In2O3 / ZnO / BiOBr catalyst for efficiently degrading rhodamine B and preparation method thereof

Abstract

The invention discloses an In2O3 / ZnO / BiOBr catalyst for efficiently degrading rhodamine B and a preparation method of the In2O3 / ZnO / BiOBr catalyst. The In2O3 / ZnO / BiOBr photocatalyst with a high specific surface area is prepared through a simple one-pot hydrothermal method, the degradation performance of the photocatalyst is improved through simultaneous coupling of In2O3, ZnO and BiOBr, formed double-Z-type heterojunctions are beneficial to inhibition of recombination of photon-generated carriers, and organic dye rhodamine B can be efficiently degraded through construction of the structure. And after sunlight irradiation is simulated for 40 minutes, the degradation rate of rhodamine B reaches 98.80%, and after four continuous degradation experiments, the degradation rate is not obviously attenuated. The material is simple in preparation method and excellent in degradation performance, and has a wide application prospect in the field of organic pollutant removal.

Description

Technical Field

[0001] The invention relates to the field of photocatalytic technology and environmental governance, and in particular to an In2O3 / ZnO / BiOBr catalyst for efficiently degrading rhodamine B and a preparation method thereof. Background Art The rise of industry has driven the development of society, but it will inevitably produce a large number of organic pollutants, such as dyes, antibiotics, pesticides and heavy metal ions. These pollutants discharged into the water will not only further deteriorate the environment but also affect human survival, which makes it necessary to study the removal of various pollutants in water. Photocatalysis, as a new type of sewage treatment technology that is efficient, energy-saving and environmentally friendly, has been proven to be an effective way to solve this problem.

[0002] Among many photocatalysts, semiconductor metal oxides (MOs) have attracted widespread attention due to their advantages such as stability, low cost, and easy preparation. Among them, In2O3, as a MOs with excellent photoelectric properties, is widely used in the field of photocatalysis. However, In2O3 still has certain defects. Due to its high recombination rate of photogenerated electrons and holes, its photocatalytic activity is poor. Researchers have found that combining it with other materials to form a heterojunction can effectively improve the utilization rate of sunlight and thus enhance its photocatalytic performance.

[0003] ZnO is widely recognized as a promising photocatalytic material due to its good conductivity and photostability. However, pure ZnO has a large band gap (Eg≈3.2eV) and can only absorb ultraviolet light. Therefore, in order to improve the visible light activity of ZnO materials, it is necessary to compound it with other materials to enhance its photocatalytic performance.

[0004] BiOBr is a ternary semiconductor, its structure consists of [Bi2O2] 2+ The unique layered structure of BiOBr not only gives it a richer specific surface area and a large number of active sites, but also inhibits the recombination of photogenerated carriers to a certain extent. Therefore, the simultaneous coupling of In2O3, ZnO and BiOBr can be used to construct a ternary composite material with high catalytic activity. The synergistic effect between the three provides a more efficient path for charge transfer, so that the prepared ternary heterojunction photocatalyst has greater application potential in the field of photocatalysis. Summary of the invention

[0005] The present invention aims to solve the problems of small specific surface area and poor stability of existing photocatalysts and difficulty in degrading Rhodamine B in wastewater, and to provide a preparation method of an In2O3 / ZnO / BiOBr catalyst for efficiently degrading Rhodamine B, so as to achieve the purpose of rapidly removing organic pollutants.

[0006] An In2O3 / ZnO / BiOBr catalyst for efficient degradation of rhodamine B and a preparation method thereof, characterized by comprising the following steps: 1) Weigh a certain amount of indium nitrate hydrate and urea, place them in 8 mL of deionized water, stir until clear and transparent, mix them, and continue stirring for 1 hour; 2) placing the solution of 1) in a sealed stainless steel autoclave lined with polytetrafluoroethylene, placing it in a constant temperature oven, and reacting it at high temperature for a certain period of time; 3) After the reactor in step 2) is naturally cooled to room temperature, the sample is centrifuged three times with deionized water and anhydrous ethanol, and then placed in a 60° C. constant temperature drying oven for 12 h. The sample is placed in a muffle furnace and calcined at high temperature to generate In2O3 powder. 4) Under magnetic stirring, a certain amount of hexadecyltrimethylammonium bromide was dissolved in deionized water, and then a certain amount of zinc acetate dihydrate was added to the solution, and the solution was adjusted to alkalinity with NaOH, and the reaction was carried out for 1 hour. The obtained product was filtered and washed three times, and dried in a constant temperature drying oven at 60°C overnight. Finally, the product was placed in a muffle furnace and calcined at high temperature to obtain ZnO. 5) First, equal masses of In2O3 and ZnO are dispersed in deionized water by ultrasonic treatment, and then mixed after ultrasonic treatment for 15 minutes. A certain mass of bismuth nitrate pentahydrate and hexadecyltrimethylammonium bromide are respectively added to the suspension and stirred evenly; 6) Pour the solution in 5) into a 50 ml stainless steel autoclave and react at high temperature for a certain period of time in a constant temperature oven. After the reaction, centrifuge and wash the product several times and dry it at 60° C. overnight to obtain an In2O3 / ZnO / BiOBr composite material.

