A porous carbon-enhanced gradient-porosity composite aerogel material and a method of making the same

Abstract

The application discloses a kind of porous carbon enhanced gradient pore composite aerogel material and preparation method thereof, belong to functional polymer aerogel material preparation technical field.Based on porous carbon enhanced gradient pore composite aerogel material, its inside has the pore size distribution of gradient change along specific direction, corresponding gradient capillary force field will be generated, and there is synergistic effect between different pore size range, beneficial to the rapid adsorption and diffusion of water molecules;At the same time, after introducing porous carbon composite material, its photothermal performance is enhanced, and the diversity of its application scene is greatly enriched.The application induces and regulates the diffusion dynamics of water molecules by its gradient pore structure and excellent photothermal performance of material, and the production process is simple, environment-friendly, and is expected to be widely used in the field of seawater desalination and the like.

Description

Technical Field

[0001] This invention relates to the field of functional material composite aerogel material preparation technology, and in particular to a porous carbon-reinforced gradient pore composite aerogel material and its preparation method. Background Technology

[0002] Traditional seawater desalination technologies, such as reverse osmosis and multi-stage flash evaporation, generally suffer from high energy consumption, huge infrastructure investments, and potential secondary environmental pollution. Therefore, developing new desalination technologies that are low-energy, low-cost, and environmentally friendly is imperative. Solar-driven interfacial water evaporation technology has emerged to address this need. By placing photothermal materials at the water-air interface, it achieves localized solar thermal conversion and utilization, heating only the surface water rather than the entire water body. This significantly improves photothermal conversion efficiency and evaporation rate, providing a highly promising solution for sustainable seawater desalination.

[0003] Among numerous photothermal materials, aerogels, with their unique three-dimensional porous network structure, exhibit enormous application potential. Their characteristics include:

[0004] 1. Extremely low thermal conductivity: Aerogels possess extremely high porosity (typically exceeding 90%) and a nanoscale three-dimensional network framework, resulting in extremely low thermal conductivity. This excellent thermal insulation property effectively suppresses the diffusion and loss of generated heat energy into the bulk water, thereby achieving heat localization and concentrating almost all energy at the evaporation interface, significantly improving energy utilization efficiency.

[0005] 2. Excellent porous structure and water transport capacity: The interconnected channels within the aerogel can spontaneously and continuously pump water from the bottom to the evaporation interface through powerful capillary action, ensuring the continuity of steam generation. At the same time, these channels also provide an efficient escape path for the generated water vapor.

[0006] 3. Functionalizable structural platform: The low density, high specific surface area, and tunable chemical properties of aerogels make them an ideal matrix for loading various nano-photothermal fillers, providing a broad platform for constructing multifunctional composite materials.

[0007] The application of aerogels in solar-powered seawater desalination aims to construct an ideal evaporator integrating efficient photothermal conversion, rapid water transport, excellent thermal management, and steam escape. However, to achieve its efficient, stable, and long-term industrial application, in-depth optimization is still needed in two key dimensions: enhancing its composite performance by combining it with other energy sources and improving its structure to improve performance.

[0008] Firstly, regarding material selection, carbon-based materials are embedded in the chitosan aerogel framework to improve photothermal performance. Structurally, an ideal evaporator needs to simultaneously meet the requirements of rapid water supply, efficient evaporation, and smooth steam escape. A gradient structure, with continuously varying pore sizes from bottom to top, precisely controls water transport and steam generation. ① Bottom large-pore region: Serving as the "main water supply channel," it achieves rapid extraction of water from the bulk material through a low capillary barrier, ensuring a sufficient water supply. ② Top small-pore region: Serving as the "active evaporation layer," its stronger capillary force confines water within narrower channels, forming an extremely thin water film. This not only increases the evaporation area but also reduces the phase transition enthalpy of water evaporation, thus significantly improving the evaporation rate. ③ Intermediate transition region: This achieves a smooth transition from "high-speed supply" to "efficient evaporation" and acts as a barrier to suppress downward heat dissipation.

