Preparation method of composite photocatalyst and composite photocatalyst
By preparing the composite photocatalyst Ag/Ag2O/N-TiO2, the existing photocatalytic reduction method has solved the problems of low reaction efficiency and high cost, and efficiently remove nitrate nitrogen in water under visible light, reducing the treatment cost.
Patent Information
- Application Number
- CN202411835719.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-21
AI Technical Summary
The existing photocatalytic reduction methods have low reaction efficiency at room temperature, high cost, and are difficult to effectively remove nitrate nitrogen in water.
By mixing titanium nitride particles with silver nitrate solution, and preparing the composite photocatalyst Ag/Ag2O/N-TiO2 through centrifugation and calcination, the reaction efficiency under visible light is improved.
The composite photocatalyst has a wide wavelength adsorption range, which improves the light quantum generation concentration under visible light, significantly improves the photocatalytic reaction efficiency, and reduces costs.
Smart Images
Figure CN119657197A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of environmental functional materials, and in particular to a preparation method of a composite photocatalyst and a composite photocatalyst. Background Art
[0002] Nitrate nitrogen has high solubility in water and stable chemical properties. It can accumulate in water bodies for a long time. It is easy to turn into nitrite when entering the human body. It is highly toxic. The country has recently revised the emission standard and limited it to 10 mg / L (GB 5749-2006). It is difficult to remove it with traditional water treatment processes (such as coagulation and filtration). Although the ion exchange (IX) and reverse osmosis (RO) methods can achieve better nitrate nitrogen removal effects, the processing capacity is limited and the subsequent treatment of the concentrated waste brine produced must be faced. The most ideal treatment method is to selectively reduce nitrate nitrogen into non-toxic and harmless nitrogen gas, thereby completing the natural cycle of nitrogen, which has become a hot topic of research.
[0003] The photocatalytic reduction method has attracted much attention in recent years due to its advantages such as operating at room temperature and pressure and being clean and free of secondary pollution. However, in the existing technology, the photocatalytic reaction efficiency is low, resulting in a low reaction conversion rate. In addition, the lighting conditions for the photocatalytic reduction method are mostly ultraviolet light, and the utilization rate of sunlight is low, so the cost is high.
[0004] Therefore, how to provide a preparation method of a composite photocatalyst and a composite photocatalyst to improve the photocatalytic reaction efficiency and reduce the cost is a technical problem that needs to be solved urgently in this application. Summary of the invention
[0005] The purpose of the present application is to provide a method for preparing a composite photocatalyst and a composite photocatalyst to improve the photocatalytic reaction efficiency and reduce costs.
[0006] In order to achieve the above object, the present application proposes a method for preparing a composite photocatalyst, comprising the following steps:
[0007] Adding a preset mass of titanium nitride particles into a preset concentration of silver nitrate solution for mixing and stirring to obtain a suspension;
[0008] The suspension is centrifuged to separate and obtain a precipitate;
[0009] The precipitate is calcined to obtain a composite photocatalyst.
[0010] Further preferably, the concentration of the silver nitrate solution is 0.5-2 mol / L.
[0011] Further preferably, the concentration of the silver nitrate solution is 1-1.5 mol / L.
[0012] Further preferably, the calcination temperature is 400-600°C.
[0013] And / or, the calcination treatment time is 1 to 3 hours.
[0014] Further preferably, the mass volume ratio of the titanium nitride particles to the silver nitrate solution is 0.0025-0.01 g / mL.
[0015] Further preferably, the step of adding a preset mass of titanium nitride particles into a preset concentration of silver nitrate solution for mixing and stirring to obtain a suspension comprises:
[0016] Adding a preset mass of titanium nitride particles into a preset concentration of silver nitrate solution, mixing the obtained mixed solution and subjecting the mixed solution to ultrasonic dispersion treatment for at least 2 hours;
[0017] The mixed solution after ultrasonic dispersion treatment was magnetically stirred for at least 1 h.
