Preparation method and application of Prussian blue nanocage
By converting iron-nickel Prussian blue nanocubes into nanocages, the problem of low catalytic activity of existing Prussian blue nanomaterials is solved, and higher catalytic activity and application potential are achieved.
Patent Information
- Application Number
- CN202510149303.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-11
- Publication Date
- 2025-05-13
AI Technical Summary
The existing Prussian blue nanomaterials have low catalytic activity, which limits their application in analytical and detection.
By dispersing potassium ferricyanide and nickel salt in a citrate solution, an iron-nickel Prussian blue nanocube was obtained and chemically etched in an acidic solution of diol to be converted into a Prussian blue nanocage.
The specific surface area, pore volume and iron ions content of Prussian blue nanomaterials have been improved, and their peroxidase mimicry activity has been significantly enhanced, which is suitable for enhancing nanoenzyme activity.
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Figure CN119976887A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of biological nanomaterials, and in particular to a preparation method and application of a Prussian blue nanocage. Background Art
[0002] Excess Hg 2+ It can cause serious damage to the brain, kidneys, cardiovascular, nervous and endocrine systems, etc., and poses significant health risks even at extremely low concentrations. Although traditional detection methods such as atomic absorption spectroscopy, inductively coupled plasma mass spectrometry and high performance liquid chromatography have high sensitivity, these methods are usually complex, expensive and not suitable for field application. Therefore, it is necessary to develop low-cost, rapid and sensitive Hg 2+ Detection methods are urgently needed.
[0003] So far, a variety of nanomaterials similar to natural enzymes have been developed, such as platinum nanoparticles, magnetic nanoparticles, Prussian blue nanoparticles and other nanomaterials, which are used in environmental analysis and detection, biological analysis, disease treatment and antibacterial activity. Among these nanomaterials, Prussian blue nanoparticles have attracted great attention due to their biocompatibility, high chemical stability and easy surface modification. However, the relatively low catalytic activity of Prussian blue nanomaterials limits their application in analytical detection. Summary of the invention
[0004] The invention provides a preparation method and application of a Prussian blue nano cage, so as to solve the technical problem of low catalytic activity of Prussian blue nano materials in the prior art.
[0005] To achieve the above object, the technical solution provided by the present invention is as follows:
[0006] The first aspect of the present invention provides a method for preparing a Prussian blue nanocage, 1. comprising the following steps: S1. dispersing potassium ferrocyanide and nickel salt in a citrate solution, and obtaining iron-nickel Prussian blue nanocubes after aging; S2. drying the iron-nickel Prussian blue nanocubes obtained in step S1, dispersing them in an acidic solution of a diol, and obtaining a Prussian blue nanocage after chemical etching.
[0007] Furthermore, the diol in step S2 is selected from one or more of ethylene glycol, propylene glycol, and butanediol.
[0008] Furthermore, the acidic solution in step S2 is selected from one or more of acetic acid solution, hydrochloric acid solution, sulfuric acid solution, and nitric acid solution.
[0009] Furthermore, the mass volume ratio of the iron-nickel Prussian blue nanocubes and the acidic solution of the diol after drying in step S2 is 1:0.9-2.4 g / L.
[0010] Furthermore, in step S2, the temperature of chemical etching is 140° C. to 220° C., and the time of chemical etching is 4 h to 12 h.
[0011] Furthermore, in the step S1, the mass ratio of the potassium ferrocyanide to the nickel salt is 1:0.1-20.
[0012] Furthermore, in step S1, the aging temperature is 15° C. to 35° C., and the aging time is 12 h to 24 h.
[0013] Furthermore, the particle size of the iron-nickel Prussian blue nanocube after drying is 110nm-160nm; the particle size of the Prussian blue nanocage is 90nm-140nm.
[0014] The second aspect of the present invention provides the use of the Prussian blue nanocage prepared by the above preparation method in the detection of mercury ions.
[0015] Furthermore, the application includes the following steps: adding L-cysteine to sewage, and then adding 3,3ˊ,5,5ˊ-tetramethylbenzidine hydrochloride, hydrogen peroxide and the Prussian blue nanocage respectively, and qualitatively detecting the mercury ions in the sewage according to the color change of the solution after the reaction.
