Porous aerogel with vertically arranged channels as well as preparation method and application of porous aerogel

Abstract

The invention relates to porous aerogel with vertical arrangement channels and a preparation method and application thereof.The porous aerogel is obtained by injecting a precursor solution into a mold with a steel needle array (3) and sequentially conducting freezing, taking out, freeze-drying and curing drying treatment, and the aerogel is provided with the vertical arrangement channels. The mold comprises an upper mold cover (1) and a lower mold cavity (2), a steel needle array (3) is arranged on a base plate of the upper mold cover (1), and the height of the lower mold cavity (2) is the same as that of the steel needle array (3). Compared with the prior art, the vertical pore channel is actively formed through the mold with the steel needle array, the problems of uncontrollable pore channel structure, complex process and the like in the prior art are solved, meanwhile, the selection range of a photo-thermal material is expanded, and the prepared aerogel can be used in the field of seawater desalination and has broad application prospects. And the water delivery efficiency, the salt tolerance and the process universality are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aerogel preparation, and in particular to a porous aerogel with vertically arranged channels, a preparation method and an application thereof. Background Art

[0002] Aerogels are three-dimensional, network-like solid materials with nanoporous structures. Their internal porosity can reach as high as 80% to 99.8%, resulting in ultra-low density, high specific surface area, and extremely low thermal conductivity. They have shown broad application prospects in aerospace, building insulation, energy storage, seawater desalination, and electronic devices. Currently, the main types of aerogels include inorganic aerogels, organic aerogels, and carbon-based aerogels. However, aerogels typically have irregular networks, uneven pore size distribution, and a disordered pore structure. In the desalination field, aerogels loaded with light-absorbing materials are used as solar interfacial desalination devices. Their porous structure increases the contact area between water molecules and the evaporating medium, accelerating the evaporation rate and improving solar energy utilization efficiency. However, with prolonged evaporation, the brine concentration in the evaporator increases, leading to the continuous precipitation of salt on the evaporator surface, forming salt crystals. These salt scales clog the aerogel pores, hindering capillary water transport. Furthermore, the salt crystals reflect sunlight, reducing light absorption efficiency, and ultimately significantly reducing the evaporation rate and device stability. The vertical channels constructed inside the aerogel are conducive to the salt exchange between high-concentration brine and seawater, diluting the brine inside the aerogel and reducing salt precipitation.

[0003] For example, patent CN117069997A discloses a nanofiber aerogel composite material for seawater desalination and a preparation method thereof, wherein the composite material includes an aerogel matrix containing a vertical pore structure and a photothermal conversion layer. However, the formation of the pore structure of the aerogel in this patent relies on the self-assembly of the material, and the controllability is insufficient: the aerogel mainly forms vertical pores by freeze-drying a nanofiber / polymer mixture, and its pore structure depends on the phase separation process of the material itself. Therefore, the pore uniformity is limited by the material ratio and freezing conditions, and it is difficult to accurately control the pore size and distribution. In addition, the patent has not verified the long-term stability under high salt concentrations (such as >10%), and its vertical pores may be blocked due to salt deposition, which may cause fluctuations in water transport performance in actual applications, and its anti-salting ability needs to be improved.

[0004] Therefore, designing a three-dimensional porous aerogel evaporation device with simple preparation method, high controllability, and strong evaporation, water purification and desalination performance is very important for solving the freshwater shortage and energy crisis. Summary of the Invention

[0005] The purpose of the present invention is to provide a porous aerogel with vertically arranged channels and its preparation method and application. The preparation method is simple and controllable. The prepared aerogel has vertically arranged channels and can be applied in the field of seawater desalination. It has the characteristics of high salt tolerance, high evaporation rate and high water transport rate.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One of the objects of the present invention is to provide a method for preparing a porous aerogel having vertically arranged channels, comprising the following steps:

[0008] S1: prepare precursor solution;

[0009] S2: The precursor solution is injected into a mold with a vertically arranged steel needle array, taken out after freezing treatment, and then freeze-dried and dried to obtain a porous aerogel.

