An expanded perlite-based aerogel structure solar interface evaporator and its preparation method and application

Abstract

The present invention discloses an expanded perlite-based aerogel structure solar interface evaporator, and its preparation method and application. The present invention relates to the field of evaporator technology. The present invention comprises an upper aerogel layer and a lower aerogel layer, wherein the upper aerogel layer is disposed on the upper surface of the lower aerogel layer; the lower aerogel layer is produced by freeze-drying a mixed solution of expanded perlite powder, polyvinyl alcohol solution, and cellulose solution; and the upper aerogel layer is produced by freeze-drying a mixed solution of photothermal conversion material, heat storage material, polyvinyl alcohol solution, and cellulose solution. The expanded perlite-based aerogel structure interface evaporator of the present invention integrates photothermal conversion, energy storage, thermal insulation, and enhanced water transmission, and can achieve a high evaporation rate through structural design.

Description

Technical Field

[0001] The present invention relates to the technical field of evaporators, and in particular to an expanded perlite-based aerogel structure solar interface evaporator, a preparation method thereof, and applications thereof. Background Art

[0002] Seawater desalination is one of the most reliable methods to solve the problem of freshwater shortage. At present, traditional seawater desalination technology is mainly divided into single-phase water treatment method (electrodialysis, membrane osmosis, etc.) and multiphase water treatment method (multi-stage flash evaporation, multi-effect distillation, etc.). However, the desalination technology has a complex process flow, high operating costs, and consumes a large amount of fossil fuels, causing environmental pollution problems. Therefore, green and clean solar energy is introduced as an energy source into seawater desalination technology to form a solar seawater desalination system. Solar seawater desalination systems can be divided into solar distiller and solar interface evaporator. Since the separation of the photothermal conversion interface and the water evaporation interface of the solar distiller causes a large amount of energy loss, the solar interface evaporator integrates photothermal conversion and water evaporation on the same interface, which can significantly reduce the energy loss problem of the former. Therefore, the solar interface evaporator is currently the research hotspot of solar seawater desalination system.

[0003] Solar interface evaporators use solar energy as their sole energy source, converting it into heat through photothermal conversion materials to heat the seawater at the evaporator interface, causing it to evaporate and achieve the desalination effect. However, due to the instability and intermittent nature of solar energy, it is not conducive to the continuous and stable operation of the evaporator, thereby reducing the utilization rate of sunlight and the efficiency of freshwater production. The intermittent and unstable nature of solar energy limits the performance improvement of solar interface evaporators. How to alleviate the problem of solar interface evaporators' over-reliance on solar energy and improve the evaporation performance of interface evaporators through material design are the hot topics and difficulties in current solar interface evaporator research. Summary of the Invention

[0004] The present invention aims to address the aforementioned shortcomings of the existing technology by proposing an expanded perlite-based aerogel solar interfacial evaporator, its preparation method, and its application. By leveraging the properties of clay minerals and functionalizing them, the structure and materials of the interfacial evaporator are designed to significantly enhance its evaporation performance and achieve efficient seawater desalination.

[0005] The present invention provides an expanded perlite-based aerogel structure solar interface evaporator, comprising an upper aerogel layer and a lower aerogel layer, wherein the upper aerogel layer is arranged on the upper surface of the lower aerogel layer; the lower aerogel layer is prepared by freeze-drying a mixed solution of expanded perlite powder, polyvinyl alcohol solution, and cellulose solution; and the upper aerogel layer is prepared by freeze-drying a mixed solution of photothermal conversion material, heat storage material, polyvinyl alcohol solution, and cellulose solution.

[0006] Furthermore, the light-to-heat conversion material is carbonized expanded perlite powder.

[0007] Furthermore, the heat storage material uses carbonized expanded perlite particles as a carrier and is loaded with phase change material.