[0016] Furthermore, the step also includes using an enzyme marker to measure the absorbance of the solution after the reaction at 652nm, and quantitatively detecting the mercury ion concentration in the sewage according to a quantitative calibration curve of the mercury ion concentration.
[0017] The preparation method of the Prussian blue nanocage provided by the present invention uses diol as a reducing agent and auxiliary agent and an acidic solution as an etchant, and successfully realizes the transformation of iron-nickel Prussian blue nanocubes into nanocages. Compared with nanocubes, the specific surface area, pore volume and iron ion content of the above-mentioned nanocages are further improved, thereby showing significantly enhanced peroxidase simulation activity, and can be used as a solution for enhancing nanozyme activity. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0019] Figure 1 The SEM and TEM images of the iron-nickel Prussian blue nanocube and the iron-nickel Prussian blue nanocage of Example 1 of the present invention;
[0020] Figure 2 The XRD patterns of the iron-nickel Prussian blue nanocubes and iron-nickel Prussian blue nanocages and the standard spectrum of potassium ferrocyanide in Example 1 of the present invention;
[0021] Figure 3 N is the N of the iron-nickel Prussian blue nanocube and the iron-nickel Prussian blue nanocage in Example 1 of the present invention. 2 Adsorption-desorption isotherms and pore size distribution diagrams;
[0022] Figure 4 Figure 2 shows the TMB-H mediated by different concentrations of FeNi Prussian blue nanocubes (Figure a) and FeNi Prussian blue nanocages (Figure b) in the embodiments of the present invention. 2 O 2 Photographs and UV-visible spectra of the colorimetric reaction solutions;
[0023] Figure 5 In the embodiment of the present invention, Hg 2+ The trend of the color intensity of the solution with changing concentration (Figure a) and Hg 2+ The colorimetric detection standard curve (Figure b);
[0024] Figure 6 Co is added to the iron-nickel Prussian blue nanocage of the embodiment of the present invention. 2+ Mg 2+ , K + 、Na + Sn 2+ , Ca 2+ Cr 3+ , Pb 2+ 、Zn 2+ 、Ni 2+ Changes in the absorbance of the interfering substances at a wavelength of 652nm;
[0025] Figure 7 This is an experimental diagram of the recovery rate of mercury ions using the iron-nickel Prussian blue nanocage according to an embodiment of the present invention. DETAILED DESCRIPTION
[0026] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0027] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.
[0028] In a first aspect of an embodiment of the present application, a method for preparing a Prussian blue nanocage is provided, comprising the following steps: S1, dispersing potassium ferrocyanide and nickel salt in a citrate solution, and obtaining iron-nickel Prussian blue nanocubes after aging; S2, drying the iron-nickel Prussian blue nanocubes obtained in step S1 and dispersing them in an acidic solution of a diol, and obtaining a Prussian blue nanocage after chemical etching.
[0029] In the embodiment of the present application, the nickel salt is selected from one or more of nitrate, chloride, and acetate. Citrate is selected from one or more of sodium salt, potassium salt, and magnesium salt. There are many methods for dispersing potassium ferrocyanide and nickel salt in a citrate solution, such as stirring or ultrasound. The above-mentioned dispersion step is carried out at room temperature. The Prussian blue nanocage obtained after chemical etching in step S2 is an iron-nickel Prussian blue nanocage. The solution after chemical etching is centrifuged, washed, and dried to obtain an iron-nickel Prussian blue nanocage.
[0030] The preparation method of the Prussian blue nanocage provided in the embodiment of the present application uses diol as a reducing agent and auxiliary agent and an acidic solution as an etchant to successfully achieve the transformation of iron-nickel Prussian blue nanocubes to nanocages. Compared with nanocubes, the specific surface area, pore volume and iron ion content of the above-mentioned nanocages are further improved. The unique hollow cube structure of the nanocage improves the catalytic activity of the nanomaterial, thereby showing a significantly enhanced peroxidase simulation activity, which can be used as a solution to enhance the activity of nanoenzymes.
