Sensor for detecting copper ions as well as preparation method and application of sensor

Abstract

The invention discloses a sensor for detecting copper ions and a preparation method and application thereof, and the sensor is used for rapidly detecting copper ions in lake water, river water and drinking water and is also suitable for detecting copper ions in sewage. According to the technical method, on the basis of an agglomeration mechanism, coordination atoms in a modifier 5-(4H-1, 2, 4-triazole-4-yl) isophthalic acid can form a specific bonding effect with gold nanoparticles, and nitrogen and oxygen atoms in the modifier can generate a coordination effect with target metal ions, so that the aggregation state of a gold nano solution is changed, and then the color of the solution is changed; the peak position and the absorption intensity of the surface plasmon resonance absorption peak of the gold nanoparticles are changed, whether the copper ions are contained in the detected sample or not is judged through naked eyes and an ultraviolet and visible light spectrum, and the content of the copper ions is quantitatively calculated. The technical scheme has the advantages of simplicity in operation, low cost, stability, good repeatability, wide application range and the like.

Description

Technical Field

[0001] The present invention belongs to the field of nanomaterials, and in particular relates to a sensor for detecting copper ions, a preparation method thereof and an application thereof. Background Art

[0002] Water is a critical factor for the proper functioning of ecosystems and an essential resource for human survival. Due to the demands of human life and industrial production, metal ions are widely used across various industries, inevitably leading to their presence in industrial wastewater. Furthermore, metal ions from the air and soil can enter water through natural phenomena such as sedimentation and rainfall. Therefore, monitoring metal ions in water has attracted widespread attention among environmental researchers.

[0003] Copper is a typical transition metal found in nature and an essential element for most living organisms. Copper ions play a vital role in enzyme synthesis, metabolism, and other biological processes. Low copper levels can induce anemia, while high copper levels can cause gastrointestinal disturbances and even damage the liver and kidneys. To ensure the healthy and orderly functioning of organisms, copper levels in organisms must be kept within a reasonable range. Therefore, developing a portable and rapid method for detecting copper ions in water is a research project that researchers urgently need to break through.

[0004] Conventional methods for detecting metal ions in water often require expensive equipment, highly trained operators, long testing cycles, or complex pre-treatment processes, making them inadequate for real-time, on-site detection. In recent years, researchers have shifted away from traditional, time-consuming methods and are opting for more portable, efficient methods to detect hazardous substances. With the rapid advancement of nanotechnology, gold nanomaterials have emerged as an ideal raw material for colorimetric sensors due to their unique advantages. Compared to other metal nanomaterials, gold nanomaterials are used as raw materials for colorimetric sensors due to their low toxicity, ease of processing, high stability, and excellent bioinertness. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a sensor for detecting copper ions, its preparation method and application in view of the existing technology. The sensor can quickly and efficiently detect divalent copper ions in the presence of multiple interfering ions. This method has the advantages of strong anti-interference ability, high sensitivity and high accuracy, and is suitable for rapid detection of copper ion concentration in sewage. The sensor detection system has a good linear relationship, R 2 =0.96, the naked eye detection limit (LOD) was 120 μM, and the UV-visible spectrum detection limit was 0.569 μM.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A method for preparing a sensor for detecting copper ions uses sodium citrate as a reducing agent and stabilizer, and 5-(4H-1,2,4-triazol-4-yl)isophthalic acid (TABDC) as a modifier. Gold nanoparticles are first prepared by sodium citrate reduction, reducing trivalent gold in a chloroauric acid solution to zero-valent gold. Then, 5-(4H-1,2,4-triazol-4-yl)isophthalic acid is added as the modifier to produce a functionalized gold nanoparticle aqueous solution. A series of copper ion standard solutions of varying concentrations are prepared using copper ion standard solutions and ultrapure water, and then added to the functionalized gold nanoparticle aqueous solution. The color of the solution gradually changes from wine red to gray-blue. The 5-(4H-1,2,4-triazol-4-yl)isophthalic acid modifier coordinates the nitrogen atoms on the triazole ring of the gold nanoparticles with the copper ions, causing the gold nanocolloids to aggregate, resulting in a color change from wine red to gray-blue. This enables colorimetric qualitative detection of copper ions in the sample using the naked eye. The change in the aggregation state of gold nanoparticles causes a change in the surface plasmon resonance absorption (SPR) of gold nanoparticles. The quantitative detection of copper ions can be achieved based on the changes in the SPR absorption peak intensity and displacement.

