A graphene quantum dot based on electron absorption and supply regulation and its preparation method and application in dye detection
By preparing yellow fluorescent graphene quantum dots based on electron absorption and donation regulation, the problem of low sensitivity of existing dye detection methods is solved, and high-sensitivity, rapid and simple selective identification and detection of methylene blue dye is achieved, which is suitable for dye pollution detection in textile wastewater.
Patent Information
- Application Number
- CN202410786394.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-18
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2044-06-18
AI Technical Summary
Existing dye detection methods have low sensitivity and are difficult to quickly and accurately detect methylene blue dye in textile wastewater.
Yellow fluorescent graphene quantum dots (y-GQDs) regulated by electron absorption and donation were prepared by a bottom-up hydrothermal method. 1-Amino-2-naphthol-4-sulfonic acid and acrylic acid were used as precursors. Through filtration and dialysis treatment, y-GQDs with excellent performance were prepared for the selective recognition of methylene blue dye.
The method achieves highly sensitive, rapid, and simple selective identification and detection of methylene blue dye, has good dispersibility and water solubility, is simple to operate, and has low cost, making it suitable for the detection of dye pollution in textile wastewater.
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Figure CN118725860B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of nanomaterials and detection, and in particular relates to a graphene quantum dot based on electron absorption and supply regulation, a preparation method thereof, and an application thereof in dye detection. Background Art
[0002] In recent years, with the rapid development of urbanization and industrialization, especially in some developing countries, textile wastewater pollution has become a serious environmental and public health issue, posing a major threat to human health and the environment. The dye industry is one of my country's traditional advantageous industries, but most of these dyes are toxic to organisms and have adverse effects on aquatic life.
[0003] Methylene blue (MLB) is a cationic dye that is soluble in water. However, its presence can negatively impact aquatic life, including blocking sunlight from penetrating the water, causing gastrointestinal irritation, and even causing eye burns, increased heart rate, difficulty breathing, confusion, nausea, vomiting, and even carcinogenicity after ingestion. Therefore, effective detection of these dyes in water is crucial. Common methods for dye detection include colorimetry, UV spectrophotometry, liquid chromatography, mass spectrometry, simultaneous voltammetry, and surface-enhanced Raman scattering. However, these methods suffer from relatively low sensitivity. Therefore, developing a simple, rapid, selective, and accurate method for dye detection is crucial. Among these methods, fluorescence sensing, due to its rapid response and high sensitivity, has become a powerful technique for detecting trace amounts of neutral and ionic (bio)molecules, as well as inorganic ions.
[0004] In recent years, graphene quantum dots (GQDs), a new type of luminescent nanomaterial, comprise graphene-derived substances with diameters less than 20 nm, have shown great potential in dye detection due to their excellent chemical stability, solubility, and cost-effectiveness. Furthermore, GQDs typically possess various functional groups, such as hydroxyl, carbonyl, and carboxyl groups, which give them excellent water solubility and broad application. Summary of the Invention
[0005] To address this pressing technical problem, the present invention proposes a yellow fluorescent graphene quantum dot based on electron absorption and donation control, its preparation method, and its application in dye detection, addressing the urgent need for dye detection. Using 1-amino-2-naphthol-4-sulfonic acid as a precursor and acrylic acid as an electron modulator, a bottom-up hydrothermal method was used to prepare high-performance yellow fluorescent graphene quantum dots (y-GQDs). After acrylic acid manipulation, yellow y-GQDs were obtained. Finally, the present invention used the even more superior y-GQDs to test their selective dye recognition in textile wastewater, ultimately achieving successful selective recognition and detection of methylene blue dye. This research has important implications for addressing dye pollution.
[0006] In order to achieve the above object, the technical solution of the present invention is achieved as follows:
[0007] A method for preparing yellow fluorescent graphene quantum dots based on electron absorption and supply regulation comprises the following steps:
[0008] A mixed aqueous solution of 1-amino-2-naphthol-4-sulfonic acid and acrylic acid is subjected to a hydrothermal reaction, cooled, and then filtered to prepare a yellow fluorescent graphene quantum dot solution.
