CN113942997B - Micro-nano particle size grading device and method - Google Patents

Abstract

The present disclosure provides a micro-nano particle size classifying device comprising: the device comprises a shell, a screen and a micro-bubble generator, wherein the screen is arranged in the shell; the microbubble generator is connected to the bottom of the shell so as to introduce microbubbles into the shell; the dispersion liquid containing micro-nano particles with different sizes is placed in the shell, and the micro-nano particles are driven by micro-bubbles to pass through the screen from bottom to top so as to carry out size classification on the micro-nano particles. The device disclosed by the invention has the advantages of low cost, simplicity in maintenance, large grading range, accuracy in grading, short grading time and high efficiency, and the whole process is a physical grading process, does not introduce new chemicals, has no influence on the subsequent process, and has 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 has an impact on the final macrostructure or device. Taking graphene as an example, the current methods for preparing graphene include chemical vapor deposition, mechanical stripping, redox and other methods, wherein the redox method is the most economical common method. The redox method is to prepare graphene by reducing Graphene Oxide (GO) as a precursor. The graphene oxide and the derivative thereof obtained by the method have good dispersibility because of containing various functional groups, and the reduced product has excellent performance. However, in the chemical oxidation process, the structure of 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 the final macrostructure or device. Therefore, it is also particularly important to regulate the size of the graphene oxide precursor.

The size classification methods of graphene and derivatives thereof reported at present mainly comprise a gradient centrifugation method, a filtration method, a free diffusion dialysis method and the like. However, due to the small size and low density of graphene, graphene oxide and other materials, effective separation of different sizes is difficult to perform through traditional sieving; the size range of the centrifugal method classification is small (less than 1 μm), and large-scale mass production cannot be realized; for the membrane filtration method, the efficiency is low, the pore diameter of the filter holes is not uniform, the blockage is easy to occur, or the size classification 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 track etching film is not suitable for industrial production; the free diffusion dialysis method has the disadvantages of long time and low production efficiency (Chinese patent application CN 108996497A).

Therefore, there is a need to develop a method that is easy to implement and can efficiently and effectively separate micro-nano particles with different sheet diameters.

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

Disclosure of Invention

It is a primary object of the present disclosure to overcome at least one of the above-mentioned drawbacks of the prior art, and to provide a micro-nano particle size classifying apparatus and method, so as to solve the problems of long time, low efficiency and unsuitable for mass production of the existing size classifying method.

In order to achieve the above purpose, the present disclosure adopts the following technical scheme:

the present disclosure provides a micro-nano particle size classifying device comprising: the device comprises a shell, a screen and a micro-bubble generator, wherein the screen is arranged in the shell; the microbubble generator is connected to the bottom of the shell so as to introduce microbubbles into the shell; wherein, the dispersion liquid containing micro-nano particles with different sizes is arranged in the shell, and the micro-nano particles are driven by micro-bubbles to pass through the screen from bottom to top so as to carry out size classification 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 a sequence of sequentially increasing the mesh numbers from bottom to top.

According to one embodiment of the present disclosure, the number of the 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 present 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 8000um.

According to one embodiment of the disclosure, when the micro-nano particles are charged particles, the micro-nano particles further comprise electrodes with opposite electrical properties respectively arranged 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 a positive electrode, and the bottom is provided with a negative electrode.

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

The disclosure also provides a method for classifying micro-nano particle size by adopting the device, which comprises the following steps: placing a dispersion containing micro-nano particles with different sizes into a shell; starting a microbubble generator, and driving the micro-nano particles to pass through a screen from bottom to top to carry out dialysis classification to obtain micro-nano particle dispersion liquid in different size ranges.

According to one embodiment of the present disclosure, when the micro-nano particles are charged particles, the method further comprises applying a voltage to the housing in a vertical direction, the voltage being 1V to 100V.

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

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 present disclosure are as follows:

the micro-nano particle size grading device provided by the disclosure can effectively realize the size grading of micro-nano particles by utilizing the dialysis principle and combining micro-bubble power. The device is used for size classification of micro-nano particles, has the advantages of large classification range, accurate classification, short classification time and high efficiency, and can complete effective classification within about 5-15 hours. The device has 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 the disclosure and together with the description serve to explain, but not limit the disclosure.

