Preparation method and application of integrated solar interface evaporation material

Abstract

The invention belongs to the technical field of interface evaporation, and discloses an integrated solar interface evaporation material with photothermal conversion and heat storage functions and a preparation method and application thereof. The integrated solar interface evaporation material comprises an upper layer and a lower layer, the upper layer is a bifunctional layer with photothermal conversion and heat storage functions, and the lower layer is a hydrophilic layer; the bifunctional layer is composed of a modified phase change microcapsule and a PVA composite fiber membrane, and the hydrophilic layer is composed of PVA hydrogel. The application of the integrated solar interface evaporation material prepared by the invention has excellent photo-thermal conversion capability, excellent heat storage capability and high evaporation rate. In addition, due to the excellent heat storage and heat release capacity, the prepared solar interface evaporator can absorb and store part of heat when irradiated by sunlight, the interface evaporation process can be continued when the sunlight disappears or in the dark environment, and day-night continuous evaporation is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of interfacial evaporation, and particularly relates to an integrated solar interfacial evaporation material with light-heat conversion and heat storage functions and a preparation method and application thereof. BACKGROUND

[0002] In the global water resource distribution, seawater accounts for about 97%, and freshwater resources only account for about 3%. With the development of society and the continuous growth of population, the depletion of freshwater resources and environmental pollution have become increasingly serious global challenges. Seawater desalination, as an effective method to solve the shortage of freshwater resources, is receiving widespread attention. However, traditional seawater desalination technologies, such as reverse osmosis (RO), membrane distillation (MD) and multi-effect flash distillation (MSF), often come with high energy consumption and high cost problems. These technologies, which exacerbate energy problems in exchange for alleviating water resource shortages, are difficult to become long-term solutions. In recent years, solar energy, as the largest developable and sustainable renewable clean energy, has received more and more attention. Using solar energy for seawater desalination has the potential to achieve low energy consumption or even zero energy consumption, which is of great significance to alleviate the global freshwater resource shortage problem. Among them, the solar-driven interfacial evaporation technology has become an effective way to solve this problem due to its low carbon, low cost and high efficiency.

[0003] However, due to the intermittent nature of solar energy, the evaporation rate will decrease rapidly when there is no sunlight, which is very detrimental to continuous water evaporation and full utilization of solar energy. At the same time, when solar energy is abundant, heat leakage from the high-temperature interfacial evaporator to the environment is inevitable, which will cause energy waste. Therefore, in order to solve these problems, an innovative interfacial evaporation system must be designed to improve the utilization of solar energy and improve the overall energy efficiency to improve its evaporation performance under intermittent solar radiation. SUMMARY

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a solar interfacial evaporation material with light-heat conversion and heat storage functions. This composite material uses modified phase change microcapsules as a functional carrier to give the interfacial evaporator excellent light-heat conversion capability and heat storage function. And by constructing a controllable directional multi-level micro-nano structure in the PVA hydrogel, a system with a shape similar to a tree trunk (vertical micron channels) and branches (micro-nano level pore walls) is formed, which can achieve high water flux. By optimizing the migration path of water transport, heat management and evaporation dynamics process, high evaporation rate is achieved, providing a better solution for seawater desalination.

[0005] Another purpose of the present application is to provide a preparation method of the above-mentioned solar interfacial evaporation material with light-heat conversion and heat storage functions.

[0006] Another object of the present application is to provide an application of the solar energy interface evaporation material with the integrated functions of photo-thermal conversion and heat storage.

[0007] The object of the present application is achieved by the following scheme:

[0008] The solar energy interface evaporation material with the integrated functions of photo-thermal conversion and heat storage comprises an upper layer and a lower layer, wherein the upper layer is a dual-functional layer with the functions of photo-thermal conversion and heat storage, and the lower layer is a hydrophilic layer; the dual-functional layer is composed of modified phase change microcapsules and a PVA composite fiber membrane, and the hydrophilic layer is composed of a PVA hydrogel.

[0009] The thickness of the dual-functional layer is 0.5-1.5 mm, and the thickness of the hydrophilic layer is 3-5 mm.

