CN113244772A

CN113244772A - Nanoparticle classification device and method

Info

Publication number: CN113244772A
Application number: CN202110765015.7A
Authority: CN
Inventors: 王晓嗣
Original assignee: Tianjin Development Area Tiandi Information Technology Co ltd
Current assignee: Tianjin Development Area Tiandi Information Technology Co ltd
Priority date: 2021-07-07
Filing date: 2021-07-07
Publication date: 2021-08-13

Abstract

The invention relates to a nanoparticle classification device and method. The cylinder, the bottom plate and the top cover form a closed cavity which is fixed on the frame, and a through hollow shaft is arranged on the bottom plate; a mechanical seal is arranged between the hollow shaft and the upper surface of the bottom plate, and a positioning bearing is arranged between the hollow shaft and the lower surface of the bottom plate; the hollow shaft is arranged in the closed space, an opening channel is arranged on the circumference of the hollow shaft and corresponds to the hollow channel of the ceramic membrane, a supporting plate is arranged on a boss of the hollow shaft, a locking device is arranged at the upper end of the supporting plate, the ceramic membrane is positioned between the supporting plate and the locking device, and a sealing gasket is arranged between the ceramic membranes; the hollow shaft is positioned at the outer part of the closed space, and is provided with a belt pulley and connected with a motor; the bottom end of the hollow shaft is connected with a rotary joint; a feed valve is arranged on the bottom plate; the top cover is provided with a discharge valve. The ceramic membrane rotating dynamic cross flow screening and grading device and method are adopted, the grading precision is high, and the granules with the grain size of 2nm can be graded; compared with plate type filter pressing grading, the grading efficiency of the invention is about 20 times of that of plate type filter pressing grading.

Description

Nanoparticle classification device and method

Technical Field

The invention relates to the technical field of nano material science and engineering, in particular to a nano particle grading device and a nano particle grading method.

Background

In 1981, the invention of Scanning Tunneling Microscope (STM) not only made us, inc, gard binging and Heinrich Rohrer, zurich institute of switzerland, to obtain the nobel physical prize in 1986, but also given scientists and engineers a "key" that opened the field of human unknown: the gate of the nanometer world. From now on, brand-new nanometer science and technology subject emerges and develops rapidly, has become the leading edge of each country's scientific and technological development, and national competitive edge ware improves the important means of national competitiveness and national welfare. STM can see atoms and molecules of less than 0.1 nm on a plane at room temperature, and the depth resolution is 0.01 nm (10 picometers); and can manipulate the movement of atoms. IBM corporation science household STM, moves one atom, spells out three letters: IBM.

Nanometer is a length unit, 1 meter (m) is 1 × 10⁹Nanometer (nm). Scientists line 3.5 gold atoms or 8 hydrogen atoms in a row, which is 1 nanometer (nm) in length. For example, CPU production is entering into the development of 5 nanometer line width and 3 nanometer line width technology. The things of nanometer magnitude exist in nature in a large amount, such as DNA diameter of 2nm and hemoglobin diameter of 5.5nm, and the natural zeolite is a porous material with pore diameter of 0.1-5 nm. In the science and technology of nanometer science, the European and American countries generally consider 1-100 nm as the nanometer scale range, and Asian countries such as China take 0.1-100 nm as the nanometer scale range. Nanoscience is generally considered to be a science of studying the phenomena and manipulations of atomic, molecular, and macromolecular materials that are essentially different from the properties of larger-sized materials; nanotechnology refers to the art of designing, characterizing, manufacturing, and applying structures, devices, and systems of materials at the nanoscale by controlling shapes and sizes. And nanomaterials are the basis of nanoscience and nanotechnology.

Nanomaterials are materials whose at least one dimension is on the nanometer scale. According to the dimension, the nano materials are divided into three categories: 1) the three-dimensional dimensions are all on the nanometer scale, such as: nanoparticles, quantum dots, nanoshells, nanorings, microcapsules, and the like; 2) two-dimensional dimensions are on the nanometer scale, such as: nanotubes, nanofibers, nanowires, and the like; 3) one dimension is on the nanometer scale, such as thin films, thin layers, coatings, etc. Nanomaterials generally fall into two broad categories: 1) unconsciously prepared nanomaterials: such as proteins, viruses, volcanic ash produced by volcanic eruption, nano-particles produced by diesel combustion, etc.; 2) human conscious preparation of nanomaterials: such as metal nano-powder produced by various processes, inorganic nano-powder (oxide, nitride, carbide) synthesized by a liquid phase method, artificially synthesized carbon nano-tube, self-assembled C60, quantum dot, chemically synthesized organic nano-material such as nano-microsphere used in a liquid crystal display device, etc.

The nano material is in nano scale due to the size, and is equivalent to many characteristic sizes in substances, such as the de broglie wavelength of electrons, the superconducting coherence length, the tunneling barrier thickness, the ferromagnetic critical dimension and the like, so that the physical and chemical properties of the nano material and the nano structure are different from those of microscopic atoms, molecules and macroscopic bulk materials, and the capability of exploring nature and creating knowledge is extended to the intermediate field between macroscopic and microscopic objects: mesoscopic field-nano world. The properties of the nano material are completely consistent with the properties of the bulk material, such as the hardness of the nano copper material with the grain size of 50 nanometers, which is prepared by American scientists, is improved by 5 times compared with the hardness of the coarse crystal copper. This is because the properties of nanomaterials are determined by their quantum mechanics and large specific surface area, as well as small size effects. For example, bulk silver is not toxic, while nano-silver can kill viruses in contact with nano-silver particles and exhibit some toxicity; for another example, the coercive force of a 20nm pure iron particle is 1000 times that of a bulk iron, and when the pure iron nanoparticle is further reduced to a certain size, such as 6nm, the coercive force is reduced to 0, so that paramagnetism is represented. Japanese scientists first discovered the nano phenomenon and introduced the nano concept, and they prepared ultra-fine particles by evaporation in the 70 s of the 20 th century and discovered by studying its properties: the copper-silver conductor with electric and heat conduction loses the original performance after being made into a nano scale, and shows that the copper-silver conductor is neither electric nor heat conduction; magnetic materials, such as Fe-Co alloys, are made to be about 20-30nm in size, and the magnetic domain becomes a single magnetic domain, which is 1000 times more magnetic than the original solid. In the middle of the 80's of the 20 th century, the nano-scale materials were named as nano-materials.