[0010] Preferably, the mold includes an upper mold cover and a lower mold cavity, a substrate is provided on the side of the upper mold cover facing the lower mold cavity, the steel needle array is provided on the substrate, and the height of the lower mold cavity is the same as that of the steel needle array.

[0011] Further preferably, the mold is a split structure.

[0012] Further preferably, the material of the upper mold cover is selected from any one of polytetrafluoroethylene, polyethylene, polypropylene, polydimethylsiloxane, and glass, and the material of the lower mold cavity is selected from any one of polytetrafluoroethylene, polyethylene, polypropylene, polydimethylsiloxane, and glass.

[0013] Preferably, the steel needle array comprises a number of uniformly distributed steel needles, the gap between two adjacent steel needles is 2mm-10cm, the height of the steel needle is 1-10cm, and the cross-sectional area of ​​the steel needle is 3mm. 2 -3cm 2 The cross-sectional area of ​​the steel needle array is 4 cm 2 -25m 2 .

[0014] Further preferably, the gap between each steel needle is 0.5-1 cm.

[0015] Further preferably, the steel needle is fixed to the upper mold cover substrate by a thread locking composite process.

[0016] Preferably, the arrangement shape of the steel needle array is selected from any one of a polygonal cross-section and a streamlined cross-section.

[0017] Further preferably, the polygonal cross-section includes a triangle, a rectangle, a rhombus, or a hexagon.

[0018] Further preferably, the streamlined cross-section includes a circular shape, an elliptical shape, a semicircular shape, and a spindle shape.

[0019] Further preferably, the shape of the cross section of the steel needles in the steel needle array is selected from one or more of circular, elliptical, triangular, square or hexagonal.

[0020] Preferably, the cross-sectional shape of the mold is selected from any one of a polygonal cross-section and a streamlined cross-section.

[0021] Further preferably, the polygonal cross-section includes a triangle, a rectangle, a rhombus, or a hexagon.

[0022] Further preferably, the streamlined cross-section includes a circular shape, an elliptical shape, a semicircular shape, and a spindle shape.

[0023] Preferably, the cross-sectional area of ​​the mold is 4 cm 2 -25m 2 .

[0024] Preferably, the height of the mold is 1-10 cm.

[0025] Preferably, in step S2, the freezing treatment temperature is -80--2°C, the time is 6-168 hours, and the freeze-drying time is 96-168 hours.

[0026] Preferably, in step S1, the precursor solution includes a framework material.

[0027] Further preferably, in step S1, the framework material is selected from any one or more of inorganic materials, organic polymers, and biomass materials.

[0028] Further preferably, in step S1, the inorganic material is selected from any one or more of silicon dioxide, aluminum oxide, and titanium oxide.

[0029] Further preferably, in step S1, the organic polymer is selected from any one or more of polyvinyl alcohol, polyacrylamide, polyethylene glycol, and polyacrylic acid.

[0030] Further preferably, in step S1, the biomass material is selected from any one or more of cellulose, chitosan, and sodium alginate.

[0031] Preferably, the preparation method further comprises step S3: loading the photothermal conversion material onto the aerogel.

[0032] Preferably, in step S3, the photothermal conversion material is selected from any one or more of semiconductor materials, metal nanomaterials, carbon materials and organic polymer materials.

[0033] Further preferably, in step S3, the semiconductor material is selected from any one or more of sulfide semiconductor materials, MXene and black phosphorus.

[0034] Further preferably, in step S3, the metal nanomaterial is selected from any one or more of gold, silver, and copper.

[0035] Further preferably, in step S3, the carbon material is selected from any one or more of carbon quantum dots, activated carbon, carbon nanotubes and graphene.

[0036] Further preferably, in step S3, the organic polymer material is selected from any one or more of polypyrrole, polydopamine, polyaniline, and polythiophene.

[0037] Further preferably, in step S3, the photothermal conversion material is added to the precursor solution in step S1, and step S2 is performed, so as to load the photothermal conversion material into the aerogel.

[0038] Further preferably, in step S3, the photothermal conversion material is loaded into the aerogel by an impregnation method or a spraying method.

[0039] More preferably, before or after the drying and curing, the material is further immersed in a calcium chloride solution for 8-16 hours.

[0040] More preferably, the soaking treatment time is 12 hours.

