CN114538504A

CN114538504A - PbTiO 23Flower-like particles, their preparation and use

Info

Publication number: CN114538504A
Application number: CN202210190496.8A
Authority: CN
Inventors: 简刚; 董瑞
Original assignee: Jiangsu University of Science and Technology
Current assignee: Jiangsu University of Science and Technology
Priority date: 2022-02-28
Filing date: 2022-02-28
Publication date: 2022-05-27

Abstract

The invention discloses PbTiO₃Flower-like particles, preparation and application thereof, and PbTiO₃The particles are prepared by a two-step hydrothermal method, the product presents flower-like appearance, and more catalytic reaction sites can be provided compared with materials with other appearances; the material can carry out high-efficiency piezoelectric-photocatalytic degradation on methylene blue solution under the dual actions of a xenon lamp and ultrasound, the piezoelectric-photocatalytic technology has the advantages of simplicity, convenience and effectiveness, and compared with single photocatalysis or piezoelectric catalysis, the material has higher degradation efficiency in the same time, so that the material has wide application prospects in the aspects of sewage treatment and environmental remediation technologies.

Description

PbTiO 23Flower-like particles, their preparation and use

Technical Field

The invention belongs to the technical field of piezoelectric-photocatalysis, and particularly relates to PbTiO₃Flower-like particles and their preparation and use.

Background

With the continuous development of industrialization, the world is currently faced with severe environmental problems, wherein the disposal and discharge of organic pollutants in water bodies become more significant problems endangering human life health and safety. In order to solve this problem, those skilled in the art have proposed many possible solutions, wherein the photocatalytic degradation technology is considered as a promising treatment technology due to its advantages of non-toxicity, low cost and high catalytic activity. However, the technology has many limitations in practical use due to low separation efficiency and fast recombination speed of electron-hole pairs.

In order to solve the above problems, a common approach is to construct a built-in electric field in the photocatalyst to provide power for photoinduced electrons and holes to be effectively separated. Ferroelectric materials have gained much attention in recent years as a material that enables better separation of carriers during catalysis. The piezoelectric material has the advantage of mutual conversion between mechanical disturbance and electric energy, and can induce local polarization charges on the surface to form an embedded electric field. The built-in electric field can spatially separate free electron-hole pairs, and further react with oxygen molecules and water to decompose organic pollutants. Piezoelectric materials have also been widely studied as new materials for degrading organic pollutants.

Therefore, the dye decomposition efficiency can be further improved based on the synergistic effect of the photocatalysis and the piezoelectric catalysis in theory, and the application of the photocatalysis is promoted. Ferroelectric oxide PbTiO₃Is a typical tetragonal perovskite structure material, has simple structure and excellent ferroelectric, piezoelectric and dielectric properties, and Chinese patent CN 104001493B discloses PbTiO with octahedral morphology₃-TiO₂A preparation method of the composite nano photocatalyst; the prepared PbTiO with octahedral morphology₃-TiO₂The composite nano photocatalyst can adjust the ultraviolet light catalysis of titanium dioxide into visible light catalysis, completely degrade methylene blue solution within 70min, but the scheme does not effectively couple ferroelectric oxide PbTiO₃The piezoelectric property and the photoelectric property of the composite material and the application in the degradation aspect are yet to be further explored.

Disclosure of Invention

The invention aims to provide PbTiO₃Flower-like particles, preparation and application thereof, and PbTiO obtained₃The flower-shaped particles can be used for piezoelectric-photocatalytic degradation of pollutants such as methylene blue and the like, and have high degradation efficiency and stable catalytic performance.

The technical scheme of the invention is as follows: PbTiO 2₃The preparation method of the flower-shaped particles specifically comprises the following steps:

1) adding tetra-n-butyl titanate to a mixture of ethanol and glycerol to obtain a mixed solution;

2) transferring the mixed solution obtained in the step 1) into a polytetrafluoroethylene-lined stainless steel autoclave for heating reaction, washing, collecting the obtained product, performing heat treatment, and standing in the air for a period of time to obtain TiO₂Flower-like particles;

3) adding TiO into the mixture₂Adding the flower-shaped particles and lead acetate trihydrate into deionized water, and stirring to obtain a mixed material;

4) transferring the mixed material into a high-pressure reaction kettle for heating treatment, cleaning, collecting and drying the obtained product, placing the product in the air for a period of time after the heat treatment to obtain the PbTiO₃Flower-like particles.

Further, the amount of tetra-n-butyl titanate in the step 1) is 1-3 g, 20-40 mL of ethanol and 5-15 mL of glycerol.

Further, the temperature of heating in the autoclave in the step 2) is 170-190 ℃, and the heating time is 22-26 h; the heat treatment process is carried out at 430-450 ℃, and the mixture is placed in the air for 2-4 hours.