Examples of nanostructures and nanofunctionality in nature provide inspiration and reference for the development of new nanostructure and nanofunctionality materials, devices, systems by humans. Such as: butterfly and bird wings-photonic crystals, gecko feet-adhesives, lotus leaf human skin-hydrophobic surfaces, spider silks-high tenacity high strength artificial fibers, and the like. Nanotechnology has been advanced into the aspects of human life. In the health and medical fields, the application of nanotechnology is called nanomedicineThe nanoscale is 100-500nm, and the scale range is just the length size of biomolecules (protein, DNA, enzyme) and biological complexes. Nanomedicine is primarily aimed at creating engineered materials with dimensions comparable to those of biomolecules, such as drug delivery systems, disease imaging probes, and even tissue engineering constructs, to ensure rapid diagnosis, treatment, and course monitoring of patient disease. Carbon nanotubes and nanowires are useful for disease diagnosis. Gold nanoshells are the most effective material for optical image detection of cancer cells. The nanometer technology can realize bone regeneration, tissue and organ regeneration and cranial nerve regeneration. The targeted drug can automatically identify pathological cells, pierce cell membranes and enter the cells to kill pathogenic cells on the molecular level, and the nanotechnology makes the targeted drug possible. In the environmental field, water pollution and soil pollution are main problems facing various countries and are also the problems which are mainly solved by various national governments. By utilizing the nano scientific technology, a novel nano material with special functions can be created to solve various pollution problems, and clean, tidy and sanitary living and working conditions are created for the healthy and beautiful life of people. Scientist laboratories and field experiments show that 1-100 nm nanometer iron powder has complete decomposition and detoxification capability to common environmental pollutants such as chlorinated organic solvents, organic chlorinated pesticides and PCBs, and has no side effect. This effect is completely absent from the micron-sized iron powder. And the nano iron powder can keep activity for 6-8 weeks on a treatment site before being completely dispersed into underground water. This is an advantage of nanoscience. Further research shows that the bimetal nano iron particles, such as iron/palladium nano particles, have better sewage repairing effect than single nano iron particles. Or the nanometer iron powder or the bimetal nanometer powder can be anchored on the activated carbon-based or silicon-based material and used for the allopatric treatment of sewage and industrial wastewater. Semiconductor nanoparticles such as ZnO₂And TiO₂Has photocatalytic properties and can oxidize organic substances such as halocarbons into CO₂，H₂And other components to repair pollution. This is an example of the remediation of contamination by semiconductor photodegradable organic contaminants. Rice University researchers found that rust with a diameter of 10nm can adsorb water under the action of a magnetArsenic. The magnetic nano-particles modified by special functional groups are used for detecting fungi in water. Research also finds that the zero-valent nano iron particles can adsorb and coprecipitate arsenic and arsenate in water. Oil drops in seawater are fatal to oceans and marine organisms, and although the aerogel can adsorb the oil drops, the cost is high; a company called interface science claims to develop a self-assembled monolayer modified nanomaterial that can adsorb 40 times its own weight of oil droplets. This provides a promising solution for purifying seawater. Although nanoparticles are promising in environmental remediation and treatment, concerns remain: once the nanoparticles are absorbed by plants and animals, they may affect the plants and animals themselves. Biodegradable nanoparticles may be preferred. In the field of environmental remediation, nanoparticles are essential for risk assessment and life cycle analysis of the environment. The nano-fiber, nano-absorbent and nano-film modified by special functions can be used for digesting polluted water and air, and the nano-scale reverse osmosis membrane developed by the University of California Los Angeles is used for seawater desalination and sewage treatment, and can repel organic matters and bacteria in water. The membrane is hardly clogged, thereby increasing the life cycle of the membrane and having obvious economic benefits. Nanotechnology is well-established in terms of pollution reduction, e.g. production of environmentally friendly materials such as biodegradable plastics, as well as providing means to increase the efficiency of certain industrial processes, such as increasing the efficiency of catalytic processes; the hydrophobic phenomenon of lotus leaves stimulates scientists to develop self-cleaning coatings and textiles; the nano silver antibacterial coating, the nano silver antimicrobial coating, the fabric and articles for living and household appliances kill viruses and microorganisms. The nano catalyst is used for desulfurizing fuel oil and preventing acid rain in the atmosphere; the nano cerium oxide is added into fuel oil to play a role in catalysis, so that the combustion efficiency is improved, and the fuel is saved. The nano catalyst plays an important role in improving the air quality and eliminating special pollutants in water. The nano gold has extremely high catalytic performance in pollution control research, and can crack carbon monoxide in indoor air at room temperature to remove carbon monoxide in hydrogen fuel cell air supply. Prepared by catalytic cracking of trichloroethylene by using nano gold/platinum co-catalyst in comparison with traditional materialThe catalyst cracks trichloroethylene 100 times faster. The nano metal oxidation catalysis can reduce the hydrogen and carbon compound emission of the diesel engine by 40 percent. Conventional catalysts are predominantly rare earth metals such as palladium. Natural palladium resources are limited and, therefore, the used palladium catalyst is regenerated into metallic palladium. Some strains can reduce divalent palladium particles into nano-grade biological palladium, the catalytic capability of the strain is equivalent to that of commercial nano-palladium particles, and the strain can be used for other catalytic processes. Thus, the regeneration of the rare earth metal catalyst is realized. The nanotechnology invented from energy utilization and material use can make industrial engineering more efficient, and at the same time minimize the generation of toxic waste, and implement green production. For example, in the cleaning industry, the water-based microemulsion is used as a cleaning agent instead of a volatile compound, so that the toxicity and the volatilization amount of the volatile compound are greatly reduced. The development of nanoelectronics has made it possible to manufacture sensors with continuous, real-time monitoring for environmental monitoring. Single-walled carbon nanotubes can be used to detect gaseous molecules, such as NH₃、NO₂The boron-implanted silicon nanowires are used for detecting pathogenic, chemical and biological components in water, atmosphere and food. By reckoning to 2050, the energy consumed all over the world is twice as much as the energy consumed at present, and reaches 28TW, while the energy is mainly from solar energy, wind energy and geographic energy (accounting for 50%), and the world population is increased from 63 hundred million to 90 hundred million at present. Fossil energy is the source of green house gas emissions and climate warming. On the other hand, fossil energy is limited in availability and its supply is on a downward trend. Therefore, renewable energy which can replace petrochemical energy is worthy of great popularization. But the promotion of renewable energy sources faces huge technical challenges: the renewable energy sources (solar energy, wind energy, geothermal energy and hydrogen energy) are efficiently and economically converted into safe and reliable energy sources anytime anywhere. The invention relates to conversion, storage and delivery of renewable energy sources such as solar energy, hydrogen energy and the like, and a nanotechnology can solve a plurality of problems. Solar energy conversion, developing nanocrystalline silicon wafers small enough to turn the indirect band gap into almost direct band gap, greatly increasing the absorption efficiency of sunlight, another approach is to simulate the photon synthesis technology of plant chlorophyll-converted photons, and the technology convertsSolar energy is a storable chemical energy that ultimately becomes carbohydrates, a source of animal food. Artificial photosynthetic cells, conversion efficiency of 12%, are also available. The dye sensitive solar cell and the quantum dot sensitive solar cell greatly improve the conversion efficiency of solar energy by utilizing a nanotechnology. In the dye sensitive solar cell, dye is coated on TiO with node pores (the aperture is 2-50nm)₂The surface can absorb light with various wavelengths, and compared with the traditional photovoltaic product, the photoelectric conversion efficiency is higher. Scientific researches show that quantum dot (nanocrystalline material) sensitive solar cells made of PbSe nano particles with the diameter of less than 10nm absorb one photon to generate 3 electrons, and the nanotechnology can improve the conversion efficiency of the solar cells of today from 20-30% to 65%. Hydrogen energy society: in principle, hydrogen generated by renewable energy sources is an environment-friendly energy carrier in the future and is used for generating electricity and driving automobiles; the best way to generate hydrogen is to electrolyze water using solar energy under the action of an electrolyte. In nature, hydrogen is abundant but not randomly available and must be separated from hydrogen-containing substances by chemical reactions. The most promising way is to split water into hydrogen and oxygen by sunlight using photochemical reactions. Scientists developed TiO with modified band gap₂The nanotube array is used as a photocatalytic surface to generate hydrogen by using sunlight to crack water. In TiO₂Depositing small noble metal islands on the surface of the nanotube array (<5nm) or metal nanoparticles are used to enhance the photocatalytic reaction and increase the amount of hydrogen generated. Other nanotechnologies used to increase hydrogen productivity include carbon-implanted titanium oxide nanotube arrays, single-walled carbon nanotubes, nanostructured hematite films, and the like. Nanoporous carbon foams are used to enhance hydrogen fuel cell utility. The nano-structure solid membrane increases the proton conductivity, the cell efficiency and the durability, and improves the performance of the proton exchange membrane fuel cell. The nanostructured solid film includes a ceramic electrolyte film (e.g., a metal-oxide film), a nanostructured solid electrolyte or a nano-sized filler. The nano material improves the property of the rechargeable battery, and increases the electric capacity, the power supply capacity, the charging rate, the safety, the service life of the battery and the like. Energy conservation is not necessary for social and economic operationCan have few links. Nanotechnology has the potential to play an important role in the field of energy conservation, such as building energy conservation, efficient lighting, use of lightweight materials, efficient transmission of electric energy of a power grid and the like. The nano catalysis technology improves the conversion efficiency. The corrosion-resistant nano coating has obvious energy-saving effect in the whole life cycle. Nanoporous aerogels improve thermal insulation for energy conservation. Organic light emitting diode lighting, quantum dot display technology, etc. are all energy-saving examples. The conducting wire made of the conductive carbon nanotube has lower resistance than a copper wire, is used for electric energy transmission, has lower electric energy loss and huge energy-saving potential, but solves a plurality of difficult technical problems step by step. The information and communication field is one of the fields in which nanoscience and technology play an important role. Computer microprocessors, i.e., Central Processing Units (CPUs), data storage units (memory storage devices) and display units, are important carriers of information and communication technology. At present, Samsung electronics, International Intel corporation in Korea, can produce LSI with a line width of 5 nm. As integrated circuit line widths are further reduced, quantum effects dominate. Next generation electronic devices developed using quantum effects and nano effects can store and process information having quantum effects. Now we use electrical signals to process information, in the future we can use spintronics, molecular electronics, photons, mechanics, electrical resistance, quantum states and magnetic flux to process information. In these ways, nanotechnology plays an important role, and is accomplished by means of new materials and new functional architectures. The Beijing university develops a carbon nanotube transistor prototype in 2020, and opens up a new way for the development of the next generation information and communication technology. Photonics is a subject of studying interaction between light and substances, and the invention of laser and optical fiber creates photonics, which becomes the theoretical basis of optical communication. Optical devices for optical communication have been produced and used in large quantities, and devices for optical computing have been developed in large companies. Quantum communication and quantum computing prototypes have also been developed. The display technology advances rapidly. Ultra-thin, oversized, foldable, rollable display technologies are emerging, where surface nanotechnology and nanomaterials support display technologies and display principles, such as organic light emitting diode technology.Electronic paper displays are also the product of nanotechnology. Various human-computer interface technologies capable of autonomously sensing the surrounding environment enable human-environment interaction to be realized, such as a smart watch for monitoring the physiological state of a body, a smart fabric for collecting movement energy and skin temperature, and nanotechnology supports the development of the technologies and products.

