Humidifying adsorption gel film utilizing electrostatic spraying, preparation method and application

Abstract

The invention discloses a wetting adsorption gel film utilizing electrostatic spraying as well as a preparation method and application thereof, and belongs to the field of air carbon dioxide capture adsorbents. The preparation method comprises the following steps: uniformly mixing an adsorption material and a forming material which are pretreated to be neutral, then loading the mixture into an electrostatic spraying machine, respectively taking mixed powder and a load as a negative electrode and a positive electrode, and adjusting the voltage and air pressure of the electrostatic spraying machine to enable the mixed powder to be adsorbed on the surface of the load; spraying a cross-linking agent on the surface of the load, so that the forming material and the cross-linking agent are subjected to chemical cross-linking reaction; repeating the steps until a forming film with a certain thickness is formed on the surface of the load; and soaking the formed film material in a carbonate base solution or a hydroxyl base solution for ion exchange reaction to obtain the wetting adsorption gel film. Molding of the humidifying adsorption material is achieved through the electrostatic spraying technology, operation is easy, industrial production is facilitated, the obtained material is high in stability and good in mechanical property, and a new thought is provided for the molding technology of the direct air trapping material.

Description

Technical Field

[0001] The present invention belongs to the field of carbon dioxide capture adsorbents, and particularly relates to a variable humidity adsorption gel film prepared by electrostatic spraying, a preparation method and an application thereof. Background Art

[0002] With the continuous increase in the emissions of greenhouse gases represented by carbon dioxide globally, climate problems such as global warming have become increasingly severe. Direct air capture (DAC) technology can directly capture carbon dioxide from the atmosphere and store it or convert it into useful resources. Different from traditional carbon capture technologies, direct air capture technology can effectively capture low-concentration carbon dioxide in the air, does not rely on specific emission sources, avoids the limitations in the industrial and energy fields, and has the advantage of flexible deployment.

[0003] Currently, the research on direct air capture technology mainly focuses on the development of adsorption materials, especially for the efficient capture of low-concentration carbon dioxide. Common adsorption materials include porous adsorbents, metal-organic frameworks (MOFs), activated carbon, zeolites, etc. These materials have a high specific surface area and good adsorption performance, but still face challenges in terms of adsorption capacity, adsorption rate and energy efficiency. In particular, the stability and cycling performance under variable humidity conditions need to be further improved. To solve this problem, variable humidity adsorption technology has gradually become a research hotspot. By using materials such as quaternary ammonium-based alkaline ion exchange resins, without relying on heat sources, the adsorption-desorption of carbon dioxide is realized by changing the water vapor pressure in the environment, greatly reducing the regeneration energy consumption and having broad application prospects.

[0004] In order to further promote the application of variable humidity adsorbents, people have begun to pay attention to shaping technologies in recent years. Gel films have good flexibility and adjustability, and their three-dimensional network structure can effectively provide a large specific surface area and porosity. At the same time, gel films can be prepared by simple methods such as solution impregnation and crosslinking, with low manufacturing costs and strong operability. Therefore, their application in variable humidity adsorption has good feasibility and can provide efficient and low-energy shaping ideas for technologies such as direct air capture. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies in the prior art and provide a variable humidity adsorption gel film prepared by electrostatic spraying, a preparation method and an application thereof. The variable humidity adsorption gel film material in the present invention can be mass-produced, has a low cost, good mechanical properties, and has broad application prospects.

[0006] The specific technical solutions adopted by the present invention are as follows:

[0007] In the first aspect, the present invention provides a preparation method for a variable humidity adsorption gel film prepared by electrostatic spraying, and the specific steps are as follows:

[0008] S1: Mix the pre-treated neutral adsorbent material and the forming material evenly to obtain a mixed powder;

[0009] S2: Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the load serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine so that the mixed powder is adsorbed on the surface of the load;

[0010] S3: Spray a cross-linking agent on the surface of the load carrying the mixed powder obtained in step S2, so that a chemical cross-linking reaction occurs between the forming material and the cross-linking agent;

[0011] S4: Alternately repeat step S2 and step S3 until a forming film material with a certain thickness is formed on the surface of the load;

[0012] S5: Immerse the forming film material obtained in step S4 in a carbonate-based alkali solution or a hydroxide-based alkali solution until the ion exchange reaction is completed to obtain a wet adsorption gel film.

