CN114481339B - A metal oxide nanofiber sensor, its preparation method and its application in detecting formaldehyde - Google Patents

Abstract

The invention discloses a metal oxide nanofiber sensor, a preparation method thereof and application thereof in formaldehyde detection, wherein the method comprises the following steps: dissolving a water-insoluble high molecular polymer in a solvent to obtain an electrospinning raw material; adding metal salt into the electrospinning raw material to obtain the electrospinning raw material doped with metal ions; inputting the electrospinning raw material doped with metal ions onto a spinneret and connecting the spinneret with a power supply for electrostatic spinning to obtain fibers; and depositing the fiber on an electrode of a quartz crystal microbalance, and then carrying out vacuum drying and calcining in the air atmosphere to obtain the metal oxide nanofiber sensor. The invention maintains the advantages of high surface area, porosity and the like of the nano-fiber, and realizes real-time, rapid, accurate and long-term formaldehyde detection by virtue of the advantages of low cost, high stability, simple working principle and the like of the metal oxide semiconductor material, the lowest detection limit can reach 26ppb, the nano-fiber can be continuously used for at least three weeks, and the stability is strong.

Description

A kind of metal oxide nanofiber sensor and its preparation method and in detecting formaldehyde application in

technical field

The invention relates to the technical field of formaldehyde detection, in particular to a metal oxide nanofiber sensor, a preparation method thereof and an application in formaldehyde detection.

Background technique

Formaldehyde is a common indoor pollutant and was listed as the first class of human carcinogens by the International Agency for Research on Cancer in 2004. The World Health Organization (WHO) has set a very strict 30-minute exposure limit, namely 80ppb, and my country has also stipulated a standard of 60ppb for the maximum allowable concentration of formaldehyde in the room air. Indoor formaldehyde has become a major health threat due to the increasing use of chemical adhesives.

So far, formaldehyde detection methods based on electrochemistry, high performance liquid chromatography, gas chromatography, spectrophotometry, polarography, and fluorescence have been established. Although these methods have some applications, their large-scale application is still limited due to high cost, complex operation, and especially poor adaptability to real-time detection.

Therefore, it is very necessary to explore small and portable instruments to monitor the concentration of formaldehyde in the environment in real time and solve the problems of high detection limit, low sensitivity, cumbersome operation, and long measurement time.

Contents of the invention

The purpose of the present invention is to provide a metal oxide nanofiber sensor and its preparation method and its application in the detection of formaldehyde. By constructing metal oxide nanofibers, while retaining the advantages of high surface area and porosity of the nanofibers themselves , with the advantages of low cost, high stability, and simple working principle of metal oxide semiconductor materials, real-time, fast, accurate, and long-term formaldehyde detection is realized. The minimum detection limit can reach 26ppb, and it can be used continuously for at least three weeks. Strong stability .

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

In a first aspect of the present invention, a method for preparing a metal oxide nanofiber sensor is provided, the method comprising:

Dissolving water-insoluble polymers in solvents to obtain electrospinning raw materials;

adding a metal salt to the electrospinning raw material to obtain an electrospinning raw material doped with metal ions; wherein the metal salt is composed of a variety of single metal salts containing different metals;

Inputting the electrospinning raw material doped with metal ions to a spinneret and connecting a power supply for electrospinning to obtain fibers;

The fibers are deposited on the electrodes of the quartz crystal microbalance, then vacuum-dried and calcined in the air atmosphere to obtain the metal oxide nanofiber sensor.

In the above technical solutions, multiple means two or more.

Further, the metal salt is added to the electrospinning raw material at a concentration of 0.01-0.5 mol/L, and the metal salt includes titanium tetrachloride, ferric hydroxide, ferric nitrate, copper acetate, copper carbonate, copper sulfate, Zinc acetate, zinc carbonate, zinc sulfate, copper nitrate, copper chloride, zinc chloride, zinc nitrate, zinc dihydrogen phosphate, tin methanesulfonate, tin ethanesulfonate, tin propanesulfonate, tin 2-propanesulfonate , at least one of cerium trichloride, cerium sulfate, ferric chloride, ferric sulfate, aluminum nitrate, aluminum chloride and aluminum sulfate.

Further, the mass fraction of the electrospinning raw material is 2%-20%.

