Multi-level EC-ZP-coated ESi-P solar evaporator based on bionic double-channel structure and preparation method of multi-level EC-ZP-coated ESi-P solar evaporator

Abstract

The invention provides a multi-level EC-ZP-ESi-P solar evaporator based on a bionic double-channel structure and a preparation method thereof.The solar evaporator comprises a photo-thermal conversion layer, a hydrophilic thermal insulation layer and a water conveying column, the photo-thermal conversion layer is arranged on the upper surface of the hydrophilic thermal insulation layer, and the upper end of the water conveying column is connected with the middle of the lower surface of the hydrophilic thermal insulation layer; the water conveying column conveys liquid below to the hydrophilic thermal insulation layer through the capillary action; the preparation method of the photo-thermal conversion layer EC-ZP porous carbon nanofiber membrane comprises the following steps: taking ZIF-8 particles and PAN as raw materials, carrying out electrostatic spinning, and then carrying out high-temperature carbonization; the preparation method of the hydrophilic heat-insulating layer ESi-P nanofiber membrane comprises the following steps: taking SiO2 nanoparticles and PAN as raw materials, and carrying out electrostatic spinning. The EC-ZP-coated ESi-P solar evaporator can effectively prevent salt crystallization from blocking a steam channel, solves the problem of performance degradation caused by salt crystallization in an existing solar evaporation device, improves the photo-thermal conversion efficiency and the water-heat cooperative management capability at the same time, and achieves efficient and sustainable seawater desalination.

Description

Technical field

[0001] The present invention relates to the technical field of solar seawater desalination, and in particular to a multi-level EC-ZP@ESi-P solar evaporator based on a bionic dual-channel structure and a preparation method thereof. [Background Technology]

[0002] Water shortages have become a common challenge facing humanity. The discharge of industrial brine exacerbates the water shortage crisis. These wastewaters and seawater must undergo desalination before they can be used directly. Consequently, various technologies have been developed to produce freshwater, including reverse osmosis (RO), multi-stage flash evaporation (MSF), electrodialysis (ED), and low-temperature multi-effect distillation (LT-MED). However, traditional desalination technologies require significant initial investment in equipment, and their energy consumption exacerbates environmental issues such as the greenhouse effect. In contrast, interfacial evaporation, which relies solely on sustainable solar energy, has emerged as a promising approach for seawater desalination. To date, a variety of materials have been developed for solar interfacial evaporation, including carbon-based materials, metal nanomaterials, and semiconductor materials. This demonstrates the effectiveness of evaporation strategies that achieve larger surface areas and higher photothermal conversion efficiencies. Furthermore, the hydrophilicity of the materials allows water molecules to accumulate on the surface, rapidly transporting seawater to the evaporation interface.

[0003] Salt crystallization during the evaporation process is a major factor affecting the efficiency of solar desalination. Salt precipitation on the evaporator surface affects light absorption and blocks water channels, thereby reducing evaporation efficiency. Current salt tolerance strategies primarily recirculate salt ions back into the bulk water via large-aperture channels. This focuses solely on salt transfer and neglects salt utilization. Proper salt recycling and reuse would not only reduce negative environmental impacts but also achieve a win-win situation for efficient resource utilization and environmental protection.

[0004] In the inventor's previous research (Chinese patent application number 202411354913.3), a preparation method of an integrated, dual-channel PCNFs / ZIF8-SA composite aerogel, its products and applications were disclosed, and the steps are as follows: Step 1, adding sodium alginate SA and ZIF-8 to the PCNFs suspension, stirring until SA is fully dissolved to form a uniform mixed liquid; the PCNFs are hydrophilically modified PAN / ZIF-8 / lignin / NaCl carbon nanofibers; Step 2, pouring the mixed liquid into a mold, placing it in a freeze dryer for directional freezing, and obtaining a composite aerogel columnar structure with a directional channel structure; Step 3, hydrophobically modifying the upper layer of the composite aerogel columnar structure to form a hydrophobic layer with a certain thickness, and the lower layer is a hydrophilic layer, and the hydrophobic layer and the hydrophilic layer are integrated. The Janus structure is integrated and dual-channel PCNFs / ZIF8-SA composite aerogel is prepared by directional freezing technology and wettability control. The design of the Janus hydrophilic and hydrophobic structure prevents salt from forming on the top and allows steam to pass through. Salt is discharged from the side of the composite aerogel, with an evaporation rate of 3.462 kg m -2 h -1 .

[0005] During the subsequent improvement and development process, the inventors' team used the osmotic pressure of bionic clams in seawater to remove impurities from the body. They also used electrospinning and carbonization technology to prepare a multi-level photothermal evaporation device. The porous internal interconnected structure in the evaporation path physically divides the main water into small molecular water clusters, reducing the evaporation enthalpy of water at the evaporation interface. The salt side extraction path, during the evaporation process, causes the salt water concentration difference to be absorbed by the center of the membrane and transferred to the edge of the membrane, maintaining a uniform salt concentration throughout the membrane, resulting in an evaporation rate of up to 4.56 kg m -2 h -1 The solar evaporator has an evaporation rate 32% higher than the previous application. It achieves efficient seawater evaporation rate and salt precipitation and crystallization at the edge of the water transmission layer during the all-weather evaporation process, avoiding evaporation performance attenuation caused by blockage of the photothermal evaporation interface, which is a significant improvement.

