CN115403034A - Method for purifying single-walled carbon nanotube with high purity and high conversion rate - Google Patents
Method for purifying single-walled carbon nanotube with high purity and high conversion rate Download PDFInfo
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- 230000003647 oxidation Effects 0.000 claims abstract description 22
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 22
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- 238000001035 drying Methods 0.000 claims abstract description 19
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- 238000010438 heat treatment Methods 0.000 claims abstract description 15
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- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 20
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- 238000001354 calcination Methods 0.000 claims description 11
- 229910052742 iron Inorganic materials 0.000 claims description 11
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 9
- 229910017604 nitric acid Inorganic materials 0.000 claims description 9
- 238000010298 pulverizing process Methods 0.000 claims description 7
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- 239000007789 gas Substances 0.000 claims description 4
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- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/158—Carbon nanotubes
- C01B32/168—After-treatment
- C01B32/17—Purification
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/158—Carbon nanotubes
- C01B32/159—Carbon nanotubes single-walled
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2202/00—Structure or properties of carbon nanotubes
- C01B2202/20—Nanotubes characterized by their properties
- C01B2202/30—Purity
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Abstract
The invention belongs to the technical field of purification, and particularly relates to a method for purifying a single-walled carbon nanotube with high purity and high conversion rate, which comprises the following steps: step one, pretreating a single-walled carbon nanotube crude product prepared by a CVD method; step two, carrying out ultrasonic dispersion on the single-walled carbon nanotube treated in the step one, a surfactant and an organic solvent, washing to be neutral, filtering, and finally freeze-drying; step three, carrying out high-temperature oxidation treatment on the single-walled carbon nanotube treated in the step two; step four, placing the single-walled carbon nanotube subjected to high-temperature oxidation treatment in a mixed acid solution, and heating while stirring; and step five, washing the single-walled carbon nanotube reacted in the step four to be neutral, filtering and drying to obtain the purified single-walled carbon nanotube. The purification method has simple steps and convenient operation, can prepare the single-walled carbon nanotube with low loss and high purity, the purity can reach more than 99 percent, and the conversion rate of the finished product can reach more than 62 percent.
Description
Technical Field
The invention belongs to the technical field of purification, and particularly relates to a method for purifying a single-walled carbon nanotube with high purity and high conversion rate.
Background
The carbon nano tube is used as a one-dimensional nano material, has light weight, perfect connection of a hexagonal structure and a plurality of abnormal mechanical, electrical and chemical properties. With the research on carbon nanotubes and nanomaterials, the broad application prospects thereof are continuously revealed in recent years. Carbon nanotubes can be regarded as being formed by winding graphene sheets, and thus can be classified into single-walled carbon nanotubes and multi-walled carbon nanotubes according to the number of graphene sheets. Compared with multi-wall carbon nano tubes, the single-wall carbon nano tubes have small diameter distribution range, less defects and higher uniformity. The typical diameter of the single-walled carbon nanotube is 0.6-2nm, the innermost layer of the multi-walled carbon nanotube can reach 0.4nm, the thickest layer can reach hundreds of nanometers, but the typical pipe diameter is 2-100nm.
At present, a plurality of methods for preparing the carbon nanotubes are commonly known as an arc discharge method, a laser evaporation method and a Chemical Vapor Deposition (CVD) method, however, the carbon nanotubes prepared by these methods usually contain impurities such as amorphous carbon, carbon nanoparticles and catalyst particles, and the presence of these impurities affects the performance test and application research of the carbon nanotubes, so that the intensive research on the purification of the carbon nanotubes is very necessary and important.
