A carbon dot with rapid and sensitive response to phosgene and its application in phosgene monitoring and removal

Abstract

The present invention discloses a carbon dot that can respond to phosgene quickly and sensitively, and through the loading effect of carbon dot on related carriers, a portable material that can be visually monitored in real time and can effectively remove phosgene is constructed. Carbon dots are prepared with 4-(4-aminophenyl)thiomorpholine-1,1-dioxide as a precursor, and the carbon dots not only have a sensitive, rapid and specific response to phosgene, but also have excellent photostability and thermal stability, which are very suitable for long-term real-time monitoring. By loading the prepared carbon dots on a carrier with large holes and high specific surface area, a fluorescent carbon dot functional material with real-time sensitive monitoring and effective removal of gaseous phosgene is designed. The functional material can achieve a visual response to 2ppm phosgene within 1min, and the functional material also has the performance of adsorbing and reacting phosgene. The functional material is made into physical objects such as masks and hats, and is expected to achieve real-time monitoring and effective removal of phosgene, providing a more excellent choice for the safety monitoring of phosgene.

Description

Technical Field

[0001] The present invention belongs to the technical field of phosgene monitoring and removal, and in particular relates to a carbon dot that can quickly and sensitively respond to phosgene and its phosgene monitoring and removal application. Technical Background

[0002] Phosgene, also known as carbonyl chloride and chloroformyl chloride, is active in nature and is an essential intermediate in the synthesis of plastics, pesticides, rubber, dyes, and synthetic fibers. The activity and specificity of phosgene make it a chemical warfare agent. It was widely used in world wars and caused tens of thousands of deaths. Studies have shown that continuous exposure to 20ppm phosgene for 2 minutes can cause lung damage; when the phosgene concentration reaches 90ppm, it can cause death after 30 minutes. Constructing a real-time and sensitive method for monitoring phosgene is of great significance for the safe use of phosgene and protecting people's safety.

[0003] The fluorescent probe method has the characteristics of rapidity, sensitivity, and visualization. In recent years, phosgene detection based on fluorescent probes has received widespread attention. However, current probes are limited to the detection of phosgene. Phosgene is an invisible gas that is almost colorless and odorless. Before leak detection and discovery, the harm caused by the spread of phosgene is inevitable. If the monitoring device we designed can also remove phosgene during the detection process, then the damage caused by phosgene in the above-mentioned actual operation process can be greatly reduced. Summary of the invention

[0004] In view of the technical problem that the existing technology cannot realize the real-time monitoring and effective removal of phosgene, the present invention designs a highly stable and highly sensitive fluorescent carbon dot that can detect phosgene in real time. By loading the carbon dot on a permeable carrier with large pores and high specific surface area, a functional material that can quickly monitor and remove phosgene with high sensitivity in real time is prepared. The functional material can produce an obvious visual signal change response to 2ppm of phosgene within 1 minute. At the same time, the material also has the performance of real-time reaction of adsorbing phosgene, which can realize the adsorption and removal of phosgene, and the removal rate can reach 92.25%. The carbon dots and functional materials designed by this patent provide a more excellent choice for the real-time monitoring and effective removal of phosgene.

[0005] The technical solution for realizing the present invention is:

[0006] A carbon dot that responds quickly and sensitively to phosgene is prepared by a solvothermal method using 4-(4-aminophenyl)thiomorpholine-1,1-dioxide as a precursor and anhydrous ethanol as a solvent.

[0007] The initial concentration of the 4-(4-aminophenyl)thiomorpholine-1,1-dioxide in anhydrous ethanol was 18.4 mM.

[0008] Application of the carbon dots in phosgene monitoring.

[0009] The carbon dots are used for monitoring phosgene in a solution. The carbon dots can realize colorimetric and ratiometric dual responses to phosgene and respond quickly to phosgene in a solution, with a response time of less than 1 second.

[0010] The carbon dots are used for monitoring gaseous phosgene, and the steps are:

[0011] (1) dissolving the carbon dots in dimethyl sulfoxide to prepare a carbon dot stock solution with a concentration of 10 mg / mL, and adding the carbon dot stock solution into acetonitrile to prepare a 200 μg / mL carbon dot acetonitrile solution;

[0012] (2) Cut the polypropylene meltblown fabric into strips of 0.5×0.5 cm and soak them in a 200 μg / mL carbon dot acetonitrile solution. After 5 min, take them out and let them dry naturally. Repeat the soaking-drying process 3 times to obtain a carbon dot / polypropylene meltblown fabric test strip.

