Polyphenylene sulfide composite fiber membrane for all-weather seawater desalination and preparation method and application thereof

Abstract

This invention discloses a polyphenylene sulfide (PPS) composite fiber membrane for all-weather seawater desalination, its preparation method, and its applications. The membrane comprises a fiber membrane body, characterized in that the fiber membrane body is prepared from PPS ultrafine fibers, and a polydopamine layer, a polypyrrole layer, a magnetic material layer, and a physical protective layer are sequentially formed on the surface of the PPS ultrafine fibers. As an interfacial evaporator, it demonstrates continuous and efficient seawater desalination capabilities around the clock. Utilizing magnetothermal and photothermal coupling, it can assist in improving photothermal conversion efficiency when sunlight is insufficient, and still maintains high seawater desalination capacity through the magnetothermal effect even in the absence of sunlight, showing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of seawater desalination technology, and particularly relates to a polyphenylene sulfide composite fiber membrane for all-weather seawater desalination, its preparation method and application. Background Technology

[0002] Water resources and energy are essential material foundations for human survival and development. In recent years, with global population growth and accelerated industrialization, freshwater shortages and energy crises have become increasingly severe. Therefore, exploring renewable energy sources and efficient freshwater production methods has become an urgent priority. Seawater desalination technology is considered an effective way to solve the water shortage problem. Solar energy, as a sustainable green energy source, has important applications in energy storage, wastewater treatment, and seawater desalination, providing a convenient energy source for seawater desalination technology. However, the solar-powered evaporator method for seawater desalination is affected by many factors, such as the evaporator stopping operation at night and rainy weather affecting its normal operation. Therefore, it cannot operate continuously for extended periods, making it difficult to further improve the efficiency of seawater desalination based on solar thermal technology. Currently, the existing technologies for solar-powered seawater desalination are as follows:

[0003] CN115557561A discloses a membrane material for seawater desalination and its preparation method. The preparation method includes the following steps: soaking a biomass substrate in a degreasing solution, followed by drying, i.e., dehydrating and degreasing the biomass substrate first; then modifying the treated biomass substrate using plasma method to obtain a new material suitable for seawater desalination. Compared with the prior art, the preparation process of the new seawater desalination material of this invention is simple and rapid. The soaking solution used in the degreasing process can be recycled. The main preparation process does not consume any chemical substances. The raw materials are inexpensive and readily available, and the biomass substrate is a renewable material with minimal environmental impact. The prepared new seawater desalination material has high solar-to-steam conversion efficiency, abundant low-torsion pore structure, strong water transport capacity, is not easily blocked by salt, and has a high evaporation rate.

[0004] CN113301985A discloses a three-dimensional porous membrane for seawater desalination, a method for manufacturing the same, a seawater desalination apparatus including the same, and a seawater desalination method using the same. According to an embodiment of the present invention, the three-dimensional porous membrane includes: a porous polymer layer; and a carbon layer comprising carbon material formed on the porous polymer layer.

[0005] CN113477100A discloses a seawater desalination nanofiltration membrane and its preparation method, comprising three steps: preparing graphene-chitosan composite nanoparticles, preparing a base membrane, and preparing the seawater desalination nanofiltration membrane. This invention obtains a highly hydrophilic composite base membrane by blending graphene-chitosan composite nanoparticles with polyvinylidene fluoride (PVDF). This base membrane overcomes the problem of poor hydrophilicity of PVDF, and the obtained base membrane allows for more uniform dispersion of piperazine solution and trimesoyl chloride solution, greatly reducing agglomeration. Furthermore, the reaction between the amino groups of piperazine and the chloride groups of trimesoyl chloride generates NC=O bonds, thereby forming a highly cross-linked polyamide network on the surface of the base membrane. This results in the PVDF membrane with hydrophilic groups exhibiting excellent antifouling performance and improving the membrane's water flux and desalination rate.

[0006] As can be seen from the aforementioned patented technologies, current solar-powered seawater desalination technology has significantly improved photothermal conversion efficiency and water delivery capacity, and also possesses certain anti-salinity and anti-fouling effects. However, it still cannot achieve all-weather seawater desalination, whether during the day, night, or on cloudy or rainy days when there is no sunlight. In other words, achieving all-weather seawater desalination cannot be accomplished solely by utilizing solar energy, and the desalination efficiency cannot be maximized. Therefore, how to compensate for insufficient or absent sunlight on the basis of solar photothermal desalination, and how to assist in improving photothermal conversion efficiency when sunlight is insufficient, while still maintaining a high seawater desalination capacity in the absence of sunlight, has become a pressing problem for engineers in the field of seawater desalination. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the technical problem to be solved by this invention is to provide a polyphenylene sulfide composite fiber membrane for all-weather seawater desalination, which utilizes magnetic response heating coupled with solar heating to effectively improve seawater desalination efficiency, and its preparation method and application.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a polyphenylene sulfide composite fiber membrane for all-weather seawater desalination, comprising a fiber membrane body, wherein the fiber membrane body is made of polyphenylene sulfide ultrafine fibers, and a polydopamine layer, a polypyrrole layer, a magnetic material layer and a physical protective layer are sequentially formed on the surface of the polyphenylene sulfide ultrafine fibers.

