Qualitative and quantitative analysis method of metal cyanide in water body

Abstract

This invention belongs to the field of water pollutant analysis and detection, and relates to a qualitative and quantitative analysis method for metal cyanides in water. The invention involves loading star-shaped gold nanoparticles onto a silica substrate to obtain a slide. The slide is reacted with standard solutions of different types and concentrations of metal cyanides, and the resulting spectra at specific wavelengths are obtained. A standard curve is then plotted based on the corresponding absorbance. The slide is then reacted with a water sample to be tested, and the sample's spectrum and absorbance at a specific wavelength are obtained. The type of metal cyanide in the water sample is determined based on the degree of fit of the spectrum. The concentration of metal cyanides in the water sample is calculated by substituting the absorbance at the specific wavelength into the standard curve, thus completing the qualitative and quantitative analysis of metal cyanides in the water. The method provided by this invention is simple and rapid. With only a slide required, a small spectroscopic instrument can be used to complete the qualitative and quantitative analysis of metal cyanides in water, enabling rapid on-site detection.

Description

Technical Field

[0001] This invention belongs to the field of water pollutant analysis and detection, and specifically relates to a qualitative and quantitative analysis method for metal cyanides in water. Background Technology

[0002] Metal cyanides are often complexes formed by the combination of one or more cyanide ions with a single transition metal cation. These complexes have a uniform structural formula [M(CN)]. b ] x- M represents a transition metal cation such as Au. + Ag + Cu 2+ Ni 2+ Fe 2+ Co 3+ In this context, b represents the number of cyanide ions bound to the complex, and x represents the anionic valence state of the complex. Metal cyanides are relatively stable under normal conditions, which can lead to persistent water pollution. In some cases, metal cyanides can release cyanide through degradation, causing continued water pollution. Therefore, they are a compound of widespread concern to environmentalists. For example, in water samples with a pH < 9.3, cyanide ions can be converted into highly toxic HCN. Consequently, in addition to the environmental protection and ecological fields, metal cyanides are also of great interest in the mining, precious metal recycling, and metal surface finishing industries.

[0003] Although metal cyanides have important applications in industries such as metallurgy and electroplating, their severe toxicity and difficulty in natural degradation make them extremely harmful to the environment. Therefore, metal cyanides are subject to strict monitoring in current water environmental standards.

[0004] Current analytical methods for metal cyanides in water bodies mainly include spectrophotometry and electrochemical methods. Spectrophotometry requires pretreatment of the water sample, such as acidification and oxidation, followed by the addition of an iron-containing reagent to form a Prussian blue complex. Detection is then performed by spectrophotometric analysis of the absorption in the 600–650 nm wavelength range. Electrochemical methods primarily detect cyanides by monitoring the characteristic current or electrode potential generated during the reduction of metal cyanides. The main principle is to apply a specific potential to the electrode, causing a redox reaction of cyanide. This reaction generates a specific electrical signal, which can be identified to detect the metal cyanides.

[0005] However, spectrophotometry and electrochemical methods still have some limitations in practical applications. For example, spectrophotometric determination of cyanide content requires pretreatment, cannot achieve real-time and rapid results, and is difficult to perform on-site testing. Furthermore, complex aquatic environments (such as the color and turbidity of other substances in the water) can also affect the accuracy of spectrophotometry. To ensure the stability of the colorimetric reaction and facilitate its identification, spectrophotometry is highly dependent on the laboratory environment and cannot be used for on-site analysis. Most importantly, spectrophotometry cannot distinguish between metal cyanides and cyanides; it can only measure the total cyanide content. Therefore, using spectrophotometry to detect the content of metal cyanides in water may lead to inflated results.

[0006] Electrochemical methods also face some challenges. Similar to spectrophotometry, they require real-time monitoring of the characteristic current generated by the reduction of metal cyanides, making the detection process complex and preventing on-site analysis. Furthermore, electrochemical methods are susceptible to interference from other electroactive substances, and the equipment used requires regular maintenance to prevent electrode aging and damage, further increasing the detection cost. Additionally, complex aquatic environments can cause electrode contamination, leading to inaccurate results.

[0007] It is evident that existing qualitative and quantitative analysis methods for metal cyanides in water bodies have some problems. These problems lead to overly complicated detection procedures and biased results.

[0008] Therefore, there is an urgent need in this field for an analytical method for metal cyanides in water that is easy to operate, highly accurate, and can be used for rapid on-site detection. Summary of the Invention

[0009] In view of the shortcomings of the prior art, the present invention provides a qualitative and quantitative analysis method for metal cyanides in water. It can not only solve the problems of complicated detection process, poor analytical efficiency and deviation of analytical results of traditional spectrophotometry, but also solve the problems of electrochemical method being easily affected by electroactive substances and high maintenance cost of electrochemical equipment, and has a wider range of application prospects.

[0010] To achieve this objective, the present invention employs the following technical solution:

[0011] This invention provides a qualitative and quantitative analysis method for metal cyanides in water, comprising the following steps:

[0012] S1. Preparation of star-shaped gold nanoparticle solution;

[0013] S2. The gold nanoparticles in the prepared star-shaped gold nanoparticle solution are loaded onto the surface of a modified silica substrate to obtain a substrate;

[0014] S3. Prepare standard solutions of different types of metal cyanide with gradient concentrations;

[0015] S4. Immerse the slides in different types of metal cyanide gradient concentration standard solutions. After the slides react with the standard solutions, obtain the standard solution slides. Obtain the standard solution spectrum of the standard solution slides and plot the standard curve based on the corresponding absorbance. The standard curve passes through the origin.

[0016] S5. Clean the standard solution slide to obtain a clean slide. Immerse the clean slide in the water sample to be tested. After the clean slide and the water sample to be tested have reacted, obtain the water sample slide. Obtain the water sample spectrum from the water sample slide. Compare the water sample spectrum with the standard solution spectrum. Determine the type of metal cyanide contained in the water sample based on the degree of matching between the two.

[0017] S6. Substitute the absorbance of the water sample slide into the standard curve to obtain the content of metal cyanide in the water sample to be tested, and complete the qualitative and quantitative analysis of metal cyanide in the water.

