Preparation method and application of porous carbon spheres based on waste cotton textiles

Abstract

The invention discloses a preparation method and application of porous carbon spheres based on waste cotton textiles. The method comprises the following steps: S1, cleaning the waste cotton textiles; s2, adding the waste cotton textile, a reaction aid and water into a reaction kettle for hydrothermal reaction, and finally washing and drying to obtain a solid product; s3, soaking the solid product in an alkali solution for activating treatment, wherein the activation temperature is 30-120 DEG C; the activation time is 15-120 minutes, and then washing and drying to obtain an activated solid product; and S4, carrying out gradient heating carbonization on the activated solid product in an inert atmosphere to obtain the porous carbon spheres. In the step S3, the porous carbon spheres with different particle sizes can be prepared by changing the concentration of the alkali solution, so that the purpose of regulating the particle sizes of the porous carbon spheres is achieved. The prepared carbon sphere material can be used in the fields of supercapacitor electrode materials, water electrolysis hydrogen evolution and oxygen evolution catalytic electrode materials, electromagnetic shielding and absorbents, oil-water separation adsorbents, seawater desalination materials and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of waste cotton textiles, and in particular to a preparation method and application of porous carbon spheres based on waste cotton textiles. Background Art

[0002] With the improvement of living standards, more and more waste cotton textiles are generated in daily life. At present, most of the waste cotton textiles are disposed of by landfilling or incineration, which exacerbates resource waste and environmental pollution. Physical recycling is relatively low-cost, but the quality of the recycled products will be reduced to some extent. Therefore, how to efficiently recycle and highly utilize waste cotton textiles has become an urgent problem to be solved.

[0003] Waste cotton textiles are rich in carbon elements, which provides the possibility of converting them into high-value carbon materials. For example, Patent CN106609405A discloses a method for recycling and reusing waste cotton textiles. Through activation, pre-oxidation, and high-temperature carbonization, waste cotton textiles are converted into multifunctional carbon fiber clusters, which can be applied to antibacterial products and adsorption of wastewater. Patent CN116920795A discloses a method for mineralizing tetracycline antibiotics based on waste cotton cloth pyrolysis carbon composites. Through operations such as pyrolysis, metal loading, compounding, alternating light irradiation and light-shielding stirring, a silver-doped soft carbon-carbon nitride-TiO2 composite material is prepared from waste cotton cloth and can be used for photocatalysis. However, the above methods have cumbersome preparation processes and long preparation cycles.

[0004] Spherical carbon materials are a class of carbon-based materials with regular spherical morphologies. Due to their unique physical and chemical properties, they show broad application prospects in the fields of adsorption, catalysis, energy storage, and biomedicine. Compared with other forms of carbon materials (such as graphene, carbon nanotubes, etc.), spherical carbon materials have excellent fluidity, higher packing density, and good mechanical strength, making them more advantageous in industrial applications. Patent CN117658134A discloses a high-performance activated carbon microsphere and its preparation method and application. By activating, hydrothermal treating, and carbonizing waste cotton fabrics, activated carbon microspheres are obtained, which have the potential to be applied to the adsorption and degradation of methylene blue. However, this method can only prepare carbon microspheres of a fixed size and cannot achieve the regulation of the particle size of carbon microspheres, and cannot prepare carbon microspheres of different sizes, which limits the application range of carbon microspheres. In different application fields, different requirements may be imposed on the size of spherical carbon. Summary of the Invention

[0005] In order to achieve the regulation of the particle size of spherical carbon during the preparation of spherical carbon materials from waste cotton textiles, the present invention provides a preparation method of porous carbon spheres based on waste cotton textiles.

