A porous aerogel-based composite moisture-absorbing material and a preparation method and application thereof

Abstract

The application discloses a kind of porous aerogel-based composite moisture-absorbing materials and its preparation method and application, belong to chemical and environmental technical field.The cellulose, sodium hydroxide, deionized water are mixed to obtain solution A;Methyl methacrylate sulfonic acid sodium, polyacrylamide, deionized water and N, N'-methylene bisacrylamide are mixed uniformly, then heated, ammonium persulfate is added to obtain solution B.A and B are mixed, and tetramethyl ethylenediamine is added to obtain gel precursor, which is pre-frozen, vacuum freeze-dried to obtain CSPA aerogel.CSPA-LiCl aerogel is obtained by immersing it in LiCl solution and freeze-drying again;The surface is repeatedly sprayed with pyrrole-isopropyl alcohol solution and ammonium persulfate solution in turn, and CSPA-LiCl-PPy aerogel is obtained after reaction and freeze-drying.The porous aerogel moisture-absorbing material is used for solar-driven atmospheric water collection.Compared with traditional electrically-driven fresh water collection technology, the solar desorption system significantly reduces energy consumption and operating cost, providing a low-cost, high-efficiency and environmentally friendly fresh water supply solution for arid regions.

Description

Technical Field

[0001] This invention belongs to the field of chemistry and environmental technology, specifically relating to a porous aerogel-based composite moisture-absorbing material, its preparation method, and its application. Background Technology

[0002] AWH (Air-to-Water) technology is a technique that uses hygroscopic salts and other adsorbent materials to capture moisture from the air and then uses solar energy to drive desorption and produce water. AWH requires not only high water adsorption capacity but also rapid water desorption. Therefore, a method has been proposed to prepare water collectors by loading hygroscopic salts into porous photothermal materials. Materials with porous structures, such as hydrogels, aerogels, polymer foams, and cotton fabrics, are typically chosen as candidates for AWH. Among these, porous structures composed of hydrophilic biopolymers, such as cellulose nanofibers (CNFs) aerogels, have shown great potential as multifunctional, lightweight matrices for water transport and storage due to their high aspect ratio and interconnected hydrophilic networks. While metal-organic frameworks (MOFs) stand out for their high surface area, numerous functional sites, tunable chemical properties, and structural stability, the high cost of most MOFs limits their large-scale application. Hygroscopic salt materials coordinate with and capture water molecules through ion-dipole interactions, initiating water absorption through hydration. However, this mechanism poses a challenge to cycle stability because regeneration is difficult when the dissolved salts are completely deliquescent in water, and there are risks such as hygroscopic aggregation and deliquescent leakage.

[0003] Currently, aerogels are considered promising candidate materials due to their large specific surface area, tunable porous structure, and fast adsorption rate. They can be used as carriers for hygroscopic salts to encapsulate them and improve adsorption efficiency. Cellulose aerogels, in particular, can have their structure and properties controlled through freeze-drying technology, exhibiting advantages such as large specific surface area, moderate pore size, uniform distribution, and fast adsorption rate. Furthermore, the interconnected porous structure within aerogels helps increase light reflection and scattering within the pores, thereby significantly enhancing the light absorption capacity of photothermal conversion materials loaded onto these structures.

[0004] Therefore, developing porous composite aerogels that combine high water absorption, rapid adsorption-desorption kinetics, long-term cycle stability, and environmental friendliness has become the key to advancing AWH technology. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a porous aerogel-based composite hygroscopic material, its preparation method and application. The porous composite hygroscopic material of this invention is an aerogel with excellent hygroscopic capacity, photothermal conversion efficiency and cycle stability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a porous aerogel-based composite moisture-absorbing material, comprising the following preparation steps: S1. Mix cellulose, sodium hydroxide, and deionized water to obtain solution A; S2. Mix sodium methacrylate, polyacrylamide, and deionized water evenly, then add N,N'-methylenebisacrylamide and continue mixing evenly. Then heat the mixture and add ammonium persulfate, mixing evenly again to obtain solution B. S3. Mix solutions A and B thoroughly, then add tetramethylethylenediamine and continue mixing until homogeneous to obtain a three-dimensional network gel precursor; S4. The three-dimensional network gel precursor was pre-frozen and then freeze-dried in vacuum to obtain CSPA aerogel; S5. After immersing the CSPA aerogel in LiCl solution, it is pre-frozen and then freeze-dried under vacuum to obtain CSPA-LiCl aerogel; S6. The surface of CSPA-LiCl aerogel is repeatedly sprayed with a mixture of pyrrole-isopropanol and ammonium persulfate solution, then reacted, and then pre-frozen and vacuum freeze-dried to obtain CSPA-LiCl-PPy aerogel.