[0009] This collaborative design, which combines a powerful heat source provided by carbon materials with a gradient pore structure to optimize quality and heat management, has created a high-performance interfacial evaporation system that is particularly suitable for high-salinity seawater desalination scenarios, providing a powerful technological path for achieving solar-driven sustainable water resource acquisition. Summary of the Invention

[0010] This invention aims to provide a functionalized seawater desalination aerogel material and its preparation method, overcoming the limitations of traditional aerogel materials such as low water vapor transport efficiency and limited utilization of solar energy and other energy sources in the environment. This innovative gradient-pore aerogel composite material controls the freezing point of the mixture by altering the water-alcohol ratio in the matrix solution, followed by freeze-drying to obtain an aerogel with a gradient pore structure. The gradient pore structure generates a corresponding gradient capillary force field during water vapor adsorption, resulting in a significant synergistic enhancement effect on the directional migration and local enrichment of water during evaporation. Furthermore, the introduction of porous carbon composite materials overcomes the poor photothermal performance of previous materials, promoting their application in complex environments.

[0011] The method for preparing a porous carbon-reinforced gradient pore composite aerogel material according to the present invention specifically includes the following steps:

[0012] S1. Mix porous carbon with deionized water and sonicate to obtain a porous carbon suspension.

[0013] S2. The pyrrole polymer monomer solution and the sodium p-styrene sulfonate polymer monomer solution are added to the porous carbon suspension and mixed evenly. When adding sodium p-styrene sulfonate, acidification treatment is required. Then, ferric chloride solution is used to initiate polymerization to obtain a composite solution. After washing, centrifuging, freeze-drying and grinding, composite powders of porous carbon and polypyrrole PPY (PPY@MC) and porous carbon and polystyrene sulfonate (PSS) (PSS@MC) are obtained respectively.

[0014] S3. Add chitosan, hydrochloric acid solution and deionized water to a beaker in sequence, stir and mix, and sonicate to obtain chitosan hydrogel matrix solution;

[0015] S4. The PPY@MC prepared in step S2, the chitosan hydrogel matrix solution prepared in step S3, and deionized water are sequentially added to a beaker for dispersion and mixing to obtain a PPY@MC precursor solution, which is then crosslinked to form the first prepolymer layer. Next, porous carbon powder (MC), the chitosan hydrogel matrix solution prepared in step S3, tert-butanol, and deionized water are sequentially added to a beaker for dispersion and mixing to obtain a porous carbon powder precursor solution, which is added to the top of the prepolymer layer for crosslinking to form the second prepolymer layer. Finally, PSS@MC prepared in step S2, the chitosan hydrogel matrix solution prepared in step S3, tert-butanol, and deionized water are sequentially added to a beaker for dispersion and mixing to obtain a PSS@MC precursor solution, which is added to the second prepolymer layer for thermal crosslinking. After freeze-drying, a gradient pore structure aerogel composite material is obtained.

[0016] As a further improvement of the present invention, the specific conditions for ultrasound in step S1 are as follows: water bath ultrasound is performed in an ultrasound machine with ice added for 30-40 minutes; the mixing conditions in step S1 are as follows: magnetic stirring for 10-20 minutes at a speed of 500-700 rpm.

[0017] As a further improvement of the present invention, the specific conditions for mixing in step S2 are: magnetic stirring for 5-10 min at a speed of 400-500 rpm; the molar ratio of polymer monomer: ferric chloride: porous carbon in step S2 is 1:1:1-4; the acidification treatment in step S2 involves adding a 5% hydrochloric acid solution; the specific conditions for initiating polymerization in step S2 are: magnetic stirring in an ice-water bath at a speed of 500-700 rpm for 6-8 h; the washing in step S2 uses deionized water and anhydrous ethanol as solvents, and the washing is performed 5-6 times; the centrifugation in step S2 is performed at a speed of 9990 rpm for 10-15 min; the freeze-drying in step S2 is performed at a temperature of -60 ℃ to -55 ℃, a pressure of 10-20 Pa, and a drying time of 36-48 h; and the grinding in step S2 is performed in an agate mortar for 30-60 min.

