Preparation method and application of fluorescent carbon dots

Abstract

The present invention relates to a method for preparing fluorescent carbon dots and their application, belonging to the field of new materials. The present invention provides a method for synthesizing fluorescent carbon dots in one step by microwave method using the Chinese medicinal material Aucklandia lappa as a carbon source. The method is simple, economical, and environmentally friendly. The prepared fluorescent carbon dots have excellent fluorescence properties, with a maximum excitation wavelength of 360 nm and a maximum emission wavelength of 465 nm. The present invention uses fluorescent carbon dots to develop a new type of fluorescent chemical sensor for rapid, highly sensitive, and highly selective detection of Fe 3+ The linear range is 0.2-200 μmol / L, and the detection limit is as low as 62 nmol / L. This method shows good recovery and reproducibility in actual water sample detection, which is a good indicator of Fe 3+ The detection of β-catenin provides a simple and efficient new approach with broad application prospects.

Description

Technical Field

[0001] The invention belongs to the field of new materials and relates to a preparation method of fluorescent carbon dots and applications thereof. Background Art

[0002] Metal ions are particularly important in our daily lives. 3+ It is one of the most important trace elements for animals, plants and humans. It plays an important role in the storage and transportation of oxygen to form human hemoglobin, signal transduction, catalysis and enzyme metabolism. Insufficient or excessive intake can lead to various problems such as liver damage, decreased immunity and hemochromatosis. 3+ Abnormal range of Fe is also one of the factors affecting many diseases such as anemia and Alzheimer's disease. 3+ It is closely related to the metabolic and photosynthetic processes of phytoplankton in aquatic environments, such as nitrate reduction, nitrogen fixation, and respiratory function. The World Health Organization (WHO) recommends that Fe 3+ The content of Fe should be lower than 0.3 mg / L, otherwise it will be considered as a toxic metal. 3+ Sensitive and selective detection methods are crucial. 3+ Research reports on detection methods include electrochemical methods, voltammetry, inductively coupled plasma mass spectrometry, chromatography, colorimetry, and atomic absorption spectrometry. However, these methods have the disadvantages of expensive instruments and equipment, cumbersome operating procedures, and high costs. Therefore, it is necessary to develop a fast, convenient, highly sensitive, and highly selective Fe 3+ The detection method is of great significance.

[0003] Nanomaterials are materials that are nanoscale (1-100 nm) in at least one dimension, or materials composed of nanoscale units. Among these materials, carbon dots (CDs) have attracted widespread attention due to their facile synthesis, low cost, tunable surface functionalization, outstanding photostability, good biocompatibility, favorable hydrophilicity, and environmental friendliness. These exceptional properties have led to their widespread application in diverse fields such as cell imaging, energy storage, heavy metal ion sensing, biomolecules, targeted drug delivery, solar cells, and photocatalysis. To date, the synthesis of CDs has primarily involved two approaches: "top-down" and "bottom-up." The "top-down" synthetic strategy involves physical or chemical exfoliation from larger carbon sources to obtain CDs. The "bottom-up" synthetic technique utilizes small carbon sources to prepare CDs. Many previous studies have used chemical reagents to synthesize CDs, which can lead to environmental pollution and thus limit their practical applications. To date, various natural plants have been used to prepare CDs. However, their low fluorescence quantum yield (QY) has hindered their application in biological systems. Therefore, a facile, rapid, and environmentally friendly strategy to synthesize high quantum yield carbon dots is a key factor for their practical application. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing fluorescent carbon dots and its application, especially Fe 3+ Application in detection.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing fluorescent carbon dots, which comprises the following steps:

[0007] S1: Dry the Chinese medicinal material Costus lappa at a high temperature, then crush and sieve;

[0008] S2: Aucklandia lappa powder was mixed with ultrapure water, dispersed in a flask, and sonicated;

[0009] S3: placing the solution in a microwave reactor, heating the solution with microwaves, filtering the solution with a filter membrane, dialyzing the solution with a dialysis bag, and drying the solution to prepare the fluorescent carbon dots;

[0010] The mass volume ratio of the Sichuan costus root powder to ultrapure water is 1-3:30 (g:mL);

[0011] The power of the microwave reactor is 600-1000W, and the microwave heating reaction is 6-10 minutes;

[0012] The pore size of the filter membrane is 0.22 μm, the molecular weight cut-off of the dialysis bag is 1000 Da, and the dialysis time is 48-72 h;

