Super-hydrophilic and oil-repellent light-to-heat fabric, and preparation and application thereof

Abstract

The present application relates to the field of photothermal fiber, and relates to a super-hydrophilic and oil-resistant photothermal fabric and preparation and application thereof, comprising the following steps: placing a fabric in a water solution containing a photothermal polymer to react, washing and drying after the reaction is completed to obtain a photothermal fabric; soaking the photothermal fabric in a casting solution, and then soaking it in a nanocrystal water solution to react, washing and drying after the reaction is completed to obtain a super-hydrophilic photothermal fabric; soaking the super-hydrophilic photothermal fabric in a porous nanocrystal-methanol solution, and washing and drying after the reaction is completed to obtain the super-hydrophilic and oil-resistant photothermal fabric. Compared with the prior art, the present application has the advantages of simple, fast preparation process, excellent oil adhesion prevention, effective oil interception and the like.

Description

Technical Field

[0001] This invention relates to the field of photothermal fibers, and in particular to a superhydrophilic, oil-resistant photothermal fabric and its preparation and application. Background Technology

[0002] The scarcity of freshwater resources has become a significant obstacle to sustainable social development. To address this issue, a series of methods, such as membrane distillation, reverse osmosis, and thermal distillation, have been developed to produce large quantities of freshwater. However, these methods consume substantial amounts of energy. Utilizing cost-effective and environmentally friendly solar-powered seawater desalination technology is considered one of the most promising strategies for alleviating the increasingly severe freshwater crisis. However, due to marine fuel leaks and the random discharge of industrial and domestic wastewater, large amounts of oil remain in natural seawater. When interfacial solar evaporators operate for extended periods in this complex environment, oil adheres to the surface of the photothermal material, causing scaling and clogging the water delivery channels. This significantly impacts the material's evaporation rate and the long-term stability of freshwater production. Therefore, there is an urgent need to develop an oil-resistant, high-efficiency photothermal material for application in seawater desalination.

[0003] Currently, researchers have proposed several approaches to prepare oil-resistant photothermal materials, typically based on two methods: The first method is to achieve superhydrophilicity and superoleophobicity in air on the material surface. This method mostly uses fluorinated surfactants with hydrophilic head groups and hydrophobic tail groups, resulting in expensive and environmentally unfriendly materials that lead to more serious environmental pollution. The second method is to develop surfaces that are hydrophilic in air and oleophobic underwater. This method mainly prepares oil-resistant photothermal materials by constructing layered structures and modifying the surface to be hydrophilic. The materials prepared mostly rely on expensive rigid metal substrates such as copper mesh and foam, which suffer from poor flexibility, high cost, and poor environmental performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide a superhydrophilic oil-resistant photothermal fabric and its preparation and application. This invention constructs a superhydrophilic oil-resistant surface on a flexible photothermal material substrate, which solves the existing complex oil pollution problem in seawater. The photothermal material can still achieve stable and efficient seawater evaporation performance in oily seawater.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a superhydrophilic, oil-resistant, photothermal fabric includes the following steps:

[0007] S1: The fabric is placed in an aqueous solution containing a photothermal polymer to react. After the reaction is complete, it is washed and dried to obtain the photothermal fabric.

[0008] S2: The photothermal fabric is immersed in the casting solution, and then immersed in the nanocrystal aqueous solution for reaction. After the reaction is completed, it is washed and dried to obtain the superhydrophilic photothermal fabric.

[0009] S3: Immerse the superhydrophilic photothermal fabric in a porous nanocrystal-methanol solution, wash and dry after the reaction is complete to obtain the superhydrophilic oil-resistant photothermal fabric.

[0010] Furthermore, in step S1, the photothermal polymer includes one or more of polydopamine, polypyrrole, polyaniline, and polythiophene.

[0011] Furthermore, in step S1, the concentration of the photothermal polymer in the aqueous solution of the photothermal polymer is 0.20 to 0.80 mol / L.

[0012] Furthermore, in step S2, the casting solution includes tannic acid, polyethyleneimine, and ferric chloride (TA / PEI / Fe). 3+ ).

[0013] Furthermore, the mass ratio of tannic acid, polyethyleneimine, and ferric chloride is 1-2:5:1.

[0014] Furthermore, in step S2, the concentration of nanocrystals in the nanocrystal aqueous solution is 0.10–0.40 g / L.

