Soft, bendable sodium alginate carbon aerogels and methods of making and using the same
By introducing cotton fabric as a support framework and nitrogen source into carbon aerogel, a soft and flexible sodium alginate carbon aerogel was prepared, which solved the problems of unstable structure and poor flexibility of carbon aerogel and achieved efficient treatment of dye wastewater.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN TEXTILE UNIV
- Filing Date
- 2026-03-02
- Publication Date
- 2026-06-16
AI Technical Summary
Existing carbon aerogels have unstable structures, poor flexibility, and are difficult to process and shape, resulting in poor adsorption effects. They are also prone to collapse, especially under humid or pressurized conditions, which limits their application in dynamic filtration or packed beds.
Cotton fabric was used as a supporting framework, and sodium alginate solution was poured onto its surface. After freeze-drying, a bilayer aerogel precursor was formed. Then, a nitrogen source was introduced, and a bilayer carbon aerogel was obtained through high-temperature carbonization. The cotton fabric layer was used to suppress the violent shrinkage of sodium alginate aerogel during high-temperature pyrolysis, forming a three-dimensional porous material with stable structure and regular shape.
A soft, flexible sodium alginate carbon aerogel was obtained, which has excellent adsorption capacity and removal efficiency. It exhibits high adsorption performance for methylene blue, methyl orange and Congo red dyes and is suitable for dye wastewater treatment.
Smart Images
Figure CN122212673A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of functional materials technology, specifically to a soft, flexible sodium alginate carbon aerogel, its preparation method, and its applications. Background Technology
[0002] Aerogels, as three-dimensional porous materials, possess extremely high specific surface area, low density, and tunable pore structure, demonstrating great potential in the field of adsorption. SA-based aerogels, due to their wide availability of raw materials, good biocompatibility, and the abundance of active groups such as carboxyl and hydroxyl groups in their molecular chains, exhibit a certain affinity for dye molecules, and have therefore been extensively studied. However, pure SA-based aerogels suffer from the following prominent problems: poor mechanical properties, prone to structural collapse during drying or under stress, leading to pore closure and loss of active sites; limited adsorption capacity, with the adsorption capacity of a single SA-based material insufficient to meet the requirements of efficient dye treatment; and difficulty in controlling morphology, easily undergoing severe shrinkage and deformation during high-temperature carbonization, affecting the material's consistency and practicality.
[0003] To improve the performance of SA-based aerogels, research has largely focused on material composites or modifications. For example, SA-based aerogels are composited with polyethyleneimine, chitosan, graphene, carbon nanotubes, etc., or functional groups are introduced through cross-linking, doping, and other methods. While these methods can improve adsorption performance to some extent, they also bring problems such as complex processes, increased costs, and a heavier environmental burden. More importantly, most composite aerogels have not fundamentally solved the problems of low mechanical strength and poor structural stability, especially their tendency to collapse under humid or pressurized conditions, making recycling or industrial-scale applications difficult.
[0004] Carbon aerogels are a class of porous carbon materials prepared by high-temperature carbonization of organic precursors. They combine the porosity of aerogels with the structural stability of carbon materials, and have attracted much attention in recent years in the fields of adsorption, energy storage, and catalysis. However, traditional carbon aerogels still face the following challenges in their preparation: uncontrollable carbonization shrinkage, with the precursor undergoing pyrolysis and shrinkage at high temperatures, leading to pore structure collapse and a decrease in specific surface area; high brittleness and poor flexibility, the materials are usually brittle and difficult to process and shape, limiting their application in dynamic filtration or packed beds; and low accessibility of active sites, with some microporous structures difficult for dye molecules to utilize effectively, affecting adsorption kinetics and capacity. Summary of the Invention
[0005] In view of the technical problems existing in the background art, this application provides a soft and flexible sodium alginate carbon aerogel, its preparation method and application, aiming to solve the problems of unstable structure, poor flexibility, difficulty in processing and shaping, and poor adsorption effect of existing carbon aerogels.
[0006] In a first aspect, this application provides a method for preparing a soft, flexible sodium alginate carbon aerogel, comprising the following steps: S1. Immerse the cotton fabric in an alkaline solution for cleaning and then dry it to obtain a pretreated cotton fabric; S2. Dissolve sodium alginate in deionized water and stir until completely dissolved to obtain a sodium alginate solution; S3. The sodium alginate solution is uniformly poured onto the pretreated cotton fabric and allowed to stand to obtain the composite material. S4. Freeze and dry the composite material to obtain an aerogel precursor with a double-layer structure; S5. The aerogel precursor and nitrogen source are subjected to high-temperature carbonization to obtain a bilayer carbon aerogel.
