A photothermal-electrothermal evaporation device and a preparation method and application thereof

Abstract

The application belongs to the field of seawater desalination, and particularly relates to a photothermal-electrothermal evaporation device and a preparation method and application thereof, and comprises the following steps: S1: adding boron nitride into epoxy resin and stirring to form a mixed solution, coating the mixed solution on the surface of stainless steel wire cloth and drying, repeating the coating and drying process for several times to obtain an electrothermal layer; S2: stacking cotton fabric and the electrothermal layer obtained in step S1 to form an intermediate layer, then growing photothermal hydrogels on the two side surfaces of the intermediate layer, standing and freezing to obtain the photothermal-electrothermal evaporation device. Compared with the prior art, the application solves the problems of the existing evaporation device in the prior art, such as electric energy loss, unstable electrothermal performance, high voltage dependence and limitation to interface floating. The scheme constructs a sandwich-structured photothermal-electrothermal evaporation device, which has excellent photothermal-electrothermal performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of seawater desalination, and particularly relates to a photothermal-electrothermal evaporation device and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of industry and the rapid increase of global population, the total global water consumption continues to rise. By 2050, more than half of the world's population will face the dilemma of freshwater shortage. Seawater is one of the most abundant resources on earth, accounting for more than 70% of the earth's surface. Using seawater desalination to produce freshwater is one of the effective ways to effectively alleviate the freshwater crisis. For this reason, people have developed a variety of seawater desalination technologies, including seawater distillation, electrodialysis, reverse osmosis, etc. However, these methods require direct or indirect consumption of a large amount of fossil energy, increasing the cost and causing secondary environmental pollution.

[0003] Solar energy as a green and sustainable energy, using it for seawater evaporation can effectively reduce the consumption of traditional fossil energy, and has attracted widespread attention. The core of solar seawater desalination is to develop an evaporator based on photothermal materials. Under strong light conditions, the evaporator absorbs light energy through photothermal materials and converts it into heat energy, which is then transferred to the material surface for evaporation of seawater. However, most of the world's regions and times are in darkness or weak light conditions, resulting in suboptimal evaporation performance of most evaporators. Therefore, there is an urgent need to develop a new type of solar evaporator to achieve all-weather seawater desalination to obtain freshwater.

[0004] In the face of the problem of low evaporation rate of traditional evaporators in darkness or weak light conditions, coupling electrothermal conversion technology is considered an effective strategy to solve this problem. The core is to develop high-conductivity photothermal material evaporators (such as graphene oxide aerogel, carbon nanotube aerogel, Mxene aerogel, metal-based materials, and carbon fiber cloth, etc.) or photothermal material coupled with conductive material evaporators (such as aerogel / copper sheet, carbon fiber / stainless steel wire, etc.). However, these evaporators still have the following problems: (1) In the process of electrification, electrons will directly contact seawater, resulting in energy loss and unstable electrothermal performance; (2) A higher voltage is required for electrothermal evaporation, showing high voltage dependence; (3) The evaporation mode is limited to interface floating, with defects such as insufficient water supply and weak salt precipitation resistance. SUMMARY

[0005] The purpose of the present application is to solve at least one of the above problems by providing a photothermal-electrothermal evaporation device and a preparation method and application thereof, to solve the problems of energy loss, unstable electrothermal performance, high voltage dependence, and limitation to interface floating in the prior art. The present application constructs a sandwich-structured photothermal-electrothermal evaporator with excellent photothermal-electrothermal performance.

[0006] The application aims to realize the technical scheme as follows.

[0007] The application discloses a preparation method of a photothermal-electrothermal evaporation device.

[0008] S1: boron nitride is added to epoxy resin and stirred to form a mixed solution, the mixed solution is coated on the surface of stainless steel wire cloth and dried, and the coating and drying process is repeated for several times to obtain an electrothermal layer;

[0009] S2: cotton fabric and the electrothermal layer obtained in step S1 are stacked to form an intermediate layer (one layer of electrothermal layer is stacked on each side of the cotton fabric, i.e. ABA structure), and then photothermal hydrogel is prepared by growing on the surfaces of the two sides of the intermediate layer, and the photothermal-electrothermal evaporation device is obtained by standing and freezing.

[0010] Preferably, in step S1, the boron nitride accounts for 10-60% of the total mass of boron nitride and epoxy resin, and the concentration of epoxy resin in the boron nitride and epoxy resin is 0.1-2 g / g.

