Cellulose composite for light-heat conversion and method for preparing the same
By using hydrophobic modification through hydrogen bonding between polyvinyl alcohol and nanocellulose and doping with acidified carbon nanotubes, a low-cost and high-efficiency cellulose composite material was prepared, solving the problems of high cost and insufficient strength of photothermal materials, and achieving excellent photothermal conversion performance and seawater desalination applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI SNOW DRAGON FIBER TECH CO LTD
- Filing Date
- 2026-03-13
- Publication Date
- 2026-06-05
AI Technical Summary
Existing photothermal materials are expensive, have poor biodegradability, and face challenges in matching material strength with water transport and heat transfer rates during seawater desalination, making large-scale application difficult.
Cellulose-based aerogels were prepared by forming strong hydrogen bonds between polyvinyl alcohol and nanocellulose, combined with methoxysilane modification with hydrophobic chains and acidified carbon nanotube doping, forming a stable Si-OC bond and hydrogen bond network, thereby improving the hydrophobicity and mechanical properties of the material.
It achieves low-cost and high-efficiency photothermal conversion performance. The material has excellent light absorption, heat conversion ability and mechanical properties in seawater desalination, and is suitable for large-scale production.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of photothermal conversion materials technology, specifically relating to a cellulose composite material for photothermal conversion and its preparation method. Background Technology
[0002] Photothermal materials are a new type of functional material that can convert light energy into heat energy under illumination. They are widely used in fields such as solar desalination and energy conversion. Common photothermal materials mainly include: metallic materials, semiconductor materials, carbon-based materials, and composite materials.
[0003] However, most existing photothermal materials suffer from high manufacturing costs, poor biodegradability, and potential pollution to aquatic environments. While metallic materials such as gold, silver, uranium, palladium, and some semiconductor materials possess excellent photothermal properties, their high cost and scarcity limit large-scale applications. Common carbon-based materials include biomass, graphite, carbon black, carbon nanotubes, and their derivatives. Although they exhibit good light absorption and thermal conductivity, their manufacturing costs are high, and the structure of natural raw materials restricts the optimization and control of material performance. Furthermore, when photothermal materials are used in seawater desalination, they need to be immersed in seawater for extended periods. The electrochemical corrosion of some common transition metals in saline seawater can affect their lifespan. Additionally, porous water-transfer insulation materials used in conjunction with the light-absorbing layer in photothermal conversion materials, such as polystyrene foam, are difficult to biodegrade, and long-term, large-scale use can also pollute water bodies. While carbonized light-absorbing materials made from natural raw materials such as wood, mushrooms, bamboo, lotus leaves, and radishes are pollution-free and biodegradable, their structure, performance, and scale are often limited by the structure of the natural raw materials themselves. It is difficult to achieve optimal control of the material structure and performance, making it difficult to solve the problem of matching water transport and heat transfer rates.
[0004] Cellulose is an abundant and biodegradable green material, thus possessing great potential for the preparation of novel environmentally friendly photothermal conversion materials. However, due to the strong hydrophilicity of nanocellulose, and since the strength of cellulose materials depends on the strength of hydrogen bonds, when applied to seawater desalination, a large amount of water will inevitably disrupt these hydrogen bonds, significantly affecting the material's strength.
[0005] Therefore, developing a low-cost, structurally controllable, and highly efficient photothermal conversion material has become an urgent technical problem to be solved in the field of solar desalination materials. Summary of the Invention
[0006] The purpose of this invention is to provide a cellulose composite material for photothermal conversion and its preparation method, so as to solve the problems of high cost and low photothermal conversion efficiency of common photothermal materials in the prior art.
[0007] The objective of this invention can be achieved through the following technical solutions: A method for preparing a cellulose composite material for photothermal conversion includes the following steps: Step 1: Add polyvinyl alcohol and nanocellulose to deionized water and mix. Stir and react for 2.0-2.5 hours. Adjust the pH value, add methoxysilane solution, and stir and react for 5.0-6.0 hours to obtain a premixed solution. Step 2: Add acidified carbon nanotubes and deionized water to the premixed solution obtained in Step 1, disperse by ultrasonication until uniform, heat to 80-90℃ and stir for 5.0-6.0 h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20 to -15°C for 15 to 30 minutes, then freeze-dry it in a freeze dryer under vacuum. After drying, the cellulose composite material is obtained.
