A method for preparing a wood-based solar interfacial evaporator and its application

Abstract

This invention discloses a method for preparing a wood-based solar interface evaporator and its application, belonging to the field of solar evaporation seawater desalination technology. Using natural wood as raw material, a superhydrophilic wood aerogel (WA) is prepared through delignification and freeze-drying. MOF material is grafted onto the porous channel surface of WA using in-situ grafting technology to obtain MOF@WA. Porous lignin carbon (PLC) is prepared from lignin through high-temperature carbonization and activation. PLC is dispersed in a chitosan / acetic acid aqueous solution, coated onto the surface of MOF@WA, and dried to obtain a PLC@MOF@WA wood-based evaporator. This evaporator exhibits high photothermal conversion efficiency and evaporation rate, and can be used for solar-driven water evaporation at a solar irradiance of 1 kW / m². 2 Its evaporation rate reaches 2.5594 kg·m³. ‑2 ·h ‑1 It can effectively purify seawater at a low cost.

Description

Technical Field

[0001] This invention relates to the field of solar evaporation seawater desalination technology, and in particular to a method for preparing a wood-based solar interface evaporator and its application. Background Technology

[0002] Solar-driven interfacial evaporation (SDIE) is a process that utilizes photothermal materials to absorb sunlight and convert solar energy into heat energy through a photothermal conversion mechanism. This heat energy then heats seawater or wastewater, causing it to evaporate and produce water vapor. The water vapor is finally collected through a condensation device to obtain clean fresh water, thus achieving seawater desalination or wastewater treatment. Currently, plasma nanomaterials, graphene oxide, carbon nanotubes, carbon black nanoparticles, metal oxides, polymers, and MXene materials have been developed as photothermal conversion materials / solar evaporators. However, these photothermal conversion materials / evaporators suffer from drawbacks such as complex fabrication processes and high costs.

[0003] Wood is an abundant biomass product derived from solar energy, possessing advantages such as low cost, renewability, biodegradability, and good biocompatibility. It is primarily composed of cellulose, hemicellulose, and lignin. Due to its abundant porous structure, oxygen-containing functional groups, excellent hydrophilicity, and low density, wood exhibits excellent water transport capacity and thermal insulation properties. Lignin is the second largest renewable aromatic polymer on Earth after cellulose and is also a byproduct of the pulp and paper industry. As an abundant natural aromatic polymer, lignin possesses advantages such as high carbon content, low cost, renewability, and good biocompatibility. It can be easily converted into graphite carbon materials with a good porous structure through mild catalytic pyrolysis, making it a green, efficient, and low-cost potential photothermal conversion material. Therefore, to address the problems of high cost, complex evaporator manufacturing processes, and low photothermal conversion rates in current solar photothermal interface evaporation water purification technologies, it is currently necessary to provide a green, low-cost, biodegradable wood-based photothermal evaporator that uses inexpensive and readily available porous lignin carbon as the photothermal conversion material and wood as the insulating water supply substrate. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a wood-based solar interface evaporator and its application. The evaporator is composed of a metal-organic framework material, lignin porous carbon, and wood aerogel. The lignin porous carbon serves as a photothermal conversion material, the lignin-free wood aerogel serves as a water-conducting and heat-insulating substrate, and the metal-organic framework material is used to reduce the enthalpy of water evaporation, so as to achieve efficient utilization of solar energy and rapid evaporation of water.

[0005] This invention provides a method for preparing a wood-based solar interfacial evaporator, comprising the following steps:

[0006] (1) Using natural wood as raw material, superhydrophilic wood aerogels were prepared by delignification and freeze-drying, and labeled as WA;

[0007] (2) The wood aerogel was immersed in a mixed solution of copper nitrate and trimesic acid. The MOF material was grafted onto the porous channel surface of the wood aerogel by in-situ grafting technology to obtain the MOF / wood aerogel composite water supply and heat insulation substrate, which was marked as MOF@WA.

