Solar interface evaporator and preparation method and application thereof

Abstract

The invention discloses a solar interface evaporator and a preparation method and application thereof. The evaporator comprises a porous cellulose supporting layer and a photo-thermal composite hydrogel layer loaded on the cellulose supporting layer, and the porous cellulose supporting layer and the photo-thermal composite hydrogel layer are combined in a gel in-situ cross-linking mode to form an integrated composite structure. The photo-thermal composite hydrogel layer is composite hydrogel formed by cross-linking polyvinyl alcohol, chitosan quaternary ammonium salt and carbon black. The preparation method comprises the following steps: adding polyvinyl alcohol and chitosan quaternary ammonium salt into a solvent to form a transparent mixed solution, adding the carbon-based photothermal conversion material, and continuously heating and stirring to prepare a hydrogel precursor solution; then adding glutaraldehyde and hydrochloric acid, and carrying out cross-linking reaction to form a hydrogel system; and immersing the cellulose sponge, standing, circularly and alternately freezing and unfreezing, and finally freeze-drying to obtain the product. The evaporator disclosed by the invention integrates highlight absorption, high heat utilization, water transportation, salt resistance and antibiosis, can realize large-scale production, and is suitable for scenes such as seawater desalination, sewage purification and emergency water supply.

Description

Technical Field

[0001] This invention relates to an evaporator, its preparation method and application, and more particularly to a solar interface evaporator, its preparation method and application. Background Technology

[0002] Currently, seawater desalination has become a key approach to alleviating freshwater shortages. Traditional mainstream technologies such as reverse osmosis and distillation have significant drawbacks: reverse osmosis requires high-pressure drive, resulting in excessive energy consumption, while multi-stage flash evaporation relies on fossil fuels and generates substantial carbon emissions. These methods are not only costly to operate but also contradict sustainable development goals. In contrast, solar-driven interfacial evaporation technology directly utilizes solar energy, achieving water molecule vaporization through localized photothermal conversion. Theoretically, it possesses significant advantages such as zero carbon emissions and low cost, and is widely recognized as a next-generation green desalination solution.

[0003] However, this technology faces two key bottlenecks in its practical application: First, insufficient salt tolerance. During seawater evaporation, continuous vaporization of water leads to salt accumulation and crystallization at the evaporation interface. Under high salinity or long-term operating conditions, salt crystals can cover the photothermal layer and block internal water transport channels, resulting in reduced evaporation efficiency. Second, a lack of antibacterial function. Seawater is rich in microorganisms (such as Escherichia coli and Staphylococcus aureus), and the warm, humid surface of the evaporator becomes a breeding ground for bacteria. The resulting biofilm not only blocks light and reduces photothermal conversion efficiency, but its metabolic products also corrode the material structure, threatening freshwater hygiene and safety. Especially when salt crystallization and biofouling coexist, they produce a synergistic negative effect: the rough surface formed by salt crystals promotes microbial attachment, while the sticky matrix of the biofilm further accelerates localized salt deposition.

[0004] Current interface evaporator designs generally do not integrate salt resistance and antibacterial mechanisms simultaneously, resulting in insufficient long-term stability in real seawater environments. Although the performance of existing salt-resistant and antibacterial interface evaporators has been continuously optimized, their practical application still faces significant challenges: current mainstream salt resistance strategies, such as biomimetic microchannels or multi-level Janus structures, usually rely on precision micro-nano fabrication. This design complexity not only increases manufacturing costs but also makes it difficult to resist the crystallization stress generated by long-term high-salt environments due to the inherent fragility of the structure, ultimately leading to a decline in mechanical stability. At the same time, antibacterial modules generally use precious metal nanoparticles (such as Ag) or easily soluble bactericides, which not only bring high cost burdens but also raise concerns about secondary pollution due to the continuous dissolution of their active components. Of particular concern is that existing designs often mechanically superimpose salt resistance and antibacterial functions. When the rough interface formed by salt crystallization encounters the sticky extracellular polymers (EPS) secreted by microorganisms, the two work together to form a vicious cycle of salt crystal promoting bacterial attachment and bacterial film accelerating salt deposition, causing the system to fail more quickly in real seawater environments. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a solar interface evaporator that can simultaneously achieve efficient salt resistance and long-lasting antibacterial function;

[0006] A second objective of this invention is to provide a method for preparing the aforementioned solar interface evaporator;

[0007] A third objective of this invention is to provide applications of the aforementioned solar interface evaporator.