[0007] According to the above scheme, the molar ratio of the indium nitrate hydrate to urea is 1:3.

[0008] According to the above scheme, the molar ratio of hexadecyltrimethylammonium bromide to zinc acetate dihydrate is 1:8.

[0009] According to the above scheme, the molar ratio of the bismuth nitrate pentahydrate to hexadecyltrimethylammonium bromide is 1:1.

[0010] According to the above scheme, the reaction temperature of the reactor is 100-200°C, and the reaction time is 18-26h.

[0011] According to the above scheme, the calcination temperature is 500-600°C, and the calcination time is 2-4 hours.

[0012] The In2O3 / ZnO / BiOBr catalyst prepared by the invention is used for degrading the organic pollutant Rhodamine B.

[0013] The present invention has the following beneficial effects:

[0014] The present invention adopts a simple one-pot method to prepare the In2O3 / ZnO / BiOBr photocatalyst with a sheet structure. This structure increases the area of ​​the contact interface between the dye and the catalyst, which is beneficial to improving the degradation ability of the catalyst.

[0015] The invention takes a short time and has a simple synthesis process. The prepared sample has excellent degradation performance. After four cycles, the degradation rate does not decay significantly, indicating that the sample has high cycle stability and reusability, and has good application prospects in the fields of environmental management and photocatalytic technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a scanning electron microscope (SEM) image of the In2O3 material prepared in Example 1; Figure 2 is a scanning electron microscope (SEM) image of the In2O3 / ZnO / BiOBr composite material prepared in Example 1; Figure 3 is a time evolution diagram of the absorption spectrum during the photocatalytic degradation process of the In2O3 / ZnO / BiOBr composite material prepared in Example 1; Figure 4 The graph is a graph showing the degradation efficiency of the In2O3 / ZnO / BiOBr composite material prepared in Example 1 for Rhodamine B solution as a function of reaction time. In addition, the curves showing the degradation efficiency of the three materials In2O3, ZnO and BiOBr for Rhodamine B solution as a function of reaction time are used for comparison; Figure 5 This is a cycle curve diagram of the degradation of the organic pollutant Rhodamine B by the In2O3 / ZnO / BiOBr composite material prepared in Example 1. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0018] Embodiment 1: An In2O3 / ZnO / BiOBr catalyst for efficient degradation of rhodamine B and a preparation method thereof comprises the following steps: 1) Weigh 1.00 g of indium nitrate hydrate and 0.60 g of urea, respectively, place in 8 mL of deionized water and stir until clear and transparent, mix them, and continue stirring for 1 hour; 2) placing the solution of 1) in a sealed stainless steel autoclave lined with polytetrafluoroethylene, placing it in a constant temperature oven, and reacting it at high temperature for a certain period of time; 3) After the reactor in step 2) is naturally cooled to room temperature, the sample is centrifuged three times with deionized water and anhydrous ethanol, and then placed in a 60° C. constant temperature drying oven for 12 h. The sample is placed in a muffle furnace and calcined at high temperature to generate In2O3 powder. 4) Under magnetic stirring, a certain amount of hexadecyltrimethylammonium bromide was dissolved in deionized water, and then a certain amount of zinc acetate dihydrate was added to the solution, and the solution was adjusted to alkalinity with NaOH, and the reaction was carried out for 1 hour. The obtained product was filtered and washed three times, and dried in a constant temperature drying oven at 60°C overnight. Finally, the product was placed in a muffle furnace and calcined at high temperature to obtain ZnO. 5) First, equal masses of In2O3 and ZnO are dispersed in deionized water by ultrasonic treatment, and then mixed after ultrasonic treatment for 15 minutes. A certain mass of bismuth nitrate pentahydrate and hexadecyltrimethylammonium bromide are respectively added to the suspension and stirred evenly; 6) Pour the solution in 5) into a 50 ml stainless steel autoclave and react at high temperature for a certain period of time in a constant temperature oven. After the reaction, centrifuge and wash the product several times and dry it at 60° C. overnight to obtain an In2O3 / ZnO / BiOBr composite material.