[0010] The paper cup method of the solar energy interface evaporation material with the integrated functions of photo-thermal conversion and heat storage comprises the following steps:

[0011] S1: uniformly dispersing a melamine and formaldehyde aqueous solution in water, adjusting the pH, and then uniformly stirring and heating to prepare a melamine prepolymer solution A; dissolving an emulsifier in water, adjusting the pH to obtain an emulsifier solution B; stirring and emulsifying a phase change material with the solution B to obtain a solution C; mixing the solution A with the solution C, and stirring and reacting to generate a polymer shell layer wrapping the phase change material and a nucleating agent, and then washing and freeze-drying the obtained reactants to prepare phase change microcapsules;

[0012] S2: dispersing the phase change microcapsule material obtained in step S1 into water by ultrasonic method, then adding gum arabic powder thereto, and stirring uniformly at room temperature to prepare a phase change microcapsule solution A; dispersing a silver salt in water, then adding ammonia water to prepare a silver solution B; uniformly mixing the solution A with the solution B, adding a reducing agent, adjusting the pH, and stirring and reacting to make the silver ions be completely reduced into silver particles attached to the surface of the phase change microcapsules, centrifugally washing the obtained reactants with water, and then freeze-drying to prepare modified phase change microcapsule material;

[0013] S3: mixing PVA, water and the modified phase change microcapsules, and stirring uniformly at room temperature to prepare a spinning solution, and building a dual-functional layer by electrospinning to obtain a PVA / modified phase change microcapsule composite fiber membrane;

[0014] S4: Put the composite fiber film obtained in step S3 into a mold, stir PVA, water, water-soluble salt and PMMA uniformly at room temperature, pour into the mold, place the mold on a cold table for unidirectional freezing, and then perform freeze-drying; the obtained dried product is soaked in water to remove salt particles; then it is soaked in an acetone solution to remove PMMA; then freeze-drying is performed again; the twice-dried product is subjected to freeze-thaw cycles to construct a hydrophilic hydrogel layer, and after the construction of the hydrophilic hydrogel layer is completed, drying is performed, that is, an integrated solar evaporation material.

[0015] The mass ratio of the melamine, the aqueous formaldehyde solution, the emulsifier and the phase change material in step S1 is (1-2):(4-6):(1-2):(15-20); the concentration of the aqueous formaldehyde solution is 20-37%; the amount of all water added in step S1 (excluding the water in the aqueous formaldehyde solution) satisfies the mass ratio of melamine and water (1-2):(20-30);

[0016] Sodium dodecyl sulfate can also be added in step S1 when preparing solution C to assist in emulsification, and the weight satisfies the mass ratio of melamine and sodium dodecyl sulfate (1-2):(0.5-1);

[0017] The phase change material in step S1 is at least one of octadecane, eicosane and docosane.

[0018] The emulsifier in step S1 is at least one of styrene-maleic anhydride copolymer and ethylene-maleic anhydride copolymer;

[0019] The heating and stirring in step S1 to prepare the melamine prepolymer solution A means stirring at 150-400 rpm for 1-3 h at 60-90℃; preferably stirring at 200-300 rpm for 1 h at 70℃;

[0020] The pH adjustment in step S1 means adjusting the pH to 4-6;

[0021] The stirring and emulsification in step S1 to obtain solution C means stirring at 70-90℃ for 2-3 h;

[0022] The heating and stirring reaction in step S1 to generate a polymer shell layer to wrap the phase change material and the nucleating agent means stirring at 70-90℃ for 1-3 h.

[0023] The silver salt in step S2 is at least one of silver nitrate, silver acetate and silver citrate; and the reducing agent is at least one of glucose, ascorbic acid, sodium citrate and polyvinylpyrrolidone.