Further, the non-water-soluble polymer is nylon 6, polypropylene, chitin, dextran, fibrin, silk protein, polyurethane, polyethylene terephthalate, polyvinylidene fluoride, Polystyrene, cellulose acetate, cellulose, chitosan, ethylene-vinyl alcohol copolymer, polymethyl methacrylate, polyisobutylene, polycarbonate, polyacrylonitrile, polycaprolactone, polyvinyl acetate, One or a mixture of two or more of epoxy resin, polysiloxane, hyaluronic acid, and chondroitin sulfate;

Described solvent is ether, dimethyl sulfoxide, benzene, chlorobenzene, acetonitrile, vinyl glycol, toluene, methylcyclohexane, N,N-dimethylformamide, ethanol, formic acid, xylene , cyclohexane, 2-methoxyethanol, 1,1,2-trichloroethylene, 1,2-dimethoxyethane, butyl acetate, isooctane, isopropyl ether, methyl isopropanone, Tributylmethyl ether, ethyl acetate, N-methylpyrrolidone, pentane, acetic acid, acetone, tetrahydrofuran, N,N-dimethylacetamide, 2-methyl-1-propanol, propyl acetate, 1,1 -diethoxypropane, 1,1-dimethoxymethane, 2,2-dimethoxypropane, isopropyl acetate, methyl ethyl ketone, cumene, dichloromethane, methanol, carbon tetrachloride, 1,2-dichloroethane, trichloroethane, 2-ethoxyethanol, sulfolane, pyrimidine, formamide, n-hexane, trichloroacetic acid, pyridine trifluoroacetic acid, 1,2-dichloroethylene, benzyl Ether, 1-propanol, 2-propanol, 1-butanol, 2-butanol, pentanol, ethyl formate, isobutyl acetate, methyl acetate, 3-methyl-1-butanol, methyl One or a mixture of two or more of isobutyl ketone, methyl tetrahydrofuran, and petroleum ether.

Further, the electrospinning raw material is input into the spinneret at a flow rate of 0.5-3 mL/h under the conditions of a room temperature of 25±2° C. and a humidity range of 35-65%.

Further, the fibers are deposited on the electrodes of the quartz crystal microbalance to control the distance between the electrodes and the spinneret to be 5-20 cm.

Further, the vacuum drying time is 1-3 hours, the calcination temperature is 200-800° C., and the calcination time is 2-10 hours.

In the second aspect of the present invention, a metal oxide nanofiber sensor obtained by the method is provided.

In a third aspect of the present invention, there is provided a method for detecting formaldehyde using the metal oxide nanofiber sensor, the method comprising:

The air sample is injected into the test tank by a syringe,

The metal oxide nanofiber sensor is placed in the detection tank, and the quality of formaldehyde in the air sample on the metal oxide nanofiber sensor is read;

By the mass of formaldehyde in the air sample and the following formula, the concentration of formaldehyde in the air is obtained:

One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

A metal oxide nanofiber sensor provided by the present invention, by constructing metal oxide nanofibers, while retaining the advantages of high surface area and porosity of the nanofibers itself, with the help of metal oxide semiconductor materials with low cost and high stability High, simple working principle and other advantages, to achieve real-time, fast, accurate, long-term formaldehyde detection, the minimum detection limit can reach 50ppb, can be used continuously for at least three weeks, strong stability. The metal oxide nanofiber sensor of the invention has low detection limit, high sensitivity, good selectivity, strong stability and long service life.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings that need to be used in the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

Fig. 1 is a schematic diagram of the preparation process of a metal oxide nanofiber sensor provided by the present invention;

Fig. 2. Field emission scanning electron microscope images of electrospun nanofibers before (A) calcined and after calcined in air atmosphere (B);

Fig. 3 is a flowchart of a method for preparing a metal oxide nanofiber sensor provided by the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments and examples, and the advantages and various effects of the present invention will be presented more clearly. Those skilled in the art should understand that these specific implementations and examples are used to illustrate the present invention, not to limit the present invention.

Throughout the specification, unless otherwise specified, terms used herein should be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, this specification shall take precedence.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or obtained through existing methods.