[0018] Optionally, the method for preparing the star-shaped gold nanoparticle solution includes the following steps:

[0019] S1.1. Mix sodium citrate solution and chloroauric acid solution and react. After the reaction is complete, a solution of spherical gold nanoparticles is obtained.

[0020] S1.2. The spherical gold nanoparticle solution is mixed with chloroauric acid solution, hydrochloric acid, silver nitrate solution and ascorbic acid solution under stirring. After the reaction is completed, the star-shaped gold nanoparticle solution is obtained.

[0021] Optionally, in step S1.1:

[0022] The concentration of the chloroauric acid solution is 2.0–3.0 mM, and the volume is 50–150 mL;

[0023] The concentration of sodium citrate solution is 3-4% (w / v), and the volume is 0.5-1.5 mL.

[0024] Optionally, in step S1.2:

[0025] The concentration of the chloroauric acid solution is 0.05 mM to 0.15 mM, and the volume is 5 to 15 mL.

[0026] The concentration of hydrochloric acid is 0.5–1.5 M, and the volume is 0.5–1.5 μL;

[0027] The concentration of the silver nitrate solution is 1–3 mM, and the volume is 100–200 μL;

[0028] The concentration of ascorbic acid solution is 50–150 mM, and the volume is 25–75 μL.

[0029] Optionally, the method for preparing the slide includes the following steps:

[0030] S2.1. Pre-treat the silica substrate to expose the hydroxyl groups on the surface of the silica substrate;

[0031] S2.2. Clean the pretreated silica substrate and immerse it in an ethanol solution of 3-aminopropyltrimethoxysilane or an ethanol solution of 3-thiolpropyltrimethoxysilane for modification.

[0032] S2.3. The cleaned and modified silica substrate is immersed in a solution of star-shaped gold nanoparticles to load the star-shaped gold nanoparticles and obtain a substrate.

[0033] Optionally, in step S2.2:

[0034] The concentration of 3-aminopropyltrimethoxysilane in the ethanol solution is 2.5%–7.5% (w / w);

[0035] The concentration of 3-thiol-propyltrimethoxysilane in the ethanol solution is 2.5%–7.5% (w / w).

[0036] Optionally, the metal ion in the metal cyanide is Au[(CN)2]. - Ag[(CN)2] - Cu[(CN)4] 2- Ni[(CN)6] 3- Co[(CN)6] 3- Any one of them.

[0037] Optionally, the gradient concentration of the metal cyanide gradient concentration standard solution is 1 to 500 ppm.

[0038] Optionally, the reaction time for immersing the slide in the standard solution is 3 to 5 minutes.

[0039] Optionally, the reaction time for immersing the cleaned slide in the water sample to be tested is 3 to 5 minutes.

[0040] Optionally, three identical water samples are collected for analysis and testing, and the content of metal cyanide in the water samples is taken as the average value of the three tests.

[0041] The beneficial effects of this invention are:

[0042] (1) The method provided by the present invention is simple and fast. It can perform qualitative and quantitative analysis of water samples using a small spectroscopic device with only a slide provided, enabling rapid on-site detection and making it more convenient to use.

[0043] (2) The method provided by the present invention can not only avoid the defects of spectrophotometry, which depends on the laboratory environment and can only analyze the total content of cyanide in the sample, but also avoid the problems of complex detection process, high maintenance cost of precision equipment and high maintenance cost of electrochemical method, and has good practical application value. Attached Figure Description

[0044] Figure 1 The schematic diagram of the color change reaction principle of the slide provided by the present invention.

[0045] Figure 2 This is a flowchart of the testing method of the present invention.

[0046] Figure 3 This is a TEM image of the star-shaped gold nanoparticles prepared in Example 1.

[0047] Figure 4 This is a SEM image of the slide prepared in Example 1.

[0048] Figure 5 The slide prepared in Example 1 and Ag(CN)2 - SEM image after treatment.

[0049] Figure 6 This is a standard curve diagram of the three metal cyanide complex ions in Example 1.

[0050] Figure 7 This is a comparison chart of the spectra of water sample I and water sample II tested in Example 1.

[0051] Figure 8 This is a standard curve diagram of three metal cyanide complex ions in Example 2.

[0052] Figure 9 This is a comparison chart of the spectra of water sample I and water sample II tested in Example 2.

[0053] Figure 10 This is a standard curve diagram of the three metal cyanide complex ions in Example 3.

[0054] Figure 11 This is a comparison chart of the spectra of water sample I and water sample II tested in Example 3.

[0055] Figure 12 This is a comparison of the spectra of the slide obtained in Example 1 before and after reaction with natural water sample and reaction with natural water sample + oxidant.

[0056] Figure 13 The unreacted, reacted with ultrapure water, and reacted with Ag[(CN)2] samples from the same batch obtained in Example 1 are shown. - Comparison of slide images after the reaction.

[0057] Figure 14 The slide obtained in Example 1 and Ag(CN)2 - A comparison of the spectra before and after the reaction.

[0058] Figure 15 The slide obtained in Example 1 and Ag(CN)2 - Thermodynamic image of gold in the corresponding region before the reaction.

[0059] Figure 16 The slide obtained in Example 1 and Ag(CN)2 - Thermodynamic image of silver in the corresponding region after the reaction.

[0060] Figure 17 The unreacted comparative slide and its Ag[(CN)2] - Au[(CN)2] - Cu[(CN)4] 2- A comparison of the spectra of these three metal cyanides after reaction.

[0061] Figure 18 This is a SEM image of a non-reacting comparative slide.

[0062] Figure 19 For comparison, the slides were prepared with Ag[(CN)2]. - SEM image after reaction.

[0063] Figure 20 For comparison, the slides and Au[(CN)2] were prepared. - SEM image after reaction.

[0064] Figure 21 For comparison, a substrate and Cu[(CN)4] were prepared. 2- SEM image after reaction. Detailed Implementation

[0065] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0066] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not limited to those elements and may also include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0067] "Optional" or "any one" means that the matter or event described thereafter may or may not occur, and the description includes both the possibility that the event will occur and the possibility that the event will not occur.