FIG. 1 is a schematic structural diagram of a micro-nano particle size classifying apparatus according to an embodiment of the present disclosure;

FIGS. 2 to 4 are schematic views each showing a micro-nano particle size classification process according to an embodiment of the present disclosure;

fig. 5 shows a schematic diagram of a specific structure of a micro-nano particle size classifying apparatus according to an embodiment of the present disclosure.

Wherein, the reference numerals are as follows:

100. 100': shell body

201. 201': first screen

202. 202': second screen mesh

300. 300': microbubble generator

400: solvent(s)

500: micro-nano particles

600: microbubbles are provided

700: anode protection net

I. II: feed inlet

III, IV, 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 in the following description. It will be understood that the present disclosure is capable of various modifications in the various embodiments, all without departing from the scope of the present disclosure, and that the description and drawings are intended to be illustrative in nature and not to be limiting of the present disclosure.

In the following description of various exemplary embodiments of the present 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 present disclosure may be practiced. It is to be understood that other specific arrangements of parts, structures, example devices, systems, and steps may be used, 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 exemplary features and elements of the disclosure, these terms are used herein for convenience only, e.g., in accordance with the directions of the examples depicted in the drawings. Nothing in this specification should be construed as requiring a particular three-dimensional orientation of structures to fall within the scope of this disclosure.

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

As shown in fig. 1, in the present embodiment, the micro-nano particle size classifying device provided by the present disclosure mainly includes a housing, a plurality of screens, and a micro-bubble generator, where the micro-nano particles may be particles of graphene, graphene oxide, silica, and the like that can be dispersed in a solvent. It should be noted that fig. 1 is only a partial schematic view of the micro-nano particle size classifying apparatus. Referring now to fig. 2-4, schematic diagrams of micro-nano particle size classification processes incorporating microbubbles and an electric field according to one embodiment of the disclosure are shown, respectively. The structure, connection manner and functional relationship of each main component of an exemplary embodiment of the micro-nano particle size classifying device according to the present disclosure will be described in detail below with reference to the above-mentioned drawings, taking micro-nano particles as an example of graphene oxide.

As shown in fig. 1, the micro-nano particle size classifying apparatus includes a housing 100, a plurality of screens 201, 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 appropriately according to actual needs. The screen mesh is nylon net, metal net or net material processed according to need, corresponding shape screen mesh can be selected according to the shape of the shell, and the mesh shape is square, rectangle, triangle, sphere, irregular sphere or other irregular shape.

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 mesh of the present disclosure may be provided with only 1 screen mesh, and is divided into only 2-stage sheet diameters. Of course, a plurality of the screens of the present disclosure may be provided according to actual needs, for example, 3, 4, etc., to which the present disclosure is not limited. The screen mesh numbers are arranged in the housing 100 at intervals in a sequentially increasing order from bottom to top. Typically, the distance between adjacent screens is from 5cm to 100cm, for example, 5cm, 15cm, 20cm, 30cm, 50cm, 75cm, etc. The first mesh number is 28 mesh to 8000 mesh, for example, 28 mesh, 300 mesh, 600 mesh, 800 mesh, 2000 mesh, 5000 mesh, 8000 mesh, etc., and the second mesh number is 28 mesh to 8000 mesh, for example, 800 mesh, 1000 mesh, 2000 mesh, 5000 mesh, 8000 mesh, etc., and is selected according to the particle size of the actual screening.

The microbubble generator 300, also called as micro-nano bubble generator, has the characteristics of small bubble size, large specific surface area, high adsorption efficiency, low rising speed in water, and the like. As shown in fig. 1, the microbubble generator 300 of the present disclosure is connected to the bottom of the housing 100, and the microbubbles are discharged through the air outlet and enter the housing, so that the micro-nano particles can pass through the plurality of screens 201 and 202 from bottom to top under the driving of the microbubbles, thereby achieving the effect of classifying the sizes of the micro-nano particles.

