Titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel material and its preparation method

Abstract

This invention discloses a method for preparing a titanium dioxide / silica / bismuth sulfide composite aerogel material, specifically: Step 1, preparing bismuth sulfide; Step 2, at room temperature, mixing and stirring tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid to obtain solution A; dispersing bismuth sulfide and tetrabutyl titanate in anhydrous ethanol to obtain solution B; stirring and mixing anhydrous ethanol, deionized water, and acetic acid to obtain solution C; Step 3, under continuous stirring, sequentially adding solutions C, A, and DMF to solution B to form a sol; after the sol transforms into a wet gel, transferring it to a reaction vessel, adding n-hexane to immerse the wet gel, carrying out a solvothermal reaction, and drying at room temperature to obtain the final product. The material prepared by this method has a controllable pore structure and a large specific surface area, exhibits strong adsorption and visible light degradation capabilities for organic dyes, and demonstrates good stability in use.

Description

Technical Field

[0001] This invention belongs to the field of composite materials, specifically relating to titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel materials, and also to a method for preparing titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel materials. Background Technology

[0002] Against the backdrop of environmental pollution control and sustainable development, photocatalysis has become an effective method for degrading organic pollutants. In recent years, composite aerogels have shown potential applications in various fields due to their excellent physical properties and diverse functions, such as drug delivery, gas storage, heavy metal adsorption, thermal insulation, sensing, and photocatalysis. Among them, TiO2 / SiO2 aerogels, which generally use SiO2 as a support to load TiO2 photocatalysts, possess high specific surface area and porous network structure, and their applications in photocatalytic degradation and polluted water treatment are increasing. However, most of the resulting materials are in powder form, and the absorption of visible light by pure TiO2 is very limited, restricting their widespread application. Summary of the Invention

[0003] The first objective of this invention is to provide a titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel material, which has a composite porous structure and a large specific surface area, can be suspended in aqueous solution, has strong adsorption and visible light degradation capabilities for organic dyes, and has good stability in use.

[0004] Another objective of this invention is to provide a method for preparing titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel materials, which is simple to implement, has a short preparation cycle, and is low in cost.

[0005] The technical solution adopted in this invention is a method for preparing titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel materials, combining the sol-gel method and the solvothermal method, including the following steps:

[0006] Step 1: Add bismuth nitrate, thiourea, and polyvinylpyrrolidone to ethylene glycol, sonicate, transfer to a reaction vessel for reaction, then wash with anhydrous ethanol and deionized water respectively, and dry to obtain black Bi2S3.

[0007] Step 2: At room temperature, mix and stir tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid to obtain solution A; disperse Bi2S3 and tetrabutyl titanate in anhydrous ethanol to obtain solution B; stir and mix anhydrous ethanol, deionized water, and acetic acid to obtain solution C.

[0008] Step 3: Under continuous stirring, solution C, solution A, and DMF are slowly added dropwise to solution B to form a sol. After the sol is converted into a wet gel, it is aged at 55℃-65℃ for 6-8 hours and then transferred to a reaction vessel. Hexane is added to immerse the wet gel and a solvothermal reaction is carried out. The gel is then dried at room temperature to obtain a gray TiO2 / SiO2 / Bi2S3 monolithic aerogel.

[0009] The invention is further characterized in that,

[0010] In step 1, the mass ratio of bismuth nitrate, thiourea, polyvinylpyrrolidone, and ethylene glycol is (5.5-6.5):(2.5-3.5):(0.9-1.1):(380-420). The solvothermal conditions for the reaction in the reactor are: temperature 150℃-170℃, time 11h-13h. The reactor is cleaned 2-4 times with anhydrous ethanol and deionized water, respectively.

[0011] In step 2, the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid in solution A is (2.8-3.2):(1.7-2.2):(5.8-6.2):(7.7-8.2); the volume ratio of tetrabutyl titanate to anhydrous ethanol in solution B is (0.4-0.6):1, and the Bi / Ti molar ratio is (0.01-0.02):1; the volume ratio of anhydrous ethanol, deionized water, and acetic acid in solution C is (34-37):(5-7):(9-11); and the mixing and stirring time for tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid is 20-30 min.

