阅读说明：本技术 BMO/Bi2S3复合光催化剂及其制备方法与在还原六价铬中的应用 (BMO/Bi2S3Composite photocatalyst, preparation method thereof and application thereof in reduction of hexavalent chromium ) 是由 路建美 陈冬赟 于 2020-04-16 设计创作，主要内容包括：本发明一种BMO/Bi<Sub>2</Sub>S<Sub>3</Sub>复合光催化剂及其制备方法与应用,以Na<Sub>2</Sub>MoO<Sub>2·</Sub>2H<Sub>2</Sub>O、NaCl为原料,采用水热反应制备MoO<Sub>3</Sub>纳米棒；以MoO<Sub>3</Sub>为牺牲模板和钼源,Bi(NO<Sub>3</Sub>)<Sub>3·</Sub>5H<Sub>2</Sub>O为原料,通过回流工艺制备Bi<Sub>2</Sub>MoO<Sub>6</Sub>纳米框架；以Bi<Sub>2</Sub>MoO<Sub>6</Sub>为前体、Na<Sub>2</Sub>S为硫化剂,水热反应制备BMO/Bi<Sub>2</Sub>S<Sub>3</Sub>复合光催化剂；将BMO/Bi<Sub>2</Sub>S<Sub>3</Sub>复合光催化剂置于含六价铬水体中,避光搅拌后进行光照,完成水体中六价铬的降解。BMO/Bi<Sub>2</Sub>S<Sub>3</Sub>催化剂表现出优异的性能,一方面是因为该催化剂的吸附能力极强,可以快速地将六价铬聚集在催化剂表面；另一方面得益于其良好的框架结构,打开光源后催化剂吸收可见光,电子和空穴迅速向不同方向转移,有效地抑制电子和空穴的复合,使得对水体中六价铬的降解效率大幅提高。(The invention relates to a BMO/Bi 2 S 3 Composite photocatalyst, preparation method and application thereof, and preparation method and application thereof 2 MoO 2· 2H 2 O, NaCl is used as raw material to prepare MoO by hydrothermal reaction 3 A nanorod; with MoO 3 For sacrificial template and molybdenum source, Bi (NO) 3 ) 3· 5H 2 Preparing Bi by using O as a raw material through a reflux process 2 MoO 6 A nano-framework; with Bi 2 MoO 6 Is a precursor, Na 2 S is a vulcanizing agent, and BMO/Bi is prepared by hydrothermal reaction 2 S 3 A composite photocatalyst; mixing BMO/Bi 2 S 3 The composite photocatalyst is placed in a hexavalent chromium-containing water bodyAnd (4) in the middle, illuminating after stirring in a dark place to complete the degradation of the hexavalent chromium in the water body. BMO/Bi 2 S 3 The catalyst shows excellent performance, on one hand, because the catalyst has extremely strong adsorption capacity, hexavalent chromium can be rapidly gathered on the surface of the catalyst; on the other hand, due to the good frame structure, the catalyst absorbs visible light after the light source is turned on, electrons and holes are rapidly transferred to different directions, and the recombination of the electrons and the holes is effectively inhibited, so that the degradation efficiency of hexavalent chromium in the water body is greatly improved.)

1. BMO/Bi₂S₃Composite photocatalyst, characterized in that said BMO/Bi₂S₃The preparation method of the composite photocatalyst comprises the following steps:

(1) with Na₂MoO_2·2H₂O, NaCl is used as raw material to prepare MoO by hydrothermal reaction₃A nanorod;

(2) with MoO₃For sacrificial template and molybdenum source, Bi (NO)₃)_3·5H₂Preparing Bi by using O as a raw material through a reflux process₂MoO₆A nano-framework;

(3) with Bi₂MoO₆Is a precursor, Na₂S is a vulcanizing agent, and BMO/Bi is prepared by hydrothermal reaction₂S₃A composite photocatalyst is provided.

2. The BMO/Bi of claim 1₂S₃The composite photocatalyst is characterized in that in the step (1), Na is added₂MoO_2·2H₂The mass ratio of O to NaCl is 1.9-2.1: 1; the temperature of the hydrothermal reaction is 150-200 ℃, and the reaction time is 18-24 h.

