Simple reusable biodegradable gel atmospheric water collection material and preparation method thereof

Abstract

The invention relates to a reusable and biodegradable gel atmospheric water collection material and a preparation method thereof. The preparation method comprises the following steps: dispersing one or more natural high-molecular polymers, a biodegradability enhancer, photothermal conversion material hygroscopic salt and other substances in a solution system taking water as a solvent; heating and magnetically stirring to a dissolving temperature; then freeze-drying or drying at normal temperature to obtain a gel material; the gel material has high moisture absorption rate, good water-retaining property and excellent biodegradability, solves the problems that a traditional water collecting material is non-degradable and wastes resources, can be widely applied to the fields of agricultural irrigation, water supply in arid regions, emergency rescue and the like, and has important social and environmental values.

Description

Technical Field

[0001] The present invention relates to the field of atmospheric water collection materials, and in particular to a simple, reusable and biodegradable gel atmospheric water collection material and a preparation method thereof. Background Art

[0002] With population growth and industrial development, freshwater shortages are becoming increasingly severe, especially in arid regions. It is estimated that by 2050, over 40% of the population will face water shortages. Atmospheric water harvesting (AWH) is a technology that collects moisture from the air. Because it is not restricted by time or location, AWH is considered an effective means of producing freshwater in the future. This is particularly important in arid and water-scarce regions.

[0003] Among various atmospheric water harvesting technologies, adsorption-based atmospheric water harvesting is the most widely studied. Adsorption-based atmospheric water harvesting utilizes various adsorbent / absorbent materials to capture water vapor from the environment, subsequently releasing the vapor through heating, and finally condensing it into liquid freshwater. Throughout this process, the adsorbent, as a core material, not only affects the production and energy consumption of liquid water but also poses potential environmental impacts. Ideal adsorbent materials should exhibit rapid adsorption and desorption kinetics, low desorption temperatures, low cost, good reproducibility, and minimal environmental impact. Currently, common adsorbent materials include hygroscopic salts, porous polymer hydrogels, silica gels, molecular sieves, activated carbon, and metal-organic frameworks (MOFs). With continued research, hydrogel-based water harvesting materials have rapidly developed due to their low cost, large-scale production, and ease of composite use with other materials. For example, CN116651410A relates to a starch-based photoresponsive hydrogel adsorbent loaded with a hygroscopic salt (lithium chloride), which has the advantages of high moisture absorption rate and simple preparation process; CN118027508A relates to a polymer gel material for atmospheric water collection, comprising a polymer gel water collection layer and a photothermal conversion layer arranged on the surface of the polymer gel water collection layer, which utilizes the positive and negative charge differences of the polymer to improve the water collection capacity and reusability of the polymer gel; CN 113571219 A provides a method for preparing an efficient atmospheric water vapor adsorption composite material, which combines a sponge skeleton and a highly absorbent gel to construct a sponge-gel layer structure to achieve liquefied adsorption of vapor.

[0004] In recent years, with the development of atmospheric water collection materials, their application scenarios are no longer limited to fresh water production, but also involve evaporative cooling, indoor dehumidification, and power generation. This will undoubtedly greatly increase the demand for adsorbent materials, especially in large arid areas. However, the ecosystems in these areas are often more fragile, and the existing various adsorbent materials have ignored the impact on the environment during processing and use during development and use. During the use of polymer gel materials, the components in the gel network, such as the polymer matrix and functional groups, are easily aged under light irradiation, which greatly shortens the service life of the adsorbent. If not properly treated, serious environmental problems will occur. Hygroscopic salts can also cause local soil salinization problems, causing vegetation degradation and intensified soil desertification.

[0005] Therefore, the present invention proposes a simple, reusable and biodegradable gel atmospheric water collection material and a preparation method thereof. By using degradable biomass materials and a green and simple preparation process, the impact of raw materials and preparation processes on the environment is avoided. At the same time, the degradable biomass materials can be reused, avoiding the waste of resources and environmental pollution caused by traditional water collection materials that are difficult to recycle or reuse after use.