[0012] In step 3, solution C, solution A, and DMF are added to solution B in the following order: solution C: solution B: solution A: DMF. The volume ratio of solution C: solution B: solution A: DMF is (26-30): (29-32): (16-18): 1. The solvothermal reaction temperature is 115℃-125℃, and the reaction time is 19h-21h.

[0013] Another technical solution adopted in this invention is a titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel material, which is prepared by the above method.

[0014] The beneficial effects of this invention are:

[0015] (1) Aerogels have attracted widespread attention from researchers due to their high porosity, large specific surface area, and good stability. They have promising development prospects in fields such as thermal insulation, photocatalysis, energy storage, and sensing. The titanium dioxide / silica / bismuth sulfide composite aerogel material prepared by the method of this invention has a composite pore structure with a relatively concentrated pore size distribution and a large surface area. This material exhibits significantly enhanced absorption in the visible light region and strong adsorption and visible light degradation capabilities for organic dyes. The prepared monolithic material was directly placed in a Rhodamine B solution for visible light catalytic degradation experiments. The material was completely immersed and suspended in the solution. After adsorption in the dark for 10 minutes, it was irradiated with visible light. After irradiation for 20 minutes, the solution color disappeared, and the monolithic material remained suspended in the solution in its original state. The monolithic nature and suitable pore structure of this material allow it to remain suspended in the solution during use, enabling it to fully contact pollutants in the aqueous solution and greatly facilitating the separation and rapid recovery of the material in practical applications. The preparation method of this material is simple, easy to operate, and has a low cycle and low cost.

[0016] (2) The method of the present invention combines the sol-gel method with the solvothermal method to effectively composite TiO2, SiO2 and Bi2S3 to obtain an integral TiO2 / SiO2 / Bi2S3 aerogel material that can be suspended in water. No stirring is required during use, which maximizes its utilization rate of visible light and photocatalytic efficiency, and it is very easy to recycle after use. Attached Figure Description

[0017] Figure 1 These are scanning electron microscope images of the materials prepared under the conditions of Example 1;

[0018] Figure 2 These are X-ray diffraction patterns of the materials obtained under the conditions of Example 1 and Comparative Example 1;

[0019] Figure 3 The N2 adsorption-desorption isotherms of the materials obtained under the conditions of Example 1 and Comparative Example 1 are shown.

[0020] Figure 4 The pore size distribution diagrams are shown for the materials prepared under the conditions of Example 1 and Comparative Example 1.

[0021] Figure 5 The UV-Vis diffuse reflectance spectra of the materials prepared under the conditions of Example 1 and Comparative Example 1 are shown.

[0022] Figure 6 This is a photograph of the visible light degradation of Rhodamine B solution by the monolithic aerogel material obtained under the conditions of Example 1. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0024] This invention provides a method for preparing titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel materials, combining the sol-gel method with a solvothermal method, including the following steps:

[0025] Step 1: Bismuth nitrate, thiourea, and polyvinylpyrrolidone are added to ethylene glycol, sonicated, and then transferred to a reaction vessel for reaction. The mixture is then washed with anhydrous ethanol and deionized water, and dried to obtain black Bi2S3. In Step 1, the mass ratio of bismuth nitrate, thiourea, polyvinylpyrrolidone, and ethylene glycol is (5.5-6.5):(2.5-3.5):(0.9-1.1):(380-420). The solvothermal conditions for the reaction in the reaction vessel are: temperature 150℃-170℃, time 11h-13h. The mixture is washed 2-4 times with anhydrous ethanol and deionized water, respectively.

[0026] Step 2: At room temperature, mix and stir tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid to obtain solution A; disperse Bi2S3 and tetrabutyl titanate in anhydrous ethanol to obtain solution B; stir and mix anhydrous ethanol, deionized water, and acetic acid to obtain solution C.

[0027] In step 2, the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid in solution A is (2.8-3.2):(1.7-2.2):(5.8-6.2):(7.7-8.2); the volume ratio of tetrabutyl titanate to anhydrous ethanol in solution B is (0.4-0.6):1, and the Bi / Ti molar ratio is (0.01-0.02):1; the volume ratio of anhydrous ethanol, deionized water, and acetic acid in solution C is (34-37):(5-7):(9-11); and the mixing and stirring time for tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid is 20-30 min.

