Method for rapidly detecting Fe < 3 + > in water by using sulfur-doped coffee residue carbon quantum dots
Through the hydrothermal reaction preparation method of sulfur-doped coffee ground carbon quantum doped, the existing Fe3+ detection technology equipment is solved, and efficient and simple Fe3+ detection is achieved, with high selectivity, low detection limit and strong anti-interference ability.
Patent Information
- Application Number
- CN202510284917.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-11
- Publication Date
- 2025-05-30
AI Technical Summary
The existing Fe3+ detection technology has problems such as expensive equipment and cumbersome pre-processing process, making it difficult to achieve efficient and simple detection.
The carbon quantum doped with sulfur-doped coffee grounds is prepared by hydrothermal reaction, and the fluorescence intensity is measured by a fluorescence spectrometer to achieve rapid detection of Fe3+.
It realizes high selective recognition of Fe3+, with wide detection linear range, low detection limit, high sensitivity, strong anti-interference ability and short detection time, and is suitable for rapid quantitative determination of samples in different environments.
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Figure CN120064230A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of water quality detection, and more specifically, relates to a method for rapidly detecting Fe in water by using sulfur-doped coffee residue carbon quantum dots 3+ . Background Art
[0002] Iron is one of the most abundant elements in nature, accounting for about 5-10% of the crust content. As one of the main sources of industrial process pollutants, when discharged into water bodies with industrial wastewater and domestic sewage, it will cause serious pollution to the ecological environment. Excessive iron ions in water will make the water body orange-red and turbid, and the dissolved oxygen in the water will rapidly decrease, resulting in the death of aquatic organisms. At present, the analytical methods for detecting Fe mainly include atomic absorption spectrometry, inductively coupled plasma emission spectrometry, inductively coupled plasma mass spectrometry, voltammetry, colorimetry, etc. These traditional methods have disadvantages such as expensive equipment and cumbersome pretreatment processes, which are not conducive to the efficient detection of actual samples. Developing simple and efficient new Fe analysis technologies has become a research hotspot in this analysis field 3+ . 3+ . 3+
[0003] Quantum dots are a new type of nanomaterial and are widely used in the fields of photocatalysis, ion detection, biological detection, biological imaging, etc. As a fluorescent probe, quantum dots can achieve simple and rapid detection of Fe. Chabok et al. synthesized carboxyl-functionalized polymer dots for detecting iron ions, with a response range of 0.1-720 μM and a detection limit of 0.058 nM. Lima et al. prepared CdTe quantum dots, used on-line single-phase extraction of iron ions, and established the interaction between iron ions and CdTe quantum dots to detect iron ions. The results showed that the fluorescence quenching intensity was proportional to the iron ion concentration, and the correlation coefficient R 3+ =0.997. Hu et al. used the air oxidation method for waste PET and carried out hydrothermal treatment in H 2 O 2 to synthesize fluorescent carbon dots, and realized the detection of iron ions and pyrophosphate anions through the quenching effect, forming a "switch" fluorescent sensor 2 .
