CN103212392B - A kind of method for preparing TiO2/diatomite composite photocatalytic material by sol-gel method - Google Patents

Abstract

The invention provides a method for preparing a TiO ₂ /diatomite composite photocatalytic material by a sol-gel method, and belongs to the technical field of environmental pollution control and preparation of photocatalytic functional materials. Add butyl titanate to absolute ethanol, then add glacial acetic acid, and then stir to form light yellow transparent solution A; take deionized water and nitric acid and add it to absolute ethanol to obtain transparent solution B; diatomaceous earth Add it into deionized water and stir to form a suspension, then add metal nitrate solution to the suspension, and then add sodium hydroxide ethanol solution to it, until the metal ions are converted into metal hydroxides to form a mixed suspension C; the solution B and the mixed suspension C are added to the solution A in turn, and the gel is formed after standing and aging; after drying, the TiO ₂ /diatomite composite photocatalytic material is obtained through heat treatment. The method is simple, low-cost, and has no secondary pollution, and the obtained material has visible light activity, high photocatalytic degradation rate and obvious shift of absorption edge to the visible light range.

Description

A kind of method for preparing TiO2/diatomite composite photocatalytic material by sol-gel method

technical field

The invention relates to a method for preparing a TiO ₂ /diatomite composite photocatalytic material by a sol-gel method, and belongs to the technical field of environmental pollution control and preparation of photocatalytic functional materials.

Background technique

With the progress of human society, the problem of environmental pollution is becoming more and more serious, and the removal of these pollutants needs to consume a lot of energy, which poses a severe challenge to the increasingly depleted energy. How to rationally utilize the limited resources in nature and effectively control and solve the problem of environmental pollution has become a hot issue studied by many international and domestic scholars. In recent years, the photocatalytic technology that has attracted much attention can use solar energy as an energy source to degrade pollutants in the environment, but the natural light utilization rate of pure TiO ₂ photocatalyst is not high; TiO ₂ is a wide bandgap semiconductor, and its anatase The forbidden band width of type TiO ₂ is 3.2ev, and only ultraviolet light (300-400nm) with a shorter wavelength can be absorbed and utilized by it. In sunlight, visible light mainly accounts for 43%, and ultraviolet light only accounts for 5%, which greatly Limits the scope of application of _TiO2 photocatalyst; while the band gap (3.0eV) of rutile _TiO2 is narrower than that of anatase _TiO2 , when the rutile phase in the bulk phase increases, the absorption band edge of the spectrum also occurs accordingly Redshift, the ratio of rutile and anatase can be controlled by adjusting the heat treatment temperature, so that the absorption band edge of the spectrum will be redshifted accordingly.

We can take two methods to solve the problem of low photocatalytic degradation rate of TiO ₂ : one is by doping metal ions. Doping metal ions can provide TiO ₂ with electron acceptors, which is beneficial to the transfer of electrons, prolongs the separation time of electrons and holes, reduces the recombination of electrons and holes, and thus improves the photocatalytic degradation rate of TiO ₂ . The second is that titanium dioxide is loaded on diatomite, which is rich in sources, low in price and stable in nature. Diatomite is a porous surface adsorbent, and it can better realize the capture of photogenerated holes and inhibit the recombination of electron-hole pairs by preparing a composite photocatalyst with _TiO2 ; at the same time, diatomite has good adsorption properties, not only It can effectively remove organic pollutants in water, reduce the cost of photocatalytic treatment, and can also adsorb organic substances to the surface of TiO ₂ grains, increasing the contact probability between catalysts and pollutants, achieving the purpose of improving photodegradation efficiency and increasing degradation rate.

