Formaldehyde-removing color-changing gel as well as preparation method and application thereof

Abstract

The invention belongs to the field of formaldehyde removal, and discloses formaldehyde removal color-changing gel as well as a preparation method and application thereof. According to the formaldehyde-removing color-changing gel disclosed by the invention, the defects that the formaldehyde-removing color-changing gel in the prior art is relatively poor in adhesion property and difficult to directly adhere to common furniture materials such as wood plates, glass and plastics, so that the contact probability of the gel and formaldehyde is reduced, and the formaldehyde-removing property of the gel cannot be fully exerted are overcome. According to the method, tannic acid, dopamine, chitosan and the like are used as raw materials, and the prepared formaldehyde-removing color-changing gel contains a large number of hydrophobic micelles and hydrophilic groups, so that the formaldehyde-removing color-changing gel has good adhesion performance and mechanical performance and can be placed in various environments where formaldehyde volatilizes, and the formaldehyde-removing performance is improved.

Description

Technical Field

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

[0002] Formaldehyde is a common air pollutant. It is commonly found in wooden furniture, floors, paints, curtains, carpets, wallpapers, ornaments, etc. Basically, common items in households release formaldehyde. Since formaldehyde can damage the structures of proteins and DNA, it has been determined by the World Health Organization as a carcinogenic and teratogenic substance.

[0003] The formaldehyde-removing color-changing gel is a new formaldehyde-removing product. It mainly relies on the slow release of chlorine dioxide to oxidize and decompose formaldehyde, and visually and directly identifies the effectiveness of the product through color change. The color-changing gel generally consists of two parts: a gel containing a chlorine dioxide precursor and an activation solution containing an organic acid. When in use, the activation solution is dropped into the gel to release chlorine dioxide, which has the advantages of high removal rate of formaldehyde and stable release of chlorine dioxide.

[0004] However, at present, the adhesion performance of the formaldehyde-removing color-changing gel is poor, and it is difficult to directly adhere to common furniture materials such as wood boards, glass, and plastics, thereby reducing the contact probability between the gel and formaldehyde and failing to fully exert the formaldehyde-removing performance of the gel. Moreover, the gel is often prepared from natural materials such as gelatin and carrageenan, and the mechanical properties and stability of the gel are poor.

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

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

[0007] The present invention provides a preparation method of a formaldehyde-removing color-changing gel, and the method includes the following steps: Step 1: Add a cationic surfactant and octadecyl methacrylate to pure water. After stirring, add acrylic acid to obtain solution A.

[0008] Step 2: Dissolve tannic acid and a natural gelling agent in deionized water. Slowly add EDC and NHS under nitrogen protection and perform the first stirring, and then add dopamine and chitosan. Adjust the pH value of the mixed solution to the range of 5.0-5.5 and perform the second stirring to obtain solution B.

[0009] Step 3: Under stirring in an ice-water bath, add the solution A obtained in Step 1 to the solution B obtained in Step 2, then add a chlorine dioxide precursor and methylene blue and stir evenly; then add an initiator and a ZnCl2 solution and stir evenly.

[0010] Step 4: Inject the mixed solution obtained by stirring evenly in Step 3 into a mold and seal it at room temperature to complete the gelation process and obtain the formaldehyde-removing color-changing gel.

[0011] In Step 1, the cationic surfactant is selected from one or more of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, etc.; preferably, it is cetyltrimethylammonium bromide.

[0012] In Step 1, the ratio of the pure water, cationic surfactant, octadecyl methacrylate, and acrylic acid is (5 - 50) mL: (1 - 5) g: (0.5 - 2) g: (5 - 15) g; preferably, it is 20 mL: 2 g: 1 g: 10 g.

[0013] In Step 1, the stirring time is 0.5 - 5 h; preferably, it is 3 h.

[0014] In Step 2, the natural gelling agent is selected from one or more of gelatin, carrageenan, gellan gum, etc.; preferably, it is gellan gum.

[0015] In Step 2, the first stirring time is 1 - 4 h; preferably, it is 3 h.

[0016] In Step 2, the second stirring time is 2 - 4 h; preferably, it is 3 h.

[0017] 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, it is 1 g: 0.1 - 1 g: 0.8 g: 0.4 g: 0.8 g: 0.3 g: 100 mL.

[0018] 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.

[0019] In Step 3, the initiator is one or more of ammonium persulfate, potassium persulfate, etc.

[0020] In Step 4, the sealing time is 1 - 10 min; preferably, it is 5 min.

[0021] In a specific embodiment, the steps for preparing the gel are as follows: 1. Add 2 g of a cationic surfactant (cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyldimethylbenzylammonium 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.

[0022] 2. Weigh 1 g of tannic acid and 0.1 - 1 g of a natural gelling agent (gelatin, carrageenan, gellan gum), 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 the range of 5.0 - 5.5, and stir for 8 h to obtain Solution B.

[0023] 3. Under stirring in an ice - water bath, slowly add Solution A to 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 evenly.

