阅读说明：本技术 一种可视化检测气液体中甲醛水凝胶及其制备方法和应用 (Visual detection of formaldehyde hydrogel in gas-liquid, and preparation method and application thereof ) 是由 谭文渊 陈琦 袁东 王竹青 付大友 于 2021-08-20 设计创作，主要内容包括：本发明提供了一种可视化检测气液体中甲醛水凝胶及其制备方法和应用,属于水凝胶技术领域。本发明通过将水凝胶前驱体溶液与浸泡吸附法和冻融循环法相结合的方法,得到了一种可视化检测气液体中甲醛的水凝胶,该水凝胶能够与甲醛发生化学反应,生成化合物吖嗪。在酸性溶液存在下,吖嗪被铁离子氧化生成蓝色化合物,在紫外可见吸收光谱中表现为600～650nm处有强吸收峰,水凝胶随着甲醛浓度的不同而发生颜色深浅变化,从而能对甲醛进行可视化检测。(The invention provides a hydrogel for visually detecting formaldehyde in gas and liquid, and a preparation method and application thereof, and belongs to the technical field of hydrogels. The hydrogel for visually detecting formaldehyde in gas and liquid is obtained by combining a hydrogel precursor solution with a soaking adsorption method and a freeze-thawing circulation method, and the hydrogel can chemically react with formaldehyde to generate a compound azine. In the presence of an acid solution, azine is oxidized by iron ions to generate a blue compound, a strong absorption peak is shown at a position of 600-650 nm in an ultraviolet visible absorption spectrum, and hydrogel generates color depth change along with different formaldehyde concentrations, so that formaldehyde can be visually detected.)

1. A preparation method for visually detecting formaldehyde hydrogel in gas and liquid is characterized by comprising the following steps:

preparing a hydrogel precursor solution:

respectively preparing polyvinyl alcohol and polyacrylate monomers into aqueous solutions by using a glycerol aqueous solution as a solvent; mixing a polyvinyl alcohol aqueous solution, a polyacrylate monomer aqueous solution, a cross-linking agent, a catalyst and a thermal initiator to obtain a hydrogel precursor solution;

preparation of hydrogel:

injecting the hydrogel precursor solution into a mold, and heating to form gel; washing the colloid and then respectively soaking the colloid in deionized water and a 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution; and (4) freezing and unfreezing the soaked colloid for circulation to obtain the formaldehyde hydrogel in the visual detection gas-liquid.

2. The method for preparing hydrogel according to claim 1, wherein the hydrogel precursor solution is prepared from the following raw materials in parts by weight: 2-10 parts of polyvinyl alcohol, 10-25 parts of polyacrylate monomer, 4-9 parts of glycerol aqueous solution, 0.5-1 part of cross-linking agent, 0.05-0.1 part of catalyst and 0.5-1 part of thermal initiator;

the volume concentration of the glycerol aqueous solution is 5-10%.

3. The method for preparing the hydrogel according to claim 2, wherein the polyacrylate monomer comprises one or more of acrylamide, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate and methyl methacrylate.

4. The method for preparing the hydrogel according to claim 3, wherein the crosslinking agent comprises one or more of N, N' -methylenebisacrylamide, tripropylene glycol diacrylate and trimethylolpropane triacrylate;

the catalyst is N, N, N ', N' -tetramethyl ethylene diamine;

the thermal initiator comprises one or more of potassium sulfate, sodium persulfate and ammonium persulfate.

5. The method for preparing the hydrogel according to claim 4, wherein the temperature for heating to form the gel is 55-65 ℃ and the heating time is 0.5-1 h.

6. The method for producing a hydrogel according to claim 5, wherein the 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution has a mass concentration of 0.10 to 0.50%.

7. The method for preparing the hydrogel according to claim 6, wherein the colloid is soaked in the deionized water for 2 to 4 hours, and the colloid is soaked in the 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution for 2 to 6 hours.

8. The method for preparing the hydrogel according to claim 7, wherein the soaked gel is frozen at a temperature of-20 to-30 ℃; the number of the freezing-thawing cycles is 2-5.

9. Visual detection of formaldehyde hydrogel in gas-liquid obtained by the preparation method of any one of claims 1 to 8.

10. The use of the hydrogel in a visual inspection gas-liquid according to claim 9 for detecting the formaldehyde content in air or water.

