A six-membered cucurbitacin-based carbon quantum dot for rapid detection of 2,4-dinitrophenol in water and its preparation method and application

Abstract

The invention discloses a six-membered cucurbitacin-based carbon quantum dot capable of rapidly detecting 2,4-dinitrophenol in water, and a preparation method and application thereof. The six-membered cucurbitacin-based carbon quantum dot (Q[6]-CQDs) is a fluorescent carbon quantum dot doped with nitrogen and sulfur, synthesized by a hydrothermal method using common six-membered cucurbitacin and p-aminobenzenesulfonamide as carbon source and nitrogen source. The obtained Q[6]-CQDs has good water dispersibility, photostability and strong blue-green fluorescence emission, and can be used for fluorescent identification of 2,4-dinitrophenol in aqueous solution. The detection method has the characteristics of high sensitivity, high accuracy, simple detection method and low cost. The fluorescent carbon quantum dot is used for the determination of 2,4-dinitrophenol in simulated wastewater samples, and the recovery rate is 98.0% to 107.0%, obtaining satisfactory results.

Description

Technical Field

[0001] The invention relates to the technical field of 2,4-dinitrophenol detection, in particular to a six-membered cucurbitacin-based carbon quantum dot for rapid detection of 2,4-dinitrophenol (2,4-DNP), and a preparation method and application thereof. Background Art

[0002] Phenolic compounds are major environmental organic pollutants with potential carcinogenic and teratogenic toxicity. In particular, nitrophenols are widely distributed in the ecological environment and are highly harmful, causing great harm to the environment and human body.

[0003] 2,4-Dinitrophenol can cause fatty acid metabolism and easily enter the body through the skin, which can cause human weakness or even death. It is one of the typical organic pollutants in the environment and is a phenolic pollutant that the US Environmental Protection Agency prioritizes for determination. In addition, a large amount of organic wastewater is discharged during the production process of 2,4-Dinitrophenol, which is toxic to the human body and the ecosystem, and is very prominent in environmental pollution. Therefore, the search for efficient methods to identify and detect 2,4-Dinitrophenol in the environment has attracted worldwide attention.

[0004] So far, the methods used to detect 2,4-dinitrophenol include high performance liquid chromatography-mass spectrometry, capillary electrophoresis, electrochemical method, colorimetry, etc., but these methods have many disadvantages such as cumbersome operation steps, high cost, long analysis time and frequent calibration, which makes it difficult to detect actual samples on site. In contrast, the fluorescence method has the advantages of simple operation, simple experiment, good selectivity, short analysis time and high sensitivity, and has advantages in environmental monitoring.

[0005] Therefore, it is of great significance to develop a highly sensitive, simple and low-cost analytical method to detect fluorescent materials for 2,4-dinitrophenol in the environment. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a six-membered cucurbitacin-based carbon quantum dot for rapid detection of 2,4-dinitrophenol in water, and a preparation method and application thereof. By using common six-membered cucurbitacin and p-aminobenzenesulfonamide as carbon source and nitrogen source to construct nitrogen- and sulfur-doped fluorescent carbon quantum dots, 2,4-dinitrophenol in aqueous solution can be sensitively identified and quantitatively detected through fluorescence changes. This method has the advantages of high sensitivity, high accuracy, simple detection method and low cost.

[0007] The technical solution of the present invention is: a six-membered cucurbitacin-based carbon quantum dot for rapid detection of 2,4-dinitrophenol in water, wherein the six-membered carbon quantum dot is a nitrogen- and sulfur-doped fluorescent carbon quantum dot synthesized by a hydrothermal method using common six-membered cucurbitacin and p-aminobenzenesulfonamide as carbon source and nitrogen source.

[0008] The structural formula of the common six-membered cucurbitacin and p-aminobenzenesulfonamide is:

[0009] in, It is an ordinary six-membered melon ring.

