Gellan gum-based aerogel as well as preparation method and formaldehyde removal application thereof

Abstract

The invention belongs to the technical field of air purification, and particularly relates to gellan gum-based aerogel as well as a preparation method and formaldehyde removal application thereof. The preparation method of the gellan gum-based aerogel comprises the following steps: dissolving gellan gum in pure water at a preset temperature; the concentration of the gellan gum is 0.5 to 2 percent; adding sodium alginate and stirring until the sodium alginate is completely dissolved; the weight ratio of the sodium alginate to the gellan gum is (1: 3)-(1: 5); adding 10% wt of a CaCl2 solution while stirring; the weight ratio of Ca < 2 + > to sodium alginate is (1: 10)-(1: 15); carrying out a plurality of rounds of freeze-thaw cycles to form gel, and freeze-drying to obtain the gellan gum-based aerogel. The gellan gum-based aerogel disclosed by the invention can efficiently adsorb formaldehyde molecules in a relatively wide humidity range; after adsorption saturation, desorption can be realized through heating, so that cyclic utilization of the aerogel is realized; the used raw materials are all analysis reagent grades, are wide in source, easy to obtain and low in cost, and are beneficial to large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of air purification, and in particular relates to a gellan gum-based aerogel, a preparation method thereof, and formaldehyde removal application thereof. Background Art

[0002] Formaldehyde is a common indoor air pollutant that poses a serious threat to human health. Therefore, the development of efficient, environmentally friendly, and recyclable formaldehyde removal materials is of great practical significance. Currently, common methods for removing formaldehyde include adsorption, photocatalysis, and chemical absorption. Adsorption is widely used due to its ease of operation and low cost. However, the adsorption performance of traditional adsorbents such as activated carbon and zeolite is significantly affected by humidity, and their ability to adsorb formaldehyde decreases at high humidity levels. Summer's high temperatures and humidity are precisely the conditions in which formaldehyde is rapidly released, necessitating the development of adsorbent materials that are resistant to humidity interference. Summary of the Invention

[0003] The purpose of the present invention is to provide a gellan gum-based aerogel and its preparation method and formaldehyde removal application, so as to solve the technical problem that the existing formaldehyde adsorption materials have low adsorption capacity under high humidity.

[0004] In a first aspect, the present application provides a method for preparing a gellan gum-based aerogel, comprising: Dissolve gellan gum in pure water at a preset temperature; the concentration of the gellan gum is 0.5-2%; Add sodium alginate and stir until completely dissolved; the weight ratio of sodium alginate to gellan gum is 1:3-1:5; Add 10%wtCaCl2 solution under stirring; Ca 2+ The weight ratio with sodium alginate is 1:10-1:15; Several freeze-thaw cycles were performed to form a gel, which was lyophilized to obtain gellan gum-based aerogel.

[0005] In one embodiment of the present application, the temperature of the pure water is 60°C.

[0006] In one embodiment of the present application, each freeze-thaw cycle includes freezing in liquid nitrogen and thawing at room temperature.

[0007] In a second aspect, the present application provides a gellan gum-based aerogel, which is prepared using the preparation method described above.

[0008] The third aspect of the present application provides a formaldehyde removal application of the gellan gum-based aerogel as described above.

[0009] The beneficial effects of the present invention are: The gellan gum-based aerogel of the present invention has the following beneficial effects: (1) Excellent adsorption performance: Through the unique cross-linked network structure design, it can efficiently adsorb formaldehyde molecules in a wide humidity range, reducing the interference of humidity on adsorption capacity.

[0010] (2) Good recyclability: It has good recyclability. After adsorption saturation, it can be desorbed by heating, thereby realizing the recycling of aerogel, reducing use costs and reducing resource waste; (3) Simple preparation process: The entire preparation process has a simple operation flow, and the raw materials used are all analytical reagent grade, widely available, easy to obtain, and low in cost, which is conducive to large-scale industrial production; (4) Outstanding environmental performance: Based on natural materials, aerogel has good biocompatibility and environmental friendliness, and has broad application prospects and market potential in the field of indoor air formaldehyde removal.

