CN103263910A - Bismuth vanadate-graphene composite photocatalyst, and preparation and application thereof - Google Patents

Abstract

The present invention proposes a bismuth vanadate-graphene composite photocatalyst and its preparation and application, aiming to provide a bismuth vanadate-graphene composite photoresponse to visible light with low production cost, short preparation cycle and high photocatalytic activity The photocatalyst comprises the following production steps: the first step: preparing graphene oxide colloidal suspension; the second step: preparing bismuth vanadate-graphene oxide composite with bismuth nitrate, ammonium metavanadate and graphene oxide colloidal suspension; The third step: the product obtained in the second step is placed in a microwave reactor to prepare a bismuth vanadate-graphene composite; the fourth step: the product obtained in the third step is centrifuged, washed with twice distilled water, and dried. The bismuth vanadate-graphene composite photocatalyst proposed by the present invention has high photocatalytic activity and low production cost; a method for preparing bismuth vanadate-graphene composite photocatalyst proposed by the present invention has simple operation, short preparation period, and environment-friendly Friendly, suitable for commercial promotion.

Description

A bismuth vanadate-graphene composite photocatalyst and its preparation and application

technical field

The invention relates to the technical field of organic wastewater decolorization treatment, in particular to a bismuth vanadate-graphene composite photocatalyst prepared by microwave synthesis using graphene as a template and its application.

Background technique

With the rapid development of the global economy, the problem of environmental pollution has become increasingly prominent. Whether environmental pollution can be controlled and treated in a timely and effective manner will affect the further development of the economy. In traditional technical research, semiconductor photocatalysis technology represented by titanium dioxide has been widely used in the field of environmental pollution control. However, the bandgap width of titanium dioxide is 3.2eV, which only responds to ultraviolet light, and its practicability is poor. For this reason, many scholars at home and abroad have carried out a lot of research work, aiming to find a photocatalyst material with good photoactivity, high catalytic efficiency, low success rate and wide application range, so as to reduce the difficulty and cost of environmental pollution control.

Bismuth vanadate, as a monoclinic scheelite structure, has photocatalytic activity when irradiated by visible light, and can catalyze the decomposition of water molecules to generate oxygen and degrade organic pollutants. It is a promising catalyst. However, the photogenerated electron-hole pairs generated by bismuth vanadate are easy to recombine in the bulk phase and surface of the catalyst, resulting in a decrease in photocatalytic activity. How to effectively prevent the recombination of photogenerated electron-hole pairs, improve the separation efficiency of photogenerated carriers, and improve the catalytic activity of bismuth vanadate are the research focus of bismuth vanadate as photocatalysis. Patent 201110021160.0 discloses a visible light-responsive bismuth vanadate-graphene composite photocatalyst and its preparation method. Using graphene as a template, a leaf-shaped bismuth vanadate-graphene composite photocatalyst was prepared by hydrothermal synthesis. However, the hydrothermal method adopted in this patent needs to be reacted at 180°C for 6 hours, and the preparation cycle is long, the reaction equipment is complex, the reaction energy consumption is high, and the production cost is high.

Contents of the invention

The present invention proposes a bismuth vanadate-graphene composite photocatalyst and its preparation and application, aiming to provide a bismuth vanadate-graphene composite photoresponse to visible light with low production cost, short preparation cycle and high photocatalytic activity catalyst of light.

A bismuth vanadate-graphene composite photocatalyst proposed by the invention is composed of bismuth vanadate and graphene with a mass ratio of 1:1.

A kind of method for preparing bismuth vanadate-graphene composite photocatalyst that the present invention proposes comprises the steps:

The first step: preparation of graphene oxide colloidal suspension:

First, graphene oxide was prepared by the Hume method using flake graphite powder as raw material; secondly, graphene oxide was centrifugally cleaned with double distilled water; finally, the cleaned graphene oxide was ultrasonically dispersed in double distilled water;

The second step: preparation of bismuth vanadate-graphene oxide composite:

First, the product of the first step is stripped with sodium hydroxide solution;

