High-selectivity evaporator for extracting lithium from salt lake or seawater and preparation method of high-selectivity evaporator

Abstract

The invention discloses a high-selectivity evaporator for extracting lithium from a salt lake or seawater and a preparation method of the high-selectivity evaporator. The evaporator comprises a hydrophobic carrier, a photo-thermal adsorption composite layer, a water guide strip and a substrate, the hydrophobic carrier is provided with a through hole penetrating through the hydrophobic carrier; a photo-thermal adsorption composite layer is loaded on the surface of the hydrophobic carrier and in the through holes; the photo-thermal adsorption composite layer comprises a photo-thermal conversion material, hydrogel and a lithium ion adsorbent; the hydrophobic carrier is also connected with at least two water guide strips; the hydrophobic carrier and the water guide strip are fixedly connected with the substrate. Therefore, the technical problems of difficulty in adsorbent recovery, low adsorption rate and poor selectivity in a salt lake or seawater high-salinity multi-competitive ion environment in the existing adsorption-method lithium extraction technology are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new material preparation, more specifically, relates to a high-selectivity evaporator for extracting lithium from salt lake or seawater and a preparation method thereof. BACKGROUND

[0002] Lithium, often referred to as "white gold", has become indispensable in modern energy storage technologies, especially in rechargeable batteries that power everything from portable electronic devices to electric vehicles. Projections indicate that global lithium demand is expected to surge several-fold over the next few decades. This exponential growth has made sustainable lithium resource acquisition one of the most critical challenges in the era of energy transition. Salt lake brine stores most of the world's lithium resources and is a promising alternative to traditional ores. However, the presence of a large number of competing ions such as sodium and magnesium ions in brine poses a significant challenge to selective lithium extraction.

[0003] China is rich in salt lake lithium resources, accounting for more than 83% of the total lithium resources in the country. However, they are generally characterized by high magnesium-lithium ratios and contain a large amount of competing ions such as magnesium and sodium ions, which pose a significant challenge to selective lithium extraction. At the same time, the total amount of lithium resources in seawater is extremely abundant (about 230 billion tons), but its concentration is extremely low (about 0.1-0.2 ppm), and the magnesium-lithium ratio is as high as millions, belonging to a typical "low-grade, high-impurity" resource, which is extremely difficult to extract. Currently, the technologies for extracting lithium from salt lake brine mainly include chemical precipitation, ion exchange, evaporation concentration, membrane separation, and adsorption methods. Among them, the adsorption method is considered the most promising technology route for extracting lithium from high magnesium-lithium ratio brine and seawater due to its advantages of simple operation, environmental friendliness, and high selectivity. The core of the adsorption method is the selection of adsorbent materials. However, existing adsorption materials have some technical bottlenecks: nano-sized powder materials are difficult to recycle and cannot be used in fixed bed operations; the hydrophobic and dense structure of the material leads to low utilization of adsorption sites and makes it difficult for internal active sites to function; conventional granulation or bulk processing limits the adsorption rate and capacity, often requiring external energy input such as mechanical stirring to achieve lithium ion enrichment and adsorption. In addition, maintaining stable operation and selectivity remains a major challenge in practical applications, especially for direct lithium extraction from real salt lake brine and seawater and production of battery-grade lithium carbonate.

[0004] In view of these technical difficulties, especially in view of the characteristics of high magnesium-lithium ratio salt lake brine in China, it has become a key technical problem to be solved in the field to develop a new lithium adsorbent material that can be applied to low-grade, high magnesium-lithium ratio brine and has high adsorption capacity, fast kinetics, high selectivity, and stable cycling performance. The present application provides an effective solution to the above technical problems through innovative material design and process optimization. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a high-selectivity evaporator for extracting lithium from salt lake brine or seawater and a preparation method thereof, thereby solving the technical problems of difficult recovery of adsorbents, slow adsorption rate, and poor selectivity in the high-salinity and multi-competitive ion environment of salt lake water in the prior art lithium extraction technology by adsorption method.

[0006] To achieve the above-mentioned object, according to one aspect of the present application, a lithium ion selective adsorption evaporator is provided, comprising a hydrophobic carrier, a water guide strip, and a base; the hydrophobic carrier has through holes penetrating through the hydrophobic carrier; the surface of the hydrophobic carrier and the through holes are loaded with a photo-thermal adsorption composite layer; the photo-thermal adsorption composite layer comprises a photo-thermal conversion material, a hydrogel, and a lithium ion adsorbent; at least two water guide strips are connected to the hydrophobic carrier; the hydrophobic carrier and the water guide strip are fixedly connected to the base.