Contents of the invention

The present invention aims at the existing problems of TiO ₂ photocatalytic materials, and proposes a method for preparing TiO ₂ /diatomite composite photocatalytic materials by sol-gel method. This TiO ₂ /diatomite composite photocatalytic materials not only pass Metal-doped TiO ₂ is loaded on porous diatomaceous earth to improve its photocatalytic degradation rate, and the ratio of rutile and anatase is controlled by adjusting the heat treatment temperature, thereby improving its photocatalytic activity and realizing Absorption and utilization of visible light.

The present invention is realized through the following technical solutions: a method for preparing _TiO2 /diatomite composite photocatalytic material by a sol-gel method, through the following steps:

(1) According to the volume ratio of butyl titanate, absolute ethanol and glacial acetic acid as 20-28:48-54:2-8, add butyl titanate to absolute ethanol, then add glacial acetic acid, and then stir 20-50 minutes to form a light yellow and transparent solution A;

(2) According to the volume ratio of deionized water, nitric acid and absolute ethanol as 8-13:1-3.5:47-55, add deionized water and nitric acid to absolute ethanol to prepare transparent solution B;

(3) Add diatomite to deionized water and stir to form a suspension, then add metal nitrate solution with a concentration of 1 to 10 mol/L to the suspension, mix and stir evenly, so that the mass concentration of metal ions is 0 to 5 %, and then add a sodium hydroxide ethanol solution with a concentration of 1 to 5 mol/L until the metal ions are converted into metal hydroxides to form a mixed suspension C;

(4) According to the volume ratio of solution A, solution B and mixed suspension C of 78～82:58～64:105～114, the solution B obtained in step (2) and the mixed suspension C obtained in step (3) are sequentially Add it into the solution A obtained in step (1) at a rate of 0.1-1.0ml/min, and stir it for 0.5-1h, then let it stand for aging to form a gel;

(5) Drying the gel obtained in step (4), and then heat-treating after drying to obtain a TiO ₂ /diatomite composite photocatalytic material.

When the obtained TiO ₂ /diatomite composite photocatalytic material is cooled to room temperature, it can be ground into powder as required; and it can be mixed with interior paint and whitening agent and applied on the wall surface to remove formaldehyde and other harmful gases according to user needs. , It has anti-mildew and anti-bacterial ability, and its powder products can also be used to control the field of organic water pollution.

The butyl titanate, absolute ethanol and glacial acetic acid in the step (1) are commercially available and of analytical grade. the

The nitric acid and absolute ethanol in the step (2) are commercially available analytically pure. the

The suspension in the step (3) is formed by stirring and mixing diatomite and deionized water at a solid-to-liquid ratio (g/mL) of 1-20:100. the

The metal nitrate solution in the step (3) is a metal nitrate solution of one or more of Fe, Cr, La, Ce and Al. the

The standing aging in the step (4) is aging at room temperature for 1-4 hours. the

The drying in the step (5) is at 50-100° C. for 1-5 hours. the

The heat treatment temperature in the step (5) is 500-700° C., and the temperature is kept for 1-6 hours. the

The invention provides a preparation method of TiO ₂ /diatomite composite photocatalytic material with simple preparation, low cost, visible light activity, high photocatalytic degradation rate and obvious shift of absorption band edge to visible light range. The preparation method is simple, low-cost, and has no secondary pollution. The TiO ₂ /diatomite composite photocatalytic material has visible light activity, high photocatalytic degradation rate and obvious shift of absorption edge to the visible light range, and has excellent visible light photocatalytic activity. The prepared powder catalyst can be mixed with indoor paint and whitening agent and coated on the surface of the inner wall according to the user's needs. It can remove harmful gases such as formaldehyde, and has anti-mildew and antibacterial capabilities. Its powder products can be used to treat organic water pollution.

