Preparation method, device and application of micro-nano bubbles

Abstract

The invention provides a preparation method of micro-nano bubbles, which comprises the following steps: adding liquid with the depth of more than 4mm into a container, then vertically placing an ultrasonic probe with the diameter of 5mm-100mm above the liquid level of the liquid without contacting with the liquid level, setting the ultrasonic frequency to be 20kHz-200kHz, adjusting the power of an ultrasonic transducer to be 10W-2000W, and carrying out ultrasonic treatment on the ultrasonic probe to obtain the micro-nano bubbles. The distance between the ultrasonic probe and the liquid level is adjusted to be n lambda / 2 + / -0.1 mm, n is a positive integer, lambda is the wavelength of sound waves, and after ultrasonic starting, gas in the container is pumped into the liquid to generate micro-nano bubbles. The invention further discloses a preparation device of the micro-nano bubbles, application of the preparation device and application of the preparation device in air purification. According to the invention, a non-contact method capable of dispersing the micro-nano bubbles into the water at a high speed is adopted, the micro-nano bubbles are generated in the water, polluted gas can be sent into liquid for purification in this way, the cost is lower than that of a filter element purification mode, and the purification effect is better than that of directly introducing the polluted gas into the liquid.

Description

Technical Field

[0001] The present invention belongs to the field of ultrasonic technology, and particularly relates to a method for preparing micro-nano bubbles, a preparation device thereof, and an application thereof. Background Art

[0002] A micro-nano bubble generator is a device that generates tiny bubbles by means of high-energy rays or ultrasonic waves, etc. It can convert gas molecules in a liquid into micro-nano level bubbles without contacting the liquid. However, the gas content in the liquid is relatively low after all, and there is currently no better method to continuously and efficiently generate bubbles to produce micro-nano bubbles. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing micro-nano bubbles in view of the deficiencies of the above-mentioned prior art. This preparation method adopts a method that does not contact and can disperse micro-nano bubbles into water at high speed to generate micro-nano bubbles in water. Moreover, through this method, polluted gas can be sent into the liquid for purification. The cost is lower than the filter element purification method, and the purification effect is also better than directly introducing the polluted gas into the liquid.

[0004] To solve the above technical problem, the technical solution adopted by the present invention is: a method for preparing micro-nano bubbles, and the method is as follows: add a liquid with a depth greater than 4 mm into a container, and then vertically place an ultrasonic probe with a diameter of 5-100 mm above the liquid surface of the liquid without contacting the liquid surface. The frequency of the ultrasonic wave is set to 20 kHz - 200 kHz, the power of the ultrasonic transducer is adjusted to 10 - 2000 W, and the distance between the ultrasonic probe and the liquid surface is adjusted to nλ / 2 ± 0.1 mm, where n is a positive integer and λ is the wavelength of the sound wave. After the ultrasonic wave is started, the gas in the container is injected into the liquid to generate micro-nano bubbles, and the maximum distance between the ultrasonic probe and the liquid surface does not exceed 50.1 mm.

[0005] Preferably, the container is an air purification container. Polluted gas with PM10 > 500 is introduced into the air purification container. After the ultrasonic wave is started, the polluted gas is injected into the liquid, and the pollutants in the polluted gas are effectively adsorbed at the gas-liquid interface within 40 seconds.

[0006] Preferably, the frequency of the ultrasonic wave is set to 20 kHz - 40 kHz, and the power of the ultrasonic transducer is adjusted to 50 - 200 W.

[0007] The present invention also discloses a device for preparing micro-nano bubbles, which includes a container and an ultrasonic adjustment device. An ultrasonic generating device is installed in the ultrasonic adjustment device. The container is placed directly below the ultrasonic generating device, and the container is used to hold a liquid with a depth greater than 4 mm; the ultrasonic adjustment device is used to adjust the distance between the ultrasonic probe and the liquid level; the ultrasonic adjustment device includes a support plate a and a support plate b arranged horizontally in parallel. The ultrasonic generating device is fixedly arranged through the support plate a and the support plate b. At least four support rods are arranged between the support plate a and the support plate b. The bottom end of the support rod is fixedly connected to the support plate b through a fixing block, and the fixing block is fixed to the support plate b by screws. The top end of the support rod is slidably connected to the support plate a through a sliding block. The sliding block is slidably arranged on one side of the top end of the support rod, and the sliding block is fixed to the support plate a by screws. Two screw rods are also arranged through the support plate a and the support plate b. One end of the screw rod is fixedly connected to a motor, and the motor is fixedly installed at the bottom of the support plate b. The other end of the screw rod passes through the support plate a and is in threaded cooperation with the support plate a.