According to the present disclosure, dialysis is a separation and purification technique that separates small molecules from biological macromolecules by the principle of diffusion of the small molecules through a semi-permeable membrane into water (or buffer). Dialysis is a physical process essentially taking advantage of the concentration differences of substances across a semipermeable membrane. Taking micro-nano particles as Graphene Oxide (GO) as an example, the screen cloth of different mesh numbers is adopted in the present disclosure, so that graphene oxide dispersion liquid can be dialyzed, GO dispersion liquid containing GO with different sheet diameters is injected into the bottom based on the basic principle of concentration difference dialysis, GO with different sheet diameters gradually diffuses upwards due to concentration difference, the minimum sheet diameter can pass through two screen cloths, the middle sheet diameter can only pass through the first screen cloth 201 with larger lower layer aperture, and the large sheet diameter can not pass through the first screen cloth 201 and the second screen cloth 202, so as to be left at the bottom. In the whole classification process, the microbubble generator 300 at the bottom of the container is connected, and through adjusting the size and the yield of the microbubbles, the GO with small sheet diameter can be easily carried out, and the GO with large sheet diameter is not easy to be driven due to the large mass of the GO, so that the microbubbles promote classification, greatly shorten classification time and improve classification efficiency.

In some embodiments, the size of the bubbles generated by the microbubble generator is 200 nm-50 um, for example, 200nm, 500nm, 1um, 20um, 30um, 40um, etc., preferably 0.5 um-20 um, and the flow rate of the bubbles is 20 sccm-2000 sccm, preferably 50 sccm-800 sccm. For the present invention, the size and flow rate of microbubbles play an important role in classification effect, and if the bubbles are too large or the flow rate is too small, the aforementioned classification promoting effect cannot be achieved. If the air bubble quantity is too large, all particles are driven to rapidly ascend, the particles have a certain pressure on the filter screen, and firstly, larger sheet diameters can be caused to squeeze through small filter holes, so that classification is inaccurate; and secondly, the local filter screen is blocked. If the air bubble amount is too small, the classification cannot be effectively accelerated, so that the classification efficiency is low and the time consumption is too long.

In some embodiments, when the micro-nano particles of the present disclosure are charged particles, particle classification may be further facilitated by providing opposing electrodes at both ends of the housing to apply an electric field.

The micro-nano particle classification method according to one embodiment of the present disclosure will be specifically described below with reference to fig. 2 to 4 by taking graphene oxide as an example.

As shown in fig. 2, a dispersion containing micro-nano particles 500 of different sizes is placed in the housing, and then a solvent 400 such as water is added to the housing to fill the entire housing 100.

Next, as shown in fig. 3, the microbubble generator 300 is turned on to generate microbubbles 600 to drive the micro-nano particles 500 to move upwards. Meanwhile, voltage is applied to the device, as the surface of GO has various polar functional groups, GO in the suspension is in a negatively charged state, at this time, a positive electrode can be arranged at the top of the shell 100, a negative electrode can be arranged at the bottom, and an electric field is generated by applying the voltage. As shown in fig. 4, when the small plate size GO is brought up by microbubbles under the action of an electric field, the small plate size GO is attracted by the positive electrode and stably exists near the upper electrode. After a certain time, the GO with different sheet diameters is stably stored in a plurality of areas separated by the screen mesh: the upper layer is small-size GO (driven by micro bubbles and attracted by the positive electrode), the middle layer is middle-size GO (driven by micro bubbles to GO upwards and intercepted by a denser filter screen), and the lower layer is large-size GO (not driven by micro bubbles). Therefore, by utilizing the principles of dialysis and electrophoresis and combining the power generated by micro-bubbles to drive the GO sheets, the multi-stage size separation of GO dispersion liquid is realized by using screens with 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, the method further includes applying a voltage to the shell in a vertical direction, where the applied voltage is not too large or too small to ensure the effect of stabilizing the particles, and is too large to reduce the classification effect, and the voltage is preferably 1V to 100V, for example, 1V, 10V, 30V, 50V, 80V, 100V, etc.

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

Specifically, as shown in fig. 5, an anode access port a and a cathode access port B are respectively provided at the top and bottom of the case 100' for respectively connecting an anode and a cathode, wherein an anode protection net 700 is provided under the anode. The first screen 201 'is near the bottom cathode and the second screen 202' is near the top anode, at which point the device is adapted to sort negatively charged particles in suspension, as described above, if positively charged micro-nano particles are to be sorted, the positions of the cathode and anode may be reversed.

