A salt-resistant photothermal evaporation device, water treatment device and water treatment salt-resistant method

Abstract

The present invention relates to a salt-resistant water treatment device and a salt-resistant method in a water treatment process. Conventional seawater, high-salt brine, etc. are treated by a photothermal absorber device to obtain freshwater resources. Solar energy is used as the sole energy source, and the absorbed solar energy is converted into thermal energy. A thin layer of water body is efficiently and locally heated to promote its rapid evaporation. The device can prevent device failure caused by salt crystallization, and is energy-saving and environmentally friendly without increasing environmental energy consumption.

Description

Technical Field

[0001] The invention relates to a photothermal evaporation device for a salt-resistant water treatment device, a water treatment device and a salt-resistant method in a water treatment process, belonging to the field of water treatment. Background Art

[0002] Energy and water resources are crucial for human survival. Traditional energy-driven water treatment technologies, such as thermal and membrane-based water treatment processes, suffer from drawbacks such as high fossil energy consumption and environmental pollution. The current mainstream membrane process is reverse osmosis, which utilizes specialized membrane materials to apply pressure to seawater, forcing it to pass through the membrane while retaining salt, thereby producing fresh water. This pressure requires high-pressure pumps, which consume electricity and are difficult to apply in remote areas. Furthermore, the generation of electricity itself may consume fossil fuels such as coal, causing significant environmental pollution. Thermal methods primarily evaporate water from seawater through boiling, then condense and collect the vapor to produce fresh water. These methods primarily utilize low-temperature, multi-effect distillation and multi-stage flash evaporation technologies, but these methods consume fossil fuels such as coal, causing atmospheric pollution. Furthermore, the investment required for a single desalination project is substantial, making it more suitable for centralized water supply in densely populated and developed areas and less applicable to islands, deserts, and other impoverished regions. Compared to traditional energy sources, solar energy, as a green and sustainable resource, offers a new energy source for water resource utilization.

[0003] Solar-based photothermal interfacial evaporation is currently attracting attention for water treatment processes. This method offers the advantages of high photothermal conversion efficiency, ease of scalability, and low cost. However, a challenge with this method is the occurrence of salt precipitation at the hydrophilic photothermal interface. The precipitated salt crystals coat the surface of the evaporating material, reducing its light absorption, significantly degrading its performance and stability, and even rendering it ineffective. Summary of the Invention

[0004] In order to solve the problem in the prior art that salt precipitation occurs at the photothermal interface, which leads to reduced performance of a photothermal evaporation device, the present invention provides, on the one hand, a salt resistance method in a water treatment process. The method utilizes the self-rotation of a photothermal evaporation device to achieve the redissolution of salt precipitated on the photothermal evaporation interface into water. The specific scheme adopted is as follows: the photothermal evaporation device uses solar energy as an energy source, absorbs solar energy and converts it into heat to heat and evaporate water; after the water evaporates, the precipitated salt crystallizes on the photothermal evaporation device, and the accumulation of salt causes the center of gravity of the photothermal evaporation device to shift, causing the photothermal evaporation device to self-rotate; the self-rotation causes the salt precipitation area of ​​the photothermal evaporation device to be immersed in water, and the salt dissolves into the water; a portion of the photothermal evaporation device is placed below the water surface, and the other portion is placed above the water surface.

[0005] On the other hand, the present invention provides a salt-resistant photothermal evaporation device. During salt precipitation, the device rotates due to the asymmetric deadweight of the system. The precipitated salt crystals will redissolve in the evaporated water, realizing surface self-removal (desalination), solving the problems of salt precipitation and pollution at the evaporation interface, and greatly improving the evaporation efficiency. This device provides a new solution for the efficient treatment of highly concentrated brine using solar energy.

[0006] The technical solution adopted is as follows: the photothermal evaporation device is at least partially hydrophilic, and water is transported within the photothermal evaporation device through the hydrophilic photothermal evaporation device; the photothermal evaporation device is a three-dimensional structure, and the three-dimensional structure is a regular or irregular structure. When treating salty water bodies, the three-dimensional photothermal evaporation device floats in the water body, with one part placed below the water surface and the other part placed above the water surface. The photothermal evaporation device placed below the water surface contacts the water body and transfers the water body to the part below the water surface; the water body evaporates and precipitates salt on the photothermal evaporation material above the water surface, and the center of gravity of the photothermal evaporation device is deflected to cause the photothermal evaporation device to rotate, switching the area of ​​the photothermal evaporation device below the water surface.