[0024] The mass ratio of the phase change microcapsule, gum arabic, silver salt, ammonia, and reducing agent in step S2 is (3-4):(3-4):(1-2):(1-2):(1-2); the concentration of the ammonia is 15%-25%; the pH is adjusted to 9-11 by using sodium hydroxide; and the stirring reaction after the pH adjustment is performed at a temperature of-5-5 ℃ for 1-3 h; in the water centrifugal washing, the centrifugal speed is 6000-10000 rpm, the centrifugal time is 5-10 min, the temperature during centrifugal is 18-25 ℃, and the washing times are 1-3 times.

[0025] The mass ratio of the PVA, water, and modified phase change microcapsule in step S3 is (1-2):(9-10):(0.5-1.5); the stirring for preparing the spinning solution is performed at a speed of 300-600 rpm;

[0026] In the electrostatic spinning in step S3, the pushing speed of the spinning solution is 0.0015-0.0030 mm / s, the voltage is 18-25 kV, the receiving roller speed is 200-300 rpm, and the distance between the needle and the receiving roller is 8-10 cm.

[0027] In step S4, the water-soluble salt is at least one of sodium chloride, potassium chloride, and lithium chloride; in step S4, the mass ratio of the PVA, water, water-soluble salt, and PMMA is (1-2):(8-9):(0.2-0.3):(0.05-0.1); in step S4, the stirring speed for stirring uniformly at room temperature is 300-600 rpm; in step S4, the temperature of the cold table is-30 ℃, and the freezing rate is 2-5 ℃ / min; in step S4, the water immersion time is 12-24 h; the acetone immersion time is 12-24 h; the freezing temperature is-30--10 ℃, the freezing time is 12-24 h, the thawing temperature is 20-30 ℃, the thawing time is 12-24 h, and the number of freeze-thaw cycles is 3-5 times; and the drying is performed in an oven at a temperature of 30-80 ℃.

[0028] The above-mentioned integrated solar interface evaporation material with light-heat conversion and heat storage functions is applied to solar interface evaporation, seawater desalination, and solar heat management.

[0029] Compared with the prior art, the application has the following advantages and beneficial effects:

[0030] The application of the integrated solar interfacial evaporation material prepared by the application has excellent light-heat conversion capacity, excellent heat storage capacity and high evaporation rate. And because of the excellent heat storage and heat release capacity, the prepared solar interfacial evaporator can absorb and store part of the heat when the sunlight is irradiated, and continue the interfacial evaporation process when the sunlight disappears or in the dark environment, realizing continuous evaporation day and night. And the prepared PVA hydrogel has a multi-level micro-nano structure, by controlling the ratio of micron / nanometer template (by controlling the ratio of PMMA and water-soluble salt), the freezing rate of the cold table, realizing the controllable adjustment of the vertical micron channel and the micro-nano pore wall, forming a system similar to the shape of the trunk (vertical micron channel) and the branch (micro-nano pore wall), by optimizing the water migration path, realizing high water flux and high-efficiency water evaporation is an ideal structure substrate. And the interfacial evaporator of the application has simple preparation process, cheap and easily available raw materials, and excellent evaporation performance in pure water. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 Scanning electron microscope pictures of phase change microcapsules, modified phase change microcapsules and composite fiber membranes;

[0032] Figure 2 DSC graph of modified phase change microcapsules and 50wt% composite fiber membrane;

[0033] Figure 3 The application's light-heat conversion and evaporation experimental data, wherein (a) is the light-heat conversion data graph of pure PVA hydrogel and 50wt% PVA / modified phase change microcapsule composite fiber membrane, (b) is the water mass change of the integrated solar interfacial evaporation material containing 50wt% modified phase change microcapsules under the irradiation of one solar intensity for 60min, (c) is the water mass change graph of the integrated solar interfacial evaporation material containing 50wt% modified phase change microcapsules under the condition of turning off the light for 60min, and (d) is the water mass change of the 50wt% PVA / modified phase change microcapsule composite fiber membrane under the irradiation of one solar intensity for 60min. DETAILED DESCRIPTION

[0034] The application will be described in further detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the application are not limited thereto. In the examples, the specific conditions not noted are carried out according to the conventional conditions or the conditions suggested by the manufacturers. The reagents or instruments used are not noted by the manufacturers, and are all conventional products that can be purchased on the market.

