Fluorescent sensitive film for detecting mercury ions in water and preparation method thereof

Abstract

The invention discloses a fluorescent sensitive film for detecting mercury ions in water and a preparation method thereof, the sensitive film comprises a fluorescent probe and a physically crosslinked matrix, the fluorescent probe is prepared from 7-(diethylamino) coumarin-3-formaldehyde, 3-methyl-2-benzothiazolone hydrazone hydrochloride and ethanol; adding chitosan, glycerol and an acetic acid solution into the round-bottom flask, and stirring until the chitosan is completely dissolved; then adding 4-(4, 6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride, and continuously stirring at room temperature to obtain a clear and transparent solution; then adding a fluorescent probe and continuously stirring; and finally, pouring the solution into a glass dish to evaporate the solvent, thereby obtaining the fluorescent sensitive film for detecting Hg < 2 + >. The sensitive membrane has a detection effect on Hg < 2 + > in water, does not need sample preparation during detection, and has the advantages of simple detection method and high detection efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of thin film sensitive materials and heavy metal detection, and relates to a fluorescent sensitive film for detecting mercury ions in water and a preparation method thereof. Background Art

[0002] Heavy metal pollution is one of the main problems of groundwater pollution. Mercury (Hg) is one of the most toxic heavy metal elements in the environment. 2+ The main sources of pollution are industrial pollution, gold mining and smelting, coal burning pollution and acid rain pollution. 2+ It not only harms the ecosystem, but also enters the human body through ingestion of contaminated water, food or inhalation of smoke, thus causing a series of neurological diseases and causing great harm to human health. Therefore, it is urgent to develop a suitable technology to detect Hg in groundwater. 2+ Conduct sensitive on-site monitoring to avoid any impact on human health.

[0003] Traditional Hg 2+ Detection methods include atomic absorption spectroscopy (AAS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), gas chromatography, high performance liquid chromatography, and capillary electrophoresis (CE). These methods have the advantages of good specificity and mature instruments, but the complex detection process, high detection cost, and difficult pretreatment process limit their rapid and sensitive detection. Therefore, fluorescent sensors have been widely used in recent years. Traditional detection methods mostly use organic small molecule fluorescent probes, and their detection process may cause secondary pollution to water bodies, and the post-processing is complicated, which still poses great challenges in practical applications. Therefore, we urgently need a new material with outstanding performance to solve the above problems. Summary of the invention

[0004] For the above existing Hg 2+ The present invention discloses a fluorescent sensor for heavy metal ion Hg 2+ The sensitive membrane CBH / ACG can be stably present in water and detect Hg by fluorescence method. 2+ It is not interfered by other ions and has high sensitivity and low detection limit, which is expected to achieve the detection of Hg in groundwater. 2+ In-situ detection.

[0005] 1. Preparation of CBH / ACG sensitive film 1) Dissolve 7-(diethylamino)coumarin-3-carboxaldehyde and 3-methyl-2-benzothiazolone hydrazone hydrochloride in hot ethanol, react at 80-90°C for 4-6 h under the catalysis of acetic acid, filter to obtain a red crude product, and then wash it three times with ethanol to obtain the fluorescent probe CBH; The molar ratio of 7-(diethylamino)coumarin-3-carboxaldehyde to 3-methyl-2-benzothiazolone hydrazone hydrochloride is (1-3): 1. The temperature of hot ethanol is 40-50°C to assist dissolution.

[0006] 2) Chitosan and glycerol were dissolved in 1% acetic acid solution and stirred until chitosan was completely dissolved, and then 4-(4.6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride was added and prepolymerized at room temperature for 6-8 h to obtain a chitosan-based membrane solution; The mass ratio of chitosan to propylene glycol is 1:(2-4), and the mass ratio of chitosan to 4-(4.6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride is (6-8):1.

[0007] 3) Add the fluorescent probe CBH to the chitosan-based membrane solution and continue stirring for 10-12 h. Then pour the solution into a glass dish for evaporation and rinse to obtain the CBH / ACG membrane. Among them, the concentration of the fluorescent probe CBH in the chitosan-based membrane solution is 0.3~0.9 g / L.

[0008] 2. Structural characterization and performance evaluation of CBH / ACG sensitive membrane 1. Microstructure Figure 3 This is a scanning electron microscope (SEM) image of the ACG film obtained by the preparation method of the present invention. Figure 4 The following is a scanning electron microscope (SEM) image of the CBH / ACG film prepared by the preparation method of the present invention. Figure 3 and 4 By comparison, the surface of CBH / ACG film is smoother, denser and more uniform than that of ACG film, indicating that the CBH fluorescent probe is stably loaded on the ACG film, providing a reliable basis for the further functional application of chitosan film.