[0011] Preferably, in step S1, the stainless steel wire cloth is subjected to ultrasonic pretreatment, and the ultrasonic pretreatment is carried out in an equal-volume proportion of ethanol, water and acetone solution.

[0012] Preferably, in step S1, the drying temperature is 40-100 DEG C.

[0013] Preferably, in step S1, the coating and drying process is repeated for 3-10 times.

[0014] Preferably, in step S2, the cotton fabric is subjected to ultrasonic pretreatment, and the ultrasonic pretreatment is carried out in an equal proportion of ethanol, water and acetone solution.

[0015] Preferably, in step S2, the cotton fabric is cotton cloth.

[0016] Preferably, in step S2, the photothermal hydrogel is a hydrogel containing a photothermal material; the photothermal material is graphite, graphene, carbon nanotube or graphene oxide, and the concentration is 0.01-0.5 g / L; the hydrogel is chitosan, polyvinyl alcohol, polyacrylic acid or polyethylene glycol, etc., and the concentration is 0.01-0.5 g / L; and the photothermal hydrogel is obtained by uniformly mixing the photothermal material in the hydrogel solution and then freezing and cross-linking.

[0017] Preferably, in step S2, the standing time is 12-24 h, and the temperature is 20-30 DEG C; and the freezing temperature is-60-0 DEG C, and the time is 12-24 h.

[0018] The second aspect of the present application discloses a photo-thermal-electro-thermal evaporation device prepared by the preparation method of any one of the above.

[0019] The third aspect of the present application discloses an application of the photo-thermal-electro-thermal evaporation device in seawater desalination.

[0020] Preferably, the photo-thermal-electro-thermal evaporation device is applied to a light-hanging type device, and seawater evaporation under the conditions of light irradiation and power supply can realize efficient and all-weather continuous production of fresh water.

[0021] The working principle of the present application is as follows:

[0022] The present application uses cotton fabric as a substrate, and sequentially constructs an electrothermal layer and a photo-thermal gel layer on the surface of the substrate to jointly form a photo-thermal-electro-thermal evaporation device. First, a layer of heat-conducting insulating material is attached to the surface of the stainless steel wire cloth by dip coating to prepare an electrothermal layer, which can effectively transfer Joule heat and inhibit the entry of electrons into water, thereby ensuring excellent electrothermal performance of the electrothermal layer. Then, using the cotton fabric and the electrothermal layer as intermediate layers, a hydrogel containing a photo-thermal material is grown on the upper and lower surfaces of the intermediate layers by freeze crosslinking, thereby constructing a sandwich-structured photo-thermal-electro-thermal evaporation device and endowing it with excellent photo-thermal-electro-thermal performance. In addition, by combining the photo-thermal-electro-thermal evaporation device with a hanging evaporation mode, the water supply capacity and salt precipitation resistance of the evaporation device are improved, and efficient and all-weather seawater desalination is realized.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] (1) The present application provides a construction method of a novel photo-thermal-electro-thermal evaporation device, which has the characteristics of simple preparation, stable effect, and good mechanical performance;

[0025] (2) Water vapor can be generated from each surface of the hydrogel, increasing the area of steam generation and improving the steam generation efficiency;

[0026] (3) Compared with traditional all-weather evaporation devices, the electrothermal layer in the present application can quickly transfer Joule heat, while avoiding direct contact between electrons and seawater and reducing energy loss;

[0027] (4) The present application provides a light-hanging type all-weather evaporation device, which exhibits a high photo-thermal-electro-thermal synergistic evaporation rate, and provides a new idea for seawater desalination to obtain fresh water. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Figure 1 is a flowchart of the preparation method of the photo-thermal-electro-thermal evaporation device;

[0029] Figure 2Physical photos and scanning electron microscope images of the photo-thermal layer (a) and the electro-thermal layer (b) of Example 1;

[0030] Figure 3 UV-visible-near infrared absorption spectrum of the photo-thermal layer (a) and the voltammetry characteristic curve of the electro-thermal layer (b) of Example 1;

[0031] Figure 4 Schematic diagram of the light-hanging type all-weather evaporation device (a) and the photo-thermal (b), electro-thermal (c) and photo-thermal + electro-thermal (d) evaporation performance test of Example 1. DETAILED DESCRIPTION

[0032] The present application will be described in detail below with reference to the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application. In addition, it should be understood that after reading the content taught by the present application, those skilled in the art can make various modifications or modifications to the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0033] As described below, if not specifically stated, the reagents used are conventional commercially available products, and the methods used are well-known means in the art.