[0006] Therefore, a multi-level EC-ZP@ESi-P solar evaporator based on a bionic dual-channel structure and its preparation method are proposed, aiming to solve the performance degradation problem caused by salt crystallization in existing solar evaporation devices, while improving the photothermal conversion efficiency and water-heat coordinated management capabilities, and realizing efficient and sustainable seawater desalination. [Summary of the invention]

[0007] One of the technical problems to be solved by the present invention is to provide a multi-level EC-ZP@ESi-P solar evaporator based on a bionic dual-channel structure, which can effectively prevent the blockage of the steam channel by salt crystallization, thereby improving the evaporation efficiency and cycle stability, solving the performance degradation problem caused by salt crystallization in existing solar evaporation devices, and at the same time improving the photothermal conversion efficiency and water-heat coordinated management capabilities, thereby realizing efficient and sustainable seawater desalination.

[0008] The present invention achieves one of the above-mentioned technical problems by:

[0009] A multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure, comprising a photothermal conversion layer, a hydrophilic insulation layer, and a water delivery column. The photothermal conversion layer is disposed on the upper surface of the hydrophilic insulation layer, and the diameter of the hydrophilic insulation layer is larger than that of the upper photothermal conversion layer. The upper end of the water delivery column is connected to the middle of the lower surface of the hydrophilic insulation layer. The water delivery column transports the liquid below to the middle of the hydrophilic insulation layer through capillary action.

[0010] The photothermal conversion layer is an EC-ZP porous carbon nanofiber membrane, and the hydrophilic heat insulation layer is an ESi-P nanofiber membrane.

[0011] Furthermore, the preparation method of the EC-ZP porous carbon nanofiber membrane of the light-to-heat conversion layer is as follows:

[0012] Ultrafine ZIF-8 particles and polyacrylonitrile (PAN) were used as raw materials, and NaCl-containing solution and DMF solution were used as solvents. The mass ratio of ZIF-8, PAN and saturated NaCl solution was adjusted to (4-6):(3-5):(5.5-6.5), and ultrasonication and stirring were performed to obtain an electrospinning precursor solution.

[0013] The precursor solution is added into a syringe and electrospun to obtain an E-ZP nanofiber membrane with uniform diameter, which is then dried for later use;

[0014] Finally, the E-ZP nanofiber membrane is carbonized at high temperature to obtain the EC-ZP porous carbon nanofiber membrane;

[0015] The preparation method of the hydrophilic insulation layer ESi-P nanofiber membrane is as follows:

[0016] Using hydrophilic SiO2 nanoparticles and polyacrylonitrile (PAN) as raw materials, N,N-dimethylformamide (DMF) solution as solvent, and adjusting the mass ratio of SiO2 nanoparticles to PAN to (1-2):5, ultrasonication and stirring were performed to obtain an electrospinning precursor solution.

[0017] The precursor solution was added into a syringe and electrospinning was performed to obtain an ESi-P nanofiber membrane with uniform diameter.

[0018] Furthermore, in the preparation method of the photothermal conversion layer EC-ZP porous carbon nanofiber membrane: the particle size of the ZIF-8 particles is 40-50 nm; the electrospinning parameters are: a propulsion rate of 0.4-0.6 mL / h and a voltage of 19-21 kV; the high-temperature carbonization conditions are as follows: heating to 280°C in a nitrogen atmosphere at a heating rate of 5°C / min and holding for 2 hours, then heating to 800-1000°C in a nitrogen atmosphere at a heating rate of 5°C / min, and finally cooling to room temperature to obtain the EC-ZP porous carbon nanofiber membrane;

[0019] In the preparation method of the hydrophilic insulation layer ESi-P nanofiber membrane: the particle size of the hydrophilic SiO2 nanoparticles is 40nm~50nm; the electrospinning parameters are: propulsion rate 0.6~0.8mL / h and voltage 16~18kV.

[0020] Furthermore, each of the electrospinning processes obtains an E-ZP nanofiber membrane with a fiber diameter of 150-800 nm, and an ESi-P nanofiber membrane with a fiber diameter of 100-750 nm.

[0021] Furthermore, the solar evaporator further comprises a buoyancy layer, which is located on the lower surface of the hydrophilic insulation layer, and the upper end of the water delivery column passes through the buoyancy layer and is connected to the middle portion of the lower surface of the hydrophilic insulation layer.

[0022] Furthermore, the water delivery column is a cotton core.

[0023] The second technical problem to be solved by the present invention is to provide a preparation method of a multi-level EC-ZP@ESi-P solar evaporator based on a bionic dual-channel structure, which can effectively prevent the blockage of the steam channel by salt crystallization, thereby improving the evaporation efficiency and cycle stability, solving the performance degradation problem caused by salt crystallization in existing solar evaporation devices, and at the same time improving the photothermal conversion efficiency and water-heat coordinated management capabilities, thereby realizing efficient and sustainable seawater desalination.