[0031] Specifically, the diol in step S2 is selected from one or more of ethylene glycol, propylene glycol, and butanediol. The acidic solution in step S2 is selected from one or more of acetic acid solution, hydrochloric acid solution, sulfuric acid solution, and nitric acid solution.
[0032] In some embodiments, the mass volume ratio of the dried iron-nickel Prussian blue nanocubes to the acidic solution of the diol in step S2 is 1: 0.9-2.4 g / L. Specifically, in step S2, if the added mass of the dried iron-nickel Prussian blue nanocubes is 5-100 mg, the concentration of ethylene glycol is 5-20 mol / L, and the volume of ethylene glycol is 10-80 mL; the concentration of the acetic acid solution is 5-20 mol / L, and the volume of the acetic acid solution is 2-10 mL.
[0033] In some embodiments, the mass ratio of potassium ferrocyanide to nickel salt in step S1 is 1: 0.1 to 20. Specifically, if the mass of potassium ferrocyanide added in step S1 is 0.05 g to 1 g, the mass of nickel nitrate added is 0.1 g to 1 g, and the mass of trisodium citrate added is 0.1 g to 2 g.
[0034] Specifically, the aging temperature in step S1 is 15° C. to 35° C., and the aging time is 12 hours to 24 hours. The chemical etching temperature in step S2 is 140° C. to 220° C., and the chemical etching time is 4 hours to 12 hours.
[0035] A second aspect of the embodiments of the present application provides the use of the Prussian blue nanocage prepared by the above preparation method in mercury ion detection.
[0036] The present invention uses the prepared Prussian blue nanocages to establish a sensing platform for colorimetric detection of mercury ions. The platform has a wide linear detection range and a low detection limit for mercury ions, and has excellent selectivity and anti-interference performance, which will have broad application potential in biosensing and biotechnology.
[0037] Specifically, the application of Prussian blue nanocages in mercury ion detection includes the following steps: adding L-cysteine to sewage, and then adding 3,3ˊ,5,5ˊ-tetramethylbenzidine hydrochloride, hydrogen peroxide and Prussian blue nanocages respectively, and qualitatively detecting the mercury ions in the sewage according to the color change of the solution after the reaction.
[0038] The Prussian blue nanocage of the embodiment of the present application can catalyze 3,3',5,5'-tetramethylbenzidine hydrochloride (abbreviated as TMB) to make the solution color. L-cysteine can inhibit the occurrence of the above-mentioned catalytic oxidation reaction due to its reducing property. Once mercury ions exist, they will undergo a special complexation with L-cysteine, causing L-cysteine to lose its reducing property. Therefore, the Prussian blue nanocage can effectively promote the oxidation of 3,3',5,5'-tetramethylbenzidine hydrochloride to dark blue oxide. The mercury ion content can be preliminarily judged based on the color of the solution of the color development system.
[0039] As the content of mercury ions increases, the absorption value of the color developing system at a wavelength of 652nm increases, and the change in the above absorbance value when the content of mercury ions is changed can draw a mercury ion quantitative standard curve. The content of mercury ions in sewage can be detected by the above standard curve. Further, the absorbance of the solution after the reaction at 652nm is measured using an ELISA instrument, and the mercury ion concentration in the sewage is quantitatively detected according to the quantitative calibration curve of the mercury ion concentration. The Prussian blue nanocage of the embodiment of the present application shows a good catalytic effect in the application of determining the content of mercury ions.
[0040] The present application is described in more detail below with specific examples. All reagents in the following examples are commercially available.
[0041] Example 1
[0042] A method for preparing a Prussian blue nanocage comprises the following steps:
[0043] 1. Dissolve 0.264g potassium ferrocyanide in 60mL ultrapure water and add it to 40mL ultrapure water solution containing 0.348g nickel nitrate and 0.441g trisodium citrate. The mixed 100mL solution was aged for 24 hours under magnetic stirring at room temperature. The yellow precipitate obtained after aging was collected by centrifugation and washed three times with ethanol and ultrapure water respectively. The obtained iron-nickel Prussian blue nanocubes were then vacuum dried at 60°C for 10h.
