Bi2WO6intercalation MgAl-LDH material and preparation method and application thereof
阅读说明：本技术 一种Bi2WO6插层MgAl-LDH材料及其制备方法和应用 (Bi2WO6intercalation MgAl-LDH material and preparation method and application thereof ) 是由 郑国源 奚羽 王吉林 莫淑一 邹正光 周炳 龙飞 于 2019-09-23 设计创作，主要内容包括：本发明提供了一种Bi_2WO_6插层MgAl-LDH材料及其制备方法和应用,属于光催化材料技术领域。本发明提供的制备方法,包括以下步骤：将镁源和铝源溶解于水中,得到溶液A；将碱溶于水中,得到溶液B；将钨源溶解于水中,得到溶液C；将所述溶液A和溶液B同时滴加到溶液C中后,进行第一水热反应,第一次固液分离后得到WO_4~(2-)插层MgAl-LDH粉体；将所述WO_4~(2-)插层MgAl-LDH粉体和铋源分散到水中,将所得悬浊液进行第二水热反应,第二次固液分离后得到Bi_2WO_6插层MgAl-LDH材料。本发明通过将Bi_2WO_6纳米颗粒负载于MgAl-LDH层间,大大提高了Bi_2WO_6的光催化性能。(The invention provides a Bi 2 WO 6 An intercalated MgAl-LDH material, a preparation method and application thereof, belonging to the technical field of photocatalytic materials. The preparation method provided by the invention comprises the following steps: dissolving a magnesium source and an aluminum source in water to obtain a solution A; dissolving alkali in water to obtain a solution B; dissolving a tungsten source in water to obtain a solution C; dropwise adding the solution A and the solution B into the solution C at the same time, performing a first hydrothermal reaction, and performing first solid-liquid separation to obtain WO 4 2‑ Intercalation MgAl-LDH powder; subjecting said WO to 4 2‑ Dispersing the intercalated MgAl-LDH powder and a bismuth source into water, carrying out a second hydrothermal reaction on the obtained suspension, and carrying out a second solid-liquid separation to obtain Bi 2 WO 6 Intercalation MgAl-LDH material. The invention is prepared byBi 2 WO 6 The nano particles are loaded between MgAl-LDH layers, so that Bi is greatly improved 2 WO 6 the photocatalytic performance of (a).)
1. bi2WO6The preparation method of the intercalated MgAl-LDH material is characterized by comprising the following steps:
Dissolving a magnesium source and an aluminum source in water to obtain a solution A; dissolving alkali in water to obtain a solution B; dissolving a tungsten source in water to obtain a solution C;
Dropwise adding the solution A and the solution B into the solution C at the same time, performing a first hydrothermal reaction, and performing first solid-liquid separation to obtain WO4 2-Intercalation MgAl-LDH powder;
Subjecting said WO to4 2-dispersing the intercalated MgAl-LDH powder and a bismuth source into water, carrying out a second hydrothermal reaction on the obtained suspension, and carrying out a second solid-liquid separation to obtain Bi2WO6Intercalation MgAl-LDH material.
2. The production method according to claim 1, wherein the magnesium source is magnesium nitrate, magnesium sulfate, or magnesium chloride; the aluminum source is aluminum nitrate, aluminum sulfate or aluminum polychloride; the alkali is sodium hydroxide or potassium hydroxide; the tungsten source is sodium tungstate or ammonium tungstate; the bismuth source is bismuth nitrate or bismuth trichloride.
3. The method according to claim 1 or 2, wherein the molar ratio of Mg to Al in the solution A is (2-2.2): 1; the total amount of Mg and Al in the solution A and OH in the solution B-The molar ratio of (1) to (2.3-2.4); the molar ratio of the total amount of Mg and Al in the solution A to W in the solution C is 1: (1.1-1.2); the molar ratio of Bi in the bismuth source to W in the solution C is (1-3): 1.