[0013] Preferably, in step S1, the adsorbent material is a strong base type I resin or a strong base type II resin.

[0014] Preferably, the pre-treatment process of the adsorbent material in step S1 is as follows: successively soak and wash the adsorbent material with absolute ethanol, hydrochloric acid solution, and sodium hydroxide solution, and then wash the soaked adsorbent material with deionized water until it is neutral, and dry it for standby; the drying temperature is set at 70 °C, and the drying time is 24-48 h.

[0015] Preferably, in step S1, a ball mill is used to mix the adsorbent material and the forming material; the added mass of the adsorbent material in the mixed powder is 26.3% - 75%.

[0016] Preferably, in step S1, the forming material is one or a mixture of two of polyvinyl alcohol, tannic acid, or citric acid.

[0017] Preferably, in step S2, the load is a copper sheet or a glass sheet; the voltage of the electrostatic spraying machine is set at 2 - 8 kV, and the air pressure is set at 0.05 - 0.25 MPa.

[0018] Preferably, in step S3, the cross-linking agent is a glutaraldehyde solution or genipin; the concentration of the cross-linking agent solution is 2 - 10 wt%.

[0019] Preferably, in step S5, the carbonate-based alkali solution is a sodium carbonate solution or a potassium carbonate solution with a concentration of 0.5 - 2.0 mol / L, and the hydroxide-based alkali solution is a sodium hydroxide solution or a potassium hydroxide solution with a concentration of 0.5 - 2.0 mol / L; the time for soaking for the ion exchange reaction is 24 h.

[0020] In a second aspect, the present invention provides a variable humidity adsorption gel film obtained by using the preparation method described in the first aspect.

[0021] In a third aspect, the present invention provides an application method of the variable humidity adsorption gel film described in the second aspect in capturing carbon dioxide from the air.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The film preparation process provided by the present invention innovatively applies the electrostatic spraying technology in the forming process of the direct air capture variable humidity adsorption material, which is simple to operate and easy to scale up on a large scale. Through the chemical cross-linking process, a three-dimensional network structure is formed inside the obtained variable humidity adsorption gel film material, which is beneficial to the progress of the adsorption reaction. Due to the formation of hydrogen bonds in the chemical reaction, the prepared variable humidity adsorption gel film has good structural and mechanical properties and outstanding cyclic stability. Description of the Drawings

[0024] Figure 1 It is a flow chart of the preparation method of the variable humidity adsorption gel film using electrostatic spraying provided by the present invention;

[0025] Figure 2 It is a comparison chart of the carbon dioxide adsorption performance of the variable humidity adsorption gel films prepared in Example 1, Example 3 and Example 4. Detailed Embodiments

[0026] The present invention will be further described and explained below in conjunction with the drawings and specific embodiments. The technical features of each embodiment in the present invention can be combined accordingly without conflict.

[0027] Example 1

[0028] This example provides a preparation method of a variable humidity adsorption gel film using electrostatic spraying, and the specific steps are as follows:

[0029] (1) Immerse the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume for 12 hours respectively, and repeatedly wash with a large amount of deionized water until the pH is approximately 7.0. After drying in an oven at 70 °C for 48 hours, it is pulverized for later use.

[0030] (2) In a ball mill, mix the pretreated neutral adsorption material and the forming material polyvinyl alcohol evenly according to a mass ratio of 1:1 to obtain a mixed powder.

[0031] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the copper sheet serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 4 kV and 0.15 Mpa respectively, and make the mixed powder evenly adsorbed on the surface of the copper sheet in the high-voltage electric field.

[0032] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the forming material polyvinyl alcohol and glutaraldehyde.

[0033] (5) Repeat steps (3) and (4) until a forming film material with a certain thickness is formed on the surface of the copper sheet.

[0034] (6) Immerse the obtained forming film material in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a humidity-responsive adsorption gel film.

[0035] The humidity-responsive adsorption gel films prepared in all examples and the materials obtained in the comparative examples were all tested for carbon dioxide adsorption performance using a NETZSCH STA449F3 synchronous thermal analyzer in Germany. The film after ion exchange with the alkaline solution was washed repeatedly with deionized water and then placed in a crucible for testing. First, it was purged with nitrogen at 20 °C and 60% RH for 0.5 h to remove the residual CO2, then purged with dry nitrogen at 20 °C for 1.5 h to dry the adsorption film, and finally purged with a mixed gas of 20 °C, 10% RH, and 400 ppm CO2@N2 for 4.0 h to complete the adsorption process test.

