Biomimetic bundled fiber evaporator and preparation method and application thereof

Abstract

This invention discloses a biomimetic bundled fiber evaporator, its preparation method, and its application, belonging to the field of solar interface evaporation water treatment technology. The evaporator includes a bundled fiber core formed by binding C-shaped or Y-shaped cross-section fibers or multi-twisted cotton threads with binding straps; a tannic acid-iron ion complex or MXene superhydrophilic photothermal coating coated on its surface; a hydrophobic thin layer of polydimethylsiloxane or polymethylhydrosilane sprayed onto the upper side of the evaporator; and an insulating float for buoyancy. This invention's biomimetic bundled fiber structure, inspired by enoki mushrooms, replaces the traditional ice template method with simple physical constraints, resulting in a simple, rapid, and low-cost preparation process. This structure achieves efficient, low-resistance water transport and excellent thermal localization effects. Experiments show that the evaporator can achieve a pure water evaporation rate of 2.43~2.82 kg·m³ under one day of sunlight. ‑2 ·h ‑1 It also has excellent evaporation performance and long-term stability, and can be widely used in seawater desalination, high-salt wastewater treatment and other fields.

Description

Technical Field

[0001] This invention belongs to the field of solar interface evaporation water treatment technology, specifically relating to a bundled fiber evaporator with a biomimetic enoki mushroom structure, its preparation method, and its application in seawater desalination, high-salt wastewater treatment, and other fields. Background Technology

[0002] Seawater desalination, especially solar-driven interfacial evaporation technology, is an effective approach for seawater desalination, high-salinity wastewater treatment, and clean water production due to its sustainability and low energy consumption. It purifies water by locally heating the water layer at the air-water interface using photothermal materials, thereby treating the steam. Among these technologies, vertical channel evaporators have attracted significant attention due to their low water transport resistance and excellent water-heat balance control capabilities. The vertically arranged channels rapidly transport water to the evaporation interface via capillary force, while minimizing heat loss to the lower water body, thus improving energy utilization efficiency and demonstrating superior water-heat balance control capabilities.

[0003] Currently, the mainstream method for constructing vertical channel structures is the ice template method (directional freezing method), which utilizes the directional growth of ice crystals to form vertical channels, followed by freeze-drying to remove the ice crystals. However, this method has significant drawbacks: 1) long preparation cycle (usually requiring 24-48 hours of freeze-drying) and high energy consumption; 2) reliance on expensive equipment, making large-scale production difficult; 3) difficulty in controlling the uniformity of the channel structure and poor batch repeatability; 4) low mechanical strength of the resulting material, making it prone to collapse.

[0004] In nature, gold needles exhibit a typical bundled fiber structure: multiple slender fibers are tightly bound together to form a vertically oriented bundle, creating numerous capillary channels between the fibers, enabling efficient water transport. Therefore, the development of a biomimetic vertical channel evaporator that is simple to manufacture, low in cost, easy to scale up, and structurally stable has significant practical value. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to overcome the deficiencies of existing technologies and provide a biomimetic bundled fiber evaporator, its preparation method, and its applications. This evaporator draws inspiration from the bundled fiber structure of enoki mushrooms, replacing the complex ice template process with simple binding and assembly, achieving efficient, low-resistance water transport and excellent photothermal evaporation performance. Furthermore, the preparation process is rapid, low-cost, and scalable.

[0006] Specifically, this invention selects fibers with specific cross-sectional shapes (C-shaped, Y-shaped cross-section fibers or multi-twisted cotton threads), assembles them into a vertical bundle structure using a simple thread binding method, and then constructs a superhydrophilic photothermal coating to prepare a biomimetic enoki mushroom bundled fiber evaporator, achieving high-efficiency solar evaporation performance; avoiding the complex process of the traditional ice template method, and achieving low-cost, scalable preparation.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On one hand, the present invention proposes a biomimetic bundled fiber evaporator, comprising: A bundled fiber core, wherein the bundled fiber core is formed by binding multiple fibers together by at least one binding member; the fibers are selected from irregular cross-section fibers with surface groove structure or fiber filaments with twisted structure. A superhydrophilic photothermal coating is applied to at least a portion of the surface of the bundled fiber core; the superhydrophilic photothermal coating is a tannic acid-iron ion complex coating (TA-Fe). 3+ ) or MXene coating, giving the fiber superhydrophilicity and photothermal conversion capability; A surface hydrophobic layer (thermal localization enhancement layer) is sprayed onto the upper evaporation end surface of the evaporator (the evaporation end surface exposed to air); the material of the surface hydrophobic layer is polydimethylsiloxane or polymethylhydrosilane; the thickness of the surface hydrophobic layer is 10~50 μm, used to reduce heat radiation and convection loss, and achieve thermal localization enhancement. An insulating float is connected to a bundled fiber core, which is embedded in the insulating float (such as polyurethane foam or polystyrene foam) to make the evaporator float on the water surface. The upper end of the fiber is exposed to the air for evaporation, and the lower end contacts the water body for water supply.

[0008] Furthermore, the irregular cross-section fiber with surface groove structure is a C-shaped cross-section fiber or a Y-shaped cross-section fiber; the fiber thread with twisted structure is a multi-twisted cotton thread.

[0009] Furthermore, the binding element is a binding strap; the diameter of the single filament of the fiber is 50~400µm; the height of the bundled fiber core is 1~3cm. The fiber bundle is first fully filled with a circular ring with an inner diameter of 5cm for pre-binding to ensure the uniformity of the fiber quantity, and then bound to a cylindrical shape with a diameter of 3cm using binding straps, and then cut into different heights (1~3cm); the width of the binding strap is 2~5mm, and the spacing between the binding straps (i.e., the center distance between adjacent binding straps) is 2~4mm.