4. The method according to claim 1, wherein the specific operation of simultaneously adding dropwise the solution A and the solution B to the solution C is: and dropwise adding the solution A into the solution C under the conditions of constant temperature of 50-70 ℃ and stirring speed of 150-500 r/min, and simultaneously dropwise adding the solution B to control the pH value of the mixed solution to be 8-11.
5. The preparation method according to claim 1, wherein the temperature of the first hydrothermal reaction is 130-160 ℃ and the time is 9-12 h.
6. The preparation method according to claim 1, wherein the temperature of the second hydrothermal reaction is 200 to 210 ℃ and the time is 15 to 24 hours.
7. The preparation method according to claim 1, wherein the first solid-liquid separation and the second solid-liquid separation are performed by centrifugation at 4000 to 10000r/min independently; the centrifugation time is independently 5-10 min.
8. The method according to claim 1 or 7, wherein after the first solid-liquid separation and the second solid-liquid separation, the method further comprises freeze-drying the obtained solid product.
9. Bi produced by the production method according to any one of claims 1 to 82WO6An intercalated MgAl-LDH material, comprising MgAl-LDH and Bi between the MgAl-LDH layers2WO6And (3) nanoparticles.
10. the Bi of claim 92WO6The intercalated MgAl-LDH material is applied to the treatment of dye wastewater.
Technical Field
The invention relates to the technical field of photocatalytic materials, in particular to Bi2WO6An intercalated MgAl-LDH material, a preparation method and application thereof.
Background
with the wide application of dyes in daily life, the pollution of underground water caused by the dyes is more and more serious. Dyes readily absorb and reflect sunlight, thereby being able to block photosynthesis by aquatic plants and interfere with the growth of aquatic species in the natural environment. More seriously, the low biodegradability of the dye leads to its constant accumulation, causing persistent pollution. Dyes can be classified into a plurality of structural species, for example, azo, anthraquinone, or metal complex compounds, depending on their structure. These organic pollutants may irritate the skin of humans and animals and cause blood disorders, liver and kidney damage, and poisoning of the central nervous system in humans and animals. Therefore, there is considerable research interest in finding solutions that easily treat these contaminants and prevent their accumulation.
The semiconductor photocatalysis technology is adopted, and infinite solar energy is utilized to degrade organic pollutants in wastewater, which is the solution with the most application prospect. Nano-sized Bi2WO6Has narrow band gap (2.5eV), and is an effective photocatalyst for dye degradation under visible light. However, Bi due to its rapid recombination of electron-hole pairs2WO6The photocatalytic efficiency of (a) is still low.
disclosure of Invention
the object of the present invention is to provide a Bi2WO6An intercalated MgAl-LDH material is prepared through mixing Bi2WO6The nano particles are loaded between MgAl-LDH layers, and Bi is improved2WO6the photocatalytic performance of (a).
In order to achieve the above object, the present invention provides the following technical solutions:
The invention provides a Bi2WO6The preparation method of the intercalated MgAl-LDH material comprises the following steps:
dissolving a magnesium source and an aluminum source in water to obtain a solution A; dissolving alkali in water to obtain a solution B; dissolving a tungsten source in water to obtain a solution C;
Dropwise adding the solution A and the solution B into the solution C at the same time, performing a first hydrothermal reaction, and performing first solid-liquid separation to obtain WO4 2-Intercalation MgAl-LDH powder;
Subjecting said WO to4 2-Dispersing the intercalated MgAl-LDH powder and a bismuth source into water, carrying out a second hydrothermal reaction on the obtained suspension, and carrying out a second solid-liquid separation to obtain Bi2WO6Intercalation MgAl-LDH material.
Preferably, the magnesium source is magnesium nitrate, magnesium sulfate or magnesium chloride; the aluminum source is aluminum nitrate, aluminum sulfate or aluminum chloride; the alkali is sodium hydroxide or potassium hydroxide; the tungsten source is sodium tungstate or ammonium tungstate; the bismuth source is bismuth nitrate or bismuth trichloride.