[0024] The present invention achieves the second of the above technical problems in the following way:

[0025] A method for preparing a multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure, wherein the structure of the solar evaporator is as described above; and the preparation method is as follows:

[0026] Step 1: Preparation of the photothermal conversion layer EC-ZP porous carbon nanofiber membrane:

[0027] Ultrafine ZIF-8 particles and polyacrylonitrile (PAN) were used as raw materials, and NaCl-containing solution and DMF solution were used as solvents. The mass ratio of ZIF-8, PAN and NaCl solution was adjusted to (4-6):(3-5):(5.5-6.5), and ultrasonication and stirring were performed to obtain an electrospinning precursor solution.

[0028] The precursor solution is added into a syringe and electrospun to obtain an E-ZP nanofiber membrane with uniform diameter, which is then dried for later use;

[0029] Finally, the E-ZP nanofiber membrane is carbonized at high temperature to obtain the EC-ZP porous carbon nanofiber membrane;

[0030] Step 2: Preparation of hydrophilic insulation layer ESi-P nanofiber membrane:

[0031] Using hydrophilic SiO2 nanoparticles and polyacrylonitrile (PAN) as raw materials, N,N-dimethylformamide (DMF) solution as solvent, and adjusting the mass ratio of SiO2 nanoparticles to PAN to (1-2):5, ultrasonication and stirring were performed to obtain an electrospinning precursor solution.

[0032] The precursor solution was added into a syringe and electrospun to obtain an ESi-P nanofiber membrane with uniform diameter;

[0033] Step 3: Assembly:

[0034] The prepared EC-ZP porous carbon nanofiber membrane is used as the photothermal conversion layer, and an ESi-P nanofiber membrane is set underneath as a hydrophilic insulation layer. Then, a water delivery column is connected to the middle of the lower surface of the hydrophilic insulation layer to assemble a solar interface evaporator; the water delivery column transports the liquid below to the hydrophilic insulation layer through capillary action.

[0035] Furthermore, in the preparation method of the photothermal conversion layer EC-ZP porous carbon nanofiber membrane: the particle size of the ZIF-8 particles is 40-50 nm; the electrospinning parameters are: a propulsion rate of 0.4-0.6 mL / h and a voltage of 19-21 kV; the high-temperature carbonization conditions are as follows: heating to 280°C in a nitrogen atmosphere at a heating rate of 5°C / min and holding for 2 hours, then heating to 800-1000°C in a nitrogen atmosphere at a heating rate of 5°C / min, and finally cooling to room temperature to obtain the EC-ZP porous carbon nanofiber membrane;

[0036] In the preparation method of the hydrophilic insulation layer ESi-P nanofiber membrane: the particle size of the hydrophilic SiO2 nanoparticles is 40nm~50nm; the electrospinning parameters are: propulsion rate 0.6~0.8mL / h and voltage 16~18kV.

[0037] Furthermore, the solar evaporator also includes a buoyancy layer, which is located on the lower surface of the hydrophilic insulation layer, and the upper end of the water delivery column passes through the buoyancy layer and is connected to the middle of the lower surface of the hydrophilic insulation layer; the water delivery column is a cotton core.

[0038] Furthermore, each of the electrospinning processes obtains an E-ZP nanofiber membrane with a fiber diameter of 150-800 nm, and an ESi-P nanofiber membrane with a fiber diameter of 100-750 nm.

[0039] The present invention has the following advantages:

[0040] 1. The present invention uses PAN as the electrospinning matrix, which has good chemical stability and mechanical properties, as well as certain strength and flexibility; PAN has thermal stability and functional modification capabilities, and can be carbonized within a certain range without thermal decomposition. In addition, the EC-ZP porous carbon nanofiber membrane prepared by high-temperature carbonization pore-making technology has a multi-level pore structure and a rich mesoporous structure for nano-confinement. After the nanofibers are carbonized, ZIF-8 is pyrolyzed to form mesoporous and microporous structures, providing high specific surface area and porosity (specific surface area>300m 2 / g), in which the micropores and mesopores make the main seawater form small clusters of water molecules, reducing the binding force of water, thereby reducing the evaporation enthalpy and increasing the evaporation rate of the evaporator interface.

[0041] 2. The wetting properties of EC-ZP porous carbon nanofiber membrane and ESi-P nanofiber membrane were analyzed. The contact angle of the EC-ZP porous carbon nanofiber membrane surface was 18.8°, indicating that the prepared porous carbon nanofiber surface has good hydrophilicity; and the surface of the ESi-P nanofiber membrane quickly absorbed water within 90ms, indicating that the EC-ZP@ESi-P dual-channel, multi-level solar evaporator has strong overall wetting performance, forming a super-hydrophilic network. At the same time, it has a low thermal conductivity of 0.0396W / m·K, which effectively inhibits heat loss and avoids untimely water supply during the evaporation process, which reduces the evaporation rate.

