Preparation method of carbon nanotube cluster microspheres based on polymer waste

Abstract

The invention discloses a preparation method of carbon nano tube cluster microspheres based on macromolecular waste, and belongs to the technical field of solid waste treatment and functionalized nano materials. According to the method, transition metal acetate or oxalate is used as a catalyst, the characteristics of strong dissolving capacity, high diffusivity, low surface tension, low viscosity and the like of a supercritical carbon dioxide system between a gas state and a liquid state are utilized, and particularly, special cracking and reaction promoting effects on organic components under high-temperature and high-pressure conditions are utilized; the plastic waste can be controlled to be prepared into the carbon nanotube cluster microspheres, so that the recycling of the waste high polymer material and the preparation of the functionalized nano material are realized. According to the method, supercritical carbon dioxide is used as a reaction solvent and is discharged or recycled in a gas form after the reaction is finished, and pollutants such as wastewater are not generated.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste treatment and functionalized nanomaterials, and particularly relates to a preparation method of carbon nanotube cluster microspheres based on polymer waste. Background Art

[0002] Polymer plastic products such as plastic bags and plastic bottles have become essential chemical products in daily life due to their low price, excellent chemical stability, light weight, and portability. However, with the continuous increase in people's demands, the production of various artificial non-biodegradable plastic products has also increased sharply. "White pollution" has become the most serious pollution today, and its harms mainly include "visual pollution" that affects the overall aesthetic and urban appearance, and "potential pollution" such as long-term and deeper ecological, environmental, and safety problems. Therefore, the recycling and reuse of polymer plastic waste have become an urgent issue.

[0003] The main types of polymer waste are general plastics such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and others such as polyethylene terephthalate (PET, with the largest recovery volume, accounting for about one-third of the proportion), polyurethane (PU), and ABS waste plastics. Common treatment methods for polymer waste raw materials mainly include the following: reducing the generation of plastic waste at the source; recycling methods such as mechanical recycling, chemical recycling, and combustion heat treatment; landfilling or using biodegradable plastic products. Landfilling and incineration are still the main methods for treating waste plastics today, with a treatment volume accounting for more than 70% of the total waste plastic volume. However, this method continuously reduces the arable land area, leading to land, water pollution, and air pollution, especially the health impacts and long-term potential threats after "microplastics" enter the ecosystem. In addition, the distribution, separation, and cleaning of plastic waste are relatively cumbersome, lacking effective equipment; factors such as the lack of awareness concept and the absence of a recycling and reuse market restrict the recycling and reuse of polymer waste as raw materials.

[0004] However, polymer waste contains rich organic components such as carbon, hydrogen, and oxygen, and is one of the ideal carbon sources. If it is not recycled and reused, it will inevitably lead to a waste of resources. Therefore, developing new markets, especially converting these waste plastics into micro-nano materials with higher added value, will be an effective way to recycle waste. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of carbon nanotube cluster microspheres based on polymer waste to solve the problems of waste of waste polymer plastics and environmental pollution.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention provides a method for preparing carbon nanotube cluster microspheres based on polymer waste, comprising the following steps:

[0008] Using the polymer waste as a raw material and a catalyst in a supercritical carbon dioxide system (sc-CO2), under the conditions of a temperature of 500 - 800 °C and a pressure of 0.7 - 300 MPa, after heat preservation and pressure maintenance for 3 - 12 h, naturally cooling to room temperature (25 - 30 °C), the obtained intermediate product is treated with acid to obtain carbon nanotube cluster microspheres.

[0009] As a further aspect of the present invention, the supercritical carbon dioxide system is a state where carbon dioxide is above its critical temperature (31.1 °C) and critical pressure (7.38 MPa). At this time, CO2 is neither a gas nor a liquid, but has the characteristics of both, forming a unique supercritical fluid; specifically, any one of dry ice or high-pressure carbon dioxide gas is used; wherein the dry ice can be obtained by freezing carbon dioxide gas with liquid nitrogen, or directly purchasing finished dry ice, which is mashed and added to the reaction kettle; the high-pressure carbon dioxide gas can be obtained by compressing carbon dioxide gas by conventional means.