[0068] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0069] The terms "one embodiment," "some embodiments," "exemplary," "specific example," or "some examples," etc., used in this invention refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this document, the illustrative expressions of the above terms are not necessarily directed at the same embodiment or example.

[0070] The numerical range described in this invention includes not only the point values ​​listed in the embodiments, but also any point values ​​not listed within the numerical range described in this invention. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0071] In the following examples, unless otherwise specified, all reagents and consumables were purchased from conventional reagent manufacturers in the field.

[0072] This invention provides a qualitative and quantitative analysis method for metal cyanides in water, comprising the following steps:

[0073] S1. Preparation of star-shaped gold nanoparticle solution;

[0074] S2. The gold nanoparticles in the prepared star-shaped gold nanoparticle solution are loaded onto the surface of a modified silica substrate to obtain a substrate;

[0075] S3. Prepare standard solutions of different types of metal cyanide with gradient concentrations;

[0076] S4. Immerse the slides in different types of metal cyanide gradient concentration standard solutions. After the slides react with the standard solutions, obtain the standard solution slides. Obtain the standard solution spectrum of the standard solution slides and plot the standard curve based on the corresponding absorbance. The standard curve passes through the origin.

[0077] S5. Clean the standard solution slide to obtain a clean slide. Immerse the clean slide in the water sample to be tested. After the clean slide and the water sample to be tested have reacted, obtain the water sample slide. Obtain the water sample spectrum from the water sample slide. Compare the water sample spectrum with the standard solution spectrum. Determine the type of metal cyanide contained in the water sample based on the degree of matching between the two.

[0078] S6. Substitute the absorbance of the water sample slide into the standard curve to obtain the content of metal cyanide in the water sample to be tested, and complete the qualitative and quantitative analysis of metal cyanide in the water.

[0079] Now combined Figure 1 and Figure 2 This invention describes the process for detecting metal cyanides in water, wherein... Figure 1 This invention describes the principle of the slide colorimetric reaction. Figure 2 This is a schematic diagram of the detection process of the present invention. Generally, surface plasmon resonances in nanomaterials can generate hot electrons, but the lifespan of these hot electrons is in the picosecond to femtosecond range, far shorter than the time dimension of chemical reactions, making them ineffective for chemical reactions. In this embodiment, star-shaped gold nanoparticles are loaded onto the surface of a substrate. These star-shaped gold nanoparticles can improve the efficiency of hot electron generation. Furthermore, during the synthesis of the star-shaped gold nanoparticles, the citrate ions on the surface are oxidized by the hot electrons, releasing carbon dioxide and increasing the reduction potential energy of the gold nanoparticles. This process is irreversible, and the continued reaction allows the gold nanoparticles to accumulate reduction potential energy.

[0080] like Figure 1 As shown, the star-shaped gold nanoparticles used in this invention are surfactant-free and have exposed surfaces, allowing for effective contact and electron transfer with the cyanide ligands of metal cyanides, thus enabling specific reactions. These characteristics of the star-shaped gold nanoparticles solve the problem of the mismatch between the hot electrons and the time dimension of the chemical reaction. The reduced metal cyanide forms nano- or micron-sized particles of the corresponding metal on the substrate surface, exhibiting the color of the corresponding metal nanoparticles, each with its own independent absorption wavelength, thus allowing observation by spectroscopic equipment.

[0081] The detection principle of this invention is as follows:

[0082] This invention utilizes the chemical reactivity of surface plasmons in star-shaped gold nanoparticles to induce a specific reaction between the star-shaped gold nanoparticles and metal cyanide, thereby reducing the metal cyanide. The reduction of the metal cyanide causes a change in the color of the gold nanoparticles on the slide, and the changed color is related to the type and concentration of the metal contained in the metal cyanide. This enables qualitative and quantitative analysis of the type and concentration of metal cyanide in the target water body.

[0083] Based on this, the invention obtains the spectra of standard solution slides with gradient concentrations of different types of metal cyanides, plots a standard curve, and then obtains the spectra of water sample slides. By comparing these spectra with those of different metal cyanides, the most consistent metal cyanide is selected, thus determining the type of metal cyanide in the water sample. Finally, the absorbance corresponding to the water sample slide spectrum is substituted into the plotted standard curve to obtain the specific concentration of the target cyanide in the water sample. This invention solves the problem of cumbersome detection procedures in existing methods for detecting metal cyanides in water.

[0084] In particular, in some specific embodiments, the slides used in this invention are square structures with a size of (3-10)mm*(3-10)mm, such as 3mm*3mm, 4mm*4mm, 5mm*5mm, 6mm*6mm, 7mm*8mm, 10mm*9mm, 10mm*10mm. As long as the side length of the slide is within this range, it is acceptable. The slides used in this invention, when combined with simple and portable spectroscopic equipment, can be used to conduct rapid on-site detection of water bodies without the need for a laboratory environment, making it more convenient.

[0085] In some specific embodiments, the preparation method of the star-shaped gold nanoparticle solution includes the following steps:

[0086] S1.1. Mix sodium citrate solution and chloroauric acid solution and react. After the reaction is complete, a solution of spherical gold nanoparticles is obtained.

[0087] S1.2. The spherical gold nanoparticle solution is mixed with chloroauric acid solution, hydrochloric acid, silver nitrate solution and ascorbic acid solution under stirring. After the reaction is completed, the star-shaped gold nanoparticle solution is obtained.

[0088] In step S1.1:

[0089] The concentration of the chloroauric acid solution is 2.0–3.0 mM. For example, the concentration of the chloroauric acid solution can be 2.0 mM, 2.1 mM, 2.2 mM, 2.3 mM, 2.4 mM, 2.5 mM, 2.6 mM, 2.7 mM, 2.8 mM, 2.9 mM, or 3.0 mM, as long as the concentration of the chloroauric acid solution is within this range.

[0090] The volume of the chloroauric acid solution is 50-150 mL. For example, the volume of the chloroauric acid solution can be 50 mL, 60 mL, 70 mL, 80 mL, 90 mL, 100 mL, 110 mL, 120 mL, 130 mL, 140 mL, or 150 mL, as long as the volume of the chloroauric acid solution is within this range.