[0008] Preferably, a flexible sealing tube for protecting the ultrasonic generating device is arranged between the support plate a and the support plate b on the outside of the ultrasonic generating device. A motor protection shell is fixedly installed at the bottom of the support plate b on the outside of the motor. The bottom of the motor protection shell is fixedly connected to a rigid sealing tube for protecting the ultrasonic probe at the bottom end of the ultrasonic generating device.

[0009] The present invention also provides an application of the device for micro-nano bubbles. When the device for preparing micro-nano bubbles is used for air purification, the container is a purification device, and the ultrasonic adjustment device is installed in the purification device; the purification device includes an outer box and a purification chamber, a purification tank and a sewage tank arranged in the outer box. The ultrasonic adjustment device is installed above the purification chamber; a water pump for inputting water into the clean water tank and a water pump for outputting water from the clean water tank are arranged on the purification tank. An air pump a and an air pump b are arranged on the purification chamber; a water pump for inputting sewage into the sewage tank and a water pump for outputting sewage from the sewage tank are arranged on the sewage tank.

[0010] Preferably, the purification chamber is located at the inner bottom center of the purification device, and the purification tank and the sewage tank are located on both sides of the purification chamber.

[0011] Preferably, both the purification tank and the sewage tank are fixed to the two sides of the inner bottom of the outer box through bayonets. The water pump for inputting sewage into the sewage tank is fixed to the inner bottom of the outer box through a bayonet and is located beside the sewage tank. The water pump for outputting sewage from the sewage tank is fixed above the water pump for inputting sewage into the sewage tank; the water pump for outputting water from the clean water tank is fixed to the inner bottom of the outer box through a bayonet and is located beside the purification tank. The water pump for inputting water into the clean water tank is fixed above the water pump for outputting water from the clean water tank.

[0012] Preferably, the water pump for outputting water from the clean water tank and the water pump for inputting sewage into the sewage tank are located on opposite sides of the central axis of the outer box.

[0013] Preferably, a control box is provided above the purification device. An electric motor control box, an ultrasonic device control box, and a temperature control system are installed on the inner wall of the control box housing. An electric motor controller for controlling two electric motors and an electric motor power supply for supplying power to the electric motors are provided in the electric motor control box. The temperature control system includes a cooling fan, a fan controller, and a temperature sensor. An ultrasonic power supply for providing a variable voltage to the ultrasonic generating device and a control circuit board for controlling the ultrasonic frequency are provided in the ultrasonic device control box. A display control panel is provided on the control box housing, and the display control panel is connected to the ultrasonic generating device, the control circuit board, the ultrasonic power supply, the fan controller, the electric motor controller, and the electric motor power supply.

[0014] The present invention has the following advantages compared with the prior art: The present invention adopts a method of non-contact and high-speed dispersion of micro-nano bubbles into water to generate micro-nano bubbles in water. Moreover, through this method, polluted gas can be sent into the liquid in the form of bubbles for purification. Under the action of ultrasonic waves, the aerogel particles (solid or liquid particles dispersed in the gas) contained in the polluted air obtain a higher free diffusion speed. At the same time, during the generation of bubbles on the liquid surface, the rapid closure of the liquid surface and the high vibration speed of the particles in the concave neck region lead to an increase in the particle impact speed, which further accelerates the contact between the aerosol particles and the liquid surface, thereby accelerating the particle absorption rate. Therefore, for air purification, the purification cost using the present invention is lower than that of the filter element purification method, and the purification effect is also better than directly introducing the polluted gas into the liquid.

[0015] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a diagram of the first-order bubble generation process induced by acoustic radiation of the present invention.

[0017] Figure 2 It is a diagram of the high-order bubble flow path of the present invention.

[0018] Figure 3 It is a size distribution diagram of the micro-nano bubbles of the present invention.

[0019] Figure 4 It is a schematic diagram of the generation of sub-bubbles by the explosion of primary bubbles.