[0010] As a further aspect of the present invention, the carbon nanotube cluster microspheres are formed by winding carbon nanotubes, the size of the microspheres is 1 - 5 μm, the diameter of the carbon nanotubes is 50 - 200 nm, and the length is 0.5 - 5 μm.

[0011] As a further aspect of the present invention, the polymer waste includes polyethylene, polypropylene, polyethylene terephthalate, polyurethane, polyvinyl chloride, polystyrene, and polyurethane.

[0012] As a further aspect of the present invention, the catalyst is one or a combination of transition metal acetates or transition metal oxalates;

[0013] Furthermore, the transition metal acetates include nickel acetate, iron acetate, cobalt acetate, or manganese acetate; the transition metal oxalates include nickel oxalate, iron oxalate, or cobalt oxalate.

[0014] As a further aspect of the present invention, the mass ratio of the catalyst to the polymer waste is 0.3 - 1.5:1.

[0015] Furthermore, the mass ratio of the catalyst to the polymer waste is 0.4 - 0.6:1.

[0016] As a further aspect of the present invention, the mass ratio of the supercritical carbon dioxide to the polymer waste is 5 - 20:1.

[0017] As a further solution of the present invention, during the acid treatment process, the acid soaking method is adopted, and the acid solution includes inorganic acid or organic acid with a concentration of 1-10 mol / L; the soaking time is 2-10 h.

[0018] Furthermore, the inorganic acid includes nitric acid, sulfuric acid, perchloric acid, hydroiodic acid, hydrobromic acid; the organic acid includes methanesulfonic acid or benzenesulfonic acid.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. The present invention uses waste polymer raw materials as carbon sources, which not only provides a new solution for the recycling and reuse of common waste plastics such as PE, PP, and PET, but also converts them into nanomaterials with high added value. The obtained carbon nanotube cluster microspheres have a unique pore structure and a large specific surface area, and have wide applications in the fields of lithium-ion batteries, energy storage, and pollutant treatment.

[0021] 2. The supercritical carbon dioxide system is between gaseous and liquid states, with characteristics such as strong dissolution ability, high diffusivity, low surface tension, and low viscosity. Under high-temperature and high-pressure conditions, it has a special cracking and reaction-promoting effect on organic components, can effectively decompose polymer waste such as plastics, form a large number of organic groups, and form carbon nanotube cluster microspheres through controlled carbonization. The recycling and reuse of waste polymer materials and the preparation of functionalized nanomaterials are realized. Compared with other liquid-phase and high-temperature gas-phase reactions, the required reaction temperature can be reduced by about two or three hundred degrees Celsius, and the reaction time can also be shortened to within a few hours, which is beneficial to reducing energy consumption.

[0022] 3. The preparation method of the present invention is simple, scientific, efficient, green, and pollution-free. Only need to put the waste polymer raw materials and transition metal salt catalysts into the reaction vessel and react under the supercritical carbon dioxide system. After the reaction, carbon dioxide is discharged or recycled in the form of gas, without any liquid or by-product residues. It is a green and environmentally friendly preparation method, which will provide a technical solution for the recycling and value improvement of waste polymer raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the drawings.

[0024] Figure 1 It is a schematic diagram of the present invention for obtaining carbon nanotube cluster microspheres based on polymer waste;

[0025] Figure 2 It is an XRD diagram of the intermediate product and the final product carbon nanotube cluster microspheres in Example 1 of the present invention;

[0026] Figure 3It is the SEM characterization diagram of the product of Embodiment 1 of the present invention. Among them, (a) is the SEM diagram of the intermediate product, and (b) is the SEM diagram of the final product, carbon nanotube cluster microspheres;

[0027] Figure 4 It is the TEM characterization diagram of the product of Embodiment 1 of the present invention. Among them, (a) is the TEM diagram of the intermediate product, and (b) is the TEM diagram of the final product, carbon nanotube cluster microspheres;