[0035] Example 1

[0036] Step one: 1 g melamine and 4 g formaldehyde aqueous solution (concentration of 37%) were dissolved in 20 mL pure water, and after adjusting pH=5, a melamine prepolymer solution A was prepared by mechanical stirring uniformly at 70°C for 1 h; 1 g maleic anhydride-vinyl copolymer was dissolved in 10 mL pure water, and an emulsifier solution B was obtained by adjusting pH=5; 15 g eicosane and 0.5 g sodium dodecyl sulfate were mixed with solution B, and solution C was obtained by stirring and emulsifying at 70°C for 2 h; solution A and solution C were mixed, and mechanical stirring was carried out at 70°C for 1 h; the obtained reactants were washed and freeze-dried to obtain phase change microcapsules;

[0037] Step two: 3 g of the microcapsules prepared in step one were dispersed into 200 mL pure water by ultrasonic method, and then 3 g gum arabic powder was added, and a phase change microcapsule solution A was prepared by stirring uniformly on a magnetic stirring table at room temperature; 2 g silver nitrate was dispersed in 20 mL pure water, and 2 g ammonia water (25%) was added to prepare a silver solution B; solution A and solution B were mixed uniformly, 2 g glucose was added, 0.5 g sodium hydroxide was added to adjust pH=9-11, ice bath stirring was carried out for 3 h, the obtained reactants were washed by centrifugation with pure water, in the centrifugal washing with water, the centrifugal speed was 8000 rpm, the centrifugal time was 10 minutes, the temperature during centrifugation was 20°C, and the washing times were 2 times, and then freeze-drying was carried out to obtain modified phase change microcapsule material.

[0038] Example 2

[0039] Step one: 1 g melamine and 4 g formaldehyde aqueous solution (concentration of 37%) were dissolved in 20 mL pure water, and after adjusting pH=5, a melamine prepolymer solution A was prepared by mechanical stirring uniformly at 70°C for 1 h; 1 g maleic anhydride-vinyl copolymer was dissolved in 10 mL pure water, and an emulsifier solution B was obtained by adjusting pH=5; 15 g eicosane and 0.5 g sodium dodecyl sulfate were mixed with solution B, and solution C was obtained by stirring and emulsifying at 70°C for 2 h; solution A and solution C were mixed, and mechanical stirring was carried out at 70°C for 1 h; the obtained reactants were washed and freeze-dried to obtain phase change microcapsules;

[0040] Step two: 3 g of the microcapsules prepared in step one were dispersed into 200 mL pure water by ultrasonic method, and then 3 g gum arabic powder was added, and a phase change microcapsule solution A was prepared by stirring uniformly on a magnetic stirring table at room temperature; 2 g silver nitrate was dispersed in 20 mL pure water, and 2 g ammonia water (25%) was added to prepare a silver solution B; solution A and solution B were mixed uniformly, 2 g glucose was added, 0.5 g sodium hydroxide was added to adjust pH=9-11, ice bath stirring was carried out for 3 h, the obtained reactants were washed by centrifugation with pure water, in the centrifugal washing with water, the centrifugal speed was 8000 rpm, the centrifugal time was 10 minutes, the temperature during centrifugation was 20°C, and the washing times were 2 times, and then freeze-drying was carried out to obtain modified phase change microcapsule material;

[0041] Step three: 1.2 g PVA, 9 g pure water and 0.8 g modified phase change microcapsules prepared in step two were mixed to prepare a spinning solution, which was stirred on a magnetic stirrer for 2 h at room temperature, and then electrospinning was performed at a voltage of 20 kv and a pushing speed of 0.0015 mm / s, with a collector distance of 10 cm and a receiving roller rotating at 200 rpm, to obtain a PVA / modified phase change microcapsule composite fiber membrane, the thickness of which was 1 mm, and the mass percentage of modified phase change microcapsules in the composite fiber membrane was 40 wt%.

