Preparation method of a wood-based double-convection structure solar interface evaporator

Abstract

The present invention belongs to the technical field of photothermal conversion materials, and specifically relates to a method for preparing a wood-based double-convection structure solar interface evaporator, comprising the following steps: (1) pretreatment: cutting basswood into wood blocks, ultrasonically treating the blocks, and drying the blocks to obtain dried wood blocks; (2) preparation of a wood-based double-convection structure solar interface evaporator substrate: removing a portion of the central region of the dried wood blocks to obtain a wood-based double-convection structure solar interface evaporator substrate; (3) preparation of a precursor solution: dissolving MXene powder in deionized water, ultrasonically treating the blocks, and obtaining a precursor solution; (4) synthesis reaction: stirring and compounding the wood-based double-convection structure solar interface evaporator substrate and the precursor solution, collecting the product, repeatedly washing the product with deionized water and ethanol, and drying the product to obtain the final wood-based double-convection structure solar interface evaporator. The method of the present invention is simple in process, and the obtained solar interface evaporator retains the ordered porous channels of wood, and has high evaporation performance and good stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of photothermal conversion materials, and in particular relates to a method for preparing a wood-based double-convection structure solar interface evaporator. Background Art

[0002] The earth has abundant seawater resources, and desalination is undoubtedly one of the effective strategies to solve the problem of fresh water shortage. However, traditional desalination technologies (such as electrodialysis and reverse osmosis) still face a series of problems such as excessive energy consumption, complex process flow, and huge energy costs. As an environmentally friendly and renewable energy source, solar energy has been widely used since ancient times. Solar interfacial evaporation technology (SIE) uses green energy solar energy to obtain fresh water by performing photothermal evaporation at the gas-liquid interface of the evaporation device. It does not require additional energy consumption and has a simple process flow. Therefore, solar-driven interfacial water evaporation is considered to be one of the most effective ways. However, although traditional evaporators have excellent performance, the manufacturing process is cumbersome and the performance is low. For example, the poor photothermal conversion capacity and high surface humidity lead to reduced evaporation performance and poor stability.

[0003] In recent years, solar evaporators have attracted great attention. For example, Chinese patent CN 111170393 A discloses a solar evaporator with a hollow structure, its preparation method and application. The invention provides a solar evaporator with a hollow structure inside and a shell with a two-layer structure outside. The two layers are respectively a porous polymer skeleton inner layer and an outer layer formed by a photothermal material. The solar evaporator obtained by the invention can generate heat in the presence of simulated sunlight (one sunlight intensity: 1KWm -2 ) irradiation, the maximum evaporation rate can reach 1.476 kg m -2 h -1 The highest evaporation efficiency can reach 92.9%. However, due to the high tortuosity of the porous polymer skeleton structure, the water transport rate and ion diffusion rate of the solar evaporator are slow. In addition, during the long-term desalination process, salt will gradually precipitate and block the pores, preventing steam from escaping, which significantly reduces the evaporation performance.

[0004] To improve water transport and ion diffusion rates, Chinese patent CN 112794307 A discloses a method for preparing a double-layer monolithic photothermal conversion material. This method involves preparing a polysaccharide aerogel matrix with a vertical pore structure through low-temperature freezing and freeze-drying, followed by high-temperature carbonization to obtain an in-situ carbonized chitosan aerogel. The large number of vertically arranged pore structures can provide sufficient water for the light absorber in the upper layer of the solar evaporator. However, the partial carbonization method may cause damage to the chitosan aerogel's upper structure and shrinkage, interfering with the water transport and ion diffusion rates. Furthermore, the light absorption rate of the partially carbonized photothermal material needs to be improved.

[0005] Therefore, it is very important to research and develop a preparation method for a solar interface evaporator that can improve water transmission speed, accelerate light-to-heat conversion, reduce surface humidity, and has high stability, no salting out, and simple preparation method. Summary of the Invention

[0006] The present invention aims to solve the above technical problems and provides a method for preparing a wood-based double-convection structure solar interface evaporator. The method is simple in process, and the prepared solar interface evaporator retains the ordered porous channels of wood, and has high evaporation performance and good stability.