[0004] However, the existing technologies for preparing quantum dots have problems such as expensive precursors, high costs, and complex preparation processes. Therefore, it is urgent to find green and cheap precursors to synthesize quantum dots and establish a detection technology with high sensitivity, low detection limit, short detection time, simple operation, and portability for real-time and rapid detection of Fe in the environment 3+ . Summary of the Invention
[0005] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for rapidly detecting Fe in water by using sulfur-doped coffee residue carbon quantum dots, which has high selectivity for the detection of Fe. 3+ 3+
[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows:
[0007] A method for rapidly detecting Fe in water by using sulfur-doped coffee residue carbon quantum dots, which measures the fluorescence intensity of the water sample to be tested added with sulfur-doped coffee residue carbon quantum dots by a fluorescence spectrometer. Compared with the fluorescence intensity of the sulfur-doped coffee residue carbon quantum dots, if the fluorescence intensity at the emission wavelength of 490 nm decreases, then the water sample to be tested contains Fe. 3+ 3+
[0008] Preferably, the linear concentration range of Fe is 0.1-10 mg / L, and the detection limit is 0.05 mg / L. 3+
[0009] A method for rapidly detecting Fe in water by using sulfur-doped coffee residue carbon quantum dots, comprising the following steps: 3+
[0010] (1) Drawing of the standard working curve:
[0011] Solutions of different concentrations of Fe are respectively added to the sulfur-doped coffee residue carbon quantum dot solution, and the fluorescence intensity of the system is measured by a fluorescence spectrometer. The excitation wavelength of the fluorescence spectrometer is 400 nm, and the emission wavelength is 490 nm; the standard working curve graph is drawn by using the fluorescence intensity ratio F / F and the concentration of Fe. 3+ 0 3+
[0012] (2) Detection of the water sample to be tested:
[0013] The F / F value of the system to be tested is measured by the same detection method as in step (1), and the concentration of Fe in the water sample to be tested is calculated by using the standard working curve of step (1). 0 3+
[0014] Preferably, in the step (1), the concentration of the sulfur-doped coffee residue carbon quantum dot solution is 1 mg / mL, and the standard concentration gradient curve of Fe is y = -0.0915x + 1.0029, and the correlation coefficient is 0.9994. 3+
[0015] A preparation method of sulfur-doped coffee residue carbon quantum dots. The coffee residue is washed, freeze-dried, and pulverized to obtain coffee residue powder. Then, the coffee residue powder and a sulfur source are added to water for hydrothermal reaction. After filtration through a microporous membrane, dialysis, and freeze-drying, it is dispersed in ultrapure water to prepare sulfur-doped coffee residue carbon quantum dots.
[0016] Preferably, the mass ratio of the coffee residue powder to the sulfur source is 0.5 - 2:1. More preferably, the mass ratio of the coffee residue powder to the sulfur source is 1:1.
[0017] Preferably, the sulfur source is selected from any one of thiosemicarbazide, methylthiourea, and thiourea. More preferably, the sulfur source is thiourea.
[0018] Preferably, the coffee bean variety of the coffee residue is selected from any one of Arabica coffee beans, Robusta coffee beans, Vietnamese coffee beans, and Yunnan coffee beans. More preferably, the coffee bean variety of the coffee residue is Yunnan coffee beans.
[0019] Preferably, the temperature of the hydrothermal reaction is 150 - 220 °C, and the reaction time is 18 h. More preferably, the temperature of the hydrothermal reaction is 200 °C, and the reaction time is 18 h.
[0020] Preferably, the pore size of the microporous membrane is 0.22 μm, the molecular weight cut-off of the dialysis bag during dialysis is 3500 Da, the dialysis time is 12 - 36 h, and it is dispersed in an ultrapure aqueous solution.
[0021] The sulfur-doped coffee residue carbon quantum dots are prepared by the above-mentioned preparation method of sulfur-doped coffee residue carbon quantum dots.
[0022] The application of the sulfur-doped coffee residue carbon quantum dots in detecting Fe 3+ in surface water, groundwater, and tap water.
[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0024] (1) The present invention uses recycled coffee residue as the raw material and thiourea as the auxiliary material to obtain carbon quantum dots with high selectivity for Fe 3+ by a one-step hydrothermal synthesis method. The raw materials are easily available, the cost is low, the preparation method does not require complex organic synthesis, the process is simple, and it is green and environmentally friendly;
[0025] (2) In an aqueous solution, the carbon quantum dots prepared by the present invention undergo a redox reaction with Fe 3+ to cause fluorescence quenching at the optimal excitation wavelength of 400 nm and emission wavelength of 490 nm. The quantitative detection of Fe 3+ is achieved according to the change in the intensity of the fluorescence characteristic peak;