Preferably, the molar ratio of Mg to Al in the solution A is (2-2.2): 1; the total amount of Mg and Al in the solution A and OH in the solution B-The molar ratio of (1) to (2.3-2.4); the molar ratio of the total amount of Mg and Al in the solution A to W in the solution C is 1: (1.1-1.2); the molar ratio of Bi in the bismuth source to W in the solution C is (1-3): 1.
Preferably, the specific operation of simultaneously dripping the solution A and the solution B into the solution C is as follows: and dropwise adding the solution A into the solution C under the conditions of constant temperature of 50-70 ℃ and stirring speed of 150-500 r/min, and simultaneously dropwise adding the solution B to control the pH value of the mixed solution to be 8-11.
Preferably, the temperature of the first hydrothermal reaction is 130-160 ℃, and the time is 9-12 h.
Preferably, the temperature of the second hydrothermal reaction is 200-210 ℃ and the time is 15-24 h.
Preferably, the first solid-liquid separation and the second solid-liquid separation adopt a centrifugal mode, and the rotating speed of the centrifugal mode is 4000-10000 r/min independently; the centrifugation time is independently 5-10 min.
preferably, after the first solid-liquid separation and the second solid-liquid separation, the method further comprises freeze-drying the obtained solid product.
The invention provides Bi prepared by the preparation method in the scheme2WO6An intercalated MgAl-LDH material comprising MgAl-LDH and Bi between the MgAl-LDH layers2WO6And (3) nanoparticles.
The invention provides the Bi of the scheme2WO6the intercalated MgAl-LDH material is applied to the treatment of dye wastewater.
The invention provides a Bi2WO6The preparation method of the intercalated MgAl-LDH material comprises the following steps: dissolving a magnesium source and an aluminum source in water to obtain a solution A; dissolving alkali in water to obtain a solution B; dissolving a tungsten source in water to obtain a solution C; dropwise adding the solution A and the solution B into the solution C at the same time, performing a first hydrothermal reaction, and performing first solid-liquid separation to obtain WO4 2-Intercalation MgAl-LDH powder; subjecting said WO to4 2-Dispersing the intercalated MgAl-LDH powder and a bismuth source into water, carrying out a second hydrothermal reaction on the obtained suspension, and carrying out a second solid-liquid separation to obtain Bi2WO6Intercalation MgAl-LDH material. The invention is prepared by mixing Bi2WO6The nano particles are loaded between the layers of MgAl-LDH, on one hand, Bi is reduced2WO6particle size of (B) increased Bi2WO6The catalytic ability of (a); on the other hand, Bi2WO6Through the recombination with MgAl-LDH, the recombination rate of electron-hole pairs is reduced, thereby increasing Bi2WO6The photocatalytic performance of (a).
drawings
FIG. 1 shows the preparation of Bi according to example 12WO6The X-ray diffraction patterns of the intercalated MgAl-LDH material and the pure MgAl-LDH powder;
FIG. 2 shows Bi obtained in example 12WO6The X-ray diffraction small-angle amplification map of the intercalated MgAl-LDH material and the pure MgAl-LDH powder;
FIG. 3 shows Bi obtained in example 1 of the present invention2WO6a field emission scanning electron microscope picture of the intercalation MgAl-LDH material;
FIG. 4 shows Bi obtained in example 1 of the present invention2WO6Transmission electron microscopy of intercalated MgAl-LDH material;
FIG. 5 shows Bi obtained in example 1 of the present invention2WO6A high resolution transmission electron microscopy image of particulate matter in the intercalated MgAl-LDH material;
FIG. 6 shows Bi obtained in example 1 of the present invention2WO6Intercalation MgAl-LDH material and pure Bi2WO6A fluorescence spectrogram of the pure MgAl-LDH powder;
FIG. 7 shows Bi obtained in example 1 of the present invention2WO6And (3) an intercalation MgAl-LDH material degradation efficiency graph for methyl orange.