[0009] The aforementioned polyphenylene sulfide composite fiber membrane for all-weather seawater desalination has a porosity of 42%-58% and a pore size of 23-27 μm.

[0010] The aforementioned polyphenylene sulfide composite fiber membrane for all-weather seawater desalination has a magnetic material layer consisting of Fe3O4 powder uniformly attached to the surface of the polypyrrole layer.

[0011] The aforementioned polyphenylene sulfide composite fiber membrane for all-weather seawater desalination has a physical protective layer that is a polyethyleneimine / polydopamine cross-linked layer uniformly coated on the surface of the magnetic material layer.

[0012] A method for preparing a polyphenylene sulfide composite fiber membrane for all-weather seawater desalination includes the following steps:

[0013] I. Fiber Membrane Body:

[0014] (1) Prepare a fiber membrane body made of polyphenylene sulfide ultrafine fibers for later use;

[0015] II. Formation of a polydopamine layer:

[0016] (2) Immerse the fiber membrane body in Tris-HCl buffer solution, then add dopamine hydrochloride, and shake continuously for 14 hours at 40°C under dark and sealed conditions to obtain polydopamine modified polyphenylene sulfide fiber membrane.

[0017] (3) Wash the polyphenylene sulfide fiber membrane obtained in step (2) with deionized water and dry it in an oven at 50-70℃.

[0018] III. Formation of a polypyrrole layer:

[0019] (4) The polyphenylene sulfide fiber membrane obtained in step (3) is immersed in a pyrrole aqueous solution with a concentration of 3-5 mg / ml, and SDBS sodium dodecylbenzene sulfonate with a mass concentration of 0.1-0.3 mg / ml and FeCl3 with a mass concentration of 0.1-0.3 mg / ml are added sequentially. The mixture is shaken and reacted for two hours to polymerize the pyrrole monomer on the surface of the polydopamine layer, thereby obtaining a polydopamine / polypyrrole modified polyphenylene sulfide fiber membrane.

[0020] (5) Wash the polyphenylene sulfide fiber membrane obtained in step (4) with deionized water and dry it in an oven at 50-70℃.

[0021] IV. Formation of a magnetic material layer:

[0022] (6) The polyphenylene sulfide fiber membrane obtained in step (5) is immersed in a Fe3O4 suspension with a concentration of 1-3 wt.% and subjected to ultrasonic vibration treatment;

[0023] (7) The polyphenylene sulfide fiber membrane after ultrasonic vibration treatment is extruded, dried in an oven at 60°C, and then the steps (6) are repeated 2-4 times to obtain a polyphenylene sulfide fiber membrane with Fe3O4 powder uniformly attached to the surface of the polypyrrole layer.

[0024] V. Physical protective layer:

[0025] (8) The polyphenylene sulfide fiber membrane obtained in step (7) is immersed in a Tris-HCl buffer solution with a concentration of 1%-3%, and dopamine hydrochloride with a mass concentration of 0.5-1.5 g / L and polyethyleneimine with a mass concentration of 0.5-1.5 g / L are added in sequence. After shaking and reacting for 2-4 hours, a polyethyleneimine / polydopamine cross-linked layer is formed on the surface of the magnetic material layer.

[0026] (9) Wash the polyphenylene sulfide fiber membrane obtained in step (8) and dry it in an oven at 50-70°C to obtain a polyphenylene sulfide composite fiber membrane.

[0027] In the above-mentioned method for preparing polyphenylene sulfide composite fiber membrane for all-weather seawater desalination, in step (2), before immersing in Tris-HCl buffer solution, the fiber membrane body is pre-wetted with anhydrous ethanol. The concentration of Tris-HCl buffer solution is 1%-3%, the pH is 8-9, and the mass concentration of dopamine hydrochloride is 0.5-1.5 g / L.

[0028] In the above-mentioned method for preparing polyphenylene sulfide composite fiber membrane for all-weather seawater desalination, in step (4), the concentration of pyrrole aqueous solution is 4 mg / ml, the concentration of sodium dodecylbenzenesulfonate SDBS is 0.2 mg / ml, and the concentration of FeCl3 is 0.2 mg / ml.

[0029] In the above-mentioned method for preparing polyphenylene sulfide composite fiber membrane for all-weather seawater desalination, in step (6), the concentration of Fe3O4 suspension is 2wt.% and the ultrasonic oscillation frequency is 40KHz.

[0030] In the above-mentioned method for preparing polyphenylene sulfide composite fiber membrane for all-weather seawater desalination, in step (8), the concentration of Tris-HCl buffer solution is 2%, the mass concentration of dopamine hydrochloride is 1.0 g / L, and the mass concentration of polyethyleneimine is 1.0 g / L.

[0031] The above-mentioned polyphenylene sulfide composite fiber membrane for all-weather seawater desalination is used in seawater desalination.

