CN111266098A - Preparation and application of core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption effect on incident light - Google Patents

Abstract

The preparation method of the core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption effect on incident light comprises the steps of preparing titanium-silicon-zirconium sol by using zirconium oxychloride octahydrate, ethyl orthosilicate and titanium sulfate as starting raw materials, wherein the addition amount of the raw materials is n (Ti), n (Zr), n (Si) 2-6, 1: 1-4. Citric acid is taken as a metal ion complexing agent, and the mass ratio of the citric acid to the zirconium oxychloride octahydrate is 0.5: 2. Drying the titanium-silicon-zirconium sol, and calcining at 800 ℃ to obtain white TiO with good crystallinity₂‑ZrO₂‑SiO₂And (3) composite powder. Preparing another part of the same titanium-silicon-zirconium sol, soaking and calcining to obtain white TiO with good crystallinity₂‑ZrO₂‑SiO₂And calcining the composite powder at 350-450 ℃ for 1-2 h to obtain the core-shell structure Ti-Zr-Si composite photocatalyst. The prepared composite photocatalyst has good adsorption and photocatalysis performances, and can greatly improve the photocatalysis efficiency. The invention has the characteristics of simple process, short period, low energy consumption and low cost.

Description

A core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption of incident light Preparation and application of chemical agent

technical field

The invention belongs to the technical field of inorganic non-metallic materials, and relates to a core-shell structure powder, in particular to the preparation and application of a core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption effect on incident light.

Background technique

In recent years, the problem of environmental pollution has always attracted everyone's attention. With the development of textile and printing and dyeing industries, the pollution of dye water has become more and more serious, and it has become a major source of pollution. In 1976, Carey and others used semiconductor materials for photocatalytic degradation of pollutants, which opened the prelude of semiconductor photocatalytic technology in the field of environmental protection. As a typical structural and functional material, _TiO2 semiconductor photocatalyst has been the most studied material. However, due to the large forbidden band width of pure-phase TiO ₂ powder, the defects such as only responding to ultraviolet light greatly limit its application in the field of environmental treatment. Nowadays, more and more researchers focus their work on the modification of TiO ₂ powder, mainly including precious metal deposition, semiconductor compounding, doping and other methods. These methods are mainly to reduce the forbidden band width of TiO ₂ powder. . Currently, there are few reports on how photocatalysts improve the absorption of incident light.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a preparation and application of a core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption of incident light. The product has strong absorption of incident light and good photocatalytic performance.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A preparation method of a core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption effect on incident light, comprising the following steps:

Step 1, using zirconium oxychloride octahydrate, ethyl orthosilicate, and titanium sulfate as starting materials to prepare a titanium-silicon-zirconium sol;

Step 2, take a part of the titanium-silicon-zirconium sol to dry it, and obtain a white TiO ₂ -ZrO ₂ -SiO ₂ composite powder with good crystallinity after calcination;

Step 3, the composite powder is immersed in the titanium-silicon-zirconium sol, and after removing the excess sol, the titanium-silicon-zirconium sol@white (TiO ₂ -ZrO ₂ -SiO ₂ ) composite is obtained;

Step 4, heat treatment of the composite to obtain a core-shell structure Ti-Zr-Si composite photocatalyst.

The preparation method of the titanium-silicon-zirconium sol is as follows:

Under the condition of continuous magnetic stirring, add an alkaline reagent to 20 mL of deionized water, adjust pH=7-10, dissolve zirconium oxychloride octahydrate and complexing agent in the deionized water, and prepare a uniform and transparent solution, that is, Zirconium precursor solution; ethyl orthosilicate is dissolved in absolute ethanol to prepare ethyl orthosilicate solution; titanium sulfate is dissolved in deionized water to prepare titanium solution; The ethyl silicate solution and the titanium solution are added to the zirconium precursor solution to prepare the titanium-silicon-zirconium sol.

The alkaline agent is ammonia water or sodium hydroxide, and the complexing agent is a metal ion complexing agent or citric acid.

