Preparation method and application of porous interfacial photo-thermal evaporation material
The preparation of porous interfacial photothermal evaporation materials by low-temperature/inferior solvent co-initiated phase separation method solves the problems of high cost and low efficiency in existing technologies, and achieves low-energy and high-efficiency seawater desalination.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANTONG UNIV
- Filing Date
- 2023-07-12
- Publication Date
- 2026-04-21
AI Technical Summary
Existing seawater desalination technologies are costly, energy-intensive, and have poor portability. Traditional photothermal evaporators are inefficient, and freeze-dried aerogel materials are expensive to produce.
Porous interfacial photothermal evaporation materials were prepared using a low-temperature/inferior solvent co-initiated phase separation method. Through the synergistic effect of hydrophilic polymers and alumina fibers, a porous structure was formed, which, combined with photothermal materials, improved evaporation efficiency.
A porous interfacial photothermal evaporation material was prepared at low cost and over a large area. It has excellent hydrophilicity and photothermal conversion function, which improves the seawater evaporation rate and reduces energy consumption. It is suitable for interfacial photothermal evaporators.
Smart Images
Figure CN117050371B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of seawater desalination technology, specifically relating to a method for preparing and applying a porous interfacial photothermal evaporation material. Background Technology
[0002] The increasing scarcity of freshwater resources is due to population growth, industrial development, and ecosystem degradation. Several proven seawater desalination technologies exist, such as vapor compression (VC) and humidification-dehumidification (HDH). However, these methods require integration with other equipment, have poor portability, and are costly and power-intensive.
[0003] Photothermal evaporation systems utilize solar energy to drive water evaporation and obtain fresh water. However, traditional solar thermal evaporators typically place the photothermal material in water, resulting in relatively low efficiency in obtaining fresh water. Interfacial photothermal evaporators have the function of absorbing solar energy and converting it into heat on the evaporator surface to evaporate brine or wastewater to obtain fresh water. Therefore, this technology is one of the more promising methods in the field of seawater desalination. Existing methods involve using freeze-dried aerogels in interfacial photothermal evaporators. For example, CN110183572A discloses an aerogel, its preparation method, and its application as a solar evaporator. The aerogel consists of a water supply layer and a light absorption layer. When using the aerogel as a solar evaporator, the lower water supply layer provides water to the upper light absorption layer. The upper light absorption layer absorbs solar energy and converts it into heat to evaporate water, allowing water to be transferred from the water supply layer to the light absorption layer. However, this method requires long-term drying under harsh low-temperature conditions, resulting in high energy consumption and high manufacturing costs. Summary of the Invention
[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing porous interfacial photothermal evaporation materials; another objective of the present invention is to provide the application of the porous interfacial photothermal evaporation materials in interfacial photothermal evaporators.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing porous interfacial photothermal evaporation materials, comprising the following steps:
[0006] (1) Dissolve the hydrophilic polymer in a good solvent, and add photothermal material and alumina fiber at the same time. Stir and dissolve at a temperature below 40°C until completely dissolved to obtain a mixed solution.
[0007] (2) The mixed solution obtained in step (1) is subjected to degassing treatment to obtain a homogeneous and transparent solution;
[0008] (3) The homogeneous and transparent solution obtained in step (2) is stirred at 60-90°C and a poor solvent is added dropwise. The mixture is then heated and stirred at 60-90°C to obtain a blended solution.
[0009] (4) After sealing the blended solution obtained in step (3), phase separation is carried out at 5-30℃ to obtain the primary solidified solid.
[0010] (5) The nascent solid obtained in step (4) is washed to remove excess good and bad solvents, and a porous interfacial photothermal evaporation material is obtained.
[0011] Further, in step (1), the alumina fiber has a length of 0.5 to 1 mm and a diameter of 14 to 17 μm.
[0012] Further, in step (1), the hydrophilic polymer is selected from starch, cellulose, alginic acid, polyvinyl alcohol or polymethacrylic acid, and the cellulose is selected from cellulose acetate; the photothermal material is one or more of carbon-based materials, nano-metal materials, organic materials and semiconductor materials; the carbon-based material is selected from graphene, reduced graphene oxide or carbon nanotubes; the organic material is selected from polypyrrole, polyaniline, polythiophene or polydopamine; the semiconductor material is selected from titanium dioxide or aluminum nitride; and the nano-metal material is selected from nano-gold or nano-silver.