[0008] Furthermore, the carbonized expanded perlite powder is prepared by the following method: adding the expanded perlite powder to a sucrose solution, heating and stirring in a water bath, and then filtering to obtain a mass, drying the mass and calcining it under an inert gas atmosphere to obtain the carbonized expanded perlite powder; and\or,

[0009] The carbonized expanded perlite particles are prepared by the following method: dropping a sucrose solution into the expanded perlite particles, vacuum filtering, heating in a water bath, and then filtering to obtain a mixture, drying the mixture and calcining it under an inert gas atmosphere to obtain the carbonized expanded perlite particles.

[0010] Furthermore, during the preparation process of the carbonized expanded perlite powder and the carbonized expanded perlite particles, they are calcined at 800-1100° C. for 2-3 hours under an argon atmosphere.

[0011] Furthermore, the specific preparation process of the heat storage material is as follows: the carbonized expanded perlite particles and the phase change material are vacuum filtered, and after heating, the phase change material is injected into the pore structure of the carbonized expanded perlite particles by vacuum impregnation.

[0012] A method for preparing the above-mentioned expanded perlite-based aerogel structure solar interface evaporator is characterized by comprising the following steps:

[0013] The expanded perlite powder, polyvinyl alcohol solution and cellulose solution are stirred and mixed to obtain a lower layer solution;

[0014] Mixing the photothermal conversion material, the heat storage material, the polyvinyl alcohol solution and the cellulose solution to obtain an upper layer solution;

[0015] The lower layer gel solution is poured into the mold and the solution is quickly solidified by directional freezing technology; after the lower layer solution is solidified, the upper layer solution is quickly poured into the mold. After the double-layer solution is completely solidified, it is placed in a freeze drying box for freeze drying to obtain a double-layer latent heat aerogel, namely, an expanded perlite-based aerogel structure solar interface evaporator.

[0016] Furthermore, in the lower layer solution, the mass ratio of the expanded perlite powder, polyvinyl alcohol solution, and cellulose solution is 1-2:20-22:2-3; wherein the mass fraction of the polyvinyl alcohol solution is 3-5% and the mass fraction of the cellulose solution is 2-3%.

[0017] Furthermore, in the upper solution, the mass ratio of the photothermal conversion material, heat storage material, polyvinyl alcohol solution, and cellulose solution is 0.5-1:2-2.5:6-8:2-2.5; wherein the mass fraction of polyvinyl alcohol solution is 3-5% and the mass fraction of cellulose solution is 2-3%.

[0018] An application of the expanded perlite-based aerogel structure solar interface evaporator as described above is to immerse the lower layer of aerogel in seawater and float the upper layer of aerogel on the seawater surface for seawater desalination.

[0019] The present invention aims at the functions that a solar interface evaporator should have, utilizes the characteristics of clay minerals and functionalizes them, designs the structure and materials of the interface evaporator, and aims to significantly improve the evaporation performance of the evaporator to achieve efficient seawater desalination effect.

[0020] To optimize the evaporator's evaporation performance, the expanded perlite-based aerogel solar interface evaporator of this invention features an upper aerogel layer that performs photothermal conversion, heat storage, and water transport functions; the lower aerogel layer provides thermal insulation and water transport functions. This invention integrates all the necessary functions of a solar interface evaporator and utilizes an ultra-high-porosity aerogel structure as its main component, resulting in a solar interface evaporator with ultra-high evaporation performance. Expanded perlite, a clay mineral, is used as the matrix material to design and prepare the photothermal conversion, heat storage, and thermal insulation materials.

[0021] The photothermal conversion material (EPC) produced by high-temperature carbonization of EP powder in this invention exhibits low reflectivity across the entire solar spectrum. The porous structure of the aerogel facilitates sunlight absorption, further reducing reflectivity and achieving ultra-high light absorptivity. The composite phase-change material, EPPC-PW, can transfer some of its thermal energy through a phase change process in PW when sunlight is abundant, storing it as latent heat. This energy is then released to continue evaporation in the absence of sunlight.

[0022] The expanded perlite-based aerogel structure interface evaporator of the present invention integrates light-heat conversion, energy storage, thermal insulation and enhanced water transmission, and can achieve a high evaporation rate through structural design.