Description of drawings

Fig. 1 is a schematic diagram of the process flow of the present invention. the

Detailed ways

The present invention will be further described below in conjunction with the examples. the

Example 1

(1) According to the volume ratio of butyl titanate, absolute ethanol and glacial acetic acid as 25:50:5, add analytical pure butyl titanate to analytical pure absolute ethanol, then add analytical pure glacial acetic acid, and then stir 30min to form a light yellow transparent solution A;

(2) According to the volume ratio of deionized water, analytically pure nitric acid and analytically pure absolute ethanol as 10:2:50, take deionized water and nitric acid and add them to absolute ethanol to obtain a transparent solution B;

(3) Stir diatomaceous earth and deionized water at a solid-to-liquid ratio (g/mL) of 8:100 to form a suspension, then add 1 mL of ferric nitrate solution with a concentration of 3 mol/L to the suspension, mix and stir evenly , so that the mass concentration of metal ions is 1%, and then adding a sodium hydroxide ethanol solution with a concentration of 5mol/L to it, until the metal ions are converted into metal hydroxides to form a mixed suspension C;

(4) According to the volume ratio of solution A, solution B and mixed suspension C as 80:60:110, the solution B obtained in step (2) and the mixed suspension C obtained in step (3) are sequentially mixed at 0.5ml/min Add it to the solution A obtained in step (1) at a high speed, and stir for 0.5h, then leave it at room temperature for 2h to form a gel;

(5) The gel obtained in step (4) was dried at 100° C. for 1 hour, and then heat-treated at 600° C. and kept for 4 hours to obtain a TiO ₂ /diatomite composite photocatalytic material. The absorption band edge of the Fe-doped TiO ₂ /diatomite composite photocatalyst material is obviously shifted to the visible light range, the forbidden band width is 2.85eV, and the absorption band is 423nm, showing good visible light activity.

Example 2

(1) According to the volume ratio of butyl titanate, absolute ethanol and glacial acetic acid as 20:48:2, add analytical pure butyl titanate to analytical pure absolute ethanol, then add analytical pure glacial acetic acid, and then stir 20min to form a light yellow transparent solution A;

(2) According to the volume ratio of deionized water, analytically pure nitric acid and analytically pure absolute ethanol as 13:3.5:47, take deionized water and nitric acid and add them to absolute ethanol to prepare a transparent solution B;

(3) Stir diatomite and deionized water at a solid-to-liquid ratio (g/mL) of 1:100 to form a suspension, then add lanthanum nitrate solution with a concentration of 1mol/L to the suspension, mix and stir evenly, Make the mass concentration of metal ions 0-5%, and then add a sodium hydroxide ethanol solution with a concentration of 3mol/L to it until the metal ions are converted into metal hydroxides to form a mixed suspension C;

(4) According to the volume ratio of solution A, solution B and mixed suspension C of 78:58:105, the solution B obtained in step (2) and the mixed suspension C obtained in step (3) are sequentially mixed at 1.0ml/min Add it to the solution A obtained in step (1) at a high speed, and stir for 0.8h, and then stand and age at room temperature for 1h to form a gel;

(5) The gel obtained in step (4) was dried at 80° C. for 3 hours, and then heat-treated at 500° C. and kept for 6 hours after drying to obtain a TiO ₂ /diatomite composite photocatalytic material. The absorption band edge of the La-doped TiO ₂ /diatomite composite photocatalyst material shifts to the visible light range obviously, the forbidden band width is 3.03eV, and the absorption band is 401nm, showing certain visible light activity.

Example 3

(1) According to the volume ratio of butyl titanate, absolute ethanol and glacial acetic acid as 28:54:8, add analytical pure butyl titanate to analytical pure absolute ethanol, then add analytical pure glacial acetic acid, and then stir 50min to form a light yellow transparent solution A;

(2) According to the volume ratio of deionized water, analytically pure nitric acid and analytically pure absolute ethanol as 8:1:55, take deionized water and nitric acid and add them to absolute ethanol to obtain a transparent solution B;

(3) Stir diatomite and deionized water at a solid-to-liquid ratio (g/mL) of 12:100 to form a suspension, then add metal aluminum nitrate solution with a concentration of 6mol/L to the suspension, mix and stir evenly , so that the mass concentration of metal ions is 0 to 5%, and then adding a sodium hydroxide ethanol solution with a concentration of 5 mol/L to it, until the metal ions are converted into metal hydroxides to form a mixed suspension C;

