WO2024007199A1

WO2024007199A1 - Barium titanate nanoparticle-compounded covalent organic framework heterojunction, and preparation method therefor

Info

Publication number: WO2024007199A1
Application number: PCT/CN2022/104161
Authority: WO
Inventors: 路建美; 李娜君
Original assignee: 苏州大学
Priority date: 2022-07-06
Filing date: 2022-07-06
Publication date: 2024-01-11

Abstract

Disclosed in the present invention are a preparation method for a barium titanate nanoparticle-compounded covalent organic framework (COF) heterojunction and a use of the barium titanate nanoparticle-compounded COF heterojunction. Barium titanate nanoparticles are mixed with a solution containing polyvinylpyrrolidone and branched polyethylenimine to obtain modified barium titanate nanoparticles; and the modified barium titanate nanoparticles, 1,3,5-tris(4-aminophenyl)benzene, and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde are mixed and subjected to a packaging reaction to obtain a barium titanate nanoparticle-compounded COF heterojunction. In the present invention, barium titanate and COFs are selected to form a piezoelectric-optical composite material, the advantages of the barium titanate and the COFs are combined, so that the catalytic performance of the material can be significantly improved.

Description

Barium titanate nanoparticle composite covalent organic framework heterojunction and preparation method thereof

Technical field

The invention relates to the technical fields of inorganic-organic nanocomposite materials and piezoelectric-photocatalysis, and specifically relates to the preparation of barium titanate nanoparticles/covalent organic framework heterojunction and its piezoelectric-photocatalytic degradation and removal of organic pollutants in water bodies. .

Background technique

With the continuous advancement of the modernization process, people's living standards have been greatly improved, but this has also brought about a series of environmental pollution and energy shortage problems. In order to solve these problems, it is necessary to explore and develop new energy-driven low-energy-consuming and highly adaptable environmental remediation technologies. Photocatalytic materials, which can convert solar energy into chemical energy, are expected to be used to solve the current increasingly serious environmental problems. However, the rapid combination of photogenerated electrons and holes results in low photocatalytic efficiency, limiting the practical application of photocatalytic technology. Although various strategies have been explored to improve photocatalytic efficiency, such as metal or non-metal doping, morphology manipulation, band gap engineering, and heterojunction structures, there is still a huge amount of effective charge transfer during the photocatalytic process potential. The prior art discloses a barium titanate nanomaterial for catalytically degrading trace organic pollutants in water and its preparation and application. The barium titanate nanomaterial uses titanium hydroxide precursor and barium hydroxide octahydrate as titanic acid respectively. The titanium source and barium source of barium nanomaterials are prepared by hydrothermal or solvothermal methods using sodium hydroxide and ethanol as reaction aids. The prior art discloses an Ag NWs@BaTiO ₃ core-sheath composite piezoelectric photocatalytic material and its preparation method and application. The surface sheath is the piezoelectric material barium titanate BaTiO ₃ and the core is silver nanowire Ag NWs. The existing technology discloses a barium titanate/potassium niobate composite piezoelectric photocatalyst. BaTiO ₃ nanospheres with a particle size of 30-50 nm are evenly distributed on prism-shaped KNbO _3. It has good stability and excellent catalytic activity. Looking at the existing technology, the preparation method of barium titanate catalyst is relatively complicated, and the treatment effect needs to be improved.

technical problem

The purpose of the present invention is to provide a method for preparing barium titanate nanoparticles/covalent organic framework heterojunction. The composite material formed can effectively remove bisphenol A in water under the combined action of ultrasonic vibration and light. As a specific example, polyvinylpyrrolidone (PVP) and branched polyethylenimine (BPEI) are first modified on the surface of barium titanate, and then 1,3,5-tris(4-ammonium titanate) is encapsulated through a simple encapsulation method. Phenyl)benzene (TAPB) and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP) are condensed on the surface of barium titanate to form a TAPB-DMTP-COF (TD-COF) shell, which is wrapped in titanium on the surface of barium acid nanoparticles. The barium titanate in the present invention can form a core-shell heterojunction structure with TD-COF, and at the same time has good adsorption performance and piezoelectric-photocatalytic performance. Experimental results show that under the combined action of ultrasound and light, the composite material has better performance in removing bisphenol A from water than barium titanate nanoparticles or pure TD-COF.

