CN109772243B - Method for efficiently stripping two-dimensional nano material by virtue of supergravity - Google Patents
Method for efficiently stripping two-dimensional nano material by virtue of supergravity Download PDFInfo
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- CN109772243B CN109772243B CN201811420442.6A CN201811420442A CN109772243B CN 109772243 B CN109772243 B CN 109772243B CN 201811420442 A CN201811420442 A CN 201811420442A CN 109772243 B CN109772243 B CN 109772243B
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Abstract
The invention relates to the field of chemical engineering and technology, and provides a method for stripping a two-dimensional nanomaterial by high efficiency and supergravity, aiming at solving the problems of high energy consumption and low efficiency of the existing two-dimensional nanomaterial stripping process, which comprises the following steps: (1) putting the two-dimensional layered material into the dispersion liquid, fully wetting and uniformly mixing to obtain a material dispersion liquid, and then inputting the material dispersion liquid into a circulating storage tank; (2) the material dispersion liquid is output from an outlet at the lower end of the circulating storage tank, enters a central inlet of a secondary rotating flow reactor rotating at a high speed through a pipeline, the material liquid flowing out of an outlet of the reactor enters an inlet of a tube type heat exchanger through a pipeline, the material liquid flowing out of an outlet of the tube type heat exchanger flows back to the circulating storage tank, and the material liquid is circulated for multiple times to obtain the few-layer two-dimensional nano material with the layer number below 3. The invention can realize the rapid, high-efficiency, low-cost, large-batch and high-quality production of various two-dimensional layered nano materials.
Description
Technical Field
The invention relates to the field of chemical engineering and technology, in particular to a method for efficiently stripping a two-dimensional nano material by virtue of supergravity.
Background
The supergravity technology is a new technology for reinforcing the transmission and reaction process of multiphase flow, and has the advantages of small volume, light weight, low energy consumption, easy operation, easy maintenance, safety, reliability, flexibility, adaptability to environment and the like which are not possessed by the traditional equipment, so that the supergravity technology has wide commercial application prospect in the industrial fields of environmental protection, materials, biology, chemical industry and the like. The basic principle of the supergravity engineering technology is to utilize the unique flowing behavior of a multi-phase flow system under the condition of a supergravity field to strengthen the relative speed and mutual contact between phases, thereby realizing the high-efficiency momentum, mass and heat transfer process. The high gravity field is formed by rotating the whole or part of the equipment through a motor to form a centrifugal force field.
The positive and negative energy flows refer to the positive and rapid increase or decrease of mechanical energy in the flowing process of fluid, and the fluid have the relationship of mutual attraction, mutual dependence and mutual transformation. There are two basic ways of rotation: the rotation method comprises the following steps of primary rotation and secondary rotation, wherein the primary rotation means that an object always rotates along one direction, and the secondary rotation means that the rotation direction is reversed once every time the object rotates 180 degrees. The primary rotating flow is characterized in that the direction of a rotating center and the direction of a centrifugal force are always fixed, taking a centrifugal pump as an example, when fluid enters the centrifugal pump, mechanical energy is rapidly reduced along the axial direction, and the primary rotating flow belongs to negative energy flow; when the fluid is thrown outward in the radial direction of the centrifugal pump, the mechanical energy rapidly increases in the radial direction, and the positive energy flow is obtained. The primary rotating flow is a typical positive energy flow as a whole, but the center of the positive energy flow is a negative energy flow, and the positive energy flow and the negative energy flow are completely separated in the primary rotating flow.
The secondary rotating flow is typically a negative energy flow as a whole, and when a fluid containing very high mechanical energy enters the secondary rotating flow channel, the mechanical energy of the fluid is rapidly and uniformly reduced along the flow direction (i.e. axial direction). In synchronization with this, a secondary flow is generated on the flow cross section, the secondary flow belongs to a positive energy flow, and the positive energy flow disappears when the secondary flow reaches an inertial flow state. Therefore, in the initial stage of the secondary rotating flow, the positive energy flow and the negative energy flow are generated simultaneously and are completely merged into a whole, the positive energy flow can fully absorb the energy of the negative energy flow and form dean vortex rotating at high speed, and the formation of the dean vortex is the result and the external expression of uniform distribution of radial shear stress of the fluid. By continuously increasing the supergravity level and the reversal frequency of the secondary rotating flow, the existence time of the positive energy flow in the secondary rotating flow can be prolonged.