[0009] Preferably, the mass volume ratio of the 1-amino-2-naphthol-4-sulfonic acid, acrylic acid and water is 1g:5-20ml:70-100ml.
[0010] Preferably, the temperature of the hydrothermal reaction is 120-230° C., and the time is 6-24 h.
[0011] Preferably, the filtration is performed sequentially using a filter membrane and dialysis filtration, the pore size of the filter membrane filtration is not greater than 220 nm; the dialysis is performed using ultrapure water until the ultrapure water becomes clear, the dialysis time is 24-48 h, and the solution in the dialysis bag is a yellow fluorescent graphene quantum dot solution.
[0012] Preferably, the yellow fluorescent graphene quantum dots prepared by the above method based on electron absorption and donation control are in the form of graphene nanosheets at the nanoscale, and the structure includes sulfur atoms, amino groups or hydroxyl groups connected to carbon atoms.
[0013] Preferably, the yellow fluorescent graphene quantum dot nanosheets have an average particle size of 0.1-20 nm and an average thickness of 0.1-5 nm.
[0014] Preferably, the yellow fluorescent graphene quantum dots regulated by electron absorption and donation are used in the detection of methylene blue dye.
[0015] Preferably, the above-mentioned application of yellow fluorescent graphene quantum dots based on electron absorption and donation regulation in the detection of methylene blue dye comprises the following steps:
[0016] 1) Add yellow fluorescent graphene quantum dots regulated by electron absorption and donation to a sample containing methylene blue dye to measure the fluorescence intensity of the sample;
[0017] 2) Substitute the fluorescence intensity measured in step 1) into the linear equation of the fluorescence intensity of the yellow fluorescent graphene quantum dots and different concentrations of methylene blue dye to calculate the concentration of methylene blue dye in the sample to be tested.
[0018] Preferably, the fluorescence intensity test adopts the maximum excitation wavelength of 370 nm for excitation, and the fluorescence intensity is the fluorescence intensity at the maximum emission wavelength of 500 nm.
[0019] Preferably, the linear equation in step 2) is y=3323.23963-501.01717x, where x is the concentration of methylene blue dye in μmol / L, and y is the fluorescence intensity in au.
[0020] The present invention has the following beneficial effects:
[0021] 1. The preparation method of the present invention is simple, rapid, green and economical, and can efficiently prepare graphene quantum dots. The prepared y-GQDs have good fluorescence performance, good dispersion, uniform size, high selectivity and recognition of methylene blue dye, high sensitivity, and fast and easy detection.
[0022] 2. The y-GQDs of the present invention are specific for methylene blue dye and cannot recognize other dyes, allowing for qualitative or quantitative detection of methylene blue. The preparation method of the present invention is simple, rapid, environmentally friendly, and economical. The prepared y-GQDs have excellent fluorescence properties, are uniform in size, are non-toxic, have specificity for methylene blue dye detection, are highly sensitive to methylene blue dye, and are quick and easy to detect. The selective recognition and detection of methylene blue dye is successfully achieved. This detection method is simple, rapid, cost-effective, and requires little manpower and effort, making it of great practical value in the field of methylene blue dye detection. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.
[0024] Figure 1 Atomic force microscopy (AFM) image (a) and height distribution diagram (b) of y-GQDs prepared in Example 1 of the present invention.
[0025] Figure 2 Transmission electron microscopy (TEM) image (a), high-resolution TEM image (the inset is the fast Fourier transform mode) (b) and size distribution diagram of y-GQDs (c) prepared in Example 1 of the present invention.
[0026] Figure 3 This is the X-ray photoelectron energy spectrum (XPS) of y-GQDs prepared in Example 1 of the present invention.
[0027] Figure 4 X-ray photoelectron spectroscopy (XPS) of y-GQDs prepared in Example 1 of the present invention: high-resolution C1s (a), N1s (b), O1s (c) and S2p (d) spectra.