[0041] Further preferably, the concentration of the calcium chloride solution is 3-4%, and further preferably 3.5%.

[0042] A second object of the present invention is to provide a porous aerogel having vertically arranged channels prepared by the preparation method.

[0043] A third object of the present invention is to provide an application of the porous aerogel having vertically arranged channels in the field of seawater desalination.

[0044] The present invention uses a method of pre-setting a steel needle array in a mold to directly shape vertical channels during the freezing process. The size, shape, and distribution of the channels can be precisely controlled through mold design. The resulting channels are regular and continuous, significantly improving the water transfer rate. The proposed split mold structure supports flexible arrangements of the steel needle array (such as circular, five-pointed star, etc.) and can be adapted to different aerogel systems. The mold is reusable and suitable for large-scale production. By adjusting parameters such as the height and gap between the steel needles, the channel performance can be further optimized.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The present invention provides a porous aerogel with vertically arranged channels and its preparation method and application by injecting a precursor solution into a mold with a steel needle array, freezing and freeze-drying. The preparation method solves the problems of uncontrollable pore structure and complex process. The prepared porous aerogel can be applied to the field of seawater desalination, and has the characteristics of high salt resistance and high evaporation rate, and has universal applicability.

[0047] (2) The present invention utilizes a mold with a steel needle array to prepare aerogel. The porous aerogel prepared by inserting the steel needles has vertical channels connected up and down, which improves the water transport performance of the capillary action and greatly increases the evaporation rate of the evaporator.

[0048] (3) In the mold of the present invention having a steel needle array, the gap between the steel needles can be set to 0.5 to 1 cm. This large-aperture design is conducive to enhancing the salt diffusion capacity, making the aerogel pores less likely to be blocked by salt and having good salt dissolving ability.

[0049] (4) The polyurethane / chitosan / MXene porous aerogel prepared by the present invention still maintains a strength of 2.31 kg·m in 10% concentrated brine. -2 h-1 evaporation rate, with good salt tolerance.

[0050] (5) The polyurethane / chitosan / MXene porous aerogel prepared by the present invention can be used for seawater desalination. The metal ion removal rate of the aerogel under 10% saline water is 3 to 4 orders of magnitude lower than that of the original seawater, and there is still no salt crystallization after 12 hours of continuous evaporation.

[0051] (6) The mold with a steel needle array of the present invention can optimize the channel performance by adjusting parameters such as the height and gap of the steel needles, adapt to different aerogel systems, and has universal applicability. The mold is reusable and suitable for industrial production.

[0052] (7) The present invention loads photothermal materials (such as polypyrrole, carbon nanotubes, etc.) by immersion / spraying, which does not require magnetic field equipment, making the process simpler and providing a variety of photothermal material options to meet the needs of different scenarios. In addition, the photothermal material is firmly bonded to the aerogel matrix and there is no risk of falling off during long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of the overall structure of the circular cross-section array mold in Example 1;

[0054] Figure 2 for Figure 1 Schematic diagram of the three-dimensional structure of the upper mold cover of the array mold shown in;

[0055] Figure 3 for Figure 1 Schematic diagram of the three-dimensional structure of the lower mold cavity of the array mold shown;

[0056] Figure 4 for Figure 1 The schematic diagram of the top structure of the array mold cover is shown;

[0057] Figure 5 This is a schematic diagram of the overall structure of the square cross-section array mold in Example 4;

[0058] Figure 6 for Figure 5 Schematic diagram of the three-dimensional structure of the upper mold cover of the array mold shown;

[0059] Figure 7 for Figure 5 Schematic diagram of the three-dimensional structure of the lower mold cavity of the array mold shown;

[0060] Figure 8 for Figure 5 The schematic diagram of the top structure of the array mold cover is shown;

[0061] Figure 9-10 This is the SEM microstructure of the sodium alginate / graphene oxide / polypyrrole porous aerogel prepared in Example 1;

[0062] Figure 11 This is the pore size distribution diagram of the sodium alginate / graphene oxide / polypyrrole porous aerogel prepared in Example 1;

[0063] Figure 12 This is a comparison curve of the evaporation rate and photothermal conversion capacity of aerogel samples with different graphene oxide contents in 3.5 wt% NaCl solution in Example 1;