[0007] In the technical solution of this application embodiment, cotton fabric is used as a supporting skeleton, and sodium alginate solution is poured onto its surface. After freeze-drying, a bilayer aerogel precursor is formed. Then, a nitrogen source is introduced, and a bilayer carbon aerogel is obtained through high-temperature carbonization. The supporting effect of the cotton fabric layer effectively inhibits the severe shrinkage of the sodium alginate aerogel during high-temperature pyrolysis, resulting in a structurally stable and regularly shaped three-dimensional porous material. The carbonized material is flexible and processable, overcoming the brittleness of traditional carbon aerogels. The uniform loading of the sodium alginate carbon aerogel layer on the fabric surface significantly increases the number of oxygen / sodium active sites and nitrogen-doped binding sites.
[0008] In some embodiments, in step S1, the cotton fabric is a pure cotton nonwoven fabric; the weight of the cotton fabric is 40~75 g / m². 2 .
[0009] In this embodiment, a pure cotton nonwoven fabric is used as the substrate, and the fabric is used as a supporting skeleton to achieve a uniform aerogel coating and controllable carbonization, thereby significantly increasing the available adsorption active sites.
[0010] In some embodiments, in step S2, the concentration of the sodium alginate solution is 1~4 g / 100 mL.
[0011] In this embodiment, the concentration of sodium alginate solution will affect the subsequent dynamic effect as well as the skeleton structure and structural strength of the material. By pouring sodium alginate solution of a specific concentration onto cotton fabric, a structurally stable gel material can be obtained.
[0012] In some embodiments, in step S3, the pouring thickness of the sodium alginate solution is 2-8 mm.
[0013] In this embodiment, different thicknesses will affect the freeze-drying efficiency and sample quality. Generally, the thicker the sample, the more difficult the freeze-drying is, and problems such as uneven drying and structural collapse are more likely to occur.
[0014] In some embodiments, in step S4, the freezing temperature is -10°C and the freezing time is 24~48h.
[0015] In this embodiment, the sodium alginate solution is frozen and solidified, and a three-dimensional porous framework is constructed by utilizing the ice crystal template effect. This ensures that the sodium alginate layer is uniformly attached to the surface of the cotton fabric and provides structural stability for subsequent freeze-drying. Ultimately, a precursor with optimized pore structure is obtained, which is beneficial for nitrogen doping and the formation of active sites during the carbonization process.
[0016] In some embodiments, step S5 specifically includes the following steps: heating to 650~750℃ at a heating rate of 2~10℃ / min, and carbonizing for 1.5h.
[0017] In this embodiment, a carbon-based material skeleton is obtained and a porous structure is created and controlled through high-temperature carbonization under specific conditions.
[0018] In some embodiments, in step S6, the nitrogen source is dicyandiamide, and the mass ratio of the nitrogen source to the aerogel precursor is 1:1 to 3:1.
[0019] In this embodiment, by introducing a nitrogen source, the microporous structure of the carbon material is increased, creating more defects and adsorption active sites. Furthermore, introducing a nitrogen source during the carbonization process avoids interference with the freeze-drying process of sodium alginate compared to adding a nitrogen source during aerogel preparation. Additionally, the gaseous nitrogen source or the active nitrogen-containing species generated by pyrolysis can fully and uniformly diffuse and penetrate into the entire carbonized material, directly reacting with the forming active carbon sites.
[0020] Secondly, this application provides a soft, flexible sodium alginate carbon aerogel, which is prepared by the above-mentioned method for preparing soft, flexible sodium alginate carbon aerogel.
[0021] In the technical solution of this application embodiment, the soft and flexible sodium alginate carbon aerogel has a regular three-dimensional porous structure, which is structurally stable and also has bendability.
[0022] Thirdly, this application provides an application of a soft, flexible sodium alginate carbon aerogel for dye wastewater treatment.
[0023] In the technical solution of this application embodiment, the aerogel exhibits excellent adsorption capacity and removal efficiency for methylene blue, methyl orange, and Congo red dyes; it can be conveniently used to construct filtration devices to achieve efficient treatment of dye wastewater.