[0008] Technical solution: The solar interface evaporator of the present invention includes a porous cellulose support layer and a photothermal composite hydrogel layer loaded on the cellulose support layer. The cellulose support layer and the photothermal composite hydrogel layer are tightly bonded by in-situ gel crosslinking to form an integrated composite structure. The photothermal composite hydrogel layer is a composite hydrogel with a three-dimensional porous network structure formed by crosslinking polyvinyl alcohol, chitosan quaternary ammonium salt and carbon black.

[0009] The above-mentioned method for preparing a solar interface evaporator includes the following steps:

[0010] (1) Polyvinyl alcohol and chitosan quaternary ammonium salt were added to the solvent to form a uniform and transparent mixed solution. Then carbon-based photothermal conversion material was added as a photothermal absorber. The mixture was heated and stirred to obtain a composite hydrogel precursor solution.

[0011] (2) Add crosslinking agent glutaraldehyde and catalyst hydrochloric acid to the precursor solution to adjust the acidity of the reaction system and promote the crosslinking reaction of polyvinyl alcohol and chitosan quaternary ammonium salt to form a hydrogel system with a network structure.

[0012] (3) Immerse the cellulose sponge in the cross-linked hydrogel system, let it stand, and then cycle and thaw alternately to promote the uniform formation of the internal cross-linked structure;

[0013] (4) Freeze-dry the material obtained in step (3) to obtain the solar interface evaporator.

[0014] In step (3), the cellulose sponge is pretreated in an alkaline solution before being immersed in the cross-linked hydrogel system to remove surface impurities and improve its hydrophilicity and structural stability.

[0015] In step (1), the mass ratio of polyvinyl alcohol and chitosan quaternary ammonium salt is 10:1 to 10:2, and the amount of carbon black added accounts for 0.25 to 1.0 wt% of the mass of the mixed solution, so as to ensure the formation of a dense and uniformly distributed photothermal functional layer.

[0016] In step (2), the concentration of glutaraldehyde is 40–60 wt%, and the concentration of hydrochloric acid is 1.0–1.2 mol·L⁻¹. -1 .

[0017] In step (3), the freeze-thaw crosslinking process is repeated at least 3 times, each round including freezing at -20 to -18°C for 8 to 12 hours and thawing at room temperature for 3 to 5 hours.

[0018] The solvent in step (1) is deionized water; the carbon-based photothermal conversion material is at least one of carbon black, activated carbon, or carbon nanotubes.

[0019] In step (2), a cross-linking reaction occurs at room temperature.

[0020] In step (4), the freeze-drying process lasts for no less than 48 hours, and the drying temperature is controlled at -40 to -60°C to achieve structural fixation and pore opening of the composite hydrogel.

[0021] The above-mentioned solar interface evaporator is used in seawater desalination, organic wastewater purification, and treatment of bacteria-containing water bodies.

[0022] Invention principle: The evaporator of the present invention uses a cellulose sponge with a layered porous structure as a supporting frame, combined with a photothermal functional hydrogel coating layer composed of polyvinyl alcohol and cationic chitosan quaternary ammonium salt, and doped with carbon black particles to form a photothermal interface with high light absorption rate, and uses cellulose sponge as a heat insulation substrate to reduce heat loss.

[0023] This invention utilizes a PVA hydrogel loaded with carbon black and chitosan quaternary ammonium salt, which is filled within a sponge framework. The hydroxyl groups in PVA and HACC react with the aldehyde groups in glutaraldehyde under acidic conditions to form a cross-linked molecular network. This network can regulate the escape behavior of water molecules during evaporation and ensures the tight adhesion of carbon black particles. The hydrogel synthesis is promoted through acetal reaction and freeze-thaw cycles. Furthermore, the molecular network structure within the hydrogel is microscopically adjusted by adding different HACC contents, generating more intermediate water.

[0024] The evaporator of this invention draws water to the photothermal interface through capillary action, achieving efficient evaporation under sunlight irradiation; the positively charged quaternary ammonium groups in HACC can charge-disrupt bacterial cell membranes, achieving long-lasting antibacterial effect; and the porous sponge structure can continuously pump water and promote the diffusion and reflux of salt ions, preventing crystal accumulation.

