Method for preparing metal ion in-situ modified titanium dioxide

A kind of preparation method of metal ion in-situ modified titanium dioxideTechnical field

[0001] The present invention relates to the field of air purification materials, in particular to photocatalyst materials, in particular to a method for preparing titanium dioxide modified in situ by metal ions.

Background technique

[0002] Ti0₂As the earliest discovered photocatalytic material, it has the characteristics of non-toxicity, high catalytic activity (degradation and purification and hydrogen production by water decomposition), strong oxidation ability, good stability, low cost, and environmental friendliness. It is the most likely to be practical photocatalysis Materials, with the rapid development of nanotechnology, the preparation, modification and application of nano-titanium dioxide has become a research hotspot in the field of air purification. However, due to Ti0₂The wider band gap (3.2 eV) determines that it can only exert its photocatalytic activity under ultraviolet light, and the utilization rate of sunlight is too low; on the other hand, nano-titanium dioxide is prone to agglomeration, which greatly restricts it. application. [0003] In order to improve the photocatalytic performance of titanium dioxide, ion doping is currently a more commonly used modification method. The doping can introduce defects on the surface or change the crystallinity, thereby affecting the recombination of electrons and holes or expanding the absorption of light. Wave band, thereby improving the photocatalytic activity of titanium dioxide. At present, there are many preparation methods of titanium dioxide and modified titanium dioxide, such as alkoxide hydrolysis, hydrothermal preparation, sol-gel method, chemical precipitation method, and solid phase method. Among them, the sol-gel method is simple to prepare, convenient to operate, and convenient. Easy to control, etc., are commonly used preparation methods. However, the current preparation methods have the following problems, such as wide application of organic solvents and reagents, great harm, low doping rate, poor doping uniformity, poor dispersion, etc., which have become technical problems that need to be solved urgently in the technical field of titanium dioxide preparation methods.

Summary of the invention

[0004] In order to solve the technical problems of complex preparation process of metal-doped titanium dioxide, high harmfulness of organic solvents, low doping rate, poor doping uniformity, and poor dispersion, the present invention provides a method for preparing metal ion in-situ modified titanium dioxide , By preparing a sol-state titanium dioxide system in an alkaline environment with a water-soluble titanium source, further comprehensively controlling the reaction conditions, and cleverly selecting the timing to add an appropriate amount of transition metal or noble metal ion aqueous solution to dissolve in the process of hydrolyzing to form titanium dioxide, so as to dissolve the sol-state titanium dioxide In situ modification, the uniformly doped and well-dispersed titanium dioxide nanoparticles modified by metal ions are prepared, which realizes simple operation, green reaction, and greatly improves the photocatalytic performance of the material.

[0005] The technical solution adopted by the present invention is: a preparation method of in-situ modified titanium dioxide with metal ions, the preparation method includes the following steps: (1) Adding a titanium source and a weak alkali solution to water under stirring at room temperature, wherein, The mass ratio of titanium source, water, and weak alkali solution is 1:10ΐ 00:1-50, and the sol-state titanium dioxide system can be obtained by stirring evenly; (2) Adjust the pH value to 6~8, and add to the sol-state titanium dioxide system under stirring The metal ion aqueous solution, the mass ratio of the metal ion to the titanium dioxide is controlled to be 0.0000U0.01:1, and the reaction is stirred at 20-100°C for 0.5-5h to obtain the metal ion-modified titanium dioxide aqueous solution.

[0006] Preferably, the stirring speed is 350-500 r/min.

[0007] The addition of the source and the addition of the metal ion aqueous solution are all added dropwise.

[0008] The concentration of the metal ion aqueous solution is 0.5-1 wt.%.

[0009] The metal ion aqueous solution includes but is not limited to transition metals or precious metals Cr, Mn, Fe, C₀, Ni, Cu, Au,

One or two or more of Ag, Pt, and Pd aqueous solutions.

[00W] The titanium source is selected from one or two or more of titanium oxysulfate, titanium tetrachloride, titanium trichloride, titanium tetrafluoride or titanium alkoxide.

[0011] The weak alkali solution is ammonia water with a mass concentration of 2.5%.

[0012] The sol-state titanium dioxide system and/or metal ion-modified titanium dioxide aqueous solution are further purified by centrifugation or filtration, and then the precipitate or filter cake is resuspended uniformly in 1-5 times the volume of water.

[0013] Preferably, the preparation method is: (1) Add 10g of titanium source and 100-130mL of 2.5wt.% ammonia solution to 400-600g of water under stirring at room temperature, and stir uniformly to obtain a sol-state titanium dioxide system; (2) ) Filter the sol-state titanium dioxide system or centrifuge at 8000-10000r/min for 8-15min. The resulting precipitated solid is shaken and resuspended in 80-100ml of water and sonicated for 15-30s. The pH is controlled to be 6~8, and 0.8-lwt is added. % Metal ion aqueous solution, control the mass ratio of metal ion to titanium dioxide to 0.000U0.0003:1, stir at 20-40 °C for 3-4 hours to obtain metal ion-modified titanium dioxide aqueous solution.