Technical Field

The invention relates to the technical field of hydrogel, in particular to hydrogel for visually detecting formaldehyde in gas and liquid and a preparation method and application thereof.

Background

Formaldehyde is an organic chemical substance, also called formil, a colorless gas with strong pungent odor and high toxicity, and has an irritant effect on human eyes, noses and the like. Formaldehyde is readily soluble in water and ethanol. The concentration of the aqueous solution can reach 55 percent at most, is generally 35 to 40 percent and is usually 37 percent, and the aqueous solution is called formalin, which is commonly called formalin. Formaldehyde is an important industrial raw material and is widely used for production of adhesives, veneers, paints and coatings, textile dyeing auxiliaries, sterilization and corrosion prevention. Formaldehyde has strong damage to the central nervous system, retina, lung and liver of a human body, and can trigger endocrine dysfunction and skin diseases. In 2017, 10 and 27, in a carcinogen list published by the international cancer research institution of the world health organization, formaldehyde is put in a carcinogen list. In 2019, 7 and 23 months, the first record of toxic and harmful water pollutants is listed in the department of ecological environment of China.

Formaldehyde gas is one of the most prominent indoor pollutants, and the concentration rises year by year. The boards, paints, carpets, wallpaper, etc. commonly used for interior decoration contain and release formaldehyde. Incomplete combustion of fuel and tobacco leaves also releases formaldehyde. Formaldehyde is also commonly used as a preservative and disinfectant, and a small amount of formaldehyde can be used in food production as a bactericidal preservative because of its bacteriostatic effect. In the early days of beer production, formaldehyde was generally used as an auxiliary material to accelerate the clarification speed of beer in order to further accelerate the sedimentation speed of floc in beer. Because formaldehyde generates stronger toxicity and strong carcinogenic effect to human bodies, the use of formaldehyde as a food additive in the food processing process is prohibited by the plain regulation of China at present. However, some of the unscrupulous people still use formaldehyde as an additive in the processing of certain foods in order to gain economic benefits. For example, a certain amount of formaldehyde added into aquatic products can prolong the shelf life and increase the water retention; the addition of formaldehyde to flour or rice flour can whiten the skin. In addition, when products such as garlic and ginger are detected, the formaldehyde content of part of the products is seriously exceeded, which is mainly caused by spraying formaldehyde on the surfaces of the garlic and the ginger by some illegal traders in order to prolong the shelf life of the products. In addition, formaldehyde is listed as one of the national detection indexes of drinking water as a disinfectant byproduct. In order to ensure the health of human bodies and quickly, sensitively and accurately detect the concentration of formaldehyde, the formaldehyde detection method is very important.

The existing formaldehyde detection methods mainly comprise spectrophotometry, colorimetry, electrochemistry, chromatography, fluorescence, chemiluminescence, ion selective electrode method and the like, wherein except the colorimetry, other formaldehyde detection methods all need corresponding professional instruments, so that the operation is relatively complex, and a user is required to perform certain instrument operation. A plurality of formaldehyde detection reagents, test paper and the like based on a colorimetric method are available on the market, the quality guarantee period of the reagents is short, and the storage conditions are harsh. These detection methods are not simple to use, require formaldehyde detection under specific conditions, and even involve the mixed use of a plurality of reagents, and have many factors affecting the detection results. In addition, the existing formaldehyde test paper is generally a single test paper, can only detect formaldehyde in air or formaldehyde in solution, and rarely can meet the requirements at the same time.

Therefore, the problem that the visual detection of the formaldehyde hydrogel in the gas and the liquid is simple to operate and convenient to detect is urgently needed to be solved in the prior art.

Disclosure of Invention

The invention aims to provide a hydrogel for visually detecting formaldehyde in gas and liquid, and a preparation method and application thereof.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method for visually detecting formaldehyde hydrogel in gas and liquid, which comprises the following steps:

preparing a hydrogel precursor solution:

respectively preparing polyvinyl alcohol and polyacrylate monomers into aqueous solutions by using a glycerol aqueous solution as a solvent; mixing a polyvinyl alcohol aqueous solution, a polyacrylate monomer aqueous solution, a cross-linking agent, a catalyst and a thermal initiator to obtain a hydrogel precursor solution;

preparation of hydrogel:

injecting the hydrogel precursor solution into a mold, and heating to form gel; washing the colloid and then respectively soaking the colloid in deionized water and a 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution; and (4) freezing and unfreezing the soaked colloid for circulation to obtain the formaldehyde hydrogel in the visual detection gas-liquid.