[0025] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0026] (1) This invention effectively constructs a water channel structure with strong permeability and excellent capillary drive capability by introducing porous cellulose sponge as a water transport support matrix. During continuous evaporation, it can guide the diffusion and reflux of salt, avoiding local accumulation and crystallization blockage of salt at the evaporation interface. The average evaporation rate in real Bohai Sea water reached 1.88 kg m³ / h in 10 hours.- 2 h -1 It exhibits excellent salt resistance; at the same time, cationic chitosan quaternary ammonium salt is introduced into the photothermal gel layer as an antibacterial component. The quaternary ammonium cationic groups contained therein can actively destroy the bacterial cell membrane structure, achieving highly efficient inhibition of Escherichia coli and Staphylococcus aureus. The antibacterial rate reaches 99.9% and 99.8% respectively within 18 hours, effectively solving the problem of evaporators being easily contaminated by microorganisms under humid and warm conditions. Therefore, the solar interface evaporator of the present invention achieves functional integration and synergistic optimization in terms of salt crystallization resistance and antibacterial contamination, significantly improving the long-term stable operation capability of the interface evaporator in complex water bodies.

[0027] (2) This invention integrates photothermal evaporation function with salt resistance and antibacterial ability. It can maintain stable operation without relying on external energy consumption or bactericides. It is suitable for various complex environments such as seawater desalination, organic wastewater purification and treatment of bacteria-containing water bodies. It has good practical application prospects and promotion value.

[0028] (3) The evaporator of the present invention operates at 1kW / m 2 The evaporation rate under solar irradiation intensity is 2.08 kg·m³ under pure water conditions. -2 ·h -1 Under conditions of 3.5wt% artificial seawater, the concentration is 1.95 kg·m³. -2 ·h -1 It can operate stably for a long time without salt buildup or blockage.

[0029] (4) In the HACC of the present invention, the positively charged quaternary ammonium group interacts with the negatively charged components on the surface of the bacterial cell membrane, thereby destroying its membrane structure. The antibacterial rate is not less than 99.9% and 99.8% for Escherichia coli and Staphylococcus aureus, respectively.

[0030] (5) The evaporator of the present invention can be used for solar desalination of water sources such as salt water, seawater, and brackish water with a salinity of 0.1% to 15%, and is also suitable for interface evaporation purification of dye wastewater and bacterial contaminated water. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the evaporator evaporation device prepared according to the present invention;

[0032] Figure 2 This is a curve showing the change in water mass over time under one times the solar irradiance of the photothermal interface evaporator prepared in Examples 1-4 and Comparative Example 1 of the present invention.

[0033] Figure 3 This is a graph showing the change in evaporation rate of the photothermal interface evaporator prepared in Example 3 of the present invention over 10 consecutive hours in the Bohai Sea.

[0034] Figure 4 This is a graph showing the antibacterial effect of the photothermal interface evaporator prepared in Example 3 of the present invention on Escherichia coli and Staphylococcus aureus in a blank control group over 18 hours.

[0035] Figure 5 This is the Raman spectrum analysis diagram of Embodiment 3 of the present invention;

[0036] Figure 6 This is the Raman spectrum analysis diagram of Comparative Example 1 of the present invention. Detailed Implementation

[0037] The present invention will now be described in further detail.

[0038] Example 1

[0039] First, the natural wood pulp cellulose sponge was soaked in a 5 wt% sodium hydroxide solution for 1 hour, rinsed with deionized water, and then dried for later use. Next, 1.25 g of polyvinyl alcohol (PVA) powder with a degree of hydrolysis of 99% and 0.05 g of chitosan quaternary ammonium salt (HACC) with a degree of substitution of 98% were added to 20 mL of deionized water and stirred at 90°C for 2 hours to form a transparent solution. Then, 0.05 g of carbon black was added and stirring continued for 30 minutes to form a homogeneous dispersion. Finally, 25 μL of 50 wt% glutaraldehyde solution and 125 μL of 1 mol·L⁻¹ were added to the homogeneous dispersion. -1 Hydrochloric acid was added and stirred rapidly, and the pretreated sponge was immediately impregnated. The sponge was left to stand at room temperature for 8 hours to allow the hydrogel precursor to fully penetrate into the 50-300μm pores of the sponge. Subsequently, three rounds of freeze-thaw cycles were performed for cross-linking, each round consisting of freezing at -18℃ for 8 hours and thawing at room temperature for 3 hours. Finally, the sponge was freeze-dried at -50℃ for 48 hours to obtain the composite evaporator.