[0028] Figure 5 It is the SEM diagram of the final product in Embodiment 2 of the present invention;

[0029] Figure 6 It is the SEM diagram of the final product in Embodiment 3 of the present invention;

[0030] Figure 7 It is the SEM diagram of the final product in Embodiment 4 of the present invention;

[0031] Figure 8 It is the SEM diagram of the final product in Comparative Example 1 of the present invention;

[0032] Figure 9 It is the SEM diagram of the final product in Comparative Example 2 of the present invention;

[0033] Figure 10 It is the SEM diagram of the final product in Comparative Example 3 of the present invention. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0035] Obviously, the following description is only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some designs, manufacturing or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be understood that the content disclosed in the present application is insufficient.

[0036] However, there may be cases where unnecessary details are omitted. For example, there are cases where details of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to prevent the following descriptions from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0037] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0038] Please refer to Figure 1 , a method for preparing carbon nanotube cluster microspheres based on polymer waste, comprising the following steps:

[0039] Material preparation: Weigh polymer waste, catalyst, and supercritical carbon dioxide according to a mass ratio of 1:0.3 - 1.5:5 - 20;

[0040] Clean and dry the polymer waste, then cut it into pieces with a particle size of about 0.5 cm and add it as a raw material into a 25 mL stainless steel reaction kettle. Add an appropriate amount of catalyst and mix evenly;

[0041] Then add the supercritical carbon dioxide system as a reaction solvent into the reaction kettle, quickly seal the reaction kettle to ensure that carbon dioxide gas does not leak out during the whole reaction process. Place the reaction kettle in a muffle furnace and heat it at a heating rate of 10 °C / min to 500 - 800 °C. The whole reaction is carried out under the self-pressure of the reaction kettle, and the pressure in the kettle is 0.7 - 300 MPa, and the supercritical condition of the carbon dioxide system is completely reached. After heat preservation and pressure maintenance for 3 - 12 h, naturally cool it to room temperature, open the reaction kettle, dissipate carbon dioxide, and take out the generated intermediate product, and perform acid treatment on it to obtain carbon nanotube cluster microspheres.

[0042] The supercritical carbon dioxide is any one of dry ice and high-pressure carbon dioxide gas; among them, dry ice can be obtained by freezing carbon dioxide gas with liquid nitrogen or directly purchasing finished dry ice, smashing it and adding it into the reaction kettle; high-pressure carbon dioxide gas can be obtained by compressing carbon dioxide gas by conventional means.

[0043] In a specific embodiment, the polymer waste as a raw material includes but is not limited to common waste plastics such as polyethylene, polypropylene, polyethylene terephthalate, polyurethane, polyvinyl chloride, polystyrene, and polyurethane.

[0044] In a specific embodiment, the catalyst is one or a combination of transition metal acetates or transition metal oxalates;

[0045] Among them, the transition metal acetates include but are not limited to nickel acetate, iron acetate, cobalt acetate or manganese acetate; the transition metal oxalates include but are not limited to nickel oxalate, iron oxalate or cobalt oxalate;

[0046] In a specific embodiment, the acid treatment is carried out by soaking with an acid solution having a concentration of 1-10 mol / L, and the soaking time is 2-10 h;

[0047] The acid solution includes but is not limited to hydrochloric acid, nitric acid, sulfuric acid, perchloric acid, hydroiodic acid, hydrobromic acid, methanesulfonic acid or benzenesulfonic acid.