[0008] The English name of 5-(4H-1,2,4-triazol-4-yl)isophthalic acid is 5-(4H-1,2,4-triazol-4-yl)benzene-1,3-dicarboxylic acid, abbreviated as TABDC, and its structure is shown in the following formula (1):

[0009]

[0010] The present invention provides a method for preparing a sensor for detecting copper ions, which specifically comprises the following steps:

[0011] Add tetrahydrated chloroauric acid aqueous solution to a three-necked flask, heat and stir until boiling, quickly add sodium citrate aqueous solution, continue stirring and react for 15 to 20 minutes, until the color of the solution gradually changes from light yellow to dark purple and finally to wine red, and then cool to room temperature to obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C for later use;

[0012] When detecting copper ions, the prepared solution is diluted half with deionized water, and then 5-(4H-1,2,4-triazol-4-yl)isophthalic acid at an optimal concentration is added as a modifier to prepare a functionalized gold nanoparticle aqueous solution, which is the sensor for detecting copper ions, abbreviated as TABDC@AuNPs. This sensor can be used to detect copper ions in a sample to be tested.

[0013] The copper ion is divalent Cu 2+ ion;

[0014] The concentration of the tetrahydrate chloroauric acid aqueous solution is 0.25 mM;

[0015] The pH range of the gold nanoparticle aqueous solution is 3 to 10;

[0016] The concentration of the 5-(4H-1,2,4-triazol-4-yl)isophthalic acid is 16 mM;

[0017] The concentration of the aqueous solution of sodium citrate is 38.8 mM.

[0018] The prepared functionalized gold nanoparticles aqueous solution was mixed with 2+ The standard solution reaction was carried out, and the standard colorimetric cards with different copper ion concentrations were made according to the color change of the solution (such as Figure 3 The sample to be tested reacts with the gold nanoparticle aqueous solution, and the color of the sample solution is compared with the standard card for on-site naked eye colorimetric detection of copper ions in the sample to be tested under different environments.

[0019] The prepared functionalized gold nanoparticles aqueous solution was mixed with 2+ The peak position and intensity changes of the surface plasmon resonance absorption peak of gold nanoparticles in the solution after the reaction were tested by UV-visible absorption spectroscopy (such as Figure 4 As shown), including the experimental results of the blank sample, the intensity ratio of the SPR resonance absorption peak at the wavelength corresponding to the peak is plotted against the concentration of the copper ion solution to draw a standard curve (as shown Figure 5 The sample to be tested reacts with the gold nanoparticle aqueous solution, and the UV-visible absorption spectrum test results are substituted into the standard curve for comparison and calculation to achieve quantitative detection of copper ions.

[0020] The detection limit of copper ions by naked eyes is 120.0 μM, and that by UV-visible spectroscopy is 0.569 μM.

[0021] The sample to be tested can be lake water, river water, or drinking water.

[0022] The present invention provides a sensor for detecting copper ions and a preparation method thereof, and a method for detecting Cu ions using the prepared sensor. 2+ Ion technology, which is based on the agglomeration mechanism and uses metal Cu 2+ The gold nanoparticles aggregated due to the coordination between the nitrogen atom on the triazole ring of the organic ligand 5-(4H-1,2,4-triazol-4-yl)isophthalic acid, the carboxyl oxygen atom and the metal copper ion. Figure 2), which changes the color of the solution and causes changes in the peak position and absorption intensity of the surface plasmon resonance absorption peak of the gold nanoparticles. Therefore, by directly using the naked eye and UV-visible spectrophotometer to determine whether the sample contains copper ions and the content of the ions, it is possible to quickly detect whether the sample contains copper ions and determine the content of the ions, thereby achieving the goal of Cu in the sample. 2+ Rapid qualitative and quantitative detection of ions.