Secondly, bismuth nitrate and ammonium metavanadate are dissolved in concentrated nitric acid and sodium hydroxide solution respectively to obtain bismuth nitrate solution and ammonium metavanadate solution of equal substance molar concentration and equal volume;

Finally, add the above-mentioned ammonium metavanadate solution into the graphene oxide colloidal suspension after exfoliation and ultrasonically disperse for 5-20min, then slowly add the above-mentioned bismuth nitrate solution into the graphene oxide colloidal suspension, stir and ultrasonically disperse for 5-20min ;

The third step: preparation of bismuth vanadate-graphene composite:

Place the product obtained in the second step in a microwave reactor and react at 70-100°C for 40-60min;

The fourth step: preparation of bismuth vanadate-graphene composite photocatalyst:

The product obtained in the third step is centrifuged, washed with twice distilled water, and dried.

As a preferred technical solution, the concentration of the graphene oxide solution obtained in the first step is 2.5-3.2g/L.

As a preferred technical solution, the time for ultrasonic dispersion in the first step is 20-40min.

As a preferred technical solution, the mass ratio of graphene oxide to bismuth vanadate in the second step is 1:1.

As a preferred technical solution, the reaction temperature in the third step is 95° C., and the reaction time is 50 minutes.

As a preferred technical solution, water cooling and magnetic stirring are used throughout the third step.

The invention proposes the application of a bismuth vanadate-graphene composite photocatalyst. The bismuth vanadate-graphene composite photocatalyst can use a high-pressure mercury lamp as a light source to decolorize methyl orange.

As a preferred technical solution, the bismuth vanadate-graphene composite photocatalyst is put into a 20 mg/L methyl orange solution at a ratio of 1 g/L for decolorization.

The bismuth vanadate-graphene composite photocatalyst proposed by the present invention has high photocatalytic activity and low production cost; a method for preparing bismuth vanadate-graphene composite photocatalyst proposed by the present invention has simple operation, short preparation period, and environment-friendly Friendly, suitable for commercial promotion. The bismuth vanadate-graphene composite photocatalyst proposed by the present invention has a good catalytic effect. Under the same conditions: using bismuth vanadate-graphene as a catalyst to catalyze the degradation of methyl orange, 73% of methyl orange is degraded in 25 minutes; The catalyst catalyzes the degradation of methyl orange, and 6% of the methyl orange is degraded in 30 minutes. The bismuth vanadate-graphene composite photocatalyst prepared by the invention has a good catalytic effect.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings that need to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description are only For some embodiments of the present invention, those skilled in the art can also obtain other drawings based on these drawings without any creative work.

Fig. 1 is a kind of schematic flow sheet of the method for preparing bismuth vanadate-graphene composite photocatalyst;

Fig. 2 is the SEM figure of bismuth vanadate-graphene composite photocatalyst;

Fig. 3 is the XRD pattern of bismuth vanadate-graphene composite photocatalyst;

Fig. 4 is the rate figure that bismuth vanadate-graphene composite photocatalyst catalyzes the degradation of methyl orange;

Figure 5 is a rate diagram of the degradation of methyl orange catalyzed by the bismuth vanadate photocatalyst.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

As shown in Figure 1: a kind of method that the present invention proposes to prepare bismuth vanadate-graphene composite photocatalyst comprises the steps:

The first step: preparation of graphene oxide colloidal suspension:

First, graphene oxide was prepared by the Hume method using flake graphite powder as raw material; secondly, graphene oxide was centrifugally cleaned with double distilled water; finally, the cleaned graphene oxide was ultrasonically dispersed in double distilled water;

The second step: preparation of bismuth vanadate-graphene oxide composite:

First, the product of the first step is stripped with sodium hydroxide solution;

Secondly, bismuth nitrate and ammonium metavanadate are dissolved in concentrated nitric acid and sodium hydroxide solution respectively to obtain bismuth nitrate solution and ammonium metavanadate solution of equal substance molar concentration and equal volume;

Finally, add the above-mentioned ammonium metavanadate solution into the graphene oxide colloidal suspension after exfoliation and ultrasonically disperse for 5-20min, then slowly add the above-mentioned bismuth nitrate solution into the graphene oxide colloidal suspension, stir and ultrasonically disperse for 5-20min ;

The third step: preparation of bismuth vanadate-graphene composite:

Place the product obtained in the second step in a microwave reactor and react at 70-100°C for 40-60min;

The fourth step: preparation of bismuth vanadate-graphene composite photocatalyst:

The product obtained in the third step is centrifuged, washed with twice distilled water, and dried.