[0048] Example 1

[0049] Please refer to Figure 1 , this embodiment provides a preparation method of carbon nanotube cluster microspheres based on polymer waste, including the following steps:

[0050] Clean and dry the waste PE as raw materials, then cut it into fragments with a particle size of about 0.5 cm, weigh 1.0 g and add it to a 25 mL stainless steel reactor, add 0.5 g of nickel acetate as a catalyst, and mix evenly;

[0051] Then add 12.00 ± 0.01 g of dry ice as a reaction solvent system to the reactor, quickly seal the reactor to ensure that carbon dioxide gas does not leak out during the whole reaction process, place the reactor in a muffle furnace and heat it to 600 °C at a heating rate of 10 °C / min. The whole reaction is carried out under the self-pressure of the reactor, the pressure in the reactor is 150 ± 3 MPa, and the supercritical condition of the carbon dioxide system is completely reached. After holding the temperature and pressure for 200 min, it is naturally cooled to room temperature. After opening the reactor and exhausting carbon dioxide, use a magnet to absorb the magnetic intermediate product, and then soak it in a hydrochloric acid solution with a concentration of 6 mol / L for 6 h, and centrifuge to obtain the final product carbon nanotube cluster microspheres.

[0052] The X-ray diffraction (XRD) is used to characterize the phase of the intermediate product and the obtained final product carbon nanotube cluster microspheres in this embodiment. The characterization results are as Figure 2 shown. It can be seen from Figure 2 that for the intermediate product sample, there are obvious diffraction peak positions of nickel (111), (200), (220) planes and carbon (002), (101), (004) planes, indicating that it is mainly composed of nickel and carbon materials; for the final product sample, it only contains the diffraction peak positions of carbon (002), (101) and (004) planes, and the diffraction peak of nickel disappears, indicating that after acid treatment, nickel in the material is removed and only carbon materials are left.

[0053] The morphology of the intermediate product and the obtained final product, carbon nanotube cluster microspheres, was characterized by scanning electron microscopy (SEM). The morphology is as shown in Figure 3 . Among them, Figure (a) is the SEM image of the intermediate product sample, and Figure (b) is the SEM image of the final product sample. By comparing Figure (a) and Figure (b) in Figure 3 , it can be seen that the cluster microspheres are mainly formed by the winding of carbon nanotubes, and the size of the microspheres is 1 - 5 μm. In the SEM image of the intermediate product sample, a large number of tiny bright spots appear, which are the nickel nanoparticles at the top of the carbon nanotubes, making the carbon nanotubes have a certain magnetism. Therefore, the intermediate product is a nickel-containing carbon nanotube cluster microsphere. After acid treatment, the bright spots disappear, leaving only the carbon nanotube material with a cluster microsphere structure.

[0054] The transmission electron microscope (TEM) was used to further finely characterize the morphology of the intermediate product and the obtained final product, carbon nanotube cluster microspheres. The morphology is as shown in Figure 4 . Among them, Figure (a) is the TEM image of the intermediate product sample, and Figure (b) is the TEM image of the final product sample. It can be seen from Figure 4 that the cluster microspheres are mainly formed by the winding of carbon nanotubes. The diameter of the carbon nanotubes that make up the microspheres is 50 - 200 nm, and the length is 0.5 - 5 μm. The unique structure gives the microsphere surface a good pore structure. After acid treatment, the nickel nanoparticles at the top of the carbon nanotubes disappear significantly.

[0055] Example 2

[0056] This example provides a method for preparing carbon nanotube cluster microspheres based on waste polymer raw materials. The difference from Example 1 is that 0.3 g of nickel acetate is added as a catalyst. After the reaction kettle is sealed, it is placed in a muffle furnace and heated at a heating rate of 10 °C / min to 500 °C, and the holding reaction time is 4 h; the remaining steps and parameters remain the same.

[0057] The SEM image of the final product is as shown in Figure 5 . It can be seen from Figure 5 that in addition to carbon nanotube cluster microspheres in the product, there are also a small amount of carbon microspheres, indicating that the amount of nickel acetate used as a catalyst is insufficient.

[0058] Example 3

[0059] This comparative example provides a method for preparing carbon nanotube cluster microspheres based on waste polymer raw materials. The difference from Example 1 is that 1.0 g of nickel acetate is added as a catalyst. After the reaction kettle is sealed, it is placed in a muffle furnace and heated at a heating rate of 10 °C / min to 600 °C, and the holding reaction time is 3 h; the remaining steps and parameters remain the same.