[0013] The fluorescent carbon dots prepared by the method have a particle size of 4 to 8 nm;

[0014] The maximum excitation wavelength of the fluorescent carbon dots is 360 nm, and the maximum emission wavelength is 465 nm;

[0015] The fluorescent carbon dots are used to detect Fe 3+ Application in

[0016] Fluorescent carbon dots for Fe detection 3+ The method is characterized in that:

[0017] S1: Add the fluorescent carbon dots to the 3+ The fluorescence quenching reaction was carried out in a phosphate buffer solution with a concentration of 100 μg / min. 3+ The linear relationship between the concentrations of

[0018] S2: Add fluorescent carbon dots to the Fe 3+ Perform fluorescence quenching reaction in the test environmental water body in phosphate buffer to obtain fluorescence intensity;

[0019] S3: Calculate the Fe content in the environmental water to be tested through the standard curve 3+ concentration.

[0020] The beneficial effects of the present invention are:

[0021] In the present invention, the traditional Chinese medicine Aucklandia lappa is used as the carbon source, and a simple, economical and environmentally friendly synthesis method is adopted to synthesize carbon dots through a one-step microwave reaction. The maximum excitation and emission wavelengths of the carbon dots are located at 360nm and 465nm respectively. 3+ When introduced into the carbon dot solution, the fluorescence intensity of the carbon dots was quenched, and a "closed-type" fluorescent chemical sensor was successfully established based on the carbon dots. The obtained fluorescent sensor showed simplicity, sensitivity and high selectivity. As an effective Fe 3+ Fluorescence sensor, carbon dots in detecting Fe 3+ The carbon dots showed excellent performance with a linear range of 0.2-200 μmol / L and a detection limit of 62 nmol / L (3σ / k). 3+ The spiked recoveries were 99.2% to 101.6%, and the relative standard deviations were 1.2% to 2.7%.

[0022] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0024] Figure 1 Synthesis process of carbon dots from Sichuan costus root and detection of Fe 3+ Schematic diagram of the principle;

[0025] Figure 2 Transmission electron microscopy (TEM) image of carbon dots (A); histogram of carbon dot size distribution (B); X-ray photoelectron spectroscopy (XPS) of carbon dots (C); high-resolution C1s spectrum of carbon dots XPS (D); emission spectrum of carbon dots (E); carbon dots and Fe 3+ Absorption spectrum and carbon dot fluorescence spectrum (FS) diagram (F);

[0026] Figure 3 For different concentrations of Fe 3+ Fluorescence quenching of carbon dots;

[0027] Figure 4 The effect of pH value. I0 (black curve) and I (red curve) represent the pH value in the absence of Fe 3+ and Fe 3+ The fluorescence intensity of carbon dots in the presence of Fe; (I0-I) / I0 (blue curve) indicates the fluorescence intensity of carbon dots in the presence of Fe 3+ The quenching efficiency after c(CDs):20mg / L; c(Fe 3+ ):20μmol / L; pH value: 4.4, 5.8, 6.2, 6.6, 7.0, 7.4, 8.0, 9.3;

[0028] Figure 5 is the effect of reaction time. I0 (black curve) and I (red curve) represent the reaction time in the absence of Fe 3+ and Fe 3+ The fluorescence intensity of carbon dots in the presence of Fe; (I0-I) / I0 (blue curve) indicates the fluorescence intensity of carbon dots in the presence of Fe 3+ The quenching efficiency after c(CDs):20mg / L; c(Fe 3+ ):20μmol / L; pH value: 6.2.

[0029] Figure 6 (A) Different concentrations of Fe 3+ Fluorescence emission spectra of carbon dots. (B) Standard curve. I0 and I represent the fluorescence emission spectra of carbon dots in the absence of Fe. 3+ and Fe 3+ Fluorescence intensity of carbon dots in the presence of; c(CDs): 20 mg / L; 0.1 mol / L phosphate buffer, pH 6.2.