[0032] The advantages of this invention regarding the polyphenylene sulfide (PP) composite fiber membrane for all-weather seawater desalination, its preparation method, and its application are as follows: This invention successfully developed a novel PP / F / PP@PPS composite fiber membrane, which, as an interfacial evaporator, demonstrates continuous and efficient seawater desalination capabilities around the clock. Utilizing magnetothermal and photothermal coupling, it can assist in improving photothermal conversion efficiency when sunlight is insufficient, and still maintains high seawater desalination capacity through the magnetothermal effect even in the absence of sunlight, showing broad application prospects. This composite fiber membrane is based on PPS fiber membrane, and through a series of carefully designed modification treatments, it retains the original excellent performance of PPS fiber membrane while further enhancing its overall performance. As an interfacial evaporator, this composite fiber membrane exhibits remarkable magnetothermal and photothermal responses to non-contact stimuli. It not only possesses excellent magnetothermal water evaporation performance but also excellent photothermal water evaporation performance, with solar energy utilization efficiency far exceeding most previously reported solar-driven and Joule-driven heating evaporators. Furthermore, as an evaporator, this composite fiber membrane also possesses excellent salt resistance, high-temperature resistance, chemical stability, as well as good mechanical properties and long-term operational stability. These characteristics give it enormous application potential in high-performance water purification and seawater desalination. It not only provides a highly efficient interfacial evaporator but also offers a new direction for the development of high-performance water purification and seawater desalination technologies. Attached Figure Description

[0033] Figure 1 This is a physical image of the polyphenylene sulfide composite fiber membrane of the present invention;

[0034] Figure 2 This is an electron microscope image of the surface morphology of the polyphenylene sulfide composite fiber membrane of the present invention;

[0035] Figure 3 This is a structural rendering of the polydopamine layer, polypyrrole layer, magnetic material layer, and physical protective layer on the surface of a single fiber in a polyphenylene sulfide composite fiber membrane.

[0036] Figure 4 This is a thermogravimetric diagram of the polyphenylene sulfide composite fiber membrane of the present invention;

[0037] Figure 5 The image shows the tensile test results of the polyphenylene sulfide composite fiber membrane of the present invention.

[0038] Figure 6 The graphs show the evaporation rate curves of the polyphenylene sulfide composite fiber membranes obtained in Examples 1-3 under magnetic heating and photoheating, respectively.

[0039] Figure 7 This is a graph showing the partial magnetic field strength and magnetic heating temperature changes measured in the polyphenylene sulfide composite fiber membrane of Example 2;

[0040] Figure 8This is a schematic diagram showing the evaporation rate results of Example 2 under photothermal and magnetic heating at a NaCl concentration of 20 wt.%.

[0041] Figure 9 Schematic diagram of the temperature results of photothermal heating after immersion of PEIPDA / Fe3O4 / PPY / PDA@PPS composite fiber membrane in solutions with different pH values ​​for 6 hours;

[0042] Figure 10 A schematic diagram showing the temperature results of magnetic heating after immersing the PEIPDA / Fe3O4 / PPY / PDA@PPS composite fiber membrane in solutions with different pH values ​​for 6 hours.

[0043] Figure 11 This is a schematic diagram showing the photothermal evaporation rate and efficiency results of the polyphenylene sulfide composite fiber membrane used 8 times in Example 2.

[0044] Figure 12 This is a schematic diagram showing the evaporation rate results of magnetic heating measured after the polyphenylene sulfide composite fiber membrane of Example 2 was used 8 times.

[0045] Figure 13 The images show the seawater desalination effect under different lighting conditions according to the present invention. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] In this invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish an order. The term "multiple" means "two or more".

[0048] like Figure 1 , 2As shown in Figure 3, a polyphenylene sulfide (PPS) composite fiber membrane for all-weather seawater desalination includes a fiber membrane body, characterized in that: the fiber membrane body is prepared from polyphenylene sulfide ultrafine fibers (PPS), and a polydopamine (PDA) layer, a polypyrrole (PPY) layer, a magnetic material layer (Fe3O4), and a physical protective layer are sequentially formed on the surface of the PPS ultrafine fibers. The magnetic material layer consists of Fe3O4 powder uniformly attached to the surface of the polypyrrole layer, and the physical protective layer is a polyethyleneimine (PEI) / polydopamine (PDA) crosslinked layer uniformly coated on the surface of the magnetic material layer. The porosity of the PPS composite fiber membrane is 42%-58%, and the pore size is 23-27 μm. The figure also describes the application of the PPS composite fiber membrane for all-weather seawater desalination in seawater desalination.

[0049] The method for preparing the polyphenylene sulfide composite fiber membrane of the present invention includes the following steps:

[0050] I. Fiber Membrane Body:

[0051] (1) Prepare a fiber membrane body made of polyphenylene sulfide ultrafine fibers for later use;

[0052] II. Formation of a polydopamine layer:

[0053] (2) Immerse the fiber membrane body in Tris-HCl buffer solution, then add dopamine hydrochloride, and shake continuously for 14 hours at 40°C under dark and sealed conditions to obtain polydopamine modified polyphenylene sulfide fiber membrane.

[0054] (3) Wash the polyphenylene sulfide fiber membrane obtained in step (2) with deionized water and dry it in an oven at 50-70℃.

[0055] III. Formation of a polypyrrole layer:

[0056] (4) The polyphenylene sulfide fiber membrane obtained in step (3) is immersed in a pyrrole aqueous solution with a concentration of 3-5 mg / ml, and SDBS sodium dodecylbenzene sulfonate with a concentration of 0.1-0.3 mg / ml and FeCl3 with a concentration of 0.1-0.3 mg / ml are added sequentially. The mixture is shaken and reacted for two hours to polymerize the pyrrole monomer on the surface of the polydopamine layer, thereby obtaining a polydopamine / polypyrrole modified polyphenylene sulfide fiber membrane.

