Preparation method and application of photothermal / magnetothermal coupling effect fiber aerogel

Abstract

The present invention discloses a preparation method and application of a fiber aerogel with a photothermal / magnetothermal coupling effect, comprising: (1) preparing ultrafine fibers with a three-dimensional layered array structure by using a solution jet spinning technique to obtain a fiber aerogel matrix; (2) immersing the fiber aerogel matrix in a Tris-HCl buffer solution, adding dopamine hydrochloride and polyethyleneimine, and shaking the fiber aerogel matrix; (3) freeze-drying the fiber aerogel matrix for 24 hours to obtain a hydrophilically modified fiber aerogel matrix; (4) dissolving a polydimethylsiloxane prepolymer in ethyl acetate to obtain a mixed solution; (5) adding ferroferric oxide nanopowder and tin selenide nanopowder to the mixed solution to obtain a modified solution; (6) dipping any surface of the fiber aerogel matrix into the modified solution to form a photothermal / magnetothermal modified layer on the surface of the fiber aerogel matrix; and (7) drying the fiber aerogel matrix in an oven. The method has high efficiency, good stability, and high desalination capacity, and can realize all-weather continuous operation of seawater desalination.

Description

Technical Field

[0001] The present invention belongs to the technical field of seawater desalination, and in particular relates to a preparation method and application of a photothermal / magnetothermal coupling effect fiber aerogel. Background Art

[0002] Seawater is one of the most abundant water resources on Earth. The use of seawater desalination technology can effectively solve the problem of freshwater shortage, especially in arid areas or island areas where freshwater resources are scarce. Water shortage has become one of the bottlenecks restricting economic and social development.

[0003] Interfacial solar energy is a technology that uses solar energy for energy conversion and is commonly used in areas such as desalination, water treatment, and energy generation. Its principle is to use solar energy to heat water or other liquids to boiling point, causing them to evaporate and separating pure water vapor, thereby purifying water or desalinating seawater. In recent years, interfacial solar energy technology has garnered widespread attention and research, demonstrating its significance in addressing water shortages and desalination. Continuous improvements in the materials and structural design of interfacial solar energy systems can enhance their solar energy utilization efficiency and water purification performance, thereby promoting the development and widespread adoption of this technology in practical applications. Due to the increasing global population, the steady modernization of society, and climate change leading to more frequent extreme droughts, existing freshwater resources are significantly insufficient, making water security a top priority. Furthermore, the growing global demand for water is hindering sustainable development. Desalination technology is an effective solution for obtaining freshwater. It can also alleviate water resource pressure, reduce the pressure on overexploitation of groundwater and other freshwater resources, and contribute to the protection and sustainable use of groundwater resources.

[0004] It can be seen that interfacial solar evaporation technology has become one of the effective strategies to solve the freshwater crisis. However, since sunlight is easily affected by weather and time, this will affect the continued progress of seawater desalination. Therefore, it is very important to build an evaporation structure for seawater desalination that has high efficiency, good stability, high desalination capacity, and can operate continuously around the clock. In interfacial solar systems, some materials or devices are usually used as interfacial evaporators to absorb solar energy and convert it into thermal energy, thereby promoting liquid evaporation. These interfacial evaporators usually have good photothermal performance and can efficiently absorb solar energy and convert it into thermal energy, thereby achieving water evaporation and purification.

[0005] Compared to traditional two-dimensional materials for photothermal desalination, three-dimensional porous materials can effectively transport water upward and also have good salt removal performance due to their adjustable pore structure, large specific surface area and multifunctionality. However, most current three-dimensional directional transport structures are usually prepared by using directional freezing aerogels or 3D printing, such as the following patented technologies:

[0006] CN108862443A discloses a gold nanoparticle / graphene three-dimensional photothermal conversion material and its uses. Gold nanoparticles and graphene are chemically assembled into a gold nanoparticle / graphene nanocomposite material, which is then directional freeze-dried to form a gold nanoparticle / graphene three-dimensional photothermal (steam) conversion material. This material efficiently converts light energy into heat energy, rapidly heating water to steam, ultimately achieving water purification, thereby realizing multiple functions such as seawater desalination, fractionation, sterilization, and sewage treatment.

[0007] CN117326615A discloses a three-dimensional heterogeneous evaporator, its preparation method, and application. Current solar desalination evaporators can only operate at relatively low evaporation rates. This invention uses existing 3D printing technology to prepare a new three-dimensional heterogeneous evaporator for the first time. It consists of two parts: rGO-TiN and rGO-F127 as evaporation interfaces, and rGO as a water transmission path. The difference in mass transfer capacity between the two ultimately leads to stable water-salt co-production. The evaporator of the present invention can stably desalinate 20wt% NaCl at an evaporation rate of 8.75kg·m-2·h-1, and the salt production rate reaches 1.02kg·m-2·h-1 (within 1 hour). This work provides a new method for zero liquid discharge of high-concentration brine driven by solar energy.