[0006] The preparation method of porous carbon spheres based on waste cotton textiles provided by the present invention comprises the following steps:

[0007] S1. Wash and treat the waste cotton textiles;

[0008] The waste cotton textiles can be any one of pure cotton textiles, polyester-cotton textiles, ammonia-cotton textiles, cotton-polyamide textiles, nitrile-cotton textiles, and cotton-viscose textiles. The waste cotton textiles are first ultrasonically cleaned with deionized water for 10 - 60 min, then ultrasonically treated in absolute ethanol for 10 - 60 min, and dried for standby.

[0009] S2. Catalytic-assisted hydrothermal reaction;

[0010] Add the waste cotton textiles, reaction assistant, and water after the cleaning treatment in step S1 into a reaction kettle for hydrothermal reaction. The hydrothermal reaction temperature is 160 - 280 °C, and the hydrothermal reaction time is 2 - 12 h. Finally, wash and dry to obtain a solid product.

[0011] Among them, the mass ratio of the amounts of the waste cotton textiles, reaction assistant, and water is (0.6 - 38):(0.7 - 83):(60 - 2000).

[0012] The reaction assistant is a catalyst or an acidic reagent or a compound of both. The catalyst is at least one of copper phosphate, copper citrate, copper oxalate, copper nitrate, copper acetate, copper sulfate, zinc nitrate, zinc sulfate, zinc acetate, and zinc citrate.

[0013] The acidic reagent is one of citric acid, oxalic acid, phosphoric acid, sulfuric acid, acetic acid, nitric acid, and hydrochloric acid.

[0014] Preferably, the reaction assistant uses a compound of a catalyst and an acidic reagent. At this time, the mass ratio of the amounts of the waste cotton textiles, acidic reagent, catalyst, and water is (0.6 - 38):(0.6 - 38):(0.1 - 45):(60 - 2000).

[0015] S3. Immerse the solid product in an alkali solution for activation treatment. The activation temperature is 30 - 120 °C; the activation time is 15 - 120 min, and then wash and dry to obtain an activated solid product.

[0016] The alkali solution is one of the aqueous solutions of NaOH, KOH, and LiOH, and the concentration of the alkali solution is 0.5 - 6 mol / L.

[0017] S4. Gradually heat up and carbonize the activated solid product in an inert atmosphere. The process of gradually heating up and carbonizing is as follows: First, heat up to 300 - 500 °C and keep it warm for 15 - 120 min; then heat up to 600 - 1000 °C and keep it warm for 30 - 180 min. Finally, obtain a spherical porous carbon material (referred to as porous carbon spheres). The inert atmosphere is one of argon, nitrogen, and helium.

[0018] In the above preparation method, porous carbon spheres with different particle sizes can be prepared by changing the concentration of the alkali solution in step S3.

[0019] The porous carbon spheres prepared by the present invention contain a rich microporous structure and have a high specific surface area. The BET specific surface area is 100 - 800 m 2 g -1 ² / g; the carbon sphere material contains 60 - 95 at% of carbon element and 5 - 40 at% of oxygen element. The porous carbon spheres can be used in fields such as supercapacitor electrodes, electrolytic water hydrogen evolution and oxygen evolution catalytic electrodes, lithium-ion electrodes, sodium-ion electrodes, potassium-ion electrodes, electromagnetic shielding and absorbers, oil-water separation adsorbents, and seawater desalination agents.