The invention discloses a method and a device for efficiently stripping a two-dimensional nano material, and the publication number is CN107139573A, and the invention introduces a method for efficiently stripping the two-dimensional nano material, which is characterized in that a secondary rotating flow mixer is adopted, the rotating direction is reversed every 180 degrees in the flowing process of fluid in the mixer, the intensity of an ultra-high field is increased every time the rotating direction is reversed, and the experimental gravity force finds that the method can realize the effect of efficiently stripping high-quality few-layer graphene (the number of graphene layers can be controlled within the range of less than 3 layers). However, this method still has the obvious disadvantage that the secondary rotating flow reactor needs to be connected with a multistage centrifugal pump and a tubular heat exchanger in series, when the inlet pressure of the secondary rotating flow reactor reaches 2.0MPa, the inlet flow rate is 200 ml/s, and the total mechanical energy of the fluid is about 0.4 kilowatt. In order to achieve the above pressure and flow requirements, the total output power of the multistage centrifugal pump needs 2.0 kw, and the excess mechanical energy of 1.6 kw is dissipated as heat energy into the stripping system, i.e. the effective power of the multistage centrifugal pump is only 20%. In order to control the stripping process to be continuously carried out at a lower temperature, a tubular heat exchanger is required to be connected in series, and the refrigerating fluid in the tubular heat exchanger comes from a refrigerating fluid circulating pump with the total output power of up to 4.0 kilowatts.
Disclosure of Invention
The invention provides a method for stripping two-dimensional nano materials by high efficiency and supergravity, aiming at overcoming the problems in the prior art, and the method can realize the effects of producing various two-dimensional layered nano materials rapidly, efficiently, energy-saving, low-cost, large-batch and high-quality.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for efficiently stripping two-dimensional nano materials by virtue of supergravity comprises the following steps:
(1) putting the two-dimensional layered material into the dispersion liquid, fully wetting the surface of the two-dimensional layered material by the dispersion liquid, uniformly mixing to obtain a material dispersion liquid, and inputting the material dispersion liquid into a circulating storage tank;
(2) the material dispersion liquid is output from an outlet at the lower end of the circulating storage tank, enters a central inlet of a secondary rotating flow reactor rotating at a high speed through a pipeline, the material liquid flowing out of an outlet of the reactor enters an inlet of a tube type heat exchanger through a pipeline, the material liquid flowing out of an outlet of the tube type heat exchanger flows back to the circulating storage tank, and the material liquid is circulated for multiple times to obtain the few-layer two-dimensional nano material with the layer number below 3.
The invention integrates the primary rotation and the secondary rotation into a whole, so that the positive energy flow generated by the primary rotation and the negative energy flow generated by the secondary rotation are integrated into a whole, the positive energy flow is directly converted into the negative energy flow, and the mechanical energy dissipation basically does not exist, thereby obviously reducing the refrigeration power.
Preferably, the secondary rotating flow reactor comprises a rotating disc, an inlet is arranged at the center of the rotating disc, an opening is arranged on the outer side of the rotating disc, and the opening is connected with the inlet through a secondary rotating flow channel; the flow section of the secondary rotating flow channel is circular, so that a uniformly distributed shearing force field and dean vortex can be formed, and the ratio of the minimum secondary rotating radius R to the diameter D of the flow section is more than 5.