[0013] (3) The prepared carbon dot / polypropylene meltblown fabric test strips were placed in a gaseous phosgene environment with different concentrations, sealed for 1 min and then taken out, and the fluorescence color change of the test strips was observed under a 365 nm ultraviolet lamp.

[0014] The carbon dot / polypropylene meltblown cloth test strip can actually detect gaseous phosgene at a concentration as low as 2 ppm within 1 minute.

[0015] The carbon dots are used in phosgene removal by loading the carbon dots on a permeable carrier with large pores and a high specific surface area, or by mixing the carbon dots with a gel matrix to prepare an aerogel with a good pore structure and a high specific surface area, and then using the carrier or aerogel loaded with the carbon dots to remove phosgene in the environment.

[0016] The carrier is any one of polypropylene meltblown cloth, fiber, cotton sheet and sponge.

[0017] The carrier is a polypropylene meltblown cloth, and the polypropylene meltblown cloth loaded with the carbon dots can be used on the surface of masks, clothes or other objects to prevent human inhalation and contact or to achieve the purpose of real-time removal of trace phosgene in the air.

[0018] The application of the carbon dots in phosgene removal specifically comprises the following steps:

[0019] (a) dissolving the carbon dots in dimethyl sulfoxide to prepare a carbon dot stock solution with a concentration of 10 mg / mL, and adding the carbon dot stock solution into acetonitrile to prepare a 200 μg / mL carbon dot acetonitrile solution;

[0020] (b) preparing a standard test strip, soaking a polypropylene meltblown cloth in a 200 μg / mL carbon dot acetonitrile solution, taking it out and drying it after 5 minutes, repeating this process 3 times, and cutting the soaked polypropylene meltblown cloth into a 1×0.6 cm test strip to obtain a standard test strip;

[0021] (c) Establishing a standard, placing a standard test strip in the lid on the top of the test container, preparing phosgene at the bottom of the test container, and sealing for 5 minutes, observing the fluorescence color changes of the standard test strip under different concentrations of phosgene under a 365nm ultraviolet lamp and performing RGB fitting on the standard test strip, using the standard test strip under gradient concentrations of phosgene as the standard reference, and using the linear relationship of RGB fitting as the standard working curve;

[0022] (d) loading the carbon dots onto a permeable carrier having large pores and a high specific surface area, cutting the carrier into a structure whose size and shape are compatible with the test container as a filter layer, preparing phosgene at the bottom of the test container to simulate phosgene leakage, placing the filter layer in the middle of the test container to filter the phosgene generated at the bottom, and placing a standard test strip in the lid on the top of the test container to detect the phosgene content in the filtered gas;

[0023] (e) comparing the standard test strip after detection in step (d) with the standard reference substance in step (c), and calculating the phosgene content in the filtered gas according to the standard working curve.

[0024] The removal rate of phosgene can reach 92.25%.

[0025] The beneficial effects of the present invention are as follows: the fluorescent carbon dots prepared by the present invention using 4-(4-aminophenyl)thiomorpholine-1,1-dioxide as a precursor can rapidly produce a specific response to phosgene, and the fluorescent carbon dots are loaded on a permeable carrier with large pores and a high specific surface area to achieve rapid portable detection, real-time monitoring and effective removal of gaseous phosgene, specifically: 1. The carbon dots of the present invention are simple to prepare, have excellent light stability and thermal stability, are sensitive to phosgene, and have high specificity. 2. The carbon dots of the present invention respond very quickly to phosgene in the solution, with a reaction time of less than 1s. 3. The carbon dots of the present invention can achieve colorimetric and ratiometric dual responses to phosgene, especially the fluorescence color changes from blue to yellow-green, with a sharp contrast, which is conducive to observing color changes at low concentrations of phosgene; 4. The polypropylene melt-blown cloth loaded with fluorescent carbon dots is made into uniform test strips, which achieves ultra-sensitive detection of gaseous phosgene, and the actual detectable concentration is as low as 2ppm when the detection time is 1min. 5. The polypropylene meltblown cloth loaded with carbon dots is used as the absorbing material for phosgene to achieve effective filtration and removal of phosgene, and the phosgene removal rate can reach 92.25%. In practical applications, the prepared polypropylene meltblown cloth loaded with fluorescent carbon dots can be used on the surface of masks, clothes or other objects to prevent human inhalation and contact or to achieve the purpose of real-time trace phosgene removal in the air. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 FT-IR spectrum of the fluorescent carbon dots prepared in Example 1;