[0028] Step 3: Under continuous stirring, solutions C, A, and DMF are slowly added dropwise to solution B to form a sol. After the sol transforms into a wet gel, it is aged at 55℃-65℃ for 6-8 hours, then transferred to a reaction vessel. Hexane is added to immerse the wet gel, and a solvothermal reaction is carried out. After drying at room temperature, a gray TiO2 / SiO2 / Bi2S3 monolithic aerogel is obtained.

[0029] In step 3, solution C, solution A, and DMF are added to solution B in the following order: solution C: solution B: solution A: DMF. The volume ratio of solution C: solution B: solution A: DMF is (26-30): (29-32): (16-18): 1. The solvothermal reaction temperature is 115℃-125℃, and the reaction time is 19h-21h.

[0030] This invention also provides a titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel material, prepared using the above method. The Bi / Ti molar ratio is 0.01-0.02:1, TiO2 is the anatase phase, Bi2S3 is orthorhombic, and Bi2S3 is uniformly distributed in the TiO2 / SiO2 aerogel framework structure. The overall material has an average pore size of 9nm-11nm and can be immersed and suspended in aqueous solution.

[0031] Example 1

[0032] The preparation method of TiO2 / SiO2 / Bi2S3 aerogel material, which combines the sol-gel method with the solvothermal method, includes the following steps:

[0033] Step 1: Add bismuth nitrate, thiourea, and polyvinylpyrrolidone to ethylene glycol, sonicate, transfer to a reaction vessel and react for a certain period of time, then wash three times each with anhydrous ethanol and deionized water, and dry to obtain black Bi2S3.

[0034] In step 1, the mass ratio of bismuth nitrate, thiourea, polyvinylpyrrolidone, and ethylene glycol is 6:3:1:400, and the solvothermal conditions are 160℃ for 12 hours.

[0035] Step 2: At room temperature, mix tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid, and stir for 30 minutes to obtain solution A. Disperse Bi₂S₃ and tetrabutyl titanate in anhydrous ethanol to obtain solution B. Mix anhydrous ethanol, deionized water, and acetic acid to obtain solution C.

[0036] In step 2, the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid in solution A is 3:2:6:8; the volume ratio of tetrabutyl titanate to anhydrous ethanol in solution B is 0.5:1, and the Bi / Ti molar ratio is 0.015:1; the volume ratio of anhydrous ethanol, deionized water, and acetic acid in solution C is 35:6:10.

[0037] Step 3: Under continuous stirring, solutions C, A, and DMF (N,N-dimethylformamide) are slowly added dropwise to solution B to form a sol. After the sol transforms into a wet gel, it is aged at 60°C for 7 hours and then transferred to a reactor for a solvothermal reaction. After drying at room temperature, a gray TiO2 / SiO2 / Bi2S3 monolithic aerogel is obtained.

[0038] In step 3, solution C, solution A, and DMF are added to solution B in the following order: volume ratio of solution C: solution B: solution A: DMF is 28:30:17:1. The solvothermal reaction temperature is 120℃ and the reaction time is 21h.

[0039] Comparative Example 1

[0040] The difference between Comparative Example 1 and Example 1 is that, except for step 2 where Bi2S3 was not added, the other reaction steps are the same as in Example 1.

[0041] Depend on Figure 1 It can be seen that Example 1 has a composite porous structure. The porous structure can effectively prevent light from being reflected to the outside world on the material surface, which can improve the efficiency of the material in fully utilizing photons for photocatalysis. It can also effectively increase the specific surface area of ​​the material, provide more active sites, and enhance the photocatalytic activity of the material.

[0042] Depend on Figure 2 It can be seen that there are 10 diffraction peaks at 2θ = 25.29 (101), 37.81 (004), 48.04 (200), 53.92 (105), 55.11 (211), 62.68 (204), 68.82 (116), 70.01 (220), 75.11 (215), and 82.65 (224), which are consistent with the anatase phase TiO2 (JCPDS No. 73-1764). In Example 1, there are three relatively obvious diffraction peaks at 2θ = 28.61 (211), 31.46 (040), and 32.88 (301), which are consistent with the orthorhombic Bi2S3 (JCPDS No. 17-0320), indicating that the composite Bi2S3 TiO2 / SiO2 aerogel was successfully prepared. The prepared material showed no significant effect on the crystal form and crystallinity of TiO2 after the introduction of Bi2S3.