[0028] Figure 5 This is a Fourier transform infrared spectrum (FT-IR) graph of y-GQDs prepared in Example 1 of the present invention.
[0029] Figure 6 This is the X-ray diffraction analysis (XRD) pattern of y-GQDs prepared in Example 1 of the present invention.
[0030] Figure 7 This is the Raman spectrum of y-GQDs prepared in Example 1 of the present invention.
[0031] Figure 8 The UV absorption spectrum (ABS), photoluminescence spectrum (PL) and photoexcitation spectrum (PLE) of y-GQDs prepared in Example 1 of the present invention are shown.
[0032] Figure 9 This is a comparison chart of the fluorescence intensity of Example 2 of the present invention; Figure 9 a is a comparison chart of the light intensity of y-GQDs after adding different dyes to y-GQDs in Example 2 of the present invention; Figure 9 b is a graph showing the fluorescence intensity change of y-GQDs according to Example 2 of the present invention as the concentration of methylene blue dye changes; Figure 9 c is a linear relationship diagram of the normalized fluorescence intensity of the y-GQDs solution of Example 2 of the present invention and the concentration of methylene blue dye. DETAILED DESCRIPTION
[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.
[0034] Example 1
[0035] This embodiment provides a method for preparing graphene quantum dots, which specifically includes the following steps:
[0036] a: Dissolve 0.59 g of 1-amino-2-naphthol-4-sulfonic acid and 5 mL of acrylic acid in 50 mL of deionized water, shaken by ultrasound, and mixed thoroughly to obtain a mixed solution;
[0037] b: The mixed solution was transferred to a 100 mL polytetrafluoroethylene stainless steel reactor and subjected to hydrothermal reaction under closed conditions at a temperature of 180°C and a reaction time of 12 h;
[0038] c) After the reaction is completed, the mixture is cooled to room temperature and filtered through a 220 nm microporous membrane to obtain the reaction solution;
[0039] d: The reaction solution was placed in a dialysis bag for dialysis. The dialysis bag was dialyzed with ultrapure water for 48 h until the ultrapure water became clear. The solution in the dialysis bag was the y-GQDs solution.
[0040] The structure of the y-GQDs prepared in this example was characterized: Figure 1 AFM image (a) and height distribution diagram (b) of y-GQDs prepared in this example. The average thickness of y-GQDs is 3.54 nm, indicating that it is composed of multilayer graphene. Figure 2 The TEM image (a), high-resolution TEM image (b) (the inset is the fast Fourier transform mode), and size distribution diagram (c) of the y-GQDs prepared in this example show that the y-GQDs are evenly dispersed, with an average particle size of 2.4 nm. The high-resolution TEM image (b) clearly shows the crystal morphology of the y-GQDs and reveals a single crystal structure with a lattice spacing of 0.24 nm. The Fourier transform diagram shows that the regular hexagonal symmetry points in the diagram are similar to the benzene ring lattice structure of graphene. y-GQDs have a good single crystal structure and good lattice symmetry. This may be due to the effect of acrylic acid regulation, which gives them a better morphology.
[0041] Figure 3 This is the total X-ray photoelectron energy spectrum of y-GQDs prepared in this example. It can be seen from the figure that y-GQDs has four peaks, indicating that it contains four elements: C, N, O, and S.
[0042] Figure 4 The C1s, N1s, O1s and S2p spectra of y-GQDs prepared in this example illustrate that the surface of y-GQDs contains functional groups such as -NH2, -OH, and -COOH. The presence of these functional groups is the reason for their good dispersibility / water solubility.
