Bio-based aerogel capable of realizing dual-mode efficient air water collection and preparation method of bio-based aerogel

Abstract

The invention relates to bio-based aerogel capable of realizing dual-mode efficient water collection in air and a preparation method of the bio-based aerogel. The aerogel comprises an aerogel matrix and a polypyrrole layer. The aerogel matrix has a gradient pore structure, and the pore diameter range of the gradient pore structure is 100 nm to 200 [mu] m; polypyrrole in the polypyrrole layer is loaded on the surface of the aerogel matrix and in the gradient pore structure, and the distribution thickness of the polypyrrole layer accounts for 1%-100% of the thickness of the aerogel matrix. The bio-based aerogel prepared by the embodiment of the invention can be used for carrying out extrusion type water collection, so that the problem of weather dependence existing in a solar-driven adsorption type air water collection technology is solved; the aerogel is internally provided with an internal pore structure in gradient distribution, so that efficient moisture absorption is realized; the construction of the double-layer structure after introduction of the polypyrrole layer clarifies the structure-function relationship between the double-layer structure and the adsorption-desorption performance of the air water-collecting aerogel, and provides a new principle for the development of a high-efficiency air water-collecting material.

Description

Technical Field

[0001] This disclosure relates to the field of air water collection technology, and more particularly to a bio-based aerogel capable of dual-mode high-efficiency air water collection and its preparation method. Background Technology

[0002] Air-based water harvesting technology, as a novel method for acquiring freshwater resources, has attracted widespread attention. This technology can directly extract moisture from the air and boasts advantages such as low operating costs and low energy consumption, providing a new water resource acquisition pathway that eliminates the need for traditional water sources. Among these, solar-driven air-based water harvesting systems utilize solar thermal energy, light energy, and the evaporation-condensation principle to significantly improve moisture collection and desorption efficiency. For example, CN119114021A discloses a hygroscopic gel prepared by blending and heating gluten powder, montmorillonite, and lithium chloride, which can capture moisture from the air and release it through solar-driven evaporation. CN119331305A discloses a bamboo cellulose-based aerogel loaded with lignin sulfonate, utilizing the excellent hygroscopic and light absorption properties of lignin sulfonate to achieve atmospheric water harvesting.

[0003] Solar energy, as a green, clean, and renewable energy source, can provide the heat required for desorption of aerogels through photothermal materials, driving the effective release of water from the aerogels and overcoming the traditional desorption challenges, thus laying the foundation for subsequent collection. However, the solar-driven desorption water collection mode is relatively simple and heavily reliant on weather parameters such as natural light intensity, temperature, and humidity. This leads to a significant decrease in water collection efficiency under low-light or no-light conditions (such as nighttime, cloudy days, smog, and building obstruction), severely limiting its application environment and scenarios.

[0004] Direct water collection via mechanical extrusion (Chem. Eng. J. 2024, 497, 154948) is a novel method in air-based water collection technology. By combining aerogels and moisture-absorbing materials, it can achieve rapid and portable water collection without requiring favorable solar radiation conditions. However, it has high energy consumption, stringent material and process requirements, and high manufacturing costs.

[0005] Therefore, it is necessary to improve one or more of the problems existing in the above-mentioned related technical solutions.

[0006] It should be noted that this section is intended to provide background or context for the technical solutions of this disclosure as set forth in the claims. The description herein does not constitute an admission that it is prior art simply because it is included in this section. Summary of the Invention

[0007] The purpose of this disclosure is to provide a bio-based aerogel capable of efficient air-to-water collection in two modes and a method for its preparation, thereby overcoming, to at least to some extent, one or more problems caused by limitations and defects in related technologies.

[0008] This invention first provides a bio-based aerogel capable of dual-mode, high-efficiency air-based water collection, the aerogel comprising: An aerogel matrix having a gradient pore structure with a pore size range of 100 nm to 200 μm; A polypyrrole layer, wherein the polypyrrole in the polypyrrole layer is loaded on the surface of the aerogel matrix and within the gradient pore structure, and the distributed thickness of the polypyrrole layer accounts for 1% to 100% of the thickness of the aerogel matrix.