[0007] The present invention realizes efficient water evaporation at the interface (desalination) directly driven by solar energy by constructing a novel photothermal evaporation system based on interface heating technology.

[0008] The photothermal absorber device consists of two key components: a support body with through holes at symmetrical positions and a photothermal evaporation material with a uniformly blackened and hydrophobicized outer surface. The support body allows the device to float on the water surface to avoid inefficient bulk heating, and the photothermal evaporation material with a blackened and hydrophobicized surface is firmly and tightly attached to the outer layer of the hollow foam cylinder. When the above device floats freely on the surface of the seawater to be treated, the seawater in the bulk phase can only enter the water-absorbing body of the photothermal evaporation material from the through holes set at the bottom of the support body. Subsequently, under the combined action of the intrinsic capillary force of the internal reticular structure of the photothermal evaporation material and the Marangoni effect, the bulk phase seawater is spontaneously pumped from bottom to top to the top of the photothermal evaporation material, so that the seawater is fully filled in the photothermal evaporation material, that is, a water film to be evaporated is formed. At the same time, because the outer side of the photothermal evaporation material has been functionally hydrophobicized, it can effectively prevent the water absorbed in the photothermal evaporation material from overflowing from the outer side, so that during the continuous photothermal water evaporation process In this process, salt accumulation is effectively prevented at the photothermal interface, ensuring a continuously efficient water evaporation rate. Salt preferentially precipitates at the hydrophilic / hydrophobic interface between the photothermal evaporation material and the support, growing and gradually diffusing into the through-holes. When salt accumulation shifts the center of gravity of the photothermal evaporation device, the device undergoes self-rotation, exposing a new evaporation surface for continued operation. This self-rotation immerses the salt-precipitating area of ​​the device in water, where the salt absorbs water and dissolves back into the bulk seawater. This clears the salt-precipitating pores, providing a continuous water supply for continued evaporation and initiating the next evaporation-self-rotation-evaporation cycle. This device prevents device failure caused by salt crystallization and is energy-efficient and environmentally friendly, eliminating the need for increased environmental energy consumption.

[0009] In another aspect, the present invention further provides a water treatment device comprising the above-mentioned photothermal evaporation device.

[0010] The beneficial effects of the present invention include: obtaining freshwater resources by treating conventional seawater, high-salt brine, etc. through a photothermal absorber device, using solar energy as the sole energy source, converting the absorbed solar energy into thermal energy, and efficiently and locally heating a thin layer of water to promote its rapid evaporation; the device can prevent device failure caused by salt crystallization, and is energy-saving and environmentally friendly, without increasing environmental energy consumption;

[0011] In the present invention, the salt precipitated after the water evaporates stays on the photothermal evaporation interface. As the salt accumulates, the center of gravity of the photothermal evaporation device shifts, driving the photothermal evaporation device to rotate and achieve self-rotation.

[0012] In the present invention, the water immersion area is switched by self-rotation, and the salt on the photothermal evaporation device is automatically dissolved, thereby stabilizing the light absorption and heat generation performance of the photothermal evaporation device;

[0013] The present invention designs a suitable draft depth to achieve the synergy between the rotation sensitivity of the photothermal evaporation device and the photothermal evaporation efficiency;

[0014] The present invention achieves internal hydrophilicity and external hydrophobicity through hydrophilic and hydrophobic treatment of the photothermal evaporation material, which can not only ensure the transmission of water inside the photothermal evaporation material, but also prevent salt from forming on the outer surface of the photothermal evaporation material, which affects the photothermal absorption performance.

[0015] The present invention adopts a photothermal evaporation material with a porous structure of specific size to provide a water transmission channel and a space for salt precipitation;

[0016] The device or method of the present invention uses solar energy or self-driven power as an energy source, which is energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A front view of the photothermal evaporation device in Example 1;

[0018] Figure 2 A side view of the photothermal evaporation device in Example 1;

[0019] Figure 3 Figure 4 shows the structure of the support body;

[0020] Figure 4 Photothermal evaporation material structure diagram;

[0021] Figure 5 Photothermal evaporation rate diagram in Example 1 and Comparative Example 1;

[0022] Figure 6 A diagram of salt formation after the photothermal evaporation device in Example 1 is disassembled;

[0023] Figure 7 Photothermal evaporation rate diagram in Example 2;

[0024] Figure 8 Photothermal evaporation rate diagram of the device in Example 3;

[0025] Figure 9 Photothermal evaporation rate diagram of the device in Comparative Example 2;

[0026] Figure 10 Support structure diagram.