[0023] Compared with the prior art, the present invention is characterized in that:

[0024] The present invention synthesizes a functionalized gold nanocolorimetric sensor modified with 5-(4H-1,2,4-triazole-4-yl)isophthalic acid and can be used to detect metallic copper ions in water. The method is simple to operate, has readily available raw materials, is low in cost, has fast detection speed, high sensitivity and specificity, and can be observed on-site by naked-eye colorimetry. The specific advantages of this work are: ① The naked-eye detection limit (LOD) of copper ions is 120.0 μM, the UV-visible spectrum detection limit is 0.569 μM, and the linear relationship is good (R 2 =0.96); ② No further processing of gold nanoparticles is required, and the response time is short; ③ Strong anti-interference ability. This detection technology is suitable for Cu in lake water, river water, drinking water and other complex systems. 2+ The rapid detection of ions has a wide range of application value.

[0025] The modifier 5-(4H-1,2,4-triazol-4-yl)isophthalic acid used in the present invention has multiple conformations and can form a variety of hydrogen bonds through its carboxyl oxygen atoms and the nitrogen atoms on the triazole ring. The coordinating oxygen and nitrogen atoms in the modifier can form specific bonding interactions with divalent copper ions, resulting in unique detection parameters for the prepared sensor. The modifier, through its coordinating atoms, can form specific bonding interactions with the synthesized gold nanoparticles, imparting unique stability to the gold nanoparticles. In the absence of copper ions, the gold nanoparticles do not aggregate. When the target ion is added, the nitrogen atom on the triazole ring in 5-(4H-1,2,4-triazole-4-yl)isophthalic acid will coordinate with the copper ion, and the carboxyl group in 5-(4H-1,2,4-triazole-4-yl)isophthalic acid will connect the gold nanoparticles. 5-(4H-1,2,4-triazole-4-yl)isophthalic acid is like a bridge, linking the gold nanoparticles with the target metal ions, causing the gold nanoparticle solution to be in an aggregated state at this time, visible to the naked eye, and the color changes from wine red to gray-blue. These specific performance parameters enable the prepared sensor to have specific detection performance parameters, so that the test results have specific sensitivity, selectivity and detection limit. The naked eye detection limit of copper ions is 120μM, and the ultraviolet-visible spectrum detection limit is 0.569μM. Therefore, the technical solution formed by the present invention has unique detection technology parameters and has specific application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a TEM image provided by Example 1 of the present invention, and the particle diameter ranges from 10 to 15 nm.

[0027] Figure 2 The functionalized gold nanoparticles aqueous solution prepared by the present invention is added with Cu 2+ TEM image of the aggregated structure.

[0028] Figure 3 The present invention provides standard colorimetric cards (100-200 μM) with different copper ion concentrations.

[0029] Figure 4 The UV-visible absorption spectra are measured when copper ion standard solutions of different concentrations provided by the present invention are added to the prepared functionalized gold nanoparticle aqueous solution.

[0030] Figure 5 The present invention provides a standard curve for testing copper ion concentration.

[0031] Figure 6 Colorimetric photographs of the selectivity experiments provided by the present invention.

[0032] Figure 7 The selectivity experiment diagram provided by the present invention shows the UV-visible spectra of different ions. The horizontal axis is the wavelength and the vertical axis is the corresponding absorbance value A. 651nm / A 522nm ratio.

[0033] Figure 8 This is a colorimetric photograph of the anti-interference experiment provided by the present invention.

[0034] Figure 9 This is the anti-interference experimental diagram provided by the present invention, showing the ultraviolet spectrum of the mixed ion solution composed of copper ions and various different ions. The horizontal axis is the wavelength and the vertical axis is the corresponding absorbance value A 651nm / A 522nm ratio. DETAILED DESCRIPTION

[0035] The present invention is further described below through specific examples.

