Solar water evaporator and preparation method and application thereof

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to a solar water evaporator and a preparation method and application thereof. According to the solar water evaporator provided by the invention, by using the carbon-based photo-thermal functional materials such as the carbon nanotubes, the micron porous hydrogel and the porous salt-inhibiting mineral powder, an efficient water transmission path and a steam escape path can be provided so as to improve the evaporation efficiency of the solar water evaporator; the porous salt inhibition mineral powder such as diatomite is doped to realize the porous physical salt inhibition mechanism and the surface charge repulsion effect of the mineral powder to effectively inhibit the salt, in addition, through the design of the conical structure with the height-diameter ratio being equal to 1.25, the automatic falling of the surface salt is effectively promoted through the gravity effect, the condition that the salt crystals are difficult to block the pore channels is reduced, and the service life is prolonged. And the evaporation rate stability of the solar water evaporator is improved, so that the technical problem of lack of a high-performance solar water evaporator in the prior art is solved.

Description

Technical Field

[0001] This application belongs to the technical field of water treatment, and particularly relates to a solar water evaporator, a preparation method thereof, and an application thereof. Background Art

[0002] Water treatment is a process of removing impurities such as suspended solids, colloids, bacteria, viruses, heavy metals, organic matters, and inorganic matters through physical, chemical, biological and other means to obtain water of the required standard; for example, seawater desalination is to remove salts and other impurities in seawater to obtain fresh water resources.

[0003] At present, the main technologies for seawater desalination are the distillation method and the membrane separation method. For example, reverse osmosis membranes are used to remove salts and other impurities in seawater. However, using reverse osmosis membranes for seawater desalination has defects such as high energy consumption and easy pollution of reverse osmosis membranes; while solar energy is a green and renewable energy source, and solar water evaporators based on solar energy are expected to become a research focus in the scientific research field. Solar water evaporators convert solar energy into heat energy through photothermal functional materials, heat and evaporate seawater, and condense water vapor into fresh water for seawater desalination; however, there are still some defects in current solar water evaporators. For example, salt crystal blockage of pores in a high-salt environment leads to a significant attenuation of efficiency, insufficient thermal localization causes heat energy loss, and a single structure cannot balance the contradiction between water transport and steam escape; therefore, how to prepare a high-performance solar water evaporator is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0004] In view of this, this application provides a solar water evaporator, a preparation method thereof, and an application thereof, which are used to solve the technical problem of the lack of high-performance solar water evaporators in the prior art.

[0005] In the first aspect of this application, a solar water evaporator is provided, which includes a micro-porous hydrogel, a carbon-based photothermal functional material, and a porous salt-inhibiting mineral powder;

[0006] The carbon-based photothermal functional material and the porous salt-inhibiting mineral powder are doped inside the micro-porous hydrogel;

[0007] The micro-porous hydrogel is provided with millimeter pores vertically penetrating therethrough.

[0008] Preferably, the hydrophilic polymer monomer of the micro-porous hydrogel is selected from at least one of polysaccharide monomers, polypeptide monomers, and synthetic hydrophilic polymer monomers.

[0009] Preferably, the polysaccharide monomers are selected from at least one of starch, cellulose, alginic acid, hyaluronic acid, and chitosan;

[0010] The polypeptide monomers are selected from at least one of collagen, poly-L-lysine, and poly-L-glutamic acid;

[0011] The synthetic hydrophilic polymer monomer is selected from at least one of polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylamide, and poly-N-substituted acrylamide.

[0012] Preferably, the carbon-based photothermal functional material is selected from at least one of carbon nanotubes, carbon black, graphene, and its derivatives.

[0013] Preferably, the porous salt-suppressing mineral powder is selected from diatomite.

[0014] Preferably, calculated by mass, it includes 100-200 parts by mass of micro-porous hydrogel, 1-3 parts by mass of carbon-based photothermal functional material, and 1-4 parts by mass of porous salt-suppressing mineral powder.

[0015] Preferably, the micro-porous hydrogel is selected from conical micro-porous hydrogels.

