Formaldehyde removal color-changing gel and its preparation method and application

Abstract

The present invention belongs to the field of formaldehyde removal, and discloses a formaldehyde removal color-changing gel, a preparation method thereof, and an application thereof. The formaldehyde removal color-changing gel of the present invention solves the problem that the prior art formaldehyde removal color-changing gel has poor adhesion performance and is difficult to directly adhere to common furniture materials such as wood boards, glass, and plastics, thereby reducing the probability of contact between the gel and formaldehyde and failing to fully exert the formaldehyde removal performance of the gel. The method of the present invention uses tannic acid, dopamine, chitosan, etc. as raw materials, and the prepared formaldehyde removal color-changing gel contains a large number of hydrophobic micelles and hydrophilic groups, so it has good adhesion performance and mechanical properties, can be placed in various environments where formaldehyde volatilizes, and improves formaldehyde removal performance.

Description

Technical Field

[0001] The invention belongs to the field of formaldehyde removal and relates to a formaldehyde removal color-changing gel and a preparation method and application thereof. Background Art

[0002] Formaldehyde is a common air pollutant, released by wooden furniture, flooring, paint, curtains, carpets, wallpaper, and decorative items—basically, common household items. Formaldehyde has been designated a carcinogen and teratogen by the World Health Organization because it can damage protein and DNA structures.

[0003] Color-changing formaldehyde removal gel is a novel formaldehyde removal product that primarily relies on the slow release of chlorine dioxide to oxidize and decompose formaldehyde. Its effectiveness is visually identified through a color change. The gel typically consists of two parts: a gel containing a chlorine dioxide precursor and an activation solution containing an organic acid. The activation solution is added dropwise to the gel to release chlorine dioxide. This product offers a high formaldehyde removal rate and stable chlorine dioxide release.

[0004] However, current formaldehyde-removing color-changing gels have poor adhesion properties, making them difficult to adhere directly to common furniture materials like wood, glass, and plastic. This reduces the gel's chance of contact with formaldehyde and prevents it from fully utilizing its formaldehyde-removing properties. Furthermore, gels are often made from natural materials like gelatin and carrageenan, which have poor mechanical properties and stability.

[0005] Therefore, there is an urgent need for a formaldehyde removal color-changing gel with good adhesion and mechanical properties, which can be placed in various environments where formaldehyde volatilizes to improve the formaldehyde removal performance. Summary of the Invention

[0006] In order to overcome the defects of the above-mentioned prior art, the present invention proposes a new formaldehyde removal color-changing gel, which has good adhesion and mechanical properties and can be placed in various environments where formaldehyde volatilizes to improve formaldehyde removal performance.

[0007] The present invention provides a method for preparing a formaldehyde removal color-changing gel, the method comprising the following steps:

[0008] Step 1: Add a cationic surfactant and octadecyl methacrylate to pure water, stir, and then add acrylic acid to obtain solution A.

[0009] Step 2: Dissolve tannic acid and natural gelling agent in deionized water, slowly add EDC and NHS under nitrogen protection and stir for the first time, then add dopamine and chitosan, adjust the pH value of the mixed solution to the range of 5.0~5.5, stir for the second time to obtain solution B.

[0010] Step 3: Add the solution A obtained in step 1 to the solution B obtained in step 2 under stirring in an ice-water bath, then add the chlorine dioxide precursor and methylene blue and stir evenly; then add the initiator and ZnCl2 solution and stir evenly.

[0011] Step 4: inject the mixed solution stirred evenly in step 3 into a mold and seal it at room temperature to complete the gelation process and obtain the formaldehyde removal color-changing gel.

[0012] In step 1, the cationic surfactant is selected from one or more of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, etc.; preferably, cetyltrimethylammonium bromide.

[0013] In step 1, the ratio of pure water, cationic surfactant, octadecyl methacrylate, and acrylic acid is (5-50) mL: (1-5) g: (0.5-2) g: (5-15) g; preferably, 20 mL: 2 g: 1 g: 10 g.

[0014] In step 1, the stirring time is 0.5-5 h; preferably, 3 h.

[0015] In step 2, the natural gelling agent is selected from one or more of gelatin, carrageenan, gellan gum, etc.; preferably, it is gellan gum.

[0016] In step 2, the first stirring time is 1-4 hours; preferably, 3 hours.

[0017] In step 2, the second stirring time is 2-4 hours; preferably, 3 hours.

[0018] In step 2, the ratio of tannic acid, natural gelling agent, EDC, NHS, dopamine, chitosan, and deionized water is: (0.5-1) g: (0.1-1) g: (0.5-1) g: (0.1-1) g: (0.1-1) g: (0.1-1) g: (50-200) mL; preferably, 1 g: 0.1-1 g: 0.8 g: 0.4 g: 0.8 g: 0.3 g: 100 mL.