[0010] Furthermore, the thickness of the hydrophobic thin layer on the surface is 10~50μm, and it is formed by spraying a hexane solution of polydimethylsiloxane or polymethylhydrosilane with a concentration of 2~5mg / mL.

[0011] Furthermore, the insulating float is a foam board, and the bundled fiber core penetrates vertically through the foam board.

[0012] When the bundled fiber evaporator of the present invention is in use, the vertical capillary channels formed by the bundled fibers rapidly transport water to the evaporation interface. The super-hydrophilic photothermal coating absorbs sunlight and converts it into heat energy. The hydrophobic thin layer on the surface further reduces heat loss at the evaporation interface and enhances the thermal localization effect. The three work together to achieve efficient solar evaporation.

[0013] On the other hand, the present invention also proposes a method for preparing the biomimetic bundled fiber evaporator as described above, comprising the following steps: S1: Assemble the bundled fiber core: Select multiple fibers, bundle them together, and fix them with one or more binding members to form a bundled structure with vertically oriented capillary channels, and cut it to a predetermined height; the fibers are selected from irregular cross-section fibers with surface groove structure or fiber filaments with twisted structure; S2: Constructing a superhydrophilic photothermal coating: obtained by one of the following methods: Method 1 (TA-Fe) 3+ Complex coating): The bundled fiber core obtained in step S1 is sequentially immersed in tannic acid solution and ferric chloride solution to form TA-Fe 3+ A complex coating is applied to create a superhydrophilic photothermal coating on its surface. Method 2 (MXene coating): The bundled fiber core obtained in step S1 is first immersed in a polyvinyl alcohol solution and then immersed in an MXene suspension to form an MXene coating, thereby forming a superhydrophilic photothermal coating on its surface. S3: Constructing a surface hydrophobic layer (thermal localization reinforcement layer): Spray a hydrophobic material solution onto the upper surface of the bundled fiber core after step S2 treatment, and form a surface hydrophobic layer after drying; S4: Assemble the evaporator: Combine the bundled fiber core treated in step S3 with the insulating float. The bundled fiber core passes vertically through the insulating float (its thickness is equal to or slightly thinner than the height of the bundled fiber, so that both ends of the bundled fiber are exposed on the surface of the insulating float). The insulating float allows the evaporator to float on the water surface, with the lower end of the fiber in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0014] Further, step S1 specifically involves selecting one or more of C-shaped cross-section fibers, Y-shaped cross-section fibers, or multi-twist cotton yarn, with a single filament diameter of 50-400µm. The fibers are fully packed into a circular ring with an inner diameter of 5cm, ensuring a tight and uniform arrangement (based on filling the 5cm ring). Then, the fiber bundle is bound into a cylindrical shape with a diameter of 3cm using binding straps. The binding straps are 2-5mm wide, and the spacing between adjacent binding straps is 2-4mm. Finally, the bound fiber bundle is cut to the desired height (1-3cm) to obtain the bundled fiber core.

[0015] Further, Method 1 specifically involves: immersing the bundled fibers in an aqueous solution of tannic acid, wherein the concentration of tannic acid is 0.5~4 mg / mL, soaking for 5~30 minutes, then removing them and immersing them in an aqueous solution of ferric chloride pentahydrate (FeCl3·5H2O), wherein the concentration of (FeCl3·5H2O) is determined based on the ratio of tannic acid to Fe... 3+ Prepare a solution with a molar ratio of 1:1 to 1:4, soak for 5 to 30 minutes to form TA-Fe. 3+ Complex coating. This can be repeated 1-3 times to increase coating load. Finally, rinse with deionized water and dry at 40-80°C.

[0016] Furthermore, Method Two specifically involves: first immersing the bundled fibers in a 2 g / L polyvinyl alcohol (PVA1799) aqueous solution for 10 minutes, then pre-drying them at 40-60°C for 5-10 minutes. Then, immersing them in MXene (Ti3C2T...) x The MXene suspension is prepared at a concentration of 2-5 mg / mL and soaked for 3-10 minutes. After removal, it is dried at 40-80℃.

[0017] Further, step S3 specifically involves: preparing the spraying solution: selecting one of polydimethylsiloxane (PDMS) or polymethylhydrosilane, dissolving it in n-hexane to prepare a spraying solution with a concentration of 2-5 mg / mL. The amount of the crosslinking agent, dibutyltin dilaurate, is one-tenth of the amount of silane. Using a spray gun, the spraying solution is evenly sprayed onto the upper side of the evaporator (i.e., the evaporation end surface exposed to air), with a spraying volume of 1-3 mL, forming a uniform hydrophobic thin layer. After spraying, it is dried at 40-80℃ for 10-30 minutes.

[0018] The invention utilizes the bundled assembly of single fibers to form a vertical channel for efficient water transport. By combining the hydrophilicity and photothermal conversion advantages of MXene, a low-cost, easily expandable, and salt-shedding-resistant solar evaporator has been developed, significantly improving photothermal efficiency and long-term stability.

[0019] Thirdly, the present invention also proposes the application of the biomimetic bundled fiber evaporator as described above or the biomimetic bundled fiber evaporator prepared by the method described above in solar interface evaporation water treatment, wherein the water treatment includes seawater desalination or high-salt wastewater treatment.

[0020] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. Breaking through the limitations of traditional processes, achieving rapid, low-cost, and scalable preparation: This invention abandons the energy-intensive and time-consuming ice template method, eliminating the need for directional freezing and freeze-drying. Instead, it adopts commercially available fiber materials (such as C / Y-shaped fibers and multi-twisted cotton yarn) and a simple "fill-bind-cut" process, which can complete the preparation of evaporators in a few hours, significantly reducing equipment and time costs and making it suitable for large-scale production.

