Composite fluorescent probe as well as preparation method and application method thereof

Abstract

The invention relates to a preparation method of a composite fluorescent probe, the composite fluorescent probe prepared by the preparation method and application of the composite fluorescent probe in the field of metal corrosion detection. The preparation method comprises the following steps: uniformly mixing a carbon source, 1, 10-phenanthroline and a zinc source in water, and carrying out a one-pot hydrothermal synthesis reaction; and cooling the obtained mixed solution, and storing in a dark place at the temperature of 4-10 DEG C. The technical scheme provided by the invention is a novel detection method with real-time monitoring, high sensitivity and lower cost, and a new breakthrough is opened for the field of metal corrosion detection.

Description

Technical Field

[0001] The present invention relates to the field of metal corrosion detection, and in particular to the preparation of a zinc-doped 1,10-phenanthroline carbon quantum dot composite fluorescent probe and its detection of Fe in the early corrosion environment of carbon steel. 3+ detection applications. Background Art

[0002] The rapid development of the industrial age has driven the widespread application of metal machinery and equipment in fields such as chemical engineering, metallurgy, and energy. However, in complex service environments, factors such as temperature and humidity, oxygen, salt ions, pH, and pollutants can lead to frequent corrosion of metal materials. Studies have shown that localized corrosion (such as stress corrosion and pitting) is hidden and, once it fails, can cause major accidents such as explosions and leaks. Therefore, the development of rapid, sensitive, and low-cost corrosion early warning technology is of great significance for the protection of metal equipment, economic cost savings, and environmental safety.

[0003] Early detection of metal corrosion is of great engineering significance for ensuring the safety of metal mechanical structures and extending the service life of chemical machinery. Currently, widely used corrosion detection methods, such as magnetic particle testing, eddy current testing, and ultrasonic testing, offer technical advantages such as dynamic response, strong penetration, and multi-angle detection. However, they also suffer from drawbacks such as complex operation, high cost, and poor adaptability. Therefore, developing new detection methods that combine real-time monitoring, high sensitivity, and low cost has become a key breakthrough in the field of corrosion detection. Summary of the Invention

[0004] Therefore, it is necessary to provide a new detection method that combines real-time monitoring, high sensitivity and low cost to solve the above problems in the field of corrosion detection technology.

[0005] To achieve the above object, the inventors provide a method for preparing a composite fluorescent probe, comprising the following steps:

[0006] The carbon source, 1,10-phenanthroline and zinc source are uniformly mixed in water to perform a one-pot hydrothermal synthesis reaction; the resulting mixed solution is cooled and stored in a dark place at a temperature range of 4-10°C;

[0007] The carbon source is citric acid, and the zinc source is zinc nitrate hexahydrate.

[0008] Furthermore, in the preparation method of the composite fluorescent probe, the "uniform mixing" is specifically: placing the container of the mixed solution on a magnetic stirrer and stirring for 10-20 minutes.

[0009] Furthermore, in the preparation method of the composite fluorescent probe, the reaction conditions of the one-pot hydrothermal method are specifically: 180-220° C., 5-10 h.

[0010] Furthermore, in the preparation method of the composite fluorescent probe, the step of "one-pot hydrothermal synthesis reaction" also includes the steps of: transferring the obtained solution to a polytetrafluoroethylene liner, loading it into a matching high-pressure reactor shell, sealing it and placing it in an oven, and maintaining it at 200°C for 7 hours.

[0011] The inventors also provide a composite fluorescent probe, which is prepared by the above-mentioned preparation method of the composite fluorescent probe.

[0012] The inventors also provide an application method of the composite fluorescent probe, which is to apply the composite fluorescent probe to Fe 3+ The specific steps of detection include:

[0013] Immerse the carbon steel to be tested in a NaCl aqueous solution to obtain a corrosion solution, and take out an appropriate amount of the corrosion solution (every 2 hours) and mix it with the composite fluorescent probe solution;

[0014] The fluorescence spectrum of the mixed solution was measured by molecular fluorescence spectrophotometer to obtain Fe 3+ Concentration information.

[0015] Furthermore, in the application method of the composite fluorescent probe, the carbon steel to be tested is Q235 carbon steel.

[0016] Furthermore, in the application method of the composite fluorescent probe, the concentration of the NaCl aqueous solution is 0.1 mol / L.

[0017] Furthermore, in the application method of the composite fluorescent probe, the step of "taking out an appropriate amount of corrosion solution and mixing it with the composite fluorescent probe solution" is specifically: taking 150 μL of the composite fluorescent probe solution and the corrosion solution and mixing them.

[0018] Furthermore, in the application method of the composite fluorescent probe, the step of "measuring the fluorescence spectrum of the mixed solution with a molecular fluorescence spectrophotometer to obtain Fe 3+ Concentration information" specifically refers to: the composite fluorescent probe and Fe 3+ The formed complex emits fluorescence at 434 nm (λ ex =388nm).