[0008] From the above technologies, it can be seen that due to the cumbersome process, high energy consumption and long time consumption of 3D printing technology and directional freeze-drying technology, the cost of aerogel is greatly increased, which seriously hinders its mass production. It can be seen that it is not suitable for large-scale industrial application. In addition, solar thermal desalination is limited by the light intensity affected by climate and region, and it is impossible to achieve continuous and uninterrupted desalination. Therefore, how to make up for the lack or absence of sunlight on the basis of solar thermal desalination, and how to assist in improving the photothermal conversion efficiency when sunlight is insufficient, and still have a high seawater desalination capacity in the absence of sunlight, so as to achieve continuous and uninterrupted desalination, has become a difficult problem that technicians in the field of seawater desalination urgently need to solve. Summary of the Invention

[0009] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is to provide a preparation method and application of a photothermal / magnetothermal coupling effect fiber aerogel with high efficiency, good stability and high desalination capacity, which can realize continuous operation of seawater desalination around the clock.

[0010] To solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a fiber aerogel with photothermal / magnetothermal coupling effect, comprising the following steps:

[0011] 1. Preparation of fiber aerogel matrix:

[0012] (1) preparing a spinning solution, using a solution jet spinning technique to prepare ultrafine fibers with a three-dimensional layered array structure, and performing a pre-oxidation treatment to obtain a fiber aerogel matrix;

[0013] 2. Hydrophilic modification:

[0014] (2) Immerse the fiber aerogel matrix obtained in step (1) in a Tris-HCl buffer solution of a certain concentration, add dopamine hydrochloride and polyethyleneimine in sequence, and shake continuously at 40°C for 6-10 hours in a dark and sealed condition;

[0015] (3) freeze-drying the fiber aerogel matrix after step (2) for 24 hours to obtain a hydrophilically modified fiber aerogel matrix;

[0016] 3. Photothermal / magnetic thermal modification:

[0017] (4) dissolving a certain amount of polydimethylsiloxane prepolymer in ethyl acetate, mixing uniformly to obtain a mixed solution for later use;

[0018] (5) adding ferroferric oxide nanopowder and tin selenide nanopowder into the mixed solution, and uniformly dispersing them by ultrasonic vibration to obtain a modified solution;

[0019] (6) dipping any one surface of the fiber aerogel matrix obtained in step (3) into the modification solution and performing an immersion deposition treatment to form a photothermal / magnetic thermal modification layer on the surface of the fiber aerogel matrix;

[0020] 4. Curing treatment:

[0021] (7) The fiber aerogel matrix impregnated and deposited in step (4) is placed in an oven for drying to obtain a surface-modified fiber aerogel with photothermal / magnetothermal coupling effect.

[0022] In the above-mentioned method for preparing the photothermal / magnetocaloric coupling effect fiber aerogel, in step (1), the polyacrylonitrile concentration in the spinning solution for solution jet spinning is 13%-17%, and aluminum chloride hexahydrate is added in a mass ratio of 1:2-1:4 to obtain a spray-spinning precursor.

[0023] In the above-mentioned method for preparing the photothermal / magnetothermal coupling effect fiber aerogel, in step (2), the concentration of the Tris-HCl buffer solution is 1%-3%, and the mass concentrations of the added dopamine hydrochloride and polyethyleneimine are both 0.5-1.5 g / L.

[0024] In the above-mentioned method for preparing the photothermal / magnetothermal coupling effect fiber aerogel, in step (4), the concentration of the polydimethylsiloxane prepolymer in the mixed solution is 3%.

[0025] In the above-mentioned method for preparing the photothermal / magnetothermal coupling effect fiber aerogel, in step (5), the concentration of ferroferric oxide nanopowder and tin selenide nanopowder in the modified solution is 2%-5%, and the mass ratio of ferroferric oxide nanopowder to tin selenide nanopowder is 2:1-1:2.

[0026] In the above-mentioned method for preparing the photothermal / magnetothermal coupling effect fiber aerogel, the step (6) is to perform multiple dipping on any surface of the fiber aerogel matrix during the dipping and deposition process.

[0027] In the above-mentioned method for preparing the photothermal / magnetothermal coupling effect fiber aerogel, in the step (7), the oven drying temperature is 40°C.

[0028] In the above-mentioned method for preparing the photothermal / magnetocaloric coupling effect fiber aerogel, the surface-modified photothermal / magnetocaloric coupling effect fiber aerogel obtained in step (7) has a photothermal / magnetocaloric modified layer with a thickness of 4-7% of the total thickness of the fiber aerogel matrix.