[0060] The SEM image of the final product is as shown in Figure 6 as shown. It can be seen fromFigure 6 It can be seen that when a relatively large amount of nickel acetate as a catalyst is added, flaky and irregular massive products are easily formed, which is not conducive to the formation of carbon nanotube cluster microspheres.

[0061] Example 4

[0062] This comparative example provides a method for preparing carbon nanotube cluster microspheres based on waste polymer raw materials. The difference from Example 1 is that 1.5 g of nickel acetate is added as a catalyst, and the remaining steps and parameters remain the same.

[0063] The SEM image of the final product is as Figure 7 shown, and it can be seen from Figure 7 that when a larger amount of nickel acetate as a catalyst is added, a large number of flaky structure products are formed, and the amount of carbon nanotube cluster microspheres formed is less.

[0064] Example 5

[0065] This example provides a method for preparing carbon nanotube cluster microspheres based on polymer waste. The difference from Example 1 is that only the dosage of nickel acetate as a catalyst is replaced with 0.4 g, and the remaining steps and parameters remain the same.

[0066] Example 6

[0067] This example provides a method for preparing carbon nanotube cluster microspheres based on polymer waste. The difference from Example 1 is that only the dosage of nickel acetate as a catalyst is replaced with 0.6 g, and the remaining steps and parameters remain the same.

[0068] Example 7

[0069] This example provides a method for preparing carbon nanotube cluster microspheres based on polymer waste. The difference from Example 1 is that only nickel acetate as a catalyst is replaced with nickel oxalate, and the remaining steps and parameters remain the same.

[0070] Example 8

[0071] This example provides a method for preparing carbon nanotube cluster microspheres based on polymer waste. The difference from Example 1 is that only nickel acetate as a catalyst is replaced with a composite nickel salt obtained by mixing nickel acetate and nickel oxalate in a mass ratio of 1:1, and the remaining steps and parameters remain the same.

[0072] Example 9

[0073] This example provides a method for preparing carbon nanotube cluster microspheres based on polymer waste. The difference from Example 1 is that only nickel acetate as a catalyst is replaced with iron acetate, and the remaining steps and parameters remain the same.

[0074] Example 10

[0075] This example provides a method for preparing carbon nanotube cluster microspheres based on polymer waste. The difference from Example 1 is that the amount of dry ice used as the reaction solvent system is 5.50 ± 0.01 g, and the remaining steps and parameters remain the same.

[0076] Example 11

[0077] This example provides a method for preparing carbon nanotube cluster microspheres based on polymer waste. The difference from Example 1 is that the amount of dry ice used as the reaction solvent system is 15.00 ± 0.01 g, and the remaining steps and parameters remain the same.

[0078] Example 12

[0079] This example provides a method for preparing carbon nanotube cluster microspheres based on polymer waste. The difference from Example 1 is that the amount of dry ice used as the reaction solvent system is 19.50 ± 0.01 g, and the remaining steps and parameters remain the same.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing a carbon material based on waste polymer raw materials. The difference from Example 1 is that 0.5 g of nickel chloride is added as a catalyst, and the remaining steps and parameters remain the same.

[0082] The SEM image of the final product is as Figure 8 shown. It can be seen from Figure 8 that the final product is mainly composed of a large number of carbon microspheres and a small amount of irregular flaky substances, and no carbon nanotube cluster microspheres are formed.

[0083] Comparative Example 2

[0084] This comparative example provides a method for preparing a carbon material based on waste polymer raw materials. The difference from Example 1 is that 0.5 g of nickel sulfate is added as a catalyst. After the reaction kettle is sealed, it is placed in a muffle furnace and heated at a heating rate of 10 °C / min to 800 °C, and the holding reaction time is 3 h. The remaining steps and parameters remain the same.

[0085] The SEM image of the final product is as Figure 9 shown. It can be seen from Figure 9 that the final product is carbon microspheres with an irregular morphology, and no carbon nanotube cluster microspheres are formed.

[0086] Comparative Example 3

[0087] This comparative example provides a method for preparing a carbon material based on waste polymer raw materials. The difference from Example 1 is that no catalyst is added, and the remaining steps and parameters remain the same.