[0023] The expanded perlite-based aerogel structure interface evaporator of the present invention has ultra-high photothermal conversion efficiency and can play an energy storage role due to the presence of photothermal conversion material EPC and composite phase change material EPPC-PW. -2 ·h -1 High evaporation rate, can still reach 2.09kg·m within 20 minutes after lights out -2 ·h -1evaporation rate.

[0024] The expanded pearlite-based aerogel structure interface evaporator of the present invention has a simple preparation process, low cost, no pollution, and significantly improved performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 These are the XRD patterns of the photothermal conversion material EPC and the expanded perlite powder EP.

[0026] Figure 2 This is a physical photo of the composite phase change material EPPC-PW.

[0027] Figure 3 This is a physical photo of the expanded perlite-based aerogel structure interface evaporator prepared in Example 1.

[0028] Figure 4 This is a contact angle test photo of the expanded pearlite-based aerogel structure interface evaporator prepared in Example 3. DETAILED DESCRIPTION

[0029] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0030] The present invention is implemented by the following technical solution, including the following process steps:

[0031] (1) Preparation of expanded perlite powder EPC after carbonization of photothermal conversion material

[0032] Weigh 90g of expanded perlite (EP) micron-sized powder into a 2000ml beaker, add 1800ml of deionized water, stir with a magnetic stirrer for 1 hour, and let it stand for another hour. Siphon the solution from the beaker into another 2000ml beaker and let it stand for 12 hours. After standing, remove the bottom precipitate and freeze-dry it in a freeze dryer for 72 hours to remove moisture. Grind the washed EP white powder.

[0033] Weigh 100g of sucrose and dissolve it in deionized water, and use a 500ml volumetric flask to make up the volume. Then transfer it to a 500ml beaker and place it in a thermal constant temperature heating magnetic stirrer at 60℃, 20rpm water bath and stir for 10min to fully dissolve the sucrose. Weigh 8g of EP powder and add it to the above sucrose solution, and continue heating and stirring in a water bath for 12h to cross-link the EP powder and sucrose. The EP-sucrose mixed solution obtained by heating and stirring in a water bath was filtered with a circulating water vacuum pump for 30min to obtain a block, which was then placed in an electric constant temperature blast drying oven at 70℃ and dried for 12h to remove moisture, and then ground into powder. It was then placed in a micro open tube furnace and calcined at 1000℃ for 2h in an argon atmosphere to obtain carbonized expanded perlite powder EPC, which was used as a photothermal conversion material.

[0034] The XRD patterns of EP before carbonization and EPC after carbonization are shown in Figure 2. Figure 1 As shown, Figure 1 It can be seen that the carbonized expanded perlite EPC shows C phase on the basis of EP, proving that EP has achieved carbonization.

[0035] (2) Preparation of heat storage material (composite phase change material EPPC-PW)

[0036] Expanded perlite particles were sieved through 1 mm and 3 mm sieves to obtain particles with a size of 1-3 mm. The particles were then washed with deionized water and dried in a drying oven at 70°C for 12 hours to obtain clean expanded perlite granules (EPP). Weigh 10 g of EPP into a filtration flask and dissolve 20 g of sucrose in deionized water to a volume of 100 ml. Pour the sucrose solution into a separatory funnel and insert the separatory funnel into the filtration flask. Close the separatory funnel and vacuum filter the EPP in the filtration flask for 10 minutes. Then, open the separatory funnel and slowly drip the sucrose solution into the filtration flask. Place the filtration flask in a water bath at 60°C while vacuum filtering for 30 minutes. The resulting EPP-sucrose solution was filtered through a Büchner funnel for 30 minutes and then dried in a drying oven at 70°C for 12 hours. The dried EPP-sucrose mixture was placed in a micro open tube furnace and calcined at 1000°C for 2 hours under an argon atmosphere to obtain carbonized expanded perlite particles EPPC, which served as the composite phase change material skeleton.

