Membrane material, formic acid sensor and formic acid detection method
By using a phase-separated water storage structure composed of hydrophobic polymers and amphiphilic surfactants, the problems of high price, slow response and humidity interference of existing formic acid sensors are solved, realizing low-cost and rapid formic acid detection and ensuring accurate monitoring in high humidity environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-11-22
- Publication Date
- 2026-05-22
AI Technical Summary
Existing formic acid sensors are expensive, not portable, slow to respond, and humidity severely interferes with the sensing film, while pH indicators have short lifespans.
A membrane material composed of hydrophobic polymers, pH indicators, and amphiphilic surfactants is used to form a phase-separated water storage structure, which suppresses humidity interference and extends the indicator life. The pH indicator is physically embedded to detect pH changes caused by formic acid vapor.
It is simple to prepare, low in cost, and fast in response. It can accurately monitor formic acid under high humidity conditions. The sensing membrane does not deactivate under acidic conditions and the thin film structure is stable.
Smart Images
Figure CN122072238A_ABST
Abstract
Description
Technical Field
[0001] This application relates to a membrane material, a formic acid sensor, and a method for detecting formic acid, belonging to the field of sensors. Background Technology
[0002] Formic acid is a common organic acid in the environment, colorless and with a pungent odor. It possesses properties of both acid and aldehyde. In nature, formic acid is often found in the venom sprays of certain ant species and in the secretions released by some stinging nettles. At low concentrations, it can be used as a food preservative, an insecticide, and an additive in industrial products such as food and cosmetics. However, when the concentration of formic acid in the environment is high, its corrosive nature can cause burns and blisters on the skin and damage the mucous membranes of the eyes, mouth, throat, and respiratory system. Inhaling concentrated formic acid can cause difficulty breathing, and swallowing concentrated acid can lead to severe ulcers (sores) in the digestive tract, as well as pain and nausea. Prolonged exposure to high concentrations of formic acid may cause liver or kidney damage. In addition, formic acid vapors released during industrial production can form explosive mixtures with air, which can ignite and explode upon contact with open flames or high heat. Therefore, it is crucial to develop a sensor device for detecting formic acid. Most commercial formic acid sensors currently available suffer from drawbacks such as high cost, lack of portability, and slow response. In contrast, colorimetric sensors have gained widespread attention due to their low cost, rapid response, convenient detection, and portability. The phase separation structure employed in this invention suppresses the interference of humidity on the sensing film and effectively extends the lifespan of the pH indicator, thus possessing broad practical value. Summary of the Invention
[0003] According to one aspect of this application, a membrane material is provided, comprising a hydrophobic polymer, a pH indicator, and an amphiphilic surfactant;
[0004] The proportions of each substance are as follows:
[0005] 100-500 parts of hydrophobic polymer;
[0006] pH indicator 1-20 parts;
[0007] 100-1000 parts of amphiphilic surfactant.
[0008] The hydrophobic polymer is selected from at least one of polymethyl methacrylate, polyvinyl butyral, polyvinyl chloride, polypropylene, ethyl cellulose, and polyvinylidene fluoride;
[0009] The degree of polymerization of the hydrophobic polymer is 10,000 to 1,000,000;
[0010] The pH indicator is selected from at least one of methyl orange, tetrabromophenol blue, bromocresol green, chlorophenol red, alizarin red, Congo red, acid fuchsin, xylenol orange, bromocresol violet, bromophenol blue, methyl orange, tetrabromophenol blue, bromocresol green, chlorophenol red, alizarin red, Congo red, acid fuchsin, xylenol orange, bromocresol violet, and bromophenol blue;
[0011] The amphiphilic surfactant is selected from at least one of Span, tributyl phosphate, Tween, and Triton.
[0012] According to another aspect of this application, a formic acid sensor is provided by coating a substrate surface with a solvent solution containing the above-mentioned membrane material and drying it to obtain the formic acid sensor.