[0009] The present invention further provides a method for preparing a bio-based aerogel capable of dual-mode high-efficiency air water collection, comprising the following steps: Step 1, Preparation of the aerogel matrix: Hydroxypropyl cellulose and anhydrous lithium chloride are added to deionized water to form a gel precursor solution. The pH of the gel precursor solution is adjusted to 7.0-9.0. Konjac mannan is added to the gel precursor solution to carry out the reaction. After the reaction is completed, the solution is transferred to a mold and then freeze-dried to obtain an aerogel matrix. Step 2, Construction of the double-layer water collection structure: The aerogel matrix is ​​placed in an aqueous solution of ferric chloride. After complete absorption, the aerogel matrix adsorbed with ferric chloride and pyrrole are placed in an oven using a vapor deposition method. Polypyrrole layer is obtained by in-situ polymerization at the location impregnated with ferric chloride solution, thus obtaining the double-layer water collection structure.

[0010] In this invention, the reaction mass ratio of hydroxypropyl cellulose and anhydrous lithium chloride is 1:(2~10).

[0011] In this invention, the reaction mass ratio of hydroxypropyl cellulose and konjac mannan is 1:(0.3~4).

[0012] In this invention, the freeze-drying process includes: freezing at -4 to -10°C for 3 hours, immersing in liquid nitrogen for 10 to 20 minutes, and then drying at -30 to -40°C for 10 to 24 hours.

[0013] In this invention, an aerogel matrix adsorbed with ferric chloride and pyrrole are placed in an oven at 40-50°C and subjected to in-situ polymerization at the location impregnated with ferric chloride solution for 20-40 minutes to obtain a polypyrrole layer.

[0014] In this invention, the thickness of the polypyrrole layer accounts for 1% to 100% of the thickness of the aerogel matrix.

[0015] In this invention, the preparation method further includes: immersing the aerogel matrix loaded with a polypyrrole layer in a phytic acid solution for 10-20 minutes, and then washing and drying it to obtain a bio-based aerogel capable of dual-mode high-efficiency air water collection.

[0016] The present invention also provides an application of a bio-based aerogel capable of dual-mode high-efficiency air water collection. The bio-based aerogel described in the above embodiments can achieve air water collection within a humidity range of 30~100%RH. It can achieve desorption of adsorbed water by using one or a combination of two modes: solar photothermal induced release and mechanical extrusion release. It can be used under both light and no-light conditions.

[0017] In this invention, the volume change range of the extrusion deformation and moisture-absorbing rebound of the bio-based aerogel is 0~95%.

[0018] The technical solution provided by this invention may include the following beneficial effects: This invention discloses a bio-based aerogel capable of dual-mode high-efficiency air water collection and its preparation method. The prepared bio-based aerogel can collect water by extrusion, solving the weather dependence problem of solar-driven adsorption air water collection technology. The aerogel has a gradient-distributed internal pore structure, thereby achieving high-efficiency moisture absorption capacity. The construction of the bilayer structure after introducing a polypyrrole layer clarifies the interaction law between the photothermal layer and the moisture-absorbing gel layer, elucidating the structure-property relationship between the bilayer structure and the adsorption-desorption performance of the air water collection aerogel, and providing a new principle for the development of high-efficiency air water collection materials. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0020] Figure 1 This illustration shows a scanning electron microscope image of the gradient pore structure of the aerogel matrix in an exemplary embodiment of this disclosure; Figure 2 Digital images of aerogel matrices with different LiCl contents in Examples 1 and 3 of this disclosure are shown; Figure 3 Show Figure 2 The air water adsorption efficiency of the aerogel matrix at 50% humidity; Figure 4 Digital images of the dual-mode water-collecting bio-based aerogels in Embodiments 4 and 5 of this disclosure are shown. Figure 5 Show Figure 4 The air water adsorption efficiency of aerogel at 60% humidity; Figure 6 Show Figure 4 The desorption efficiency of aerogel under sunlight; Figure 7 The air water adsorption efficiency of the aerogel of this disclosure under different humidity conditions is shown; Figure 8 The adsorbed water release efficiency of the aerogel of this disclosure is shown under different light conditions; Figure 9 The condensation and collection of released water vapor from the aerogel of this disclosure under natural light conditions is shown. Figure 10 Digital images of the aerogel of this disclosure after extrusion and moisture absorption and rebound are shown; Figure 11 Showing 50 cm 3 The cumulative increase in water collected during the five extrusion processes of the bio-based aerogel. Detailed Implementation