[0007] Preferably, the method for preparing cellulose in S1 is as follows: selectively remove some hemicellulose from 80-100 mesh wood powder with sodium hydroxide solution; subsequently add sodium chlorite-acetic acid mixture to remove lignin; wash with deionized water until neutral, then vacuum filter and dry in a vacuum drying oven to constant weight.

[0008] Preferably, the mass ratio of cellulose, sodium hydroxide, and deionized water in S1 is (1-3):(0.5-1.5):(45-50), and more preferably 2:1:47.

[0009] Preferably, the mass ratio of sodium methacrylate sulfonate, polyacrylamide, deionized water, N,N'-methylenebisacrylamide, and ammonium persulfate in S2 is (2~4):(0.5~1.5):45:(0.1~0.3):(0.05~0.2).

[0010] Preferably, the heating temperature in S2 is 35±0.5 ℃.

[0011] Preferably, the volume ratio of solution A to solution B in S3 is (0.5-1.5):(0.5-1.5), and more preferably 1:1.

[0012] Preferably, the volume ratio of tetramethylethylenediamine in S3 to the mixed system is (0.03~0.05):100.

[0013] Preferably, the pyrrole-isopropanol mixture in S6 is prepared by mixing pyrrole, isopropanol, and phytic acid solution evenly. The volume ratio of the pyrrole, isopropanol, and phytic acid solution is (0.8~1.0):(4~6):(1.5~2.5). The concentration of the phytic acid solution is 50 wt%.

[0014] Preferably, the concentration of the ammonium persulfate solution in S6 is 4-6 wt%.

[0015] Preferably, the coating is applied repeatedly 3-4 times in step S6.

[0016] Preferably, the pre-freezing temperature in S4-S6 is -15~-25℃; and the time is 12-24h.

[0017] The present invention also provides a porous aerogel-based composite moisture-absorbing material prepared by the above-described preparation method.

[0018] This invention also provides the application of the above-mentioned porous aerogel-based composite moisture-absorbing material in atmospheric water collection.

[0019] The porous aerogel hygroscopic material of this invention can be used for rapid adsorption of atmospheric water and rapid desorption under solar energy. In application, the porous aerogel hygroscopic material is placed in a constant temperature and humidity chamber to adsorb atmospheric water. After adsorption is completed, the hygroscopic material is placed in a sealed container and placed under a xenon lamp light source to simulate sunlight. After being heated by the solar light source, the adsorbed water evaporates to produce water vapor. After the water vapor condenses, the liquid water is collected in a glass bottle.

[0020] It contains at least the following beneficial technical effects: (1) The reaction system described in this invention is simple, uses agricultural and forestry waste as raw materials, and is inexpensive, thus reducing the cost of material preparation. Compared with traditional methods, this invention aims to provide a low-cost, highly hygroscopic method that can be coupled with renewable energy solar energy to achieve rapid desorption and water collection, thereby achieving efficient freshwater production.

[0021] (2) The present invention prepares a cellulose-based porous composite CSPA-LiCl-PPy aerogel material with high hygroscopicity and no obvious leakage by simply loading LiCl into CSPA aerogel with a porous structure and alternately spraying a photothermal conversion material polypyrrole coating on the surface.

[0022] (3) The moisture-absorbing material of the present invention has a stable pore structure, strong hydrophilicity, and efficient water vapor transport channels. In arid (30% RH) and humid (90% RH) regions, the water absorption capacity of the adsorbent is 0.685 g·g and 2.525 g·g, respectively. -1This material maintains high moisture absorption performance over a wide humidity range.

[0023] (4) The cellulose-based porous aerogel hygroscopic material prepared by this invention maintains stable performance in the cyclic adsorption-desorption test, indicating that it has good cyclic durability and long-term reliability. It can be applied to atmospheric water collection under different climate and humidity conditions.