[0015] Furthermore, in step S3, the porous nanocrystals are metal-organic framework compounds, including one or more of UiO-66, MIL-101(Fe), ZIF-8, and ZIF-67.

[0016] Furthermore, in step S1, the fabric is placed in an aqueous solution containing a photothermal polymer for reaction at a temperature of -10 to 37°C; in steps S2 and S3, the reaction temperature is room temperature.

[0017] A superhydrophilic, oil-resistant, photothermal fabric is prepared using the method described above.

[0018] Furthermore, this superhydrophilic, oil-resistant photothermal fabric, when used in a sun-facing suspended solar seawater evaporator, achieves an evaporation rate of 2.10 kg / m³ under one times the light intensity. -2 h -1 After evaporation for 9 hours at one times the light intensity, the oil retention rate can reach 87%, and only a very small number of oil droplets remain in the emulsion after evaporation. Therefore, this photothermal fabric has important application value in the field of high-efficiency solar seawater desalination.

[0019] This invention uses cotton fabric, which has strong water absorption, high mechanical strength, low price, and easy modification, as the base of a photothermal oil-resistant material. An easily synthesized polymer nanoparticle with strong light absorption properties is introduced as a photothermal layer through in-situ polymerization, ensuring the excellent photothermal conversion performance of the composite material. Utilizing surface coating technology, the superhydrophilic layer is prepared by applying the superhydrophilic nanocrystals to the fabric using the adhesion of the casting solution, constructing a robust and dense superhydrophilic coating on the surface of the photothermal layer. This coating effectively prevents oil adhesion without affecting the photothermal performance of the material, thus reducing the degree of oil contamination. By growing a suitable amount of nanocrystal bumps on the superhydrophilic surface, oil-water separation is achieved. During the transport of oily seawater, oil droplets are continuously captured and adsorbed on the surface of the nanocrystals, aggregating into larger droplets and being separated to the higher side, while water molecules still pass through the superhydrophilic coating normally and rapidly, undergoing efficient water evaporation.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] (1) The preparation process of this invention is simple, fast, and the reaction conditions are mild, which can realize large-scale production.

[0022] (2) In terms of performance, the present invention achieves efficient light absorption, excellent oil adhesion prevention and effective oil retention, providing a feasible strategy for achieving efficient evaporation in oily seawater environment and broadening the practical application scenarios of photothermal materials for seawater desalination. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the preparation process of a superhydrophilic, oil-resistant, photothermal fabric, as described in Example 1.

[0024] Figure 2 The appearance morphology and SEM image of a superhydrophilic, oil-resistant photothermal fabric prepared in Example 1;

[0025] Figure 3 XPS spectra of cotton / polypyrrole / cellulose nanocrystals and cotton / polypyrrole / cellulose nanocrystals@ZIF-8 prepared in Example 1;

[0026] Figure 4 High-resolution XPS spectrum of Zn 2p at the Zn content of a superhydrophilic, oil-resistant photothermal fabric prepared in Example 1;

[0027] Figure 5 High-resolution XPS spectrum at N1s of a superhydrophilic, oil-resistant photothermal fabric prepared in Example 1;

[0028] Figure 6 Comparison of light absorption efficiency of a superhydrophilic, oil-resistant photothermal fabric prepared in Example 1;

[0029] Figure 7 The photothermal temperature rise diagram and the infrared image of the stable state of the superhydrophilic and oil-resistant photothermal fabric prepared in Example 1 are shown in the figure.

[0030] Figure 8 The images show the photothermal temperature rise from room temperature to equilibrium temperature and the stable state of the superhydrophilic, oil-resistant photothermal fabric prepared in Example 1 under humid conditions.

[0031] Figure 9 A comparison diagram of the water contact angle of a superhydrophilic, oil-resistant, photothermal fabric prepared in Example 1;

[0032] Figure 10 Comparison of underwater oil contact angles on the surfaces of the superhydrophilic flexible oil-resistant photothermal materials prepared in Example 1 using peanut oil, soybean oil, olive oil, cyclohexane, and chloroform;

[0033] Figure 11 A schematic diagram of the apparatus used for testing the seawater evaporation performance of a superhydrophilic, oil-resistant photothermal fabric prepared in Example 1;

[0034] Figure 12 The figure shows the mass loss of a superhydrophilic, oil-resistant photothermal fabric prepared in Example 1 in various oily seawater.