[0027] In the figure, 1, support body, 2, light and heat absorbing material, 201, first surface, 202, second surface, 203, side surface, 3, through hole (water guide hole), 4, hollow cavity, 5, water. DETAILED DESCRIPTION

[0028] The present invention will be further explained in detail below in conjunction with specific embodiments, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0029] The water treatment device of the present invention is used to treat saltwater, such as salt lake water, seawater, and industrial wastewater. The device includes a photothermal evaporation device, which is a three-dimensional structure. When in use, it floats on the water surface, with a portion immersed in the water and another portion above the water surface. The photothermal evaporation device is at least partially hydrophilic, or the entire device can be hydrophilic. The photothermal evaporation device placed in the water absorbs water and, using its hydrophilic effect, transports the water to the portion above the water surface, where it evaporates to separate salt and water. The precipitated salt crystallizes at the evaporation interface. As salt accumulates, the center of gravity of the photothermal evaporation device shifts, causing the device floating on the water surface to rotate, thereby immersing the salt-precipitating area in the water and redissolving the salt on the photothermal interface. The device uses solar energy as the energy source for salt-water separation, and the center of gravity shift caused by salt precipitation as the power source for the photothermal evaporation device's rotation. This rotation causes the area on the photothermal evaporation device to switch between immersing and dissolving salt and precipitating salt, thereby timely clearing salt from the device and stabilizing device performance.

[0030] The photoevaporation device has a three-dimensional structure, with its center of gravity being the same or different from its geometric center, preferably the same. This arrangement ensures that each area of ​​the device is immersed in water for a uniform amount of time, preventing excessive salt accumulation in certain areas that cannot be cleaned promptly and can degrade the device's performance. The structure of the photoevaporation device can be regular or irregular, and can be a polyhedron or a cylinder. The polyhedron or cylinder preferably has a hollow structure. This facilitates the introduction of water, allowing it to contact the inner surface of the device and evaporate on the outer surface. Furthermore, the hollow structure reduces the depth of salt crystallization within the device, even at the same photoevaporation interface area. This depth refers to the distance between the salt distribution area within the device and the device surface. Reducing this distance helps shorten the salt dissolution time.

[0031] When a CTE device is placed in water, its depth significantly impacts its water treatment efficiency. Immersing the device too shallowly in the water affects water transport, reducing treatment efficiency. Immersing the device too deeply increases heat conduction losses and prevents the full utilization of solar heat. The CTE device's geometric center should be positioned above the liquid surface. In this configuration, the device is sensitive to the deflection of its center of gravity caused by salt precipitation, allowing it to switch its immersion area promptly to dissolve the salt deposited on the device. Preferably, the device's immersion area is 1 / 5-1 / 3 of its total height.

[0032] The photothermal evaporation device includes a support body and a photothermal evaporation material. The support body acts as a skeleton, and the photothermal evaporation material is attached to the support body. On the one hand, the support body acts as a skeleton, and on the other hand, it provides buoyancy for the photothermal evaporation device, allowing the photothermal evaporation device to float in the water. Specifically, the support body is a hollow structure, including a hollow cavity. The photothermal evaporation material is placed outside the support body and adheres to the outer wall of the support body. It can be a bonding setting, a fixing setting with a fixing part, or other setting methods that can fix the photothermal evaporation material to the support body.

[0033] Specifically, the support is cylindrical, and the photothermal evaporation material is attached to the outer wall of the cylindrical support. The support wall is provided with a number of through-holes that penetrate the inner and outer walls. These through-holes serve as water guide holes for introducing water, allowing water to contact the photothermal evaporation material. The side of the photothermal evaporation material closest to the support is the inner side, and the side facing away from the support is the outer side. Water first contacts the photothermal evaporation material through the through-holes and then soaks the entire photothermal evaporation material. The photothermal evaporation material has a porous structure with a pore size of 2μm to 20μm. This micron-scale pore size provides capillary force for water transport and space for salt precipitation, while also preventing the precipitated salt from clogging the pores. The photothermal evaporation material can be a PVA sponge sheet. The thickness of the PVA sponge sheet and the diameter of the inner cylindrical support are synergistically controlled so that the water surface at least covers one of the through-holes, achieving a continuous and spontaneous water supply and making the PVA sponge soaked. The support body is made of lightweight hollow foam. The through holes on the support body serve as water guide holes to provide a water transmission path for the photothermal evaporation material. On the other hand, they serve as salt formation sites to allow salt to precipitate in the through holes and accumulate. After accumulation, the photothermal evaporation device is rotated. The through holes can be provided in one or several groups, each group containing an even number of through holes, which can be as follows. Figure 1 Set 4 in , or you can Figure 3 There are 8, preferably at least 4, through holes arranged in the cylindrical support body, which are distributed along the circumference of the cylindrical support body, and the through holes in the same group form a ring. Figure 10 The middle support body is provided with 3 groups of through holes, each group containing 4 through holes.