[0030] Figure 7 Fe detection for carbon dots 3+ Selectivity with other anions or metal ions. 3+ The concentration of anions or other metal ions was 20 μmol / L. 0.1 mol / L phosphate buffer pH 6.2; excitation wavelength: 360 nm; c(CDs): 20 mg / L; I0 and I represent the concentration of Fe 3+ and Fe 3+ The fluorescence intensity of carbon dots when Fe is present; (I0-I) / I0 represents the fluorescence intensity of carbon dots when Fe is added. 3+ All histograms represent the (I0-I) / I0 of the system in the presence of anions or other metal ions. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0032] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0033] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0034] Example 1 Preparation of fluorescent carbon dots

[0035] 1. Instruments and Reagents

[0036] Fluorescence spectra were recorded using a Hitachi F-2700FL fluorescence spectrophotometer (Japan). The size and morphology of the carbon dots were analyzed using a TECNAI 10 transmission electron microscope (The Netherlands). UV-visible absorption spectra were acquired using a Hitachi U-2550 spectrophotometer (Japan). X-ray photoelectron spectroscopy (XPS) of the carbon dots was collected on a ThermoEscalab 250Xi X-ray photoelectron spectrometer (USA).

[0037] Costus root, a traditional Chinese medicinal material, was purchased from Sichuan Longsen Chinese Medicine Co., Ltd. FeCl₃, NaF, NaCl, KBr, KI, Na₂CO₃, Na₂SO₄, AgNO₃, BaCl₂, ZnCl₂, CoCl₂, NiCl₂, MgCl₂, MnCl₂, Pb(NO₃)₂, and CuCl₂ were provided by Shanghai Sinopharm Chemical Reagent Co., Ltd. All chemicals used were of analytical grade and used directly without further purification. 0.1 mol / L phosphate buffer solutions of varying pH were prepared using stock standard solutions of 0.2 mol / L NaH₂PO₄ and 0.2 mol / L Na₂HPO₄ in varying proportions.

[0038] 2. Preparation of Fluorescent Carbon Dots

[0039] Fluorescent carbon dots (Cdots) were synthesized in a single step using a microwave method using the traditional Chinese medicinal herb Costus lappa as a carbon source. Costus lappa was oven-dried at 105°C and then pulverized through a 20-mesh sieve. 1.00 g of Costus lappa powder was weighed and dispersed in 30 mL of ultrapure water in a 100 mL round-bottom flask. After sonication for 10 minutes, the mixture was placed in a microwave reactor. The microwave reactor power was adjusted to 1000 W and microwave heating was performed for 6 minutes. The Cdots were successfully synthesized when the solution changed from light yellow to dark brown. After the reaction was complete, the mixture was cooled to room temperature and centrifuged at 10,000 rpm for 15 minutes to remove large particles. The supernatant was filtered through a 0.22 μm filter membrane. The filtrate was collected and dialyzed using a 1000 Da dialysis bag for 72 hours to obtain a light yellow fluorescent Cdot dispersion. The light yellow fluorescent Cdot solution was then vacuum dried for 24 hours to obtain yellow fluorescent Cdots. Finally, the carbon dots were dispersed in double distilled water to obtain a 0.4 g / L dispersion, which was stored in a refrigerator at 4°C for later use.

[0040] Example 2 Preparation of fluorescent carbon dots

[0041] Fluorescent carbon dots (Cdots) were synthesized in a single step using a microwave method using the traditional Chinese medicinal material Costus lappa as a carbon source. Costus lappa was dried at 80°C and then pulverized through a 60-mesh sieve. 2.00 g of Costus lappa powder was weighed and dispersed in 30 mL of ultrapure water in a 100 mL round-bottom flask. After sonication for 10 minutes, the mixture was placed in a microwave reactor. The microwave reactor power was adjusted to 600 W and microwave heating was performed for 10 minutes. The Cdots were successfully synthesized when the solution changed from light yellow to dark brown. After the reaction was complete, the mixture was cooled to room temperature and centrifuged at 10,000 rpm for 15 minutes to remove large particles. The supernatant was filtered through a 0.22 μm filter membrane. The filtrate was collected and dialyzed using a 1000 Da dialysis bag for 60 hours to obtain a light yellow fluorescent Cdot dispersion. The light yellow fluorescent Cdot solution was then vacuum dried for 24 hours to obtain yellow fluorescent Cdots. Finally, the carbon dots were dispersed in double distilled water to obtain a 0.4 g / L dispersion, which was stored in a refrigerator at 4°C for later use.