[0020] Figure 5 It is a high-order acoustic signal generated by the explosion of bubbles.

[0021] Figure 6 It is a schematic structural diagram of the micro-nano bubble preparation device of the present invention used for air purification.

[0022] Figure 7This is the analysis diagram of the particle vibration velocity around the sound cavity of the present invention.

[0023] Figure 8 This is the structural schematic diagram of the ultrasonic adjustment device of the present invention.

[0024] Figure 9 This is the external structural schematic diagram of a preparation device for micro-nano bubbles of the present invention.

[0025] Figure 10 is Figure 8 the A-A sectional view of

[0026] Figure 11 This is the internal structure display diagram of the cross-sectional part of the control box housing of the present invention.

[0027] Figure 12 This is the internal structural schematic diagram of the purification device of the present invention.

[0028] Figure 13 This is the exploded structural schematic diagram of the components of the purification device of the present invention.

[0029] Explanation of reference numerals:

[0030] 1 - Control box; 1.1 - Display panel; 1.2 - Motor control box; 1.3 - Ultrasonic device control box; 1.4 - Heat dissipation device; 1.5 - Control box housing; 2.1 - Ultrasonic generating device; 2.2 - Support plate a; 2.3 - Flexible sealing tube; 2.4 - Support plate b; 2.5 - Motor; 2.6 - Motor protection shell; 2.7 - Rigid sealing tube; 2.8 - Screw; 2.9 - Active support frame; 3 - Purification device; 3.1 - Outer box; 3.2 - Water purification tank; 3.3 - Air pump a; 3.4 - Water input pump for water purification tank; 3.5 - Water output pump for water purification tank; 3.6 - Sewage tank; 3.7 - Air pump b; 3.8 - Sewage tank output pump; 3.9 - Sewage tank input pump; 3.10 - Purification chamber. Detailed implementation manners

[0031] Example 1

[0032] A method for preparing micro-nano bubbles disclosed in this example is as follows:

[0033] Add water with a depth greater than 4 mm into a container, then vertically place an ultrasonic probe with a diameter of 5 mm - 100 mm above the water surface without contacting the liquid surface. Set the frequency of the ultrasonic wave to 20.5 kHz, adjust the power of the ultrasonic transducer to 100 W, and adjust the distance between the ultrasonic probe and the liquid surface to nλ / 2 ± 0.1 mm, where n is a positive integer, n = 2, and λ is the wavelength of the sound wave. After the ultrasonic wave is started, gas in the container is injected into the liquid to generate micro-nano bubbles.

[0034] In this embodiment, the frequency of the ultrasound can also be set to 20 kHz, 30 kHz, 40 kHz, 100 kHz, 150 kHz, 200 kHz, etc., and the power of the ultrasonic transducer can also be adjusted to 10 W, 200 W, 500 W, 1000 W, 2000 W, etc.

[0035] When the distance from the ultrasonic probe to the water surface is approximately λ / 2, λ, 3λ / 2 (λ represents the wavelength of the sound wave), a bubble phenomenon will occur on the water surface. Under the action of the acoustic radiation pressure, a concave shape is formed at the gas-liquid interface, and then it quickly closes and further evolves into a closed bubble, which is squeezed down into a large amount of liquid. The bubbling phenomenon is attributed to the Helmholtz resonance of the liquid depression caused by the acoustic radiation force.

[0036] First, the ultrasonic wave induces the formation of bubbles on the liquid surface, which are called first-order bubbles. The first-order bubbles will explode, and smaller bubbles will be generated after the explosion, which are called second-order bubbles, and so on, which are called higher-order bubbles.

[0037] As Figure 1 shown, after the ultrasonic probe is started, the pictures at 0 ms, 17 ms, 42 ms, 69 ms, 80 ms, and 86 ms show the generation process of the first-order bubbles induced by acoustic radiation.

[0038] Figure 2 shows the flow schematic diagram of the first-order bubbles generated after the explosion of the first-order bubbles.