[0007] Preferably, the diameter of the through holes on the hydrophobic carrier is 1-10 mm; the water guide strip is a hydrophilic fiber; the material of the hydrophilic fiber is selected from non-woven fabric, cotton fiber, hemp fiber, viscose fiber, absorbent cotton, polyamide fiber, or hydrophilic treated polyester fiber.

[0008] Preferably, the photo-thermal conversion material is selected from one or more of carbon black, graphene, carbon nanotube, polypyrrole, polydopamine, manganese oxide, molybdenum oxide, transition metal carbide, and transition metal nitride.

[0009] Preferably, the lithium ion adsorbent is selected from lithium ion sieve, magnesium-aluminum layered double hydroxide, amorphous aluminum hydroxide, or inorganic oxide modified by surface silanization; Preferably, the lithium ion sieve is titanium-based lithium ion sieve or manganese-based lithium ion sieve; Preferably, the inorganic oxide modified by surface silanization is silica, alumina, or silicate material with amino, sulfonic acid, or phosphate functional groups bonded to the surface.

[0010] Preferably, the material of the hydrophobic carrier is selected from polystyrene, polyvinyl chloride, polyurethane, or polypropylene; Preferably, the base is foamed plastic; the material of the foamed plastic is selected from polyurethane foam, polystyrene foam, polyethylene foam, polypropylene foam, polyvinyl chloride foam, or melamine formaldehyde foam.

[0011] Preferably, the hydrogel is formed by cross-linking reaction of cross-linkable hydrophilic polymer and cross-linking agent; the cross-linkable hydrophilic polymer is selected from polyvinyl alcohol, sodium alginate, polyacrylamide, polyacrylic acid, or gelatin; the cross-linking agent is selected from glutaraldehyde, boric acid, epichlorohydrin, or soluble calcium salt.

[0012] According to another aspect of the present invention, a method for preparing the lithium-ion selective adsorption evaporator is provided, comprising the following steps: (1) Photothermal conversion material and lithium-ion adsorbent are added to a crosslinkable hydrophilic polymer solution and mixed to obtain a prepolymer solution; (2) The prepolymer liquid and crosslinking agent are coated on the hydrophobic carrier respectively; the hydrophobic carrier has through holes penetrating the hydrophobic carrier; the crosslinkable hydrophilic polymer in the prepolymer liquid reacts with the crosslinking agent to form a hydrogel and adheres to the surface and through holes of the hydrophobic carrier, thereby obtaining a photothermal adsorption composite layer modified hydrophobic carrier; (3) Connect at least two water-guiding strips to the hydrophobic carrier modified by the photothermal adsorption composite layer, and fix the hydrophobic carrier modified by the photothermal adsorption composite layer and the water-guiding strips to the substrate to obtain the lithium-ion selective adsorption evaporator. Preferably, in the crosslinkable hydrophilic polymer solution, the mass ratio of the crosslinkable hydrophilic polymer to the solvent is (5-25):100; Preferably, the mass ratio of the photothermal conversion material to the crosslinkable hydrophilic polymer solution is (1-10):100; Preferably, the mass ratio of the crosslinking agent to the crosslinkable hydrophilic polymer solution is (1-5):100; Preferably, the mass ratio of the lithium-ion adsorbent to the crosslinkable hydrophilic polymer solution is (5-25):100; Preferably, the crosslinking reaction takes 0.5 to 24 hours.

[0013] According to another aspect of the present invention, an application of the lithium-ion selective adsorption evaporator is provided, wherein the lithium-ion selective adsorption evaporator is applied to lithium extraction from salt lake brine or seawater. The lithium-ion selective adsorption evaporator is placed on the surface of brine or seawater in a salt lake, so that the lithium-ion selective adsorption evaporator is suspended on the surface of brine or seawater. The base of the evaporator is in contact with the brine or seawater. At least one of the water guide strips is placed on the base without contacting the brine or seawater, and at least one of the water guide strips is in contact with the brine or seawater, so as to complete the lithium extraction from the brine or seawater.