[0018] As a further improvement of the present invention, the hydrochloric acid solution in step S3 has a mass fraction of 3%; the mass ratio of chitosan, deionized water and hydrochloric acid in the chitosan hydrogel matrix solution in step S3 is 1:44:5; the stirring and blending involved in step S3 is specifically carried out at room temperature, with a stirring speed of 500-700 rpm and a stirring time of 4-8 h; the ultrasonication is specifically carried out in a room temperature water bath with a power of 300 W and a time of 30-60 min.

[0019] As a further improvement of the present invention, in step S4, the mass ratio of chitosan hydrogel matrix solution to deionized water in the PPY@MC precursor solution is 1:1; the mass ratio of chitosan hydrogel matrix solution to tert-butanol and deionized water in the MC precursor solution is 75:118:60; the mass ratio of chitosan hydrogel matrix solution to tert-butanol and deionized water in the PSS@MC precursor solution is 25:118:10; the prepolymer in step S4 is a hydrogel in a semi-crosslinked state; the stirring and dispersion in step S4 is specifically carried out under the conditions of stirring in a homogenizer for 3-5 min at room temperature and a rotation speed of 10000-12000 rpm; the thermal crosslinking in step S4 is specifically carried out at 50-70 ℃ for 20-60 min; the freeze-drying in step S4 is specifically carried out at a temperature of -60 ℃ to -55 ℃ and a pressure of 10-20 Pa for 36-48 h.

[0020] A porous carbon-reinforced gradient pore composite aerogel material prepared according to the above method is characterized in that the bottom layer of the gradient pore composite aerogel is a PPY@MC / CS layer with a pore size of 50–100 μm; the middle layer is an MC / CS layer with a pore size of 20–50 μm; and the top layer is a PSS@MC / CS layer with a pore size of 10–20 μm.

[0021] The photothermal conversion performance of the gradient pore composite aerogel material is as follows: at an optical density of 150 mW / cm², the photothermal conversion performance is as follows. 2 Under simulated sunlight, within 240 seconds, the temperature of the PPY@MC / CS layer increased from 43 ℃ to 74.7 ℃; the temperature of the PSS@MC / CS layer increased from 45.3 ℃ to 68.8 ℃.

[0022] The prepared composite aerogel can remove Na+ from seawater. + K + Ca 2+ Mg 2+ The content decreased by 2-3 orders of magnitude.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) This invention controls the freezing point of a mixed solution of water and tert-butanol by adjusting the volume ratio of the mixed solution, thereby constructing a gradient pore size distribution in the aerogel. This gradient porous structure not only facilitates the rapid adsorption and diffusion of water molecules, but also works synergistically within different pore size ranges to improve the water vapor adsorption performance of the material under different humidity conditions.

[0025] (2) The composite aerogel material prepared by the present invention is lightweight and its mass increase will not be too large after a series of assembly; and it has a high seawater desalination effect and has a wide application prospect in the field of seawater desalination.

[0026] (3) The composite aerogel material prepared in this invention uses porous carbon material as the matrix, which gives it excellent photothermal conversion performance at a light intensity of 150 mW / cm². 2 After 240 seconds, its surface temperature exceeded 65 ℃. Attached Figure Description

[0027] Figure 1 A flowchart illustrating the preparation process of a porous carbon-reinforced gradient pore composite aerogel material;

[0028] Figure 2 Figure a shows the absorbance test results of PPY@MC / CS aerogel. Figure 2 b is the absorbance test result of MC / CS aerogel. Figure 2c is the absorbance test result of PSS@MC / CS aerogel;

[0029] Figure 3 a is a scanning electron microscope image of PPY@MC / CS aerogel. Figure 3 b is a scanning electron microscope image of MC / CS aerogel. Figure 3 c is a scanning electron microscope image of PSS@MC / CS aerogel;

[0030] Figure 4 The graph shows the BET test results of the monolayer aerogel prepared in Comparative Example 2.

[0031] Figure 5 Differential scanning calorimetry (DSC) results of a pore-adjusting mixed solution (a mixture of water and tert-butanol) used for aerogel preparation. Figure 5 a is the melt flow curve. Figure 5 b is the solidification curve).

