Preparation of a Novel Boron-Doped Carbon Quantum Dot and Its Application in Detecting Fe 3+ ions

Abstract

The present invention provides a preparation method of a novel boron-doped carbon quantum dot and its application in detecting Fe<supgt;3+< / supgt>. The preparation method of the novel boron-doped carbon quantum dot is as follows: Using tartaric acid, arginine, and boric acid as raw materials, a boron-doped carbon quantum dot with abundant functional groups on its surface is prepared by a hydrothermal synthesis method. This carbon quantum dot can be uniformly dispersed in water and has good fluorescence detection selectivity for Fe<supgt;3+< / supgt>. Compared with existing or identical detection techniques, the carbon quantum dot obtained by the present invention is simple to prepare, has inexpensive raw materials, the synthesis process meets the requirements of green chemistry, is convenient for post-treatment, and is suitable for large-scale production; at the same time, the detection method is simple and fast. This carbon quantum dot can detect trace Fe<supgt;3+< / supgt> ions with high sensitivity and high selectivity in a pure water medium and has application value in many aspects in actual life detection.

Description

Technical Field

[0001] The present invention relates to the technical fields of the preparation of carbon nanomaterials and ion detection. In particular, it relates to the preparation of a novel boron-doped carbon quantum dot and its application in detecting Fe 3+ ions. Background Art

[0002] Iron is one of the indispensable metal ions in biological systems and plays an important role in processes including cell metabolism, enzyme catalysis, oxygen transport, and the synthesis of DNA and RNA. Abnormal changes in iron ion concentration are indicators of the occurrence of various diseases such as anemia, mental decline, heart disease, obesity, etc. Therefore, the detection of iron ion concentration is of great significance for the early diagnosis of these diseases.

[0003] There are many traditional methods for analyzing iron ions, such as atomic absorption spectrometry and inductively coupled plasma mass spectrometry. However, these analytical methods usually require sophisticated and expensive instruments and cumbersome pretreatment, thus affecting their application in practice. Fluorescence sensing technology has become an emerging detection technology due to its high sensitivity and fast detection speed in detecting heavy metal ions. At the same time, fluorescence sensing technology also has the advantages of low cost, easy operation, simplicity, and high selectivity.

[0004] In recent years, fluorescent carbon-based materials have attracted extensive attention, which mainly include carbon quantum dots, graphene quantum dots, fluorescent graphene, nanodiamonds, and fullerenes. As a member of fluorescent carbon-based materials, carbon quantum dots have attracted extensive attention from scientists in photocatalysis, sensors, printing inks, drug delivery, bioimaging, and environmental monitoring due to their good optoelectronic and chemical properties different from metal-based quantum dots. Therefore, it can be considered to use carbon quantum dots to detect Fe. Currently, the preparation of carbon quantum dots is mainly divided into two categories, one is the top-down method, and the other is the bottom-up method, mainly including chemical oxidation method, ultrasonic method, solvothermal method, microwave radiation method, and laser ablation method. However, most of these methods are relatively complex, and the prepared products will also cause a certain degree of pollution to the environment. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide the preparation of a novel boron-doped carbon quantum dot and its application in detecting Fe 3+ ions. The preparation method of this novel boron-doped carbon quantum dot is as follows: Using tartaric acid, arginine, and boric acid as raw materials, a boron-doped carbon quantum dot with rich surface functional groups is prepared by a hydrothermal synthesis method. This carbon quantum dot can be uniformly dispersed in water and is used for Fe 3+It has good fluorescence detection selectivity. Compared with existing or the same detection technologies, the carbon quantum dots obtained by the present invention are simple to prepare, with cheap raw materials, the synthesis process meets the requirements of green chemistry, the post-treatment is convenient, and it is suitable for large-scale production. At the same time, the detection method is simple and fast. The carbon quantum dots can detect trace amounts of Fe with high sensitivity and high selectivity in pure water medium. 3+ ions, and have application value in many aspects of actual life detection.