The nanometer scientific technology and the nanometer material support the development of social economy, promote the technological innovation of the whole society and are one of the key technologies for competing the technological high points of various countries. Nanoscience directs the design and manufacture of new materials with innovative properties and functions, such as the properties of reinforced plastics, ceramics, coatings, composites, and the like. In the aspect of material design, the nano science also introduces an overall brand new concept: the design method of material self-assembly from bottom layer to upper layer is derived from the construction of organic and inorganic materials in nature. Natural materials have special functions due to internal nanostructures, such as the hydrophobicity of lotus leaves. The metal nano-particles are excellent particles, and prove how the performance of the material is greatly changed when the material is in a nano scale. Of all metals, the bulk gold is the most noble gold yellow and is very stable (no oxidation, no discoloration) at normal temperature. However, the spherical nanogold is red, and the ring-shaped nanogold is colorless. The gold nanoparticles are very active and are used as catalysts. Ceramic materials are generally considered to be inorganic materials formed by ionic or covalent bonding, have high hardness and stable electrical and thermal properties, and are oxidized by oxides such as Al₂O₃,ZrO₂Nitrides, e.g. Si₃N₄Carbides, such as SiC and the like. Research shows that the mechanical property of the ceramic material sintered by the nano ceramic powder with the same chemical composition is far better than that of the ceramic material sintered by the micron powder. Nanostructured materials, nanoparticles, nanoporous materials, and the like, can be produced by essentially two broad classes of methods: from top to bottom and from bottom to top. From top to bottom, the nanomaterial is obtained by gradually removing material, similar to a machining mode; from bottom to top, as opposed to top to bottom, e.g. nanocoating, atomic or molecular precursors as starting materials, assembled stepwise to form the desired assemblyStructure and performance of. Some top-down methods of fabricating nanomaterials are derived from semiconductor manufacturing processes, such as photolithographic etching and the like. The bottom-up process for producing nanomaterials can be divided into gas-phase and liquid-phase processes. Vapor phase processes such as plasma arc, chemical vapor deposition; liquid phase processes such as sol-gel method, and emerging molecular self-assembly method. The plasma arc can produce nano metal powder and carbon nano tubes; the sol-gel method is to prepare nano particles such as nano alumina powder, nano zirconia powder and the like, nano-structured surfaces and three-dimensional nano-structured materials such as aerogel under the condition of liquid phase.

In general, the material having the longest axis and the shortest axis almost equal to each other in the three-dimensional nano material is called a nanoparticle, such as an approximately spherical metal powder, an inorganic powder synthesized by a liquid phase method, an organic microsphere, and the like. Because the properties of the nano-material are closely related to the size and shape of the nano-material, it is necessary to screen out nano-particles meeting specific properties and specific sizes and shapes according to the particle size of the nano-material. The catalytic activity of the catalyst is greatly related to the size and the shape of the particles of the catalyst, and the cytotoxicity of the nano-silver is closely related to the size of the silver particles. The nano particles are widely applied to sensors, drug carriers, super capacitors, diodes, data storage media, photocatalysis, photonics, photovoltaic cells, ceramic materials, composite materials, macromolecules and the like.

The size and shape of the nanoparticles are closely related to the production process and process conditions, and even under the same synthesis process conditions, the size distribution of the produced nanoparticles may be narrow or wide. Based on the correlation between the performance of the nano material and the size of the nano particles, the sorting out of the nano particles with relatively consistent size and ensuring that the performance of the nano particles is fully exerted becomes a primary and important task. The process of separating particles of a certain size from a stack of particles is size classification, which is called classification for short, and is one of the most important unit operations in powder technology. Two classification techniques, external force field and sieving principle, are used to size classify the nanoparticle size. According to the different forces of the nano particles in the external force field, the size grading of the nano particles is realized, and the grading can be divided into field flow grading, continuous field flow grading, centrifugal field grading, electric field (charged nano particles) grading, magnetic field (only used for magnetic nano particles) grading and the like. External force field grading is carried out in batches and is low in efficiency. Sieving, like flour sieving, uses actual pores or carriers to classify particles. Examples of real pores are membranes, divided into organic and inorganic membranes, used for filtration in tubular or planar form; the carrier refers to a chromatographic column filled with porous materials. In membrane fractionation, the size of the pores of the membrane itself determines the fractionation accuracy: particles smaller in size than the membrane pores permeate the membrane and particles larger in size than the membrane pores cannot permeate the membrane and are retained. The chromatographic column method has different built-in porous materials to form different grading modes, and the pore size of the porous materials and the interaction between particles and the porous materials determine the laminar flow grading efficiency. The small-size material enters the porous material, and the large-size material is left on the porous material in the chromatographic column, so that the material classification is realized. Whether an external force field or screening is used for grading the nano particles, the biggest problem is that the grading efficiency is low, and the urgent need of using the nano particles in various industries in the current society cannot be met. Therefore, efficient and simple nanoparticle classification devices and classification method technologies are urgently needed to meet the requirements of various industries on nanoparticles. Of course, two-dimensional nanomaterials, such as nanofibers, carbon nanotubes, etc., also need to be graded to better perform their optimal performance.