[0032] Figure 6 a is a photograph of the aerogel synthesized in Example 1 placed on the branches and leaves of a certain plant. Figure 6 b is a photograph of the aerogel synthesized in Example 1 placed on the stamen of a flower;

[0033] Figure 7 a1-a5 represent the test results of photothermal conversion of PPY@MC / CS monolayer aerogel at 150 mW / cm². 2 Under the specified light intensity, data was recorded every 60 seconds.

[0034] Figure 7 b1-b5 represent the test results of photothermal conversion of MC / CS monolayer aerogels at 150 mW / cm². 2 Under the specified light intensity, data was recorded every 60 seconds.

[0035] Figure 7 c1-c5 represent the test results of photothermal conversion of PSS@MC / CS monolayer aerogel at 150 mW / cm². 2 Under the specified light intensity, data was recorded every 60 seconds.

[0036] Figure 7 d1-d5 represent the test results of photothermal conversion of pure chitosan monolayer aerogels at 150 mW / cm². 2 Under the specified light intensity, data was recorded every 60 seconds.

[0037] Figure 8 a is a graph showing the mass loss over time when the aerogel synthesized in Example 1 is used for seawater desalination. Figure 8b is a graph showing the ion content before and after desalination of the aerogel synthesized in Example 1 when applied to seawater desalination. Detailed Implementation

[0038] This invention provides a gradient pore composite aerogel based on porous carbon reinforcement and its preparation method. In order to make the purpose, technical solution and advantages of this invention clearer and more explicit, this invention will be further described in conjunction with specific embodiments and accompanying drawings.

[0039] Example 1

[0040] like Figure 1 As shown, a gradient pore composite aerogel based on porous carbon reinforcement of the present invention is prepared by the following steps:

[0041] Step 1: 200 mg of porous carbon was mixed with 30 ml of deionized water and sonicated for 30 min to obtain a porous carbon suspension. Then, a pyrrole monomer solution (0.333 g dissolved in 20 ml of anhydrous ethanol) was added to the porous carbon suspension, followed by a ferric chloride solution (0.81 g of anhydrous ferric chloride dissolved in 50 ml of deionized water). The mixture was stirred in an ice-water bath for 6 h to initiate polymerization. The same porous carbon suspension was prepared, and a sodium p-styrene sulfonate solution (2.062 g of sodium p-styrene sulfonate dissolved in 20 ml of deionized water) and 5% hydrochloric acid solution were added. Ferric chloride solution (1.62 g of anhydrous ferric chloride dissolved in 50 ml of deionized water) was used to initiate polymerization, and the mixture was stirred in an ice-water bath for 6 h to obtain composite solutions of porous carbon with polypyrrole and polystyrene sulfonic acid. These composite solutions were washed, centrifuged, freeze-dried, and ground to obtain powder samples.

[0042] Step 2: Add chitosan, 3% hydrochloric acid solution and deionized water to a beaker in sequence. The mass of chitosan, deionized water and hydrochloric acid are 2 g, 88 g and 10 g respectively. Stir and mix to obtain chitosan hydrogel matrix solution.

[0043] Step 3: The porous carbon polymer composite prepared in Step 1 and the chitosan hydrogel matrix solution prepared in Step 2 are sequentially added to a beaker for dispersion. The chitosan hydrogel matrix solution and deionized water were prepared with a mass of 7.5 g and 7.5 g, respectively. PPY@MC filler was added, and the mixture was stirred and dispersed. The mixture was then divided into three portions and placed in an oven for crosslinking for 20 min to obtain a prepolymer. Next, a mixed solution of the chitosan matrix solution, tert-butanol, and deionized water was prepared with a mass of 7.5 g, 1.18 g, and 6 g, respectively. MC filler was added, and the dispersed solution was divided into three portions and added to the top layer of the prepolymer. These were then placed in an oven for crosslinking. A further mixed solution of the chitosan matrix solution, tert-butanol, and deionized water was prepared with a mass of 7.5 g, 3.54 g, and 3 g, respectively. PSS@MC filler was added, and the dispersed solution was divided into three portions and added to the top layer of the prepolymer. These were then placed in an oven for crosslinking. After successful crosslinking, the mixture was frozen in a foam box using liquid nitrogen and then freeze-dried in a freeze dryer to obtain a porous carbon-reinforced gradient pore composite aerogel.