[0026] (3) The sulfur-doped coffee ground carbon quantum dots prepared by the present invention have high selectivity for the detection of Fe 3+ with a wide detection linear range from 0.1 to 10 mg / L, a low detection limit of 0.05 mg / L, high sensitivity, strong anti-interference ability, and a detection time as short as within 15 s. It can be used for the rapid quantitative determination of Fe 3+ in different environmental samples;
[0027] (4) The sulfur-doped coffee ground carbon quantum dots prepared by the present invention can achieve the quantitative detection of Fe 3+ in surface water, groundwater, and tap water, with good precision and accuracy, and have good application prospects. DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 is the infrared spectrum of the sulfur-doped coffee ground carbon quantum dots prepared in Example 1;
[0029] Figure 2 is the transmission electron microscope and particle size distribution diagram of the sulfur-doped coffee ground carbon quantum dots prepared in Example 1 under a 10 nm scale; where Figure (a) is the transmission electron microscope image and Figure (b) is the particle size distribution diagram;
[0030] Figure 3 is the X-ray photoelectron spectroscopy of the sulfur-doped coffee ground carbon quantum dots prepared in Example 1;
[0031] Figure 4 is the fluorescence intensity and standard working linear diagram of the sulfur-doped coffee ground carbon quantum dots prepared in Example 1 for detecting different concentrations of Fe 3+ ; where Figure (a) is the fluorescence intensity diagram and Figure (b) is the standard working linear diagram;
[0032] Figure 5 is the influence of pH when the sulfur-doped coffee ground carbon quantum dots prepared in Example 1 detect Fe 3+ ;
[0033] Figure 6 is the influence of reaction time when the sulfur-doped coffee ground carbon quantum dots prepared in Example 1 detect Fe 3+ ;
[0034] Figure 7 is the anti-interference ability result diagram of the sulfur-doped coffee ground carbon quantum dots prepared in Example 1 for Fe 3+ ; where Figure (a) is the fluorescence quenching diagram of 10 different metal ions; Figure (b) is the fluorescence quenching diagram of Fe 3+ mixed with other metal ions. DETAILED DESCRIPTION OF THE INVENTION
[0035] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified in the following embodiments, the technical means used are all conventional means well-known to those skilled in the art. For those not specifying specific conditions in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.
[0036] Example 1
[0037] A preparation method of sulfur-doped coffee residue carbon quantum dots provided in this embodiment specifically includes the following steps:
[0038] 1) After collecting Yunnan coffee residues, washing them, and freeze-drying them, they are ground into powder with a high-speed grinder and passed through a 100-mesh sieve for standby;
[0039] 2) 0.1 g of Yunnan coffee residues and 0.1 g of thiourea are evenly dispersed in 50 mL of water, stirred evenly, added into a reaction kettle, and hydrothermally reacted at 200 °C for 18 h to obtain a sulfur-doped coffee residue carbon quantum dot solution;
[0040] 3) The sulfur-doped coffee residue carbon quantum dot solution prepared in step 2) is dialyzed for 18 h with a 0.22 μm filter membrane and a dialysis bag with a cut-off molecular weight of 3500 Da, freeze-dried, and then 0.05 g is dispersed in 50 mL of ultrapure water to prepare a sulfur-doped coffee residue carbon quantum dot dispersion with a concentration of 1 mg / mL, which is stored at 4 °C.
[0041] The Fourier transform infrared spectrum, particle size distribution diagram, and X-ray photoelectron spectrum of the sulfur-doped coffee residue carbon quantum dots prepared in this embodiment are respectively Figure 1 、 Figure 2 and Figure 3 .
[0042] It can be seen from Figure 1 that the absorption peak at 3148 cm -1 is the stretching vibration peak of hydroxyl -OH, and the absorption peak at 2049 cm -1 is the stretching vibration peak of carbon-sulfur double bond. The characteristic peak of C=O appears near 1620 cm -1 , indicating that the synthesized carbon quantum dots have rich oxygen-containing and sulfur-containing functional groups, making them have good water solubility.
[0043] It can be seen from Figure 2 that under the transmission electron microscope (10 nm scale), these carbon quantum dots are all spherical particles, with an average particle diameter of about 3.2 nm and good dispersibility, ensuring good fluorescence properties of the carbon quantum dots.
[0044] It can be seen from Figure 3It can be seen that through X-ray photoelectron spectroscopy, it is further verified that the carbon quantum dots contain a carbon-sulfur cumulative double bond structure, which can react with Fe 3+ in an oxidation-reduction reaction, enabling it to selectively detect Fe 3+ .