[0028] Figure 2 (a) The fluorescence intensity change diagram of 20 μg / mL carbon dot acetonitrile solution at 415 nm after continuous irradiation at 345 nm excitation wavelength for 30 min; (b) The fluorescence intensity change diagram of 20 μg / mL carbon dot dimethyl sulfoxide solution at 415 nm after heating at 50 °C for 30 min;

[0029] Figure 3 When the carbon dot concentration is 20 μg / mL, the UV-visible absorption spectra of each solution before and after adding different amounts of triphosgene solution (a), the fluorescence emission spectra (b), and the linear relationship between the logarithm of the ratio of the fluorescence intensity at 530 nm and 415 nm and the triphosgene concentration (c) are shown. Figure 3The illustrations in (a) and (b) are pictures of the color change of the solution before and after the addition of triphosgene under sunlight and 365nm UV light, respectively;

[0030] Figure 4 When the concentration of carbon dots is 20 μg / mL, the fluorescence emission spectra of each solution after adding triphosgene and different interfering substances (a) and the ratio of fluorescence intensity at 530 nm to 415 nm (b) are shown. Figure 4 The inset in (b) is the color change diagram of the solution under 365nm ultraviolet light. The numbers 1-9 in the inset are carbon dots (blank group), triphosgene (Trephosgene), diethyl chlorophosphate (DCP), diethyl cyanophosphate (DECP), acetyl chloride (CH3COCl), thionyl chloride (SOCl2), formaldehyde (HCHO), p-toluenesulfonyl chloride (p-TsCl) and oxalyl chloride ((COCl)2);

[0031] Figure 5 The time-scan fluorescence spectra of 20 μg / mL carbon dots and 20 μM triphosgene in acetonitrile solution (a) and the fluorescence color change process under 365 nm ultraviolet light after adding triphosgene solution (b);

[0032] Figure 6 The fluorescence color change picture of the carbon dot / polypropylene melt-blown fabric test strip exposed to 0-10ppm gaseous phosgene environment for 1 minute under 365nm ultraviolet light (a) and the fluorescence color change picture of the carbon dot / polypropylene melt-blown fabric test strip exposed to 20ppm gaseous phosgene and other interferents for 1 minute (b);

[0033] Figure 7 The fluorescence change image (a), RGB bar graph (b) and linear relationship graph between the G channel value and phosgene concentration (c) of the standard test strip exposed to 0-25ppm gaseous phosgene environment for 5 minutes under 365nm ultraviolet light;

[0034] Figure 8 Figure 2 shows the fluorescence color change of the standard test strip under sunlight and 365nm UV light after 20ppm phosgene was filtered out through blank polypropylene meltblown cloth and polypropylene meltblown cloth loaded with fluorescent carbon dots (a) and the remaining amount of 20ppm phosgene after filtration and the removal rate results (b and c). DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] 1) Preparation of carbon dots

[0038] Accurately weigh 50.0 mg of 4-(4-aminophenyl)thiomorpholine-1,1-dioxide, add 12 mL of anhydrous ethanol and sonicate for 10 min until completely dissolved. Then transfer it into a high-pressure reactor and heat it to 180 ° C for 12 h. After the reaction is completed, cool it naturally to room temperature. The crude product is eluted and purified by a mixture of dichloromethane and methanol (v:v = 180:1), and then rotary evaporated to obtain fluorescent carbon dots (CDs).

[0039] 2) Stability study

[0040] The fluorescent carbon dots were completely dissolved in dimethyl sulfoxide to prepare a carbon dot stock solution with a concentration of 10 mg / mL (Note: the carbon dot stock solution used in all subsequent examples refers to this solution).

[0041] The carbon dot stock solution was added to the acetonitrile solution to prepare a 20 μg / mL carbon dot acetonitrile solution, which was continuously irradiated for 30 min at the optimal excitation wavelength (345 nm) to observe the change in fluorescence intensity at 415 nm.

