A gel composite fabric for air water harvesting and a method of making the same

Abstract

The present application relates to the field of adsorbent assisted water extraction technology, and particularly relates to a gel composite fabric for air water extraction and a preparation method thereof. The method specifically comprises the following steps: ultrasonic treatment of the fabric in a sodium hydroxide solution with a concentration of 20-40 g / L, then repeated washing of the fabric with deionized water until neutral, and drying to obtain a pretreated fabric; mixing of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (DMAPS), a hygroscopic agent and a crosslinking agent in deionized water, and nitrogen treatment to obtain a treatment liquid; preparation of a persulfate initiator aqueous solution, and uniform spraying of the persulfate initiator aqueous solution on the pretreated fabric, then airing of the fabric at room temperature, drying to obtain a persulfate initiator loaded fabric, and then immersion of the fabric in the treatment liquid for reaction to obtain a hydrogel composite fabric material with high hygroscopic and water-retention performance. The gel composite fabric prepared by the method has high adsorption capacity and stable hygroscopic performance, and can be widely applied in the field of air water extraction.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorbent-assisted water extraction, and in particular to a gel composite fabric for air water extraction and a preparation method thereof. Background Art

[0002] The atmosphere contains nearly 13 trillion tons of renewable freshwater, unrestricted by geography and climate, making it a highly anticipated emerging water source. Air-to-water technology converts atmospheric water into liquid freshwater. Using this technology to capture atmospheric water and use it for freshwater production can provide a sustainable water source for production, life, and agricultural development, with significant practical implications for arid regions and extreme water shortages.

[0003] Adsorbent-assisted water extraction (ADA) is one of the most commonly used air-to-water extraction technologies. It utilizes ADA materials to capture and enrich moisture from the air, releasing it into liquid water through desorption. With its low cost and minimal equipment requirements, it has attracted widespread attention as a green and energy-efficient ADA technology. The adsorbent used in ADA materials is crucial, determining freshwater production capacity. Commonly used adsorbents include metal-organic frameworks (MOFs), hygroscopic salts such as CaCl2 and LiCl, silica gel, and zeolites. However, these adsorbents suffer from high production costs and high desorption energy consumption.

[0004] Compared to conventional desiccant materials, fabrics offer significant potential in the field of air-to-water extraction due to their designability, low cost, rapid heat transfer, and lightweight properties. In particular, fabrics possess a designable, multi-level structure, which greatly enhances the diversity of their shapes and structures, expanding the contact area between the fabric material and the outside world and improving their water absorption and transfer performance. However, fabrics' inherent moisture absorption rate is limited, failing to meet the high moisture absorption requirements of air-to-water extraction materials. Loading desiccant materials with these materials can overcome this limitation. However, fabrics have a low adsorption capacity and insufficient water storage capacity, making them unable to accommodate excessive amounts of water. Furthermore, the fabric and desiccant cannot form an effective bond, leading to leakage of the desiccant during the moisture absorption process, resulting in a decrease in moisture absorption performance and limiting their application in air-to-water extraction.

[0005] To address the above shortcomings, conventional solutions mainly include ultraviolet-induced grafting and plasma-induced grafting. Functional groups are introduced into the fabric surface through light, heat, and high-energy rays, giving the material high hygroscopic properties. However, due to the limitations of its own adsorption capacity, the water storage capacity of the material cannot be increased. In addition, the cumbersome operation and expensive equipment also limit its industrial production. However, compounding the fabric with a high-water-storage material through a simple process can effectively solve the drawbacks of conventional methods and prepare a composite fabric with efficient moisture absorption and water retention properties.

[0006] Therefore, developing a composite fabric water extraction product for air water extraction has important practical significance and application value. Summary of the Invention

[0007] The present invention aims to address the low adsorption capacity and moisture absorbent leakage issues associated with current fabric-based air water extraction, as noted in the background art. Leveraging the superior water storage and retention properties and dynamic coordination of hydrogels, the present invention provides a gel composite fabric for air water extraction and a specific preparation method. The gel composite fabric prepared by this method exhibits efficient moisture absorption and retention, stable hygroscopicity, and a short synthetic route and simple manufacturing process, enabling mass production of low-cost air water extraction materials.

