Method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation method

Abstract

The invention discloses a method for preparing zinc oxide powder with different morphologies through a microwave-assisted precipitation method and application, and the method comprises the following steps: a) dissolving soluble zinc salt in deionized water to obtain a zinc ion solution; b) dissolving strong alkali in deionized water in proportion to obtain an alkali solution; c) performing two-phase opposite spraying on the solution in the step a) and the solution in the step b) by using a Y-shaped micro-jet reactor matched with an injection pump to obtain a reaction mixture; d) transferring the reaction mixture of c) into a microwave reaction vessel; e) separating and purifying a product; and f) drying. According to the invention, the preparation of nano zinc oxide with different morphologies such as a nano thick sheet shape, an ellipse shape, a 3D flower shape, a spherical shape composed of nano sheets and the like is conveniently realized through the same equipment; the experimental reaction time is shortened, the reaction efficiency is improved, the morphology of the zinc oxide is controllable, and different application requirements can be met; the preparation method is simple and suitable for large-scale batch production; the preparation process is green and environment-friendly, the preparation cost is low, and good economic benefits are achieved.

Description

Technical Field

[0001] This invention relates to the field of zinc oxide preparation technology, and in particular to a method for preparing zinc oxide powders with different morphologies by microwave-assisted precipitation. Background Technology

[0002] Zinc oxide has a wide range of applications. As a wide-bandgap semiconductor, zinc oxide strongly absorbs ultraviolet light while being transparent to visible light. This characteristic makes it irreplaceable in sunscreen cosmetics and ultraviolet light detectors. Its intrinsic nature is an n-type semiconductor, and its conductivity can be significantly improved by doping with Al, Ga, etc., while maintaining its transparency to visible light. It is an ideal material for solar cells and transparent electrodes. At the nanoscale, zinc oxide has a short electron transport path and a significant quantum tunneling effect, which enables it to efficiently release static electricity in electrostatic dissipative coatings, making it an excellent electrostatic dissipative coating material.

[0003] The key factor in the effectiveness of zinc oxide in various applications lies in its diverse morphological characteristics. Due to its polar nature, zinc oxide exhibits a variety of morphologies under different preparation methods, such as nanorods, nanosheets, nanoflowers, nanospheres, and rings.

[0004] Currently, common methods for producing zinc oxide include precipitation, hydrothermal synthesis, microwave synthesis, and ultrasonic irradiation. However, numerous studies have shown that it is difficult to prepare zinc oxide with specific morphologies through synthesis experiments using a single material.

[0005] Chinese patent CN120117645A discloses a bark-like nano-zinc oxide and its preparation method. It uses zinc acetate dihydrate, zinc nitrate hexahydrate, and zinc chloride as zinc sources, and employs a polyol-water biphase regulation mechanism to synergistically control the nucleation and growth of nano-zinc oxide, thereby synthesizing bark-like nano-zinc oxide. This nano-zinc oxide is then used as an antibacterial material against Gram-negative bacteria, Gram-positive bacteria, and fungi. However, the same method cannot produce controllable changes in the morphology of the product. Obtaining zinc oxide particles with different morphologies may require different methods and equipment, making the operation very inconvenient.

[0006] Therefore, providing a method for preparing nano-zinc oxide with different morphologies, such as nano-thick sheets, ellipses, 3D flowers, and spheres composed of nanosheets, using the same equipment is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A method for preparing zinc oxide powders with different morphologies by microwave-assisted precipitation includes the following steps:

[0010] a) Preparation of zinc ion solution:

[0011] Soluble zinc salts are dissolved in deionized water to obtain zinc ion solutions;

[0012] b) Prepare an alkaline solution:

[0013] A strong base is dissolved in deionized water in a certain proportion to obtain an alkaline solution;

[0014] c) Reaction with spray:

[0015] The solution from step a) and the solution from step b) are sprayed back and forth using a Y-type microjet reactor and an injection pump to obtain a reaction mixture.

[0016] d) Microwave-heated reaction:

[0017] The reaction mixture from step c) is transferred to a microwave reaction vessel and stirred and heated.

[0018] e) Product separation and purification:

[0019] After the reaction is complete, the mixture is cooled, filtered to separate the product, washed, and impurities are removed.

[0020] f) Drying:

[0021] The product was dried under vacuum at low temperature to obtain zinc oxide.

[0022] Preferably, in step a), the soluble zinc salt is one or more of zinc sulfate, zinc nitrate, and zinc acetate;

[0023] The concentration range of zinc ions is 110-140 mmol / L.

[0024] Preferably, in step b), the strong base is one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide;

[0025] The molar ratio of the strong base is 2-7 times that of the soluble zinc salt in step a).