[0044] 2. Disperse 10 mg of the above-mentioned iron-nickel Prussian blue nanocubes in a mixed solution consisting of ethylene glycol (40 mL, 17 mol / L) and acetic acid (5 mL, 17.5 mol / L). After thorough mixing, a suspension is obtained, which is transferred to a 60 mL autoclave and heated at 180°C for 8 h. After the autoclave is cooled to room temperature, the product is collected by centrifugation, washed with deionized water, and finally dried at 60°C overnight to obtain a blue iron-nickel Prussian blue nanocage.
[0045] Figure 1 a is a SEM image of the iron-nickel Prussian blue nanocube of Example 1; Figure 1 c is the TEM image of the iron-nickel Prussian blue nanocube of Example 1. Figure 1 b is a SEM image of the iron-nickel Prussian blue nanocage of Example 1; Figure 1 d is a TEM image of the iron-nickel Prussian blue nanocage of Example 1. By comparing the above SEM and TEM images, it can be clearly observed that the hollow cage structure formed in the ethylene glycol solution after the cube is etched with acetic acid.
[0046] Figure 2It can be seen that the characteristic XPS peak of the iron-nickel Prussian blue nanocubes is consistent with the standard spectrum of nickel ferrocyanide (JCPDS, PDF No.46-0906). After etching at 180°C for 8 hours in ethylene glycol solvent, the peak of the iron-nickel Prussian blue nanocage shifts to a higher diffraction angle, and its peak is consistent with the standard reflection of nickel ferrocyanide (JCPDS, PDF No.14-0291), which is attributed to the reducing properties of ethylene glycol.
[0047] Reference Figure 3 The specific surface area and pore volume of Fe-Ni Prussian blue nanocages are 332.99 m 2 / g and 0.51cm 3 / g, which is much higher than the specific surface area and pore volume of Fe-Ni Prussian blue nanocubes (33.89m 2 / g and 0.13cm 3 / g), which is attributed to the size reduction and the formation of hollow structure. The pore size distribution of Fe-Ni Prussian blue nanocages is 5-50nm, indicating that it has a porous structure, which is consistent with the results of SEM and TEM images.
[0048] Example 2
[0049] A method for preparing a Prussian blue nanocage comprises the following steps:
[0050] 1. Dissolve 0.1g potassium ferrocyanide in 60mL ultrapure water and add it to 40mL ultrapure water solution containing 0.13g nickel nitrate and 0.167g trisodium citrate. The mixed 100mL solution was aged for 12 hours under magnetic stirring at room temperature. The yellow precipitate obtained after aging was collected by centrifugation and washed three times with ethanol and ultrapure water respectively. The obtained iron-nickel Prussian blue nanocubes were then vacuum dried at 60°C for 10h.
[0051] 2. Disperse 5 mg of the above-mentioned iron-nickel Prussian blue nanocubes in a mixed solution consisting of propylene glycol (10 mL, 5 mol / L) and hydrochloric acid (2 mL, 5 mol / L). After thorough mixing, a suspension is obtained, which is transferred to a 60 mL autoclave and heated at 140°C for 12 h. After the autoclave is cooled to room temperature, the product is collected by centrifugation, washed with deionized water, and finally dried at 60°C overnight to obtain a blue iron-nickel Prussian blue nanocage.
[0052] Example 3
[0053] A method for preparing a Prussian blue nanocage comprises the following steps:
[0054] 1. Dissolve 0.528g potassium ferrocyanide in 60mL ultrapure water and add it to 40mL ultrapure water solution containing 0.7g nickel nitrate and 0.88g trisodium citrate. The mixed 100mL solution was aged for 16 hours under magnetic stirring at room temperature. The yellow precipitate obtained after aging was collected by centrifugation and washed three times with ethanol and ultrapure water respectively. The obtained iron-nickel Prussian blue nanocubes were then vacuum dried at 60°C for 10h.