Further, the hydrogel precursor solution is prepared from the following raw materials in parts by weight: 2-10 parts of polyvinyl alcohol, 10-25 parts of polyacrylate monomer, 4-9 parts of glycerol aqueous solution, 0.5-1 part of cross-linking agent, 0.05-0.1 part of catalyst and 0.5-1 part of thermal initiator.

Further, the volume concentration of the glycerol aqueous solution is 5-10%.

Further, the polyacrylate monomer comprises one or more of acrylamide, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate and methyl methacrylate.

Further, the cross-linking agent comprises one or more of N, N' -methylene bisacrylamide, tripropylene glycol diacrylate and trimethylolpropane triacrylate.

Further, the catalyst is N, N, N ', N' -tetramethyl ethylenediamine.

Further, the thermal initiator comprises one or more of potassium sulfate, sodium persulfate and ammonium persulfate.

Furthermore, the temperature for heating and gelling is 55-65 ℃, and the heating time is 0.5-1 h.

Furthermore, the mass concentration of the 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution is 0.10-0.50%.

Furthermore, the colloid is soaked in the deionized water for 2-4 hours, and the colloid is soaked in the 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution for 2-6 hours.

Further, freezing the soaked colloid at the temperature of-20 to-30 ℃; the number of the freezing-thawing cycles is 2-5.

The invention provides a visual detection method of formaldehyde hydrogel in gas and liquid.

The invention provides an application of formaldehyde hydrogel in gas-liquid visual detection in detecting formaldehyde content in air or water.

The invention has the beneficial effects that:

the hydrogel prepared by the invention has high water content and large specific surface area, enhances the formaldehyde absorption capacity, and is more beneficial to the chemical reaction between formaldehyde and 3-methyl-2-benzothiazolinone hydrazone hydrochloride hydrate; and secondary crosslinking is carried out after freeze-thaw cycling of the gel and hydrogen bonds are formed, so that the stability of the 3-methyl-2-benzothiazolinone hydrazone hydrochloride is improved. In addition, the hydrogel detection method has the advantages of obvious color change, simple and convenient operation, no human error, rapidness, accuracy, strong specificity, high sensitivity and low cost. And the quality guarantee period is long, and the requirement of on-site detection can be met.

Drawings

FIG. 1 is a graph of the UV-VIS absorption spectra of the hydrogel of example 1 at various formaldehyde concentrations;

FIG. 2 shows the concentration of formaldehyde in a liquid (mg/m)³) And a linear relation graph of an absorption peak of the ultraviolet-visible absorption spectrum at 620 nm;

FIG. 3 shows the concentration of formaldehyde in a liquid (mg/m)³) A plot of color change versus gel;

FIG. 4 is a color change chart of the result of detection of the liquid sample 1;

FIG. 5 shows the concentration of formaldehyde in the gas (mg/m)³) And a linear relation graph of an absorption peak of the ultraviolet-visible absorption spectrum at 620 nm;

FIG. 6 shows the concentration of formaldehyde in the gas (mg/m)³) A plot of color change versus gel;

FIG. 7 is a color change chart of the result of detection of gas sample 2.

Detailed Description

The invention provides a preparation method for visually detecting formaldehyde hydrogel in gas and liquid, which comprises the following steps:

preparing a hydrogel precursor solution:

respectively preparing polyvinyl alcohol and polyacrylate monomers into aqueous solutions by using a glycerol aqueous solution as a solvent; mixing a polyvinyl alcohol aqueous solution, a polyacrylate monomer aqueous solution, a cross-linking agent, a catalyst and a thermal initiator to obtain a hydrogel precursor solution;

preparation of hydrogel:

injecting the hydrogel precursor solution into a mold, and heating to form gel; washing the colloid and then respectively soaking the colloid in deionized water and a 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution; and (4) freezing and unfreezing the soaked colloid for circulation to obtain the formaldehyde hydrogel in the visual detection gas-liquid.

In the invention, the hydrogel precursor solution is prepared from the following raw materials in parts by weight: 2-10 parts of polyvinyl alcohol, 10-25 parts of polyacrylate monomer, 4-9 parts of glycerol aqueous solution, 0.5-1 part of cross-linking agent, 0.05-0.1 part of catalyst and 0.5-1 part of thermal initiator.

In the invention, the addition amount of the polyvinyl alcohol is 2-10 parts by weight, preferably 3-8 parts by weight, and more preferably 4-6 parts by weight.