In yet another embodiment of the present invention, as a preferred technical solution, the concentration of the graphene oxide solution obtained in the first step is 2.5-3.2 g/L.

In yet another embodiment of the present invention, as a preferred technical solution, the time for ultrasonic dispersion in the first step is 20-40 minutes.

In another embodiment of the present invention, as a preferred technical solution, the mass ratio of graphene oxide to bismuth vanadate in the second step is 1:1.

In yet another embodiment of the present invention, as a preferred technical solution, the reaction temperature in the third step is 95° C., and the reaction time is 50 minutes.

In another embodiment of the present invention, as a preferred technical solution, water cooling and magnetic stirring are used throughout the third step.

As a preferred technical solution, the bismuth vanadate-graphene composite photocatalyst is put into a 20 mg/L methyl orange solution at a ratio of 1 g/L for decolorization.

As shown in Figure 2 and Figure 3: a bismuth vanadate-graphene composite photocatalyst proposed by the present invention is composed of bismuth vanadate and graphene with a mass ratio of 1:1. The SEM picture in Figure 2 shows that the shape of bismuth vanadate is irregular granular, with a particle size of about 1-2 μm, distributed on the surface and between the sheets of graphene oxide, forming an intercalation composite structure; the XRD spectrum in Figure 3 It shows that the 2θ of bismuth vanadate-graphene composite photocatalyst is 28.784°, compared with the standard card (JCPDS No.14-0688), it is found that its position and relative intensity are consistent with the standard diffraction line of monoclinic bismuth vanadate The main peaks are basically consistent, and the characteristic absorption peak of graphene oxide does not appear in the spectrum, indicating that the addition of graphite oxide does not change the monoclinic phase structure of bismuth vanadate, which may be due to the increase in the interlayer spacing of graphene oxide, resulting in the position of the absorption peak Moving to a low diffraction angle, it can be seen that bismuth vanadate is a monoclinic crystal system with high crystallinity.

As shown in Fig. 4 and Fig. 5: the present invention proposes the application of a kind of bismuth vanadate-graphene composite photocatalyst, with bismuth vanadate-graphene composite photocatalyst and bismuth vanadate respectively as catalyst, with high pressure mercury lamp as The light source was used to decolorize methyl orange, and the relationship between the degradation rate and the degradation time was investigated.

A method for preparing bismuth vanadate-graphene composite photocatalyst proposed by the present invention has low production cost, short preparation cycle and environmental friendliness, and is suitable for commercial promotion; the catalytic effect of the bismuth vanadate-graphene composite photocatalyst proposed by the present invention Good, under the same conditions: using bismuth vanadate-graphene as a catalyst to catalyze the degradation of methyl orange, 73% of methyl orange was degraded in 25 minutes; using bismuth vanadate as a catalyst to catalyze the degradation of methyl orange, 30 minutes degraded 6% of methyl orange %, it can be seen that the bismuth vanadate-graphene composite photocatalyst prepared by the present invention has a good catalytic effect.

Example 1

preparation:

The first step: preparation of graphene oxide colloidal suspension:

Firstly, graphene oxide was prepared by the Hume method using flake graphite powder as raw material; secondly, graphene oxide was centrifugally cleaned with double distilled water; finally, the cleaned graphene oxide was ultrasonically dispersed in double distilled water, and ultrasonic time 20-40min, the graphene oxide solution concentration is 2.9g/L;

The second step: preparation of bismuth vanadate-graphene oxide composite:

First, the product of the first step is stripped with sodium hydroxide solution;

Secondly, bismuth nitrate and ammonium metavanadate are dissolved in concentrated nitric acid and sodium hydroxide solution respectively to obtain bismuth nitrate solution and ammonium metavanadate solution of equal substance molar concentration and equal volume;