Further, in step 3), flower-like TiO in the mixture₂The concentration of the particles was 0.001mol/L and the concentration of lead acetate trihydrate was 0.0001 mol/L.

Further, in the step 4), the temperature is 250-300 ℃ when the mixture is heated in a high-pressure reaction kettle, and the heating time is 5-7 h; and then cleaning at 80-90 ℃, wherein the heat treatment temperature is 480-520 ℃, and placing in the air for 1-2 hours.

PbTiO prepared according to the above method₃The particles present a flower-like morphology structure.

PbTiO as described above₃The particles can be applied to piezoelectric-photocatalytic degradation of methylene blue dye wastewater, can completely degrade 5mg/L of methylene blue solution within 40min under the dual effects of an ultrasonic cleaner and a xenon lamp, and has higher efficiency than a single catalytic mode, and the PbTiO prepared by the method is applied to the preparation of the PbTiO₃The flower-like particles have high reusability, are recovered after experiments, and have PbTiO after 4-6 times of continuous synergistic reaction₃The catalytic ability of (a) is still maintained at a high level.

PbTiO prepared by the present application₃The flower-shaped particles as piezoelectric materials have the characteristic of interconversion between mechanical disturbance and electric energy, and can induce local charges on the surface to be polarized to form an embedded electric field. The built-in electric field can separate free electron-hole pairs in space, and the free electron-hole pairs further react with oxygen molecules and water under the irradiation of ultraviolet light, so that organic pollutants are finally decomposed.

Compared with the prior art, the invention has the following advantages:

1. PbTiO prepared by the present application₃When the particles are used for water pollution treatment, a piezoelectric effect is generated through ultrasonic waves, and methylene blue organic pollutants in a water body can be completely degraded under the synergistic catalysis effect of ultraviolet light, two catalysis modes of photocatalysis and piezoelectric catalysis are effectively coupled, so that the electron transmission characteristic is changed, the separation of photo-generated electron-hole pairs in the photocatalytic reaction is driven, and the degradation efficiency is effectively improved finally;

2. PbTiO prepared by the method disclosed by the application₃The particles have flower-shaped morphology, can provide more catalytic reaction active sites, is beneficial to the rapid degradation process, can completely degrade 5mg/L methylene blue solution within 40min under the dual functions of piezoelectric and photocatalysis, and has remarkably improved catalytic degradation efficiency compared with similar materials disclosed in the prior art;

3. the present application utilizes only PbTiO without complexing with other particles₃The particles can show good methylene blue catalytic degradation effect, so that the whole preparation process is simpler, the preparation efficiency is improved, the material cost can be more effectively controlled, and the method is more suitable for industrial popularization and application.

Drawings

FIG. 1 shows PbTiO obtained in example 1₃Scanning electron microscope pictures of the particles;

FIG. 2 shows the use of PbTiO obtained in example 1₃Carrying out piezoelectric-photocatalytic degradation on a methylene blue solution of 5mg/L by the particles to obtain a degradation curve;

FIG. 3 shows PbTiO obtained in example 1₃Powder XRD pattern of flower-like particles after four catalytic reactions;

FIG. 4 shows PbTiO prepared in example 1 in a comparative test example₃Degradation curves obtained by photocatalytic degradation of particles on a 5mg/L methylene blue solution.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings, but not limited thereto, and any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be covered by the protection scope of the present invention.

Example I A PbTiO₃Preparation of flower-like particles

1) Adding 2g of tetra-n-butyl titanate (98%, alatin, china) to a mixture of 30mL of ethanol (99.5%, alatin, china) and 10mL of glycerol (99.5%, alatin, china) to obtain a mixed solution;

2) transferring the mixed solution obtained in the previous step into a 100mL stainless steel autoclave with a polytetrafluoroethylene lining, and continuously heating for 24 hours at 180 ℃; washing, collecting and heat treating the obtained product at 450 ℃, and standing in the air for 2-4 hours to obtain TiO₂Flower-like particles;

3) 0.02765g of TiO₂The granules and 0.13276g of lead acetate trihydrate were added to 350mL of deionized water and stirred for 1h (molar ratio of Pb/Ti 1: 1; Pb in solution)²⁺And Ti⁴⁺The concentration of the components is 0.001M) to obtain a mixed material;

4) transferring the mixed material into a 500mL stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, and heating for 6 hours at 260 ℃; cleaning at 85 deg.C, collecting, drying, performing heat treatment at 500 deg.C, and standing in air for 1-2 hr; to obtain PbTiO₃Particles;