[0034] A photo-thermal-electro-thermal evaporation device, which is composed of cotton cloth, an electro-thermal layer of insulating stainless steel wire cloth and a photo-thermal hydrogel, i.e. the cotton cloth and the electro-thermal layer are used as the intermediate layer, and the photo-thermal hydrogel is constructed on the upper and lower surfaces to form a sandwich structure. The constructed photo-thermal-electro-thermal evaporation device can not only effectively convert photo-thermal and electro-thermal energy, but also realize all-weather photo-thermal-electro-thermal synergistic evaporation.

[0035] A preparation method of a photo-thermal-electro-thermal evaporation device, comprising:

[0036] (1) First, a proper amount of boron nitride is added to an epoxy resin solution and stirred for 1-2 h, then the above mixed solution is brushed on the pretreated stainless steel wire cloth, and after sufficient immersion coating, it is dried, and the operation is repeated for several times, to obtain an electro-thermal layer.

[0037] (2) The above electro-thermal layer and the pretreated cotton cloth are stacked together, and a hydrogel containing photo-thermal material is grown on the upper and lower surfaces, and is left to stand and freeze for 12-24 h, to obtain a photo-thermal-electro-thermal evaporation device.

[0038] In step (1), the mass fraction of boron nitride is 10%-60%; the concentration of epoxy resin is 0.1-2 g / g.

[0039] In step (2), the photothermal material is graphite, graphene, carbon nanotube or graphene oxide, etc., and the concentration is 0.01-0.5 g / L; the hydrogel is chitosan, polyvinyl alcohol, polyacrylic acid or polyethylene glycol, etc., and the concentration is 0.01-0.5 g / L; the standing time is 12-24 h, and the temperature is 20-30℃; and the freezing temperature is-60-0℃.

[0040] The application of a photothermal-electrothermal evaporation device, in particular, the application of a light-hanging type interface evaporator based on a novel photothermal-electrothermal evaporation device, which combines the novel photothermal-electrothermal evaporation device with a light-hanging type evaporation device to construct a light-hanging type all-weather evaporator.

[0041] Example 1

[0042] The construction process of the novel photothermal-electrothermal evaporation device is shown in Figure 1 .

[0043] A 1.5×1.5 cm 2 stainless steel wire cloth (SWWC) is placed in a mixed solution of anhydrous ethanol, acetone and deionized water (in equal proportions) for ultrasonic treatment for 40 min, and then washed and dried after ultrasonic treatment; 0.075 g of boron nitride (BN) and 0.25 g of epoxy resin (EP) are added to 0.5 g of diluent (polypropylene glycol diglycidyl ether) respectively, and stirred for 1.5 h to obtain a mixed solution; 0.1 g of curing agent (2-ethyl-4-methylimidazole) is added dropwise to the above mixed solution, which is then uniformly brushed on the pretreated stainless steel wire cloth, and dried in an 80℃ oven for 20 min, and the operation is repeated for 3 times to obtain an electrothermal layer (SWWC / EP@BN).

[0044] A 2×8 cm 2 cotton cloth is placed in a mixed solution of anhydrous ethanol, acetone and deionized water (in equal proportions) for ultrasonic treatment for 40 min, and then washed and dried after ultrasonic treatment; 0.05 g of dopamine-modified graphite powder (C@PDA) is added to 5 mL of 2% chitosan (CS) solution, and stirred for 30 min to obtain a mixed solution; 0.5 mL of glutaraldehyde crosslinking agent solution is added dropwise to the above mixed solution, and stirred uniformly, and then added to two molds with a volume of 2.5 mL respectively; then the electrothermal layer is placed in the middle position of the cotton cloth as an intermediate layer, and the above two molds are respectively buckled from both sides of the intermediate layer, so that the photothermal hydrogel (CS / PDA@C) is placed and crosslinked on both sides of the intermediate layer for 24 h; then it is placed in a 0℃ refrigerator for freezing for 12 h to obtain a photothermal-electrothermal evaporation device (SWWC / EP@BN+CS / PDA@C).