[0036] Example 2

[0037] (1) Immerse the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume amount for 12 h in sequence, and repeatedly wash with a large amount of deionized water until the pH ≈ 7.0. After drying in an oven at 70 °C for 48 h, it was pulverized for use.

[0038] (2) In a ball mill, mix the pretreated adsorbent material and the forming material polyvinyl alcohol evenly according to a mass ratio of 3:1 to obtain a mixed powder.

[0039] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode and the copper sheet serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 4 kV and 0.15 Mpa respectively, and make the mixed powder evenly adsorbed on the surface of the copper sheet in a high-voltage electric field.

[0040] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the forming material polyvinyl alcohol and glutaraldehyde.

[0041] (5) Repeat steps (3) and (4) until a forming film material with a certain thickness is formed on the surface of the copper sheet.

[0042] (6) Immerse the obtained forming film material in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a humidity-responsive adsorption gel film.

[0043] Due to the relatively high content of ion-exchange resin and the relatively low content of the molding material polyvinyl alcohol, which is only 25%, the material can form a gel after molding, but its mechanical properties are average.

[0044] Example 3

[0045] (1) Soak the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume for 12 hours respectively, and repeatedly wash with a large amount of deionized water until the pH is approximately 7.0. After drying in an oven at 70 °C for 48 hours, crush it for later use.

[0046] (2) In a ball mill, mix the pretreated neutral adsorbent material, the molding material polyvinyl alcohol, and tannic acid evenly according to the mass ratio of 0.5:0.5:0.9 to obtain a mixed powder.

[0047] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the copper sheet serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 4 kV and 0.15 Mpa respectively, and make the mixed powder evenly adsorbed on the surface of the copper sheet in a high-voltage electric field.

[0048] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the molding material and glutaraldehyde.

[0049] (5) Repeat steps (3) and (4) until a molding film material with a certain thickness is formed on the surface of the copper sheet.

[0050] (6) Immerse the obtained molding film material in a 0.5 mol / L sodium hydroxide solution for 24 hours until the ion exchange reaction is completed to obtain a wet adsorption gel film.

[0051] Example 4

[0052] (1) Soak the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume for 12 hours respectively, and repeatedly wash with a large amount of deionized water until the pH is approximately 7.0. After drying in an oven at 70 °C for 48 hours, crush it for later use.

[0053] (2) In a ball mill, mix the pretreated neutral adsorbent material, the molding material polyvinyl alcohol, and citric acid evenly according to the mass ratio of 0.5:0.5:0.8 to obtain a mixed powder.

[0054] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the copper sheet serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 4 kV and 0.15 Mpa respectively, and make the mixed powder evenly adsorbed on the surface of the copper sheet in a high-voltage electric field.

[0055] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the molding material and glutaraldehyde.

[0056] (5) Repeat steps (3) and (4) until a molding film material with a certain thickness is formed on the surface of the copper sheet.

[0057] (6) Immerse the obtained molding film material in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a humidity-responsive adsorption gel film.

[0058] Figure 2 It is a comparison chart of the carbon dioxide adsorption performance of the humidity-responsive adsorption gel films prepared in Example 1, Example 3, and Example 4. The results show that the humidity-responsive adsorption gel film prepared in Example 3 has the highest carbon dioxide adsorption capacity. Because tannic acid is rich in hydroxyl groups, it can not only cross-link with polyvinyl alcohol but also further undergo a secondary chemical cross-linking reaction with the glutaraldehyde solution. Through the formation of hydrogen bonds, a rich three-dimensional network structure is formed inside the material, which not only has good mechanical properties but also, due to the presence of pores, is conducive to the circulation of gas inside. Although the content of the ion exchange resin in the adsorption material is low, the adsorption performance is the best.

[0059] Example 5

[0060] (1) Immerse the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume for 12 h in turn, and repeatedly wash with a large amount of deionized water until the pH ≈ 7.0, and then dry it in an oven at 70 °C for 48 h and crush it for use.