[0057] (5) Wash the polyphenylene sulfide fiber membrane obtained in step (4) with deionized water and dry it in an oven at 50-70℃.

[0058] IV. Formation of a magnetic material layer:

[0059] (6) The polyphenylene sulfide fiber membrane obtained in step (5) is immersed in a Fe3O4 suspension with a concentration of 1-3 wt.% and subjected to ultrasonic vibration treatment;

[0060] (7) The polyphenylene sulfide fiber membrane after ultrasonic vibration treatment is extruded, dried in an oven at 60°C, and then the steps (6) are repeated 2-4 times to obtain a polyphenylene sulfide fiber membrane with Fe3O4 powder uniformly attached to the surface of the polypyrrole layer.

[0061] V. Physical protective layer:

[0062] (8) The polyphenylene sulfide fiber membrane obtained in step (7) is immersed in a Tris-HCl buffer solution with a concentration of 1%-3%, and dopamine hydrochloride with a mass concentration of 0.5-1.5 g / L and polyethyleneimine with a mass concentration of 0.5-1.5 g / L are added in sequence. After shaking and reacting for 2-4 hours, a polyethyleneimine / polydopamine cross-linked layer is formed on the surface of the magnetic material layer.

[0063] (9) Wash the polyphenylene sulfide fiber membrane obtained in step (8) and dry it in an oven at 50-70°C to obtain a polyphenylene sulfide composite fiber membrane.

[0064] Polyphenylene sulfide (PPS) fiber membranes typically have a fiber diameter of less than 5 μm, also known as microfibers, ultrafine fibers, or fine fibers. The fiber membrane has a porosity of approximately 70% and a pore size of about 35 μm. Modified PPS composite fiber membranes have a porosity of 42%-58% and a pore size of 23-27 μm. The membrane body is prepared using meltblown nonwoven technology or electrospinning technology; this invention uses meltblown nonwoven technology. Since electrospinning technology can produce very fine fibers, typically with a diameter below 100 nm and a uniform diameter distribution, it can achieve a larger specific surface area and porosity, exhibiting better desalination efficiency during solar heating and magnetic heating processes. Therefore, it can also be used to prepare the membrane body required for this invention. Furthermore, electrospinning does not require high temperature and high pressure conditions, making the process conditions relatively easy to achieve and enabling large-scale production. Both of these technologies are conventional existing technologies in textile engineering and can be flexibly selected according to the actual needs of the PPS fiber membrane. The process parameters can be determined according to requirements, so they will not be described in detail.

[0065] Polyphenylene sulfide (PPS) fiber is a novel polymer material with high heat resistance, corrosion resistance, and mechanical properties, making PPS fiber membranes an ideal choice for seawater desalination. Furthermore, by utilizing magnetic response heating and solar heating, all-weather seawater desalination can be achieved.

[0066] Polydopamine (PDA) possesses unique advantages as both a binder and a photothermal material. As a binder, it exhibits excellent adhesion to various material surfaces, forming strong bonds with metals, plastics, ceramics, and biomaterials. Its advantage lies in maintaining good adhesion even in humid environments, enabling reliable applications in bonding, coating, and surface modification across diverse conditions. As a photothermal material, PDA exhibits excellent photothermal conversion performance and stability. Through surface modification or doping with other functional components, its photothermal performance can be regulated, leading to its widespread application in solar energy absorption, heat conversion, and energy storage. Its advantages lie in its naturally occurring biocompatibility and its tunable polymerization methods and structures, making it a promising multifunctional photothermal material. However, the photothermal conversion efficiency of PDA as a photothermal material needs improvement; therefore, it is necessary to find a material with excellent photothermal performance, good thermal stability and thermal conductivity, and high photothermal conversion efficiency.

[0067] Polypyrrole (PP) is a polymer material with excellent photothermal properties. Photothermal properties typically refer to a material's ability to absorb, conduct, and release heat energy under light. PPP exhibits the following characteristics in this regard: it has a high absorption rate for visible and near-infrared light, effectively converting light energy into heat; it has good thermal conductivity, efficiently transferring absorbed heat energy into the material's interior; it possesses good thermal stability, maintaining structural stability within a certain temperature range and resisting thermal decomposition or loss of function; and as a photothermal material, it boasts high photothermal conversion efficiency, effectively converting light energy into heat energy for applications such as solar thermal power generation and solar water heaters. In summary, PPP possesses excellent photothermal properties, making it suitable for various photothermal applications, and it has broad development prospects in material design and engineering applications.

[0068] Iron(III) oxide (Fe3O4) is an important magnetic material exhibiting ferromagnetism, meaning it displays strong magnetization under an applied magnetic field, making it potentially valuable in magnetocaloric applications. Fe3O4 undergoes a magnetic entropy change under an applied magnetic field, meaning it releases or absorbs heat when the magnetic field changes; this entropy change effect can be used in magnetocaloric conversion technology. Furthermore, Fe3O4 has a certain absorption capacity in the visible and near-infrared light regions, allowing it to convert light energy into heat energy. While the photothermal conversion efficiency of Fe3O4 as a photothermal material may not be as high as some materials specifically designed for photothermal conversion, it possesses certain photothermal properties and can synergize with the photothermal effect of PDA (Polymer Producer). However, after Fe3O4 is adhered, significant detachment occurs due to the PPY layer separating it from the PDA. Therefore, it is necessary to find a material that can add a physical barrier to the outer layer of Fe3O4 without affecting its other functions, thus limiting Fe3O4 detachment.

