Preparation method of multifunctional fluorescent material for detecting pollutants in water

Abstract

The invention relates to the technical field of environmental monitoring, and discloses a preparation method of a multifunctional fluorescent material for detecting pollutants in water, and the preparation method comprises the following steps: carrying out hydrothermal reaction on carbon aerogel, croconic acid, melamine and water to obtain a hydrothermal carbon solution and modified carbon aerogel; reacting the hydrothermal carbon solution, double-stranded DNA, magnesium salt and a buffer solution to obtain an active solution; dipping the modified carbon aerogel into the active liquid, and carrying out ultrasonic reaction to obtain the multifunctional fluorescent material. Under the ultraviolet condition, the fluorescent probe can be combined with copper ions and tetracycline to generate specific fluorescence characteristics, and can be used for detecting copper ions and tetracycline in water, so that the convenience and specificity of detection are improved, and the detection time is shortened. The modified carbon aerogel can effectively improve the enrichment of copper ions and tetracycline in water by the material and improve the detection sensitivity and accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of environmental monitoring, and in particular to a method for preparing a multifunctional fluorescent material for detecting pollutants in water. Background Art

[0002] When copper is present excessively in water, it can significantly inhibit the self-purification of water bodies, causing poor growth of crops, especially rice and barley, and contaminating grains, which are highly toxic to aquatic organisms. Antibiotics in the environment are difficult to be completely degraded, but instead produce a series of metabolic and degradation intermediates, which are often more toxic. At the same time, the widespread residues of tetracycline antibiotics in the environment can also induce microorganisms to gradually develop resistance to them, resulting in the enrichment of drug-resistant bacteria and the production of resistance genes.

[0003] At present, atomic absorption method and ultraviolet spectrophotometry are mostly used to detect Cu in water, and liquid phase mass spectrometry is used to detect tetracycline, but there are problems such as cumbersome operation, high cost, low sensitivity and poor specificity. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a multifunctional fluorescent material for detecting pollutants in water, so as to solve the problems of complicated operation, high cost, low sensitivity and poor specificity in the detection of copper and tetracycline in water.

[0005] To achieve the above object, the present invention provides the following technical solutions: The present invention discloses a method for preparing a multifunctional fluorescent material for detecting pollutants in water, which specifically comprises the following steps: Step S1: 10-15 parts by mass of carbon aerogel, 3-6 parts by mass of keto acid, 2-5 parts by mass of melamine, and 50-100 parts by mass of water are uniformly dispersed, transferred to a hydrothermal kettle for reaction, and centrifuged for solid-liquid separation to obtain a supernatant and a precipitate respectively; Step S2: dialyzing the supernatant to obtain a hydrothermal carbon solution; washing and drying the precipitate to obtain a modified carbon aerogel; Step S3: 1-5 parts by weight of hydrothermal carbon solution, 3-8 parts by weight of double-stranded DNA, 15-20 parts by weight of magnesium salt, and 30-60 parts by weight of buffer solution are stirred under the protection of inert gas to obtain an active solution after the reaction is completed; Step S4: immersing the modified carbon aerogel in an active liquid, and under the protection of an inert gas, ultrasonically reacting, centrifuging, washing, and freeze-drying to obtain a multifunctional fluorescent material.

[0006] Preferably, the particle size of the carbon aerosol in step S1 is 0.3-5 μm.

[0007] Preferably, the reaction temperature in step S1 is 180-220° C. and the reaction time is 12-24 h.

[0008] Preferably, the method of centrifugal solid-liquid separation in step S1 is to first centrifuge at 3000 rpm for 5 minutes at a temperature of 5°C, discard the precipitate and retain the liquid, and then centrifuge at 15000 rpm for 20 minutes to retain the supernatant and precipitate.

[0009] Preferably, the dialysis in step S2 uses a dialysis bag with a molecular equivalent of 100 to 500, and the dialysis is performed at 0 to 5° C. for 8 to 10 hours.

[0010] Preferably, the drying method in step S2 is freeze drying at -60 to -20°C for 10 to 20 hours.

[0011] Preferably, in step S3, the double-stranded DNA molecule contains adjacent 6-aminopurine and 5-methyluracil.

[0012] Preferably, the magnesium salt in step S3 is one of magnesium chloride, magnesium sulfate and magnesium nitrate.

[0013] Preferably, the buffer solution in step S3 is obtained by uniformly dispersing disodium hydrogen phosphate, sodium ascorbate, polyvinyl pyrrolidone and water in a mass ratio of 1:2:0.05:10.