[0021] 2. Biomimetic structural design achieves superior water transport performance: Inspired by the bundled fiber structure of enoki mushrooms, this invention uses binding straps to bundle multiple fibers with special cross-sections (C / Y shape) or twisted structures to form vertically oriented capillary channels. The natural grooves and gaps between the fibers form ordered, vertical micron-level capillary channels. Compared to traditional circular solid fiber bundles, this design provides higher capillary porosity and lower water transport resistance, achieving rapid and efficient bulk water supply and ensuring continuous wetting of the evaporation interface.

[0022] 3. The synergistic effect of the hydrophilic-hydrophobic dual-layer coating achieves efficient energy utilization: Superhydrophilic photothermal coating: TA-Fe 3+ Complexes or MXene materials not only possess broad-spectrum, highly efficient light absorption and photothermal conversion capabilities, but their superhydrophilicity (nearly 0° contact angle) ensures continuous water transfer from the bottom to the top of the evaporator. The superhydrophilic photothermal coating absorbs sunlight and converts it into heat energy, thereby generating steam.

[0023] Upper hydrophobic thin layer: A 10-50 μm hydrophobic layer (such as PDMS) is cleverly constructed on the upper evaporation surface to effectively suppress heat loss from the evaporation interface to the ambient air via radiation and convection. Simultaneously, the thin layer isolates the direct heat conduction path between the evaporation end and the water below, localizing heat on the evaporation surface and significantly improving photothermal conversion efficiency. At the same time, this thin layer does not obstruct the passage of water vapor. This synergistic effect of the "lower layer for water supply / heat absorption, upper layer for insulation" dual-layer structure achieves superior water-heat balance. Both coating preparation methods are simple, low-cost, and environmentally friendly.

[0024] 4. Excellent evaporation performance and long-term stability: Experimental data show that the evaporator of this invention can achieve a pure water evaporation rate of 2.43~2.82 kg·m³ under one standard solar radiation intensity. -2 ·h -1 In some embodiments, the performance is even higher. Meanwhile, the mechanical strength of the fiber material, the structural stability of the binding and fixing, and the strong bond between the coating and the substrate ensure that the evaporator can be used floatingly for a long time without significant performance degradation.

[0025] 5. Good water-heat balance: The vertical channel confines the water inside the fiber, reducing heat loss through conduction to the water below; at the same time, the bundled fiber height (1~3cm) can optimize the heat localization effect, with the highest evaporation efficiency at a height of 2.5cm.

[0026] 6. Raw materials are readily available and environmentally friendly: the fibers, binding straps, and TA-Fe used are all readily available. 3+ The raw materials, such as tannic acid (a natural product), MXene, and PDMS, are all commercial products or can be obtained through simple synthesis. The preparation process is mainly carried out in water or low-toxicity solvents (n-hexane), which is in line with the concept of green chemistry. Attached Figure Description

[0027] Figure 1 (a) A schematic diagram of the structure of the biomimetic bundled fiber evaporator provided in Embodiment 1 of the present invention and (b) A photograph of the actual product.

[0028] Figure 2 These are infrared thermal imaging comparison photos of the evaporators of Embodiment 1 and Comparative Example 2 under dry and wet conditions.

[0029] Figure 3 The diagrams show the changes in water contact angle of the evaporator in Example 1 of the present invention in (a) its original state, (b) after the construction of the photothermal coating, and (c) after the spraying of the hydrophobic layer; as well as the water contact angle diagrams in Examples 2 (d) and 3 (e) after the spraying of the hydrophobic layer.

[0030] Figure 4 Schematic diagrams of evaporator cross-sections composed of fibers with different cross-sections: (a) circular fibers, (b) C-shaped fibers, (c) Y-shaped fibers, and (d) multi-twisted cotton yarn. Compared to circular cross-section fibers, shaped fibers and multi-twisted fibers, due to their grooved structure, can generate more vertical water channels, promoting water transport and helping to improve evaporation efficiency.

[0031] Figure 5 The figures show (a) mass loss curves and (b) water evaporation rate graphs of the evaporator in Embodiment 1 of the present invention under different solar radiation intensities. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0033] Example 1

[0034] This embodiment provides a biomimetic bundled fiber evaporator and its preparation method.

[0035] S1: Bundled fiber assembly Y-shaped cross-section polypropylene fibers (monofilament diameter 50 µm) were selected and fully filled into a circular ring with an inner diameter of 5 cm until no more could be filled, ensuring consistent filling density in each batch of fiber bundles. Using 3 mm wide polyester binding tape, the filled fiber bundles were bound into a 3 cm diameter cylinder, with a center-to-center distance of 3 mm between adjacent binding tapes. Finally, a cut height of 2.5 cm was made to obtain the bundled fiber core.

[0036] S2: Constructing TA-Fe 3+ Superhydrophilic photothermal coating Prepare a 3 mg / mL aqueous solution of tannic acid. Prepare an aqueous solution of FeCl3·5H2O, controlling the reaction between tannic acid and Fe. 3+ The molar ratio is 1:3. The bundled fiber core obtained from S1 is moistened with ethanol, then immersed in a tannic acid solution for 15 minutes, removed, and then immersed in a FeCl3 solution for 15 minutes, causing a dark TA-Fe coating to form on the fiber surface. 3+ Coordination coating. After removal, rinse three times with deionized water and dry in a 60°C oven for 2 hours.

[0037] S3: Construct a surface hydrophobic layer Preparation of the spraying solution: Dissolve polydimethylsiloxane (PDMS) in n-hexane to prepare a solution with a concentration of 3 mg / mL, and add dibutyltin dilaurate (1 / 10 by mass of PDMS) as a crosslinking agent. Use a handheld spray gun to evenly spray the solution onto the upper surface of the evaporator obtained in S2, with a spray volume of 1 mL. After spraying, dry at 80℃ for 20 min.