[0044] Comparative Example 1

[0045] To measure experimental data, an aerogel without fillers was prepared as Comparative Example 1, which was prepared through the following steps:

[0046] The synthesis steps for the filler and matrix are the same as steps 1 and 2 in Example 1, and will not be described in detail here.

[0047] Step 3: The porous carbon polymer composite prepared in Step 1 and the chitosan hydrogel matrix solution prepared in Step 2 were sequentially added to a beaker for dispersion. The mass of the chitosan matrix solution and deionized water were 17.5 g and 17.5 g, respectively. The dispersed solution was divided into three portions and placed in an oven for crosslinking for 20 min. After successful crosslinking, the mixture was frozen in a foam box using liquid nitrogen and then freeze-dried in a freeze dryer to obtain pure CS aerogel.

[0048] Comparative Example 2

[0049] To measure experimental data, a monolayer aerogel with a single filler was prepared as Comparative Example 2, which was prepared through the following steps:

[0050] The steps for synthesizing the filler and matrix are the same as steps 1 and 2 in Example 1, and will not be described in detail here.

[0051] Step 3: The porous carbon polymer composite prepared in Step 1 and the chitosan hydrogel matrix solution prepared in Step 2 were sequentially added to beakers for dispersion. The mass of chitosan matrix solution and deionized water were 17.5 g and 17.5 g, respectively, and filler PPY@MC was added. The dispersed solution was divided into three portions and placed in an oven for crosslinking. Then, a mixed solution of the chitosan hydrogel matrix solution and deionized water with mass of 17.5 g and 17.5 g was prepared, and filler MC was added. The dispersed solution was divided into three portions and placed in an oven for crosslinking. A mixed solution of the chitosan hydrogel matrix solution, tert-butanol, and deionized water with mass of 17.5 g and 17.5 g, respectively, was prepared, and filler PSS@MC was added. The dispersed solution was divided into three portions and placed in an oven for crosslinking. After successful crosslinking, the mixture was frozen in a foam box using liquid nitrogen and then freeze-dried in a freeze dryer to obtain three aerogels: PPY@MC / CS, MC / CS, and PSS@MC / CS.

[0052] The absorbance of three monolayer aerogels prepared in Comparative Example 2, each with fillers of PPY@MC, PSS@MC, and MC respectively, was measured under different wavelengths of light. The results are as follows: Figure 2 As shown in a, b, and c.

[0053] Figure 2 b reveals that the porous carbon material used in this invention exhibits significant light absorption capacity due to its intrinsic pure black color. After being composited with polypyrrole (PPY) and polystyrene sulfonic acid (PSS) respectively, the resulting composite materials still maintain excellent light absorption properties. Among them, PPY@MC / CS ( Figure 2 a) showed only a slight decrease in absorbance, while PSS@MC / CS ( Figure 2 c) The absorbance remained essentially unchanged. These results indicate that all three materials possess excellent light absorption properties and demonstrate significant photothermal conversion potential, showing broad application prospects in fields such as solar energy utilization, photothermal therapy, and photothermal catalysis.

[0054] The monolayer aerogel prepared in Comparative Example 2 was subjected to SEM and BET tests, and the results are as follows: Figure 3 and 4 As shown.