Disclosure of Invention

The invention aims to provide a nanoparticle grading device and a method, wherein the device manufactured by adopting a ceramic membrane high-speed rotating dynamic cross-flow screening grading principle not only can be used for precisely grading three-dimensional nano materials such as nanoparticles, but also can be used for precisely grading two-dimensional nano materials such as nano fibers and carbon nano tubes, so that the grading precision is high, and the nanoparticle with the particle size of 2nm can be graded; the grading efficiency is high, and for nano particles with the same particle size, compared with plate type filter pressing grading, the grading efficiency of the high-speed rotating butterfly ceramic membrane is about 20 times of that of the plate type filter pressing grading; the process is simple, grading equipment with different particle sizes is cascaded, and the nano particles with different particle sizes can be quickly obtained; the technology can realize the automatic continuous operation of nanoparticle grading, and thoroughly change the embarrassment that the external force field and static screening consume long time, are intermittent and have low productivity.

The cross-flow sieving principle is that the liquid/solid and gas/solid mixture of nano particles to be graded is pumped through the pores of filtering membrane with different pore sizes, and under the action of pump pressure, the nano particles suspended in the liquid/solid and gas/solid mixture enter the pores of the filtering membrane under the action of liquid or gas and are carried away by the liquid or gas. The nano particles dispersed into single particles are suspended in liquid or gas, and can easily enter the holes of the filter membrane under the action of pressure, and meanwhile, a small amount of nano particles which are attached to the surface of the membrane and are larger than the aperture of the filter membrane are taken away due to the rotation of the filter membrane, so that the filter membrane is prevented from being blocked, and the normal operation of screening is ensured.

Due to the huge specific surface area of the nano particles, under the action of the dispersing agent, the comprehensive action of electrostatic force, van der waals force, buoyancy and gravity, the nano particles are in a suspension state in liquid, and the action of pump pressure is greater than that of centrifugal force, so that the nano particles flow in the hollow channel of the ceramic membrane by means of liquid or gas, enter the hollow shaft through an opening channel corresponding to the hollow channel of the ceramic membrane on the hollow shaft, are collected and are subjected to subsequent concentration or evaporation to obtain the nano particles. Based on the cross-flow screening principle of ceramic membrane rotation, the precise grading of the nano particles is realized.

The purpose of the invention can be realized by the following technical scheme:

a nanometer particle grading device comprises a closed cavity body formed by a cylinder body, a bottom plate and a top cover, wherein a through hollow shaft is arranged on the bottom plate of the closed cavity body, the hollow shaft is positioned in the part of a closed space, at least one ceramic membrane is arranged on the hollow shaft, and a locking device is arranged at the upper end of the hollow shaft; the part of the hollow shaft, which is positioned outside the closed space, is provided with a belt pulley, the belt pulley is connected with a motor through a belt, a support bearing is arranged below the belt pulley on the hollow shaft, and the lower end of the hollow shaft is connected with a rotary joint; a mechanical seal is arranged between the hollow shaft and the upper surface of the bottom plate, a sealing pressure plate is arranged on the mechanical seal, the sealing pressure plate is fixed on the bottom plate through bolts, a positioning bearing is arranged between the hollow shaft and the lower surface of the bottom plate, the positioning bearing is fixed on the bottom plate through a bearing support of the positioning bearing, and the hollow shaft, the mechanical seal, the positioning bearing and the sealing pressure plate are concentric; the inner part of the closed space of the hollow shaft is provided with opening channels with the number consistent with that of the hollow channels of the ceramic membrane on the circumference, and the size of the opening channels is consistent with that of the hollow channels of the ceramic membrane; a sealing gasket is arranged between the ceramic membranes; a feeding one-way valve is arranged on the bottom plate; the top cover is provided with a discharge one-way valve; the sealed cavity is fixed on the upper surface of the frame by bolts with the help of a bottom plate, the motor is fixed in the frame, and the supporting bearing frame is fixed in the frame.

The hollow shaft is positioned in the closed cavity, a step is arranged at the position close to the mechanical seal, a supporting plate for supporting the ceramic membrane is placed on the step, and the supporting plate is fixed on the hollow shaft through a positioning pin; a sealing gasket is arranged between the supporting plate and the ceramic membrane.

The locking device is an internal thread and an external thread at the upper end of the hollow shaft, a compression nut and an end cover; the ceramic membrane is locked by a compression nut through an external thread at the upper end of the hollow shaft; the internal thread at the upper end of the hollow shaft is screwed into the end cover.

The ceramic membrane is a butterfly ceramic membrane and comprises a membrane layer, a support layer and a hollow channel; the butterfly ceramic membrane is placed between the supporting plate and the locking device on the hollow shaft and is locked by the compression nut; the aperture of the film layer is 2nm to 100nm, and the area of the film is 0.06m²~6m²The hollow channel of the butterfly ceramic membrane is parabolic or linear; recrystallizing silicon carbide or aluminum oxide by using a butterfly ceramic membrane support layer material; the butterfly ceramic membrane layer is made of silicon carbide, titanium oxide or zirconium oxide; the butterfly ceramic membrane is locked by a gland nut through an external thread at the upper end of the hollow shaft, and a sealing gasket is arranged between the butterfly ceramic membrane and the gland nut; the internal thread at the upper end of the hollow shaft is screwed into the end cover; the hollow channel of the butterfly ceramic membrane completely corresponds to the open channel on the circumference of the hollow shaft.

The cylinder body and the bottom plate and the cylinder body and the top cover are fixed through bottom plate bolts and top cover bolts respectively, the cylinder body, the bottom plate and the top cover are made of stainless steel, the cylinder body is lined with polyurethane or wear-resistant ceramic, the upper surface of the bottom plate is sprayed with polyurethane or ceramic, and the lower surface of the cover plate is sprayed with polyurethane or ceramic.

The sealing gasket is made of high polymer materials such as rubber, the thickness of the sealing gasket is 1-3 mm, the inner diameter of the sealing gasket is consistent with that of the butterfly ceramic membrane, and the width of the sealing gasket is 5-10 mm.

The device is used for carrying out the nanoparticle grading method, slurry containing dispersed single nanoparticles enters a closed cavity of the grading device through a feeding one-way valve by means of the pressure of a pump, the nanoparticles are suspended in the slurry, so that the closed cavity is filled with the slurry, and the efficient and precise grading of the nanoparticles is realized by utilizing the cross-flow screening principle of a ceramic membrane rotating in the closed cavity; specifically, a liquid-solid or gas-solid mixture of nano particles dispersed into single particles is connected between a pump and a feeding one-way valve through a pipeline, the nano particles are suspended in slurry to enable the slurry to fill the closed cavity and to be in contact with a ceramic membrane rotating in the closed cavity by virtue of the pressure of the pump and enter the closed cavity through the feeding one-way valve, the ceramic membrane is fixed on a hollow shaft, the hollow shaft is driven to rotate by a motor, the hollow channel of the ceramic membrane corresponds to an opening channel on the hollow shaft, the nano particles with the particle size smaller than a nano hole of a butterfly-type ceramic membrane layer enter the hollow channel of the ceramic membrane by virtue of the flow of liquid or gas by virtue of the pressure of the pump, the nano particles enter the hollow channel of the ceramic membrane by virtue of the shearing force and the like, move to the hollow shaft through the opening channel corresponding to the hollow channel of the ceramic membrane on the hollow shaft, and are led out to a closed material receiving box through a pipeline connected with a rotary joint at the bottom end of the hollow shaft; the nano particles with the particle size larger than the nano holes of the butterfly ceramic membrane layer can not enter the hollow channel of the butterfly ceramic membrane and are left in the closed cavity; therefore, the precise and efficient grading of the nano particles is realized through the cross-flow screening effect of the rotating ceramic membrane.

The rotation speed of the ceramic membrane is 100-1000 rpm.

The nano particle grading device is in multi-stage connection, and is connected with a rotary joint of a previous grading device, such as a feeding one-way valve of a next grading device, by utilizing a conveying pipeline, so that the multi-stage grading device is formed according to the cascade method; multistage classification requires that the pore size of the ceramic membrane in the secondary nanoparticle classification device is smaller than the pore size of the ceramic membrane in the previous stage of nanoparticle classification device.