[0040] A schematic diagram of the evaporator's evaporation device is shown below. Figure 1 As shown.

[0041] Example 2

[0042] First, natural wood pulp cellulose sponge was soaked in a 5 wt% sodium hydroxide solution for 1 hour, rinsed with deionized water, and then dried for later use. Next, 1.25 g of PVA powder with a degree of hydrolysis of 99% and 0.10 g of HACCP with a degree of substitution of 98% were added to 20 mL of deionized water and stirred at 90°C for 2 hours to form a transparent solution. Then, 0.05 g of carbon black was added and stirring continued for 30 minutes to form a homogeneous dispersion. Finally, 25 μL of 50 wt% glutaraldehyde solution and 125 μL of 1 mol·L⁻¹ were added to the homogeneous dispersion. -1Hydrochloric acid was added and stirred rapidly, and the pretreated sponge was immediately impregnated. The sponge was left to stand at room temperature for 8 hours to allow the hydrogel precursor to fully penetrate into the 50-300μm pores of the sponge. Subsequently, three rounds of freeze-thaw cycles were performed for cross-linking, each round consisting of freezing at -18℃ for 8 hours and thawing at room temperature for 3 hours. Finally, the sponge was freeze-dried at -50℃ for 48 hours to obtain the composite evaporator.

[0043] Example 3

[0044] First, natural wood pulp cellulose sponge was soaked in a 5 wt% sodium hydroxide solution for 1 hour, rinsed with deionized water, and then dried for later use. Next, 1.25 g of PVA powder with a degree of hydrolysis of 99% and 0.15 g of HACCP with a degree of substitution of 98% were added to 20 mL of deionized water and stirred at 90°C for 2 hours to form a transparent solution. Then, 0.05 g of carbon black was added and stirring continued for 30 minutes to form a homogeneous dispersion. Finally, 25 μL of 50 wt% glutaraldehyde solution and 125 μL of 1 mol·L⁻¹ sodium hydroxide solution were added to the homogeneous dispersion. -1 Hydrochloric acid was added and stirred rapidly, and the pretreated sponge was immediately impregnated. The sponge was left to stand at room temperature for 8 hours to allow the hydrogel precursor to fully penetrate into the 50-300μm pores of the sponge. Subsequently, three rounds of freeze-thaw cycles were performed for cross-linking, each round consisting of freezing at -18℃ for 8 hours and thawing at room temperature for 3 hours. Finally, the sponge was freeze-dried at -50℃ for 48 hours to obtain the composite evaporator.

[0045] Example 4

[0046] First, natural wood pulp cellulose sponge was soaked in a 5wt% sodium hydroxide solution for 1 hour, rinsed with deionized water, and then dried for later use. Next, 1.25g of PVA powder with a degree of hydrolysis of 99% and 0.20g of HACCP with a degree of substitution of 98% were added to 20mL of deionized water and stirred at 90℃ for 2 hours to form a transparent solution. Then, 0.05g of carbon black was added and stirring continued for 30 minutes to form a homogeneous dispersion. Finally, 25μL of 50wt% glutaraldehyde solution and 125μL of 1mol·L⁻¹ were added to the homogeneous dispersion. -1 Hydrochloric acid was added and stirred rapidly, and the pretreated sponge was immediately impregnated. The sponge was left to stand at room temperature for 8 hours to allow the hydrogel precursor to fully penetrate into the 50-300μm pores of the sponge. Subsequently, three rounds of freeze-thaw cycles were performed for cross-linking, each round consisting of freezing at -18℃ for 8 hours and thawing at room temperature for 3 hours. Finally, the sponge was freeze-dried at -50℃ for 48 hours to obtain the composite evaporator.