In the zirconium precursor solution, the zirconium ion concentration is 0.25±0.2moL/L, the mass ratio of zirconium oxychloride octahydrate and the complexing agent is 0.5:2, and the addition amount of ethyl orthosilicate and titanium sulfate is based on n (Ti):n(Zr):n(Si)=2～6:1:1～4 is determined.

In the step 2, a part of the titanium-silicon-zirconium sol is heated and stirred in a water bath at 80±10° C. for 4-6 hours to obtain a wet gel, which is dried in an oven at 100±10° C. for 12-24 hours to obtain the Titanium-silicon-zirconium dry gel; put the titanium-silicon-zirconium dry gel in a muffle furnace for calcination at 800° C. to obtain a white (TiO ₂ -ZrO ₂ -SiO ₂ ) composite powder with good crystallinity.

In the step 3, 2 g of the composite powder is immersed in the titanium-silicon-zirconium sol for 2-5 minutes, and then the excess sol is removed by vacuum filtration.

In the step 4, the composite is dried and placed in a crucible, and heat-treated in a muffle furnace at 350-550° C. for 1-2 hours.

The core-shell structure Ti-Zr-Si composite photocatalyst prepared by the invention can be used for the adsorption and photocatalytic degradation treatment of organic dye wastewater in dye, printing and other industries. The specific steps and principles are as follows: The black Ti-Zr-Si shell layer on the catalyst surface is rich in surface defect states, and the photocatalyst will quickly adsorb pollutants to its surface first. When the incident light irradiates the catalyst, it can absorb the incident light greatly, and then under the excitation of sunlight, the surface black Ti-Zr-Si shell layer absorbs sunlight energy, and then excites the white (TiO ₂ -ZrO 2 - TiO 2 -ZrO ₂ - SiO ₂ ) generates a large number of photogenerated carriers, and the surface black Ti-Zr-Si shell layer has many defect states, which act as electron traps, which is beneficial to the separation of photogenerated carriers, thereby improving the photocatalytic efficiency.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention firstly prepares white (TiO ₂ -ZrO ₂ -SiO ₂ ) powder with excellent photocatalytic performance, and after attaching a layer of titanium-silicon-zirconium gel on its surface, obtains black Ti-Zr-Si by calcining at low temperature shell. The black Ti-Zr-Si shell layer has a certain defect state, which enhances the activity of the powder. The UV-Vis absorption spectra show that the prepared core-shell structure Ti-Zr-Si composite photocatalyst has a high light absorption rate in the visible region. The method used in the invention for preparing the core-shell structure Ti-Zr-Si composite photocatalyst powder with strong absorption of incident light is simple, low in cost and free from secondary pollution. The surface of the white (TiO ₂ -ZrO ₂ -SiO ₂ ) powder with good crystallinity is wrapped with a low-temperature strong absorption layer with a certain number of defect states to form a core-shell structure, which does not affect the original white (TiO ₂ -ZrO _{2 )} -SiO ₂ ) powder is photocatalytic and has good adsorption performance.

(2) The core-shell structure Ti-Zr-Si composite photocatalyst prepared by the present invention has both good adsorption performance and excellent photocatalytic performance. In the photocatalytic reaction process, the photocatalyst prepared by the present invention will first rapidly adsorb pollutants to its surface, and then under the excitation of sunlight, the black Ti-Zr-Si shell on the surface absorbs sunlight energy, and then stimulates the The white color of the core layer (TiO ₂ -ZrO ₂ -SiO ₂ ) generates a large number of photogenerated carriers. Because the surface black Ti-Zr-Si shell layer has many defect states, it acts as an electron trap, which is beneficial to the separation of photogenerated carriers. Thus, the photocatalytic efficiency is improved.

(3) The introduction of SiO ₂ can effectively inhibit the growth of grains and the transformation of crystal forms. The fine-grained powder has a quantum size effect, and the surface activity of the powder is increased, which is beneficial to the improvement of the photocatalytic activity.

(4) ZrO ₂ is the only oxide with both acidic and basic sites. It has both oxidizing and reducing properties. It is an excellent adsorption material. Zr and Ti belong to the same family and have similar properties. , the _two have good matching after recombination, and can maintain their respective advantages. At the same time, new catalytic active sites are generated through the synergistic effect of titanium and zirconium. response.

