Preparation method of wood water collecting material for extracting water from air

Abstract

The invention discloses a preparation method of a wood water collecting material for extracting water from air. The method comprises the steps that natural wood is pretreated, a photo-thermal material-nano carbon black is added, the material is endowed with photo-thermal conversion performance, then moisture absorption salt is added, a product is subjected to freeze drying after loading is finished, and the high-moisture-absorption wood is obtained. The method has the advantages of simple process flow, mild reaction conditions, short reaction time, excellent moisture absorption and photo-thermal conversion performance, and good practical application value.

Description

Technical Field

[0001] This invention relates to the field of natural polymers, specifically a method for preparing a wood-based water-collecting material for air-based water extraction. Background Technology

[0002] Approximately 2.2 billion people worldwide face water scarcity. Water exists as a liquid in many places in the natural environment, including rivers, lakes, oceans, and groundwater. In addition, water exists in the atmosphere as vapor or droplets; it is estimated that the Earth's atmosphere contains about 13,000 cubic meters of water. The technology of extracting water from the atmosphere represents a new, non-traditional water extraction technology that has emerged in recent years. It is generally not geographically limited, inexpensive, and easy to implement. This technology includes collecting fog and dew at high humidity levels and utilizing adsorption technology at low humidity levels. Currently, mainstream technologies for capturing water vapor from the air, such as cooling and condensation, solid adsorption, and liquid absorption, all have significant limitations: cooling and condensation processes consume enormous amounts of energy; the adsorption rate and water capacity of solid adsorbents (such as silica gel and molecular sieves) are generally low; and liquid absorption methods using hygroscopic salts face problems such as easy leakage of salt solutions, equipment corrosion, and poor long-term stability.

[0003] Wood, as a natural renewable resource, possesses an inherent porous structure and abundant hydrophilic groups (such as hydroxyl groups), making it a typical hygroscopic material with great potential for regulating environmental humidity. However, since ancient times, researchers have used drying, preservation, and modification treatments on wood to overcome or control the structural deformation, decay, and reduced mechanical strength caused by its hygroscopicity. With the continuous development of materials science, researchers no longer view wood's hygroscopicity as a drawback, but rather as a treasure trove that can be designed and utilized. However, unmodified wood has low hygroscopicity. Therefore, this invention proposes a simple and low-cost method to prepare highly hygroscopic wood, enabling it to play a key role in emerging fields such as energy, environment, and construction, aligning with the global trend of green and sustainable development. Summary of the Invention

[0004] This invention addresses the shortcomings and drawbacks of existing wood materials, such as low hygroscopicity and high energy consumption during desorption, by proposing a method for preparing wood-based water-collecting materials for air extraction.

[0005] A method for preparing a wood-based water-collecting material for air extraction includes the following steps: pre-treating, impregnating, and freeze-drying natural wood sequentially to obtain highly hygroscopic wood.

[0006] Preferably, the natural wood is linden wood with a thickness of 2 mm in the R direction.

[0007] Preferably, the pretreatment method is NaClO2 solution bleaching at a temperature of 80-110℃ for 2-4 hours.

[0008] Preferably, the impregnation is photothermal material impregnation and moisture-absorbing salt impregnation.

[0009] Preferably, the photothermal material is nano-carbon black with a concentration of 1 wt%.

[0010] Preferably, the selected hygroscopic salt is lithium chloride or calcium chloride, with a concentration of 10-30 wt%.

[0011] A wood-based water-collecting material for air-based water extraction is prepared by the above method.

[0012] The highly hygroscopic wood prepared by this invention has the following advantages:

[0013] (1) This invention is prepared from natural wood as raw material, and has the advantages of low cost and easy availability. It has important practical significance for the effective recycling and utilization of forest biomass resources and the sustainable development of the environment.

[0014] (2) The process of this invention is simple, the reaction conditions are mild, the reaction time is short, and the principles of energy saving and environmental protection are fully considered. It is easy to industrialize and has good application value.

[0015] (3) The highly absorbent wood prepared by this invention has good photothermal properties and can be desorbed under sunlight, which significantly reduces the energy consumption required for desorption.

[0016] (4) The highly absorbent wood prepared by this invention has high moisture absorption capacity and long-lasting moisture absorption properties, and can be reused for a long time. It has great application potential in air-water extraction. Attached Figure Description

[0017] Figure 1 This is a SEM image of the highly absorbent wood prepared in Example 1 of the present invention.

[0018] Figure 2 This is the adsorption isotherm diagram of the highly hygroscopic wood prepared in Example 1 of the present invention.

[0019] Figure 3 This is a cyclic stability diagram of the highly hygroscopic wood prepared in Example 1 of the present invention. Detailed Implementation

[0020] To better understand the technical features of the present invention, the present invention will be further described below with reference to embodiments and accompanying drawings. The content described is illustrative and not restrictive, and the embodiments of the present invention are not limited thereto.

[0021] Example 1

[0022] (1) Cut natural wood into wood chips with a thickness of 2 mm and soak the wood chips in NaClO2 solution for 2 h. The solution pH is 4.6 and the reaction temperature is 80℃. After the reaction is completed, rinse repeatedly with ethanol and deionized water until pH is 7. After freeze drying, bleached wood is obtained.

[0023] (2) Weigh 1g of nano carbon black and 1g of sodium dodecylbenzene sulfonate and add them to 100ml of deionized water. Mix them evenly by ultrasonication. Soak the white wood obtained in step (1) in the solution for 1 hour, rinse it with deionized water until it no longer discolors, and freeze-dry it to obtain wood loaded with photothermal material.