Detailed Description
The invention provides a Bi2WO6The preparation method of the intercalated MgAl-LDH material comprises the following steps:
Dissolving a magnesium source and an aluminum source in water to obtain a solution A; dissolving alkali in water to obtain a solution B; dissolving a tungsten source in water to obtain a solution C;
Dropwise adding the solution A and the solution B into the solution C at the same time, performing a first hydrothermal reaction, and performing first solid-liquid separation to obtain WO4 2-Intercalation MgAl-LDH powder;
Subjecting said WO to4 2-Dispersing the intercalated MgAl-LDH powder and a bismuth source into water, carrying out a second hydrothermal reaction on the obtained suspension, and carrying out a second solid-liquid separation to obtain Bi2WO6Intercalation MgAl-LDH material.
In the present invention, the starting materials used are all commercially available products well known in the art, unless otherwise specified.
In the invention, a magnesium source and an aluminum source are dissolved in water to obtain a solution A. In the present invention, the magnesium source is preferably magnesium nitrate, magnesium sulfate or magnesium chloride; the aluminum source is preferably aluminum nitrate, aluminum sulfate or aluminum chloride; the water is preferably deionized water. Since the magnesium source and the aluminum source used in the present invention mostly contain crystal water, the magnesium source and the aluminum source of the present invention include the above-listed compounds and hydrates thereof. The present invention does not require any particular manipulation of the dissolution, and the dissolution may be performed in any manner known in the art. In the invention, the molar ratio of Mg to Al in the solution A is preferably (2-2.2): 1; the concentration of Mg in the solution A is preferably 0.05-2 mol/L.
The invention dissolves alkali in water to obtain solution B. In the present invention, the base is preferably sodium hydroxide or potassium hydroxide; the water is preferably deionized water. In the present invention, the amount of the alkali is preferably determined depending on the contents of Mg and Al in the solution a; the total amount of Mg and Al in the solution A and OH in the solution B-The molar ratio of (A) to (B) is preferably 1 (2.3 to 2.4). In the present invention, OH in the solution B-The concentration of (b) is preferably 0.05 to 2 mol/L.
The invention dissolves tungsten source in water to obtain solution C. In the present invention, the tungsten source is preferably sodium tungstate or ammonium tungstate; the water is preferably deionized water. In the present invention, the amount of the tungsten source is preferably determined according to the contents of Mg and Al in the solution a; the molar ratio of the total amount of Mg and Al in the solution A to W in the solution C is preferably 1: (1.1-1.2).
After obtaining the solution A, the solution B and the solution C, the solution A and the solution B are simultaneously dripped into the solution C, then a first hydrothermal reaction is carried out, and WO is obtained after first solid-liquid separation4 2-Intercalation MgAl-LDH powder.
In the present invention, the specific operation of simultaneously adding the solution a and the solution B dropwise to the solution C is preferably: and dropwise adding the solution A into the solution C under the conditions of constant temperature of 50-70 ℃ and stirring speed of 150-500 r/min, and simultaneously dropwise adding the solution B to control the pH value of the mixed solution to be 8-11. The dropping speed of the solution A and the solution B is not specially limited, and the pH value of the mixed solution can be ensured to be 8-11 in the dropping process.
In the invention, the temperature of the first hydrothermal reaction is preferably 130-160 ℃, and the time is preferably 9-12 h. In the first hydrothermal reaction process, a magnesium source and an aluminum source react to generate MgAl-LDH, and meanwhile, MgAl-LDH is generatedinserting a tungsten source between the layers of MgAl-LDH to obtain WO4 2-And (3) suspension of intercalated MgAl-LDH powder.