The high-speed rotating secondary rotating flow reactor is a rotating disc, an inlet is positioned at the central opening of the rotating disc, and an outlet is positioned at two outermost openings of the rotating disc. In the process of stripping the two-dimensional nano material, the pressure of an inlet and an outlet are completely equal, the reactor is driven by a motor to rotate at a high speed, when a material liquid enters the center of the reactor rotating at a high speed and then is quickly thrown into a secondary rotating flow channel, the high supergravity potential energy of the material liquid in the axial direction in the secondary rotating flow channel is directly converted into the kinetic energy of a dean vortex formed by high-speed rotation in the radial direction, and the loss of mechanical energy in the transferring process caused by the fact that the supergravity potential energy is firstly converted into static pressure energy and then converted into the kinetic energy is avoided. All two-dimensional materials in the dean vortex are thrown to the wall surface by the dean vortex, the two-dimensional materials collide and rub with the wall surface, the strong shearing force between the inner flow layers of the dean vortex provides enough high kinetic energy for the friction of the two-dimensional materials on the wall surface, the two-dimensional materials are rapidly stripped layer by layer to form two-dimensional nano materials (the number of layers is less than 3), and the two-dimensional nano materials stripped by clinging to the wall surface are further stripped by the flow layers from the wall surface to enter the liquid phase main body.
Preferably, the two-dimensional layered material is a fourth to sixth main group semiconductor compound (e.g., GaSe, SnS), a transition metal halide (e.g., PbI)2、MgBr2) Metal oxides (e.g. MnO)2、MoO3) Hexagonal boron nitride (white graphene), graphite phase carbon nitride, transition metal carbides, carbon nitrides, main group IV graphene analogues (semimetal silylenes, germanenes), honeycomb binary compounds of main group IV elements (e.g. SiC, SnGe), main group III to sixth compounds (e.g. InSb, GaN), main group V elements (e.g. phosphenes, arsenes and stibenes), siliconAcid salt, aluminosilicate charge balance membrane (such as mica and clay), and layered hydrotalcite.
Preferably, in the step (1), the concentration of the material dispersion liquid is controlled to be 2.0-8.0 g/L.
Preferably, in step (2), the fluid is co-rotated 360 degrees in a secondary rotating flow channel within the secondary rotating flow reactor, the hypergravity field strength produced by the secondary rotation continuously and rapidly increases during the rotation, the hypergravity field strength continuously and rapidly increases from 3000g to 6000g during the first 180 degree rotation, then the direction of rotation is reversed, and the hypergravity field strength continuously and rapidly increases from 6000g to 9000g during the second 180 degree rotation.
Preferably, the successive rapid increase in the hypergravity field strength produced by the secondary rotation is achieved by successive shortening of the radius of rotation.
Preferably, in the step (2), the supergravity potential energy difference between the inlet and the outlet of the secondary rotating flow reactor rotating at high speed in the stripping process is more than 2.0 MPa.
Preferably, in the step (2), the axial average linear velocity of the material dispersion liquid flowing in the secondary rotating flow channel is not lower than 30 m/s.
Preferably, the secondary rotating flow reactor cavity has a streamline structure, and the smaller the air resistance of the rotating disc in the high-speed rotating process in the cavity is, the better the air resistance is.
Preferably, the temperature during the peeling process is controlled to 0 ℃ or lower.
Preferably, the scale-up mode of the method for stripping the two-dimensional nano material by the supergravity is scale-up.
Therefore, the invention has the following beneficial effects: the process of the invention can realize the rapid, high-efficiency, low-cost, large-batch and high-quality production of various two-dimensional layered nano materials.
Drawings
FIG. 1 is a schematic diagram of the structure of a double spin flow reactor.
FIG. 2 is a schematic diagram of the structure of a rotating disk in a double-spin flow reactor.
In the figure: the rotary table comprises a rotary table 1, a support 2, a motor 3, an inlet 4, an opening 5 and a secondary rotation flow channel 6.
Detailed Description
The technical solution of the present invention is further specifically described below by using specific embodiments and with reference to the accompanying drawings.
In the present invention, all the equipment and materials are commercially available or commonly used in the art, and the methods in the following examples are conventional in the art unless otherwise specified.