[0038] S4: Assemble the evaporator The S3-treated bundled fiber core is vertically passed through the central hole of a 1 cm thick polystyrene foam board (insulating float), with the upper end of the fiber protruding from the foam board by about 0.3 cm and the lower end protruding by about 1.2 cm. The foam board allows the evaporator to float on the water surface, with the lower end in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0039] Performance testing:

[0040] All evaporation experiments were conducted at approximately 25°C and approximately 50% humidity. The water contact angle of the evaporator was 0° (superhydrophilic) after the hydrophilic coating (after step S2 treatment) and 128±1° (hydrophobic) after the hydrophilic silane coating (after step S3 treatment).

[0041] The temperature of the evaporator was tested using a solar-powered simulated xenon lamp under dry and wet conditions. The temperature was 92.1°C in the dry condition and 49.5°C in the wet condition.

[0042] Figure 5 The figures for (a) mass loss curve and (b) water evaporation rate graph of the evaporator in Embodiment 1 of the present invention under different solar irradiance intensities are shown. In complete darkness, the evaporation rate of this evaporator is 0.5 kg·m³. -2 ·h -1 At 0.5, 1.0, 1.5, and 2.5 kW·m -2 Under solar irradiation, the evaporation rates of the pure water system reached 2.03, 2.82, 3.25, and 3.65 kg·m³, respectively. -2 ·h -1 After 10 hours of continuous operation, the evaporation rate remained stable with no significant decrease.

[0043] like Figure 1 The diagram shows (a) a schematic diagram and (b) a photograph of the biomimetic bundled fiber evaporator provided in Example 1.

[0044] Examples 2-7: Referring to the process of Example 1, the fiber type, size, coating parameters, hydrophobic layer material, etc. are changed as follows.

[0045] Example 2

[0046] This embodiment provides a biomimetic bundled fiber evaporator and its preparation method.

[0047] S1: Bundled fiber assembly Select C-shaped cross-section polypropylene fibers (monofilament diameter 100 µm) and fill them thoroughly into a 5 cm inner diameter circular ring until no more can be filled, ensuring consistent filling density for each batch of fiber bundles. Use 2 mm wide polyester binding tape to bind the filled fiber bundles into a 3 cm diameter cylinder, with a center-to-center distance of 2 mm between adjacent binding tapes. Finally, cut to a height of 2.5 cm to obtain the bundled fiber core.

[0048] S2: Constructing TA-Fe 3+ Superhydrophilic photothermal coating Prepare a 2 mg / mL aqueous solution of tannic acid. Prepare an aqueous solution of FeCl3·5H2O, controlling the reaction between tannic acid and Fe. 3+ The molar ratio is 1:3. The bundled fiber core obtained from S1 is moistened with ethanol, then immersed in tannic acid solution for 15 min, removed, and then immersed in FeCl3 solution for 15 min, causing a dark TA-Fe coating to form on the fiber surface. 3+ Coordination coating. After removal, rinse three times with deionized water and dry in a 60°C oven for 2 hours.

[0049] S3: Construct a surface hydrophobic layer Preparation of the spraying solution: Dissolve polydimethylsiloxane (PDMS) in n-hexane to prepare a solution with a concentration of 4 mg / mL, and add dibutyltin dilaurate (1 / 10 by mass of PDMS) as a crosslinking agent. Use a handheld spray gun to evenly spray the solution onto the upper surface of the evaporator obtained in S2, with a spray volume of 1.5 mL. After spraying, dry at 80℃ for 20 min.

[0050] S4: Assemble the evaporator The S3-treated bundled fiber core is vertically passed through the central hole of a 1 cm thick polystyrene foam board (insulating float), with the upper end of the fiber protruding from the foam board by about 0.3 cm and the lower end protruding by about 1.2 cm. The foam board allows the evaporator to float on the water surface, with the lower end in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0051] Performance testing:

[0052] The dry temperature is 90.1℃, the wet temperature is 49.8℃, and the surface water contact angle is 133±1°. (The last sentence appears to be incomplete and possibly refers to a solar radiation level of 1 kW·m³.) -2 Under irradiation, the evaporation rate of the pure water system reached 2.43 kg·m³. -2 ·h -1 After 10 hours of continuous operation, the evaporation rate remained stable with no significant decrease.

[0053] Example 3

[0054] This embodiment provides a biomimetic bundled fiber evaporator and its preparation method.

[0055] S1: Bundled fiber assembly Y-shaped cross-section polypropylene fibers (monofilament diameter 400 µm) were selected and fully filled into a circular ring with an inner diameter of 5 cm until no more could be filled, ensuring consistent filling density for each batch of fiber bundles. Using 3 mm wide polyester binding tape, the filled fiber bundles were bound into a 3 cm diameter cylinder, with a center-to-center distance of 4 mm between adjacent binding tapes. Finally, a cut height of 2.5 cm was made to obtain the bundled fiber core.

[0056] S2: Constructing TA-Fe 3+ Superhydrophilic photothermal coating Prepare a 2 mg / mL aqueous solution of tannic acid. Prepare an aqueous solution of FeCl3·5H2O, controlling the reaction between tannic acid and Fe. 3+ The molar ratio is 1:3. The bundled fiber core obtained from S1 is moistened with ethanol, then immersed in tannic acid solution for 15 min, removed, and then immersed in FeCl3 solution for 15 min, causing a dark TA-Fe coating to form on the fiber surface. 3+ Coordination coating. After removal, rinse three times with deionized water and dry in a 60°C oven for 2 hours.