[0008] (3) Using lignin as raw material, lignin powder is carbonized at high temperature under N2 atmosphere, washed with dilute hydrochloric acid solution and deionized water, dried, ground and sieved to obtain lignin carbon, which is labeled as LC; LC is uniformly mixed with activator, and the LC / activator mixture is carbonized at high temperature in a tube furnace. After grinding, washing and drying, porous LC photothermal conversion material is obtained, which is labeled as PLC;

[0009] (4) PLC powder was dispersed in chitosan / acetic acid aqueous solution under water bath ultrasonic conditions to prepare lignin porous carbon suspension; it was coated on the upper surface of MOF@WA and dried at room temperature to obtain lignin porous carbon / MOF / wood evaporator, which was labeled as PLC@MOF@WA.

[0010] Preferably, in the above-mentioned method for preparing a wood-based solar interface evaporator, in step (1), natural wood is cut into blocks of a certain size using a laser cutting machine, and the blocks are soaked and cleaned with anhydrous ethanol. Natural wood includes balsa wood, eucalyptus, linden, willow, birch, beech, pine, etc.

[0011] Preferably, in the above-mentioned method for preparing a wood-based solar interface evaporator, in step (2), the molar ratio of copper nitrate and trimesic acid is 1:15-1:1.

[0012] Preferably, in the above-mentioned method for preparing a wood-based solar interface evaporator, in step (3), the high-temperature carbonization temperature of lignin is 400℃~900℃ and the time is 1h~2h; the activator includes KOH, K2CO3, ZnCl2, NaOH, H3PO4, etc., and the lignin includes alkaline lignin, dealkalized lignin, enzymatically hydrolyzed lignin, lignin sulfonate, etc.

[0013] Preferably, in the above-mentioned method for preparing a wood-based solar interface evaporator, in step (4), the ultrasonic frequency is 100W and the time is 10min to 30min.

[0014] Preferably, in the above-mentioned method for preparing a wood-based solar interface evaporator, the specific process for preparing superhydrophilic wood aerogel in step (1) is as follows: balsa wood blocks are soaked in a 2wt% acidic sodium chlorite solution (pH≈4.6), refluxed and boiled in a constant temperature oil bath for 8 hours until the wood blocks are completely white; the wood blocks are rinsed with deionized water to remove residual chemicals, and then reacted in a 5wt% hydrogen peroxide (H2O2) solution at 120°C for 2 hours to enhance bleaching and remove residual lignin; the bleached wood blocks are rinsed with deionized water and freeze-dried for 48 hours to obtain wood aerogel (WA).

[0015] Preferably, in the above-mentioned method for preparing a wood-based solar interface evaporator, the specific preparation process of MOF@WA in step (2) is as follows: the wood aerogel is immersed in a 0.5M copper nitrate / ethanol / water mixed solution for a first vacuum impregnation, and then a 0.05M trimesic acid / ethanol / water mixed solution is added for a second vacuum impregnation, wherein the molar ratio of copper nitrate and trimesic acid is 10:1. After reacting at 25°C for 24 hours, the mixture is washed and vacuum dried to obtain the MOF@WA composite material.

[0016] Preferably, in the above-mentioned method for preparing a wood-based solar interface evaporator, the specific preparation process of the PLC in step (3) is as follows: Take 2g of dealkalized lignin powder, put it into a ceramic boat, place it in a tube furnace, and under N2 atmosphere protection, heat it at 5℃ for 1 minute. -1 The heating rate was increased to 600℃, and carbonization was carried out at a constant temperature for 2 hours. After cooling to room temperature, it was ground into powder; under centrifugation, it was then subjected to 1 mol / L... -1 The powder was washed several times with dilute hydrochloric acid, then rinsed with deionized water to remove soluble impurities. It was then dried in an oven at 80°C for 24 hours to obtain lignin carbonization product powder. This powder was then ground in an agate mortar and sieved through a 500-mesh stainless steel sieve to obtain LC. The LC powder was thoroughly mixed with KOH and placed in a covered corundum crucible. Under a N2 atmosphere, the mixture was heated at 5°C for 1 minute. -1 The heating rate was increased to 850℃, and carbonization was carried out at a constant temperature for 60 minutes. After cooling to room temperature, it was ground into powder; under centrifugation, it was then subjected to 1 mol L... -1 The powder was washed several times with dilute hydrochloric acid, then rinsed with deionized water to remove soluble impurities, and then dried in an oven at 80°C for 24 hours to obtain PLC photothermal material.

