CN113942997A

CN113942997A - Micro-nano particle size grading device and method

Info

Publication number: CN113942997A
Application number: CN202010687698.4A
Authority: CN
Inventors: 郭逦达; 张佑专; 权滢; 陈韵吉
Original assignee: Beijing Graphene Research Institute Co ltd
Current assignee: Beijing Graphene Research Institute Co ltd
Priority date: 2020-07-16
Filing date: 2020-07-16
Publication date: 2022-01-18
Anticipated expiration: 2040-07-16
Also published as: CN113942997B

Abstract

The present disclosure provides a micro-nano particle size grading device, including: the screen is arranged in the shell; the micro-bubble generator is connected to the bottom of the shell so as to introduce micro-bubbles into the shell; the micro-nano particle size grading device comprises a shell, a micro-bubble screen, a micro-nano particle screen, and a micro-nano particle screen. The device disclosed by the invention is low in cost and simple to maintain, the device is adopted for size classification of micro-nano particles, the classification range is large, the classification is accurate, the classification time is short, the efficiency is high, the whole process is a physical classification process, no new chemicals are introduced, no influence is caused on the subsequent process, and the device has a good application prospect.

Description

Micro-nano particle size grading device and method

Technical Field

The disclosure relates to the technical field of material size separation, in particular to a micro-nano particle size grading device and method.

Background

In the field of materials, the size of micro-nano particles often affects the final macroscopic structure or device. Taking graphene as an example, methods for preparing graphene currently include chemical vapor deposition, mechanical exfoliation, oxidation reduction, and the like, wherein the oxidation reduction method is the most economical and commonly used method. The oxidation-reduction method is to reduce Graphene Oxide (GO) serving as a precursor to prepare graphene. The graphene oxide and the graphene oxide derivative obtained by the method have good dispersibility due to containing a plurality of functional groups, and the reduced product also has excellent performance. However, in the chemical oxidation process, the structure of the graphene oxide is damaged to a certain extent, and the size of the sheet diameter is often uncontrollable. The sheet diameter size of graphene and graphene oxide has obvious influence on the performance of a final macroscopic structure or a device. Therefore, it is also important to control the size of the graphene oxide precursor.

The currently reported methods for size fractionation of graphene and derivatives thereof mainly include gradient centrifugation, filtration, free diffusion dialysis, and the like. However, due to the small size and low density of materials such as graphene and graphene oxide, effective separation of different sizes through traditional sieving is difficult; the size range of the centrifugal method is small (less than 1 mu m), and large-scale mass production cannot be realized; for the membrane filtration method, the efficiency is low, the aperture of the filtration pores is not uniform, the blockage is easy to occur or the size grading effect is not ideal; for the track etching film with regular holes, the area is small, the selling price is expensive, the efficiency is low, and the method is not suitable for industrial production; the free diffusion dialysis method is too long and has low production efficiency (Chinese patent application CN 108996497A).

Therefore, a method which is easy to implement and can efficiently and effectively separate micro-nano particles with different sheet diameters is urgently needed to be developed.

It is noted that the information disclosed in the foregoing background section is only for enhancement of background understanding of the present disclosure and therefore it may contain information that does not constitute prior art that is known to a person of ordinary skill in the art.

Disclosure of Invention

The main purpose of the present disclosure is to overcome at least one of the defects in the prior art, and provide a micro-nano particle size classification apparatus and method, so as to solve the problems of long time, low efficiency and unsuitability for large-scale production in the existing size classification method.

In order to achieve the purpose, the following technical scheme is adopted in the disclosure:

the present disclosure provides a micro-nano particle size grading device, including: the screen is arranged in the shell; the micro-bubble generator is connected to the bottom of the shell so as to introduce micro-bubbles into the shell; the micro-nano particles are driven by micro-bubbles to pass through a screen from bottom to top so as to carry out size grading on the micro-nano particles.