3. The BMO/Bi of claim 2₂S₃Composite photocatalyst, its special featureCharacterized in that in the step (1), the temperature of the hydrothermal reaction is 180 ℃, and the reaction time is 20 h.

4. The BMO/Bi of claim 1₂S₃The composite photocatalyst is characterized in that in the step (2), MoO₃And Bi (NO)₃)_3·5H₂The mass ratio of O is 1: 6.5-7.2; the temperature of the reflux reaction is 110-130 ℃, and the reaction time is 4-10 h.

5. The BMO/Bi of claim 4₂S₃The composite photocatalyst is characterized in that in the step (2), the temperature of the reflux reaction is 120 ℃, and the reaction time is 4-10 hours.

6. The BMO/Bi of claim 1₂S₃The composite photocatalyst is characterized in that in the step (3), Bi is fed₂MoO₆And Na₂The mass ratio of S is 1: 5.8-6.2; the temperature of the hydrothermal reaction is 120-180 ℃, and the reaction time is 0.5-6 h.

7. A method for degrading hexavalent chromium in a water body comprises the following steps:

(1) with Na₂MoO_2·2H₂O, NaCl is used as raw material to prepare MoO by hydrothermal reaction₃A nanorod;

(2) with MoO₃For sacrificial template and molybdenum source, Bi (NO)₃)_3·5H₂Preparing Bi by taking O as raw material through reflux reaction₂MoO₆A nano-framework;

(3) with Bi₂MoO₆Is a precursor, Na₂S is a vulcanizing agent, and BMO/Bi is prepared by hydrothermal reaction₂S₃A composite photocatalyst;

(4) mixing BMO/Bi₂S₃The composite photocatalyst is placed in a water body containing hexavalent chromium, and is illuminated after being stirred away from light, so that the degradation of the hexavalent chromium in the water body is completed.

8. The method of degrading hexavalent chromium in the body of water of claim 7 wherein the illumination is with a 300W xenon lamp.

9. The BMO/Bi according to claim 1₂S₃The application of the composite photocatalyst in degrading hexavalent chromium in water.

10. BMO/Bi₂S₃The preparation method of the composite photocatalyst is characterized by comprising the following steps:

(1) with Na₂MoO_2·2H₂O, NaCl is used as raw material to prepare MoO by hydrothermal reaction₃A nanorod;

(2) with MoO₃For sacrificial template and molybdenum source, Bi (NO)₃)_3·5H₂Preparing Bi by using O as a raw material through a reflux process₂MoO₆A nano-framework;

(3) with Bi₂MoO₆Is a precursor, Na₂S is a vulcanizing agent, and BMO/Bi is prepared by hydrothermal reaction₂S₃A composite photocatalyst is provided.

Technical Field

The invention belongs to the technical field of inorganic functional materials, and particularly relates to a BMO/Bi with a cross frame structure under the synergistic action of adsorption and photocatalysis₂S₃A preparation method of the composite catalyst and application thereof in degrading and removing hexavalent chromium in water.

Background

There are many methods for treating hexavalent chromium in wastewater, and the methods are commonly known as an adsorption method, a membrane separation method, an ion exchange method, an electrodialysis method, a photocatalytic method and the like. Taking the adsorption method as an example, common adsorbents include activated carbon, clay, polymer resin and the like, and have the advantage of quickly removing hexavalent chromium in water. However, the adsorption method also has fatal disadvantages such as the adsorbent fails after reaching the saturated adsorption capacity; desorption is easy to occur, and secondary pollution is caused. In terms of photocatalysis technology, it is a promising, low-cost, environment-purifying green technology. The photocatalytic reduction method has the advantages of low energy consumption, no secondary pollution and the like, but the solar energy utilization efficiency is low in practical application; poor selective adsorption, potentially forming highly toxic intermediates; the stability is poor; the problems of high recombination rate of electron hole pairs and the like are difficult to completely meet the increasing energy requirements and the increasingly serious environmental pollution requirements. Therefore, the research of the method for degrading and removing chromium wastewater with low cost, high efficiency and energy saving has become a hot problem of environmental research.