[0017] Preferably, in the above-mentioned method for preparing a wood-based solar interface evaporator, the specific preparation process of PLC@MOF@WA in step (4) is as follows: Take 40mg of lignin porous carbon powder, disperse it in 0.5mL of 8g / L chitosan / acetic acid solution, sonicate it for 10min to make it uniformly dispersed, and obtain lignin porous carbon suspension. Coat the lignin porous carbon suspension uniformly on the surface of MOF@WA and dry it naturally at room temperature to obtain PLC@MOF@WA.

[0018] The wood-based solar interface evaporator prepared by the method described above is used for water evaporation driven by solar energy. The specific process is as follows: A 20mm·20mm·10mm wood-based evaporator is embedded in the middle of a 10mm thick circular polystyrene foam board. This board is then floated on the surface of a 100mL beaker containing deionized water. The beaker is placed on an electronic balance connected to a computer for real-time data recording. A xenon lamp is used to simulate sunlight at 1kW / m². 2 -3kW / m 2 A high-intensity light source was vertically irradiated onto the evaporator surface and the water surface for 1 hour. The ambient temperature was 25℃, the humidity was 40%, the deionized water temperature was 25℃, and the water evaporation rate was 2.5594 kg·m³. -2 ·h -1 .

[0019] Therefore, this invention employs the aforementioned method for preparing and applying a wood-based solar interfacial evaporator. Using lignin, a byproduct of pulping and papermaking, as the carbon source, porous lignin carbon is obtained through high-temperature carbonization and used as a photothermal conversion material. Inexpensive, biodegradable, and renewable natural wood is used as the water-conducting and heat-insulating substrate. This assembles a low-cost and biodegradable wood-based solar interfacial evaporator, achieving efficient photothermal conversion, rapid water evaporation rate, and water purification capabilities. Under a single solar irradiance, its evaporation rate reaches as high as 2.5594 kg·m³. –2 ·h –1 It can reduce the sodium ion concentration in seawater from 10,500 ppm to 1.80 ppm.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a longitudinal section SEM image of the PLC@MOF@WA obtained in Embodiment 1 of the present invention;

[0022] Figure 2 This is a diagram showing the temperature rise of the PLC@MOF@WA obtained in Embodiment 2 of the present invention under a solar radiation intensity.

[0023] Figure 3 Evaporation rate curves of pure water, balsa wood logs, and PLC@MOF@WA under one light intensity;

[0024] Figure 4 The water evaporation rate curves for PLC@WA, MOF@WA, and PLC@MOF@WA evaporators under a single light intensity are shown. Detailed Implementation

[0025] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0027] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0028] This invention provides a method for preparing a wood-based solar interfacial evaporator, comprising the following steps:

[0029] (1) Using natural wood as raw material, superhydrophilic wood aerogels were prepared by delignification and freeze-drying, and labeled as WA;

[0030] (2) The wood aerogel was immersed in a mixed solution of copper nitrate and trimesic acid. The MOF material was grafted onto the porous channel surface of the wood aerogel by in-situ grafting technology to obtain the MOF / wood aerogel composite water supply and heat insulation substrate, which was marked as MOF@WA.