[0036] Add tetrahydrate chloroauric acid aqueous solution to a three-necked flask, heat and stir until boiling, quickly add sodium citrate aqueous solution, continue stirring and react for 15 to 20 minutes, the solution color gradually changes from light yellow to dark purple and finally to wine red, and then stand and cool to room temperature to obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C for later use;

[0037] The prepared solution was diluted half with deionized water, and then 5-(4H-1,2,4-triazol-4-yl)isophthalic acid was added as a modifier to prepare a functionalized gold nanoparticle aqueous solution, which is the sensor for detecting copper ions, abbreviated as TABDC@AuNPs. The sensor can be used to detect copper ions in the sample to be tested.

[0038] Preparation of copper ion standard cards:

[0039] Step (1): Add 1.0 mL of 12.5 mM chloroauric acid tetrahydrate and 49 mL of ultrapure water to a round-bottom flask to obtain a 0.25 mM chloroauric acid aqueous solution, heat to boiling while stirring, quickly add 2.5 mL of a 38.8 mM sodium citrate aqueous solution, react for 15 to 20 minutes, the solution color gradually changes from light yellow to wine red, and cool to room temperature, dilute the above-prepared solution by half with deionized water to obtain a gold nanoparticle aqueous solution, and store it in a refrigerator at 4°C for later use; when detecting copper ions, take the above 0.8 mL of prepared gold nanoparticle aqueous solution and 0.1 mL of 16 mM 5-(4H-1,2,4-triazol-4-yl)isophthalic acid (modifier) were added to a detection tube at a volume ratio of 8:1, and the pH value of the reaction mixture solution was adjusted to 5 to obtain a functionalized gold nanoparticle aqueous solution modified with 5-(4H-1,2,4-triazol-4-yl)isophthalic acid, which is the sensor for detecting copper ions. The sensor can be used to detect copper ions in a sample to be tested.

[0040] Step (2): Prepare a series of copper ion standard aqueous solutions with different concentrations using deionized water and copper ion standard solution, with the concentrations being 100 μM, 110 μM, 120 μM, 130 μM, 140 μM, 150 μM, 160 μM, 170 μM, 180 μM, 200 μM and 300 μM, respectively. Take 0.1 mL of copper ion standard solution with different concentrations and add it to 0.9 mL of functionalized gold nanoparticle aqueous solution prepared in step (1) above. Let it stand for a period of time, and the copper ions will coordinate with the organic ligand 5-(4H-1,2,4-triazole-4-yl)isophthalic acid modified on the surface of the gold nanoparticles to cause the gold nanoparticles to aggregate ( Figure 2 ), and the color of the reaction solution changes. According to the different colors reflected by different solution concentrations, a standard colorimetric card with gradient copper ion concentration is obtained, including a card with blank test results ( Figure 3 ).

[0041] Draw the copper ion standard curve:

[0042] The copper ion standard solutions of different concentrations were added to the functionalized gold nanoparticle aqueous solution modified with 5-(4H-1,2,4-triazole-4-yl)isophthalic acid, and the solution was allowed to stand. The peak position and intensity of the surface plasmon resonance absorption peak of the gold nanoparticles in each reaction solution within the wavelength range of 400-800 nm were measured. The spectrum was plotted with the wavelength as the abscissa and the sample absorbance as the ordinate. Figure 4 ) and record the UV-visible spectrum absorbance ratio at the two peaks of 651nm and 522nm. Use the concentration of the standard sample as the horizontal axis and the absorbance ratio as the vertical axis to draw a standard curve ( Figure 5 ), the linear equation of the copper ion solution standard curve was obtained by linear fitting: in the copper ion concentration range of 100-200 μM, Y=00.25231+0.00527X, R 2 =0.96.