[0042] The carbon dot stock solution was diluted in dimethyl sulfoxide to prepare a carbon dot dimethyl sulfoxide solution with a concentration of 20 μg / mL. The 20 μg / mL carbon dot dimethyl sulfoxide solution was heated at 50°C for 30 min. Samples were taken at 0 min, 5 min, 10 min, 15 min, 20 min, 25 min and 30 min for fluorescence spectrum measurement, and the change in fluorescence intensity of the solution at 415 nm was observed. The excitation wavelength was 365 nm.

[0043] Figure 1 This is the FI-IR spectrum of the fluorescent carbon dots synthesized in Example 1. -1 OH, NH stretching vibration, 2925, 2854 cm -1 Corresponding to the stretching vibration of saturated CH, at 1670, 1622 cm -1 The two characteristic peaks are the stretching vibration of C=O on the secondary amide, 1599, 1515 cm -1 The characteristic peaks of the benzene ring are located at 1305, 1274 cm -1 The two peaks at 1211 cm -1 is the stretching vibration of CS.

[0044] Depend on Figure 2(a) It can be seen that the fluorescence intensity of the carbon dots does not change significantly after continuous irradiation for 30 min at their optimal excitation wavelength (345 nm), indicating that the fluorescent carbon dots of the present invention have excellent photostability. Figure 2 (b) shows that the fluorescence intensity of the carbon dots does not change significantly when they are continuously heated at 50°C for 30 min, which proves that the carbon dots of the present invention have good thermal stability.

[0045] Example 2

[0046] Detection of Phosgene by Fluorescent Carbon Dots in Acetonitrile Solution

[0047] In the subsequent examples, all experiments used acetonitrile as the test solvent unless otherwise specified, and considering the severe toxicity of phosgene, the phosgene in the experiment was replaced by triphosgene, which is less toxic, in situ. Since the fluorescent carbon dots themselves have a large number of nitrogen-containing groups such as amino groups and pyridine, they have the ability to directly catalyze triphosgene into phosgene in situ. Therefore, when the fluorescent carbon dots detect phosgene in the solution, there is no need to add triethylamine, and the experiment can be carried out directly with triphosgene.

[0048] 1) Spectral response experiment of fluorescent carbon dots to phosgene in solution

[0049] 4 μL of carbon dot stock solution was transferred into acetonitrile, and different volumes of triphosgene solution (2 mM, solvent was acetonitrile) were added respectively. The total volume was fixed at 2 ml, the final concentration of fluorescent carbon dots was 20 μg / mL, and the final concentrations of triphosgene were 0 μM, 2 μM, 4 μM, 6 μM, 8 μM, 10 μM, 12 μM, 14 μM, 16 μM, 18 μM, and 20 μM, respectively. Finally, the solution was mixed and allowed to stand for 2 min. UV-visible absorption spectrum and fluorescence emission spectrum were detected for each solution, and the color change of each solution was observed under sunlight and 365 nm UV lamp, respectively.

[0050] Depend on Figure 3 (a) It can be seen that the changes in the UV-visible absorption spectrum of the solution are as follows: the absorption band of the fluorescent carbon dots is at 345nm. As the concentration of triphosgene gradually increases, the absorption peak of the fluorescent carbon dots themselves continues to weaken. At the same time, a new product absorption peak appears at 395nm, and the isosbestic point appears at 365nm.

[0051] from Figure 3 (b) It can be seen that the changes in the fluorescence emission spectrum of the solution are as follows: the fluorescent carbon dots have an emission peak at 415nm. When triphosgene is added, the fluorescence intensity at 415nm gradually decreases, and then a new emission peak appears at 530nm. Figure 4(c) shows that the logarithm of the ratio of the fluorescence intensity of the solution at 530 nm to that at 415 nm has a good linear relationship with the concentration of triphosgene (0-16 μM), and the detection limit can be calculated to be: 0.5336 nM (3σ / k), and the linear equation is y=0.1819x-1.8206, where y represents the logarithm of the ratio of the fluorescence intensity of the solution at 530 nm to that at 415 nm lg (F 530 / F 415 ), x represents the concentration of triphosgene, R 2 =0.9845.

[0052] Figure 3 The illustration shows that after adding phosgene, the color of the detection solution changes from colorless to light yellow under sunlight, and the fluorescence changes from blue to yellow-green under 365nm ultraviolet light.

[0053] The above phenomena all indicate that the fluorescent carbon dots prepared in the present invention can respond to phosgene in the solution and can detect signals through UV-visible absorption spectrum / fluorescence emission spectrum. Most importantly, the visual detection of phosgene can be achieved by observing its obvious color change.