[0024] The porous aerogel hygroscopic material of this invention is used for solar-driven atmospheric water collection. Compared with traditional electric-driven freshwater collection technology, the solar desorption system significantly reduces energy consumption and operating costs, providing a low-cost, high-efficiency, and environmentally friendly freshwater supply solution for arid regions. Attached Figure Description

[0025] Figure 1 These are scanning electron microscope (SEM) images of the porous aerogel in Example 1; where a is an internal image of the CSPA aerogel; b and c are internal images and magnified SEM images of the CSPA-LiCl aerogel; d is an internal SEM image of the CSPA-LiCl-PPY aerogel; e and f are surface SEM images and magnified images of the CSPA-LiCl-PPY aerogel; and g is an EDS elemental mapping image of the CSPA-LiCl-PPY aerogel.

[0026] Figure 2 This is a water contact angle diagram of the CSPA-LiCl-PPy porous aerogel in Example 1.

[0027] Figure 3 The moisture absorption properties of each CSPA-LiCl-PPy porous aerogel in Examples 1-4 are shown.

[0028] Figure 4 The moisture absorption properties of the CSPA-LiCl-PPy porous aerogel in Example 3 under different relative humidity conditions are shown.

[0029] Figure 5 The graph shows the desorption rate of the CSPA-LiCl-PPy porous aerogel in Example 3 under different light intensities.

[0030] Figure 6 The graph shows the moisture absorption properties of the porous aerogels in Comparative Examples 1-2 at 90% RH.

[0031] Figure 7 The diagram shows the actual water collection volume of the CSPA-LiCl-PPy porous aerogel in Example 3 during indoor simulated solar water collection. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0036] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0037] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0038] Unless otherwise specified, all raw materials or instruments used in the following embodiments of the present invention are commercially available.

[0039] raw material: Preparation method of cellulose powder: After removing the outer bark of wood, it is mechanically ground into wood flour and sieved through an 80-mesh standard sieve to control particle size uniformity. An 8 wt% NaOH solution is prepared, and the wood flour is placed in a beaker containing NaOH. The mixture is boiled in a 90℃ water bath for 12 h to selectively remove some hemicellulose. After removal, the mixture is repeatedly washed with deionized water. Then, a 2 wt% NaClO2 solution is prepared, and the pH is adjusted to 4.6 with acetic acid. The hemicellulose-removed wood flour is placed in a beaker containing NaClO2 and boiled in an 80℃ water bath for 12 h to remove lignin, with the solution changed every 4 h. After repeated washing with deionized water until the filtrate is neutral, the solid phase is separated by vacuum filtration and dried in a vacuum drying oven to constant weight, finally obtaining cellulose powder for later use.

[0040] Example 1 This invention provides an aerogel-based composite moisture-absorbing material and its preparation method, comprising the following steps: (1) Preparation of CSPA porous aerogel: Weigh 2 g of cellulose and 1 g of sodium hydroxide, add 47 mL of deionized water, place in a 60 ℃ constant temperature water bath, stir in the water bath for 2 h until the cellulose is completely dissolved and a homogeneous and stable cellulose suspension is formed, which is labeled as solution A. In a separate clean beaker, add 3 g sodium methacrylate sulfonate (SMAS), 1 g polyacrylamide (PAM), and 45 mL deionized water. Stir at 25 °C for 1 h to ensure complete polymer dissolution. Then add 0.3 g N,N'-methylenebisacrylamide (MBA, crosslinking agent) and continue stirring for 1 h to ensure uniform dispersion. After raising the system temperature to 35 °C, add 0.1 g ammonium persulfate (APS, free radical initiator) and stir rapidly with a magnetic stirrer for 10 min to initiate the prepolymerization reaction, obtaining a homogeneous and viscous precursor solution, labeled as solution B. The prepared solution A was slowly injected into solution B, and the mixture was stirred continuously for 1 h to ensure thorough mixing of the two phases. Subsequently, 40 μL of tetramethylethylenediamine (TEMED, catalyst) was added to the mixture, and stirring was continued for 3 h to promote free radical polymerization and cross-linking reactions, forming a three-dimensional network gel precursor. The above-mentioned gel precursor was slowly poured into a custom mold and pre-frozen in a -20°C freezer for 12 h to allow the water inside the gel to fully crystallize. Then it was transferred to a freeze dryer and freeze-dried under vacuum for 36 h to sublimate and remove the internal ice crystals, finally obtaining CSPA aerogel with a three-dimensional porous structure.