The multi-walled carbon nano-tube is purified by adopting the existing purification technology, and the purity of the purified multi-walled carbon nano-tube can reach more than 99 percent. However, in the prior art, the iron catalyst is adopted to produce the single-walled carbon nanotube, the diameter of the produced iron-based carbon nanotube is small, and the single-walled carbon nanotube is tightly combined with iron impurities, so that the purification difficulty of the single-walled carbon nanotube is higher than that of the multi-walled carbon nanotube. The single-walled carbon nanotube prepared by the arc discharge method is purified by adopting the existing single-walled carbon nanotube purification technology, the purity of the purified single-walled carbon nanotube can reach more than 99 percent, but the conversion rate of the finished single-walled carbon nanotube is lower than 10 percent, the single-walled carbon nanotube prepared by a chemical vapor deposition method (CVD method) is purified by adopting the existing purification technology, the purity of the purified single-walled carbon nanotube can only reach 90 percent, the conversion rate of the finished product is also lower than 10 percent, and the purity and the conversion rate are both very low. The chemical vapor deposition method has the advantages of low cost, large yield, easy control of conditions and the like, and is the most suitable method for industrially producing the single-walled carbon nanotube at present. Therefore, there is an urgent need to find a purification technique suitable for CVD method to produce single-walled carbon nanotubes with high purity and high conversion rate.
Disclosure of Invention
The invention aims to provide a method for purifying a single-walled carbon nanotube with high purity and high conversion rate, and aims to solve the technical problems of low purity and low conversion rate of a finished product of the single-walled carbon nanotube prepared by a purification CVD method in the prior art.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
the invention provides a method for purifying a single-walled carbon nanotube with high purity and high conversion rate, which comprises the following steps:
step one, pretreating a single-walled carbon nanotube crude product prepared by a CVD method;
step two, carrying out ultrasonic dispersion on the single-walled carbon nanotube treated in the step one together with a surfactant and an organic solvent, then washing to be neutral, filtering, and finally carrying out freeze drying;
thirdly, carrying out high-temperature oxidation treatment on the single-walled carbon nanotube treated in the second step;
step four, placing the single-walled carbon nanotube subjected to high-temperature oxidation treatment in a mixed acid solution, and heating while stirring;
and step five, washing the single-walled carbon nanotube reacted in the step four to be neutral, filtering and drying to obtain the purified single-walled carbon nanotube.
Wherein the pretreatment comprises at least one of crushing treatment, centrifugal treatment, oscillation treatment and ultrasonic treatment.
Wherein the organic solvent comprises at least one of an alcohol solvent and a ketone solvent.
Wherein the surfactant comprises at least one of an anionic surfactant, a nonionic surfactant and an amphoteric surfactant.
Wherein, in the second step, the temperature is 35-45 ℃ during ultrasonic dispersion, and the ultrasonic time is 1.5-2.5h.
In the third step, the high-temperature oxidation treatment comprises the steps of placing the single-walled carbon nanotube in a mixed atmosphere of argon and water vapor, controlling the gas flow to be 350-450mL/min, calcining at 350-500 ℃ for 30-60min, and finally cooling.
In the fourth step, the mixed acid solution comprises a hydrochloric acid solution with the concentration of 3-6mol/L and a nitric acid solution with the concentration of 6% -16%.
Wherein, in the fourth step, the stirring speed is 350-450rpm, the heating temperature is 75-85 ℃, and the reaction time is 3.5-4.5h.
Wherein the single-walled carbon nanotube is an iron-based single-walled carbon nanotube.
The invention has the beneficial effects that:
the invention pretreats the single-walled carbon nanotube produced by the CVD method, so that the carbon nanotube can be better contacted with the solution fully, the pretreated single-walled carbon nanotube, the surfactant and the organic solvent are ultrasonically dispersed together, the residual organic substances in the carbon nanotube can be removed, and the surfactant and the organic solvent jointly act to open the gap between the single-walled carbon nanotube and the metal impurities, so that part of the metal impurities are separated from the single-walled carbon nanotube, and part of the metal impurities are removed. The high-temperature oxidation treatment can remove the residual amorphous carbon covered on the carbon tube and oxidize the metal catalyst particles on the surface of the carbon tube, so that on one hand, the formed metal oxide is not firmly combined with the single-walled carbon nanotube, the loss of the carbon tube can be reduced during stripping, and on the other hand, the oxidized metal is easier to react with acid to be removed, thereby better improving the purity of the single-walled carbon nanotube and the conversion rate of a finished product. The excellent conductivity of the single-walled carbon nanotube is kept by means of washing to neutrality, filtering, freeze-drying and the like, and the method is used as a foundation for subsequent application of the single-walled carbon nanotube. The purification method has simple steps and convenient operation, and can prepare the single-walled carbon nanotube with low loss and high purity, the purity can reach 99 percent, and the conversion rate of the finished product can reach 62 percent.