[0008] Specifically, the present invention adopts the following technical solutions:

[0009] A method for preparing a gel composite fabric for air water extraction, the method specifically comprising the following steps: (1) firstly, ultrasonically treating 1.5-6.0 g of a fabric (CF) in a sodium hydroxide solution with a concentration of 20-40 g / L for 1-2 hours, then repeatedly washing the fabric with deionized water until it becomes neutral, and then drying the fabric at 70-80°C for 8-12 hours to obtain a pretreated fabric;

[0010] (2) 8.0-14.0 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide (DMAPS), a desiccant, and a cross-linking agent were mixed evenly in 100 mL of deionized water, and nitrogen was introduced into the mixture for 45-75 minutes to obtain a treated solution;

[0011] (3) preparing a persulfate initiator aqueous solution, and evenly spraying the persulfate initiator aqueous solution on the pretreated fabric obtained in step (1), and then airing the fabric in a ventilated place at room temperature for 10-12 hours to obtain an initiator-loaded fabric;

[0012] (4) Immersing the initiator-loaded fabric obtained in step (3) in the treatment solution obtained in step (2), reacting at 60-70° C. for 8-10 hours, thereby preparing a hydrogel composite fabric material with high moisture absorption and water retention properties.

[0013] Furthermore, the added amount of the desiccant is 10-50% of the mass of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide.

[0014] Furthermore, the desiccant is lithium chloride (LiCl), calcium chloride (CaCl2) or lithium chloride modified with ethanolamine (E-LiCl).

[0015] Furthermore, the molar ratio of the cross-linking agent to [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide is 0.02-0.05:1.

[0016] Furthermore, the cross-linking agent is N,N'-methylenebisacrylamide (MBAA).

[0017] Furthermore, the molar ratio of the initiator to [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide is 0.01-0.04:1.

[0018] Furthermore, the initiator is ammonium persulfate or potassium persulfate.

[0019] Furthermore, the amount of the initiator-loaded fabric added in step (4) is 20-40% of the mass of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide.

[0020] Furthermore, in step (4), the amount of the initiator-loaded fabric added is 35-40% of the mass of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide.

[0021] A gel composite fabric for air water extraction is prepared by the above-mentioned preparation method.

[0022] In the above-mentioned embodiment of the present invention, the hydrogel is a highly absorbent porous material with a three-dimensional network structure. The hydrogel material exhibits excellent water absorption properties, capable of absorbing tens to hundreds of times its own mass in water. Furthermore, the hydrogel effectively retains water, preventing its rapid release. Furthermore, a dynamic coordination is formed between the hydrogel and the hygroscopic agent, effectively preventing the hygroscopic agent from leaking, resulting in the material exhibiting stable hygroscopic capacity.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The preparation method of the present invention is to load the hydrogel into the fabric, and utilize the presence of the hydrogel to enhance the water storage and water retention performance of the material and improve the adsorption capacity of the material; and through the dynamic coordination between the hydrogel and the desiccant, the leakage of the desiccant is effectively prevented, thereby reducing the attenuation of the fabric's moisture absorption performance;

[0025] The gel composite fabric prepared by the method of the present invention not only has a high adsorption capacity but also has stable moisture absorption performance, and can be widely used in the field of air water extraction;

[0026] In addition, the preparation method of the present invention does not involve complex equipment, the raw materials are cheap, and the process is simple and easy, which is conducive to the market development of air water extraction materials and further expands the application scenarios of fabric materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a physical picture of the hydrogel composite fabric material prepared by the present invention.

[0028] Figure 2 This is a scanning electron microscope comparison of conventional cotton fabric and the hydrogel composite fabric material prepared in the present invention;

[0029] Wherein, a is the hydrogel composite fabric material prepared by the present invention, and b is conventional cotton fabric.