The technical solution of the embodiment of the present application is to solve the above-mentioned technical problems, and the general idea is as follows:

According to a typical implementation of the present invention, a method for preparing a metal oxide nanofiber sensor is provided, as shown in Figure 3, the method comprising:

S1. Dissolving the water-insoluble polymer in a solvent to obtain electrospinning raw materials;

In the step S1,

The non-water-soluble polymer is nylon 6, polypropylene, chitin, dextran, fibrin, silk protein, polyurethane, polyethylene terephthalate, polyvinylidene fluoride, polystyrene , cellulose acetate, cellulose, chitosan, ethylene-vinyl alcohol copolymer, polymethyl methacrylate, polyisobutylene, polycarbonate, polyacrylonitrile, polycaprolactone, polyvinyl acetate, epoxy resin , polysiloxane, hyaluronic acid, chondroitin sulfate, or a mixture of two or more;

Described solvent is ether, dimethyl sulfoxide, benzene, chlorobenzene, acetonitrile, vinyl glycol, toluene, methylcyclohexane, N,N-dimethylformamide, ethanol, formic acid, xylene , cyclohexane, 2-methoxyethanol, 1,1,2-trichloroethylene, 1,2-dimethoxyethane, butyl acetate, isooctane, isopropyl ether, methyl isopropanone, Tributylmethyl ether, ethyl acetate, N-methylpyrrolidone, pentane, acetic acid, acetone, tetrahydrofuran, N,N-dimethylacetamide, 2-methyl-1-propanol, propyl acetate, 1,1 -diethoxypropane, 1,1-dimethoxymethane, 2,2-dimethoxypropane, isopropyl acetate, methyl ethyl ketone, cumene, dichloromethane, methanol, carbon tetrachloride, 1,2-dichloroethane, trichloroethane, 2-ethoxyethanol, sulfolane, pyrimidine, formamide, n-hexane, trichloroacetic acid, pyridine trifluoroacetic acid, 1,2-dichloroethylene, benzyl Ether, 1-propanol, 2-propanol, 1-butanol, 2-butanol, pentanol, ethyl formate, isobutyl acetate, methyl acetate, 3-methyl-1-butanol, methyl One or a mixture of two or more of isobutyl ketone, methyl tetrahydrofuran, and petroleum ether.

As a preferred embodiment, the mass fraction of the electrospinning raw material is 2%-20%. If the mass fraction of the electrospinning raw material is less than 2%, there is an adverse effect that easily produces a beaded structure; if it is greater than 20%, the solution viscosity is too high to perform electrospinning;

S2. Add metal salts to the electrospinning raw materials to obtain electrospinning raw materials doped with metal ions; wherein, the metal salts are composed of various single metal salts containing different metals;

In the step S2,

The metal salt is added to the electrospinning raw material at a final concentration of 0.01-0.5 mol/L;

The reason or advantage of adding the metal salt at a final concentration of 0.01 to 0.5 mol/L is that it can form a sufficient and evenly distributed metal-doped nanofiber film to provide sufficient active sites for formaldehyde adsorption and detection; If the concentration of the metal salt is less than 0.01mol/L, the detection sensitivity of the sensor will be reduced; if it is greater than 0.5mol/L, it will be difficult to form a sensor with uniform distribution and stable performance.

Described metal salt comprises titanium tetrachloride, ferric hydroxide, ferric nitrate, copper acetate, copper carbonate, copper sulfate, zinc acetate, zinc carbonate, zinc sulfate, copper nitrate, cupric chloride, zinc chloride, zinc nitrate, phosphoric acid Zinc dihydrogen, tin methanesulfonate, tin ethanesulfonate, tin propanesulfonate, tin 2-propanesulfonate, cerium trichloride, cerium sulfate, ferric chloride, ferric sulfate, aluminum nitrate, aluminum chloride, and sulfuric acid Two or more of aluminum (and must be metal salts containing different metals). Because it has been found through experiments that only two or more metals with different electron adsorption capabilities can be added together to form a heterojunction structure, and then detect formaldehyde.

The present invention finds through a large number of experiments that in step 2, metal salts are added to the electrospinning raw materials, and then input to the spinneret and connected to a power supply for electrospinning and deposition, and finally the metal oxide nanofiber sensor is prepared. Low, high sensitivity, good selectivity, strong stability, long life.

S3. Input the electrospinning raw material mixed with metal ions to the spinneret and connect the power supply to perform electrospinning to obtain fibers;

In the step S3,

The electrospinning raw material is input into the spinneret at a flow rate of 0.5-3 mL/h under the conditions of a room temperature of 25±2° C. and a humidity range of 35-65%. This condition is conducive to better input of electrospinning raw materials to the spinneret. The power supply connected to the spinneret is 5-30kV.