[0043] Figure 5 This is the Fourier transform infrared spectrum of y-GQDs prepared in this example, at 3500-3300 cm −1 The peak at 2997 cm is the OH / NH stretching vibration peak; the CH stretching vibration at 2997 cm -1 The high-intensity peak at 1710 cm is attributed to the asymmetric stretching vibration of the carboxylate anion;−1 The characteristic peaks of the -CO group are attributed to the -CO group; at 1700 cm -1 The peaks near 1450 cm are attributed to C=O bonds; -1 The peak at 1403 cm corresponds to the CN stretching vibration, which indicates the presence of N elements on the surface of y-GQDs; -1 The absorption peaks at 1250 and 1180 cm correspond to the bending vibration absorption characteristic bands of CN; −1 The peaks at 1050 cm-1 reveal the presence of -COO and C-OH functional groups, respectively. −1 The peak at 840 cm corresponds to the stretching vibration absorption peak of SO; −1 At 650 cm −1 The peak at is the SC stretching vibration absorption peak. The above functional groups indicate that the surface of y-GQDs has many amino and hydroxyl groups, indicating that it has good hydrophilicity.
[0044] Figure 6 From the XRD pattern of the y-GQDs prepared in this example, it can be seen that there is an obvious diffraction peak at about 22.5° 2θ, and the interlayer spacing is 3.93Å.
[0045] Figure 7 The Raman spectrum of y-GQDs prepared in this example shows the typical disordered sp 3 The D peak of the hybrid carbon structure (1383 cm -1 ) and ordered sp 2 The G peak of graphitic carbon structure (1500 cm -1 ).
[0046] Figure 8 The UV absorption spectrum (ABS), photoexcitation spectrum (PLE) and photoluminescence spectrum (PL) of the y-GQDs prepared in this example show that the maximum excitation wavelength of the obtained y-GQDs is 370 nm, and the optimal emission wavelength of the fluorescence intensity is 500 nm.
[0047] Example 2
[0048] The y-GQDs prepared in Example 1 were used to detect methylene blue dye, and the linear relationship between fluorescence intensity and different concentrations of methylene blue dye was tested, specifically comprising the following steps:
[0049] a: 500 μL of y-GQDs solution was mixed with 500 μL of different dye solutions, and fluorescence tests were performed respectively to obtain a comparison chart of the fluorescence intensity of the y-GQDs solution after adding different dyes. The different dyes include methyl orange (MO), methyl blue (MB), methylene blue (MLB), malachite green (MG), rhodamine B (RB), rhodamine 6G (R6G), azure B dye (Azure B), cationic brilliant red 4G (ABR4G), etc.
[0050] b: 500 μL of y-GQDs solution was mixed with 500 μL of methylene blue dye at different concentrations. The volume was fixed to the concentrations of 0 μM, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.5 μM, and 2 μM. Fluorescence measurements were performed on the different mixed solutions, and the fluorescence spectra at the maximum fluorescence intensity of the methylene blue dye at different concentrations were plotted.
[0051] c: According to the maximum fluorescence intensity value of each fluorescence spectrum in step b, the normalized maximum intensity is used as the vertical axis and the concentration of methylene blue dye is used as the horizontal axis to obtain a linear relationship diagram between the fluorescence intensity of y-GQDs and different concentrations of methylene blue dye;
[0052] The fluorescence intensity in step (1) was substituted into the normalized curve to estimate the concentration of methylene blue dye in the mixed solution, with a deviation of ±0.01 mol / ml from the actual concentration.
[0053] Figure 9 a is a comparison chart of the fluorescence intensity of the y-GQDs solution after adding different dyes to the y-GQDs prepared in an embodiment of the present invention. It can be seen from the figure that the fluorescence intensity of y-GQDs is significantly reduced after adding methylene blue dye, and the fluorescence quenching phenomenon is obvious. However, when other dyes are added, there is no obvious fluorescence quenching phenomenon. Figure 9 b is a graph showing the fluorescence intensity of y-GQDs prepared in an embodiment of the present invention as the concentration of methylene blue dye changes. Figure 9 c is a linear relationship diagram of the normalized fluorescence intensity of the y-GQDs solution prepared in an embodiment of the present invention and the concentration of methylene blue dye. The linear regression equation is y=3323.23963-501.01717x, where x is the concentration of methylene blue dye in μmol / L, the concentration range of x is 0-2 μmol / L, and y is the fluorescence intensity in au; the correlation coefficient R 2The y-GQDs prepared in this paper have a high selectivity and sensitivity for methylene blue, enabling rapid and convenient detection of methylene blue. This also demonstrates that y-GQDs fluorescent probes have promising applications in biological and environmental testing.