[0039] Figure 3 The size distribution of micro-nano bubbles in

[0040] Figure 4 is a schematic diagram of the generation of second-order bubbles by the explosion of first-order bubbles. In the figure, Acoustic probe is the acoustic wave probe; primary bubble is the primary bubble; water film is the water film; glass slide is the glass slide; daughter bubble is the secondary bubble. Figure 4 (a) shows that the main bubble is vertically placed under the acoustic probe, and the bubble film folds outwards to obtain a circle of smaller daughter bubbles; Figure 4 (b) shows that when the main bubble is not directly under the acoustic probe, the smaller daughter bubbles are captured by the inwardly folded bubble film; in Figure 4 (a) state, the bubble starts to burst from the top and contracts towards the edge. During the contraction process, the bubble film flips outwards and finally folds with the lower layer of liquid to form a circle of smaller daughter bubbles. However, in Figure 4 (b) condition, the primary bubble is first attracted by the sound field of the sound field and bursts due to acoustic radiation. Finally, the remaining bubble film folds inwards and captures smaller bubbles.

[0041] Figure 5It is the high-order sound signal generated by the bubble explosion. This figure shows that different frequency signals correspond to bubble explosions of different sizes.

[0042] Example 2

[0043] In this example, the air purification is carried out by using the method for preparing micro-nano bubbles in Example 1, which specifically includes:

[0044] Add a liquid with a depth greater than 4 mm into the air purification container, and then vertically place an ultrasonic probe with a diameter of 5 mm - 1000 mm above the liquid surface without contacting the liquid surface. Set the frequency of the ultrasonic wave to 20.5 kHz, adjust the power of the ultrasonic transducer to 100 W, and adjust the distance between the ultrasonic probe and the liquid surface to nλ / 2 ± 0.1 mm, where n is a positive integer, n = 2, and λ is the wavelength of the sound wave. Introduce the polluted gas with PM10 > 500 into the air purification container. After the ultrasonic wave is started, the polluted gas in the container is injected into the liquid to generate micro-nano bubbles.

[0045] Experimental results show that more than 70% of the pollutants in 8 L of polluted gas are adsorbed by the liquid interface within 40 seconds.

[0046] In this example, the liquid can be pure water or an aqueous solution added with functional substances such as disinfection and adsorption.

[0047] After research, the adsorption rate of aerosol particles contained in polluted air on the liquid surface is determined by two stages: 1) the speed at which the particles reach and contact the liquid surface (Stage I); 2) the speed at which the contacted particles are captured by the gas-liquid interface (Stage II). According to the previous research, the particle capture process (Stage II) is very fast, on the time scale of ms. This indicates that the limitation of the particle adsorption rate depends on the approach and contact process of the particles (Stage I). In the absence of a sound field, the contact between aerosol particles and the liquid surface mainly depends on the thermal diffusion of the particles following the Brownian motion law. However, under the action of the sound field, obvious acoustic streaming is generated between the ultrasonic probe and the liquid surface, as shown in Figure 6 (d), driving the particles to impact the liquid surface at a speed of ~ 0.2 m / s. The acoustic streaming is the reason for the increase in the particle absorption rate. In addition, under the action of the ultrasonic foaming process, the rapid closure of the liquid surface and the high vibration speed of the particles in the concave neck region lead to an increase in the particle impact speed, approximately 0.5 m / s, which further accelerates the contact between the aerosol particles and the liquid surface, thus accelerating the particle absorption rate.

[0048] Figure 6 Enhance the adsorption of air pollutants through ultrasonic foaming. Figure 6(a) is the experimental setup; the experimental setup includes a transparent working chamber (equivalent to an air purification container), an aerosol generator that injects aerosol gas (equivalent to polluted air) into the air purification container, a camera that takes pictures of the working chamber, an LED light that provides supplementary lighting to the air purification container, and the aerosol generator, LED light, and camera are all connected to a computer.

[0049] Figure 6 (b) are clarity photos of different air purification methods: (i) The initial state of the working chamber, with the injected aerosol particles suspended in the air, having very low transparency and making it almost impossible to observe the acoustic probe inside the chamber. (ii) After 40 s of ultrasonic foaming, the injected aerosol particles are effectively absorbed and the acoustic probe can be clearly observed. (iii) With ultrasonic action but without foaming for 40 s, the injected aerosol particles are partially adsorbed and the transparency of the injected aerosol gas is higher than the initial state. (iv) After 40 s with the ultrasonic not working and no sound field, the transparency of the injected aerosol gas remains unchanged from the initial state. Figure 6 (c) is the MGV analysis of images under different conditions. MGV is the gray value, and the lower the smoke concentration, the lower the gray value. Figure 6 (d) is the acoustic streaming between the ultrasonic probe and the gas-liquid interface, indicating that the sound field can accelerate air flow and enhance the contact between pollutants and the liquid surface.