[0014] Preferably, the inert gas in step S4 is one of nitrogen and argon.

[0015] Preferably, the frequency of the ultrasonic reaction in step S4 is 50-80 kHz, and the time is 10-20 min.

[0016] Beneficial effects of the present invention: 1. A multifunctional fluorescent material was constructed by in-situ synthesis of Mg@double-stranded DNA@carbon dots on carbon aerogel. Under ultraviolet conditions, it can combine with copper ions and tetracycline to produce specific fluorescence properties. It can be used to detect copper ions and tetracycline in water, improve the convenience and specificity of detection, and reduce the detection time. 2. Modified carbon aerogel can effectively improve the enrichment of copper ions and tetracycline in water, and improve detection sensitivity and accuracy; 3. The multifunctional fluorescent material of the present invention is prepared based on non-precious metals and carbon materials, has low cost, and has broad application prospects in the fields of environment and food. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Scanning electron microscope image of the multifunctional fluorescent material prepared in Example 1; Figure 2 Fluorescence spectrum of the multifunctional fluorescent material prepared in Example 1 in the presence of copper ions and tetracycline. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0019] A method for preparing a multifunctional fluorescent material for detecting pollutants in water comprises the following steps: Step S1: 10-15 parts by mass of carbon aerogel with a particle size of 0.3-5 μm, 3-6 parts by mass of keto acid, 2-5 parts by mass of melamine, and 50-100 parts by mass of water are dispersed uniformly, transferred to a hydrothermal kettle at a temperature of 180-220° C. to react for 12-24 hours, and first centrifuged at 3000 rpm for 5 minutes at a temperature of 5° C., discarded the precipitate and retained the liquid, and then centrifuged at 15000 rpm for 20 minutes to obtain a supernatant and a precipitate, respectively.

[0020] Step S2: the supernatant is dialyzed at 0-5°C for 8-10 hours using a dialysis bag with a molecular equivalent of 100-500 to obtain a hydrothermal carbon solution; the precipitate is washed and freeze-dried at -60--20°C for 10-20 hours to obtain a modified carbon aerogel.

[0021] Step S3: 1-5 parts by mass of hydrothermal carbon solution, 3-8 parts by mass of double-stranded DNA containing adjacent 6-aminopurine and 5-methyluracil, 15-20 parts by mass of magnesium salt, and 30-60 parts by mass of buffer solution are stirred under the protection of inert gas to obtain an active solution after the reaction; the magnesium salt is one of magnesium chloride, magnesium sulfate, and magnesium nitrate; the buffer solution is sodium hydrogen phosphate, sodium ascorbate, polyvinyl pyrrolidone, and water uniformly dispersed in a mass ratio of 1:2:0.05:10.

[0022] Step S4: immersing the modified carbon aerogel in the active liquid, setting the frequency to 50-80kHz for ultrasonic reaction for 10-20min under the protection of inert gas, centrifuging, washing, freeze-drying, and obtaining a multifunctional fluorescent material; the inert gas is one of nitrogen and argon.

[0023] Example 1: In this example, the multifunctional fluorescent material is obtained by the following scheme 10 parts by mass of carbon aerogel with a particle size of 0.3 μm, 3 parts by mass of keto acid, 2 parts by mass of melamine, and 50 parts by mass of water were evenly dispersed, transferred to a hydrothermal kettle at a temperature of 180°C for reaction for 12 hours, and centrifuged at 3000 rpm for 5 minutes at a temperature of 5°C, discarded the precipitate and retained the liquid, and then centrifuged at 15000 rpm for 20 minutes to obtain the supernatant and precipitate respectively. The supernatant was dialyzed for 8 hours at 0°C using a 100 molecular equivalent dialysis bag to obtain a hydrothermal carbon solution; the precipitate was washed and freeze-dried at -60°C for 10 hours to obtain a modified carbon aerogel. 1 part by mass of hydrothermal carbon solution, 3 parts by mass of double-stranded DNA containing adjacent 6-aminopurine and 5-methyluracil, 15 parts by mass of magnesium chloride, and 30 parts by mass of buffer solution (sodium hydrogen phosphate, sodium ascorbate buffer solution, polyvinyl pyrrolidone, and water are uniformly dispersed in a mass ratio of 1:2:0.05:10) are stirred under the protection of inert gas to obtain an active liquid after the reaction is completed. The modified carbon aerogel is immersed in the active liquid, and under the protection of nitrogen, the frequency is set to 50kHz for ultrasonic reaction for 10 minutes, centrifuged, washed, and freeze-dried to obtain a multifunctional fluorescent material.