[0054] 2) Experiment on the selective response of fluorescent carbon dots to phosgene in solution

[0055] A series of interfering substance solutions were prepared, all with a concentration of 1 mM, including diethyl chlorophosphate (DCP), diethyl cyanophosphate (DECP), acetyl chloride (CH3COCl), thionyl chloride (SOCl2), formaldehyde (HCHO), p-toluenesulfonyl chloride (p-TsCl) and oxalyl chloride ((COCl)2).

[0056] Take several cuvettes, add acetonitrile and 4 μL carbon dot stock solution into each cuvette, take one group as the blank group, take another group and add 20 μL triphosgene solution (2 mM), and add 40 μL of different interfering substance solutions to the remaining groups. The total volume in each cuvette is 2 mL, the final concentration of fluorescent carbon dots is 20 μg / mL, and the final concentration of triphosgene and each interfering substance is 20 μM. After reacting for 2 minutes, measure the fluorescence emission spectrum of each solution at an excitation wavelength of 365 nm, and observe the fluorescence color change of the solution under a 365 nm ultraviolet lamp.

[0057] like Figure 4As shown in the figure, there is no obvious change in the fluorescence emission spectra of the blank carbon dot solution and the solution with other interferences. Only after the addition of triphosgene, the fluorescence intensity of the solution at 415nm decreases, and a new product emission peak appears at 530nm. In addition, the change in the fluorescence color of the illustrated solution under a 365nm ultraviolet lamp can also clearly show that only the solution with the addition of triphosgene will change its fluorescence from blue to yellow-green. These all indicate that the fluorescent carbon dots of the present invention have good selectivity and can achieve specific detection of phosgene.

[0058] 3) Experiment on the time response of carbon dots to phosgene

[0059] In order to reduce the time impact caused by the slow diffusion rate of triphosgene added in a small volume and high concentration, this experiment used a small concentration of triphosgene solution to prepare a 100 μM triphosgene solution. Specifically, 50 μL of triphosgene solution (2 mM) was added to 950 μL of acetonitrile and mixed to obtain a 100 μM triphosgene solution.

[0060] Take a cuvette, add 1596 μL of acetonitrile to it, then add 4 μL of carbon dot stock solution, mix well, and monitor the change of fluorescence intensity at 530 nm in real time under 365 nm excitation wavelength. Then quickly add 400 μL of 100 μM triphosgene solution to the cuvette to make the final concentration of 20 μM, and continue to monitor the change of fluorescence intensity of the solution at 530 nm over time and the change of fluorescence color of the solution under 365 nm ultraviolet light.

[0061] Depend on Figure 5 (a) It can be seen that the fluorescent carbon dots respond quickly to phosgene. The fluorescence intensity at 530nm reaches the maximum value immediately after the addition of triphosgene and tends to be stable. The response time is less than 1s. Figure 5 The fluorescence change picture (b) also shows that the solution changes color immediately when triphosgene is added, and the reaction is complete within 1 second. It can be seen that the fluorescent carbon dots of the present invention respond quickly to phosgene and can be used for on-site real-time detection of phosgene.

[0062] Example 3

[0063] Fluorescent carbon dots for rapid detection of gaseous phosgene

[0064] (I) Detection of gaseous phosgene by carbon dot / polypropylene meltblown fabric test strips

[0065] (1) Pipette 40 μL of the carbon dot stock solution and add it to 1960 μL of acetonitrile. Mix well to prepare a 200 μg / mL carbon dot acetonitrile solution.

[0066] (2) The polypropylene meltblown fabric was cut into strips of 0.5×0.5 cm, immersed in the above-mentioned 200 μg / mL carbon dot acetonitrile solution, taken out after 5 minutes and naturally dried, and the immersion-drying process was repeated 3 times to obtain a carbon dot / polypropylene meltblown fabric test strip.