[0010] It is p-aminobenzenesulfonamide, and the molar ratio of the common six-membered cucurbitacin ring to p-aminobenzenesulfonamide is 1:(1.2-1.3).

[0011] The particle size of the six-membered cucurbitacin-based carbon quantum dots is 1.75-6 nm, the excitation wavelength is 260 nm, and the emission wavelength is 325-450 nm.

[0012] The method for preparing six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water comprises the following steps: (1) dissolving common six-membered cucurbitacin and p-aminobenzenesulfonamide in water, and uniformly mixing the two substances by ultrasonic treatment; (2) placing the above solution in a polytetrafluoroethylene reactor, reacting at 160°C to 180°C for 10 to 12 hours, cooling the obtained yellow solution to room temperature, centrifuging and collecting the supernatant, filtering the supernatant with an ultrafiltration membrane, and collecting the filtrate, wherein the filtrate is the six-membered cucurbitacin-based carbon quantum dot solution; (3) transferring the filtrate obtained in step (2) into a dialysis bag with a molecular cutoff mass of 1000Da, and dialyzing it in ultrapure water; and then freeze-drying the dialyzed solution to obtain the six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water.

[0013] In step (2), the pore size of the ultrafiltration membrane is 0.45 μm; and the rotation speed of the centrifugal treatment is 4000 r / min.

[0014] The application of the six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water comprises dissolving the six-membered cucurbitacin-based carbon quantum dots in water to prepare a standard solution, and using the solution to perform fluorescence sensing or quantitative detection of 2,4-dinitrophenol in a liquid sample.

[0015] The fluorescence sensing method comprises the following steps: (1) adding the six-membered cucurbitacin-based carbon quantum dot solution to the aqueous solution to be tested, measuring the fluorescence emission spectrum at an excitation wavelength of 260 nm, and drawing a fluorescence intensity change graph; (2) adding the six-membered cucurbitacin-based carbon quantum dot standard solution to the aqueous solution to be tested according to the curve calculation of step (1), measuring the fluorescence intensity change value ΔI before and after at an emission wavelength of 350 nm, and thus detecting 2,4-dinitrophenol in water.

[0016] The quantitative detection method comprises the following steps: (1) preparing a standard solution of the six-membered cucurbitacin-based carbon quantum dots, adding 2,4-dinitrophenol solutions of different concentrations, and performing fluorescence spectrum measurement respectively, and establishing a standard curve equation with the fluorescence intensity of the six-membered cucurbitacin-based carbon quantum dots as the ordinate and the concentration of 2,4-dinitrophenol as the abscissa; (2) adding a sample to be tested to the solution of the six-membered cucurbitacin-based carbon quantum dots to obtain a solution to be tested, measuring the fluorescence spectrum of the solution to be tested, and substituting it into the standard curve equation to obtain the concentration of 2,4-dinitrophenol.

[0017] In step (2), the sample to be tested is simulated wastewater containing 2,4-dinitrophenol.

[0018] Beneficial effects of the present invention:

[0019] 1. The present invention provides an application of hexamembered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water. Hexamembered cucurbitacin and p-aminobenzenesulfonamide are used as carbon sources and nitrogen sources, and nitrogen- and sulfur-doped carbon quantum dots with fluorescent properties are synthesized by a hydrothermal method. The present invention is a new type of fluorescent carbon quantum dot material.

[0020] 2. The six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water of the present invention have stable performance, good selectivity for 2,4-dinitrophenol, minimal effect of other phenols on the detection results, strong anti-interference ability, high sensitivity, high accuracy and simple detection method; and the six-membered cucurbitacin-based carbon quantum dots have the advantages of excellent photostability, good water solubility, low toxicity and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 (a) UV absorption spectrum of carbon quantum dots; (b) fluorescence emission spectrum;

[0022] Figure 2 This is the infrared absorption spectrum of carbon quantum dots;

[0023] Figure 3 (a) XPS spectrum of carbon quantum dots and (b) high-resolution spectrum of C1s;