[0016] Preferably, the micro-porous hydrogel is provided with millimeter channels vertically penetrating through it, specifically: there are 3-9 millimeter channels vertically penetrating through and evenly distributed along the circumference in the micro-porous hydrogel.

[0017] Preferably, the bottom diameter of the conical micro-porous hydrogel is 10-50 mm, and the height is 12.5-62.5 mm;

[0018] The diameter of a single vertically penetrating millimeter channel is 2-10 mm.

[0019] Preferably, the number of vertically penetrating millimeter channels is 6, and the 6 vertically penetrating millimeter channels are evenly distributed along the circumference;

[0020] The bottom diameter of the micro-porous hydrogel is 30 mm, and the height is 37.5 mm;

[0021] The diameter of a single vertically penetrating millimeter channel is 5 mm.

[0022] The second aspect of the present application provides a preparation method of a solar water evaporator, which can prepare a solar water evaporator described in the first aspect. The preparation method includes the following steps:

[0023] Step S1: Mix water, a hydrophilic polymer monomer, a carbon-based photothermal functional material, and a porous salt-suppressing mineral powder evenly to obtain a mixed solution;

[0024] Step S2: Heat and stir the mixed solution to obtain a mixed solution with polymer chains untangled;

[0025] Step S3: Add a cross-linking agent and a catalyst, or only add a cross-linking agent to the mixed solution with polymer chains untangled and mix evenly to obtain a precursor of the solar water evaporator;

[0026] Step S4: Add the precursor of the solar water evaporator into a mold and let it stand still, then crosslink to obtain the solar water evaporator.

[0027] The mold is a cone with a hollow structure, and a cylindrical structure is arranged inside the cone with the hollow structure.

[0028] Preferably, calculated by mass, in step S1, it includes 100 parts by mass of water, 10 - 20 parts by mass of hydrophilic polymer monomer, 1 - 3 parts by mass of carbon-based photothermal functional material, and 1 - 4 parts by mass of porous salt-inhibiting mineral powder.

[0029] Preferably, the way of mixing evenly is ultrasonic treatment for 20 - 40 min.

[0030] Preferably, in step S2, during the process of heating and stirring, the heating temperature is , the rotation speed is 600 - 1000 r / min, and the time is 20 - 40 min.

[0031] Preferably, in step S3, the crosslinking agent is selected from at least one of calcium chloride, carbodiimide-N-hydroxysuccinimide, glutaraldehyde, and N,N-methylenebisacrylamide;

[0032] The catalyst is selected from at least one of hydrochloric acid, nitric acid, ammonium persulfate, and potassium persulfate.

[0033] Preferably, in step S4, the standing time is 1 - 5 h.

[0034] Preferably, the bottom diameter of the hollow structure of the cone with the hollow structure is 10 - 50 mm, and the height is 12.5 - 62.5 mm;

[0035] The diameter of the cylindrical structure is 2 - 10 mm.

[0036] Preferably, the number of the cylindrical structures is 3 - 9, and the positions are equally spaced along the circumference.

[0037] Preferably, after step S4, it further includes step S5: Demold and soak the solar water evaporator.

[0038] The third aspect of this application provides an application of the solar water evaporator described in the first aspect in the field of seawater desalination.

[0039] Compared with the prior art, the solar water evaporator provided by this application has at least the following beneficial effects:

[0040] 1. In the solar water evaporator provided by the present application, a carbon-based photothermal functional material with ultra-wideband light absorption and high photothermal conversion efficiency is used to provide more thermal energy. Vertical millimeter channels are arranged in the micro-porous hydrogel, which cooperate with the micro-sized pores of different sizes existing in the micro-porous hydrogel itself, providing an efficient water transmission path and a steam escape path, reducing the flow resistance of water and water vapor transmission, and improving the evaporation efficiency of the solar water evaporator.