[0007] The technical solution of the present invention is:

[0008] A method for preparing a wood-based double-convection structure solar interface evaporator comprises the following steps:

[0009] (1) Pretreatment: Basswood was cut into blocks with a length-width-height ratio of 3:2:2 along the direction perpendicular to the tree growth. The blocks were ultrasonically treated with deionized water and ethanol in sequence and then dried to obtain dry blocks.

[0010] (2) Preparation of the wood-based double-convection structure solar interface evaporator substrate: removing a portion of the central area of ​​the dry wood block to obtain the wood-based double-convection structure solar interface evaporator substrate;

[0011] (3) Preparation of precursor solution: MXene powder was dissolved in deionized water and ultrasonically treated to obtain a precursor solution;

[0012] (4) Synthesis reaction: The wood-based double convection structure solar interface evaporator substrate in step (2) and the precursor solution in step (3) were stirred and compounded at a material-liquid ratio of 30 mg:50 mL, the product was collected, repeatedly washed with deionized water and ethanol, and dried to obtain the final wood-based double convection structure solar interface evaporator.

[0013] In order to prevent the wood base from affecting the performance of the subsequent solar interface evaporator, the wood block needs to be cleaned with deionized water and ethanol in sequence. Preferably, in step (1) of the present invention, the material-liquid ratio of the wood block to deionized water or ethanol is 6.36 g:50 mL, and the wood block is ultrasonicated in deionized water and ethanol for 10-30 minutes respectively. Preferably, in step (1) of the present invention, the drying conditions are 50-60°C for 1.5-2 hours.

[0014] In order to obtain a solar interface evaporator with a double convection structure, a part of the central area of ​​the dried wood block is removed. In order to obtain a solar interface evaporator with excellent performance, preferably, in step (2) of the present invention, the central area is removed: starting from the center of the length and width of the wood block, the central area is cut out according to the ratio of the length, width and height corresponding to the wood block of (3:2): (2:1): (2:2). If too much of the central part is removed, the evaporation surface area is reduced and the evaporation rate may be reduced; if too little is removed, the evaporation surface area is too large, and the double convection may be formed slowly or difficult to form, resulting in a reduced evaporation rate.

[0015] In order to obtain excellent light absorption performance, the present invention loads MXene powder onto the substrate of a wood-based double-convection structure solar interface evaporator, synergistically improving the evaporation performance of the evaporator, and prepares MXene powder into a precursor liquid. Preferably, in step (3) of the present invention, the material-liquid ratio of MXene powder to deionized water is 3-4:5 mg / mL; and the ultrasonic treatment is preferably performed for 1.5-2.5 h.

[0016] In order to obtain MXene powder, preferably, in step (3) of the present invention, the preparation method of MXene powder is: dissolving LiF in HCl solution and stirring uniformly at room temperature to obtain a mixed solution; then adding Ti3AlC2 to the above-mentioned mixed solution, stirring uniformly, centrifuging, and ultrasonically treating the solid matter to obtain MXene powder. Preferably, the material-liquid ratio of the LiF and HCl solution is 3g:50mL; the weight ratio of LiF and Ti3AlC2 is 1.2:1; in the present invention, the solid matter is ultrasonically treated for 50-70 min, and the concentration of the HCl solution is 9 mol / L.