[0042] 3. Using UV-visible-near-infrared absorption testing, the light absorption rate of the solar evaporator's photothermal conversion layer exceeded 90% within the wavelength range of 250-2500nm, and reached as high as 96% within the visible light range of 400-750nm. This demonstrates that the EC-ZP@ESi-P dual-channel, multi-layer solar evaporator has excellent light absorption performance.

[0043] 4. The EC-ZP@ESi-P solar evaporator was placed under 1 sun intensity and 3.5 wt% salt solution for cycle testing. It can run stably for 20 cycles, and the evaporation rate is always maintained at 4.46-4.58 kg m -2 h-1 , showing negligible degradation, which indicates that the EC-ZP@ESi-P solar evaporator has good stability.

[0044] 5. Most existing evaporators return salt to the main water source through large-aperture channels. This salt-tolerance approach doesn't effectively utilize the salt crystals. However, the present invention allows salt crystals to precipitate at the edges of the evaporator during the solar desalination process, preventing the vaporization channels from being clogged by salt crystals and affecting the evaporation rate. The precipitated salt can also be recovered and purified. This method conserves resources, responds to the call for "scientific resource utilization and green development," and opens up possibilities for developing a resource recycling industry.

[0045] 6. This invention achieves spatial decoupling of water evaporation and salt collection during solar evaporation through bionic design and collaborative innovation of materials, structures, and processes. The modular structure of the EC-ZP@ESi-P solar evaporator is easy to mass-produce and has significant application value in scenarios such as off-grid water supply and offshore platforms.

Brief Description of the Drawings

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0047] Figure 1 This is a structural schematic diagram of a multi-level EC-ZP@ESi-P solar evaporator based on a bionic dual-channel structure of the present invention; wherein 1 is a photothermal conversion layer, 2 is a hydrophilic insulation layer, 3 is a buoyancy layer, and 4 is a water delivery column.

[0048] Figure 2 These are SEM images of the EC-ZP porous carbon nanofiber membrane and the ESi-P nanofiber membrane prepared in the examples of the present invention, where a is the SEM image of the EC-ZP membrane (Example 1); b is the SEM image of the ESi-P membrane (Example 8).

[0049] Figure 3 These are water contact angle diagrams of the EC-ZP porous carbon nanofiber membrane and the ESi-P nanofiber membrane prepared according to the embodiments of the present invention; (a) is the water contact angle diagram of the surface of the ESi-P nanofiber membrane (Example 8); (b) is the water contact angle diagram of the surface of the EC-ZP porous carbon nanofiber membrane (Example 1).

[0050] Figure 4 This is a graph of the evaporation rate of the EC-ZP@ESi-P solar evaporator in an embodiment of the present invention under 1 sun intensity in 3.5 wt% brine.

[0051] Figure 5: This is a side salt crystallization diagram of the EC-ZP@ESi-P solar evaporator in an embodiment of the present invention; wherein a is a macroscopic surface diagram of the EC-ZP@ESi-P solar evaporator before evaporation; b is a macroscopic surface diagram of the EC-ZP@ESi-P solar evaporator after evaporation.

[0052] Figure 6 This is a cyclic stability test chart of the EC-ZP@ESi-P solar evaporator in an embodiment of the present invention under 1 sunlight intensity and 3.5% salt water.

[0053] Figure 7 It is the ultraviolet-visible-near infrared spectrum of the light-to-heat conversion layer prepared in the embodiment of the present invention. [Specific implementation method]

[0054] The following will be combined with the Figure 1-7 The technical solutions of the present invention are clearly and completely described in the following and in detail. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention. If specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0055] Example 1:

[0056] This embodiment provides a method for preparing an optimal EC-ZP porous carbon nanofiber membrane, comprising the following steps:

[0057] ZIF-8 particles (50 nm) and polyacrylonitrile (PAN) were used as raw materials, and a saturated NaCl solution and DMF solution were used as solvents. The weight ratio of ZIF-8, PAN, saturated NaCl solution, and DMF solution was 5:3:6:52. The precursor solution was added to a syringe and stirred under ultrasonication for 24 hours. Electrospinning was performed at a feed rate of 0.6 mL / h and a voltage of 19 kV, adjusting the electrospinning parameters. E-ZP nanofiber membranes with a diameter of approximately 300 nm were obtained and dried at 80°C. Finally, the E-ZP nanofiber membranes were placed in a crucible and carbonized in a tubular furnace. The temperature was raised to 280°C under a nitrogen atmosphere at a rate of 5°C / min and held for 2 hours. The temperature was then raised to 900°C under a nitrogen atmosphere at a rate of 5°C / min. After cooling to room temperature, the EC-ZP porous carbon nanofiber membranes were obtained.

[0058] The SEM image of the EC-ZP porous carbon nanofiber membrane is shown in Figure 2As shown in a, it can be seen from the figure that the ZIF-8 in the fiber undergoes pyrolysis, and the organic components form carbonaceous materials at high temperatures, which are graphitized as a whole. There are many pores inside the fiber, and the internal pores are closed by the carbonized shell on the surface. The pores are connected by the pore walls to obtain cross-linked porous carbonized porous nanofibers, which greatly improves its specific surface area.