[0055] 2. Disperse 50 mg of the above-mentioned iron-nickel Prussian blue nanocubes in a mixed solution consisting of butanediol (60 mL, 10 mol / L) and sulfuric acid (8 mL, 15 mol / L). After thorough mixing, a suspension is obtained, which is transferred to a 60 mL autoclave and heated at 160°C for 10 h. After the autoclave is cooled to room temperature, the product is collected by centrifugation, washed with deionized water, and finally dried at 60°C overnight to obtain a blue iron-nickel Prussian blue nanocage.
[0056] Example 4
[0057] A method for preparing a Prussian blue nanocage comprises the following steps:
[0058] 1. Dissolve 0.1g potassium ferrocyanide in 60mL ultrapure water and add it to 40mL ultrapure water solution containing 1g nickel nitrate and 1.8g trisodium citrate. The mixed 100mL solution was aged for 24 hours under magnetic stirring at room temperature. The yellow precipitate obtained after aging was collected by centrifugation and washed three times with ethanol and ultrapure water respectively. The obtained iron-nickel Prussian blue nanocubes were then vacuum dried at 60°C for 10h.
[0059] 2. Disperse 100 mg of the above-mentioned iron-nickel Prussian blue nanocubes in a mixed solution consisting of ethylene glycol (80 mL, 20 mol / L) and nitric acid (10 mL, 20 mol / L). After thorough mixing, a suspension is obtained, which is transferred to a 60 mL autoclave and heated at 220°C for 4 h. After the autoclave is cooled to room temperature, the product is collected by centrifugation, washed with deionized water, and finally dried at 60°C overnight to obtain a blue iron-nickel Prussian blue nanocage.
[0060] The standard substrate 3,3′,5,5′-tetramethylbenzidine hydrochloride was catalyzed in H 2 O 2 The peroxidase-like activity of the material was evaluated by oxidation reaction in the presence of . Specifically, 3,3′,5,5′-tetramethylbenzidine hydrochloride (0.6 mmol / L) and H 2 O 2(3mmol / L) was dissolved in 200μL of sodium acetate / citrate buffer solution to prepare TMB / H 2 O 2 Subsequently, 10 μL of different concentrations (0, 1, 5, 10, 20, 30, 40, 60 μg / mL) of iron-nickel Prussian blue nanocubes or iron-nickel Prussian blue nanocages in Example 1 were added to the mixture to promote the color development reaction. After 30 minutes of incubation, absorbance was measured.
[0061] like Figure 4 As shown, the iron-nickel Prussian blue cube ( Figure 4 a) or Fe-Ni Prussian blue nanocages ( Figure 4 b) As a substitute for the natural enzyme, 2 O 2 At the same concentration of nanomaterials, the characteristic absorption rate of the Fe-Ni Prussian blue nanocage catalytic reaction system is 2.4 times higher than that of the Fe-Ni Prussian blue nanocube catalytic reaction system on average, and the corresponding solution color also supports this result.
[0062] To quantitatively detect Hg 2+ 80 μL of Cys (240 μmol / L) was mixed with different concentrations of Hg 2+ After incubation for 10 min, 100 μL of 1.25 mmol / L TMB, 100 μL of 5.88 mmol / L H 2 O 2 and 10 μL of H-FeNiPBA nanocages (2.5 μg / mL). Subsequently, the absorbance of the reaction solution was measured at 652 nm using an ELISA reader, and the reaction time was 6 min. The standard curve was obtained for reference Figure 5 .
[0063] Following the same procedure, different concentrations of Hg 2+ The real samples were analyzed by introducing the sample into the laboratory tap water (without additional treatment). 2+ Mg 2+ , K + 、Na + Sn 2+ , Ca 2+ Cr 3+ , Pb 2+ 、Zn 2+ 、Ni 2+ Plasma is used as an interferent and its influence on the contrast color signal is measured.