Technical solutions

In order to achieve the above purpose, the specific technical solution of the present invention is as follows: a barium titanate nanoparticle composite covalent organic framework heterojunction, and its preparation method includes the following steps: (1) Barium titanate with a particle size of 30 to 100 nanometers The nanoparticles are mixed with an ethanol solution containing polyvinylpyrrolidone (PVP) and branched polyethyleneimine (BPEI) to obtain modified barium titanate nanoparticles; (2) Modified barium titanate nanoparticles, 1, 3,5-Tris(4-aminophenyl)benzene (TAPB) and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP) are mixed to obtain composite covalent barium titanate nanoparticles through an encapsulation reaction Organic framework heterojunction (BTO@TD-COF).

A method for removing pollutants in water bodies, including the following steps: placing barium titanate nanoparticle composite covalent organic framework heterojunction (BTO@TD-COF) into water bodies containing pollutants, ultrasonic and/or illuminating, Complete the removal of pollutants in water bodies.

In the above technical solution, in step (1), the barium titanate nanoparticles are barium titanate nanospheres (BTO); the mass ratio of barium titanate nanoparticles, PVP, and BPEI is (30~50): (0.8 ~ 1.2) ∶1, preferably 40:1:1; the mass and weight ratio of PVP and BPEI relative to the ethanol solution is (0.03~0.07):1, preferably 0.05:1; the mixing time is 18~30 h, preferably 24 h; Preferably, barium titanate nanoparticles are added to the ethanol solution of PVP and BPEI, magnetically stirred for 24 hours, centrifuged and washed after stirring, and dried to obtain modified barium titanate nanoparticles. The present invention first uses PVP and BPEI to modify the barium titanate nanoparticles, which facilitates the growth of TD-COF on the surface of the barium titanate nanoparticles during the polycondensation process, thereby better wrapping the barium titanate nanoparticles.

In the above technical solution, in step (2), the molar ratio of DMTP and TAPB is (0.5~2):1, preferably 1.5:1; 1,3,5-tris(4-aminophenyl)benzene (TAPB), The mass ratio of the modified barium titanate nanoparticles is 10.5:1.95~9.75, preferably 10.5:5~6, such as 10.5:5.86.

In the above technical solution, the encapsulation reaction is carried out in the presence of acetic acid and in an organic solvent. Preferably, the modified barium titanate, TAPB and DMTP are mixed, and the added concentration is 10~17.5 M, preferably 17.5 M acetic acid, and the reaction is carried out at room temperature for 2 hours. Then add 8~12 M, preferably 10 M acetic acid and continue the reaction for 4 hours at 70 ^° C. After Soxhlet extraction and drying, the barium titanate nanoparticle composite covalent organic framework heterojunction is obtained. The organic solvents are 1,4-dioxane and n-butanol.

In the above technical solution, the barium titanate nanoparticle composite covalent organic framework heterojunction is placed into water containing pollutants, stirred in the dark, and then used ultrasonic-assisted illumination to achieve the removal of pollutants in the water.

The invention further discloses the application of barium titanate nanoparticles/covalent organic framework heterojunction in degrading pollutants in water, and the preferred pollutant is bisphenol A.

beneficial effects

Advantages of the present invention: 1. The barium titanate nanoparticles/covalent organic framework heterojunction disclosed in the present invention has the advantages of high stability, excellent performance and simple preparation method; 2. The barium titanate nanoparticles disclosed in the present invention/ The existence of the voltage electric field in the covalent organic framework heterojunction can reduce the recombination rate of free carriers and effectively promote the separation of free carriers; 3. This invention combines COF and barium titanate materials for the first time, and the existence of a built-in electric field It can effectively improve the photocatalytic performance of COF materials. At the same time, the excellent performance of COF materials enables composite materials to handle a large number of water pollutants.

Description of the drawings

Figure 1 shows the scanning electron microscopy and transmission electron microscopy images of TAPB-DMTP-COF. The upper left corner is the transmission electron microscopy image.

Figure 2 shows the scanning electron microscope image and the transmission electron microscope image of the barium titanate nanoparticle/covalent organic framework heterojunction. The upper left corner is the transmission electron microscope image.

Figure 3 shows the degradation curve of bisphenol A in water using different catalysts.

Figure 4 is a transmission electron microscope image of the barium titanate nanoparticle/covalent organic framework heterojunction.

Figure 5 is a cyclic degradation curve of bisphenol A in water by barium titanate nanoparticles/covalent organic framework heterojunction.