[0030] Figure 3 This is a schematic diagram of the principle of the hydrogel composite fabric material prepared by the present invention.

[0031] Figure 4 This is a comparison diagram of the moisture absorption stability of the hydrogel composite fabric material and the moisture-absorbing fabric prepared by the present invention; wherein a is the actual image after moisture absorption, and b is the cyclic stability image. DETAILED DESCRIPTION

[0032] Representative embodiments will now be further refined. It should be understood that the following description is not intended to limit the embodiments to a preferred embodiment. On the contrary, it is intended to encompass alternatives, modifications, and equivalents that may be included within the spirit and scope of the embodiments defined by the appended claims.

[0033] The present invention provides a gel composite fabric for air water extraction; the gel composite fabric is prepared by the following method:

[0034] (1) First, 1.5-6.0 g of fabric (CF) was ultrasonically treated in a sodium hydroxide solution with a concentration of 20-40 g / L for 1-2 hours, and then the fabric was repeatedly washed with deionized water until neutral, and then dried at 70-80 ° C for 8-12 hours to obtain a pretreated fabric;

[0035] (2) 8.0-14.0 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide (DMAPS), a desiccant and a cross-linking agent were mixed evenly in 100 mL of deionized water, and nitrogen was introduced for 45-75 minutes to obtain a treatment solution; the amount of the desiccant added was 10-50% of the mass of DMAPS; the desiccant was lithium chloride (LiCl), calcium chloride (CaCl2) or lithium chloride modified with ethanolamine (E-LiCl), etc.; the molar ratio of the cross-linking agent to DMAPS was 0.02-0.05:1; the cross-linking agent was N,N'-methylenebisacrylamide (MBAA);

[0036] (3) preparing an aqueous persulfate initiator solution, and uniformly spraying the aqueous persulfate initiator solution onto the pretreated fabric obtained in step (1), and then airing the fabric in a ventilated place at room temperature for 10-12 hours to obtain an initiator-loaded fabric; the molar ratio of the initiator to DMAPS is 0.01-0.04:1; wherein the initiator is ammonium persulfate or potassium persulfate, etc.

[0037] (4) Immersing the initiator-loaded fabric obtained in step (3) in the treatment solution obtained in step (2), and reacting at 60-70°C for 8-10 hours to prepare a gel composite fabric for air water extraction. The amount of initiator-loaded fabric added is 20-40% of the mass of DMAPS, and preferably 35-40%.

[0038] Example 1:

[0039] The applicant prepared a gel composite fabric for air water extraction through a specific case, and the steps are as follows:

[0040] (1) First, 4.0 g of CF was ultrasonically treated in a 30 g / L sodium hydroxide solution for 1 hour. The parameters of the cotton fabric were: yarn count 21S, density 30*28; then, the cotton fabric was repeatedly washed with deionized water until neutral, and then dried at 75°C for 8 hours to obtain the pretreated fabric;

[0041] (2) 11.0 g of DMAPS, desiccant LiCl, and crosslinker MBAA were mixed evenly in 100 mL of deionized water. The amount of desiccant LiCl added was 27% of the mass of DMAPS, and the molar ratio of crosslinker MBAA to DMAPS was 0.05:1. Nitrogen was introduced into the mixture for 45 minutes to obtain a treated solution.

[0042] (3) preparing an ammonium persulfate initiator aqueous solution at a molar ratio of initiator to DMAPS of 0.01:1, and spraying the ammonium persulfate initiator aqueous solution evenly on the pretreated fabric obtained in step (1), and then airing the fabric in a ventilated place at room temperature for 10 hours to obtain an initiator-loaded fabric;

[0043] (4) Immersing the initiator-loaded fabric obtained in step (3) in the treatment solution obtained in step (2), wherein the amount of initiator-loaded fabric added is 36% of the mass of DMAPS; reacting at 65° C. for 8 hours to prepare a gel composite fabric material with high moisture absorption and water retention performance, such as Figure 1 .