[0064] like Figure 5 As shown, in the range of 0.1 to 42 μmol / L Hg2+ Within the concentration range, the absorbance value increases with Hg 2+ In this range, the absorbance is proportional to Hg 2+ There is a linear correlation between the concentrations ( Figure 5 b) The Hg 2+ The detection limit (LOD) of the sensing platform was determined to be 0.035 μmol / L (S / N = 3), which is significantly lower than the established Hg 2+ To evaluate the selectivity and anti-interference performance, Co 2+ Mg 2+ , K + 、Na + Sn 2+ , Ca 2+ Cr 3+ , Pb 2+ 、Zn 2+ and Ni 2+ Although the concentrations of these interfering ions are higher than Hg 2+ The absorbance changes in these control groups were negligible, indicating that the colorimetric method is effective for Hg in the presence of either single or multiple control ions. 2+ The detection showed good anti-interference performance ( Figure 6 ). Figure 7 The colorimetric method for detecting Hg in tap water samples was studied. 2+ The practicality of 2+ As shown in the figure, the recovery rate of spiked samples was 92.78% to 103.17%, and the relative standard deviation of each concentration level was 4.34% to 6.39% (n=3), indicating that this method can be used to quantitatively evaluate Hg in actual samples. 2+ It has high reliability and repeatability.
[0065] The iron-nickel Prussian blue nanocages prepared in Examples 1 to 4 were used in the above experiments. Despite the differences in preparation conditions and raw material ratios, they all successfully achieved effective detection of the same concentration of standard sample mercury ions (20 μM), and the detection results were 19.77, 20.86, 21.03 and 19.82 μM, respectively, showing good detection consistency and accuracy. These results show that the iron-nickel Prussian blue nanocage has potential application value in mercury ion detection.
[0066] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing a Prussian blue nanocage, characterized in that: The following steps are involved: S1, dispersing potassium ferrocyanide and nickel salt in a citrate solution, and obtaining iron-nickel Prussian blue nanocubes after aging; S2, drying the iron-nickel Prussian blue nanocubes obtained in step S1, dispersing them in an acidic solution of a diol, and chemically etching them to obtain Prussian blue nanocages.
2. The method for preparing the Prussian blue nanocage according to claim 1, characterized in that: The diol in step S2 is selected from one or more of ethylene glycol, propylene glycol and butanediol.
3. The method for preparing the Prussian blue nanocage according to claim 1, characterized in that: The acidic solution in step S2 is selected from one or more of acetic acid solution, hydrochloric acid solution, sulfuric acid solution, and nitric acid solution.
4. The method for preparing the Prussian blue nanocage according to claim 1, characterized in that: The mass volume ratio of the iron-nickel Prussian blue nanocubes and the diol acid solution after drying in step S2 is 1:0.9-2.4 g / L.
5. The method for preparing the Prussian blue nanocage according to claim 1, characterized in that: The temperature of the chemical etching in step S2 is 140° C. to 220° C., and the time of the chemical etching is 4 h to 12 h.
6. The method for preparing the Prussian blue nanocage according to any one of claims 1 to 5, characterized in that: In the step S1, the mass ratio of the potassium ferrocyanide to the nickel salt is 1:0.1-20; and / or, In step S1, the aging temperature is 15° C. to 35° C., and the aging time is 12 h to 24 h.
7. The method for preparing the Prussian blue nanocage according to any one of claims 1 to 5, characterized in that: The particle size of the iron-nickel Prussian blue nanocube after drying is 110nm-160nm; the particle size of the Prussian blue nanocage is 90nm-140nm.
8. Use of the Prussian blue nanocage prepared by the preparation method according to any one of claims 1 to 7 in mercury ion detection.
9. The use according to claim 8, characterized in that: The application comprises the following steps: adding L-cysteine to sewage, and then respectively adding 3,3',5,5'-tetramethylbenzidine hydrochloride, hydrogen peroxide and the Prussian blue nanocage, and qualitatively detecting mercury ions in the sewage according to the color change of the solution after the reaction.
10. The use according to claim 9, characterized in that: The step also includes using an enzyme marker to measure the absorbance of the solution after the reaction at 652nm, and quantitatively detecting the mercury ion concentration in the sewage according to a quantitative calibration curve of the mercury ion concentration.