[0031] (3) Using lignin as raw material, lignin powder is carbonized at high temperature under N2 atmosphere, washed with dilute hydrochloric acid solution and deionized water, dried, ground and sieved to obtain lignin carbon, which is labeled as LC; LC is uniformly mixed with activator, and the LC / activator mixture is carbonized at high temperature in a tube furnace. After grinding, washing and drying, porous LC photothermal conversion material is obtained, which is labeled as PLC;

[0032] (4) PLC powder was dispersed in chitosan / acetic acid aqueous solution under water bath ultrasonic conditions to prepare lignin porous carbon suspension; it was coated on the upper surface of MOF@WA and dried at room temperature to obtain lignin porous carbon / MOF / wood evaporator, which was labeled as PLC@MOF@WA.

[0033] To further optimize the above technical solution, in step (1), natural wood is cut into blocks of a certain size using a laser cutting machine, and the blocks are soaked and cleaned with anhydrous ethanol. Natural wood includes balsa wood, eucalyptus, linden, willow, birch, beech, pine, etc.

[0034] To further optimize the above technical solution, in step (2), the molar ratio of copper nitrate and pyromellitic acid is 1:15-1:1.

[0035] To further optimize the above technical solution, in step (3), the high-temperature carbonization temperature of lignin is 400℃~900℃ and the time is 1h~2h; the activator includes KOH, K2CO3, ZnCl2, NaOH, H3PO4, etc., and the lignin includes alkaline lignin, dealkalized lignin, enzymatically hydrolyzed lignin, lignin sulfonate, etc.

[0036] To further optimize the above technical solution, in step (4), the ultrasonic frequency is 100W and the time is 10min to 30min.

[0037] To further optimize the above technical solution, the specific process for preparing superhydrophilic wood aerogel in step (1) is as follows: immerse balsa wood blocks in a 2wt% acidic sodium chlorite solution (pH≈4.6), reflux and boil in a constant temperature oil bath for 8 hours until the wood blocks turn completely white; rinse the wood blocks with deionized water to remove residual chemicals, and react in a 5wt% hydrogen peroxide (H2O2) solution at 120℃ for 2 hours to enhance bleaching and remove residual lignin; rinse the bleached wood blocks with deionized water and freeze-dry for 48 hours to obtain wood aerogel (WA).

[0038] To further optimize the above technical solution, the specific preparation process of MOF@WA in step (2) is as follows: the wood aerogel is immersed in a 0.5M copper nitrate / ethanol / water mixed solution for a first vacuum impregnation, and then a 0.05M trimesic acid / ethanol / water mixed solution is added for a second vacuum impregnation, wherein the molar ratio of copper nitrate and trimesic acid is 10:1. After reacting at 25℃ for 24h, the mixture is washed and vacuum dried to obtain the MOF@WA composite material.

[0039] To further optimize the above technical solution, the specific preparation process of PLC in step (3) is as follows: Take 2g of dealkalized lignin powder, put it into a porcelain boat, place it in a tube furnace, and under N2 atmosphere protection, heat it at 5℃ for 1 minute. -1 The heating rate was increased to 600℃, and carbonization was carried out at a constant temperature for 2 hours. After cooling to room temperature, it was ground into powder; under centrifugation, it was then subjected to 1 mol / L... -1 The powder was washed several times with dilute hydrochloric acid, then rinsed with deionized water to remove soluble impurities. It was then dried in an oven at 80°C for 24 hours to obtain lignin carbonization product powder. This powder was then ground in an agate mortar and sieved through a 500-mesh stainless steel sieve to obtain LC. The LC powder was thoroughly mixed with KOH and placed in a covered corundum crucible. Under a N2 atmosphere, the mixture was heated at 5°C for 1 minute. -1 The heating rate was increased to 850℃, and carbonization was carried out at a constant temperature for 60 minutes. After cooling to room temperature, it was ground into powder; under centrifugation, it was then subjected to 1 mol L... -1 The powder was washed several times with dilute hydrochloric acid, then rinsed with deionized water to remove soluble impurities, and then dried in an oven at 80°C for 24 hours to obtain PLC photothermal material.