The invention has the beneficial effects that: the invention adopts the dynamic cross-flow grading screening principle with the nano-scale aperture ceramic membrane as the core to precisely grade nano materials such as nano particles, nano fibers, nano tubes and the like, has high grading efficiency, automatic continuous operation and easy cascade of grading devices, is suitable for research and development stages and laboratories, and is more suitable for large-scale production. The polyurethane material and the ceramic material of the lining prevent the nano particles from directly contacting with the stainless steel, and prevent the metal particles from polluting the nano particles. The grading technology is simple and convenient, has wide application range, is not only suitable for liquid/solid grading, but also suitable for gas/solid grading, such as grading and collecting of nano silver particles in the aerogel nano silver process. The ceramic membrane sealing device has the advantages of large grading area, small occupied area, low energy consumption, more environment-friendly sealing environment, more compact and firm contact of a plurality of ceramic membranes due to the pressing part, high-speed rotation of the rotatable grading component, great reduction of grading time and great reduction of cost.

Drawings

FIG. 1: the invention relates to a nano particle dynamic cross-flow grading screening device and a schematic diagram;

FIG. 2: cross-sectional view of the positioning pin between the support plate and the hollow shaft;

FIG. 3: a schematic diagram of nanoparticle cascade fractionation;

description of reference numerals: 11-circular bottom plate, 12-cylinder, 13-circular top cover, 31-feeding one-way valve, 32-discharging one-way valve, 21-butterfly ceramic membrane, 22-hollow shaft, 23-sealing gasket, 24-supporting plate, 25-compression nut, 26-end cover, 27-positioning pin; 40-sealing pressure plate, 41-mechanical seal, 42-hollow shaft positioning bearing, 43-belt pulley, 44-hollow shaft supporting bearing, 45-motor, 51-rotary joint, leading out classified material, 61-top cover bolt, 62-bottom plate bolt, 210-butterfly ceramic membrane hollow channel, 220-hollow shaft upper opening channel and 221 hollow shaft upper boss; 100-first-stage grading device, 200-second-stage grading device, 131-first-stage grading device feeding one-way valve, 132-first-stage grading device material discharging one-way valve, 151-first-stage grading device material collecting port rotary joint, 231-second-stage grading device feeding one-way valve, 232-second-stage grading device material discharging one-way valve, 251-second-stage grading device material collecting port rotary joint and 300-conveying pipeline.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be apparent that the described embodiments are only some but not all of the embodiments of the present invention. All other embodiments, which can be derived by one of ordinary skill in the art and related arts based on the embodiments of the present invention without any creative effort, shall fall within the protection scope of the present invention.

A nanoparticle fractionation apparatus as shown in fig. 1; the device comprises a closed cavity formed by a cylinder body 12, a circular bottom plate 11 and a circular top cover 13, wherein a through hollow shaft 22 is arranged on the circular bottom plate 11 of the closed cavity; the part of the hollow shaft 22 in the closed space is provided with at least one butterfly ceramic membrane 21, the butterfly ceramic membrane 21 is placed on a support plate 24, the support plate 24 is fixed on the hollow shaft through a positioning pin 27, the upper end of the hollow shaft is provided with a locking device, the upper end of the hollow shaft is provided with an internal thread, an external thread, a compression nut and an end cover, the compression nut 25 is screwed into the external thread at the upper end of the hollow shaft to lock the butterfly ceramic membrane 21, and the end cover 26 is screwed into the upper end of the hollow shaft 22; the part of the hollow shaft outside the closed space is provided with a belt pulley 43, the belt pulley 43 is connected with a motor 45 through a belt, a hollow shaft support bearing 44 is arranged below the hollow shaft belt pulley, and the lower end of the hollow shaft is connected with a rotary joint 51; a mechanical seal 41 is arranged between the hollow shaft 22 and the upper surface of the bottom plate, a sealing pressure plate 40 is arranged on the mechanical seal 41, and the sealing pressure plate 40 is fixed on the circular bottom plate 11 by bolts; a hollow shaft positioning bearing 42 is arranged between the hollow shaft and the lower surface of the circular bottom plate, and the hollow shaft 22, the mechanical seal 41, the hollow shaft positioning bearing 42 and the seal pressing plate 40 are concentric; the circumference of the part of the hollow shaft in the closed space is provided with the uniformly distributed hollow shaft upper opening passages 220 with the same number as the butterfly ceramic membrane hollow passages 210, and the size of the hollow shaft upper opening passages 220 is the same as that of the ceramic membrane hollow passages; a sealing gasket 23 is arranged between the ceramic membranes; the circular bottom plate 11 is provided with a feeding one-way valve 31; the top cover is provided with a discharge one-way valve 32; the round bottom plate 11 is connected with the cylinder 12 through a bottom plate bolt 62, and the round top cover 13 is connected with the cylinder 12 through a bottom plate bolt 62; a closed cavity containing a circular bottom plate 11 is fixed on the upper surface of a frame by bolts, and a motor 45 and a hollow shaft support bearing 44 are fixed in the frame in a bearing frame mode.

The classification device is manufactured by: the upper surface of the circular bottom plate 11 is provided with a mechanical sealing groove, the lower surface of the circular bottom plate is provided with a groove for mounting the hollow shaft positioning bearing 42, the sealing groove and the groove are concentric, and the diameter of the groove is in interference fit with the outer diameter of the bracket of the hollow shaft positioning bearing 42; a hollow shaft upper boss 221 is arranged on the hollow shaft 22 close to the mechanical seal, and a key groove is arranged on the hollow shaft upper boss 221; the circumference of the hollow shaft 22 is provided with hollow shaft upper opening channels 220 with the same number as the hollow channels of the butterfly ceramic membrane 21, the size of the hollow shaft upper opening channels 220 is the same as that of the butterfly ceramic membrane hollow channels 210, the hollow shaft upper opening channels 220 are uniformly distributed on the circumference of the hollow shaft 22, and the butterfly ceramic membrane hollow channels are uniformly distributed on the inner circle circumference of the butterfly ceramic membrane; the lower part of the hollow shaft 22 is provided with a belt pulley positioning step and a support bearing positioning step; fixing a circular bottom plate 11 on a rack, placing a mechanical seal 41 in a mechanical seal groove on the circular bottom plate 11, placing a groove of a bearing support with a hollow shaft positioning bearing 42 at the lower part of the circular bottom plate 11, penetrating a hollow shaft 22 from the upper part of the circular bottom plate into inner holes of the mechanical seal 41 and the hollow shaft positioning bearing 42, fixing the positioning bearing 41 on the circular bottom plate 11, penetrating a seal pressing plate 40 on the hollow shaft 22 to be in contact with the mechanical seal 41, and fixing the seal pressing plate 40 on the circular bottom plate 11; placing a positioning pin 27 in a key groove on a boss 221 on the hollow shaft, placing a supporting plate 24 on the boss 221 on the hollow shaft, fixing the supporting plate 24 on the hollow shaft 22 by using the positioning pin 27, placing a sealing gasket 23, placing a butterfly ceramic membrane 21 on the hollow shaft 22, enabling an opening channel 210 on the hollow shaft of the butterfly ceramic membrane 21 to correspond to an opening channel 220 on the hollow shaft on the circumference of the hollow shaft, sequentially placing the sealing gasket 23 and the ceramic membrane 21 on the hollow shaft 22, enabling the butterfly ceramic membrane hollow channel 210 of the butterfly ceramic membrane 21 to correspond to the opening channel 220 on the hollow shaft 22 until the upper thread part of the hollow shaft 22, placing the sealing gasket 23 on the upper surface of the uppermost butterfly ceramic membrane 21, screwing a compression nut 25, enabling the hollow shaft 22 and the butterfly ceramic membrane 21 to be tightly contacted into a whole, and screwing an end cover 26 on the hollow shaft 22; placing a seam allowance of the cylinder body 12 in a groove of the circular bottom plate 11, arranging a sealing ring in a sealing groove on the upper surface of the circular bottom plate 11, fixing the circular bottom plate 11 and the cylinder body 12 by using a bottom plate bolt 62, and screwing the bottom plate bolt 62 by using a torque wrench to enable the torque of the bottom plate bolt 62 to be consistent; a feeding one-way valve 31 is arranged on the circular bottom plate 11; placing a groove of the top cover 13 on the cylinder body 12, placing a sealing ring in a sealing groove on the lower surface of the circular top cover 13, fixing the circular top cover 13 and the cylinder body 12 by using a top cover bolt 61, and screwing the top cover bolt 61 by using a torque wrench to enable the torque of the top cover bolt 61 to be consistent; a discharge check valve 32 is arranged on the circular top cover 13; fixing the belt pulley 43 on the belt pulley positioning step of the hollow shaft 22 by using a key and a jackscrew, fixing the motor 45 in a frame, connecting the motor 45 with the belt pulley 43, positioning the hollow shaft 22 by using a hollow shaft support bearing 44 at the position of the bearing support step to enable the hollow shaft 22 to rotate more stably, fixing the bearing frame of the hollow shaft support bearing 44 in the frame, and connecting the bottom end of the hollow shaft 22 with a rotary joint 51; all bolts of the round bottom plate 11 fixed on the frame are screwed down by a torque wrench; the butterfly ceramic membrane 21 in the closed space rotates together with the hollow shaft 22; grading devices with different apertures are cascaded, and particles with various particle sizes are obtained through one-time operation.