[0024] like Figure 1 As shown, it is a scanning electron microscope image of the prepared multifunctional fluorescent material. It can be seen that the material is evenly distributed with a particle size of about 350nm, and there are granular magnesium@DNA@carbon dots loaded on the aerogel. Figure 2 The fluorescence spectrum of the multifunctional fluorescent material prepared in this embodiment in the presence of copper ions and tetracycline shows that the material has a strong fluorescence response to copper ions and tetracycline in water at wavelengths of 601nm and 505nm, respectively, indicating that under ultraviolet conditions, the multifunctional fluorescent material prepared by this method can combine with copper ions and tetracycline to produce specific fluorescence characteristics. When used for the detection of copper ions and tetracycline in water, it can effectively improve the convenience and specificity of detection and reduce the detection time.

[0025] Example 2: In this example, the multifunctional fluorescent material is obtained by the following scheme 12 parts by mass of carbon aerogel with a particle size of 2 μm, 5 parts by mass of keto acid, 4 parts by mass of melamine, and 80 parts by mass of water were evenly dispersed, transferred to a hydrothermal kettle at a temperature of 200°C for reaction for 18 hours, and centrifuged at 3000 rpm for 5 minutes at a temperature of 5°C, discarded the precipitate and retained the liquid, and then centrifuged at 15000 rpm for 20 minutes to obtain the supernatant and precipitate respectively. The supernatant was dialyzed for 9 hours at 3°C ​​using a 300 molecular equivalent dialysis bag to obtain a hydrothermal carbon solution; the precipitate was washed and freeze-dried at -40°C for 15 hours to obtain a modified carbon aerogel. 3 parts by mass of hydrothermal carbon solution, 6 parts by mass of double-stranded DNA containing adjacent 6-aminopurine and 5-methyluracil, 18 parts by mass of magnesium sulfate, and 50 parts by mass of buffer solution (sodium hydrogen phosphate, sodium ascorbate buffer solution, polyvinyl pyrrolidone, and water are uniformly dispersed in a mass ratio of 1:2:0.05:10) are stirred under the protection of inert gas to obtain an active liquid after the reaction. The modified carbon aerogel is immersed in the active liquid, and under the protection of argon gas, the frequency is set to 70kHz for ultrasonic reaction for 15 minutes, centrifuged, washed, and freeze-dried to obtain a multifunctional fluorescent material.

[0026] Example 3: In this example, the multifunctional fluorescent material is obtained by the following scheme 15 parts by mass of carbon aerogel with a particle size of 5 μm, 6 parts by mass of keto acid, 5 parts by mass of melamine, and 100 parts by mass of water were evenly dispersed, transferred to a hydrothermal kettle at a temperature of 220°C for reaction for 24 hours, and centrifuged at 3000 rpm for 5 minutes at a temperature of 5°C, discarded the precipitate and retained the liquid, and then centrifuged at 15000 rpm for 20 minutes to obtain the supernatant and precipitate respectively. The supernatant was dialyzed for 10 hours at 5°C using a 500 molecular equivalent dialysis bag to obtain a hydrothermal carbon solution; the precipitate was washed and freeze-dried at -20°C for 20 hours to obtain a modified carbon aerogel. 5 parts by mass of hydrothermal carbon solution, 8 parts by mass of double-stranded DNA containing adjacent 6-aminopurine and 5-methyluracil, 20 parts by mass of magnesium nitrate, and 60 parts by mass of buffer solution (sodium hydrogen phosphate, sodium ascorbate buffer solution, polyvinyl pyrrolidone, and water are uniformly dispersed in a mass ratio of 1:2:0.05:10) are stirred under the protection of inert gas to obtain an active liquid after the reaction. The modified carbon aerogel is immersed in the active liquid, and under the protection of (nitrogen, argon), the frequency is set to 50~80kHz for ultrasonic reaction for 10~20min, centrifuged, washed, and freeze-dried to obtain a multifunctional fluorescent material.

[0027] Copper ion and tetracycline solutions of different concentrations were prepared, and fluorescence tests were performed using the multifunctional fluorescent materials prepared in Examples 1-3. Standard curves were drawn with the copper ion concentration and tetracycline concentration and the corresponding fluorescence intensity, and a calculation formula was fitted. When used, the fluorescence intensity of the sample to be tested was substituted into the calculation formula to obtain the concentrations of copper ions and tetracycline therein.

