A method for enhancing cavitation and mixing in an ultrasonic microreactor

Abstract

The present invention discloses a method for strengthening cavitation and mixing in an ultrasonic microreactor, by introducing a mutual dissolving solution consisting of a gas-rich solution and a gas-poor solution into the ultrasonic microreactor; Meanwhile, a certain ultrasonic frequency and ultrasonic power are applied to the ultrasonic microreactor, and under ultrasonic action, these mutual dissolving solutions precipitate a large amount of gas nuclei and rapidly grow into cavitation bubbles, producing a violent cavitation effect, and the violent cavitation effect strengthens the mixing in the ultrasonic microreactor. Wherein, the nitrogen saturation solubility of the gas-rich solution is 1.3 45 times that of the gas-poor solution, and the volume flow rate of the gas-rich solution is 0.025 20 times that of the gas-poor solution. The present invention makes the average density of cavitation bubbles in a single microchannel in the ultrasonic microreactor be ≥1 / microliter, and a large amount of cavitation bubbles quickly stir the fluid like a stirrer, and the complete mixing time of the fluid is less than 100 milliseconds. The present invention solves the problem that cavitation is weak in the ultrasonic microreactor and cannot achieve millisecond mixing.

Description

Technical Field

[0001] The invention relates to the field of acoustic cavitation and microfluid mixing, and in particular to a method for enhancing cavitation and mixing in an ultrasonic microreactor. Background Art

[0002] Introducing ultrasound into a microreactor can enhance the mixing of the microreactor to a certain extent by utilizing ultrasonic cavitation. At the same time, the acoustic flow generated by ultrasonic cavitation can break up the agglomeration and sedimentation of solid particles and prevent microchannel clogging. The essence of the process enhancement effect of ultrasonic microreactors is derived from a series of physical and chemical effects brought about by ultrasonic cavitation. However, the ultrasonic microreactors reported so far (AIChE Journal, 2017, 63(4): 1404-1418; Proc Natl Acad Sci USA, 2011, 108(15): 5996-5998; Chem. Commun., 2004, 20: 2280-2281) lack cavitation bubble nuclei in the microchannels and the microchannels have an inhibitory effect on the vibration of cavitation bubbles. As a result, the cavitation effect in the ultrasonic microreactor is weaker than that in the traditional ultrasonic reactor, which is manifested as fewer cavitation bubbles and weaker cavitation bubble vibration amplitude in the ultrasonic microreactor. If the cavitation effect in the ultrasonic microreactor needs to be improved, the ultrasonic energy input needs to be increased. However, higher energy input will lead to a series of problems such as heating and damage of the equipment, which greatly limits the further application of ultrasonic microreactors.

[0003] The cavitation intensity within the ultrasonic microreactor determines its mixing performance, and the mixing performance determines the product quality of some mixing-sensitive processes. For example, in the preparation of nanomaterials by precipitation, the mixing intensity determines the particle size and distribution of the final nanomaterial, and the particle size and distribution of the product further affect the terminal performance of the product. In the precipitation method, the self-assembly time of polymers is on the order of 20-60 milliseconds (Physical Review Letters, 2003, 91(11): 118302). The mixing of fluids must be fast enough to make the mixing time less than the nucleation time, so as to ensure that the generated nanoparticles are small and uniform in size. For this type of process, we need a reactor with a mixing time of the millisecond order (mixing time less than 100ms). However, the existing ultrasonic microreactor (AIChE Journal, 2017, 63(4): 1404-1418; CN 104923468 B) has a low internal cavitation intensity, and the mixing time can only reach 0.2-1.0s under the operating conditions allowed by the equipment, which cannot achieve millisecond-level mixing. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for enhancing cavitation and mixing in an ultrasonic microreactor, aiming to overcome the problems of weak cavitation, long mixing time and inability to achieve millisecond-level mixing in the above-mentioned prior art ultrasonic microreactor.