[0034] The photothermal evaporation material is hydrophilic, which is conducive to fully infiltrating the material. In order to increase the salt resistance of the photothermal evaporation device and prevent salt precipitation on the outer side of the photothermal evaporation material, the outer side is treated with hydrophobicity. The preparation method of the photothermal evaporation material is as follows:

[0035] A porous material is used as a matrix of a photothermal evaporation material, and the porous material is immersed in a polymer solution to obtain light absorption and heat generation properties. The polymer solution is preferably a mixed solution of a polypyrrole solution and a hydrophilic agent. The polypyrrole solution enables the porous material to obtain light absorption and heat generation properties, and the hydrophilic agent enables the porous material to obtain hydrophilic properties.

[0036] Place in oven for later use;

[0037] Prepare a hydrophobic agent, which can be one of polyolefin, silicone resin, and fluorocarbon polymer. Preferably, FAS (perfluorodecylethoxysilane), water, and ethanol are used as solvents. The pH is adjusted to between 2 and 6 with acetic acid, and the mixture is mixed uniformly to obtain a hydrophobic solution.

[0038] The hydrophobic solution is brushed or sprayed on the four sides 202 and the first surface 201 of the photothermal evaporation material, leaving only the second surface uncoated. The second surface is opposite to the first surface. The solution coating thickness is controlled to be no more than 2 mm, and then dried to obtain the photothermal evaporation material.

[0039] The photothermal evaporation material is sponge or foam rubber. The second surface not coated with the hydrophobic solution is used as the bonding surface. The photothermal evaporation material is bonded to the outer surface of the support with a thickness of 1mm-10mm. The hydrophilic agent can be a mixed solution of one or more of starch, protein, cellulose-based natural polymers, polyacrylic acid, polyacrylamide, polyvinyl alcohol, polyurethane, polyamide, etc. The mass fraction of the hydrophobic agent ranges from 2% to 15%, preferably 5% to 10%.

[0040] The thickness of the photothermal evaporation material affects the overall draft of the device, and the thickness is 1~10mm. The support body is a material with both hydrophobic and buoyant properties, which can be one of hydrophobic sponge, foam and wood. The axis of the through hole is perpendicular to the axis of the support body cylinder, and the through holes are evenly distributed in the circumferential direction. Specifically, 4 through holes can be arranged along the circumferential direction.

[0041] The salt resistance method of the water treatment device mentioned in the present invention comprises the following steps:

[0042] The light absorbing device is placed in water, has a certain draft, and floats in the water;

[0043] Water soaks the photothermal evaporation material through the through-holes. The photothermal evaporation material absorbs light and generates heat, heating the water on it, causing the water to evaporate. The precipitated salt remains at the hydrophilic and hydrophobic interface and in the through-holes of the support. It is worth mentioning that the through-holes for accumulating salt are at least placed above the water surface, generally at the top of the photothermal evaporation device.

[0044] The accumulation of salt in the photothermal evaporation material causes the center of gravity of the cylindrical photothermal evaporation device to deflect, driving the photothermal evaporation device to rotate, and the area with accumulated salt rotates downward and immerses in water;

[0045] The salt on the photothermal evaporation material is redissolved in the brine to be treated, and the photothermal evaporation material is cleaned, exposing a new evaporation surface to continue working.

[0046] The present invention will be further explained in detail below with reference to specific embodiments. Example

[0047] The water treatment device is a photothermal evaporation device, which includes a support body 1 and a photothermal absorption material 2 arranged on the support body. The support body 1 is a hollow foam, and its structure is a hollow cylinder with an inner diameter of 5 cm, a wall thickness of 0.5 cm, and a height of 10 cm. At a height of 5 cm on the cylinder, water guide holes are formed at 90-degree intervals in the circumferential direction. There are 4 holes with a hole diameter of 1 cm.