[0061] (2) In a ball mill, uniformly mix the pretreated adsorption material and the molding material polyvinyl alcohol according to a mass ratio of 1:1 to obtain a mixed powder.

[0062] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder is used as the negative electrode and the copper sheet is used as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 4 kV and 0.15 Mpa respectively, and make the mixed powder uniformly adsorbed on the surface of the copper sheet in a high-voltage electric field.

[0063] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the molding material and glutaraldehyde.

[0064] (5) Repeat steps (3) and (4) until a molding film material with a certain thickness is formed on the surface of the copper sheet.

[0065] (6) Immerse the obtained molding film material in a 0.5 mol / L sodium carbonate solution for 24 h until the ion exchange reaction is completed to obtain a humidity-responsive adsorption gel film.

[0066] Compared with Example 1, in this example, sodium carbonate solution is used for ion exchange. Due to the decrease in adsorption sites, the carbon dioxide adsorption capacity of the variable humidity adsorption gel film prepared in this example also decreases accordingly.

[0067] Example 6

[0068] (1) The strongly basic type II resin is successively soaked in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume for 12 h, and repeatedly washed with a large amount of deionized water until the pH is approximately 7.0, dried in an oven at 70 °C for 48 h, and then crushed for use.

[0069] (2) In a ball mill, the pretreated neutral adsorbent material and the forming material polyvinyl alcohol are mixed evenly according to a mass ratio of 1:1 to obtain a mixed powder.

[0070] (3) The mixed powder is loaded into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the glass sheet serves as the positive electrode. The voltage and air pressure of the electrostatic spraying machine are adjusted to 4 kV and 0.15 Mpa respectively, and the mixed powder is evenly adsorbed on the surface of the glass sheet in a high-voltage electric field.

[0071] (4) A 3 wt% glutaraldehyde solution is sprayed on the surface of the glass sheet adsorbed with the mixed powder, so that the forming material and glutaraldehyde undergo a chemical cross-linking reaction.

[0072] (5) Steps (3) and (4) are repeated until a forming film material with a certain thickness is formed on the surface of the glass sheet.

[0073] (6) The obtained forming film material is soaked in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a variable humidity adsorption gel film.

[0074] Compared with Example 1, this example uses a glass sheet as the carrier. The results show that compared with a copper sheet, the loading capacity of the glass sheet is relatively weak, and the amount of loaded powder is much lower than that of the copper sheet.

[0075] Example 7

[0076] (1) The strongly basic type II resin is successively soaked in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume for 12 h, and repeatedly washed with a large amount of deionized water until the pH is approximately 7.0, dried in an oven at 70 °C for 48 h, and then crushed for use.

[0077] (2) In a ball mill, the pretreated neutral adsorbent material and the forming material polyvinyl alcohol are mixed evenly according to a mass ratio of 1:1 to obtain a mixed powder.

[0078] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the copper sheet serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 2 kV and 0.15 Mpa respectively, and make the mixed powder uniformly adsorb on the surface of the copper sheet in a high-voltage electric field.

[0079] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the forming material and glutaraldehyde.

[0080] (5) Repeat steps (3) and (4) until a formed film material with a certain thickness is formed on the surface of the copper sheet.

[0081] (6) Immerse the obtained formed film material in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a wet adsorption gel film.

[0082] Compared with Example 1, a lower electrostatic spraying voltage is used in this example. The results show that the magnitude of the electrostatic spraying voltage has a certain influence on the film thickness and uniformity. When the voltage is small, the attraction in the electric field is insufficient, resulting in a thinner wet adsorption gel film prepared in this example.

[0083] Example 8

[0084] (1) Immerse the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume for 12 h respectively, and repeatedly wash with a large amount of deionized water until the pH is approximately 7.0. Dry it in an oven at 70 °C for 48 h and then crush it for use.

[0085] (2) In a ball mill, uniformly mix the pretreated adsorbent material and the forming material polyvinyl alcohol in a mass ratio of 1:1 to obtain a mixed powder.

[0086] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the copper sheet serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 6 kV and 0.15 Mpa respectively, and make the mixed powder uniformly adsorb on the surface of the copper sheet in a high-voltage electric field.

[0087] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the forming material and glutaraldehyde.

[0088] (5) Repeat steps (3) and (4) until a formed film material with a certain thickness is formed on the surface of the copper sheet.