[0041] (2) Preparation of CSPA-LiCl porous aerogel: The obtained CSPA aerogel was immersed in a 5 wt% LiCl solution for 12 h and pre-frozen in a -20 ℃ freezer for 12 h to allow sufficient crystallization of water inside the gel. Then it was transferred to a freeze dryer and freeze-dried under vacuum for 24 h to obtain a LiCl-loaded hygroscopic aerogel.

[0042] (3) Preparation of CSPA-LiCl-PPy porous aerogel: 0.274 g of ammonium persulfate was dissolved in 5 ml of distilled water, and this was designated as the first solution. 0.84 ml of freshly distilled pyrrole was mixed with 5 ml of isopropanol, and then 1.8 ml of phytic acid solution (50 wt%) was added, and this was designated as the second solution. The second and first solutions were sprayed alternately four times, reacting at room temperature for 2 min until the entire surface of the CSPA-LiCl aerogel turned dark black. Finally, the aerogel was pre-frozen for 12 h and then placed in a freeze dryer for another 24 h to obtain the CSPA-LiCl-PPy aerogel.

[0043] Example 2 The preparation method of this embodiment is the same as that of Example 1, except that the concentration of LiCl solution in step (2) is 10 wt%.

[0044] Example 3 The preparation method of this embodiment is the same as that of Example 1, except that the concentration of LiCl solution in step (2) is 15 wt%.

[0045] Example 4 The preparation method of this embodiment is the same as that of Example 1, except that the concentration of LiCl solution in step (2) is 20 wt%.

[0046] Example 5 This invention provides an aerogel-based composite moisture-absorbing material and its preparation method, comprising the following steps: (1) Preparation of CSPA porous aerogel: Weigh 1 g of cellulose and 0.5 g of sodium hydroxide, add 50 mL of deionized water, place in a 60 ℃ constant temperature water bath, stir in the water bath for 2 h until the cellulose is completely dissolved and a homogeneous and stable cellulose suspension is formed, which is labeled as solution A. In a separate clean beaker, add 2 g of sodium methacrylate sulfonate (SMAS), 0.5 g of polyacrylamide (PAM), and 45 mL of deionized water. Stir at 25 °C for 1 h to ensure complete polymer dissolution. Then add 0.1 g of N,N'-methylenebisacrylamide (MBA, crosslinking agent) and continue stirring for 1 h to ensure uniform dispersion. After raising the system temperature to 35 °C, add 0.05 g of ammonium persulfate (APS, free radical initiator) and stir rapidly with a magnetic stirrer for 10 min to initiate the prepolymerization reaction, obtaining a homogeneous and viscous precursor solution, labeled as solution B. The prepared solution A was slowly injected into solution B, and the mixture was stirred continuously for 1 h to ensure thorough mixing of the two phases. Then, 30 μL of tetramethylethylenediamine (TEMED, catalyst) was added to the mixture, and stirring was continued for 3 h to promote free radical polymerization and cross-linking reactions, forming a three-dimensional network gel precursor. The above-mentioned gel precursor was slowly poured into a custom mold and pre-frozen in a -20°C freezer for 12 h to allow the water inside the gel to fully crystallize. Then it was transferred to a freeze dryer and freeze-dried under vacuum for 36 h to sublimate and remove the internal ice crystals, finally obtaining CSPA aerogel with a three-dimensional porous structure.

[0047] (2) Preparation of CSPA-LiCl porous aerogel: The obtained CSPA aerogel was immersed in a 5 wt% LiCl solution for 12 h and pre-frozen in a -20 ℃ freezer for 12 h to allow sufficient crystallization of water inside the gel. Then it was transferred to a freeze dryer and freeze-dried under vacuum for 24 h to obtain a LiCl-loaded hygroscopic aerogel.

[0048] (3) Preparation of CSPA-LiCl-PPy porous aerogel: 0.2 g of ammonium persulfate was dissolved in 5 ml of distilled water, and this was designated as the first solution. 0.8 ml of freshly distilled pyrrole was mixed with 4 ml of isopropanol, and then 1.5 ml of phytic acid solution (50 wt%) was added, and this was designated as the second solution. The second and first solutions were sprayed alternately four times, and the reaction was allowed to proceed at room temperature for 2 min until the entire surface of the CSPA-LiCl aerogel turned dark black. Finally, the aerogel was pre-frozen for 12 h and then placed in a freeze dryer for another 24 h to obtain the CSPA-LiCl-PPy aerogel.