[0091] The concentration of sodium citrate solution is 3.0–4.0% (w / v). For example, the concentration of sodium citrate can be 3.0% (w / v), 3.1% (w / v), 3.2% (w / v), 3.3% (w / v), 3.4% (w / v), 3.5% (w / v), 3.6% (w / v), 3.7% (w / v), 3.8% (w / v), 3.9% (w / v), or 4.0% (w / v), as long as the concentration of sodium citrate solution is within this range.

[0092] The volume of sodium citrate solution is 0.5 to 1.5 mL. For example, the volume of sodium citrate solution can be 0.5 mL, 0.6 mL, 0.7 mL, 0.8 mL, 0.9 mL, 1.0 mL, 1.1 mL, 1.2 mL, 1.3 mL, 1.4 mL, or 1.5 mL, as long as the volume of sodium citrate solution is within this range.

[0093] In some specific embodiments, the chloroauric acid solution is mixed and reacted with the sodium citrate solution under boiling conditions, and the boiling sodium citrate solution is conducive to the generation of uniformly sized spherical gold nanoparticles.

[0094] In some specific embodiments, the reaction of chloroauric acid solution and sodium citrate solution is carried out under stirring, which also helps to form uniformly sized gold nanoparticles.

[0095] In some specific embodiments, the stirring speed during the reaction of chloroauric acid solution and citric acid solution is 500-1500 rpm. For example, the stirring speed during the reaction of chloroauric acid solution and citric acid solution can be 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, or 1500 rpm, as long as the speed is within this range.

[0096] In step S1.2:

[0097] The concentration of the chloroauric acid solution is 0.05 mM to 0.15 mM. For example, the concentration of the chloroauric acid solution can be 0.05 mM, 0.06 mM, 0.07 mM, 0.08 mM, 0.09 mM, 0.10 mM, 0.11 mM, 0.12 mM, 0.13 mM, 0.14 mM, or 0.15 mM, as long as the concentration of the chloroauric acid solution is within this range.

[0098] The volume of the chloroauric acid solution is 5 to 15 mL. For example, the volume of the chloroauric acid solution can be 5 mL, 6 mL, 7 mL, 8 mL, 9 mL, 10 mL, 11 mL, 12 mL, 13 mL, 14 mL, or 15 mL, as long as the volume of the chloroauric acid solution is within this range.

[0099] The concentration of hydrochloric acid is 0.5 to 1.5 M. For example, the concentration of hydrochloric acid can be 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M, 1.0 M, 1.1 M, 1.2 M, 1.3 M, 1.4 M, or 1.5 M, as long as the concentration of hydrochloric acid is within this range.

[0100] The volume of hydrochloric acid is 0.5 to 1.5 μL. For example, the volume of hydrochloric acid can be 0.5 μL, 0.6 μL, 0.7 μL, 0.8 μL, 0.9 μL, 1.0 μL, 1.1 μL, 1.2 μL, 1.3 μL, 1.4 μL, or 1.5 μL, as long as the volume of hydrochloric acid is within this range.

[0101] The concentration of silver nitrate solution is 1.0–3.0 mM. For example, the concentration of silver nitrate solution can be 1.0 mM, 1.2 mM, 1.4 mM, 1.6 mM, 1.8 mM, 2.0 mM, 2.2 mM, 2.4 mM, 2.6 mM, 2.8 mM, or 3.0 mM, as long as the concentration of silver nitrate solution is within this range.

[0102] The volume of the silver nitrate solution is 100–200 μL. For example, the volume of the silver nitrate solution can be 100 μL, 110 μL, 120 μL, 130 μL, 140 μL, 150 μL, 160 μL, 170 μL, 180 μL, 190 μL, or 200 μL, as long as the volume of the silver nitrate solution is within this range.

[0103] The concentration of ascorbic acid solution is 50-150 mM. For example, the concentration of ascorbic acid solution can be 50 mM, 60 mM, 70 mM, 80 mM, 90 mM, 100 mM, 110 mM, 120 mM, 130 mM, 140 mM, or 150 mM, as long as the concentration of ascorbic acid solution is within this range.

[0104] The volume of the ascorbic acid solution is 25–75 μL. For example, the volume of the ascorbic acid solution can be 25 μL, 30 μL, 35 μL, 40 μL, 45 μL, 50 μL, 55 μL, 60 μL, 65 μL, 70 μL, or 75 μL, as long as the volume of the ascorbic acid solution is within the range.

[0105] In some specific embodiments, the spherical gold nanoparticle solution is mixed and reacted with chloroauric acid solution, hydrochloric acid, silver nitrate solution, and ascorbic acid solution under more vigorous stirring conditions. The stirring speed is 2000-30000 rpm. For example, the stirring speed can be 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm, 2800 rpm, 2900 rpm, or 30000 rpm, as long as the stirring speed is within this range.

[0106] In particular, the reaction of the spherical gold nanoparticle solution with chloroauric acid solution, hydrochloric acid, silver nitrate solution, and ascorbic acid solution can be carried out under vortex conditions. This embodiment does not further limit the specific parameters of the vortex, as long as the reaction requirements are met and star-shaped gold nanoparticles can be generated.

[0107] In some specific embodiments, the method for preparing the slide includes the following steps:

[0108] S2.1. Pre-treat the silica substrate to expose the hydroxyl groups on the surface of the silica substrate;

[0109] S2.2. Clean the pretreated silica substrate and immerse it in an ethanol solution of 3-aminopropyltrimethoxysilane or an ethanol solution of 3-thiolpropyltrimethoxysilane for modification.

[0110] S2.3. The cleaned and modified silica substrate is immersed in a solution of star-shaped gold nanoparticles to load the star-shaped gold nanoparticles and obtain a substrate.