[0018] Further preferably, after centrifuging the suspension, the step of separating and obtaining a precipitate comprises:
[0019] First, the suspension is centrifuged to obtain a sediment;
[0020] The sediment is washed with deionized water for multiple times and then dried to obtain the precipitate.
[0021] Preferably, the temperature of the drying treatment is such that the precipitate does not undergo chemical modification and the catalytic performance does not fail.
[0022] Further preferably, the temperature of the drying treatment is 60-70° C.; and the drying time of the drying treatment is more than 12 hours.
[0023] Further preferably, the drying temperature is 60°C.
[0024] Further preferably, the step of obtaining the composite photocatalyst after calcining the precipitate comprises:
[0025] The precipitate is placed in a muffle furnace and calcined for 2 to 3 hours to obtain a residue;
[0026] In a light-proof environment, the residue is ground and then screened with a 100-200 mesh sieve to obtain a composite photocatalyst.
[0027] The present application also provides a composite photocatalyst, which is prepared by the above-mentioned composite photocatalyst preparation method.
[0028] Compared with the prior art, the composite photocatalyst prepared in the present application has a wider wavelength adsorption range and increases the concentration of photons generated under visible light, thereby improving the photocatalytic reaction efficiency and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 Flow chart of the preparation method of the composite photocatalyst in this application;
[0030] Figure 2 UV-visible diffuse reflectance spectra of different catalysts (P25, N-TiO2, Ag / Ag2O / N-TiO2);
[0031] Figure 3 XRD patterns of different photocatalysts (N-TiO2, Ag / Ag2O / N-TiO2). DETAILED DESCRIPTION
[0032] The preparation method of the composite photocatalyst of the present application will be described in more detail below in conjunction with the schematic diagram, wherein the preferred embodiment of the present application is shown, and it should be understood that those skilled in the art can modify the present application described herein, and still achieve the beneficial effects of the present application. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation to the present application.
[0033] In some embodiments of the present invention, the method for preparing the composite photocatalyst comprises the following steps:
[0034] Step S1: in a light-proof environment, adding a preset mass of titanium nitride particles into a preset concentration of silver nitrate solution for mixing and stirring to obtain a suspension;
[0035] Step S2: centrifuging the suspension to obtain a precipitate;
[0036] Step S3: calcining the precipitate to obtain a composite photocatalyst.
[0037] Here, it should be noted that the light-proof environment in this embodiment is a weak light or dark environment, and the light intensity is preferably 50-100 lux, or less than 50 lux.
[0038] The preparation method of the composite photocatalyst is described in detail below in conjunction with specific embodiments:
[0039] Example 1
[0040] Step 1: Add 2 g TiN into 200 mL of 1 mol / L AgNO3 solution, disperse by ultrasonic for 2 h and continue magnetic stirring for 1 h;
[0041] Step 2: centrifuge the dispersed suspension and wash the obtained sediment with deionized water three times, and dry the solid obtained after washing at 60° C. for 12 h;
[0042] Step 3: calcine the product in step 2 in a muffle furnace at 500°C for 2h, grind it, and sieve it with a 200-mesh sieve to obtain light gray Ag / Ag2O / N-TiO2.
[0043] Example 2
[0044] Step 1: Add 1 g TiN into 200 mL of 1 mol / L AgNO3 solution, disperse by ultrasonic for 2 h and continue magnetic stirring for 1 h;
[0045] Step 2: centrifuge the dispersed suspension and wash the obtained sediment with deionized water three times, and dry the solid obtained after washing at 60° C. for 12 h;
[0046] Step 3: calcine the product in step 2 in a muffle furnace at a temperature of 500°C for 2 hours, grind it, and screen it with a 200-mesh sieve to obtain a composite photocatalyst, that is, a light gray product with a material composition of Ag / Ag2O / N-TiO2.