[0006] To achieve the above object, the following technical solutions are adopted:

[0007] A preparation method of boron-doped carbon quantum dots, comprising the following steps:

[0008] Step S1: Weigh L(+)-tartaric acid, arginine, and boric acid and pour them into a beaker. Add deionized water, stir and dissolve. After complete dissolution, transfer to a reaction kettle.

[0009] Step S2: Place the reaction kettle in step S1 in an oven and react for a certain period of time.

[0010] Step S3: Filter the reaction solution in step S2 with a filter membrane; add acetone, precipitate, and then centrifuge the obtained solution in a centrifuge to obtain the boron-doped carbon quantum dots, and store the carbon quantum dots for later use.

[0011] Further, the molar ratio of L(+)-tartaric acid, arginine, and boric acid in step S1 is 9.2 mmol: 4.6 mmol: 12.9 mmol.

[0012] Further, the oven temperature in step S2 is 180 °C and the reaction is for 10 h.

[0013] Further, the pore size of the filter membrane in step S3 is 0.2 μm.

[0014] Further, the centrifuge speed in step S3 is 11000 r / m and the centrifugation is for 10 min.

[0015] Further, the synthesized carbon quantum dots in step S3 are stored at 4 °C for later use.

[0016] A boron-doped carbon quantum dot prepared by the above method.

[0017] An application of a boron-doped carbon quantum dot in detecting Fe 3+ ions, comprising the following steps:

[0018] Step K1: Take n sample bottles, and add untreated household water to each sample bottle.

[0019] Step K2: Add boron-doped carbon quantum dots into each sample bottle respectively, and then add ferric dichloride solution into each sample bottle respectively to prepare mixed solutions with different molar concentrations of iron ions. After standing at room temperature, with an excitation wavelength of 330 nm, measure the fluorescence emission spectrum change diagram of each sample respectively;

[0020] Step K3: Make a fitting curve of the corresponding fluorescence intensity versus iron ion concentration according to the change of fluorescence intensity in the fluorescence emission spectrum change diagram of each sample;

[0021] Step K4: Substitute the fluorescence intensity value of the sample to be detected into the fitting curve equation in Step K3 to obtain the Fe 3+ concentration in the sample to be detected.

[0022] Furthermore, when the untreated domestic water is 3 mL, the addition amount of boron-doped carbon quantum dots is 60 μL.

[0023] Furthermore, the standing time at room temperature is 3 min.

[0024] This carbon quantum dot can be evenly dispersed in water and has good fluorescence detection selectivity for Fe 3+ ions.

[0025] Beneficial effects:

[0026] The beneficial effects of the present invention are as follows:

[0027] (1) According to the fitting equation, the detection limit of this carbon quantum dot sensor for iron ions is 5.36×10 -10 M. The concentration of iron ions in domestic water stipulated in China shall not exceed 3 mg / L. The normal values of serum iron in the human body are 13.43 - 31.34 μmol / L for men and 10.74 - 30.98 μmol / L for women. These contents are all higher than the detection limit of this carbon quantum dot for detecting iron ions. Therefore, this carbon quantum dot is expected to be applied to the detection of iron ions in domestic water and in the human body.

[0028] (2) Compared with the existing detection technologies, the synthesis route of the carbon quantum dots in the present invention is very simple, the synthesis method is green and environmentally friendly, and the post-treatment is convenient; the detection method is simple and fast, with strong selectivity for Fe 3+ ions, high detection sensitivity, not affected by other ions, and can directly perform high-sensitivity and specific recognition on Fe 3+ ions in domestic water, and is suitable for large-scale synthesis and practical production applications. Description of the drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0030] Figure 1 XRD diffraction pattern of the carbon quantum dot powder prepared in the embodiment of the present application;

[0031] Figure 2 Transmission electron microscope image of the carbon quantum dots prepared in the embodiment of the present application;

