阅读说明：本技术 一种复合可见光催化剂及其制备方法和应用 (Composite visible light catalyst and preparation method and application thereof ) 是由 喻恺 吕燕妮 罗旭彪 邵鹏辉 石慧 杨利明 任重 熊贞晟 于 2020-05-11 设计创作，主要内容包括：本发明涉及光催化剂技术领域,具体涉及一种复合可见光催化剂及其制备方法和应用。本发明提供的制备方法兼顾材料的制备、改性和降解污染物,利用初始所需的合成材料降解污染物的同时制备出目标复合可见光催化剂材料。而且,本发明提供的制备方法得到的复合可见光催化剂,在贵金属银的作用下,通过二次调控碳酸氧铋的禁带宽度,能够促进其可见光催化效率的提高。由实施例的结果可知,本发明提供的制备方法得到的复合可见光催化剂在可见光的照射下对甲基橙、苯二胺、双酚A和罗丹明B的降解效率均远远大于市售的碳酸氧铋产品。(The invention relates to the technical field of photocatalysts, in particular to a composite visible-light-driven photocatalyst and a preparation method and application thereof. The preparation method provided by the invention gives consideration to preparation, modification and pollutant degradation of the material, and the target composite visible-light-driven photocatalyst material is prepared while the pollutant is degraded by using the initially required synthetic material. Moreover, the composite visible-light-driven photocatalyst obtained by the preparation method provided by the invention can promote the improvement of the visible-light-driven catalysis efficiency of bismuth oxycarbonate by secondarily regulating the forbidden bandwidth of bismuth oxycarbonate under the action of noble metal silver. The results of the examples show that the degradation efficiency of the composite visible-light-driven photocatalyst obtained by the preparation method provided by the invention under the irradiation of visible light on methyl orange, phenylenediamine, bisphenol A and rhodamine B is far higher than that of a commercially available bismuthyl carbonate product.)

1. The preparation method of the composite visible-light-driven photocatalyst is characterized by comprising the following steps:

carrying out first mixing on the sodium bismuthate dihydrate suspension and the soluble silver salt to carry out ion exchange reaction to obtain bismuth silver oxide;

carrying out second mixing on the bismuth silver oxide and the aqueous solution of the halogen-free water-soluble organic pollutant, carrying out solid-liquid separation after an oxidative degradation reaction is carried out, replacing the bismuth silver oxide with the solid-liquid separated solid, and circulating the processes of the second mixing and the solid-liquid separation to obtain a silver bismuthyl carbonate precursor;

and thirdly mixing the silver bismuthyl carbonate precursor and the silver ion aqueous solution to obtain the composite visible-light-driven photocatalyst.

2. The method of claim 1, wherein the halogen-free water-soluble organic contaminant comprises one or more of methyl orange, phenylenediamine, bisphenol a, and rhodamine B.

3. The method according to claim 1, wherein the mass ratio of the bismuth silver oxide to the halogen-free water-soluble organic contaminant in the aqueous solution of the halogen-free water-soluble organic contaminant is 1 to 2:0.01 to 0.02.

4. The preparation method according to claim 1, 2 or 3, wherein the mass concentration of the water-soluble organic pollutants in the water solution of the water-soluble organic pollutants without halogen is 40-80 mg/L;

the number of the circulation is more than or equal to 2; the time of each cycle is the same;

the end conditions of the cycle are: the mass concentration of the water-soluble organic pollutants which do not contain halogen elements in the reaction suspension obtained after the oxidative degradation reaction is more than or equal to 95 percent of the mass concentration of the water-soluble organic pollutants in the water solution of the water-soluble organic pollutants which do not contain halogen elements before the oxidative degradation reaction.

5. The preparation method according to claim 1, wherein the mass concentration of the sodium bismuthate dihydrate in the sodium bismuthate suspension is 5-10 g/L;

the mass ratio of the sodium bismuthate dihydrate to the soluble silver salt is 1: 0.5-1.

6. The method according to claim 1, wherein the molar concentration of silver ions in the aqueous silver ion solution is 0.1 to 0.2 mol/L.

7. The preparation method according to claim 6, wherein the mass ratio of the silver bismuthyl carbonate precursor to the silver in the silver ion aqueous solution is (5-10): (11-22).

8. The preparation method according to claim 1, wherein the third mixing is carried out under stirring conditions, wherein the stirring time is 20-24 hours, the stirring temperature is 50-60 ℃, and the stirring speed is 400-600 r/min.