Description of drawings

FIG. 1 is the UV-Vis absorption spectra of white (TiO ₂ -ZrO ₂ -SiO ₂ ) (a) and core-shell structure Ti-Zr-Si composite photocatalysts (b) prepared in Example 2.

Fig. 2 is white (TiO ₂ -ZrO ₂ -SiO ₂ ) (S1) and the core-shell structure Ti-Zr-Si composite photocatalyst (S2) with strong absorption of incident light prepared in Example 2 on Rhodamine B Photocatalytic degradation diagram of .

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, which are not intended to limit its protection scope.

Example 1

A core-shell structure Ti-Zr-Si composite photocatalyst preparation process with strong absorption of incident light, the specific process is as follows:

(1) Step 1: under the condition of continuous magnetic stirring, add alkaline reagent ammonia water to 20 mL of deionized water, adjust pH=7～10, dissolve zirconium oxychloride and metal ion complexing agent in the above deionized water, prepare A uniform and transparent solution with a zirconium ion concentration of 0.05moL/L was obtained, that is, a zirconium precursor solution. Wherein, the mass ratio of zirconium oxychloride and metal ion complexing agent is 0.5:2. The ethyl orthosilicate solution was prepared by dissolving ethyl orthosilicate in absolute ethanol. Dissolve titanium sulfate in deionized water to prepare a titanium solution. The addition amounts of ethyl orthosilicate and titanium sulfate were determined according to n(Ti):n(Zr):n(Si)=6:1:4. Under the condition of continuous magnetic stirring, the ethyl orthosilicate solution and the titanium solution are sequentially added to the zirconium precursor solution to prepare the titanium-silicon-zirconium sol. The titanium-silicon-zirconium sol was heated and stirred in a water bath at 80°C for 4 hours to obtain a wet gel, which was then dried in an oven at 80°C for 12 hours to obtain a titanium-silicon-zirconium dry gel. Finally, the titanium-silicon-zirconium xerogel is calcined in a muffle furnace at 800° C. to obtain a white (TiO ₂ -ZrO ₂ -SiO ₂ ) composite powder with good crystallinity, which is ready for use.

(2) Step 2: firstly prepare a titanium-silicon-zirconium sol (the preparation process is the same as that of step 1). Weigh 2 g of the white (TiO ₂ -ZrO ₂ -SiO ₂ ) composite powder obtained in step 1, and immerse it in the titanium-silicon-zirconium sol for 2 minutes. Then the excess sol was removed by vacuum filtration to obtain a titanium-silicon-zirconium sol@white (TiO ₂ -ZrO ₂ -SiO ₂ ) composite. The composite was dried at a certain temperature, placed in a crucible, and heat-treated in a muffle furnace at 350 °C for 2 h to obtain a core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption of incident light.

Example 2

The preparation process of a core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption of incident light is the same as in Example 1, except that the calcination time after impregnation is different.

In this example, the calcination temperature after impregnation was 400°C.

FIG. 1 is the UV-Vis absorption spectra of white (TiO ₂ -ZrO ₂ -SiO ₂ ) (a) and core-shell structure Ti-Zr-Si composite photocatalysts (b) prepared in Example 2. It can be seen from the figure that the white (TiO ₂ -ZrO ₂ -SiO ₂ ) composite photocatalyst hardly absorbs incident light with a wavelength greater than 400 nm. The core-shell structure Ti-Zr-Si composite photocatalyst has a high absorption intensity in the entire visible light range, indicating that its response to visible light has a strong absorption effect.

Fig. 2 is white (TiO ₂ -ZrO ₂ -SiO ₂ ) (S1) and the core-shell structure Ti-Zr-Si composite photocatalyst (S2) with strong absorption of incident light prepared in Example 2 on Rhodamine B Photocatalytic degradation diagram of . It can be seen from the figure that compared with the white (TiO ₂ -ZrO ₂ -SiO ₂ ) composite photocatalyst, the core-shell structure Ti-Zr-Si composite photocatalyst has significantly improved the adsorption efficiency and photocatalytic degradation efficiency of Rhodamine B. The core-shell structure Ti-Zr-Si composite photocatalyst has an adsorption rate of 50% for rhodamine B after dark reaction for 60 minutes, and the degradation efficiency of rhodamine B reaches 98%-99% under the irradiation condition of 500w mercury lamp.