[0049] Example 6 This invention provides an aerogel-based composite moisture-absorbing material and its preparation method, comprising the following steps: (1) Preparation of CSPA porous aerogel: Weigh 3 g of cellulose and 1.5 g of sodium hydroxide, add 45 mL of deionized water, place in a 60 ℃ constant temperature water bath, stir in the water bath for 2 h until the cellulose is completely dissolved and a homogeneous and stable cellulose suspension is formed, which is labeled as solution A. In a separate clean beaker, add 4 g of sodium methacrylate sulfonate (SMAS), 1.5 g of polyacrylamide (PAM), and 45 mL of deionized water. Stir at 25 °C for 1 h to ensure complete polymer dissolution. Then add 0.3 g of N,N'-methylenebisacrylamide (MBA, crosslinking agent) and continue stirring for 1 h to ensure uniform dispersion. After raising the system temperature to 35 °C, add 0.2 g of ammonium persulfate (APS, free radical initiator) and stir rapidly with a magnetic stirrer for 10 min to initiate the prepolymerization reaction, obtaining a homogeneous and viscous precursor solution, labeled as solution B. The prepared solution A was slowly injected into solution B, and the mixture was stirred continuously for 1 h to ensure thorough mixing of the two phases. Then, 50 μL of tetramethylethylenediamine (TEMED, catalyst) was added to the mixture, and stirring was continued for 3 h to promote free radical polymerization and cross-linking reactions, forming a three-dimensional network gel precursor. The above-mentioned gel precursor was slowly poured into a custom mold and pre-frozen in a -20°C freezer for 12 h to allow the water inside the gel to fully crystallize. Then it was transferred to a freeze dryer and freeze-dried under vacuum for 36 h to sublimate and remove the internal ice crystals, finally obtaining CSPA aerogel with a three-dimensional porous structure.

[0050] (2) Preparation of CSPA-LiCl porous aerogel: The obtained CSPA aerogel was immersed in a 5 wt% LiCl solution for 12 h and pre-frozen in a -20 ℃ freezer for 12 h to allow sufficient crystallization of water inside the gel. Then it was transferred to a freeze dryer and freeze-dried under vacuum for 24 h to obtain a LiCl-loaded hygroscopic aerogel.

[0051] (3) Preparation of CSPA-LiCl-PPy porous aerogel: 0.3 g of ammonium persulfate was dissolved in 5 ml of distilled water, and this was designated as the first solution. 1.0 ml of freshly distilled pyrrole was mixed with 6 ml of isopropanol, and then 2.5 ml of phytic acid solution (50 wt%) was added, and this was designated as the second solution. The second and first solutions were sprayed alternately four times, reacting at room temperature for 2 min until the entire surface of the CSPA-LiCl aerogel turned dark black. Finally, the aerogel was pre-frozen for 12 h and then placed in a freeze dryer for another 24 h to obtain the CSPA-LiCl-PPy aerogel.

[0052] Comparative Example 1 The preparation method of this comparative example is the same as that of Example 3, except that in step (2), LiCl solution is not used and only deionized water is used for soaking.

[0053] Comparative Example 2 The preparation method of this comparative example is the same as that of Example 3, except that in step (3), the second solution and the first solution are sprayed alternately once.

[0054] Experimental Example 1 The porous aerogel of Example 1 was tested: The CSPA porous aerogel exhibits an interconnected open macroporous network. Figure 1 (a) The presence of these larger pores, ranging in size from hundreds to thousands, acts as conduits, effectively transporting water vapor into the aerogel. This morphological analysis confirms the successful synthesis of a hygroscopic gel exhibiting a multilayered, interconnected porous network that not only enhances rapid water vapor transport but also supports efficient internal water diffusion.

[0055] During ion exchange, excess LiCl appears on the pore walls, forming nanoparticles. Figure 1 (bc). The porous structure of CSPA aerogel gives it a larger surface area, which is beneficial for the adhesion of abundant LiCl. Some LiCl particles aggregate into flakes, which may further accelerate the moisture absorption of the composite material.