[0029] The photothermal / magnetothermal coupling effect fiber aerogel prepared by the above preparation method is used as an interface evaporator in seawater desalination.

[0030] The advantages of the preparation method and application of the photothermal / magnetocaloric coupling effect fiber aerogel of the present invention are: a unique three-dimensional layered array structure water evaporator is prepared based on mass-producible spray-spinning technology, which has multi-scale, efficient water transmission channels with strong capillary forces. In addition to providing a large capillary force to effectively transport water upward and multiple refractions to improve the utilization of sunlight, the aerogel layered array structure has excellent anti-salting properties due to its super-hydrophobic surface. In addition, the efficient photothermal / magnetocaloric layer can efficiently desalinate seawater. By introducing Fe3O4 / SnSe into the three-dimensional layered evaporator produced by spray-spinning, the magnetocaloric photothermal effect is utilized. Under strong daylight conditions, the evaporator uses the photothermal effect to directly convert sunlight into heat energy for water evaporation; under poor daylight conditions or at night, the evaporator uses the magnetocaloric effect to convert heat energy into water evaporation, thereby achieving uninterrupted, continuous and efficient seawater desalination around the clock. Furthermore, this fiber aerogel, when used as an evaporator, exhibits excellent salt tolerance, high temperature resistance, chemical stability, good mechanical properties, and long-term operational stability, enabling continuous, all-weather water evaporation using alternating photothermal and magnetic thermal processes. These properties give it enormous potential for application in high-performance water purification and desalination. It not only provides a highly efficient interfacial evaporator but also offers a new development direction for high-performance water purification and desalination technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the preparation process of the fiber aerogel matrix of the present invention;

[0032] Figure 2 This is a physical picture of the photothermal / magnetothermal coupling effect fiber aerogel of the present invention;

[0033] Figure 3 This is the surface morphology electron microscope image of the fiber aerogel with photothermal / magnetothermal coupling effect;

[0034] Figure 4 This is an electron microscope magnified image of the surface morphology of fiber aerogel with photothermal / magnetothermal coupling effect;

[0035] Figure 5 This is a thermogravimetric comparison diagram of the photothermal / magnetothermal coupling effect fiber aerogel prepared in Example 3;

[0036] Figure 6 This is a comparison chart of the compression performance test of the photothermal / magnetothermal coupling effect fiber aerogel prepared in Example 3;

[0037] Figure 7 Schematic diagram of the evaporation rate of the photothermal / magnetothermal coupling effect fiber aerogel prepared in Examples 1-4 under photothermal heating conditions;

[0038] Figure 8 Schematic diagram of the evaporation rate of the photothermal / magnetothermal coupling effect fiber aerogel prepared in Examples 1-4 under magnetic heating conditions;

[0039] Figure 9 Schematic diagram of the water contact angle of the photothermal / magnetothermal coupling effect fiber aerogel prepared in Example 3;

[0040] Figure 10 Schematic diagram of the working principle of photothermal / magnetothermal coupling effect fiber aerogel used as an interfacial evaporator in seawater desalination. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] In this disclosure, unless otherwise indicated, directional terms such as "upper" and "lower" generally refer to the upper and lower parts of a device in actual use or operation, specifically in the directions of the drawings in the accompanying drawings; whereas "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "including" means "including but not limited to." Terms such as first, second, and third are used merely as designations and do not impose numerical requirements or establish a sequence. The term "plurality" means "two or more."

[0043] like Figure 1 、 2 As shown in Figures 3 and 4, a method for preparing a fiber aerogel with photothermal / magnetothermal coupling effect comprises the following steps:

[0044] 1. Preparation of fiber aerogel matrix:

[0045] (1) preparing a spinning solution, using a solution jet spinning technique to eject ultrafine fibers having a three-dimensional layered array structure through an air flow, and performing a pre-oxidation treatment to obtain a fiber aerogel matrix having a certain thickness;

[0046] 2. Hydrophilic modification:

[0047] (2) Immerse the fiber aerogel matrix obtained in step (1) in a Tris-HCl buffer solution of a certain concentration, add dopamine hydrochloride and polyethyleneimine in sequence, and shake continuously at 40°C for 6-10 hours in a dark and sealed condition;

[0048] (3) freeze-drying the fiber aerogel matrix after step (2) for 24 hours to obtain a hydrophilically modified fiber aerogel matrix;

[0049] 3. Photothermal / magnetic thermal modification:

[0050] (4) dissolving a certain amount of polydimethylsiloxane prepolymer in ethyl acetate, mixing uniformly to obtain a mixed solution for later use;

[0051] (5) adding ferroferric oxide nanopowder and tin selenide nanopowder into the mixed solution, and uniformly dispersing them by ultrasonic vibration to obtain a modified solution;

[0052] (6) dipping any one surface of the fiber aerogel matrix obtained in step (3) into the modification solution and performing an immersion deposition treatment to form a photothermal / magnetic thermal modification layer on the surface of the fiber aerogel matrix;

[0053] 4. Curing treatment:

[0054] (7) The fiber aerogel matrix impregnated and deposited in step (4) is placed in an oven for drying to obtain a surface-modified fiber aerogel with photothermal / magnetothermal coupling effect. A unique layered array structure can be seen under an electron microscope, and nanoparticles of ferroferric oxide and tin selenide are successfully adhered to the fiber surface.