[0005] To achieve the above objectives, the present invention proposes a method for enhancing cavitation and mixing in an ultrasonic microreactor, which is as follows:

[0006] By introducing miscible solutions with different gas solubilities into an ultrasonic microreactor and simultaneously applying ultrasound at frequencies of 25kHz-200kHz and powers of 1W-300W, gas nuclei are precipitated from the miscible solutions within the ultrasonic microreactor and grow into cavitation bubbles with an average density of ≥1 per microliter. The high ultrasonic frequency (>22kHz) prevents the cavitation bubbles from coalescing into large bubbles, thereby reducing their density. This process produces a dramatic cavitation effect, which intensifies mixing within the ultrasonic microreactor.

[0007] The mutual soluble solutions with different gas solubilities are mainly composed of a gas-rich solution and a gas-lean solution; the nitrogen saturation solubility of the gas-rich solution (referring to the molar fraction of nitrogen in the solution) is 1.3-45 times, preferably 25-45 times, of the nitrogen saturation solubility of the gas-lean solution; the volume flow rate of the gas-rich solution is 0.025-20 times, preferably 0.1-10 times, of the volume flow rate of the gas-lean solution. The gas-rich solution and the gas-lean solution are respectively: ethanol and water, acetonitrile and water, acetone and water, N,N-dimethylformamide and water, acetone and ethanol, etc., that is, any two mutual soluble solutions that meet the above-mentioned nitrogen saturation solubility multiples can implement the present invention. When the mutual soluble solution introduced into the ultrasonic microreactor includes multiple fluids, the gas-rich solution is defined as the solution with the highest gas saturation solubility, and the gas-lean solution is defined as the solution with the lowest gas saturation solubility. At this time, a variety of mutual soluble solutions that meet the above-mentioned nitrogen saturation solubility multiples and volume flow rates can implement the present invention.

[0008] Preferably, the ultrasonic frequency is 41-80 kHz, the ultrasonic power is 5-25 W; the hydraulic diameter of the microchannel in the ultrasonic microreactor is 0.1-50 mm, preferably 0.2-5 mm.

[0009] The average density of cavitation bubbles in the microchannel refers to the number of cavitation bubbles formed per microliter of solution in a single channel. In the present invention, the density of cavitation bubbles is ≥1 per microliter under the gas-rich solution, gas-lean solution, and ultrasonic frequency and power. At such a high density, the cavitation bubbles quickly stir the fluid like a stirrer, and the complete mixing time of the fluid is less than 100 ms, preferably less than 40 ms.

[0010] Beneficial effects

[0011] Compared with the prior art, the present invention has the following significant features:

[0012] (1) A large number of cavitation bubble nuclei are generated from bottom to top in the ultrasonic microreactor by gas precipitation nuclei. Under the action of ultrasound, the cavitation nuclei further grow into cavitation bubbles, and violent cavitation occurs in the microchannel. The average density of cavitation bubbles is greater than one cavitation bubble per microliter.

[0013] (2) The large number of cavitation bubbles generated in the microchannel quickly stir the fluid like a stirrer, achieving millisecond-level mixing in the ultrasonic microreactor with a mixing time of less than 100 ms. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a comparison of the cavitation and mixing behaviors in the ultrasonic microreactor of Comparative Example 1 and Example 1. In the ultrasonic microreactor of Comparative Example 1, there are only four cavitation bubbles circled in the figure.

[0015] Figure 2 This is the variation of mixing time with ultrasonic power in the ultrasonic microreactor of Example 2.

[0016] Figure 3 This is the variation of mixing time with ultrasonic power in the ultrasonic microreactor of Example 3.

[0017] Figure 4 This is the variation of mixing time with ultrasonic power in the ultrasonic microreactor of Example 4.

[0018] Figure 5 This is the variation of mixing time with ultrasonic power in the ultrasonic microreactor of Example 5.

[0019] Figure 6 This is the variation of mixing time with ultrasonic power in the ultrasonic microreactor of Example 6.

[0020] Figure 7 This is the variation of mixing time with ultrasonic power in the ultrasonic microreactor of Example 7.

[0021] Figure 8 This is the variation of mixing time with ultrasonic power in the ultrasonic microreactor of Example 8.