[0041] 2. In the solar water evaporator provided by the present application, porous salt-inhibiting mineral powders such as diatomite are used to effectively inhibit salts through the porous physical salt-inhibiting mechanism and the surface charge repulsion effect of the mineral powder, improving the evaporation rate stability of the solar water evaporator. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0043] Figure 1 SEM images of parallel cross-sections of the solar water evaporator provided in Embodiment 2 and Embodiment 3 of the present application, where (1) and (2) are SEM images of parallel cross-sections of the solar water evaporator provided in Embodiment 2; (3) and (4) are SEM images of parallel cross-sections of the solar water evaporator provided in Embodiment 3;

[0044] Figure 2 SEM images of vertical cross-sections of the solar water evaporator provided in Embodiment 2 and Embodiment 3 of the present application, where (1) is the SEM image of the vertical cross-section of the solar water evaporator provided in Embodiment 2; (2) is the SEM image of the vertical cross-section of the solar water evaporator provided in Embodiment 3;

[0045] Figure 3 Design drawings and physical drawings of the molds used for the solar water evaporator provided in Embodiment 2 and Embodiment 3 of the present application;

[0046] Figure 4 Graphs showing the evaporation performance test results of the solar water evaporator provided in Embodiments 1-5 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The present application provides a solar water evaporator, its preparation method and application, which are used to solve the technical problem of the lack of high-performance solar water evaporators in the prior art.

[0048] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0049] In view of the current lack of high-performance solar water evaporators, the present application provides a solar water evaporator, which comprises a micro-porous hydrogel, a carbon-based photothermal functional material, and a porous salt-inhibiting mineral powder; in the solar water evaporator, the carbon-based photothermal functional material and the porous salt-inhibiting mineral powder are doped inside the micro-porous hydrogel, and the micro-porous hydrogel is provided with vertically penetrating millimeter channels.

[0050] When the solar water evaporator provided by the present application is placed on the surface of simulated seawater or seawater and irradiated by the sun, the micro-porous hydrogel in the solar water evaporator provides moisture, and the carbon-based photothermal functional material will convert solar energy into heat energy; due to the ultra-wideband light absorption and high photothermal conversion efficiency of the carbon-based photothermal functional materials such as graphene used in the present application, more heat energy will be provided. At the same time, the micro-porous hydrogel provided by the present application is provided with vertically penetrating millimeter channels, which cooperate with the micro-scale pores of different sizes existing in the micro-porous hydrogel itself. That is, the vertical perforation channels provide a water transmission path, enabling the internal water channels of the solar water evaporator to be oriented and arranged, which is conducive to continuously providing moisture. The interior of the micro-porous hydrogel presents a highly connected multi-level micro-channel structure, providing a path for rapid capillary water transportation and efficient steam escape, reducing the flow resistance of water and water vapor transmission, significantly enhancing the diffusion rate of steam after the water is heated and evaporated, and enhancing the evaporation driving force. Therefore, the solar water evaporator provided by the present application uses carbon-based photothermal functional materials such as graphene with high-efficiency photothermal conversion ability to provide heat energy, and sets millimeter, micro-scale and other multi-scale hierarchical pore structures in the solar water evaporator to optimize the water and water vapor transmission and escape channels, thereby improving the evaporation rate of the solar water evaporator; in addition, the present application also doped porous salt-inhibiting mineral powder in the micro-porous hydrogel. On the one hand, the porous structure of the porous salt-inhibiting mineral powder further optimizes the multi-scale hierarchical structure pores of the micro-porous hydrogel, improving the water and water vapor transmission and escape. On the other hand, the physical salt-inhibiting mechanism of the porous structure and the surface characteristics of the mineral powder effectively inhibit the enrichment of salt ions at the evaporation interface through the charge repulsion effect, and cooperate with the salt-inhibiting mechanism of significantly increasing the critical concentration of salt crystal nucleation, which can significantly inhibit the transport of salt ions, so that the concentration of salt ions on the evaporation interface of the solar water evaporator will remain at a low level for a long time, and salt crystals are difficult to block the pores, improving the good evaporation rate stability of the solar water evaporator provided by the present application and not being easily attenuated; thus, the present application provides a high-performance solar water evaporator.