[0014] Preferably, the pH of the salt lake brine or seawater is 8.0 to 13.0.

[0015] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: (1) This invention employs a photothermal adsorption composite layer composed of a photothermal conversion material, a hydrogel, and a lithium-ion adsorbent, which work synergistically to achieve efficient and highly selective photothermal lithium extraction. The photothermal conversion material efficiently absorbs and converts solar energy into thermal energy, generating localized high temperatures that accelerate lithium-ion migration and water evaporation; the hydrogel, as a hydrophilic network, stabilizes the loaded material and continuously transports water; the lithium-ion adsorbent selectively captures lithium ions, achieving high-rate and high-capacity adsorption in the optimized mass transfer structure. This composite layer significantly improves lithium extraction efficiency and selectivity through an integrated mechanism of "photothermal drive - multi-channel water supply - selective adsorption," overcoming the technical bottlenecks of low efficiency and low adsorption selectivity in traditional methods.

[0016] (2) The hydrophobic carrier described in this invention has a through vertical hole. The structure is designed based on the following functional synergy mechanism: the hydrophobic carrier itself has anti-wetting properties, which can precisely limit the evaporation process to the photothermal adsorption composite layer loaded on its surface and in the vertical hole, avoiding the disordered crystallization of salt and structural failure caused by the brine penetrating into the hydrophobic carrier; the photothermal adsorption composite layer coated on the inner wall of the vertical hole constitutes an important auxiliary water guiding channel, which together with the hydrophilic water guiding strip set later forms a multi-channel water supply system.

[0017] (3) The water-guiding strip and vertical through hole set in this invention form a multi-channel water supply-directional salt crystallization system: the hydrophilic water-guiding strip, as the external main channel, is responsible for supplying water and discharging competing ions (such as Mg) 2+ Na + The lithium ions are directed to a pre-defined region at their end for crystallization; vertical through-holes serve as built-in reinforced channels to promote evaporation and accelerate lithium-ion mass transfer. This design completely separates the lithium adsorption region (photothermal adsorption composite layer) from the impurity crystallization region (end of the water guide strip) in space, thereby achieving both anti-clogging stability and extremely high ion selectivity.

[0018] (4) Through ingenious evaporator structure design and surface functionalization modification, this invention successfully achieves directional crystallization control of salt, effectively preventing clogging of the photothermal surface and water delivery channels. Even in extremely high-salt environments, the system can maintain long-term stable operation and retain excellent adsorption performance and equipment integrity after multiple cycles, demonstrating outstanding durability and operational reliability. Attached Figure Description

[0019] Figure 1 The image shows a side-section SEM image of the evaporator prepared in Example 1.

[0020] Figure 2 The image shows a SEM image of the photothermal adsorption composite layer prepared in Example 1.

[0021] Figure 3 This is a physical image of the evaporator prepared in Example 2.

[0022] Figure 4 This is a schematic diagram of the hydrophobic carrier with through holes in Example 1.

[0023] Figure 5 The lithium extraction performance of the evaporator prepared in Example 3 in salt lakes in different regions.

[0024] Figure 6 The evaporation rate of the evaporator prepared in Example 4 under different light angles.

[0025] Figure 7 The XRD pattern and physical image of lithium carbonate obtained by seawater extraction from the evaporator prepared in Example 5.

[0026] Figure 8 Photographs showing the adsorption performance of the evaporator prepared in Example 6 on lithium and other competing ions when treating salt lake water, and its surface state after continuous operation in salt lake water.

[0027] Figure 9 Photographs showing the adsorption performance of the evaporator prepared for Comparative Example 1 on lithium and other competing ions when treating salt lake water, and its surface state after continuous operation in salt lake water.

[0028] Figure 10 Photographs showing the adsorption performance of the evaporator prepared for Comparative Example 2 on lithium and other competing ions in salt lake water, and its surface state after continuous operation in salt lake water. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Example 1 This embodiment provides a method for preparing a lithium-ion selective adsorption evaporator, including the following steps: (1) Preparation of prepolymer solution A uniformly dispersed prepolymer solution was prepared by mixing 20 g of 15 wt% polyvinyl alcohol-formic acid (PVA-HCOOH) solution with 0.5 g of carbon black (CB) and 2 g of titanic acid (H2TiO3) and then ultrasonically treating the mixture.