[0042] Example 3 Preparation of fluorescent carbon dots

[0043] Fluorescent carbon dots (Cdots) were synthesized in a single step using a microwave method using the traditional Chinese medicinal material Costus lappa as a carbon source. Costus lappa was dried at 40°C and then pulverized through a 100-mesh sieve. 3.00 g of Costus lappa powder was weighed and dispersed in 30 mL of ultrapure water in a 100 mL round-bottom flask. After sonication for 10 minutes, the mixture was placed in a microwave reactor. The microwave reactor power was adjusted to 800 W and microwave heating was performed for 8 minutes. The Cdots were successfully synthesized when the solution changed from light yellow to dark brown. After the reaction was complete, the mixture was cooled to room temperature and centrifuged at 10,000 rpm for 15 minutes to remove large particles. The supernatant was filtered through a 0.22 μm filter membrane. The filtrate was collected and dialyzed using a 1000 Da dialysis bag for 48 hours to obtain a light yellow fluorescent Cdot dispersion. The light yellow fluorescent Cdot solution was then vacuum dried for 24 hours to obtain yellow fluorescent Cdots. Finally, the carbon dots were dispersed in double distilled water to obtain a 0.4 g / L dispersion, which was stored in a refrigerator at 4°C for later use.

[0044] Example 4 Characterization of Fluorescent Carbon Dots

[0045] The structure and properties of the prepared carbon dots were characterized by fluorescence spectroscopy (FS), transmission electron microscopy (TEM), ultraviolet-visible absorption spectroscopy (UV-Vis) and X-ray photoelectron spectroscopy (XPS). Figure 2 (A) Transmission electron microscopy (TEM) images show that the carbon dots prepared from Sichuan woodruff are spherical or quasi-spherical, with uniform particles, good dispersion, and no agglomeration. Figure 2 (B) shows the carbon dot particle size distribution histogram. According to the statistics of 50 carbon dot particles, the carbon dot particle size is mainly distributed in the range of 4 to 8 nm, with an average particle size of 5.9 nm. Figure 2From the X-ray photoelectron spectroscopy (XPS) image of carbon dots (C), it can be seen that characteristic peaks appear at 284.8eV and 532.5eV, indicating that the carbon dots mainly contain C and O elements. Figure 2 From the high-resolution C1s spectrum of the carbon dots in (D), it can be seen that the absorption peak of C1 is located at 284.74 eV, accounting for 48.79%, the absorption peak of C2 is located at 286.22 eV, accounting for 38.91%, the absorption peak of C3 is located at 287.75 eV, accounting for 10.54%, and the absorption peak of C4 is located at 288.86 eV, accounting for 1.76%. It can be seen that the surface of the carbon dots is rich in O functional groups. Figure 2 (E) is the emission spectrum of carbon dots at an excitation wavelength of 320nm to 390nm, with the maximum excitation wavelength at 360nm. Figure 2 (F) It can be seen that at the carbon dot concentration of 20 mg / L and Fe 3+ When tested at a concentration of 100 μmol / L, the emission peak of carbon dots was located at 465 nm under the maximum excitation wavelength. 3+ The characteristic absorption peaks of the carbon dots appear at 280nm and 290nm respectively. Taking quinine sulfate as the standard substance (fluorescence quantum yield is 54%), the fluorescence quantum yield of the carbon dots is 15%.

[0046] Example 5 Application of fluorescent carbon dots

[0047] 1. Carbon dot detection of Fe 3+ Feasibility analysis

[0048] By adding different concentrations of Fe to the carbon dot solution with a concentration of 20 mg / L 3+ , studied the use of carbon dots to detect Fe 3 + feasibility, such as Figure 3 When Fe is added 3+ The fluorescence intensity of carbon dots decreases rapidly. 3+ When the concentration of Fe is 2μmol / L, 20μmol / L and 200μmol / L, the quenching efficiency is 17.6%, 66.4% and 93.6% respectively. 3+ concentration, which shows that carbon dots can be used to detect Fe 3+ Feasibility characteristics.

[0049] 2. Optimization of pH conditions

[0050] To get better Fe 3+ Detection sensitivity, the detection conditions such as pH value were optimized, such as Figure 4As shown. The effect of pH value of phosphate buffer solution on fluorescence quenching efficiency was studied in the range of 4.4-9.3. It was found that (I0-I) / I0 increased slightly from pH 4.4 to pH 6.2 and then decreased. I0 and I represent the addition of Fe 3+ Fluorescence intensity of carbon dots before and after addition; (I0-I) / I0 represents the fluorescence intensity of carbon dots after addition of Fe 3+ Based on the above experimental results, pH 6.2 was finally used as the quenching efficiency for Fe 3+ The optimal pH value.