[0022] Figure 9 This is the variation of mixing time with ultrasonic power in the ultrasonic microreactor of Example 9. DETAILED DESCRIPTION

[0023] The following non-limiting examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0024] Example 1

[0025] A rhodamine B (Aladdin, analytical grade)-dyed ethanol solution (rhodamine B concentration 0.25 mg / mL) was introduced at 0.5 mL / min, and another undyed deionized water solution was introduced at 1.5 mL / min into an ultrasonic microreactor with a channel hydraulic diameter of 1 mm and an operating frequency of 41 kHz. At room temperature and atmospheric pressure, the molar fraction of nitrogen saturated in the ethanol solution was 34.4 × 10 -5 (Physical and Chemical Reference Data, 1984, 13, 563-600), the molar fraction of nitrogen saturated in aqueous solution is 1.1×10 -5 (Physical and Chemical Reference Data, 1984, 13, 563-600), the nitrogen saturation solubility of the gas-rich solution is 31.3 times that of the gas-poor solution, and the flow rate of the gas-rich solution is 0.33 times that of the gas-poor solution. The ultrasonic microreactor is applied with a power of 5W to observe the cavitation effect in the ultrasonic microreactor, such as Figure 1 As shown, a large number of cavitation bubbles are generated in the microchannel, with an average density of 1.4 cavitation bubbles per microliter. The cavitation bubbles stir the fluid rapidly like a stirrer, and the two fluids are mixed instantly, with a mixing time of 82ms.

[0026] Example 2

[0027] A stream of Rhodamine B (Aladdin, analytical grade)-dyed ethanol solution (Rhodamine B concentration 0.25 mg / mL) was passed through an ultrasonic microreactor with an operating frequency of 25 kHz and a channel hydraulic diameter of 1 mm at 4 mL / min. At room temperature and atmospheric pressure, the molar fraction of nitrogen saturated in the ethanol solution was 34.4 × 10 -5 (Physical and Chemical Reference Data, 1984, 13, 563-600), the molar fraction of nitrogen saturated in aqueous solution is 1.1×10 -5 (Physical and Chemical Reference Data, 1984, 13, 563-600), the saturated solubility of nitrogen in the gas-rich solution is 31.3 times that of the gas-lean solution, and the flow rate of the gas-rich solution and the gas-lean solution is the same. The ultrasonic microreactor was applied with 10, 20, and 30W power, and the cavitation effect in the ultrasonic microreactor was observed. A large number of cavitation bubbles were generated in the microchannel, and the average density of cavitation bubbles was greater than 1 cavitation bubble per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly. The mixing time changes with the ultrasonic power as shown in Figure 2When 10W ultrasound was applied, the mixing time was 62ms. When the ultrasound power was further increased to 30W, the mixing time was further reduced to 38ms.

[0028] Example 3

[0029] A stream of acetonitrile solution (rhodamine B concentration 0.5 mg / mL) dyed with rhodamine B (Aladdin, analytical grade) was passed at 100 mL / min, and another stream of undyed deionized water solution was passed at 100 mL / min through an ultrasonic microreactor with a working frequency of 45 kHz and a channel hydraulic diameter of 50 mm. At room temperature and atmospheric pressure, the molar fraction of nitrogen saturated in the acetonitrile solution was 48×10 -5 (Physical and Chemical Reference Data, 1984, 13, 563-600), the molar fraction of nitrogen saturated in aqueous solution is 1.1×10 -5 (Physical and Chemical Reference Data, 1984, 13, 563-600), the saturated solubility of nitrogen in the gas-rich solution is 43.6 times that of the gas-lean solution, and the flow rate of the gas-rich solution and the gas-lean solution is the same. The ultrasonic microreactor was applied with 5, 10, 20, and 30W power, and the cavitation effect in the ultrasonic microreactor was observed. A large number of cavitation bubbles were generated in the microchannel, and the average density of cavitation bubbles was greater than 1 cavitation bubble per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly. The mixing time changes with the ultrasonic power as shown in Figure 3 When 5W ultrasound was applied, the mixing time was 74ms. When the ultrasound power was further increased to 30W, the mixing time was further reduced to 28ms.