[0017] In order to make the precursor liquid more evenly loaded onto the wood-based double convection structure solar interface evaporator substrate and to improve the evaporation performance of the evaporator, preferably, in the step (4), after adding the precursor liquid to the wood-based double convection structure solar interface evaporator substrate in step (2), 0.2-0.8% of the weight of the precursor liquid of fumed silica is also added. Fumed silica can well disperse the MXene powder material, prevent the MXene powder from agglomerating during the composite process with the wood-based double convection structure solar interface evaporator substrate, and make the MXene powder material evenly dispersed on the wood-based double convection structure solar interface evaporator substrate. At the same time, it can improve the adsorption force of the MXene powder material on the wood-based double convection structure solar interface evaporator substrate, thereby improving the mechanical properties and subsequent stability of the solar interface evaporator as a whole, and improving the evaporation performance of the evaporator as a whole.

[0018] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0019] 1. The method of the present invention directly removes the middle part of the wood base surface and designs a new double-convection porous structure evaporator, which retains the three-dimensional ordered porous structure of the wood itself, provides a large number of channels for rapid water transport in the evaporator, and concentrates the heat on the evaporator surface, effectively improving the evaporation rate, reducing the negative impact of high humidity on evaporation performance, improving evaporation performance, and effectively avoiding the occurrence of reduced evaporation performance due to insufficient water supply. At the same time, the method has mild reaction conditions, simple preparation, and is green.

[0020] 2. The method of the present invention uses multi-porous wood as the substrate and loads MXene photothermal material to form a dual convection structure, which significantly enhances the light absorption capacity and rapid water supply, increases the heat concentration on the evaporation surface, and at the same time, the dual convection structure is conducive to reducing the humidity of the evaporation surface, accelerating water evaporation, and further improving the evaporation performance and stability of the evaporator.

[0021] 3. The method of the present invention also adds fumed silica, which can disperse the MXene powder material very well, avoid the agglomeration of the MXene powder during the compounding process with the wood-based double-convection structure solar interface evaporator substrate, and make the MXene powder material evenly dispersed on the wood-based double-convection structure solar interface evaporator substrate. At the same time, it can improve the adsorption force of the MXene powder material on the wood-based double-convection structure solar interface evaporator substrate, thereby improving the mechanical properties and subsequent stability of the solar interface evaporator as a whole.

[0022] 4. The present invention demonstrates excellent stability in the application of a wood-based solar interface evaporator with a dual convection structure in seawater desalination. The evaporation rate remains essentially unchanged for eight hours of continuous evaporation, and there is still no salt crystallization on the evaporation surface. This not only solves the many challenges faced by traditional evaporators in seawater desalination applications, but also provides strong technical support for achieving efficient and low-cost freshwater production, which is of great significance for promoting the widespread application of renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a longitudinal scanning electron microscope image of the evaporator prepared in Example 1 of the present invention.

[0024] Figure 2 Graphs showing the evaporation performance of the evaporators prepared in Examples 1, 2, and 3 of the present invention.

[0025] Figure 3 This is a stability diagram of the evaporator prepared in Example 1 of the present invention.

[0026] Figure 4 This is a sample diagram of the wood-based double-convection structure solar interface evaporator substrate obtained in the present invention. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention. Example 1

[0028] A method for preparing a wood-based double-convection structure solar interface evaporator comprises the following steps:

[0029] (1) Pretreatment: First, the basswood was cut into 3 cm × 2 cm × 2 cm blocks along the vertical direction of the tree growth. The blocks were ultrasonically cleaned with ethanol and deionized water for 20 min respectively, and then dried in a vacuum drying oven at 50 °C for 2 h. The material-liquid ratio of the block to deionized water was 6.36 g:50 mL, and the material-liquid ratio of the block to ethanol was 6.36 g:50 mL.

[0030] (2) Preparation of double convection structural wood: Use a milling machine to remove a part of the central area of ​​a wood block (3cm×2cm×2cm) (the part of the central area removed: starting from the center of the length and width of the wood block, cut out the central area according to the ratio of the length, width and height of the wood block (3:2): (2:1): (2:2), such as Figure 4 As shown), a wood-based double convection structure solar interface evaporator substrate is obtained;

[0031] (3) Preparation of precursor solution: 3 g of LiF was dissolved in 50 mL of 9 mol / L HCl solution and stirred at room temperature for 10 min to obtain a mixed solution; then 2.5 g of Ti3AlC2 was slowly added to the above mixture solution and stirred at 40 °C for 24 h. The mixture was centrifuged at 400 r / min. After centrifugation for 2 h, the sample was taken out and ultrasonicated for 1 h to obtain powder material MXene. Then, 30 mg of MXene was dissolved in 50 mL of deionized water and ultrasonicated for 2 h to obtain a precursor solution.