According to one embodiment of the present disclosure, the screen is a plurality of screens with different mesh numbers, and the plurality of screens are arranged in the housing at intervals in an order of increasing mesh numbers from bottom to top.

According to one embodiment of the present disclosure, the number of the mesh screens is 1 to 10; when the number of the screens is more than 1, the distance between the adjacent screens is 5 cm-100 cm; the volume of the shell is 1L-2500L.

According to one embodiment of the disclosure, the micro-nano particles are selected from one or more of graphene, graphene oxide and silicon dioxide, and the size of the micro-nano particles is 10nm to 8000 um.

According to one embodiment of the disclosure, when the micro-nano particles are charged particles, the method further comprises the step of respectively arranging electrodes with opposite electric properties at the top and the bottom of the shell.

According to one embodiment of the disclosure, the micro-nano particles are graphene oxide, the top of the shell is provided with an anode, and the bottom of the shell is provided with a cathode.

According to one embodiment of the present disclosure, the plurality of screens is composed of a first screen and a second screen positioned above the first screen, the first screen having a mesh number of 28 to 8000, and the second screen having a mesh number of 28 to 8000.

The invention also provides a method for grading the size of the micro-nano particles by adopting the device, which comprises the following steps: placing dispersion liquid containing micro-nano particles with different sizes in a shell; and (3) starting the microbubble generator, and carrying out dialysis classification on the micro-nano particles driven by the microbubbles through the screen from bottom to top to obtain micro-nano particle dispersion liquid in different size ranges.

According to one embodiment of the disclosure, when the micro-nano particles are charged particles, applying a voltage to the shell along the vertical direction, wherein the voltage is 1-100V.

According to one embodiment of the present disclosure, the size of the bubbles generated by the microbubble generator is 200nm to 50um, and the flow rate of the bubbles is 20sccm to 2000 sccm.

According to one embodiment of the present disclosure, the dialysis time is 5 to 15 hours.

According to the technical scheme, the beneficial effects of the disclosure are as follows:

according to the micro-nano particle size grading device, the size grading of micro-nano particles can be effectively realized by utilizing a dialysis principle and combining micro-bubble power. The device is used for size grading of micro-nano particles, the grading range is large, grading is accurate, the device has the advantages of short grading time and high efficiency, effective grading can be completed within about 5-15 hours, and in addition, because the whole process is a physical grading process, new chemicals are not introduced, and the device has no influence on subsequent processes. The device has the advantages of low cost, simple maintenance, no material residue on the screen, difficult blockage, repeated use and good industrial application prospect.

Drawings

The following drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the principles of the disclosure and not to limit the disclosure.

Fig. 1 is a schematic diagram of a principle structure of a micro-nano particle size classification device according to an embodiment of the disclosure;

fig. 2 to 4 respectively show a micro-nano particle size classification process schematic diagram according to an embodiment of the disclosure;

fig. 5 shows a schematic structural diagram of a micro-nano particle size classification device according to an embodiment of the present disclosure.

Wherein the reference numbers are as follows:

100. 100': shell body

201. 201': first screen mesh

202. 202': second screen mesh

300. 300': micro-bubble generator

400: solvent(s)

500: micro-nano particle

600: micro bubbles

700: anode protection net

I. II: feed inlet

III, IV and VI: discharge port

V: water inlet

A: anode access port

B: cathode access port

C: microbubble access port

D: exhaust port

Detailed Description

Exemplary embodiments that embody features and advantages of the present disclosure are described in detail below in the specification. It is to be understood that the disclosure is capable of various modifications in various embodiments without departing from the scope of the disclosure, and that the description and drawings are to be regarded as illustrative in nature, and not as restrictive.