[0014] In the above technical solution, a method for preparing metal ion in-situ modified titanium dioxide is provided. This method adopts an in-situ modification method to prepare metal ion-doped titanium dioxide nanoparticles. The specific method is stirring at room temperature, Using water as the solvent, add the titanium source and the weak alkali solution to the water, and control the mass ratio of the titanium source, water, and weak alkali solution to 1:1 ο-100: 1-50. At this time, the reaction conditions are alkaline, and the sol-state titanium dioxide system can be obtained by stirring evenly. The stirring time is generally more than 3 minutes. If the amount of weak alkali solution is small, the stirring time needs to be extended appropriately; the end of the stirring Then quickly adjust the pH value of the sol-state titanium dioxide system to 6~8, and the adjustment method can be the method commonly used by those skilled in the art, such as centrifugal resuspension or standing to remove the supernatant. As a key to this method, the metal ion aqueous solution The timing of the addition should be selected during and/or just when the sol-state titanium dioxide is formed, when the system appears flocculent suspension, and the titanium dioxide is in an amorphous state, and then the metal ion aqueous solution is added to the uniform sol-state titanium dioxide system. The mass ratio of the added metal ion to the titanium dioxide is controlled to be 0.00001~0.01:1, and the metal ion-modified titanium dioxide nanoparticle aqueous solution can be obtained by stirring at a temperature of 20-100°C for 0.5-5h. In this method, the metal-doped titanium dioxide photocatalyst nanoparticles with uniform morphology and high activity are obtained by comprehensively adding the timing of each raw material and controlling the ratio of reaction raw materials, reaction temperature, pH, and reaction time. The method has good stability and high repetition rate, and the 24h degradation efficiency of the product to formaldehyde is above 90%.

[0015] The beneficial effects of the present invention are: (1) The method of the present invention comprehensively controls the timing of addition of each raw material and controls the ratio of reaction raw materials, reaction temperature, pH and reaction time, and the solvent and reaction reagents are green and environmentally friendly and have high safety. It is a green chemical reaction with simple operation and mild production conditions, which is suitable for large-scale production; (2) In the further improved technical scheme, the stirring speed is strictly controlled, and the metal ion aqueous solution is added dropwise to achieve a uniform doping reaction rate and doping High efficiency and uniform morphology, realizing the controllable reaction process and time; choose 0.5-lwt.% metal ion aqueous solution and 2.5% mass concentration ammonia water to further comprehensively adjust the reaction concentration, reaction pH and other reaction conditions. The scientificity and stability of the preparation method are ensured, and the operating conditions are safe and reliable; (3) The method has a wide range of raw materials, low cost, and high economic and social benefits; (4) The method of the invention has low energy consumption, reaction reagents and The reaction process is pollution-free and conforms to the concept of green environmental protection.

Description of the drawings

[0016] FIG. 1 is a scanning electron micrograph of metal ion-modified titanium dioxide obtained in Example 1 of the present invention.

Detailed ways

[0017] The present invention provides a method for preparing metal ion in-situ modified titanium dioxide. The following specific examples illustrate the present invention for ease of understanding. The reagents involved in the examples can be purchased through commercial channels unless otherwise specified. , The methods used, unless otherwise specified, are conventional methods.

[0018] Embodiment 1:

Dissolve 10g of oxon sulfate in 500ml of water, add 110ml of ammonia with a concentration of 2.5wt.% under stirring, stir at 400r/min for 10min and then stop to obtain a sol-state titanium dioxide system; stand for 30min at 8000-10000r/min After centrifugation, the upper layer was removed, the solid precipitate obtained by centrifugation was resuspended in 90 ml of water, adjusted to pH 6, and the resuspended system was made uniform by stirring and ultrasound to obtain a purified sol-state titanium dioxide system; (2) To purified sol Co (NOs) 2 aqueous solution with a concentration of 1wt.% is added dropwise to the titanium dioxide system to avoid uneven doping of metal ions. By controlling the dropping acceleration and stirring speed, the metal ions are doped to change in situ. The reaction rate of titanium dioxide is uniform, the doping efficiency is high, and the morphology is uniform, which realizes the control of the reaction process and time, and controls the Co²⁺The mass ratio to titanium dioxide is 0.00001:1, which ensures the ratio of doped metal ions and the catalytic performance of the obtained metal ion-modified titanium dioxide, prevents excessive metal ions from causing disordered appearance and uneven doping. 350r/min under 25Ό After stirring and reacting for 3 hours, an aqueous solution of cobalt ion-modified titanium dioxide nanoparticles was obtained. See attached Figure 1 for scanning electron micrographs. The average particle size was 48 nm for particle size analysis.