[0006] In summary, the development of a reusable water-collecting material is of great significance for improving resource utilization and reducing environmental pollution. Summary of the Invention

[0007] In response to the technical problems and potential environmental risks of various existing atmospheric water collection adsorbent materials, the present invention provides a simple, reusable and biodegradable gel atmospheric water collection material and a preparation method thereof. The gel adsorbent material is derived from degradable biomass materials and has the advantages of simple preparation process, strong hygroscopicity and good repeatability.

[0008] In order to achieve the above technical effects, the present invention adopts the following technical solutions: A method for preparing a simple, reusable and biodegradable gel atmospheric water collection material comprises the following steps: S1: Deionized water is used as the solvent, and other substances such as natural polymer, hygroscopic salt, photothermal conversion material, and biodegradability enhancer are added to the deionized water in sequence. The mixed solution is placed in an ultrasonic device for dispersion, and then the solution is heated until it is dissolved to form a uniform solution system; S2: placing the mixed solution in a mold, cooling it to a certain temperature, and obtaining a polymer gel material after a stable cross-linking network is formed between the polymers; S3: Use drying technology to remove excess water from the material to obtain biodegradable atmospheric water collection material.

[0009] Preferably, the natural high molecular polymer involved in S1 can be any one of agar, starch, nanocellulose, pectin, guar gum, alginate, hyaluronic acid, or a combination of at least two thereof, forming a hydrogel structure having a single network or an interpenetrating network.

[0010] Preferably, the hygroscopic salt involved in S1 can be any one of calcium chloride (CaCl2), calcium acrylate, calcium alginate, choline chloride (ChCl) or a combination of at least two thereof.

[0011] Preferably, the light-to-heat conversion material involved in S1 can be any one of nano-carbon powder, carbon black, graphene, polyaniline, polypyrrole, carbon nanotubes, etc., or a combination of at least two thereof.

[0012] Preferably, the biodegradability enhancer involved in S1 includes any one or a combination of at least two of inorganic material nucleating agents (layered silicate compounds, inorganic salt compounds, inorganic non-metallic oxides and carbon materials), organic phosphates, cyclodextrins, etc.

[0013] Preferably, the natural high molecular polymer involved in S1: hygroscopic salt: water = 1~10:1~40:100.

[0014] Preferably, the mass ratio of the photothermal conversion material to the natural high molecular polymer involved in S1 is 1 to 5:100.

[0015] Preferably, the other substance can be any one or a combination of at least two of inorganic materials such as molecular sieve, silica, biochar, etc. used to support the gel structure.

[0016] Preferably, the ultrasonic dispersion time in S1 is 0.1 to 3 hours.

[0017] Preferably, the heating temperature in S1 is 15-95°C.

[0018] Preferably, the mold involved in S2 can be one of various shapes such as strip, cylinder, flat plate, etc.

[0019] Preferably, the drying technology involved in S3 can be any one of supercritical drying, solar drying, heating oven drying (temperature of 60-95°C), freeze drying and room temperature vacuum drying, or a combination of at least two of them.

[0020] The present invention also provides a simple, reusable and biodegradable gel atmospheric water collection material prepared by the above scheme.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a simple, reusable and biodegradable gel atmospheric water collection material and a preparation method thereof. The gel atmospheric water collection material uses degradable biomass materials, avoiding the waste of resources and environmental pollution caused by the difficulty of recycling or reusing traditional water collection materials; (2) The present invention provides a simple, reusable and biodegradable gel atmospheric water collection material and a preparation method thereof. The gel atmospheric water collection material has excellent hygroscopic properties and can efficiently capture moisture from the air under low humidity conditions, which is particularly important in arid and water-scarce areas; (3) The present invention provides a simple, reusable and biodegradable gel atmospheric water collection material and a preparation method thereof. The gel atmospheric water collection material is made entirely of biomass resources and can be completely degraded into non-toxic substances in the soil, thus avoiding the environmental burden caused by the decommissioning of the adsorbent.