[0055] Wherein, in step (1), the concentration of polyacrylonitrile in the spinning solution for solution jet spinning is 13%-17%, and aluminum chloride hexahydrate is added in a mass ratio of 1:2-1:4 to obtain a jet spinning precursor. In step (2), the concentration of the Tris-HCl buffer solution is 1%-3%, and the mass concentrations of the added dopamine hydrochloride and polyethyleneimine are both 0.5-1.5 g / L. In step (4), the concentration of the polydimethylsiloxane prepolymer in the mixed solution is 3%. In step (5), the concentration of the ferroferric oxide nanopowder and the tin selenide nanopowder in the modified solution is 2%-5%, and the mass ratio of the ferroferric oxide nanopowder to the tin selenide nanopowder is 2:1-1:2. In step (6), during the impregnation deposition process, any surface of the fiber aerogel matrix is ​​dipped multiple times. In step (7), the oven drying temperature is 40°C. The surface-modified photothermal / magnetocaloric coupling effect fiber aerogel prepared in step (7) has a photothermal / magnetocaloric modification layer having a thickness of 4-6% of the total thickness of the fiber aerogel matrix. The photothermal / magnetocaloric coupling effect fiber aerogel prepared by the preparation method of the present invention is used as an interface evaporator in seawater desalination.

[0056] Polydopamine is a polymer material with excellent photothermal properties. Photothermal properties refer to a material's ability to absorb, conduct, and release heat when exposed to light. Polydopamine has a high absorptivity to visible and near-infrared light, effectively converting light energy into heat. It also exhibits excellent thermal conductivity, effectively conducting absorbed heat energy into the material while maintaining structural stability within a certain temperature range. As a photothermal material, polydopamine boasts high photothermal conversion efficiency and is suitable for applications such as solar thermal power generation and solar water heaters, offering broad potential for development.

[0057] Ferroferric oxide (Fe3O4) is an important magnetic material with ferromagnetism, that is, it exhibits strong magnetization behavior under an external magnetic field. Therefore, Fe3O4 has potential value in magnetothermal applications. Under an external magnetic field, Fe3O4 will undergo a magnetic entropy change, that is, it will release or absorb heat when the magnetic field changes, and can be used for magnetothermal conversion technology. At the same time, Fe3O4 has a certain absorption capacity in the visible light and near-infrared light regions, and can convert light energy into thermal energy. Although the photothermal conversion efficiency of Fe3O4 as a photothermal material may not be as good as some materials specially designed for photothermal conversion, it has certain photothermal properties and can work synergistically with SnSe.

[0058] SnSe is a material with a very high photothermal conversion efficiency. Under light irradiation, SnSe can efficiently absorb light energy and convert it into heat. This photothermal effect makes SnSe have broad application prospects in fields such as solar thermal power generation and solar evaporation. Due to its excellent photothermal properties, SnSe has great potential in solar energy utilization and can help improve the energy conversion efficiency of solar devices. Therefore, the photothermal effect of SnSe is of great significance in promoting the development of renewable energy technologies.

[0059] The ability to continuously and efficiently desalinate seawater around the clock demonstrates the innovative and successfully developed new three-dimensional solar aerogel evaporator, which presents a wide range of application prospects as an interfacial evaporator. The composite fiber membrane, acting as an interfacial evaporator, exhibits excellent magnetocaloric and photothermal responses to non-contact stimuli. It excels not only in magnetocaloric and photothermal evaporation, but also in photothermal evaporation, achieving a solar energy utilization efficiency far exceeding that of most previously reported solar-driven and Joule-driven heating evaporators. Furthermore, the composite fiber membrane, acting as an evaporator, exhibits outstanding salt tolerance, high temperature resistance, and chemical stability, as well as excellent mechanical properties and long-term operational stability. These properties give it enormous potential for application in high-performance water purification and desalination. Overall, this innovation not only provides a highly efficient interfacial evaporator but also opens up new development directions for high-performance water purification and desalination technologies, potentially bringing significant breakthroughs to related industries.

[0060] The present application will be described in detail below through specific examples. The following examples are only some examples of the present application and are not limitations of the present application.