[0020] The present invention uses waste cotton textiles as a carbon source and realizes high-value utilization through an innovative process. First, with the help of catalytic-assisted hydrothermal reaction, the waste cotton textiles are induced to undergo structural remodeling to form spherical precursors. The application modes of the catalyst and the acidic reagent show diverse characteristics. They can be used alone or in combination. Compared with using the catalyst or the acidic reagent alone, when the catalyst and the acidic reagent are used in combination, the spheroidization effect can be significantly improved through the synergistic effect. Then, an alkali solution activation strategy is adopted to control the particle size of the carbon spheres. Finally, through a gradient carbonization process, impurities and residual alkali are effectively removed, which not only significantly enhances the chemical stability of the carbon spheres; through a staged heating method, sufficient time for rearrangement and regularization of carbon atoms inside the carbon spheres is provided, thereby improving the graphitization degree. At the same time, the inventors' research shows that compared with the carbon spheres prepared by the gradient carbonization process, the carbon spheres prepared by the direct carbonization process have obvious agglomeration and adhesion phenomena. This agglomeration phenomenon reduces the specific surface area of the carbon spheres, decreases the number of surface active sites, and seriously affects the dispersibility of the carbon spheres. These performance defects directly limit the functional applications of the carbon spheres in multiple fields. Therefore, the preparation process of the present invention cleverly combines multi-step treatment technologies such as catalytic-assisted hydrothermal reaction, alkali activation, and gradient carbonization. Each link synergistically enhances the efficiency and provides a new path for the resource utilization of waste cotton textiles.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] (1) The present invention uses waste cotton textiles as raw materials for waste recycling, reducing resource waste. The preparation method can be used for waste pure cotton textiles and is also equally applicable to waste cotton blended textiles (such as polyester-cotton textiles, ammonia-cotton textiles, cotton-nylon textiles, nitrile-cotton textiles, cotton-viscose textiles, etc.).

[0023] (2) The porous carbon spheres prepared by the present invention have a rich pore structure and a uniform pore size distribution; moreover, during the preparation process, carbon spheres of different sizes can be prepared by adjusting the concentration of the alkaline solution, meeting different application requirements. The prepared carbon sphere materials can be used in fields such as supercapacitor electrode materials, electrolytic water hydrogen evolution and oxygen evolution catalytic electrode materials, electromagnetic shielding and absorption materials, oil-water separation adsorbents, and seawater desalination materials.

[0024] (3) The preparation method of the present invention has a simple process, low cost, and simple and easily available raw materials, is easy to achieve large-scale batch production, and is convenient for industrial application and promotion.

[0025] Other advantages, objectives, and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. Brief Description of the Drawings

[0026] Figure 1 It is a flow chart of the preparation method of the porous carbon spheres based on waste cotton textiles of the present invention.

[0027] Figure 2 It is an SEM image of the porous carbon spheres obtained in Example 1.

[0028] Figure 3 It is the nitrogen adsorption-desorption isotherm of the porous carbon spheres obtained in Example 1.

[0029] Figure 4 It is the pore size distribution curve of the porous carbon spheres obtained in Example 1.

[0030] Figure 5 It is the Raman spectrum of the porous carbon spheres obtained in Example 1.

[0031] Figure 6 It is the X-ray photoelectron spectroscopy of the porous carbon spheres obtained in Example 1.

[0032] Figure 7 It is an SEM image of the porous carbon spheres obtained in Example 2.

[0033] Figure 8 It is an SEM image of the porous carbon spheres obtained in Example 3.

[0034] Figure 9 It is the particle size distribution diagram of the porous carbon spheres prepared with different alkaline solution concentrations. Among them, Figures (a), (b), (c), (d), and (e) correspond to sodium hydroxide concentrations of 0, 0.5, 0.75, 1.0, and 1.25 mol / L, respectively.

[0035] Figure 10 It is an SEM image of the porous carbon spheres obtained in Example 5.

[0036] Figure 11SEM image of the porous carbon spheres obtained in Example 6.

[0037] Figure 12 Reflection loss diagram of the porous carbon spheres obtained in Example 6. Detailed implementation manners

[0038] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0039] Example 1

[0040] A method for preparing porous carbon spheres is as Figure 1 shown, and is specifically as follows:

[0041] (1) The waste cotton textiles are successively placed in deionized water and absolute ethanol for ultrasonic treatment for 10 min each to wash away soluble impurities. After drying, they are cut or shredded into flocs for standby.

[0042] (2) The flocculent cotton textiles, citric acid, copper citrate and deionized water are added to a reaction kettle and reacted at 260 °C for 8 h. After the reaction is completed, the solid product is washed with deionized water until the filtrate is clear and transparent, and then dried to obtain the solid product. Among them, the mass ratio of the cotton textiles, citric acid, copper citrate and deionized water added to the reaction kettle is 12:12:1:600.

