阅读说明：本技术 一种含异质结负载粘土纳米光催化材料的制备方法 (Preparation method of heterojunction-containing supported clay nano photocatalytic material ) 是由 史慧贤 杨树蓉 马建超 庞进 张晓鹏 王雨昕 于 2019-09-18 设计创作，主要内容包括：本发明属纳米光催化材料技术领域,提供一种含异质结负载粘土纳米光催化材料的制备方法。由AgCl、AgX、粘土按一定比例制成；AgX中X为Br或I；粘土为膨润土、硅藻土或凹凸棒土。先将干燥粘土加入到NaCl溶液中,搅拌下逐滴加入AgNO<Sub>3</Sub>溶液,得二元AgCl/粘土催化剂；缓慢滴加KI(NaBr)溶液,继续搅拌,溶液离心分离,去离子水洗涤烘干,得光催化材料AgX-AgCl/粘土。利用卤化银和氯化银拥有匹配的能级水平,通过构建卤化银氯化银异质结,负载于矿土材料粘土上,有效抑制氯化银易团聚、光腐蚀与易分解的缺点,提高其在光照下的稳定性及光催化活性。制备方法简单,成本较低,能在可见光光催化降解有机污染物。(The invention belongs to the technical field of nano photocatalytic materials, and provides a preparation method of a heterojunction-containing clay-loaded nano photocatalytic material. Prepared by AgCl, AgX and clay according to a certain proportion; x in AgX is Br or I; the clay is bentonite, diatomite or attapulgite. Firstly, adding dry clay into NaCl solution, and dropwise adding AgNO while stirring 3 The solution is prepared by mixing a solvent and a solvent,obtaining a binary AgCl/clay catalyst; slowly dripping KI (NaBr) solution, continuously stirring, centrifugally separating the solution, washing with deionized water and drying to obtain the photocatalytic material AgX-AgCl/clay. The silver halide and the silver chloride have matched energy level levels, and the silver halide-silver chloride heterojunction is constructed and loaded on the clay of the mineral soil material, so that the defects of easy aggregation, photo-corrosion and easy decomposition of the silver chloride are effectively inhibited, and the stability and the photocatalytic activity of the silver chloride under illumination are improved. The preparation method is simple, has low cost, and can degrade organic pollutants under the catalysis of visible light.)

1. A nanometer photocatalysis material containing heterojunction loading clay is characterized in that: the material is prepared from the following raw materials in percentage by weight: AgCl: 5% -40%; AgX: 4% -16%; clay: 54% -91%; wherein: x in AgX is Br or I; the clay is bentonite, diatomite or attapulgite.

2. The method for preparing the heterojunction-containing supported clay nano-photocatalytic material as described in claim 1, is characterized in that:

(1) AgCl/clay: weighing clay according to a certain proportion, mixing the clay in NaCl solution, and dripping AgNO under the condition of stirring₃Stirring the solution at room temperature for 4-6 hours, and washing AgCl/clay with deionized water until the pH value of a washing solution is 6-7;

(2) preparation of the heterojunction-containing supported nano photocatalytic material AgX-AgCl/clay: dropwise adding a KI or NaBr solution into the prepared AgCl/clay solution; stirring for 10-20 min, then centrifugally separating the obtained solution, washing with deionized water until the pH value of a washing liquid is 6-7, and drying in a drying box to obtain a nano photocatalytic material AgX-AgCl/clay; wherein: KI or NaBr with AgNO₃The mass ratio of the components is as follows: 0.01-0.5: 0.1 to 1.0.

3. The method for preparing the heterojunction-containing supported clayey clay nano-photocatalytic material according to claim 2, wherein: NaCl and AgNO in step (1)₃The mass ratio of the components is as follows: 1.0-2.0: 0.1-1.0.

4. The method for preparing the heterojunction-containing supported clayey-soil nano photocatalytic material according to claim 2 or 3, wherein: the specific preparation method of AgCl/clay in the step (1) comprises the following steps:

A. 1.0g of dry clay was weighed out and uniformly dispersed in 50mL of deionized water, 50mL of 0.3M NaCl solution was added dropwise with stirring, and then 100mL of 0.05M AgNO was added dropwise₃Solutions, i.e. NaCl and AgNO₃The weight ratio of the components is 1.4: 0.8;

B. mixing the solution containing clay and NaCl with AgNO₃After the solution was mixed, stirring was continued at room temperature for 5 hours.

5. The method for preparing a heterojunction-containing supported clay nano-photocatalytic material according to claim 4, wherein: AgNO₃The dropping speed of (2) to (10) drops per second.

6. The method for preparing a heterojunction-containing supported clay nano-photocatalytic material according to claim 5, wherein: in the step (2), the dropping speed of the KI or NaBr solution is 2-10 drops per second; the concentration of the KI or NaBr solution is 0.01-0.05M; KI and AgNO₃The mass ratio of the components is 0.331: 0.796; NaBr and AgNO₃The mass ratio of (A) to (B) is 0.205: 0.796.