[0013] Further, in step (1), the good solvent is selected from N,N-dimethylformamide, N,N-dimethylacetamide, acetone, dichloromethane, tetrahydrofuran or dimethyl sulfoxide.
[0014] Furthermore, in step (2), the degassing treatment method is selected from ultrasonic treatment, depressurized standing, or the addition of a degassing agent.
[0015] Furthermore, in step (3), the inferior solvent is selected from hexanol, isohexanediol, octanediol or water.
[0016] Furthermore, in step (4), the phase separation time is 20 to 40 minutes.
[0017] Furthermore, in step (5), the solvent used for washing is methanol or ethanol.
[0018] Further, the concentration of the hydrophilic polymer in the blend solution is 60–120 mg / mL; the mass ratio of the hydrophilic polymer, photothermal material, and alumina fiber is 0.8–1.5:0.16–0.35:0.6–1.2; and the volume percentage of the good solvent to the inferior solvent is 36%–44%:56%–64%.
[0019] The porous interfacial photothermal evaporation material prepared by the above method.
[0020] The above-mentioned porous interfacial photothermal evaporation materials are used in interfacial photothermal evaporators.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] (1) By using the low temperature / inferior solvent co-initiated phase separation method, the porous interface photothermal evaporation material can be formed into a porous structure by washing out the good solvent and the inferior solvent. A porous interface photothermal evaporation material with good continuous water supply capacity can be prepared. The preparation method is simple and easy to implement, and avoids the use of high-energy-consuming freeze-drying equipment. It can be prepared on a large scale and is convenient for market promotion and application. The porous interface photothermal evaporation material is embedded in the end of the through hole in the floating layer that allows it to float. Due to the excellent hydrophilicity of the porous interface photothermal evaporation material, the bottom of the porous interface photothermal evaporation material floating on the water surface is in contact with the water surface and can continuously supply water to the surface of the porous interface photothermal evaporation material to achieve the effect of interface evaporation.
[0023] (2) Using a hydrophilic polymer as a matrix, the synergistic effect of photothermal materials and alumina (Al2O3) fibers endows the porous interface photothermal evaporation material with photothermal conversion function and good wicking properties. During the evaporation process, due to the wicking effect of Al2O3 fibers and the hydrophilicity of the hydrophilic polymer matrix, seawater is continuously supplied to the surface of the porous interface photothermal evaporation material. The photothermal materials on the surface and inside of the porous interface photothermal evaporation material absorb light energy and convert it into heat energy. The Al2O3 fibers are oriented along the photothermal evaporation direction and are relatively uniformly distributed. The uniformly arranged Al2O3 fibers connect the photothermal materials to make the entire photothermal conversion more uniform, thereby heating the seawater supplied to the surface of the material and causing it to evaporate rapidly. Attached Figure Description
[0024] Figure 1 This is a flowchart illustrating the preparation process of the porous interfacial photothermal evaporation material in Example 1.
[0025] Figure 2 This is a schematic diagram of the interfacial photothermal evaporator in Example 1;
[0026] Figure 3 SEM images of the porous interfacial photothermal evaporation materials of Comparative Examples 1-2 and Example 1;
[0027] Figure 4 SEM images of the porous interfacial photothermal evaporation materials of Example 1 and Comparative Example 3;
[0028] Figure 5 This is a schematic diagram of the structure of the simulated evaporation testing device of the present invention;
[0029] Figure 6 The figures show the evaporation test results for pure simulated seawater solution, the examples, and the comparative examples.
[0030] Among them, 1 is a porous interfacial photothermal evaporation material and 2 is a floating layer. Detailed Implementation
[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0032] Example 1
[0033] The flowchart of the preparation method of the porous interface photothermal evaporation material in this embodiment is shown below. Figure 1 As shown, it is prepared by the following method:
[0034] (1) Dissolve 1.5g of cellulose acetate in 10ml of N,N-dimethylformamide (DMF), and add 0.16g of carbon nanotubes (CNTs) and 0.6g of Al2O3 fiber at the same time. Stir and dissolve at room temperature for 8h until completely dissolved to obtain a mixed solution; wherein the length of the alumina fiber is 0.8mm and the diameter is 16μm.
[0035] (2) The mixed solution obtained in step (1) is subjected to degassing treatment to obtain a homogeneous and transparent solution; wherein, the degassing treatment method is ultrasonic treatment, and after ultrasonic treatment, it is left to stand at 80°C for 10 min.