[0111] In step S2.1, exposing the hydroxyl groups on the surface of the silica substrate requires creating defects on the silica substrate surface. This can be achieved by immersing the silica substrate in a piranha etching solution (a mixture of concentrated sulfuric acid and hydrogen peroxide), using an alkaline solution (such as sodium hydroxide solution or potassium hydroxide solution), treating the silica substrate surface with ozone, or other methods that can create defects on the silica substrate surface.

[0112] In step S2.2:

[0113] The concentration of 3-aminopropyltrimethoxysilane in the ethanol solution of 3-aminopropyltrimethoxysilane is 2.5% to 7.5% (w / w). As an example, the concentration of 3-aminopropyltrimethoxysilane in the ethanol solution of 3-aminopropyltrimethoxysilane can be 2.5% (w / w), 3.0% (w / w), 3.5% (w / w), 4.0% (w / w), 4.5% (w / w), 5.0% (w / w), 5.5% (w / w), 6.0% (w / w), 6.5% (w / w), 7.0% (w / w), or 7.5% (w / w), as long as the concentration of 3-aminopropyltrimethoxysilane in the ethanol solution of 3-aminopropyltrimethoxysilane is within this range.

[0114] Similarly, when choosing an ethanol solution of 3-thiolpropyltrimethoxysilane, the concentration of 3-thiolpropyltrimethoxysilane in the ethanol solution is 2.5% to 7.5% (w / w). As an example, the concentration of 3-thiolpropyltrimethoxysilane in the ethanol solution can be 2.5% (w / w), 3.0% (w / w), 3.5% (w / w), 4.0% (w / w), 4.5% (w / w), 5.0% (w / w), 5.5% (w / w), 6.0% (w / w), 6.5% (w / w), 7.0% (w / w), or 7.5% (w / w), as long as the concentration of 3-thiolpropyltrimethoxysilane in the ethanol solution is within this range.

[0115] In some specific embodiments, the pretreated substrate needs to be soaked overnight in an ethanol solution of 3-aminopropyltrimethoxysilane or an ethanol solution of 3-thiolpropyltrimethoxysilane at a temperature above 45°C to complete the modification.

[0116] In some specific implementations, the metal ion in the metal cyanide is Au[(CN)2]. - Ag[(CN)2] - Cu[(CN)4] 2- Ni[(CN)6] 3- Co[(CN)6] 3- Any one of them.

[0117] In some specific implementations, the gradient concentration of the metal cyanide gradient concentration standard solution is 1 to 500 ppm. For example, the gradient concentration of the metal cyanide gradient concentration standard solution can be 1 ppm, 5 ppm, 25 ppm, 50 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, or 500 ppm. Of course, the gradient concentration of the metal cyanide standard solution can also be adjusted adaptively according to the actual detection scenario.

[0118] In some specific embodiments, the reaction time of the slide immersion in the standard solution is 3 to 5 minutes. For example, the reaction time of the slide immersion in the standard solution is 3 minutes, 4 minutes, and 5 minutes. Within this time range, the slide can fully react with the metal cyanide in the standard solution, and a significant change in the color of the slide can be observed with the naked eye.

[0119] In some specific embodiments, the reaction time for immersing the cleaning slide in the water sample to be tested is 3 to 5 minutes. For example, the reaction time for immersing the cleaning slide in the water sample to be tested is 3 minutes, 4 minutes, and 5 minutes. Similarly, if the water sample to be tested contains metal hydrides, a significant color change of the cleaning slide can be observed with the naked eye within this time range.

[0120] The present invention will be further illustrated below through specific embodiments:

[0121] Example 1

[0122] S1.1 100 mL of a solution containing 2.5 mM gold chloro acid was heated to boiling, followed by the addition of 1 mL of a solution containing 3.3% (w / v) sodium citrate. The entire process was carried out with stirring at 1000 rpm, and the solution turned red after 5 minutes. Heating was stopped after the solution color change ceased, yielding a solution of spherical gold nanoparticles with a particle size of approximately 15 nm.

[0123] S1.2 200 μL of spherical gold nanoparticles were added to 10 mL of a solution containing 0.1 mM gold chloric acid, and 0.1 μL of 1 M hydrochloric acid was added. The mixture was stirred at 2500 rpm, and simultaneously 150 μL of 2 mM silver nitrate solution and 50 μL of 100 mM ascorbic acid solution were added. The solution turned blue-green. Stirring was continued for 30 seconds to obtain a solution of star-shaped gold nanoparticles. The TEM morphology of the star-shaped gold nanoparticles is shown in the figure. Figure 3 As shown, in conjunction with the foregoing inventive principle section of this invention and Figure 3 As can be seen, the star-shaped gold nanoparticles referred to in this invention are gold nanoparticles with a spherical gold nanoparticle core, and several spike-like protrusion structures are grown on the surface of the spherical gold nanoparticle through a reaction.

[0124] S2.1 The glass slide was pretreated with freshly prepared piranha etching solution, then thoroughly washed with deionized water and dried. The glass slide was then immersed in an ethanol solution containing 5% (w / w) (3-aminopropyl)trimethoxysilane, maintaining the solution temperature at 45°C, and left to stand overnight. After removing the glass slide, it was washed with ethanol and dried, then placed in the nano-gold particle solution prepared in S1.2 and left to stand overnight to obtain a blue-green slide with star-shaped nano-gold particles loaded on its surface. The SEM morphology of the slide is shown in Figure 1. Figure 4 As shown.

[0125] S3. Preparation of Ag[(CN)2] - Au[(CN)2] - Cu[(CN)4] 2- The standard solutions of these three metal cyanide complex ions have concentrations of 5 ppm, 25 ppm, 50 ppm, 100 ppm, 200 ppm, and 300 ppm for each complex ion.

[0126] S4. Immerse the slides in different types of metal cyanide standard solutions with varying concentrations. After the slides react with the standard solutions for 5 minutes, obtain standard solution slides. Place the standard solution slides in a handheld spectrometer, acquire the spectra, and record the absorbance of the slides near 450 nm, 530 nm, and 610 nm. Figure 5 The slide prepared in Example 1 and Ag(CN)2 - Morphology of the complexed ions after reaction under SEM.