[0051] 3. Optimization of reaction time conditions

[0052] In addition, the effect of reaction time on detection was studied with a time span of 60 min, e.g. Figure 5 It is clearly seen that the fluorescence intensity of carbon dots remains stable even after 60 min, which indicates that carbon dots have excellent fluorescence stability. 3+ After the addition of Fe, the fluorescence intensity of the carbon dots decreased immediately, and the fluorescence quenching efficiency reached its maximum when the reaction time was 2 min. In general, the quenching efficiency remained stable from 2 min to 60 min. 3+ After that, select Fe 3+ Perform quantitative detection.

[0053] 4.Fe 3+ Quantitative analysis

[0054] Under the optimal conditions obtained in the above study, as Fe 3+ With the increase of concentration, the fluorescence intensity of carbon dots gradually decreases ( Figure 6 A). Figure 6 B shows the relationship with Fe 3+ The concentration has a good linear correlation in the range of 0.20-200 μmol / L. The linear equation can be expressed as (I0-I) / I=0.0872x+0.0672, with a correlation coefficient of 0.9992, where I0-I is the concentration in the absence of Fe 3+ (I0) and Fe 3+ The fluorescence intensity difference of (I) in the presence of Fe 3+ The concentration of Fe 3+ The detection limit of Fe was 62 nmol / L (3σ / k), which is consistent with other literature reports on the detection of Fe 3+ Compared with the method (as shown in Table 1), this Fe 3+ The sensor has a good detection range and a low detection limit.

[0055] Table 1 Different Fe 3+ Comparison of detection methods

[0056]

[0057] 5. Carbon dots on Fe 3+ Selectivity of detection

[0058] As we all know, the selectivity of the proposed sensor is also very important in the actual sample analysis. Since there are multiple ions in the actual sample, these ions may also cause the fluorescence intensity of the carbon dots to decrease, thereby affecting the Fe 3+ To explore the effects of possible interfering species, several anions, such as F - 、Cl - Br - , I - 、CO3 2- 、SO4 2- and some metal ions, including Ag + 、Ba 2+ 、Zn 2+ 、Co 2+ 、Ni 2+ Mg 2+ 、Mn 2+ , Pb 2+ 、Cu 2+ , and the fluorescence spectrum was measured under 360nm excitation. Figure 7 As shown in Figure 3, it is clearly revealed that anions have no significant effect on the measurement. In addition, in the presence of carbon dots, the quenching efficiency of metal ions is almost less than 10%. Therefore, this method is effective for Fe 3+ The determination showed high selectivity.

[0059] 6. Interference Experiment

[0060] In order to explore the effects of other metal cations and anions on Fe 3+ Detect interference, keep Fe 3+ The concentration of F was constant at 20 μmol / L, while - 、Ag + 、Ba 2+ 、Zn 2+ The concentration of Br is 400 μmol / L; - 、CO3 2- 、Co 2+ 、Ni 2+ Mg 2+ The concentration of I-, SO4 is 800μmol / L; 2 -、Mn 2+ , Pb 2+ 、Cu 2+The concentrations of 100 μmol / L and 1200 μmol / L, respectively. As shown in Table 2, the quenching efficiency (I0-I) / I0 is still close to 66.4%, and the relative standard deviation (RSD) is 0.6%-2.5%. Obviously, the coexistence of other metal cations and anions does not interfere with the carbon dots' quenching of Fe. 3+ Detection.

[0061] Table 2 Interference experiments at different concentrations

[0062]

[0063] 7.Fe 3+ Detection

[0064] Take 1 mL of 0.1 mol / L phosphate buffer (pH 6.2) and 200 μL of 0.4 g / L carbon dot solution, add appropriate amount of Fe 3+ The standard solution or sample solution was prepared and supplemented with double distilled water to a total volume of 4.0 mL. The mixed solution was thoroughly vortexed and allowed to react at room temperature for 2 min. The photomultiplier tube voltage of the fluorescence spectrophotometer was set to 400 V and the slit width to 5 nm. The fluorescence intensity was measured at room temperature and an excitation wavelength of 360 nm (the average of three measurements was taken). The Fe 3+ Content detection and analysis.