[0048] For photothermal absorber material 2, a hydrophilic sponge was used as the substrate. The sponge was 5 mm thick, 31.4 cm long, and 10 cm wide. Sponge treatment: Prepare a 5% polypyrrole solution. Take a sponge 5 mm thick, 31.4 cm long, and 10 cm wide and soak it in the polypyrrole solution. Repeat this process several times until the sponge turns completely black. Rinse the surface with water to remove any excess solution. Place in an oven to dry and set aside.

[0049] Sponge hydrophobic treatment: 1. Use perfluorodecylethoxysilane as solute, water and ethanol as solvents to prepare a 10% perfluorodecylethoxysilane solution with a mass ratio of water to ethanol of 1:4. The obtained perfluorodecylethoxysilane solution is adjusted to pH 3 with acetic acid and then mixed evenly.

[0050] 2. Use spraying method to evenly spray perfluorodecylethoxysilane solution on one side of the black sponge, let it dry, and control the coating thickness to 1-2mm.

[0051] The photothermal evaporation material and the support are assembled, and the photothermal evaporation material is attached to the outer wall of the support with the side sprayed with the perfluorodecylethoxysilane solution as the outer side to obtain a photothermal evaporation device.

[0052] Conduct effect experiments on the obtained photothermal evaporation device:

[0053] The device was placed in a 15% sodium chloride solution as a simulated salt solution, with the device's draft depth approximately 1 / 4 of its height. It was then placed outdoors in the sun for a photothermal evaporation concentration experiment. At 1 p.m., when the outdoor temperature was 35°C, the device's outer surface temperature reached 80°C, with an evaporation rate of 2kg / h / m 2 After 2 hours, the salt concentration of the solution reached 22%, and the device continued to work. The evaporation rate curve of the device is shown in the figure below. Figure 5 As shown in the figure, the evaporation rate of the photothermal evaporator is about 2.0 kg / m -2 h -1After running for 2 hours, the accumulated salt in the through-holes caused gravity imbalance and rotation. After the rotation, the evaporation rate of the device dropped to 1.8kgm-2h-1. After the rotation, the precipitated salts dissolved in the water, and the through-holes continued to introduce water into the entire device, and then the evaporation rate of the entire device slowly increased to the original level. Figure 6 , you can see salt inside the pores. Example

[0054] The water treatment device is a photothermal evaporation device, which includes a support body 1 and a photothermal absorption material 2 arranged on the support body. The support body 1 is a hollow foam, and its structure is a hollow hexagonal barrel with a side length of 3 cm, a wall thickness of 0.5 cm, and a height of 10 cm. At a height of 5 cm on the barrel, a hole is punched on each barrel wall to form a water guide hole. There are 6 holes with a hole diameter of 1 cm.

[0055] For photothermal absorber material 2, a hydrophilic sponge was used as the substrate. The sponge was 5 mm thick, 3 cm long, and 10 cm wide. Sponge treatment: Prepare a 5% polypyrrole solution by mass. Take a sponge 5 mm thick, 3 cm long, and 10 cm wide and soak it in the polypyrrole solution. Repeat this process several times until the sponge turns completely black. Rinse the surface with water to remove any excess solution. Place in an oven to dry and set aside.

[0056] Sponge hydrophobic treatment: same as Example 1

[0057] 2. Use spraying method to evenly spray perfluorodecylethoxysilane solution on one side of the black sponge, let it dry, and control the coating thickness to 1-2mm.

[0058] Assemble the photothermal evaporation material and the support body, use the side sprayed with perfluorodecylethoxysilane solution as the outer side, and stick 6 pieces of photothermal evaporation material on the outer wall of the hexagonal support body to make a photothermal evaporation device.