[0127] S5. Plot a standard curve with absorbance on the x-axis and concentration of the standard solution on the y-axis. The standard curve is shown below. Figure 6 As shown, the standard curve passes through the origin.

[0128] S6. Prepare water sample I and water sample II to be tested. Water sample I is a clean, natural water sample, and water sample II is a sample artificially treated with approximately 200 ppm of Ag(CN)2. - Natural water samples were collected. After cleaning the standard solution slide, a clean slide was obtained. This clean slide was then immersed in water sample I. After reacting with water sample I for 5 minutes, the water sample I slide was obtained. The water sample I slide was then placed in a handheld spectrometer to acquire its spectral data. After cleaning the water sample I slide, it was immersed in water sample II for 5 minutes to acquire its spectral data. The spectral data of water sample I and water sample II were then compared to form a spectral comparison chart. Figure 7 .from Figure 7It can be observed that the absorbance of sample I remains unchanged near 450 nm, while the absorbance of sample II near 450 nm is 0.55 Abs. Comparing the spectrum of sample II with that of the standard solution reveals that sample II contains Ag[(CN)2] metal cyanide. - After substituting into the standard curve, the Ag[(CN)2] in the water sample II was calculated. - The concentration was 209 ppm, while the concentration of metal cyanide in water sample I was not detected.

[0129] Example 2

[0130] S1.1 Heat 100 mL of a solution containing 2.5 mM gold chloro acid to boiling, then add 1 mL of a solution containing 3.3% (w / v) sodium citrate. Stir at 1000 rpm throughout the process; the solution turns red after 4 minutes. Stop heating after the solution color change ceases, yielding a solution of spherical gold nanoparticles with a particle size of approximately 15 nm.

[0131] S1.2 Add 200 μL of spherical gold nanoparticles to 10 mL of a solution containing 0.1 mM gold chloro acid, and then add 0.1 μL of 1 M hydrochloric acid. While maintaining a vortex, add 150 μL of 2 mM silver nitrate solution and 50 μL of 100 mM ascorbic acid solution. The solution turns blue-green. Continue stirring for 30 seconds to obtain a solution of star-shaped gold nanoparticles.

[0132] S2.1 The glass slide is pretreated using an ultraviolet ozone generator, then thoroughly washed and dried with deionized water. The glass slide is then immersed in an ethanol solution containing 5% (w / w) (3-thiolpropyl)trimethoxysilane, maintaining the solution temperature at 45°C, and left to stand overnight. After removing the glass slide, it is washed with ethanol and dried, then placed in the nano-gold particle solution prepared in S1.2 and left to stand overnight to obtain a blue-green carrier slide with star-shaped nano-gold particles loaded on its surface.

[0133] S3. Preparation of Ag[(CN)2] - Au[(CN)2] - Cu[(CN)4] 2- The standard solutions of these three metal cyanide complex ions have concentrations of 5 ppm, 25 ppm, 50 ppm, 100 ppm, 200 ppm, and 300 ppm for each complex ion.

[0134] S4. Immerse the slides in different types of metal cyanide gradient concentration standard solutions. After the slides react with the standard solutions for 5 minutes, transfer them to the standard solution slides. Place the standard solution slides in a handheld spectrometer to obtain the spectra and record the absorbance of the slides near 450 nm, 530 nm, and 610 nm.

[0135] S5. Plot a standard curve with absorbance on the x-axis and concentration of the standard solution on the y-axis. The standard curve is shown below. Figure 8 As shown, the standard curve passes through the origin.

[0136] S6. Prepare water sample I and water sample II to be tested. Water sample I is a clean, natural water sample, and water sample II is a sample artificially treated with approximately 100 ppm of Au(CN)2. - Natural water samples were collected. After cleaning the standard solution slide, a clean slide was obtained. This clean slide was immersed in water sample I and reacted with water sample I for 4 minutes to obtain water sample I slide. Water sample I slide was then placed in a handheld spectrometer to acquire its spectral data. After cleaning the water sample I slide, it was immersed in water sample II for 4 minutes to obtain water sample II slide. The spectral data of water sample II was acquired. It was recorded that the absorbance of water sample I slide near 530 nm remained unchanged, while the absorbance of water sample II slide near 530 nm was 0.27 Abs. The spectral data of water sample I and water sample II were compiled into a spectral comparison chart. Figure 9 Comparing the spectra of water sample II with those of the standard solution reveals that the metal cyanide present in water sample II is Ag[(CN)2]. - After substituting into the standard curve, the Ag[(CN)2] in the water sample II was calculated. - The concentration was 97 ppm, while the concentration of metal cyanide in water sample I was not detected.

[0137] Example 3

[0138] S1.1 100 mL of a solution containing 2.5 mM gold chloro acid was heated to boiling, followed by the addition of 1 mL of a solution containing 3.3% (w / v) sodium citrate. The entire process was carried out with stirring at 2000 rpm. After 3 minutes, the solution turned red. Heating was stopped after the solution color change ceased, yielding a solution of spherical gold nanoparticles with a particle size of approximately 15 nm.

[0139] S1.2 Add 200 μL of spherical gold nanoparticles to 10 mL of a solution containing 0.1 mM gold chloro acid, and then add 0.1 μL of 1 M hydrochloric acid. Stir at 3000 rpm, and simultaneously add 150 μL of 2 mM silver nitrate solution and 50 μL of 100 mM ascorbic acid solution. The solution turns blue-green. Continue stirring for 30 seconds to obtain a solution of star-shaped gold nanoparticles.

[0140] S2.1 Pre-treat the glass slide using freshly prepared piranha etching solution, then thoroughly wash and dry it with deionized water. Immerse the glass slide in an ethanol solution containing 5% (w / w) (3-aminopropyl)trimethoxysilane, maintaining the solution temperature at 45°C, and let it stand overnight. After removing the glass slide, wash it with ethanol and blow it dry, then place it in the nano-gold particle solution prepared in S1.2 and let it stand overnight to obtain a blue-green carrier with star-shaped nano-gold particles loaded on its surface.