[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description
[0025] To more clearly illustrate the technical solution of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.
[0026] Figure 1 The images shown are SEM images of the aerogel prepared in Example 1. (a) is a cross-sectional SEM image of the aerogel precursor, (b) is a surface SEM image of the bilayer carbon aerogel, and (c) is a surface SEM image of the carbonized cotton nonwoven fabric. Detailed Implementation
[0027] The embodiments of the technical solution of this application are described in detail below. These embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore merely examples and should not be used to limit the scope of protection of this application.
[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terms “comprising” and “having” and any variations thereof as used herein are for the purpose of describing particular embodiments only and are not intended to limit this application.
[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0030] To address the problems of unstable structure, poor flexibility, difficulty in processing and molding, and poor adsorption effect of existing carbon aerogels, this application provides a soft, flexible sodium alginate carbon aerogel, its preparation method, and its applications. This application uses cotton fabric as a supporting framework, pours sodium alginate solution onto its surface, freeze-dries it to form a bilayer aerogel precursor, then introduces a nitrogen source and carbonizes it at high temperature to obtain the bilayer carbon aerogel. The supporting effect of the cotton fabric layer effectively inhibits the severe shrinkage of the sodium alginate aerogel during high-temperature pyrolysis, resulting in a structurally stable and regularly shaped three-dimensional porous material. The carbonized material is flexible and processable, overcoming the brittleness of traditional carbon aerogels. The uniform loading of the sodium alginate carbon aerogel layer on the fabric surface significantly increases the number of oxygen / sodium active sites and nitrogen-doped binding sites. The synergistic effect of these two factors gives it excellent adsorption capacity and removal efficiency for methylene blue, methyl orange, and Congo red dyes. The material can be easily used to construct filtration devices for efficient treatment of dye wastewater.
[0031] In a first aspect, this application provides a method for preparing a soft, flexible sodium alginate carbon aerogel, comprising the following steps: S1. Immerse the cotton fabric in an alkaline solution for cleaning and then dry it to obtain a pretreated cotton fabric; S2. Dissolve sodium alginate in deionized water and stir until completely dissolved to obtain a sodium alginate solution; S3. The sodium alginate solution is uniformly poured onto the pretreated cotton fabric and allowed to stand to obtain the composite material. S4. Freeze and dry the composite material to obtain an aerogel precursor with a double-layer structure; S5. The aerogel precursor and nitrogen source are subjected to high-temperature carbonization to obtain a bilayer carbon aerogel.
[0032] In the technical solution of this application embodiment, cotton fabric is used as a supporting skeleton, and sodium alginate solution is poured onto its surface. After freeze-drying, a bilayer aerogel precursor is formed. Then, a nitrogen source is introduced, and a bilayer carbon aerogel is obtained through high-temperature carbonization. The supporting effect of the cotton fabric layer effectively inhibits the severe shrinkage of the sodium alginate aerogel during high-temperature pyrolysis, resulting in a structurally stable and regularly shaped three-dimensional porous material. The carbonized material is flexible and processable, overcoming the brittleness of traditional carbon aerogels. The uniform loading of the sodium alginate carbon aerogel layer on the fabric surface significantly increases the number of oxygen / sodium active sites and nitrogen-doped binding sites. The synergistic effect of these two factors gives it excellent adsorption capacity and removal efficiency for methylene blue, methyl orange, and Congo red dyes. The material can be easily used to construct filtration devices to achieve efficient treatment of dye wastewater.
[0033] Furthermore, in some embodiments, in step S1, the alkaline solution is a NaOH solution with a concentration of 10 g / L; the cleaning temperature is 60°C, the cleaning time is 3 hours; and the drying temperature is 60°C.
[0034] Furthermore, in some embodiments, in step S1, the cotton fabric is a pure cotton nonwoven fabric; the weight of the cotton fabric is 40~75 g / m². 2 .
[0035] In the technical solution of this application embodiment, pure cotton nonwoven fabric is used as the base, and the fabric is used as the supporting skeleton to achieve uniform aerogel coating and controllable carbonization, thereby significantly increasing the available adsorption active sites.
[0036] Furthermore, in some embodiments, in step S2, the concentration of the sodium alginate solution is 1~4 g / 100 mL.