The secondary rotating flow reactor used in the invention is shown in figure 1, and comprises a rotating disc 1, wherein the rotating disc is composed of an upper part and a lower part, the rotating disc part shown in figure 1 is a schematic diagram formed by combining the upper part and the lower part of the rotating disc together, the bottom of the rotating disc is provided with a bracket 2, and the rotating disc is fixed on a rotor of a motor 3; the part shown in fig. 2 is the internal structure of the secondary rotation flow path shown after the upper part of the turntable is opened. The center of the rotary table is provided with an inlet 4, the outer side of the rotary table is provided with two openings 5, and the openings are connected with the inlet through a secondary rotating flow passage 6; the flow section of the secondary rotating flow channel is circular, and the ratio of the minimum secondary rotating radius R to the diameter D of the flow section is more than 5; the inner part of the secondary rotating flow reactor cavity is provided with a streamline structure.
Taking the process of preparing the graphene material with few layers by stripping as a specific example, an isopropanol aqueous solution (IPA) is used as a dispersion liquid, the specific gravity of the solution is 0.95 to 0.96g/mL, and flake graphite is used as a raw material.
The specific operation steps are as follows:
(1) putting the flaky graphite into an isopropanol aqueous solution to fully wet the surface of the flaky graphite by a dispersion liquid, uniformly mixing to obtain a graphite body dispersion liquid with the concentration of 4.0g/L, and inputting the graphite body dispersion liquid into a circulating storage tank;
(2) the graphite body dispersion liquid is output from an outlet at the lower end of a circulating storage tank, enters a central inlet of a secondary rotating flow reactor rotating at a high speed through a pipeline, a feed liquid flowing out of an outlet of the reactor enters an inlet of a tubular heat exchanger through a pipeline, the feed liquid flowing out of an outlet of the tubular heat exchanger flows back to the circulating storage tank, and the graphene nano material with the number of layers below 3 is obtained after the circulation is repeated for many times; the fluid rotates 360 degrees in a secondary rotating flow channel in the secondary rotating flow reactor, the intensity of the hypergravity field generated by the secondary rotation is continuously and rapidly increased in the rotating process, the intensity of the hypergravity field is continuously and rapidly increased from 3000g to 6000g in the first 180-degree rotating process, then the rotating direction is reversed, and the intensity of the hypergravity field is continuously and rapidly increased from 6000g to 9000g in the second 180-degree rotating process; the axial average linear velocity of the graphite body dispersion liquid flowing in the secondary rotating flow channel is 40 m/s, and the temperature is controlled below 0 ℃ in the whole stripping process;
in the process of peeling the flaky graphite, the inlet pressure and the outlet pressure of the secondary rotating flow reactor are completely equal, and the supergravity potential energy difference between the inlet and the outlet of the high-speed rotating secondary rotating flow reactor is more than 2.0 MPa. The secondary rotating flow reactor is driven by a motor to rotate at a high speed, when graphite body dispersion liquid enters the center of the secondary rotating flow reactor rotating at a high speed, the graphite body dispersion liquid is quickly thrown into a secondary rotating flow channel, and high supergravity potential energy of the material liquid in the secondary rotating flow channel along the axial direction is directly converted into kinetic energy of dean vortex formed by high-speed rotation along the radial direction, so that the loss of mechanical energy in the transferring process caused by the fact that the supergravity potential energy is firstly converted into static pressure energy and then the static pressure energy is converted into the kinetic energy is avoided. All two-dimensional materials in the dean vortex are thrown to the wall surface by the dean vortex, the two-dimensional materials collide and rub with the wall surface, strong shearing force between inner flow layers of the dean vortex provides enough high kinetic energy for the two-dimensional materials to rub on the wall surface, the two-dimensional materials are rapidly stripped layer by layer to form graphene two-dimensional nano materials (the number of layers is less than 3), and the graphene two-dimensional nano materials which are tightly stripped from the wall surface are then strongly stripped from the wall surface by the flow layers to enter the liquid phase main body.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.