[0040] To further optimize the above technical solution, the specific preparation process of PLC@MOF@WA in step (4) is as follows: Take 40mg of lignin porous carbon powder, disperse it in 0.5mL of 8g / L chitosan / acetic acid solution, sonicate for 10min to make it uniformly dispersed, and obtain lignin porous carbon suspension. Coat the lignin porous carbon suspension evenly on the surface of MOF@WA and dry it naturally at room temperature to obtain PLC@MOF@WA.

[0041] The wood-based solar interface evaporator prepared by the method described above is used for water evaporation driven by solar energy. The specific process is as follows: A 20mm·20mm·10mm wood-based evaporator is embedded in the middle of a 10mm thick circular polystyrene foam board. This board is then floated on the surface of a 100mL beaker containing deionized water. The beaker is placed on an electronic balance connected to a computer for real-time data recording. A xenon lamp is used to simulate sunlight at 1kW / m². 2 -3kW / m 2A high-intensity light source was vertically irradiated onto the evaporator surface and the water surface for 1 hour. The ambient temperature was 25℃, the humidity was 40%, the deionized water temperature was 25℃, and the water evaporation rate was 2.5594 kg·m³. -2 ·h -1 .

[0042] To more clearly and in detail introduce the preparation method and application of a wood-based solar interface evaporator provided by the embodiments of the present invention, the following description will be based on specific embodiments.

[0043] Example 1

[0044] (1) Immerse 20mm·20mm·10mm balsa wood blocks in a 2wt% acidic sodium chlorite solution (pH≈4.6), and boil them in a constant temperature oil bath under reflux for 8 hours until the wood blocks are completely white; rinse the wood blocks with deionized water to remove residual chemicals, and bleach them again in a 5wt% hydrogen peroxide solution at 120℃ for 2 hours; rinse the bleached wood blocks with deionized water and freeze-dry them for 48 hours to obtain wood aerogel (WA).

[0045] (2) The wood aerogel was immersed in a 0.5M copper nitrate / ethanol / water mixed solution and impregnated under vacuum (200Pa) for 12h. Then, a 0.05M trimesic acid / ethanol / water mixed solution was added, with a molar ratio of copper nitrate to trimesic acid of 10:1. A second vacuum impregnation was performed, and the reaction was carried out at 25℃ for 24h. After washing and vacuum drying, the MOF@WA composite material was obtained.

[0046] (3) Take 2g of alkali-degraded lignin powder, put it into a porcelain boat, place it in a tube furnace, and heat it at 5℃ for 5 minutes under a N2 atmosphere. -1 The temperature was increased to 600℃, carbonized at that temperature for 2 hours, and then cooled to room temperature before being ground into powder. The powder was then centrifuged using 1 mol / L... -1 The carbonized powder was washed several times with dilute hydrochloric acid, then rinsed with deionized water to remove soluble impurities. It was then dried in an oven at 80°C for 24 hours to obtain lignin carbon powder (LC). KOH and LC were thoroughly ground and mixed in a 1:1 mass ratio. The mixture was transferred to a covered corundum crucible and placed in a tube furnace. Under N2 protection, the mixture was heated at 5°C for 1 minute. -1 The temperature was increased to 850℃ at a rate of [temperature value missing] and held for 60 min. After cooling, [the temperature was determined using 1 mol / L...] -1 The carbonized product was washed with hydrochloric acid, followed by washing with a large amount of deionized water until neutral, and then dried in an oven at 80°C for 24 hours to obtain activated lignin carbon. The powder was then ground in an agate mortar and sieved through a stainless steel mesh (500 mesh) to obtain porous lignin carbon powder (PLC).

[0047] (4) Take 40 mg of PLC powder and disperse it in 0.5 mL of 8 g / L chitosan / acetic acid solution. Sonicate for 10 min to ensure uniform dispersion and obtain a lignin porous carbon suspension. Coat the lignin porous carbon suspension evenly on the surface of MOF@WA and allow it to dry naturally at room temperature to obtain a PLC@MOF@WA wood-based evaporator. The SEM image of its longitudinal section is shown below. Figure 1 As shown.