Detailed Description
In order to make the objects, technical solutions and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described, and the embodiments described below are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive step in connection with the embodiments of the present invention shall fall within the scope of protection of the present invention. Those whose specific conditions are not specified in the examples are carried out according to conventional conditions or conditions recommended by the manufacturer; the reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
In the description of the present invention, the term "and/or" describes an association relationship of associated objects, which means that there may be three relationships, for example, a and/or B, which may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
In the description of the present invention, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (a), b, or c", or "at least one (a), b, and c", may each represent: a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple respectively.
It should be understood that the weight of the related components mentioned in the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the weight of each component, and therefore, the proportional enlargement or reduction of the content of the related components according to the embodiments of the present invention is within the scope of the present disclosure. Specifically, the weight described in the embodiments of the present invention may be a unit of mass known in the chemical field such as μ g, mg, g, kg, etc.
In addition, unless the context clearly uses otherwise, an expression of a word in the singular is to be understood as including the plural of the word. The terms "comprises" or "comprising" are intended to specify the presence of stated features, quantities, steps, operations, elements, portions, or combinations thereof, but are not intended to preclude the presence or addition of one or more other features, quantities, steps, operations, elements, portions, or combinations thereof.
The embodiment of the invention provides a method for purifying a single-walled carbon nanotube with high purity and high conversion rate, which comprises the following steps:
step one, pretreating a crude product of the single-walled carbon nanotube prepared by a CVD method, wherein the weight part of the single-walled carbon nanotube is 4-6 parts, and the purity is 55-65%;
step two, carrying out ultrasonic dispersion on the single-walled carbon nanotube treated in the step one together with 8-10 parts by weight of surfactant and organic solvent, then washing to be neutral, filtering, and finally freeze-drying;
step three, carrying out high-temperature oxidation treatment on the single-walled carbon nanotube treated in the step two;
step four, placing the single-walled carbon nanotube subjected to high-temperature oxidation treatment in a mixed acid solution, and heating while stirring;
and step five, washing the single-walled carbon nanotube reacted in the step four to be neutral, filtering and drying to obtain the purified single-walled carbon nanotube.
The invention pretreats the single-walled carbon nanotube produced by the CVD method, so that the single-walled carbon nanotube can be better and fully contacted with the solution, the pretreated single-walled carbon nanotube, the surfactant and the organic solvent are ultrasonically dispersed together, the surfactant and the organic solvent jointly act between the single-walled carbon nanotube and the metal impurities, the gap between the single-walled carbon nanotube and the metal impurities is opened, the gap between the metal and the single-walled carbon nanotube is enlarged, part of the metal impurities are loosened and fall off from the single-walled carbon nanotube, the effect of removing part of the metal catalyst is further achieved, and the organic solvent can remove the residual organic substances in the carbon nanotube. The surfactant and the organic solvent act on the carbon tube and the metal impurities together to increase the gap between the carbon tube and the metal impurities, so that the binding force between part of the metal impurities and the carbon tube is reduced, the loss of the carbon tube can be reduced when the metal impurities are separated from the carbon tube, and the conversion rate of the purified single-walled carbon nanotube finished product is higher.
The ultrasonically dispersed single-walled carbon nanotubes are subjected to freeze drying, so that on one hand, the gap between the single-walled carbon nanotubes and the single-walled carbon nanotubes can be ensured, the overall bulkiness of a single-walled carbon nanotube mixture is ensured, the single-walled carbon nanotubes are prevented from being agglomerated, impurities can be more fully reacted during later purification treatment, the impurities in the single-walled carbon nanotubes can be more favorably removed, and the purity of the purified single-walled carbon nanotubes is higher; on the other hand, the method can ensure the clearance between the single-walled carbon nanotube and the metal catalyst impurities, is beneficial to reducing the binding force between the single-walled carbon nanotube and the metal impurities, enables the impurities to be separated from the single-walled carbon nanotube more easily, reduces the loss of the single-walled carbon nanotube and enables the conversion rate of the purified single-walled carbon nanotube finished product to be higher.