[0008] Furthermore, in step 1, the amounts of polyvinyl alcohol, nanocellulose, deionized water, and methoxysilane are 6.0–6.2 g: 3.0–3.5 g: 200 mL: 3–5 mL.
[0009] Furthermore, in step 1, the pH value is adjusted to 4.0–4.2.
[0010] Furthermore, the preparation steps of the methoxysilane solution in step 1 are as follows: Add methoxysilane to deionized water, adjust the pH to 4.0-4.2, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution; wherein the ratio of methoxysilane to deionized water is 6.0-6.5 g: 80 mL.
[0011] Furthermore, the methoxysilane is one of ethyltrimethoxysilane, dodecyltrimethoxysilane, and octadecyltrimethoxysilane. The use of silanes with hydrophobic chains of a certain length to hydrophobize nanocellulose polyvinyl alcohol aerogel imparts excellent hydrophobic properties to the aerogel. Under acidic conditions, the methoxysilane can hydrolyze into a polymer with silanol groups (Si-OH) and hydrophobic chains of a certain length, which can form hydrogen bonds with the hydroxyl groups on the surface of polyvinyl alcohol and nanocellulose, forming a mixed network and improving the hydrophobic and mechanical properties of the cellulose-based aerogel.
[0012] Furthermore, in step 2, the preparation steps of the acidified carbon nanotubes are as follows: Carbon nanotubes were added to HNO3 and H2SO4, ultrasonically dispersed until uniform, heated to 60℃ and stirred under reflux for 4.0 h, cooled to room temperature, diluted and stirred, centrifuged and washed, filtered and vacuum dried to obtain acidified carbon nanotubes.
[0013] Furthermore, the ratio of carbon nanotubes, HNO3, and H2SO4 used is 2.0–3.0 g: 40 mL: 120 mL.
[0014] Furthermore, in step 2, the amounts of acidified carbon nanotubes, deionized water, and premixed solution are 0.1–0.2 g: 10 mL: 50 mL.
[0015] Furthermore, in step 3, the freeze-drying temperature is -60 to -50°C, and the freeze-drying time is 44 to 48 hours. The control of freeze-drying temperature and time has a significant impact on the final properties of the cellulose composite material. Freeze-drying at -60 to -50°C for 44 to 48 hours ensures a uniform internal structure of the cellulose-based aerogel, exhibiting high porosity and a uniform pore size distribution, effectively protecting the microstructure of the aerogel.
[0016] The present invention also provides a cellulose composite material for photothermal conversion, which is prepared by the above steps.
[0017] The beneficial effects of this invention are: This invention first prepares cellulose-based aerogels using polyvinyl alcohol (PVA) and nanocellulose. PVA can form strong interactions with nanocellulose: the negative charge on the surface of nanocellulose interacts with the positive charge on the surface of PVA, and the hydroxyl groups on the surface of nanocellulose can form hydrogen bonds with the hydroxyl groups on the surface of PVA. These strong hydrogen bonds improve the mechanical properties, toughness, and structural stability of the cellulose-based aerogel. However, because the surface of the cellulose-based aerogel contains a large number of hydrophilic groups, when applied to seawater desalination, a large amount of water will inevitably disrupt these hydrogen bonds, significantly affecting the material's strength. Therefore, this invention further modifies the cellulose-based aerogel with methoxysilanes, which have long hydrophobic chains. After adding the hydrolyzed methoxysilane solution, the silanol groups react with the hydroxyl groups in nanocellulose and PVA to form Si-O-Si bonds. Furthermore, the hydrolysis product silanol undergoes a condensation reaction on the surfaces of nanocellulose and PVA to form a rigid polysiloxane with stable Si-O-Si bonds. This forms a rigid layer on the surface of the cellulose-based aerogel after subsequent freeze-drying, greatly improving the mechanical strength and structural stability of the cellulose material.