[0032] (4) Synthesis reaction: The wood-based double convection structure solar interface evaporator substrate in step (2) was placed into the precursor solution in step (3) at a material-liquid ratio of 30 mg:50 mL and stirred at 400 rpm for 2 h. The product was collected and washed with deionized water and ethanol respectively, and the washing was repeated twice. The washed precipitate was placed in a vacuum drying oven and dried at 60 ° C for 2 h to obtain a wood-based double convection structure solar interface evaporator.

[0033] The wood-based double convection structure solar interface evaporator in this embodiment is directly placed in deionized water for photothermal evaporation test to characterize its evaporation performance during water evaporation. Figure 2 As shown in Figure 2, under 1 sun, the evaporation rate of the wood-based double convection structure solar interface evaporator is 2.16 kg m -2 h -1 , the photothermal conversion efficiency is 118%.

[0034] In addition, the wood-based double convection structure solar interface evaporator in this embodiment was directly placed in simulated seawater (3.5 wt% salt water) for 8 hours of photothermal evaporation test to test its salt resistance stability. Figure 3 As shown in the figure, after 8 hours of continuous evaporation, the evaporation rate remains basically unchanged and there is no salt crystallization on the surface, which shows the excellent stability of the evaporator. Example 2

[0035] A method for preparing a wood-based double-convection structure solar interface evaporator comprises the following steps:

[0036] (1) Pretreatment: First, the basswood was cut into 3 cm × 2 cm × 2 cm blocks along the vertical direction of the tree growth. The blocks were ultrasonically cleaned with ethanol and deionized water for 20 min respectively, and then dried in a vacuum drying oven at 60 °C for 1.5 h. The ratio of the wood block to deionized water was 6.36 g:50 mL, and the ratio of the wood block to ethanol was 6.36 g:50 mL.

[0037] (2) Preparation of double-convection structure wood: A portion of the central area of ​​a wood block (3 cm × 2 cm × 2 cm) was removed using a milling machine (same as in Example 1) to obtain a wood-based double-convection structure solar interface evaporator substrate;

[0038] (3) Preparation of precursor solution: 3 g of LiF was dissolved in 50 mL of HCl solution and stirred at room temperature for 10 min to obtain a mixed solution; then 2.5 g of Ti3AlC2 was slowly added to the above mixture solution and stirred at 40 °C for 24 h. After centrifugation for 2 h, the sample was taken out and ultrasonicated for 1 h to obtain powder material MXene. Then 30 mg of MXene was dissolved in 50 mL of deionized water and ultrasonicated for 2 h to obtain a precursor solution;

[0039] (4) Synthesis reaction: The wood-based double convection structure solar interface evaporator substrate in step (2) was placed in the precursor solution of step (3) and stirred at 400 rpm for 2 h. The product was collected and washed with deionized water and ethanol respectively, and the washing was repeated twice. The washed precipitate was placed in a vacuum drying oven and dried at 60 ° C for 2 h to obtain a wood-based double convection structure solar interface evaporator. Example 3

[0040] The difference from Example 1 is: (4) Synthesis reaction: the wood-based double convection structure solar interface evaporator substrate in step (2) is placed in the precursor solution in step (3), and then 0.2 wt% of the weight of the precursor solution is added with gas-phase silica; the remaining steps and parameters are the same as in Example 1.