[0037] In the technical solution of this application embodiment, the concentration of sodium alginate solution will affect the subsequent dynamic effect as well as the skeleton structure and structural strength of the material. By pouring sodium alginate solution of a specific concentration onto cotton fabric, a structurally stable gel material can be obtained.
[0038] Furthermore, in some embodiments, in step S3, the pouring thickness of the sodium alginate solution is 2-8 mm.
[0039] In the technical solutions of this application embodiment, different thicknesses will affect the freeze-drying efficiency and sample quality of the sample. Generally, the thicker the sample, the more difficult the freeze-drying is, and problems such as uneven drying and structural collapse are likely to occur.
[0040] Furthermore, in some embodiments, the settling time in step S3 is 12 hours.
[0041] Furthermore, in some embodiments, in step S4, the freezing temperature is -10°C and the freezing time is 24~48h.
[0042] In the technical solution of this application embodiment, the sodium alginate solution is frozen and solidified, and a three-dimensional porous framework is constructed by utilizing the ice crystal template effect. This ensures that the sodium alginate layer is uniformly attached to the surface of the cotton fabric and provides structural stability for subsequent freeze-drying. Ultimately, a precursor with optimized pore structure is obtained, which is beneficial for nitrogen doping and the formation of active sites during the carbonization process.
[0043] Furthermore, in some embodiments, step S5 specifically includes the following steps: heating to 650~750℃ at a heating rate of 2~10℃ / min, and carbonizing for 1.5h.
[0044] In the technical solution of this application embodiment, a carbon-based material skeleton is obtained and a porous structure is created and controlled through high-temperature carbonization under specific conditions.
[0045] Furthermore, in some embodiments, in step S6, the nitrogen source is dicyandiamide, and the mass ratio of the nitrogen source to the aerogel precursor is 1:1 to 3:1.
[0046] In the technical solution of this application embodiment, by introducing a nitrogen source, the microporous structure of the carbon material is increased, creating more defects and adsorption active sites; and by introducing a nitrogen source during the carbonization process, on the one hand, compared with adding a nitrogen source when preparing aerogel, the addition of a nitrogen source avoids interference with the freeze-drying process of sodium alginate, and on the other hand, the gaseous nitrogen source or the active nitrogen-containing species generated by pyrolysis can fully and uniformly diffuse and penetrate into the interior of the entire carbonized material, and react directly with the active carbon sites that are being formed.
[0047] Secondly, this application provides a soft, flexible sodium alginate carbon aerogel, which is prepared by the above-mentioned method for preparing soft, flexible sodium alginate carbon aerogel.
[0048] In the technical solution of this application embodiment, the soft and flexible sodium alginate carbon aerogel has a regular three-dimensional porous structure, which is structurally stable and also has bendability.
[0049] Thirdly, this application provides an application of a soft, flexible sodium alginate carbon aerogel for dye wastewater treatment.
[0050] In the technical solution of this application embodiment, the aerogel exhibits excellent adsorption capacity and removal efficiency for methylene blue, methyl orange, and Congo red dyes; it can be conveniently used to construct filtration devices to achieve efficient treatment of dye wastewater.
[0051] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.
[0052] Example 1 This embodiment provides a method for preparing a soft, flexible sodium alginate carbon aerogel, which specifically includes the following steps: (1) 75g / m 2 Pure cotton nonwoven fabric was immersed in a 10 g / L NaOH solution, treated at 60°C for 3 hours, washed with water, and dried at 60°C to obtain pretreated cotton fabric.
[0053] (2) Dissolve sodium alginate in deionized water and stir magnetically for 2 hours to obtain a sodium alginate solution with a concentration of 2 g / 100 mL.
[0054] (3) The above sodium alginate solution was poured onto the surface of the pretreated cotton fabric and left to stand at room temperature for 12 h to obtain a composite material with a coating thickness of about 4 mm.
[0055] (4) The above composite material was frozen at -10℃ for 24 h and then dried at -40℃ for 48 h to obtain an aerogel precursor with a double-layer structure.
[0056] (5) Place the above 1g aerogel precursor in a tube furnace and add 2g of dicyandiamide to the tube furnace. Under N2 atmosphere, heat to 700℃ at a heating rate of 5℃ / min, keep warm for 1.5h, and cool naturally to obtain a double-layer carbon aerogel.