[0018] Furthermore, this invention incorporates acidified carbon nanotubes during the preparation of the cellulose composite material. Carbon nanotubes possess highly efficient light absorption capabilities, thus endowing the cellulose-based aerogel with excellent photothermal conversion performance. The incorporation of acidic carbon nanotubes into the cellulose-based aerogel network allows them to form hydrogen bonds with polyvinyl alcohol and nanocellulose molecular chains, ensuring excellent interfacial interactions. This effectively prevents carbon nanotubes from easily detaching from the aerogel, which would reduce the photothermal effect of the cellulose composite material. The uniform dispersion and abundant hydrogen bond network of acidic carbon nanotubes endow the cellulose-based aerogel with high solar energy absorption and high photothermal conversion efficiency; moreover, the incorporation of acidic carbon nanotubes can effectively improve the tensile strength, elastic modulus, and mechanical properties of the aerogel.
[0019] The cellulose composite material for photothermal conversion provided by this invention has excellent light absorption performance, photothermal conversion performance and mechanical properties, and also has the characteristics of low cost, high stability and low pollution, showing great potential in seawater desalination.
[0020] The present invention provides a simple method for preparing a cellulose composite material for photothermal conversion, which uses readily available raw materials, is cost-effective, and is suitable for large-scale production. Detailed Implementation
[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, modifications to design, manufacturing, or production based on the disclosed technical content are merely conventional technical means and should not be construed as insufficient disclosure. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Moreover, the following description is provided to enable those skilled in the art to fully understand this application and is not intended to limit the subject matter of the claims.
[0023] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions, and all technical features and optional technical features of this application can be combined to form new technical solutions.
[0024] Example 1
[0025] This embodiment provides a preparation step for acidified carbon nanotubes as follows: 2.0 g of carbon nanotubes were added to 40 mL of HNO3 and 120 mL of H2SO4 and ultrasonically dispersed until uniform. The mixture was heated to 60 °C and stirred under reflux for 4.0 h. After cooling to room temperature, deionized water was added for dilution and stirring was continued in an ice bath. The mixture was centrifuged and repeatedly washed with deionized water until the supernatant was neutral. After filtration, the mixture was placed in a vacuum drying oven at 80 °C and dried for 24 h to obtain acidified carbon nanotubes.
[0026] The acidified carbon nanotubes used in other embodiments and comparative examples of this invention were all prepared in this embodiment.
[0027] Example 2
[0028] This embodiment provides a cellulose composite material for photothermal conversion and its preparation method: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.0g of polyvinyl alcohol and 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0029] The preparation steps of the methoxysilane solution are as follows: Add 6.0 g of ethyltrimethoxysilane to 80 mL of deionized water, adjust the pH to 4.0, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution.
[0030] The cellulose composite material for photothermal conversion is prepared by the above steps.
[0031] Example 3
[0032] Compared to Example 2, the only difference is that the preparation process in step 1 is different: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.2g of polyvinyl alcohol and 3.5g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0033] The preparation steps of the methoxysilane solution are as follows: Add 6.0 g of ethyltrimethoxysilane to 80 mL of deionized water, adjust the pH to 4.0, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution.
[0034] Example 4
[0035] Compared to Example 2, the only difference is that the preparation process in step 2 is different: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.0g of polyvinyl alcohol and 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.2g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0036] The preparation steps of the methoxysilane solution are as follows: Add 6.0 g of ethyltrimethoxysilane to 80 mL of deionized water, adjust the pH to 4.0, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution.
[0037] Example 5
[0038] The only difference from Example 2 is that the preparation process in step 3 is different: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.0g of polyvinyl alcohol and 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -55℃ under vacuum for 46 hours. After drying, the cellulose composite material is obtained.
[0039] The preparation steps of the methoxysilane solution are as follows: Add 6.0 g of ethyltrimethoxysilane to 80 mL of deionized water, adjust the pH to 4.0, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution.
[0040] Example 6
[0041] The only difference from Example 2 is the preparation process of the methoxysilane solution: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.0g of polyvinyl alcohol and 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0042] The preparation steps of the methoxysilane solution are as follows: Add 6.3g of dodecyltrimethoxysilane to 80mL of deionized water, adjust the pH to 4.0, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution.
[0043] Example 7
[0044] Compared with Example 2, the only difference is that the preparation processes in steps 1-2 are different: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.1g of polyvinyl alcohol and 3.2g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.5h. Adjust the pH to 4.2 with hydrochloric acid solution (concentration of 0.1mol / L). Add 4mL of methoxysilane solution and stir and react for 5.0h to obtain the premixed solution. Step 2: Add 0.15g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 90℃ and stir for 5.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0045] The preparation steps of the methoxysilane solution are as follows: Add 6.0 g of ethyltrimethoxysilane to 80 mL of deionized water, adjust the pH to 4.2, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution.