[0045] The actual photos and scanning electron microscope images of the photothermal layer and the electrothermal layer are as follows:

[0046] As shown in the accompanyingFigure 2 As shown, the photothermal layer hydrogel ( Figure 2 (a)) presents a flaky porous structure, and graphite particles are evenly distributed on its surface; the electric heating layer ( Figure 2 (b) shows that the surface of the stainless steel wire is uniformly covered with a layer of boron nitride / epoxy resin coating, proving the successful synthesis of the photothermal layer and the electric heating layer.

[0047] Ultraviolet-visible-near-infrared absorption spectrum of the photothermal layer and volt-ampere characteristic curve of the electric heating layer:

[0048] The results are as attached Figure 3 As shown, the CS / PDA@C photothermal gel layer ( Figure 3 (a)) can achieve a light absorption efficiency of 94%, and the electric heating layer ( Figure 3 (b)) exhibits good electrical conductivity.

[0049] Schematic diagram of the all-weather evaporation device with photothermal, electric heating, and photothermal + electric heating performance tests:

[0050] The experimental device is as attached Figure 4 As shown in (a) (refer to the phototropic evaporation device in CN111348708A), the evaporation performance of the phototropic suspension all-weather evaporator was tested: under a simulated light intensity of one times (1.0 kW m -2 , i.e. 1sun, simulating sunlight) and / or 2V DC power supply, two water tanks were placed horizontally, the cotton fabric of the new photothermal-electrothermal evaporation device was fixed between the two tanks with a magnet, the light source was irradiated on the photothermal layer, and the electrode clip of the power supply was connected to the electric heating layer. Room temperature was maintained during the test, and the entire device was placed on an electronic balance. The mass change of the entire device after different evaporation times was recorded, and the evaporation rate under different time conditions was calculated.

[0051] The results are as attached Figure 4 (b), (c) and (d) show the mass loss of the new photothermal-electrothermal evaporation device in simulated seawater. The device has excellent photothermal, electrothermal and photothermal-electrothermal evaporation performance. Figure 4 In (b), 20, 40, and 300 mesh SEB+CPC represent 20-mesh SWWC / EP@BN+CS / PDA@C, 40-mesh SWWC / EP@BN+CS / PDA@C, and 300-mesh SWWC / EP@BN+CS / PDA@C, respectively, where mesh represents the number of holes per unit area.

[0052] Example 2

[0053] The preparation steps of this embodiment are basically the same as those of Example 1, with the main difference being that the amount of boron nitride added is 0.25 g. The specific steps are as follows:

[0054] 1.5×1.5cm 2 Stainless steel wire cloth (SWWC) was placed in a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportions) and ultrasonicated for 40 minutes. After the ultrasonication, it was washed and dried; then 0.25g of boron nitride (BN) and 0.25g of epoxy resin (EP) were added to 0.5g of diluent (polypropylene glycol diglycidyl ether) respectively, and stirred for 1.5h to obtain a mixed solution; after 0.1g of curing agent (2-ethyl-4-methylimidazole) was added dropwise to the above mixed solution, it was evenly brushed on the pretreated stainless steel wire cloth, placed in an 80℃ oven and dried for 20min. The operation was repeated 3 times to obtain the electric heating layer (SWWC / EP@BN).

[0055] 2×8cm 2 The cotton cloth was placed in a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportions) and ultrasonicated for 40 minutes. After the ultrasonication, it was washed and dried; then 0.05g of dopamine-modified graphite powder (C@PDA) was added to 5mL of 2% chitosan (CS) solution and stirred for 30 minutes to obtain a mixed solution; 0.5mL of glutaraldehyde crosslinker solution was added dropwise to the above mixed solution, and after stirring evenly, it was added to two molds with a volume of 2.5mL respectively; then the electric heating layer was placed in the middle position of the cotton cloth as the middle layer, and the above two molds were buckled together from both sides of the middle layer, and the photothermal water gel (CS / PDA@C) was allowed to crosslink on both sides of the middle layer for 24 hours; then it was placed in a 0℃ refrigerator and frozen for 12 hours to obtain a photothermal-electrothermal evaporation device (SWWC / EP@BN+CS / PDA@C).

[0056] Example 3

[0057] The preparation steps of this embodiment are basically the same as those of Example 1, with the main difference being that the amount of boron nitride added is 0.05 g. The specific steps are as follows:

[0058] 1.5×1.5cm 2 Stainless steel wire cloth (SWWC) was placed in a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportions) and ultrasonicated for 40 minutes. After the ultrasonication, it was washed and dried; then 0.05g of boron nitride (BN) and 0.25g of epoxy resin (EP) were added to 0.5g of diluent (polypropylene glycol diglycidyl ether) respectively, and stirred for 1.5h to obtain a mixed solution; after 0.1g of curing agent (2-ethyl-4-methylimidazole) was added dropwise to the above mixed solution, it was evenly brushed on the pretreated stainless steel wire cloth, placed in an 80℃ oven and dried for 20min. The operation was repeated 3 times to obtain the electric heating layer (SWWC / EP@BN).