The high-temperature oxidation treatment can remove residual amorphous carbon covered on the single-walled carbon nanotube, and simultaneously oxidize metal catalyst particles on the surface of the single-walled carbon nanotube, so that metal oxide can react with acid more easily, and metal impurities can be removed more easily, and the oxidized metal oxide and the single-walled carbon nanotube are combined more firmly, so that the metal oxide is stripped from the single-walled carbon nanotube and carbon tubes are not easy to lose, and the high-temperature oxidation treatment is more favorable for improving the purity of the single-walled carbon nanotube and the conversion rate of a purified finished product.
The acid solution can effectively remove the metal catalyst and the oxide thereof in the carbon tube, and the mixed acid is more beneficial to improving the conversion rate of the finished product after the purification of the single-walled carbon nanotube.
The purification method of the invention firstly pretreats the single-walled carbon nanotube, so that the single-walled carbon nanotube can better and fully contact with the surfactant and the organic solvent, after the single-walled carbon nanotube is ultrasonically dispersed with the surfactant and the organic solvent, the surfactant and the organic solvent can better open the gap between the single-walled carbon nanotube and the metal impurities, and the gap between the carbon tube and the gap between the carbon tube and the metal impurities are kept by a freeze drying means, so that the integral filling power is kept, amorphous carbon on the surface of the carbon tube can be more fully removed and the metal impurities can be more fully oxidized during the later high-temperature oxidation treatment, and the method is more favorable for the acid solution to react with the oxidized metal oxides and remove the metal impurities. In conclusion, the purification method has simple steps and convenient operation, can prepare the single-walled carbon nanotube with low loss and high purity, the purity can reach more than 99 percent, and the conversion rate of the finished product can reach more than 62 percent.
Specifically, the single-walled carbon nanotube is an iron-based single-walled carbon nanotube and is prepared by adopting an iron catalyst.
Wherein the pretreatment comprises at least one of crushing treatment, centrifugal treatment, oscillation treatment and ultrasonic treatment.
Preferably, the pretreatment adopts crushing treatment, and the pretreatment step comprises crushing the crude carbon nanotube in a crusher at 350-450rpm for 25-35min. Specifically, the rotation speed of the pulverizer can be, but is not limited to, 350rpm, 360rpm, 370rpm, 380rpm, 390rpm, 400rpm, 410rpm, 420rpm, 430rpm, 440rpm, 450rpm, and the pulverization time can be, but is not limited to, 25min, 26min, 27min, 28min, 29min, 30min, 31min, 32min, 33min, 34min, 35min. Carry out the pretreatment to single-walled carbon nanotube crude through adopting crushing mode, can disperse the single-walled carbon nanotube who reunites on the one hand, make single-walled carbon nanotube later stage can fully contact the reaction with the solvent, on the other hand can cut into less metal particle with great fast metal impurity, more is favorable to follow-up reaction rate who improves metal impurity, improves single-walled carbon nanotube's purification effect. When the rotation speed is too low or the pulverizing time is too short, the single-walled carbon nanotubes are not completely dispersed, which may affect the purification effect. When the rotation speed is too high or the pulverizing treatment time is too long, the subsequent conductivity of the carbon nanotubes is affected.
Wherein the organic solvent comprises at least one of an alcohol solvent and a ketone solvent.
Wherein the surfactant comprises at least one of anionic surfactant, nonionic surfactant and amphoteric surfactant.
Wherein, in the second step, the temperature is 35-45 ℃ during ultrasonic dispersion, and the ultrasonic time is 1.5-2.5h. Specifically, the temperature during the ultrasonic dispersion can be, but is not limited to, 35 ℃, 36 ℃, 37 ℃, 38 ℃, 39 ℃, 40 ℃, 41 ℃, 42 ℃, 43 ℃, 44 ℃ and 45 ℃, and the ultrasonic temperature can be, but is not limited to, 1.5h, 1.8h, 1.9h, 2.0h, 2.3h and 2.5h. The ultrasonic dispersion power is 25-35Hz.