A plurality of inlet and outlet ports and inlet and outlet ports are respectively arranged on the shell 100', comprising: the top and the bottom of the shell 100' are respectively provided with a feed inlet I and a feed inlet II, the other side of the shell 100' is provided with a discharge outlet III and a discharge outlet IV above the first screen 201' and the second screen 202', and the lowest part of the shell 100' is provided with a discharge outlet VI. In addition, a water inlet V is provided above the anode protection net 700. In order to connect the microbubble generator 300', the lowermost part of the housing 100' is provided with a microbubble interface C, and correspondingly, the uppermost part is provided with an exhaust port D to exhaust the surplus gas.

When in use, the suspension containing micro-nano particles can be loaded from the feed inlet I or the feed inlet II according to actual needs, and then water is fed from the water inlet V until the whole container is filled. The anode and the cathode are electrified to form an electric field through the anode access port A and the cathode access port B, the microbubble generator 300' is started, at the moment, the power generated by the microbubbles drives 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 of the micro-nano particles can be realized by using screens with different apertures.

In summary, the present disclosure can achieve precise control of the particle size classification size of particles by utilizing dialysis principles in combination with microbubble dynamics, and the classification range can be large or small (10 nm to 8000 um). The method 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 processes of accelerating microbubbles and attracting electric fields, and the effective classification can be completed within 5-15 hours. In addition, the device disclosed by the invention has the characteristics of simplicity, easiness in implementation, low cost and easiness in industrial application, is simple in maintenance, has no material residue on the screen, is not easy to block, and can be repeatedly used. Because the whole process is physical classification, no new chemicals are introduced in the classification process, and the subsequent process is not influenced. In a word, the micro-nano particle size grading device and the micro-nano particle size grading method can realize controllable separation of micro-nano particles, particularly graphene oxide and the like, so that the regulation and control on the performance of the obtained product are further realized, and the micro-nano particle size grading device and the micro-nano particle size grading method have important significance.

The invention will be further illustrated by the following examples, but the invention is not limited thereby. The reagents used in the present invention are commercially available unless otherwise specified.

Example 1

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

2g of 325 mesh flake graphite is added with 70mL of concentrated sulfuric acid and placed in an ice-water bath for stirring (200 rpm) for 25min; slowly add 10g KMnO ₄ Reacting for 60min; transferring the mixture into a warm water bath at 35 ℃ to continue the reaction for 60min, and stirring at 300rpm; 110mL of deionized water is slowly added, the reaction temperature is kept at 98 ℃, and stirring is carried out for 5min; adding a proper amount of H ₂ O ₂ Until 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, and removing metal ions; fully drying in a vacuum drying oven at 60 ℃ to obtain graphite oxide; dispersing graphite oxide in water to obtain a brown yellow liquid; sonication for 1h gave 2mg/mL GO dispersion.

(2) Size classification of the GO dispersion obtained in 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 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 microbubble generator. Slowly pouring 2g/mL GO dispersion liquid 5L into the bottom of the container, horizontally fixing the screen in the 20L container, wherein the upper side is a 2000-mesh screen, the lower side is a 600-mesh screen, the distance between the screens of each layer is adjustable, and the screens are in a loose state. The vessel is filled with water. And (3) switching on a direct current power supply, and switching on a micro-bubble generator, wherein the flow rate of bubbles is 200sccm, and the size of bubbles is 2 mu m, so as to carry out dialysis. After dialysis for 8 hours, GO sheet size fractionation was completed.

And taking out the GO sheet diameter dispersion liquid with different size ranges after classification, and characterizing the GO sheet diameter dispersion liquid. At least 3 points were taken by SEM in the same batch of samples for a total of at least 90 pieces of sheet diameter data to obtain a sheet diameter average. The sizes of the sheets after classification were 4.1 μm,16.1 μm and 35.3 μm in this order.

Example 2

(1) Preparing GO:

220mL of a mixed acid of concentrated sulfuric acid and phosphoric acid (volume ratio 9:1) was prepared, and the mixed acid was slowly poured into 6g of 800 mesh flake graphite and 48g of KMnO ₄ Is added to the mixture and stirred. The reaction temperature was raised to 40℃and stirring was continued for 10h. The mixed solution was poured into 2500mL of deionized water followed by 150mL of H ₂ O ₂ The solution turned from dark brown to yellow; washing with deionized water and 5% hydrochloric acid for 3 times to neutrality, and removing metal ions and sulfate ions. Fully drying in a vacuum drying oven at 60 ℃ to obtain graphite oxide; dispersing graphite oxide in water to obtain a brown yellow liquid; sonication for 1h gave 3mg/mL GO dispersion.