[0043] (3) The solid product obtained in step (2) is placed in a 1 mol / L NaOH solution and soaked at a constant temperature of 60 °C for 30 min, and then washed with deionized water until the filtrate is neutral, and dried to obtain the NaOH-activated solid product.

[0044] (4) The activated solid product obtained in step (3) is carbonized in a nitrogen atmosphere at 300 °C for 60 min, and then carbonized at 900 °C for 60 min, and porous carbon spheres are obtained after naturally cooling to room temperature.

[0045] Figure 2 is the SEM image of the prepared porous carbon spheres. It can be seen from the figure that the carbon material has a spherical structure with a diameter of about 5.1 ± 0.12 μm.

[0046] Figure 3 is the nitrogen adsorption-desorption isotherm of the prepared porous carbon spheres. It can be seen from the figure that the specific surface area of the carbon material can reach 396.92 m 2 g -1 .

[0047] Figure 4 is the pore size distribution curve of the prepared porous carbon spheres. It can be seen from the figure that the pore size of the carbon material is mainly distributed below 2 nm.

[0048] Figure 5 is the Raman spectrum of the prepared porous carbon spheres. It can be seen from the figure that its I D / I G value corresponds to a large number of defective carbon structures.

[0049] Figure 6 is the X-ray photoelectron total spectrum of the prepared porous carbon spheres. It can be seen from the figure that the carbon material contains two elements, C and O.

[0050] Example 2

[0051] On the basis of Example 1, in step (2), the catalyst copper citrate is replaced with citric acid of the same amount, that is, only the acidic reagent citric acid is used in the hydrothermal reaction, and other steps remain unchanged. The SEM image of the finally prepared porous carbon spheres is shown in Figure 7 .

[0052] Example 3

[0053] On the basis of Example 1, in step (2), citric acid is replaced with copper citrate of the same amount, that is, only the catalyst copper citrate is used in the hydrothermal reaction, and other steps remain unchanged. The SEM image of the finally prepared porous carbon spheres is shown in Figure 8 .

[0054] From Figure 2 , Figure 7 and Figure 8 comparisons, it can be seen that during the hydrothermal reaction process, porous carbon spheres can be prepared by using only the catalyst or the acidic reagent alone; however, when the catalyst and the acidic reagent are used in combination, the number of prepared porous carbon spheres is more, and the scattered impurities are less, improving the yield of carbon spheres. This is because when the catalyst and the acidic reagent are used in combination, they can play a synergistic role, further promoting the structural remodeling of waste cotton textiles to form more spherical precursors and significantly improving the spheroidization yield.

[0055] Example 4

[0056] On the basis of Example 1, in step (3), the alkali activation reaction conditions are changed; the NaOH solution is replaced with deionized water, and other conditions remain unchanged to prepare carbon sphere A. According to the same method, the concentration of the NaOH solution is adjusted to 0.5 mol / L, 0.75 mol / L, and 1.25 mol / L respectively, and other conditions remain unchanged to prepare carbon spheres B, C, and D respectively.

[0057] The particle size analysis tests were carried out on the porous carbon spheres of Example 1, carbon sphere A, carbon sphere B, carbon sphere C, and carbon sphere D, and the measured particle size distributions are as shown in Figure 9As shown, where Figures (a), (b), (c), (d), and (e) correspond to sodium hydroxide concentrations of 0, 0.5, 0.75, 1.0, and 1.25 mol / L respectively. It can be seen from the figures that in the method for preparing porous carbon spheres of the present invention, changing the concentration of the alkali solution in step (3) can prepare porous carbon spheres with different particle sizes. As the concentration of the alkali solution increases, the particle size of the prepared carbon spheres gradually increases. In addition, the particle sizes of carbon spheres A and B are relatively similar, indicating that when the concentration of the sodium hydroxide solution is low, the change in concentration does not have an obvious effect on regulating the particle size of the carbon spheres. Only when the concentration of the sodium hydroxide solution is relatively high does the change in concentration have an impact on the particle size of the carbon spheres.