[0035] Figure 13 This is a comparison chart of the evaporation rates of a superhydrophilic, oil-resistant photothermal fabric prepared in Example 1 in oily seawater;

[0036] Figure 14 The figure shows the results of a cycling experiment in oily seawater on a superhydrophilic, oil-resistant photothermal fabric prepared in Example 1.

[0037] Figure 15 The retention rate of oily seawater by a superhydrophilic, oil-resistant photothermal fabric prepared in Example 1 at different evaporation times;

[0038] Figure 16 A comparison chart of the total organic carbon (TOC) content of the original emulsion and the collected distilled water;

[0039] Figure 17 Microscopic comparison of the original emulsion and the low-tank emulsion collected after evaporation. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0041] The following embodiments are implemented based on the above-described technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0042] The following are more detailed implementation examples, which further illustrate the technical solution of the present invention and the technical effects that can be obtained.

[0043] In the following embodiments, unless otherwise specified, the raw materials, reagents or processing techniques are all conventional commercial products or conventional processing techniques in the art.

[0044] Example 1

[0045] This embodiment provides a superhydrophilic, oil-resistant photothermal fabric and its preparation (e.g., ...). Figure 1 As shown), its preparation method is as follows:

[0046] (1) First, take 0.16g of fabric (cotton fabric: purchased from Shiyi Changfeng Textile Co., Ltd., fabric size 2×10cm) 2 The material is immersed in 20 ml of 0.8 mol / L ammonium persulfate solution (3.648 g of ammonium persulfate added to 20 mL of deionized water), and then 20 ml of pyrrole solution (0.62 mol / L) is added dropwise to the surface and the reaction is carried out for 24 h. After the reaction is completed, the material is ultrasonically cleaned with ethanol (5 min at room temperature, ultrasonic intensity of 100%), rinsed repeatedly with deionized water, and then dried (60℃ for 30 min) to obtain the photothermal fabric.

[0047] Principle: The cotton fabric is soaked in an ammonium persulfate solution, and the surface of the fabric is completely wetted by the ammonium persulfate. Then, pyrrole is dropped onto the surface of the fabric. The ammonium persulfate can catalyze the polymerization reaction of pyrrole, and finally, polypyrrole nanoparticles are grafted onto the surface of the cotton fabric.

[0048] (2) The photothermal fabric is placed in the casting solution (the casting solution contains TA / PEI / Fe). 3+ After soaking in a solution with a mass ratio of 2:5:1 for 8 hours, the fabric was removed, rinsed with deionized water, and set aside. The photothermal fabric soaked in the casting solution was then immersed in 60 ml of a 0.78 g / L nanocrystal solution (nanocrystals purchased from Shanghai Maclean Biochemical Technology Co., Ltd.), shaken for 5 hours, washed with an equal volume mixture of ethanol and deionized water, and finally dried in an oven (45℃ for 15 minutes) to obtain the superhydrophilic photothermal fabric Cotton / Ppy / CNC (cotton / polypyrrole / cellulose nanocrystals).

[0049] The preparation method of the casting solution is as follows: Weigh 0.727g of tris(hydroxymethyl)aminomethane (Tris), add 60mL of deionized water and stir until completely dissolved. The resulting solution is designated as solution A. Weigh 1.2g of tannic acid (TA), 3g of FeCl3, and 0.6g of polyethyleneimine (PEI) and add them to solution A. Stir until completely mixed to obtain the casting solution (TA / PEI / FeCl3). 3+ ).

[0050] Principle: The cotton fabric is immersed in a casting solution with adhesive properties, which allows the superhydrophilic nanocrystals to be firmly wrapped around the polypyrrole nanoparticles without affecting the photothermal properties of the fabric.

[0051] (3) The prepared superhydrophilic photothermal fabric was immersed in 20 ml of 0.4 mol / L zinc nitrate-methanol solution until the zinc nitrate solution completely soaked into the cotton fabric. Then, 20 ml of 0.56 mol / L dimethylimidazole-methanol solution was poured into the above solution, and the mixture was stirred at room temperature for 1.5 h to generate ZIF-8 on the cotton fabric. After the reaction was completed, the fabric was washed and dried in an oven (drying at 45℃ for 30 min) to obtain the superhydrophilic flexible oil-stained photothermal fabric Cotton / Ppy / CNC@ZIF-8 (cotton / polypyrrole / cellulose nanocrystals@ZIF-8).