[0051] Preferably, in the solar water evaporator provided by the present application, the hydrophilic polymer monomers crosslinked to form the micro-porous hydrogel are selected from polysaccharide monomers such as alginic acid, polypeptide monomers such as poly-L-lysine, synthetic hydrophilic polymer monomers such as polyvinyl alcohol, etc. The crosslinking agents for monomer crosslinking can be selected from components such as calcium chloride, carbodiimides, glutaraldehyde, N,N'-methylenebisacrylamide, etc. according to different monomers. Some monomers require catalysis and can be selected from catalysts such as hydrochloric acid, nitric acid, ammonium persulfate, potassium persulfate, etc. according to different monomers.

[0052] Preferably, in the solar water evaporator provided by the present application, the carbon-based photothermal functional material can be selected from carbon nanotubes, carbon black, graphene and its derivatives, etc. These carbon-based photothermal functional materials have ultra-wideband light absorption and high photothermal conversion efficiency, and can provide more thermal energy for the solar water evaporator under sunlight irradiation.

[0053] Preferably, in the solar water evaporator provided by the present application, the porous salt-inhibiting mineral powder is selected from diatomite. Diatomite is formed by the accumulation of the remains of ancient diatoms, and its main component is amorphous silica. During the growth process, diatoms form cell walls with regular shapes and porous structures. These cell walls gradually accumulate and are preserved after the death of diatoms, making diatomite have unique porous characteristics. The pore sizes of diatomite vary, ranging from micropores to mesopores, and the pore diameters are usually between a few micrometers and dozens of micrometers. At the same time, the silanol groups ( ) on the surface of silica in diatomite will dissociate, making the surface of diatomite carry negative charges, and the charges repel cations such as sodium ions ( ). Therefore, porous salt-inhibiting mineral powders such as diatomite can reduce the occurrence of salt deposition blocking the pores.

[0054] Preferably, in the solar water evaporator provided by the present application, the shape of the micro-porous hydrogel is a conical micro-porous hydrogel. The bottom diameter of the conical micro-porous hydrogel is 10 - 50 mm, and the height is 12.5 - 62.5 mm. The micro-porous hydrogel provided by the present application has a conical structure design with a height-to-diameter ratio equal to 1.25, which effectively promotes the automatic shedding of surface salts through the gravity effect, and improves the evaporation rate stability of the solar water evaporator.

[0055] Preferably, in the solar water evaporator provided by the present application, the number of vertically penetrating millimeter channels can be set to 3 - 9, such as 6. These vertically penetrating millimeter channels are equally spaced along the circumference, and the diameter of a single vertically penetrating millimeter channel can be 2 - 10 mm, such as 5 mm.

[0056] Correspondingly, the present application correspondingly provides a preparation method of the above-mentioned solar water evaporator. The preparation method includes: first, mixing water, a hydrophilic polymer monomer, a carbon-based photothermal functional material, and a porous salt-inhibiting mineral powder evenly to obtain a mixed solution, then heating and stirring to untangle the polymer chains of the hydrophilic polymer monomer in the mixed solution, and next adding a crosslinking agent or simultaneously adding a crosslinking agent and a catalyst and quickly stirring and mixing evenly, and then pouring it into a mold and standing still to obtain the solar water evaporator.

[0057] In the preparation method of the solar water evaporator, adding a crosslinking agent or simultaneously adding a crosslinking agent is carried out according to different monomers. For example, when polysaccharide monomers such as alginic acid are added, only calcium chloride is added as the crosslinking agent, while when polypeptide monomers such as poly-L-lysine are added, crosslinking agents such as carbodiimide-N-hydroxysuccinimide need to be added. When synthetic hydrophilic polymer monomers such as polyvinyl alcohol are added, crosslinking agents such as glutaraldehyde and catalysts such as hydrochloric acid need to be added, or crosslinking agents such as N,N'-methylenebisacrylamide and catalysts such as ammonium persulfate need to be added. The mold is a specific mold with a hollow conical shape inside. The mold corresponds to the shape of the micro-porous hydrogel. The bottom diameter of the hollow structure is 10 - 50 mm, the height is 12.5 - 62.5 mm, the diameter of the set cylindrical structure is 2 - 10 mm, and the number is 3 - 9, evenly distributed along the circumference.