[0043] Depend on Figures 3-4 It can be seen that the adsorption-desorption isotherms of Comparative Example 1 and Example 1 are both IV.

[0044] The material exhibits an H2-type hysteresis loop, indicating that it is a mesoporous material with a composite pore structure and a relatively concentrated pore size distribution. The specific surface area of ​​the embodiment is 221.7 m². 2 ·g -1 The average pore size is 10.9 nm.

[0045] Depend on Figure 5 It can be seen that Example 1 has stronger absorption in the visible light region, which is significantly higher than that of Comparative Example 1. Therefore, doping the sample with a certain amount of Bi2S3 can enhance the absorption of visible light by the material, thereby improving its utilization rate of visible light.

[0046] from Figure 6 As can be seen in Example 1, it has a gray, monolithic block structure. It was directly placed into 40 mL of a solution with a concentration of 10 mg·L⁻¹. -1Visible light photocatalytic degradation experiments were conducted in RhB solution. After the material was placed in the solution, it was completely immersed and suspended in the solution. After adsorption in the dark for 10 minutes, it was irradiated with visible light. After 20 minutes of irradiation, the solution color disappeared, but the material remained suspended in the solution in its original state, indicating that the prepared aerogel has excellent visible light photocatalytic activity.

[0047] Example 2

[0048] A method for preparing titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel materials, combining the sol-gel method and the solvothermal method, includes the following steps:

[0049] Step 1: Bismuth nitrate, thiourea, and polyvinylpyrrolidone were added to ethylene glycol, sonicated, and then transferred to a reaction vessel for reaction. The mixture was then washed with anhydrous ethanol and deionized water, respectively, and dried to obtain black Bi2S3. In Step 1, the mass ratio of bismuth nitrate, thiourea, polyvinylpyrrolidone, and ethylene glycol was 5.5:2.5:0.9:380. The solvothermal conditions for the reaction in the reaction vessel were: temperature 150℃ and time 11h. The mixture was washed twice with anhydrous ethanol and deionized water, respectively.

[0050] Step 2: At room temperature, mix and stir tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid to obtain solution A; disperse Bi2S3 and tetrabutyl titanate in anhydrous ethanol to obtain solution B; stir and mix anhydrous ethanol, deionized water, and acetic acid to obtain solution C.

[0051] In step 2, the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid in solution A is 2.8:1.7:5.8:7.7; the volume ratio of tetrabutyl titanate to anhydrous ethanol in solution B is 0.4:1, and the Bi / Ti molar ratio is 0.01:1; the volume ratio of anhydrous ethanol, deionized water, and acetic acid in solution C is 34:5:9; and the mixing and stirring time for tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid is 20 min.

[0052] Step 3: Under continuous stirring, solution C, solution A, and DMF (N,N-dimethylformamide) are slowly added dropwise to solution B to form a sol. After the sol transforms into a wet gel, it is aged at 55°C for 6 hours and then transferred to a reaction vessel. Hexane is added to immerse the wet gel, and a solvothermal reaction is carried out. After drying at room temperature, a gray TiO2 / SiO2 / Bi2S3 monolithic aerogel is obtained.

[0053] In step 3, solution C, solution A, and DMF are added to solution B in the following order: volume ratio of solution C: solution B: solution A: DMF is 26:29:16:1. The solvothermal reaction temperature is 115℃ and the reaction time is 19h.

[0054] Example 3

[0055] A method for preparing titanium dioxide / silicon dioxide / bismuth sulfide composite aerogel materials, combining the sol-gel method and the solvothermal method, includes the following steps:

[0056] Step 1: Bismuth nitrate, thiourea, and polyvinylpyrrolidone were added to ethylene glycol, sonicated, and then transferred to a reaction vessel for reaction. The mixture was then washed with anhydrous ethanol and deionized water, and dried to obtain black Bi2S3. In Step 1, the mass ratio of bismuth nitrate, thiourea, polyvinylpyrrolidone, and ethylene glycol was 6.5:3.5:1.1:420. The solvothermal conditions for the reaction in the reaction vessel were: temperature 170℃ and time 13h. The mixture was washed four times with anhydrous ethanol and deionized water, respectively.