7. The method for preparing a heterojunction-containing supported clay nano-photocatalytic material according to claim 2, wherein: the stirring time in the step (2) is 15 min; and (3) the drying temperature of the drying box in the step (2) is 60-80 ℃.

8. The use of the nano photocatalytic material AgX-AgCl/clay containing heterojunction loading clay according to claim 1 in degrading p-hydroxybenzoate esters, organic dyes and phenols.

9. The application of the heterojunction-containing supported clay nano photocatalytic material in degrading organic matters according to claim 8 is characterized in that: the specific application method comprises the following steps: taking methylene blue, phenol or methyl p-hydroxybenzoate with the concentration of 20 mg/L as a substrate, taking 0.1g of a heterojunction-containing clay-loaded nano photocatalytic material, using a xenon lamp with a light source of 300W, and filtering out ultraviolet light by using an optical filter, wherein the reaction time is 40-120 min.

Technical Field

The invention belongs to the technical field of nano photocatalytic materials, and particularly relates to a preparation method of a heterojunction-containing clay-loaded nano photocatalytic material.

Background

With the continuous development of industrialization and modernization, the problem of water pollution is getting more and more serious. Compared with the traditional water pollution treatment method, the photocatalysis method is green and environment-friendly and has no secondary pollution. The photocatalyst material with good performance is the key for treating water body pollution by a photocatalysis method. At present, most of photocatalysts have photocatalytic activity only under ultraviolet light, and have the defects of narrow photoresponse range, low quantum efficiency and the like. In order to widen the photoresponse range, various methods have been tried to prepare novel visible light photocatalytic materials. In recent years, AgX is increasingly applied to the field of preparation of photocatalysts due to its unique photosensitivity. In a patent of silver halide/silicon titanium aerogel ternary composite photocatalyst and a preparation method thereof (application number 201610658028.3) applied by the institute of new materials of academy of sciences in Shandong province, a multilevel semiconductor composite photocatalyst is prepared by using a silicon titanium aerogel block material as a carrier of silver halide nanoparticles; the Huainan academy of academic department, namely a preparation method of a silver halide heterostructure photocatalyst (application number 201210540641.7), discloses and reports that silver halide is loaded on a silicon dioxide carrier through a deposition-precipitation method, and the formed heterojunction nano composite material well improves the photocatalytic activity of the silver halide.

In summary, in the prior art, the multistage load-type material is mainly prepared by coupling AgX and a semiconductor, so that the application of various semiconductor materials increases the industrialization cost, and is not beneficial to industrial popularization; and the silver halide is easy to corrode by light, easy to agglomerate, poor in stability and difficult to recover. Therefore, the problem can be better solved by preparing the supported photocatalyst by loading AgX on a carrier with good adsorbability and large specific surface area. The bentonite, the diatomite, the attapulgite and other clays are used as mineral materials with low price and rich raw materials, so that on one hand, the immobilization of active components of the catalyst can be realized, the problems of poor agglomeration stability and difficult recovery of AgX are solved, and photo-generated electrons can be captured by utilizing the interlayer cation capture capacity of the bentonite, the recombination of electrons and holes is inhibited, and the free radical oxidation reaction of the holes is strengthened; on the other hand, the bentonite, the diatomite, the attapulgite and other clays have larger surface areas and better adsorptivity, can adsorb pollutant molecules on the surface of the catalyst, increase the effective contact area of the catalyst and the pollutant molecules directly, and improve the activity of the catalyst. The contact between AgX and organic mineral soil can effectively reduce the contact potential barrier between the photocatalytic material and organic pollutant molecules, and improve the photocatalytic degradation efficiency of organic matters. At present, the application of the AgX and clay heterojunction-containing supported nano material in the aspect of photocatalysis is not reported.

Disclosure of Invention

The invention aims to provide a preparation method and application of a heterojunction-containing supported clay nano photocatalytic material, wherein the heterojunction-containing supported nano photocatalytic material is a novel photocatalyst material formed by forming a heterojunction between silver halide AgX (Br, I) -silver chloride (AgCl) and loading the heterojunction-containing supported clay nano photocatalytic material on bentonite (diatomite and attapulgite). The material can degrade organic pollutants by photocatalysis under visible light.

The technical scheme includes that the heterojunction-containing clay-loaded nano photocatalytic material is prepared from the following raw materials, by weight, 5.0% of AgCl ~ 40, 4.0% of AgX ~ 16.0.0 and 54.0% of clay ~ 91.0.0, wherein X in AgX is Br or I, and the clay is bentonite, diatomite or attapulgite.