After the first hydrothermal reaction is finished, the invention carries out the first hydrothermal reaction to obtain a product system (WO)4 2-Suspension of intercalated MgAl-LDH powder) is subjected to first solid-liquid separation to obtain WO4 2-Intercalation MgAl-LDH powder. Before the first solid-liquid separation, the method preferably further comprises washing the first hydrothermal reaction product system with deionized water for 5-6 times. In the invention, the first solid-liquid separation mode is preferably centrifugation, and the rotation speed of the centrifugation is preferably 4000-10000 r/min; the time for centrifugation is preferably 5-10 min. After the first solid-liquid separation, the invention preferably further comprises freeze-drying the solid product obtained after the first solid-liquid separation to obtain WO4 2-Intercalation MgAl-LDH powder. In the invention, the freeze drying is preferably carried out in a freeze dryer, the temperature of the freeze drying is preferably-10 to-50 ℃, and the time of the freeze drying is preferably 15 to 22 hours.
To obtain WO4 2-After the MgAl-LDH powder is intercalated, the WO is added into the powder4 2-Dispersing the intercalated MgAl-LDH powder and a bismuth source into water, carrying out a second hydrothermal reaction on the obtained suspension, and carrying out a second solid-liquid separation to obtain Bi2WO6Intercalation MgAl-LDH material. In the present invention, the bismuth source is preferably bismuth nitrate or bismuth trichloride; the bismuth source is preferably used in an amount according to preparation WO4 2-the using amount of a tungsten source is determined when the MgAl-LDH powder is intercalated, and the molar ratio of Bi in the bismuth source to W in the solution C is preferably (1-3): 1. The invention has no special requirement on the dosage of the water, and can lead WO to be used4 2-The intercalated MgAl-LDH powder and the bismuth source are uniformly dispersed.
In the invention, the temperature of the second hydrothermal reaction is preferably 200-210 ℃, and the time is preferably 15-24 h. In the second hydrothermal reaction process, the bismuth source reacts with tungstate radical to generate Bi2WO6And inserted between the layers of MgAl-LDH.
after the second hydrothermal reaction is finished, the invention is implementedThe second hydrothermal reaction product system is subjected to second solid-liquid separation to obtain Bi2WO6Intercalation MgAl-LDH material. Before the second solid-liquid separation, the method preferably further comprises washing the second hydrothermal reaction product system with deionized water for 5-6 times. In the invention, the second solid-liquid separation mode is preferably centrifugation, and the rotation speed of the centrifugation is preferably 4000-10000 r/min; the time for centrifugation is preferably 5-10 min. After the second solid-liquid separation, the present invention preferably further comprises freeze-drying the solid product obtained after the second solid-liquid separation to obtain Bi2WO6Intercalation MgAl-LDH material. In the invention, the freeze drying is preferably carried out in a freeze dryer, the temperature of the freeze drying is preferably-10 to-50 ℃, and the time of the freeze drying is preferably 15 to 22 hours.
The invention provides Bi prepared by the preparation method in the scheme2WO6An intercalated MgAl-LDH material comprising MgAl-LDH and Bi between the MgAl-LDH layers2WO6And (3) nanoparticles. The invention is prepared by mixing Bi2WO6The nano particles are loaded between the layers of MgAl-LDH, on one hand, Bi is reduced2WO6Particle size of (B) increased Bi2WO6the catalytic ability of (a); on the other hand, Bi2WO6Through the recombination with MgAl-LDH, the recombination rate of electron-hole pairs is reduced, thereby increasing Bi2WO6The photocatalytic performance of (a).
The invention provides the Bi of the scheme2WO6The intercalated MgAl-LDH material is applied to the treatment of dye wastewater. The invention is not particularly limited to the specific embodiments of the applications described, and may be applied in any manner known in the art. The invention has no special requirements on the specific source and the composition of the dye wastewater, and the dye wastewater well known in the field can be used.
The following examples are given to illustrate Bi according to the present invention2WO6The intercalated MgAl-LDH material and the preparation method and use thereof are explained in detail but they are not to be construed as limiting the scope of the invention.