[0022] Through the description of the above beneficial effects, the present invention not only provides an effective atmospheric water collection solution, but also emphasizes its importance in environmental protection and resource conservation, and meets the requirements of sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The diagram shows the principle of preparing the polymer gel (using agar as the main raw material) in Example 1, a physical picture of the gel prepared in Example 1, and a microscopic morphology of the gel.

[0024] Figure 2 The contact angle of the polymer gel (using agar as the main raw material) of Example 1 was photographed.

[0025] Figure 3 Graph showing atmospheric water capture behavior of the polymer gel prepared in Example 2 at a relative humidity of 70% and 25°C.

[0026] Figure 4 This is the surface temperature distribution diagram prepared in Example 2 after irradiation with simulated sunlight for 1 hour (under the intensity of 1 standard sun).

[0027] Figure 5 This is a schematic diagram of the principle that the polymer gel prepared in the example adsorbs water in the environment at night and desorbs and collects water under the drive of sunlight during the day.

[0028] Figure 6 This is a simple device and effect diagram for desorption and collection of water from the polymer gel prepared in Example 1 in the laboratory.

[0029] Figure 7 This is a cycle test chart of the reuse performance of the polymer gel prepared in Example 1. DETAILED DESCRIPTION

[0030] This specification will fully illustrate the present invention through specific examples. These examples are intended to enable professionals in the relevant technical field to more deeply understand the essence and features of the present invention, but do not constitute any limitation of the present invention. It should be emphasized that those skilled in the art may make various modifications and optimizations without departing from the core concept of the present invention. Such modifications and optimizations are also considered to be within the scope of protection of the present invention.

[0031] To facilitate understanding of the embodiments of the present invention, the following will be further explained with reference to the accompanying drawings using specific implementations as examples, and each implementation does not constitute a limitation on the embodiments of the present invention. Specific implementation 1: 0.5 g agar, 1.0 g calcium chloride, and 0.01 g carboxylated carbon nanotubes were dispersed in 8.49 ml deionized water, ultrasonicated for 10 min to uniformly disperse them, and then heated to 95°C for 30 min to completely dissolve the agar to obtain a stock solution of gel; The stock solution is poured into a round cake-shaped mold and cooled at room temperature to obtain a hydrogel material; The hydrogel material was removed from the mold and placed in a refrigerator for 24 hours at a freezing temperature of -12°C. After being frozen into shape, it was transferred to a freeze dryer for freeze drying for 48 hours at a freeze drying temperature of -55°C.

[0033] The agar-based water-collecting gel material prepared in Example 1 was tested for water collection performance under conditions of a relative humidity of 70% and a temperature of 25° C. The water collection capacity within 360 minutes was 1.22 g / g. Specific embodiment 2: 1.5 g of sodium alginate and 0.02 g of nano-carbon powder were dispersed in 20 ml of deionized water, and ultrasonicated for 10 min to make them uniformly dispersed. Then, they were heated to 60 °C for 20 min to completely dissolve the sodium alginate to obtain a stock solution of gel; The stock solution was poured into a beaker and 0.4 g of calcium chloride was added to form a sodium alginate-calcium chloride / nanocarbon powder hydrogel; The hydrogel was washed with clean water 5 times, placed in a strip mold and dried in a heating oven at 80°C for 6 hours. The hydrogel material was taken out of the mold and placed in a beaker. 30 ml of the prepared 12.5% choline chloride solution was poured into it. After dispersion for 12 hours, the hydrogel was placed in a refrigerator and frozen for 24 hours at a freezing temperature of -12°C. After being frozen into shape, it was transferred to a freeze dryer for freeze-drying for 48 hours at a freeze-drying temperature of -55°C to obtain a gel water-collecting material.