[0052] Principle: Cotton fabrics are immersed in zinc nitrate-methanol and dimethylimidazole-methanol solutions respectively to react and grow an appropriate amount of ZIF-8 nanocrystal bumps on the fabric surface. Since negatively charged oil droplets can be continuously captured and adsorbed by positively charged ZIF-8 nanocrystals, the material is endowed with excellent oil stain resistance.

[0053] This embodiment also includes performance testing and characterization of the obtained superhydrophilic, oil-resistant photothermal fabric, specifically including:

[0054] (1) SEM characterization

[0055] like Figure 2 The image shown is a physical photograph of the superhydrophilic, oil-resistant, photothermal fabric obtained in Example 1, and SEM images at different magnifications: [Image showing the fabric]. Figure 2 (b) and 2(c) show that the superhydrophilic flexible anti-oil photothermal material consists of regular dodecahedral nanoparticles. Figure 2 (d) The particles grow evenly dispersed on the fiber surface, with a certain distance between them, which is conducive to water penetration.

[0056] (2) The sample surface was analyzed using XPS, such as... Figure 3 As shown, characteristic peaks of C1s, N1s, O1s, and Fe 2p appeared in the XPS spectrum of Cotton / Ppy / CNC (cotton / polypyrrole / cellulose nanocrystals). In addition to the above characteristic peaks, new Zn 2p signal peaks also appeared at 1047 eV and 1019 eV in the spectrum of Cotton / Ppy / CNC@ZIF-8 (CPC@ZIF-8: cotton / polypyrrole / cellulose nanocrystals@ZIF-8). (Zn 2p high-resolution XPS spectrum) Figure 4Two peaks appeared at 1045 eV and 1022 eV, belonging to Zn 2p3 / 2 and Zn 2p1 / 2 respectively. In the N1s spectrum ( Figure 5 By fitting experimental data, characteristic peaks were detected at 400 eV and 398.6 eV. The presence of NH at 400 eV is mainly due to the presence of CNC coating on the surface of cotton fiber cloth, while the characteristic peak at 398.6 eV is attributed to the binding energy of zinc nitride (N-Zn).

[0057] (3) The light absorption efficiency of the superhydrophilic, oil-resistant photothermal fabric was measured using a UV-Vis-NIR diffuse reflectance spectrometer, and it reached 93.38%. The results are shown in the attached figure. Figure 6 As shown, the CPC@ZIF-8 prepared in this embodiment: cotton / polypyrrole / cellulose nanocrystals@ZIF-8 has superior solar absorption performance compared to raw cotton. AM1.5G is a standard solar energy spectrum for reference, which is beneficial to achieving high photothermal conversion and improved evaporation efficiency.

[0058] (4) Photothermal temperature rise diagram and steady-state infrared diagram of superhydrophilic, oil-resistant photothermal fabric

[0059] Under simulated sunlight with one times the intensity, the superhydrophilic, oil-resistant photothermal fabric rapidly increased from room temperature (26°C) to an equilibrium temperature of 62.9°C within a short period of time. The results are as follows: Figure 7 (Heating under dry conditions) Figure 8 As shown in the (heating under humid conditions) diagram, this superhydrophilic, oil-resistant photothermal fabric exhibits excellent photothermal conversion performance.

[0060] The wet state involves suspending and fixing the fabric between two PMMA high and low tanks (with a height difference of 1cm) using small magnets. Deionized water is added to the high tank so that the liquid level just covers the edge of the cotton fabric. The fabric uses its own capillary action and gravity to transport water from the high tank to the low tank, thus making the fabric wet.

[0061] (5) Water contact angle and underwater oil contact angle test of superhydrophilic and oil-resistant photothermal fabric:

[0062] As attached Figure 9 As shown, pure fabrics have poor surface hydrophilicity. Figure 9 (a) The hydrophilicity of the fiber surface is greatly improved after the addition of the photothermal layer and the superhydrophilic layer. Figure 9 (b)- Figure 9 (c) The surface still exhibits superhydrophilicity after being modified with nanocrystal bumps. Figure 9 (d);

[0063] Figure 10The underwater oil contact angles of the superhydrophilic, oil-resistant photothermal material prepared in Example 1 are peanut oil, soybean oil, olive oil, cyclohexane, and chloroform. The contact angles of the oil droplets on the fabric surface are all greater than 150°, indicating that the oil droplets are blocked on the surface of the hydration layer, thus achieving underwater superoleophobicity.