(4) According to the volume ratio of solution A, solution B and mixed suspension C of 82:64:114, the solution B obtained in step (2) and the mixed suspension C obtained in step (3) are sequentially mixed at 0.5ml/min Add it to the solution A obtained in step (1) at a high speed, and stir it for 0.5h, then leave it to stand and age at room temperature for 3h to form a gel;

(5) The gel obtained in step (4) was dried at 50° C. for 5 hours, and then heat-treated at 650° C. and kept for 4 hours to obtain a TiO ₂ /diatomite composite photocatalytic material. The absorption band edge of the Al-doped TiO ₂ /diatomite composite photocatalyst material shifts to the visible light range obviously, the forbidden band width is 3.06eV, and the absorption band is 390nm, showing certain visible light activity.

Example 4

(1) According to the volume ratio of butyl titanate, absolute ethanol and glacial acetic acid as 23:52:7, add analytical pure butyl titanate to analytical pure absolute ethanol, then add analytical pure glacial acetic acid, and then stir 30min to form a light yellow transparent solution A;

(2) According to the volume ratio of deionized water, analytically pure nitric acid and analytically pure absolute ethanol as 9:3.5:55, take deionized water and nitric acid and add them to absolute ethanol to obtain a transparent solution B;

(3) Stir diatomite and deionized water at a solid-to-liquid ratio (g/mL) of 15:100 to form a suspension, then add 0.5ml of aluminum nitrate with a concentration of 6mol/L and 0.5ml of aluminum nitrate with a concentration of 3mol/L ferric nitrate mixed solution, mix and stir evenly, so that the mass concentration of metal ions is 0-5%, and then add sodium hydroxide ethanol solution with a concentration of 5mol/L to it, until the metal ions are transformed into metal hydroxides , forming a mixed suspension C;

(4) According to the volume ratio of solution A, solution B and mixed suspension C of 78:64:105, the solution B obtained in step (2) and the mixed suspension C obtained in step (3) are sequentially mixed at 0.5ml/min Add it to the solution A obtained in step (1) at a high speed, and stir it for 1 hour, then leave it to stand and age at room temperature for 2 hours to form a gel;

(5) The gel obtained in step (4) was dried at 60°C for 2 hours, and then heat-treated at 700°C and kept for 2 hours after drying to obtain a TiO ₂ /diatomite composite photocatalytic material. The absorption band edge of Al and Fe co-doped TiO ₂ /diatomite composite photocatalytic material shifts to the visible light range obviously, the forbidden band width is 2.72eV, and the absorption band is 435nm, showing obvious visible light catalytic activity.

Example 5

(1) According to the volume ratio of butyl titanate, absolute ethanol and glacial acetic acid as 28:48:6, add analytical pure butyl titanate to analytical pure absolute ethanol, then add analytical pure glacial acetic acid, and then stir 50min to form a light yellow transparent solution A;

(2) According to the volume ratio of deionized water, analytically pure nitric acid and analytically pure absolute ethanol as 8:1:49, add deionized water and nitric acid to absolute ethanol to obtain a transparent solution B;

(3) Stir diatomite and deionized water at a solid-to-liquid ratio (g/mL) of 20:100 to form a suspension, then add chromium nitrate and cerium nitrate solutions with a concentration of 10mol/L to the suspension, and mix Stir evenly so that the mass concentration of metal ions is 0-5%, and then add sodium hydroxide ethanol solution with a concentration of 1mol/L to it until the metal ions are converted into metal hydroxides to form a mixed suspension C;