[0064] Figure 13 This is a bar graph showing the removal effect of sodium alginate / graphene oxide / polypyrrole porous aerogel prepared in Example 1 on typical seawater ions;

[0065] Figure 14 This is a bar graph showing the removal effect of the polyurethane / chitosan / MXene porous aerogel prepared in Example 3 on typical seawater ions;

[0066] Figure 15 This is a schematic diagram of the assembly structure of the split array mold of the present invention; in the figure: 1-upper mold cover; 2-lower mold cavity; 3-steel needle array. DETAILED DESCRIPTION

[0067] This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0068] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0069] A method for preparing a porous aerogel having vertically arranged channels comprises the following steps:

[0070] S1: prepare precursor solution;

[0071] S2: The precursor solution is injected into a mold having a vertically arranged steel needle array 3, taken out after freezing treatment, and then freeze-dried, dried and solidified to obtain a porous aerogel.

[0072] like Figure 15 As shown, the mold includes an upper mold cover 1 and a lower mold cavity 2. The upper mold cover 1 is provided with a base plate on the side facing the lower mold cavity 2. The steel needle array 3 is provided on the base plate of the upper mold cover 1. The height of the lower mold cavity 2 is the same as that of the steel needle array 3. The steel needle array 3 includes a number of evenly distributed steel needles. The gap between two adjacent steel needles is 2mm-10cm. The height of the steel needle is 1-10cm. The cross-sectional area of ​​the steel needle is 3mm. 2 -3cm 2 The cross-sectional area of ​​the steel needle array 3 is 4 cm 2 -25m 2 ;

[0073] The arrangement shape of the steel needle array 3 is selected from any one of a polygonal cross-section or a streamlined cross-section. The polygonal cross-section includes a triangle, a rectangle, a rhombus, and a hexagon. The streamlined cross-section includes a circle, an ellipse, a semicircle, and a spindle. The shape of the cross-section of the steel needles in the steel needle array 3 is selected from one or more of a circle, an ellipse, a triangle, a square, or a hexagon.

[0074] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0075] Example 1

[0076] A sodium alginate / graphene oxide / polypyrrole porous aerogel, the preparation method of which comprises the following steps:

[0077] Step 1: Dissolve 0.75 g of sodium alginate and 0.04 g of graphene oxide powder in 40 mL of deionized water using a water bath heating method to prepare a mixed solution of sodium alginate and graphene oxide;

[0078] Step 2: Pour the prepared sodium alginate and graphene oxide mixed solution into a mold with a cross-section size of 9cm 2In a polytetrafluoroethylene mold, the mold and the steel needle array have a circular cross-sectional pattern, each steel needle is 3 cm high and has a gap of 0.5 cm. The cross-sectional pattern of each steel needle is circular and placed in a -60°C environment and frozen for 48 hours to form a gel;

[0079] Step 3: Take out the frozen gel, freeze-dry it into aerogel, soak it in 3.5% calcium chloride solution for 12 hours, and dry and solidify it to obtain sodium alginate / graphene oxide porous aerogel;

[0080] Step 4: Add the sodium alginate / graphene oxide porous aerogel to the pyrrole monomer aqueous solution (0.283 M, 40 mL) and soak for 30 minutes;

[0081] Step 5: Add 200 ml of anhydrous ferric chloride (0.293 M) acidified with concentrated hydrochloric acid to the mixed solution prepared in Step 4. The mixture is magnetically stirred for 60 minutes. The aerogel is then washed with deionized water to remove any residual reactants. This process is repeated three times. Finally, the alginate / graphene oxide / polypyrrole porous aerogel is dried and solidified to obtain.

[0082] The mold model in this embodiment 1 is as follows Figure 1-4 shown.

[0083] The sodium alginate / graphene oxide / polypyrrole porous aerogel prepared in Example 1 was observed by scanning electron microscopy. Figure 9 、 10 As expected, the aerogels obtained after freeze-drying exhibited a porous structure with many straight micron-sized channels, as shown in Figure 2. Figure 11 As shown, the average pore size is 145.0±75.6μm.