[0019] Example 1 is an In2O3 / ZnO / BiOBr composite material prepared by a one-pot hydrothermal method. Its preparation method is simple, low cost, has high degradation ability, and has good application in environmental governance.

[0020] The scanning electron microscope image of the In2O3 material prepared in Example 1 is as follows: Figure 1 The material shows that In2O3 has an aggregated rod-like microstructure, and the length of the rod-like particles is about 1μm.

[0021] The scanning electron microscope image of the In2O3 / ZnO / BiOBr composite material prepared in Example 1 is shown in Figure 2. During the hydrothermal process, the three samples were rearranged, intertwined and stacked to form a sheet structure. This increases the contact area between the dye and the catalyst, which is beneficial to improving the degradation ability of the catalyst.

[0022] The time evolution of the absorption spectrum of the In2O3 / ZnO / BiOBr composite material prepared in Example 1 during the photocatalytic degradation process is shown in the figure below: Figure 3 As shown in the figure, with the increase of simulated solar light irradiation time, the absorption peak of Rhodamine B gradually weakened, indicating that the concentration of Rhodamine B in the solution gradually decreased. After 40 minutes, the degradation of Rhodamine B was completed.

[0023] The degradation efficiency of the In2O3 / ZnO / BiOBr composite material prepared in Example 1 for the Rhodamine B solution changes with the reaction time. Figure 4 As shown. The catalyst reached adsorption equilibrium after 25 minutes of adsorption of Rhodamine B. After 40 minutes of simulated solar irradiation (at room temperature), the degradation rate of Rhodamine B by In2O3 / ZnO / BiOBr composite material reached 98.80%. The higher degradation efficiency of the composite sample can be attributed to the synergistic effect between In2O3, ZnO and BiOBr, which promoted the transfer of photogenerated electron-hole pairs.

[0024] The cycle curve of the In2O3 / ZnO / BiOBr composite material prepared in Example 1 for degradation of the organic pollutant Rhodamine B is shown in FIG. Figure 5 After four consecutive degradation experiments of Rhodamine B by In2O3 / ZnO / BiOBr composite material, the degradation rate of the dye by the catalyst showed extremely weak attenuation, indicating that the sample has excellent cycle stability and reusability.

Claims

1. A method for preparing an In2O3 / ZnO / BiOBr catalyst for efficiently degrading rhodamine B, the method comprising the following steps: 1) Weigh a certain amount of indium nitrate hydrate and urea, place them in 8 mL of deionized water, stir until clear and transparent, mix them, and continue stirring for 1 hour; 2) placing the solution of 1) in a sealed stainless steel autoclave lined with polytetrafluoroethylene, placing it in a constant temperature oven, and reacting it at high temperature for a certain period of time; 3) After the reactor in step 2) is naturally cooled to room temperature, it is centrifuged repeatedly with deionized water and anhydrous ethanol for 3 times, and then placed in a 60°C constant temperature drying oven for 12 hours, and the sample is placed in a muffle furnace for high temperature calcination to generate In2O3 powder; 4) Under magnetic stirring, a certain amount of hexadecyltrimethylammonium bromide was dissolved in deionized water, and then a certain amount of zinc acetate dihydrate was added to the solution, and the solution was adjusted to alkalinity with NaOH, and reacted for 1 hour. The obtained product was filtered and washed three times, and dried in a constant temperature drying oven at 60°C overnight. Finally, the product was placed in a muffle furnace and calcined at high temperature to obtain ZnO; 5) First, equal masses of In2O3 and ZnO are dispersed in deionized water by ultrasonic treatment, and then mixed after ultrasonic treatment for 15 minutes. A certain mass of bismuth nitrate pentahydrate and hexadecyltrimethylammonium bromide are respectively added to the suspension and stirred evenly; 6) Pour the solution in 5) into a 50 ml stainless steel autoclave and react at high temperature for a certain period of time in a constant temperature oven. After the reaction, centrifuge and wash the product several times and dry it at 60° C. overnight to obtain an In2O3 / ZnO / BiOBr composite material.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the indium nitrate hydrate to urea is 1:

3.

3. The preparation method according to claim 1, characterized in that: The molar ratio of the hexadecyltrimethylammonium bromide to the zinc acetate dihydrate is 1:

8.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the bismuth nitrate pentahydrate to hexadecyltrimethylammonium bromide is 1:

1.

5. The preparation method according to claim 1, characterized in that: The reaction temperature of the reactor is 100-200° C., and the reaction time is 18-26 hours.

6. The preparation method according to claim 1, characterized in that: The calcination temperature is 500-600° C., and the calcination time is 2-4 hours.

7. The preparation method according to claim 1, characterized in that: Used to degrade the organic pollutant Rhodamine B.

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