[0141] S3. Preparation of Ag[(CN)2] - Au[(CN)2] - Cu[(CN)4] 2- The standard solutions of these three metal cyanide complex ions have concentrations of 5 ppm, 25 ppm, 50 ppm, 100 ppm, 200 ppm, and 300 ppm for each complex ion.

[0142] S4. Immerse the slides in different types of metal cyanide gradient concentration standard solutions. After the slides react with the standard solutions for 5 minutes, transfer the standard solution slides to the standard solution slides. Place the standard solution slides in a handheld spectrometer, acquire the spectrum, and record the absorbance of the slides near 610 nm.

[0143] S5. Plot a standard curve with absorbance on the x-axis and concentration of the standard solution on the y-axis. The standard curve is shown below. Figure 10 As shown, the standard curve passes through the origin.

[0144] S6. Prepare water sample I and water sample II to be tested. Water sample I is a clean, natural water sample, and water sample II is water with approximately 50 ppm of Cu(CN)4 artificially added. 2- Natural water samples were collected. After cleaning the standard solution slide, a clean slide was obtained. This clean slide was immersed in water sample I and reacted with water sample I for 3 minutes to obtain water sample I slide. Water sample I slide was then placed in a handheld spectrometer to acquire its spectral data. After cleaning the water sample I slide, it was immersed in water sample II and reacted for 3 minutes to obtain water sample II slide. The spectral data of water sample II was acquired. It was recorded that the absorbance of water sample I slide near 530 nm remained unchanged, while the absorbance of water sample II slide near 530 nm was 0.12 Abs. The spectral data of water sample I and water sample II were compiled into a spectral comparison chart. Figure 11 .from Figure 11It can be observed that the absorbance of sample I remains unchanged near 610 nm, while the absorbance of sample II near 510 nm is 0.12 Abs. Comparing the spectrum of sample II with that of the standard solution reveals that sample II contains Cu(CN)4 metal cyanide. 2- After substituting into the standard curve, the concentration of the water sample II to be tested was calculated. Cu(CN)4 2- The concentration was 48 ppm, while the concentration of metal cyanide in water sample I was not detected.

[0145] Verification Example 1

[0146] To further demonstrate the stability of the method provided by this invention, the following tests were conducted in this verification example:

[0147] The slide prepared in Example 1 was cleaned and analyzed using a handheld spectrometer to obtain the spectrum before treatment. Then, the slide was immersed in a natural water sample (ultrapure water) for 5 minutes, removed, dried, and the spectrum of the natural water sample was obtained using a handheld spectrometer. Finally, the slide was immersed in a 5% hydrogen peroxide aqueous solution prepared from ultrapure water for 5 minutes, removed, cleaned, and the spectrum of the natural water sample + oxidant group under oxidant interference was obtained using a handheld spectrometer. A comparison of the spectra under the three conditions is shown below. Figure 12 .

[0148] pass Figure 12 It can be seen that the spectra of the untreated slide, the slide soaked in natural water sample, and the slide with added oxidant as an interfering component are not significantly different. Even with oxidant as an interfering component, it can still meet the normal detection requirements. Therefore, it can be considered that the detection method provided by the present invention has strong stability.

[0149] Verification Example 2

[0150] This verification example provides a more detailed explanation of certain aspects of the test and analysis process in Example 1 by referring to the accompanying drawings, as follows:

[0151] (1) Figure 13 These are the morphologies of the same batch of slides prepared in Example 1 under different treatment states. The top slide is the slide without additional treatment, the middle slide is the slide after soaking in ultrapure water, and the bottom slide is the slide after being treated with Ag(CN)2. - The slides after treatment. It can be observed that the slides soaked in pure water showed no color change compared to the untreated slides, while the color of Ag(CN)2... - The color of the slide after the reaction showed a visible change, which proves that the present invention is feasible for qualitative and quantitative analysis of metal cyanide in water by comparing the color change of the slide after the reaction with metal cyanide.

[0152] (2) Figure 14 The slide obtained in Example 1 and Ag(CN)2 - A comparison of the spectra before and after the reaction is shown, with the blue line representing the spectrum before the reaction and the orange line representing the spectrum after the reaction. It can be seen that the star-shaped gold nanoparticles on the slide react with Ag(CN)₂. - The shift in the spectrum after the reaction indicates that new substances have been formed.

[0153] (3) Figure 15 The slide obtained in Example 1 and Ag(CN)2 - Thermodynamic image of gold in the corresponding region before the reaction. Figure 16 The slide obtained in Example 1 and Ag(CN)2 - Thermodynamic images of silver in the corresponding region after the reaction demonstrate the interaction between the star-shaped gold nanoparticles and Ag(CN)₂. - The reaction produced elemental silver, the specific morphology of which is as follows: Figure 5 As shown, its main shape is rod-shaped.

[0154] Comparative Example

[0155] To further demonstrate the accuracy and reliability of the method provided by this invention, a comparative test is conducted. This comparative example is to verify the specificity of the star-shaped gold nanoparticle carrier and metal cyanide in the detection method provided by this invention. The spherical gold nanoparticles obtained in step S1.1 are loaded onto a silica substrate to form a comparative example carrier. The specific steps differ from those in Example 1 only in that step S1.2 (the process of making the spherical gold nanoparticles into star-shaped gold nanoparticles) is omitted. The details are as follows:

[0156] S1.1 100 mL of a solution containing 2.5 mM gold chloro acid was heated to boiling, followed by the addition of 1 mL of a solution containing 3.3% (w / v) sodium citrate. The entire process was carried out with stirring at 1000 rpm, and the solution turned red after 5 minutes. Heating was stopped after the solution color change ceased, yielding a solution of spherical gold nanoparticles with a particle size of approximately 15 nm.

[0157] S2.1 The glass slide was pretreated with freshly prepared piranha etching solution, then thoroughly washed with deionized water and dried. The glass slide was immersed in an ethanol solution containing 5% (w / w) (3-aminopropyl)trimethoxysilane, and the solution temperature was maintained at 45°C for overnight standing. After removing the glass slide, it was washed with ethanol and dried, then placed in the spherical gold nanoparticle solution prepared in 1.1 and left to stand overnight to obtain a comparative sample substrate with spherical gold nanoparticles loaded on its surface.