[0064] (6) Testing of the evaporation performance and cycle stability of superhydrophilic, oil-resistant, photothermal fabrics containing oil and seawater:

[0065] Environmental conditions maintained during evaporation tests: room temperature maintained at approximately 25°C, humidity: 35%–50%. All solar-powered seawater evaporation experiments were conducted in a suspended apparatus. The experimental setup is as follows: Figure 11 As shown: Place two PMMA water tanks with dimensions of 8×3×5cm and 8×3×4cm respectively (height difference of 1cm) horizontally, and place a 2×10cm... 2 The superhydrophilic, oil-resistant, photothermal fabric is suspended by magnets between two high and low grooves and kept taut. The distance between the two grooves is adjusted to ensure a projected area of ​​2×3cm. 2 The angle between the fabric and the horizontal ground is approximately 20° (α = 20°). The high tank is filled with a prepared 3.5wt% NaCl simulated seawater solution, so that the liquid level just covers the edge of the fabric. No solution is added to the low tank.

[0066] The entire apparatus was placed on an electronic balance, and the mass change of the entire apparatus was recorded after different evaporation times.

[0067] The results are attached. Figure 12 As shown, Figure 12 To illustrate the mass loss of the superhydrophilic, oil-resistant photothermal material in various types of oily seawater, this test used three types of oil: peanut oil (brand: Longda, manufacturer: Shandong Longda Vegetable Oil Co., Ltd.), soybean oil (brand: Jinlongyu, manufacturer: Zihai Kerry Food Marketing Co., Ltd.), and olive oil (brand: Earl Extra Virgin Olive Oil, manufacturer: Beijing Zhongqi Huaye Food Co., Ltd.). The oily seawater was prepared as follows: oil:water = 1:100 (5ml of oil: 500ml of 3.5wt% NaCl solution), where the 3.5wt% NaCl solution was used as the simulated seawater.

[0068] The results showed that the evaporation rate of the photothermal fabric in various oil-contaminated seawaters was basically consistent with that in pure brine, maintaining a high evaporation rate. Furthermore, the evaporation performance of different materials in the same peanut oil-simulated seawater was also tested. Figure 13 This indicates that the superhydrophilic, oil-resistant photothermal material prepared by this invention is minimally affected by oil during evaporation in oily seawater, and can achieve the highest evaporation rate.

[0069] To demonstrate the stability of the superhydrophilic, oil-resistant photothermal fabric in long-term operation in oily seawater, a cyclic experiment was conducted. An evaporation test was performed for 32 hours in a peanut oil-seawater system under simulated sunlight with one times the intensity of sunlight. Figure 14 The results show that the evaporation rate of oily seawater in the last three cycles (3 hours per cycle, the same below) is basically consistent with that in the first cycle, indicating that the superhydrophilic and oil-resistant photothermal material of the present invention can still maintain high efficiency and durability in the presence of oil.

[0070] (7) Superhydrophilic, oil-resistant photothermal fabric applied to oil separation rate testing in suspension devices

[0071] Environmental conditions maintained during evaporation tests: room temperature maintained at approximately 25℃, humidity: 35%–50%. All solar-powered seawater evaporation experiments were conducted in a suspended device, with a 2×10cm... 2 The superhydrophilic, oil-resistant, photothermal fabric is suspended by magnets between two high and low grooves and kept taut. The distance between the two grooves is adjusted to ensure a projected area of ​​2×3cm. 2 The angle between the fabric and the horizontal ground is approximately 20° (α = 20°). The high tank is filled with a prepared peanut oil-seawater mixture (oil:seawater = 1:100, using a 3.5wt% NaCl solution as a simulated seawater), so that the liquid level just covers the edge of the fabric. No solution is needed in the low tank.