[0054] Example 3
[0055] The method for preparing graphene quantum dots in this embodiment specifically includes the following steps:
[0056] a: Dissolve 0.59 g of 1-amino-2-naphthol-4-sulfonic acid and 8 mL of acrylic acid in 41.3 mL of deionized water, shake the mixture by ultrasonication, and mix thoroughly to obtain a mixed solution;
[0057] b: The mixed solution was transferred to a 100 mL polytetrafluoroethylene stainless steel reactor and subjected to hydrothermal reaction under closed conditions at a temperature of 230 °C for 6 h.
[0058] c) After the reaction is completed, the mixture is cooled to room temperature and filtered through a 220 nm microporous membrane to obtain the reaction solution;
[0059] d: The reaction solution was placed in a dialysis bag for dialysis. The dialysis bag was dialyzed with ultrapure water for 24 h until the ultrapure water became clear. The solution in the dialysis bag was the y-GQDs solution.
[0060] The y-GQDs prepared above were used to detect methylene blue dye, and the linear relationship between fluorescence intensity and different concentrations of methylene blue dye was tested, specifically including the following steps:
[0061] a: 500 μL of y-GQDs solution was mixed with 500 μL of methylene blue dye at different concentrations to a constant volume. The concentrations of methylene blue dye were 0 μM, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.5 μM, and 2 μM, respectively. Fluorescence measurements were performed on the different mixed solutions, and the fluorescence spectra at the maximum fluorescence intensity of the methylene blue dye at different concentrations were plotted.
[0062] b: According to the maximum fluorescence intensity value of each fluorescence spectrum in step a, the linear relationship diagram between the fluorescence intensity of y-GQDs and different concentrations of methylene blue dye is obtained with the normalized maximum intensity as the ordinate and the methylene blue dye concentration as the abscissa.
[0063] c: Based on the fluorescence intensity of step (1), the normalized curve is used to calculate the concentration of methylene blue dye in the mixed solution, with a deviation of ±0.01 mol / ml from the actual concentration.
[0064] Example 4
[0065] The method for preparing graphene quantum dots in this embodiment specifically includes the following steps:
[0066] a: Dissolve 0.59 g of 1-amino-2-naphthol-4-sulfonic acid and 5 mL of acrylic acid in 59 mL of deionized water, shake the mixture by ultrasonication, and mix thoroughly to obtain a mixed solution;
[0067] b: The mixed solution was transferred to a 100 mL polytetrafluoroethylene stainless steel reactor and subjected to hydrothermal reaction under closed conditions at a temperature of 200°C and a reaction time of 12 h;
[0068] c) After the reaction is completed, the mixture is cooled to room temperature and filtered through a 220 nm microporous membrane to obtain the reaction solution;
[0069] d: The reaction solution was placed in a dialysis bag for dialysis. The dialysis bag was dialyzed with ultrapure water for 48 h until the ultrapure water became clear. The solution in the dialysis bag was the y-GQDs solution.
[0070] The prepared y-GQDs were used to detect methylene blue dye. The linear relationship between fluorescence intensity and different concentrations of methylene blue dye was tested, which specifically included the following steps:
[0071] a: 500 μL of y-GQDs solution was mixed with 500 μL of methylene blue dye at different concentrations to a constant volume. The concentrations of methylene blue dye were 0 μM, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.5 μM, and 2 μM, respectively. Fluorescence measurements were performed on the different mixed solutions, and the fluorescence spectra at the maximum fluorescence intensity of the methylene blue dye at different concentrations were plotted.
[0072] b: According to the maximum fluorescence intensity value of each fluorescence spectrum in step a, the linear relationship diagram between the fluorescence intensity of y-GQDs and different concentrations of methylene blue dye is obtained with the normalized maximum intensity as the ordinate and the methylene blue dye concentration as the abscissa.