Wherein, in the second step, the freeze drying temperature is-40 to-60 ℃.
In the third step, the high-temperature oxidation treatment comprises the steps of placing the single-wall carbon nanotube mixture in a mixed atmosphere of argon and water vapor, controlling the gas flow to be 350-450mL/min, calcining at 750-850 ℃ for 25-35min, and finally cooling. Specifically, the gas flow rate may be, but not limited to, 350mL/min, 360mL/min, 370mL/min, 380mL/min, 390mL/min, 400mL/min, 410mL/min, 420mL/min, 430mL/min, 440mL/min, 450mL/min, and the calcination temperature may be, but not limited to, 750 ℃, 760 ℃, 770 ℃, 780 ℃, 790 ℃, 800 ℃, 810 ℃, 820 ℃, 830 ℃, 840 ℃, 850 ℃.
Through introducing argon and vapor mist, can accelerate the oxidation of metal catalyst to become the metal oxide who reacts with acid more easily, and metal oxide compares the combination of metal simple substance and carbon nanotube insecure with single-walled carbon nanotube's combination, is difficult to damage carbon nanotube when metal oxide peels off from carbon nanotube more, therefore argon and vapor mist is more favorable to improving purification effect and finished product conversion rate.
In the fourth step, the mixed acid solution comprises a hydrochloric acid solution with the concentration of 3-6mol/L and a nitric acid solution with the concentration of 6% -16%. Tests show that the hydrochloric acid solution and the nitric acid solution with the concentrations are mixed, so that the purity of the single-walled carbon nanotube and the conversion rate of a purified finished product are improved, and when the concentration of the nitric acid is too high, the high-concentration acid and iron generate passivation reaction and damage the carbon nanotube, so that the purity and the conversion rate of the single-walled carbon nanotube are influenced.
Preferably, the volume ratio of the hydrochloric acid solution to the nitric acid solution is 1.
Wherein, in the fourth step, the stirring speed is 350-450rpm, the heating temperature is 75-85 ℃, and the reaction time is 3.5-4.5h.
In order to clearly understand the details of the above-described implementation and operation of the present invention for those skilled in the art and to significantly embody the advanced performance of the embodiments of the present invention, the above-described technical solution is illustrated by a plurality of embodiments below.
Example 1
A method for purifying single-wall carbon nanotubes with high purity and high conversion rate comprises the following steps:
step one, pretreating a single-walled carbon nanotube crude product prepared by a CVD method in the following way:
weighing 5g of a crude single-walled carbon nanotube product with the purity of 60%, wherein the single-walled carbon nanotube product is prepared by adopting an iron catalyst, placing the crude single-walled carbon nanotube product in a pulverizer, and controlling the rotating speed of the pulverizer to be 400rpm and the pulverizing time to be 30min to obtain pulverized single-walled carbon nanotube powder.
And step two, carrying out ultrasonic dispersion on the single-walled carbon nanotube treated in the step one, 9g of sodium dodecyl benzene sulfonate surfactant and 300mL of 50% ethanol aqueous solution, wherein the ultrasonic power is 30Hz, the temperature during dispersion is 40 ℃, the ultrasonic time is 2 hours, washing the single-walled carbon nanotube with deionized water after ultrasonic dispersion until the washing liquid is neutral, filtering, and finally carrying out freeze drying at the temperature of 50 ℃ below zero for 20 minutes.
And step three, placing the single-walled carbon nanotube treated in the step two in a mixed atmosphere of argon and water vapor for high-temperature oxidation treatment, controlling the volume ratio of the argon to the water vapor to be 1.
And step four, placing the single-walled carbon nanotube subjected to high-temperature oxidation treatment in a mixed acid solution, and heating while stirring, wherein the stirring speed is 400rpm, the heating temperature is 80 ℃, and the reaction is carried out for 4 hours, wherein the mixed acid solution comprises 300mL of a hydrochloric acid solution with the concentration of 6mol/L and 300mL of a nitric acid solution with the concentration of 11%.