In the following description of various exemplary embodiments of the disclosure, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration various exemplary structures, systems, and steps in which aspects of the disclosure may be practiced. It is to be understood that other specific arrangements of parts, structures, example devices, systems, and steps may be utilized, and structural and functional modifications may be made without departing from the scope of the present disclosure. Moreover, although the terms "over," "between," "within," and the like may be used in this specification to describe various example features and elements of the disclosure, these terms are used herein for convenience only, e.g., in accordance with the orientation of the examples described in the figures. Nothing in this specification should be construed as requiring a specific three dimensional orientation of structures in order to fall within the scope of this disclosure.

Referring to fig. 1, a schematic structural diagram of a micro-nano particle size classification apparatus according to an exemplary embodiment of the present disclosure is representatively illustrated. The micro-nano particle size grading device provided by the disclosure is explained by taking the application to graphene oxide size grading as an example. Those skilled in the art will readily appreciate that various modifications, additions, substitutions, deletions, or other changes may be made to the embodiments described below in order to apply the relevant designs of the present disclosure to other types of micro-nano particle size classification, and still fall within the scope of the present disclosure to provide apparatus principles.

As shown in fig. 1, in this embodiment, the micro-nano particle size classification apparatus proposed by the present disclosure mainly includes a housing, a plurality of screens, and a microbubble generator, wherein the micro-nano particles may be particles of graphene, graphene oxide, silica, and the like, which can be dispersed in a solvent. Fig. 1 is only a partial schematic diagram of the micro-nano particle size classification apparatus. Fig. 2 to 4 are schematic diagrams illustrating a micro-nano particle size classification process combining micro-bubbles and an electric field according to an embodiment of the present disclosure. The structure, connection mode and functional relationship of each main component of an exemplary embodiment of the micro-nano particle size classification device provided by the present disclosure will be described in detail below with reference to the above drawings and taking the micro-nano particles as graphene oxide as an example.

As shown in fig. 1, the micro-nano particle size classifying apparatus includes a housing 100, a plurality of

screens

201 and 202, and a micro-bubble generator 300. The casing 100 may be in various shapes such as a cylinder, a cuboid, a cube, etc., and the volume of the enclosed container is 1L-2500L, which can be adjusted properly according to actual needs. The screen mesh is nylon net, metal mesh or the reticular material that processes as required, and the screen mesh of corresponding shape can be selected for use according to the casing shape, and the mesh shape is square, rectangle, triangle-shaped, sphere, irregular sphere or other irregular shapes.

In the present embodiment, the plurality of screens is composed of a first screen 201 and a second screen 202 located above the first screen 201. It should be noted that, the screen of the present disclosure may be provided with only 1 screen, and in this case, only 2 stages of sheet diameters are provided. Of course, the screen of the present disclosure may be provided in plural, for example, 3, 4, etc., according to actual needs, and the present disclosure is not limited thereto. The screen meshes are arranged in the casing 100 at intervals in an increasing order from bottom to top. Typically, the distance between adjacent screens is from 5cm to 100cm, e.g., 5cm, 15cm, 20cm, 30cm, 50cm, 75cm, etc. The first mesh is 28 to 8000 mesh, for example, 28 mesh, 300 mesh, 600 mesh, 800 mesh, 2000 mesh, 5000 mesh, 8000 mesh, etc., and the second mesh is 28 to 8000 mesh, for example, 800 mesh, 1000 mesh, 2000 mesh, 5000 mesh, 8000 mesh, etc., and is selected according to the particle size to be screened.

The micro bubble generator 300, also called micro-nano bubble generator, generates micro bubbles having the characteristics of small bubble size, large specific surface area, high adsorption efficiency, slow ascending speed in water, etc. As shown in fig. 1, the micro-bubble generator 300 of the present disclosure is connected to the bottom of the housing 100, discharges micro-bubbles through the gas outlet and enters the housing, so that micro-nano particles can pass through the plurality of

screens

201 and 202 from bottom to top under the driving of the micro-bubbles, thereby achieving the effect of size classification of the micro-nano particles.