[0046] Example 8
[0047] Compared with Example 2, the only difference is that the preparation processes in steps 1-3 are different: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.2g of polyvinyl alcohol and 3.5g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.5h. Adjust the pH to 4.2 with hydrochloric acid solution (concentration of 0.1mol / L). Add 5mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.15g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 85℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -15℃ for 20 minutes, and then freeze-dry it in a freeze dryer at -50℃ under vacuum for 48 hours. After drying, the cellulose composite material is obtained.
[0048] The preparation steps of the methoxysilane solution are as follows: Add 6.0 g of ethyltrimethoxysilane to 80 mL of deionized water, adjust the pH to 4.0, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution.
[0049] Comparative Example 1
[0050] Compared to Example 2, the only difference is that in step 1, polyvinyl alcohol and methoxysilane solution are not added; that is, only nanocellulose is used. The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L) and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0051] Comparative Example 2
[0052] The only difference from Example 2 is that polyvinyl alcohol is not added in step 1: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0053] The preparation steps of the methoxysilane solution are as follows: Add 6.0 g of ethyltrimethoxysilane to 80 mL of deionized water, adjust the pH to 4.0, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution.
[0054] Comparative Example 3
[0055] The only difference from Example 2 is that no methoxysilane solution is added in step 1: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.0g of polyvinyl alcohol and 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L) and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0056] Comparative Example 4
[0057] Compared to Example 2, the only difference is that the preparation process in step 1 is different: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 5.5g of polyvinyl alcohol and 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0058] Comparative Example 5
[0059] Compared to Example 2, the only difference is that the preparation process in step 2 is different: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.0g of polyvinyl alcohol and 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.05g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -60℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0060] Comparative Example 6
[0061] The only difference from Example 2 is that the preparation process in step 3 is different: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 6.0g of polyvinyl alcohol and 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 50mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -70℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0062] Comparative Example 7
[0063] The only difference from Example 2 is the preparation process of the methoxysilane solution: The preparation steps of the methoxysilane solution are as follows: Add 5.0 g of ethyltrimethoxysilane to 80 mL of deionized water, adjust the pH to 4.0, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution.
[0064] Comparative Example 8
[0065] Compared with Example 2, the only difference is that the preparation processes in steps 1-3 are different: The preparation steps of a cellulose composite material for photothermal conversion are as follows: Step 1: Add 5.5g of polyvinyl alcohol and 3.0g of nanocellulose to 200mL of deionized water and mix. Stir and react for 2.0h. Adjust the pH to 4.0 with hydrochloric acid solution (concentration of 0.1mol / L). Add 3mL of methoxysilane solution and stir and react for 6.0h to obtain the premixed solution. Step 2: Add 0.1g of acidified carbon nanotubes and 10mL of deionized water to 80mL of the premixed solution obtained in Step 1, disperse it by ultrasonication until uniform, heat it to 80℃ and stir for 6.0h to obtain a mixed solution; Step 3: Pour the mixed solution obtained in Step 2 into a polytetrafluoroethylene mold container, freeze the container at -20℃ for 15 minutes, and then freeze-dry it in a freeze dryer at -80℃ under vacuum for 44 hours. After drying, the cellulose composite material is obtained.
[0066] The performance of the cellulose composite materials obtained in Examples 2-8 and Comparative Examples 1-8 was tested: (1) Evaporation efficiency test: The cellulose composite material was placed in a 3.5% salt solution (the average salt concentration of seawater in China) for evaporation test. The temperature was controlled at 20℃ and the relative humidity was controlled at 40%. A xenon lamp was used as sunlight to detect the change in water mass during the evaporation process. Data was recorded every 3 minutes until the evaporation was completed. All results were the average of 3 experiments. The evaporation rate and evaporation efficiency were calculated.
[0067] (2) Rebound performance test: At room temperature, a cellulose composite material with a diameter of 21 mm and a height of 23 mm was compressed to 80% of its original size and height using a 200 g weight. The percentage of the height of the cellulose composite material after the 200 g weight was removed was the initial compression rebound rate. Based on this, 50 compression and rebound cycles were performed. The percentage of the height of the cellulose composite material after the 200 g weight was removed after 50 cycles was the compression rebound rate after 50 cycles.