[0011] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description and the drawings.

[0012] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 1 is a SEM image of the aerogels prepared in Examples 1-4 of the present invention; Figure 2 This is a diagram showing the effect of aerogel adsorption of formaldehyde at 80% humidity in various embodiments of the present invention; Figure 3 This is a diagram showing the effect of aerogel adsorption of formaldehyde at 20% humidity in various embodiments of the present invention; Figure 4 Schematic diagram of the formaldehyde adsorption and formaldehyde release effects of the aerogel prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0016] Example 1 (1) Heat pure water to 60°C, add gellan gum powder with a concentration of 0.5% while stirring, and stir until completely dissolved; (2) Add sodium alginate with a weight ratio of sodium alginate to gellan gum of 1:3 and stir until completely dissolved; (3) Add 10%wt CaCl2 solution while stirring. 2+ The weight ratio of sodium alginate is 1:10, and stirring is carried out for 30 minutes; (4) Two freeze-thaw cycles (freezing in liquid nitrogen and thawing at room temperature) were performed to form a gel, which was then freeze-dried in a freeze dryer to obtain gellan gum-based aerogel.

[0017] Example 2 (1) Heat pure water to 60°C, add gellan gum powder with a concentration of 1% while stirring, and stir until completely dissolved; (2) Add sodium alginate with a weight ratio of sodium alginate to gellan gum of 1:3 and stir until completely dissolved; (3) Add 10%wt CaCl2 solution while stirring. 2+ The weight ratio of sodium alginate is 1:10, and stirring is carried out for 30 minutes; (4) Two freeze-thaw cycles (freezing in liquid nitrogen and thawing at room temperature) were performed to form a gel, which was then freeze-dried in a freeze dryer to obtain gellan gum-based aerogel.

[0018] Example 3 (1) Heat pure water to 60°C, add gellan gum powder with a concentration of 1% while stirring, and stir until completely dissolved; (2) Add sodium alginate with a weight ratio of sodium alginate to gellan gum of 1:3 and stir until completely dissolved; (3) Add 10%wt CaCl2 solution while stirring. 2+ The weight ratio of sodium alginate is 1:12, and stirring is carried out for 30 minutes; (4) Two freeze-thaw cycles (freezing in liquid nitrogen and thawing at room temperature) were performed to form a gel, which was then freeze-dried in a freeze dryer to obtain gellan gum-based aerogel.

[0019] Example 4 (1) Heat pure water to 60°C, add gellan gum powder with a concentration of 2% while stirring, and stir until completely dissolved; (2) Add sodium alginate with a weight ratio of sodium alginate to gellan gum of 1:5 and stir until completely dissolved; (3) Add 10%wt CaCl2 solution while stirring. 2+ The weight ratio of sodium alginate is 1:15, and stirring is carried out for 30 minutes; (4) Two freeze-thaw cycles (freezing in liquid nitrogen and thawing at room temperature) were performed to form a gel, which was then freeze-dried in a freeze dryer to obtain gellan gum-based aerogel. Figure 1 These are SEM images of the aerogels prepared in Examples 1-4. Examples 1-3 have porous and loose structures, while Example 4 has a relatively dense structure.

[0020] Formaldehyde removal rate testing: In a 200L sealed chamber, the temperature and humidity were controlled at 25°C and 20% or 25°C and 80%. A heating plate was preheated to 80°C. 50 μL of formaldehyde solution was dripped into a glass Petri dish, which was placed on the heating plate and heated for 5 minutes to completely volatilize the formaldehyde. Heating was then stopped. Then, 10 g of the sample prepared in Examples 1-4 of the present invention was placed in the chamber. Samples were collected at different time points using an atmospheric sampler, and the values ​​were recorded.