[0019] In step 3, the chlorine dioxide precursor is selected from sodium chlorite, potassium chlorite, barium chlorite, magnesium chlorite or a mixture thereof; preferably, it is sodium chlorite.

[0020] In step 3, the initiator is one or more of ammonium persulfate, potassium persulfate, etc.

[0021] In step 4, the sealing time is 1-10 minutes; preferably, 5 minutes.

[0022] In one embodiment, the gel preparation step is:

[0023] 1. Add 2 g of cationic surfactants (cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyldimethylbenzyl ammonium chloride) and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and then add 10 g of acrylic acid to obtain solution A.

[0024] 2. Weigh 1 g of tannic acid and 0.1-1 g of a natural gelling agent (gelatin, carrageenan, gellan gum) and dissolve them in 100 mL of deionized water. Slowly add 0.8 g of EDC and 0.4 g of NHS under nitrogen protection. Then, after stirring for 20 min, add 0.8 g of dopamine and 0.3 g of chitosan. Adjust the pH of the mixed solution to 5.0-5.5 and stir for 8 h to obtain Solution B.

[0025] 3. While stirring in an ice-water bath, slowly add the solution A to the solution B, then add 1 g of a chlorine dioxide precursor (sodium chlorite, potassium chlorite, barium chlorite, magnesium chlorite, or a mixture thereof) and 0.01 g of methylene blue and stir until uniform.

[0026] 4. Add 0.1g initiator (ammonium persulfate, potassium persulfate) and 120uL 0.2mol / L ZnCl2 solution and stir evenly.

[0027] 5. The mixed solution is injected into the mold and sealed at room temperature for a few minutes to complete the gel process.

[0028] The present invention also provides the formaldehyde-removing color-changing gel prepared by the method.

[0029] The present invention also provides application of the formaldehyde removal color-changing gel in formaldehyde removal and the like.

[0030] The beneficial effects of the present invention are as follows: the formaldehyde removal color-changing gel network prepared by the present invention contains a large number of hydrophobic micelles and hydrophilic groups, such as -COOH, -OH and catechol groups, which can form various interactions with the surface of the target substrate to improve adhesion performance. For example, the catechol group adheres to the hydrophobic material through hydrophobic interactions, and can also form hydrogen bonds with silicates on glass and -CN groups on the rubber surface. Through hydrogen bonds, electrostatic interactions and cation-π bonds, the hydrogel can interact with -NH2 or -COOH groups. The -COOH and -OH groups in the hydrogel segments can also promote adhesion to various materials through electrostatic interactions and hydrogen bonds. In addition, the cationic surfactant neutralizes the long hydrophobic alkyl chain of octadecyl methacrylate, reducing the hygroscopicity of the gel and avoiding the influence of humidity in the air on adhesion performance.

[0031] On the other hand, the multiple interactions within the formaldehyde removal and color-changing gel prepared by the present invention increase the cross-linking density of its internal network, thereby producing excellent mechanical properties. For example, dopamine interacts with the -NH2 of chitosan, the -COOH and -OH groups of polyacrylic acid, natural colloids, and tannic acid, generating numerous hydrogen bonds. The positively charged quaternary ammonium groups of the cationic surfactant form electrostatic interactions with the -COOH groups of polyacrylic acid, natural colloids, and tannic acid in the hydrogel network. In addition, Zn 2+ The ions coordinate with the -COOH groups on the polyacrylic acid chain, the -NH2 of chitosan and the -OH groups in natural colloids and tannic acid to form ionic crosslinking points. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the SEM image of the gel prepared in Examples 1-4 of the present invention, wherein: Figure 1 a is the SEM image of the gel prepared in Example 1, Figure 1 b is the SEM image of the gel prepared in Example 2, Figure 1 c is the SEM image of the gel prepared in Example 3, Figure 1 d is the SEM image of the gel prepared in Example 4. DETAILED DESCRIPTION

[0033] The present invention is further described in detail with reference to the following specific examples and accompanying drawings. The processes, conditions, experimental methods, etc. for implementing the present invention, except for those specifically mentioned below, are common knowledge and common common sense in the art and are not particularly limited by the present invention.

[0034] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention, its application, or use. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0035] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0036] Example 1:

[0037] 1. Add 2 g of hexadecyltrimethylammonium bromide and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and then add 10 g of acrylic acid to obtain solution A.

[0038] 2. Weigh 1 g of tannic acid and 1 g of gelatin and dissolve them in 100 mL of deionized water. Slowly add 0.8 g of EDC and 0.4 g of NHS under nitrogen protection. Then, add 0.8 g of dopamine and 0.3 g of chitosan after stirring for 20 min. Adjust the pH value of the mixed solution to 5.0-5.5 and stir for 8 h to obtain Solution B.