[0068] The test results are shown in Table 1: Table 1
[0069] As can be seen from the data in Table 1, compared with the cellulose composite materials obtained in Comparative Examples 1-8, the cellulose composite materials obtained in Examples 2-8 have superior evaporation rates and evaporation efficiencies. This indicates that the fiber composite material provided by this invention can achieve efficient photothermal conversion and efficient seawater desalination. Simultaneously, the cellulose composite material prepared in this invention possesses excellent mechanical properties, thus enabling it to exist stably in seawater and other water bodies without being crushed. The cellulose composite material for photothermal conversion provided by this invention has excellent light absorption performance, photothermal conversion performance, and mechanical properties. It also features low cost, high stability, and low pollution, showing great potential in seawater desalination. Furthermore, the preparation method is simple, the raw materials are readily available, and it is suitable for large-scale production.
[0070] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
[0071] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. It should be understood that, in the various embodiments of this application, the sequence number of each process does not imply a sequential order of execution; some or all steps may be performed in parallel or sequentially; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0072] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application are available on the market or can be prepared by existing methods.
[0073] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions, and all technical features and optional technical features of this application can be combined to form new technical solutions.
[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a cellulose composite material for photothermal conversion, characterized in that, Includes the following steps: Step 1: Add polyvinyl alcohol and nanocellulose to deionized water and mix. Stir and react for 2.0-2.5 hours. Adjust the pH value, add methoxysilane solution, and stir and react for 5.0-6.0 hours to obtain a premixed solution. Step 2: Add acidified carbon nanotubes and deionized water to the premixed solution, disperse by ultrasonication until uniform, heat to 80-90℃ and stir for 5.0-6.0 h to obtain a mixed solution; Step 3: Pour the mixed solution into a polytetrafluoroethylene mold container, freeze the container at -20 to -15°C for 15 to 30 minutes, then freeze-dry it in a freeze dryer under vacuum. After drying, the cellulose composite material is obtained.
2. The method for preparing a cellulose composite material for photothermal conversion according to claim 1, characterized in that, In step 1, the amounts of polyvinyl alcohol, nanocellulose, deionized water, and methoxysilane are 6.0–6.2 g: 3.0–3.5 g: 200 mL: 3–5 mL.
3. The method for preparing a cellulose composite material for photothermal conversion according to claim 1, characterized in that, In step 1, adjust the pH value to 4.0–4.
2.
4. The method for preparing a cellulose composite material for photothermal conversion according to claim 1, characterized in that, The preparation steps of the methoxysilane solution in step 1 are as follows: Add methoxysilane to deionized water, adjust the pH to 4.0-4.2, and stir until the silane is fully hydrolyzed to obtain a methoxysilane solution; wherein the ratio of methoxysilane to deionized water is 6.0-6.5 g: 80 mL.
5. The method for preparing a cellulose composite material for photothermal conversion according to claim 4, characterized in that, The methoxysilane is one of ethyltrimethoxysilane, dodecyltrimethoxysilane, and octadecyltrimethoxysilane.
6. The method for preparing a cellulose composite material for photothermal conversion according to claim 1, characterized in that, In step 2, the preparation steps of the acidified carbon nanotubes are as follows: Carbon nanotubes were added to HNO3 and H2SO4, ultrasonically dispersed until uniform, heated to 60℃ and stirred under reflux for 4.0 h, cooled to room temperature, diluted and stirred, centrifuged and washed, filtered and vacuum dried to obtain acidified carbon nanotubes.
7. The method for preparing a cellulose composite material for photothermal conversion according to claim 6, characterized in that, The ratio of carbon nanotubes, HNO3 and H2SO4 used is 2.0-3.0 g: 40 mL: 120 mL.
8. The method for preparing a cellulose composite material for photothermal conversion according to claim 1, characterized in that, In step 2, the amounts of acidified carbon nanotubes, deionized water, and premixed solution are 0.1–0.2 g: 10 mL: 50 mL.
9. The method for preparing a cellulose composite material for photothermal conversion according to claim 1, characterized in that, In step 3, the freeze-drying temperature is -60 to -50°C, and the freeze-drying time is 44 to 48 hours.
10. A cellulose composite material for photothermal conversion, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.