[0058] Example 5

[0059] On the basis of Example 1, in step (4), the carbonization heating method is changed. Specifically: the activated solid product obtained in step (3) is directly heated to 900 °C under the protection of a nitrogen atmosphere and carbonized at a constant temperature for 60 min, and then naturally cooled to room temperature to obtain porous carbon spheres.

[0060] Figure 10 It is the SEM image of the porous carbon spheres obtained in Example 5. Compared with the SEM image of the porous carbon spheres in Example 1, it can be seen that the porous carbon spheres in Example 5 are still spherical in structure, but there is an obvious phenomenon of agglomeration and adhesion. This shows that the gradient carbonization process adopted in step (4) of the present invention can avoid the agglomeration of carbon spheres and obtain carbon spheres with good dispersibility.

[0061] Example 6

[0062] A method for preparing porous carbon spheres is as follows:

[0063] (1) The waste ammonia cotton textiles are successively placed in deionized water and absolute ethanol for ultrasonic treatment for 60 min each to wash away soluble impurities, dried and then cut or shredded into flocs for standby.

[0064] (2) The flocculent ammonia cotton textiles, sulfuric acid, zinc nitrate, and deionized water are added to the reaction kettle and reacted at 240 °C for 12 h. After the reaction, the solid product is washed with deionized water until the filtrate is clear and transparent, and then dried to obtain the solid product. Among them, the mass ratio of the ammonia cotton textiles, sulfuric acid, zinc nitrate, and deionized water added to the reaction kettle is 6:6:1:300.

[0065] (3) The solid product obtained in step (2) is placed in a 1 mol / L NaOH solution and soaked at a constant temperature of 30 °C for 120 min, and then washed with deionized water until the filtrate is neutral, and then dried to obtain the activated solid product.

[0066] (4) The activated solid product obtained in step (3) is carbonized under the protection of a nitrogen atmosphere at 300 °C for 120 min, and then carbonized at 600 °C for 120 min. After naturally cooling to room temperature, porous carbon spheres are obtained.

[0067] Figure 11 SEM image of the porous carbon spheres obtained in Example 6. It can be seen from the figure that the carbon material has a spherical structure with a diameter of about 4.8 ± 0.07 μm.

[0068] Figure 12 Reflection loss diagram of the porous carbon spheres obtained in Example 6. It can be seen from the figure that the minimum reflection loss of the carbon material can reach -39.4 dB.

[0069] Example 7

[0070] A preparation method of porous carbon spheres is as follows:

[0071] (1) The waste polyester-cotton textile is successively placed in deionized water and absolute ethanol for ultrasonic treatment for 30 min each to wash away soluble impurities. After drying, it is cut or shredded into floccules for standby.

[0072] (2) The flocculent polyester-cotton textile, hydrochloric acid, copper nitrate and deionized water are added to a reaction kettle and reacted at 240 °C for 10 h. After the reaction, the solid product is washed with deionized water until the filtrate is clear and transparent, and then dried to obtain the solid product. Among them, the mass ratio of the polyester-cotton textile, hydrochloric acid, copper nitrate and deionized water added to the reaction kettle is 12:6:5:600.

[0073] (3) The solid product obtained in step (2) is placed in a 3 mol / L KOH solution and soaked at a constant temperature of 30 °C for 15 min, and then washed with deionized water until the filtrate is neutral, and then dried to obtain the activated solid product.

[0074] (4) The activated solid product obtained in step (3) is carbonized under the protection of a nitrogen atmosphere at 300 °C for 90 min, and then carbonized at 800 °C for 120 min. After naturally cooling to room temperature, porous carbon spheres are obtained.