[0061] Example 1:

[0062] A method for preparing a fiber aerogel with photothermal / magnetothermal coupling effect comprises the following steps:

[0063] 1. Preparation of fiber aerogel matrix:

[0064] (1) preparing a spinning solution for solution jet spinning, wherein the concentration of polyacrylonitrile is 13%, and aluminum chloride hexahydrate is added at a mass ratio of 1:2 to obtain a jet spinning precursor. Ultrafine fibers having a three-dimensional layered array structure are prepared using solution jet spinning technology, and pre-oxidized to obtain a fiber aerogel matrix;

[0065] 2. Hydrophilic modification:

[0066] (2) Immerse the fiber aerogel matrix obtained in step (1) in a 1% Tris-HCl buffer solution, add 0.5 g / L dopamine hydrochloride and 0.5 g / L polyethyleneimine, respectively, and shake the mixture continuously at 40°C for 6 h in a dark and sealed environment.

[0067] (3) freeze-drying the fiber aerogel matrix after step (2) for 24 hours to obtain a hydrophilically modified fiber aerogel matrix;

[0068] 3. Photothermal / magnetic thermal modification:

[0069] (4) dissolving a certain amount of polydimethylsiloxane prepolymer in ethyl acetate and mixing them uniformly to obtain a mixed solution with a polydimethylsiloxane prepolymer concentration of 3%, which is set aside;

[0070] (5) Adding ferroferric oxide nanopowder and tin selenide nanopowder to the mixed solution, and uniformly dispersing them by ultrasonic vibration to obtain a modified solution; the concentration of ferroferric oxide nanopowder and tin selenide nanopowder in the modified solution is 2%, and the mass ratio of ferroferric oxide nanopowder to tin selenide nanopowder is 2:1.

[0071] (6) dipping any one surface of the fiber aerogel matrix obtained in step (3) into the modified solution multiple times, performing an immersion deposition treatment, and forming a photothermal / magnetic thermal modification layer on the surface of the fiber aerogel matrix;

[0072] 4. Curing treatment:

[0073] (7) The fiber aerogel matrix obtained by impregnation and deposition in step (4) was placed in an oven at 40°C to dry, thereby obtaining a surface-modified fiber aerogel having a photothermal / magnetocaloric coupling effect. The surface-modified fiber aerogel having a photothermal / magnetocaloric coupling effect prepared in this embodiment had a photothermal / magnetocaloric modification layer having a thickness of 4% of the total thickness of the fiber aerogel matrix.

[0074] Example 2:

[0075] A method for preparing a fiber aerogel with photothermal / magnetothermal coupling effect comprises the following steps:

[0076] 1. Preparation of fiber aerogel matrix:

[0077] (1) preparing a spinning solution for solution jet spinning, wherein the concentration of polyacrylonitrile is 14%, and aluminum chloride hexahydrate is added at a mass ratio of 1:3 to obtain a jet spinning precursor. Ultrafine fibers having a three-dimensional layered array structure are prepared using solution jet spinning technology, and pre-oxidized to obtain a fiber aerogel matrix;

[0078] 2. Hydrophilic modification:

[0079] (2) Immerse the fiber aerogel matrix obtained in step (1) in a 2% Tris-HCl buffer solution, add 1.0 g / L dopamine hydrochloride and 1.0 g / L polyethyleneimine, respectively, and shake the mixture continuously at 40°C for 7 h in a dark and sealed environment.

[0080] (3) freeze-drying the fiber aerogel matrix after step (2) for 24 hours to obtain a hydrophilically modified fiber aerogel matrix;

[0081] 3. Photothermal / magnetic thermal modification:

[0082] (4) dissolving a certain amount of polydimethylsiloxane prepolymer in ethyl acetate and mixing them uniformly to obtain a mixed solution with a polydimethylsiloxane prepolymer concentration of 3%, which is set aside;

[0083] (5) Adding ferroferric oxide nanopowder and tin selenide nanopowder to the mixed solution, and uniformly dispersing them by ultrasonic vibration to obtain a modified solution; the concentration of ferroferric oxide nanopowder and tin selenide nanopowder in the modified solution is 3%, and the mass ratio of ferroferric oxide nanopowder to tin selenide nanopowder is 1:1.

[0084] (6) dipping any one surface of the fiber aerogel matrix obtained in step (3) into the modified solution multiple times, performing an immersion deposition treatment, and forming a photothermal / magnetic thermal modification layer on the surface of the fiber aerogel matrix;

[0085] 4. Curing treatment:

[0086] (7) The fiber aerogel matrix obtained by impregnation and deposition in step (4) is placed in an oven at 40°C for drying to obtain a surface-modified fiber aerogel having a photothermal / magnetocaloric coupling effect. The surface-modified fiber aerogel having a photothermal / magnetocaloric coupling effect prepared in this embodiment has a photothermal / magnetocaloric modification layer having a thickness of 5% of the total thickness of the fiber aerogel matrix.