[0050] Figure 7 It is an analysis diagram of the vibration velocity of particles around the acoustic cavity. The depression during the ultrasonic foaming process can be regarded as a special Helmholtz resonance cavity, where the vibration velocity of the medium particles at the neck is very high, accelerating the adsorption of pollutant particles.

[0051] Example 2

[0052] As Figures 8 - 13As shown in the figure, this embodiment discloses a preparation device for micro-nano bubbles, which includes a container and an ultrasonic adjustment device 2. An ultrasonic generating device 2.1 is installed in the ultrasonic adjustment device 2. The container is used to hold a liquid with a depth greater than 4 mm, and the container is placed directly below the ultrasonic generating device 2.1. The ultrasonic adjustment device 2 is used to adjust the distance between the ultrasonic probe and the liquid level; the ultrasonic adjustment device 2 includes a support plate a 2.2 and a support plate b 2.4 that are horizontally and parallelly arranged. The ultrasonic generating device 2.1 is fixedly arranged between the support plate a 2.2 and the support plate b 2.4 through penetration. At least four support rods 2.9 are arranged between the support plate a 2.2 and the support plate b 2.4. The bottom end of the support rod 2.9 is fixedly connected to the support plate b 2.4 through a fixing block, and the fixing block is fixed to the support plate b 2.4 by screws. The top end of the support rod 2.9 is slidably connected to the support plate a 2.2 through a sliding block. The sliding block is slidably arranged on one side of the top end of the support rod 2.9, and the sliding block is fixed to the support plate a 2.2 by screws. Two screw rods 2.8 are also arranged between the support plate a 2.2 and the support plate b 2.4 through penetration. One end of the screw rod 2.8 is fixedly connected to a motor 2.5, and the motor 2.5 is fixedly installed at the bottom of the support plate b 2.4. The other end of the screw rod 2.8 passes through the support plate a 2.2 and is in threaded cooperation with the support plate a 2.2.

[0053] In this embodiment, a flexible sealing tube 2.3 for protecting the ultrasonic generating device 2.1 is arranged between the support plate a 2.2 and the support plate b 2.4 on the outside of the ultrasonic generating device 2.1. A motor protection shell 2.6 is fixedly installed on the bottom of the support plate b 2.4 on the outside of the motor 2.5. The bottom of the motor protection shell 2.6 is fixedly connected to a rigid sealing tube 2.7 for protecting the ultrasonic probe at the bottom end of the ultrasonic generating device 2.1.

[0054] When the preparation device for micro-nano bubbles is used for air purification, the container is a purification device 3, and the ultrasonic adjustment device 2 is installed in the purification device 3; the purification device 3 includes an outer box 3.1 and a purification chamber 3.10, a purification box 3.2 and a sewage box 3.6 arranged in the outer box 3.1. The ultrasonic adjustment device 2 is installed above the purification chamber 3.10; a water inlet pump 3.4 and a water outlet pump 3.5 for the purified water tank are arranged on the purification box 3.2. An air pump a 3.3 and an air pump b 3.7 are arranged on the purification chamber 3.10. The polluted air is introduced into the purification box 3.2 by using the air pump a 3.3, and the purified gas is extracted from the purification box 3.2 by using the air pump b 3.7; a sewage box water inlet pump 3.9 and a sewage box water outlet pump 3.8 are arranged on the sewage box 3.6. The sewage box water inlet pump 3.9 is used to supply water into the sewage box 3.6, and the sewage box water outlet pump 3.8 is used to pump water from the sewage box 3.6.

[0055] In this embodiment, the purification chamber 3.10 is located at the inner bottom center of the purification device 3, and the purification tank 3.2 and the sewage tank 3.6 are located on both sides of the purification chamber 3.10; the output water pump 3.5 of the purified water tank and the input water pump 3.9 of the sewage tank are located on both sides of the center axis symmetry of the outer box 3.1.