[0073] c: Substitute the fluorescence intensity from step (1) into the normalized curve to calculate the concentration of methylene blue dye in the mixed solution.
[0074] Example 5
[0075] The method for preparing graphene quantum dots in this embodiment specifically includes the following steps:
[0076] a: Dissolve 0.59 g of 1-amino-2-naphthol-4-sulfonic acid and 11.8 mL of acrylic acid in 50 mL of deionized water, shake the mixture by ultrasonication, and mix thoroughly to obtain a mixed solution;
[0077] b: The mixed solution was transferred to a 100 mL polytetrafluoroethylene stainless steel reactor and subjected to hydrothermal reaction under closed conditions at a temperature of 120°C for 24 h.
[0078] c) After the reaction is completed, the mixture is cooled to room temperature and filtered through a 220 nm microporous membrane to obtain the reaction solution;
[0079] d: The reaction solution was placed in a dialysis bag for dialysis. The dialysis bag was dialyzed with ultrapure water for 36 h until the ultrapure water became clear. The solution in the dialysis bag was the y-GQDs solution.
[0080] The prepared y-GQDs were used to detect methylene blue dye. The linear relationship between fluorescence intensity and different concentrations of methylene blue dye was tested, which specifically included the following steps:
[0081] a: 500 μL of y-GQDs solution was mixed with 500 μL of methylene blue dye at different concentrations to a constant volume. The concentrations of methylene blue dye were 0 μM, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.5 μM, and 2 μM, respectively. Fluorescence measurements were performed on the different mixed solutions, and the fluorescence spectra at the maximum fluorescence intensity of the methylene blue dye at different concentrations were plotted.
[0082] b: According to the maximum fluorescence intensity value of each fluorescence spectrum in step b, the linear relationship diagram of y-GQDs fluorescence intensity and different concentrations of methylene blue dye is obtained with the normalized maximum intensity as the ordinate and the methylene blue dye concentration as the abscissa;
[0083] c: Based on the fluorescence intensity of step (1), the normalized curve is used to calculate the concentration of methylene blue dye in the mixed solution.
[0084] Example 6
[0085] The method for preparing graphene quantum dots in this embodiment specifically includes the following steps:
[0086] a: Dissolve 0.59 g of 1-amino-2-naphthol-4-sulfonic acid and 3 mL of acrylic acid in 45 mL of deionized water, shaken by ultrasound, and thoroughly mixed to obtain a mixed solution;
[0087] b: The mixed solution was transferred to a 100 mL polytetrafluoroethylene stainless steel reactor and subjected to hydrothermal reaction under closed conditions at a temperature of 150°C and a reaction time of 18 h.
[0088] c) After the reaction is completed, the mixture is cooled to room temperature and filtered through a 220 nm microporous membrane to obtain the reaction solution;
[0089] d: The reaction solution was placed in a dialysis bag for dialysis. The dialysis bag was dialyzed with ultrapure water for 48 h until the ultrapure water became clear. The solution in the dialysis bag was the y-GQDs solution.
[0090] The prepared y-GQDs were used to detect methylene blue dye. The linear relationship between fluorescence intensity and different concentrations of methylene blue dye was tested, which specifically included the following steps:
[0091] a: 500 μL of y-GQDs solution was mixed with 500 μL of methylene blue dye at different concentrations to a constant volume. The concentrations of methylene blue dye were 0 μM, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.5 μM, and 2 μM, respectively. Fluorescence measurements were performed on the different mixed solutions, and the fluorescence spectra at the maximum fluorescence intensity of the methylene blue dye at different concentrations were plotted.
[0092] b: According to the maximum fluorescence intensity value of each fluorescence spectrum in step a, the linear relationship diagram between the fluorescence intensity of y-GQDs and different concentrations of methylene blue dye is obtained with the normalized maximum intensity as the ordinate and the methylene blue dye concentration as the abscissa.
[0093] c: The fluorescence intensity from step (1) was normalized into the curve.