[0056] Alternating spraying of PPy only changes the roughness of the hole walls, without affecting the morphology and structure of the holes. Figure 1 (d). The aerogel pore channels contain uniformly distributed polypyrrole particles, and PPy exhibits a typical cauliflower-like appearance. Figure 1 in ef), Figure 1 Image g is a scanning electron microscope (SEM) image of the aerogel surface, showing the formation of a three-dimensional nucleated PPy polymer under polymerization conditions, which enhances the desorption rate. Energy dispersive spectroscopy (EDS) analysis is shown below. Figure 1 As shown in Figure g, the uniform distribution of all components, particularly LiCl, within the CSPA-LiCl-PPy matrix is ​​confirmed. This uniformity is crucial for reducing localized heat loss and enhancing adsorption kinetics by ensuring consistent interactions between the materials. The dynamic contact angle of CSPA-LiCl-PPy exhibits excellent hydrophilicity, which allows the surface hygroscopic components to wet the matrix after capturing water from the air. During adsorption, the adsorbed water is transported from the surface to the interior of the aerogel for storage. Figure 2 ).

[0057] Experiment Example 2 A light intensity of 1 sun refers to a light spectrum of AM 1.5 g and a total power density of 1 kilowatt per square meter (kW / m²).2 Lighting conditions. First, the samples from Examples 1-4 were dried in an oven at 100°C for 12 h to remove all moisture. The adsorption kinetics of the dried samples under different humidity levels (RHs) were determined using a constant temperature and humidity chamber. After reaching the set temperature (25°C) and RHs (30%, 50%, 70%, 90%), with temperature and RH accuracy of ±2°C and ±2%, respectively, the dried samples were placed in a constant temperature and humidity chamber for 10 h, and mass changes were recorded every h. Subsequently, the wet samples were placed in a forced-air drying oven at 70°C for desorption experiments. In the solar-driven water desorption experiment, the samples were exposed to a xenon lamp simulating 0.5, 1.0, and 1.5 kW / m². 2 The solar intensity. Calculate the evaporation rate of the CSPA-LiCl-PPy aerogel based on the reference mass change.

[0058] Under conditions of 90% RH and 25℃, the adsorption capacities of the aerogel were 1.921, 2.294, 2.525, and 1.752 g·g⁻¹ when the LiCl concentrations were 5 wt%, 10 wt%, 15 wt%, and 20 wt%, respectively. -1 .like Figure 3 As shown, the adsorbed water capacity did not increase with increasing LiCl loading. At 90% relative humidity, the CSPA-LiCl-PPy aerogel treated with 15 wt% LiCl solution exhibited the highest adsorption capacity, reaching 2.525 g·g⁻¹ after 10 h. -1 .

[0059] The CSPA-LiCl-PPy aerogel prepared in Example 3 had water absorption capacities of 0.0898, 0.1616, 0.2986, and 0.773 g / h at relative humidity of 30%, 50%, 70%, and 90%, respectively. -1 This indicates that it has a high adsorption rate ( Figure 4 Under 90% RH conditions, the maximum water absorption of CSPA-LiCl-PPy aerogel after 10 h was 2.525 g·g⁻¹. -1 Even at a relative humidity of 30%, the water absorption of CSPA-LiCl-PPy aerogel still reaches 0.685 g·g. -1 This indicates that CSPA-LiCl-PPy aerogel exhibits excellent AWH performance over a wide humidity range.

[0060] At 0.5, 1.0 and 1.5 kW / m 2 Under simulated solar radiation, the desorption rates of CSPA-LiCl-PPy aerogel in the first 60 min were 52.34%, 72.62%, and 84.48%, respectively. Figure 5 Furthermore, the times required for desorption water to reach equilibrium were 120, 100, and 75 minutes, respectively. (At 0.5 kW / m³) 2 Under simulated solar radiation, CSPA-LiCl-PPy aerogel can still desorb 80% of the water within 120 min. Moisture content is another important factor affecting the desorption rate.

[0061] Depend on Figure 6 As shown, in Comparative Example 1, the moisture absorption capacity of the unmodified CSPA aerogel reached 1.069 g / g after 10 hours of moisture absorption at 90% RH. In Comparative Example 2, after loading LiCl hygroscopic salts into the CSPA aerogel, both the moisture absorption capacity and absorption rate of the material were significantly improved, with the 10-hour moisture absorption capacity increasing from 1.069 g / g for pure CSPA to 2.4 g / g, verifying the core role of LiCl in atmospheric water collection in cellulose-based aerogels. The fewer spraying cycles in Comparative Example 2 resulted in uneven photothermal conversion material on the surface, which only affected subsequent desorption tests, causing a decrease in the desorption rate.