[0024] 4. Then add 0.1 g of an initiator (ammonium persulfate, potassium persulfate) and 120 μL of a 0.2 mol / L ZnCl₂ solution and stir evenly.

[0025] 5. Inject the mixed solution into a mold and seal it at room temperature for a few minutes to complete the gelation process.

[0026] The present invention also provides a formaldehyde - removing color - changing gel prepared by the above method.

[0027] The present invention also provides the application of the formaldehyde - removing color - changing gel in formaldehyde removal and the like.

[0028] The beneficial effects of the present invention are as follows: The formaldehyde - removing 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 the adhesion performance. For example, the catechol group adheres to the hydrophobic material through hydrophobic interaction, 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 chain segments can also promote adhesion to various materials through electrostatic interactions and hydrogen bonds. In addition, the cationic surfactant neutralizes the long hydrophobic alkyl chains of octadecyl methacrylate, reducing the hygroscopicity of the gel and avoiding the influence of air humidity on the adhesion performance.

[0029] On the other hand, the multiple interactions within the formaldehyde-removing color-changing gel prepared by the present invention increase the crosslinking density of its internal network, thereby producing excellent mechanical properties. For example, the -NH2 of dopamine interacts with the -COOH and -OH groups of chitosan, polyacrylic acid, natural colloid, and tannic acid, generating many hydrogen bonds. The positively charged quaternary ammonium group of the cationic surfactant forms electrostatic interactions with the -COOH of polyacrylic acid, natural colloid, and tannic acid in the hydrogel network. In addition, Zn 2+ ions coordinate with the -COOH groups on the polyacrylic acid chain, the -NH2 of chitosan, and the -OH groups in natural colloid and tannic acid to form ionic crosslinking points. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The SEM images of the gels prepared in Examples 1-4 of the present invention are shown, where 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 OF THE INVENTION

[0031] In combination with the following specific examples and drawings, the present invention will be further described in detail. The processes, conditions, experimental methods, etc. for implementing the present invention are all common knowledge and well-known common sense in the art except for the specifically mentioned content below, and the present invention has no particularly restricted content.

[0032] The following description of at least one exemplary embodiment is merely illustrative in nature and in no way limits the present invention or its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts fall within the scope of protection of the present invention.

[0033] In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0034] Example 1: 1. Add 2 g of cetyltrimethylammonium 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.

[0035] 2. Weigh 1 g of tannic acid and 1 g of gelatin, 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 the range of 5.0 - 5.5, and stir for 8 h to obtain solution B.

[0036] 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 1 g of sodium chlorite and methylene blue and stir evenly.

[0037] 4. Then add 0.1 g of ammonium persulfate and 120 μL of 0.2 mol / L ZnCl₂ solution, and stir evenly.

[0038] 5. Inject the mixed solution into a mold and seal it at room temperature for 5 minutes to complete the gelation process, obtaining a formaldehyde - removing color - changing gel.

[0039] Example 2: 1. Add 2 g of cetyltrimethylammonium chloride and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and add 10 g of acrylic acid to obtain solution A.

[0040] 2. Weigh 1 g of tannic acid and 0.5 g of carrageenan, 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 the range of 5.0 - 5.5, and stir for 8 h to obtain solution B.

[0041] 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 1 g of potassium chlorite and methylene blue, and stir evenly.

[0042] 4. Then add 0.1 g of ammonium persulfate and 120 μL of 0.2 mol / L ZnCl₂ solution, and stir evenly.

[0043] 5. Inject the mixed solution into a mold and seal it at room temperature for 5 minutes to complete the gelation process, obtaining a formaldehyde - removing color - changing gel.

[0044] Example 3: 1. Add 2 g of octadecyltrimethylammonium chloride and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and add 10 g of acrylic acid to obtain solution A.

[0045] 2. Weigh 1 g of tannic acid and 0.1 g of gellan gum, 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 the range of 5.0 - 5.5, and stir for 8 h to obtain Solution B.

[0046] 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.

[0047] 4. Then add 0.1 g of initiator ammonium persulfate and 120 μL of 0.2 mol / L ZnCl₂ solution, and stir evenly.

[0048] 5. Inject the mixed solution into a mold and seal it at room temperature for 5 minutes to complete the gelation process, obtaining a formaldehyde - removing color - changing gel.

[0049] Example 4: 1. Add 2 g of dodecyldimethylbenzylammonium chloride and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and add 10 g of acrylic acid to obtain Solution A.

[0050] 2. Weigh 1 g of tannic acid and 0.5 g of gelatin, 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 the range of 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 magnesium chlorite and methylene blue, and stir evenly.

[0052] 4. Then add 0.1 g of ammonium persulfate and 120 μL of 0.2 mol / L ZnCl₂ solution, and stir evenly.

[0053] 5. Inject the mixed solution into a mold and seal it at room temperature for 5 minutes to complete the gelation process, obtaining a formaldehyde - removing color - changing gel.