[0043] Different concentrations of copper ions were detected using standard cards and standard curves. The naked eye detection limit was 120.0 μM, and the UV-visible spectrum detection limit was 0.569 μM. The calculation formula for the UV-visible spectrum detection limit was 3×σ / S, where σ is the standard deviation and S is the slope.

[0044] Selective experiments

[0045] In order to investigate the selectivity of the prepared sensor (functionalized gold nanoparticles aqueous solution) for copper ion detection, 15 different types of ions (500 μM: Fe 2+ 、Fe 3+ 、Mn 2+ 、Cd 2+ 、Ba 2+ 、Zn 2+ 、Ni 2+ 、Co 2+ , Pb 2+ 、Sr 2+ , K + 、Sn 2+ 、Na + , Ca 2+ ; 150μM:Cu 2+ ) were added to the prepared functionalized gold nanoparticles (TABDC@AuNPs) aqueous solution, and the obtained colorimetric display was shown in FIG Figure 6 As shown, the solution containing copper ions can functionalize the gold nanoparticle aqueous solution to change its color from wine red to gray-blue, while the other 14 ions cannot change the color of the functionalized gold nanoparticle aqueous solution, and its color remains the same as the blank sample, which is wine red. Figure 7 It can be seen that the copper ion (A 651nm / A 522nmThe UV spectrum of the sample was significantly different from that of the blank sample and the absorbance ratio of the sample containing only other interfering ions. These results indicate that the sensor has excellent selectivity for copper ion detection.

[0046] Anti-interference experiment

[0047] According to actual detection needs, the detection method also investigated the anti-interference performance of the prepared sensor for copper ion detection. 0.05mL of 150μM copper ion solution was mixed with 0.05mL of 500μM solutions of 14 other ions to obtain 14 mixed ion solutions containing copper ions and other interferences. The results showed that the color of the mixed ion solution containing copper ions and other interferences changed, which was very different from the color of the blank solution ( Figure 8 ). Figure 9 It shows that after a mixed ion solution containing copper ions and other interfering ions is added to the functionalized AuNPs solution, its UV spectrum is significantly different from the absorption ratio of the blank sample, indicating that the prepared sensor has no effect on copper ion detection in the presence of other ions and has strong anti-interference performance.

[0048] Cu 2+ Ion detection example

[0049] Example 1

[0050] Add 50 mL of 0.25 mM chloroauric acid aqueous solution to a round-bottom flask, stir and heat until boiling, quickly add 2.5 mL of 38.8 mM sodium citrate aqueous solution, and after 20 minutes of reaction, the color of the solution gradually changes from light yellow to wine red. Let it stand and cool to room temperature to obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C until use.

[0051] The prepared solution was diluted to half with deionized water, and then 0.8 mL of the solution and 0.1 mL of 16 mM 5-(4H-1,2,4-triazole-4-yl)isophthalic acid were added to a detection tube in a volume ratio of 8:1, and the pH value of the reaction mixture was adjusted to 5 to prepare a functionalized gold nanoparticle aqueous solution, which is the sensor for detecting copper ions. The sensor can be used to detect copper ions in a sample to be tested. The morphology of the prepared functionalized gold nanoparticles was observed by TEM, and the results showed that the diameter of the functionalized gold nanoparticles ranged from 10 to 15 nm ( Figure 1 Finally, 0.1 mL of the copper ion sample to be tested was added to perform a copper ion content test experiment.

[0052] Example 2

[0053] Add 20 mL of 0.25 mM chloroauric acid aqueous solution to a round-bottom flask, stir and heat until boiling, quickly add 1.0 mL of 38.8 mM sodium citrate aqueous solution, and after 20 minutes of reaction, the color of the solution gradually changes from light yellow to wine red. Let it stand and cool to room temperature to obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C until use.