[0044] Gel composite fabric material has excellent moisture absorption performance, all of which is attributed to the introduction of gel (such as Figure 2 ) and rational design of composite materials (e.g. Figure 3 ).

[0045] Example 2:

[0046] A gel composite fabric for air water extraction is prepared in the following steps:

[0047] (1) First, 4.0 g of CF was ultrasonically treated in a 30 g / L sodium hydroxide solution for 1 hour. The parameters of the cotton fabric were: yarn count 21S, density 30*28; then, the cotton fabric was repeatedly washed with deionized water until neutral, and then dried at 75°C for 8 hours to obtain the pretreated fabric;

[0048] (2) 11.0 g of DMAPS, desiccant LiCl, and crosslinker MBAA were mixed evenly in 100 mL of deionized water. The amount of desiccant LiCl added was 27% of the mass of DMAPS, and the molar ratio of crosslinker MBAA to DMAPS was 0.05:1. Nitrogen was introduced into the mixture for 45 minutes to obtain a treated solution.

[0049] (3) preparing a potassium persulfate initiator aqueous solution at a molar ratio of initiator to DMAPS of 0.01:1, and uniformly spraying the potassium persulfate initiator aqueous solution onto the pretreated fabric obtained in step (1), and then airing the fabric in a ventilated place at room temperature for 10 hours to obtain an initiator-loaded fabric;

[0050] (4) Immersing the initiator-loaded fabric obtained in step (3) in the treatment solution obtained in step (2), wherein the amount of initiator-loaded fabric added is 36% of the mass of DMAPS; reacting at 65°C for 8 hours to prepare a gel composite fabric material with high moisture absorption and water retention properties.

[0051] Example 3:

[0052] A gel composite fabric for air water extraction is prepared in the following steps:

[0053] (1) First, 4.0 g of CF was ultrasonically treated in a 30 g / L sodium hydroxide solution for 1 hour. The parameters of the cotton fabric were: yarn count 21S, density 30*28; then, the cotton fabric was repeatedly washed with deionized water until neutral, and then dried at 75°C for 8 hours to obtain the pretreated fabric;

[0054] (2) 11.0 g of DMAPS, desiccant E-LiCl, and crosslinker MBAA were mixed evenly in 100 mL of deionized water. The amount of E-LiCl added was 27% of the mass of DMAPS, and the molar ratio of crosslinker MBAA to DMAPS was 0.05:1. Nitrogen was introduced for 45 minutes to obtain a treated solution.

[0055] (3) preparing an ammonium persulfate initiator aqueous solution at a molar ratio of initiator to DMAPS of 0.01:1, and spraying the ammonium persulfate initiator aqueous solution evenly on the pretreated fabric obtained in step (1), and then airing the fabric in a ventilated place at room temperature for 10 hours to obtain an initiator-loaded fabric;

[0056] (4) Immersing the initiator-loaded fabric obtained in step (3) in the treatment solution obtained in step (2), wherein the amount of initiator-loaded fabric added is 36% of the mass of DMAPS; reacting at 65°C for 8 hours to prepare a gel composite fabric material with high moisture absorption and water retention properties.

[0057] Example 4:

[0058] A gel composite fabric for air water extraction is prepared in the following steps:

[0059] (1) First, 1.8 g of CF was ultrasonically treated in a sodium hydroxide solution with a concentration of 30 g / L for 1 hour. The parameters of the cotton fabric were: yarn count 40S, density 28*24; then, the cotton fabric was repeatedly washed with deionized water until neutral, and then dried at 75°C for 8 hours to obtain the pretreated fabric;

[0060] (2) 14.0 g of DMAPS, desiccant LiCl, and crosslinker MBAA were mixed evenly in 100 mL of deionized water. The amount of desiccant LiCl added was 27% of the mass of DMAPS, and the molar ratio of crosslinker MBAA to DMAPS was 0.05:1. Nitrogen was introduced into the mixture for 45 minutes to obtain a treated solution.