[0062] To verify the indoor water collection performance of CSPA-LiCl-PPy, an indoor AWH (Ambient Air Heating) device was designed for this experiment. Water was collected in a laboratory during the northern winter. The collection device was turned on at night, collecting atmospheric moisture from 19:00 to 9:00. During the day, the device was sealed and placed under a xenon lamp light source to simulate sunlight (1 kW·m²). -2 Water was released from 9:00 AM to 7:00 PM. When the collection device was exposed to sunlight during the day, the captured water was gradually released as water vapor due to solar heating of the CSPA-LiCl-PPy aerogel. The released water vapor condensed into water mist in the low-temperature region, then evolved into large water droplets, which were collected to produce fresh water. Ultimately, 6.15, 6.47, 6.21, and 6.71 g of liquid water were successfully collected daily. Figure 7 The calculated water production rates of CSPA-LiCl-PPy were 1.22, 1.27, 1.18, and 1.35 g·g⁻¹, respectively. -1 The average daily water yield reaches 1.26 g·g -1 .

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a porous aerogel-based composite moisture-absorbing material, characterized in that, The preparation steps include the following: S1. Mix cellulose, sodium hydroxide, and deionized water to obtain solution A; S2. Mix sodium methacrylate, polyacrylamide, and deionized water evenly, then add N,N'-methylenebisacrylamide and continue mixing evenly. Then heat the mixture and add ammonium persulfate, mixing evenly again to obtain solution B. S3. Mix solutions A and B thoroughly, then add tetramethylethylenediamine and continue mixing until homogeneous to obtain a three-dimensional network gel precursor; S4. The three-dimensional network gel precursor was pre-frozen and then freeze-dried in vacuum to obtain CSPA aerogel; S5. After immersing the CSPA aerogel in LiCl solution, it is pre-frozen and then freeze-dried under vacuum to obtain CSPA-LiCl aerogel; S6. The surface of CSPA-LiCl aerogel is repeatedly sprayed with a mixture of pyrrole-isopropanol and ammonium persulfate solution, then reacted, and then pre-frozen and vacuum freeze-dried to obtain CSPA-LiCl-PPy aerogel. The method for preparing cellulose in S1 is as follows: selectively remove some hemicellulose from 80-100 mesh wood powder with sodium hydroxide solution; subsequently add sodium chlorite-acetic acid mixture to remove lignin; wash with deionized water until neutral, then vacuum filter and dry in a vacuum drying oven to constant weight.

2. The preparation method according to claim 1, characterized in that, The mass ratio of cellulose, sodium hydroxide, and deionized water in S1 is (1-3):(0.5-1.5):(45-50).

3. The preparation method according to claim 1, characterized in that, The mass ratio of sodium methacrylate sulfonate, polyacrylamide, deionized water, N,N'-methylenebisacrylamide, and ammonium persulfate in S2 is (2~4):(0.5~1.5):45:(0.1~0.3):(0.05~0.2).

4. The preparation method according to claim 1, characterized in that, The volume ratio of solution A to solution B in S3 is (0.5-1.5):(0.5-1.5).

5. The preparation method according to claim 1, characterized in that, The volume ratio of tetramethylethylenediamine in S3 to the mixed system is (0.03~0.05):

100.

6. The preparation method according to claim 1, characterized in that, The concentration of LiCl solution in S5 is 5-20 wt%.

7. The preparation method according to claim 1, characterized in that, The preparation method of the pyrrole-isopropanol mixture in S6 is as follows: pyrrole, isopropanol, and phytic acid solution are mixed evenly to obtain the mixture. The volume ratio of the pyrrole, isopropanol, and phytic acid solution is (0.8~1.0):(4~6):(1.5~2.5). The concentration of the phytic acid solution is 50 wt%.

8. The preparation method according to claim 1, characterized in that, The concentration of ammonium persulfate solution in S6 is 4~6 wt%.

9. The porous aerogel-based composite moisture-absorbing material prepared by the preparation method according to any one of claims 1-8.

10. The application of the porous aerogel-based composite moisture-absorbing material according to claim 9 in atmospheric water collection.

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