Embodiments of the invention

When piezoelectric materials are subjected to external stress, they will generate positive and negative charges on their opposite surfaces. The built-in electric field thus established can inhibit the recombination of photogenerated electrons and holes. The invention effectively combines piezoelectricity and photocatalysis to achieve very excellent pollutant degradation capabilities. Covalent organic framework materials (COFs) are an emerging class of crystalline porous organic materials. Due to their large specific surface area and good porosity, combined with barium titanate, they show good adsorption and degradation in water pollution treatment. ability, becoming a promising photocatalyst for environmental remediation. The present invention obtains barium titanate nanoparticles/covalent organic framework heterojunction through a simple encapsulation method, and achieves the purpose of degrading water pollutants under the simultaneous action of ultrasound and light. The raw materials of the present invention are existing products, and the specific preparation operations and testing methods are conventional technologies.

Example 1 Surface modification of barium titanate. The specific steps are as follows: 10 mL of ethanol containing 200 mg of barium titanate nanospheres (D90 particle size 50 nm, purchased from Aladdin (Shanghai) Reagent Co., Ltd.) was added dropwise to 5 mg of barium titanate nanospheres. PVP and 5 mg BPEI in 10 mL of ethanol, and then the resulting mixture was stirred regularly at room temperature for 24 h. Finally, the product was washed with ethanol three times and dried at 60 ^° C to obtain modified barium titanate (XBTO).

Example 2 Preparation of TAPB-DMTP-COF, the specific steps are as follows: 1,3,5-tris(4-aminophenyl)benzene (10.5 mg, 0.03 mmol), 2,5-dimethoxybenzene-1 , a mixture of 4-dicarboxaldehyde (8.7 mg, 0.045 mmol), 1,4-dioxane (2 mL) and n-butanol (2 mL) was conventionally sonicated for 60 minutes, and then 0.1 mL acetic acid was added and reacted at room temperature 2 h, then add 0.4 mL of 10 M acetic acid, and then react at 70°C for 4 h; after the reaction is completed, it is cooled to room temperature, the mixture is filtered and extracted with 250 mL of tetrahydrofuran Soxhlet for 24 h, and then dried at 60 ^° C. Obtain TAPB-DMTP-COF (TD-COF). Figure 1 is a scanning electron microscope image of the above simple TAPB-DMTP-COF. It can be seen from the figure that simple TAPB-DMTP-COF has a regular nanosphere morphology.

Example: Preparation of barium trititanate nanoparticle composite covalent organic framework heterojunction. The specific steps are as follows: 1,3,5-tris(4-aminophenyl)benzene (10.5 mg, 0.03 mmol), 2,5 -Dimethoxybenzene-1,4-dicarboxaldehyde (8.7 mg, 0.045 mmol), 1,4-dioxane (2 mL), n-butanol (2 mL), and 5.86 mg of modified barium titanate The mixture was conventionally sonicated for 60 minutes, then 0.1 mL acetic acid was added, reacted at room temperature for 2 h, then 0.4 mL 10 M acetic acid was added, and then reacted at 70°C for 4 h; after the reaction was completed, it was cooled to room temperature, and the mixture was filtered After Soxhlet extraction with 250 mL tetrahydrofuran for 24 h, and then drying at 60 ^° C, the final product barium titanate nanoparticle composite covalent organic framework heterojunction (BTO-3@TD-COF) was obtained. Figure 2 is a scanning electron microscope image of the above-mentioned barium titanate nanoparticle composite covalent organic framework heterojunction. From the picture, it can be seen that the barium titanate nanoparticle composite covalent organic framework heterojunction still maintains a regular nanosphere morphology. , and it can be clearly seen that TAPB-DMTP-COF completely wraps barium titanate.

Example 4 Preparation of barium titanate nanoparticle composite covalent organic framework heterojunctions with different mass ratios. The specific steps are as follows: 1,3,5-tris(4-aminophenyl)benzene (10.5 mg, 0.03 mmol) , 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (8.7 mg, 0.045 mmol), 1,4-dioxane (2 mL), n-butanol (2 mL), and modification of 1.95 mg After the barium titanate mixture was sonicated for 60 minutes, 0.1 mL of acetic acid was added and reacted at room temperature for 2 h. Then 0.4 mL of 10 M acetic acid was added, and then reacted at 70°C for 4 h; after the reaction was completed, it was cooled to room temperature. The mixture was filtered, Soxhlet extracted with 250 mL tetrahydrofuran for 24 h, and then dried at 60 ^° C to obtain the final product barium titanate nanoparticle composite covalent organic framework heterojunction (BTO-1@TD-COF).