[0061] (3) preparing an ammonium persulfate initiator aqueous solution at a molar ratio of initiator to DMAPS of 0.01:1, and spraying the ammonium persulfate initiator aqueous solution evenly on the pretreated fabric obtained in step (1), and then airing the fabric in a ventilated place at room temperature for 10 hours to obtain an initiator-loaded fabric;

[0062] (4) Immersing the initiator-loaded fabric obtained in step (3) in the treatment solution obtained in step (2), wherein the amount of initiator-loaded fabric added is 21% of the mass of DMAPS; reacting at 65°C for 8 hours to prepare a gel composite fabric material with high moisture absorption and water retention properties.

[0063] Example 5:

[0064] A gel composite fabric for air water extraction is prepared in the following steps:

[0065] (1) First, 4.0 g of CF was ultrasonically treated in a 30 g / L sodium hydroxide solution for 1 hour. The parameters of the cotton fabric were: yarn count 21S, density 30*28; then, the cotton fabric was repeatedly washed with deionized water until neutral, and then dried at 75°C for 8 hours to obtain the pretreated fabric;

[0066] (2) 11.0 g of DMAPS, desiccant LiCl, and crosslinker MBAA were mixed evenly in 100 mL of deionized water. The amount of desiccant LiCl added was 36% of the mass of DMAPS, and the molar ratio of crosslinker MBAA to DMAPS was 0.05:1. Nitrogen was introduced into the mixture for 45 minutes to obtain a treated solution.

[0067] (3) preparing an ammonium persulfate initiator aqueous solution at a molar ratio of initiator to DMAPS of 0.01:1, and spraying the ammonium persulfate initiator aqueous solution evenly on the pretreated fabric obtained in step (1), and then airing the fabric in a ventilated place at room temperature for 10 hours to obtain an initiator-loaded fabric;

[0068] (4) Immersing the initiator-loaded fabric obtained in step (3) in the treatment solution obtained in step (2), wherein the amount of initiator-loaded fabric added is 36% of the mass of DMAPS; reacting at 65°C for 8 hours to prepare a gel composite fabric material with high moisture absorption and water retention properties.

[0069] Comparative Example 1:

[0070] The preparation method of the material of this comparative example specifically comprises the following steps:

[0071] 4.0 g of CF was ultrasonically cleaned in 30 g / L NaOH solution for 1 h, then repeatedly washed with deionized water until neutral, and dried at 75 °C for 8 h to obtain clean CF.

[0072] Comparative Example 2:

[0073] The preparation method of the material of this comparative example specifically comprises the following steps:

[0074] (1) First, 4.0 g of CF was ultrasonically treated in a 30 g / L sodium hydroxide solution for 1 hour. The parameters of the cotton fabric were: yarn count 21S, density 30*28; then, the cotton fabric was repeatedly washed with deionized water until neutral, and then dried at 75°C for 8 hours to obtain the pretreated fabric;

[0075] (2) Mix 3 g of desiccant LiCl in 100 mL of deionized water and allow nitrogen to flow through the mixture for 45 minutes to obtain a treated solution.

[0076] (3) Immersing the pretreated fabric obtained in step (1) in the treatment solution obtained in step (2); reacting at 65° C. for 8 hours to prepare a hygroscopic fabric material.

[0077] The moisture absorption performance of the gel composite fabric of the present invention was tested and compared with that of Comparative Example 1. The results are shown in Table 1 below.

[0078] Table 1. Hygroscopicity index measurement results. This measurement process was conducted in accordance with the relevant standards of the national standard "GB / T 41767-2022 Test method for hygroscopicity and equilibrium state adjustment of polymer-based composite materials."

[0079] 25℃, 60% RH (moisture absorption) performance comparison table:

[0080] Moisture absorption time Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 0 h 0 0 0 0 0 0 1 h 0.45 0.46 0.38 0.37 0.38 0.05 2 h 0.49 0.50 0.40 0.47 0.44 0.06

[0081] The moisture absorption (R) of the materials in Table 1 is calculated by the following formula:

[0082] ;

[0083] Where M1 is the mass of the composite material after moisture absorption, and M0 is the original mass of the composite material.