Dialysis, according to the present disclosure, is a separation and purification technique that separates small molecules from biological macromolecules by the principle of diffusion of small molecules through a semi-permeable membrane into water (or buffer). Dialysis is a physical process that essentially uses the difference in concentration of substances across a semi-permeable membrane. Use receiving a little particle as Graphite Oxide (GO) as an example, this disclosure is through the screen cloth that adopts different mesh numbers, can carry out "dialysis" to the graphite oxide dispersion liquid, based on concentration difference dialysis theory of bases, inject the GO dispersion liquid that contains different piece footpath GO in the bottom, because concentration difference, the GO of different piece footpaths upwards diffuses gradually, minimum piece footpath can pass through two screens, medium piece footpath can only pass through the great first screen cloth 201 of lower floor's aperture, and big piece footpath can't pass through first screen cloth 201 and second screen cloth 202, stay in the bottom. In the whole grading process, the microbubble generator 300 of container bottom switches on, through size, the output of adjusting the microbubble, can realize can easily taking up the GO in small piece footpath, and the GO in big piece footpath is difficult for being driven because self quality is great, therefore the microbubble has promoted the grading, has shortened the classification time greatly, has promoted classification efficiency.

In some embodiments, the size of the bubbles generated by the microbubble generator is 200nm to 50um, such as 200nm, 500nm, 1um, 20um, 30um, 40um, etc., preferably 0.5um to 20um, and the flow rate of the bubbles is 20sccm to 2000sccm, preferably 50sccm to 800 sccm. For the present invention, the size and flow rate of the microbubbles play an important role in the classification effect, and if the bubbles are too large or the flow rate is too small, the classification promoting effect cannot be achieved. If the amount of the bubbles is too large, all the particles are driven to rapidly move upwards, and the particles have certain pressure on the filter screen, so that the larger sheet diameter extrudes the small filter holes, and the grading is inaccurate; secondly, local filter screen blockage can be caused. If the amount of bubbles is too small, the classification cannot be accelerated effectively, resulting in low classification efficiency and too long time consumption.

In some embodiments, when the micro-nano particles of the present disclosure are charged particles, particle classification can be further promoted by providing opposite electrodes at two ends of the shell to apply an electric field.

The method for classifying micro-nano particles according to an embodiment of the present disclosure is specifically described below with reference to fig. 2 to 4, taking graphene oxide as an example.

As shown in fig. 2, a dispersion liquid containing micro-nano particles 500 with different sizes is placed in the shell, and then a solvent 400 such as water is added into the shell to fill the whole shell 100.

Next, as shown in fig. 3, the microbubble generator 300 is turned on, and microbubbles 600 are generated to drive the micro-nano particles 500 to move upwards. Meanwhile, voltage is applied to the device, and as the surface of GO has various polar functional groups, GO in the suspension is in a negative charge state, at the moment, the top of the shell 100 is provided with a positive electrode, the bottom of the shell is provided with a negative electrode, and an electric field is generated by applying voltage. As shown in fig. 4, when the small-diameter GO is brought upward by the microbubbles under the action of the electric field, the small-diameter GO is attracted by the positive electrode and stably exists near the upper electrode. After a certain time, in several regions separated by the screen, the GO with different sheet diameters is stably stored: the upper strata is small-size GO (the microbubble drives, is attracted by the positive pole), and the middle level is medium-size GO (the microbubble drives and goes upward, is intercepted by denser filter screen), and the lower floor is large-size GO (the microbubble can't drive). With this, through utilizing the principle of dialysis and electrophoresis, the power that combines the microbubble to produce drives the GO piece, has realized multistage size separation to the GO dispersion with the screen cloth of different apertures.

In some embodiments, when the micro-nano particles are charged particles, that is, when the particles are in a charged state (positive or negative) in the dispersion liquid, the method further includes applying a voltage to the shell along a vertical direction, where the applied voltage is not too large or too small, and too small cannot ensure the effect of stabilizing the particles, and the applied voltage is preferably 1V to 100V, for example, 1V, 10V, 30V, 50V, 80V, 100V, and the like.