9. The composite visible-light-driven photocatalyst prepared by the preparation method of any one of claims 1 to 8, wherein the chemical composition of the composite visible-light-driven photocatalyst is Ag_n-Bi₂O₂CO₃Said Ag being_n-Bi₂O₂CO₃The molar ratio of the Ag element to the Bi element is 1: 1.5-2.

10. Use of the composite visible-light-driven photocatalyst of claim 9 in photocatalysis.

Technical Field

The invention relates to the technical field of photocatalysts, in particular to a composite visible-light-driven photocatalyst and a preparation method and application thereof.

Background

At present, the development and utilization of solar energy become one of the important methods for eliminating environmental pollutants, and the semiconductor photocatalysis technology which is an important part of the method is expected to become an effective way for solving the problem of environmental pollution, wherein the photocatalytic degradation for eliminating toxic organic pollutants becomes a cheap and feasible way for solving the environmental pollution.

However, it is still difficult to realize efficient and inexpensive conversion and utilization of solar energy by the photocatalytic technology. The main reason is that a series of semiconductor photocatalysts developed by people at present have wider band gaps and only respond in an ultraviolet light range, while the ultraviolet light part accounts for very limited total solar energy, and the solar energy is mainly concentrated in a visible light range. Therefore, the development of the visible light response catalyst is the key for improving the solar energy utilization rate and finally realizing the industrial application of the photocatalysis technology.

Bismuth subcarbonate is a novel material with excellent performance and wide application, and recent research shows that the bismuth subcarbonate has high visible light catalytic activity besides the application of the bismuth subcarbonate in the aspect of medicine, and can completely reveal the corners in the field of visible light catalytic degradation pollution. At present, the main method for synthesizing bismuth oxycarbonate is a hydrothermal method or a crystal nucleus growth method, and the preparation method has high requirements on reaction conditions and reaction equipment or has a slow reaction process. Meanwhile, researches show that the response wavelength of the photocatalyst can be further red-shifted through modification, the main modification method comprises the means of metal ion and nonmetal doping, metal simple substance deposition, heterojunction construction and the like, and the further modified bismuthyl carbonate visible-light photocatalyst generally has a series of advantages of stability, high efficiency, low cost and the like, and has a certain application prospect in the field of photocatalytic degradation of organic pollutants. However, the above modification process, especially the metal simple substance deposition modification, generally requires high-precision control of the deposition process, and the process is complex and difficult to control.

Disclosure of Invention

In view of this, the present invention aims to provide a composite visible-light-driven photocatalyst, and a preparation method and an application thereof, wherein the preparation method provided by the present invention combines preparation of the composite visible-light-driven photocatalyst and degradation of pollutants, and prepares a target composite visible-light-driven photocatalyst while degrading pollutants by using an initially required synthetic material. The preparation method of the composite visible-light-driven photocatalyst provided by the invention is simple and feasible, and can degrade organic pollutants. Moreover, the composite visible light catalyst prepared by the preparation method provided by the invention has excellent visible light catalytic activity.

In order to solve the technical problems, the invention provides the following technical scheme:

the invention provides a preparation method of a composite visible-light-driven photocatalyst, which comprises the following steps:

carrying out first mixing on the sodium bismuthate dihydrate suspension and the soluble silver salt to carry out ion exchange reaction to obtain bismuth silver oxide;

carrying out second mixing on the bismuth silver oxide and the aqueous solution of the halogen-free water-soluble organic pollutant, carrying out solid-liquid separation after an oxidative degradation reaction is carried out, replacing the bismuth silver oxide with the solid-liquid separated solid, and circulating the processes of the second mixing and the solid-liquid separation to obtain a silver bismuthyl carbonate precursor;

and thirdly mixing the silver bismuthyl carbonate precursor and the silver ion aqueous solution to obtain the composite visible-light-driven photocatalyst.

Preferably, the halogen-free water-soluble organic contaminants include one or more of methyl orange, phenylenediamine, bisphenol a, and rhodamine B.

Preferably, the mass ratio of the bismuth silver oxide to the halogen-free water-soluble organic pollutant in the aqueous solution of the halogen-free water-soluble organic pollutant is 1-2: 0.01-0.02.

Preferably, the mass concentration of the water-soluble organic pollutants in the water solution of the water-soluble organic pollutants containing no halogen is 40-80 mg/L;

the number of the circulation is more than or equal to 2; the time of each cycle is the same;

the end conditions of the cycle are: the mass concentration of the water-soluble organic pollutants which do not contain halogen elements in the reaction suspension obtained after the oxidative degradation reaction is more than or equal to 95 percent of the mass concentration of the water-soluble organic pollutants in the water solution of the water-soluble organic pollutants which do not contain halogen elements before the oxidative degradation reaction.