[0094] Example 7
[0095] The method for preparing graphene quantum dots in this embodiment specifically includes the following steps:
[0096] a: Dissolve 0.6 g of 1-amino-2-naphthol-4-sulfonic acid and 8 mL of acrylic acid in 40 mL of deionized water, shake the mixture by ultrasonication, and mix thoroughly to obtain a mixed solution;
[0097] b: The mixed solution was transferred to a 100 mL polytetrafluoroethylene stainless steel reactor and subjected to hydrothermal reaction under closed conditions at a temperature of 200°C and a reaction time of 18 h;
[0098] c) After the reaction is completed, the mixture is cooled to room temperature and filtered through a 220 nm microporous membrane to obtain the reaction solution;
[0099] d: The reaction solution was placed in a dialysis bag for dialysis. The dialysis bag was dialyzed with ultrapure water for 24 h until the ultrapure water became clear. The solution in the dialysis bag was the y-GQDs solution.
[0100] The prepared y-GQDs were used to detect methylene blue dye. The linear relationship between fluorescence intensity and different concentrations of methylene blue dye was tested, which specifically included the following steps:
[0101] a: 500 μL of y-GQDs solution was mixed with 500 μL of methylene blue dye at different concentrations to a constant volume. The concentrations of methylene blue dye were 0 μM, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.5 μM, and 2 μM, respectively. Fluorescence measurements were performed on the different mixed solutions, and the fluorescence spectra at the maximum fluorescence intensity of the methylene blue dye at different concentrations were plotted.
[0102] b: According to the maximum fluorescence intensity value of each fluorescence spectrum in step a, the linear relationship diagram between the fluorescence intensity of y-GQDs and different concentrations of methylene blue dye is obtained with the normalized maximum intensity as the ordinate and the methylene blue dye concentration as the abscissa.
[0103] c: The fluorescence intensity from step (1) was normalized into the curve.
[0104] 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 principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. Application of graphene quantum dots in the detection of methylene blue dye based on electron absorption and donation, characterized by: The preparation steps of graphene quantum dots based on electron absorption and supply control are as follows: A mixed aqueous solution of 1-amino-2-naphthol-4-sulfonic acid and acrylic acid is subjected to a hydrothermal reaction, cooled, and then filtered to prepare graphene quantum dots; The mass volume ratio of the 1-amino-2-naphthol-4-sulfonic acid, acrylic acid and water is 1g:5-20ml:70-100ml; The temperature of the hydrothermal reaction is 120-230° C., and the time is 6-24 h.
2. The method of claim 1, wherein the method comprises the following steps: The filtration is performed sequentially using a filter membrane and dialysis filtration, wherein the pore size of the filter membrane filtration is not greater than 220 nm; the dialysis is performed using ultrapure water until the ultrapure water becomes clear, and the dialysis time is 24-48 h. The solution in the dialysis bag is the graphene quantum dot solution.
3. The method of claim 2, wherein the graphene quantum dots are used to detect methylene blue dyes by electron absorption and supply. The application comprises the following steps: 1) Adding graphene quantum dots regulated by electron absorption and donation to a sample containing methylene blue dye to measure the fluorescence intensity of the sample; 2) Substituting the fluorescence intensity measured in step 1) into the linear equation of the fluorescence intensity of the graphene quantum dots and different concentrations of methylene blue dye, the concentration of the methylene blue dye in the sample to be tested is calculated.
4. The method of claim 3, wherein the graphene quantum dots are used to detect methylene blue dyes by electron absorption and supply control. The fluorescence intensity test adopts the maximum excitation wavelength of 370 nm for excitation, and the fluorescence intensity is the fluorescence intensity at the maximum emission wavelength of 500 nm.
5. The method of claim 4, wherein the graphene quantum dots are used to detect methylene blue dyes based on electron absorption and supply. The linear equation described in step 2) is y=3323.23963-501.01717x, where x is the concentration of methylene blue dye in μmol / L, and y is the fluorescence intensity in au.