And step five, filtering and washing the single-walled carbon nanotube reacted in the step four, firstly washing the single-walled carbon nanotube by deionized water until the pH value of a washing liquid is neutral, then washing and filtering the single-walled carbon nanotube twice by using an ethanol water solution with the concentration of 50%, then putting the washed single-walled carbon nanotube into a forced air drying oven for drying at the drying temperature of 120 ℃ for 4 hours, and obtaining the purified single-walled carbon nanotube.
Calcining 0.3g of the purified single-walled carbon nanotube at the high temperature of 800 ℃ for 30min under the air atmosphere and the air flow of 400mL/min, cooling and weighing the residual ash, and finally measuring that the purity of the purified single-walled carbon nanotube is 99.1% and the conversion rate of the finished product is 62.8%.
Example 2
A method for purifying single-walled carbon nanotubes with high purity and high conversion rate comprises the following steps:
step one, pretreating a single-walled carbon nanotube crude product prepared by a CVD method in the following way:
weighing 4g of a crude single-walled carbon nanotube product with the purity of 55%, wherein the single-walled carbon nanotube product is prepared by adopting an iron catalyst, placing the crude single-walled carbon nanotube product in a pulverizer, and controlling the rotating speed of the pulverizer to be 350rpm and the pulverizing time to be 35min to obtain pulverized single-walled carbon nanotube powder.
And step two, carrying out ultrasonic dispersion on the single-walled carbon nanotube treated in the step one, 8g of sodium dodecyl benzene sulfonate surfactant and 300mL of 50% ethanol water solution, wherein the ultrasonic power is 25Hz, the temperature during dispersion is 45 ℃, the ultrasonic time is 1.5h, washing the single-walled carbon nanotube with deionized water after ultrasonic dispersion until the washing liquid is neutral, filtering, and finally carrying out freeze drying at the temperature of minus 40 ℃ for 20min.
And step three, placing the single-walled carbon nanotube treated in the step two in a mixed atmosphere of argon and water vapor for high-temperature oxidation treatment, controlling the volume ratio of the argon to the water vapor to be 1.
And step four, placing the single-walled carbon nanotube subjected to high-temperature oxidation treatment in a mixed acid solution, and heating while stirring, wherein the stirring speed is 350rpm, the heating temperature is 75 ℃, and the reaction is performed for 3.5 hours, wherein the mixed acid solution comprises 300mL of hydrochloric acid solution with the concentration of 3mol/L and 300mL of nitric acid solution with the concentration of 6%.
And step five, filtering and washing the single-walled carbon nanotube reacted in the step four, firstly washing the single-walled carbon nanotube by deionized water until the pH value of a washing liquid is neutral, then washing and filtering the single-walled carbon nanotube twice by using an ethanol water solution with the concentration of 50%, then putting the washed single-walled carbon nanotube into a forced air drying oven for drying at the drying temperature of 120 ℃ for 4 hours, and obtaining the purified single-walled carbon nanotube.
Calcining 0.3g of the purified single-walled carbon nanotube at the high temperature of 800 ℃ for 30min under the air atmosphere with the air flow of 400mL/min, and weighing the residual ash after the calcination is cooled, thereby finally measuring that the purity of the purified single-walled carbon nanotube is 99.0% and the conversion rate of the finished product is 62.1%.
Example 3
A method for purifying single-walled carbon nanotubes with high purity and high conversion rate comprises the following steps:
step one, pretreating a single-walled carbon nanotube crude product prepared by a CVD method in the following way:
weighing 6g of crude single-walled carbon nanotube products with the purity of 65%, wherein the single-walled carbon nanotubes are prepared by adopting an iron catalyst, placing the crude single-walled carbon nanotube products into a pulverizer, and controlling the rotating speed of the pulverizer to be 450rpm and the pulverizing time to be 35min to obtain pulverized single-walled carbon nanotube powder.
And step two, carrying out ultrasonic dispersion on the single-walled carbon nanotube treated in the step one, 10g of sodium dodecyl benzene sulfonate surfactant and 300mL of 50% ethanol water solution, wherein the ultrasonic power is 35Hz, the temperature during dispersion is 35 ℃, the ultrasonic time is 2.5h, washing the single-walled carbon nanotube with deionized water after ultrasonic dispersion until the washing liquid is neutral, filtering, and finally carrying out freeze drying at the temperature of minus 60 ℃ for 20min.