[0084] According to the steps in Example 1, sodium alginate / graphene oxide / polypyrrole porous aerogels with different graphene oxide contents were prepared (the added graphene oxide mass was 0.02g, 0.04g, 0.08g, and 0.1g, respectively). The salt resistance of the obtained aerogel samples was tested. The test results are shown in FIG. Figure 12 As shown in the figure, at a saline concentration of 3.5%, each sodium alginate / graphene oxide / polypyrrole porous aerogel sample exhibited excellent evaporation rate and photothermal conversion ability.

[0085] The desalination capacity of the sodium alginate / graphene oxide / polypyrrole porous aerogel prepared in Example 1 was investigated, and the concentration of typical seawater ions after desalination was tested. The results are as follows: Figure 13 As shown. After aerogel purification, Na + , K + Mg 2+ and Ca 2+The concentration of ions in the water is about two orders of magnitude lower than that in pristine seawater. At the same time, the salinity of all four ions is below the salinity standards set by the World Health Organization.

[0086] Example 2

[0087] A polyvinyl alcohol / carbon nanotube porous aerogel, the preparation method comprising the following steps:

[0088] Step 1: Prepare 8% wt polyvinyl alcohol (PVA) solution by water bath heating method, heating in 80°C water bath for 2 hours;

[0089] Step 2: PVA solution, 2% wt carbon nanotube (CNT) suspension, and glutaraldehyde (2 mL) were added to water in a volume ratio of 5:3:1. The resulting solution was placed in an ice-water bath to cool to 4°C while stirring, and then HCl (0.3 mL, 1.2 M) was added with vigorous stirring.

[0090] Step 3: Pour the solution prepared in step 2 into the mold. The cross-section of the mold is 25cm. 2 In a polytetrafluoroethylene mold, the mold and the steel needle array have a rectangular cross-sectional pattern, each steel needle is 5 cm high and has a gap of 0.7 cm. The cross-sectional pattern of each steel needle is a five-pointed star, and it is placed in a -70°C environment to freeze into a gel;

[0091] Step 4: Take out the frozen gel, freeze-dry it into aerogel, soak it in calcium chloride solution for 12 hours, and obtain polyvinyl alcohol / carbon nanotube porous aerogel after drying and solidification.

[0092] Comparative Example 1

[0093] A polyvinyl alcohol / carbon nanotube porous aerogel is prepared in Comparative Example 1. Unlike Example 2, the mold of the present invention is not used in the preparation. The preparation method includes the following steps:

[0094] Step 1: Prepare 8% wt polyvinyl alcohol (PVA) solution by water bath heating method, heating in 80°C water bath for 2 hours;

[0095] Step 2: PVA solution, 2% wt carbon nanotube (CNT) suspension, and glutaraldehyde (2 mL) were added to water in a volume ratio of 5:3:1. The resulting solution was placed in an ice-water bath to cool to 4°C while stirring, and then HCl (0.3 mL, 1.2 M) was added with vigorous stirring.

[0096] Step 3: Place the solution prepared in step 2 directly at -70°C to freeze into a gel.

[0097] Step 4: Take out the frozen gel, freeze-dry it into aerogel, soak it in calcium chloride solution for 12 hours, and obtain polyvinyl alcohol / carbon nanotube porous aerogel after drying and solidification.

[0098] The polyvinyl alcohol / carbon nanotube porous aerogels of Example 2 and Comparative Example 1 were subjected to a salt resistance test. At a salt water concentration of 5%, the polyvinyl alcohol / carbon nanotube porous aerogels exhibited a superior evaporation rate compared to the polyvinyl alcohol / carbon nanotube aerogels that had not been mold-treated.

[0099] Example 3

[0100] A polyurethane / chitosan / MXene porous aerogel, the preparation method comprising the following steps:

[0101] Step 1: MXene nanosheets were prepared using MAX phase as the starting material via hydrofluoric acid (HF) etching. 2g of MAX was slowly added to 20ml of HF at 45°C and magnetically stirred for 56 hours. The resulting solution was centrifuged for 5 minutes at 8000 rpm and then washed several times with deionized water until the supernatant had a pH of 6. The collected supernatant was freeze-dried to yield MXene.