[0057] The cross-sectional SEM images of the aerogel precursor with a double-layer structure, the surface SEM image of the double-layer carbon aerogel, and the surface SEM image of the carbonized cotton nonwoven fabric prepared in this embodiment are shown below. Figure 1 The figures (a), (b), and (c) are shown in the table.
[0058] Depend on Figure 1 As shown in Figure (a), the aerogel precursor in this embodiment has a two-layer structure with completely different morphologies. As shown in Figure (b), the SA carbon aerogel layer is assembled from stacked layered sheets, and the surface is covered with a large number of macropores with diameters ranging from hundreds of nanometers to several micrometers. Some of the pores are interconnected, forming continuous channels. As shown in Figure (c), the fabric layer shows a disordered arrangement of carbonized cotton fibers, and the fibers have groove-like stripes.
[0059] Examples 2-3 and Comparative Examples 1-2 Examples 2-3 and Comparative Examples 1-2 respectively provide a method for preparing a soft and flexible sodium alginate carbon aerogel. The difference from Example 1 is that the concentration of the sodium alginate solution is different, as shown in Table 1. The other steps are roughly the same as in Example 1 and will not be repeated here.
[0060] Table 1. Concentration of sodium alginate and properties of carbon aerogels in Examples 1-3 and Comparative Examples 1-2 As shown in Table 1, with the increase of sodium alginate concentration, the specific surface area of the carbon aerogel gradually decreases, while the percentage of oxygen atoms gradually increases. The adsorption capacity of methylene blue dye after 24 hours shows a trend of first increasing and then decreasing. The adsorption capacity reaches its maximum value after 24 hours when the sodium alginate concentration is 2 g / 100 ml. Since sodium alginate is the only source of oxygen active sites in the carbon aerogel, its concentration increases directly, leading to a significant increase in the percentage of oxygen-containing functional groups (such as -COOH, -OH) on the surface of the carbonized material. However, excessively high sodium alginate solution concentrations result in an overly dense precursor gel network, clogging and reducing mesopores and micropores. Ultimately, the dye adsorption performance of this bilayer carbon aerogel is a combination of pore structure and surface elements. When both the specific surface area and oxygen content are at a high level, the carbon aerogel exhibits the best adsorption performance.
[0061] Examples 4-5 and Comparative Examples 3-4 Examples 4-5 and Comparative Examples 3-4 respectively provide a method for preparing a soft and flexible sodium alginate carbon aerogel. The difference from Example 1 is that the pouring thickness of the sodium alginate solution is different, as shown in Table 2. The other steps are roughly the same as in Example 1, and will not be repeated here.
[0062] Table 2. Thickness of sodium alginate solution and properties of carbon aerogel in Examples 1, 4-5 and Comparative Examples 3-4 As shown in Table 2, with the increase of sodium alginate thickness, the specific surface area of the carbon aerogel gradually decreases, while the oxygen atom percentage gradually increases. The adsorption amount of methylene blue dye after 24 hours shows a trend of first increasing and then decreasing. The adsorption amount reaches its maximum value when the sodium alginate thickness is 4 mm. This indicates that the addition of sodium alginate is not conducive to increasing the specific surface area of the carbon aerogel. However, while the specific surface area decreases significantly, the adsorption amount after 24 hours does not decrease significantly but remains at a high level. This suggests that the methylene blue adsorption performance of the carbon aerogel is mainly determined by the surface oxygen element, and the increase of specific surface area is conducive to the exposure of surface oxygen element. Therefore, when both the specific surface area and oxygen element content are at a high level, the carbon aerogel exhibits the best adsorption performance.
[0063] Examples 6-7 and Comparative Examples 5-6 Examples 6-7 and Comparative Examples 5-6 respectively provide a method for preparing a soft and flexible sodium alginate carbon aerogel. The difference from Example 1 is that the carbonization temperature is different, as shown in Table 3. The other steps are roughly the same as in Example 1, and will not be repeated here.
[0064] Table 3 shows the carbonization temperature and properties of carbon aerogels in Examples 1, 6-7 and Comparative Examples 5-6. As shown in Table 3, the specific surface area of the carbon aerogel increases with increasing carbonization temperature. Too low a temperature (e.g., 500℃) is not conducive to complete carbonization, while too high a temperature (e.g., 1000℃) will cause the carbon aerogel to completely vaporize without any sample residue. In addition, lower temperatures are beneficial to the retention of oxygen in the sodium alginate aerogel layer. Finally, when both the specific surface area and oxygen content are at a high level, i.e., when the carbonization temperature is 700℃, the carbon aerogel exhibits the best adsorption performance.