[0065] 8. Fe in actual water samples 3+ Detection

[0066] Actual water samples were collected from local steel plant wastewater, rivers, and pharmaceutical wastewater and ultrafiltered using a 10KD ultrafiltration membrane. 1 mL of actual water sample, 1 mL of 0.1 mol / L phosphate buffer (pH 6.2), and 200 μL of 0.4 g / L carbon dot solution were added to a test tube, and the final volume of the mixture was adjusted to 4.0 mL with double distilled water. The mixture was vortexed and reacted at room temperature for 2 minutes. 3+ The content was determined at an excitation wavelength of 360 nm. In order to obtain a satisfactory recovery rate, a recovery experiment was also carried out.

[0067] Practical application performance of carbon dots in detecting Fe in steel plant wastewater, rivers and pharmaceutical wastewater 3+ First, Fe 3+ Then 5μmol / L, 20μmol / L and 50μmol / L of Fe were added to the actual water samples respectively. 3+ The results are shown in Table 3. The recovery rates were 99.2% to 101.6% and the relative standard deviations (RSDs) were 1.2% to 2.7%. These results indicate that carbon dots can be used for Fe 3+The effectiveness of the test.

[0068] Table 3 Fe in wastewater from steel plants, rivers and pharmaceutical plants 3+ The measurement results.

[0069]

[0070] Using the traditional Chinese medicine Aucklandia lappa as the carbon source, carbon dots were prepared by microwave method, and a new type of fluorescence sensor was developed for the rapid, highly sensitive and highly selective detection of Fe 3+ Based on Fe 3+ The fluorescence quenching effect of carbon dots demonstrates the detection of Fe in aqueous solution. 3+ The linear range is 0.2-200 μmol / L and the detection limit is 62 nmol / L. This provides a simple and efficient method for the synthesis of fluorescent carbon dots and achieves Fe 3+ The established method was validated with three real water samples and achieved satisfactory recoveries. Kawana woodruff carbon dots have many advantages, such as low cost, environmental friendliness, and excellent chemical and optical stability, which provide a potential avenue for the application of carbon dots in chemical sensing and environmental applications.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. Fluorescent carbon dots in detecting Fe 3+ The application is characterized in that The preparation method of the fluorescent carbon dots comprises the following steps: S1: Dry the Chinese medicinal material Costus lappa at a high temperature, then crush and sieve; S2: Aucklandia lappa powder was mixed with ultrapure water, dispersed in a flask, and sonicated; S3: placing the solution in a microwave reactor, heating the solution with microwaves, filtering the solution with a filter membrane, dialyzing the solution with a dialysis bag, and drying the solution to prepare the fluorescent carbon dots; The mass volume ratio of Sichuan costus root powder to ultrapure water is 1-3g:30mL; The microwave reactor power is 600-1000W, and the microwave heating reaction is 6-10 min; The pore size of the filter membrane is 0.22 μm, the molecular weight cut-off of the dialysis bag for collection is 1000 Da, and the dialysis time is 48-72 h.

2. Detection of Fe by Fluorescent Carbon Dots 3+ The method is characterized in that The steps are as follows: S1: Dry the Chinese medicinal material Costus lappa at a high temperature, then crush and sieve; S2: Aucklandia lappa powder was mixed with ultrapure water, dispersed in a flask, and sonicated; S3: placing the solution in a microwave reactor, heating the solution with microwaves, filtering the solution with a filter membrane, dialyzing the solution with a dialysis bag, and drying the solution to prepare the fluorescent carbon dots; The mass volume ratio of Sichuan costus root powder to ultrapure water is 1-3:30mL; The microwave reactor power is 600-1000W, and the microwave heating reaction is 6-10 min; The pore size of the filter membrane is 0.22 μm, the molecular weight cut-off of the dialysis bag for collection is 1000 Da, and the dialysis time is 48-72 h; S4: Add the fluorescent carbon dots to the 3+ The fluorescence quenching reaction was carried out in a phosphate buffer solution with a concentration of 100 μg / min. 3+ The linear relationship between the concentrations of S5: Add fluorescent carbon dots to the Fe-containing 3+ Perform fluorescence quenching reaction in the test environmental water body in phosphate buffer to obtain fluorescence intensity; S6: Calculate the Fe content in the environmental water to be tested through the standard curve 3+ concentration.

Images