[0056] Specifically, both the purification tank 3.2 and the sewage tank 3.6 are fixed to both sides of the inner bottom of the outer box 3.1 through bayonets. The input water pump 3.9 of the sewage tank is fixed to the inner bottom of the outer box 3.1 through a bayonet and is located beside the sewage tank 3.6. The output water pump 3.8 of the sewage tank is fixed to the upper part of the input water pump 3.9 of the sewage tank; the output water pump 3.5 of the purified water tank is fixed to the inner bottom of the outer box 3.1 through a bayonet and is located beside the purification tank 3.2. The input water pump 3.4 of the purified water tank 3.2 is fixed to the upper part of the output water pump 3.5 of the purified water tank.

[0057] In this embodiment, a control box 1 is provided above the purification device 3. The control box 1 includes a control box housing 1.5. An electric motor control box 1.2, an ultrasonic device control box 1.3, and a temperature control system 1.4 are installed on the inner wall of the control box housing 1.5; the electric motor control box 1.2 has a motor controller for controlling two electric motors 2.5 and a motor power supply for supplying power to the electric motors 2.5, and the motor controller is connected to the electric motors. The temperature control system 1.4 includes a cooling fan, a fan controller, and a temperature sensor. The temperature sensor is used to detect the temperature inside the box and then transmit it to the fan controller. Once the detected temperature exceeds the threshold, the fan controller controls the cooling fan to start, increasing the air flow inside the box for cooling. The number of ultrasonic device control boxes 1.3 is two. An ultrasonic power supply for providing a variable voltage to the ultrasonic generating device 2.1 and a control circuit board for controlling the ultrasonic frequency are respectively arranged in the two ultrasonic device control boxes 1.3. The ultrasonic power supply controls the ultrasonic power by controlling the output of different voltages, and the control circuit board is used to control the ultrasonic frequency.

[0058] A display control panel 1.1 is arranged on the control box housing 1.5, and the display control panel 1.1 is connected to the ultrasonic generating device 2.1, the control circuit board, the ultrasonic power supply, the fan controller, the motor controller, and the motor power supply.

[0059] In this application, a micro-nano bubble preparation device is used to prepare micro-nano bubbles. The process is as follows: The rotation of the screw 2.8 is controlled by the electric motor 2.5, and the up and down movement of the support plate a 2.2 is controlled, so as to adjust the distance between the end face of the ultrasonic generating device and the water surface in the container to be an integer multiple of the half wavelength. After the ultrasonic generating device 2.1 is started, bubbles are generated on the water surface.

[0060] The air purification is carried out by using the preparation device of micro-nano bubbles. The working process is as follows: Start the input water pump 3.4 of the clean water tank, add 4 L of pure water into the clean water tank 3.2, start the output water pump 3.5 of the clean water tank, add 2 L of pure water into the purification chamber 3.10, control the rotation of the screw rod 2.8 through the motor 2.5, and control the up and down movement of the support plate a2.2 meshed with the screw rod 2.8, so as to adjust the distance between the end face of the ultrasonic generating device and the water surface in the purification chamber to be an integer multiple of the half wavelength. Start the ultrasonic generating device 2.1, and at the same time start the air pump a to input polluted air into the purification chamber 3.10, and start the air pump b to extract the gas in the purification chamber 3.10. Start the input water pump 3.9 of the sewage tank every 12 hours to clean the sewage in the purification chamber. After the sewage is discharged into the sewage tank, start the output water pump 3.5 of the clean water tank again to input 2 L of pure water into the purification chamber 3.10.

[0061] As mentioned above, it is only a preferred embodiment of the present invention and does not impose any limitation on the present invention. Any simple modification, change and equivalent change made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing micro-nano bubbles, characterized in that: The method is as follows: liquid with a depth greater than 4 mm is added into a container, and then an ultrasonic probe with a diameter of 5-100 mm is vertically placed above the liquid surface without contacting the liquid surface, the frequency of the ultrasound is set to 20 kHz-200 kHz, the power of the ultrasonic transducer is adjusted to 10-2000 W, and the distance between the ultrasonic probe and the liquid surface is adjusted to nλ / 2±0.1 mm, wherein n is a positive integer, and λ is the wavelength of the sound wave. After the ultrasound is started, the gas in the container is pumped into the liquid to generate micro-nano bubbles, and the maximum distance between the ultrasonic probe and the liquid surface does not exceed 50.1 mm.