[0057] S3: Construct a surface hydrophobic layer Preparation of the spraying solution: Dissolve polydimethylsiloxane (PDMS) in n-hexane to prepare a solution with a concentration of 5 mg / mL, and add dibutyltin dilaurate (1 / 10 by mass of PDMS) as a crosslinking agent. Use a handheld spray gun to evenly spray the solution onto the upper surface of the evaporator obtained in S2, with a spray volume of 1 mL. After spraying, dry at 80℃ for 20 min.

[0058] S4: Assemble the evaporator The S3-treated bundled fiber core is vertically passed through the central hole of a 1 cm thick polystyrene foam board (insulating float), with the upper end of the fiber protruding from the foam board by about 0.3 cm and the lower end protruding by about 1.2 cm. The foam board allows the evaporator to float on the water surface, with the lower end in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0059] Performance testing:

[0060] The dry temperature is 93.4℃, the wet temperature is 48.3℃, the surface water contact angle is 130±1°, and the evaporation rate is 2.65 kg·m³ under one solar irradiation. -2 ·h -1 After running continuously for 10 hours, the evaporation rate remained stable with no significant decrease.

[0061] Example 4

[0062] This embodiment provides a biomimetic bundled fiber evaporator and its preparation method.

[0063] S1: Bundled fiber assembly Y-shaped cross-section polypropylene fibers (monofilament diameter 50 µm) were selected and fully filled into a circular ring with an inner diameter of 5 cm until no more could be filled, ensuring consistent filling density for each batch of fiber bundles. Using 3 mm wide polyester binding tape, the filled fiber bundles were bound into a 3 cm diameter cylinder, with a center-to-center distance of 3 mm between adjacent binding tapes. Finally, a 1.5 cm cut was made to obtain the bundled fiber core.

[0064] S2: Constructing an MXene photothermal coating Prepare a 2 g / L PVA1799 aqueous solution, soak the bundled fibers for 10 min, then remove and pre-dry at 50℃ for 8 min. Prepare MXene (Ti3C2T) solution. x A suspension with a concentration of 3 mg / mL was prepared. The fibers were immersed in the suspension for 5 minutes, then removed and dried at 60°C.

[0065] S3: Construct a surface hydrophobic layer Preparation of the spraying solution: Dissolve polydimethylsiloxane (PDMS) in n-hexane to prepare a solution with a concentration of 3 mg / mL, and add dibutyltin dilaurate (1 / 10 by mass of PDMS) as a crosslinking agent. Use a handheld spray gun to evenly spray the solution onto the upper surface of the evaporator obtained in S2, with a spray volume of 1 mL. After spraying, dry at 80℃ for 20 min.

[0066] S4: Assemble the evaporator The S3-treated bundled fiber core is vertically passed through the central hole of a 1 cm thick polystyrene foam board (insulating float), with the upper end of the fiber protruding from the foam board by about 0.3 cm and the lower end protruding by about 1.2 cm. The foam board allows the evaporator to float on the water surface, with the lower end in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0067] Performance testing:

[0068] The dry temperature is 94.4℃, the wet temperature is 39.6℃, and the surface water contact angle is 129±1°. Under one solar irradiation, the evaporation rate is 2.20 kg·m³. -2 ·h -1 .

[0069] Example 5

[0070] This embodiment provides a biomimetic bundled fiber evaporator and its preparation method.

[0071] S1: Bundled fiber assembly Y-shaped cross-section polypropylene fibers (monofilament diameter 50 µm) were selected and fully filled into a circular ring with an inner diameter of 5 cm until no more could be filled, ensuring a consistent filling density for each batch of fiber bundles. Using 3 mm wide polyester binding tape, the filled fiber bundles were bound into a 3 cm diameter cylinder, with a center-to-center distance of 3 mm between adjacent binding tapes. Finally, the bundle was cut to a height of 2.5 cm to obtain the bundled fiber core.

[0072] S2: Constructing an MXene photothermal coating Prepare a 2 g / L PVA1799 aqueous solution, soak the bundled fibers for 10 min, then remove and pre-dry at 50℃ for 8 min. Prepare MXene (Ti3C2T) solution. x A suspension with a concentration of 5 mg / mL was prepared. The fibers were immersed in the suspension for 10 minutes, then removed and dried at 60°C.

[0073] S3: Construct a surface hydrophobic layer Preparation of the spraying solution: Dissolve polymethylhydrosilane (PHMS) in n-hexane to prepare a solution with a concentration of 2 mg / mL, and add dibutyltin dilaurate (1 / 10 by mass of PHMS) as a crosslinking agent. Use a handheld spray gun to evenly spray the solution onto the upper surface of the evaporator obtained in S2, with a spray volume of 3 mL. After spraying, dry at 80℃ for 20 min.

[0074] S4: Assemble the evaporator The S3-treated bundled fiber core is vertically passed through the central hole of a 1 cm thick polystyrene foam board (insulating float), with the upper end of the fiber protruding from the foam board by about 0.3 cm and the lower end protruding by about 1.2 cm. The foam board allows the evaporator to float on the water surface, with the lower end in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0075] Performance testing:

[0076] The dry temperature is 96.4℃, the wet temperature is 49.6℃, and the surface water contact angle is 129±1°. Under one solar irradiation, the evaporation rate is 2.64 kg·m³. -2 ·h -1 .

[0077] Example 6

[0078] This embodiment provides a biomimetic bundled fiber evaporator and its preparation method.

[0079] S1: Bundled fiber assembly Y-shaped cross-section polypropylene fibers (monofilament diameter 300 µm) were selected and fully filled into a circular ring with an inner diameter of 5 cm until no more could be filled, ensuring consistent filling density in each batch of fiber bundles. Using 3 mm wide polyester binding tape, the filled fiber bundles were bound into a 3 cm diameter cylinder, with a center-to-center distance of 3 mm between adjacent binding tapes. Finally, a cut height of 2.5 cm was made to obtain the bundled fiber core.