Claims (9)

1. a preparation method of the core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption effect to incident light, is characterized in that, comprises the steps: Step 1, using zirconium oxychloride octahydrate, ethyl orthosilicate, and titanium sulfate as starting materials to prepare a titanium-silicon-zirconium sol; Step 2, take a part of the titanium-silicon-zirconium sol to dry it, and obtain a white TiO ₂ -ZrO ₂ -SiO ₂ composite powder with good crystallinity after calcination; Step 3, the composite powder is immersed in the titanium-silicon-zirconium sol, and after removing the excess sol, the titanium-silicon-zirconium sol@white (TiO ₂ -ZrO ₂ -SiO ₂ ) composite is obtained; Step 4, heat treatment of the composite to obtain a core-shell structure Ti-Zr-Si composite photocatalyst. 2. the preparation method of the core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption effect to incident light according to claim 1, is characterized in that, the preparation method of described titanium-silicon-zirconium sol is as follows: Under the condition of continuous magnetic stirring, add an alkaline reagent to 20 mL of deionized water, adjust pH=7-10, dissolve zirconium oxychloride octahydrate and complexing agent in the deionized water, and prepare a uniform and transparent solution, that is, Zirconium precursor solution; ethyl orthosilicate is dissolved in absolute ethanol to prepare ethyl orthosilicate solution; titanium sulfate is dissolved in deionized water to prepare titanium solution; The ethyl silicate solution and the titanium solution are added to the zirconium precursor solution to prepare the titanium-silicon-zirconium sol. 3. the preparation method of the core-shell structure Ti-Zr-Si composite photocatalyst that has strong absorption effect to incident light according to claim 2, is characterized in that, described alkaline reagent is ammoniacal liquor or sodium hydroxide, described complex The mixture is metal ion complexing agent or citric acid. 4. The preparation method of the core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption effect on incident light according to claim 2 or 3, characterized in that, in the zirconium precursor solution, the zirconium ion concentration is 0.25 ±0.2moL/L, the mass ratio of zirconium oxychloride octahydrate and complexing agent is 0.5:2, the addition amount of tetraethyl orthosilicate and titanium sulfate is based on n(Ti):n(Zr):n(Si) = 2～6:1:1～4 is determined. 5. the preparation method of the core-shell structure Ti-Zr-Si composite photocatalyst that has strong absorption effect to incident light according to claim 1, is characterized in that, in described step 2, a part of titanium-silicon-zirconium sol is placed in 80 Heating and stirring in a water bath at ±10°C for 4-6 hours to obtain wet gel, and drying in an oven at 100±10°C for 12-24 hours to obtain a titanium-silicon-zirconium dry gel; put the titanium-silicon-zirconium dry gel in a It was calcined at 800°C in a muffle furnace to obtain a white (TiO ₂ -ZrO ₂ -SiO ₂ ) composite powder with good crystallinity. 6 . The method for preparing a core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption of incident light according to claim 1 , wherein in the step 3, 2 g of the composite powder is immersed in titanium silicon. 7 . zirconium sol for 2 to 5 minutes, and then remove excess sol by vacuum filtration. 7. The preparation method of the core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption to incident light according to claim 1, wherein in the step 4, the composite is dried and placed in a crucible , heat treatment in a muffle furnace at 350 to 550°C for 1 to 2 hours. 8 . The core-shell structure Ti-Zr-Si composite photocatalyst prepared by the method for preparing the core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption effect on incident light according to claim 1 . 9. The preparation method of the core-shell structure Ti-Zr-Si composite photocatalyst with strong absorption effect on incident light according to claim 1. The obtained core-shell structure Ti-Zr-Si composite photocatalyst is used for the adsorption and light absorption of organic dye wastewater. Applications of Catalytic Degradation.

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