[0037] Weigh 6g of EPPC and 14g of paraffin wax (PW) and place them in a filtration bottle. First, vacuum filter for 10 minutes. Then place the filtration bottle in a water bath at 60°C and heat while vacuuming for 30 minutes. The paraffin wax is injected into the pore structure of EPPC by vacuum impregnation. The composite phase change material obtained by vacuum impregnation is then spread on filter paper and placed in a desktop blast drying oven at 60°C for 48 hours. The filter paper is replaced every 12 hours to remove the PW on the surface of EPPC, thereby obtaining a composite phase change material EPPC-PW. Figure 2 .

[0038] In the preparation of the heat storage material described above, the EPP in the filtration flask is first vacuum-filtered for 10 minutes to expel air from the EPP's porous structure, allowing the sucrose solution to flow into the EPP's micropores and undergo cross-linking during heating. High-temperature calcination then yields uniformly carbonized EPPC. When vacuum impregnating EPPC and PW to form the composite phase-change material EPPC-PW, the mixture in the filtration flask is first vacuum-filtered to expel air from the EPPC's micropores, allowing the high-temperature molten paraffin wax to flow smoothly into the EPPC's pores. The EPPC's microporous structure binds the PW through capillary forces, preventing leakage due to the melt phase transition.

[0039] The photothermal conversion material (EPC) produced by high-temperature carbonization of EP powder in this invention exhibits low reflectivity across the entire solar spectrum. The porous structure of the aerogel facilitates sunlight absorption, further reducing reflectivity and achieving ultra-high light absorptivity. The composite phase-change material, EPPC-PW, can transfer some of its thermal energy through a phase change process in PW when sunlight is abundant, storing it as latent heat. This energy is then released to continue evaporation in the absence of sunlight.

[0040] Example 1

[0041] An aerogel with a mass ratio of 2:1 of composite phase change material EPPC-PW and photothermal conversion material EPC was prepared, and water evaporation under sunlight was simulated.

[0042] Weigh 1g of EP powder, 20g of a 5wt.% polyvinyl alcohol (PVA) solution, and 2.5g of a 2wt.% cellulose (MFC) solution into a 25ml beaker A, so that the EP:PVA:MFC wt.% ratio is 20:20:1. Weigh 0.7g of EPC, 7g of a 5wt.% PVA, and 2.275g of a 2wt.% MFC into beaker B, so that the EPC:PVA:MFC wt.% ratio is 15.4:7.7:1. Additionally, weigh 1.4g of EPPC-PW and add it to beaker B, so that the EPPC-PW:EPC ratio is 2:1. Stir the mixed solutions in the two beakers for 30 minutes, then sonicate for 30 minutes, repeating this cycle three times to obtain a mixed solution. A 20cm*20cm copper plate was placed inside a foam box. A hollow plastic cylindrical mold (3cm tall, 30mm inner diameter, and 36mm outer diameter) was placed on the copper plate (marked at 2cm). Liquid nitrogen was poured into the plate to cool it. The solution in beaker A was then poured into the mold to the 2cm mark. The solution was rapidly solidified using a directional freezing technique. After the lower layer of solution solidified, the solution in beaker B was quickly poured into the mold to the same height. After the double-layer solution completely solidified, it was placed in a freeze-drying oven and freeze-dried for 72 hours to produce a double-layer latent heat aerogel, namely, an expanded perlite-based aerogel structure interface evaporator.

[0043] The aerogel was fixed with foam and placed in a 100ml beaker, with the lower layer of the aerogel immersed in water and the upper layer floating on the water surface. A simulated solar evaporation system was built to simulate water evaporation on the aerogel, and the evaporation rate reached 2.85kg·m under one sun. -2 ·h -1 The evaporation rate can reach 1.51 kg·m within 20 minutes of turning off the light. -2 ·h -1 .

[0044] Figure 3This is a physical photo of the expanded perlite-based aerogel structure interface evaporator prepared in Example 1.