Fig. 5 shows a schematic structural diagram of a micro-nano particle size classification device according to an embodiment of the present disclosure. As shown in fig. 5, in the present embodiment, the micro-nanoparticle size classification apparatus mainly includes: a housing 100 ', a first screen 201', a second screen 202 ', and a microbubble generator 300'. Of course, a plurality of screens with different meshes can be arranged according to actual needs, and the disclosure is not limited to the screens.

Specifically, as shown in fig. 5, an anode inlet a and a cathode inlet B are respectively provided at the top and bottom of the case 100' to connect the anode and the cathode, respectively, wherein an anode protection mesh 700 is provided under the anode. The first screen 201 'is close to the bottom cathode and the second screen 202' is close to the top anode, and the device is suitable for classifying negatively charged particles in the suspension, and as mentioned above, if the positively charged micro-nano particles need to be classified, the positions of the cathode and the anode are exchanged.

At casing 100' be equipped with a plurality of business turn over material mouths and business turn over gas port respectively, include: the feed inlet I and the feed inlet II are respectively arranged at the top and the bottom of the shell 100 ', the discharge outlet III and the discharge outlet IV are respectively arranged above the first screen 201 ' and the second screen 202 ' at the other side of the shell 100 ', and the discharge outlet VI is arranged at the lowest part of the shell 100 '. In addition, a water inlet V is also provided above the anode protection mesh 700. To connect the microbubble generator 300 ', the housing 100' has a microbubble port C opened at the lowermost portion and an exhaust port D opened at the uppermost portion, respectively, to exhaust excessive gas.

When the device is used, suspension containing micro-nano particles can be filled into the feed inlet I or the feed inlet II according to actual needs, and then water is fed into the device from the water inlet V until the whole container is filled. The anode and the cathode are electrified through the anode access port A and the cathode access port B to form an electric field, the micro-bubble generator 300' is started, at the moment, the micro-bubbles generate power to drive the micro-nano particles to move upwards, meanwhile, under the attraction of the electric field, the movement of the micro-nano particles is further accelerated, and the multi-stage size separation can be realized by using screens with different apertures for the micro-nano particles.

In conclusion, the present disclosure can realize precise control of particle size classification size of particles by using dialysis principle and combining micro-bubble power, and the classification range can be large or small (10 nm-8000 um). The present disclosure can further promote particle size classification by combining an electric field attraction mode, effectively reduce classification time and improve efficiency. Through verification, the particle size classification by adopting a common dialysis mode usually needs more than 40 hours, and the time can be greatly shortened through the process of microbubble acceleration and electric field attraction, and the effective classification can be completed within 5-15 hours. In addition, the device disclosed by the invention has the characteristics of simplicity, feasibility, low price and easiness in industrial application, is simple to maintain, has no material residue on the screen, is not easy to block and can be used repeatedly. Because the whole process is physical grading, no new chemical is introduced in the grading process, and the subsequent process is not influenced. In a word, the micro-nano particle size grading device and method disclosed by the invention can realize controllable separation of micro-nano particles, particularly graphene oxide and the like, so that the regulation and control of the performance of the obtained product are further realized, and the device and method have important significance.

The invention will be further illustrated by the following examples, but is not to be construed as being limited thereto. Unless otherwise specified, the reagents used in the present invention are commercially available.