[0013] Formic acid can be effectively detected by using a physically embedded pH indicator to measure the pH changes caused by the hydration of formic acid vapor with water molecules in the polymer film water storage layer to form formic acid.
[0014] The solvent is selected from at least one of methanol, ethanol, toluene, and N,N-dimethylformamide;
[0015] In the mixed solvent solution containing the membrane material according to any one of claims 1 or 2, the content of the hydrophobic polymer in the membrane material is 0.01 to 0.1 g / ml.
[0016] The drying process is vacuum drying;
[0017] The vacuum degree of the drying process is 10^ -1 ~10^ -5 pa;
[0018] The drying temperature is 10–100°C;
[0019] The drying time is 10 to 120 minutes.
[0020] The substrate is selected from plastic and / or glass.
[0021] In the formic acid sensor, a hydrophobic polymer serves as the substrate, a pH indicator sensing molecule, and an amphiphilic surfactant forms the working layer and water storage layer. The membrane formed on the substrate surface after the membrane material is dried has a phase-separated water storage structure and exhibits acid and high humidity resistance.
[0022] According to another aspect of this application, a method for detecting formic acid is provided, comprising the following steps:
[0023] (1) Obtain the working curve:
[0024] At room temperature, the formic acid sensor described above is placed in the gas detection chamber. First, air is introduced to obtain a stable baseline. Then, the gas chambers containing formic acid solutions of different concentrations are replaced. After the film color stabilizes, the color value of the sensing film is recorded. The working curve is obtained by plotting the formic acid solution concentration on the x-axis and the film color value on the y-axis.
[0025] (2) Determination of unknown samples:
[0026] At room temperature, the formic acid sensor described above is placed in a gas detection chamber containing a formic acid solution of unknown concentration. After the film color stabilizes, the color value of the sensing film is recorded. The concentration of formic acid in the formic acid solution of unknown concentration can be calculated by substituting the color value into the working curve.
[0027] The color value is either an RGB value or an HSV value.
[0028] The beneficial effects that this application can produce include:
[0029] 1. This detection method utilizes an acid-resistant and high-humidity formic acid sensing membrane based on a phase-separated water storage structure to detect formic acid. The indicator of this sensing membrane will not be deactivated under acidic conditions, and it is simple to prepare, has a fast response speed, and is low in cost.
[0030] 2. The introduction of amphiphilic surfactants in this detection method forms a hydrophobic / hydrophilic separation layer on the film surface, which inhibits the penetration of water molecules in the ambient air, cuts off the water molecule exchange channels inside and outside the traditional formic acid sensing membrane based on pH indicators, and maintains the stability of the film structure.
[0031] 3. In this detection method, a water storage layer is used instead of environmental bound water, which ensures accurate monitoring of formic acid under high humidity conditions. Attached Figure Description
[0032] Figure 1 The graph shows the linear relationship between formic acid solutions of different concentrations and H value in Example 1.
[0033] Figure 2 This is a linear relationship graph between formic acid solutions of different concentrations and the value of B in Example 2.
[0034] Figure 3 The graph shows the linear relationship between formic acid solutions of different concentrations and the R value in Example 3.
[0035] Figure 4 The graph shows the linear relationship between formic acid solutions of different concentrations and the G value in Example 4.
[0036] Figure 5 This is a graph showing the correspondence between the G value and formic acid solutions of different concentrations in Example 4.
[0037] Figure 6This is a linear relationship graph between formic acid solutions of different concentrations and the R value in Example 5.
[0038] Figure 7 This is a graph showing the relationship between time and H value in Example 6.
[0039] Figure 8 This is a graph showing the relationship between time and G value in Example 7. Detailed Implementation
[0040] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0041] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0042] Example 1
[0043] In this embodiment, the transparent matrix of the formic acid sensitive film is selected as 0.125g of polyvinyl chloride, which is dissolved in a mixed solution of ethanol, toluene and methanol (2ml of ethanol, 0.5ml of methanol and 1ml of toluene), and then 0.5ml of Triton X114 and 10mg of tetrabromophenol blue are added. After uniform mixing, the solution is uniformly coated on the PET substrate and placed in a vacuum desiccator to dry at room temperature for 20min.