[0054] The prepared solution was diluted half with deionized water, and then 0.8 mL of the above solution and 0.1 mL of 16 mM 5-(4H-1,2,4-triazol-4-yl)isophthalic acid were added to the test tube in a volume ratio of 8:1. The pH value of the reaction mixture was adjusted to 5 to prepare a functionalized gold nanoparticle aqueous solution. The morphology of the prepared functionalized gold nanoparticles was observed by TEM. Finally, 0.1 mL of the copper ion-containing sample to be tested was added to perform a copper ion content test experiment.

[0055] Example 3

[0056] Add 15 mL of 0.25 mM chloroauric acid aqueous solution to a round-bottom flask, stir and heat until boiling, quickly add 0.75 mL of 38.8 mM sodium citrate aqueous solution, and after 20 minutes of reaction, the color of the solution gradually changes from light yellow to wine red. Let it stand and cool to room temperature to obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C until use.

[0057] The prepared solution was diluted half with deionized water, and then 0.8 mL of the above solution and 0.1 mL of 16 mM 5-(4H-1,2,4-triazol-4-yl)isophthalic acid were added to the test tube in a volume ratio of 8:1. The pH value of the reaction mixture was adjusted to 5 to prepare a functionalized gold nanoparticle aqueous solution. The morphology of the prepared functionalized gold nanoparticles was observed by TEM. Finally, 0.1 mL of the copper ion-containing sample to be tested was added to perform a copper ion content test experiment.

[0058] Example 4

[0059] "Lake Water" 2+ Detection of ions

[0060] (a) Take 0.1 mL of the actual lake water sample as blank solution A;

[0061] (b) Take 0.1 mL of the actual lake water sample and add copper ion standard solution to prepare a 130 μM copper ion solution as test solution B;

[0062] (c) The blank solution A and the test solution B (0.1 mL each) were added to 0.9 mL of the gold nanoparticle aqueous solution prepared in Example 1. The color change was observed for 2 minutes and compared with the standard card to detect copper ions.

[0063] If the solution to be tested changes color, copper ions are present in the water sample to be tested. The concentration of the sample to be tested can be determined based on the standard colorimetric card. Alternatively, the UV-visible absorption spectrum of the solution to be tested can be obtained. If the intensity and position of the UV-visible absorption peak change, copper ions are present in the solution to be tested. The absorbance ratio at the peak is substituted into the standard curve to calculate and determine the copper ion concentration in the lake water sample to be tested. The test results are shown as follows:

[0064] The color of the blank group reaction solution A was wine red;

[0065] The color of the test sample reaction solution B turns gray-blue;

[0066] The UV-visible absorption spectrometer was used to measure the UV-visible absorption peak intensity and position of the blank reaction solution.

[0067] The Cu content was determined by UV-visible absorption spectrometer. 2+ Ion A of the lake water sample B to be tested 651nm / A 522nm The ratio is 0.94, and Cu 2+ The linear equation of the ion solution standard curve is Y = 0.25231 + 0.00527X, and X = 131 can be calculated, that is, Cu 2+ The concentration of the ion was 131 μM.

[0068] Example 5

[0069] "River Water" 2+ Detection of ions

[0070] (a) Take 0.1 mL of the actual river water sample as blank solution A;

[0071] (b) Take 0.1 mL of the actual river water sample and add the copper ion standard solution to prepare a 150 μM copper ion solution as the test solution B;

[0072] (c) The blank solution A and the test solution B (0.1 mL each) were added to 0.9 mL of the gold nanoparticle aqueous solution prepared in Example 1. The color change was observed for 2 minutes and compared with the standard card to detect copper ions.

[0073] If the color of the solution to be tested changes, copper ions are present in the water sample to be tested. The concentration of the sample to be tested can be determined based on the standard colorimetric card. Alternatively, the UV-visible absorption spectrum of the solution to be tested can be obtained. If the intensity and position of the UV-visible absorption peak change, copper ions are present in the solution to be tested. The absorbance ratio at the peak is substituted into the standard curve to calculate and determine the copper ion concentration in the river water sample to be tested. The test results are shown as follows:

[0074] The color of the blank group reaction solution A was wine red;

[0075] The color of the test sample reaction solution B turns gray-blue;

[0076] The UV-visible absorption spectrometer was used to measure the UV-visible absorption peak intensity and position of the blank reaction solution.