[0045] Example 2
[0046] Perform a quantitative detection experiment of Fe 3+ on the sulfur-doped coffee residue carbon quantum dots prepared in Example 1 above: Add 3 mL of the sulfur-doped coffee residue carbon quantum dot solution with a concentration of 1 mg / mL prepared in Example 1 to a 1-cm quartz cuvette. It is found that the sulfur-doped coffee residue carbon quantum dots have a strong fluorescence response at an excitation wavelength of 400 nm and an emission wavelength of 490 nm. Add different concentrations of Fe 3+ , conduct fluorescence detection, and establish a standard working curve based on the linear relationship between the detected fluorescence emission intensity change and the Fe 3+ concentration. The results are as Figure 4 shown.
[0047] It can be seen from Figure 4 that after adding Fe 3+ , within 15 s, the fluorescence spectrum of the coffee residue carbon quantum dots has changed significantly, and with the increase of the Fe 3+ concentration, the fluorescence response intensity at 490 nm gradually decreases. When F 0 is the initial fluorescence intensity and F is the fluorescence intensity corresponding to different concentrations of added Fe 3+ , plot the fluorescence emission intensity of F 0 / F against the Fe 3+ concentration. The coffee residue carbon quantum dots have a good linear relationship with Fe 3+ in the concentration range of 0.1 - 10 mg / L. The standard concentration gradient curve is y = -0.0915x + 1.0029, the correlation coefficient is 0.9994, and the detection limit is 0.05 mg / L.
[0048] Example 3
[0049] Perform an experiment on the effects of pH value and reaction time on the sulfur-doped coffee residue carbon quantum dots prepared in Example 1. The results are as Figures 5 - 6 shown.
[0050] It can be seen from Figure 5 that within the range of solution pH between 2.0 and 11.0, the fluorescence intensity of the carbon quantum dots does not change significantly with the change of pH value. However, after adding Fe 3+ , the fluorescence intensity drops significantly, and effective recognition of Fe 3 + can be achieved within the acid-base range.
[0051] It can be seen from Figure 6 that when Fe is added to the carbon quantum dot solution prepared by the present invention 3+ , after about 15 s of reaction time, the fluorescence emission intensity has decreased significantly, and the fluorescence value is basically stable after 5 min without obvious change. It shows that the reaction rate of this carbon quantum dot and Fe 3+ is fast.
[0052] Example 4
[0053] The selective experiment and anti-interference experiment of Fe 3+ were carried out on the sulfur-doped coffee residue carbon quantum dots prepared in Example 1, and the fluorescence responses of 10 common metal ions (Fe 3+ , Na + , Ag + , Ca 2+ , Mg 2+ , Ba 2+ , Co 2+ , Ni 2+ , Cu 2+ , Mn 2+ ) in water and their competitive effects on each other were measured.
[0054] The specific experimental process is as follows: at room temperature, 10 metal ions with a concentration of 10 mg / L were reacted with sulfur-doped coffee residue carbon quantum dots with the same concentration (1 mg / mL) respectively, and the fluorescence intensity of the solution at the emission spectrum of 490 nm under the excitation wavelength of 400 nm was measured. The results are as Figure 7 (a) shown. Then 5 mg / L of Fe 3+ was mixed with the other 9 metal ions with a concentration of 5 mg / L respectively and reacted with 1 mg / mL of carbon quantum dots, and the fluorescence intensity of the solution at the emission spectrum of 490 nm under the excitation wavelength of 400 nm was measured. The results are as Figure 7 (b) shown.
[0055] It can be seen from Figure 7 (a) that only Fe 3+ can significantly quench the fluorescence emission of sulfur-doped coffee residue carbon quantum dots at 490 nm, indicating that the sulfur-doped coffee residue carbon quantum dots prepared by the present invention have significant selectivity for Fe 3+ .
[0056] It can be seen from Figure 7 (b) that when Fe 3+ coexists with other metal ions, it can still effectively quench the fluorescence of sulfur-doped coffee residue carbon quantum dots, and the fluorescence response has no significant difference from that when Fe 3+ exists alone, indicating that the coffee residue carbon quantum dots prepared by the present invention have significant selectivity for Fe 3+Strong anti-interference ability.
[0057] Example 5
[0058] The coffee ground carbon quantum dots prepared in Example 1 were used to detect Fe in surface water, groundwater, and tap water. 3+ The specific process was as follows: After the water sample was filtered, 1 mL of the sample was directly taken and added to 3 mL of a 1 mg / mL sulfur-doped coffee ground carbon quantum dot solution, and a standard addition recovery experiment was then carried out. The results are shown in Table 1.