[0032] Figure 3 Fourier transform infrared spectrum of the carbon quantum dots prepared in the embodiment of the present application;

[0033] Figure 4 Fluorescence emission spectrum change diagram at different iron ion concentrations in the embodiment of the present application;

[0034] Figure 5 For Fe in the embodiment of the present application 3+ Standard curve graph of the titration of the solution;

[0035] Figure 6 Selective quenching detection of metal ions on B-CDs in the embodiment of the present application;

[0036] Figure 7 For other metal ions on Fe in the embodiment of the present application 3+ Interference test graph of ions;

[0037] Figure 8 Fluorescence detection of actual samples in the embodiment of the present application. Specific embodiments

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further details the present invention in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] Example 1

[0040] The synthesis method of carbon quantum dots includes the following steps:

[0041] (1) Weigh 2.762 g of L(+) tartaric acid, 1.6 g of arginine, and 1.6 g of boric acid, pour them into a beaker, add 25 ml of deionized water, stir to dissolve, and after complete dissolution, transfer to a 50 ml reaction kettle

[0042] (2) Place the above-treated reaction kettle in an oven and set it at 180 °C for 10 h;

[0043] (3) Filter the above reaction solution through a 0.2 μm filter membrane; add acetone to precipitate, and then centrifuge the obtained solution in a centrifuge at a speed of 11000 r / m for 10 min. Store the synthesized carbon quantum dots at 4 °C for later use.

[0044] Figure 1 XRD diffraction pattern of the prepared carbon quantum dot powder; it can be seen from the figure that there is an obvious broad absorption peak at around 2θ = 22°, indicating that the carbon dots have an amorphous carbon structure.

[0045] Figure 2 This is the transmission electron microscope image of the prepared carbon quantum dots; after statistical calculation, the particle size of the carbon quantum dots is about 5 nm.

[0046] Figure 3 This is the Fourier transform infrared spectrum of the prepared carbon quantum dots; an O-H stretching vibration peak can be observed at 3186 cm -1 , and the signal peaks at 1744 cm -1 and 1667 cm -1 are the stretching vibrations of carboxyl (C=O) and vinyl (C=C) respectively. The stretching vibration peak at 1292 cm -1 is -NO2, and the signal peak at 1092 cm -1 is B-O, and the signal peak at 950 cm -1 is B-C. The infrared spectrum of B-CQDs indicates that the surface of the carbon quantum dots contains hydrophilic groups such as hydroxyl and carboxyl, making B-CQDs have good water solubility.

[0047] The method for detecting Fe 3+ using the prepared carbon quantum dots includes the following steps:

[0048] (1) Take 34 5-mL sample bottles, and add 3 mL of untreated household water to each sample bottle;

[0049] (2) Add 60 μL of the carbon quantum dots prepared in Claim 1 to each sample bottle, and then add ferric chloride solution respectively to prepare solutions with iron ion molar concentrations of 0, 0.01x10 -6 ,

[0050] 0.02x10 -6 , 0.03x10 -6 , 0.04x10 -6 , 0.05x10 -6 …0.1x10 -6 , 0.11x10 -6, 0.12x10 -6 …0.2x10 -6 , 0.21x10 -6 , 0.22x10 -6 …0.3x10 -6 , 0.33x10 -6 , 0.36x10 -6 , 0.39x10 -6 of the mixed solution. After standing at room temperature for 3 min, with 330 nm as the excitation wavelength, the fluorescence emission spectra change diagrams of 34 samples were measured respectively. As Figure 4 shown, the measurement results show that the fluorescence intensity of the carbon quantum dots gradually decreases with the increase of the iron ion concentration;

[0051] (3) According to the change of fluorescence intensity, a fitting curve of the fluorescence intensity vs. the iron ion concentration can be made. As Figure 5 described, the function corresponding to this curve is:

[0052] Y = -85344x + 996.74, R 2 = 0.9862, and the linear range is 0.01 - 0.05 M;;

[0053] According to this equation, the detection limit of the carbon quantum dots for Fe 3+ is 1.527×3 / 8534 = 5.36×10 - 10 M;

[0054] (4) Substitute the luminescence intensity value of the sample to be detected under the excitation wavelength of 330 nm into the above linear equation to obtain the Fe 3+ concentration in the sample to be detected.