[0026] Preferably, in step c), the two-phase solutions are each held in the Y-type microjet reactor for 1-2 seconds.

[0027] Preferably, in step c), the ratio of the zinc salt phase to the strong base phase in the injection pump is 1:1 to 1:4;

[0028] The speed of the infusion pump is 100-150 ml / min.

[0029] Preferably, in step d), the microwave power is 300-600W, the heating time at the microwave power is 2-5 minutes, and the microwave heating temperature is 50-80℃.

[0030] Preferably, in step e), the washing involves rinsing 3-5 times with deionized water and anhydrous ethanol, respectively.

[0031] Preferably, in step f), the low-temperature vacuum drying temperature is 50-70℃, and the drying time is 9-11 hours.

[0032] Preferably, in the preparation method, zinc oxide particles with different morphologies are obtained by adjusting the molar ratio of strong alkali and zinc salt; as the molar concentration of strong alkali increases, the morphology of the obtained zinc oxide changes from nano-thick sheets to elliptical shapes to 3D flower shapes and then to spheres composed of nanosheets.

[0033] The present invention achieves the following technical effects compared to the prior art:

[0034] (1) This invention is the first to apply microwave technology to the preparation of zinc oxide, utilizing its rapid and uniform heating characteristics to shorten the experimental reaction time and improve the reaction efficiency;

[0035] (2) By adjusting the process parameters, the present invention can obtain zinc oxide particles with different morphologies, thereby achieving controllable zinc oxide morphology and meeting different application requirements;

[0036] (3) The present invention is prepared by direct precipitation method, which is simple and suitable for large-scale mass production;

[0037] This invention achieves excellent dispersion without using any dispersant, and the preparation process is green and environmentally friendly with low cost, resulting in good economic benefits. Attached Figure Description

[0038] Figure 1 This is a flowchart of a method for preparing zinc oxide powder with different morphologies using microwave-assisted precipitation according to the present invention;

[0039] Figure 2 This is a scanning electron microscope image of zinc oxide synthesized under different molar ratios using a microwave-assisted precipitation method for preparing zinc oxide powders with different morphologies according to the present invention.

[0040] Figure (a) shows an electron microscope image of zinc oxide particles obtained under a molar ratio of 1:2.

[0041] (b) The figure shows an electron microscope image of zinc oxide particles obtained under the condition of a molar ratio of 1:2.85;

[0042] (c) The figure shows an electron microscope image of zinc oxide particles obtained under a molar ratio of 1:3;

[0043] (d) The figure shows an electron microscope image of zinc oxide particles obtained under a molar ratio of 1:4;

[0044] (e) Figure 1 shows an electron microscope image of zinc oxide particles obtained at a molar ratio of 1:5;

[0045] (f) is an electron microscope image of zinc oxide particles obtained under the condition of a molar ratio of 1:7. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] This invention proposes a method for preparing zinc oxide powders with different morphologies using microwave-assisted precipitation, comprising the following steps:

[0048] a) Preparation of zinc ion solution:

[0049] Soluble zinc salts were dissolved in deionized water to obtain solutions with zinc ion concentrations ranging from 110 to 140 mmol / L.

[0050] b) Prepare an alkaline solution:

[0051] A strong base is dissolved in deionized water in a certain proportion to obtain an alkaline solution;

[0052] c) Reaction with spray:

[0053] The solution from step a) and the solution from step b) were sprayed back and forth using a Y-type microjet reactor and an injection pump to obtain a reaction mixture.

[0054] d) Microwave-heated reaction:

[0055] Transfer the reaction mixture from step c) to a microwave reaction vessel and stir and heat.

[0056] e) Product separation and purification:

[0057] After the reaction is complete, the mixture is cooled, filtered to separate the product, washed, and impurities are removed.

[0058] f) Drying:

[0059] The product was dried under vacuum at low temperature to obtain zinc oxide.

[0060] The soluble zinc salt is one or more of zinc sulfate, zinc nitrate, and zinc acetate.

[0061] The strong base is one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide;

[0062] The molar ratio of strong bases is 2-7 times that of the soluble zinc salt in step a);

[0063] The two-phase solutions are each held in a Y-shaped microjet reactor for 1-2 seconds.

[0064] In the syringe pump, the ratio of the zinc salt phase to the strong base phase is 1:1 to 1:4;

[0065] The infusion pump speed is 100-150 ml / min;

[0066] The microwave power is 300-600W, the heating time at the microwave power is 2-5 minutes, and the microwave heating temperature is 50-80℃;

[0067] Washing involves rinsing 3-5 times with deionized water and anhydrous ethanol respectively to remove unreacted reagents and impurities;

[0068] The vacuum drying temperature at low temperature is 50-70℃, and the drying time is 9-11 hours.