[0019] Embodiment 2:

Dissolve 10g of tetrachloride in 300ml of water, add 100ml of ammonia with a concentration of 2.5 wt.% under stirring, and stop stirring at 450r/min for 6min to obtain a sol-state titanium dioxide system; let stand for 50min, centrifuge at 8000-10000r/min, and then Remove the supernatant liquid, resuspend the solid precipitate obtained by centrifugation with 100ml of water, adjust the pH to 7, shake with a screw mixer for 10 minutes, and ultrasound for 30s to make the resuspended system uniform to obtain a purified sol-state titanium dioxide system; (2) The concentration of 0.8wt.°/c^MnCl is added dropwise to the purified sol-state iron dioxide system₂Aqueous solution, control the mass ratio of manganese ion to titanium dioxide at 0.0001_:The reaction 511 was stirred at a speed of 40(^/1^11 at 1,30°(3) to obtain an aqueous solution of manganese ion-modified titanium dioxide nanoparticles.

Embodiment 3:

Dissolve 10g of titanium trichloride in 300ml of water, add 200ml of ammonia with a concentration of 2.5 wt.% under stirring, and stop stirring at 500r/min for 3 minutes to obtain a sol-state titanium dioxide system; let stand for 30 minutes and filter with suction. The resulting filter cake is filled with 100ml of water. Resuspend, adjust the pH to 8,500r/min and stir for 5 minutes until uniform. 100 Hz ultrasound for 20 seconds to make the resuspended system uniform to obtain a purified sol-state titanium dioxide system; (2) Add a concentration of 0.8 to the purified sol-state titanium dioxide system wt.%(:11(:1₂In the aqueous solution, the mass ratio of copper ion to titanium dioxide is controlled at 0.01:1, and the reaction is stirred for 2 hours at 40 °C to obtain an aqueous solution of copper ion-modified titanium dioxide.

[0021] The metal ion in-situ modified titanium dioxide photocatalyst nanoparticles prepared by the method of the present invention can be used for formaldehyde purification, and the purification efficiency test method is as follows: prepare two identical 1.5m under the same conditions³Among the experimental chambers, one is used as a test chamber and the other is used as a blank control chamber. 100g of the solution obtained in Example 1 above is sprayed onto 1 sheet of lm²Hung in the test chamber after the surface is dried on the base paper of inert material. The untreated base paper is hung in the blank contrast chamber. Two same slow-release formaldehyde pollution sources are placed in the experimental chamber and the experiment is closed. Chamber; Then turn on the fan of the experiment chamber at the same time to make the pollutants in the chamber circulate evenly, turn off the fan of the experiment chamber; after 24 hours, sample the concentration of the pollutants in the experiment chamber at the same time, analyze and test, calculate the pollutant removal rate, and refer to the calculation method The following formula: Pollutant removal rate = (Blank cabin pollutant concentration

Value-sample test chamber pollutant concentration value) + blank chamber pollutant concentration value X 100%, the same method is used to test the formaldehyde removal rate of the products obtained in the above embodiments, the results are shown in Table 1.

Table 1 Example 1-4 Formaldehyde removal rate of in-situ modified titanium dioxide with metal ions for 24 hours

<td rowspan="2">'' praise milk</td><td colspan="2">1 B knot medicine</td><td rowspan="2">β malice Iih T sun F----------------------------------------- ------------1</td>

<td>I Po··</td><td>1 Solin Record 3: ::-&lt;-&gt;':&gt;:&lt; ^:ϋ·&lt;ύ·-:^:: ：：：!</td>

<td>1：</td><td>1 Ο'.Ώ</td><td>1 α.04</td><td>95Λ2 |</td>

<td></td><td>1 Discuss</td><td></td><td>Transfer&gt; |</td>

<td></td><td></td><td>Measurement:</td><td>93.75 1</td>

<td></td><td>-+One</td><td>}Y ""·</td><td></td>

<td>4</td><td>s</td><td>1 Na</td><td>92.94 ]</td>

[0022] It can be seen from the above specific embodiments that the method of the present invention has a wide range of raw materials, low cost, simple operation process, mild production conditions, low energy consumption, suitable for large-scale production, and the reaction reagents and reaction process are pollution-free and conform to environmental protection. The concept is more worthy of respect is that the obtained in-situ modified titanium dioxide nanoparticles with metal ions have a uniform particle size. As a photocatalyst material, the removal efficiency of pollutants is high. The removal rate of formaldehyde in 24 hours is more than 90%, even more than 95%. .