[0055] Take 16 5-mL sample bottles, add 3 mL of untreated household water to each of them. After adding 60 μL of carbon quantum dots to the 16 sample bottles, then add Cd -3 with a concentration of 5.0x10 2+ , Ag + , Al 3+ , Ba 2+ , Co 2 + , Cr 3+ , Cu 2+ , Hg 2+ , K + , Mg 2+ , Mn 2+ , Na + , NH4 + , Ni 2+ , Pb 2+, Zn 2+ , Fe 3+ A 60 μL solution. The fluorescence emission spectra of 16 samples were measured at 330 nm, and the results are as Figure 6 shown. Figure 6 The test results show that: in domestic water, the addition of Fe 3+ significantly reduces the fluorescence intensity of the carbon quantum dots, while the addition of other metal ions basically does not affect the fluorescence intensity of the carbon quantum dots, indicating that the carbon quantum dots can effectively identify iron ions Fe 3+ in domestic water.

[0056] Sixteen 5 mL sample bottles were taken. After adding 3 mL of untreated domestic water to each, 60 μL of carbon quantum dots were added to each. Then, 60 μL of 5.0x10 -3 M Fe 3+ was added to each of the 16 sample bottles. The fluorescence emission spectra were measured. Then, 60 μL of a solution with a concentration of 5.0x10 -3 M Cd 2+ , Ag + , Al 3+ , Ba 2+ , Co 2+ , Cr 3+ , Cu 2+ , Hg 2+ , K + , Mg 2+ , Mn 2+ , Na + , NH4 + , Ni 2+ , Pb 2+ , Zn 2+ , Fe 3+ A 60 μL solution. The fluorescence emission spectra of each sample were measured at 330 nm, and the results are as Figure 7 shown. The test results show that: the addition of other ions does not affect the detection of iron ions by the carbon quantum dots. Even when all the ions are mixed with iron ions, the fluorescence intensity of the carbon quantum dots does not change significantly, indicating that the carbon quantum dots have strong anti-interference ability and can effectively detect the presence of iron ions in domestic water. At the same time, it also shows that the probe has the potential to be applied to detect iron ions in more complex environmental systems or biological systems.

[0057] The concentrations of Fe 3+ in actual samples were measured by atomic absorption method and carbon dots respectively.

[0058] Table 1 Determination of Fe 3+ concentration

[0059]

[0060] To verify the feasibility of this method in the detection of actual samples, this method was used to determine the Fe content in pre-treated beverages (apple juice, grape juice). 3+ First, atomic absorption was used to determine the Fe content in apple juice and grape juice. 3+ It can be known that the Fe content in apple juice 3+ is 8.678×10 -3 μM, and the Fe content in grape juice 3+ is 1.056×10 -2 μM, as shown in Table 1.

[0061] Then, the pre-treated samples after filtration were respectively added to the carbon dot solution to measure the change in fluorescence intensity. 10 μl, 30 μl, 50 μl, 100 μl, 200 μl, and 300 μl of apple juice were added, and the corresponding fluorescence intensities were measured. Similarly, the same method was used for grape juice to measure the corresponding fluorescence intensities. As Figure 8 shown, substituting the fluorescence intensity at this time into the detection line equation Y = -85344x + 996.74, the corresponding Fe concentration at this time can be calculated to detect whether this method can be used for the detection of actual samples. 3+ Table 2 Determination of iron ion concentration by two methods

[0062] As shown in the above table, when 100 μl of apple juice was added, the calculated Fe concentration in the sample

[0063]