[0057] Step 2: At room temperature, mix and stir tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid to obtain solution A; disperse Bi2S3 and tetrabutyl titanate in anhydrous ethanol to obtain solution B; stir and mix anhydrous ethanol, deionized water, and acetic acid to obtain solution C.

[0058] In step 2, the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid in solution A is 3.2:2.2:6.2:8.2; the volume ratio of tetrabutyl titanate to anhydrous ethanol in solution B is 0.6:1, and the Bi / Ti molar ratio is 0.02:1; the volume ratio of anhydrous ethanol, deionized water, and acetic acid in solution C is 37:7:11; and the mixing and stirring time for tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid is 25 min.

[0059] Step 3: Under continuous stirring, solutions C, A, and DMF (N,N-dimethylformamide) are slowly added dropwise to solution B to form a sol. After the sol transforms into a wet gel, it is aged at 65°C for 8 hours and then transferred to a reaction vessel. Hexane is added to immerse the wet gel, and a solvothermal reaction is carried out. After drying at room temperature, a gray TiO2 / SiO2 / Bi2S3 monolithic aerogel is obtained.

[0060] In step 3, solution C, solution A, and DMF are added to solution B in the following order: volume ratio of solution C: solution B: solution A: DMF is 30:32:18:1. The solvothermal reaction temperature is 125℃ and the reaction time is 20h.

Claims

1. A method for preparing a titanium dioxide / silica / bismuth sulfide composite aerogel material, characterized by, The combination of the sol-gel method and the solvothermal method includes the following steps: Step 1: Add bismuth nitrate, thiourea, and polyvinylpyrrolidone to ethylene glycol, sonicate, transfer to a reaction vessel for reaction, then wash with anhydrous ethanol and deionized water respectively, and dry to obtain black Bi2S3. In step 1, the mass ratio of bismuth nitrate, thiourea, polyvinylpyrrolidone, and ethylene glycol is 5.5-6.5: 2.5-3.5: 0.9-1.1: 380-420. The solvothermal conditions for the reaction in the reactor are: temperature 150℃-170℃, time 11h-13h; the reactor is cleaned 2-4 times with anhydrous ethanol and deionized water respectively. Step 2: At room temperature, mix and stir tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid to obtain solution A; disperse Bi2S3 and tetrabutyl titanate in anhydrous ethanol to obtain solution B; stir and mix anhydrous ethanol, deionized water, and acetic acid to obtain solution C. In step 2, the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid in solution A is 2.8-3.2:1.7-2.2:5.8-6.2:7.7-8.2; the volume ratio of tetrabutyl titanate to anhydrous ethanol in solution B is 0.4-0.6:1, and the Bi / Ti molar ratio is 0.01-0.02:1; the volume ratio of anhydrous ethanol, deionized water, and acetic acid in solution C is 34-37:5-7:9-11; the mixing and stirring time for tetraethyl orthosilicate, anhydrous ethanol, deionized water, and glacial acetic acid is 20-30 minutes. Step 3: Under continuous stirring, solution C, solution A, and DMF are slowly added dropwise to solution B to form a sol. After the sol is converted into a wet gel, it is aged at 55℃-65℃ for 6-8 hours and then transferred to a reaction vessel. Hexane is added to immerse the wet gel and carry out a solvothermal reaction. The gel is then dried at room temperature to obtain a gray TiO2 / SiO2 / Bi2S3 monolithic aerogel. In step 3, solution C, solution A, and DMF are added to solution B in the following order: volume ratio of solution C: solution B: solution A: DMF is 26-30: 29-32: 16-18:

1. The solvothermal reaction temperature is 115℃-125℃, and the reaction time is 19h-21h.

2. Titanium dioxide / silica / bismuth sulfide composite aerogel material, characterized in that, It was prepared using the method described in claim 1.

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