Manganese-based perovskite / TiO2 composite photocatalyst as well as preparation method and application thereof

Abstract

The invention provides a manganese-based perovskite / TiO2 composite photocatalyst as well as a preparation method and application thereof, and relates to the technical field of photocatalysts. The preparation method comprises the following steps: preparing a polymethyl methacrylate colloidal microsphere suspension solution through an emulsion polymerization method, and centrifuging to obtain a three-dimensionally arranged colloidal crystal template; mixing cerous nitrate, lanthanum nitrate, manganese nitrate and water to prepare a perovskite precursor solution; adding the precursor solution, the TiO2 slurry and a surfactant into a template, stirring, and removing a solvent to obtain a composite intermediate; and finally, calcining the composite intermediate at high temperature to remove the template to form the 3DOM manganese-based perovskite / TiO2 composite photocatalyst. Compared with single manganese-based perovskite and TiO2 catalysts, the manganese-based perovskite / TiO2 composite catalyst disclosed by the invention has better degradation effect and cycling stability on antibiotics represented by tetracycline, and the preparation method is simple, easy to operate and convenient for practical application.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysts, and in particular to a manganese-based perovskite / TiO 2 Composite photocatalyst and its preparation method and application. Background Art

[0002] Antibiotics have the effect of inhibiting or killing various pathogens or harmful microorganisms, so they are widely used in human disease treatment, animal husbandry and aquaculture, agricultural production and other fields.

[0003] Common treatment methods for antibiotic wastewater include: physical treatment, chemical oxidation, biological treatment and a combination of treatment methods. Among them, chemical oxidation can use groups or substances with strong oxidizing properties to degrade antibiotics dissolved in water. The method is simple to operate, has low energy consumption, and is not selective for wastewater. It has greater advantages than other processes in treating antibiotic wastewater. Among them, photocatalytic oxidation technology has low energy consumption, simple operation, mild reaction conditions and no secondary pollution. It is an antibiotic wastewater treatment technology with broad development prospects.

[0004] TiO 2 It is the most common photocatalyst at present, but due to its large bandgap and almost no visible light absorption, the photocatalytic degradation efficiency is low. Most of the other new photocatalysts have complex synthesis methods and are expensive, which is not conducive to large-scale production and promotion and application.

[0005] As a new type of functional material, perovskite metal oxides have widely available raw materials, simple synthesis methods, stable crystal structures, and high redox, hydrogenolysis, isomerization, and electrocatalytic activities. They have great development potential in the fields of environmental protection and industrial catalysis. However, due to the large microscopic scale of single-phase perovskites, the photogenerated electron-hole recombination rate is fast and the catalytic efficiency is low.

[0006] Three-dimensional ordered macroporous structure (3DOM) perovskite material is a perovskite material with unique structure and excellent performance. 3DOM perovskite material combines the advantages of 3DOM structure and perovskite material, with high specific surface area and number of active sites, but its structure is unstable, resulting in reduced overall stability of the material.

[0007] Therefore, how to overcome the existing TiO 2 In order to solve the problems existing in 3DOM perovskite materials and obtain a composite photocatalyst with good stability, it is one of the technical problems to be solved urgently in the treatment of antibiotic wastewater. Summary of the invention

[0008] In view of this, the present invention provides a manganese-based perovskite / TiO 2Composite photocatalyst and its preparation method and application. The present invention combines manganese-based perovskite and TiO 2 The composite was made and the process parameters in the preparation process were adjusted to overcome the single manganese-based perovskite and TiO 2 By overcoming the shortcomings of the catalyst, an aqueous antibiotic catalyst with good degradation effect and cyclic stability was obtained.

[0009] The manganese-based perovskite / TiO 2 The preparation method of the composite photocatalyst comprises the following steps:

[0010] (1) obtaining a polymethyl methacrylate (PMMA) colloidal microsphere suspension solution by an emulsion polymerization method, and centrifuging the PMMA colloidal microsphere suspension solution to obtain a three-dimensionally arranged colloidal crystal template;

[0011] (2) mixing cerium nitrate, lanthanum nitrate, manganese nitrate and water in proportion to obtain a perovskite precursor solution;

[0012] (3) The perovskite precursor solution, TiO 2 Adding slurry and surfactant to the colloidal crystal template, stirring thoroughly and removing the solvent to obtain a composite intermediate;

[0013] (4) calcining the composite intermediate at high temperature to remove the colloidal crystal template to form 3DOM manganese-based perovskite / TiO 2 Composite photocatalyst.

[0014] Furthermore, the molar ratio of cerium nitrate, lanthanum nitrate and manganese nitrate in the perovskite precursor solution is (6-4):(4-6):1, and the total ion concentration in the perovskite precursor solution is 1-4 mol / L. Preferably, the total ion concentration in the perovskite precursor solution is 2 mol / L.