In the invention, the addition amount of the polyacrylate monomer is 10-25 parts by weight, preferably 12-22 parts by weight, and more preferably 15-20 parts by weight. The polyacrylate monomer comprises one or more of acrylamide, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate and methyl methacrylate; preferably one or more of acrylamide, hydroxypropyl methacrylate and methyl methacrylate; further preferred is hydroxypropyl methacrylate.

In the present invention, the glycerol aqueous solution is added in an amount of 4 to 9 parts by weight, preferably 5 to 8 parts by weight, and more preferably 6 to 7 parts by weight. The glycerol aqueous solution has a volume concentration of 5 to 10%, preferably 6 to 9%, and more preferably 7 to 8%.

In the invention, the addition amount of the cross-linking agent is 0.5-1 part by weight, preferably 0.6-0.9 part by weight, and more preferably 0.7-0.8 part by weight. The cross-linking agent comprises one or more of N, N '-methylene bisacrylamide, tripropylene glycol diacrylate and trihydroxy methyl propane triacrylate, preferably N, N' -methylene bisacrylamide and/or tripropylene glycol diacrylate, and more preferably tripropylene glycol diacrylate.

In the invention, the addition amount of the catalyst is 0.05-0.1 part by weight, preferably 0.06-0.08 part by weight, and more preferably 0.07-0.08 part by weight. The catalyst is preferably N, N, N ', N' -tetramethylethylenediamine.

In the invention, the addition amount of the thermal initiator is 0.5 to 1 part by weight, preferably 0.6 to 0.9 part by weight, and more preferably 0.7 to 0.9 part by weight. The thermal initiator comprises one or more of potassium sulfate, sodium persulfate and ammonium persulfate, and potassium sulfate is preferred.

In the invention, the temperature for heating and gelling is 55-65 ℃, preferably 58-62 ℃, and further preferably 60 ℃; the heating time is 0.5 to 1 hour, preferably 0.6 to 0.8 hour, and more preferably 0.7 hour.

In the present invention, the mass concentration of the 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution is 0.10 to 0.50%, preferably 0.20 to 0.40%, and more preferably 0.30%.

In the invention, the colloid is soaked in deionized water for 2-4 h, preferably 3 h; the time for soaking the colloid in the 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution is 2-6 h, preferably 3-5 h, and further preferably 4 h.

In the invention, the soaked colloid is frozen at the temperature of-20 to-30 ℃, preferably-22 to-28 ℃, and more preferably-25 ℃; the number of the freezing-thawing cycles is 2 to 5, preferably 3 to 4.

The invention provides a visual detection method of formaldehyde hydrogel in gas and liquid.

The invention provides an application of formaldehyde hydrogel in gas-liquid visual detection in detecting formaldehyde content in air or water, which specifically comprises the following steps:

exposing the hydrogel in a sample or environment to be detected, or dripping a liquid sample to be detected on the hydrogel, then dripping an acidic ferric ammonium sulfate solution, observing color change or measuring an ultraviolet visible absorption spectrum to judge the intensity of absorbance with the wavelength of 600-650 nm.

In the present invention, the mass concentration of the acidic ammonium ferric sulfate solution is 0.1 to 4%, preferably 0.5 to 3%, and more preferably 1 to 2%.

The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.

Example 1

Weighing a certain amount of 3-methyl-2-benzothiazolinone hydrazone hydrochloride, dissolving the 3-methyl-2-benzothiazolinone hydrazone hydrochloride in deionized water to prepare a 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution with the mass concentration of 0.30%;

weighing a certain amount of ammonium ferric sulfate, dissolving the ammonium ferric sulfate in 0.1% dilute sulfuric acid solution, and preparing an acidic ammonium ferric sulfate solution with the mass concentration of 4%;

preparing a 2% polyvinyl alcohol solution and a 10% acrylamide solution by taking a 10% glycerol aqueous solution in volume concentration as a solvent and respectively taking polyvinyl alcohol and acrylamide as solutes; mixing 5 parts of polyvinyl alcohol solution and 15 parts of acrylate monomer solution, and then sequentially adding 0.5 part of N, N ' -methylene bisacrylamide, 0.05 part of N, N, N ', N ' -tetramethyl ethylenediamine and 0.5 part of potassium persulfate to obtain hydrogel precursor solution;