[0075] Example 8

[0076] A preparation method of porous carbon spheres is as follows:

[0077] (1) The waste ammonia-cotton textile is successively placed in deionized water and absolute ethanol for ultrasonic treatment for 50 min each to wash away soluble impurities. After drying, it is cut or shredded into floccules for standby.

[0078] (2) Add the flocculent ammonia cotton textile, phosphoric acid, copper phosphate, and deionized water into a reaction kettle, react at 280 °C for 10 h. After the reaction, wash the solid product with deionized water until the filtrate is clear and transparent, and then dry it to obtain the solid product. Among them, the mass ratio of the ammonia cotton textile, phosphoric acid, copper phosphate, and deionized water added into the reaction kettle is 6:12:1:400.

[0079] (3) Place the solid product obtained in step (2) into a 1 mol / L NaOH solution, soak it at a constant temperature of 120 °C for 15 min, then wash it with deionized water until the filtrate is neutral, and dry it to obtain the activated solid product.

[0080] (4) Under the protection of a nitrogen atmosphere, carbonize the activated solid product obtained in step (3) at 500 °C for 15 min, and then carbonize it at 700 °C for 120 min. After naturally cooling to room temperature, porous carbon spheres are obtained.

[0081] Example 9

[0082] A preparation method of porous carbon spheres is as follows:

[0083] (1) Place the waste cotton and nylon textile into deionized water and absolute ethanol successively, ultrasonically treat each for 30 min, wash off the soluble impurities, dry it, and then cut or shred it into floccules for standby.

[0084] (2) Add the flocculent cotton and nylon textile, nitric acid, copper citrate, and deionized water into a reaction kettle, react at 280 °C for 12 h. After the reaction, wash the solid product with deionized water until the filtrate is clear and transparent, and then dry it to obtain the solid product. Among them, the mass ratio of the cotton and nylon textile, nitric acid, copper citrate, and deionized water added into the reaction kettle is 2:4:1:200.

[0085] (3) Place the solid product obtained in step (2) into a 0.5 mol / L LiOH solution, soak it at a constant temperature of 60 °C for 60 min, then wash it with deionized water until the filtrate is neutral, and dry it to obtain the activated solid product.

[0086] (4) Under the protection of a nitrogen atmosphere, carbonize the activated solid product obtained in step (3) at 400 °C for 80 min, and then carbonize it at 900 °C for 30 min. After naturally cooling to room temperature, porous carbon spheres are obtained.

[0087] Example 10

[0088] A preparation method of porous carbon spheres is as follows:

[0089] (1) The waste nitrile cotton textiles are successively placed in deionized water and absolute ethanol for ultrasonic treatment for 30 min each to wash away soluble impurities, dried, and then cut or ground into flocs for standby.

[0090] (2) The flocculent nitrile cotton textiles, acetic acid, copper acetate, and deionized water are added to a reaction kettle and reacted at 240 °C for 12 h. After the reaction, the solid product is washed with deionized water until the filtrate is clear and transparent, and then dried to obtain the solid product. Among them, the mass ratio of the nitrile cotton textiles, acetic acid, copper acetate, and deionized water added to the reaction kettle is 1:2:1:80.

[0091] (3) The solid product obtained in step (2) is placed in a 6 mol / L KOH solution and soaked at a constant temperature of 30 °C for 15 min, and then washed with deionized water until the filtrate is neutral, and dried to obtain the activated solid product.

[0092] (4) The activated solid product obtained in step (3) is carbonized at 500 °C for 120 min under the protection of a nitrogen atmosphere, and then carbonized at 1000 °C for 30 min. After naturally cooling to room temperature, porous carbon spheres are obtained.

[0093] Example 11

[0094] A method for preparing porous carbon spheres is as follows:

[0095] (1) The waste cotton fiber textiles are successively placed in deionized water and absolute ethanol for ultrasonic treatment for 30 min each to wash away soluble impurities, dried, and then cut or ground into flocs for standby.