[0036] (3) The homogeneous and transparent solution obtained in step (2) was stirred at 80°C and 15 ml of n-hexanol was added dropwise. The mixture was then heated and stirred at 80°C for 3 h to obtain a blend solution. The concentration of cellulose acetate in the blend solution was 60 mg / mL. The mass ratio of cellulose acetate, carbon nanotubes and alumina fibers was 1.5:0.16:0.6. The volume percentage of DMF to n-hexanol was 40%:60%.
[0037] (4) After sealing the blended solution obtained in step (3), phase separation was carried out at 25°C for 30 min to obtain the initial solidified solid.
[0038] (5) The nascent solid obtained in step (4) is placed in a constant temperature shaker at 20°C for washing. Excess DMF and n-hexanol are replaced with methanol. The washing is repeated 3 times, with an interval of 6 hours between each wash, to obtain a porous interface photothermal evaporation material.
[0039] The thickness of the porous interfacial photothermal evaporation material in this embodiment is 0.5 mm.
[0040] The interfacial photothermal evaporator of this embodiment is prepared by the following method:
[0041] The porous interfacial photothermal evaporation material 1 is embedded in the through-holes of the floating layer 2. The thickness of the floating layer is 1 mm. The bottom surface of the porous interfacial photothermal evaporation material 1 is flush with the bottom surface of the floating layer 2. The structure is as follows: Figure 2 As shown, an interfacial photothermal evaporator is obtained. The interfacial photothermal evaporator is as follows... Figure 2 As shown, Figure 2 The left image shows the top surface of the interfacial photothermal evaporator. Figure 2 The right figure shows the bottom surface of the interfacial photothermal evaporator.
[0042] Comparative Example 1
[0043] Same as Example 1, except that:
[0044] In the preparation method of the porous interfacial photothermal evaporation material in this comparative example, step (1) involves dissolving 1.5g of cellulose acetate in 10ml of DMF and stirring at room temperature for 8 hours until completely dissolved to obtain a mixed solution.
[0045] Comparative Example 2
[0046] Same as Example 1, except that:
[0047] In the preparation method of the porous interfacial photothermal evaporation material in this comparative example, step (1) involves dissolving 1.5g of cellulose acetate in 10ml of DMF and adding 0.16g of CNTs. The mixture is stirred and dissolved at room temperature for 8 hours until it is completely dissolved, resulting in a mixed solution.
[0048] Comparative Example 3
[0049] The porous interfacial photothermal evaporation material in this comparative example was prepared by the following method:
[0050] (1) Dissolve 1.5g of cellulose acetate in 10ml of N,N-dimethylformamide (DMF) and stir at room temperature for 8h until completely dissolved to obtain a mixed solution;
[0051] (2) The mixed solution obtained in step (1) is subjected to ultrasonic dispersion treatment, and then degassed by standing at 80°C for 10 min to obtain a homogeneous and transparent solution.
[0052] (3) The homogeneous and transparent solution obtained in step (2) was stirred at 80°C and 15 ml of n-hexanol was added dropwise. At the same time, 0.16 g of CNTs and 0.6 g of Al2O3 fiber were added. The mixture was heated and stirred at 80°C for 3 h to obtain a blend solution.
[0053] (4) After sealing the blended solution obtained in step (3), phase separation was carried out at 25°C for 30 min to obtain the initial solidified solid.
[0054] (5) The nascent solid obtained in step (4) is placed in a constant temperature shaker at 20°C for washing. DMF and n-hexanol are washed out with methanol. The washing is repeated 3 times with an interval of 6 hours each time to obtain a porous interface photothermal evaporation material.
[0055] The porous interfacial photothermal evaporation materials of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were analyzed by scanning electron microscopy (SEM).
[0056] Figure 3 The images shown are SEM images of Example 1, Comparative Example 1, and Comparative Example 2 at the same magnification. Figure 3 (a) is Comparative Example 1; Figure 3 (b) is Comparative Example 2; Figure 3 (c) is Example 1. By comparison, it can be seen that the alumina fiber connects CNTs in the cross-sectional morphology of the porous interfacial photothermal evaporation material of Example 1.