A nano particle grading method, which is a slurry of single nano particles uniformly dispersed, the nano particles are suspended in the slurry, the slurry enters a closed cavity formed by a circular bottom plate 11, a cylinder 12 and a circular top cover 13 of the grading device through a feeding one-way valve 31 of the grading device by means of the pressure of a pump, the pump is connected with the feeding one-way valve through a pipeline, so that the whole closed cavity is filled with the slurry, the slurry contacts with the surfaces of a plurality of butterfly ceramic membranes 21 with nanometer apertures rotating in the closed cavity, the particle diameter of the slurry is less than or equal to the nanometer particles of the nanometer apertures of the butterfly ceramic membranes 21, under the action of pump pressure and shearing force, the liquid or gas flows into the ceramic membrane, passes through the hollow channel 210 of the butterfly ceramic membrane and the open channel 220 on the hollow shaft 22, further moving to the hollow shaft 22, and collecting into a closed container through the rotary joint 51 and a hose connected to the bottom of the rotary joint 51; the nano particles with the particle size larger than the nano-scale holes of the membrane layer of the butterfly ceramic membrane component in the slurry can not enter the butterfly ceramic membrane 21 and are left in the closed space, and then the nano particles are extracted out of the closed space through the discharging one-way valve 32; the slurry which is continuously pumped and evenly dispersed into single nano particles is filled in the whole closed cavity, is contacted with the surface of the rotating butterfly ceramic membrane 21 with the nano aperture under the action of pump pressure and shearing force, enters the ceramic membrane by the flowing of liquid or gas, and realizes the precise grading of the nano particles by utilizing the cross flow screening principle of the ceramic membrane with the nano aperture.

The butterfly ceramic membrane with the nano aperture has the aperture of 2 nm-100 nm, and the ceramic membrane layer is made of zirconium oxide, titanium oxide or silicon carbide; the ceramic membrane supporting layer is made of aluminum oxide or recrystallized silicon carbide; a grading device consisting of a plurality of butterfly ceramic membranes, the grading area of which is 0.06m²~6m²The rotating speed of the rotary speed is continuously adjustable between 100rpm and 1000 rpm. The interior of the cylinder 12, the bottom plate 11 and the top cover 13 are made of stainless steel lined with polyurethane or wear-resistant ceramic; the butterfly ceramic membrane with the nano aperture has a hollow channel in a parabolic shape or a linear shape. The wear resistant ceramic is an oxide, nitride or carbide.

The specific operation of the device is as follows:

example 1

Grading to obtain 100nm coprecipitation zirconia powder

The method comprises the steps of selecting a closed cavity consisting of a stainless steel cylinder body 12 with a polyurethane lining, a polyurethane coating circular upper cover 13 and a circular bottom plate 11, forming a stainless steel hollow shaft 22, a butterfly ceramic membrane 21 with a 100 nm-diameter membrane layer titanium oxide and a support layer alumina material, wherein a butterfly ceramic membrane hollow channel 210 of the butterfly ceramic membrane 21 is in a parabolic shape, the outer diameter of the upper half part of the hollow shaft is 90mm, the inner diameter of a rubber sealing gasket 23 is 90mm, the width of the rubber sealing gasket is 10mm, the thickness of the butterfly ceramic membrane 21 is 1mm, the inner diameter of the butterfly ceramic membrane 21 is 90mm, the outer diameter of the butterfly ceramic membrane is 380mm, the thickness of the butterfly ceramic membrane is 6mm, 60 pieces are formed, and the total membrane surface area is 6m²The rotation speed of the butterfly ceramic membrane component is 1000 rpm. Closing the discharge one-way valve 32, opening the feed one-way valve 31, pumping zirconia slurry into the polyurethane-lined closed cavity by using a peristaltic pump to fill the slurry into the whole closed cavity, starting a motor to adjust the rotating speed of the motor so that the rotating speed of the butterfly ceramic membrane is 1000rpm, enabling zirconia particles with the particle size of 100nm or less in the slurry to enter the surface of the rotating butterfly ceramic membrane 21 with the pore diameter of 100nm, and flowing into the hollow through cavity of the butterfly ceramic membraneThe channel 210 enters the hollow shaft and flows into the closed material receiving box through a pipeline connected with the lower end of the rotary joint 51; zirconia particles with the particle size of more than 100nm in the slurry are left in the closed cavity; when the operation is carried out for 4 hours, the feeding valve 31 is closed, the rotation of the butterfly ceramic membrane component is stopped, the discharging valve 32 is opened, zirconium oxide particles with the particle size of more than 100nm are pumped away by a peristaltic pump, and the powder taken from the closed material receiving box is observed by a transmission electron microscope, wherein the average particle size is 97.0 +/-3.0 nm; this operation achieves continuous fine classification of nanoparticles.

Example 2

The 20nm hydrothermal alumina powder is obtained by classification

A closed cavity consisting of a stainless steel cylinder 12 with an alumina ceramic lining, a polyurethane coated round upper cover 13 and a round bottom plate 11 is selected; a hollow shaft 22 made of stainless steel, a butterfly ceramic membrane 21 made of a membrane layer titanium oxide with the aperture of 20nm and a support layer alumina, wherein the butterfly ceramic membrane 21 and the butterfly ceramic membrane hollow channel 210 are linear, the outer diameter of the upper half part of the hollow shaft is 90mm, the inner diameter of the rubber sealing gasket 23 is 90mm, the width of the rubber sealing gasket is 10mm, the thickness of the rubber sealing gasket is 3mm, the inner diameter of the butterfly ceramic membrane 21 is 90mm, the outer diameter of the butterfly ceramic membrane is 380mm, the thickness of the butterfly ceramic membrane is 6mm²The rotation speed of the butterfly ceramic membrane component is 1000 rpm. Closing the material discharging one-way valve 32, opening the material feeding one-way valve 31, pumping alumina slurry into a closed cavity of the ceramic lining by using a peristaltic pump to fill the whole closed cavity with the slurry, starting a motor to adjust the rotating speed of the motor so that the rotating speed of the butterfly ceramic membrane is 1000rpm, enabling alumina particles with the particle size of 20nm or less in the slurry to enter the surface of the rotating butterfly ceramic membrane 21 with the aperture of 20nm, flowing into the middle runner 210 of the butterfly ceramic membrane to enter the hollow shaft, and flowing into a closed material receiving box through a pipeline connected with the lower end of the rotary joint 51; zirconia particles with the particle size of more than 20nm in the slurry are left in the closed cavity; when the operation is carried out for 6 hours, the feeding valve 31 is closed, the rotation of the butterfly ceramic membrane component is stopped, the discharging valve 32 is opened, and alumina particles with the particle size larger than 20nm are pumped away by a peristaltic pump; observing the powder taken from the closed material receiving box by using a transmission electron microscope, wherein the average grain diameter is 20.0 +/-2.0 nm; this operation achieves continuous fine classification of nanoparticles.