S4. Depositing the fibers on the electrodes of the quartz crystal microbalance, drying in vacuum and calcining in the air atmosphere to obtain a metal oxide nanofiber sensor.

The fibers are deposited on the electrodes of the quartz crystal microbalance to control the distance between the electrodes and the spinneret to be 5-20 cm. This setting is conducive to the rapid and sufficient volatilization of the organic solvent during the spinning process, and the formation of a porous nanofiber film on the electrode;

The vacuum drying time is 1-3 hours, the calcination temperature is 200-800° C., and the calcination time is 2-10 hours.

According to another typical embodiment of the present invention, a metal oxide nanofiber sensor obtained by the method is provided.

According to another typical embodiment of the present invention, a method for detecting formaldehyde using the metal oxide nanofiber sensor is provided, the method comprising:

The air sample is injected into the test tank by a syringe,

The metal oxide nanofiber sensor is placed in the detection tank, and the quality of formaldehyde in the air sample on the metal oxide nanofiber sensor is read;

By the mass of formaldehyde in the air sample and the following formula, the concentration of formaldehyde in the air is obtained:

A metal oxide nanofiber sensor of the present application, its preparation method and application will be described in detail below in combination with examples, comparative examples and experimental data.

Example 1

At room temperature of 25°C, 1 g of cellulose acetate was stirred and dissolved in 10 g of dichloromethane and acetone mixed solvent (3:1 by weight) in a stirred tank at a rotation speed of 150 rpm to obtain a 10% mass fraction of cellulose acetate solution (0.01L); under the condition of room temperature 25°C, continue to add 0.200g copper acetate and 0.219g zinc acetate to the above-mentioned cellulose acetate solution to obtain the electrospinning raw material doped with metal ions (the final concentration of the metal salt is 0.2mol/ L); under the conditions of room temperature 25°C and humidity 35%, the spinning solution is input to the spinneret at a flow rate of 1mL/h, and the spinneret is connected to an 18kV power supply to prepare nanofibers by electrospinning; The spun fiber was deposited on the electrode of the quartz crystal microbalance, and the distance between the accepting click and the spinneret was 8 cm; the electrode of the quartz crystal microbalance deposited with the fiber was vacuum-dried at room temperature for 1 hour, and then heated at 450 °C Calcined in the air for 5 hours, the preparation process is shown in Figure 1; using a field emission scanning electron microscope to observe the nanofibers before and after calcination in the air atmosphere, it can be found that the nanofibers with a porous three-dimensional structure have been successfully prepared, see the appendix Figure 2: Inject 0.5 μL air sample into the detection tank through a syringe, place the quartz crystal microbalance electrode in the detection tank, and after the quartz crystal microbalance reading is stable, read the mass of formaldehyde in the air sample as 2.5×10 ^-3 ng, the calculated concentration of formaldehyde in the air is 50ppb. Using the quartz crystal microbalance electrode to detect the above-mentioned air samples for 15 consecutive days, the calculated formaldehyde concentration does not change, which shows that the detection method has good stability and repeatability.

Example 2

At room temperature of 25°C, 1 g of cellulose acetate was dissolved in 10 g of dichloromethane and acetone mixed solvent (weight ratio 2:1) in a stirred tank at a speed of 500 rpm to obtain a cellulose acetate solution with a mass fraction of 10%. (0.01L); under the condition of room temperature 25°C, continue to add 0.100g copper acetate and 0.219g zinc acetate to the above-mentioned cellulose acetate solution to obtain the electrospinning raw material doped with metal ions (the final concentration of the metal salt is 0.15mol/ L); under the conditions of room temperature 25° C. and humidity 35%, the spinning liquid is input to the spinneret at a flow rate of 0.8 mL/h, and the spinneret is connected to a 16kV power supply for electrospinning to prepare nanofibers; The spun fiber was deposited on the electrode of the quartz crystal microbalance, and the distance between the accepting click and the spinneret was 10 cm; the electrode of the quartz crystal microbalance deposited with the fiber was vacuum-dried at room temperature for 2 hours, and then heated at 450 Calcination in air at ℃ for 5 hours; inject 0.5 μL air sample into the detection tank through a syringe, place the quartz crystal microbalance electrode in the detection tank, and read the mass of formaldehyde in the air sample after the quartz crystal microbalance reading is stable 5×10 ^{- 3} ng, the calculated concentration of formaldehyde in the air is 100ppb.