[0059] Conduct effect experiments on the obtained photothermal evaporation device:

[0060] The device was placed in a 15% sodium chloride solution as a simulated salt solution, with the device's draft depth being approximately 1 / 3 of the device's height. The device was then placed outdoors in the sun for a photothermal evaporation concentration experiment. At 1 p.m., when the outdoor temperature was 35°C, the device's outer surface temperature reached 80°C, and the evaporation rate was as follows: Figure 7 As shown, the initial evaporation rate is 1.93 kg / h / m 2 After 2 hours, the salt concentration of the solution reached 22%, and the evaporation rate of the device remained stable at (1.9~2.0) kg / m -2 h -1 between. Example

[0061] The water treatment device is a photothermal evaporation device, which includes a support body 1 and a photothermal absorption material 2 arranged on the support body. The support body 1 is a hollow foam, and its structure is a hollow cylinder with an inner diameter of 5 cm, a wall thickness of 0.5 cm, and a height of 10 cm. At a height of 5 cm on the cylinder, water guide holes are formed at 90-degree intervals in the circumferential direction. There are 4 holes with a hole diameter of 1 cm.

[0062] For photothermal absorber material 2, a hydrophilic cotton cloth was used as the substrate. The cotton cloth was 1.5 mm thick, 31.4 cm long, and 10 cm wide. To prepare the cotton cloth, prepare a 5% polypyrrole solution by weight. Soak a piece of cotton cloth (5 mm thick, 31.4 cm long, and 10 cm wide) in the polypyrrole solution several times until the sponge turns completely black. Rinse the surface of the sponge with water to remove any excess solution. Place the sponge in an oven to dry and set aside.

[0063] Hydrophobic treatment of cotton cloth: 1. Use silicone resin as solute and water and ethanol as solvent to prepare a 15% silicone resin solution with a mass ratio of water to ethanol of 1:4. Mix the obtained silicone resin solution evenly and set aside.

[0064] 2. Use spraying method to evenly spray perfluorodecylethoxysilane solution on one side of the black sponge, let it dry, and control the coating thickness to 1-2mm.

[0065] Assemble the photothermal evaporation material and the support body, use the side sprayed with the silicone resin solution as the outer side, and stick the photothermal evaporation material on the outer wall of the support body to make a photothermal evaporation device.

[0066] Conduct effect experiments on the obtained photothermal evaporation device:

[0067] The device was placed in a 15% sodium chloride solution as a simulated salt solution, with the device's draft depth being approximately 1 / 5 of the device's height. It was then placed outdoors in the sun for a photothermal evaporation concentration experiment. At 1 p.m., when the outdoor temperature was 35°C, the device's outer surface temperature reached 80°C, and the evaporation rate was as follows: Figure 8 As shown, the initial evaporation rate of the device is 1.98 kg / h / m 2 After 2 hours, the salt concentration of the solution reached 22%, and the evaporation rate of the device remained stable at (1.9~2.0) kg / m -2 h -1 There was no decline in between. Example

[0068] The only difference from Example 1 is that 8 holes are punched on the support body, and the 8 through holes are evenly and symmetrically distributed around the circumference. The support body structure is as follows: Figure 3 shown.

[0069] Comparative Example 1 (no hole)

[0070] Compared with Example 1, the selected materials and preparation methods are the same, but the hole with a diameter of 1 cm is not made on the hollow cylinder. Therefore, the entire device has no through-hole.

[0071] Conduct effect experiments on the obtained photothermal evaporation device:

[0072] The device was placed in a 15% sodium chloride solution as a simulated salt solution, with the device's draft depth being approximately 1 / 4 of the device's height. It was then placed outdoors in the sun for a photothermal evaporation concentration experiment; the average evaporation rate was measured to be approximately 1.4 kg / h / m 2 , but the device took about 3.5 hours to rotate. The evaporation rate curve of the device is shown in Figure 5 shown.

[0073] Comparative Example 2

[0074] The same hydrophilic sponge as in Example 1 was used as the substrate to prepare the photothermal absorber. The sponge was processed in the same manner as in Example 1 to produce a photothermal absorber with one side being superhydrophobic and the other side being superhydrophilic. The photothermal absorber was bent into a cylindrical shape and then secured with pins.

[0075] The effect experiment was conducted on the prepared photothermal evaporation device without support:

[0076] The device was placed in a 15% sodium chloride solution as a simulated salt solution and placed outdoors in the sun for a photothermal evaporation concentration experiment. At this time, the device's draft was approximately 1 / 6 of the device's height. After 4 hours of operation, obvious salt deposition occurred on the inner surface of the device, and its evaporation rate was as follows: Figure 9 As shown, the initial rate is 1.5 kg / h / m 2 , and then continued to decrease, and after 4 hours the rate was 1.15kg / h / m 2 , the salt concentration of the solution reaches 16%, and the device cannot rotate. As the salt content increases, the evaporation rate of the device gradually decreases.