Example 1

(1) GO was prepared using a modified Hummers method:

adding 70mL of concentrated sulfuric acid into 2g of 325-mesh crystalline flake graphite, and placing the mixture in a containerStirring (200rpm) in ice water bath for 25 min; slowly add 10g KMnO₄Reacting for 60 min; transferring the mixture into a warm water bath at 35 ℃ to continue reacting for 60min, and stirring at the speed of 300 rpm; slowly adding 110mL of deionized water, keeping the reaction temperature at 98 ℃, and stirring for 5 min; adding a proper amount of H₂O₂Until no bubbles are generated, the solution turns from dark brown to yellow; washing with deionized water and 5% hydrochloric acid for 3 times to neutrality to remove metal ions; fully drying in a vacuum drying oven at 60 ℃ to obtain graphite oxide; dispersing graphite oxide in water to obtain brown yellow liquid; and carrying out ultrasonic treatment for 1h to obtain 2mg/mL GO dispersion.

(2) Size grading is carried out on the GO dispersion liquid obtained in the step 1):

the screen and the container are cleaned, electrodes are arranged at the upper end and the lower end of the 20L container and connected with a 30V direct current power supply, the upper side is a positive electrode, and the lower side is a negative electrode. The bottom of the container is provided with a micro-bubble generator. Slowly pouring 5L of GO dispersion liquid 2g/mL into the bottom of the container, horizontally fixing a screen in a 20L container, wherein the upper side is a 2000-mesh screen, the lower side is a 600-mesh screen, the distance between the screens is adjustable, and the screens are in a loose state. The vessel was filled with water. And (3) switching on a direct current power supply and turning on the micro-bubble generator, wherein the flow rate of the bubbles is 200sccm, and the size of the bubbles is 2 mu m, and performing dialysis. After 8 hours of dialysis, GO plate size grading was completed.

And taking out the GO sheet diameter dispersion liquid which is graded and contains different size ranges, and characterizing the GO sheet diameter dispersion liquid. At least 3 points are taken from the same batch of samples by SEM, and at least 90 pieces of sheet diameter data are measured in total to obtain the average value of the sheet diameter. The sizes of the plate diameters after the classification are 4.1 μm, 16.1 μm and 35.3 μm in sequence.

Example 2

(1) Preparing GO:

preparing 220mL of mixed acid of concentrated sulfuric acid and phosphoric acid (volume ratio is 9:1), slowly pouring the mixed acid into 6g of 800-mesh crystalline flake graphite and 48g of KMnO₄And stirred. The reaction temperature was raised to 40 ℃ and stirring was continued for 10 h. The combined solution was poured into 2500mL of deionized water, followed by addition of 150mL of H₂O₂The solution changed from dark brown to yellow; washing with deionized water and 5% hydrochloric acid for 3 times to neutral, removingMetal ions and sulfate ions. Fully drying in a vacuum drying oven at 60 ℃ to obtain graphite oxide; dispersing graphite oxide in water to obtain brown yellow liquid; and carrying out ultrasonic treatment for 1h to obtain 3mg/mL GO dispersion.

and cleaning the screen and the container. The upper end and the lower end of the 4L container are provided with electrodes which are connected with a 30V direct current power supply, the upper side is a positive electrode, and the lower side is a negative electrode. The bottom of the container is provided with a micro-bubble generator. Slowly pouring 1L of 3g/mL GO dispersion liquid at the bottom of the container, horizontally fixing the screen in a 4L container, wherein the upper side is a 8000-mesh screen, the lower side is a 1000-mesh screen, the distance between the screens is adjustable, and the screens are in a loose state. The container was filled with water. And switching on a direct current power supply and turning on a micro-bubble generator, wherein the flow rate of bubbles is 100sccm, and the size of the bubbles is 500nm for dialysis. After dialysis for 10 hours, GO size grading was completed.

And taking out the GO sheet diameter dispersion liquid which is graded and contains different size ranges, and characterizing the GO sheet diameter dispersion liquid. At least 3 points are taken from the same batch of samples by SEM, and at least 90 pieces of sheet diameter data are measured in total to obtain the average value of the sheet diameter. The sizes of the plate diameters after the classification are 1.1 μm, 5.8 μm and 14.1 μm in sequence.