Example 3

Grading to obtain 20nm iron particles

The hollow channel 210 of the butterfly ceramic membrane is a linear type, the outer diameter of the upper half part of the hollow shaft is 90mm, the inner diameter of the rubber sealing gasket 23 is 90mm, the width is 8mm, the thickness is 2mm, the inner diameter of the butterfly ceramic membrane 21 is 90mm, the outer diameter is 380mm, the thickness is 6mm, 50 pieces, and the total membrane surface area is 5m²The butterfly ceramic membrane module rotates at 500 rpm. Closing the discharge one-way valve 32, opening the feed one-way valve 31, pumping iron powder slurry with ethanol as a solvent into a closed cavity with a polyurethane lining by using a peristaltic pump to fill the whole closed cavity with the slurry, starting a motor to adjust the rotating speed of the motor so that the rotating speed of the butterfly ceramic membrane is 500rpm, allowing iron particles with the particle size of 20nm or less in the slurry to enter the surface of the rotating butterfly ceramic membrane 21 with the pore size of 20nm, flowing into the middle runner 210 of the butterfly ceramic membrane to enter a hollow shaft, and flowing into a closed material receiving box through a pipeline connected with the lower end of the rotary joint 51; iron particles with the particle size of more than 20nm in the slurry are left in the closed cavity; the operation is carried out for 6 hours, the feed valve (31) is closed, the rotation of the butterfly ceramic membrane component is stopped, the discharge valve 32 is opened, and iron particles with the particle size larger than 20nm are pumped away by a peristaltic pump; observing the powder taken from the closed material receiving box by using a transmission electron microscope, wherein the average grain diameter is 20.0 +/-2.0 nm; this operation achieves continuous fine classification of nanoparticles.

Example 4

Grading 5nm and 2nm silver particles from aerogel method nano silver powder

With the multi-stage arrangement as described in fig. 3, each stage configuration is as shown in fig. 1 and 2. First-stage classification device 100: the butterfly ceramic membrane type ceramic membrane bioreactor comprises a stainless steel cylinder body 12 with a silicon carbide ceramic lining, an aluminum oxide ceramic coating circular upper cover 13 and a circular bottom plate 11, wherein the stainless steel cylinder body, the aluminum oxide ceramic coating circular upper cover and the circular bottom plate form a closed cavity, a stainless steel hollow shaft 22, a butterfly ceramic membrane 21 with a 5 nm-film layer of silicon carbide and a support layer of recrystallized silicon carbide, the butterfly ceramic membrane hollow channel 210 is of a parabolic shape, the outer diameter of the upper half part of the hollow shaft is 40mm, the inner diameter of a rubber sealing gasket 23 is 40mm, the width of the rubber sealing gasket is 5mm, the thickness of the rubber sealing gasket is 1mm, the inner diameter of the butterfly ceramic membrane 21 is 40mm, the outer diameter of the butterfly ceramic membrane is 200mm, the thickness of the butterfly ceramic membrane is 6mm, 50 pieces, and the total membrane surface area is 3m²。

Second-stage classification device 200: the butterfly ceramic membrane is characterized in that a stainless steel cylinder body 12 with a silicon carbide ceramic lining, a ceramic coating circular upper cover 13 and a circular bottom plate 11 are selected to form a closed cavity, a stainless steel hollow shaft 22, a butterfly ceramic membrane 21 with a 2 nm-aperture membrane layer of silicon carbide and a support layer of recrystallized silicon carbide, a butterfly ceramic membrane hollow channel 210 is parabolic, the outer diameter of the upper half part of the hollow shaft is 40mm, the inner diameter of a rubber sealing gasket 23 is 40mm, the width of the hollow shaft is 5mm, the thickness of the hollow shaft is 1mm, the inner diameter of the butterfly ceramic membrane is 40mm, the outer diameter of the butterfly ceramic membrane is 200mm, the thickness of the butterfly ceramic membrane is 6mm, 35 pieces, and the total membrane surface area is 2m²。

The first stage classifier material collection port swivel 151 and the second stage classifier feed check valve 231 are connected by a transfer hose 300. The rotating speeds of the butterfly ceramic membrane components of the first-stage grading device and the second-stage grading device are both 100 rpm.

Closing the discharge valve 132 and the material discharge one-way valve 232 of the second-stage grading device, opening the feed one-way valve 131 and the feed one-way valve 231 of the second-stage grading device, pumping the gas containing nano silver particles into the feed one-way valve 131 of the first-stage grading device by using a diaphragm pump to ensure that the gas is filled in the sealed cavity, adjusting the rotating speed of the butterfly ceramic membrane to 100rpm, keeping the silver particles with the particle diameter of more than 5nm in the gas in the sealed cavity of the first-stage grading device, enabling the silver particles with the particle diameter of 5nm and below in the gas to enter the surface of the butterfly ceramic membrane in the rotating first-stage grading device with the pore diameter of 5nm, enabling the silver particles to flow into the middle channel of the butterfly ceramic membrane of the first-stage grading device to enter the hollow shaft, and then enter the sealed cavity of the second-stage grading device through the conveying pipeline 300 connected with the lower end of the material collecting port rotary joint 151 of the first-stage grading device and the feed one-way valve 231 of the second-stage grading device, flowing into a butterfly ceramic membrane made of film layer silicon carbide with the second-stage aperture of 2nm and silicon carbide of a support layer, and leaving silver particles with the particle diameter of more than 2nm and less than 5nm in the gas in a closed cavity of the second-stage grading device; silver particles with the particle size of less than 2nm enter a butterfly ceramic membrane hollow channel in the second-stage grading device and flow into a closed material receiving box through a pipeline connected with the lower end of the rotary joint 251. The first-stage grading system and the second-stage grading system operate for 6 hours, the feed valve 131 of the first-stage grading device and the feed valve 231 of the second-stage grading device are closed, the butterfly ceramic membrane assemblies of the first-stage grading system and the second-stage grading system stop rotating, the discharge valve 132 of the first-stage grading system is opened, silver particles with the particle size larger than 5nm are pumped away by a peristaltic pump, the discharge valve 232 of the second-stage grading system is opened, and silver particles with the particle size smaller than 5nm are pumped away by the peristaltic pump; respectively observing silver particles taken from a discharge opening 232 of the second-stage grading system and nano silver particles in a closed cavity connected with the second-stage grading device by using a Scanning Tunneling Microscope (STM), wherein the nano silver particle diameter taken from the first-stage grading system is 4.80 +/-0.2 nm, and the nano silver particle diameter taken from the second-stage grading system is 1.80 +/-0.2 nm; this operation achieves continuous fine classification of nanoparticles.