[0039] 3. Under stirring in an ice-water bath, slowly add all of the solution A obtained in step 1 to all of the solution B obtained in step 2, and then add 1g of sodium chlorite and methylene blue and stir evenly.

[0040] 4. Add 0.1g ammonium persulfate and 120uL 0.2mol / L ZnCl2 solution and stir evenly.

[0041] 5. The mixed solution is injected into the mold and sealed at room temperature for 5 minutes to complete the gelation process and obtain the formaldehyde removal color-changing gel.

[0042] Example 2:

[0043] 1. Add 2 g of hexadecyltrimethylammonium chloride and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and then add 10 g of acrylic acid to obtain solution A.

[0044] 2. Weigh 1 g of tannic acid and 0.5 g of carrageenan and dissolve them in 100 mL of deionized water. Slowly add 0.8 g of EDC and 0.4 g of NHS under nitrogen protection. Then, add 0.8 g of dopamine and 0.3 g of chitosan after stirring for 20 min. Adjust the pH value of the mixed solution to 5.0-5.5 and stir for 8 h to obtain solution B.

[0045] 3. Slowly add all the solution A obtained in step 1 to all the solution B obtained in step 2 while stirring in an ice-water bath, then add 1 g of potassium chlorite and methylene blue, and stir evenly.

[0046] 4. Add 0.1g ammonium persulfate and 120uL 0.2mol / L ZnCl2 solution and stir evenly.

[0047] 5. The mixed solution is injected into the mold and sealed at room temperature for 5 minutes to complete the gelation process and obtain the formaldehyde removal color-changing gel.

[0048] Example 3:

[0049] 1. Add 2 g of octadecyltrimethylammonium chloride and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and then add 10 g of acrylic acid to obtain solution A.

[0050] 2. Weigh 1 g of tannic acid and 0.1 g of gellan gum and dissolve them in 100 mL of deionized water. Slowly add 0.8 g of EDC and 0.4 g of NHS under nitrogen protection. Then, add 0.8 g of dopamine and 0.3 g of chitosan after stirring for 20 min. Adjust the pH value of the mixed solution to 5.0-5.5 and stir for 8 h to obtain solution B.

[0051] 3. Under stirring in an ice-water bath, slowly add all of the solution A obtained in step 1 to all of the solution B obtained in step 2, then add 1 g of barium chlorite and methylene blue, and stir evenly.

[0052] 4. Add 0.1g initiator ammonium persulfate and 120uL 0.2mol / L ZnCl2 solution and stir evenly.

[0053] 5. The mixed solution is injected into the mold and sealed at room temperature for 5 minutes to complete the gelation process and obtain the formaldehyde removal color-changing gel.

[0054] Example 4:

[0055] 1. Add 2 g of dodecyldimethylbenzyl ammonium chloride and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and then add 10 g of acrylic acid to obtain solution A.

[0056] 2. Weigh 1 g of tannic acid and 0.5 g of gelatin and dissolve them in 100 mL of deionized water. Slowly add 0.8 g of EDC and 0.4 g of NHS under nitrogen protection. Then, add 0.8 g of dopamine and 0.3 g of chitosan after stirring for 20 min. Adjust the pH value of the mixed solution to 5.0-5.5 and stir for 8 h to obtain Solution B.

[0057] 3. Under stirring in an ice-water bath, slowly add all of the solution A obtained in step 1 to all of the solution B obtained in step 2, then add 1 g of magnesium chlorite and methylene blue, and stir evenly.

[0058] 4. Add 0.1g ammonium persulfate and 120uL 0.2mol / L ZnCl2 solution and stir evenly.

[0059] 5. The mixed solution is injected into the mold and sealed at room temperature for 5 minutes to complete the gelation process and obtain the formaldehyde removal color-changing gel.

[0060] Comparative Example 1:

[0061] 1. Add 2 g of hexadecyltrimethylammonium bromide and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and then add 10 g of acrylic acid to obtain solution A.

[0062] 2. Weigh 1 g of tannic acid and 1 g of gelatin and dissolve them in 100 mL of deionized water. Slowly add 0.8 g of EDC and 0.4 g of NHS under nitrogen protection. Then, add 0.8 g of dopamine and 0.3 g of chitosan after stirring for 20 min. Adjust the pH value of the mixed solution to 5.0-5.5 and stir for 8 h to obtain Solution B.

[0063] 3. Slowly add all the solution A obtained in step 1 to all the solution B obtained in step 2 while stirring in an ice-water bath, then add methylene blue and stir evenly.

[0064] 4. Add 0.1g ammonium persulfate and 120uL 0.2mol / L ZnCl2 solution and stir evenly.