[0030] Example 4

[0031] A stream of acetone solution dyed with rhodamine B (Aladdin, analytical grade) (rhodamine B concentration 0.1 mg / mL) was passed at 1 mL / min, and another stream of undyed deionized water solution was passed at 1 mL / min through an ultrasonic microreactor with a working frequency of 48 kHz and a channel hydraulic diameter of 0.5 mm. At room temperature and atmospheric pressure, the molar fraction of nitrogen saturated in the acetone solution was 49×10 -5 (Physical and Chemical Reference Data, 1984, 13, 563-600), the molar fraction of nitrogen saturated in aqueous solution is 1.1×10 -5(Physical and Chemical Reference Data, 1984, 13, 563-600), the saturated solubility of nitrogen in the gas-rich solution is 44.5 times that of the gas-lean solution, and the flow rate of the gas-rich solution and the gas-lean solution is the same. The ultrasonic microreactor was applied with 50, 100, 200, and 300W power, and the cavitation effect in the ultrasonic microreactor was observed. A large number of cavitation bubbles were generated in the microchannel, and the average density of the cavitation bubbles was greater than 1 cavitation bubble per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly. The mixing time changes with the ultrasonic power as shown in Figure 4 When 50W ultrasound was applied, the mixing time was 15ms. When the ultrasound power was further increased to 300W, the mixing time was further reduced to 6ms.

[0032] Example 5

[0033] A rhodamine B (Aladdin, analytical grade)-dyed N,N-dimethylformamide solution (rhodamine B concentration 0.25 mg / mL) was passed through an ultrasonic microreactor with an operating frequency of 41 kHz and a channel hydraulic diameter of 1 mm at 4 mL / min. At room temperature and atmospheric pressure, the molar fraction of nitrogen saturated in the N,N-dimethylformamide solution was 10.1×10 -5 (Physical and Chemical Reference Data, 1984, 13, 563-600), the molar fraction of nitrogen saturated in aqueous solution is 1.1×10 -5 (Physical and Chemical Reference Data, 1984, 13, 563-600), the nitrogen saturation solubility of the gas-rich solution is 9.2 times that of the gas-poor solution, and the flow rate of the gas-rich solution and the gas-poor solution is the same. The ultrasonic microreactor was applied with 10, 20, and 30W power, and the cavitation effect in the ultrasonic microreactor was observed. A large number of cavitation bubbles were generated in the microchannel, and the average density of cavitation bubbles was 1.1 cavitation bubbles per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly. The mixing time changes with the ultrasonic power as shown in Figure 5 When 10W ultrasound was applied, the mixing time was 92ms. When the ultrasound power was further increased to 30W, the mixing time was further reduced to 44ms.

[0034] Example 6

[0035] A stream of acetonitrile solution dyed with rhodamine B (Aladdin, analytical grade) (rhodamine B concentration 0.1 mg / mL) was introduced into an ultrasonic microreactor with a working frequency of 60 kHz and a channel hydraulic diameter of 0.5 mm at a flow rate of 1.9 mL / min and another stream of undyed deionized water solution was introduced at a flow rate of 0.1 mL / min. The saturated solubility of nitrogen in the gas-rich solution is 43.6 times that of the gas-poor solution, and the flow rate of the gas-rich solution is 20 times that of the gas-poor solution. The ultrasonic microreactor applied powers of 5, 10, 20, and 30 W to observe the cavitation effect in the ultrasonic microreactor. A large number of cavitation bubbles were generated in the microchannel, and the average density of the cavitation bubbles was greater than 1 cavitation bubble per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly. The mixing time varies with ultrasonic power as shown in FIG. Figure 6 When 5W ultrasound was applied, the mixing time was 56ms. When the ultrasound power was further increased to 30W, the mixing time was further reduced to 23ms.

[0036] Example 7

[0037] A stream of acetonitrile solution dyed with rhodamine B (Aladdin, analytical grade) (rhodamine B concentration 0.1 mg / mL) was introduced into an ultrasonic microreactor with a working frequency of 80 kHz and a channel hydraulic diameter of 0.25 mm at a flow rate of 0.45 mL / min and another stream of undyed deionized water solution was introduced at a flow rate of 0.05 mL / min. The saturated solubility of nitrogen in the gas-rich solution is 43.6 times that of the gas-poor solution, and the flow rate of the gas-rich solution is 9 times that of the gas-poor solution. The ultrasonic microreactor applied powers of 5, 10, 20, and 30 W to observe the cavitation effect in the ultrasonic microreactor. A large number of cavitation bubbles were generated in the microchannel, and the average density of the cavitation bubbles was greater than 1 cavitation bubble per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly. The mixing time varies with ultrasonic power as shown in FIG. Figure 7 When 5W ultrasound was applied, the mixing time was 14ms. When the ultrasound power was further increased to 30W, the mixing time was further reduced to 5ms.