[0059] The water contact angle of the EC-ZP porous carbon nanofiber membrane surface is shown in the figure Figure 3 As shown in b, it can be seen from the figure that the water contact angle of the membrane surface is 18.8°, indicating that the surface of the prepared porous carbon nanofiber has good hydrophilicity.

[0060] The light absorption performance of the EC-ZP@ESi-P dual-channel, multi-layer solar evaporator was tested using UV-visible-near-infrared absorption. The light absorption efficiency of the photothermal conversion layer of the solar evaporator of the present invention was greater than 90% within the wavelength range of 250-2500nm, and as high as 96% within the visible light range of 400-750nm (see Figure 7 ). This indicates that the EC-ZP@ESi-P dual-channel, multi-level solar evaporator has excellent light absorption performance.

[0061] Example 2:

[0062] The preparation method of EC-ZP porous carbon nanofibers is the same as that described in Example 1, except that:

[0063] The mass ratio of ZIF-8 was adjusted to 4 to 6, and the other operations and dosages were exactly the same as those in Example 1.

[0064] Example 3:

[0065] The preparation method of EC-ZP porous carbon nanofibers is the same as that described in Example 1, except that:

[0066] The mass proportion of PAN was adjusted to 3-5, and the other operations and dosages were exactly the same as those in Example 1.

[0067] Example 4:

[0068] The preparation method of EC-ZP porous carbon nanofibers is the same as that described in Example 1, except that:

[0069] The mass ratio of the NaCl solution was adjusted to 5.5-6.5, and the other operations and dosages were exactly the same as those in Example 1.

[0070] Example 5:

[0071] The preparation method of EC-ZP porous carbon nanofibers is the same as that described in Example 1, except that:

[0072] The spinning propulsion rate was set to 0.4-0.6 mL / h, and the remaining operations and dosages were exactly the same as those in Example 1.

[0073] Example 6:

[0074] The preparation method of EC-ZP porous carbon nanofibers is the same as that described in Example 1, except that:

[0075] The spinning voltage was set to 16-18 kV, and the remaining operations and dosages were exactly the same as in Example 1.

[0076] Example 7:

[0077] The preparation method of EC-ZP porous carbon nanofibers is the same as that described in Example 1, except that:

[0078] The final carbonization temperature was set at 800-1000° C., and the remaining operations and dosages were exactly the same as those in Example 1.

[0079] Example 8:

[0080] This embodiment provides an ESi-P nanofiber membrane with optimal wettability, and a preparation method thereof comprises the following steps:

[0081] Hydrophilic SiO2 nanoparticles (40-50 nm) and polyacrylonitrile (PAN) were used as raw materials, and N,N-dimethylformamide (DMF) solution was used as the solvent. The mass ratio of SiO2 nanoparticles, PAN, and DMF solution was 2:5:47. Ultrasonic stirring was applied for 12 hours to prepare the electrospinning precursor solution. The precursor solution was added to a 5 mL syringe and electrospun at a propulsion rate of 0.7 mL / h and a voltage of 18 kV by adjusting the electrospinning parameters. ESi-P nanofiber membranes with a diameter of approximately 250 nm were obtained and dried at 80°C for later use.

[0082] The SEM image of the ESi-P nanofiber membrane is shown in Figure 2 As shown in Figure b, it can be seen that the hydrophilic SiO2 nanoparticles are uniformly and densely distributed in PAN electrospinning, and the surface roughness is significantly improved; the water contact angle of the ESi-P nanofiber membrane surface is shown in Figure 2. Figure 3 As shown in a, it can be seen from the figure that the water contact angle of the membrane surface is close to 0°, that is, the surface of the ESi-P nanofiber membrane quickly absorbs water within 90ms, indicating that the EC-ZP@ESi-P dual-channel, multi-level solar evaporator has strong overall wetting performance, avoiding untimely water supply during the evaporation process, which reduces the evaporation rate; the thermal conductivity of the ESi-P nanofiber membrane was measured by the steady-state hot plate method to be 0.0396W / m·K.

[0083] Example 9:

[0084] The preparation method of the ESi-P electrospinning nanofiber membrane is the same as that of Example 8, except that:

[0085] The mass ratio of SiO2 nanoparticles was adjusted to 1-2, and the other operations and dosages were exactly the same as those in Example 8.

[0086] Example 10:

[0087] The preparation method of the ESi-P electrospinning nanofiber membrane is the same as that of Example 8, except that:

[0088] The spinning propulsion rate was set to 0.6-0.8 mL / h, and the remaining operations and dosages were exactly the same as those in Example 8.

[0089] Example 11:

[0090] The preparation method of the ESi-P electrospinning nanofiber membrane is the same as that of Example 8, except that:

[0091] The spinning voltage was set to 16-18 kV, and the remaining operations and dosages were exactly the same as in Example 8.