[0021] The aerogels prepared in Examples 1-4 and commercial activated carbon (Sky Blue brand columnar activated carbon) were tested for formaldehyde adsorption at 80% and 20% humidity, respectively. Formaldehyde removal rate testing: The temperature and humidity in a 200L sealed chamber were controlled at 25°C and 80% (or 20%). A heating plate was preheated to 80°C in the chamber. 50µl of formaldehyde solution was dripped into a glass petri dish and placed on the heating plate. The dish was heated for 5 minutes to completely volatilize the formaldehyde, and then the heating was stopped. Then, 10g of the sample prepared in Example 1 of the present invention was placed on the heating plate. Samples were taken at 12h intervals using an atmospheric sampler, and the values ​​were recorded. The heating plate was turned on at 12h, 36h, and 60h, respectively, and maintained at 80°C for 12h. The heating plate was then turned off.

[0022] Adsorption effect see Figure 2 and Figure 3 As can be seen from the figure, the activated carbon's ability to remove formaldehyde is significantly weakened under high humidity, with 60% formaldehyde remaining after 24 hours. The aerogels prepared in Examples 1-4 have a high formaldehyde removal rate, with only 1% remaining after 24 hours. Under low humidity, both the activated carbon and the aerogels prepared in Examples 1-4 have a high formaldehyde removal rate. Compared to the approximately 6% formaldehyde remaining after 24 hours of activated carbon adsorption, the aerogels prepared in Examples 1-4 have a higher formaldehyde removal rate, reaching 1-2%.

[0023] The aerogel prepared in Example 1 was tested for formaldehyde adsorption and formaldehyde release upon heating. Figure 4.

[0024] Test of formaldehyde adsorption and formaldehyde release upon heating: The temperature and humidity in a 200L sealed cabin are controlled at 25°C and 80%, respectively. The heating platform is preheated to 80°C in the cabin, 50ul of formaldehyde solution is dripped into a glass culture dish and placed on the heating platform for heating for 5 minutes to completely volatilize the formaldehyde, and then the heating is stopped. Then 10g of the sample prepared in Example 1 of the present invention is placed on the heating platform, and sampling is performed at intervals of 12 hours using an atmospheric sampler, and the values ​​are recorded. The heating platform is turned on at 12h, 36h, and 60h, respectively, to maintain 80°C for 12h, and then the heating platform is turned off. In the unheated state, the aerogel can remove 99% of formaldehyde in 12h. After heating, the aerogel desorbs and releases formaldehyde into the cabin. After stopping heating, the aerogel resumes the adsorption effect and continues to reduce the formaldehyde concentration. After 3 cycles, the aerogel still maintains an efficient formaldehyde removal effect.

[0025] In summary, the gellan gum-based formaldehyde-removal aerogel prepared in this invention can be widely used in the field of indoor air formaldehyde removal. By placing the aerogel in an indoor environment, it can effectively adsorb formaldehyde molecules in the air, reducing formaldehyde concentration, purifying indoor air, significantly improving indoor environmental quality, and creating a healthy and comfortable living and working environment for people.

[0026] It should be noted that the various devices selected in this application (components whose specific structures are not described) are all universal standard parts or components known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or through conventional experimental methods.

[0027] Based on the above-mentioned ideal embodiment of the present invention, and through the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical concept of the present invention. The technical scope of the present invention is not limited to the contents of the specification.

Claims

1. A method for preparing gellan gum-based aerogel, characterized in that: include: Dissolve gellan gum in pure water at a preset temperature; the concentration of the gellan gum is 0.5-2%; Add sodium alginate and stir until completely dissolved; The weight ratio of sodium alginate to gellan gum is 1:3-1:5; Add 10%wtCaCl2 solution under stirring; Ca 2+ The weight ratio with sodium alginate is 1:10-1:15; Several freeze-thaw cycles were performed to form a gel, which was lyophilized to obtain gellan gum-based aerogel.

2. The method for preparing gellan gum-based aerogel according to claim 1, wherein: The temperature of the pure water is 60°C.

3. The method for preparing gellan gum-based aerogel according to claim 1, wherein: Each freeze-thaw cycle consisted of freezing in liquid nitrogen and thawing at room temperature.

4. A gellan gum-based aerogel, characterized in that The preparation method is as described in any one of claims 1 to 3.

5. Use of the gellan gum-based aerogel according to claim 4 for removing formaldehyde.

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