[0044] At room temperature, the prepared sensor was placed in a gas chamber. Air was first introduced into the gas detection chamber to obtain a stable baseline. Then, gas chambers containing formic acid solution concentrations of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5% were used. After the thin film color stabilized, the color value of the sensing film was recorded, and the H-value change curve was plotted. Figure 1 .
[0045] Example 2
[0046] In this embodiment, the transparent matrix of the formic acid sensitive film is selected from 0.125g of ethyl cellulose and 0.25g of polyvinylidene fluoride. It is dissolved in 3ml of toluene solution, and then 0.5ml of Tween and 20mg of chlorophenol red are added. After uniform mixing, the solution is uniformly coated on the PET substrate and placed in a vacuum desiccator to dry at 35°C for 15min.
[0047] At room temperature, the prepared sensor was placed in a gas chamber. Air was first introduced into the gas detection chamber to obtain a stable baseline. Then, gas chambers containing formic acid solution concentrations of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5% were used. After the thin film color stabilized, the color value of the sensing film was recorded, and the B-value change curve was plotted. Figure 2 .
[0048] Example 3
[0049] In this embodiment, the transparent matrix of the formic acid sensitive film is selected as 0.2g of polymethyl methacrylate, which is dissolved in 20ml of tetrahydrofuran solution, and then 5ml of Triton X100 and 5mg of bromocresol green are added. After uniform mixing, the solution is uniformly coated on the PET substrate and placed in a vacuum desiccator to dry at 20°C for 40min.
[0050] At room temperature, the prepared sensor was placed in a gas chamber. Air was first introduced into the gas detection chamber to obtain a stable baseline. Then, gas chambers containing formic acid solution concentrations of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5% were used. After the thin film color stabilized, the color value of the sensing film was recorded, and the R-value change curve was plotted. Figure 3 .
[0051] Example 4
[0052] In this embodiment, the transparent matrix of the formic acid sensitive film is 0.2g of polyvinyl butyral, which is dissolved in 3ml of ethanol solution, and then 1ml of Span 80 and 2.5mg of xylenol orange are added. After uniform mixing, the solution is uniformly coated on the PET substrate and placed in a vacuum desiccator to dry at 35°C for 20min.
[0053] At room temperature, the prepared sensor was placed in a gas chamber. Air was first introduced into the gas detection chamber to obtain a stable baseline. Then, gas chambers containing formic acid solution concentrations of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5% were introduced. After the thin film color stabilized, the color value of the sensing film was recorded, and the G-value change curve was plotted. Figure 4 .
[0054] Prepare five gas chambers containing formic acid solutions of 0.5%, 1.5%, 2%, 3.5%, and 5% respectively. Cover the concentration labels and conduct random tests. Identify the corresponding concentration based on the color value. Compare the experimental results with the actual results and summarize them onto an image, such as... Figure 5 .
[0055] Example 5
[0056] In this embodiment, the transparent matrix of the formic acid sensitive film is selected as 0.1g of polyvinylidene fluoride, which is dissolved in 3ml of N,N-dimethylformamide solution, and then 0.5ml of Tween 20 and 15mg of bromocresol purple are added. After uniform mixing, the solution is uniformly coated on the PET substrate and placed in a vacuum desiccator to dry at room temperature for 30min.
[0057] At room temperature, the prepared sensor was placed in a gas chamber. Air was first introduced into the gas detection chamber to obtain a stable baseline. Then, gas chambers containing formic acid solution concentrations of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5% were used. After the thin film color stabilized, the color value of the sensing film was recorded, and the R-value change curve was plotted. Figure 6 .