[0009] 2. Determination of mercury ion detection limit The CBH / ACG film was cut into a circular film sheet with a diameter of 1 cm; 20 mL of secondary water was taken into a beaker, and the film sheet was placed in the water. After soaking for 2-5 min, it was taken out, and the water on the surface of the film sheet was first absorbed with filter paper, and then 40 μL of secondary water was dripped onto the film sheet to ensure that the water content of the film sheet was consistent during the test. The film sheet on the slide was pressed with a quartz sheet, and the initial fluorescence intensity of the film sheet was detected on a fluorescence spectrophotometer; then, the film sheet was removed, the water on the surface of the film sheet was absorbed with filter paper, and 1 μL of Hg was dripped into the test solution. 2+ion solution (concentration of 100 ppm), mix evenly to obtain a mixed solution with a concentration of 5 ppb, then put the film into 20 mL of the mixed solution to be tested and soak for 2 to 5 minutes, then take it out, first use filter paper to absorb the moisture on the surface of the film, and then add 40 μL of the mixed solution to the film to ensure that the water content of the film is consistent during the test, and then use another quartz sheet to press the film tightly, and detect the change in fluorescence intensity of the film on a fluorescence spectrophotometer. The detection method of the other test solutions with concentrations of 10 ppb, 15 ppb, 20 ppb, 25 ppb, 30 ppb, 35 ppb, 40 ppb, 45 ppb, 50 ppb, 60 ppb, 70 ppb, and 80 ppb is the same as the detection method of the test solution with a concentration of 5 ppb, and finally obtain Figure 5 The corresponding concentration-fluorescence intensity standard working curve is shown.

[0010] from Figure 5 The corresponding concentration-fluorescence intensity standard working curve shown in the figure shows that as the Hg 2+ As the ion concentration increases, the fluorescence intensity of the sensitive membrane also gradually increases. 2+ When the ion concentration is 5ppb, it contains Hg 2+ The fluorescence intensity of the ion-sensitive membrane is significantly higher than that of the blank membrane, and Figure 6 The detection limit was calculated to be 3.6 ppb.

[0011] 3. Mercury ion selectivity and anti-interference First prepare the following solutions: 20 mL 80 ppb Hg 2+ Solution; 20 mL each of other metal ion solutions with a concentration of 1000 ppb, including KCl solution, MgCl2 solution, CrCl3·3H2O solution, ZnCl2 solution, FeCl3 solution, CuCl2·2H2O solution, CaCl2 solution, HgCl2 solution, PbCl2 solution, K2Cr2O7 solution, MnCl2·4H2O solution, NiCl2·6H2O solution, NaBr solution, NaI solution, NaCl solution, Na2SO4 solution, Na2S2O3 solution, Na2S·9H2O solution, NaNO3 solution, NaSCN solution and NaNO2 solution.

[0012] Subsequently, the above solid fluorescence detection method was used to detect the initial fluorescence intensity of each film after soaking in secondary water for 2 to 5 minutes, and then the fluorescence intensity of the sensitive membrane in the presence of different metal ions was tested, and finally the Hg 2+ The fluorescence intensity of the sensitive film when it coexists with other metal ions. Figure 7 The selectivity and anti-interference performance of the sensitive membrane of the present invention to cations are shown in the figure and Figure 8 The selectivity and anti-interference of the sensitive membrane of the present invention to anions are shown in the figure. By comparing the changes in fluorescence intensity, it is found that only the mercury ion solution causes a significant change in the fluorescence intensity of the film, indicating that the sensitive membrane of the present invention has excellent selectivity and anti-interference to mercury ions.

[0013] The preparation method of the present invention has the following advantages: 1) The CBH / ACG film can exist stably in water, can detect mercury ions in water, and has good selectivity and anti-interference. No sample preparation is required during detection, which can improve detection efficiency.

[0014] 2) The synthesis method of CBH / ACG film is simple and the materials used in the film are low-cost and can be prepared in batches, which is expected to achieve the purpose of Hg removal in groundwater. 2+ In-situ detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a physical picture of the CBH / ACG film prepared by the preparation method of the present invention.

[0016] Figure 2 This is a physical picture of the ACG film obtained by the preparation method of the present invention.