[0092] Example 12:

[0093] This embodiment provides an assembly method for an EC-ZP@ESi-P dual-channel, multi-level solar evaporator with the highest evaporation rate. The specific structure is as follows: Figure 1 As shown, the assembly process is as follows:

[0094] A solar interfacial evaporator was assembled using the EC-ZP porous carbon nanofibers prepared in Example 1 as the photothermal conversion layer 1 (2×2 cm in area), and the ESi-P nanofiber membrane prepared in Example 8 as the hydrophilic insulation layer 2 (3 cm in diameter). To ensure an adequate water supply, a foam layer was used at the bottom as the buoyancy layer 3, and a 3 mm diameter water wick was installed as the water delivery column 4. This capillary action transported the bulk water to the upper hydrophilic insulation layer 2, ensuring a continuous water supply.

[0095] Example 13:

[0096] In this example, a solar interfacial evaporator was assembled using the EC-ZP porous carbon nanofibers prepared in Example 2 as the photothermal conversion layer 1 (2×2 cm in area), and the ESi-P nanofiber membrane prepared in Example 9 as the hydrophilic insulation layer 2 (3 cm in diameter). Furthermore, to ensure an adequate water supply, a foam layer was used at the bottom as the buoyancy layer 3, and a 3 mm diameter water delivery wick was installed as the water delivery column 4. This capillary action transported the bulk water to the upper hydrophilic insulation layer 2, ensuring a continuous water supply.

[0097] Example 14:

[0098] In this example, a solar interface evaporator was assembled using the EC-ZP porous carbon nanofibers prepared in Example 3 as the photothermal conversion layer 1 (2×2 cm in area), and the ESi-P nanofiber membrane prepared in Example 9 as the hydrophilic insulation layer 2 (3 cm in diameter). Furthermore, to ensure an adequate water supply, a foam layer was used at the bottom as the buoyancy layer 3, and a 3 mm diameter water delivery wick was installed as the water delivery column 4. This capillary action transported the bulk water to the upper hydrophilic insulation layer 2, ensuring a continuous water supply.

[0099] Application Example 1:

[0100] The solar evaporator constructed in Example 12 was used to simulate the desalination of seawater. Figure 4 As shown in Figure 2, under 1 sun intensity and in 3.5 wt% saline, the evaporation rate of the EC-ZP@ESi-P dual-channel, multi-level solar evaporator remains at 4.3892 kg m -2 h -1 ~4.5684kg m -2 h -1 Due to the rapid evaporation of water in the photothermal conversion layer, a salt concentration gradient is formed in the middle water transport layer, and the salt at the edge precipitates from the side of the water transport layer ( Figure 5 The salt collected from the side can be recycled and reused, providing possibilities for the country's green development and resource recycling.

[0101] 6. The solar evaporator constructed in Example 12 was subjected to a cycle stability test. Figure 6 The EC-ZP@ESi-P solar evaporator was placed under 1 sun intensity and 3.5 wt% salt solution for a cycle test. It can run stably for 20 cycles, and the evaporation rate is always maintained at 4.46-4.58 kg m -2 h -1 , showing negligible degradation, which indicates that the EC-ZP@ESi-P solar evaporator has good stability.

[0102] Application Example 2:

[0103] The solar evaporator constructed in Example 13 was used to simulate seawater desalination experiments. Under 1 sun intensity and 3.5 wt% saline water, the evaporation rate of the EC-ZP@ESi-P dual-channel, multi-level solar evaporator was maintained at 3.9842 kg m - 2 h -1 ~4.0582kg m -2 h -1Due to the rapid evaporation of water in the photothermal conversion layer, a salt concentration gradient forms in the middle water transport layer, and salt at the edge precipitates from the side of the water transport layer. The salt collected from the side can be recycled and reused, providing opportunities for national green development and resource recycling.

[0104] Application Example 3:

[0105] The solar evaporator constructed in Example 14 was used to simulate seawater desalination experiments. Under 1 sun intensity and 3.5 wt% saline water, the evaporation rate of the EC-ZP@ESi-P dual-channel, multi-level solar evaporator was maintained at 4.1123 kg m - 2 h -1 ~4.2064kg m -2 h -1 Due to the rapid evaporation of water in the photothermal conversion layer, a salt concentration gradient forms in the middle water transport layer, and salt at the edge precipitates from the side of the water transport layer. The salt collected from the side can be recycled and reused, providing opportunities for national green development and resource recycling.

[0106] In summary, the structure of the EC-ZP@ESi-P solar interface evaporator of the present invention is as follows Figure 1 As shown, the solar evaporation system consists of three main components: a photothermal conversion layer, a hydrophilic insulation layer, and a water column. The functions of each component are as follows: the photothermal conversion layer is a porous carbonized electrospun membrane with high photothermal conversion performance. It can rapidly absorb solar energy and convert it into heat (light absorption rate is 96%). Simultaneously, the bulk water passes through the porous internal interconnecting structure of the photothermal conversion layer and is physically divided into small water clusters, reducing the evaporation enthalpy of water at the evaporation interface. As the fiber heat increases, a large number of water clusters are converted into steam and dissipated upward. The hydrophilic insulation layer is an ESi-P membrane with rapid water transport and high thermal insulation. During the evaporation process, the salt water absorbed by the water column below continuously infiltrates and diffuses to the edge of the membrane, where the salt concentration increases and salt crystals precipitate. Simultaneously, the hydrophilic insulation layer continues to absorb salt water to maintain a constant salt concentration, thus forming a salt concentration gradient. In addition, the buoyancy layer is foam, which makes the evaporation system above float on the water surface; the water delivery column is a cotton core with a diameter of 3mm, which transports the main water under the foam to the middle of the upper hydrophilic insulation layer through the capillary action of the cotton core.