Disclosure of Invention

The invention aims to provide an inorganic functional material capable of efficiently adsorbing and photocatalytically degrading hexavalent chromium in a water body.

In order to achieve the purpose, the invention adopts the following specific technical scheme:

BMO/Bi₂S₃The composite photocatalyst and the preparation method thereof comprise the following steps:

(1) with Na₂MoO_2·2H₂O, NaCl is prepared by hydrothermal reactionMoO₃A nanorod;

(2) with MoO₃For sacrificial template and molybdenum source, Bi (NO)₃)_3·5H₂Preparing Bi by using O as a raw material through a reflux process₂MoO₆A nano-framework;

(3) with Bi₂MoO₆Is a precursor, Na₂S is a vulcanizing agent, and BMO/Bi is prepared by hydrothermal reaction₂S₃A composite photocatalyst is provided.

A method for degrading hexavalent chromium in a water body comprises the following steps:

(1) with Na₂MoO_2·2H₂O, NaCl is used as raw material to prepare MoO by hydrothermal reaction₃A nanorod;

(2) with MoO₃For sacrificial template and molybdenum source, Bi (NO)₃)_3·5H₂Preparing Bi by taking O as raw material through reflux reaction₂MoO₆A nano-framework;

(3) with Bi₂MoO₆Is a precursor, Na₂S is a vulcanizing agent, and BMO/Bi is prepared by hydrothermal reaction₂S₃A composite photocatalyst;

(4) mixing BMO/Bi₂S₃The composite photocatalyst is placed in a water body containing hexavalent chromium, and is illuminated after being stirred away from light to complete the degradation of the hexavalent chromium in the water body, for example, a 300W xenon lamp (lambda is more than or equal to 400 nm) is used for illuminating a reactor.

The invention adopts an anion exchange method to convert Bi into Bi₂S₃The nano-sheet grows in situ in Bi₂MoO₆Preparing n-n type BMO/Bi on a nano-framework₂S₃The composite photocatalyst has a cross frame structure.

In the technical scheme, the raw material Na in the step (1)₂MoO_2·2H₂The mass ratio of O to NaCl is 1.9-2.1: 1, preferably 2: 1. Preferably, the two raw materials are dissolved in water, and ultrasonic treatment is carried out for 10-30 min; the temperature of the hydrothermal reaction is 150-200 ℃, preferably 180 ℃, and the reaction time is 18-24 hours, preferably 20 hours; naturally cooling to room temperature after the reaction is finished, washing the product with deionized water and ethanol in sequence, and then dryingDrying at 70-80 ℃, preferably 80 ℃ to prepare MoO₃And (4) nanorods.

In the technical scheme, the raw material MoO in the step (2)₃And Bi (NO)₃)_3·5H₂The mass ratio of O is 1: 6.5-7.2, preferably 1: 6.79; preferably, the two raw materials are dissolved in water, and the ultrasonic treatment is carried out for 10-30 min to completely dissolve the raw materials; the temperature of the reflux reaction is 110-130 ℃, the preferred temperature is 120 ℃, and the reaction time is 4-10 hours, the preferred time is 6 hours; naturally cooling to room temperature after the reaction is finished, washing the product with deionized water and ethanol in sequence, and drying at 60-80 ℃, preferably 60 ℃ to prepare Bi₂MoO₆And (3) obtaining the product. The reaction time in step (2) is preferably selected according to the invention, so that the formation of Bi having a cross structure is facilitated₂MoO₆And (4) a nano framework, which provides a good support structure for the reaction of the step (3).