[0087] Example 3:

[0088] A method for preparing a fiber aerogel with photothermal / magnetothermal coupling effect comprises the following steps:

[0089] 1. Preparation of fiber aerogel matrix:

[0090] (1) preparing a spinning solution for solution jet spinning, wherein the concentration of polyacrylonitrile is 15%, and aluminum chloride hexahydrate is added at a mass ratio of 1:3 to obtain a jet spinning precursor. Ultrafine fibers having a three-dimensional layered array structure are prepared using solution jet spinning technology, and pre-oxidized to obtain a fiber aerogel matrix;

[0091] 2. Hydrophilic modification:

[0092] (2) Immerse the fiber aerogel matrix obtained in step (1) in a 2% Tris-HCl buffer solution, add 1.0 g / L dopamine hydrochloride and 1.0 g / L polyethyleneimine, respectively, and shake the mixture continuously at 40°C for 8 h in a dark and sealed environment.

[0093] (3) freeze-drying the fiber aerogel matrix after step (2) for 24 hours to obtain a hydrophilically modified fiber aerogel matrix;

[0094] 3. Photothermal / magnetic thermal modification:

[0095] (4) dissolving a certain amount of polydimethylsiloxane prepolymer in ethyl acetate and mixing them uniformly to obtain a mixed solution with a polydimethylsiloxane prepolymer concentration of 3%, which is set aside;

[0096] (5) Adding ferroferric oxide nanopowder and tin selenide nanopowder to the mixed solution, and uniformly dispersing them by ultrasonic vibration to obtain a modified solution; the concentration of ferroferric oxide nanopowder and tin selenide nanopowder in the modified solution is 4%, and the mass ratio of ferroferric oxide nanopowder to tin selenide nanopowder is 1:1.

[0097] (6) dipping any one surface of the fiber aerogel matrix obtained in step (3) into the modified solution multiple times, performing an immersion deposition treatment, and forming a photothermal / magnetic thermal modification layer on the surface of the fiber aerogel matrix;

[0098] 4. Curing treatment:

[0099] (7) The fiber aerogel matrix obtained by impregnation and deposition in step (4) was placed in an oven at 40°C to dry, thereby obtaining a surface-modified fiber aerogel having a photothermal / magnetocaloric coupling effect. The surface-modified fiber aerogel having a photothermal / magnetocaloric coupling effect prepared in this embodiment had a photothermal / magnetocaloric modification layer having a thickness of 6% of the total thickness of the fiber aerogel matrix.

[0100] Example 4:

[0101] A method for preparing a fiber aerogel with photothermal / magnetothermal coupling effect comprises the following steps:

[0102] 1. Preparation of fiber aerogel matrix:

[0103] (1) preparing a spinning solution for solution jet spinning, wherein the concentration of polyacrylonitrile is 17%, and aluminum chloride hexahydrate is added at a mass ratio of 1:4 to obtain a jet spinning precursor. Ultrafine fibers having a three-dimensional layered array structure are prepared using solution jet spinning technology, and pre-oxidized to obtain a fiber aerogel matrix;

[0104] 2. Hydrophilic modification:

[0105] (2) Immerse the fiber aerogel matrix obtained in step (1) in a 3% Tris-HCl buffer solution, add 1.5 g / L dopamine hydrochloride and 1.5 g / L polyethyleneimine, respectively, and shake the mixture continuously at 40°C for 10 h in a dark and sealed container.

[0106] (3) freeze-drying the fiber aerogel matrix after step (2) for 24 hours to obtain a hydrophilically modified fiber aerogel matrix;

[0107] 3. Photothermal / magnetic thermal modification:

[0108] (4) dissolving a certain amount of polydimethylsiloxane prepolymer in ethyl acetate and mixing them uniformly to obtain a mixed solution with a polydimethylsiloxane prepolymer concentration of 3%, which is set aside;

[0109] (5) Adding ferroferric oxide nanopowder and tin selenide nanopowder to the mixed solution, and uniformly dispersing them by ultrasonic vibration to obtain a modified solution; the concentration of ferroferric oxide nanopowder and tin selenide nanopowder in the modified solution is 5%, and the mass ratio of ferroferric oxide nanopowder to tin selenide nanopowder is 1:2.