[0080] S2: Constructing TA-Fe 3+ Superhydrophilic photothermal coating Prepare a 4 mg / mL aqueous solution of tannic acid. Prepare an aqueous solution of FeCl3·5H2O, controlling the reaction between tannic acid and Fe. 3+ The molar ratio is 1:3. The bundled fiber core obtained from S1 is moistened with ethanol, then immersed in tannic acid solution for 15 min, removed, and then immersed in FeCl3 solution for 15 min, causing a dark TA-Fe coating to form on the fiber surface. 3+ Coordination coating. After removal, rinse three times with deionized water and dry in a 60°C oven for 2 hours.

[0081] S3: Construct a surface hydrophobic layer Preparation of the spraying solution: Dissolve polydimethylsiloxane (PDMS) in n-hexane to prepare a solution with a concentration of 3 mg / mL, and add dibutyltin dilaurate (1 / 10 by mass of PDMS) as a crosslinking agent. Use a handheld spray gun to evenly spray the solution onto the upper surface of the evaporator obtained in S2, with a spray volume of 2.5 mL. After spraying, dry at 80℃ for 20 min.

[0082] S4: Assemble the evaporator The S3-treated bundled fiber core is vertically passed through the central hole of a 1 cm thick polystyrene foam board (insulating float), with the upper end of the fiber protruding from the foam board by about 0.3 cm and the lower end protruding by about 1.2 cm. The foam board allows the evaporator to float on the water surface, with the lower end in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0083] Performance testing:

[0084] The dry temperature is 93.4℃, the wet temperature is 48.3℃, and the surface water contact angle is 132±1°. Under one solar irradiation, the evaporation rate is 2.57 kg·m³. -2 ·h -1 .

[0085] Example 7

[0086] This embodiment provides a biomimetic bundled fiber evaporator and its preparation method.

[0087] S1: Bundled fiber assembly Y-shaped cross-section polypropylene fibers (monofilament diameter 300 µm) were selected and fully filled into a circular ring with an inner diameter of 5 cm until no more could be filled, ensuring consistent filling density in each batch of fiber bundles. Using 3 mm wide polyester binding tape, the filled fiber bundles were bound into a 3 cm diameter cylinder, with a center-to-center distance of 3 mm between adjacent binding tapes. Finally, a cut height of 2.5 cm was made to obtain the bundled fiber core.

[0088] S2: Constructing TA-Fe 3+ Superhydrophilic photothermal coating Prepare a 4 mg / mL tannic acid aqueous solution. Prepare a FeCl3·5H2O aqueous solution, controlling the reaction between tannic acid and Fe. 3+ The molar ratio is 1:3. The bundled fiber core obtained from S1 is moistened with ethanol, then immersed in tannic acid solution for 15 min, removed, and then immersed in FeCl3 solution for 15 min, causing a dark TA-Fe coating to form on the fiber surface. 3+ Coordination coating. After removal, rinse three times with deionized water and dry in a 60°C oven for 2 hours.

[0089] S3: Construct a surface hydrophobic layer Preparation of the spraying solution: Dissolve polymethylhydrosilane (PHMS) in n-hexane to prepare a solution with a concentration of 3 mg / mL, and add dibutyltin dilaurate (1 / 10 by mass of PDMS) as a crosslinking agent. Use a handheld spray gun to evenly spray the solution onto the upper surface of the evaporator obtained in S2, with a spray volume of 2.5 mL. After spraying, dry at 80℃ for 20 min.

[0090] S4: Assemble the evaporator The S3-treated bundled fiber core is vertically passed through the central hole of a 1 cm thick polystyrene foam board (insulating float), with the upper end of the fiber protruding from the foam board by about 0.3 cm and the lower end protruding by about 1.2 cm. The foam board allows the evaporator to float on the water surface, with the lower end in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0091] Performance testing:

[0092] The dry temperature is 91.1℃, the wet temperature is 46.1℃, and the surface water contact angle is 125±1°. Under one solar irradiation, the evaporation rate is 2.48 kg·m³. -2 ·h -1 .

[0093] The specific parameters and performance results of each embodiment are shown in Table 1 below. All embodiments exhibit excellent evaporation performance.

[0094] Table 1 Summary of performance parameters for each embodiment

[0095] Comparative Example 1 (Straight solid fiber, no special cross-section) S1: Bundled fiber assembly: Select round solid polyester fibers with a diameter of 50μm. After pre-filling, bind them to a 3cm diameter cylinder using 3mm wide binding straps (3mm intervals), and cut to a height of 2.5cm.

[0096] S2: Constructing TA-Fe 3+ Superhydrophilic photothermal coating Prepare an aqueous solution of tannic acid with a concentration of 4 mg / mL. Prepare an aqueous solution of FeCl3·5H2O, in which tannic acid reacts with Fe... 3+ The molar ratio is 1:3. The bundled fibers are immersed in a tannic acid solution for 15 minutes, then removed and immersed in a FeCl3 solution for 15 minutes to form a dark-colored TA-Fe... 3+ Coating. After removal, rinse three times with deionized water and dry in a 60°C oven for 2 hours.

[0097] S3: Construct a surface hydrophobic layer Preparation of the spraying solution: Prepare a 3 mg / mL polydimethylsiloxane (PDMS) hexane spraying solution (the crosslinking agent is one-tenth the amount of silane). Use a handheld spray gun to evenly spray the solution onto the upper surface of the evaporator, with a spray volume of 1 mL. After spraying, dry at 80°C for 20 min.