In the above technical scheme, raw material Bi in step (3)₂MoO₆And Na₂The mass ratio of S is 1: 5.8-6.2, preferably 1: 6; preferably, Na is added₂S solution is slowly dropped with Bi₂MoO₆Stirring for 30-60 min in a dispersion system to uniformly mix; the temperature of the hydrothermal reaction is 120-180 ℃, the preference is 150 ℃, and the reaction time is 0.5-6 h; naturally cooling to room temperature after the reaction is finished, washing the product with deionized water and ethanol in sequence, and drying at 60-80 ℃, preferably 60 ℃, thereby preparing the BMO/Bi₂S₃A composite photocatalytic material. The reaction time of step (2) is preferably selected according to the invention, so that the formation of tightly crossed BMO/Bi is favored₂S₃A heterostructure.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

1. the BMO/Bi is obtained by adopting a simple and easy-to-operate solvothermal method and an anion exchange method₂S₃The composite photocatalyst has simple preparation process and rich material sources, is beneficial to reducing the preparation cost and is easy to realize large-scale production; bi₂MoO₆The band gap value is about 2.6 eV, and the high-efficiency and stable visible lightA photocatalyst; the invention uses MoO₃Is used as a sacrificial template to prepare Bi₂MoO₆The nano-framework structure has a larger specific surface area and more nano-channels. Meanwhile, BMO/Bi is successfully prepared by adopting an anion exchange method₂S₃Composite photocatalyst of Bi-retained₂MoO₆The size of the composite material can be regulated and controlled while the nano framework structure is adopted, and Bi is added₂S₃The nano-sheet grows uniformly in Bi₂MoO₆On the frame, the separation efficiency of the photoproduction electrons and the photoproduction holes is further improved. Greatly enhances the capability of photocatalytic reduction of hexavalent chromium by gradually modifying the composite material, and shows that the composite material has Bi which is single₂MoO₆And Bi₂S₃Stronger adsorption activity and higher photocatalytic activity.

2. BMO/Bi of the present invention₂S₃The composite photocatalyst promotes Bi₂MoO₆Nano-framework and Bi₂S₃The separation efficiency of photo-generated carriers in the nanosheets effectively prolongs the survival life of photo-generated charges and promotes the photocatalytic activity of the photo-generated charges; can inhibit the recombination of electrons and holes and further improve the degradation efficiency of the chromium-containing wastewater. More importantly, Bi₂MoO₆The nano-framework has stable structure and is beneficial to the recovery and recycling of the photocatalyst.

3. The invention overcomes the defect of the traditional adsorption method for treating the chromium-containing wastewater, and adopts the photocatalysis technology to convert hexavalent chromium in the chromium wastewater into trivalent chromium which has low toxicity and is easy to generate precipitates by using a semiconductor photocatalyst under the condition of not adding an adsorbent or a reducing agent by using a solar light source or an artificial light source, thereby greatly reducing the treatment cost and the energy consumption.

Drawings

FIG. 1 is MoO₃、Bi₂MoO₆And BMO/Bi₂S₃Scanning electron microscope images and transmission electron microscope images of;

FIG. 2 shows Bi₂MoO₆、Bi₂S₃And BMO/Bi₂S₃An effect graph for adsorbing hexavalent chromium in a water body;

FIG. 3 shows Bi₂MoO₆、Bi₂S₃And BMO/Bi₂S₃An effect graph of degrading hexavalent chromium in a water body by photocatalysis;

FIG. 4 shows Bi₂MoO₆、Bi₂S₃And BMO/Bi₂S₃An effect diagram of direct photocatalytic degradation of hexavalent chromium in a water body;

FIG. 5 shows BMO/Bi₂S₃-1 a cyclic effect of degrading hexavalent chromium in a water body.

Detailed Description

The invention discloses a BMO/Bi₂S₃The preparation method of the composite photocatalyst comprises the following steps:

(1) with Na₂MoO_2·2H₂O, NaCl is used as raw material to prepare MoO by hydrothermal reaction₃A nanorod;

(2) with MoO₃For sacrificial template and molybdenum source, Bi (NO)₃)_3·5H₂Preparing Bi by using O as a raw material through a reflux process₂MoO₆A nano-framework;

(3) with Bi₂MoO₆Is a precursor, Na₂S is a vulcanizing agent, and BMO/Bi is prepared by hydrothermal reaction₂S₃A composite photocatalyst is provided.

The present invention will be further described with reference to the following examples, in which the experiments of hexavalent chromium adsorption and photocatalytic degradation by the catalyst are conducted by conventional methods.