[0047] Example 5

[0048] First, natural wood pulp cellulose sponge was soaked in a 5 wt% sodium hydroxide solution for 1 hour, rinsed with deionized water, and then dried for later use. Next, 1.25 g of PVA powder with a degree of hydrolysis of 99% and 0.20 g of HACCP with a degree of substitution of 98% were added to 20 mL of deionized water and stirred at 90°C for 2 hours to form a transparent solution. Then, 0.05 g of carbon black was added and stirring continued for 30 minutes to form a homogeneous dispersion. Finally, 25 μL of 60 wt% glutaraldehyde solution and 125 μL of 2 mol·L⁻¹ were added to the homogeneous dispersion. -1 Hydrochloric acid was added and stirred rapidly, and the pretreated sponge was immediately impregnated. The sponge was left to stand at room temperature for 8 hours to allow the hydrogel precursor to fully penetrate into the 50-300μm pores of the sponge. Subsequently, three rounds of freeze-thaw cycles were performed for cross-linking, each round consisting of freezing at -20℃ for 12 hours and thawing at room temperature for 5 hours. Finally, the sponge was freeze-dried at -50℃ for 48 hours to obtain the composite evaporator.

[0049] Comparative Example 1

[0050] First, natural wood pulp cellulose sponge was soaked in a 5 wt% sodium hydroxide solution for 1 hour, rinsed with deionized water, and then dried. Next, 1.25 g of PVA powder with a 99% degree of hydrolysis was added to 20 mL of deionized water and stirred at 90°C for 2 hours to form a transparent solution. Then, 0.05 g of carbon black was added and stirring continued for 30 minutes to form a homogeneous dispersion. Finally, 25 μL of 50 wt% glutaraldehyde solution and 125 μL of 1 mol·L⁻¹ were added to the homogeneous dispersion. -1 Hydrochloric acid was added and stirred rapidly, and the pretreated sponge was immediately impregnated. The sponge was left to stand at room temperature for 8 hours to allow the hydrogel precursor to fully penetrate into the 50-300μm pores of the sponge. Subsequently, three rounds of freeze-thaw cycles were performed for cross-linking, each round consisting of freezing at -18℃ for 8 hours and thawing at room temperature for 3 hours. Finally, the sponge was freeze-dried at -50℃ for 48 hours to obtain the composite evaporator.

[0051] Comparative Example 2

[0052] Based on Example 1, the difference is that 125 μL of 50% glutaraldehyde solution and 200 μL of 1 mol L⁻¹ were added. -1 The hydrochloric acid solution. The gel formed in this comparative example cannot absorb water.

[0053] Comparative Example 3

[0054] Based on Example 1, the difference is that the natural wood pulp cellulose sponge was replaced with a loofah sponge. This comparative example could not form a glue due to its excessively large pore size.

[0055] Depend on Figure 2It can be seen that the evaporation effect of the examples with added HACC is better than that of the comparative example without HACC. Initially, the evaporation rate increases with the increase of HACC content, but after a certain range, the evaporation rate decreases with the increase of HACC content. In this figure, Example 3 with added 0.15g HACC reached the highest evaporation rate of 2.08kg m³ within 1 hour. -2 h -1 .

[0056] Depend on Figure 3 It can be seen that initially, the evaporation rate increases due to the gradual rise in temperature and decrease in heat loss. Subsequently, the evaporation rate gradually decreases due to the increase in seawater salinity. Notably, the average evaporation rate reaches 1.88 kg m³ over 10 hours. -2 h -1 The rate decreased by only 4% compared to the initial 1-hour rate, which strongly demonstrates the evaporator's excellent salt resistance.

[0057] Depend on Figure 4 As can be seen, the agar plate coating test further quantified the antibacterial performance of the evaporator. For Escherichia coli, the colony count increased from 1.31 × 10⁻⁶. 9 The CFU (control group) decreased to 386.6 CFU (experimental group), corresponding to an inhibition rate of 99.9%. For Staphylococcus aureus, the count decreased from 1.68 × 10⁻⁶ CFU. 8 CFU (control group) decreased to 1.46×10 4 CFU (experimental group) showed an inhibition rate of 99.8%. This remarkable antibacterial activity originates from the cationic quaternary ammonium groups in HACCP, which interact electrostatically with anionic components of the bacterial cell wall, such as phospholipids and teichoic acid. These interactions disrupt membrane integrity, leading to cytoplasmic leakage and ultimately cell lysis.