[0069] Both PDA and PEI possess excellent chemical stability, resisting the erosion and corrosion of many chemicals. This allows them to maintain their physical barrier function under various environmental conditions. A PDA / PEI crosslinked network is formed on the fiber surface through Schiff base or Michael addition reactions, giving the fibers excellent hydrophilicity. Interestingly, an extremely thin PDA / PEI layer is innovatively assembled on the composite membrane surface as a physical barrier, thereby inhibiting the spontaneous oxidation and shedding of Fe3O4, thus improving environmental stability and evaporator lifespan. This invention achieves all-weather seawater desalination through magnetic response control coupled with solar energy. Utilizing both magnetic heating and solar heating, it achieves all-weather seawater desalination, not only solving the problem of low efficiency in solar desalination alone, but also enabling continuous seawater desalination through magnetic response when sunlight is insufficient, aided by polypyrrole and iron oxide layers to improve photothermal conversion efficiency, even at night or on cloudy days when solar desalination is unavailable.

[0070] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0071] Example 1:

[0072] A method for preparing a polyphenylene sulfide composite fiber membrane for all-weather seawater desalination includes the following steps:

[0073] I. Fiber Membrane Body:

[0074] (1) Prepare a fiber membrane body made of polyphenylene sulfide ultrafine fibers for later use;

[0075] II. Formation of a polydopamine layer:

[0076] (2) The polyphenylene sulfide fiber membrane was pre-wetted with anhydrous ethanol to improve the modification effect. The pre-wetted fiber membrane was immersed in a Tris-HCl buffer solution with a concentration of 1% and a pH of 8. Then, dopamine hydrochloride with a mass concentration of 0.5 g / L was added. Under dark and sealed conditions, the membrane was continuously shaken at 40°C for 14 h to obtain polydopamine-modified polyphenylene sulfide fiber membrane.

[0077] (3) Wash the polyphenylene sulfide fiber membrane obtained in step (2) with deionized water and dry it in an oven at 50-70℃.

[0078] III. Formation of a polypyrrole layer:

[0079] (4) The polyphenylene sulfide fiber membrane obtained in step (3) is immersed in a pyrrole aqueous solution with a concentration of 3 mg / ml, and SDBS sodium dodecylbenzene sulfonate with a concentration of 0.1 mg / ml and FeCl3 with a concentration of 0.1 mg / ml are added sequentially. The mixture is shaken and reacted for two hours to allow the pyrrole monomer to polymerize on the surface of the polydopamine layer, thereby obtaining a polydopamine / polypyrrole modified polyphenylene sulfide fiber membrane.

[0080] (5) Wash the polyphenylene sulfide fiber membrane obtained in step (4) with deionized water and dry it in an oven at 50-70℃.

[0081] IV. Formation of a magnetic material layer:

[0082] (6) The polyphenylene sulfide fiber membrane obtained in step (5) is immersed in a Fe3O4 suspension with a concentration of 1 wt.% and subjected to ultrasonic vibration treatment at a frequency of 40 kHz.

[0083] (7) The polyphenylene sulfide fiber membrane after ultrasonic vibration treatment is extruded, dried in an oven at 60°C, and then the steps (6) are repeated 2-4 times to obtain a polyphenylene sulfide fiber membrane with Fe3O4 powder uniformly attached to the surface of the polypyrrole layer.

[0084] V. Physical protective layer:

[0085] (8) The polyphenylene sulfide fiber membrane obtained in step (7) is immersed in a Tris-HCl buffer solution with a concentration of 1%-3%, and then 0.5 g / L of dopamine hydrochloride and 0.5 g / L of polyethyleneimine are added in sequence. After shaking and reacting for 2-4 hours, a polyethyleneimine / polydopamine cross-linked layer is formed on the surface of the magnetic material layer.

[0086] (9) The polyphenylene sulfide fiber membrane obtained in step (8) is washed and dried in an oven at 50-70°C to obtain a polyphenylene sulfide composite fiber membrane with a porosity of 42% and a pore size of 23μm.

[0087] Example 2:

[0088] A method for preparing a polyphenylene sulfide composite fiber membrane for all-weather seawater desalination includes the following steps:

[0089] I. Fiber Membrane Body:

[0090] (1) Prepare a fiber membrane body made of polyphenylene sulfide ultrafine fibers for later use;

[0091] II. Formation of a polydopamine layer:

[0092] (2) The polyphenylene sulfide fiber membrane was pre-wetted with anhydrous ethanol to improve the modification effect. The pre-wetted fiber membrane body was immersed in a Tris-HCl buffer solution with a concentration of 2% and a pH of 8.5. Then, dopamine hydrochloride with a mass concentration of 1.0 g / L was added. Under dark and sealed conditions, it was continuously shaken at 40°C for 14 h to obtain polydopamine modified polyphenylene sulfide fiber membrane.

[0093] (3) Wash the polyphenylene sulfide fiber membrane obtained in step (2) with deionized water and dry it in an oven at 50-70℃.