[0035] The calcium alginate-based water-collecting gel material prepared in Example 2 was tested for water collection performance under conditions of a relative humidity of 70% and a temperature of 25° C. The water collection capacity within 360 minutes was 0.31 g / g. Specific embodiment 3: 1.0 g of nanocellulose, 1.0 g of PVA, 0.02 g of graphene, and 0.02 g of cyclodextrin were dispersed in 10 ml of deionized water, ultrasonicated for 10 min to make them uniformly dispersed, and then heated to 90 °C for 30 min to completely dissolve the PVA to obtain a stock solution of gel; Pour the stock solution into a beaker and add 0.8 g of 4A molecular sieves. Keep it at 60°C for 30 minutes to remove bubbles in the solution. The solution was placed in a -20°C refrigerator, frozen for 24 hours, and thawed once at room temperature. This process was repeated three times to obtain a gel water-collecting material. The hydrogel was placed in a strip mold and dried in a heating oven at 70°C for 12 hours. The hydrogel material is taken out from the mold to obtain a gel water-collecting material.

[0037] The cellulose-based hydrogel material prepared in Example 3 was tested for water collection performance under conditions of a relative humidity of 70% and a temperature of 25° C. The water collection capacity within 360 minutes was 0.6 g / g.

[0038] It should be understood that the present invention uses the above-described embodiments to illustrate the detailed structural features of the present invention, but the present invention is not limited to the above-described detailed structural features, that is, it does not mean that the present invention must rely on the above-described detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components of the present invention, addition of auxiliary components, selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

[0039] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0040] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0041] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A simple, reusable and biodegradable gel atmospheric water collection material and its preparation method, characterized in that: The following steps are involved: Deionized water is used as a solvent, and other substances such as natural high molecular polymer, hygroscopic salt, photothermal conversion material, and biodegradability enhancer are sequentially added to the deionized water. The mixed solution is placed in an ultrasonic device for dispersion, and then the solution is heated until it is dissolved to form a uniform solution system. The mixed solution is placed in a mold, cooled to a certain temperature, and a stable cross-linked network is formed between the polymers to obtain a polymer gel material; Drying technology is used to remove excess water from the material to obtain biodegradable atmospheric water collection materials.

2. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, characterized in that: The natural high molecular polymer can be any one of agar, starch, nanocellulose, pectin, guar gum, alginate, and hyaluronic acid, or a combination of at least two of them, forming a hydrogel structure having a single network or an interpenetrating network.

3. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, characterized in that: The hygroscopic salt may be any one of calcium chloride (CaCl2), calcium acrylate, calcium alginate, choline chloride (ChCl), or a combination of at least two thereof.

4. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, characterized in that: The light-to-heat conversion material may be any one of nano-carbon powder, carbon black, graphene, polyaniline, polypyrrole, carbon nanotubes, etc., or a combination of at least two thereof.

5. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, characterized in that: The biodegradability enhancer includes any one or a combination of at least two of inorganic nucleating agents (layered silicate compounds, inorganic salt compounds, inorganic non-metallic oxides and carbon materials), organic phosphates, cyclodextrins, etc.

6. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, characterized in that: Natural high molecular polymer: hygroscopic salt: water = 1~10:1~40:

100.

7. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, wherein the mass ratio of the photothermal conversion material to the natural high molecular polymer is 1 to 5:

100.

8. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, characterized in that The other substances are any one or a combination of at least two inorganic materials such as molecular sieve, silica, biochar, etc. used to support the gel structure.

9. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, characterized in that The heating temperature is 15~95 ℃.

10. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, characterized in that The mold can be in any shape, such as a strip, a cylinder, or a flat plate.

11. The simple, reusable and biodegradable gel atmospheric water collection material and its preparation method according to claim 1, characterized in that: The drying technology can be any one of supercritical drying, solar drying, heating oven drying (temperature of 60~95℃), freeze drying and room temperature vacuum drying, or a combination of at least two of them.

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