[0021] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0022] Furthermore, the accompanying drawings are merely illustrative diagrams of embodiments of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0023] This example embodiment first provides a bio-based aerogel capable of dual-mode, high-efficiency air-based water collection, comprising: an aerogel matrix and a polypyrrole layer. The aerogel matrix has a gradient pore structure with a pore size ranging from 100 nm to 200 μm; the polypyrrole in the polypyrrole layer is loaded on the surface of the aerogel matrix and within the gradient pore structure, and the distribution thickness of the polypyrrole layer accounts for 1% to 100% of the thickness of the aerogel matrix.

[0024] In this embodiment, the prepared bio-based aerogel can be used for extrusion-type water collection, solving the weather dependence problem of solar-driven adsorption-type air water collection technology; the aerogel has a gradient-distributed internal pore structure, thereby achieving high-efficiency moisture absorption capacity; the construction of the bilayer structure after introducing the polypyrrole layer clarifies the interaction law between the photothermal layer and the moisture-absorbing gel layer, elucidates the structure-property relationship between the bilayer structure and the adsorption-desorption performance of the air water collection aerogel, and provides a new principle for the development of high-efficiency air water collection materials.

[0025] This example embodiment further provides a method for preparing a bio-based aerogel capable of dual-mode, high-efficiency air-based water collection, comprising the following steps: Step 1, Preparation of the aerogel matrix: Hydroxypropyl cellulose and anhydrous lithium chloride are added to deionized water to form a gel precursor solution. The pH of the gel precursor solution is adjusted to 7.0-9.0. Konjac mannan is added to the gel precursor solution to carry out the reaction. After the reaction is completed, the solution is transferred to a mold and then freeze-dried to obtain an aerogel matrix. Step 2, Construction of the double-layer water collection structure: The aerogel matrix is ​​placed in an aqueous solution of ferric chloride. After complete absorption, the aerogel matrix adsorbed with ferric chloride and pyrrole are placed in an oven using a vapor deposition method. Polypyrrole layer is obtained by in-situ polymerization at the location impregnated with ferric chloride solution, thus obtaining the double-layer water collection structure.

[0026] The bio-based aerogel reaction system provided by this invention is simple, inexpensive, and easy to prepare. Compared with traditional methods, the prepared bio-based aerogel solves the weather dependence problem of solar-driven adsorption air water collection technology by introducing an extrusion-type water collection method.

[0027] This invention significantly improves the efficiency of air-based water collection and effectively reduces dependence on weather conditions by synergistically combining solar-driven air-based water collection technology with mechanical compression water collection. The combination enables the release of adsorbed water during the day via solar thermal stimulation, and continuous water collection at night or on cloudy days via mechanical compression, forming a highly efficient water collection cycle. This synergistic model is highly adaptable, particularly suitable for regions with large temperature differences or arid areas, and can maintain continuous and stable water collection efficiency under variable climatic conditions, thereby improving the overall energy efficiency and sustainability of the material.

[0028] This example embodiment also provides an application of a bio-based aerogel capable of dual-mode, high-efficiency air-based water collection. The bio-based aerogel in the above embodiment can effectively collect water from the air within a humidity range of 30-100% RH. It achieves desorption of adsorbed water through one or a combination of solar photothermal induced release and mechanical extrusion release modes, and can be used effectively under both light and dark conditions. The volume change range of the extrusion deformation and moisture rebound of the bio-based aerogel is 0-95%, for example, 30%, 50%, 80%, etc.

[0029] The following specific experiments and tests on the aerogels obtained from the experiments will illustrate the technical effects.

[0030] Example 1: First, add 0.1 g of hydroxypropyl cellulose and 0.6 g of anhydrous lithium chloride to 10 mL of deionized water. Stir mechanically for 5 min at room temperature and pressure. Adjust the pH of the mixed solution to 7.0-9.0 using 0.05 M sodium hydroxide solution. Then add 0.4 g of konjac mannan. After reacting for 2 min, transfer the mixture to a mold and let it stand for 15 min. Freeze in a refrigerator for 3 h, then freeze with liquid nitrogen for 15 min. After freeze-drying for 12 h, an aerogel matrix with air water adsorption properties can be obtained.