[0019] Different from the existing technology, the present invention uses zinc-doped 1,10-phenanthroline carbon quantum dots (Zn-CDs@P) as a fluorescent probe and uses fluorescence analysis method to explore Fe 3+The influence of concentration change on the fluorescence intensity of the probe can be used to warn the early corrosion response of carbon steel in NaCl medium. This invention has important engineering significance and practical application value. Its technical principle is: using zinc-doped 1,10-phenanthroline carbon quantum dots (Zn-CDs@P) as fluorescent probes, on the one hand, by doping zinc ions, the crystallinity of carbon quantum dots is changed, and the non-radiative transition process in Zn-CDs is reduced, thereby amplifying the fluorescence emission intensity of carbon quantum dots; on the other hand, Fe 3+ It forms [Fe(Phen) n ] 3+ Stable orange complex, photogenerated electrons in the conduction band of carbon quantum dots move from quantum dots to Fe 3+ The metal center migrates. Once the composite probe is combined with Fe 3+ Combined with 388nm excitation light, with the Fe 3+ As the concentration increases, the fluorescence emission intensity of the solution at 434nm decreases. At the same time, the color of the solution changes significantly. This method can quickly detect Fe 3+ concentration, thereby detecting the early corrosion of carbon steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of a method for preparing a composite fluorescent probe according to one embodiment of the present invention;

[0021] Figure 2 This is a TEM image of the composite fluorescent probe according to one embodiment of the present invention.

[0022] Figure 3 In the application method of the composite fluorescent probe according to one embodiment of the present invention, different concentrations of Fe 3+ Visualization of Zn-CDs@P solution. DETAILED DESCRIPTION

[0023] In order to explain the technical content, structural features, achieved objectives and effects of the technical solution in detail, the following is a detailed description in conjunction with specific embodiments and accompanying drawings.

[0024] First embodiment

[0025] A method for preparing a zinc-doped 1,10-phenanthroline carbon quantum dot composite fluorescent probe (Zn-CDs@P) is provided. Zn-CDs@P is prepared by a hydrothermal method. The specific steps are as follows:

[0026] Weigh 0.5 g of citric acid monohydrate, 0.05 g of 1,10-phenanthroline monohydrate, and 0.05 g of Zn(NO₃)₂·6H₂O, dissolve them in 15 mL of ultrapure water, and stir for 10 minutes until a clear solution forms. Transfer the solution to a 25 mL polytetrafluoroethylene-lined autoclave, seal it, and place it in an oven at 200°C for 7 hours. Allow the autoclave to cool to room temperature, collect the liquid, and store it in a refrigerator at 4°C protected from light until ready for use.

[0027] Second embodiment

[0028] A zinc-doped 1,10-phenanthroline carbon quantum dot composite fluorescent probe is prepared by the preparation method of the zinc-doped 1,10-phenanthroline carbon quantum dot composite fluorescent probe (Zn-CDs@P) described in the first embodiment.

[0029] Please refer to the attached Figure 2 , which is the TEM image of the above-mentioned Zn-CDs@P. It can be seen from the figure that Zn-CDs@P is spherical, uniform in size, has good dispersion, and the lattice spacing is 0.24nm.

[0030] Third embodiment

[0031] A zinc-doped 1,10-phenanthroline carbon quantum dot composite fluorescent probe (Zn-CDs@P) for Fe 3+ Application method of the detection:

[0032] At room temperature, the prepared Zn-CDs@P solution was used to treat Fe 3+ Perform fluorescence detection. Dissolve appropriate amount of FeCl3·6H2O in ultrapure water to prepare a series of Fe 3+ Solution. Different concentrations of Fe were added to the Zn-CDs@P solution. 3+ , mix well with equal volumes and incubate for 20 min.

[0033] Please refer to the attached Figure 3 :Under the excitation wavelengths of 302nm(b) and 365nm(c), the fluorescence color of Zn-CDs@P was observed to increase with the Fe 3+ The fluorescence emission spectrum of the mixed solution at 388 nm excitation wavelength was measured by molecular fluorescence spectrophotometer, and the fluorescence intensity of the mixed solution was measured by adding different concentrations of Fe 3+ The fluorescence spectrum of Zn-CDs@P solution can be obtained. 3+ The detection limit LOD of this detection method is 0.89 μM.