Example 5 Preparation of barium titanate nanoparticle composite covalent organic framework heterojunctions with different mass ratios. The specific steps are as follows: 1,3,5-tris(4-aminophenyl)benzene (10.5 mg, 0.03 mmol) , 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (8.7 mg, 0.045 mmol), 1,4-dioxane (2 mL), n-butanol (2 mL), and modification of 9.75 mg After the barium titanate mixture was sonicated for 60 minutes, 0.1 mL of acetic acid was added and reacted at room temperature for 2 h. Then 0.4 mL of 10 M acetic acid was added, and then reacted at 70°C for 4 h; after the reaction was completed, it was cooled to room temperature. The mixture was filtered, Soxhlet extracted with 250 mL tetrahydrofuran for 24 h, and then dried at 60 ^o C to obtain the final product barium titanate nanoparticle composite covalent organic framework heterojunction (BTO-5@TD-COF).

Comparative Example 1: 1,3,5-tris(4-aminophenyl)benzene (10.5 mg, 0.03 mmol), 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (8.7 mg, 0.045 mmol) ), 1,4-dioxane (2 mL), n-butanol (2 mL) and 5.86 mg of barium titanate nanospheres (D90 particle size 50 nm, purchased from Aladdin (Shanghai) Reagent Co., Ltd.) The mixture was conventionally sonicated for 60 minutes, then 0.1 mL acetic acid was added, reacted at room temperature for 2 h, then 0.4 mL 10 M acetic acid was added, and then reacted at 70°C for 4 h; after the reaction was completed, it was cooled to room temperature, the mixture was filtered and used 250 mL of tetrahydrofuran was Soxhlet extracted for 24 h and then dried at 60 ^o C to obtain the final product (WBTO@TD-COF).

Example 6: Piezoelectric-photocatalytic degradation experiment of bisphenol A by different catalysts: Place 5 mg of catalyst in a small beaker of 50 mL bisphenol A aqueous solution with a concentration of 20 mg/L, and adsorb it in the dark for 2 hours. During this period, Take a sample of 1 mL after 60 minutes, filter it through a filter head (0.22 μm), and then inject it into a high-performance liquid phase sample bottle. After adsorption equilibrium, transfer the sample to a glass test tube, place the test tube in an ultrasonic cleaner, turn on the ultrasound (180 W, 45 Hz) and simultaneously turn on the xenon light source (visible light, 300 W), sample 1 mL every 5 minutes, and Filter the catalyst through a filter head (0.22 μm) and inject it into a high-performance liquid phase sample bottle. Use a high-performance liquid chromatograph to test the absorption curve of the sample at a UV wavelength of 290 nm in a mobile phase of deionized water: methanol = 30:70. Record the bisphenol A peak area at about 6 minutes, and record the initial bisphenol A concentration as 100% to obtain the piezoelectric catalytic degradation curve of bisphenol A.

The catalysts are existing barium titanate nanospheres, TAPB-DMTP-COF, and BTO/TD-COF (BTO-3@TD-COF). The degradation results of bisphenol A are shown in Figure 3. The BTO/TD-COF of the present invention Complete degradation of bisphenol A was achieved 30 minutes after adsorption equilibrium.

Example 7: Using other catalysts, bisphenol A is degraded according to the method of Example 6. After 30 minutes of adsorption equilibrium, the residual rate of bisphenol A is as shown in Table 1; using BTO-3@TD-COF as the catalyst, in Example Based on method six, omitting ultrasound or light, 30 minutes after adsorption equilibrium, the residual rate of bisphenol A is as shown in Table 1.

.

XBTO+TD-COF refers to the regular grinding and mixing of modified barium titanate and TAPB-DMTP-COF for 30 minutes.

Example 8: Replace the barium titanate nanospheres in Example 1 with barium titanate cubes (D90 particle size 10 nm, purchased from Aladdin (Shanghai) Reagent Co., Ltd.), and leave the rest unchanged to obtain modified barium titanate. ; Then according to the method of Example 3, a barium titanate nanoparticle composite covalent organic framework heterojunction is obtained, and Figure 4 is a transmission electron microscope image thereof; Bisphenol A is degraded according to the method of Example 6, and after 30 minutes of adsorption equilibrium , Bisphenol A residual rate is 40%.