[0031] Example 2: First, 0.3 g of hydroxypropyl cellulose and 0.6 g of anhydrous lithium chloride were added to 10 mL of deionized water and mechanically stirred for 15 min at room temperature and pressure. The pH of the mixed solution was adjusted to 8.5 using 0.05 M sodium hydroxide solution. Then, 0.1 g of konjac mannan was added and reacted for 2 min. After that, the mixture was transferred to a mold and allowed to stand for 15 min. After freezing in a refrigerator for 3 h, it was frozen with liquid nitrogen for 15 min. After freeze-drying for 12 h, an aerogel matrix with a gradient pore structure that can adsorb air moisture was obtained. Figure 1 Scanning electron microscopy images of the gradient pore structure of the aerogel matrix, from Figure 1 It can be seen that its pore size distribution is 100 nm to 200 μm.

[0032] Example 3: Unlike Example 1, the LiCl content in the aerogel was adjusted to 0.2 g, 0.4 g, 0.8 g and 1.0 g. Figure 2 These are digital images of aerogel matrices with different LiCl contents from Examples 1 and 3. Figure 2 It can be seen that when the amount of LiCl added is 0.6g, the bulk structure morphology of the aerogel matrix is ​​maintained best. Figure 3 To correspond to the air water adsorption efficiency of the aerogel matrix at 50% humidity, from Figure 3It can be seen that when the amount of LiCl added is 0.6g, the aerogel matrix has the highest air water adsorption efficiency at 50% humidity.

[0033] Example 4: The aerogel matrix from Example 1 was placed in 750 μL of ferric chloride aqueous solution. After the aerogel matrix completely and freely adsorbed the ferric chloride aqueous solution, it was placed together with 3 mL of pyrrole in a forced-air drying oven and reacted at 50°C for 30 min. Then, the resulting aerogel was immersed in 30 mL of phytic acid solution and reacted for 15 min. It was then washed with ethanol and deionized water in sequence and dried to prepare a bimodal water-collecting bio-based aerogel with a polypyrrole layer accounting for 25% of the bilayer structure.

[0034] Example 5: Unlike Example 4, the volume of ferric chloride solution adsorbed on the aerogel matrix was adjusted to 100 μL, 1500 μL, 2250 μL and 4000 μL, and the amount of pyrrole was adjusted to 1 mL, 6 mL, 9 mL and 12 mL, resulting in bimodal water-collecting bio-based aerogels with a polypyrrole layer accounting for 1%, 50%, 75% and 100% of the bilayer structure. Figure 4 Digital images of the dual-mode water-collecting bio-based aerogels in Examples 4 and 5. Figure 5 To determine the air moisture adsorption efficiency of aerogel at 60% humidity. Figure 6 To determine the adsorption and desorption efficiency of aerogel under a certain solar intensity, it can be seen that the desorption efficiency is highest when the polypyrrole layer accounts for 25%. The polypyrrole layer plays a photothermal role, but it affects the hygroscopic performance and extrusion effect. Therefore, this application makes the aerogel into a double-layer structure to balance and achieve compatibility between the two modes.

[0035] Example 6: The prepared dual-mode water-collecting bio-based aerogel can adsorb water from the air and then be placed under sunlight to release the adsorbed water. Water collection in photothermal mode is achieved by condensing the released water vapor. Figure 7 The values ​​represent the air water adsorption efficiency under different humidity conditions. The higher the humidity, the higher the air water adsorption efficiency. Figure 8 To determine the adsorbed water release efficiency under different light conditions, from Figure 8 It can be seen that the greater the intensity of sunlight, the faster the adsorbed water is released. Figure 9 For the condensation and collection of water vapor released under natural light conditions, from Figure 9 It can be seen that the adsorbed water in the aerogel can be released naturally under natural light and collected by condensation on the inner wall of the collection chamber.

[0036] Example 7: The prepared dual-mode water-collecting bio-based aerogel can adsorb water from the air, and then release and collect the adsorbed water by extrusion. (50 cm) 3 The bio-based aerogel can collect 150 mL of water after 5 extrusions. Figure 10 Digital images of dual-mode water-collecting bio-based aerogel after extrusion and moisture-absorbing rebound, from Figure 10 It can be seen that the volume of the aerogel after vacuum extrusion is reduced to 25% of its original volume. After the vacuum is released, the volume of the aerogel gradually expands back to 95% of its original volume because it spontaneously absorbs moisture from the air. Figure 11 50 cm 3 The cumulative increase in water collected during the five extrusion processes of the bio-based aerogel, from Figure 11 It can be seen that 50 cm 3 The aerogel can collect nearly 150 mL of water in 5 adsorption-extrusion cycles, which is highly efficient.