[0031] (2) Substrate spraying and crosslinking The prepolymer liquid obtained in step (1) is loaded into a spray gun and sprayed in a controlled manner under compressed air. A polystyrene (PS) sphere with a diameter of 25 mm and a pre-formed vertical through-hole of 5 mm in the center is selected as the substrate (e.g., Figure 4 As shown in the image, the PS spheres are rotated at a constant speed during the spraying process to ensure uniform coating of the solution. After coating, a 2% glutaraldehyde solution is immediately sprayed for cross-linking and curing.

[0032] (3) Evaporator construction and assembly The PVA composite solution described in step (1) was coated into the through-holes of the PS sphere, and then crosslinked again with 2% glutaraldehyde solution for 12 hours to complete the construction of the evaporator. Subsequently, four water-conducting paper strips were arranged vertically around the sphere, and stable suspension was achieved through foam support.

[0033] Figure 1 The prepared spherical evaporator side profile SEM image, such as Figure 1 As shown, a 480 μm photothermal adsorption layer was successfully sprayed onto the surface of the foam ball. Figure 2 For the SEM image of this layer, such as Figure 2 As shown, the carbon black and lithium-ion sieve nanoparticles attached to the inner wall of the hydrogel network structure prove the successful synthesis of the photothermal adsorption layer.

[0034] Example 2 This embodiment provides a method for preparing a lithium-ion selective adsorption evaporator, including the following steps: (1) Preparation of prepolymer solution A uniformly dispersed prepolymer solution was prepared by mixing 30 g of 10 wt% gelatin-dimethyl sulfoxide solution with 0.5 g of carbon nanotubes and 3 g of HAlMnO and then ultrasonically treating the mixture.

[0035] (2) Substrate spraying and crosslinking The prepolymer obtained in step (1) is loaded into a spray gun and sprayed in a controlled manner under compressed air. A polyvinyl chloride (PVC) sphere with a diameter of 25 mm and a 5 mm diameter vertical through hole in the middle is selected as the substrate. During the spraying process, the PVC sphere is kept rotating at a constant speed to ensure uniform coating of the solution. After coating, a 2% glutaraldehyde solution is immediately sprayed for cross-linking and curing.

[0036] (3) Evaporator construction and assembly The gelatin composite solution described in step (1) was coated into the through-holes of the PVC sphere, and then crosslinked again with a 2% glutaraldehyde solution for 12 hours to complete the construction of the evaporator. Subsequently, four water-guiding papers were arranged vertically around the sphere, and stable suspension was achieved through foam support. Figure 3 An actual image of the evaporator prepared for this example.

[0037] Example 3 This embodiment provides a method for preparing a lithium-ion selective adsorption evaporator, including the following steps: (1) Preparation of prepolymer solution 40 g of 10 wt% polyacrylamide-dimethyl sulfoxide solution was mixed with 0.5 g of polypyrrole and 4 g of H4Ti5O 12 The mixture is then ultrasonically treated to prepare a uniformly dispersed prepolymer.

[0038] (2) Substrate spraying and crosslinking The prepolymer obtained in step (1) was loaded into a spray gun and sprayed under controlled conditions driven by compressed air. Ethylene-vinyl acetate copolymer foam (EVA) spheres with a diameter of 25 mm and a pre-formed vertical through-hole of 5 mm in the center were selected as the substrate. During spraying, the PS spheres were kept rotating at a constant speed to ensure uniform coating of the solution. After coating, a 2% glutaraldehyde solution was immediately sprayed for crosslinking and curing.

[0039] (3) Evaporator construction and assembly The polyacrylamide composite solution described in step (1) is coated into the through-holes of the EVA spheres, and then crosslinked again with 2% glutaraldehyde solution for 12 hours to complete the construction of the evaporator. Subsequently, four water-guiding papers are arranged vertically around the spheres, and one water-guiding paper is placed at the bottom of the spheres. The four vertical water-guiding papers and the spheres are supported by foam to achieve stable suspension.

[0040] The lithium-ion selective adsorption evaporator prepared in this embodiment is suspended on the surface of brine or seawater in a salt lake. The water guide strips on the base of the evaporator are in contact with the brine or seawater, while the four vertical water guide strips in contact with the sphere are not in contact with the brine or seawater, so as to complete the lithium extraction from the brine or seawater.