[0048] (5) The wood-based evaporator is embedded in the middle of a 10mm thick circular polystyrene foam board, and floated on the surface of a 100mL beaker containing deionized water. The beaker is placed on an electronic balance connected to a computer for real-time data recording, and simulated sunlight (1kW / m²). 2 The irradiation was applied to the upper surface of a wood-based evaporator for 1 hour, and the mass change was recorded every 5 minutes. The experimental environment was 25℃, 40% humidity, and the temperature of the deionized water was 25℃.

[0049] Example 2

[0050] The preparation method of the wood-based evaporator in Example 2 is the same as in Example 1, except that in step (3) of Example 2, the mass ratio of KOH and LC in the preparation of lignin porous carbon is changed from 1:1 to 4:1. Other operations are the same as in Example 1, ultimately yielding a low-cost wood-based evaporator. The surface temperature rise of the obtained wood-based evaporator under one solar radiation intensity is as follows... Figure 2 As shown.

[0051] Comparative Example 1

[0052] Place a 100mL beaker containing deionized water on the weighing pan of an electronic balance with a strength of 1kW / m. 2 A simulated solar light source was vertically irradiated onto the water surface for 1 hour, and the mass change of the water in the beaker during the irradiation process was recorded. The ambient temperature was 25℃, the humidity was 40%, and the temperature of the deionized water was 25℃.

[0053] Comparative Example 2

[0054] A 10mm thick polystyrene foam board with a 20mm x 20mm x 10mm original balsa wood block embedded in the center was floated on the surface of a 100mL beaker containing deionized water. The beaker was placed on an electronic balance connected to a computer that could record mass changes in real time, with a strength of 1kW / m. 2 The system was subjected to simulated solar radiation perpendicularly for 1 hour, and the mass change caused by water evaporation was recorded in real time. The ambient temperature was 25℃, the humidity was 40%, and the temperature of the deionized water was 25℃.

[0055] Comparative Example 3

[0056] A 10mm thick polystyrene foam board (containing wood aerogel (PLC@WA, 20mm·20mm·10mm) with lignin-loaded porous carbon embedded in its core was floated on the surface of a 100mL beaker of deionized water. The beaker was placed on an electronic balance connected to a computer that could record mass changes in real time, with a strength of 1kW / m. 2 The water was subjected to simulated solar radiation vertically for 1 hour, and the mass change during water evaporation was recorded in real time. The ambient temperature was 25℃, the humidity was 40%, and the temperature of the deionized water was 25℃.

[0057] Comparative Example 4

[0058] A 10mm thick polystyrene foam board (with MOF-grafted wood aerogel (MOF@WA, 20mm·20mm·10mm)) was floated on the surface of a 100mL beaker containing deionized water. The beaker was placed on an electronic balance connected to a computer that could record mass changes in real time, with a strength of 1kW / m. 2 The water was subjected to simulated solar radiation vertically for 1 hour, and the mass change during water evaporation was recorded in real time. The ambient temperature was 25℃, the humidity was 40%, and the temperature of the deionized water was 25℃.

[0059] Performance testing

[0060] The data on the change of water evaporation over time in Example 1, Comparative Example 1, and Comparative Example 2 were analyzed respectively. Figure 3 It can be seen that at a strength of 1kW / m 2 When exposed to a xenon lamp simulating sunlight for 1 hour, the water evaporation rate for pure water, balsa wood logs, and PLC@MOF@WA was 0.2980 kg·m³. -2 ·h -1 0.4700 kg·m -2 ·h -1 and 2.1133 kg·m -2 ·h -1 Experimental data show that water alone evaporates very little per unit area and time. The introduction of wood aerogel evaporators can significantly increase the evaporation rate. In particular, after dual modification with lignin porous carbon surface loading and MOF in-situ grafting, the evaporation rate of water is greatly improved. The evaporation rate of the PLC@MOF@WA wood-based evaporator is about 7.1 times that of pure water.