[0069] The present invention discloses a method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation, which obtains zinc oxide particles with different morphologies by adjusting the molar ratio of strong alkali and zinc salt.

[0070] As the molar concentration of the strong base increases, the morphology of the resulting zinc oxide changes from nano-thick flakes to elliptical shapes to 3D flower-like shapes and then to spheres composed of nanosheets.

[0071] Example 1: Preparation of zinc oxide powders with different morphologies by varying the molar ratio of zinc nitrate as the zinc salt.

[0072] 1. Reagents and materials:

[0073] Zinc salt: Zinc nitrate hexahydrate, analytical grade;

[0074] Strong base: Sodium hydroxide, analytical grade;

[0075] Solvent: Deionized water.

[0076] 2. Preparation steps:

[0077] a) Preparation of zinc ion solution:

[0078] Weigh 3.7 g of zinc nitrate hexahydrate using an analytical balance and dissolve it in 100 ml of deionized water. Stir with a magnetic stirrer until completely dissolved to obtain a zinc ion solution with a concentration of 124.4 mmol / L.

[0079] b) Preparation of alkaline solution:

[0080] Weigh out analytical grade sodium hydroxide according to the molar ratio of zinc nitrate to sodium hydroxide of 1:2-1:7, dissolve each in 100 ml of deionized water, and use for subsequent experiments;

[0081] c) Reaction with spray:

[0082] The solutions from step a) and step b) were sprayed back and forth using a Y-type microjet reactor and an injection pump. The injection pump speed was set to 100 ml / min, and the ratio of the zinc salt phase and the strong base phase in the injection pump was 1:1. The two phase solutions were each held in the Y-type microjet reactor for 1 second and then sprayed back and forth to obtain the reaction mixture.

[0083] d) Microwave-heated reaction:

[0084] Transfer the reaction mixture from step c) to a microwave reaction vessel, set the microwave power to 500W, the temperature to 70℃, and the holding time to 3 minutes, and stir and heat.

[0085] e) Product separation and purification:

[0086] After the reaction is complete, the product is cooled and separated by vacuum filtration. The product is then washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0087] f) Drying:

[0088] The product was vacuum dried at a temperature of 60°C for 10 hours to obtain zinc oxide.

[0089] Change the molar ratio of zinc nitrate to sodium hydroxide in step b) (e.g., 1:2, 1:2.85, 1:3, 1:4, 1:5, 1:7).

[0090] When the molar ratio of zinc nitrate to sodium hydroxide is 1:2, the pH of the supernatant after the reaction is complete is 5.93.

[0091] When the molar ratio of zinc nitrate to sodium hydroxide is 1:2.85, the pH of the supernatant after the reaction is complete is 6.82.

[0092] When the molar ratio of zinc nitrate to sodium hydroxide is 1:3, the pH of the supernatant after the reaction is complete is 12.10.

[0093] When the molar ratio of zinc nitrate to sodium hydroxide is 1:4, the pH of the supernatant after the reaction is complete is 12.56.

[0094] When the molar ratio of zinc nitrate to sodium hydroxide is 1:5, the pH of the supernatant after the reaction is complete is 12.87.

[0095] When the molar ratio of zinc nitrate to sodium hydroxide is 1:7, the pH of the supernatant after the reaction is complete is 13.12.

[0096] Morphology analysis was performed on zinc oxide particles obtained at different molar ratios of zinc nitrate and sodium hydroxide.

[0097] 3. Result characterization:

[0098] Electron micrograph of zinc oxide particles as shown in the figure Figure 2 As shown, the morphology of zinc oxide particles generated by zinc nitrate and sodium hydroxide at different molar ratios is significantly different. With the increase of sodium hydroxide concentration, the morphology changes from nano-thick sheets to elliptical shapes to 3D flower shapes and then to spherical shapes formed by interwoven and stacked nanosheets.

[0099] Figure 2 The electron microscope image of zinc oxide particles obtained under the condition of a molar ratio of 1:2 is shown in Figure (a).

[0100] from Figure 2 As can be seen in Figure (a), when the molar ratio is 1:2, the resulting zinc oxide particles are in the form of nano-thick sheets.

[0101] Figure 2 Figure (b) shows an electron microscope image of zinc oxide particles obtained under a molar ratio of 1:2.85.

[0102] from Figure 2 As can be seen in Figure (b), when the molar ratio is 1:2.85, the resulting zinc oxide particles are elliptical in shape formed by the extrusion of two spheres.

[0103] Figure 2 The electron microscope image of zinc oxide particles obtained under the condition of a molar ratio of 1:3 is shown in Figure (c).