[0107] This invention uses an electrospinning process to prepare EC-ZP porous carbon nanofiber membranes and ESi-P nanofiber membranes, interweaving the fibers into a continuous nanoscale network structure. The EC-ZP porous carbon nanofiber membrane forms a nanofiber membrane with a high specific surface area (average pore diameter of 2.53 nm in the pore size distribution diagram and a specific surface area of 345.7084 m2 / g) and porosity. Nanofiber membranes designed with fiber functionalization offer distinct advantages in solar evaporators, leveraging the strengths of each material layer and optimizing the overall performance of the evaporator. To improve the efficiency of solar desalination and enhance its performance in actual seawater, this invention fabricated a multi-stage EC-ZP@ESi-P solar evaporator with high photothermal conversion, side salt extraction, and dual-channel synergy for solar desalination by regulating electrospinning and carbonization processes. This dual-channel biomimetic structure draws on the mechanism of clams, which expel impurities through osmotic pressure, to innovatively separate the evaporation channel from the salt discharge channel, solving the problem of salt crystallization clogging in traditional interfacial evaporators while simultaneously enabling salt resource recovery, in line with the concept of a circular economy.

[0108] It can be seen that the solar evaporator of the present invention adopts a gradient functional layered structure, and constructs a heat-water-salt management system through the synergistic effect of three layers of materials. The top layer EC-ZP porous carbon nanofiber membrane (photothermal conversion layer) → the middle layer ESi-P nanofiber membrane (water transport / insulation layer) → the bottom layer foam / cotton core (water supply / floating layer) realizes functional modular integration. The EC-ZP porous carbon nanofiber membrane obtained by carbonization electrospinning is controlled by microstructure (can reach 96% light absorption rate) and macropore structure design (specific surface area>300m 2 / g), achieving full-spectrum solar energy capture and localized thermal effects. The introduction of SiO2 nanoparticles (50-100 nm) into the ESi-P nanofiber membrane, produced by electrospinning in the middle layer, results in a surface contact angle close to 0°, forming a super-hydrophilic network. This membrane also exhibits a low thermal conductivity of 0.0396 W / m·K, effectively suppressing heat loss.

[0109] In summary, the solar evaporator of the present invention adopts a dual-channel design, including a seawater evaporation channel and a salt side extraction channel. This dual-channel biomimetic structure is derived from the principle that clams use osmotic pressure to expel impurities from the side of their bodies in salt water. This effectively prevents salt crystals from blocking the steam channel, thereby improving evaporation efficiency and cycle stability. In addition, the spatial structure design of the dual-channel evaporation not only achieves a high solar evaporation rate, but also can collect the precipitated salt from the side channel. This not only further improves the stability of the evaporator, but also realizes resource reuse, meets the national green development requirements, and provides new possibilities for the development of the resource recycling industry.

[0110] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure, characterized by: The solar evaporator includes a photothermal conversion layer, a hydrophilic insulation layer, and a water delivery column. The photothermal conversion layer is arranged on the upper surface of the hydrophilic insulation layer, and the diameter of the hydrophilic insulation layer is larger than that of the upper photothermal conversion layer. The upper end of the water delivery column is connected to the middle of the lower surface of the hydrophilic insulation layer. The water delivery column transports the liquid below to the middle of the hydrophilic insulation layer through capillary action. The photothermal conversion layer is an EC-ZP porous carbon nanofiber membrane, and the hydrophilic heat insulation layer is an ESi-P nanofiber membrane.

2. The multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure according to claim 1, characterized in that: The preparation method of the EC-ZP porous carbon nanofiber membrane of the light-to-heat conversion layer is as follows: Ultrafine ZIF-8 particles and polyacrylonitrile (PAN) were used as raw materials, and NaCl-containing solution and DMF solution were used as solvents. The mass ratio of ZIF-8, PAN and saturated NaCl solution was adjusted to (4-6):(3-5):(5.5-6.5), and ultrasonication and stirring were performed to obtain an electrospinning precursor solution. The precursor solution is added into a syringe and electrospun to obtain an E-ZP nanofiber membrane with uniform diameter, which is then dried for later use; Finally, the E-ZP nanofiber membrane is carbonized at high temperature to obtain the EC-ZP porous carbon nanofiber membrane; The preparation method of the hydrophilic insulation layer ESi-P nanofiber membrane is as follows: Using hydrophilic SiO2 nanoparticles and polyacrylonitrile (PAN) as raw materials, N,N-dimethylformamide (DMF) solution as solvent, and adjusting the mass ratio of SiO2 nanoparticles to PAN to (1-2):5, ultrasonication and stirring were performed to obtain an electrospinning precursor solution. The precursor solution was added into a syringe and electrospinning was performed to obtain an ESi-P nanofiber membrane with uniform diameter.