[0024] Figure 4 (a) Fluorescence spectrum (λex = 260 nm) of 2,4-dinitrophenol gradually added to the six-membered cucurbitacin-based carbon quantum dot solution (40 μg / mL) of the present invention; (b) Fluorescence intensity increases with C [2,4-DNP] (c) The fluorescence response diagram of the six-membered cucurbitacin-based carbon quantum dots of the present invention to some phenols; (d) From left to right, the fluorescence photographs of the six-membered cucurbitacin-based carbon quantum dots of the present invention without and with 2,4-DNP added are shown respectively;

[0025] Figure 5 The fluorescence spectra of Q6-CDs-2,4-DNP (40 μg / mL) system and other phenolic pollutants respectively;

[0026] Figure 6 It is a linear relationship diagram between the fluorescence intensity change of six-membered cucurbitacin-based carbon quantum dots in the presence of different concentrations of 2,4-dinitrophenol and the standard curve equation of different concentrations of 2,4-dinitrophenol;

[0027] Figure 7 This is a schematic diagram of the structure of an ordinary melon ring. DETAILED DESCRIPTION

[0028] The present invention is further described below with reference to the embodiments, but they are not intended to limit the present invention.

[0029] Embodiments of the present invention

[0030] Embodiment 1:

[0031] A six-membered cucurbitacin-based carbon quantum dot for rapid detection of 2,4-dinitrophenol in water is prepared by the following method:

[0032] (1) Dissolve ordinary six-membered cucurbitacin (135 mg, 0.14 mmol) and p-aminobenzenesulfonamide (29 mg, 0.17 mmol) in 50 mL of ultrapure water, and mix the two substances evenly by ultrasonic treatment;

[0033] (2) placing the above solution in a polytetrafluoroethylene reactor, reacting at 160° C. to 180° C. for 10 to 12 hours, cooling the obtained yellow solution to room temperature, centrifuging it for 50 minutes (4000 r / min), collecting the supernatant, and filtering it with an ultrafiltration membrane to obtain a filtrate, which is a six-membered cucurbitacin-based carbon quantum dot solution;

[0034] (3) The filtrate obtained in step (1) is transferred into a dialysis bag with a molecular cutoff mass of 1000 Da, and dialyzed in ultrapure water for 24 hours. The dialyzed solution is then freeze-dried to obtain six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water.

[0035] See also Figure 1 (a) and (b) are respectively the ultraviolet absorption spectrum and the fluorescence emission spectrum of the six-membered cucurbitacin-based carbon quantum dots in Example 1. It can be seen from the figure that the carbon quantum dots have ultraviolet absorption peaks at 260nm and 445nm, and the fluorescence emission wavelength is 325-450nm.

[0036] See also Figures 2-3, respectively, are the XPS spectra and infrared absorption spectra of the six-membered cucurbitacin-based carbon quantum dots in Example 1. It can be seen from the XPS spectra and infrared absorption spectra that the carbon quantum dots prepared using the six-membered cucurbitacin and p-aminobenzenesulfonamide as carbon and nitrogen sources have amino and sulfonyl groups on their surfaces.

[0037] Embodiment 2:

[0038] Detection method of 2,4-dinitrophenol in water to be tested:

[0039] (1) Take the six-membered cucurbitacin-based carbon quantum dots prepared in Example 1, dissolve them in water, and prepare a standard solution with a concentration of 40 μg / mL;

[0040] (2) Add the aqueous solution to be tested to the standard solution. If the fluorescence of the solution at 350 nm is significantly reduced under an excitation wavelength of 260 nm, it indicates that the aqueous solution to be tested contains 2,4-dinitrophenol.