[0042] Step four: 1 g PVA, 9 g pure water, 0.2 g sodium chloride and 0.05 g PMMA were added to the surface of the obtained composite fiber membrane, which was stirred on a magnetic stirrer for 1 h at room temperature, and then poured into a mold, which was placed on a cold table to be directionally frozen, with a cold source temperature of -30 °C and a freezing rate of 3 °C / min, to form vertical micron channels, followed by freeze-drying; the dried product was soaked in pure water for 12 h to remove salt particles, to form a nanometer pore wall; then it was soaked in an acetone solution for 12 h to remove PMMA, to form a micron pore wall; followed by freeze-drying again; the twice-dried product was subjected to freeze-thaw cycles, with a freezing temperature of -20 °C, a freezing time of 12 h, a thawing temperature of 25 °C, a thawing time of 12 h, and a freeze-thaw cycle number of 3 times, to construct a hydrophilic hydrogel layer, and after the construction of the hydrophilic hydrogel layer was completed, drying was performed, to obtain an integrated solar interface evaporation material, and the thickness of the PVA hydrogel was 3 mm.

[0043] Examples 3-5

[0044] Examples 3-5 were all repeated as in Example 2, except that the amount of modified phase change microcapsules in step three was different, and the amounts of modified phase change microcapsules in Examples 3-5 were 1.2 g, 1.8 g and 2.8 g, respectively, i.e. in step three of Examples 3-5, PVA / modified phase change microcapsule composite fiber membranes with modified phase change microcapsules of 50 wt%, 60 wt% and 70 wt% were obtained, respectively.

[0045] Comparative Example 1

[0046] Comparative Example 1 was the same as Example 2, except that the amount of modified phase change microcapsules in step three was different, and the amount of modified phase change microcapsules in Comparative Example 1 was 0, i.e. a composite fiber membrane with a mass ratio of 0 wt% was obtained. Step four was not performed.

[0047] The integrated solar interface evaporation materials obtained in Examples 1-5 and the intermediate products thereof were tested as follows:

[0048] The microstructure of the materials prepared in Examples 1-5 was characterized using a scanning electron microscope (SEM, SU-8200, Japan), and the elemental composition of the material surface was analyzed using the energy dispersive spectroscopy (EDS) instrument built into the scanning electron microscope. (See attached figure.) Figure 1 As shown, (a) is a SEM image of the phase change microcapsules prepared in step one of Example 2; (b) is a SEM image of the modified phase change microcapsules prepared in step two of Example 2; (c) is a SEM image of the composite fiber membrane with a modified phase change microcapsule mass ratio of 0 wt% prepared in step three of Comparative Example 1; and (d) is a SEM image of the composite fiber membrane with a modified phase change microcapsule mass ratio of 50 wt% prepared in step three of Example 3. The results are derived from scanning electron microscopy (SEM). Figure 1 As can be seen, the phase change microcapsules are smooth spheres, while the modified phase change microcapsules show obvious Ag particle growth on their surface. Compared to the 0wt% composite fiber membrane, the 50wt% composite fiber membrane clearly shows spherical modified phase change microcapsules embedded in the fiber network, forming a "net"-like structure. This structure can effectively prevent the modified phase change microcapsules from falling off during use.

[0049] The enthalpy values ​​of the materials prepared in Examples 1-5 were characterized using a differential scanning calorimeter (METTLERTOLEDO, Switzerland), with reference to the appendix. Figure 2 As shown, (a) is the DSC image of the modified phase change microcapsules prepared in step two of Example 2; (b) is the DSC image of the composite fiber membrane with a mass percentage of 50 wt% of the modified phase change microcapsules prepared in step three of Example 3. The results were obtained from differential scanning calorimetry (DSC). Figure 2 It can be seen that the modified phase change microcapsules have a high enthalpy of 147.30 J / g, and the enthalpy of the 50 wt% composite fiber membrane also reaches 69.15 J / g, indicating that the prepared composite fiber membrane has excellent heat storage capacity.