[0038] Example 8

[0039] A stream of acetonitrile solution dyed with rhodamine B (Aladdin, analytical grade) (rhodamine B concentration 0.1 mg / mL) was introduced into an ultrasonic microreactor with a working frequency of 100 kHz and a channel hydraulic diameter of 0.1 mm at a flow rate of 0.25 mL / min, and another stream of undyed deionized water solution was introduced into an ultrasonic microreactor with a working frequency of 100 kHz and a channel hydraulic diameter of 0.1 mm at a flow rate of 0.25 mL / min. The saturated solubility of nitrogen in the gas-rich solution is 43.6 times that of the gas-lean solution, and the flow rates of the gas-rich solution and the gas-lean solution are the same. The ultrasonic microreactor applied powers of 5, 10, 20, and 30 W, and the cavitation effect in the ultrasonic microreactor was observed. A large number of cavitation bubbles were generated in the microchannel, and the average density of the cavitation bubbles was greater than 1 cavitation bubble per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly. The variation of mixing time with ultrasonic power is shown in FIG. Figure 8 When 5W ultrasound was applied, the mixing time was 5ms. When the ultrasound power was further increased to 30W, the mixing time was further reduced to 1.5ms.

[0040] Example 9

[0041] A stream of acetonitrile solution dyed with rhodamine B (Aladdin, analytical grade) (rhodamine B concentration 0.1 mg / mL) was introduced into an ultrasonic microreactor with a working frequency of 200 kHz and a channel hydraulic diameter of 0.1 mm at a flow rate of 0.17 mL / min and another stream of undyed deionized water solution was introduced at a flow rate of 0.34 mL / min. The saturated solubility of nitrogen in the gas-rich solution is 43.6 times that of the gas-poor solution, and the flow rate of the gas-rich solution is 0.5 times that of the gas-poor solution. The ultrasonic microreactor applied powers of 5, 10, 20, and 30 W to observe the cavitation effect in the ultrasonic microreactor. A large number of cavitation bubbles were generated in the microchannel, and the average density of the cavitation bubbles was greater than 1 cavitation bubble per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly. The mixing time changes with ultrasonic power as shown in FIG. Figure 9 When 5W ultrasound was applied, the mixing time was 5ms. When the ultrasound power was further increased to 30W, the mixing time was further reduced to 1.5ms.

[0042] Example 10

[0043] A rhodamine B (Aladdin, analytical grade)-dyed acetonitrile solution (rhodamine B concentration 0.25 mg / mL) was introduced into an ultrasonic microreactor with a working frequency of 41 kHz and a channel hydraulic diameter of 1 mm at a flow rate of 0.2 mL / min, and another undyed deionized water solution was introduced at a flow rate of 7.8 mL / min. The nitrogen saturation solubility of the gas-rich solution was 43.6 times that of the gas-poor solution, and the flow rate of the gas-rich solution was 0.26 times that of the gas-poor solution. A power of 1 W was applied to the ultrasonic microreactor to observe the cavitation effect in the ultrasonic microreactor. A large number of cavitation bubbles were generated in the microchannel, and the average density of the cavitation bubbles was greater than 1 cavitation bubble per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly, with a mixing time of 79 ms.

[0044] Example 11

[0045] A rhodamine B (Aladdin, analytical grade)-dyed acetone solution (rhodamine B concentration 0.25 mg / mL) was introduced into an ultrasonic microreactor with a working frequency of 41 kHz and a channel hydraulic diameter of 1 mm at 4 mL / min, while another undyed ethanol solution was introduced into an ultrasonic microreactor with a working frequency of 41 kHz and a channel hydraulic diameter of 1 mm at 4 mL / min. The nitrogen saturation solubility of the gas-rich solution was 1.4 times that of the gas-lean solution, and the flow rate of the gas-rich solution and the gas-lean solution was the same. The ultrasonic microreactor applied 20 W of power to observe the cavitation effect in the ultrasonic microreactor, and a large number of cavitation bubbles were generated in the microchannel, with an average density of 1.2 cavitation bubbles per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly, with a mixing time of 48 ms.