[0098] S4: Assemble the evaporator The S3-treated bundled fiber core is vertically passed through the central hole of a 1cm thick polystyrene foam board (insulating float), with the upper end of the fiber protruding from the foam board by about 0.3cm and the lower end by about 1.2cm. The foam board allows the evaporator to float on the water surface, with the lower end in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0099] Performance testing: Dry temperature 92.1℃, wet temperature 48.6℃, surface water contact angle 127±1°. (1 solar watt-hour) -2 Under irradiation, the evaporation rate of the pure water system reached 2.33 kg·m³. -2 ·h -1 .

[0100] Comparative Example 2 (bundled fibers without hydrophobic surface layer)

[0101] S1: Bundled fiber assembly: Y-shaped cross-section polypropylene fibers with a single filament diameter of 50μm were selected. The fibers were fully packed into a circular ring with an inner diameter of 5cm until no more could be packed in, ensuring a uniform fiber quantity. Then, a 3mm wide binding tape (polyester tape) was used to bind the fiber bundle into a cylindrical shape with a diameter of 3cm, with adjacent binding tapes spaced 3mm apart. Finally, the bound fiber bundle was cut into 2.5cm lengths to obtain the bundled fiber core.

[0102] S2: Constructing TA-Fe 3+ Superhydrophilic photothermal coating Prepare an aqueous solution of tannic acid with a concentration of 4 mg / mL. Prepare an aqueous solution of FeCl3·5H2O, in which tannic acid reacts with Fe... 3+ The molar ratio is 1:3. The bundled fibers are immersed in a tannic acid solution for 15 minutes, then removed and immersed in a FeCl3 solution for 15 minutes to form a dark-colored TA-Fe... 3+ Coating. After removal, rinse three times with deionized water and dry in a 60°C oven for 2 hours.

[0103] S3: Assemble the evaporator The S2-treated bundled fiber core is vertically passed through the central hole of a 1cm thick polystyrene foam board (insulating float), with the upper end of the fiber protruding from the foam board by about 0.3cm and the lower end by about 1.2cm. The foam board allows the evaporator to float on the water surface, with the lower end in contact with the water for water supply and the upper end exposed to the air for evaporation.

[0104] Performance testing: Dry temperature 91.4℃, wet temperature 40.6℃, surface water contact angle 0°. (1 solar voltaic unit, 1 kW·m³) -2 Under irradiation, the evaporation rate of the pure water system reached 2.41 kg·m³. -2 ·h -1 .

[0105] Comparative Example 3 (Preparation of Vertical Channel Aerogels using the Ice Template Method)

[0106] S1: Pour a 2wt% polyvinyl alcohol (PVA) aqueous solution into a cylindrical mold with a diameter of 3cm, place it at -20℃ for unidirectional freezing for 12 hours, and then freeze-dry for 48 hours to obtain a vertical channel PVA aerogel with a cutting height of 2.5cm.

[0107] S2: Prepare an aqueous solution of tannic acid with a concentration of 4 mg / mL. Prepare an aqueous solution of FeCl3·5H2O, in which tannic acid reacts with Fe... 3+ The molar ratio was 1:3. The above gel was immersed in tannic acid solution for 15 minutes, then removed and immersed in FeCl3 solution for 15 minutes, forming a dark-colored TA-Fe... 3+ Coating. After removal, rinse three times with deionized water and dry in a 60°C oven for 2 hours.

[0108] S3: Prepare a 3 mg / mL hexane spraying solution of polydimethylsiloxane (PDMS) (the crosslinking agent is one-tenth the amount of silane). Use a handheld spray gun to evenly spray the solution onto the upper surface of the evaporator, with a spray volume of 1 mL. After spraying, dry at 80°C for 20 min.

[0109] S4: Vertically insert the coated bundled fiber core into the central hole of a 1cm thick polystyrene foam board, leaving approximately 0.3cm of the upper fiber exposed. The foam board floats on the water surface as a buoy, with the lower fiber ends submerged.

[0110] Performance testing: Dry temperature 97.4℃, wet temperature 46.3℃, surface water contact angle 125±1°. Evaporation rate under one solar irradiation: 2.58 kg·m³. -2 ·h -1 The preparation cycle takes more than 48 hours, consumes a lot of energy, and the aerogel has poor mechanical strength and is prone to collapse.

[0111] The performance parameters of each comparative example are summarized in Table 2.

[0112] Table 2 Comparison of performance parameters of each comparative example and Example 1

[0113] The results of the above embodiments and comparative examples show that: As can be seen from Table 1, the fiber evaporators prepared in each embodiment of the present invention all exhibit good evaporation rates, indicating that the technical solution of the present invention has broad applicability and feasibility. Specifically, Y-shaped cross-section fibers, an evaporator height of 2.5 cm, and TA-Fe... 3+ Example 1, modified with PDMS (4 mg / mL), exhibited the best overall performance. Figure 3 The figures shown are the water contact angle changes of the evaporator in Example 1 of the present invention in (a) the original state, (b) after the construction of the photothermal coating, and (c) after the spraying of the hydrophobic layer; and the water contact angle figures in Example 2 (d) and Example 3 (e) after the spraying of the hydrophobic layer.

[0114] Example 1, compared with Comparative Example 1, confirms the crucial role of irregularly shaped fibers (Y-shaped, C-shaped) or twisted structures with surface grooves in improving evaporation efficiency, as the additional capillary channels they provide optimize water transport. In the multi-twisted fiber evaporator, the numerous helical channels in the multi-twisted structure hinder water transport, resulting in a lower evaporation rate compared to Y-shaped fibers. Figure 4 The diagram shows cross-sections of evaporators composed of different fibers: (a) circular fibers; (b) C-shaped fibers; (c) Y-shaped fibers; (d) multi-twisted fibers.

[0115] Example 1, compared with Comparative Example 2, demonstrates the decisive contribution of the upper hydrophobic thin layer (PDMS / PHMS) to achieving heat localization, reducing heat loss, and improving evaporation efficiency. Figure 2 These are infrared thermal imaging comparison photos of the evaporators of Embodiment 1 and Comparative Example 2 under dry and wet conditions.