[0094] III. Formation of a polypyrrole layer:

[0095] (4) The polyphenylene sulfide fiber membrane obtained in step (3) is immersed in a pyrrole aqueous solution with a concentration of 4 mg / ml, and SDBS sodium dodecylbenzene sulfonate with a mass concentration of 0.2 mg / ml and FeCl3 with a mass concentration of 0.2 mg / ml are added sequentially. The mixture is shaken and reacted for two hours to allow the pyrrole monomer to polymerize on the surface of the polydopamine layer, thereby obtaining a polydopamine / polypyrrole modified polyphenylene sulfide fiber membrane.

[0096] (5) Wash the polyphenylene sulfide fiber membrane obtained in step (4) with deionized water and dry it in an oven at 50-70℃.

[0097] IV. Formation of a magnetic material layer:

[0098] (6) The polyphenylene sulfide fiber membrane obtained in step (5) is immersed in a Fe3O4 suspension with a concentration of 2 wt.% and subjected to ultrasonic vibration treatment;

[0099] (7) The polyphenylene sulfide fiber membrane after ultrasonic vibration treatment is extruded, dried in an oven at 60°C, and then step (6) is repeated twice to obtain a polyphenylene sulfide fiber membrane with Fe3O4 powder uniformly attached to the surface of the polypyrrole layer.

[0100] V. Physical protective layer:

[0101] (8) The polyphenylene sulfide fiber membrane obtained in step (7) is immersed in a Tris-HCl buffer solution with a concentration of 2%, and then 1.0 g / L of dopamine hydrochloride and 1.0 g / L of polyethyleneimine are added in sequence. After shaking and reacting for 2-4 hours, a polyethyleneimine / polydopamine cross-linked layer is formed on the surface of the magnetic material layer.

[0102] (9) The polyphenylene sulfide fiber membrane obtained in step (8) is washed and dried in an oven at 50-70°C to obtain a polyphenylene sulfide composite fiber membrane with a porosity of 58% and a pore size of 27μm.

[0103] Example 3:

[0104] A method for preparing a polyphenylene sulfide composite fiber membrane for all-weather seawater desalination includes the following steps:

[0105] I. Fiber Membrane Body:

[0106] (1) Prepare a fiber membrane body made of polyphenylene sulfide ultrafine fibers for later use;

[0107] II. Formation of a polydopamine layer:

[0108] (2) The polyphenylene sulfide fiber membrane was pre-wetted with anhydrous ethanol to improve the modification effect. The pre-wetted fiber membrane was immersed in a Tris-HCl buffer solution with a concentration of 3% and a pH of 9. Then, dopamine hydrochloride with a mass concentration of 1.5 g / L was added. Under dark and sealed conditions, the membrane was continuously shaken at 40°C for 14 h to obtain polydopamine-modified polyphenylene sulfide fiber membrane.

[0109] (3) Wash the polyphenylene sulfide fiber membrane obtained in step (2) with deionized water and dry it in an oven at 50-70℃.

[0110] III. Formation of a polypyrrole layer:

[0111] (4) The polyphenylene sulfide fiber membrane obtained in step (3) is immersed in a pyrrole aqueous solution with a concentration of 5 mg / ml, and SDBS sodium dodecylbenzene sulfonate with a mass concentration of 0.3 mg / ml and FeCl3 with a mass concentration of 0.3 mg / ml are added sequentially. The mixture is shaken and reacted for two hours to allow the pyrrole monomer to polymerize on the surface of the polydopamine layer, thereby obtaining a polydopamine / polypyrrole modified polyphenylene sulfide fiber membrane.

[0112] (5) Wash the polyphenylene sulfide fiber membrane obtained in step (4) with deionized water and dry it in an oven at 50-70℃.

[0113] IV. Formation of a magnetic material layer:

[0114] (6) The polyphenylene sulfide fiber membrane obtained in step (5) is immersed in a Fe3O4 suspension with a concentration of 3wt.% and subjected to ultrasonic vibration treatment at a frequency of 40KHz.

[0115] (7) The polyphenylene sulfide fiber membrane after ultrasonic vibration treatment is extruded, dried in an oven at 60°C, and then step (6) is repeated 3 times to obtain a polyphenylene sulfide fiber membrane with Fe3O4 powder uniformly attached to the surface of the polypyrrole layer.

[0116] V. Physical protective layer:

[0117] (8) The polyphenylene sulfide fiber membrane obtained in step (7) is immersed in a Tris-HCl buffer solution with a concentration of 3%, and dopamine hydrochloride with a mass concentration of 1.5 g / L and polyethyleneimine with a mass concentration of 1.5 g / L are added in sequence. After shaking and reacting for 2-4 hours, a polyethyleneimine / polydopamine cross-linked layer is formed on the surface of the magnetic material layer.

[0118] (9) The polyphenylene sulfide fiber membrane obtained in step (8) is washed and dried in an oven at 50-70°C to obtain a polyphenylene sulfide composite fiber membrane with a porosity of 50% and a pore size of 25μm.

[0119] The performance test results of the polyphenylene sulfide composite fiber membranes for all-weather seawater desalination prepared in Examples 1-3 of this invention are as follows:

[0120] 1. Thermal stability and mechanical properties.