[0110] (6) dipping any one surface of the fiber aerogel matrix obtained in step (3) into the modified solution multiple times, performing an immersion deposition treatment, and forming a photothermal / magnetic thermal modification layer on the surface of the fiber aerogel matrix;

[0111] 4. Curing treatment:

[0112] (7) The fiber aerogel matrix obtained by impregnation and deposition in step (4) was placed in an oven at 40°C to dry, thereby obtaining a surface-modified fiber aerogel having a photothermal / magnetocaloric coupling effect. The surface-modified fiber aerogel having a photothermal / magnetocaloric coupling effect prepared in this embodiment had a photothermal / magnetocaloric modification layer having a thickness of 7% of the total thickness of the fiber aerogel matrix.

[0113] The performance test results of the photothermal / magnetothermal coupling effect fiber aerogels prepared in Examples 1-4 of the present invention are as follows:

[0114] 1. Thermal stability and mechanical properties.

[0115] like Figure 5 As shown in the TG curves, the weight loss rates of SPA, PDA / PEI@SPA, and Fe3O4 / SnSe / PDA / PEI@SPA fiber aerogels at 200°C were 4.45%, 2.93%, and 1.04%, respectively. The main reasons for this are the evaporation of water molecules, the adsorption of SnSe and Fe3O4 on the SPA fiber aerogel, and high-temperature oxidation.

[0116] Furthermore, the weight loss rate of Fe3O4 / SnSe / PDA / PEI@SPA remained stable as the temperature increased, significantly higher than that of SPA and PDA@SPA, indicating excellent thermal stability and providing a good foundation for all-weather desalination. The weight loss rate of the three-dimensional aerogel remained relatively stable at 300°C as the temperature increased, demonstrating its good thermal stability.

[0117] like Figure 6 As shown in the figure, the stress-strain curve of Fe3O4 / SnSe / PDA / PEI@SPA under 60% compressive strain shows that the fatigue durability is estimated by measuring the long-term cyclic compression load. The fiber aerogel can withstand up to 50 cycles without breaking, and its elastic recovery performance is still good, showing its excellent fatigue resistance and ensuring the stability of long-term operation.

[0118] 2. Evaporation rate.

[0119] like Figure 9 As shown in the figure, the surface of the photothermal / magnetic thermal coupling effect fiber aerogel has super hydrophobicity, and the hydrophobic angle can reach about 160°. PDMS (polydimethylsiloxane) plays the role of hydrophobicity and powder adhesion in the present invention, while improving salt resistance. Due to its super hydrophobic effect, it can reduce the deposition of salt on the fiber surface, thus giving it excellent salt resistance, high temperature resistance, and chemical stability. Figure 7-8 As shown, the photothermal evaporation rate can reach 2.53 kgm -2 h -1 , the magnetothermal evaporation rate can reach 4.54kgm -2 h -1 , it can be seen that it has a higher evaporation rate. The specific working principle is as follows Figure 10 As shown, the all-weather seawater desalination technology can continuously provide a stable supply of fresh water. The unique layered array structure has a strong capillary force to effectively transport water upward and can perform multiple refractions to improve the utilization of sunlight. The surface superhydrophobicity has good anti-salting properties. Coupled with the efficient photothermal / magnetic thermal modification layer, it is not restricted by seasonal, weather or climatic conditions, which helps to ensure the sustainable use of water resources.

[0120] 3. Actual test results.

[0121] When the sun is bright and clear, the photothermal / magnetic thermal coupling effect fiber aerogel (Fe3O4 concentration is 4% wt) can be used in the photothermal water evaporation mode. The Fe3O4 and SnSe coupled photothermal effect gives it excellent photothermal water evaporation performance. The water evaporation rate under 1 sun is as follows: Figure 7 shown.

[0122] When the sun is insufficient on cloudy or rainy days, the photothermal / magnetothermal coupling effect fiber aerogel (Fe3O4 concentration is 4% wt) can be used in magnetic hot water evaporation mode or photothermal evaporation coupled with magnetic hot water evaporation mode. In the magnetic hot water evaporation mode, Fe3O4 makes it have excellent magnetic hot water evaporation performance. The magnetic field strength is 18.75KA / m, and the water evaporation rate is as follows: Figure 8 As shown in the photothermal water evaporation coupled with magnetic water evaporation mode, the SnSe photothermal effect is coupled with the Fe3O4 magnetocaloric effect, which makes it have excellent water evaporation performance, and the water evaporation rate reaches 9.1512 kg / m -2 h -1 .