[0041] This example explores the adaptability of the evaporator to salt lake water in different regions. Lithium adsorption test method: A certain amount of simulated salt lake solution was taken, and the pH of the lithium solution was adjusted to 9.5 with NaOH. The solution before and after adsorption was filtered through a micron-sized aqueous phase filter before and after 6 hours of light exposure. The concentrations of lithium, potassium, calcium, sodium, and magnesium in the filtered solution were measured, and the adsorption amount was calculated using formula (1). Then, lithium ions in the evaporator were desorbed using hydrochloric acid solution. The ion concentrations in the solution and eluent were analyzed by ICP-OES. The selectivity of the adsorbent was calculated according to formulas (2) and (3).

[0042] Figure 5 To assess the lithium adsorption and selectivity of the prepared evaporator in different salt lakes, from... Figure 5 The highest lithium-magnesium selectivity can be seen in the middle ( S Li / Mg = 629.5) appeared at the lowest lithium-ion concentration (0.162 g L). -1(in the salt water of Da Qaidam Salt Lake).

[0043] Example 4 This embodiment provides a method for preparing a lithium-ion selective adsorption evaporator, including the following steps: (1) Preparation of prepolymer solution A uniformly dispersed prepolymer solution was prepared by mixing 30 g of 10 wt% polyacrylic acid-formic acid solution with 0.5 g of graphene and 3 g of magnesium aluminum layered double hydroxide (MgAl-LDH) and then ultrasonically treating the mixture.

[0044] (2) Substrate spraying and crosslinking The prepolymer obtained in step (1) is loaded into a spray gun and sprayed under controlled conditions driven by compressed air. Polypropylene foam (PP) spheres with a diameter of 25 mm and a 5 mm diameter vertical through hole in the middle are selected as the substrate. During the spraying process, the PP spheres are kept rotating at a constant speed to ensure uniform coating of the solution. After coating, 2% glutaraldehyde solution is sprayed immediately for cross-linking and curing.

[0045] (3) Evaporator construction and assembly The polyacrylic acid composite solution described in step (1) was coated into the through-holes of the PS sphere, and then crosslinked again with 2% glutaraldehyde solution for 12 hours to complete the construction of the evaporator. Subsequently, four water-guiding paper strips were arranged vertically around the sphere, and stable suspension was achieved through foam support.

[0046] like Figure 6 As shown, the evaporation rate of the prepared evaporator is shown under different illumination angles. The evaporator exhibits a robust photothermal response that is insensitive to the sun's position, which demonstrates its potential for all-weather operation.

[0047] Example 5 This embodiment provides a method for preparing a lithium-ion selective adsorption evaporator, including the following steps: (1) Preparation of prepolymer solution A uniformly dispersed prepolymer solution was prepared by mixing 20 g of 10 wt% polyvinyl alcohol-formic acid (PVA-HCOOH) solution with 0.5 g of transition metal carbide (Mxene) and 2 g of HMn2O4 and then ultrasonically treating the mixture.

[0048] (2) Substrate spraying and crosslinking The prepolymer obtained in step (1) is loaded into a spray gun and sprayed in a controlled manner under compressed air. Polystyrene (PS) spheres with a diameter of 25 mm and a 5 mm diameter vertical through hole in the middle are selected as the substrate. During the spraying process, the PS spheres are kept rotating at a constant speed to ensure uniform coating of the solution. After coating, 2% glutaraldehyde solution is sprayed immediately for crosslinking and curing.

[0049] (3) Evaporator construction and assembly The PVA composite solution described in step (1) was coated into the through-holes of the PS spheres, and then crosslinked again with 2% glutaraldehyde solution for 6 hours to complete the construction of the evaporator. Subsequently, four water-conducting paper strips were arranged vertically around the spheres, and stable suspension was achieved through foam support.

[0050] Figure 7 This invention demonstrates the final product of lithium extraction from seawater. High-purity lithium carbonate was successfully obtained through a simple sodium carbonate precipitation treatment of the lithium-rich desorption solution. Testing showed a purity of 99.7%, meeting battery-grade material standards.

[0051] Example 6 This embodiment provides a method for preparing a lithium-ion selective adsorption evaporator, including the following steps: (1) Preparation of prepolymer solution A uniformly dispersed prepolymer solution was prepared by mixing 40 g of 10 wt% gelatin-formic acid solution with 0.5 g of polypyrrole and 4 g of LiMnO2 and then ultrasonically treating the mixture.