[0065] 5. The mixed solution is injected into the mold and sealed at room temperature for 5 minutes to complete the gel process.

[0066] Comparative Example 2:

[0067] 0.5 g of carrageenan was dissolved in 100 mL of deionized water to obtain a gel.

[0068] SEM: SEM images of the gels prepared in Examples 1-4 of the present invention are as follows: Figure 1 As shown, according to Figure 1 It can be seen that the gel prepared by the present invention has a dense structure.

[0069] Application Example 1 Formaldehyde adsorption experiment:

[0070] In a 200-liter sealed chamber, the temperature and humidity were controlled at 27°C and 30%. A heating plate was preheated to 80°C. 150 μl of formaldehyde solution was dripped into a glass petri dish and placed on the heating plate for 30 minutes to allow the formaldehyde to completely evaporate. Then, 100 g of gel samples prepared in Examples 1-4 of the present invention and Comparative Example 1 were placed in the chamber. Samples were collected using an atmospheric sampler at 0 h and 24 h. The formaldehyde removal rate (%) was calculated as: (initial formaldehyde concentration - formaldehyde concentration at 24 h) / initial formaldehyde concentration × 100%. The results are shown in Table 1.

[0071]

[0072] Application Example 2: Color Change Reaction Test

[0073] The formaldehyde removal gel prepared by the present invention is placed in an activation solution, and a color change reaction is observed.

[0074] (1) Preparation of activation solution: Place 15g of anhydrous citric acid in a 100g beaker and add 85g of deionized water to prepare the activation solution.

[0075] (2) Weigh 200g of the formaldehyde removal gel of Examples 1-4 of the present invention and Comparative Example 1, and add 2g of activation liquid to each sample. The test results are shown in Table 2:

[0076]

[0077] Application Example 3 Adhesion Performance Test:

[0078] Evaluation was performed using a universal testing machine (Instron 5500). The hydrogels adhered to various substrates, including wood, glass, and rubber, with a bonding area of ​​20 mm x 20 mm. The adhesion strengths of the hydrogels to wood, glass, and rubber in air are shown in Table 3. The hydrogels prepared in Examples 1-4 of the present invention exhibited significantly higher adhesion strengths than those in Comparative Example 2.

[0079]

[0080] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0081] As used in the present invention, the term "comprising" is an open expression, that is, including the contents specified in the present invention, but not excluding other aspects.

[0082] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0083] Although the embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a formaldehyde removal color-changing gel, characterized in that: The method comprises the following steps: Step 1: Add a cationic surfactant and octadecyl methacrylate to pure water, stir, and then add acrylic acid to obtain solution A; the ratio of pure water, cationic surfactant, octadecyl methacrylate, and acrylic acid is (5-50) mL: (1-5) g: (0.5-2) g: (5-15) g; Step 2: Dissolve tannic acid and a natural gelling agent in deionized water, slowly add EDC and NHS under nitrogen protection and stir for the first time, then add dopamine and chitosan, adjust the pH value of the mixed solution to a range of 5.0-5.5, and stir for the second time to obtain solution B; the ratio of tannic acid, natural gelling agent, EDC, NHS, dopamine, chitosan, and deionized water is: (0.5-1) g: (0.1-1) g: (0.5-1) g: (0.1-1) g: (0.1-1) g: (0.1-1) g: (50-200) mL; Step 3: Add the solution A obtained in step 1 to the solution B obtained in step 2 under stirring in an ice-water bath, then add a chlorine dioxide precursor and methylene blue and stir evenly; then add an initiator and a ZnCl2 solution and stir evenly; the chlorine dioxide precursor is selected from sodium chlorite, potassium chlorite, barium chlorite, magnesium chlorite or a mixture thereof; Step 4: inject the mixed solution stirred evenly in step 3 into a mold and seal it at room temperature to complete the gelation process and obtain the formaldehyde removal color-changing gel.

2. The method according to claim 1, wherein In step 1, the cationic surfactant is selected from one or more of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium chloride, and dodecyldimethylbenzylammonium chloride; and / or the stirring time is 0.5-5 h.

3. The method according to claim 1, wherein In step 2, the natural gelling agent is selected from one or more of gelatin, carrageenan, and gellan gum.

4. The method according to claim 1, wherein In step 2, the first stirring time is 1-4 hours; and / or the second stirring time is 2-4 hours.

5. The method according to claim 1, wherein In step 3, the initiator is one or both of ammonium persulfate and potassium persulfate.

6. The method according to claim 1, wherein In step 4, the sealing time is 1-10 minutes.

7. The formaldehyde-removing color-changing gel prepared by the method according to any one of claims 1 to 6.

8. Use of the formaldehyde removal color-changing gel as claimed in claim 7 in removing formaldehyde.

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