Example 5

Grading to obtain 5nm copper particles

The butterfly ceramic membrane is characterized in that a stainless steel cylinder 12 with a silicon nitride ceramic lining, an aluminum oxide ceramic coating circular upper cover 13 and a circular bottom plate 11 are selected to form a closed cavity, a stainless steel hollow shaft 22 is made of a stainless steel material, a butterfly ceramic membrane 21 with a 5 nm-aperture membrane layer and silicon carbide supporting body weight crystallization silicon carbide material is made of a butterfly ceramic membrane, a hollow channel 210 of the butterfly ceramic membrane is in a parabolic shape, the outer diameter of the upper half part of the hollow shaft is 40mm, the inner diameter of a rubber sealing gasket 23 is 40mm, the width of the rubber sealing gasket is 5mm, the thickness of the rubber sealing gasket is 1mm, the inner diameter of the butterfly ceramic membrane 21 is 40mm, the outer diameter of the butterfly ceramic membrane is 200mm, the thickness of the butterfly ceramic membrane is 6mm, the number of 1, and the total membrane surface area is 0.06m²The butterfly ceramic membrane module rotates at 500 rpm. Closing the discharge one-way valve 32, opening the feed one-way valve 31, pumping copper powder slurry taking ethanol as a solvent into a closed cavity of the silicon nitride ceramic lining by using a peristaltic pump to fill the whole closed cavity with the slurry, starting a motor to adjust the rotating speed of the motor so that the rotating speed of the butterfly ceramic membrane is 500rpm, enabling copper particles with the particle size of 5nm or less in the slurry to enter the surface of the rotating butterfly ceramic membrane 21 with the pore size of 5nm, flowing into the hollow channel 210 of the butterfly ceramic membrane to enter the hollow shaft, and flowing into a closed material receiving box through a pipeline connected with the lower end of the rotary joint 51; copper particles with the particle size of more than 5nm in the slurry are left in the closed cavity; the operation is carried out for 6 hours, the feeding one-way valve 31 is closed, the rotation of the butterfly ceramic membrane component is stopped, the discharging one-way valve 32 is opened, and copper particles with the particle size larger than 5nm are pumped away by a peristaltic pump; observing the powder taken from the closed material receiving box by using a transmission electron microscope, wherein the average grain diameter is 5.0 +/-2.0 nm; thus operating to realize nanometerAnd (4) continuously and precisely grading the particles.

The invention can also be used for concentrating the nano-slurry, removing impurities in the nano-slurry by a dissolving method, and recovering the organic solvent to realize gas/solid separation; large particle particles in the chemical mechanical polishing liquid of the semiconductor wafer are filtered, and the yield of the wafer is improved; the device is used for filtering grinding fluid of the solar photovoltaic wafer multi-wire cutting machine, treating urban sewage, improving water quality of domestic water and the like. The dynamic cross-flow filtration is formed by using the butterfly ceramic membrane with the micron-sized aperture, so that the micron-sized powder particles can be accurately classified, the micro-powder slurry can be concentrated, soluble impurities in the slurry can be removed, the urban sewage can be treated, and the like, and thus the application range of the device and the method can be greatly expanded.

The preferred embodiments of the invention disclosed above are intended only to aid in the description of the invention. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations will be apparent to those skilled in the art in light of the present disclosure, and the embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. The nano particle grading device is characterized in that a closed cavity is formed by a cylinder body, a bottom plate and a top cover, a through hollow shaft is arranged on the bottom plate of the closed cavity, the hollow shaft is positioned in the closed cavity, at least one ceramic membrane is arranged on the hollow shaft, and a locking device is arranged at the upper end of the hollow shaft; the part of the hollow shaft, which is positioned outside the closed cavity body, is provided with a belt pulley, and the belt pulley is connected with a motor through a belt; a support bearing is arranged below the belt pulley of the hollow shaft, and the lower end of the hollow shaft is connected with a rotary joint; a mechanical seal is arranged between the hollow shaft and the upper surface of the bottom plate, a positioning bearing is arranged between the hollow shaft and the lower surface of the bottom plate, and the hollow shaft, the mechanical seal and the positioning bearing are concentric; the circumference of the hollow shaft in the closed cavity is provided with opening channels with the number consistent with that of the ceramic membrane hollow channels, and the size of the opening channels is consistent with that of the ceramic membrane hollow channels; a sealing gasket is arranged between the ceramic membranes; the bottom plate is provided with a feeding one-way valve which is connected with the pump through a pipeline; the top cover is provided with a discharge one-way valve.

2. The apparatus for nanoparticle fractionation according to claim 1, wherein the hollow shaft is provided at a portion thereof located in the closed chamber, and a step is provided at a position close to the mechanical seal, and a support plate for supporting the ceramic membrane is placed on the step and fixed to the hollow shaft by a positioning pin; a sealing gasket is arranged between the supporting plate and the ceramic membrane.

3. The apparatus for nanoparticle classification as claimed in claim 1, wherein the locking means is a hollow shaft provided with internal and external threads at its upper end, a compression nut and an end cap; the ceramic membrane is locked by a compression nut through an external thread at the upper end of the hollow shaft; the internal thread at the upper end of the hollow shaft is screwed into the end cover.

4. The nanoparticle fractionation apparatus of claim 1, wherein the ceramic membrane is a butterfly ceramic membrane comprising a membrane layer, a support layer, and hollow channels; the butterfly ceramic membrane is placed between the supporting plate and the locking device on the hollow shaft and is locked by the compression nut; the aperture of the film layer is 2 nm-100 nm, and the area of the film layer is 0.06m²~6m²The film material is silicon carbide, titanium oxide or zirconium oxide; the hollow channel is parabolic or linear; the support layer is recrystallized silicon carbide or aluminum oxide.

5. The apparatus for fractionating nanoparticles according to claim 1, wherein the cylinder and the base plate and the cylinder and the top cover are fixed by bolts, the cylinder, the base plate and the top cover are made of stainless steel, and the inner surface of the cylinder is lined with polyurethane or wear-resistant ceramic.

6. The nanoparticle classifying apparatus according to claim 1, wherein the gasket has a thickness of 1 to 3mm and a width of 5 to 10 mm.

7. The apparatus for fractionating nanoparticles according to claim 1, wherein a multistage connection is adopted, and a rotary joint of a preceding stage of the fractionating apparatus and a feed check valve of a next stage of the fractionating apparatus are connected by a transfer pipe, and a multistage fractionating apparatus is constituted according to this cascade method; multistage classification requires that the pore size of the ceramic membrane in the secondary nanoparticle classification device is smaller than the pore size of the ceramic membrane in the previous stage of nanoparticle classification device.

8. The nanoparticle classifying apparatus according to claim 1, wherein the ceramic membrane rotates at 100 to 1000 rpm.

9. A method for grading nanoparticles using the device according to any of claims 1 to 8, characterized in that a slurry containing the dispersed individual nanoparticles is fed into the closed chamber of the grading device through a feed check valve by means of the pressure of a pump, the nanoparticles are suspended in the slurry such that the closed chamber is filled with the slurry, and efficient and precise grading of the nanoparticles is achieved by means of the cross-flow sieving principle of the ceramic membrane rotating in the closed chamber.

10. The method for nanoparticle classification as claimed in claim 9, wherein the nanoparticles are suspended in a slurry such that the slurry fills a closed chamber and contacts a ceramic membrane rotating in the closed chamber, the ceramic membrane is fixed on a hollow shaft, the hollow shaft is rotated by a motor, the hollow channel of the ceramic membrane completely corresponds to an open channel on the hollow shaft, the nanoparticles having a particle size equal to or smaller than the nanopore of the ceramic membrane layer enter the hollow channel of the ceramic membrane by the flow of liquid or gas by means of pump pressure, shearing force, etc., move to the hollow shaft through the open channel on the hollow shaft corresponding to the hollow channel of the ceramic membrane, and are led out to a closed collection box through a pipe connected to a rotary joint at the bottom end of the hollow shaft; the nano particles with the particle size larger than the nano holes of the ceramic membrane layer can not enter the hollow channel of the ceramic membrane and are left in the closed cavity; therefore, the precise and efficient grading of the nano particles is realized through the cross-flow screening effect of the rotating ceramic membrane.