[0058] Next, a solar water evaporator provided by the present application will be specifically described in conjunction with examples and experimental examples.

[0059] Example 1

[0060] This example provides a preparation method of a solar water evaporator, including the steps of preparing a mixed solution, untangling the polymer chains in the mixed solution, configuring a precursor, and crosslinking and curing.

[0061] The step of preparing the mixed solution includes: ultrasonicating a mixture of 30 g of deionized water, 3 g of polyvinyl alcohol PVA (MW is 31000), and 0.45 g of 99% ultra-pure multi-walled carbon nanotube powder for 0.5 h to obtain a mixed solution.

[0062] The step of untangling the polymer chains in the mixed solution includes: heating the mixed solution to and magnetically stirring at a speed of 800 r / min for 0.5 h to untangle the polymer chains of polyvinyl alcohol PVA, obtaining a mixed solution with untangled polymer chains.

[0063] The step of configuring the precursor includes: adding 300 μl of a hydrochloric acid solution with a concentration of 6 mol / L and 0.75 g of a glutaraldehyde solution with a concentration of 50% to the mixed solution and quickly stirring to obtain a precursor of the solar water evaporator.

[0064] The steps of crosslinking and curing include: quickly pouring the precursor of the solar water evaporator into a pre-prepared mold, taking out the prepared hydrogel after standing for 3 h, demolding it, and soaking it in water to complete the preparation and obtain the solar water evaporator; the mold used in the preparation process of the solar water evaporator is as Figure 3 shown, which is a hollow cone with an inner hollow diameter of 30 mm and a height of 37.5 mm. It has six hollow cylindrical holes of the same size inside, and their positions are evenly distributed along the circumference like the 2 / 4 / 6 / 8 / 10 / 12 time scales on a dial. At the same time, the mold is equipped with six cylindrical structures, and the diameter of the matching cylinders is the same as that of the hollow cylindrical holes, which is 5 mm. Before pouring the precursor of the solar water evaporator, the matching cylinders are inserted into the corresponding hollow cylindrical holes, and the height of the matching cylinders is greater than the height of the hollow conical mold, which can be 50 mm, so that vertical through-hole channels with a millimeter size are formed in the solar water evaporator after demolding.

[0065] Example 2

[0066] This example provides a preparation method of a solar water evaporator, including the steps of preparing a mixed solution, untangling the polymer chains in the mixed solution, preparing a precursor, and crosslinking and curing.

[0067] The steps of preparing a mixed solution include: ultrasonically treating a mixture of 30 g of deionized water, 3 g of polyvinyl alcohol PVA (MW is 31000), 0.45 g of 99% ultrapure multi-walled carbon nanotube powder, and 0.6 g of diatomaceous earth (MW is 60.08) for 0.5 h to obtain a mixed solution.

[0068] The steps of untangling the polymer chains in the mixed solution include: heating the mixed solution to and magnetically stirring it at a speed of 800 r / min for 0.5 h to untangle the polymer chains of polyvinyl alcohol PVA and obtain a mixed solution with untangled polymer chains.

[0069] The steps of preparing a precursor include: adding 300 μl of a hydrochloric acid solution with a concentration of 6 mol / L and 0.75 g of a glutaraldehyde solution with a concentration of 50% to the mixed solution, and quickly stirring to obtain a precursor of the solar water evaporator.