[0017] Figure 3 This is a scanning electron microscope (SEM) image of the ACG film prepared by the preparation method of the present invention.

[0018] Figure 4 It is a scanning electron microscope (SEM) picture of the CBH / ACG film prepared by the preparation method of the present invention.

[0019] Figure 5 It is a linear titration diagram of the CBH / ACG film prepared by the preparation method of the present invention.

[0020] Figure 6 It is the linear fitting curve of the CBH / ACG film prepared by the preparation method of the present invention.

[0021] Figure 7 The diagram is a graph showing the selectivity and anti-interference properties of the CBH / ACG film prepared by the preparation method of the present invention to cations.

[0022] Figure 8 The diagram is a graph showing the selectivity and anti-interference properties of the CBH / ACG film prepared by the preparation method of the present invention to anions. DETAILED DESCRIPTION

[0023] The preparation of the CBH / ACG sensitive film of the present invention is further explained below in conjunction with specific examples. Example

[0024] Preparation of CBH / ACG sensitive film 1) Dissolve 7-(diethylamino)coumarin-3-carboxaldehyde (245 mg, 1 mmol) and 3-methyl-2-benzothiazolone hydrazone hydrochloride (233 mg, 1 mmol) in hot ethanol (20 mL), and add five drops of acetic acid solution to the solution. The solution was reacted at 85°C for 4 h, then filtered to obtain a red crude product, which was then washed three times with ethanol to obtain the fluorescent probe CBH. Yield: 211 mg; Yield: 52.2%.

[0025] 2) Add chitosan (300 mg), glycerol (900 mg) and 1% acetic acid solution (30 mL) into a single-necked flask and stir until the chitosan is completely dissolved. Then, add 4-(4.6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride (45 mg) and prepolymerize at room temperature for 6 h to obtain a chitosan-based membrane solution. Finally, add the fluorescent probe CBH (10 mg) to the chitosan-based membrane solution (30 ml) and continue stirring for 12 hours. Pour the solution into a glass dish and evaporate to obtain a crude membrane, which is rinsed with water three times to obtain the following: Figure 1 CBH / ACG films shown.

[0026] ACG membrane preparation 1) Add chitosan (300 mg), glycerol (900 mg) and 1% acetic acid solution (30 mL) into a single-necked flask and stir until chitosan is completely dissolved. Then, add 4-(4.6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride (45 mg) and prepolymerize at room temperature for 6 h to obtain a chitosan-based membrane solution. Pour the solution into a glass dish and evaporate to obtain a crude membrane, which is then rinsed with water three times to obtain a Figure 2 ACG film shown.

Claims

1. A method for preparing a fluorescent sensitive membrane for detecting mercury ions in water, characterized in that: The following steps are involved: 1) Dissolve 7-(diethylamino)coumarin-3-carboxaldehyde and 3-methyl-2-benzothiazolone hydrazone hydrochloride in hot ethanol, react at 80-90°C for 4-6 h under the catalysis of acetic acid, filter to obtain a red crude product, and then wash it three times with ethanol to obtain the fluorescent probe CBH; 2) Chitosan and glycerol were dissolved in 1% acetic acid solution and stirred until chitosan was completely dissolved, and then 4-(4.6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride was added and prepolymerized at room temperature for 6-8 h to obtain a chitosan-based membrane solution; 3) Add the fluorescent probe CBH to the chitosan-based membrane solution and continue stirring for 10-12 h. Then pour the solution into a glass dish for evaporation and rinse to obtain the CBH / ACG membrane.

2. A method for preparing a fluorescent sensitive membrane for detecting mercury ions in water as claimed in claim 1, characterized in that: In step 1), the molar ratio of 7-(diethylamino)coumarin-3-carboxaldehyde and 3-methyl-2-benzothiazolone hydrazone hydrochloride is (1-3):

1.

3. A method for preparing a fluorescent sensitive membrane for detecting mercury ions in water as claimed in claim 1, characterized in that: In step 1), the temperature of the hot ethanol is 40-50°C.

4. A method for preparing a fluorescent sensitive membrane for detecting mercury ions in water as claimed in claim 1, characterized in that: In step 2), the mass ratio of chitosan to propylene glycol is 1:(2-4), and the mass ratio of chitosan to 4-(4.6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride is (6-8):

1.

5. The method for preparing a fluorescent sensitive membrane for detecting mercury ions in water according to claim 1, characterized in that: In step 3), the concentration of the fluorescent probe CBH in the chitosan-based membrane solution is 0.3-0.9 g / L.

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