And step three, placing the single-walled carbon nanotube treated in the step two in a mixed atmosphere of argon and water vapor for high-temperature oxidation treatment, controlling the volume ratio of the argon to the water vapor to be 1.
And step four, placing the single-walled carbon nanotube subjected to high-temperature oxidation treatment in a mixed acid solution, and heating while stirring at the stirring speed of 450rpm and the heating temperature of 85 ℃, wherein the mixed acid solution reacts for 4.5 hours and comprises 300mL of a hydrochloric acid solution with the concentration of 6mol/L and 300mL of a nitric acid solution with the concentration of 16%.
And step five, filtering and washing the single-walled carbon nanotube reacted in the step four, washing the single-walled carbon nanotube by using deionized water until the pH value of a washing liquid is neutral, washing and filtering the single-walled carbon nanotube twice by using an ethanol water solution with the concentration of 50%, then placing the washed single-walled carbon nanotube into a forced air drying oven for drying at the drying temperature of 120 ℃ for 4 hours, and obtaining the purified single-walled carbon nanotube.
Calcining 0.3g of the purified single-walled carbon nanotube at the high temperature of 800 ℃ for 30min under the air atmosphere with the air flow of 400mL/min, and weighing the residual ash after the calcination is cooled, thereby finally measuring that the purity of the purified single-walled carbon nanotube is 99.0% and the conversion rate of the finished product is 62.3%.
Comparative example 1
A single-walled carbon nanotube purification method comprises the following steps:
2g of a crude sample of the single-walled carbon nanotube with the purity of about 60 percent is mixed with 200mL of a 6mol/L hydrochloric acid solution, heated and stirred at the stirring speed of 400rpm, the heating temperature of 80 ℃ and the stirring time of 4h, then filtered and washed, washed by deionized water until the pH value of a washing solution is neutral, put into an air-blast drying oven for drying at the drying temperature of 120 ℃ and the drying time of 4h, and the purified single-walled carbon nanotube is obtained after drying.
Calcining 0.3g of the purified single-walled carbon nanotube at the high temperature of 800 ℃ for 30min under the air atmosphere and the air flow of 400mL/min, cooling and weighing the residual ash, and finally measuring that the purity of the purified single-walled carbon nanotube is 83.5% and the conversion rate of the finished product is 18.1%.
Comparative example 2
A single-walled carbon nanotube purification method comprises the following steps:
2g of a crude sample of the single-walled carbon nanotube with the purity of about 50 percent is mixed with 250mL of a 6mol/L hydrochloric acid solution, heated and stirred at the stirring speed of 400rpm, the heating temperature of 80 ℃ and the stirring time of 4h, then filtered and washed, washed by deionized water until the pH value of a washing solution is neutral, put into an air-blowing drying oven for drying at the drying temperature of 120 ℃ for 4h, and then the purified single-walled carbon nanotube is obtained after drying.
Calcining 0.3g of the purified single-walled carbon nanotube at the high temperature of 800 ℃ for 30min under the air atmosphere and the air flow of 400mL/min, cooling and weighing the residual ash, and finally measuring that the purity of the purified single-walled carbon nanotube is 83.5% and the conversion rate of the finished product is 18.1%.
The purification method of the single-walled carbon nanotube solves the problems of low purity and low conversion rate of a finished product of the single-walled carbon nanotube produced by the traditional CVD method, the purity of the single-walled carbon nanotube reaches 90 percent at most and the conversion rate of the finished product is only 10 percent before the single-walled carbon nanotube is purified, and after the purification technology of the single-walled carbon nanotube is used, the purity of the purified single-walled carbon nanotube reaches 99.1 percent at most and the conversion rate of the finished product also reaches over 60 percent.