[0055] exist Figure 3In the scanning electron microscopy (SEM) images, it can be clearly observed that all the aerogel materials prepared in this study exhibit a well-developed three-dimensional porous network structure. This highly interconnected loose pore topology not only provides ideal interfacial conditions for the transport and contact of water molecules within the aerogel, but also significantly increases the effective specific surface area of ​​the material, thus laying a solid structural foundation for efficient water vapor adsorption. From the microstructural characteristics of the pore size distribution... Figure 3 As shown in figure a, the PPY@MC / CS aerogel sample exhibits a relatively uniform macroporous / large pore structure, with its pore size mainly distributed in the size range of 50–100 μm. Pores in this size range are conducive to the rapid diffusion of water vapor inside the material. Figure 3 The MC / CS aerogel sample in sample b exhibits a more refined hierarchical porous structure, with a pore size distribution ranging from approximately 20 to 50 μm, indicating that the mesoscopic structure of the aerogel can be effectively controlled by adjusting the process parameters. Meanwhile... Figure 3 In the PSS@MC / CS aerogel in section c, a finer microporous / mesoporous structure can be clearly observed, with the pore size further reduced to the scale of 5–10 μm. This size range is close to the characteristic scale of typical mesoporous materials, indicating that ice crystal growth behavior is significantly suppressed under this water-to-alcohol ratio, forming a more dense porous network. This systematic trend in pore size change fully demonstrates that by controlling the volume ratio of the precursor solution, the phase transition behavior of the aqueous phase during freezing can be effectively altered, thereby affecting the nucleation and growth kinetics of ice crystals. Ice crystals, as templates for forming porous structures, directly determine the pore size distribution characteristics of the final aerogel material through their size and morphology. This study achieved the regulation of ice crystal formation temperature and growth rate by precisely controlling the composition of the solution, thus constructing a pore size distribution with gradient changes along a specific direction within the aerogel.

[0056] Ultimately, we successfully prepared a layered aerogel material with a significant pore size gradient structure. This material exhibits a hierarchical pore system ranging from macropores to mesopores at the microscale. This gradient porous structure not only facilitates the rapid adsorption and diffusion of water molecules but also allows for synergistic effects across different pore size ranges, enhancing the material's water vapor adsorption performance under varying humidity conditions.

[0057] On the other hand, by performing specific surface area analysis (BET) on Comparative Example 2, Figure 4 The nitrogen adsorption data clearly reveal a gradually changing pore size distribution in the upper, middle, and lower layers of the material. This structural feature determines that a corresponding gradient capillary force field will be generated during the water vapor adsorption process. This force field is key to achieving directional migration and local enrichment of water, thus producing a significant synergistic enhancement effect on the water vapor evaporation process.

[0058] In creating the pore gradient, water and tert-butanol were selected, and their mixed solution was controlled to regulate the ice crystal formation temperature and growth rate, thereby constructing a pore size distribution exhibiting a gradient along a specific direction within the aerogel. For ease of selection of the ratio, DSC testing was performed on the mixed solution, such as... Figure 5 By comparing the freezing points, pure water, water-to-alcohol ratios of 9:1 and 7:3 were selected for pore control in the upper, middle and lower layers.

[0059] The aerogel prepared in Example 1 was physically demonstrated and its seawater desalination performance was tested. The results are as follows: Figure 6 , Figure 8 As shown; and photothermal conversion tests were performed on comparative examples 1 and 2, as shown. Figure 7 .

[0060] like Figure 6 As shown in a and b, the moisture-generating aerogel prepared in this study can be stably loaded onto the surface of plant petals and slender branches without causing structural deformation. This phenomenon directly confirms the material's extremely low density and suggests that its lightweight properties are suitable for seawater desalination. Furthermore, it can form a close conformal contact with bio-interfaces with high specific surface areas, laying the structural foundation for its subsequent functional realization. The core innovation of this material lies in its integration of "ultra-lightweight properties" with "water vapor diffusion" functionality. Its carefully designed microporous-mesoporous gradient structure endows the material with extremely light physical properties and provides ideal nanochannels and a large specific surface area for the spontaneous adsorption and directional transport of water vapor in the environment. When a humidity gradient exists, a stable proton concentration difference can be formed inside the material, thereby enabling the directional diffusion of hydrated ions within the charged channels. Based on this "lightweight purification" characteristic, this aerogel shows great application potential in the field of seawater purification. Its ultra-lightweight nature means that when applied to seawater desalination, it can float lightly on seawater, providing an essential characteristic for its application scenario. Furthermore, this material exhibits excellent cutability and modularity. Multiple independent aerogel units can be flexibly assembled without significantly increasing the system's mass.