[0028] Comparative Example 1 Refer to GB / T 22990-2008 and test by liquid chromatography-mass spectrometry.

[0029] Comparative Example 2 Tested by UV spectrophotometry with reference to GB / T 36084-2018.

[0030] The same concentrations of copper ions and tetracycline aqueous solution were tested in Examples 1-3 and Comparative Examples 1-2 at the same time, and the test time and error were recorded. The results are shown in Table 1.

[0031] The test results are shown in Table 1: Table 1 Test results summary

[0032] As can be seen from Table 1, the test time of Examples 1-3 is significantly less than that of Comparative Examples 1-2. At the same time, compared with Comparative Example 1, the test error of Examples 1-3 is significantly reduced, mainly because the present invention constructs a multifunctional fluorescent material by in-situ synthesizing Mg@double-stranded DNA@carbon dots on carbon aerogels. Under ultraviolet conditions, it can combine with copper ions and tetracycline to produce specific fluorescence characteristics, which can be used for the detection of copper ions and tetracycline in water, improve the convenience and specificity of detection, and reduce the detection time. In addition, the modified carbon aerogel can effectively improve the enrichment of copper ions and tetracycline in water by the material, further improving the detection sensitivity and accuracy.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a multifunctional fluorescent material for detecting pollutants in water, characterized in that: The specific steps include: Step S1: 10-15 parts by mass of carbon aerogel, 3-6 parts by mass of keto acid, 2-5 parts by mass of melamine, and 50-100 parts by mass of water are uniformly dispersed, transferred to a hydrothermal kettle for reaction, and centrifuged for solid-liquid separation to obtain a supernatant and a precipitate respectively; Step S2: dialyzing the supernatant to obtain a hydrothermal carbon solution; washing and drying the precipitate to obtain a modified carbon aerogel; Step S3: 1-5 parts by weight of hydrothermal carbon solution, 3-8 parts by weight of double-stranded DNA, 15-20 parts by weight of magnesium salt, and 30-60 parts by weight of buffer solution are stirred under the protection of inert gas to obtain an active solution after the reaction is completed; Step S4: immersing the modified carbon aerogel in an active liquid, and under the protection of an inert gas, ultrasonically reacting, centrifuging, washing, and freeze-drying to obtain a multifunctional fluorescent material.

2. The method for preparing a multifunctional fluorescent material for detecting pollutants in water according to claim 1, characterized in that: The particle size of the carbon aerosol in step S1 is 0.3-5 μm.

3. The method for preparing a multifunctional fluorescent material for detecting pollutants in water according to claim 1, characterized in that: The reaction temperature in step S1 is 180-220° C. and the reaction time is 12-24 hours.

4. The method for preparing a multifunctional fluorescent material for detecting pollutants in water according to claim 1, characterized in that: The method of centrifugal solid-liquid separation in step S1 is to centrifuge at 3000 rpm for 5 minutes at a temperature of 5°C, discard the precipitate and retain the liquid, and then centrifuge at 15000 rpm for 20 minutes to retain the supernatant and precipitate.

5. The method for preparing a multifunctional fluorescent material for detecting pollutants in water according to claim 1, characterized in that: In step S2, the dialysis is performed using a dialysis bag with a molecular weight of 100 to 500 and the dialysis is performed at 0 to 5° C. for 8 to 10 hours.

6. The method for preparing a multifunctional fluorescent material for detecting pollutants in water according to claim 1, characterized in that: The drying method in step S2 is freeze drying at -60 to -20°C for 10 to 20 hours.

7. The method for preparing a multifunctional fluorescent material for detecting pollutants in water according to claim 1, characterized in that: In step S3, the double-stranded DNA molecule chain contains adjacent 6-aminopurine and 5-methyluracil.

8. The method for preparing a multifunctional fluorescent material for detecting pollutants in water according to claim 1, characterized in that: In step S3, the magnesium salt is one of magnesium chloride, magnesium sulfate and magnesium nitrate.

9. The method for preparing a multifunctional fluorescent material for detecting pollutants in water according to claim 1, characterized in that: The buffer solution in step S3 is obtained by uniformly dispersing disodium hydrogen phosphate, sodium ascorbate, polyvinyl pyrrolidone and water in a mass ratio of 1:2:0.05:

10.

10. The method for preparing a multifunctional fluorescent material for detecting pollutants in water according to claim 1, characterized in that: In step S4, the inert gas is one of nitrogen and argon; the frequency of the ultrasonic reaction is 50-80 kHz, and the time is 10-20 min.

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