[0096] (2) The flocculent cotton fiber textiles, oxalic acid, zinc nitrate, and deionized water are added to a reaction kettle and reacted at 280 °C for 10 h. After the reaction, the solid product is washed with deionized water until the filtrate is clear and transparent, and then dried to obtain the solid product. Among them, the mass ratio of the cotton fiber textiles, oxalic acid, zinc nitrate, and deionized water added to the reaction kettle is 5:5:1:600.

[0097] (3) The solid product obtained in step (2) is placed in a 1 mol / L NaOH solution and soaked at a constant temperature of 120 °C for 120 min, and then washed with deionized water until the filtrate is neutral, and dried to obtain the activated solid product.

[0098] (4) The activated solid product obtained in step (3) is carbonized at 350 °C for 120 min under the protection of a nitrogen atmosphere, and then carbonized at 700 °C for 180 min. After naturally cooling to room temperature, porous carbon spheres are obtained.

[0099] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the technical content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of porous carbon spheres based on waste cotton textiles, characterized in that, It includes the following steps: S1. Wash the waste cotton textiles; S2. Add the washed waste cotton textiles, reaction aids and water into a reaction kettle for hydrothermal reaction. The hydrothermal reaction temperature is 160-280 °C, and the hydrothermal reaction time is 2-12 h. Finally, wash and dry to obtain a solid product. The reaction aids are a catalyst or an acidic reagent or a compound of both. The catalyst is at least one of copper phosphate, copper citrate, copper oxalate, copper nitrate, copper acetate, copper sulfate, zinc nitrate, zinc sulfate, zinc acetate, zinc citrate. The acidic reagent is one of citric acid, oxalic acid, phosphoric acid, sulfuric acid, acetic acid, nitric acid, hydrochloric acid; S3. Immerse the solid product in an alkali solution for activation treatment. The activation temperature is 30-120 °C, and the activation time is 15-120 min. Then wash and dry to obtain an activated solid product; S4. Carry out gradient heating carbonization of the activated solid product in an inert atmosphere. First, heat up to 300-500 °C and keep it warm for 15-120 min. Then heat up to 600-1000 °C and keep it warm for 30-180 min. Finally, obtain porous carbon spheres; In step S3, by changing the concentration of the alkali solution, the particle size of the porous carbon spheres can be regulated.

2. The preparation method of the porous carbon spheres based on waste cotton textiles according to claim 1, wherein The waste cotton textiles are one of pure cotton textiles, polyester-cotton textiles, ammonia-cotton textiles, cotton-polyamide textiles, acrylic-cotton textiles, cotton-viscose textiles.

3. The preparation method of the porous carbon spheres based on waste cotton textiles according to claim 1, characterized in that, In step S2, the mass ratio of the amounts of the waste cotton textiles, reaction aids and water is (0.6-38):(0.7-83):(60-2000).

4. The preparation method of the porous carbon spheres based on waste cotton textiles according to claim 3, characterized in that, In step S2, the reaction aids are a compound of a catalyst and an acidic reagent.

5. The preparation method of the porous carbon spheres based on waste cotton textiles according to claim 1, characterized in that, In step S3, the alkali solution is one of aqueous solutions of NaOH, KOH and LiOH, and the concentration of the alkali solution is 0.5-6 mol / L.

6. The preparation method of the porous carbon spheres based on waste cotton textiles according to claim 1, characterized in that, In step S4, the inert atmosphere is one of argon, nitrogen or helium.

7. A porous carbon sphere, characterized in that, Prepared by the preparation method according to any one of claims 1-6.

8. The application of the porous carbon spheres according to claim 7, wherein, For supercapacitor electrodes, electrolytic water hydrogen evolution and oxygen evolution catalytic electrodes, lithium ion electrodes, sodium ion electrodes, potassium ion electrodes, electromagnetic shielding and absorbers, oil-water separation adsorbents and seawater desalination agents.

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