[0104] from Figure 2 As can be seen in Figure (c), when the molar ratio is 1:3, the resulting zinc oxide particles are several one-dimensional hexagonal pyramids that start from the center and eventually stack and self-assemble into a 3D polygonal flower-like structure.

[0105] Figure 2 The middle (d) image is an electron microscope image of zinc oxide particles obtained under the condition of a molar ratio of 1:4.

[0106] from Figure 2 As can be seen in Figure (d), when the molar ratio is 1:4, the resulting zinc oxide particles grow more cones on the basis of 1:3, which is a transitional state from 3D flower-like to surface-rough spherical.

[0107] Figure 2 The electron microscope image of zinc oxide particles obtained under the condition of a molar ratio of 1:5 is shown in Figure (e).

[0108] from Figure 2As can be seen in Figure (e), when the molar ratio is 1:5, the resulting zinc oxide particles are spherical, formed by interwoven and stacked nanosheets.

[0109] Figure 2 The electron microscope image of zinc oxide particles obtained under the condition of a molar ratio of 1:7 is shown in Figure (f).

[0110] from Figure 2 As can be seen in Figure (f), when the molar ratio is 1:7, the resulting zinc oxide particles are also spherical composed of flakes, but compared with the zinc oxide particles obtained under the 1:5 condition, the spherical particle size is larger and the flakes that make up the spheres are thicker.

[0111] Example 2: Application of spherical zinc oxide composed of nanosheets in the photocatalytic degradation of dyes 1. Experimental procedure:

[0112] Spherical zinc oxide powder composed of nanosheets was dissolved in 100 ml of methylene blue aqueous solution, stirred in the dark for 30 minutes, and the light source xenon lamp was turned on. Samples were taken every 10 minutes, and two control groups were set up: one without catalyst and one with commercial zinc oxide catalyst.

[0113] 2. Test Results:

[0114] The results showed that the spherical zinc oxide composed of nanosheets prepared in the experiment had a significantly higher degradation rate than commercial zinc oxide within 60 minutes, exhibiting high catalytic activity and stability, and was suitable for wastewater treatment.

[0115] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing zinc oxide powders with different morphologies by microwave-assisted precipitation, characterized in that, Includes the following steps: a) Preparation of zinc ion solution: Soluble zinc salts are dissolved in deionized water to obtain zinc ion solutions; b) Prepare an alkaline solution: A strong base is dissolved in deionized water in a certain proportion to obtain an alkaline solution; c) Reaction with spray: The solution from step a) and the solution from step b) are sprayed back and forth using a Y-type microjet reactor and an injection pump to obtain a reaction mixture. d) Microwave-heated reaction: The reaction mixture from step c) is transferred to a microwave reaction vessel and stirred and heated. e) Product separation and purification: After the reaction is complete, the mixture is cooled, filtered to separate the product, washed, and impurities are removed. f) Drying: The product was dried under vacuum at low temperature to obtain zinc oxide.

2. The method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation according to claim 1, characterized in that, In step a), the soluble zinc salt is one or more of zinc sulfate, zinc nitrate, and zinc acetate; The concentration range of zinc ions is 110-140 mmol / L.

3. The method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation according to claim 1, characterized in that, In step b), the strong base is one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide; The molar ratio of the strong base is 2-7 times that of the soluble zinc salt in step a).

4. The method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation according to claim 1, characterized in that, In step c), the two-phase solutions are each held in the Y-type microjet reactor for 1-2 seconds.

5. The method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation according to claim 1, characterized in that, In step c), the ratio of the zinc salt phase and the strong base phase in the injection pump is 1:1 to 1:

4. The speed of the infusion pump is 100-150 ml / min.

6. The method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation according to claim 1, characterized in that, In step d), the microwave power is 300-600W, the heating time at the microwave power is 2-5 minutes, and the microwave heating temperature is 50-80℃.

7. The method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation according to claim 1, characterized in that, In step e), the washing involves rinsing 3-5 times with deionized water and anhydrous ethanol, respectively.

8. The method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation according to claim 1, characterized in that, In step f), the low-temperature vacuum drying temperature is 50-70℃, and the drying time is 9-11 hours.

9. The method for preparing zinc oxide powder with different morphologies by microwave-assisted precipitation according to claim 1, characterized in that, In the preparation method, zinc oxide particles with different morphologies are obtained by adjusting the molar ratio of strong alkali and zinc salt. As the molar concentration of strong alkali increases, the morphology of the obtained zinc oxide changes from nano-thick sheets to elliptical shapes to 3D flower shapes and then to spheres composed of nanosheets.

10. The application of spherical zinc oxide composed of nanosheets prepared by the microwave-assisted precipitation method for preparing zinc oxide powder with different morphologies according to claims 1-9 in the photocatalytic degradation of dyes.

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