[0041] (3) Qualitative testing process:

[0042] When different phenol solutions (2,4-diaminophenol (2,4-AP), 2,4-dinitrophenol (2,4-DNP), 3-bromophenol (3-BP), 4-bromophenol (4-BP), 4-aminophenol (4-AP), 3-aminophenol (3-AP), 3-aminophenol (2-AP), 4-methylphenol (4-MP), 3-methylphenol (3-MP), 4-chlorophenol (4-CP), hydroquinone (HQ), catechol (CL), phenol (Ph), phloroglucinol (PG), pyrogallol (Pyro), meta-trichlorophenol (2,4,6-TCP), pentachlorophenol (PCP), o-nitrophenol (o-NP)) were added to the standard solution (volume 3 mL, concentration 40 μg / mL), only 2,4-dinitrophenol caused a significant decrease in the fluorescence intensity of the system, while other phenols had no effect on the fluorescence. The results are shown in Figure 2. Figure 5 As shown in (c) and (d);

[0043] (4) Quantitative detection process:

[0044] Different concentrations of 2,4-dinitrophenol solutions (concentration gradient of 0, 1, 3, ..., 20, 25, 30 μM) were added to the standard solution (volume 3 mL, concentration 40 μg / mL) for fluorescence spectrum detection. As the concentration of 2,4-dinitrophenol continued to increase, the fluorescence intensity of the carbon quantum dot system gradually decreased at 350 nm until the concentration of 2,4-dinitrophenol reached 30 μM, and the fluorescence intensity change reached equilibrium, as shown in FIG. Figure 4(a)(b) As shown. When the concentration of 2,4-dinitrophenol in the system is 0-10 μM, a good linear relationship is shown. The fluorescence intensity of the carbon quantum dot system is used as the ordinate and the concentration of 2,4-dinitrophenol is used as the abscissa to establish a standard curve, as shown in FIG. Figure 6 As shown, the standard curve equation is: I = -16.45C + 654.82, R 2 =0.9931, where C is the concentration of 2,4-dinitrophenol in μM, and the detection limit is 0.15 μM.

[0045] (4) Anti-interference determination of other phenols:

[0046] Prepare phenol solution with a concentration of 2.00×10 -3 mol / L, a standard solution of six-membered cucurbitacin-based carbon quantum dots (volume 3mL, concentration 40μg / mL) was added to 17 test tubes respectively, and then a 30μM 2,4-dinitrophenol solution was added. The fluorescence intensity decreased significantly, and then other phenol solutions were added to the system respectively, and the fluorescence of the system did not change. Figure 5 As shown, it is proved that other phenols will not interfere with the detection of 2,4-dinitrophenol in the system.

[0047] Embodiment 3:

[0048] Quantitative detection method of 2,4-dinitrophenol in simulated wastewater:

[0049] (1) Configuration of simulated wastewater liquid sample to be tested:

[0050] Prepare 10 mL of simulated wastewater liquid sample containing 2,4-dinitrophenol, which contains common ions in wastewater, as well as organic pollutants such as aniline, hydroquinone and phenol;

[0051] (2) Quantitative detection process of 2,4-dinitrophenol in simulated wastewater:

[0052] The test liquid of Example (1) was added to the six-membered cucurbitacin-based carbon quantum dot solution, and then 4, 6, 8, and 9 μM of 2,4-dinitrophenol were added respectively to obtain a test solution. The fluorescence spectrum was measured, and the obtained fluorescence intensity I was substituted into the standard curve equation of Example 2 (4) to obtain the concentration of 2,4-dinitrophenol. The parallel measurement was repeated three times, and the recovery rate was calculated as shown in Table 1.

[0053] Table 1 shows the detection results of 2,4-dinitrophenol in simulated wastewater

[0054]

[0055] As shown in Table 1, the recovery rate of the six-membered cucurbitacin-based carbon quantum dots provided by the present invention for detecting 2,4-dinitrophenol ranges from 98.00% to 107.00%. The results show that Q6-CQDs as a fluorescent probe is suitable for the quantitative determination of 2,4-dinitrophenol in water.