[0116] Example 1, due to its irregularly shaped fibers with linear grooves and hydrophobic coating, can endow the evaporator with excellent vertical channels and surface thermal localization capabilities, thus exhibiting an excellent evaporation rate.

[0117] Compared with Comparative Example 3, Example 1 fully demonstrates the great advantages of the present invention in terms of preparation process (fast, simple, low cost, and scalable). Example 1 has a simple preparation process, fast preparation time and low energy consumption (no need for long-term freeze drying), and has excellent evaporation performance (performance is not inferior to or even better than the complex ice template method).

[0118] In summary, this invention successfully constructs a high-performance solar evaporator that combines efficient water transport, excellent photothermal conversion, and significant thermal localization effect through the synergistic design of "fiber bundles with specific cross-sections / structures" and a double-layer coating of "hydrophilic photothermal layer + hydrophobic thermal insulation layer" and a simple "bundling-dip coating-spraying" preparation process.

[0119] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A biomimetic bundled fiber evaporator, characterized in that, include: A bundled fiber core, wherein the bundled fiber core is formed by binding multiple fibers together by at least one binding member; The fiber is selected from irregular cross-section fibers with surface grooves or fiber yarns with twisted structures; A superhydrophilic photothermal coating is applied to at least a portion of the surface of the bundled fiber core; the superhydrophilic photothermal coating is a tannic acid-iron ion complex coating or an MXene coating. A hydrophobic surface layer is disposed on the upper evaporation end surface of the evaporator; the material of the hydrophobic surface layer is polydimethylsiloxane or polymethylhydrosilane. An insulating float is connected to the bundled fiber core, which is embedded in the insulating float to make the evaporator float on the water surface.

2. The biomimetic bundled fiber evaporator according to claim 1, characterized in that, The irregularly shaped cross-section fiber with surface groove structure is a C-shaped cross-section fiber or a Y-shaped cross-section fiber; the fiber thread with twisted structure is a multi-twisted cotton thread.

3. The biomimetic bundled fiber evaporator according to claim 1, characterized in that, The binding element is a binding strap; the diameter of the single filament of the fiber is 50~400 µm; the width of the binding strap is 2~5 mm, and the center distance between adjacent binding straps is 2~4 mm; the height of the bundled fiber core is 1~3 cm.

4. The biomimetic bundled fiber evaporator according to claim 1, characterized in that, The thickness of the hydrophobic thin layer on the surface is 10~50 μm, and it is formed by spraying a hexane solution of polydimethylsiloxane or polymethylhydrosilane with a concentration of 2~5 mg / mL.

5. A biomimetic bundled fiber evaporator according to claim 1, characterized in that, The heat-insulating float is a foam board, and the bundled fiber core penetrates vertically through the foam board.

6. A method for preparing a biomimetic bundled fiber evaporator as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Assemble the bundled fiber core: Select multiple fibers, bundle them together, and fix them with one or more binding members to form a bundled structure with vertically oriented capillary channels, and cut it to a predetermined height; the fibers are selected from irregular cross-section fibers with surface groove structure or fiber filaments with twisted structure; S2: Constructing a superhydrophilic photothermal coating: obtained by one of the following methods: Method 1: The bundled fiber core obtained in step S1 is sequentially immersed in tannic acid solution and ferric chloride solution to form TA-Fe 3+ A complex coating is applied to create a superhydrophilic photothermal coating on its surface. Method 2: The bundled fiber core obtained in step S1 is first immersed in a polyvinyl alcohol solution and then immersed in an MXene suspension to form an MXene coating, thereby forming a superhydrophilic photothermal coating on its surface. S3: Constructing a surface hydrophobic layer: Spray a hydrophobic material solution onto the upper surface of the bundled fiber core after step S2 treatment, and form a surface hydrophobic layer after drying; S4: Assemble the evaporator: Combine the bundled fiber core treated in step S3 with the insulating float. The bundled fiber core passes vertically through the insulating foam board, so that the lower end of the core is used to contact the water and the upper end is exposed to the air for evaporation.

7. The method for preparing a biomimetic bundled fiber evaporator according to claim 6, characterized in that, The concentration of the tannic acid solution is 0.5~4 mg / mL. Tannic acid reacts with Fe... 3+ The molar ratio is 1:1 to 1:4, the soaking time is 5 to 30 minutes, and it can be repeated 1 to 3 times.

8. The method for preparing a biomimetic bundled fiber evaporator according to claim 6, characterized in that, In step S2, the preparation process of method two includes: first, immersing the bundled fiber core in a polyvinyl alcohol aqueous solution for pretreatment, then pre-drying at 40~60℃ for 5~10 min, then immersing it in an MXene suspension for 3~10 min, and then drying it at 40~80℃; the concentration of the MXene suspension is 2~5 mg / mL.

9. The method for preparing a biomimetic bundled fiber evaporator according to claim 6, characterized in that, In step S3, the hydrophobic material solution is a hexane solution of polydimethylsiloxane or polymethylhydrosilane with a concentration of 2-5 mg / mL, and a crosslinking agent, dibutyltin dilaurate, is added; the spraying amount is 1-3 mL, and after spraying, it is dried at 40-80℃ for 10-30 min; the amount of crosslinking agent used is one-tenth of the amount of polydimethylsiloxane or polymethylhydrosilane used.

10. The application of the biomimetic bundled fiber evaporator as described in any one of claims 1 to 5 or the biomimetic bundled fiber evaporator prepared by the preparation method described in any one of claims 6 to 9 in solar interface evaporation water treatment, wherein the water treatment includes seawater desalination or high-salinity wastewater treatment.

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