Example 3

At room temperature of 25°C, 0.75 g of cellulose acetate was dissolved in 10 g of dichloromethane and acetone mixed solvent (weight ratio 1:1) in a stirred tank at a speed of 500 rpm to obtain cellulose acetate with a mass fraction of 7.5%. solution (0.01L); at room temperature at 25°C, continue to add 0.200g of copper acetate and 0.219g of zinc acetate to the above-mentioned cellulose acetate solution to obtain an electrospinning raw material doped with metal ions (the final concentration of the metal salt is 0.2mol /L); under the conditions of room temperature 25°C and humidity 35%, the spinning solution is input to the spinneret at a flow rate of 1.2mL/h, and the spinneret is connected to a 20kV power supply for electrospinning to prepare nanofibers ; The spun fiber is deposited on the electrode of the quartz crystal microbalance, and the distance between the accepting click and the spinneret is 10 cm; the electrode of the quartz crystal microbalance deposited with the fiber is vacuum-dried at room temperature for 2 hours, and then placed in the Calcined in air at 500°C for 3 hours; inject 0.5 μL air sample into the detection tank through a syringe, place the quartz crystal microbalance electrode in the detection tank, and read the formaldehyde content in the air sample after the quartz crystal microbalance reading is stable. The mass is 7.5×10 ^-3 ng, and the calculated concentration of formaldehyde in the air is 150ppb.

Example 4

At room temperature of 25°C, 0.75 g of cellulose acetate was dissolved in 10 g of dichloromethane and acetone mixed solvent (weight ratio 3:1) in a stirred tank at a speed of 500 rpm to obtain 7.5% cellulose acetate solution (0.01L); at room temperature at 25°C, continue to add 0.200g of copper acetate and 0.219g of zinc acetate to the above-mentioned cellulose acetate solution to obtain an electrospinning raw material doped with metal ions (the final concentration of the metal salt is 0.2mol /L); under the conditions of room temperature 25°C and humidity 35%, the spinning liquid is input to the spinneret at a flow rate of 0.6mL/h, and the spinneret is connected to an 18kV power supply for electrospinning to prepare nanofibers ; The spun fiber is deposited on the electrode of the quartz crystal microbalance, and the distance between the accepting click and the spinneret is 5 cm; the electrode of the quartz crystal microbalance deposited with the fiber is vacuum-dried at room temperature for 2 hours, and then placed in the Calcined in air at 500°C for 3 hours; inject 0.5 μL air sample into the detection tank through a syringe, place the quartz crystal microbalance electrode in the detection tank, and read the formaldehyde content in the air sample after the quartz crystal microbalance reading is stable. The mass is 2.5×10 ^-3 ng, and the calculated concentration of formaldehyde in the air is 50ppb.

Example 5

At room temperature of 25°C, 1 g of polyacrylonitrile was stirred and dissolved in 10 g of N,N-dimethylformamide in a stirred tank at a speed of 200 rpm to obtain a polyacrylonitrile solution (0.01 L) with a mass fraction of 10%; room temperature 25 Under the condition of ℃, continue to add 0.200g copper acetate and 0.219g zinc acetate to the above-mentioned cellulose acetate solution to obtain the electrospinning raw material doped with metal ions (the final concentration of metal salt is 0.2mol/L); at room temperature 25 ℃ 1. Under the condition of 35% humidity, the spinning solution is input to the spinneret at a flow rate of 1mL/h, and at the same time, the spinneret is connected to a 18kV power supply for electrospinning to prepare nanofibers; the spun fibers are deposited on quartz On the electrode of the crystal microbalance, the distance between the click and the spinneret is 8 cm; the electrode of the quartz crystal microbalance deposited with fibers is vacuum-dried at room temperature for 1 hour, and then calcined in air at 450 ° C for 5 hours; Inject 0.5 μL of air sample into the detection tank through the syringe, place the quartz crystal microbalance electrode in the detection tank, and after the reading of the quartz crystal microbalance is stable, read the mass of formaldehyde in the air sample as 20×10 ^-3 ng, calculate The concentration of formaldehyde in the air is 400ppb.