Claims (5)
1. A method for efficiently stripping two-dimensional nano materials by virtue of supergravity is characterized by comprising the following steps:
(1) putting the two-dimensional layered material into the dispersion liquid, fully wetting and uniformly mixing to obtain a material dispersion liquid, and then inputting the material dispersion liquid into a circulating storage tank; the two-dimensional layered material is flaky graphite;
(2) the material dispersion liquid is output from an outlet at the lower end of the circulating storage tank, enters a central inlet of a secondary rotating flow reactor rotating at a high speed through a pipeline, the material liquid flowing out of an outlet of the reactor enters an inlet of a tube type heat exchanger through a pipeline, the material liquid flowing out of an outlet of the tube type heat exchanger flows back to the circulating storage tank, and the material liquid is circulated for multiple times to obtain a few-layer two-dimensional nano material with the layer number below 3; the secondary rotating flow reactor comprises a rotating disc, an inlet is formed in the center of the rotating disc, an opening is formed in the outer side of the rotating disc, and the opening is connected with the inlet through a secondary rotating flow channel; the super-gravitational potential energy difference between the inlet and the outlet of the secondary rotating flow reactor rotating at high speed in the stripping process is more than 2.0 MPa; the flow section of the secondary rotating flow channel is circular, and the ratio of the minimum secondary rotating radius R to the diameter D of the flow section is more than 5; when the material dispersion liquid flows in the secondary rotating flow channel, the axial average linear velocity is not lower than 30 m/s; the fluid co-rotates 360 degrees in a secondary rotating flow channel in the secondary rotating flow reactor, the hypergravity field strength generated by the secondary rotating continuously and rapidly increases in the rotating process, the hypergravity field strength continuously and rapidly increases from 3000g to 6000g in the first 180-degree rotating process, then the rotating direction is reversed, and the hypergravity field strength continuously and rapidly increases from 6000g to 9000g in the second 180-degree rotating process.
2. The method for high-efficiency supergravity exfoliation of two-dimensional nano materials as claimed in claim 1, wherein in the step (1), the concentration of the material dispersion is controlled to be 2.0-8.0 g/L.
3. The method of claim 1, wherein the continuous and rapid increase of the supergravity field strength generated by the secondary rotation is achieved by continuously shortening the radius of rotation.
4. The method for high-efficiency supergravity exfoliation of two-dimensional nano-materials as claimed in claim 1, wherein the secondary rotational flow reactor has a streamlined structure inside the cavity.
5. A method for high efficiency supergravity exfoliation of two-dimensional nano-materials according to any of claims 1-4, wherein the temperature during exfoliation is controlled below 0 ℃.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104401970A (en) * | 2014-10-23 | 2015-03-11 | 江阴碳谷科技有限公司 | Rotary graphene stripping device, graphene production system and production method |
| CN105727811A (en) * | 2016-03-11 | 2016-07-06 | 无锡职业技术学院 | Hybrid graphene stripping system and hybrid graphene stripping method |
| CN105895913A (en) * | 2016-05-04 | 2016-08-24 | 北京化工大学 | Method for preparing two-dimensional material |
| CN107139573A (en) * | 2017-04-01 | 2017-09-08 | 浙江海洋大学 | A kind of efficient method and device for peeling off two-dimensional material |
| CN108630338A (en) * | 2018-03-08 | 2018-10-09 | 北京地泽科技有限公司 | A kind of method, apparatus for producing graphene conductive slurry in batches and graphene conductive slurry prepared therefrom |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| TWI334854B (en) * | 2006-07-28 | 2010-12-21 | Method for manufacturing metal nano-particle |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104401970A (en) * | 2014-10-23 | 2015-03-11 | 江阴碳谷科技有限公司 | Rotary graphene stripping device, graphene production system and production method |
| CN105727811A (en) * | 2016-03-11 | 2016-07-06 | 无锡职业技术学院 | Hybrid graphene stripping system and hybrid graphene stripping method |
| CN105895913A (en) * | 2016-05-04 | 2016-08-24 | 北京化工大学 | Method for preparing two-dimensional material |
| CN107139573A (en) * | 2017-04-01 | 2017-09-08 | 浙江海洋大学 | A kind of efficient method and device for peeling off two-dimensional material |
| CN108630338A (en) * | 2018-03-08 | 2018-10-09 | 北京地泽科技有限公司 | A kind of method, apparatus for producing graphene conductive slurry in batches and graphene conductive slurry prepared therefrom |
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