[0057] Figure 4 These are SEM images of Example 1 and Comparative Example 3 at the same magnification, where... Figure 4 (a) is Example 1; Figure 4 (b) is Comparative Example 3. It can be seen that in Example 1, the alumina fibers are oriented and relatively uniformly distributed along the photothermal evaporation direction, while in Comparative Example 1, the alumina fibers are oriented and relatively randomly. This is because the present invention involves adding a hydrophilic polymer to a good solvent, simultaneously adding a photothermal material and Al2O3 fibers, and then adding a poor solvent for phase separation. During the phase separation process, the Al2O3 fibers are oriented and uniformly arranged. In practical applications, the oriented arrangement of Al2O3 fibers along the photothermal evaporation direction can further improve the transfer of water molecules along the fiber bundle axis and promote the evaporation rate. This solves the problem of low photothermal conversion efficiency caused by the non-oriented arrangement of Al2O3 fibers after adding a poor solvent and then adding the photothermal material and Al2O3 fibers.
[0058] The interfacial photothermal evaporators of Examples 1, 1, 2, and 3, along with a pure simulated seawater solution, were used for simulated evaporation tests. The test setup is shown in the diagram. Figure 5 As shown, the interfacial photothermal evaporator floated on a 3.5 wt% simulated seawater solution. A xenon lamp was used to simulate sunlight, and the lamp intensity was corrected to one solar intensity to simulate seawater evaporation. Weight changes were recorded using an analytical balance, and the evaporation test results are shown below. Figure 6 As shown in the figure, the change in evaporation mass over time is as follows: Figure 6 As shown in (a), the seawater evaporation rate diagram is as follows: Figure 6 As shown in (b), the change in evaporation mass is the initial mass minus the current mass, and the evaporation rate is the mass of water vapor evaporated per unit area per unit time. The evaporation rates of the interfacial photothermal evaporators in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 are 1.804 kg / h·m. 2 0.612 kg / h·m 2 1.488 kg / h·m 2 1.579 kg / h·m 2This indicates that the porous interfacial photothermal evaporation material formed by Al2O3 fibers and CNTs doped with cellulose acetate in Example 1 improved the seawater evaporation rate by adding CNTs. In order to improve the seawater evaporation rate of the porous photothermal conversion material using CNTs as the photothermal material, the addition of Al2O3 fibers significantly improved the seawater evaporation rate. The Al2O3 fibers act as a wicking agent, enhancing the photothermal conversion. At the same time, as a connecting medium for CNTs, the Al2O3 fibers connect the CNTs, making the entire photothermal conversion more uniform, thereby allowing the seawater supplied to the material surface to be heated and evaporate rapidly.
[0059] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.
Claims
1. A method of preparing a porous interfacial photo-thermal evaporation material, characterized in that, The preparation method comprises the following steps: (1) dissolving a hydrophilic polymer in a good solvent, while adding a photothermal material and alumina fibers, stirring and dissolving at a temperature below 40℃ until complete dissolution, to obtain a mixed solution; the mass ratio of the hydrophilic polymer, the photothermal material and the alumina fibers is 0.8-1.5:0.16-0.35:0.6-1.2; the hydrophilic polymer is selected from cellulose acetate; the photothermal material is carbon nanotubes; the length of the alumina fibers is 0.5-1 mm, and the diameter is 14-17 μm; (2) performing defoaming treatment on the mixed solution obtained in step (1) to obtain a uniform transparent solution; (3) stirring and adding a poor solvent to the uniform transparent solution obtained in step (2) at a temperature of 60-90℃, and continuing to heat and stir at a temperature of 60-90℃ to obtain a blended solution; (4) performing phase separation on the blended solution obtained in step (3) at a temperature of 5-30℃ after sealing to obtain a nascent coagulum; (5) performing washing on the nascent coagulum obtained in step (4) to replace the excess good solvent and poor solvent, to obtain a porous interfacial photothermal evaporation material.
2. The method of claim 1, wherein, In step (1), the good solvent is selected from N,N-dimethylformamide, N,N-dimethylacetamide, acetone, dichloromethane, tetrahydrofuran or dimethyl sulfoxide.
3. The method of claim 1, wherein, In step (2), the method for defoaming treatment is selected from ultrasonic treatment, reduced pressure standing or adding a defoaming agent.
4. The method of claim 1, wherein, In step (3), the poor solvent is selected from n-hexanol, isohexyl alcohol, octanediol or water.
5. The method of claim 1, wherein, In step (5), the solvent used for washing is methanol or ethanol.
6. The method of claim 1, wherein, The concentration of the hydrophilic polymer in the blended solution is 60-120 mg / mL; and the volume percentage of the good solvent and the poor solvent is 36%-44%:56%-64%.
7. The porous interfacial photothermal evaporation material prepared by the preparation method in any one of claims 1-6.
8. The application of the porous interfacial photothermal evaporation material in claim 7 in an interfacial photothermal evaporator.