

[0082] In this example, a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material was prepared in the same manner as in Example 1.

[0083] Comparative Example 1

[0084] Compared with Example 1, this comparative example has the following differences:

[0085] In step 4), 25 g of butyl titanate was added, and the remaining steps were the same as those in Example 1.

[0086] This comparative example was prepared in the same manner as in Example 1. Figure 8 Eucalyptus activated carbon-silica-titania composite material shown.

[0087] Comparative Example 2

[0088] Compared with Example 1, this comparative example has the following differences:

[0089] In step 4), 30 g of butyl titanate was added, and the remaining steps were the same as those in Example 1.

[0090] In this comparative example, a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material was prepared in the same manner as in Example 1.

[0091] Comparative Example 3

[0092] Compared with Example 1, this comparative example has the following differences:

[0093] The addition of 6.7 g (5 ml) of 50% by mass phosphoric acid solution in step 4) was replaced by the addition of 5 ml of 1 mol / L ZnCl2 solution. The remaining steps were the same as those in Example 1.

[0094] In this comparative example, a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material was prepared in the same manner as in Example 1.

[0095] Experimental example

[0096] 1. Evaluation of photocatalytic activity

[0097] The photocatalytic activity of the eucalyptus activated carbon-silica-titania composite materials and pure titanium dioxide prepared in Examples 1-8 and Comparative Examples 1-3 was evaluated as follows: 0.2 g of pure titanium dioxide or the eucalyptus activated carbon-silica-titania composite material was added to a photochemical reactor, followed by 50 ml of a 25 mg / L alkaline violet solution. The reaction was stirred at 120 rpm and a UV lamp (15 W, 251 nm) was turned on. After reacting for 2 hours, the mixture was filtered and the supernatant was tested. The absorbance of the solution was measured at its maximum absorption wavelength using a spectrophotometer. The degradation rate was calculated according to the following formula:

[0098] η

[0099] η is the degradation rate of the dye (%); A0 and At are the absorbance of the dye solution before degradation and after t time, respectively;

[0100] The test results are shown in Table 1.

[0101] Table 1 Photocatalytic test results of eucalyptus activated carbon-silica-titanium dioxide composite materials

[0102]

[0103] As can be seen from Table 1, the photocatalytic activity of the eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material prepared by the present invention is significantly improved.

[0104] (1) Compared with pure titanium dioxide, the photocatalytic activity of the eucalyptus activated carbon-silicon dioxide-titanium dioxide composite materials prepared in Examples 1-8 is significantly improved compared with the photocatalytic activity of pure titanium dioxide. This is because the participation of activated carbon and silicon dioxide changes the agglomeration structure of titanium dioxide, and the three materials overlap, so that the reaction sites of titanium dioxide can be exposed to the greatest extent.

[0105] (2) The photocatalytic activity of Examples 1-8 is significantly higher than that of Comparative Examples 1-2. This is because butyl titanate will turn into titanium dioxide after hydrolysis. During the hydrolysis process, titanium atoms need to form new bonds with silicon, activated carbon, etc. If there is too much butyl titanate, there will be relatively less activated carbon and silicon dioxide, and the above material structure cannot be completed to form a material composite. The main component will be carbon dioxide agglomerates formed by the hydrolysis of butyl carbonate. As a result, excessive use of butyl titanate will make the main component of the product only titanium dioxide, rather than a composite material bonded with carbon, silicon, etc., and the photocatalytic activity is low.

[0106] 2. Photocatalytic Stability Evaluation

[0107] The photocatalytic stability of the eucalyptus activated carbon-silica-titania composite material was evaluated. The specific method was as follows: after the photocatalytic activity evaluation step in Example 1, Example 2, and Comparative Example 3, the solid phase was collected after filtration, washed, and dried to recover the photodegradable material, and the photocatalytic activity evaluation step was repeated four times, namely: 0.2 grams of the eucalyptus activated carbon-silica-titania composite material was added to the photochemical reactor, and then 50 ml of an alkaline violet solution with a concentration of 25 mg / L was added. The ultraviolet lamp (power 15 W, wavelength 251 nm) was turned on, and after reacting for 2 hours, the mixture was filtered and the supernatant was tested. The absorbance of the solution was measured at its maximum absorption wavelength by a spectrophotometer, and the dye degradation rate was calculated.

[0108] The test results are shown in Table 2.