[0052] (2) Substrate spraying and crosslinking The prepolymer obtained in step (1) is loaded into a spray gun and sprayed in a controlled manner under compressed air. Polystyrene (PS) spheres with a diameter of 25 mm and a 5 mm diameter vertical through hole in the middle are selected as the substrate. During the spraying process, the PS spheres are kept rotating at a constant speed to ensure uniform coating of the solution. After coating, 2% glutaraldehyde solution is sprayed immediately for crosslinking and curing.

[0053] (3) Evaporator construction and assembly The gelatin composite solution described in step (1) was coated into the through-holes of the PS sphere, and then crosslinked again with 2% glutaraldehyde solution for 10 hours to complete the construction of the evaporator. Subsequently, four water-guiding papers were arranged vertically around the sphere, and stable suspension was achieved through foam support.

[0054] Figure 8 The evaporator prepared for this embodiment exhibits selectivity for different ions in a saline lake water environment. The figure shows that this evaporator is selective for Li... + It has significantly higher than Na + Mg 2+ The adsorption capacity of competing ions demonstrates excellent selectivity. Salt crystals are effectively guided to the end region of the water guide strip, and the surface of the evaporator body remains clean, confirming the salt resistance of the "spatial crystallization-guided" design. This result verifies that the multi-channel synergistic structure can achieve highly selective adsorption of lithium and spatial separation of impurity crystals.

[0055] Comparative Example 1 Unlike Example 6, water-wicking paper is not used in step (3), but the other steps are the same as in Example 6.

[0056] Figure 9 The image shows the adsorption performance of the evaporator prepared in Comparative Example 1 on lithium and other competing ions when treating salt lake water, as well as its surface state after continuous operation in salt lake water. It can be seen that the evaporator sample constructed without water-conducting paper has no salt resistance, and the lithium adsorption performance and selectivity are reduced.

[0057] This comparative example investigated the impact of introducing multiple water supply channels in the structure on salt resistance and lithium extraction performance. Example 6 used the same light irradiation method as Comparative Example 1. In Example 6, salt scale began to form at the edge of the water-conducting paper and continuously accumulated there, thus ensuring a stable water evaporation rate. Conversely, Figure 9 In Comparative Example 1, the evaporator without water-conducting paper was completely covered by salt crystals, which led to a significant decrease in the water evaporation rate, hindering light absorption and ion transport, resulting in a decrease in interface temperature and adsorption performance, and a significant reduction in lithium adsorption performance.

[0058] Comparative Example 2 Unlike Example 6, Comparative Example 2 did not use water-wicking paper or foam suspension; it relied solely on its own suspension. Figure 10 The image shows the adsorption performance of the evaporator prepared in Comparative Example 2 on lithium and other competing ions in salt lake water, as well as its surface state after continuous operation in salt lake water. Figure 10 It can be seen that although the evaporator constructed in Comparative Example 2 has salt resistance, its lithium adsorption performance is reduced and its selectivity is decreased.

[0059] Comparative Example 2 investigated the effect of introducing a water supply channel in the structure on salt resistance and lithium extraction performance. Example 6 used the same illumination method as Comparative Example 2. The channel water supply design ensured rapid water supply, effectively promoting the transport of lithium ions to the adsorption layer, thereby significantly improving the adsorption kinetic rate. During evaporation, the total salinity of the evaporator in Example 6 remained stable because lithium ions were selectively adsorbed, while other ions gradually precipitated and crystallized. However, in Comparative Example 2, as... Figure 10 As shown, the salt crystals redissolve due to the device being turned over, causing the total salinity to rise continuously, increasing the competitive ion concentration, and resulting in a decrease in lithium ion separation efficiency.

[0060] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lithium-ion selective adsorption evaporator, characterized in that, The device includes a hydrophobic carrier, water-conducting strips, and a substrate; the hydrophobic carrier has through-holes; a photothermal adsorption composite layer is loaded on the surface of the hydrophobic carrier and inside the through-holes; the photothermal adsorption composite layer includes a photothermal conversion material, a hydrogel, and a lithium-ion adsorbent; at least two water-conducting strips are also connected to the hydrophobic carrier; both the hydrophobic carrier and the water-conducting strips are fixedly connected to the substrate.