[0046] Example 12

[0047] A rhodamine B (Aladdin, analytical grade)-dyed acetonitrile solution (rhodamine B concentration 0.25 mg / mL) was introduced into an ultrasonic microreactor with a working frequency of 41 kHz and a channel hydraulic diameter of 1 mm at 1 mL / min, an undyed ethanol solution at 2 mL / min, and another undyed deionized water solution at 3 mL / min. Calculated based on the acetonitrile solution and deionized water solution, the nitrogen saturation solubility of the gas-rich solution was 43.6 times that of the gas-poor solution, and the flow rate of the gas-rich solution was 0.33 times that of the gas-poor solution. The ultrasonic microreactor applied 25 W of power to observe the cavitation effect within the ultrasonic microreactor, generating a large number of cavitation bubbles in the microchannel with an average density of 1.3 cavitation bubbles per microliter. The cavitation bubbles stirred the fluid rapidly like a stirrer, and the two fluids mixed rapidly with a mixing time of 32 ms.

[0048] Comparative Example 1

[0049] A deionized water solution dyed with rhodamine B (Aladdin, analytical grade) (rhodamine B concentration 0.25 mg / mL) was passed through an ultrasonic microreactor with an operating frequency of 41 kHz and a hydraulic diameter of 1 mm. The two solutions had the same gas solubility. The ultrasonic microreactor was powered at 5 W and the cavitation effect was observed. Figure 1 As shown in the figure, there are only four cavitation bubbles circled in the microchannel, with an average density of 0.48 cavitation bubbles per microliter. Uniform mixing of the fluid cannot be achieved in the entire microchannel, and the mixing time is greater than 100ms.

[0050] Comparative Example 2

[0051] A rhodamine B (Aladdin, analytical grade)-dyed ethanol solution (rhodamine B concentration 0.25 mg / mL) was passed through an ultrasonic microreactor operating at a frequency of 20 kHz and a channel hydraulic diameter of 1 mm. Both solutions had identical gas solubility. At 3 W of power applied to the ultrasonic microreactor, no cavitation was observed within the channel.

Claims

1. A method for enhancing cavitation and mixing in an ultrasonic microreactor, characterized by: By introducing mutually soluble solutions with different gas solubilities into the ultrasonic microreactor, and applying a certain ultrasonic frequency and ultrasonic power to the ultrasonic microreactor, gas nuclei are precipitated from the mutually soluble solutions with different gas solubilities in the ultrasonic microreactor and grow into cavitation bubbles with a certain density, thereby enhancing mixing in the ultrasonic microreactor; The miscible solutions with different gas solubilities are mainly composed of a gas-rich solution and a gas-lean solution; the nitrogen saturation solubility of the gas-rich solution is 1.3-45 times that of the gas-lean solution, where the nitrogen saturation solubility refers to the molar fraction of nitrogen in the solution; and the volume flow rate of the gas-rich solution is 0.025-20 times that of the gas-lean solution. The gas-rich solution and the gas-lean solution are respectively: ethanol and water, acetonitrile and water, acetone and water, N,N-dimethylformamide and water or acetone and ethanol.

2. The method for enhancing cavitation and mixing in an ultrasonic microreactor according to claim 1, characterized in that: When the miscible solution introduced into the ultrasonic microreactor includes multiple fluids, the gas-rich solution is defined as the solution with the highest gas saturation solubility, and the gas-lean solution is defined as the solution with the lowest gas saturation solubility.

3. The method for enhancing cavitation and mixing in an ultrasonic microreactor according to claim 1, characterized in that: The ultrasonic frequency is 25kHz-200kHz, the ultrasonic power is 1W-300W; and the hydraulic diameter of the microchannel in the ultrasonic microreactor is 0.1-50mm.

4. The method for enhancing cavitation and mixing in an ultrasonic microreactor according to claim 1 or 3, characterized in that: The average density of the cavitation bubbles in the microchannel is ≥1 per microliter.

5. The method for enhancing cavitation and mixing in an ultrasonic microreactor according to claim 1, characterized in that: The mixing time in the ultrasonic microreactor is less than 100ms.

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