[0056] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Other technical solutions and inventive concepts created according to the present invention and equivalently replaced or changed should all be included in the protection scope of the present invention.

Claims

1. A six-membered cucurbitacin-based carbon quantum dot for rapid detection of 2,4-dinitrophenol in water, characterized in that: The six-membered carbon quantum dots are nitrogen- and sulfur-doped fluorescent carbon quantum dots synthesized by a hydrothermal method using common six-membered cucurbitacin and p-aminobenzenesulfonamide as carbon source and nitrogen source.

2. The six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water according to claim 1, characterized in that: The structural formula of the common six-membered cucurbitacin and p-aminobenzenesulfonamide is: in, It is an ordinary six-membered melon ring. It is p-aminobenzenesulfonamide, and the molar ratio of the common six-membered cucurbitacin ring to p-aminobenzenesulfonamide is 1:(1.2-1.3).

3. The six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water according to claim 1, characterized in that: The particle size of the six-membered cucurbitacin-based carbon quantum dots is 1.75-6 nm, the excitation wavelength is 260 nm, and the emission wavelength is 325-450 nm.

4. A method for preparing six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: (1) dissolving common six-membered cucurbitacin and p-aminobenzenesulfonamide in water, and mixing the two substances uniformly by ultrasonic treatment; (2) placing the above solution in a polytetrafluoroethylene reactor, reacting at 160° C. to 180° C. for 10 to 12 hours, cooling the obtained yellow solution to room temperature, centrifuging and collecting the supernatant, and filtering the supernatant with an ultrafiltration membrane to obtain a filtrate, wherein the filtrate is a six-membered cucurbitacin-based carbon quantum dot solution; (3) transferring the filtrate obtained in step (2) into a dialysis bag with a molecular cutoff mass of 1000 Da, and dialyzing it in ultrapure water; and then freeze-drying the dialyzed solution to obtain six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water.

5. The preparation method according to claim 4, characterized in that: In step (2), the pore size of the ultrafiltration membrane is 0.45 μm; and the rotation speed of the centrifugal treatment is 4000 r / min.

6. The use of six-membered cucurbitacin-based carbon quantum dots for rapid detection of 2,4-dinitrophenol in water as claimed in any one of claims 1 to 3, characterized in that: The six-membered cucurbitacin-based carbon quantum dots are dissolved in water to prepare a standard solution, and the solution is used to perform fluorescence sensing or quantitative detection on 2,4-dinitrophenol in a liquid sample.

7. The use according to claim 6, characterized in that: The fluorescence sensing method comprises the following steps: (1) adding the six-membered cucurbitacin-based carbon quantum dot solution to the aqueous solution to be tested, performing fluorescence emission spectrum measurement at an excitation wavelength of 260 nm, and drawing a fluorescence intensity change graph; (2) adding the six-membered cucurbitacin-based carbon quantum dot standard solution to the aqueous solution to be tested according to the curve calculation of step (1), measuring the fluorescence intensity change value ΔI before and after at an emission wavelength of 350 nm, and thus detecting 2,4-dinitrophenol in water.

8. The use according to claim 6, characterized in that: The quantitative detection method comprises the following steps: (1) preparing a standard solution of the six-membered cucurbitacin-based carbon quantum dots, adding 2,4-dinitrophenol solutions of different concentrations, and performing fluorescence spectrum measurement respectively, and establishing a standard curve equation with the fluorescence intensity of the six-membered cucurbitacin-based carbon quantum dots as the ordinate and the concentration of 2,4-dinitrophenol as the abscissa; (2) adding a sample to be tested to the solution of the six-membered cucurbitacin-based carbon quantum dots to obtain a solution to be tested, measuring the fluorescence spectrum of the solution to be tested, and substituting it into the standard curve equation to obtain the concentration of 2,4-dinitrophenol.

9. The use according to claim 8, characterized in that: In step (2), the sample to be tested is simulated wastewater containing 2,4-dinitrophenol.

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