[0064] was 8.617×10 3+ μM, and when 30 μl of grape juice was added, the calculated Fe concentration in the sample -3 was 1.13×10 3+ μM. The errors are very small, indicating that this method can be used for the detection of actual samples. -2 In summary, the present invention provides a preparation method of a novel boron-doped carbon quantum dot and its application in the detection of Fe. The preparation method of this novel boron-doped carbon quantum dot is as follows: using tartaric acid, arginine, and boric acid as raw materials, a hydrothermal synthesis method is used to prepare boron-doped carbon quantum dots with rich surface functional groups. These carbon quantum dots can be uniformly dispersed in water and have good fluorescence detection selectivity for Fe. Compared with existing or the same detection technologies, the carbon quantum dots obtained in the present invention are simple to prepare, the raw materials are inexpensive, the synthesis process meets the requirements of green chemistry, the post-treatment is convenient, and it is suitable for large-scale production; at the same time, the detection method is simple and fast. These carbon quantum dots can detect trace Fe with high sensitivity and high selectivity in pure water medium.

[0065] 3+ 3+ 3+ ​​​Ions have application value in many aspects in actual life detection.

[0066] As described above, it is not any form of restriction on the present invention. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, may make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content disclosed above. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of boron-doped carbon quantum dots, characterized in that, The preparation method comprises the following steps: Step S1: Weigh L(+)-tartaric acid, arginine, and boric acid and pour them into a beaker. Add deionized water and stir to dissolve. After complete dissolution, transfer it to a reaction kettle. Step S2: Place the reaction kettle in Step S1 in an oven and react for a certain period of time. Step S3: Filter the reaction solution in Step S2 with a filter membrane; add acetone to precipitate, and then centrifuge the obtained solution in a centrifuge to obtain boron-doped carbon quantum dots, and store the carbon quantum dots for later use. In Step S1, the molar ratio of L(+)-tartaric acid, arginine, and boric acid is 9.2 mmol: 4.6 mmol: 12.9 mmol.

2. The preparation method of a boron-doped carbon quantum dot as described in claim 1, characterized in that, In Step S2, the oven temperature is 180 °C and the reaction time is 10 h.

3. The preparation method of a boron-doped carbon quantum dot as described in claim 1, characterized in that, In Step S3, the pore size of the filter membrane is 0.2 μm.

4. The preparation method of a boron-doped carbon quantum dot as described in claim 1, characterized in that, In Step S3, the centrifuge rotates at 11000 r / m for 10 min.

5. The preparation method of a boron-doped carbon quantum dot as described in claim 1, characterized in that, In Step S3, the synthesized carbon quantum dots are stored at 4 °C for later use.

6. A boron-doped carbon quantum dot, characterized in that, The boron-doped carbon quantum dots are prepared by the preparation method described in any one of claims 1-5.

7. Use of a boron-doped carbon quantum dot as described in claim 6 for detecting Fe 3+ characterized in that The application method comprises the following steps: Step K1: Take n sample bottles and add untreated household water to each sample bottle. Step K2: Add boron-doped carbon quantum dots to each sample bottle respectively, and then add ferric chloride solution to each sample bottle respectively to prepare mixed solutions with different iron ion molar concentrations. After standing at room temperature, with 330 nm as the excitation wavelength, measure the fluorescence emission spectrum change diagrams of each sample respectively. Step K3: Make a fitting curve of the fluorescence intensity versus the iron ion concentration according to the change of the fluorescence intensity in the fluorescence emission spectrum change diagram of each sample. Step K4: Substitute the fluorescence intensity value of the sample to be detected into the fitting curve equation in Step K3 to obtain the Fe concentration in the sample to be detected. 3+ Concentration.

8. Use of a boron-doped carbon quantum dot as described in claim 7 for detecting Fe 3+ wherein, When the untreated household water is 3 mL, the addition amount of the boron-doped carbon quantum dots is 60 μL.

9. Use of a boron-doped carbon quantum dot as described in claim 7 for detecting Fe 3+ characterized in that The standing time at room temperature is 3 min.

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