Example 6

At room temperature of 25°C, 2g of polyamide 6 was stirred and dissolved in 10g of formic acid in a stirred tank at a speed of 500rpm to obtain a polyamide 6 solution (0.01L) with a mass fraction of 20%; at room temperature of 25°C, continue to add 0.200 Add 1g copper acetate and 0.219g zinc acetate to the above-mentioned cellulose acetate solution to obtain the electrospinning raw material doped with metal ions (the final concentration of the metal salt is 0.2mol/L); , the spinning solution is input to the spinneret at a flow rate of 0.8mL/h, and at the same time, the spinneret is connected to an 18kV power supply for electrospinning to prepare nanofibers; the spun fibers are deposited on the electrodes of the quartz crystal microbalance , the distance between the click and the spinneret was 8 cm; the electrode of the quartz crystal microbalance deposited with fibers was vacuum-dried at room temperature for 1 hour, and then calcined in air at 500 °C for 5 hours; 0.5 μL air The sample is injected into the detection tank, and the quartz crystal microbalance electrode is placed in the detection tank. After the reading of the quartz crystal microbalance is stable, the mass of formaldehyde in the air sample is read as 25×10 ^-3 ng, and the concentration of formaldehyde in the air is calculated as 500ppb.

Comparative example 1

At room temperature of 25°C, 1g of cellulose acetate was stirred and dissolved in 10g of dichloromethane and acetone mixed solvent (weight ratio: 3:1) in a stirred tank at a speed of 150rpm to obtain electrospinning raw materials; at room temperature of 25°C and humidity Under the condition of 35%, the spinning solution was input to the spinneret at a flow rate of 1mL/h, and at the same time, the spinneret was connected to an 18kV power supply for electrospinning to prepare nanofibers; the spun fibers were deposited on a quartz crystal micro On the electrode of the balance, the distance between the receiving click and the spinneret is 8 cm; the electrode of the quartz crystal microbalance deposited with fibers is vacuum-dried at room temperature for 1 hour, and then calcined in the air at 450 ° C for 5 hours; through the syringe A 0.5 μL air sample was injected into the detection tank, and the quartz crystal microbalance electrode was placed in the detection tank. It was found that the reading of the quartz crystal microbalance did not change, indicating that the nanofibers without metal oxides could not respond to formaldehyde gas.

Comparative example 2

At room temperature of 25°C, 1g of cellulose acetate was stirred and dissolved in 10g of dichloromethane and acetone mixed solvent (weight ratio: 2:1) in a stirred tank at a speed of 500rpm to obtain electrospinning raw materials; at room temperature of 25°C and humidity Under the condition of 35%, the spinning solution was input to the spinneret at a flow rate of 0.8mL/h, and at the same time, the spinneret was connected to a 16kV power supply for electrospinning to prepare nanofibers; the spun fibers were deposited on the quartz crystal On the electrode of the microbalance, the distance between the click and the spinneret is 10 cm; the electrode of the quartz crystal microbalance deposited with fibers is vacuum-dried at room temperature for 2 hours, and then calcined in the air at 450 ° C for 5 hours; by The syringe injected 0.5 μL air sample into the detection tank, and the quartz crystal microbalance electrode was placed in the detection tank. It was found that the reading of the quartz crystal microbalance did not change, indicating that the nanofibers without metal oxides could not respond to formaldehyde gas. .

Comparative example 3

At room temperature of 25°C, 0.75g of cellulose acetate was stirred and dissolved in 10g of dichloromethane and acetone mixed solvent (1:1 by weight) in a stirred tank at a rotation speed of 500rpm to obtain electrospinning raw materials; at room temperature of 25°C, Under the condition of a humidity of 35%, the spinning solution was input to the spinneret at a flow rate of 1.2mL/h, and at the same time, the spinneret was connected to a 20kV power supply for electrospinning to prepare nanofibers; the spun fibers were deposited on a quartz On the electrode of the crystal microbalance, the distance between the click and the spinneret is 10 cm; the electrode of the quartz crystal microbalance deposited with fibers is vacuum-dried at room temperature for 2 hours, and then calcined in the air at 500 ° C for 3 hours; Inject 0.5 μL air sample into the detection tank through a syringe, place the quartz crystal microbalance electrode in the detection tank, and find that the reading of the quartz crystal microbalance has not changed, indicating that the nanofibers without metal oxides cannot produce formaldehyde gas. response.