Preferably, the mass concentration of the sodium bismuthate dihydrate in the sodium bismuthate suspension is 5-10 g/L;

the mass ratio of the sodium bismuthate dihydrate to the soluble silver salt is 1: 0.5-1.

Preferably, the molar concentration of the silver ions in the silver ion aqueous solution is 0.1-0.2 mol/L.

Preferably, the mass ratio of the silver bismuthyl carbonate precursor to the silver in the silver ion aqueous solution is (5-10): (11-22).

Preferably, the third mixing is carried out under the condition of stirring, the stirring time is 20-24 hours, the stirring temperature is 50-60 ℃, and the stirring speed is 400-600 r/min.

The invention provides the composite visible-light-driven photocatalyst prepared by the preparation method in the technical scheme, and the chemical composition of the composite visible-light-driven photocatalyst is Ag_n-Bi₂O₂CO₃Said Ag being_n-Bi₂O₂CO₃The molar ratio of the Ag element to the Bi element is 1: 1.5-2.

The invention also provides the application of the composite visible-light-driven photocatalyst in photocatalysis.

Compared with the prior art, the invention has the following technical effects:

the invention provides a preparation method of a composite visible-light-driven photocatalyst, which comprises the following steps: carrying out first mixing on the sodium bismuthate dihydrate suspension and the soluble silver salt to carry out ion exchange reaction to obtain bismuth silver oxide; carrying out second mixing on the bismuth silver oxide and the aqueous solution of the halogen-free water-soluble organic pollutant, carrying out solid-liquid separation after an oxidative degradation reaction is carried out, replacing the bismuth silver oxide with the solid-liquid separated solid, and circulating the processes of the second mixing and the solid-liquid separation to obtain a silver bismuthyl carbonate precursor; and thirdly mixing the silver bismuthyl carbonate precursor and the silver ion aqueous solution to obtain the composite visible-light-driven photocatalyst. According to the preparation method provided by the invention, the bismuth silver oxide is used for oxidizing and degrading water-soluble organic pollutants to obtain the silver bismuthyl carbonate precursor, in the process, the water-soluble organic pollutants are degraded, the bismuth silver oxide is subjected to structural change, the main body becomes bismuth oxycarbonate, and trivalent silver is reduced to elemental precious metal silver, so that a perfect silver bismuthyl carbonate precursor is formed; and thirdly mixing the precursor of the silver bismuthyl carbonate and the silver ion aqueous solution to obtain the visible light catalytic material. The preparation method provided by the invention considers the preparation of the material and the degradation of pollutants, and prepares the target composite visible-light-driven photocatalyst while degrading the pollutants by using the initially required synthetic material. The preparation method provided by the invention effectively combines the preparation and modification of the composite visible-light-driven photocatalyst, and the preparation method is simple and feasible. In addition, the composite visible-light-driven photocatalyst prepared by the preparation method provided by the invention realizes secondary regulation and control of the forbidden bandwidth of bismuth oxycarbonate through silver under the action of noble metal silver, and can promote the improvement of the visible-light-driven photocatalytic efficiency. The results of the examples show that the degradation efficiency of the composite visible-light-driven photocatalyst obtained by the preparation method provided by the invention under the irradiation of visible light on methyl orange, phenylenediamine, bisphenol A and rhodamine B is far higher than that of a commercially available bismuthyl carbonate product.

Drawings

FIG. 1 is a comparative XRD pattern of the feed and product of example 1; 1-sodium bismuthate, 2-bismuth silver oxide, 3-precursor of silver bismuthate carbonate oxide and 4-composite visible light catalyst.

Detailed Description

The invention provides a preparation method of a composite visible-light-driven photocatalyst, which comprises the following steps:

carrying out first mixing on the sodium bismuthate dihydrate suspension and the soluble silver salt to carry out ion exchange reaction to obtain bismuth silver oxide;

carrying out second mixing on the bismuth silver oxide and the aqueous solution of the halogen-free water-soluble organic pollutant, carrying out solid-liquid separation after an oxidative degradation reaction is carried out, replacing the bismuth silver oxide with the solid-liquid separated solid, and circulating the processes of the second mixing and the solid-liquid separation to obtain a silver bismuthyl carbonate precursor;

and thirdly mixing the silver bismuthyl carbonate precursor and the silver ion aqueous solution to obtain the composite visible-light-driven photocatalyst.

In the present invention, all the raw materials are commercially available products well known to those skilled in the art unless otherwise specified.