[0061] The data on the change of water evaporation over time in Comparative Example 2, Comparative Example 3, and Comparative Example 4 were analyzed respectively. Figure 4 It can be seen that at a strength of 1kW / m 2 When the xenon lamp was irradiated under simulated sunlight for 1 hour, the water evaporation rates of PLC@WA, MOF@WA, and PLC@MOF@WA were 0.7274 kg·m³, respectively. -2 ·h-1 1.8807 kg·m -2 ·h -1 and 2.5594 kg·m -2 ·h -1 Experimental results show that, compared with individual modification, the synergistic modification of lignin porous carbon surface loading and MOF in-situ grafting results in better water evaporation in the wood evaporator. Furthermore, the surface temperature of PLC@MOF@WA ultimately reaches 47.6℃, indicating that the PLC@MOF@WA evaporator has excellent photothermal conversion capabilities.

[0062] The PLC@MOF@WA evaporator of Example 1 was used to evaporate and desalinate simulated seawater. The changes in the concentration of each metal ion before and after evaporation were observed, as shown in Table 1.

[0063] Table 1. Concentration changes of various metal ions before and after simulated seawater evaporation.

[0064] ion Initial concentration (ppm) Freshwater concentration (ppm) <![CDATA[Na + ]]> 10500 1.80 <![CDATA[K + ]]> 380 0.12 <![CDATA[Ca 2+ ]]> 415 0.56 <![CDATA[Mg 2+ ]]> 580 0.40

[0065] Therefore, this invention employs the aforementioned method for preparing and applying a wood-based solar interfacial evaporator. Using lignin, a byproduct of pulping and papermaking, as the carbon source, porous lignin carbon is obtained through high-temperature carbonization and used as a photothermal conversion material. Inexpensive, biodegradable, and renewable natural wood is used as the water-conducting and heat-insulating substrate. This assembles a low-cost and biodegradable wood-based solar interfacial evaporator, achieving efficient photothermal conversion, rapid water evaporation rate, and water purification capabilities. Under a single solar irradiance, its evaporation rate reaches as high as 2.5594 kg·m³. –2 ·h –1 It can reduce the sodium ion concentration in seawater from 10,500 ppm to 1.80 ppm.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a wood-based solar interface evaporator, characterized in that, Includes the following steps: (1) Using natural wood as raw material, superhydrophilic wood aerogels were prepared by delignification and freeze-drying, and labeled as WA; (2) The wood aerogel was immersed in a mixed solution of copper nitrate and trimellitic acid. The MOF material was grafted onto the porous channel surface of the wood aerogel by in-situ grafting technology to obtain the MOF / wood aerogel composite water-transporting and heat-insulating substrate, which was marked as MOF@WA; the molar ratio of copper nitrate and trimellitic acid was 1:15-1:

1. The specific preparation process of MOF@WA is as follows: Wood aerogel is immersed in a 0.5M copper nitrate / ethanol / water mixed solution for a first vacuum impregnation, and then a 0.05M trimellitic acid / ethanol / water mixed solution is added for a second vacuum impregnation, wherein the molar ratio of copper nitrate and trimellitic acid is 10:

1. After reacting at 25℃ for 24h, it is washed and vacuum dried to obtain MOF@WA composite material; (3) Using lignin as raw material, the lignin powder is carbonized at high temperature under N2 atmosphere, washed with dilute hydrochloric acid solution and deionized water, dried, ground and sieved to obtain lignin carbon, which is labeled as LC. The LC and activator were uniformly mixed, and the LC / activator mixture was carbonized at high temperature in a tube furnace. After grinding, washing and drying, a porous LC photothermal conversion material was obtained, which was labeled as PLC. The specific preparation process of PLC is as follows: Take 2g of dealkalized lignin powder, put it into a porcelain boat, place it in a tube furnace, and heat it at 5℃ for 5 minutes under a N2 atmosphere. -1 The heating rate was increased to 600℃, and carbonization was carried out at a constant temperature for 2 hours. After cooling to room temperature, it was ground into powder; under centrifugation, it was then subjected to 1 mol / L... -1 The powder was washed several times with dilute hydrochloric acid, then rinsed with deionized water to remove soluble impurities. It was then dried in an oven at 80°C for 24 hours to obtain lignin carbonization product powder. This powder was then ground in an agate mortar and sieved through a 500-mesh stainless steel sieve to obtain LC. The LC powder was thoroughly mixed with KOH and placed in a covered corundum crucible. Under a N2 atmosphere, the mixture was heated at 5°C for 1 minute. -1 The heating rate was increased to 850℃, and carbonization was carried out at a constant temperature for 60 minutes. After cooling to room temperature, it was ground into powder; under centrifugation, it was then subjected to 1 mol / L... -1 The powder was washed several times with dilute hydrochloric acid, then rinsed with deionized water to remove soluble impurities, and then dried in an oven at 80°C for 24 hours to obtain PLC photothermal material. (4) PLC powder was dispersed in chitosan / acetic acid aqueous solution under water bath ultrasonic conditions to prepare lignin porous carbon suspension; it was coated on the upper surface of MOF@WA and dried at room temperature to obtain lignin porous carbon / MOF / wood evaporator, which was labeled as PLC@MOF@WA.

2. The method for preparing a wood-based solar interface evaporator according to claim 1, characterized in that, In step (1), natural wood is cut into blocks of a certain size using a laser cutting machine, and the blocks are then soaked and cleaned with anhydrous ethanol.

3. The method for preparing a wood-based solar interface evaporator according to claim 1, characterized in that, In step (3), the high-temperature carbonization temperature of lignin is 400℃~900℃ and the time is 1h~2h; the activator includes one or more of KOH, K2CO3, ZnCl2, NaOH, and H3PO4.

4. The method for preparing a wood-based solar interface evaporator according to claim 1, characterized in that, In step (4), the ultrasonic frequency is 100W and the time is 10min to 30min.

5. The method for preparing a wood-based solar interface evaporator according to claim 1, characterized in that, The specific process for preparing superhydrophilic wood aerogel in step (1) is as follows: balsa wood blocks are soaked in a 2wt% acidic sodium chlorite solution and boiled under reflux in a constant temperature oil bath for 8 hours until the wood blocks turn completely white; the wood blocks are rinsed with deionized water to remove residual chemicals and then reacted in a 5wt% hydrogen peroxide solution at 120°C for 2 hours to enhance bleaching and remove residual lignin; the bleached wood blocks are rinsed with deionized water and freeze-dried for 48 hours to obtain WA.

6. The method for preparing a wood-based solar interface evaporator according to claim 1, characterized in that, The specific preparation process of PLC@MOF@WA in step (4) is as follows: Take 40mg of lignin porous carbon powder, disperse it in 0.5mL of 8g / L chitosan / acetic acid solution, sonicate for 10min to make it uniformly dispersed, and obtain lignin porous carbon suspension. Coat the lignin porous carbon suspension evenly on the surface of MOF@WA and dry it naturally at room temperature to obtain PLC@MOF@WA.

7. The application of a wood-based solar interface evaporator prepared by the method described in any one of claims 1-6, characterized in that, The process for solar-driven water evaporation is as follows: A 20mm x 20mm x 10mm wood-based evaporator is embedded in a 10mm thick circular polystyrene foam board. This evaporator is then floated on the surface of a 100mL beaker containing deionized water. The beaker is placed on an electronic balance connected to a computer for real-time data recording. A xenon lamp is used to simulate sunlight at a power of 1kW / m². 2 -3kW / m 2 A high-intensity light source was vertically irradiated onto the evaporator surface and the water surface for 1 hour. The ambient temperature was 25℃, the humidity was 40%, the deionized water temperature was 25℃, and the water evaporation rate was 2.5594 kg·m³. -2 ·h -1 .

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