[0067] (3) A centrifuge tube with a capacity of 50 mL was used as a reaction container, and 6 centrifuge tubes were numbered 1-6. Acetonitrile and triethylamine solution (1 mM) were added to centrifuge tubes 1-6, and then triphosgene solution (1 mM) of the same concentration and different volumes were added to centrifuge tubes 1-6, respectively. Triethylamine was used as a catalyst, and the amount of triethylamine solution (1 mM) added was fixed at 1 μL. Finally, the gaseous phosgene concentrations in centrifuge tubes 1-6 were: 0 ppm, 2 ppm, 4 ppm, 6 ppm, 8 ppm, and 10 ppm, respectively. The specific experimental steps were: affixing the carbon dot / polypropylene melt-blown cloth test strip to the centrifuge tube, and then gradually adding acetonitrile, triethylamine solution and triphosgene solution to the centrifuge tube. After the addition was completed, the tube cap was immediately covered and sealed for 1 min. After the completion, the carbon dot / polypropylene melt-blown cloth test strip in the centrifuge tube was taken out, and the color change under different concentrations of phosgene was observed under a 365 nm ultraviolet lamp;

[0068] The solutions in centrifuge tubes 1-6 are as follows:

[0069] No. 1: 20 μL acetonitrile as reference;

[0070] No. 2: 1.4 μL triphosgene solution + 1 μL triethylamine solution + 17.6 μL acetonitrile;

[0071] No. 3: 2.8 μL triphosgene solution + 1 μL triethylamine solution + 16.2 μL acetonitrile;

[0072] No. 4: 4.2 μL triphosgene solution + 1 μL triethylamine solution + 14.8 μL acetonitrile;

[0073] No. 5: 5.6 μL triphosgene solution + 1 μL triethylamine solution + 13.4 μL acetonitrile;

[0074] No. 6: 6.8 μL triphosgene solution + 1 μL triethylamine solution + 12.2 μL acetonitrile.

[0075] from Figure 6 (a) It can be seen that: as the phosgene concentration increases from 0 ppm to 10 ppm, the fluorescence of the carbon dot / polypropylene meltblown cloth test strip gradually changes from blue to yellow-green under a 365 nm UV lamp. Most importantly, when the fixed detection time is 1 min, phosgene as low as 2 ppm can cause a change in fluorescence color, indicating that the fluorescent carbon dots are sensitive to phosgene and can be loaded on polypropylene meltblown cloth to achieve portable, rapid and sensitive detection of gaseous phosgene.

[0076] (II) Experiment on the selectivity of carbon dot / polypropylene meltblown fabric test strips for gaseous phosgene

[0077] A centrifuge tube with a capacity of 50 mL was used as the reaction container. The concentration of the interfering substance solution was 1 mM. The interfering substances included: diethyl chlorophosphate (DCP), diethyl cyanophosphate (DECP), acetyl chloride (CH3COCl), thionyl chloride (SOCl2), formaldehyde (HCHO), p-toluenesulfonyl chloride (p-TsCl) and oxalyl chloride ((COCl)2), and the total solution volume was fixed at 20 μL. Nine 50 mL centrifuge tubes were taken, numbered 7-15, and 13.6 μL of different interfering substance solutions were added to centrifuge tubes 7-13 respectively. liquid and 6.4μL acetonitrile, 5.4μL acetonitrile, 1μL triethylamine solution (1mM) and 13.6μL triphosgene solution (1mM) were added to centrifuge tube No. 14 in sequence, and 20μL acetonitrile was added to centrifuge tube No. 15 as a blank reference; the carbon dot / polypropylene meltblown cloth test strip was attached to the centrifuge tube, and each solution was added to the corresponding centrifuge tube. After the addition was completed, the tube cap was immediately covered and sealed for 1min. After the end, the carbon dot / polypropylene meltblown cloth test strip in the centrifuge tube was taken out, and the color change under different concentrations of phosgene was observed under 365nm ultraviolet light.

[0078] Figure 6 (b) shows that only the fluorescence of the carbon dot / polypropylene melt-blown cloth test strip under 365nm ultraviolet light changes from blue to yellow-green after the addition of phosgene, and other interferences do not cause obvious changes, indicating that the prepared carbon dot / polypropylene melt-blown cloth test strip has good selectivity for phosgene.

[0079] Example 4

[0080] Fluorescent carbon dots for removal of gaseous phosgene

[0081] (a) The Cdot stock solution was added into acetonitrile to prepare a 200 μg / mL Cdot acetonitrile solution.

[0082] (b) Prepare standard test strips: soak polypropylene meltblown cloth in 200 μg / mL carbon dot acetonitrile solution, take it out and dry it after 5 minutes, repeat this process 3 times, and cut the soaked polypropylene meltblown cloth into 1×0.6 cm test strips to obtain standard test strips.