[0024] (3) The wood obtained in (2) was soaked in a 10wt% lithium chloride solution for 6 hours and then freeze-dried to obtain highly hygroscopic wood.

[0025] It should be noted that the application performance test of the high moisture absorption capacity prepared by this invention is as follows:

[0026] The water vapor adsorption of the material was tested using a dynamic water vapor adsorption instrument at a lithium chloride concentration of 10 wt%, and the results are shown in Table 1.

[0027] Table 1

[0028] relative humidity % <![CDATA[Moisture absorption capacity g / g -1 > relative humidity % <![CDATA[Moisture absorption capacity g / g -1 > 5 0.06573 40 0.77579 10 0.19324 50 0.9565 15 0.35237 60 1.29081 20 0.50031 70 1.6728 30 0.65393 80 1.98853

[0029] The microstructure of the highly hygroscopic wood prepared according to this invention was obtained by scanning electron microscopy (SEM). Figure 1 As shown, the adsorption isotherm is as follows Figure 2 As shown in Figure 3, the adsorption cycle stability is as shown in Figure 4.

[0030] Example 2

[0031] (1) Cut natural wood into wood chips with a thickness of 3 mm and soak the wood chips in NaClO2 solution for 3 h. The solution pH is 4.6 and the reaction temperature is 100℃. After the reaction is completed, rinse repeatedly with ethanol and deionized water until pH is 7. After freeze drying, bleached wood is obtained.

[0032] (2) Weigh 1.5g of nano-carbon black and 1g of sodium dodecylbenzenesulfonate and add them to 100ml of deionized water. Mix thoroughly by ultrasonication. Soak the white wood obtained in step (1) in the solution for 2 hours, rinse with deionized water until no more color is lost, and freeze-dry to obtain wood loaded with photothermal material.

[0033] (3) The wood obtained in (2) was soaked in a 15wt% lithium chloride solution for 6 hours and then freeze-dried to obtain highly hygroscopic wood.

[0034] Example 3

[0035] (1) Cut natural wood into wood chips with a thickness of 4 mm and soak the wood chips in NaClO2 solution for 4 h. The solution pH is 4.6 and the reaction temperature is 110℃. After the reaction is completed, rinse repeatedly with ethanol and deionized water until pH is 7. After freeze drying, bleached wood is obtained.

[0036] (2) Weigh 2g of nano-carbon black and 1g of sodium dodecylbenzenesulfonate and add them to 100ml of deionized water. Mix thoroughly by ultrasonication. Soak the white wood obtained in step (1) in the solution for 3 hours, rinse with deionized water until it no longer discolors, and freeze-dry to obtain wood loaded with photothermal material.

[0037] (3) The wood obtained in (2) was soaked in a 20wt% lithium chloride solution for 6 hours and then freeze-dried to obtain highly hygroscopic wood.

[0038] Implementation 4

[0039] (1) Cut natural wood into wood chips with a thickness of 2 mm and soak the wood chips in NaClO2 solution for 2 h. The solution pH is 4.6 and the reaction temperature is 80℃. After the reaction is completed, rinse repeatedly with ethanol and deionized water until pH is 7. After freeze drying, bleached wood is obtained.

[0040] (2) Weigh 2g of nano-carbon black and 1g of sodium dodecylbenzenesulfonate and add them to 100ml of deionized water. Mix thoroughly by ultrasonication. Soak the white wood obtained in step (1) in the solution for 3 hours, rinse with deionized water until it no longer discolors, and freeze-dry to obtain wood loaded with photothermal material.

[0041] (3) The wood obtained in (2) was soaked in a 40wt% lithium chloride solution for 6 hours and then freeze-dried to obtain highly hygroscopic wood.

[0042] It should be noted that the above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation of the present invention. Other variations can be made based on the above description. Any other modifications or changes that do not depart from the technical solution of the present invention, or that make obvious modifications or changes to the technical solution of the present invention, should be included within the protection scope of the present invention.

Claims

1. A method for preparing a wood-based water-collecting material for air-based water extraction, characterized in that, Includes the following steps: (1) Pre-treatment of natural wood; (2) Weigh a certain amount of nano carbon black to prepare a solution, and then freeze-dry (1) after immersing it in the solution; (3) Weigh a certain amount of hygroscopic salt to prepare a solution, impregnate the material obtained in (2) and freeze-dry it to obtain the highly hygroscopic wood.

2. The method according to claim 1, characterized in that, The natural wood used in step (1) includes, but is not limited to, linden, balsa wood, beech, etc., with a thickness of 2-4 mm.

3. The method according to claim 1, characterized in that, The pretreatment in step (1) is a NaClO2 solution (pH=4.6), the treatment time is 2-4 hours, and the heating temperature is 80-110℃.

4. The method according to claim 1, characterized in that, The nano carbon black solution prepared in step (2) is 1-2 wt%, and the impregnation time is 1-3 h.

5. The method according to claim 1, characterized in that, The hygroscopic salt in step (3) is lithium chloride, calcium chloride, etc.

6. The method according to claim 1, characterized in that, The amount of hygroscopic salt added in step (3) is 10-40 wt%.

7. The method according to claim 1, characterized in that, The hygroscopic salt soaking time in step (3) is 6 hours.

8. The method according to claim 1, characterized in that, This method has a simple process flow, mild reaction conditions, and short reaction time, making it suitable for industrial applications.

9. The highly absorbent wood according to claim 1 is a resource-friendly, low-cost, and moisture-absorbing material with significant moisture absorption capacity.

10. The highly absorbent wood according to claim 1 is a moisture-absorbing material with good photothermal capacity and low desorption energy consumption.

Images