[0047] Example 3
[0048] Step 1: Add 2 g TiN into 200 mL of 1.5 mol / L AgNO3 solution, disperse by ultrasonic for 2 h and continue magnetic stirring for 1 h;
[0049] Step 2: centrifuge the dispersed suspension and wash the obtained sediment with deionized water three times, and dry the solid obtained after washing at 60° C. for 12 h;
[0050] Step 3: calcine the product in step 2 in a muffle furnace at a temperature of 500°C for 2 hours, grind it, and screen it with a 200-mesh sieve to obtain a composite photocatalyst, that is, a light gray product with a material composition of Ag / Ag2O / N-TiO2.
[0051] Example 4
[0052] Step 1: Add 2 g TiN into 200 mL of 1 mol / L AgNO3 solution, disperse by ultrasonic for 2 h and continue magnetic stirring for 1 h;
[0053] Step 2: centrifuge the dispersed suspension and wash the obtained sediment with deionized water three times, and dry the solid obtained after washing at 60° C. for 12 h;
[0054] Step 3: calcine the product in step 2 in a muffle furnace at 600°C for 2h, grind it, and sieve it with a 200-mesh sieve to obtain a composite photocatalyst, that is, a light gray product with a material composition of Ag / Ag2O / N-TiO2.
[0055] Example 5
[0056] Step 1: Add 2 g TiN into 200 mL of 1 mol / L AgNO3 solution, disperse by ultrasonic for 2 h and continue magnetic stirring for 1 h;
[0057] Step 2: centrifuge the dispersed suspension and wash the obtained sediment with deionized water three times, and dry the solid obtained after washing at 60° C. for 12 h;
[0058] Step 3: calcine the product in step 2 in a muffle furnace at 500°C for 1 hour, grind it, and sieve it with a 200-mesh sieve to obtain a composite photocatalyst, that is, a light gray product with a material composition of Ag / Ag2O / N-TiO2.
[0059] Performance test results:
[0060] UV-Vis diffuse reflectance spectra: The Ag / Ag2O / N-TiO2 samples in Example 1 and Example 2 were marked as A and B, respectively, and tested separately, and compared with the catalyst composed of P25 and the catalyst composed of N-TiO2.
[0061] XRD (X-ray diffraction) spectrum test: The Ag / Ag2O / N-TiO2 samples in Example 1 and Example 2 were marked as A and B, respectively, and tested separately, and compared with the catalyst composed of P25 and the catalyst composed of N-TiO2.
[0062] Visible light source: 500W xenon lamp with filter (for filtering light below 420nm),
[0063] The composite photocatalysts prepared in Examples 1 to 5 were applied to remove nitrate nitrogen from water, and tested according to the following steps:
[0064] Step 1: Add 0.1 g Ag / Ag2O / N-TiO2 into 100 mL of 25 mg.N / L potassium nitrate solution and mix;
[0065] Step 2: In a dark environment, stir the mixed solution in step 1 for 30 minutes, add 0.15 mL of HCOOH, then introduce argon for 30 minutes, and place under a visible light source for catalytic reaction for 2 hours under magnetic stirring, wherein the conditions for the catalytic reaction are: temperature 25°C, magnetic stirring speed 150 rpm.
[0066] Table 1 Nitrate nitrogen reduction performance data of Ag / Ag2O / N-TiO2 composite photocatalysts prepared in Examples 1 to 5
[0067] Composite photocatalyst Example 1 Example 2 Example 3 Example 4 Example 5 NO3- removal rate (%) 89.3 78.90 88.4 86.5 67.62 N2 selectivity (%) 85.7 82.1 83.7 88.7 86.7
[0068] According to the experimental results in Table 1 and Figure 2 and Figure 3 It can be seen from the analysis that: by comparing the results of the embodiments, it can be seen that the present embodiment can achieve better Ag2O and modified TiO by using TiO2 with low cost, non-toxic and stable chemical properties to react with AgNO3 solution with preset molar concentration. 2， That is, N-TiO2 is compounded to form a pn heterojunction type composite photocatalyst with a wider wavelength adsorption range, and the concentration of photons generated under visible light and the photocatalytic reaction efficiency are increased, thereby reducing costs and having good nitrate nitrogen reduction and removal performance under visible light.