Example 3

The classification was carried out in the same manner as in example 1 except that no voltage was applied. After 15 hours of dialysis, GO fractionation was complete. And taking out the GO sheet diameter dispersion liquid which is graded and contains different size ranges, and characterizing the GO sheet diameter dispersion liquid. At least 3 points are taken from the same batch of samples by SEM, and at least 90 pieces of sheet diameter data are measured in total to obtain the average value of the sheet diameter. The sizes of the plate diameters after the classification are 4.2 μm, 15.6 μm and 35.5 μm in sequence.

Comparative example 1

The fractionation method was the same as in example 1 except that the microbubble generator was not turned on and no voltage was applied. After dialysis for 15 hours, characterization was performed and found that GO was not fractionated in size, and the specific fractions of each layer were 3.9 μm, 12.6 μm, and 30.5 μm. Indicating that many small radii did not pass through the screen, resulting in a lower average size for the large radius area.

Comparative example 2

The fractionation method was the same as example 1 except that the microbubble generator was not turned on. After dialysis for 15 hours, characterization was performed and found that GO was not fractionated in size, and specific layers were fractionated at 4.0 μm, 14.6 μm, and 33.5 μm. Indicating that many small radii did not pass through the screen, resulting in a lower average size for the large radius area.

It should be noted by those skilled in the art that the described embodiments of the present disclosure are merely exemplary, and that various other substitutions, alterations, and modifications may be made within the scope of the present disclosure. Accordingly, the present disclosure is not limited to the above-described embodiments, but is only limited by the claims.

Claims

1. A micro-nano particle size grading device is characterized by comprising:

a housing;

a screen disposed within the housing; and

the micro-bubble generator is connected to the bottom of the shell and is used for introducing micro-bubbles into the shell;

the micro-nano particle size grading screen is characterized in that dispersion liquid containing micro-nano particles with different sizes is placed in the shell, and the micro-nano particles are driven by the micro-bubbles to pass through the screen from bottom to top so as to carry out size grading on the micro-nano particles.

2. The device of claim 1, wherein the screen is a plurality of screens with different meshes, and the screens are arranged in the shell at intervals in an order of increasing mesh number from bottom to top.

3. The apparatus of claim 1, wherein the number of said screens is 1 to 10; when the number of the screens is more than 1, the distance between the adjacent screens is 5 cm-100 cm; the volume of the shell is 1L-2500L.

4. The device according to claim 1, wherein the micro-nano particles are selected from one or more of graphene, graphene oxide and silicon dioxide, and the size of the micro-nano particles is 10nm to 8000 um.

5. The device according to claim 1, wherein when the micro-nano particles are charged particles, the device further comprises electrodes with opposite electric properties respectively arranged at the top and the bottom of the shell.

6. The device according to claim 5, wherein the micro-nano particles are graphene oxide, the top of the shell is provided with a positive electrode, and the bottom of the shell is provided with a negative electrode.

7. The apparatus of claim 6, wherein the plurality of screens consists of a first screen and a second screen positioned above the first screen, the first screen having a mesh size of 28-8000 mesh and the second screen having a mesh size of 28-8000 mesh.

8. A method for grading the size of micro-nano particles by using the device of any one of claims 1-7 is characterized by comprising the following steps:

placing dispersion liquid containing micro-nano particles with different sizes in the shell;

and starting the microbubble generator, wherein the microbubbles drive the micro-nano particles to pass through the screen from bottom to top for dialysis classification, so as to obtain micro-nano particle dispersion liquid in different size ranges.

9. The method according to claim 8, wherein when the micro-nano particles are charged particles, the method further comprises applying a voltage to the shell along a vertical direction, wherein the voltage is 1V-100V, and the dialysis time is 5 h-15 h.

10. The method of claim 8, wherein the microbubble generator generates bubbles having a size of 200nm to 50um and a bubble flow rate of 20sccm to 2000 sccm.