[0070] The steps of crosslinking and curing include: quickly pouring the precursor of the solar water evaporator into a pre-prepared mold, taking out the prepared hydrogel after standing for 3 h, demolding it, and soaking it in water to complete the preparation and obtain a solar water evaporator with a diatomaceous earth doping amount of about 2%; the electron micrograph of the solar water evaporator is as Figure 1-2As shown, it can be seen that the interior of the hydrogel is a porous hierarchical micro-porous structure; the monomer for forming the micro-porous hydrogel by crosslinking is polyvinyl alcohol, the carbon-based photothermal functional material is ultra-pure multi-walled carbon nanotubes, the porous salt-suppressing mineral powder is diatomaceous earth, and the mold used in the preparation process of the solar water evaporator is as Figure 3 shown, which is a hollow cone with an inner hollow diameter of 30 mm and a height of 37.5 mm. There are six hollow cylindrical holes of the same size inside, and their positions are evenly distributed along the circumference like the 2 / 4 / 6 / 8 / 10 / 12 time scales on a dial. At the same time, the mold is equipped with six cylindrical structures. The diameter of the matching cylinder is the same as that of the hollow cylindrical hole, which is 5 mm. Before pouring the precursor of the solar water evaporator, the matching cylinder is inserted into the corresponding hollow cylindrical hole, and the height of the matching cylinder is greater than the height of the hollow cone mold, which can be 50 mm, so as to form a vertically penetrating millimeter pore channel in the solar water evaporator after demolding.

[0071] Example 3

[0072] This example provides a preparation method of a solar water evaporator. The difference in the preparation method from Example 2 lies in increasing the addition amount of diatomaceous earth, and adding steps of preparing the mixed solution, untangling the polymer chains in the mixed solution, preparing the precursor, and crosslinking and curing.

[0073] The step of preparing the mixed solution includes: ultrasonicating a mixture of 30 g of deionized water, 3 g of polyvinyl alcohol PVA (MW is 31000), 0.45 g of 99% ultra-pure multi-walled carbon nanotube powder, and 1.2 g of diatomaceous earth (MW is 60.08) for 0.5 h to obtain the mixed solution.

[0074] The step of untangling the polymer chains in the mixed solution includes: heating the mixed solution to and magnetically stirring at a speed of 800 r / min for 0.5 h to untangle the polymer chains of polyvinyl alcohol PVA, obtaining a mixed solution with untangled polymer chains.

[0075] The step of preparing the precursor includes: adding 300 μl of hydrochloric acid solution with a concentration of 6 mol / L and 0.75 g of glutaraldehyde solution with a concentration of 50% to the mixed solution, and quickly stirring to obtain the precursor of the solar water evaporator.

[0076] The step of crosslinking and curing includes: quickly pouring the precursor of the solar water evaporator into a pre-prepared mold, taking out the prepared hydrogel after standing for 3 h, demolding it, and soaking it in water to complete the preparation, obtaining a solar water evaporator with a diatomaceous earth doping amount of about 4%. The monomer for crosslinking to form the micro-porous hydrogel and the carbon-based photothermal functional material in the preparation process of the solar water evaporator are the same as those in Example 2, and the mold used is as Figure 3As shown, it is also the same as Example 2, except that the doping amount of the porous salt - suppressing mineral powder diatomite is increased.

[0077] Example 4

[0078] This example provides a preparation method of a solar water evaporator. The difference in the preparation method from Example 2 lies in the different molds used, the steps of preparing the mixed solution, the step of disentangling the polymer chains in the mixed solution, the step of preparing the precursor, and the step of cross - linking and curing.

[0079] The step of preparing the mixed solution includes: ultrasonically treating a mixture of 30 g of deionized water, 3 g of polyvinyl alcohol PVA (MW is 31000), 0.45 g of 99% ultra - pure multi - walled carbon nanotube powder, and 0.6 g of diatomite (MW is 60.08) for 0.5 h to obtain a mixed solution.

[0080] The step of disentangling the polymer chains in the mixed solution includes: heating the mixed solution to and magnetically stirring at a speed of 800 r / min for 0.5 h to disentangle the polymer chains of polyvinyl alcohol PVA, obtaining a mixed solution with disentangled polymer chains.