The bismuth silver oxide is prepared by mixing sodium bismuthate dihydrate suspension and soluble silver salt for the first time and performing ion exchange reaction.

In the invention, the mass concentration of the sodium bismuthate dihydrate in the sodium bismuthate suspension is preferably 5-10 g/L, and more preferably 6.5-8.5 g/L. in the invention, the dispersion medium of the sodium bismuthate suspension is preferably deionized water, the invention has no special requirement on the preparation process of the sodium bismuthate dihydrate suspension, and the operation well known to a person skilled in the art can be adopted.

The invention has no special requirements on the types of the soluble silver salts, and can adopt any water-soluble silver salt. In an embodiment of the invention, the soluble silver salt is silver nitrate.

In the invention, the mass ratio of the soluble silver salt to the sodium bismuthate dihydrate in the suspension is preferably 0.5-1: 1, more preferably 0.75 to 0.9: 1.

In the invention, the first mixing is preferably carried out under stirring conditions, the stirring time is preferably 2-3 min, the stirring speed is preferably 450-600 r/min, more preferably 500-550 r/min, and the stirring is preferably carried out at room temperature.

In the first mixing process, sodium bismuthate dihydrate in the sodium bismuthate suspension and silver ions in the soluble silver salt are subjected to ion exchange reaction to generate black precipitated bismuth silver oxide.

After the ion exchange reaction is finished, solid-liquid separation is preferably carried out on suspension obtained by the ion exchange reaction, and the obtained solid product is bismuth silver oxide. In the present invention, the solid-liquid separation is preferably centrifugation, and the present invention does not require any particular operation for the centrifugation, and may employ an operation known to those skilled in the art.

After the bismuth silver oxide is obtained, the bismuth silver oxide and the aqueous solution of the halogen-free water-soluble organic pollutant are subjected to second mixing, after an oxidative degradation reaction, solid-liquid separation is carried out, the solid subjected to solid-liquid separation replaces the bismuth silver oxide, and the processes of the second mixing and the solid-liquid separation are circulated, so that the silver bismuthyl carbonate precursor is obtained.

In the present invention, the halogen-free water-soluble organic contaminant in the aqueous solution of halogen-free water-soluble organic contaminant preferably includes one or more of methyl orange, phenylenediamine, bisphenol a, and rhodamine B, and more preferably includes methyl orange, phenylenediamine, bisphenol a, or rhodamine B. In the invention, when the halogen-free water-soluble organic pollutants comprise any two of methyl orange, phenylenediamine, bisphenol A and rhodamine B, the mass ratio is preferably 1-2: 1 to 2. When the water-soluble organic pollutants containing no halogen comprise more than three of methyl orange, phenylenediamine, bisphenol A and rhodamine B, the invention has no special requirements on the mass ratio of the specific substances and can adopt any ratio.

In the invention, the mass concentration of the water-soluble organic pollutants containing no halogen in the water solution of the water-soluble organic pollutants containing no halogen is preferably 40-80 mg/L.

In the invention, the mass ratio of the bismuth silver oxide to the halogen-free water-soluble organic pollutant in the aqueous solution of the halogen-free water-soluble organic pollutant is preferably 1-2: 0.01-0.02, and more preferably 1.2-1.5: 0.012-0.015.

In the present invention, the second mixing is preferably performed under stirring conditions, the stirring speed is preferably 450 to 600r/min, and more preferably 500 to 550r/min, the stirring is preferably performed at room temperature, and the stirring is preferably performed at room temperature.

In the invention, the bismuth silver oxide has strong oxidizing property, when the bismuth silver oxide and the aqueous solution of the halogen-free water-soluble organic pollutant are subjected to second mixing, the halogen-free water-soluble organic pollutant is oxidized and degraded by the bismuth silver oxide, and the bismuth silver oxide is subjected to structural change in the process of oxidative degradation, so that the main body becomes bismuth oxycarbonate and trivalent silver is reduced into elemental noble metal silver, thereby forming a silver bismuth oxycarbonate precursor.

In the invention, the solid-liquid separation is preferably centrifugation, the acceleration of the centrifugation is preferably 6000G, and the time of the centrifugation is preferably 15-30 min.

In the invention, the number of the circulation is preferably more than or equal to 2, and the time of each circulation is the same; the end conditions of the cycle are: the mass concentration of the water-soluble organic pollutants which do not contain halogen elements in the reaction suspension obtained after the oxidative degradation reaction is more than or equal to 95 percent of the mass concentration of the water-soluble organic pollutants in the water solution of the water-soluble organic pollutants which do not contain halogen elements before the oxidative degradation reaction. In the present invention, the 1 st cycle termination conditions are preferably: the mass concentration of the water-soluble organic pollutants which do not contain halogen elements in the reaction suspension obtained after the oxidative degradation reaction is less than or equal to 90% of the mass concentration of the water-soluble organic pollutants in the water solution of the water-soluble organic pollutants which do not contain halogen elements before the oxidative degradation reaction.