Finally, add the above-mentioned ammonium metavanadate solution into the graphene oxide colloidal suspension after exfoliation and ultrasonically disperse for 5-20min, then slowly add the above-mentioned bismuth nitrate solution into the graphene oxide colloidal suspension, stir and ultrasonically disperse for 5-20min , to obtain a composite of bismuth vanadate-graphene oxide with a mass ratio of 1:1;

The third step: preparation of bismuth vanadate-graphene composite:

The product obtained in the second step was placed in a microwave reactor, and reacted for 50 minutes under the conditions of 95°C, magnetic stirring, and circulating water cooling;

The fourth step: preparation of bismuth vanadate-graphene composite photocatalyst:

The product obtained in the third step is centrifuged, washed with twice distilled water, and dried.

application:

Using bismuth vanadate/graphene composite photocatalyst as the catalyst, methyl orange as the model pollutant, 0.1g of the composite was used to catalyze the degradation of 100ml, 20mg/L methyl orange solution, and the methyl orange was studied under the irradiation of a high-pressure mercury lamp Decolorization reaction. As shown in Figure 4 and Figure 5 together: with bismuth vanadate-graphene composite photocatalyst as catalyst, methyl orange degrades 73% in 25 minutes, and under the same conditions with bismuth vanadate as catalyst, methyl orange degrades in 30 minutes 6%, it can be seen that the bismuth vanadate-graphene composite photocatalyst prepared by the present invention has a good catalytic effect.

Example 2

preparation:

The first step: preparation of graphene oxide colloidal suspension:

Firstly, graphene oxide was prepared by the Hume method using flake graphite powder as raw material; secondly, graphene oxide was centrifugally cleaned with double distilled water; finally, the cleaned graphene oxide was ultrasonically dispersed in double distilled water, and ultrasonic time 20-40min, the graphene oxide solution concentration is 2.5g/L;

The second step: preparation of bismuth vanadate-graphene oxide composite:

First, the product of the first step is stripped with sodium hydroxide solution;

Secondly, bismuth nitrate and ammonium metavanadate are dissolved in concentrated nitric acid and sodium hydroxide solution respectively to obtain bismuth nitrate solution and ammonium metavanadate solution of equal substance molar concentration and equal volume;

Finally, add the above-mentioned ammonium metavanadate solution into the graphene oxide colloidal suspension after exfoliation and ultrasonically disperse for 5-20min, then slowly add the above-mentioned bismuth nitrate solution into the graphene oxide colloidal suspension, stir and ultrasonically disperse for 5-20min , to obtain a composite of bismuth vanadate-graphene oxide with a mass ratio of 1:1;

The third step: preparation of bismuth vanadate-graphene composite:

The product obtained in the second step was placed in a microwave reactor, and reacted for 40 minutes at 70°C, magnetic stirring, and circulating water cooling;

The fourth step: preparation of bismuth vanadate-graphene composite photocatalyst:

The product obtained in the third step is centrifuged, washed with twice distilled water, and dried.

Example 3

preparation:

The first step: preparation of graphene oxide colloidal suspension:

Firstly, graphene oxide was prepared by the Hume method using flake graphite powder as raw material; secondly, graphene oxide was centrifugally cleaned with double distilled water; finally, the cleaned graphene oxide was ultrasonically dispersed in double distilled water, and ultrasonic time 20-40min, the graphene oxide solution concentration is 3.2g/L;

The second step: preparation of bismuth vanadate-graphene oxide composite:

First, the product of the first step is stripped with sodium hydroxide solution;

Secondly, bismuth nitrate and ammonium metavanadate are dissolved in concentrated nitric acid and sodium hydroxide solution respectively to obtain bismuth nitrate solution and ammonium metavanadate solution of equal substance molar concentration and equal volume;

Finally, add the above-mentioned ammonium metavanadate solution into the graphene oxide colloidal suspension after exfoliation and ultrasonically disperse for 5-20min, then slowly add the above-mentioned bismuth nitrate solution into the graphene oxide colloidal suspension, stir and ultrasonically disperse for 5-20min , to obtain a composite of bismuth vanadate-graphene oxide with a mass ratio of 1:1;

The third step: preparation of bismuth vanadate-graphene composite:

The product obtained in the second step was placed in a microwave reactor, and reacted for 60 minutes at 100°C, magnetic stirring, and circulating water cooling;

The fourth step: preparation of bismuth vanadate-graphene composite photocatalyst:

The product obtained in the third step is centrifuged, washed with twice distilled water, and dried.