[0065] Comparative Example 7 This comparative example provides a method for preparing a soft, flexible sodium alginate carbon aerogel. The difference from Example 1 is that the nitrogen source (dicyandiamide) is added in step (2) instead of in step (5). The other steps are roughly the same as in Example 1 and will not be repeated here.
[0066] In this comparative example, when the nitrogen source (dicyandiamide) is added in step (2), nitrogen source molecules will precipitate on the sample surface after freeze-drying, affecting the structure of the aerogel. At the same time, during the carbonization process, due to the direct etching effect of the nitrogen source on the sodium alginate aerogel, the oxygen content on the sample surface decreases significantly, thus exhibiting poor methylene blue adsorption performance.
[0067] In summary, this application provides a soft, flexible sodium alginate carbon aerogel, its preparation method, and its applications. This application uses cotton fabric as a supporting framework, pours sodium alginate solution onto its surface, freeze-dries it to form a bilayer aerogel precursor, then introduces a nitrogen source and carbonizes it at high temperature to obtain the bilayer carbon aerogel. The supporting effect of the cotton fabric layer effectively inhibits the severe shrinkage of the sodium alginate aerogel during high-temperature pyrolysis, resulting in a structurally stable and regularly shaped three-dimensional porous material. The carbonized material is flexible and processable, overcoming the brittleness of traditional carbon aerogels. The uniform loading of the sodium alginate carbon aerogel layer on the fabric surface significantly increases the number of oxygen / sodium active sites and nitrogen-doped binding sites. The synergistic effect of these two factors gives it excellent adsorption capacity and removal efficiency for methylene blue, methyl orange, and Congo red dyes. The material can be conveniently used to construct filtration devices for efficient treatment of dye wastewater.
[0068] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.
Claims
1. A method for preparing a soft, flexible sodium alginate carbon aerogel, characterized in that, Includes the following steps: S1. Immerse the cotton fabric in an alkaline solution for cleaning and then dry it to obtain a pretreated cotton fabric; S2. Dissolve sodium alginate in deionized water and stir until completely dissolved to obtain a sodium alginate solution; S3. The sodium alginate solution is uniformly poured onto the pretreated cotton fabric and allowed to stand to obtain the composite material. S4. Freeze and dry the composite material to obtain an aerogel precursor with a double-layer structure; S5. The aerogel precursor and nitrogen source are subjected to high-temperature carbonization to obtain a bilayer carbon aerogel.
2. The method for preparing the soft, flexible sodium alginate carbon aerogel according to claim 1, characterized in that, In step S1, the cotton fabric is a pure cotton nonwoven fabric.
3. The method for preparing the soft, flexible sodium alginate carbon aerogel according to claim 2, characterized in that, The weight of the cotton fabric is 40~75 g / m². 2 .
4. The method for preparing the soft, flexible sodium alginate carbon aerogel according to claim 1, characterized in that, In step S2, the concentration of the sodium alginate solution is 1~4g / 100mL.
5. The method for preparing the soft, flexible sodium alginate carbon aerogel according to claim 1, characterized in that, In step S3, the thickness of the sodium alginate solution being poured is 2-8 mm.
6. The method for preparing the soft, flexible sodium alginate carbon aerogel according to claim 1, characterized in that, In step S4, the freezing temperature is -10℃ and the freezing time is 24~48h.
7. The method for preparing the soft, flexible sodium alginate carbon aerogel according to claim 1, characterized in that, In step S5, the high-temperature carbonization specifically includes the following steps: heating to 650~750℃ at a heating rate of 2~10℃ / min, and carbonizing for 1.5h.
8. The method for preparing the soft, flexible sodium alginate carbon aerogel according to claim 1, characterized in that, In step S6, the nitrogen source is dicyandiamide, and the mass ratio of the nitrogen source to the aerogel precursor is 1:1 to 3:
1.
9. A soft, flexible sodium alginate carbon aerogel, characterized in that, The soft, flexible sodium alginate carbon aerogel was prepared using the preparation method described in any one of claims 1 to 8.
10. An application of a soft, flexible sodium alginate carbon aerogel, characterized in that, The soft, flexible sodium alginate carbon aerogel is used for dye wastewater treatment.