(4) According to the volume ratio of solution A, solution B and mixed suspension C of 82:62:110, the solution B obtained in step (2) and the mixed suspension C obtained in step (3) are sequentially mixed at 0.1ml/min Add it to the solution A obtained in step (1) at a high speed, and stir it for 1 hour, and then leave it at room temperature for 4 hours to form a gel;

(5) The gel obtained in step (4) was dried at 100°C for 3 hours, and after drying, it was heat-treated at 700°C and kept for 1 hour to obtain a TiO ₂ /diatomite composite photocatalytic material. The absorption band edge of the Cr and Ce co-doped TiO ₂ /diatomite composite photocatalytic material shifts to the visible light range obviously, the forbidden band width is 2.92eV, and the absorption band is 405nm, showing obvious visible light catalytic activity.

Claims (8)

1. a sol-gel process prepares TiO ₂the method of/diatomite composite photocatalytic material, is characterized in that through following each step:

(1) be 20 ~ 28:48 ~ 54:2 ~ 8 by the volume ratio of butyl titanate, absolute ethyl alcohol and glacial acetic acid, butyl titanate joined in absolute ethyl alcohol, then adds glacial acetic acid, then stir the solution A that 20 ~ 50min forms pale yellow transparent;

(2) be 8 ~ 13:1 ~ 3.5:47 ~ 55 by the volume ratio of deionized water, nitric acid and absolute ethyl alcohol, remove ionized water, nitric acid joins solution B obtained transparent in absolute ethyl alcohol;

(3) diatomite is joined deionized water for stirring and become suspension, then in suspension, the metal-nitrate solutions that concentration is 1 ~ 10mol/L is added, mixing and stirring, the mass concentration of metal ion is made to be 0 ~ 5%, add the NaOH ethanolic solution that concentration is 1 ~ 5mol/L more wherein, until make metal ion change metal hydroxides into, form mixing suspension C;

(4) be 78 ~ 82:58 ~ 64:105 ~ 114 by the volume ratio of solution A, solution B and mixing suspension C, the mix suspending C of the solution B of step (2) gained and step (3) gained is joined with the speed of 0.1 ~ 1.0ml/min in the solution A of step (1) gained successively, and with stirring 0.5 ~ 1h, more still aging rear formation gel;

(5) step (4) gained gel is carried out drying, after drying, namely obtain TiO through Overheating Treatment ₂/ diatomite composite photocatalytic material.

2. sol-gel process according to claim 1 prepares TiO ₂the method of/diatomite composite photocatalytic material, is characterized in that: it is pure that the butyl titanate of described step (1), absolute ethyl alcohol and glacial acetic acid are commercial analysis.

3. sol-gel process according to claim 1 prepares TiO ₂the method of/diatomite composite photocatalytic material, is characterized in that: it is pure that the nitric acid of described step (2) and absolute ethyl alcohol are commercial analysis.

4. sol-gel process according to claim 1 prepares TiO ₂the method of/diatomite composite photocatalytic material, is characterized in that: the suspension of described step (3) is diatomite and deionized water is that 1 ~ 20:100 carries out being uniformly mixed forming by solid-to-liquid ratio.

5. sol-gel process according to claim 1 prepares TiO ₂the method of/diatomite composite photocatalytic material, is characterized in that: the metal-nitrate solutions of described step (3) is one or more the metal-nitrate solutions in Fe, Cr, La, Ce and Al.

6. sol-gel process according to claim 1 prepares TiO ₂the method of/diatomite composite photocatalytic material, is characterized in that: described step (4) still aging is at room temperature ageing 1 ~ 4h.

7. sol-gel process according to claim 1 prepares TiO ₂the method of/diatomite composite photocatalytic material, is characterized in that: the drying of described step (5) is dry 1 ~ 5h at 50 ~ 100 DEG C.

8. sol-gel process according to claim 1 prepares TiO ₂the method of/diatomite composite photocatalytic material, is characterized in that: the heat treatment temperature of described step (5) is 500 ~ 700 DEG C, insulation 1 ~ 6h.