Comparative example 4

At room temperature of 25°C, 1 g of cellulose acetate was dissolved in 10 g of dichloromethane and acetone mixed solvent (weight ratio 2:1) in a stirred tank at a speed of 500 rpm to obtain a cellulose acetate solution with a mass fraction of 10%. ; under the condition of room temperature 25°C, continue to add 0.100g copper acetate to the above-mentioned cellulose acetate solution to obtain the electrospinning raw material doped with metal ions; The flow rate of /h is input to the spinneret, and at the same time, the spinneret is connected to a 16kV power supply for electrospinning to prepare nanofibers; the spun fibers are deposited on the electrodes of the quartz crystal microbalance, and the click and the spinneret are accepted. The distance between them is 10cm; the electrodes of the quartz crystal microbalance deposited with fibers were vacuum-dried at room temperature for 2 hours, and then calcined in the air at 450°C for 5 hours; 0.5μL air sample was injected into the detection tank through a syringe, and it was found that The readings of the quartz crystal microbalance did not change, indicating that the nanofibers without metal oxides were unable to respond to formaldehyde gas.

Comparative example 5

At room temperature of 25°C, 1 g of cellulose acetate was dissolved in 10 g of dichloromethane and acetone mixed solvent (weight ratio 2:1) in a stirred tank at a speed of 500 rpm to obtain a cellulose acetate solution with a mass fraction of 10%. ; at room temperature of 25°C, continue to add 0.100g of zinc acetate to the above-mentioned cellulose acetate solution to obtain electrospinning raw materials doped with metal ions; The flow rate of /h is input to the spinneret, and at the same time, the spinneret is connected to a 16kV power supply for electrospinning to prepare nanofibers; the spun fibers are deposited on the electrodes of the quartz crystal microbalance, and the click and the spinneret are accepted. The distance between them is 10cm; the electrodes of the quartz crystal microbalance deposited with fibers were vacuum-dried at room temperature for 2 hours, and then calcined in the air at 450°C for 5 hours; 0.5μL air sample was injected into the detection tank through a syringe, and it was found that The readings of the quartz crystal microbalance did not change, indicating that the nanofibers without metal oxides were unable to respond to formaldehyde gas.

Experimental example 1

For the convenience of comparison, the data tabulation statistics of the above-mentioned each embodiment and each comparative example are shown in Table 1.

Table 1

It can be seen from the data in Table 1 that:

In comparative example 1-comparative example 3, since no metal salt is added, the formaldehyde concentration cannot be read;

In Comparative Example 4-Comparative Example 5, the added monometallic salt cannot form a heterojunction active site capable of adsorbing and detecting formaldehyde after being calcined, and the concentration of formaldehyde cannot be read;

In Example 1-Example 5 of the present invention, the concentration of formaldehyde can be read; and the lowest detection limit can reach 26ppb through experiments.

In addition, when the metal oxide nanofiber sensor obtained in the embodiment of the present invention is passed through an air sample containing volatile organic compounds such as ethanol, dichloromethane, acetone, and dimethylformamide, it cannot detect a change in reading or only has an extremely low value. The weak response indicates that the sensor has good selectivity for formaldehyde gas. At the same time, in the three-week continuous formaldehyde gas detection experiment, the metal oxide nanofiber sensor showed a stable reading value, indicating that the sensor has a long life and strong stability. High sensitivity (data is 1.2Hz/ppm, able to detect trace changes in formaldehyde concentration);

In summary, the metal oxide nanofiber sensor of the present invention has low detection limit, high sensitivity, good selectivity, strong stability and long life, and can realize real-time, fast, accurate and long-term formaldehyde detection.

Finally, it should also be noted that the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also Other elements not expressly listed, or inherent to the process, method, article, or apparatus are also included.

While preferred embodiments of the invention have been described, additional changes and modifications to these embodiments can be made by those skilled in the art once the basic inventive concept is appreciated. Therefore, it is intended that the appended claims be construed to cover the preferred embodiment as well as all changes and modifications which fall within the scope of the invention.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (8)