2. The lithium-ion selective adsorption evaporator according to claim 1, characterized in that, The diameter of the through holes on the hydrophobic carrier is 1~10 mm; the water-guiding strip is a hydrophilic fiber; the material of the hydrophilic fiber is selected from non-woven fabric, cotton fiber, hemp fiber, viscose fiber, degreased cotton, polyamide fiber or polyester fiber that has been hydrophilically treated.

3. The lithium-ion selective adsorption evaporator according to claim 1, characterized in that, The photothermal conversion material is selected from one or more of carbon black, graphene, carbon nanotubes, polypyrrole, polydopamine, manganese oxide, molybdenum oxide, transition metal carbides, and transition metal nitrides.

4. A lithium-ion selective adsorption evaporator according to claim 1, characterized in that, The lithium-ion adsorbent is selected from lithium-ion sieves, magnesium-aluminum layered double hydroxides, amorphous aluminum hydroxide, or inorganic oxides modified by surface silanization. Preferably, the lithium-ion screen is a titanium-based lithium-ion screen or a manganese-based lithium-ion screen. Preferably, the surface-silanized inorganic oxide is a silicon dioxide, alumina, or silicate material with amino, sulfonic acid, or phosphate functional groups bonded to its surface.

5. A lithium-ion selective adsorption evaporator according to claim 1, characterized in that, The hydrophobic carrier is made of polystyrene, polyvinyl chloride, polyurethane, or polypropylene. The substrate is a foam plastic; the material of the foam plastic is selected from polyurethane foam, polystyrene foam, polyethylene foam, polypropylene foam, polyvinyl chloride foam or melamine-formaldehyde foam.

6. A lithium-ion selective adsorption evaporator according to claim 1, characterized in that, The hydrogel is formed by the crosslinking reaction of a crosslinkable hydrophilic polymer and a crosslinking agent; the crosslinkable hydrophilic polymer is selected from polyvinyl alcohol, sodium alginate, polyacrylamide, polyacrylic acid, or gelatin; the crosslinking agent is selected from glutaraldehyde, boric acid, epichlorohydrin, or soluble calcium salt.

7. A method for preparing a lithium-ion selective adsorption evaporator as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Photothermal conversion material and lithium-ion adsorbent are added to a crosslinkable hydrophilic polymer solution and mixed to obtain a prepolymer solution; (2) The prepolymer liquid and crosslinking agent are coated on the hydrophobic carrier respectively; the hydrophobic carrier has through holes penetrating the hydrophobic carrier; the crosslinkable hydrophilic polymer in the prepolymer liquid reacts with the crosslinking agent to form a hydrogel and adheres to the surface and through holes of the hydrophobic carrier, thereby obtaining a photothermal adsorption composite layer modified hydrophobic carrier; (3) Connect at least two water-guiding strips to the hydrophobic carrier modified by the photothermal adsorption composite layer, and fix the hydrophobic carrier modified by the photothermal adsorption composite layer and the water-guiding strips to the substrate to obtain the lithium-ion selective adsorption evaporator.

8. The method for preparing a lithium-ion selective adsorption evaporator as described in claim 7, characterized in that, In the crosslinkable hydrophilic polymer solution, the mass ratio of the crosslinkable hydrophilic polymer to the solvent is (5-25):100; The mass ratio of the photothermal conversion material to the crosslinkable hydrophilic polymer solution is (1-10):100; The mass ratio of the crosslinking agent to the crosslinkable hydrophilic polymer solution is (1-5):100; The mass ratio of the lithium-ion adsorbent to the crosslinkable hydrophilic polymer solution is (5-25):100; The cross-linking reaction takes 0.5 to 24 hours.

9. The application of the lithium-ion selective adsorption evaporator as described in any one of claims 1 to 6, characterized in that, The lithium-ion selective adsorption evaporator is applied to lithium extraction from salt lake brine or seawater. The specific application involves placing the lithium-ion selective adsorption evaporator on the surface of brine or seawater in a salt lake, suspending the evaporator on the surface of the brine or seawater, with the base of the evaporator in contact with the brine or seawater, placing at least one water guide strip on the base without contacting the brine or seawater, and at least one water guide strip in contact with the brine or seawater, to complete lithium extraction from the brine or seawater.

10. The application of the lithium-ion selective adsorption evaporator as described in claim 9, characterized in that, The pH of the salt lake brine or seawater is 8.0 to 13.0.

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