The preparation method of the heterojunction-containing supported clay nano photocatalytic material comprises the following steps:

(1) system for makingPreparation of AgCl/Clay: weighing clay according to a certain proportion, mixing the clay in NaCl solution, and dripping AgNO under the condition of stirring₃Stirring the solution at room temperature for 4-6 hours, and washing AgCl/clay with deionized water until the pH value of a washing solution is 6-7;

(2) preparation of the heterojunction-containing supported nano photocatalytic material AgX-AgCl/clay: dropwise adding a KI or NaBr solution into the prepared AgCl/clay solution; stirring for 10-20 min, then centrifugally separating the obtained solution, washing with deionized water until the pH value of a washing liquid is 6-7, and drying in a drying box to obtain a nano photocatalytic material AgX-AgCl/clay; wherein: KI or NaBr with AgNO₃The mass ratio of the components is as follows: 0.01-0.5: 0.1 to 1.0.

NaCl and AgNO in step (1)₃The mass ratio of the components is as follows: 1.0-2.0: 0.1-1.0. The specific preparation method of AgCl/clay in the step (1) comprises the following steps:

A. 1.0g of dry clay was weighed out and uniformly dispersed in 50mL of deionized water, 50mL of 0.3M NaCl solution was added dropwise with stirring, and then 100mL of 0.05M AgNO was added dropwise₃Solutions, i.e. NaCl and AgNO₃The weight ratio of the components is 1.4: 0.8;

B. mixing the solution containing clay and NaCl with AgNO₃After the solution was mixed, stirring was continued at room temperature for 5 hours.

The method for preparing a heterojunction-containing supported clay nano-photocatalytic material according to claim 5, wherein: AgNO₃The dropping speed of (2) to (10) drops per second.

In the step (2), the dropping speed of the KI or NaBr solution is 2-10 drops per second; the concentration of the KI or NaBr solution is 0.01-0.05M; KI and AgNO₃The mass ratio of the components is 0.331: 0.796; NaBr and AgNO₃The mass ratio of (A) to (B) is 0.205: 0.796. The stirring time in the step (2) is 15 min; and (3) the drying temperature of the drying box in the step (2) is 60-80 ℃.

Taking methylene blue, phenol or methyl p-hydroxybenzoate with the concentration of 20 mg/L as a substrate, taking 0.1g of a heterojunction-containing clay-loaded nano photocatalytic material, using a xenon lamp with a light source of 300W, and filtering out ultraviolet light by using an optical filter, wherein the reaction time is 40-120 min.

The supported nanometer photocatalytic material AgX-AgCl/clay containing the heterojunction is used as a photocatalyst, is particularly suitable for being used as a photocatalyst for degrading organic matters in the field of environmental protection, shows strong photocatalytic performance in the aspect of being applied to degrading phenol substances such as p-hydroxybenzoate esters, organic dyes and phenol, and has a wide application range.

AgCl has excellent photocatalytic activity, but the rate of photon-generated electron hole recombination is high, so that the utilization rate of photon-generated carriers is not high, and the stability is poor due to easy occurrence of photodecomposition and photo corrosion; the AgI (AgBr) and AgCl form a heterojunction structure, so that the transfer of photoproduction electrons of the composite material is accelerated, and the recombination of photoproduction electron-hole pairs is inhibited, so that the photocatalysis performance of the composite material is enhanced, the photolysis and corrosion of AgCl can be inhibited, and the stability of the composite material is effectively improved. AgX (Br, I) -AgCl/clay has obvious adsorption effect on organic pollutants in a dark reaction stage, because the AgX (Br, I) and the AgCl change the surface appearance of clay bentonite (diatomite and attapulgite), the specific surface area of the clay is increased, and the adsorption capacity of the clay is enhanced.

The clay is a carrier for reaction and can further increase the adsorption performance of the material, and AgI (AgBr) is formed on the surface of AgCl by KI (NaBr) solution through ion exchange, so that the photocatalytic performance and the stability of the AgCl are effectively enhanced.

According to the invention, AgCl is loaded on the surface of clay, and the developed pore structure of the clay is utilized, so that the activity of the catalyst is effectively distributed, and the defect of easy agglomeration of AgCl is effectively inhibited. The flow of photoproduction electrons can be effectively accelerated by utilizing a heterojunction structure formed between AgX (Br, I) and AgCl, and the separation of electrons and cavities is promoted, so that the photocatalytic activity is improved, the existence of AgX (Br, I) also effectively inhibits the photo corrosion and decomposition of AgCl, the stability of AgCl under illumination is ensured, and the absorption of the AgCl to visible light is effectively improved.

The preparation process of the supported nanometer photocatalytic material AgX (Br, I) -AgCl/clay containing the heterojunction is simple, and in addition, the composite catalyst can also reduce the consumption of noble metal silver, and has the advantages of low cost and short preparation time.

The heterojunction-containing supported nano photocatalytic material AgX (Br, I) -AgCl/clay provided by the invention has the advantages of wide photoresponse range, high quantum efficiency and the like, and can be applied to the field of environmental protection, particularly to photocatalytic degradation of organic pollutants in water.

Drawings

FIG. 1 is a graph of the degradation kinetics of methylene blue.

FIG. 2 is an SEM image of AgI-AgCl/bentonite.

Detailed Description

The present invention is further illustrated by, but is not limited to, the following examples.