[0102] Step 2: Disperse 2g of chitosan (CTS) and 2mL of acetic acid (HAc) in 100ml of deionized water. Add 12ml of CTS to 2.64g of waterborne polyurethane (WPU) solution and sonicate for 5min to obtain a highly dispersed, uniform suspension.

[0103] Step 3: Pour the uniform solution into a polydimethylsiloxane mold with a cross-sectional area of ​​73 cm 2 The mold and the steel needle array had a five-pointed star cross-sectional pattern, with each needle 8.5 cm tall and 1 cm apart. Each needle had a triangular cross-sectional pattern. The mold was frozen at -40°C for 56 hours. Finally, the frozen sample was freeze-dried for 96 hours and then cured at 80°C for 8 hours. It was then immersed in a calcium chloride solution for 12 hours to obtain a polyurethane / chitosan / MXene porous aerogel.

[0104] The polyurethane / chitosan / MXene porous aerogel of Example 3 was subjected to a salt resistance test. At a salt water concentration of 10%, the evaporation rate of the polyurethane / chitosan / MXene porous aerogel was 2.31 kg·m -2 ·h -1 After desalination, the four target metal ions (Na + Mg 2+ 、B 3+ , Ca 2+ and K 2+) concentration is 3-4 orders of magnitude lower than that of simulated seawater, and is significantly lower than the safety salinity standards of the World Health Organization (WHO) and the U.S. Environmental Protection Agency (EPA), such as Figure 14 In addition, the three metal ions (Ti + 、Al 3+ and Cu 2+ ) were tested, and the concentrations of the three heavy metal ions in the water samples were all reduced to below the drinking water standard, demonstrating the potential for practicality.

[0105] Example 4

[0106] This embodiment is different from embodiment 2 in that Figure 5-8 As shown, in this embodiment, the mold parameters used are:

[0107] The cross-sectional pattern of the mold and the steel needle array is square, each steel needle is 6 cm high, with a gap of 1 cm, and the cross-sectional pattern of each steel needle is triangular.

[0108] Comparative Example 2

[0109] A nanofiber aerogel for seawater desalination, the preparation method of which is as follows:

[0110] Step 1: Polyacrylamide, glutaraldehyde, and a PVA-co-PE (polyvinyl alcohol-ethylene copolymer) nanofiber suspension are mixed and magnetically stirred for 40 minutes to obtain a mixture, which is then frozen to set. The mixture comprises 1.5 wt% polyacrylamide, 3 wt% PVA-co-PE nanofibers, and 1 wt% glutaraldehyde. The mixture is frozen at -80°C for 6 hours. The average diameter of the PVA-co-PE nanofibers is 200 nm.

[0111] Step 2: freeze-dry the mixture after freeze-setting in step S1, the freeze-drying time is 48 hours and the temperature is 60° C. to obtain a nanofiber aerogel with a vertical pore structure.

[0112] Example 5

[0113] A nanofiber aerogel for seawater desalination, the preparation method of which is as follows:

[0114] Step 1: Mixing a polymer polyacrylamide, glutaraldehyde, and a PVA-co-PE (polyvinyl alcohol-ethylene copolymer) nanofiber suspension, and magnetically stirring for 40 minutes to obtain a mixture; wherein the mass percentage concentration of polyacrylamide in the mixture is 1.5wt%, the mass percentage concentration of PVA-co-PE nanofibers is 3wt%, and the mass percentage concentration of glutaraldehyde is 1wt%; and the average diameter of the PVA-co-PE nanofibers is 200nm;

[0115] Step 2: Pour the prepared mixed solution into a mold with a cross-section size of 9cm 2 In a polytetrafluoroethylene mold, the mold and the steel needle array have a circular cross-sectional pattern, each steel needle is 3 cm high and has a gap of 0.5 cm. The cross-sectional pattern of each steel needle is circular and placed in a -60°C environment and frozen for 48 hours to form a gel;

[0116] Step 3: Take out the frozen gel, freeze-dry it into aerogel, and soak it in 3.5% calcium chloride solution for 12 hours. After drying and solidification, a nanofiber aerogel with a vertical pore structure is obtained.