[0045] Example 2

[0046] An aerogel with a mass ratio of composite phase change material EPPC-PW and photothermal conversion material EPC of 2.5:1 was prepared, and water evaporation under sunlight was simulated.

[0047] Weigh 1g of EP powder, 20g of a 5wt.% polyvinyl alcohol (PVA) solution, and 2.5g of a 2wt.% cellulose (MFC) solution into a 25ml beaker A, so that the EP:PVA:MFC wt.% ratio is 20:20:1. Weigh 0.7g of EPC, 7g of a 5wt.% PVA, and 2.275g of a 2wt.% MFC into beaker B, so that the EPC:PVA:MFC wt.% ratio is 15.4:7.7:1. Additionally, weigh 1.75g ​​of EPPC-PW and add it to beaker B, so that the EPPC-PW:EPC ratio is 2.5:1. The mixed solutions in the two beakers are stirred for 30 minutes, then sonicated for 30 minutes, repeating three cycles to obtain a mixed solution. A 20cm*20cm copper plate was placed in a foam box, and a plastic cylindrical hollow mold with a height of 3cm, an inner diameter of 30mm, and an outer diameter of 36mm was placed on the copper plate (marked at a height of 2cm), and liquid nitrogen was poured in to cool the copper plate. Then, the solution in beaker A was poured into the mold to the mark line at a height of 2cm, and the solution was quickly solidified by directional freezing technology; after the lower layer of solution solidified, the solution in beaker B was quickly poured into the mold to the same height as the mold. After the double-layer solution was completely solidified, it was placed in a freeze drying oven and freeze-dried for 72 hours to obtain a double-layer latent heat aerogel. The aerogel was fixed with foam and placed in a 100ml beaker, so that the lower layer of the aerogel was immersed in water and the upper layer floated on the water surface. The aerogel was subjected to simulated water evaporation, and the evaporation rate reached 3.05kg·m under one sun. -2 ·h -1 The evaporation rate can reach 1.88 kg·m within 20 minutes of turning off the light. -2 ·h -1 .

[0048] Example 3

[0049] An aerogel with a mass ratio of 3:1 of composite phase change material EPPC-PW and photothermal conversion material EPC was prepared, and water evaporation under sunlight was simulated.

[0050] Weigh 1g of EP powder, 20g of a 5wt.% polyvinyl alcohol (PVA) solution, and 2.5g of a 2wt.% cellulose (MFC) solution into a 25ml beaker A, so that the EP:PVA:MFC wt.% ratio is 20:20:1. Weigh 0.7g of EPC, 7g of a 5wt.% PVA, and 2.275g of a 2wt.% MFC into beaker B, so that the EPC:PVA:MFC wt.% ratio is 15.4:7.7:1. Additionally, weigh 2.1g of EPPC-PW and add it to beaker B, so that the EPPC-PW:EPC ratio is 3:1. Stir the mixed solutions in the two beakers for 30 minutes, then sonicate for 30 minutes, repeating this cycle three times to obtain a mixed solution. A 20cm*20cm copper plate was placed inside a foam box. A hollow plastic cylindrical mold (3cm tall, 30mm inner diameter, and 36mm outer diameter) was placed on the copper plate (marked at 2cm). Liquid nitrogen was poured into the plate to cool it. The solution in beaker A was then poured into the mold to the 2cm mark. The solution was then rapidly solidified using a directional freezing technique. After the lower layer of solution solidified, the solution in beaker B was quickly poured into the mold to the same height. After the double-layer solution completely solidified, it was placed in a freeze-drying oven and freeze-dried for 72 hours to produce a double-layer latent heat aerogel.

[0051] The surface of the obtained aerogel has strong water absorption, and the contact angle test shows that Figure 4 shown.

[0052] The aerogel was fixed with foam and placed in a 100ml beaker, with the lower layer of the aerogel immersed in water and the upper layer floating on the water surface. The aerogel was subjected to simulated water evaporation, and the evaporation rate reached 3.29kg·m under one sun. -2 ·h -1 The evaporation rate can reach 2.09 kg·m within 20 minutes of turning off the light. -2 ·h -1 .