FIG. 1 shows PbTiO obtained in this example₃The obtained particles are in a flower-like shape, and the particles with the shapes have larger specific surface area, can provide more catalytic reaction sites during catalytic reaction and are beneficial to accelerating the reaction process;

correlation performance detection

1) Preparing methylene blue with the concentration of 5mg/L100mL of the solution was added 2g of PbTiO obtained in example 1₃And (4) carrying out magnetic stirring on the granules for 40min to achieve adsorption balance under the dark condition by using a magnetic stirrer. Adding an optical filter at the mouth of a beaker, performing a piezoelectric-photocatalytic degradation reaction under the synergistic action of an ultrasonic cleaner (40kHz,180W) and a xenon lamp (300W) at room temperature, keeping the solution at a distance of 15cm from a light source, cooling with water to prevent the temperature of the solution from rising, sampling 5mL of PbTiO at each time every 10min, and sampling PbTiO₃The piezoelectric-photocatalytic degradation curve of the flower-like particles is shown in fig. 2, and it can be seen from the graph that after 40min, methylene blue is completely degraded, the solution becomes clear, and finally the sample is centrifuged.

2) For PbTiO₃The flower-like particles are subjected to a piezoelectric-photocatalytic recovery experiment, and PbTiO is subjected to continuous synergistic reaction operation₃The catalytic ability of (a) is maintained at a high level. After run 4, which was still active, see in particular fig. 3, it can be seen from fig. 3 that the XRD pattern of the powder after four reactions was consistent with the peak position and shape of the curve of the sample without catalytic reaction, indicating that the powder phase did not change before and after catalytic reaction.

3) Reducing the initial concentration of methylene blue, preparing 100mL of methylene blue solution with the concentration of 4mg/L, and finding out that the methylene blue solution with the concentration is completely degraded after 35min through a piezoelectric-photocatalytic degradation experiment which is the same as that of 1), so that the solution becomes clear.

4) Comparative test example:

100mL of methylene blue solution having a concentration of 5mg/L was prepared, and 2g of PbTiO 2 obtained in example 1 was added₃And (4) carrying out magnetic stirring on the granules for 40min by a magnetic stirrer under the dark condition to achieve adsorption balance. Placing an optical filter at the mouth of the beaker, and carrying out photocatalytic degradation on the solution under the action of a xenon lamp (300W) at room temperature, wherein the distance between the solution and a light source is 15 cm. Samples were taken every 10min, 5mL each, and finally the samples were centrifuged. PbTiO 2₃The photocatalytic degradation curve of the flower-like particles is shown in fig. 4, and it can be seen from the graph that after 60min, the methylene blue solution is completely degraded, which indicates that the piezo-photocatalysis has higher efficiency than the single photocatalysis. It is inferred that the pressure was generated due to the mechanical force applied to the catalyst powder by the ultrasoundThe piezoelectric potential can promote the separation of photon-generated carriers, thereby improving the photocatalytic efficiency.

The above description is only an embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes performed by the present invention or directly or indirectly applied to other related technical fields are included in the scope of the present invention.

Claims

1. PbTiO 2₃The preparation method of the flower-shaped particles is characterized by comprising the following steps:

2) transferring the mixed solution obtained in the step 1) into a polytetrafluoroethylene-lined stainless steel autoclave, carrying out heating reaction, washing, collecting the obtained product, carrying out heat treatment, and standing in the air for a period of time to obtain TiO₂Flower-like particles;

2. A PbTiO according to claim 1₃The preparation method of the flower-like particles is characterized in that the amount of the tetra-n-butyl titanate in the step 1) is 1-3 g, 20-40 mL of ethanol and 5-15 mL of glycerol.

3. A PbTiO according to claim 1₃The preparation method of the flower-like particles is characterized in that the temperature of heating in the autoclave in the step 2) is 170-190 ℃, and the heating time is 22-26 h; the heat treatment process is carried out at 430-450 ℃, and the mixture is placed in the air for 2-4 hours.

4. A PbTiO according to claim 1₃The preparation method of the flower-shaped particles is characterized in that in the step 3), flower-shaped TiO in the mixture₂The concentration of the particles was 0.001mol/L, the concentration of lead acetate trihydrate was 0.0001mol/L, and the molar ratio of Pb/Ti was 1: 1.

5. A PbTiO according to claim 1₃The preparation method of the flower-like particles is characterized in that in the step 4), the temperature is 250-300 ℃ when the flower-like particles are heated in a high-pressure reaction kettle, and the heating time is 5-7 h; and then cleaning at 80-90 ℃, wherein the heat treatment temperature is 480-520 ℃, and placing in the air for 1-2 hours.

6. PbTiO according to any one of claims 1 to 5₃PbTiO prepared by preparation method of flower-like particles₃Particles, characterized in that the PbTiO obtained₃The particles exhibit a flower-like morphology.

7. PbTiO according to claim 6₃The flower-like particles are applied to piezoelectric-photocatalytic degradation of methylene blue dye wastewater.