3. The multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure according to claim 2, characterized in that: In the preparation method of the photothermal conversion layer EC-ZP porous carbon nanofiber membrane, the particle size of the ZIF-8 particles is 40-50 nm; the electrospinning parameters are: a propulsion rate of 0.4-0.6 mL / h and a voltage of 19-21 kV; the high-temperature carbonization conditions are as follows: heating to 280°C at a heating rate of 5°C / min in a nitrogen atmosphere and holding for 2 hours, then heating to 800-1000°C at a heating rate of 5°C / min in a nitrogen atmosphere, and finally cooling to room temperature to obtain the EC-ZP porous carbon nanofiber membrane; In the preparation method of the hydrophilic insulation layer ESi-P nanofiber membrane: the particle size of the hydrophilic SiO2 nanoparticles is 40nm~50nm; the electrospinning parameters are: propulsion rate 0.6~0.8mL / h and voltage 16~18kV.

4. The multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure according to claim 2, characterized in that: The electrospinning method can obtain an E-ZP nanofiber membrane with a fiber diameter of 150-800 nm and an ESi-P nanofiber membrane with a fiber diameter of 100-750 nm.

5. The multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure according to claim 1, characterized in that: The solar evaporator further comprises a buoyancy layer, which is located on the lower surface of the hydrophilic insulation layer, and the upper end of the water delivery column passes through the buoyancy layer and is connected to the middle of the lower surface of the hydrophilic insulation layer.

6. The multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure according to claim 1, characterized in that: The water delivery column is a cotton core.

7. A method for preparing a multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure, characterized by: The structure of the solar evaporator is as described in claim 1; the preparation method is as follows: Step 1: Preparation of the photothermal conversion layer EC-ZP porous carbon nanofiber membrane: Ultrafine ZIF-8 particles and polyacrylonitrile (PAN) were used as raw materials, and NaCl-containing solution and DMF solution were used as solvents. The mass ratio of ZIF-8, PAN and NaCl solution was adjusted to (4-6):(3-5):(5.5-6.5), and ultrasonication and stirring were performed to obtain an electrospinning precursor solution. The precursor solution is added into a syringe and electrospun to obtain an E-ZP nanofiber membrane with uniform diameter, which is then dried for later use; Finally, the E-ZP nanofiber membrane is carbonized at high temperature to obtain the EC-ZP porous carbon nanofiber membrane; Step 2: Preparation of hydrophilic insulation layer ESi-P nanofiber membrane: Using hydrophilic SiO2 nanoparticles and polyacrylonitrile (PAN) as raw materials, N,N-dimethylformamide (DMF) solution as solvent, and adjusting the mass ratio of SiO2 nanoparticles to PAN to (1-2):5, ultrasonication and stirring were performed to obtain an electrospinning precursor solution. The precursor solution was added into a syringe and electrospun to obtain an ESi-P nanofiber membrane with uniform diameter; Step 3: Assembly: The prepared EC-ZP porous carbon nanofiber membrane is used as the photothermal conversion layer, and an ESi-P nanofiber membrane is set underneath as a hydrophilic insulation layer. Then, a water delivery column is connected to the middle of the lower surface of the hydrophilic insulation layer to assemble a solar interface evaporator; the water delivery column transports the liquid below to the hydrophilic insulation layer through capillary action.

8. The method for preparing a multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure according to claim 7, characterized in that: In the preparation method of the photothermal conversion layer EC-ZP porous carbon nanofiber membrane, the particle size of the ZIF-8 particles is 40-50 nm; the electrospinning parameters are: a propulsion rate of 0.4-0.6 mL / h and a voltage of 19-21 kV; the high-temperature carbonization conditions are as follows: heating to 280°C at a heating rate of 5°C / min in a nitrogen atmosphere and holding for 2 hours, then heating to 800-1000°C at a heating rate of 5°C / min in a nitrogen atmosphere, and finally cooling to room temperature to obtain the EC-ZP porous carbon nanofiber membrane; In the preparation method of the hydrophilic insulation layer ESi-P nanofiber membrane: the particle size of the hydrophilic SiO2 nanoparticles is 40nm~50nm; the electrospinning parameters are: propulsion rate 0.6~0.8mL / h and voltage 16~18kV.

9. The method for preparing a multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure according to claim 7, characterized in that: The solar evaporator also includes a buoyancy layer, which is located on the lower surface of the hydrophilic insulation layer, and the upper end of the water delivery column passes through the buoyancy layer and is connected to the middle of the lower surface of the hydrophilic insulation layer; the water delivery column is a cotton core.

10. The method for preparing a multi-level EC-ZP@ESi-P solar evaporator based on a biomimetic dual-channel structure according to claim 7, characterized in that: The electrospinning method can obtain an E-ZP nanofiber membrane with a fiber diameter of 150-800 nm and an ESi-P nanofiber membrane with a fiber diameter of 100-750 nm.

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