[0117] The aerogel produced in Example 5 using the steel needle array mold of the present invention exhibits a vertically ordered pore structure that significantly improves capillary water transport and evaporation rate, resulting in superior salt crystallization resistance. Compared to the random-pore aerogel in Comparative Example 2, which lacks the steel needle structure, Example 5 exhibits significant advantages in pore connectivity, water vapor transport efficiency, and resistance to salt precipitation, making it suitable for longer-term desalination applications.

[0118] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing a porous aerogel having vertically arranged channels, characterized in that: The steps include: S1: prepare precursor solution; S2: The precursor solution is injected into a mold having a vertically arranged steel needle array (3), taken out after freezing treatment, and then freeze-dried, dried and solidified to obtain a porous aerogel.

2. The method for preparing a porous aerogel having vertically arranged channels according to claim 1, characterized in that: The mold comprises an upper mold cover (1) and a lower mold cavity (2); a base plate is provided on the side of the upper mold cover (1) facing the lower mold cavity (2); the steel needle array (3) is provided on the base plate; and the height of the lower mold cavity (2) is the same as that of the steel needle array (3).

3. The method for preparing a porous aerogel having vertically arranged channels according to claim 2, characterized in that: The material of the upper mold cover (1) is selected from any one of polytetrafluoroethylene, polyethylene, polypropylene, polydimethylsiloxane, and glass, and the material of the lower mold cavity (2) is selected from any one of polytetrafluoroethylene, polyethylene, polypropylene, polydimethylsiloxane, and glass.

4. The method for preparing a porous aerogel having vertically arranged channels according to claim 1, wherein: The steel needle array (3) comprises a number of uniformly distributed steel needles, the gap between two adjacent steel needles is 2mm-10cm, the height of the steel needles is 1-10cm, and the cross-sectional area of ​​the steel needles is 3mm. 2 -3cm 2 The cross-sectional area of ​​the steel needle array (3) is 4 cm 2 -25m 2 .

5. The method for preparing a porous aerogel having vertically arranged channels according to claim 1, wherein: The arrangement shape of the steel needle array (3) is selected from any one of a polygonal cross-section or a streamlined cross-section, the polygonal cross-section includes a triangle, a rectangle, a rhombus, and a hexagon, the streamlined cross-section includes a circle, an ellipse, a semicircle, and a spindle, and the shape of the cross-section of the steel needles in the steel needle array (3) is selected from one or more of a circle, an ellipse, a triangle, a square, or a hexagon.

6. The method for preparing a porous aerogel having vertically arranged channels according to claim 1, characterized in that: In step S2, the freezing treatment temperature is -80--2°C, the time is 6-168 hours, and the freeze-drying time is 96-168 hours.

7. The method for preparing a porous aerogel having vertically arranged channels according to claim 1, characterized in that: In step S1, the precursor solution includes a skeleton material, and the skeleton material is selected from any one or more of inorganic materials, organic polymers, and biomass materials, wherein the inorganic material is selected from any one or more of silica, alumina, and titanium oxide, the organic polymer is selected from any one or more of polyvinyl alcohol, polyacrylamide, polyethylene glycol, and polyacrylic acid, and the biomass material is selected from any one or more of cellulose, chitosan, and sodium alginate.

8. The method for preparing a porous aerogel having vertically arranged channels according to claim 1, characterized in that: The method further includes step S3: loading a photothermal conversion material onto the aerogel, wherein the photothermal conversion material is selected from any one or more of a semiconductor material, a metal nanomaterial, a carbon material, and an organic polymer material, wherein the semiconductor material is selected from any one or more of a sulfide semiconductor material, MXene, and black phosphorus, the metal nanomaterial is selected from any one or more of gold, silver, and copper, the carbon material is selected from any one or more of carbon quantum dots, activated carbon, carbon nanotubes, and graphene, and the organic polymer material is selected from any one or more of polypyrrole, polydopamine, polyaniline, and polythiophene.

9. A porous aerogel having vertically arranged channels prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The aerogel has a porous structure and has vertically arranged channels.

10. Use of the porous aerogel having vertically arranged channels as claimed in claim 9 in the field of seawater desalination.

Images