[0059] 2×8cm 2cotton cloth into a mixed solution of anhydrous ethanol, acetone and deionized water (in equal proportions) for 40 min of ultrasonic treatment, and then washed and dried after the ultrasonic treatment; 0.05 g of dopamine-modified graphite powder (C@PDA) was added to 5 mL of a 2% chitosan (CS) solution, and stirred for 30 min to obtain a mixed solution; 0.5 mL of glutaraldehyde crosslinking agent solution was added dropwise to the above mixed solution, and then stirred uniformly and added to two molds with a volume of 2.5 mL; then the electrothermal layer was placed in the middle position of the cotton cloth as an intermediate layer, and the above two molds were buckled on one piece from both sides of the intermediate layer, so that the photo-thermal hydrogel (CS / PDA@C) was placed on both sides of the intermediate layer for crosslinking for 24 h; then placed in a 0°C refrigerator for 12 h, and the photo-thermal-electro-thermal evaporation device (SWWC / EP@BN+CS / PDA@C) was obtained.

[0060] Example 4

[0061] The preparation steps of this example are basically the same as those of Example 1, the main difference being that it is placed in a 100°C oven for drying; and the operation is repeated 6 times, and the specific steps are as follows:

[0062] 1.5×1.5 cm 2 of stainless steel wire cloth (SWWC) was placed in a mixed solution of anhydrous ethanol, acetone and deionized water (in equal proportions) for 40 min of ultrasonic treatment, and then washed and dried after the ultrasonic treatment; 0.25 g of boron nitride (BN) and 0.25 g of epoxy resin (EP) were added to 0.5 g of diluent (polypropylene glycol diglycidyl ether) respectively, and stirred for 1.5 h to obtain a mixed solution; 0.1 g of curing agent (2-ethyl-4-methyl imidazole) was added dropwise to the above mixed solution, and then uniformly brushed on the pretreated stainless steel wire cloth, placed in a 100°C oven for drying for 20 min, and the operation was repeated 6 times to obtain the electrothermal layer (SWWC / EP@BN).

[0063] 2×8 cm 2 of cotton cloth was placed in a mixed solution of anhydrous ethanol, acetone and deionized water (in equal proportions) for 40 min of ultrasonic treatment, and then washed and dried after the ultrasonic treatment; 0.05 g of dopamine-modified graphite powder (C@PDA) was added to 5 mL of a 2% chitosan (CS) solution, and stirred for 30 min to obtain a mixed solution; 0.5 mL of glutaraldehyde crosslinking agent solution was added dropwise to the above mixed solution, and then stirred uniformly and added to two molds with a volume of 2.5 mL; then the electrothermal layer was placed in the middle position of the cotton cloth as an intermediate layer, and the above two molds were buckled on one piece from both sides of the intermediate layer, so that the photo-thermal hydrogel (CS / PDA@C) was placed on both sides of the intermediate layer for crosslinking for 24 h; then placed in a 0°C refrigerator for 12 h, and the photo-thermal-electro-thermal evaporation device (SWWC / EP@BN+CS / PDA@C) was obtained.

[0064] Example 5

[0065] The preparation steps of this embodiment are basically the same as those of Example 1, the main difference is that it is placed in a 40°C oven to dry and repeated 10 times, the specific steps are as follows:

[0066] Put 1.5x1.5cm 2 stainless steel wire cloth (SWWC) into a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportion) and ultrasonic for 40 min, after ultrasonic, wash and dry; Then add 0.25g boron nitride (BN) and 0.25g epoxy resin (EP) to 0.5g diluent (polypropylene glycol diglycidyl ether) respectively, stir for 1.5h to get a mixed solution; Add 0.1g curing agent (2-ethyl-4-methyl imidazole) to the above mixed solution, and then brush it evenly on the pretreated stainless steel wire cloth, and dry it in a 40°C oven for 20min, repeat the operation 10 times, and get the electrothermal layer (SWWC / EP@BN).