[0061] Figure 7 The prepared composite aerogel material was revealed to possess excellent photothermal conversion properties, such as... Figure 7 (a1-a5), (b1-b5), (c1-c5), and (d1-d5) show three aerogels: PPY@MC / CS, MC / CS, and PSS@MC / CS, as well as pure CS aerogel, at 150 mW / cm². 2 Under the specified light intensity, temperature data for a set of aerogel samples were recorded every 60 seconds. Comparative Example 1, the chitosan aerogel material prepared without filler, showed almost no photothermal conversion capability. Figure 7(d1-d5) shows that after 240 s of illumination, the surface temperature of the hydrogel composite material hardly changed. Further analysis reveals that although a slight temperature increase occurred, this was mainly due to the gradual increase in temperature of the tin foil at the bottom of the sample, which facilitated heat conduction from the bottom to the aerogel surface, leading to a gradual increase in its surface temperature. In contrast, the single-filler aerogel material prepared in Comparative Example 2 exhibits excellent photothermal conversion capabilities, such as... Figure 7 As can be seen from (a1-a5), (b1-b5) and (c1-c5), under the same light intensity, the surface temperature of the three different filler aerogel materials increases from about 43 ℃ to about 70 ℃ within 240 s. After adding the three fillers, the aerogel materials have a relatively rapid heating rate and exhibit extremely good photothermal response performance.

[0062] Meanwhile, to evaluate the practical application potential of the composite aerogel in seawater desalination in Example 1, we focused on examining its desalination performance and long-term stability in simulated seawater. Figure 8 As shown in b, the salt ion concentration of the brine treated with this material can be reduced from the initial 10. 3 -10 4 The mg / L decreased sharply to 10. -1 The concentration of sulfur dioxide was reduced by two to three orders of magnitude, achieving an astonishing desalination rate of 99.9%, demonstrating its highly efficient seawater desalination capabilities. More importantly, in... Figure 8 After 1 hour of continuous purification testing, the mass loss rate in simulated seawater experiment a reached 4 kg·cm². -2 ·h -2 Its purification performance has maintained steady growth, with purification efficiency gradually increasing at a relatively high growth rate. This excellent operational stability is attributed to the robust three-dimensional network structure of the aerogel material, which effectively prevents structural collapse that may occur under osmotic pressure, thereby ensuring the continuity and reliability of the desalination process. Furthermore, its strong photothermal conversion capability makes it suitable for more diversified application scenarios, enabling the degradation and utilization of seawater resources in a green and environmentally friendly manner, thus laying a solid experimental foundation for its industrial-scale brine desalination application.

[0063] The above embodiments are only used to illustrate preferred embodiments of the present invention and do not constitute a limitation on the scope of protection of the present invention. Any modifications, equivalent substitutions, or optimizations made within the technical concept and principle framework of the present invention should be considered to fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a porous carbon-reinforced gradient pore composite aerogel material, specifically comprising the following steps: S1. Mix porous carbon with deionized water and sonicate to obtain a porous carbon suspension. S2. The pyrrole polymer monomer solution and the sodium p-styrene sulfonate polymer monomer solution are added to the porous carbon suspension and mixed evenly. Then, ferric chloride solution is used to initiate polymerization to obtain a composite solution. When adding sodium p-styrene sulfonate, acidification treatment is required. After washing, centrifuging, freeze-drying and grinding, composite powders of porous carbon and polypyrrole PPY (PPY@MC) and porous carbon and polystyrene sulfonate (PSS) (PSS@MC) are obtained respectively. S3. Add chitosan, hydrochloric acid solution and deionized water to a beaker in sequence, stir and mix, and sonicate to obtain chitosan hydrogel matrix solution; S4. The PPY@MC prepared in step S2, the chitosan hydrogel matrix solution prepared in step S3, and deionized water are sequentially added to a beaker for dispersion and mixing to obtain a PPY@MC precursor solution, which is then crosslinked to form a first prepolymer layer. Next, porous carbon powder, the chitosan hydrogel matrix solution prepared in step S3, tert-butanol, and deionized water are sequentially added to a beaker for dispersion and mixing to obtain a porous carbon powder precursor solution, which is added to the top of the first prepolymer layer for crosslinking to form a second prepolymer layer. Finally, PSS@MC prepared in step S2, the chitosan hydrogel matrix solution prepared in step S3, tert-butanol, and deionized water are sequentially added to a beaker for dispersion and mixing to obtain a PSS@MC precursor solution, which is added to the second prepolymer layer for thermal crosslinking. After freeze-drying, a gradient pore structure aerogel composite material is obtained. The method is characterized in that step S4... The mass ratio of chitosan hydrogel matrix solution to deionized water in the PPY@MC precursor solution is 1:1; the mass ratio of chitosan hydrogel matrix solution to tert-butanol and deionized water in the MC precursor solution is 75:118:60; the mass ratio of chitosan hydrogel matrix solution to tert-butanol and deionized water in the PSS@MC precursor solution is 25:118:10; the prepolymer in step S4 is a hydrogel in a semi-crosslinked state. The dispersion and mixing described in step S4 are specifically carried out under the following conditions: stirring in a homogenizer for 3-5 minutes at room temperature and a rotation speed of 10,000-12,000 rpm; the thermal crosslinking described in step S4 is carried out at 50-70 ℃ for 20-60 minutes; the freeze drying described in step S4 is carried out at a temperature of -60 ℃ to -55 ℃ and a pressure of 10-20 Pa for 36-48 hours.