[0083] (c) Establishing a standard, using a centrifuge tube with a capacity of 50 mL as the test container, taking 6 centrifuge tubes numbered 16-21, and the specific experimental steps are: taking 6 standard test strips and sticking them in the lids on the top of each centrifuge tube, and then adding acetonitrile, triethylamine solution (1 mM) and triphosgene solution (2 mM) to the centrifuge tubes in sequence, fixing the total volume of the solution in each centrifuge tube to be 20 μL, and the gaseous phosgene concentrations in centrifuge tubes 16-21 to be 0 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, and 25 ppm, respectively. Immediately after the addition is completed, the tube caps are covered, and after sealing for 5 minutes, the fluorescence color changes of the standard test strips under different concentrations of phosgene are observed under a 365 nm ultraviolet lamp and RGB fitting is performed on them, the standard test strips under gradient concentrations of phosgene are used as standard reference substances, and the linear relationship of RGB fitting is used as the standard working curve;

[0084] The solution in centrifuge tubes No. 16-21 is as follows:

[0085] No. 16: 20 μL acetonitrile as reference;

[0086] No. 17: 1.7 μL triphosgene solution + 1 μL triethylamine solution + 17.3 μL acetonitrile;

[0087] No. 18: 3.4 μL triphosgene solution + 1 μL triethylamine solution + 15.6 μL acetonitrile;

[0088] No. 19: 5.1 μL triphosgene solution + 1 μL triethylamine solution + 13.9 μL acetonitrile;

[0089] No. 20: 6.8 μL triphosgene solution + 1 μL triethylamine solution + 12.2 μL acetonitrile;

[0090] No. 21: 8.5 μL triphosgene solution + 1 μL triethylamine solution + 10.5 μL acetonitrile.

[0091] (d) Soak a polypropylene meltblown cloth (8.5*8.5cm) in a 200 μg / mL carbon dot acetonitrile solution in a volume of 2ml. Take it out and dry it after 5min. Repeat 3 times. Cut the soaked polypropylene meltblown cloth into a circle with a diameter of 4cm as a filter layer so that it can just be stuck in a 50mL centrifuge tube. Take 2 50mL centrifuge tubes, prepare phosgene at the bottom of the centrifuge tube to simulate phosgene leakage, set the prepared filter layer in the middle of one of the centrifuge tubes as an experimental group, and set a polypropylene meltblown cloth (with a diameter of 4cm) without fluorescent carbon dots in the middle of another centrifuge tube as a blank group. Stick a 1×0.6cm standard test strip in the top cover of the two centrifuge tubes to detect the phosgene content in the filtered gas. The initial concentration of phosgene is selected as 20ppm.

[0092] (e) After 5 minutes of sealing, observe the fluorescent colors of the two standard test strips under sunlight and 365 nm ultraviolet light and compare them with the standard reference substance. Calculate the phosgene content in the filtered gas according to the standard working curve.

[0093] Figure 7 (a) It can be seen that: as the phosgene concentration increases, under a 365nm ultraviolet lamp, the fluorescence of the standard test strip changes from blue to yellow-green, and the degree of change increases; Figure 7 (b) and (c) show that as the phosgene concentration increases, the values ​​of the R channel and the G channel increase gradually, and the value of the G channel has a good linear relationship with the phosgene concentration. The linear equation is y = 4.17x + 75.85, where R 2 =0.9910, y represents the value of G channel, and x represents the concentration of phosgene.

[0094] from Figure 8 (a) It can be seen that the color of the standard test strip of the blank group changes from white to slightly yellow under sunlight, and the fluorescence changes from blue to yellow-green under 365nm ultraviolet light, indicating that the polypropylene meltblown cloth itself does not have the ability to remove phosgene, while the standard test strip of the experimental group has basically no change, indicating that the polypropylene meltblown cloth loaded with fluorescent carbon dots can remove the phosgene generated at the bottom of the centrifuge tube; Figure 8 (b) and Figure 8 (c) shows that the experimental group detected a phosgene concentration of 1.55 ppm after filtration, and the phosgene removal rate was 92.25%, while the blank group detected a phosgene concentration of 19.14 ppm after filtration, which also shows that the polypropylene meltblown cloth itself does not have the ability to remove phosgene. This indicates that the polypropylene meltblown cloth with a larger pore structure and a higher specific surface area can load a large amount of fluorescent carbon dots to achieve effective removal of phosgene.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. 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 carbon dots that respond quickly and sensitively to phosgene, characterized in that: The carbon dots are prepared by using 4-(4-aminophenyl)thiomorpholine-1,1-dioxide as a precursor and anhydrous ethanol as a solvent through a solvothermal reaction, and then eluting and rotary evaporation after the reaction is completed; The initial concentration of the 4-(4-aminophenyl)thiomorpholine-1,1-dioxide in anhydrous ethanol is 18.4 mM; The elution was performed by using a mixture of dichloromethane and methanol in a volume ratio of 180:

1.