In the present invention, the mass concentration of the halogen-free water-soluble organic contaminant in the aqueous solution of the halogen-free water-soluble organic contaminant is detected by liquid chromatography.

After the circulation is finished, the solid precursor is preferably washed and subjected to solid-liquid separation in sequence to obtain the silver bismuthyl carbonate precursor. In the present invention, the washing preferably includes a first washing, a second washing and a third washing, the detergent of the first washing is preferably water, more preferably deionized water, the detergent of the second washing is preferably ethanol, the detergent of the third washing is preferably n-hexane, the number of times of the first washing, the second washing and the third washing is preferably 1, and the time is preferably 5 min; the first washing, the second washing and the third washing are preferably performed under the condition of sonication. In the invention, the solid-liquid separation is preferably centrifugation, the acceleration of the centrifugation is preferably 6000G, and the time of the centrifugation is preferably 15-30 min. In the embodiment of the present invention, the washing and solid-liquid separation are preferably performed in an oxygen-free glove box.

According to the invention, through washing and solid-liquid separation, water-soluble organic pollutants which do not participate in oxidative degradation reaction and do not contain halogen elements on the surface of the silver bismuthyl carbonate precursor are removed, so that the influence on the subsequent preparation steps is reduced.

After the silver bismuth subcarbonate precursor is obtained, the silver bismuth subcarbonate precursor and a silver ion aqueous solution are subjected to third mixing to obtain the composite visible light catalyst.

In the invention, the molar concentration of the silver ions in the silver ion aqueous solution is preferably 0.1-0.2 mol/L, and more preferably 0.12-0.18 mol/L.

In the invention, the mass ratio of the silver bismuthyl carbonate precursor to the silver ion aqueous solution is preferably (5-10): (11-22), more preferably (6-8): (12-21).

In the present invention, the silver ions in the aqueous silver ion solution are preferably provided by a soluble silver salt; the present invention has no particular requirement on the kind of the soluble silver salt. In an embodiment of the present invention, the aqueous silver ion solution is an oxygen-free aqueous silver ion solution.

In the invention, the third mixing is preferably carried out under the condition of stirring, the stirring time is preferably 20-24 h, more preferably 21-22 h, the stirring temperature is preferably 50-60 ℃, more preferably 53-58 ℃, and the stirring speed is preferably 400-600 r/min, more preferably 450-550 r/min. In the present invention, the third mixing is preferably performed in an oxygen-free environment, and in an embodiment of the present invention, the third mixing is performed in an oxygen-free glove box.

After the third mixing is completed, the mixed liquid obtained after the third mixing is preferably subjected to solid-liquid separation to obtain the composite visible-light-driven photocatalyst. In the invention, the solid-liquid separation is preferably centrifugation, the acceleration of the centrifugation is preferably 6000G, and the time of the centrifugation is preferably 15-30 min. In the present invention, the solid-liquid separation is preferably carried out in an oxygen-free glove box.

The invention provides the composite visible-light-driven photocatalyst prepared by the preparation method in the technical scheme, and the chemical composition of the composite visible-light-driven photocatalyst is Ag_n-Bi₂O₂CO₃Said Ag being_n-Bi₂O₂CO₃The molar ratio of the Ag element to the Bi element is 1: 1.5-2.

The invention also provides the application of the composite visible-light-driven photocatalyst in photocatalysis.

In the invention, the application of the composite visible-light-driven photocatalyst in photocatalysis is preferably the application of the composite visible-light-driven photocatalyst in degrading halogen-free water-soluble organic pollutants, and in the invention, the specific application is preferably as follows: and mixing the composite visible light catalyst and the water solution of the halogen-free water-soluble organic pollutant, and carrying out photocatalytic reaction under the irradiation of visible light.

In the invention, the mass ratio of the composite visible light catalyst to the halogen-free water-soluble organic pollutant is preferably 0.5-1: 0.01-0.06, the mass concentration of the halogen-free water-soluble organic pollutant in the halogen-free water-soluble organic pollutant aqueous solution is preferably 10-60 mg/L, the intensity of visible light is preferably 400W, the mixing is preferably carried out under the condition of stirring, the stirring time is preferably 20-45 min, and the stirring speed is preferably 450-500 r/min.

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.