[0067] Put 2x8cm 2 cotton cloth into a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportion) and ultrasonic for 40 min, after ultrasonic, wash and dry; Then add 0.05g dopamine modified graphite powder (C@PDA) to 5mL 2% chitosan (CS) solution, stir for 30min to get a mixed solution; Add 0.5mL glutaraldehyde crosslinking agent solution to the above mixed solution, and then add two molds with a volume of 2.5mL respectively; Then put the electrothermal layer in the middle position of the cotton cloth as the middle layer, and put the two molds on the both sides of the middle layer respectively, and let the photo-thermal hydrogel (CS / PDA@C) stand crosslinking on both sides of the middle layer for 24h; Then put it in a 0°C refrigerator for 12h, and get the photo-thermal-electro-thermal evaporator (SWWC / EP@BN+CS / PDA@C).

[0068] Example 6

[0069] The preparation steps of this embodiment are basically the same as those of Example 1, the main difference is that the photo-thermal material is graphene, and the hydrogel is polyvinyl alcohol, the specific steps are as follows:

[0070] Put 1.5x1.5cm 2Stainless steel wire cloth (SWWC) was put into a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportion) for ultrasonic treatment for 40 min. After ultrasonic treatment, the stainless steel wire cloth was washed and dried. Then, 0.25 g of boron nitride (BN) and 0.25 g of epoxy resin (EP) were added to 0.5 g of diluent (polypropylene glycol diglycidyl ether) respectively, and stirred for 1.5 h to obtain a mixed solution. After 0.1 g of curing agent (2-ethyl-4-methylimidazole) was added dropwise to the mixed solution, the mixed solution was uniformly brushed on the pretreated stainless steel wire cloth, which was then placed in an 80°C oven for drying for 20 min. The operation was repeated for 3 times to obtain an electrothermal layer (SWWC / EP@BN).

[0071] Cotton cloth with a size of 2x8 cm 2 was put into a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportion) for ultrasonic treatment for 40 min. After ultrasonic treatment, the cotton cloth was washed and dried. Then, 0.05 g of dopamine-modified graphene (GN@PDA) was added to 5 mL of 2% polyvinyl alcohol (PVA) solution, and stirred for 30 min to obtain a mixed solution. After 0.5 mL of glutaraldehyde crosslinking agent solution was added dropwise to the mixed solution and stirred uniformly, the mixed solution was added to two molds with a volume of 2.5 mL respectively. Then, the electrothermal layer was placed in the middle position of the cotton cloth as an intermediate layer, and the two molds were buckled on one piece from both sides of the intermediate layer. The photo-thermal hydrogel (PVA / PDA@GN) was placed and crosslinked on both sides of the intermediate layer for 24 h. Subsequently, the photo-thermal-electro-thermal evaporation device (SWWC / EP@BN+PVA / PDA@GN) was placed in a refrigerator at 0°C for 12 h.

[0072] Example 7

[0073] The preparation steps of this example are basically the same as those of Example 1, the main difference is that the photo-thermal material is carbon nanotube, and the hydrogel is polyethylene glycol. The specific steps are as follows:

[0074] Stainless steel wire cloth (SWWC) with a size of 1.5x1.5 cm 2 was put into a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportion) for ultrasonic treatment for 40 min. After ultrasonic treatment, the stainless steel wire cloth was washed and dried. Then, 0.25 g of boron nitride (BN) and 0.25 g of epoxy resin (EP) were added to 0.5 g of diluent (polypropylene glycol diglycidyl ether) respectively, and stirred for 1.5 h to obtain a mixed solution. After 0.1 g of curing agent (2-ethyl-4-methylimidazole) was added dropwise to the mixed solution, the mixed solution was uniformly brushed on the pretreated stainless steel wire cloth, which was then placed in an 80°C oven for drying for 20 min. The operation was repeated for 3 times to obtain an electrothermal layer (SWWC / EP@BN).

[0075] Cotton cloth with a size of 2x8 cm 2The cotton cloth was placed in a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportions) and ultrasonicated for 40 minutes. After the ultrasonication, it was washed and dried; then 0.05g of dopamine-modified carbon nanotubes (CNT@PDA) was added to 5mL of 2% polyethylene glycol (PEG) solution and stirred for 30 minutes to obtain a mixed solution; 0.5mL of glutaraldehyde crosslinker solution was added dropwise to the above mixed solution, and after stirring evenly, it was added to two molds with a volume of 2.5mL respectively; then the electric heating layer was placed in the middle position of the cotton cloth as the middle layer, and the above two molds were buckled together from both sides of the middle layer, and the photothermal water gel (PEG / PDA@CNT) was allowed to crosslink on both sides of the middle layer for 24 hours; then it was placed in a 0℃ refrigerator and frozen for 12 hours to obtain a photothermal-electrothermal evaporation device (SWWC / EP@BN+PEG / PDA@CNT).