[0081] The step of preparing the precursor includes: adding 300 μl of hydrochloric acid solution with a concentration of 6 mol / L and 0.75 g of glutaraldehyde solution with a concentration of 50% to the mixed solution, and quickly stirring to obtain the precursor of the solar water evaporator.

[0082] The step of cross - linking and curing includes: quickly pouring the precursor of the solar water evaporator into a pre - prepared mold, standing for 3 h, then taking out the prepared hydrogel, demolding it, and soaking it in water to complete the preparation, obtaining a solar water evaporator with a diatomite doping amount of approximately 2%; the monomers that form micro - porous hydrogels during the cross - linking process in the preparation of the solar water evaporator, the doping amounts of the carbon - based photothermal functional material and the porous salt - suppressing mineral powder diatomite are the same as those in Example 2. The difference lies in that the mold used is a hollow cone with an internal hollow diameter of 30 mm and a height of 37.5 mm, but there are no six hollow cylindrical holes of the same size inside, nor are there six matching cylindrical structures, so there are no vertically penetrating millimeter - sized channels in the solar water evaporator after demolding.

[0083] Example 5

[0084] This example provides a preparation method of a solar water evaporator. The difference in the preparation method from Example 2 lies in the different molds used, the steps of preparing the mixed solution, the step of disentangling the polymer chains in the mixed solution, the step of preparing the precursor, and the step of cross - linking and curing.

[0085] The steps for preparing the mixed solution include: ultrasonically treating a mixture of 30 g of deionized water, 3 g of polyvinyl alcohol PVA (MW = 31000), 0.45 g of 99% ultra-pure multi-walled carbon nanotube powder, and 0.6 g of diatomaceous earth (MW = 60.08) for 0.5 h to obtain the mixed solution.

[0086] The steps for the disentanglement of polymer chains in the mixed solution include: heating the mixed solution to and magnetically stirring at a speed of 800 r / min for 0.5 h to disentangle the polymer chains of polyvinyl alcohol PVA, obtaining a mixed solution with disentangled polymer chains.

[0087] The steps for preparing the precursor include: adding 300 μl of a hydrochloric acid solution with a concentration of 6 mol / L and 0.75 g of a glutaraldehyde solution with a concentration of 50% to the mixed solution, and rapidly stirring to obtain the precursor of the solar water evaporator.

[0088] The steps for crosslinking and curing include: quickly pouring the precursor of the solar water evaporator into a pre-prepared mold, standing for 3 h, then taking out the prepared hydrogel, demolding it, and soaking it in water to complete the preparation, obtaining a solar water evaporator with a diatomaceous earth doping amount of approximately 2%; during the preparation of the solar water evaporator, the monomers for crosslinking to form micro-porous hydrogels, the carbon-based photothermal functional materials, and the doping amount of the porous salt-suppressing mineral powder diatomaceous earth are the same as in Example 2. The difference lies in that the mold used is a hollow cone with an internal hollow diameter of 30 mm, a height of 15 mm, and a height-to-diameter ratio of 0.5. At the same time, there are no six hollow cylindrical holes of the same size inside, nor are there six matching cylindrical structures, so there are no vertically penetrating millimeter channels in the solar water evaporator after demolding.

[0089] Experimental Example 1

[0090] This Experimental Example 1 is for performing performance tests on the solar water evaporators provided in Examples 1 - 5, and the performance test is an evaporation performance experiment.

[0091] The process of the evaporation performance experiment includes: placing the solar water evaporators provided in Examples 1 - 5 on the water surface of the simulated seawater in an evaporating dish (the salt component content of the simulated seawater is 3.5%), and exposing the entire device to simulated sunlight for (1 sun) sunlight for 6-hour testing, recording the weight loss, and using an infrared thermometer to test and record the temperature on the surface of the solar water evaporator.