2. The method for preparing a porous carbon-reinforced gradient pore composite aerogel material according to claim 1, characterized in that, The specific conditions for ultrasound in step S1 are as follows: water bath ultrasound in an ultrasound machine with ice added for 30-40 minutes; the mixing conditions in step S1 are as follows: magnetic stirring for 10-20 minutes at a speed of 500-700 rpm.

3. The method for preparing a porous carbon-reinforced gradient pore composite aerogel material according to claim 1, characterized in that, The specific mixing conditions in step S2 are: magnetic stirring for 5-10 min at a speed of 400-500 rpm; the molar ratio of polymer monomer: ferric chloride: porous carbon in step S2 is 1:1:1-4; wherein the polymer monomers are pyrrole and sodium p-styrene sulfonate; the acidification treatment in step S2 involves adding a 5% (w / w) hydrochloric acid solution; the specific conditions for initiating polymerization in step S2 are: magnetic stirring in an ice-water bath at a speed of 500-700 rpm for 6-8 h; the washing in step S2 uses deionized water and anhydrous ethanol as solvents, and the number of washing cycles is 5-6; the centrifugation in step S2 is specifically performed at a speed of 9990 rpm for 10-15 min; the freeze-drying in step S2 is specifically performed at a temperature of -60 ℃ to -55 ℃, a pressure of 10-20 Pa, and a drying time of 36-48 minutes. h; The grinding described in step S2 is specifically performed in an agate mortar for 30-60 minutes.

4. The method for preparing a porous carbon-reinforced gradient pore composite aerogel material according to claim 1, characterized in that, The hydrochloric acid solution in step S3 has a mass fraction of 3%; the mass ratio of chitosan, deionized water, and hydrochloric acid in the chitosan hydrogel matrix solution in step S3 is 1:44:5; the stirring and blending involved in step S3 is carried out at room temperature, with a stirring speed of 500-700 rpm and a stirring time of 4-8 h; the ultrasonication is carried out in a room temperature water bath with a power of 300 W and a time of 30-60 min.

5. A porous carbon-reinforced gradient pore composite aerogel material, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 4.

6. The porous carbon-reinforced gradient pore composite aerogel material according to claim 5, characterized in that, The gradient porous composite aerogel has a bottom layer of PPY@MC / CS with a pore size of 50–100 μm; a middle layer of MC / CS with a pore size of 20–50 μm; and an uppermost layer of PSS@MC / CS with a pore size of 10–20 μm.

7. The porous carbon-reinforced gradient pore composite aerogel material according to claim 5, characterized in that, The photothermal conversion performance of the gradient pore composite aerogel material is as follows: at an optical density of 150 mW / cm², the photothermal conversion performance is as follows. 2 Under simulated sunlight, within 240 seconds, the temperature of the PPY@MC / CS layer increased from 43℃ to 74.7℃; the temperature of the PSS@MC / CS layer increased from 45.3℃ to 68.8℃.

8. The porous carbon-reinforced gradient pore composite aerogel material according to claim 5, characterized in that, The prepared composite aerogel can remove Na+ from seawater. + K + Ca 2+ Mg 2+ The content decreased by 2-3 orders of magnitude.

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