2. The method for preparing micro-nano bubbles according to claim 1, characterized in that: The container is an air purification container. Polluted gas with PM10>500 is introduced into the air purification container. After ultrasound is started, the polluted gas is pumped into the liquid, and the pollutants in the polluted gas are effectively adsorbed by the gas-liquid interface within 40 seconds.

3. The method for preparing micro-nano bubbles according to claim 1, characterized in that: The frequency of ultrasound was set to 20kHz-40kHz, and the power of the ultrasonic transducer was adjusted to 50-200W.

4. A device for preparing micro-nano bubbles as claimed in claim 1 or 2, characterized in that: It includes a container and an ultrasonic adjustment device, an ultrasonic generating device is installed in the ultrasonic adjustment device, the container is placed directly below the ultrasonic generating device, the container is used to hold liquid with a depth greater than 4 mm; the ultrasonic adjustment device is used to adjust the distance between the ultrasonic probe and the liquid surface; the ultrasonic adjustment device includes a support plate a and a support plate b arranged horizontally and parallel, the ultrasonic generating device is passed through and fixed between the support plate a and the support plate b, at least four support rods are arranged between the support plate a and the support plate b, the bottom end of the support rod is fixedly connected to the support plate b through a fixed block, the fixed block is fixed to the support plate b through a screw, the top end of the support rod is slidably connected to the support plate a through a sliding block, the sliding block is slidably arranged on one side of the top end of the support rod, the sliding block is fixed to the support plate a through a screw, two screws are also passed between the support plate a and the support plate b, one end of the screw is fixedly connected to the motor, the motor is fixedly installed at the bottom of the support plate b, the other end of the screw passes through the support plate a and is threadedly matched with the support plate a.

5. The micro-nano bubble device according to claim 4, characterized in that: A flexible sealing tube for protecting the ultrasonic generating device is arranged between the support plate a and the support plate b on the outside of the ultrasonic generating device, a motor protection shell is fixedly installed on the bottom of the support plate b on the outside of the motor, and a rigid sealing tube for protecting the ultrasonic probe at the bottom end of the ultrasonic generating device is fixedly connected to the bottom of the motor protection shell.

6. An application of a micro-nano bubble device as claimed in claim 4, characterized in that: When the micro-nano bubble preparation device is used for air purification, the container is a purification device, and the ultrasonic adjustment device is installed in the purification device; The purification device comprises an outer box and a purification chamber, a purification box and a sewage tank arranged in the outer box, and the ultrasonic adjustment device is installed above the purification chamber; The purification box is provided with a clean water tank input water pump and a clean water tank output water pump, the purification chamber is provided with air pump a and air pump b; the sewage tank is provided with a sewage tank input water pump and a sewage tank output water pump.

7. The micro-nano bubble device according to claim 6, characterized in that: The purification chamber is located at the central inner bottom of the purification device, and the purification box and the sewage box are located at two sides of the purification chamber.

8. The micro-nano bubble device according to claim 6, characterized in that: The purification tank and the sewage tank are both fixed to the two sides of the inner bottom of the outer box by means of bayonet, the sewage tank input water pump is fixed to the inner bottom of the outer box by means of bayonet and is located beside the sewage tank, and the sewage tank output water pump is fixed to the upper part of the sewage tank input water pump; the clean water tank output water pump is fixed to the inner bottom of the outer box by means of bayonet and is located beside the purification tank, and the clean water tank input water pump is fixed to the upper part of the clean water tank output water pump.

9. The micro-nano bubble device according to claim 6, characterized in that: The clean water tank output water pump and the sewage tank input water pump are located on opposite sides of the central axis of the outer box.

10. A micro-nano bubble device according to any one of claims 6 to 9, characterized in that: A control box is arranged above the purification device, and a motor control box, an ultrasonic device control box and a temperature control system are installed on the inner wall of the control box shell; a motor controller for controlling two motors and a motor power supply for powering the motors are arranged in the motor control box; the temperature control system includes a cooling fan, a fan controller, and a temperature sensor; an ultrasonic power supply for providing a variable voltage for an ultrasonic generating device and a control circuit board for controlling the ultrasonic frequency are arranged in the ultrasonic device control box; a display control panel is arranged on the control box shell, and the display control panel is connected to the ultrasonic generating device, the control circuit board, the ultrasonic power supply, the fan controller, the motor controller, and the motor power supply.

Images