2. Use of the carbon dots according to claim 1 in phosgene monitoring.

3. The use of carbon dots in phosgene monitoring according to claim 2, characterized in that: Used for monitoring phosgene in solution, the carbon dots can realize colorimetric and ratiometric dual responses to phosgene, and respond quickly to phosgene in solution, with a response time of less than 1 s.

4. The use of carbon dots in phosgene monitoring according to claim 2, characterized in that: For monitoring of gaseous phosgene, the steps are: (1) dissolving the carbon dots in dimethyl sulfoxide to prepare a carbon dot stock solution, and adding the carbon dot stock solution into acetonitrile to prepare a 200 μg / mL carbon dot acetonitrile solution; (2) Cut the polypropylene meltblown fabric into strips of 0.5 × 0.5 cm and soak them in a 200 μg / mL carbon dot acetonitrile solution. After 5 min, take them out and let them dry naturally. Repeat the soaking-drying process 3 times to obtain a carbon dot / polypropylene meltblown fabric test strip. (3) The prepared carbon dot / polypropylene meltblown fabric test strips were placed in a gaseous phosgene environment with different concentrations, sealed for 1 min and then taken out. The fluorescent color changes of the test strips were observed under a 365 nm ultraviolet lamp.

5. The use of carbon dots in phosgene removal according to claim 1, characterized in that: The carbon dots are loaded on a permeable carrier with large pores and high specific surface area, or the carbon dots are mixed with a gel matrix to prepare an aerogel with a good pore structure and high specific surface area, and the carrier or aerogel loaded with the carbon dots is used to remove phosgene in the environment.

6. The use of carbon dots in phosgene removal according to claim 5, characterized in that: The carrier is any one of polypropylene melt-blown cloth, fiber, cotton sheet and sponge.

7. The use of carbon dots in phosgene removal according to claim 6, characterized in that: The carrier is a polypropylene meltblown cloth, and the polypropylene meltblown cloth loaded with the carbon dots can be used on the surface of masks, clothes or other objects to prevent human inhalation and contact or to achieve the purpose of real-time removal of trace phosgene in the air.

8. The use of the carbon dots in phosgene removal according to any one of claims 5 to 7, characterized in that The steps include: (a) dissolving the carbon dots in dimethyl sulfoxide to prepare a carbon dot stock solution, and adding the carbon dot stock solution into acetonitrile to prepare a 200 μg / mL carbon dot acetonitrile solution; (b) Prepare standard test strips by soaking polypropylene meltblown cloth in 200 μg / mL carbon dot acetonitrile solution, taking it out and drying it after 5 min, repeating it for 3 times, and cutting the soaked polypropylene meltblown cloth into 1×0.6 cm test strips to obtain standard test strips; (c) Establishing a standard, placing a standard test strip in the lid on the top of the test container, preparing phosgene at the bottom of the test container, and after 5 minutes, observing the fluorescence color changes of the standard test strip under different concentrations of phosgene under a 365nm ultraviolet lamp and performing RGB fitting on them, using the standard test strip under gradient concentrations of phosgene as the standard reference, and using the linear relationship of RGB fitting as the standard working curve; (d) cutting the carrier loaded with the carbon dots into a structure whose size and shape are compatible with the test container as a filter layer, preparing phosgene at the bottom of the test container to simulate phosgene leakage, setting the filter layer in the middle of the test container to filter the phosgene generated at the bottom, and placing a standard test strip in the cover on the top of the test container to detect the phosgene content in the filtered gas; (e) comparing the standard test strip after detection in step (d) with the standard reference substance in step (c), and calculating the phosgene content in the filtered gas according to the standard working curve.

9. The use of carbon dots in phosgene removal according to claim 8, characterized in that: The removal rate of phosgene can reach 92.25%.

Images