[0089] (6) Immerse the obtained formed film material in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a wet adsorption gel film.

[0090] In comparison with Example 1, a higher electrostatic spraying voltage is adopted in this example. The results show that due to the higher voltage, the higher energy in the electric field causes premature collision and aggregation of the powder, resulting in a slightly lower thickness of the humidity-responsive adsorption gel film prepared in this example compared to Example 1.

[0091] Example 9

[0092] (1) Soak the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume for 12 h respectively, and repeatedly wash with a large amount of deionized water until pH≈7.0. After drying in an oven at 70 °C for 48 h, crush it for later use.

[0093] (2) In a ball mill, mix the pretreated neutral adsorbent material and the forming material polyvinyl alcohol evenly according to a mass ratio of 1:1 to obtain a mixed powder.

[0094] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the copper sheet serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 8 kV and 0.15 Mpa respectively, and make the mixed powder evenly adsorb on the surface of the copper sheet in a high-voltage electric field.

[0095] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the forming material and glutaraldehyde.

[0096] (5) Repeat steps (3) and (4) until a forming film material with a certain thickness is formed on the surface of the copper sheet.

[0097] (6) Immerse the obtained forming film material in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a humidity-responsive adsorption gel film.

[0098] In comparison with Example 1, a higher electrostatic spraying voltage is adopted in this example. The results show that due to the too high voltage, the degree of particle collision and aggregation is more intense, and the thickness attenuation of the humidity-responsive adsorption gel film obtained in this example is more severe.

[0099] Example 10

[0100] (1) Soak the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume for 12 h respectively, and repeatedly wash with a large amount of deionized water until pH≈7.0. After drying in an oven at 70 °C for 48 h, crush it for later use.

[0101] (2) In a ball mill, mix the pretreated neutral adsorbent material and the forming material polyvinyl alcohol evenly according to a mass ratio of 1:1 to obtain a mixed powder.

[0102] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the copper sheet serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 4 kV and 0.10 Mpa respectively, and make the mixed powder evenly adsorbed on the surface of the copper sheet in a high-voltage electric field.

[0103] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the forming material and glutaraldehyde.

[0104] (5) Repeat steps (3) and (4) until a forming film material with a certain thickness is formed on the surface of the copper sheet.

[0105] (6) Immerse the obtained forming film material in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a wet adsorption gel film.

[0106] Example 11

[0107] (1) Immerse the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume amount for 12 h respectively, and repeatedly wash with a large amount of deionized water until the pH is approximately 7.0. After drying in an oven at 70 °C for 48 h, crush it for later use.

[0108] (2) In a ball mill, mix the pretreated neutral adsorption material and the forming material polyvinyl alcohol evenly according to a mass ratio of 1:1 to obtain a mixed powder.

[0109] (3) Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the copper sheet serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to 4 kV and 0.20 Mpa respectively, and make the mixed powder evenly adsorbed on the surface of the copper sheet in a high-voltage electric field.

[0110] (4) Spray a 3 wt% glutaraldehyde solution on the surface of the copper sheet adsorbed with the mixed powder to cause a chemical cross-linking reaction between the forming material and glutaraldehyde.

[0111] (5) Repeat steps (3) and (4) until a forming film material with a certain thickness is formed on the surface of the copper sheet.

[0112] (6) Immerse the obtained forming film material in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a wet adsorption gel film.

[0113] Example 12

[0114] (1) Immerse the strong base type II resin in anhydrous ethanol, hydrochloric acid solution, and sodium hydroxide solution with twice the volume amount for 12 h respectively, and repeatedly wash with a large amount of deionized water until the pH is approximately 7.0. After drying in an oven at 70 °C for 48 h, crush it for later use.

[0115] (2) In a ball mill, the pretreated neutral adsorbent material and the forming material polyvinyl alcohol are mixed evenly according to a mass ratio of 1:1 to obtain a mixed powder.

[0116] (3) The mixed powder is loaded into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and a copper sheet serves as the positive electrode. The voltage and air pressure of the electrostatic spraying machine are adjusted to 4 kV and 0.25 Mpa respectively, so that the mixed powder is evenly adsorbed on the surface of the copper sheet in a high-voltage electric field.

[0117] (4) A 3 wt% glutaraldehyde solution is sprayed on the surface of the copper sheet adsorbed with the mixed powder, so that a chemical cross-linking reaction occurs between the forming material and glutaraldehyde.