[0058] Example 6
[0059] In this embodiment, the transparent matrix of the formic acid sensitive film is 0.175g of polypropylene, which is dissolved in 2ml of ethanol, and then 0.5ml of Triton X114 and 6mg of Congo red are added. After homogenization, the solution is evenly coated on the PET substrate and placed in a vacuum desiccator to dry at room temperature for 30min.
[0060] At room temperature, the prepared sensor was placed in a gas chamber. Air was first introduced into the gas detection chamber to obtain a stable baseline. Then, nitrogen gas with 100% humidity was introduced into the gas chamber. After the thin film color stabilized, the color value of the sensing film was recorded, and the H-value change curve was plotted. Figure 7 .
[0061] Example 7
[0062] In this embodiment, the transparent matrix of the formic acid sensitive film is selected as 0.1g of polyvinyl chloride, which is dissolved in 1.5ml of methanol, and then 0.125ml of tributyl phosphate and 12mg of alizarin red are added. After uniform mixing, the solution is uniformly coated on the PET substrate and placed in a vacuum desiccator to dry at 40°C for 10min.
[0063] At room temperature, the prepared sensor was placed in a gas chamber. Air was first introduced into the gas detection chamber to obtain a stable baseline. The chamber was then replaced with a gas chamber containing a 10% formic acid solution. After the thin film color stabilized, the color value of the sensing film was recorded, and the G-value change curve was plotted. Figure 8 .
[0064] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A membrane material, characterized in that, Including hydrophobic polymers, pH indicators, and amphiphilic surfactants; The proportions of each substance are as follows: 100-500 parts of hydrophobic polymer; pH indicator 1-20 parts; 100-1000 parts of amphiphilic surfactant.
2. The membrane material according to claim 1, characterized in that, The hydrophobic polymer is selected from at least one of methyl methacrylate, polyvinyl butyral, polyvinyl chloride, polypropylene, ethyl cellulose, and polyvinylidene fluoride; The degree of polymerization of the hydrophobic polymer is 10,000 to 1,000,000; The pH indicator is selected from at least one of methyl orange, tetrabromophenol blue, bromocresol green, chlorophenol red, and alizarin; The amphiphilic surfactant is selected from at least one of Span, Tween, and Triton.
3. A formic acid sensor, characterized in that, A solvent solution containing the membrane material according to any one of claims 1 or 2 is coated onto the surface of a substrate and dried to obtain the formic acid sensor.
4. The formic acid sensor according to claim 3, characterized in that, The solvent is selected from at least one of methanol, ethanol, toluene, and N,N-dimethylformamide; The content of the hydrophobic polymer in the solvent solution is 0.01 to 0.1 g / ml.
5. The formic acid sensor according to claim 3, characterized in that, The drying process is vacuum drying; The vacuum degree of the drying process is 10^ -1 ~10^ -5 pa; The drying temperature is 10–100°C; The drying time is 10 to 120 minutes.
6. The formic acid sensor according to claim 3, characterized in that, The substrate is selected from plastic and / or glass.
7. A method for detecting formic acid, characterized in that, Includes the following steps: (1) Obtain the working curve: At room temperature, the formic acid sensor according to any one of claims 3 to 6 is placed in the gas detection chamber. First, air is introduced to obtain a stable baseline. Then, the gas chamber containing formic acid solutions of different concentrations is replaced. After the film color stabilizes, the color value of the sensing film is recorded. The working curve is obtained by plotting the formic acid solution concentration as the abscissa and the film color value as the ordinate. (2) Determination of unknown samples: At room temperature, the formic acid sensor according to any one of claims 3 to 6 is placed in a gas detection chamber containing a formic acid solution of unknown concentration. After the film color stabilizes, the color value of the sensing film is recorded, and the concentration of formic acid in the formic acid solution of unknown concentration can be calculated by substituting it into the working curve.
8. The method according to claim 7, characterized in that, The color value is either an RGB value or an HSV value.