(2) Size classification of the GO dispersion obtained in step 1):

the screen and the container are cleaned. Electrodes are arranged at the upper end and the lower end of the 4L container and 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 microbubble generator. Slowly pouring 3g/mL GO dispersion liquid 1L into the bottom of the container, horizontally fixing the screen in the 4L container, wherein the upper side is 8000 mesh screen, the lower side is 1000 mesh screen, the distance between the screens of each layer is adjustable, and the screen is in a loose state. The container is filled with water. And (3) switching on a direct current power supply, and switching on a microbubble generator, wherein the flow rate of bubbles is 100sccm, and the size of bubbles is 500nm for dialysis. After 10 hours of dialysis, GO sheet size fractionation was completed.

And taking out the GO sheet diameter dispersion liquid with different size ranges after classification, and characterizing the GO sheet diameter dispersion liquid. At least 3 points were taken by SEM in the same batch of samples for a total of at least 90 pieces of sheet diameter data to obtain a sheet diameter average. The sizes of the sheets after classification were 1.1 μm,5.8 μm and 14.1. Mu.m.

Example 3

The classification method was the same as in example 1, except that no voltage was applied. After 15 hours of dialysis, GO fractionation was completed. And taking out the GO sheet diameter dispersion liquid with different size ranges after classification, and characterizing the GO sheet diameter dispersion liquid. At least 3 points were taken by SEM in the same batch of samples for a total of at least 90 pieces of sheet diameter data to obtain a sheet diameter average. The sizes of the sheets after classification were 4.2 μm,15.6 μm and 35.5 μm in this order.

Comparative example 1

The classification method was different from example 1 in that the microbubble generator was not turned on and no voltage was applied. After 15 hours of dialysis, characterization was performed, and it was found that GO size fractionation was incomplete, with specific individual layer fractionation of 3.9 μm,12.6 μm,30.5 μm. It is illustrated that many small chip sizes do not pass through the screen, so that the average size of the large chip size area is lower.

Comparative example 2

The classification method was the same as in example 1, except that the microbubble generator was not turned on. After 15 hours of dialysis, characterization was performed, and it was found that GO size fractionation was incomplete, with specific individual layer fractionation cases of 4.0 μm,14.6 μm,33.5 μm. It is illustrated that many small chip sizes do not pass through the screen, so that the average size of the large chip size area is lower.

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

Claims (7)

1. A micro-nano particle size classification apparatus, comprising:

a housing;

the screen is arranged in the shell; and

The micro-bubble generator is connected to the bottom of the shell so as to introduce micro-bubbles into the shell;

wherein, the dispersion liquid containing micro-nano particles with different sizes is arranged 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 size grade the micro-nano particles;

the screen mesh is a plurality of screen meshes with different mesh numbers, and the screen meshes are arranged in the shell at intervals from bottom to top according to the order of increasing the screen mesh numbers in sequence;

the top and the bottom of the shell are respectively provided with electrodes with opposite electrical properties;

the size of bubbles generated by the microbubble generator is 200 nm-50 um, and the flow rate of the bubbles is 20 sccm-2000 sccm.

2. The device according to claim 1, wherein the number of the screens is 1-10; when the number of the screens is larger than 1, the distance between every two adjacent screens is 5 cm-100 cm; the volume of the shell is 1L-2500L.

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

4. The device of claim 1, wherein the micro-nano particles are graphene oxide, the top of the housing is provided with a positive electrode, and the bottom is provided with a negative electrode.

5. The apparatus of claim 4, 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 mesh to 8000 mesh, the second screen having a mesh size of 28 mesh to 8000 mesh.

6. A method for classifying micro-nano particle size by using the device of any one of claims 1 to 5, comprising the steps of:

placing a dispersion containing micro-nano particles of different sizes in the housing;

starting the microbubble generator, and driving the micro-nano particles to pass through the screen from bottom to top for dialysis classification to obtain micro-nano particle dispersion liquid in different size ranges;

the size of bubbles generated by the microbubble generator is 200 nm-50 um, and the flow rate of the bubbles is 20 sccm-2000 sccm.

7. The method of claim 6, wherein when the micro-nano particles are charged particles, further comprising applying a voltage to the housing in a vertical direction, the voltage being 1v to 100v, and the dialysis time being 5h to 15h.

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