[0076] Example 8

[0077] The preparation steps of this embodiment are basically the same as those of Example 1, with the main difference being that the photothermal material is graphene oxide and the hydrogel is polyacrylic acid. The specific steps are as follows:

[0078] 1.5×1.5cm 2 Stainless steel wire cloth (SWWC) was placed in a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportions) and ultrasonicated for 40 minutes. After the ultrasonication, it was washed and dried; then 0.25g of boron nitride (BN) and 0.25g of epoxy resin (EP) were added to 0.5g of diluent (polypropylene glycol diglycidyl ether) respectively, and stirred for 1.5h to obtain a mixed solution; after 0.1g of curing agent (2-ethyl-4-methylimidazole) was added dropwise to the above mixed solution, it was evenly brushed on the pretreated stainless steel wire cloth, placed in an 80℃ oven and dried for 20min. The operation was repeated 3 times to obtain the electric heating layer (SWWC / EP@BN).

[0079] 2×8cm 2 The cotton cloth was placed in a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportions) and ultrasonicated for 40 minutes. After the ultrasonication, it was washed and dried; then 0.05g of dopamine-modified graphene oxide (GO@PDA) was added to 5mL of 2% polyacrylic acid (PAA) solution and stirred for 30 minutes to obtain a mixed solution; 0.5mL of glutaraldehyde crosslinker solution was added dropwise to the above mixed solution, and after stirring evenly, it was added to two molds with a volume of 2.5mL respectively; then the electric heating layer was placed in the middle position of the cotton cloth as the middle layer, and the above two molds were buckled together from both sides of the middle layer, and the photothermal water gel (PAA / PDA@GO) was allowed to crosslink on both sides of the middle layer for 24 hours; then it was placed in a 0℃ refrigerator and frozen for 12 hours to obtain a photothermal-electrothermal evaporation device (SWWC / EP@BN+PAA / PDA@GO).

[0080] Example 9

[0081] The preparation steps of this example are basically the same as those of Example 1, the main difference is that the cross-linking is at room temperature for 16 h, and the freezing is at -60℃ for 18 h, the specific steps are as follows:

[0082] Put 1.5 x 1.5 cm 2 of stainless steel wire cloth (SWWC) into a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportion) and ultrasonic for 40 min, then wash and dry after ultrasonic; Then add 0.25 g of boron nitride (BN) and 0.25 g of epoxy resin (EP) to 0.5 g of diluent (polypropylene glycol diglycidyl ether) respectively, stir for 1.5 h to obtain a mixed solution; Add 0.1 g of curing agent (2-ethyl-4-methyl imidazole) to the above mixed solution, then evenly brush it on the pretreated stainless steel wire cloth, and dry it in an 80℃ oven for 20 min, repeat the operation for 3 times, and then the electrothermal layer (SWWC / EP@BN) is obtained.

[0083] Put 2 x 8 cm 2 of cotton cloth into a mixed solution of anhydrous ethanol, acetone and deionized water (equal proportion) and ultrasonic for 40 min, then wash and dry after ultrasonic; Then add 0.05 g of dopamine modified graphite powder (C@PDA) to 5 mL of 2% chitosan (CS) solution, stir for 30 min to obtain a mixed solution; Add 0.5 mL of glutaraldehyde cross-linking agent solution to the above mixed solution, and stir evenly, then add two molds with a volume of 2.5 mL respectively; Then place the electrothermal layer in the middle position of the cotton cloth as the middle layer, and put the two molds on the both sides of the middle layer respectively, and let the photo-thermal hydrogel (CS / PDA@C) stand cross-linking on both sides of the middle layer for 16 h; Then put it in a -60℃ refrigerator for 18 h, and then the photo-thermal-electro-thermal evaporator (SWWC / EP@BN+CS / PDA@C) is obtained.