[0050] The solar interface evaporation experiment was conducted using a self-made evaporation system in the laboratory. This system consisted of a xenon lamp, an infrared camera, an analytical balance, and a computer. The xenon lamp source simulated solar radiation, and the simulated solar irradiance was measured to be 1 kW / m² using a full-spectrum optical power meter. 2 The evaporator surface is vertically irradiated, and the surface temperature of the evaporator is monitored in real time by an infrared camera. The changes in water quality are recorded by an analytical balance and a connected computer.

[0051] from Figure 3 As shown in the light irradiation experiment (a), compared with pure PVA hydrogel, the PVA / modified phase change microcapsule composite fiber membrane with a mass percentage of 50 wt% prepared in step three of Example 3 has better photothermal conversion capability. From the evaporation experiment (… Figure 3As can be seen from (b) and (c), the evaporation rate of the interfacial evaporator prepared in step four of Example 3 can reach 2.616 kg / (m²) under illumination. 2 ·h), and even after one hour of irradiation, the evaporation rate of the interfacial evaporator can still reach 1.511 kg / (m³). 2 ·h). However, when only the composite fiber membrane from step three of Example 3 lacks PVA hydrogel ( Figure 3 (d) Under sunlight, the evaporation rate is only 2.104 kg / (m³). 2 (h) Compared with the presence of PVA hydrogel, it can be seen that the presence of PVA hydrogel can increase the interfacial evaporation rate. In summary, adding modified phase change microcapsules to PVA spinning solution can significantly improve the heat storage capacity of composite fiber membranes and endow the fiber membranes with excellent photothermal conversion capabilities. The combination of composite fiber membranes and PVA hydrogels can also have excellent photothermal conversion and heat storage capabilities, meeting the application requirements of solar interfacial evaporators for day and night operation.

[0052] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An integrated solar interface evaporation material with photothermal conversion and heat storage functions, characterized in that... It consists of two layers, with the upper layer being a bifunctional layer that has photothermal conversion and heat storage functions, and the lower layer being a hydrophilic layer; the bifunctional layer is composed of modified phase change microcapsules and PVA composite fiber membrane, and the hydrophilic layer is composed of PVA hydrogel.

2. The integrated solar interface evaporation material with photothermal conversion and heat storage functions according to claim 1, characterized in that: The thickness of the dual-functional layer is 0.5-1.5 mm; the thickness of the hydrophilic layer is 3-5 mm.

3. A method for preparing an integrated solar interface evaporation material with photothermal conversion and heat storage functions according to any one of claims 1-2, characterized in that... Includes the following steps: S1: Melamine and formaldehyde aqueous solution are uniformly dispersed in water, and after adjusting the pH, the mixture is heated and stirred to prepare melamine prepolymer solution A; emulsifier is dissolved in water, and the pH is adjusted to obtain emulsifier solution B; phase change material is stirred and emulsified with solution B to obtain solution C; solution A and solution C are mixed, heated and stirred to react and generate a polymer shell that encapsulates the phase change material and nucleating agent; the resulting reactants are washed and freeze-dried to obtain phase change microcapsules. S2: The phase change microcapsule material obtained in step S1 is dispersed in water by ultrasonication, and then gum arabic powder is added to it. The mixture is stirred evenly at room temperature to prepare phase change microcapsule solution A; silver salt is dispersed in water, and then ammonia is added to prepare silver solution B; solution A and solution B are mixed evenly, a reducing agent is added, the pH is adjusted, and the mixture is stirred to react, so that the silver ions are completely reduced to silver particles that adhere to the surface of the phase change microcapsules. The resulting reactants are washed with water by centrifugation, and then freeze-dried to obtain the modified phase change microcapsule material. S3: PVA, water and modified phase change microcapsules are mixed and stirred evenly at room temperature to prepare a spinning solution. A bifunctional layer is constructed by electrospinning to obtain a PVA / modified phase change microcapsule composite fiber membrane. S4: Place the composite fiber membrane obtained in step S3 into a mold, stir PVA, water, water-soluble salt and PMMA evenly at room temperature, pour into the mold, place the mold on a cold table for unidirectional freezing, and then freeze-dry; soak the dried product in water to remove salt particles; then soak it in acetone solution to remove PMMA; then freeze-dry again; subject the product after the second drying to freeze-thaw cycles to construct a hydrophilic hydrogel layer, and after completing the construction of the hydrophilic hydrogel layer, dry it to obtain an integrated solar interface evaporation material.