Claims

1. A salt-resistant photothermal evaporation device, characterized by: The photothermal evaporation material comprises a photothermal evaporation material, wherein the photothermal evaporation material is at least partially hydrophilic, and water is transported through the hydrophilic photothermal evaporation material; The photothermal evaporation device is a three-dimensional structure, which is a regular or irregular structure. When treating a salty water body, the three-dimensional photothermal evaporation device floats in the water body, with one part placed below the water surface and the other part placed above the water surface. The photothermal evaporation device placed below the water surface contacts the water body and transfers the water body to the part above the water surface. After the water evaporates and salt is precipitated on the photothermal evaporation device, the center of gravity of the photothermal evaporation device deflects, and the photothermal evaporation device rotates; The photothermal evaporation device further includes a support body, the support body forms a skeleton of the hollow structure, and the photothermal evaporation material is arranged on the support body to form a hollow structure. The photothermal evaporation material includes an inner side facing the hollow cavity and an outer side facing away from the hollow cavity, water infiltrates the photothermal evaporation material from the inner side, and the outer side of the photothermal evaporation material is hydrophobic treated; The support body is a hollow cylinder, the photothermal evaporation material is a flexible material, and is attached to the outer wall of the hollow cylinder. The hollow cylinder is provided with a plurality of through holes that pass through the inner and outer walls of the hollow cylinder, and the water body contacts the photothermal evaporation material through the through holes.

2. The salt-resistant photothermal evaporation device according to claim 1, characterized in that: The center of gravity of the photothermal evaporation device is the geometric center of the three-dimensional structure.

3. The salt-resistant photothermal evaporation device according to claim 1 or 2, characterized in that: When the photothermal evaporation device is placed in a body of water, the geometric center of the photothermal evaporation device is placed above the liquid surface or flush with the liquid surface.

4. The salt-resistant photothermal evaporation device according to claim 1 or 2, characterized in that: The photothermal evaporation device is a hollow cylinder, which is placed horizontally in the water body, and the water depth is 1 / 5-1 / 3 of the height of the device.

5. The salt-resistant photothermal evaporation device according to claim 1, characterized in that: The photothermal evaporation material satisfies one of the following requirements: The photothermal evaporation material includes an inner side surface attached to the support and an outer side surface facing away from the support, wherein the contact angle between the inner side surface and water is 0°, and the contact angle between the outer side surface and water is greater than 150°; - The photothermal evaporation material has a solar light absorption rate greater than 90%.

6. The salt-resistant photothermal evaporation device according to claim 1, characterized in that: The support is a hydrophobic medium, and a hydrophilic-hydrophobic interface is formed between the photothermal evaporation material and the support. After the water in the photothermal evaporation material evaporates, salt accumulates in the hydrophilic-hydrophobic interface in the adjacent area and in at least one through hole thereof. After the salt accumulates, the photothermal evaporator rotates to immerse the through hole where the salt accumulates in the water.

7. The salt-resistant photothermal evaporation device according to claim 1, characterized in that: The photothermal evaporation material has a porous structure with a pore size of 2 μm to 20 μm.

8. The salt-resistant photothermal evaporation device according to claim 1, characterized in that: The hydrophobic treatment method for the outer side of the photothermal evaporation material is: spraying or brushing a hydrophobic agent on the outer side of the photothermal evaporation material, wherein the hydrophobic agent is a combination of one or more of polyolefin, silicone resin, and fluorocarbon polymer.

9. A water treatment device, characterized in that: The photothermal evaporation device comprises the photothermal evaporation device according to any one of claims 1 to 8.

10. A water treatment and salt resistance method, characterized in that: The self-rotation of a photothermal evaporation device is used to redissolve salt precipitated during water treatment into water, wherein the photothermal evaporation device is the photothermal evaporation device according to any one of claims 1 to 8. The salt resistance method comprises the following steps: The photothermal evaporation device uses solar energy as an energy source, absorbs solar energy and converts it into heat to heat and evaporate water; After the water evaporates, the salt precipitates and crystallizes on the photothermal evaporation device. The accumulation of salt causes the center of gravity of the photothermal evaporation device to shift, causing the photothermal evaporation device to rotate. The self-rotation causes the salt precipitation area of ​​the photothermal evaporation device to be immersed in water, and the salt is dissolved into the water; A portion of the photothermal evaporation device is placed below the water surface, and the other portion is placed above the water surface.

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