[0077] The Cu content was determined by UV-visible absorption spectrometer. 2+ Ion A of the river water sample B to be tested 651nm / A 522nm The ratio is 1.05, and Cu 2+ The linear equation of the ion solution standard curve is Y = 0.25231 + 0.00527X, and X = 151 can be calculated, that is, Cu 2+ The concentration of the ion is 151 μM.

[0078] Example 6

[0079] Cu in drinking water 2+ Detection of ions

[0080] (a) Take 0.1 mL of the actual drinking water sample as blank solution A;

[0081] (b) Take 0.1 mL of an actual drinking water sample and add a copper ion standard solution to prepare a 170 μM copper ion solution, which serves as test solution B.

[0082] (c) The blank solution A and the test solution B (0.1 mL each) were added to 0.9 mL of the gold nanoparticle aqueous solution prepared in Example 1. The color change was observed for 2 minutes and compared with the standard card to detect copper ions.

[0083] If the solution to be tested changes color, copper ions are present in the water sample to be tested. The concentration of the sample to be tested can be determined based on the standard colorimetric card. Alternatively, the UV-visible absorption spectrum of the solution to be tested can be obtained. If the intensity and position of the UV-visible absorption peak change, copper ions are present in the solution to be tested. The absorbance ratio at the peak is substituted into the standard curve to calculate and determine the copper ion concentration in the lake water sample to be tested. The test results are shown as follows:

[0084] The color of the blank group reaction solution A was wine red;

[0085] The color of the test sample reaction solution B turns gray-blue;

[0086] The UV-visible absorption spectrometer was used to measure the UV-visible absorption peak intensity and position of the blank reaction solution.

[0087] The Cu content was determined by UV-visible absorption spectrometer. 2+ Ion A of the tested drinking water sample B 651nm / A 522nm The ratio is 1.16, and Cu 2+ The linear equation of the ion solution standard curve is Y = 0.25231 + 0.00527X, and X = 172 can be calculated, that is, Cu 2+ The concentration of the ion is 172 μM.

[0088] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, combinations, and improvements made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a sensor for detecting copper ions, characterized in that: The preparation method comprises the following steps: A tetrahydrated chloroauric acid (HAuCl4·4H2O) aqueous solution was added to a round-bottom flask, heated and stirred until boiling, and an aqueous solution of sodium citrate was added. The solution was stirred and reacted for 15 to 20 minutes. The color of the solution gradually changed from light yellow to purple-black and finally to wine red. The solution was allowed to cool to room temperature to obtain an aqueous solution of gold nanoparticles, which was stored in a refrigerator at 4°C for later use. The prepared gold nanoparticle aqueous solution is diluted to half with deionized water, and 5-(4H-1,2,4-triazol-4-yl)isophthalic acid at an optimal concentration is added as a modifier to prepare a functionalized gold nanoparticle aqueous solution, which is the sensor for detecting copper ions and magnesium ions. The sensor can be used to detect copper ions and magnesium ions in a sample to be tested; The copper ion is Cu 2+ ion; The concentration of the tetrahydrate chloroauric acid aqueous solution is 0.25 mM; The pH range of the gold nanoparticle aqueous solution is 3 to 10; The concentration of the 5-(4H-1,2,4-triazol-4-yl)isophthalic acid is 16 mM; The concentration of the sodium citrate aqueous solution is 38.8 mM.

2. A sensor prepared by the preparation method according to claim 1, characterized in that: The sensor is stable, non-toxic, has strong anti-interference performance and high sensitivity.

3. Use of the sensor prepared by the preparation method according to claim 1, characterized in that: The sensor is used for rapid detection of copper ions in lake water, river water, and drinking water, or for detecting copper ion concentration in sewage. The naked eye detection limit is 120.0 μM, and the ultraviolet-visible spectrum detection limit is 0.569 μM.

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