[0123] The present invention prepares a photothermal / magnetothermal coupling effect fiber aerogel with a unique three-dimensional layered array structure based on mass-producible spray spinning technology, and uses it in a seawater desalination interface water evaporator. It has a multi-scale efficient water transmission channel with strong capillary force. In addition to providing a large capillary force to effectively transport water upward, the aerogel layered array structure can also perform multiple refractions to improve the utilization of sunlight. The surface super-hydrophobicity gives it good anti-salting performance. Coupled with the efficient photothermal / magnetothermal layer, it can effectively desalinate seawater. Magnetothermal seawater desalination is mainly through After the surface magnetothermal modification is successful, the external magnetic field (current range is 150A-350A, magnetic field strength range is 13.75-24.75kA / m) is used. The magnetic heating performance is good and energy-saving. When the current is greater than 350A and the magnetic field strength is greater than 24.75KA / m, the magnetic heating performance almost stops increasing and the energy consumption is large. The surface magnetic particles generate magnetic heat to evaporate fresh water through the action of the external magnetic field. The same is true for photothermal seawater desalination. The surface material contains materials that have strong absorption of sunlight, which can effectively absorb sunlight to generate heat and be used for seawater desalination.

[0124] In summary, the photothermal / magnetocaloric coupling fiber aerogel of the present invention utilizes magnetically responsive heating coupled with solar energy for desalination. As an interfacial evaporator, this aerogel exhibits excellent magnetocaloric and photothermal responses, achieving not only superior magnetic and photothermal water evaporation performance but also solar energy utilization efficiency far exceeding previously reported solar-driven and Joule-driven heating evaporators. These characteristics give it enormous potential for application in high-performance water purification and desalination, promising new development directions and significant breakthroughs for related industries.

[0125] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a fiber aerogel with photothermal / magnetothermal coupling effect, characterized in that: The steps include:

1. Preparation of fiber aerogel matrix: (1) preparing a spinning solution, using a solution jet spinning technique to prepare ultrafine fibers with a three-dimensional layered array structure, and performing a pre-oxidation treatment to obtain a fiber aerogel matrix; in the spinning solution used for solution jet spinning, the concentration of polyacrylonitrile is 13%-17%, and aluminum chloride hexahydrate is added at a mass ratio of 1:2-1:4 to obtain a spray-spinning precursor; 2. Hydrophilic modification: (2) Immerse the fiber aerogel matrix obtained in step (1) in a Tris-HCl buffer solution of a certain concentration, add dopamine hydrochloride and polyethyleneimine in sequence, and shake continuously at 40°C for 6-10 hours in the dark and sealed conditions; (3) freeze-drying the fiber aerogel matrix after step (2) for 24 hours to obtain a hydrophilically modified fiber aerogel matrix; 3. Photothermal / magnetic thermal modification: (4) Dissolve a certain amount of polydimethylsiloxane prepolymer in ethyl acetate, mix well, and obtain a mixed solution for later use; (5) Adding ferroferric oxide nanopowder and tin selenide nanopowder into the mixed solution, and uniformly dispersing them by ultrasonic vibration to obtain a modified solution; (6) Dipping any one surface of the fiber aerogel matrix obtained in step (3) into the modified solution and performing an immersion deposition treatment to form a photothermal / magnetic thermal modification layer on the surface of the fiber aerogel matrix; 4. Curing treatment: (7) The fiber aerogel matrix impregnated and deposited in step (4) is placed in an oven for drying to obtain a surface-modified fiber aerogel with photothermal / magnetothermal coupling effect.

2. The method for preparing the photothermal / magnetothermal coupling effect fiber aerogel according to claim 1, characterized in that: In the step (2), the concentration of the Tris-HCl buffer solution is 1%-3%, and the mass concentrations of the added dopamine hydrochloride and polyethyleneimine are both 0.5-1.5 g / L.

3. The method for preparing the photothermal / magnetothermal coupling effect fiber aerogel according to claim 1, characterized in that: In the step (4), the concentration of the polydimethylsiloxane prepolymer in the mixed solution is 3%.

4. The method for preparing the photothermal / magnetothermal coupling effect fiber aerogel according to claim 1, wherein: In the step (5), the concentration of the ferroferric oxide nanopowder and the tin selenide nanopowder in the modified solution is 2%-5%, and the mass ratio of the ferroferric oxide nanopowder to the tin selenide nanopowder is 2:1-1:

2.

5. The method for preparing the photothermal / magnetothermal coupling effect fiber aerogel according to claim 1, characterized in that: In the step (6), any surface of the fiber aerogel matrix is ​​dipped multiple times during the static deposition process.

6. The method for preparing the photothermal / magnetothermal coupling effect fiber aerogel according to claim 1, characterized in that: In the step (7), the oven drying temperature is 40°C.

7. The method for preparing the photothermal / magnetothermal coupling effect fiber aerogel according to claim 1, characterized in that: The surface-modified photothermal / magnetothermal coupling effect fiber aerogel prepared in step (7) has a photothermal / magnetothermal modification layer with a thickness of 4-7% of the total thickness of the fiber aerogel matrix.

8. Use of the photothermal / magnetothermal coupling effect fiber aerogel prepared according to the preparation method according to any one of claims 1 to 7 as an interface evaporator in seawater desalination.

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