Example 9: Cyclic degradation experiment of BTO-3@TD-COF on bisphenol A in water. In Example 6, the composite material recovered after ultrasonic illumination for 30 minutes was washed with deionized water and 95% ethanol in sequence, dried in a vacuum oven, and then re-added to the newly taken 50 mL of bisulfite with a concentration of 20 mg/L. Phenol A solution was stirred for 2 h under dark conditions to achieve adsorption equilibrium. After equilibrium, transfer the solution to an ultrasonic cleaner, turn on the xenon light source (visible light) while turning on the ultrasound, take 1 mL every 5 minutes, filter it with a 0.22 μm filter head, and put it into a high-performance liquid phase sample bottle. Use high-performance liquid phase. The phase chromatograph tests the absorption curve of the sample at a UV wavelength of 290 nm in a mobile phase of deionized water: methanol = 3:7 (volume ratio), records the peak area of bisphenol A around 6 minutes, and converts the initial bisphenol A into The concentration was recorded as 100%, and the piezoelectric degradation curve of bisphenol A was obtained. Repeat the above steps 5 times, test and record the data respectively. The results are shown in Figure 5. It can be seen from the figure that in the five repeated processes, the piezoelectric catalyst of the present invention always maintains excellent piezoelectric catalytic performance, and the final removal rate of bisphenol A in the aqueous solution is greater than 90%. Therefore, the catalyst can be reused and has good stability.

The invention discloses a barium titanate nanoparticle/covalent organic framework heterojunction composite material that can effectively adsorb and degrade water-soluble organic pollutants under simultaneous stimulation by ultrasound and light. 1,3,5-Tris(4-aminophenyl)benzene (TAPB) and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP) were condensed and encapsulated in titanate through a simple encapsulation method. A covalent organic framework shell (TD-COF) is formed on the surface of barium nanoparticles (BTO), and a barium titanate nanoparticle/covalent organic framework core-shell heterojunction (BTO@TD-COF) is constructed; in piezoelectricity and illumination , the catalytic performance is significantly improved.

Claims

A method for preparing barium titanate nanoparticle composite covalent organic framework heterojunction, which is characterized by including the following steps:

(1) Mix barium titanate nanoparticles with a solution containing polyvinylpyrrolidone and branched polyethyleneimine to obtain modified barium titanate nanoparticles;

(2) Mix modified barium titanate nanoparticles, 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde through encapsulation reaction A barium titanate nanoparticle composite covalent organic framework heterojunction is obtained.
The preparation method of barium titanate nanoparticles composite covalent organic framework heterojunction according to claim 1, characterized in that the barium titanate nanoparticles are barium titanate nanospheres; barium titanate nanoparticles, polyvinylpyrrolidone, branched The mass ratio of polyethyleneimine is (30~50): (0.8~1.2):1.
The method for preparing barium titanate nanoparticle composite covalent organic framework heterojunction according to claim 1, characterized in that in step (1), the mixing time is 18 to 30 h.
The preparation method of barium titanate nanoparticle composite covalent organic framework heterojunction according to claim 1, characterized in that, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 1,3,5- The molar ratio of tris(4-aminophenyl)benzene is (0.5~2):1; the mass ratio of 1,3,5-tris(4-aminophenyl)benzene to modified barium titanate nanoparticles is 10.5 ∶1.95~9.75.
The method for preparing barium titanate nanoparticle composite covalent organic framework heterojunction according to claim 1, characterized in that the encapsulation reaction is carried out in the presence of acetic acid and in an organic solvent.
The preparation method of barium titanate nanoparticle composite covalent organic framework heterojunction according to claim 1, characterized in that modified barium titanate nanoparticles, 1,3,5-tris(4-aminophenyl) )benzene and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde are mixed, acetic acid is added to react at room temperature, and then acetic acid is added to continue the reaction at 60°C~80°C to obtain barium titanate nanoparticle composite covalent organic Skeleton heterojunction.
The barium titanate nanoparticle composite covalent organic framework heterojunction is prepared according to the method for preparing the barium titanate nanoparticle composite covalent organic framework heterojunction of claim 1.
A method for removing pollutants in water, characterized by comprising the following steps: placing the barium titanate nanoparticle composite covalent organic framework heterostructure of claim 7 into a water body containing pollutants, ultrasonic and/or Light, complete the removal of pollutants in water bodies.
The method for removing pollutants in water according to claim 8, characterized in that the barium titanate nanoparticle composite covalent organic skeleton heterojunction is placed in the water containing pollutants, and is stirred in the dark and then combined with ultrasonic light to achieve Removal of pollutants from water.
Application of the barium titanate nanoparticle composite covalent organic framework heterojunction described in claim 7 in degrading pollutants in water.