[0015] Furthermore, the TiO 2 The slurry is water-based nano-TiO with a particle size of ≤50nm 2 Slurry.

[0016] Furthermore, the surfactant is a polyoxyethylene fatty alcohol ether nonionic surfactant.

[0017] Furthermore, the mass volume ratio of the three-dimensionally arranged colloidal crystal template to the perovskite precursor solution is 150-250 g / L.

[0018] Furthermore, the mass ratio of the water to the surfactant is 1:(0.003-0.006).

[0019] Furthermore, the high temperature calcination temperature is 600°C to 800°C, and the high temperature calcination time is 4 to 5 hours.

[0020] Furthermore, the manganese-based perovskite / TiO 2 In the composite photocatalyst, TiO 2 The mass fraction is 20% to 50%.

[0021] The present invention also provides a manganese-based perovskite / TiO prepared according to the above method. 2 Composite photocatalyst.

[0022] The manganese-based perovskite / TiO 2 Composite photocatalysts are used for the degradation of antibiotics in water, especially the degradation of tetracycline in water.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] Compared with single Mn-based perovskite and TiO 2 Compared with the catalyst, the manganese-based perovskite / TiO 2 The composite catalyst has better degradation effect and cyclic stability on antibiotics represented by tetracycline, and the preparation method is simple, easy to operate, and convenient for practical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Figure 1 Mn-based perovskite / TiO 2 The catalytic performance test results of the composite photocatalyst, where a is the catalyst adsorption-degradation tetracycline performance test result, and b is the first-order kinetic curve of the catalyst tetracycline degradation.

[0027] Figure 2 Mn-based perovskite / TiO 2 Stability experimental results of composite photocatalyst. DETAILED DESCRIPTION

[0028] The technical solution provided by the present invention is further described below in conjunction with embodiments.

[0029] The TiO used in the embodiment of the present invention 2 The slurry is a water-based slurry, the model is McLean T914089, the TiO 2 The particle size of water-based slurry is ≤50nm.

[0030] Example 1 A manganese-based perovskite / TiO 2 The preparation method of the composite photocatalyst comprises the following steps:

[0031] (1) obtaining a PMMA colloidal microsphere suspension solution by emulsion polymerization and then centrifuging it to obtain a three-dimensionally arranged colloidal crystal template;

[0032] (2) mixing cerium nitrate, lanthanum nitrate and manganese nitrate with water in a molar ratio of 6:4:1, adjusting the total ion concentration in the solution to 2 mol / L, and obtaining a perovskite precursor solution;

[0033] (3) 500 mL of perovskite precursor solution, 405 g of TiO 2 For aqueous slurry, 0.003 g of polyoxyethylene lauryl ether was added to 85 g of colloidal crystal template and stirred thoroughly to allow the precursor liquid ions and TiO 2 The slurry is fully filled into the gaps between the colloidal microspheres, and the excess solvent is removed by drying at 70° C. to obtain a composite intermediate;

[0034] (4) The composite intermediate was calcined at 600°C for 4 hours to remove the colloidal crystal template, thereby obtaining a Ce with a three-dimensional ordered macroporous structure. 0.6 La 0.4 MnO 3 / TiO 2 Composite materials.

[0035] Example 2 A manganese-based perovskite / TiO 2 The preparation method of the composite photocatalyst comprises the following steps:

[0036] (1) obtaining a PMMA colloidal microsphere suspension solution by emulsion polymerization and then centrifuging it to obtain a three-dimensionally arranged colloidal crystal template;

[0037] (2) mixing cerium nitrate, lanthanum nitrate and manganese nitrate with water in a molar ratio of 5:5:1, adjusting the total ion concentration in the solution to 2 mol / L, and obtaining a perovskite precursor solution;

[0038] (3) 500 mL of perovskite precursor solution, 350 g of TiO 2 For aqueous slurry, 0.003 g of polyoxyethylene lauryl ether was added to 85 g of colloidal crystal template and stirred thoroughly to allow the precursor liquid ions and TiO 2 The slurry is fully filled into the gaps between the colloidal microspheres, and the excess solvent is removed by drying at 70° C. to obtain a composite intermediate;

[0039] (4) The composite intermediate was calcined at 600°C for 4 hours to remove the colloidal crystal template, thereby obtaining a Ce with a three-dimensional ordered macroporous structure. 0.5 La 0.5 MnO 3 / TiO 2 Composite materials.