[0084] Example 10

[0085] The preparation steps of this example are basically the same as those of Example 1, the main difference is that the cross-linking is at room temperature for 12 h, and the freezing is at -30℃ for 24 h, the specific steps are as follows:

[0086] Put 1.5 x 1.5 cm 2The stainless steel wire cloth (SWWC) was put into a mixed solution of anhydrous ethanol, acetone and deionized water (in equal proportions) for ultrasonic treatment for 40 min. After ultrasonic treatment, the stainless steel wire cloth was washed and dried. Then, 0.25 g of boron nitride (BN) and 0.25 g of epoxy resin (EP) were added to 0.5 g of diluent (polypropylene glycol diglycidyl ether) respectively, and stirred for 1.5 h to obtain a mixed solution. After 0.1 g of curing agent (2-ethyl-4-methylimidazole) was added dropwise to the mixed solution, the mixed solution was uniformly brushed on the pretreated stainless steel wire cloth, which was then dried in an 80°C oven for 20 min. The above operation was repeated for 3 times to obtain an electrothermal layer (SWWC / EP@BN).

[0087] Two 2×8 cm 2 pieces of cotton cloth were put into a mixed solution of anhydrous ethanol, acetone and deionized water (in equal proportions) for ultrasonic treatment for 40 min. After ultrasonic treatment, the cotton cloth was washed and dried. Then, 0.05 g of dopamine-modified graphite powder (C@PDA) was added to 5 mL of 2% chitosan (CS) solution, and stirred for 30 min to obtain a mixed solution. After 0.5 mL of glutaraldehyde crosslinking agent solution was added dropwise to the mixed solution and stirred uniformly, the mixed solution was added to two molds with a volume of 2.5 mL respectively. Then, the electrothermal layer was placed in the middle position of the cotton cloth as an intermediate layer, and the two molds were buckled on one piece from both sides of the intermediate layer. The photo-thermal hydrogel (CS / PDA@C) was placed and crosslinked on both sides of the intermediate layer for 12 h. Subsequently, the photo-thermal-electrothermal evaporation device (SWWC / EP@BN+CS / PDA@C) was placed in a-30°C refrigerator for freezing for 24 h.

[0088] The above description of the embodiments is for the purpose of enabling a person of ordinary skill in the art to understand and use the application. Those skilled in the art can easily make various modifications to the embodiments, and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A method for preparing a photothermal-electrothermal evaporation device, characterized in that: The method comprises the following steps: S1: adding boron nitride to epoxy resin and stirring to form a mixed solution, coating the mixed solution on the surface of a stainless steel wire cloth and drying, repeating the coating and drying process several times to obtain an electrothermal layer; S2: stacking a cotton fabric and the electrothermal layer obtained in step S1 to form an intermediate layer, then growing photo-thermal hydrogel on both sides of the intermediate layer, standing and freezing to obtain the photo-thermal-electrothermal evaporator.

2. The method of claim 1, wherein the method further comprises: In step S1, the boron nitride accounts for 10-60% of the total mass of boron nitride and epoxy resin, and the concentration of epoxy resin in the boron nitride and epoxy resin is 0.1-2 g / g.

3. The method of claim 1, wherein the method further comprises: In step S1, the stainless steel wire cloth is subjected to ultrasonic pretreatment, and the ultrasonic pretreatment is carried out in an equal proportion of ethanol, water and acetone solution.

4. The method of claim 1, wherein the method further comprises: In step S1, the drying temperature is 40-100℃.

5. The method of claim 1, wherein the method further comprises: In step S1, the coating and drying process is repeated 3-10 times.

6. The method of claim 1, wherein the method further comprises: In step S2, the cotton fabric is subjected to ultrasonic pretreatment, and the ultrasonic pretreatment is carried out in an equal proportion of ethanol, water and acetone solution.

7. The method of claim 1, wherein the method further comprises: In step S2, the photo-thermal hydrogel is a hydrogel containing a photo-thermal material; the photo-thermal material is graphite, graphene, carbon nanotube or graphene oxide, and the concentration is 0.01-0.5 g / L; the hydrogel is chitosan, polyvinyl alcohol, polyacrylic acid or polyethylene glycol, and the concentration is 0.01-0.5 g / L.

8. The method of claim 1, wherein the method further comprises: In step S2, the standing time is 12-24 h at a temperature of 20-30℃, and the freezing temperature is -60-0℃ for 12-24 h.

9. A photothermal- electrothermal evaporation device, characterized in that, The photo-thermal-electrothermal evaporator is prepared by the preparation method of any one of claims 1-8.

10. The photo-thermal-electrothermal evaporator of claim 9 is used in seawater desalination.

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