[0053] Example 4

[0054] An aerogel with a mass ratio of 3.5:1 of composite phase change material EPPC-PW and photothermal conversion material EPC was prepared, and water evaporation under sunlight was simulated.

[0055] Weigh 1g of EP powder, 20g of a 5wt.% polyvinyl alcohol (PVA) solution, and 2.5g of a 2wt.% cellulose (MFC) solution into a 25ml beaker A, so that the EP:PVA:MFC wt.% ratio is 20:20:1. Weigh 0.7g of EPC, 7g of a 5wt.% PVA, and 2.275g of a 2wt.% MFC into beaker B, so that the EPC:PVA:MFC wt.% ratio is 15.4:7.7:1. Additionally, weigh 2.45g of EPPC-PW and add it to beaker B, so that the EPPC-PW:EPC ratio is 3.5:1. The mixed solutions in the two beakers are stirred for 30 minutes, then sonicated for 30 minutes, repeating three cycles to obtain a mixed solution. A 20cm*20cm copper plate was placed inside a foam box. A hollow plastic cylindrical mold (3cm tall, 30mm inner diameter, and 36mm outer diameter) was placed on the copper plate (marked at 2cm). Liquid nitrogen was poured into the plate to cool it. The solution in beaker A was then poured into the mold to the 2cm mark. The solution was then rapidly solidified using a directional freezing technique. After the lower layer of solution solidified, the solution in beaker B was quickly poured into the mold to the same height. After the double-layer solution completely solidified, it was placed in a freeze-drying oven and freeze-dried for 72 hours to produce a double-layer latent heat aerogel.

[0056] The aerogel was fixed with foam and placed in a 100ml beaker, with the lower layer of the aerogel immersed in water and the upper layer floating on the water surface. The aerogel was subjected to simulated water evaporation, and the evaporation rate reached 2.99 kg·m under one sun. -2 ·h -1 The evaporation rate can reach 1.78 kg·m within 20 minutes of turning off the light. -2 ·h -1 .

[0057] Example 5

[0058] An aerogel with a mass ratio of 4:1 of composite phase change material EPPC-PW and photothermal conversion material EPC was prepared, and water evaporation under solar light was simulated.

[0059] Weigh 1g of EP powder, 20g of a 5wt.% polyvinyl alcohol (PVA) solution, and 2.5g of a 2wt.% cellulose (MFC) solution into a 25ml beaker A, so that the EP:PVA:MFC wt.% ratio is 20:20:1. Weigh 0.7g of EPC, 7g of a 5wt.% PVA, and 2.275g of a 2wt.% MFC into beaker B, so that the EPC:PVA:MFC wt.% ratio is 15.4:7.7:1. Additionally, weigh 2.8g of EPPC-PW and add it to beaker B, so that the EPPC-PW:EPC ratio is 4:1. The mixed solutions in the two beakers are stirred for 30 minutes, then sonicated for 30 minutes, repeating three cycles to obtain a mixed solution. A 20cm*20cm copper plate was placed inside a foam box. A hollow plastic cylindrical mold (3cm tall, 30mm inner diameter, and 36mm outer diameter) was placed on the copper plate (marked at 2cm). Liquid nitrogen was poured into the plate to cool it. The solution in beaker A was then poured into the mold to the 2cm mark. The solution was then rapidly solidified using a directional freezing technique. After the lower layer of solution solidified, the solution in beaker B was quickly poured into the mold to the same height. After the double-layer solution completely solidified, it was placed in a freeze-drying oven and freeze-dried for 72 hours to produce a double-layer latent heat aerogel.

[0060] The aerogel was fixed with foam and placed in a 100ml beaker, with the lower layer of the aerogel immersed in water and the upper layer floating on the water surface. The aerogel was subjected to simulated water evaporation, and the evaporation rate reached 2.89kg·m under one sun. -2 ·h -1 The evaporation rate can reach 1.53 kg·m within 20 minutes of turning off the light. -2 ·h -1 .