[0092] The results of the evaporation performance experiment are as Figure 4 shown. It can be seen from Figure 4 that the solar water evaporator provided in Example 4 has a solid structure, no vertically penetrating millimeter channels, and lacks an oriented water transport path, which is not conducive to continuously supplying water, resulting in a slower evaporation rate of the solar water evaporator, which is or so, while the evaporation rates of the solar water evaporators provided in Examples 2-3 are respectively and , and the evaporation rate is significantly higher than that of the solar water evaporator provided in Example 3. In addition, there is usually an optimal addition ratio of diatomite in the composite material. When this threshold is exceeded, its negative effects (such as enhanced light scattering, decreased CNT dispersibility, and thermal conductivity imbalance) may exceed its positive contribution to salt inhibition. The evaporation performance of the solar evaporator with 2% diatomite content in Example 2 is better than that of the solar evaporator with 4% diatomite content in Example 3. The evaporation rates of Example 1, Example 2, and Example 3 are respectively , and . Furthermore, the conical solid structure provided in Example 4 has an inclined surface, which may increase the surface area for light absorption. Especially at different solar angles, the inclined surface of the cone can capture light more effectively, and the evaporation rate is . Compared with the solid structure solar evaporator with a height-to-diameter ratio of 0.5 provided in Example 5, the evaporation rate is , which confirms that the design with a height-to-diameter ratio of 1.25 can effectively improve the evaporation performance and self-cleaning desalination performance of the solar evaporator. This structure-chemistry synergy strategy provides an innovative solution to break through the bottleneck problem of the long-term stable operation of the evaporator.

[0093] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A solar water evaporator, characterized in that, It includes a micro-porous hydrogel, a carbon-based photothermal functional material, and a porous salt-suppressing mineral powder; The carbon-based photothermal functional material and the porous salt-suppressing mineral powder are doped inside the micro-porous hydrogel; The micro-porous hydrogel is provided with vertically penetrating millimeter channels.

2. The solar water evaporator according to claim 1, characterized in that, The hydrophilic polymer monomer of the micro-porous hydrogel is selected from at least one of polysaccharide monomers, polypeptide monomers, and synthetic hydrophilic polymer monomers.

3. The solar water evaporator according to claim 1, wherein The carbon-based photothermal functional material is selected from at least one of carbon nanotubes, carbon black, graphene and its derivatives.

4. A solar water evaporator according to claim 1, wherein The porous salt-suppressing mineral powder is selected from diatomite.

5. The solar water evaporator according to claim 1, wherein Calculated by mass, it includes 100-200 parts by mass of the micro-porous hydrogel, 1.5-2 parts by mass of the carbon-based photothermal functional material, and 2-4 parts by mass of the porous salt-suppressing mineral powder.

6. The solar water evaporator according to claim 1, wherein The micro-porous hydrogel is selected from a conical micro-porous hydrogel.

7. The solar water evaporator according to claim 1, wherein, The fact that the micro-porous hydrogel is provided with vertically penetrating millimeter channels specifically means: there are 3-9 vertically penetrating millimeter channels evenly distributed along the circumference in the micro-porous hydrogel.

8. A solar water evaporator according to claim 6, wherein, The bottom diameter of the conical micro-porous hydrogel is 10-50 mm, and the height is 12.5-62.5 mm; The diameter of a single vertically penetrating millimeter channel is 2-10 mm.

9. A preparation method of a solar water evaporator for preparing the solar water evaporator according to any one of claims 1-5, characterized in that, It includes the following steps: Step S1: Mix water, a hydrophilic polymer monomer, a carbon-based photothermal functional material, and a porous salt-suppressing mineral powder evenly to obtain a mixed solution; Step S2: Heat and stir the mixed solution to obtain a mixed solution with untangled polymer chains; Step S3: Add a cross-linking agent and a catalyst, or only add a cross-linking agent to the mixed solution with untangled polymer chains and mix evenly to obtain a precursor of the solar water evaporator; Step S4: Add the precursor of the solar water evaporator to a mold and let it stand to cross-link to obtain a solar water evaporator.

10. Application of a solar water evaporator in the field of seawater desalination, characterized in that, Use of the solar water evaporator according to any one of claims 1-5 in the field of seawater desalination.

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