The bismuth vanadate-graphene composite photocatalyst proposed by the present invention has high photocatalytic activity and low production cost; a method for preparing bismuth vanadate-graphene composite photocatalyst proposed by the present invention has simple operation, short preparation period, and environment-friendly Friendly, suitable for commercial promotion. The bismuth vanadate-graphene composite photocatalyst proposed by the present invention has a good catalytic effect. Under the same conditions: using bismuth vanadate-graphene as a catalyst to catalyze the degradation of methyl orange, 73% of methyl orange is degraded in 25 minutes; The catalyst catalyzes the degradation of methyl orange, and 6% of the methyl orange is degraded in 30 minutes. The bismuth vanadate-graphene composite photocatalyst prepared by the invention has a good catalytic effect.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention within.

Claims (9)

1. A bismuth vanadate-graphene composite photocatalyst is characterized in that: it is compounded by bismuth vanadate and graphene with a mass ratio of 1:1. 2. a method for preparing bismuth vanadate-graphene composite photocatalyst as claimed in claim 1, is characterized in that: comprise the steps: The first step: preparation of graphene oxide colloidal suspension: First, graphene oxide was prepared by the Hume method using flake graphite powder as raw material; secondly, graphene oxide was centrifugally cleaned with double distilled water; finally, the cleaned graphene oxide was ultrasonically dispersed in double distilled water; The second step: preparation of bismuth vanadate-graphene oxide composite: First, the product of the first step is stripped with sodium hydroxide solution; Secondly, bismuth nitrate and ammonium metavanadate are dissolved in concentrated nitric acid and sodium hydroxide solution respectively to obtain bismuth nitrate solution and ammonium metavanadate solution of equal substance molar concentration and equal volume; Finally, add the above-mentioned ammonium metavanadate solution into the graphene oxide colloidal suspension after exfoliation and ultrasonically disperse for 5-20min, then slowly add the above-mentioned bismuth nitrate solution into the graphene oxide colloidal suspension, stir and ultrasonically disperse for 5-20min ; The third step: preparation of bismuth vanadate-graphene composite: Place the product obtained in the second step in a microwave reactor and react at 70-100°C for 40-60min; The fourth step: preparation of bismuth vanadate-graphene composite photocatalyst: The product obtained in the third step is centrifuged, washed with twice distilled water, and dried. 3. a kind of method for preparing bismuth vanadate-graphene composite photocatalyst according to claim 2, is characterized in that: the graphene oxide solution concentration that obtains in the first step is 2.5-3.2g/L. 4. a kind of method for preparing bismuth vanadate-graphene composite photocatalyst according to claim 2 is characterized in that: the time of ultrasonic dispersion in the first step is 20-40min. 5. a kind of method for preparing bismuth vanadate-graphene composite photocatalyst according to claim 2 is characterized in that: the mass ratio of graphene oxide and bismuth vanadate is 1:1 in the second step. 6. A method for preparing bismuth vanadate-graphene composite photocatalyst according to claim 2, characterized in that: in the third step, the reaction temperature is 95°C, and the reaction time is 50min. 7. A kind of method for preparing bismuth vanadate-graphene composite photocatalyst according to claim 2, is characterized in that: adopt water cooling and magnetic stirring in the whole process in the 3rd step. 8. an application of bismuth vanadate-graphene composite photocatalyst as claimed in claim 1, is characterized in that: described bismuth vanadate-graphene composite photocatalyst can adopt high-pressure mercury lamp to make light source, to methyl orange For decolorization. 9. the application of composite photocatalyst according to claim 8 is characterized in that: described bismuth vanadate-graphene composite photocatalyst is dropped in the methyl orange solution of 20mg/L by the ratio of 1g/L and carries out decolorization deal with.

Images