[0040] Comparative Example 1 A method for preparing a manganese-based perovskite photocatalyst, the steps are as follows:

[0041] (1) obtaining a PMMA colloidal microsphere suspension solution by emulsion polymerization, and obtaining a three-dimensionally arranged colloidal crystal template by centrifugation;

[0042] (2) mixing cerium nitrate, lanthanum nitrate and manganese nitrate with water in a molar ratio of 6:4:1, adjusting the total ion concentration in the solution to 2 mol / L, and obtaining a perovskite precursor solution;

[0043] (3) adding 500 mL of the perovskite precursor solution to 85 g of the colloidal crystal template, stirring thoroughly to allow the precursor solution ions to fully fill the gaps between the colloidal microspheres, and drying at 70° C. to remove excess solvent to form a composite intermediate;

[0044] (4) After calcination at 600℃ for 4h, the colloidal crystal template was removed to obtain Ce with a three-dimensional ordered macroporous structure. 0.6 La 0.4 MnO 3 Manganese-based perovskite materials.

[0045] Test Example 1 Performance Test

[0046] The degradation performance of the catalysts obtained in Examples 1-2 and Comparative Example 1 was tested as follows:

[0047] Weigh 30 mg of catalyst and disperse it into a reactor containing 40 mL of 50 mg / L tetracycline solution. Before the degradation experiment, stir in the dark for 40 minutes to allow the catalytic material to reach adsorption saturation for tetracycline, then stir and react for 1 hour under 300W (λ≥400nm) xenon lamp irradiation for photocatalytic degradation. Take out the reaction solution at regular intervals, centrifuge and filter with a 0.22μm filter membrane, and finally measure its absorbance with a spectrophotometer. The test results are as follows: Figure 1 shown.

[0048] The stability of the catalysts obtained in Examples 1-2 and Comparative Example 1 was tested as follows:

[0049] The solution after the catalytic reaction was centrifuged to remove the supernatant, leaving the catalyst remaining at the bottom, adding pure water and ultrasonic cleaning at 200W for 5 minutes, centrifuging again, and repeating the cleaning for more than three times. The catalyst was dried in a forced air drying oven at 70°C for 4 hours to complete the regeneration of the catalyst. After drying, the test was repeated according to the above degradation performance test method to evaluate the stability of the catalyst.

[0050] Test results such as Figure 2 shown.

[0051] Depend on Figure 1 It can be seen that, with Ce 0.6 La 0.4 MnO 3Compared with the manganese-based perovskite material, the manganese-based perovskite / TiO 2 The adsorption performance of the composite catalyst was slightly improved, while the degradation rate was significantly increased, increasing from 65% to 93% at 80 minutes of reaction.

[0052] Depend on Figure 2 It can be seen that Ce 0.6 La 0.4 MnO 3 After the manganese-based perovskite material was recycled for 5 times, the catalytic efficiency dropped from the initial 65% to 25%. 2 After being recycled 10 times, the catalytic efficiency of the composite catalyst can still be maintained above 85%, showing better stability and being more conducive to practical application.

[0053] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing a manganese-based perovskite / TiO2 composite photocatalyst, characterized in that: The following steps are involved: (1) obtaining a polymethyl methacrylate colloidal microsphere suspension solution by an emulsion polymerization method, and centrifuging the polymethyl methacrylate colloidal microsphere suspension solution to obtain a three-dimensionally arranged colloidal crystal template; (2) mixing cerium nitrate, lanthanum nitrate, manganese nitrate and water in proportion to obtain a perovskite precursor solution; (3) adding the perovskite precursor solution, TiO2 slurry, and surfactant to the colloidal crystal template, stirring thoroughly and removing the solvent to obtain a composite intermediate; (4) calcining the composite intermediate at high temperature to remove the colloidal crystal template and form a 3DOM manganese-based perovskite / TiO2 composite photocatalyst.

2. The preparation method according to claim 1, characterized in that: The molar ratio of cerium nitrate, lanthanum nitrate and manganese nitrate in the perovskite precursor solution is (6-4):(4-6):1, and the total ion concentration in the perovskite precursor solution is 1-4 mol / L.

3. The preparation method according to claim 1, characterized in that: The surfactant is a polyoxyethylene fatty alcohol ether type nonionic surfactant.

4. The preparation method according to claim 1, characterized in that: The mass volume ratio of the three-dimensionally arranged colloidal crystal template to the perovskite precursor solution is 150-250 g / L.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the water to the surfactant is 1:(0.003-0.006).

6. The preparation method according to claim 1, characterized in that: The high temperature calcination temperature is 600° C. to 800° C., and the high temperature calcination time is 4 to 5 hours.

7. The preparation method according to claim 1, characterized in that: The mass fraction of TiO2 in the manganese-based perovskite / TiO2 composite photocatalyst is 20% to 50%.

8. A manganese-based perovskite / TiO2 composite photocatalyst, characterized in that: Prepared by the method according to any one of claims 1 to 8.

9. The manganese-based perovskite / TiO2 composite photocatalyst according to claim 8 is used for the degradation of antibiotics in water.

10. The use according to claim 9, characterized in that: The antibiotic is tetracycline.

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