[0058] Regulating the state of water within the evaporator plays a crucial role in achieving superior solar evaporation performance. The inherent enthalpy of evaporation can be reduced by adjusting the water's flowability. Water molecules exist in two distinct states depending on the strength of their interaction with the matrix material—free water (FW) and intermediate water (IW). Intermediate water, due to weakened hydrogen bonding, requires less energy to evaporate, thus contributing to a lower enthalpy. Raman spectroscopy was used to analyze the state of water within the OH stretching region (3000-3800 cm⁻¹). -1 In the free water plane, it is decomposed into four Gaussian sub-peaks: 3225cm in the free water plane (3225cm) -1 ) and out-of-plane (3405cm) -1 Vibration, and the symmetry of the water in the middle (3520cm) -1 ) and asymmetry (3625cm) -1(Stretching mode.) The presence of intermediate water promotes evaporation from the low-energy state, and water activation lowers the enthalpy of evaporation. Figure 5 , 6 It can be seen that in Comparative Example 1, the proportion of intermediate water was 22.8%, while in Example 3, this proportion increased to 24.0%. Correspondingly, the ratio of intermediate water to free water increased from 0.295 to 0.315, which confirms that the optimized HACC addition amount effectively increased the content of intermediate water, thereby reducing the enthalpy of vaporization.

Claims

1. A solar interface evaporator, characterized in that, It includes a porous cellulose support layer and a photothermal composite hydrogel layer loaded on the cellulose support layer. The cellulose support layer and the photothermal composite hydrogel layer are tightly bonded together by in-situ gel crosslinking to form an integrated composite structure. The photothermal composite hydrogel layer is a composite hydrogel with a three-dimensional porous network structure formed by crosslinking polyvinyl alcohol, chitosan quaternary ammonium salt and carbon black.

2. A method for preparing the solar interface evaporator according to claim 1, characterized in that, Includes the following steps: (1) Polyvinyl alcohol and chitosan quaternary ammonium salt were added to the solvent to form a uniform and transparent mixed solution. Then carbon-based photothermal conversion material was added as a photothermal absorber. The mixture was heated and stirred to obtain a composite hydrogel precursor solution. (2) Add crosslinking agent glutaraldehyde and catalyst hydrochloric acid to the precursor solution to adjust the acidity of the reaction system and promote the crosslinking reaction of polyvinyl alcohol and chitosan quaternary ammonium salt to form a hydrogel system with a network structure. (3) Immerse the cellulose sponge in the cross-linked hydrogel system, let it stand, and then cycle and thaw alternately to promote the uniform formation of the internal cross-linked structure; (4) Freeze-dry the material obtained in step (3) to obtain the solar interface evaporator.

3. The method for preparing a solar interface evaporator according to claim 2, characterized in that, In step (3), the cellulose sponge is pretreated in an alkaline solution before being immersed in the cross-linked hydrogel system to remove surface impurities and improve its hydrophilicity and structural stability.

4. The method for preparing a solar interface evaporator according to claim 2, characterized in that, In step (1), the mass ratio of polyvinyl alcohol and chitosan quaternary ammonium salt is 10:1 to 10:2, and the amount of carbon black added accounts for 0.25 to 1.0 wt% of the mass of the mixed solution, so as to ensure the formation of a dense and uniformly distributed photothermal functional layer.

5. The method for preparing a solar interface evaporator according to claim 2, characterized in that, In step (2), the concentration of glutaraldehyde is 40–60 wt%, and the concentration of hydrochloric acid is 1.0–1.2 mol·L⁻¹. -1 .

6. The method for preparing a solar interface evaporator according to claim 2, characterized in that, In step (3), during the alternating freezing and thawing cycle, each round includes freezing at -20 to -18°C for 8 to 12 hours and thawing at room temperature for 3 to 5 hours.

7. The method for preparing a solar interface evaporator according to claim 2, characterized in that, The solvent in step (1) is deionized water.

8. The method for preparing a solar interface evaporator according to claim 2, characterized in that, In step (1), the carbon-based photothermal conversion material is at least one of carbon black, activated carbon, or carbon nanotubes.

9. The method for preparing a solar interface evaporator according to claim 2, characterized in that, In step (4), the freeze-drying process lasts for no less than 48 hours, and the drying temperature is controlled between -40 and -60°C to achieve structural fixation and pore opening of the composite hydrogel.

10. The application of the solar interface evaporator according to claim 1 in seawater desalination, organic wastewater purification and bacterial water treatment.

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