[0072] The suspension device was placed in a sealed plexiglass chamber for evaporation experiments. During the evaporation process, samples of the emulsion before and after the reaction, as well as clean water samples from the evaporation device, were collected. The total organic carbon (TOC) content in the collected emulsions was determined using a total organic carbon analyzer, and the oil rejection rate was calculated based on the TOC content of different emulsions. The results are attached. Figure 15 , 16 As shown, Figure 15 The figure shows the retention rates of CPC@ZIF-8 for oily seawater at different evaporation times. As can be seen from the figure, the retention rates after 3h, 6h, and 9h of evaporation reached 68%, 73%, and 87%, respectively. With prolonged evaporation time, the vast majority of the oil was retained and concentrated on the high-side tank, while only a small amount remained on the CPC@ZIF-8 on the high-side tank. Only a trace amount of oil flowed to the low-side tank, thus achieving separation. Furthermore, combined with the results of the circulating evaporation experiment in simulated oily seawater, the small amount of oil remaining on the CPC@ZIF-8 on the high-side tank did not affect the normal evaporation behavior. After each cycle, simple ethanol washing and drying were performed before the material was put into the next cycle for normal evaporation. In addition to determining the oil retention rate of this material, the total organic carbon (TOC) content of the original emulsion and distilled water in the closed evaporation device was also determined at different evaporation times (3h, 6h, 9h). Figure 16It can be seen that the TOC values ​​of the distilled water collected after 3h, 6h and 9h of evaporation were 18mg / L, 16mg / L and 20mg / L respectively, which were 38 to 45 times lower than the TOC of the initial stock solution. This indicates that CPC@ZIF-8 has excellent ability to prevent oil pollution and produce clean water by photothermal means in the real environment of oily seawater.

[0073] (8) Microscopic tests before and after oil-containing seawater separation

[0074] To more intuitively demonstrate the excellent oil separation performance of the superhydrophilic, oil-resistant photothermal material in oily seawater, the initial high-tank emulsion (as the original emulsion) and the post-evaporation low-tank emulsion (as the post-evaporation emulsion) from the oily seawater evaporation experiment in step (7) above were observed under a microscope. The results are attached. Figure 17 As shown, the solution after evaporation in the suspension device is more transparent and nearly colorless than the original solution, as can be observed with the naked eye (Figure a: left side of the original emulsion, right side of the emulsion after evaporation). Further staining of the solution and observation under a microscope revealed a large number of oil droplets of varying sizes in the original solution (Figure b), while no obvious oil droplets were present in the emulsion after evaporation, with only a very few small oil droplets visible in the field of view (Figure c). This indicates the excellent oil-water separation effect of the superhydrophilic flexible anti-oil photothermal material fabric.

[0075] Therefore, the superhydrophilic flexible oil-resistant photothermal material prepared in this embodiment can be applied to solar seawater evaporators for desalination of solar-powered seawater due to the addition of polypyrrole.

[0076] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a super-hydrophilic and oil-repellent light heat fabric, characterized in that, The method comprises the following steps: S1: placing the fabric in an aqueous solution containing a photothermal polymer for reaction, washing and drying after the reaction is completed to obtain a photothermal fabric; S2: immersing the photothermal fabric in a casting solution, then immersing it in an aqueous solution of cellulose nanocrystals for reaction, washing and drying after the reaction is completed to obtain a super-hydrophilic photothermal fabric; S3: immersing the super-hydrophilic photothermal fabric in a porous nanocrystal-methanol solution, washing and drying after the reaction is completed to obtain the super-hydrophilic oil-resistant photothermal fabric; In step S2, the casting solution comprises tannic acid, polyethyleneimine and ferric chloride; In step S3, the porous nanocrystal is a metal organic framework compound, comprising one or more of UiO-66, MIL-101(Fe), ZIF-8 and ZIF-67.

2. A process for the preparation of super-hydrophilic, oil-repellent, photo-thermal fabric according to claim 1, characterized in that, In step S1, the photothermal polymer comprises one or more of polydopamine, polypyrrole, polyaniline and polythiophene.

3. The method for preparing the superhydrophilic, oil-resistant, photothermal fabric according to claim 1, characterized in that, In step S1, the concentration of the photothermal polymer in the aqueous solution is 0.20-0.80 mol / L.

4. The method of claim 1, wherein the super-hydrophilic, oil-repellent, photo-thermal fabric is prepared by the steps of: The mass ratio of the tannic acid, polyethyleneimine and ferric chloride is 1-2:5:

1.

5. The method for preparing the superhydrophilic, oil-resistant, photothermal fabric according to claim 1, characterized in that, In step S2, the concentration of the nanocrystal in the aqueous solution is 0.10-0.40 g / L.

6. The method of claim 1, wherein the super-hydrophilic, oil-repellent, photo-thermal fabric is prepared by the steps of: In step S1, the reaction temperature is-10-37℃; in steps S2 and S3, the reaction temperature is room temperature.

7. A super-hydrophilic, oil-repellent, light-to-heat fabric, characterized in that, The method is prepared according to any one of claims 1-6.

8. Use of the super-hydrophilic, oil-repellent, photo-thermal fabric according to claim 7, characterized in that, The super-hydrophilic oil-resistant photothermal fabric is used for a solar sea water evaporator.

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