[0121] like Figure 4 As shown in the TG curve, the weight loss rate of the polyphenylene sulfide composite fiber membrane remains stable with increasing temperature, indicating that the polyphenylene sulfide composite fiber membrane has good thermal stability. Figure 5 As shown in the stress-strain diagram, it represents the tensile behavior of the polyphenylene sulfide composite fiber membrane before and after modification. A strong π-π interface exists between the benzene rings of polyphenylene sulfide fiber (PPS) and polydopamine (PDA), enhancing the tensile strength of the polyphenylene sulfide composite fiber membrane.

[0122] 2. Evaporation rate.

[0123] like Figure 6 As shown in the evaporation rate curves obtained from the polyphenylene sulfide composite fiber membranes in Examples 1-3 under magnetic heating and light heating, it can be seen that when the Fe3O4 suspension concentration is 1%wt, the evaporation rate of the magnetic hot water is not high, reaching only 1.6 kg m³. -2 h -1 As the Fe3O4 concentration increases, the evaporation rate of the polyphenylene sulfide composite fiber membrane increases under magnetic heating. However, after the Fe3O4 suspension concentration reaches 2%, the increase in evaporation rate is minimal. When the Fe3O4 suspension concentration is 3% wt, the excessively high Fe3O4 agglomeration concentration leads to uneven aggregation of Fe3O4 powder on the surface of the polypyrrole (PPY) layer, resulting in poor thermal uniformity and significantly reduced porosity between the fiber membranes. Consequently, the evaporation rate of the composite fiber membrane under magnetic heating does not increase significantly. The excessive agglomeration of Fe3O4 does not lead to a significant increase in evaporation rate, and the blocking effect of Fe3O4 on the polypyrrole (PPY) layer reduces the photothermal effect, thus lowering the photothermal evaporation rate. Therefore, a Fe3O4 suspension concentration of 2% wt is the optimal concentration.

[0124] like Figure 7 As shown in the graph of partial magnetic field strength and magnetic heating temperature changes measured in the polyphenylene sulfide composite fiber membrane prepared in Example 2, when the Fe3O4 concentration is 2%wt, the current range is 150A-350A, the magnetic field strength range is 13.75-24.75kA / m, the magnetic heating performance is good and energy-saving, and the magnetic heating temperature range is 80℃-116℃. When the current is >350A and the magnetic field strength is greater than 24.75KA / m, the magnetic heating temperature hardly increases anymore, reaching 118℃, and the energy consumption is high.

[0125] 3. Tolerance under harsh environments:

[0126] like Figure 8 The figure shows the evaporation rates of the polyphenylene sulfide fiber composite membrane prepared in Example 2 under photothermal and magnetic heating conditions at a NaCl concentration of 20 wt.%. As can be seen from the figure, in a high-concentration brine of 20 wt.%, the magnetic evaporation rate of the evaporator not only does not decrease, but also increases due to the induced current generated by the conductivity of the salt particles, which enhances the heating effect. The photothermal evaporation rate is unaffected, demonstrating the strong salt resistance of the composite material.

[0127] like Figure 9 , 10 As shown, the polyphenylene sulfide fiber composite membrane prepared in Example 2 was immersed in seawater under different acid and alkaline environments to simulate seawater desalination under harsh conditions. According to... Figure 9-10 It can be seen that the temperature of the composite membrane is not affected after treatment in different acid and alkali environments. This indicates that the polyphenylene sulfide fiber composite membrane of the present invention has stable chemical corrosion resistance, and its photothermal temperature and magnetothermal temperature remain unchanged.

[0128] like Figure 11 , 12 As shown in the bar chart, the evaporation rates and efficiencies of light heating and magnetic heating were measured after 8 uses. It can be seen that the evaporation rate and efficiency do not fluctuate much with the number of uses, indicating that the polyphenylene sulfide composite fiber membrane of the present invention has good durability as a seawater desalination evaporator.

[0129] 4. Actual test results:

[0130] like Figure 13 As shown, under clear, sunny conditions, this polyphenylene sulfide composite fiber membrane (Fe3O4 concentration of 2% wt) can utilize photothermal evaporation. The coupled photothermal effect of polydopamine (PDA) and polypyrrole (PPY) gives it excellent photothermal evaporation performance, achieving a water evaporation rate of 1.84 kg / m³ under one day of sunlight. -2 h -1 The solar energy conversion efficiency reaches 90.76%, such as Figure 6 As shown.

[0131] When sunlight is insufficient on cloudy or rainy days, this polyphenylene sulfide composite fiber membrane (Fe3O4 concentration of 2% wt) can be used in either magnetic water evaporation mode or photo-water evaporation coupled with magnetic water evaporation mode. In magnetic water evaporation mode, Fe3O4 gives it excellent magnetic water evaporation performance, with a magnetic field strength of 18.75 kA / m and a water evaporation rate of 2.83 kg / m. -2 h -1 .

[0132] In the photothermal evaporation coupled with magnetic evaporation mode, the photothermal effects of PDA and PPY are coupled with the magnetic evaporative effect of Fe3O4, resulting in excellent water evaporation performance with an evaporation rate of 3.25 kg m³. -2 h -1 .