[0061] Through the above five examples, it is found that when the content ratio of the composite phase change material EPPC-PW to the photothermal conversion material is 3:1, the evaporation performance is optimal.

[0062] Any matters not mentioned above shall be subject to the existing technology.

[0063] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in similar ways, but they will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. An expanded perlite-based aerogel structure solar interface evaporator, characterized by: The invention comprises an upper aerogel layer and a lower aerogel layer, wherein the upper aerogel layer is arranged on the upper surface of the lower aerogel layer; the lower aerogel layer is prepared by freeze-drying a mixed solution of expanded perlite powder, polyvinyl alcohol solution, and cellulose solution; and the upper aerogel layer is prepared by freeze-drying a mixed solution of photothermal conversion material, heat storage material, polyvinyl alcohol solution, and cellulose solution. The light-to-heat conversion material is carbonized expanded perlite powder; The heat storage material is a carbonized expanded perlite particle carrier loaded with a phase change material; The carbonized expanded perlite powder is prepared by the following method: adding the expanded perlite powder to a sucrose solution, heating and stirring in a water bath, and then filtering to obtain a block; drying the block and calcining it under an inert gas atmosphere to obtain the carbonized expanded perlite powder; and\or, The carbonized expanded perlite particles are prepared by the following method: dropping a sucrose solution into the expanded perlite particles, vacuum filtering, heating in a water bath, and then filtering to obtain a mixture, drying the mixture and calcining it under an inert gas atmosphere to obtain the carbonized expanded perlite particles.

2. The expanded perlite-based aerogel structure solar interface evaporator according to claim 1, characterized in that: During the preparation of the carbonized expanded perlite powder and the carbonized expanded perlite particles, both were calcined at 800-1100° C. for 2-3 hours under an argon atmosphere.

3. The expanded perlite-based aerogel structure solar interface evaporator according to claim 1, characterized in that: The specific preparation process of the heat storage material is as follows: vacuum filtering the carbonized expanded perlite particles and the phase change material, heating them, and then injecting the phase change material into the pore structure of the carbonized expanded perlite particles by vacuum impregnation.

4. A method for preparing an expanded pearlite-based aerogel structure solar interface evaporator according to any one of claims 1 to 3, characterized in that: The steps include: Stir and mix expanded perlite powder, polyvinyl alcohol solution, and cellulose solution to obtain a lower layer solution; Mixing the photothermal conversion material, the heat storage material, the polyvinyl alcohol solution and the cellulose solution to obtain an upper layer solution; The lower gel solution is poured into the mold and the solution is quickly solidified by directional freezing technology; After the lower layer solution solidifies, the upper layer solution is quickly poured into the mold. After the double-layer solution is completely solidified, it is placed in a freeze drying box for freeze drying to obtain a double-layer latent heat aerogel, namely, an expanded perlite-based aerogel structure solar interface evaporator.

5. The preparation method according to claim 4, wherein: In the lower layer solution, the mass ratio of the expanded perlite powder, polyvinyl alcohol solution, and cellulose solution is 1-2:20-22:2-3; the mass fraction of the polyvinyl alcohol solution is 3-5% and the mass fraction of the cellulose solution is 2-3%.

6. The preparation method according to claim 4, wherein: In the upper solution, the mass ratio of the photothermal conversion material, the heat storage material, the polyvinyl alcohol solution, and the cellulose solution is 0.5-1:2-2.5:6-8:2-2.5; the polyvinyl alcohol solution with a mass fraction of 3-5% and the cellulose solution with a mass fraction of 2-3% are used.

7. An application of the expanded pearlite-based aerogel structure solar interface evaporator according to any one of claims 1 to 3, characterized in that: The lower layer of aerogel is immersed in seawater, and the upper layer of aerogel floats on the surface of the seawater for use in seawater desalination.

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