[0118] (5) Steps (3) and (4) are repeated until a formed film material with a certain thickness is formed on the surface of the copper sheet.

[0119] (6) The obtained formed film material is immersed in a 0.5 mol / L sodium hydroxide solution for 24 h until the ion exchange reaction is completed to obtain a wet adsorption gel film.

[0120] In Examples 10 - 12, as the air pressure of the electrostatic spraying gun increases, the thickness of the obtained wet adsorption gel film increases accordingly.

[0121] Comparative Example 1

[0122] Compared with Example 1, only the adsorbent material strong base type II resin and a 3 wt% glutaraldehyde solution are used in this comparative example, and other process parameters are the same as those in Example 1. Since there are fewer active groups for cross-linking reaction with the ion exchange resin, no gel is formed after forming.

[0123] The above-described embodiments are only a preferred solution of the present invention, but they are not intended to limit the present invention. Those of ordinary skill in the relevant technical field can still make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by adopting equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A preparation method of a variable-wet adsorption gel film using electrostatic spraying, characterized in that, The specific steps are as follows: S1: Mix the adsorption material pretreated to neutrality with the forming material evenly to obtain a mixed powder; S2: Load the mixed powder into an electrostatic spraying machine. The mixed powder serves as the negative electrode, and the load serves as the positive electrode. Adjust the voltage and air pressure of the electrostatic spraying machine to make the mixed powder adsorb on the surface of the load; S3: Spray a crosslinking agent on the surface of the load loaded with the mixed powder obtained in step S2 to cause a chemical crosslinking reaction between the forming material and the crosslinking agent; S4: Alternately repeat step S2 and step S3 until a forming film material with a certain thickness is formed on the surface of the load; S5: Immerse the forming film material obtained in step S4 in a carbonate-based base solution or a hydroxide-based base solution until the ion exchange reaction is completed to obtain a moisture-variable adsorption gel film.

2. The method for preparing a variable humidity adsorption gel film using electrostatic spraying according to claim 1, wherein In step S1, the adsorption material uses a strong base type I resin or a strong base type II resin.

3. The method for preparing a variable wet adsorption gel film using electrostatic spraying according to claim 1, wherein, The pretreatment process of the adsorption material in step S1 is as follows: successively soak and wash the adsorption material with absolute ethanol, hydrochloric acid solution, and sodium hydroxide solution, and then wash the soaked adsorption material with deionized water to neutrality and dry it for standby; the drying temperature is set at 70°C, and the drying time is 24 - 48h.

4. The method for preparing a variable humidity adsorption gel film by electrostatic spraying according to claim 1, characterized in that, In step S1, a ball mill is used to mix the adsorption material and the forming material; the added mass of the adsorption material in the mixed powder is 26.3% - 75%.

5. The method for preparing a variable humidity adsorption gel film using electrostatic spraying according to claim 1, wherein In step S1, the forming material uses one or a mixture of two of polyvinyl alcohol, tannic acid, or citric acid.

6. The method for preparing a variable wet adsorption gel film by electrostatic spraying according to claim 1, characterized in that, In step S2, the load uses a copper sheet or a glass sheet; the voltage of the electrostatic spraying machine is set at 2 - 8 kV, and the air pressure is set at 0.05 - 0.25 MPa.

7. The method for preparing a variable humidity adsorption gel film using electrostatic spraying according to claim 1, characterized in that, In step S3, the crosslinking agent uses a glutaraldehyde solution or genipin; the concentration of the crosslinking agent solution is 2 - 10 wt%.

8. The method for preparing a variable wet adsorption gel film using electrostatic spraying according to claim 1, characterized in that, In step S5, the carbonate-based base solution uses a sodium carbonate solution or a potassium carbonate solution with a concentration of 0.5 - 2.0 mol / L, and the hydroxide-based base solution uses a sodium hydroxide solution or a potassium hydroxide solution with a concentration of 0.5 - 2.0 mol / L; the time for soaking and carrying out the ion exchange reaction is 24h.

9. A moisture-variable adsorption gel film obtained by using the preparation method according to any one of claims 1 - 8.

10. A method for applying the moisture-variable adsorption gel film according to claim 9 to capture carbon dioxide in the air.

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