[0133] In summary, this invention provides a method for preparing a PP / F / PP@PPS composite fiber membrane for seawater desalination using magnetic response heating coupled with solar heating. This composite fiber membrane, as an interfacial evaporator, exhibits remarkable magnetothermal and photothermal responses to non-contact stimuli. It not only possesses excellent magnetothermal evaporation performance but also superior photothermal evaporation performance, with solar energy utilization efficiency far exceeding that of most previously reported solar-driven and Joule-driven heating evaporators. Furthermore, this composite fiber membrane, as an evaporator, also possesses excellent salt resistance, high-temperature resistance, chemical stability, as well as good mechanical properties and long-term operational stability. These characteristics give it enormous application potential in high-performance water purification and seawater desalination. This invention not only provides a highly efficient interfacial evaporator but also offers a new direction for the development of high-performance water purification and seawater desalination technologies, and is expected to bring significant breakthroughs to related industries.

[0134] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A polyphenylene sulfide composite fiber membrane for all-weather seawater desalination, comprising a fiber membrane body, characterized in that: The fiber membrane body is made of polyphenylene sulfide ultrafine fibers, and a polydopamine layer, a polypyrrole layer, a magnetic material layer and a physical protective layer are sequentially formed on the surface of the polyphenylene sulfide ultrafine fibers; the porosity of the polyphenylene sulfide composite fiber membrane is 42%-58% and the pore size is 23-27μm; the magnetic material layer is Fe3O4 powder uniformly attached to the surface of the polypyrrole layer, and the physical protective layer is a polyethyleneimine / polydopamine crosslinked layer uniformly coated on the surface of the magnetic material layer.

2. A method for preparing the polyphenylene sulfide composite fiber membrane as described in claim 1, characterized in that, Includes the following steps: I. Fiber Membrane Body: (1) Prepare a fiber membrane body made of polyphenylene sulfide ultrafine fibers for later use; II. Formation of a polydopamine layer: (2) First, the fiber membrane body is pre-wetted with anhydrous ethanol, then the fiber membrane body is immersed in a Tris-HCl buffer solution with a concentration of 1%-3% and a pH of 8-9. Then, dopamine hydrochloride with a mass concentration of 0.5-1.5 g / L is added. Under dark and sealed conditions, the membrane is continuously shaken at 40°C for 14 h to obtain polydopamine-modified polyphenylene sulfide fiber membrane. (3) Wash the polyphenylene sulfide fiber membrane obtained in step (2) with deionized water and dry it in an oven at 50-70℃; III. Formation of a polypyrrole layer: (4) The polyphenylene sulfide fiber membrane obtained in step (3) is immersed in a pyrrole aqueous solution with a concentration of 3-5 mg / ml, and SDBS sodium dodecylbenzene sulfonate with a mass concentration of 0.1-0.3 mg / ml and FeCl3 with a mass concentration of 0.1-0.3 mg / ml are added sequentially. The mixture is shaken and reacted for two hours to allow the pyrrole monomer to polymerize on the surface of the polydopamine layer, thereby obtaining a polydopamine / polypyrrole modified polyphenylene sulfide fiber membrane. (5) Wash the polyphenylene sulfide fiber membrane obtained in step (4) with deionized water and dry it in an oven at 50-70°C. IV. Formation of a magnetic material layer: (6) The polyphenylene sulfide fiber membrane obtained in step (5) is immersed in a Fe3O4 suspension with a concentration of 1-3 wt.% and subjected to ultrasonic vibration treatment; (7) The polyphenylene sulfide fiber membrane after ultrasonic vibration treatment is extruded, dried in an oven at 60°C, and then the steps (6) are repeated 2-4 times to obtain a polyphenylene sulfide fiber membrane with Fe3O4 powder uniformly attached to the surface of the polypyrrole layer. V. Physical protective layer: (8) The polyphenylene sulfide fiber membrane obtained in step (7) is immersed in a Tris-HCl buffer solution with a concentration of 1%-3%, and dopamine hydrochloride with a mass concentration of 0.5-1.5 g / L and polyethyleneimine with a mass concentration of 0.5-1.5 g / L are added in sequence. After shaking and reacting for 2-4 hours, a polyethyleneimine / polydopamine cross-linked layer is formed on the surface of the magnetic material layer. (9) Wash the polyphenylene sulfide fiber membrane obtained in step (8) and dry it in an oven at 50-70°C to obtain a polyphenylene sulfide fiber composite membrane.

3. The method for preparing the polyphenylene sulfide composite fiber membrane for all-weather seawater desalination according to claim 2, characterized in that: In step (4), the concentration of the pyrrole aqueous solution is 4 mg / ml, the concentration of sodium dodecylbenzenesulfonate SDBS is 0.2 mg / ml, and the concentration of FeCl3 is 0.2 mg / ml.

4. The method for preparing the polyphenylene sulfide composite fiber membrane for all-weather seawater desalination according to claim 2, characterized in that: In step (6), the concentration of Fe3O4 suspension is 2 wt.%, and the ultrasonic oscillation frequency is 40 kHz.

5. The method for preparing the polyphenylene sulfide composite fiber membrane for all-weather seawater desalination according to claim 2, characterized in that: In step (8), the concentration of Tris-HCl buffer solution is 2%, the mass concentration of dopamine hydrochloride is 1.0 g / L, and the mass concentration of polyethyleneimine is 1.0 g / L.

6. The application of the polyphenylene sulfide composite fiber membrane for all-weather seawater desalination according to claim 1 in seawater desalination.

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