The purification method has simple steps and convenient operation, can prepare the single-walled carbon nanotube with high purity and high conversion rate, greatly reduces the purification cost, simultaneously furthest retains the excellent performance of the single-walled carbon nanotube, lays a solid foundation for the subsequent application of the single-walled carbon nanotube, and can be suitable for large-scale industrial production and application thereof.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the present invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A method for purifying single-wall carbon nanotubes with high purity and high conversion rate is characterized by comprising the following steps:
step one, pretreating a single-walled carbon nanotube crude product prepared by a CVD method;
step two, carrying out ultrasonic dispersion on the single-walled carbon nanotube treated in the step one, a surfactant and an organic solvent, washing to be neutral, filtering, and finally freeze-drying;
thirdly, carrying out high-temperature oxidation treatment on the single-walled carbon nanotube treated in the second step;
step four, placing the single-walled carbon nanotube subjected to high-temperature oxidation treatment in a mixed acid solution, and heating while stirring;
and step five, washing the single-walled carbon nanotube reacted in the step four to be neutral, filtering and drying to obtain the purified single-walled carbon nanotube.
2. The method of claim 1, wherein the pre-treatment comprises at least one of a pulverization treatment, a centrifugation treatment, a shaking treatment, and an ultrasonic treatment.
3. The method as claimed in claim 1, wherein the organic solvent comprises at least one of an alcohol solvent and a ketone solvent.
4. The method of claim 1, wherein the surfactant comprises at least one of an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant.
5. The method for purifying the single-walled carbon nanotube with high purity and high conversion rate as claimed in claim 1, wherein the temperature for ultrasonic dispersion is 35-45 ℃ and the ultrasonic time is 1.5-2.5h in the second step.
6. The method as claimed in claim 1, wherein the high temperature oxidation treatment comprises placing the single-walled carbon nanotube in a mixed atmosphere of argon and water vapor, controlling the gas flow rate to be 350-450mL/min, calcining at 750-850 ℃ for 25-35min, and cooling.
7. The method for purifying the single-walled carbon nanotube with high purity and high conversion rate as claimed in claim 1, wherein in the fourth step, the mixed acid solution comprises a hydrochloric acid solution with a concentration of 3-6mol/L and a nitric acid solution with a concentration of 6% -16%.
8. The method for purifying the single-walled carbon nanotube with high purity and high conversion rate as claimed in claim 1, wherein in the fourth step, the stirring speed is 350-450rpm, the heating temperature is 75-85 ℃, and the reaction time is 3.5-4.5h.
9. The method as claimed in claim 1, wherein the single-walled carbon nanotubes are iron-based single-walled carbon nanotubes.
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| CN101780951A (en) * | 2010-03-09 | 2010-07-21 | 北京大学 | Purification method for obtaining high-purity carbon nano tube |
| CN104724691A (en) * | 2013-12-23 | 2015-06-24 | 北京阿格蕾雅科技发展有限公司 | Method for raising dispersibility of single-walled carbon nanotubes |
| CN111232954A (en) * | 2020-02-24 | 2020-06-05 | 中国科学院苏州纳米技术与纳米仿生研究所 | High-purity high-concentration chiral single-walled carbon nanotube dispersion liquid, carbon nanotube film and preparation method |
| CN114014300A (en) * | 2021-11-24 | 2022-02-08 | 深圳市飞墨科技有限公司 | Carbon nanotube and method for purifying the same |
| CN114314566A (en) * | 2021-12-29 | 2022-04-12 | 无锡碳谷科技有限公司 | Separation and purification method of carbon nano tube |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101780951A (en) * | 2010-03-09 | 2010-07-21 | 北京大学 | Purification method for obtaining high-purity carbon nano tube |
| CN104724691A (en) * | 2013-12-23 | 2015-06-24 | 北京阿格蕾雅科技发展有限公司 | Method for raising dispersibility of single-walled carbon nanotubes |
| CN111232954A (en) * | 2020-02-24 | 2020-06-05 | 中国科学院苏州纳米技术与纳米仿生研究所 | High-purity high-concentration chiral single-walled carbon nanotube dispersion liquid, carbon nanotube film and preparation method |
| CN114014300A (en) * | 2021-11-24 | 2022-02-08 | 深圳市飞墨科技有限公司 | Carbon nanotube and method for purifying the same |
| CN114314566A (en) * | 2021-12-29 | 2022-04-12 | 无锡碳谷科技有限公司 | Separation and purification method of carbon nano tube |
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