[0109] Table 2 Stability test results of eucalyptus activated carbon-silicon dioxide-titanium dioxide composite materials

[0110]

[0111] As can be seen from Table 2, the photocatalytic stability of the eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material prepared by the present invention is significantly improved. As can be seen from Examples 1-2, the photocatalytic activity fluctuates little with the increase in the number of catalytic degradations; as can be seen from Comparative Example 3, when other variables remain unchanged, the phosphoric acid method is no longer used, that is, 50% phosphoric acid 5ml is replaced with 1mol / L ZnCl2 solution 5ml, and the photocatalytic activity decreases sharply with the increase in the number of catalytic degradations. Compared with the zinc chloride activation method, since zinc chloride and phosphoric acid have different effects on the cell wall structure and polymer compounds of plant fiber raw materials, the hydroxyl groups of phosphoric acid can form phosphate ester bonds with the hydroxyl groups of biopolymers, which has the characteristic of cross-linking reaction with biopolymers that zinc chloride does not have. At the same time, phosphoric acid can also significantly promote the aromatization reaction of new carbon atoms, making the composite material more stable.

[0112] Further, from Figure 1 It can be seen that the eucalyptus activated carbon carbonized using phosphoric acid has large pores and abundant contact sites with titanium dioxide and other materials. Phosphoric acid has oxidizing properties and can further oxidize the formed carbon, playing a further oxidizing role, corroding the carbon and creating pores, forming a microcrystalline structure with well-developed micropores. Phosphoric acid also acts as a skeleton during carbonization, providing a framework for the newly formed carbon, allowing carbon to be deposited on the framework. Under an electron microscope, the abundant pores of the carbon attached to the framework can be seen.

[0113] from Figure 2-8 It can be seen that: Figure 8 Different from Figure 2-7The raw material butyl titanate hydrolyzate is not mixed evenly with other raw materials. The reason is that the amount of butyl titanate is too much, the structure agglomerates after hydrolysis, and the titanium atoms in titanium dioxide cannot react with other reagents, so the material is not mixed evenly. Figure 8 The photocatalytic performance of the product is lower than Figure 2-7 .

[0114] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material, characterized in that: The steps include: 1) Eucalyptus wood pretreatment: crush the eucalyptus wood blocks and pass them through a 100-500 mesh sieve to obtain eucalyptus wood chips; 2) Hydrolysis: Adding anhydrous hydrochloric acid chlorosilane waste liquid mixture from the polysilicon industry chain and water to the eucalyptus sawdust described in step 1), hydrolyzing at room temperature for 8 to 10 hours under continuous stirring to obtain a mixed slurry consisting of eucalyptus sawdust and silicate, and drying the mixed slurry to remove water and hydrogen chloride to obtain a mixture; 3) Semi-carbonization: The mixture of step 2) is calcined at 400-550° C. for 2-4 hours under a nitrogen atmosphere, and then naturally cooled to room temperature to obtain slag ash; 4) Precursor Preparation: butyl titanate, a macromolecular surfactant, and a phosphoric acid solution are sequentially added to the slag ash described in step 3) under stirring, and the mixture is allowed to stand and mature for 8 to 10 hours to prepare a precursor material; the mass ratio of slag ash to butyl titanate is 0.25 to 1.6:1; 5) Carbonization: calcining the precursor material in step 4) at 400-550° C. for 2-4 hours under a nitrogen atmosphere, and then naturally cooling to room temperature; 6) Post-processing: After natural cooling, the mixture is washed multiple times, dried, and crushed to obtain a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material.

2. The method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material according to claim 1, characterized in that: In the step 2), the mass ratio of the eucalyptus sawdust to the anhydrous hydrochloric acid chlorosilane mixture is 3 to 10:

1.

3. The method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material according to claim 1, characterized in that: In the step 2), the mass ratio of eucalyptus sawdust to water is 1.11-1.43:

1.

4. The method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material according to claim 1, characterized in that: In the step 4), the macromolecular surfactant is one or more of dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide and octadecyltrimethylammonium chloride.

5. The method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material according to claim 4, characterized in that: In step 4), the mass ratio of slag ash to macromolecular surfactant is 20-40:

1.

6. The method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material according to claim 1, characterized in that: The mass percentage concentration of phosphoric acid in step 4) is 50%.

7. The method for preparing a eucalyptus activated carbon-silicon dioxide-titanium dioxide composite material according to claim 6, characterized in that: In step 4), the mass ratio of slag ash to phosphoric acid is 0.2-0.6:1.

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