[0041] The wood-based double convection structure solar interface evaporator in this embodiment was directly placed in deionized water for photothermal evaporation testing to characterize its evaporation performance during the water evaporation process. Under 1 sun, the evaporation rate of the wood-based double convection structure solar interface evaporator was 2.82 kg m -2 h -1 , the photothermal conversion efficiency is 123%.

[0042] Furthermore, the wood-based dual-convection solar interface evaporator from this example was placed directly in simulated seawater (3.5 wt% brine) for 8 hours to test its salt tolerance. After 24 hours of continuous evaporation, the evaporation rate remained essentially unchanged, and no salt crystals were observed on the surface, demonstrating the evaporator's excellent stability. Example 4

[0043] The difference from Example 1 is: (4) Synthesis reaction: the wood-based double convection structure solar interface evaporator substrate in step (2) is placed in the precursor solution in step (3), and then 0.8% of the weight of the precursor solution is added with gas-phase silica; the remaining steps and parameters are the same as in Example 1.

[0044] The wood-based double convection structure solar interface evaporator in this embodiment was directly placed in deionized water for photothermal evaporation testing to characterize its evaporation performance during the water evaporation process. Under 1 sun, the evaporation rate of the wood-based double convection structure solar interface evaporator was 2.74 kg m -2 h -1 , the photothermal conversion efficiency is 121%.

[0045] Furthermore, the wood-based dual-convection solar interface evaporator from this example was placed directly in simulated seawater (3.5wt% brine) for 8 hours to test its salt tolerance. After 24 hours of continuous evaporation, the evaporation rate remained essentially unchanged, and no salt crystals were observed on the surface, demonstrating the evaporator's excellent stability.

[0046] Comparative Example 1

[0047] A method for preparing a wood-based solar interface evaporator comprises the following steps:

[0048] Preparation of the evaporator: First, basswood was cut into 3 cm × 2 cm × 2 cm basswood blocks along the direction perpendicular to the tree growth. The blocks were ultrasonically cleaned with ethanol and deionized water for 20 min respectively, and then dried in a 50°C vacuum drying oven for 2 h to obtain a wood-based solar interface evaporator. The material-liquid ratio of the wood block to deionized water was 6.36 g:50 mL, and the material-liquid ratio of the wood block to ethanol was 6.36 g:50 mL.

[0049] As can be seen from the figure, the central area of ​​Comparative Example 1 is not removed, and its evaporation rate is lower than that of Examples 1 and 2.

[0050] Comparative Example 2

[0051] The difference from Example 1 is: (4) Synthesis reaction: the wood-based double convection structure solar interface evaporator substrate in step (2) is placed in the precursor solution in step (3), and then 1% of the weight of the precursor solution is added with gas-phase silica; the remaining steps and parameters are the same as in Example 1.

[0052] The wood-based dual-convection solar interface evaporator in this example was placed directly in deionized water for photothermal evaporation testing to characterize its evaporation performance. Under 1 sun, the photothermal conversion efficiency of the wood-based dual-convection solar interface evaporator was 91%.

[0053] Furthermore, the wood-based dual-convection solar interface evaporator from this example was placed directly in simulated seawater (3.5 wt% brine) for 8 hours to test its salt tolerance. After 8 hours of continuous evaporation, some salt crystals formed on the surface.

[0054] In summary, the amount of fumed silica added cannot be excessive. If it is excessive, it will adhere to the evaporator substrate or precursor liquid material particles, which will also affect the adhesion uniformity, reduce the absorption of light, and thus reduce the photothermal conversion efficiency.

[0055] Comparative Example 3

[0056] The difference from Example 1 is that: a larger area is removed, and part of the central area is removed: starting from the center of the length and width of the wood block, the central area is cut out according to the ratio of the length, width and height of the wood block corresponding to (6:5): (2:1): (2:2), and the rest is the same as Example 1.

[0057] The wood-based double convection structure solar interface evaporator in this comparative example was directly placed in deionized water for photothermal evaporation test to characterize its evaporation performance during water evaporation. Under 1 sun, the evaporation rate of the wood-based double convection structure solar interface evaporator was 2.14 kg m -2 h -1 , the photothermal conversion efficiency is 117%.