[0084] The stability of the gel composite fabric of the present invention was tested and compared with that of Comparative Example 2. The results are shown in Table 2 below.

[0085] Table 2. Moisture absorption index test results. This test was conducted in accordance with the relevant standards of the national standard "GB / T 9995-1997 Textile materials - Determination of moisture content and moisture regain - Oven drying method".

[0086] 105℃ stability comparison table:

[0087] Sample name Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 2 Loss rate 0.6% 0.4% 0.7% 1.1% 0.7% 47.2 %

[0088] The material loss rate (S) in Table 2 is calculated by the following formula:

[0089] ;

[0090] Where M2 is the dry weight of the composite material after moisture absorption, and M0 is the original dry weight of the composite material.

[0091] As shown in Tables 1 and 2, the results show that the hydrogel composite fabric of the present invention has a far superior moisture absorption capacity than pure fabric, and a much lower moisture loss rate than hygroscopic fabric. This indicates that the presence of the hydrogel enhances the material's water storage capacity, overcoming the limitation of pure fabric's insufficient moisture absorption capacity. Furthermore, the coordination effect between the hydrogel and the hygroscopic component effectively prevents moisture absorbent leakage, increases the material's effective moisture absorption sites, and facilitates rapid moisture absorption and cyclic stability. After ten cycles of moisture absorption and desorption, the material's moisture absorption capacity has not significantly decreased, demonstrating its excellent cyclic stability (e.g., Figure 4 The product's moisture absorption and stability indicate excellent moisture absorption and water retention, as well as cyclic stability. The hydrogel composite fabric of the present invention exhibits excellent air-water absorption, is simple to prepare, and can be mass-produced.

[0092] It is obvious to those skilled in the art that certain modifications, combinations and variations can be made based on the above teachings.

Claims

1. A method for preparing a gel composite fabric for air water extraction, characterized in that: The preparation method specifically comprises the following steps: (1) First, 1.5-6.0 g of fabric is ultrasonically treated in a sodium hydroxide solution with a concentration of 20-40 g / L for 1-2 hours, and then the fabric is repeatedly washed with deionized water until it is neutral, and then dried at 70-80 ° C for 8-12 hours to obtain a pretreated fabric; (2) 8.0-14.0 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide, a desiccant and a cross-linking agent are mixed evenly in 100 mL of deionized water, and nitrogen is introduced into the mixture for 45-75 minutes to obtain a treatment solution; the desiccant is lithium chloride, calcium chloride or lithium chloride modified with ethanolamine; (3) preparing an aqueous solution of a persulfate initiator, and uniformly spraying the aqueous solution of the persulfate initiator onto the pretreated fabric obtained in step (1), and then airing the fabric in a ventilated place at room temperature for 10-12 hours to obtain an initiator-loaded fabric; (4) Immersing the initiator-loaded fabric obtained in step (3) in the treatment solution obtained in step (2), reacting at 60-70° C. for 8-10 hours, thereby preparing a gel composite fabric material with high moisture absorption and water retention properties.

2. The preparation method according to claim 1, wherein: The amount of the desiccant added in step (2) is 10-50% of the mass of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide.

3. The preparation method according to claim 1, wherein: In step (2), the molar ratio of the cross-linking agent to [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide is 0.02-0.05:

1.

4. The preparation method according to claim 1 or 3, characterized in that: The cross-linking agent in step (2) is N,N'-methylenebisacrylamide.

5. The preparation method according to claim 1, wherein: The molar ratio of the persulfate initiator to [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide is 0.01-0.04:

1.

6. The preparation method according to claim 1, wherein: The persulfate initiator is ammonium persulfate or potassium persulfate.

7. The preparation method according to claim 1 or 3, characterized in that: The amount of the initiator-loaded fabric added in step (4) is 20-40% of the mass of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide.

8. The preparation method according to claim 5, characterized in that: The amount of initiator-loaded fabric added in step (4) is 35-40% of the mass of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide.

9. A gel composite fabric for air water extraction, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.

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