[0034] Fourth embodiment

[0035] An application method of a zinc-doped 1,10-phenanthroline carbon quantum dot composite fluorescent probe (Zn-CDs@P):

[0036] Q235 carbon steel was used as the experimental object and immersed in 0.1mol / L NaCl solution for corrosion simulation. As the immersion time increased, the Fe 3+ The concentration was gradually increased. Appropriate amounts of the corrosion solution were removed at preset time intervals and mixed with an equal volume of the Zn-CDs@P solution. The mixture was incubated at room temperature for 20 minutes. The fluorescence emission spectrum of the mixed solution was scanned using a molecular fluorescence spectrophotometer, and the fluorescence emission intensity at 434 nm was recorded. The fluorescence intensity of the blank control (Zn-CDs@P mixed with NaCl solution without carbon steel immersion) was used as a reference. The fluorescence intensity of the Zn-CDs@P probe gradually decreased with increasing corrosion time. After 30 minutes of immersion, the fluorescence intensity of the Zn-CDs@P probe underwent dynamic quenching, indicating that the mixed solution was in the anodic activation dissolution control stage, corresponding to the early corrosion process of carbon steel, indicating that Zn-CDs@P can be used for early corrosion detection.

[0037] Compared with the prior art, the present invention has the following advantages: by introducing zinc ions and 1,10-phenanthroline into carbon quantum dots to prepare a composite fluorescent probe, the zinc ions enhance the fluorescence performance of the carbon quantum dots, and significantly improve the fluorescence of the composite fluorescent probe to Fe 3+ At the same time, the zinc-doped 1,10-phenanthroline carbon quantum dot composite fluorescent probe and Fe 3+ Complexation occurs to quench fluorescence, achieving Fe 3+ Rapid and sensitive detection of Fe 3+ The formation of a stable orange complex promotes the mixed system to have different Fe 3+ The present invention has the characteristics of simple operation, high sensitivity and good selectivity, and is suitable for Fe in the early corrosion environment of carbon steel. 3+ Detection. The present invention uses zinc-doped 1,10-phenanthroline carbon quantum dot composite fluorescent probes to conveniently and quickly detect the early corrosion of carbon steel in NaCl corrosive medium, and can qualitatively judge the degree of corrosion by the color change of the corrosive solution, providing an effective technical solution for the early detection of metal corrosion.

[0038] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection of the present invention. Therefore, based on the innovative concept of the present invention, changes and modifications to the embodiments described herein, or equivalent structural or equivalent process transformations made using the contents of the present invention's specification and drawings, and direct or indirect application of the above technical solutions to other related technical fields, are all included in the scope of patent protection of the present invention.

Claims

1. A method for preparing a composite fluorescent probe, characterized in that: The following steps are involved: The carbon source, 1,10-phenanthroline and zinc source are uniformly mixed in water to perform a one-pot hydrothermal synthesis reaction; the resulting mixed solution is cooled and stored in the dark at a temperature range of 4-10°C; The carbon source is citric acid, and the zinc source is zinc nitrate hexahydrate.

2. The method for preparing the composite fluorescent probe according to claim 1, wherein: The "uniform mixing" specifically includes placing the container of the mixed solution on a magnetic stirrer and stirring for 10-20 minutes.

3. The method for preparing the composite fluorescent probe according to claim 1 or 2, wherein: The reaction conditions of the one-pot hydrothermal method are specifically: 180-220° C., 5-10 h.

4. The method for preparing the composite fluorescent probe according to claim 3, wherein: The step "one-pot hydrothermal synthesis reaction" also includes the steps of: transferring the obtained solution to a polytetrafluoroethylene liner, loading it into a matching high-pressure reactor shell, sealing it, and placing it in an oven at 200°C for 7 hours.

5. A composite fluorescent probe, characterized in that The method is prepared according to any one of claims 1 to 4.

6. A method for applying a composite fluorescent probe, characterized in that: The composite fluorescent probe described in claim 5 is applied to Fe in the early corrosion environment of carbon steel. 3+ The specific steps of detection include: Immerse the carbon steel to be tested in a NaCl aqueous solution to obtain a corrosion solution, and take out an appropriate amount of the corrosion solution (every 2 hours) and mix it with the composite fluorescent probe solution; The fluorescence spectrum of the mixed solution was measured by molecular fluorescence spectrophotometer to obtain Fe 3+ Concentration information.

7. The application method of the composite fluorescent probe according to claim 6, characterized in that: The carbon steel to be tested is Q235 carbon steel.

8. The method for using the composite fluorescent probe according to claim 6 or 7, wherein: The concentration of the NaCl aqueous solution is 0.1 mol / L.

9. The method for using the composite fluorescent probe according to claim 8, wherein: The step of "taking out an appropriate amount of the corrosion solution and mixing it with the composite fluorescent probe solution" specifically includes: taking 150 μL of the composite fluorescent probe solution and the corrosion solution and mixing them.

10. The application method of the composite fluorescent probe according to claim 9, characterized in that: The step "measure the fluorescence spectrum of the mixed solution with a molecular fluorescence spectrophotometer to obtain Fe 3+ Concentration information" specifically refers to: the composite fluorescent probe and Fe 3+ The formed complex emits fluorescence at 434 nm (λ ex =388nm).

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