[0037] It should be noted that in this application, one ray of sunlight refers to a standard solar radiation intensity, which is 1.0 kWm. -2 , Figure 8 The 0.7, 1.0, and 1.5 solar rays correspond to 0.7 kWm, respectively. -2 1.0kWm -2 and 1.5kWm -2 .

[0038] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A bio-based aerogel capable of dual-mode, high-efficiency air-based water collection, characterized in that, The aerogel comprises: An aerogel matrix having a gradient pore structure with a pore size range of 100 nm to 200 μm; A polypyrrole layer, wherein the polypyrrole in the polypyrrole layer is loaded on the surface of the aerogel matrix and within the gradient pore structure, and the distributed thickness of the polypyrrole layer accounts for 1% to 100% of the thickness of the aerogel matrix.

2. A method for preparing a bio-based aerogel capable of dual-mode, high-efficiency air-based water collection, characterized in that, Includes the following steps: Step 1, Preparation of the aerogel matrix: Hydroxypropyl cellulose and anhydrous lithium chloride are added to deionized water to form a gel precursor solution. The pH of the gel precursor solution is adjusted to 7.0-9.

0. Konjac mannan is added to the gel precursor solution to carry out the reaction. After the reaction is completed, the solution is transferred to a mold and then freeze-dried to obtain an aerogel matrix. Step 2, Construction of the double-layer water collection structure: The aerogel matrix is ​​placed in an aqueous solution of ferric chloride. After complete absorption, the aerogel matrix adsorbed with ferric chloride and pyrrole are placed in an oven using a vapor deposition method. Polypyrrole layer is obtained by in-situ polymerization at the location impregnated with ferric chloride solution, thus obtaining the double-layer water collection structure.

3. The method for preparing the dual-mode, high-efficiency air-based aerogel according to claim 2, characterized in that, The reaction mass ratio of hydroxypropyl cellulose and anhydrous lithium chloride is 1:(2~10).

4. The method for preparing a bio-based aerogel capable of dual-mode high-efficiency air-based water collection according to claim 2, characterized in that, The reaction mass ratio of hydroxypropyl cellulose and konjac mannan is 1:(0.3~4).

5. The method for preparing the dual-mode, high-efficiency air-based aerogel according to claim 2, characterized in that, The freeze-drying process includes: freezing at -4 to -10°C for 3 hours, immersing in liquid nitrogen for 10 to 20 minutes, and then drying at -30 to -40°C for 10 to 24 hours.

6. The method for preparing the dual-mode, high-efficiency air-based aerogel according to claim 2, characterized in that, The aerogel matrix adsorbed with ferric chloride and pyrrole monomer were placed in an oven at 40-50°C and polymerized in situ at the location impregnated with ferric chloride solution for 20-40 minutes to obtain a polypyrrole layer.

7. The method for preparing the dual-mode, high-efficiency air-based aerogel according to claim 2, characterized in that, The thickness of the polypyrrole layer accounts for 1% to 100% of the thickness of the aerogel matrix.

8. The method for preparing the dual-mode, high-efficiency air-based aerogel according to any one of claims 1 to 7, characterized in that, The preparation method further includes: immersing the aerogel matrix loaded with a polypyrrole layer in a phytic acid solution for 10-20 minutes, and then washing and drying it to obtain a bio-based aerogel capable of dual-mode high-efficiency air water collection.

9. An application of a bio-based aerogel capable of dual-mode, high-efficiency air-based water collection, characterized in that, The bio-based aerogel of claim 1 can collect water from the air within a humidity range of 30~100%RH. It can desorb adsorbed water by using one or a combination of two modes: solar photothermal induced release and mechanical extrusion release. It can be used under both light and no light conditions.

10. The application of the dual-mode, high-efficiency air-based aerogel according to claim 9, characterized in that, The volume change range of the bio-based aerogel in terms of extrusion deformation and moisture absorption rebound is 0-95%.

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