[0054] Comparative Example 1: 1. Add 2 g of cetyltrimethylammonium bromide and 1 g of octadecyl methacrylate to 20 mL of pure water, stir for 3 h, and add 10 g of acrylic acid to obtain Solution A.

[0055] 2. Weigh 1 g of tannic acid and 1 g of gelatin, 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 the range of 5.0 - 5.5, and stir for 8 h to obtain solution B.

[0056] 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 methylene blue and stir evenly.

[0057] 4. Then add 0.1 g of ammonium persulfate and 120 μL of 0.2 mol / L ZnCl₂ solution, and stir evenly.

[0058] 5. Inject the mixed solution into a mold and seal it at room temperature for 5 minutes to complete the gelation process.

[0059] Comparative Example 2: Dissolve 0.5 g of carrageenan in 100 mL of deionized water to obtain a gel.

[0060] SEM: The SEM of the gels prepared in Examples 1 - 4 of the present invention is as Figure 1 shown. It can be seen from Figure 1 that the gels prepared by the present invention have a dense structure.

[0061] Application Example 1 Formaldehyde Adsorption Experiment: Control the temperature and humidity in a 200 L closed chamber to 27 °C and 30%. Pre - heat the heating table in the chamber to 80 °C, drop 150 μL of formaldehyde solution into a glass petri dish and place it on the heating table to heat for 30 min to completely volatilize the formaldehyde. Then put 100 g of the gel samples prepared in Examples 1 - 4 of the present invention and Comparative Example 1. Use an air sampler to sample at 0 h and 24 h respectively, and calculate the formaldehyde removal rate (%) according to the formula: formaldehyde removal rate (%) = (initial formaldehyde concentration - formaldehyde concentration at 24 h) / initial formaldehyde concentration × 100%. The results are shown in Table 1.

[0062]

[0063] Application Example 2 Color - change Reaction Test Place the formaldehyde - removing gel prepared by the present invention in the activation solution and observe the color - change reaction.

[0064] (1) Preparation method of the activation solution: Place 15 g of anhydrous citric acid in a beaker with a capacity of 100 g, and then add 85 g of deionized water to prepare the activation solution.

[0065] (2)Weigh 200 g of the formaldehyde-removing gels of Examples 1-4 and Comparative Example 1 of the present invention respectively, and add 2 g of the activation solution to each sample. The test results are shown in Table 2:

[0066] Application Example 3 Adhesion performance test: It was evaluated using a universal testing machine (Instron 5500). The hydrogel was adhered to the surfaces of various substrates, including wood, glass, and rubber, with a bonding area of 20 mm × 20 mm. The bonding strengths of the hydrogel to wood, glass, and rubber in air are shown in Table 3 respectively. The gels prepared in Examples 1-4 of the present invention are significantly higher in bonding strength than that in Comparative Example 2.

[0067]

[0068] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0069] As used in the present invention, the term "comprising" is an open expression, that is, it includes the content specified in the present invention, but does not exclude other aspects.

[0070] As used in the present invention, the term "and / or" includes any one and all combinations of one or more of the related listed items.

[0071] Although the embodiments of the present specification have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present specification. The scope of the present specification is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a formaldehyde-removing color-changing gel, characterized in that, The method comprises the following steps: Step 1: Add a cationic surfactant and octadecyl methacrylate into pure water. After stirring, add acrylic acid to obtain Solution A; Step 2: Dissolve tannic acid and a natural gelling agent in deionized water. Slowly add EDC and NHS under nitrogen protection and conduct the first stirring. Then add dopamine and chitosan, and adjust the pH value of the mixed solution to the range of 5.0 - 5.5, and conduct the second stirring to obtain Solution B; Step 3: Under ice - water bath stirring, add the Solution A obtained in Step 1 into the Solution B obtained in Step 2, then add a chlorine dioxide precursor and methylene blue and stir evenly; then add an initiator and a ZnCl₂ solution and stir evenly; 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 - removing color - changing gel.

2. The method according to claim 1, characterized in that, 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 1, the ratio of the pure water, cationic surfactant, octadecyl methacrylate, and acrylic acid is (5 - 50) mL : (1 - 5) g : (0.5 - 2) g : (5 - 15) g.

4. 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.

5. The method according to claim 1, wherein In Step 2, the time of the first stirring is 1 - 4 h; and / or, the time of the second stirring is 2 - 4 h.

6. The method according to claim 1, characterized in that, In Step 2, the ratio of the 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.

7. The method according to claim 1, wherein In Step 3, the chlorine dioxide precursor is selected from one or more of sodium chlorite, potassium chlorite, barium chlorite, magnesium chlorite or a mixture thereof; and / or, the initiator is one or two of ammonium persulfate and potassium persulfate.

8. The method according to claim 1, characterized in that, In Step 4, the sealing time is 1 - 10 min.

9. The formaldehyde - removing color - changing gel prepared by the method according to any one of claims 1 - 8.

10. The application of the formaldehyde - removing color - changing gel according to claim 9 in formaldehyde removal.

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