[0059] Table 1 Detection of Fe in actual water samples using the sulfur-doped coffee ground carbon quantum dots prepared in Example 1 3+ Results
[0060]
[0061] As can be seen from Table 1, the standard addition recovery rate of the actual water sample was between 85.0% and 105%, and the relative standard deviation range was between 0.52% and 8.95%, indicating that this method has high precision and accuracy in the detection of actual samples.
[0062] In summary, the present invention designed and synthesized a carbon quantum material based on sulfur-doped coffee grounds for the detection of Fe in water bodies. 3+ It not only has a fast detection speed, but also shows selectivity, high sensitivity, good stability, and strong anti-interference ability. Moreover, the preparation method of this carbon quantum dot material is simple, the raw materials are cheap and easily available, environmentally friendly, and easy to operate.
[0063] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.
Claims
1. A method for rapid detection of Fe in water using sulfur-doped coffee grounds carbon quantum dots 3+ The method is characterized in that The fluorescence intensity of the water sample to be tested with sulfur-doped coffee grounds carbon quantum dots was measured by fluorescence spectrometer. Compared with the fluorescence intensity of sulfur-doped coffee grounds carbon quantum dots, if the fluorescence intensity at the emission wavelength of 490nm is reduced, the water sample to be tested contains Fe 3+ .
2. Rapid detection of Fe in water using coffee grounds carbon quantum dots according to claim 2 3+ The method is characterized in that Fe 3+ The linear concentration range is 0.1~10 mg / L, and the detection limit is 0.05 mg / L.
3. A method for rapid detection of Fe in water using sulfur-doped coffee grounds carbon quantum dots 3+ The method is characterized in that The following steps are involved: (1) Drawing of standard working curve: The different concentrations of Fe 3+ The solution was added to the sulfur-doped coffee grounds carbon quantum dot solution, and the fluorescence intensity of the system was measured using a fluorescence spectrometer with an excitation wavelength of 400 nm and an emission wavelength of 490 nm. The fluorescence intensity ratio F0 / F and Fe 3+ Concentration is used to draw the standard working curve; (2) Testing of water samples to be tested: The same detection method as step 1) is used to determine the F0 / F value of the test system, and the standard working curve of step 1) is used to calculate the Fe content in the water sample to be tested. 3+ concentration.
4. Rapid detection of Fe in water using sulfur-doped coffee grounds carbon quantum dots according to claim 3 3+ The method is characterized in that In step (1), the concentration of the sulfur-doped coffee grounds carbon quantum dots solution is 1 mg / mL, and the Fe 3+ The standard concentration gradient curve is y=-0.0915x+1.0029, and the correlation coefficient is 0.9994.
5. A method for preparing sulfur-doped coffee grounds carbon quantum dots, characterized in that: The coffee grounds are washed, freeze-dried and crushed to obtain coffee grounds powder, and then the coffee grounds powder and a sulfur source are added to water for hydrothermal reaction. After filtering through a microporous filter membrane, dialyzing and freeze-drying, the powder is dispersed with ultrapure water to obtain sulfur-doped coffee grounds carbon quantum dots.
6. The method for preparing sulfur-doped coffee grounds carbon quantum dots according to claim 5, characterized in that: The mass ratio of the coffee grounds powder to the sulfur source is 0.5-2:
1.
7. The method for preparing sulfur-doped coffee grounds carbon quantum dots according to claim 5, characterized in that: The sulfur source is selected from any one of thiosemicarbazide, methylthiourea and thiourea.
8. The method for preparing sulfur-doped coffee grounds carbon quantum dots according to claim 5, characterized in that: The temperature of the hydrothermal reaction is 150-220° C., and the reaction time is 18 h.
9. The method for preparing sulfur-doped coffee grounds carbon quantum dots according to any one of claims 5 to 8 prepares sulfur-doped coffee grounds carbon quantum dots.
10. The sulfur-doped coffee grounds carbon quantum dots according to claim 9 are useful for detecting Fe in surface water, groundwater, and tap water. 3+ Application in.