injecting the gel precursor solution into a circular mold with the thickness of 3mm and the diameter of 2cm, placing the circular mold in an oven, heating for 1h at 65 ℃, taking out the circular mold after gelling, placing the circular mold in deionized water, washing and soaking for 2h, then integrally soaking the circular mold in a 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution with the mass concentration of 0.30%, replacing the 3-methyl-2-benzothiazolinone hydrazone hydrochloride aqueous solution at least once after soaking for 2h, continuing soaking for 12h, then placing the circular mold in a refrigerator at-20 ℃, freezing the circular mold, completely freezing the circular mold, thawing the circular mold at room temperature for 2h, freezing and thawing the circular mold into a cycle, and after absorbing surface moisture, obtaining the formaldehyde hydrogel in the visual detection gas liquid.

Example 2

Detecting formaldehyde in the liquid:

blank group: first 0.1mL of the test solution was added dropwise to the hydrogel of example 1. After 10min of reaction, 0.3mL of 4% acidic ammonium ferric sulfate solution was added dropwise, at which time the gel gradually turned blue and the color became stable after 5 min. The absorbance of the hydrogel was measured at a wavelength of 620nm, using water as a reference. The relationship between formaldehyde concentration and absorbance is shown in FIG. 2. The relationship between formaldehyde concentration and gel color is shown in FIG. 3.

Experimental groups: taking a solution of a fresh product fresh-keeping ice block melted at normal temperature as a sample 1, detecting the sample 1 (the method is the same as the blank group), and displaying that the absorbance of the hydrogel at 620nm is 0.532, and calculating to obtain the concentration of about 0.87mg/m³The color change is shown in figure 4, and the concentration obtained by comparing the color change with the color relation in figure 3 is 0.5-1 mg/m³The method is consistent with the absorbance result, and the feasibility of the method for visually detecting the formaldehyde hydrogel is verified. And the sample 1 is measured and compared by adopting an acetylacetone colorimetric method in the industry standard NY 5172-2002 of Ministry of agriculture to obtain the sample 1 with the concentration of 0.861mg/m³And visual detection of formaldehyde hydrogel in gas-liquidThe test results are close, and the method is proved to be effective.

Example 3

Detecting formaldehyde in the gas:

blank group: the hydrogel of example 1 was first placed in a closed environment to be tested. After 20min of reaction, 0.3mL of 4% acidic ammonium ferric sulfate solution was added dropwise, at which time the gel gradually turned blue, and the color tended to stabilize after 5 min. The absorbance of the hydrogel was measured at a wavelength of 620nm, using water as a reference. The relationship between formaldehyde concentration and absorbance is shown in FIG. 4. The relationship between formaldehyde concentration and gel color is shown in FIG. 5.

Experimental groups: taking the indoor air of a laboratory in a laboratory building as a sample 2, detecting the indoor air (the method is the same as the blank group), sealing all doors and windows of the laboratory in the testing process, and displaying that the absorbance of the hydrogel at 620nm is 0.479, and calculating to obtain the concentration of about 1.56mg/m³The color change is shown in figure 7, and the concentration is 1.5-2.5 mg/m after the color change is compared with the color relation in figure 6³The method is consistent with the absorbance result, and the feasibility of the method for visually detecting the formaldehyde hydrogel is verified. And a phenol reagent colorimetric method in formaldehyde in the air of a public place (GB/T18204.26-2000 first method) is adopted to carry out determination and comparison on the sample 2 to obtain the sample 2 with the concentration of 1.526mg/m³The method is close to the test result of visually detecting the formaldehyde hydrogel in the gas and liquid, and the method is proved to be effective.

The embodiment of the invention provides a visual detection method of formaldehyde hydrogel in gas and liquid, and a preparation method and application thereof. The hydrogel prepared by the invention has high water content and large specific surface area, enhances the formaldehyde absorption capacity, and is more beneficial to the chemical reaction between formaldehyde and 3-methyl-2-benzothiazolinone hydrazone hydrochloride hydrate; and secondary crosslinking is carried out after freeze-thaw cycling of the gel and hydrogen bonds are formed, so that the stability of the 3-methyl-2-benzothiazolinone hydrazone hydrochloride is improved. In addition, the hydrogel detection method has the advantages of obvious color change, simple and convenient operation, no human error, rapidness, accuracy, strong specificity, high sensitivity and low cost. And the quality guarantee period is long, and the requirement of on-site detection can be met.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.