[0058] Comparative Example 4

[0059] The difference from Example 1 is that: a smaller area is removed, and part of the central area is removed: starting from the center of the length and width of the wooden block, the central area is cut out according to the ratio of the length, width and height of the wooden block corresponding to (2:1): (2:1): (2:2), and the rest is the same as Example 1.

[0060] The wood-based double convection structure solar interface evaporator in this comparative example was directly placed in deionized water for photothermal evaporation test to characterize its evaporation performance during water evaporation. Under 1 sun, the evaporation rate of the wood-based double convection structure solar interface evaporator was 1.82 kg m -2 h -1 , the photothermal conversion efficiency is 97%.

[0061] The above description is a detailed description of the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for preparing a wood-based double convection structure solar interface evaporator, characterized in that: The following steps are involved: (1) Pretreatment: Basswood was cut into blocks with a length-width-height ratio of 3:2:2 along the direction perpendicular to the tree growth. The blocks were ultrasonically treated with deionized water and ethanol in sequence and then dried to obtain dry blocks. (2) Preparation of the wood-based double-convection structure solar interface evaporator substrate: removing a portion of the central area of ​​the dry wood block to obtain the wood-based double-convection structure solar interface evaporator substrate; (3) Preparation of precursor solution: MXene powder was dissolved in deionized water, centrifuged, and ultrasonicated to obtain the precursor solution; (4) Synthesis reaction: The wood-based double convection structure solar interface evaporator substrate in step (2) and the precursor solution in step (3) were stirred and compounded at a material-liquid ratio of 30 mg:50 mL, the product was collected, and repeatedly washed with deionized water and ethanol, and dried to obtain the final wood-based double convection structure solar interface evaporator; In step (2), the central area is removed by taking the center of the length and width of the wood block as the starting point and cutting out the central area according to the length, width and height ratios of the wood block (3:2): (2:1): (2:2); In the step (4), after adding the precursor liquid to the wood-based double convection structure solar interface evaporator substrate in step (2), 0.2-0.8% of the weight of the precursor liquid of fumed silica is also added.

2. The method for preparing the wood-based double-convection structure solar interface evaporator according to claim 1, characterized in that: In the step (1), the material-liquid ratio of the wood block to deionized water or ethanol is 6.36 g:50 mL, and the wood block is ultrasonically treated in deionized water or ethanol for 10-30 min respectively.

3. The method for preparing the wood-based double convection structure solar interface evaporator according to claim 1, characterized in that: In the step (1), the drying conditions are 50-60°C for 1.5-2h.

4. The method for preparing the wood-based double convection structure solar interface evaporator according to claim 1, characterized in that: In step (3), the material-liquid ratio of MXene powder to deionized water is 3-4 mg:5 mL.

5. The method for preparing the wood-based double convection structure solar interface evaporator according to claim 1, characterized in that: In the step (3), ultrasonic treatment is performed for 1.5-2.5 h.

6. The method for preparing the wood-based double convection structure solar interface evaporator according to claim 1, characterized in that: In step (3), the preparation method of MXene powder is as follows: dissolving LiF in HCl solution and stirring uniformly at room temperature to obtain a mixed solution; then adding Ti3AlC2 to the mixed solution, stirring uniformly, centrifuging, and ultrasonically treating the solid matter to obtain MXene powder.

7. The method for preparing the wood-based double convection structure solar interface evaporator according to claim 6, characterized in that: The material-liquid ratio of the LiF and HCl solutions is 3 g:50 mL; the weight ratio of the LiF and Ti3AlC2 is 1.2:

1.

8. The method for preparing the wood-based double convection structure solar interface evaporator according to claim 6, characterized in that: The solid material was ultrasonically treated for 50-70 min, and the concentration of the HCl solution was 9 mol / L.

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