[0069] In addition, the novel Ag / Ag2O / N-TiO2 ternary catalyst with high visible light response activity prepared in this application can be synthesized by a simple "one-pot method", and the preparation process is simple and fast. The obtained catalyst has high efficiency in nitrate nitrogen reduction and can be used multiple times, and has good application prospects.
[0070] Moreover, under the condition of visible light, Ag2O is excited to generate electrons and holes to separate. Under the action of heterojunction, photogenerated electrons will transfer from the conduction band of silver oxide to the conduction band of titanium dioxide, and holes will remain in the valence band of silver oxide, thereby effectively preventing the recombination of electrons and holes, and synchronously exciting TiO2 to generate separation and transfer of electrons and holes, significantly improving the photon concentration, and greatly improving the catalytic efficiency under visible light. In addition, through the above reaction steps, the Ag2O generated by the partial reaction can be converted into single substance Ag (Ag2O is easily decomposed into Ag and O2 at a high temperature greater than 300°C), forming a ternary system of Ag / Ag2O / N-TiO2. Due to the different work functions, the electrons generated by the semiconductor material will transfer to metallic silver to improve the utilization efficiency of photogenerated electrons, and the surface plasma resonance of Ag will enhance the visible light response of the semiconductor material, so that the composite catalyst can better reduce and remove nitrate nitrogen in water, and realize its high selectivity to N2 to eliminate nitrate nitrogen.
[0071] The above are only preferred embodiments of the present application and do not have any limiting effect on the present application. Any technical personnel in the relevant technical field, without departing from the scope of the technical solution of the present application, may make any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present application, which shall be deemed as the content of the technical solution of the present application and still fall within the protection scope of the present application.
Claims
1. A method for preparing a composite photocatalyst, characterized in that: The following steps are involved: In a light-proof environment, adding a preset mass of titanium nitride particles into a preset concentration of silver nitrate solution for mixing and stirring to obtain a suspension; The suspension is centrifuged to separate and obtain a precipitate; The precipitate is calcined to obtain a composite photocatalyst.
2. The method for preparing the composite photocatalyst according to claim 1, characterized in that: The concentration of the silver nitrate solution is 0.5-2 mol / L.
3. The method for preparing the composite photocatalyst according to claim 1, characterized in that: The concentration of the silver nitrate solution is 1-1.5 mol / L.
4. The method for preparing the composite photocatalyst according to claim 1, characterized in that: The calcination temperature is 400-600°C; And / or, the calcination treatment time is 1 to 3 hours.
5. The method for preparing the composite photocatalyst according to claim 1, characterized in that: The mass volume ratio of the titanium nitride particles to the silver nitrate solution is 0.0025 to 0.01 g / mL.
6. The method for preparing the composite photocatalyst according to claim 1, characterized in that: The step of adding titanium nitride particles of a preset mass into a silver nitrate solution of a preset concentration for mixing and stirring to obtain a suspension comprises: Adding a preset mass of titanium nitride particles into a preset concentration of silver nitrate solution, mixing the obtained mixed solution and subjecting the mixed solution to ultrasonic dispersion treatment for at least 2 hours; The mixed solution after ultrasonic dispersion treatment was magnetically stirred for at least 1 h.
7. The method for preparing the composite photocatalyst according to claim 6, characterized in that: After the suspension is centrifuged, the step of separating and obtaining a precipitate comprises: First, the suspension is centrifuged to obtain a sediment; The sediment is washed with deionized water for multiple times and then dried to obtain the precipitate.
8. The method for preparing the composite photocatalyst according to claim 7, characterized in that: The temperature of the drying process is 60-70° C.; the drying time of the drying process is more than 12 hours.
9. The method for preparing the composite photocatalyst according to claim 1, characterized in that: After calcining the precipitate, the step of obtaining the composite photocatalyst comprises: The precipitate is placed in a muffle furnace and calcined for 2 to 3 hours to obtain a residue; In a light-proof environment, the residue is ground and then screened with a 100-200 mesh sieve to obtain a composite photocatalyst.
10. A composite photocatalyst prepared by the method for preparing a composite photocatalyst according to any one of claims 1 to 9.