[0158] S3. Preparation of Ag[(CN)2]- Au[(CN)2] - Cu[(CN)4] 2- The standard solutions of these three metal cyanide complex ions have concentrations of 5 ppm, 25 ppm, 50 ppm, 100 ppm, 200 ppm, and 300 ppm for each complex ion.

[0159] S4. Immerse the comparative sample slides in graded concentration standard solutions of gold, silver, and copper cyanides, respectively. After the comparative sample slides react with the standard solutions for 5 minutes, obtain the corresponding comparative standard solution slides. Place the comparative standard solution slides in a handheld spectrometer to acquire spectral data. The unreacted comparative sample slides and those reacting with Ag[(CN)2]... - Au[(CN)2] - Cu[(CN)4] 2- The comparison of the spectra of these three metal cyanides after reaction is shown in the figure below. Figure 17 As shown. The absorbance of the slide was recorded at approximately 450 nm, 530 nm, and 610 nm, and no significant changes were observed. Separately, absorbance was measured on the unreacted comparative slide and the slide containing Ag[(CN)2]. - Comparative slides after the reaction, and Au[(CN)2] - Comparative sample slides after the reaction, and samples with Cu[(CN)4] 2- SEM analysis was performed on the comparative slides after the reaction, and the corresponding images are as follows: Figure 18 , Figure 19 , Figure 20 Figure 21 It can be observed that there are no significant differences in the SEM images of the comparative slides under the above four conditions, which can be considered that the slides carrying spherical gold nanoparticles do not react with metal cyanide.

[0160] Comparative analysis shows that although both Example 1 and the comparative example prepared gold nanoparticle carriers, the spherical gold nanoparticle carriers obtained in the comparative example could not react specifically with metal cyanide as in Example 1, thus causing the carriers to change color. This demonstrates the importance of the structure of the star-shaped gold nanoparticles for their specific reaction with metal cyanide.

[0161] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make modifications or alterations based on the above description, and all such modifications and alterations should fall within the protection scope of the appended claims.

Claims

1. A qualitative and quantitative analysis method for metal cyanides in water, characterized in that, Includes the following steps: S1. Preparation of star-shaped gold nanoparticle solution; S2. The gold nanoparticles in the prepared star-shaped gold nanoparticle solution are loaded onto the surface of a modified silica substrate to obtain a substrate; S3. Prepare standard solutions of different types of metal cyanide with gradient concentrations; S4. Immerse the slides in different types of metal cyanide gradient concentration standard solutions. After the slides react with the standard solutions, obtain the standard solution slides. Obtain the standard solution spectrum of the standard solution slides and plot the standard curve based on the corresponding absorbance. The standard curve passes through the origin. S5. Clean the standard solution slide to obtain a clean slide. Immerse the clean slide in the water sample to be tested. After the clean slide and the water sample to be tested have reacted, obtain the water sample slide. Obtain the water sample spectrum from the water sample slide. Compare the water sample spectrum with the standard solution spectrum. Determine the type of metal cyanide contained in the water sample based on the degree of matching between the two. S6. Substitute the absorbance of the water sample slide into the standard curve to obtain the content of metal cyanide in the water sample to be tested, and complete the qualitative and quantitative analysis of metal cyanide in the water body. The preparation method of the star-shaped gold nanoparticle solution includes the following steps: S1.

1. Mix sodium citrate solution and chloroauric acid solution and react. After the reaction is complete, a solution of spherical gold nanoparticles is obtained. S1.

2. The spherical gold nanoparticle solution is mixed with chloroauric acid solution, hydrochloric acid, silver nitrate solution and ascorbic acid solution under stirring. After the reaction is completed, the star-shaped gold nanoparticle solution is obtained. In step S1.1: The concentration of the chloroauric acid solution is 2.0–3.0 mM, and the volume is 50–150 mL; The concentration of the sodium citrate solution is 3.0–4.0% (w / v), and the volume is 0.5–1.5 mL; In step S1.2: The concentration of the chloroauric acid solution is 0.05 mM to 0.15 mM, and the volume is 5 to 15 mL. The concentration of hydrochloric acid is 0.5–1.5 M, and the volume is 0.5–1.5 μL; The concentration of the silver nitrate solution is 1.0–3.0 mM, and the volume is 100–200 μL; The concentration of ascorbic acid solution is 50–150 mM, and the volume is 25–75 μL; The method for preparing the slide includes the following steps: S2.

1. Pre-treat the silica substrate to expose the hydroxyl groups on the surface of the silica substrate; S2.

2. Clean the pretreated silica substrate and immerse it in an ethanol solution of 3-aminopropyltrimethoxysilane or an ethanol solution of 3-thiolpropyltrimethoxysilane for modification. S2.

3. The cleaned and modified silica substrate is immersed in a solution of star-shaped gold nanoparticles to load the star-shaped gold nanoparticles and obtain a substrate. The metal ion in the metal cyanide is Au[(CN)2]. - Ag[(CN)2] - Cu[(CN)4] 2- Ni[(CN)6] 3- Co[(CN)6] 3- Any one of them.

2. The qualitative and quantitative analysis method for metal cyanides in water according to claim 1, characterized in that, In step S2.2: The concentration of 3-aminopropyltrimethoxysilane in the ethanol solution is 2.5%–7.5% (w / w); The concentration of 3-thiol-propyltrimethoxysilane in the ethanol solution is 2.5%–7.5% (w / w).

3. The qualitative and quantitative analysis method for metal cyanides in water according to claim 1, characterized in that, The gradient concentration of the metal cyanide gradient concentration standard solution is 1–500 ppm.

4. The qualitative and quantitative analysis method for metal cyanides in water according to claim 1, characterized in that, The reaction time for the slide to be immersed in the standard solution is 3 to 5 minutes. The reaction time for immersing the clean slide in the water sample to be tested is 3 to 5 minutes.

5. The qualitative and quantitative analysis method for metal cyanides in water according to claim 1, characterized in that, Three identical water samples were collected for analysis and testing. The content of metal cyanide in the water samples was taken as the average value of the three tests.

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