4. The method for preparing the integrated solar interface evaporation material with photothermal conversion and heat storage functions according to claim 3, characterized in that: The phase change material mentioned in step S1 is at least one of octadecane, eicosane, and docosane; The emulsifier mentioned in step S1 is at least one of styrene-maleic anhydride copolymer and ethylene-maleic anhydride copolymer; The preparation of melamine prepolymer solution A by heating and stirring in step S1 refers to stirring at 60-90℃ for 1-3 hours. The pH adjustment mentioned in step S1 refers to adjusting the pH to 4-6; The solution C obtained by stirring and emulsifying in step S1 refers to stirring at 70-90℃ for 2-3 hours; The heating and stirring reaction described in step S1 to generate a polymer shell that encapsulates the phase change material and nucleating agent refers to stirring at 70-90℃ for 1-3 hours.

5. The method for preparing the integrated solar interface evaporation material with photothermal conversion and heat storage functions according to claim 3, characterized in that: The mass ratio of melamine, formaldehyde aqueous solution, emulsifier, and phase change material in step S1 is (1-2):(4-6):(1-2):(15-20); the concentration of formaldehyde aqueous solution is 20-37%. In step S1, sodium dodecyl sulfate can be added to assist in emulsification when preparing solution C. The weight of sodium dodecyl sulfate should satisfy the mass ratio of melamine to sodium dodecyl sulfate as (1-2):(0.5-1).

6. The method for preparing the integrated solar interface evaporation material with photothermal conversion and heat storage functions according to claim 3, characterized in that: The silver salt mentioned in step S2 is at least one of silver nitrate, silver acetate, and silver citrate; the reducing agent is at least one of glucose, ascorbic acid, sodium citrate, and polyvinylpyrrolidone.

7. The method for preparing the integrated solar interface evaporation material with photothermal conversion and heat storage functions according to claim 3, characterized in that: The mass ratio of phase change microcapsules, gum arabic, silver salt, ammonia, and reducing agent in step S2 is (3-4):(3-4):(1-2):(1-2):(1-2); The concentration of ammonia water is 15%-25%; the pH adjustment refers to adjusting the pH to 9-11 with sodium hydroxide; the stirring reaction after pH adjustment refers to stirring at -5 to 5℃ for 1-3 hours.

8. The method for preparing the integrated solar interface evaporation material with photothermal conversion and heat storage functions according to claim 3, characterized in that: The mass ratio of PVA, water and modified phase change microcapsules in step S3 is (1-2):(9-10):(0.5-1.5); In the electrospinning described in step S3, the feeding speed of the spinning solution is 0.0015-0.0030 mm / s, the voltage is 18-25 kV, the receiving roller speed is 200-300 rpm, and the distance between the needle and the receiving roller is 8-10 cm.

9. The method for preparing the integrated solar interface evaporation material with photothermal conversion and heat storage functions according to claim 3, characterized in that: In step S4, the water-soluble salt is at least one of sodium chloride, potassium chloride, and lithium chloride; in step S4, the mass ratio of PVA, water, water-soluble salt, and PMMA is (1-2):(8-9):(0.2-0.3):(0.05-0.1); in step S4, the cooling table temperature is -30℃, and the freezing rate is 2-5℃ / min; in step S4, the soaking time in water is 12-24h; the soaking time in acetone is 12-24h; the freezing temperature is -30~-10℃, the freezing time is 12-24h, the thawing temperature is 20-30℃, the thawing time is 12-24h, and the number of freeze-thaw cycles is 3-5 times; the drying refers to drying in an oven at 30-80℃.

10. The application of the integrated solar interface evaporation material with photothermal conversion and heat storage functions as described in claim 1 or 2 in solar interface evaporation, seawater desalination, and solar thermal management.

Images