1. A method of making a metal oxide nanofiber sensor for detecting formaldehyde concentration, the method comprising:

dissolving a water-insoluble high molecular polymer in a solvent to obtain an electrospinning raw material;

adding metal salt into the electrospinning raw material to obtain the electrospinning raw material doped with metal ions; wherein the metal salt consists of a plurality of monometallic salts containing different metals; the metal salt is added into the electrospinning raw material at the concentration of 0.01-0.5 mol/L, and comprises two or more of titanium tetrachloride, ferric hydroxide, ferric nitrate, copper acetate, copper carbonate, copper sulfate, zinc acetate, zinc carbonate, zinc sulfate, copper nitrate, copper chloride, zinc nitrate, zinc dihydrogen phosphate, tin methane sulfonate, tin ethane sulfonate, tin propane sulfonate, tin 2-propane sulfonate, cerium trichloride, cerium sulfate, ferric chloride, ferric sulfate, aluminum nitrate, aluminum chloride and aluminum sulfate;

inputting the electrospinning raw material doped with the metal ions onto a spinneret and connecting the spinneret with a power supply to carry out electrostatic spinning to obtain fibers;

and depositing the fiber on an electrode of a quartz crystal microbalance, and then carrying out vacuum drying and calcining in an air atmosphere to obtain the metal oxide nanofiber sensor.

2. The method for preparing the metal oxide nanofiber sensor for detecting formaldehyde concentration as claimed in claim 1, wherein the mass fraction of the electrospinning raw material is 2-20%.

3. The method according to claim 1, wherein the water-insoluble polymer is one or more of nylon 6, polypropylene, chitin, dextran, fibrin, silk fibroin, polyurethane, polyethylene terephthalate, polyvinylidene fluoride, polystyrene, cellulose acetate, cellulose, chitosan, ethylene-vinyl alcohol copolymer, polymethyl methacrylate, polyisobutylene, polycarbonate, polyacrylonitrile, polycaprolactone, polyvinyl acetate, epoxy resin, polysiloxane, hyaluronic acid, and chondroitin sulfate;

the solvent is diethyl ether, dimethyl sulfoxide, benzene, chlorobenzene, acetonitrile, vinyl glycol, toluene, methylcyclohexane, N-dimethylformamide, ethanol, formic acid, xylene, cyclohexane, 2-methoxyethanol, 1,1,2-trichloroethylene, 1,2-dimethoxyethane, butyl acetate, isooctane, isopropyl ether, methyl isopropyl ketone, tributyl methyl ethyl ether, ethyl acetate, N-methylpyrrolidone, pentane, acetic acid, acetone, tetrahydrofuran and N, one or more of N-dimethylacetamide, 2-methyl-1-propanol, propyl acetate, 1,1-diethoxypropane, 1,1-dimethoxymethane, 2,2-dimethoxypropane, isopropyl acetate, methyl ethyl ketone, isopropyl benzene, methylene chloride, methanol, carbon tetrachloride, 1,2-dichloroethane, trichloroethane, 2-ethoxyethanol, sulfolane, pyrimidine, formamide, N-hexane, trichloroacetic acid, pyridine trifluoroacetate, 1,2-dichloroethylene, anisole, 1-propanol, 2-propanol, 1-butanol, 2-butanol, pentanol, ethyl formate, isobutyl acetate, methyl acetate, 3-methyl-1-butanol, methyl isobutyl ketone, methyltetrahydrofuran, and petroleum ether.

4. The method for preparing a metal oxide nanofiber sensor for detecting formaldehyde concentration as claimed in claim 1, wherein the electrospinning raw material is input into the spinneret and input at a flow rate of 0.5-3 mL/h at a room temperature of 25 ± 2 ℃ and a humidity range of 35-65%.

5. The method for preparing a metal oxide nanofiber sensor for detecting formaldehyde concentration as claimed in claim 1, wherein when the fiber is deposited on an electrode of a quartz crystal microbalance, the distance between the electrode and the spinneret is controlled to be 5-20 cm.

6. The method for preparing the metal oxide nanofiber sensor for detecting the concentration of formaldehyde as claimed in claim 1, wherein the time of vacuum drying is 1-3 h, the temperature of calcination is 200-800 ℃, and the time of calcination is 2-10 h.

7. A metal oxide nanofiber sensor for detecting formaldehyde concentration obtained according to the method of any one of claims 1 to 6.

8. A method for detecting formaldehyde using the metal oxide nanofiber sensor for detecting formaldehyde concentration as claimed in claim 7,

an air sample is injected into the test slot by a syringe,

placing the metal oxide nanofiber sensor of claim 7 in a detection tank, and reading the mass of formaldehyde in an air sample on the metal oxide nanofiber sensor by a quartz crystal microbalance;

and obtaining the concentration of the formaldehyde in the air according to the mass of the formaldehyde in the air sample.

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