[0088] The SEM image of the final product is as Figure 10 shown. It can be seen from Figure 10 that the final product is carbon microspheres with regular morphology, and no carbon nanotube cluster microspheres are generated.

[0089] The raw materials used in Examples 1-12 and Comparative Examples 1-3 and the final yields of carbon nanotube cluster microspheres are shown in Table 1.

[0090] Table 1

[0091]

[0092] As can be seen from the above examples and comparative examples, by changing the amount of transition metal acetate or oxalate used as the catalyst, the morphology of the final product can be regulated; when the amount of transition metal acetate or oxalate is relatively small, the yield of carbon nanotube cluster microspheres in the final product is relatively small, and when the amount of transition metal acetate or oxalate is relatively large, flaky and irregular blocky products are likely to be generated, resulting in a relatively small yield of carbon nanotube cluster microspheres in the final product;

[0093] When the amount of transition metal acetate or oxalate is in the range of 0.4 - 0.6 g, the final product is mainly carbon nanotube cluster microspheres with a porous structure in morphology. Compared with ordinary carbon materials, it has a higher specific surface area and better application effects in the fields of lithium-ion batteries, energy storage, pollutant treatment, etc.

[0094] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to this process, method, article or device.

[0095] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of carbon nanotube cluster microspheres based on polymer waste, characterized in that, It includes the following steps: Taking the polymer waste as raw material and placing it with a catalyst in a supercritical carbon dioxide system, under the conditions of a temperature of 500 - 800 °C and a pressure of 0.7 - 300 MPa, after heat preservation and pressure maintenance for 3 - 12 h, naturally cooling to room temperature, and after acid treatment of the obtained intermediate product, carbon nanotube cluster microspheres are obtained.

2. The preparation method of a carbon nanotube cluster microsphere based on polymer waste according to claim 1, characterized in that, The polymer waste includes polyethylene, polypropylene, polyethylene terephthalate, polyurethane, polyvinyl chloride, polystyrene, and polyurethane.

3. The preparation method of a carbon nanotube cluster microsphere based on polymer waste according to claim 1, characterized in that, The catalyst is one or a combination of transition metal acetates or transition metal oxalates.

4. The preparation method of a carbon nanotube cluster microsphere based on polymer waste according to claim 3, characterized in that, The transition metal acetates include nickel acetate, iron acetate, cobalt acetate, or manganese acetate; the transition metal oxalates include nickel oxalate, iron oxalate, or cobalt oxalate.

5. The preparation method of a carbon nanotube cluster microsphere based on polymer waste according to claim 1, characterized in that, The mass ratio of the catalyst to the polymer waste is 0.3 - 1.5:

1.

6. The preparation method of a carbon nanotube cluster microsphere based on polymer waste according to claim 5, wherein The mass ratio of the catalyst to the polymer waste is 0.4 - 0.6:

1.

7. The preparation method of a carbon nanotube cluster microsphere based on polymer waste according to claim 1, wherein The mass ratio of the supercritical carbon dioxide to the polymer waste is 5 - 20:

1.

8. The preparation method of a carbon nanotube cluster microsphere based on polymer waste according to claim 1, wherein During the acid treatment process, the acid solution soaking method is adopted. The acid solution includes inorganic acids or organic acids with a concentration of 1 - 10 mol / L; the soaking time is 2 - 10 h.

9. The preparation method of a carbon nanotube cluster microsphere based on polymer waste according to claim 8, wherein, The inorganic acids include nitric acid, sulfuric acid, perchloric acid, hydroiodic acid, and hydrobromic acid; the organic acids include methanesulfonic acid or benzenesulfonic acid.

10. The preparation method of a carbon nanotube cluster microsphere based on polymer waste according to claim 1, wherein, The carbon nanotube cluster microspheres are formed by winding of carbon nanotubes. The size of the microspheres is 1 - 5 μm; the diameter of the carbon nanotubes is 50 - 200 nm, and the length is 0.5 - 5 μm.

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