Methods for detecting fluoride ion concentration and fluoride ion indicators

Abstract

This invention discloses a method for detecting fluoride ion concentration and a fluoride ion indicator. The method includes: mixing silicon nanoparticles with a test solution to form a mixed solution; performing a high-temperature silicon corrosion reaction at 70–100°C; and observing the color change of the mixed solution after a predetermined reaction time to determine the concentration of fluoride ions in the test solution. The high-temperature silicon corrosion reaction can be carried out under the influence of fluoride ions. The fluoride ion concentration detection method and fluoride ion indicator provided by this invention can reduce the requirement for the quantity of fluoride ions and improve the sensitivity of fluoride ion detection by controlling the reaction temperature to make fluoride ions act as a catalyst or similar catalyst. Furthermore, this method has excellent selectivity and anti-interference properties, enabling reasonable, convenient, and low-cost fluoride detection in drinking water and industrial wastewater.

Description

Technical Field

[0001] This invention relates to the field of analytical detection technology, and in particular to a method for detecting fluoride ion concentration and a fluoride ion indicator. Background Technology

[0002] The detection of fluoride ions is of great significance for environmental monitoring and human health management. Fluorides are ubiquitous in natural water bodies, and their concentration directly affects human health. Excessive fluoride intake can lead to various health problems, such as fluorosis and urolithiasis.

[0003] Currently, common methods for detecting fluoride ions mainly include fluoride reagent spectrophotometry, ion-selective electrode (ISE) methods, and visual colorimetry. Among these, spectrophotometry and ISE methods are widely used in fluoride analysis due to their accuracy. However, both methods require complex instruments and highly trained operators, and involve cumbersome sample pretreatment processes and complex operating procedures. These limitations make them unsuitable for rapid on-site detection or low-cost applications.

[0004] In contrast, visual colorimetry has attracted widespread research interest due to its ease of operation and rapid detection. Existing visual colorimetric methods typically use organic complexes as indicators. These methods utilize the interaction between fluoride ions and metal cations or silicon atoms in these complexes, causing changes in the complex's structure and consequently altering its fluorescence or absorption spectrum. This change can be used to quantitatively analyze the fluoride ion content by comparing the solution color with a standard color chart, making it suitable for rapid on-site detection, such as wastewater self-testing and agricultural water monitoring.

[0005] However, colorimetric methods based on organic complexes are susceptible to interference from ions and microbial decomposition, affecting their accuracy and stability. Furthermore, many organic complexes are poorly soluble in water, and increased water content in the system can significantly reduce the sensitivity of fluoride ion detection.

[0006] Therefore, it is necessary to provide a new method for detecting fluoride ion concentration and a fluoride ion indicator to address the problems in the existing technology.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a method for detecting fluoride ion concentration and a fluoride ion indicator, which have high selectivity, anti-interference and high sensitivity.

[0009] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0010] In a first aspect, the present invention provides a method for detecting fluoride ion concentration, comprising:

[0011] Silicon nanoparticles are mixed with the test solution to form a mixed solution; a high-temperature silicon corrosion reaction is carried out at 70–100°C, and after a predetermined reaction time, the color change of the mixed solution is observed to determine the concentration of fluoride ions in the test solution; wherein the high-temperature silicon corrosion reaction can be carried out under the action of fluoride ions.

[0012] In one or more embodiments of the present invention, the high-temperature silicon etching reaction comprises the reaction shown in the following reaction equation:

[0013]

[0014] In one or more embodiments of the present invention, silicon nanoparticles are mixed with the test solution to form a mixed solution, specifically including: adding a mixed powder of silicon nanoparticles and surfactant to the test solution and mixing to form a mixed solution.

[0015] In one or more embodiments of the present invention, the content of silicon nanoparticles in the silicon nanoparticle suspension is 0.01 to 0.04 g / L.

[0016] In one or more embodiments of the present invention, the silicon nanoparticles have a particle size between 10 and 1000 nm.

[0017] In one or more embodiments of the present invention, the average particle size of the silicon nanoparticles is 95-105 nm.

[0018] In one or more embodiments of the present invention, the reaction temperature of the high-temperature silicon etching reaction is 90°C.

[0019] In one or more embodiments of the present invention, the reaction time of the high-temperature silicon etching reaction is 5 to 150 min.

[0020] Secondly, the present invention provides a fluoride ion indicator, wherein the fluoride ion indicator is a solution or powder containing silicon nanoparticles; wherein the silicon nanoparticles in the fluoride ion indicator can undergo a high-temperature silicon corrosion reaction under the action of fluoride ions at a temperature of 70-100°C.

[0021] Thirdly, the present invention provides a method for detecting fluoride ion concentration, wherein the method uses the aforementioned fluoride ion indicator to detect fluoride ion concentration by visual colorimetry.

[0022] Compared with existing technologies, the fluoride ion concentration detection method and fluoride ion indicator provided by this invention can make fluoride ions act as a catalyst or similar catalyst by adjusting the reaction temperature, thereby reducing the requirement for the quantity of fluoride ions and improving the sensitivity of fluoride ion detection. Moreover, this method has excellent selectivity and anti-interference ability, and can achieve reasonable, convenient and low-cost fluoride detection in drinking water and industrial wastewater. Attached Figure Description

[0023] Figure 1 This is an optical image of the silicon nanoparticle sample in Example 1 of this invention;

[0024] Figure 2 This is a SEM image of the silicon nanoparticle sample in Example 1 of this invention;

[0025] Figure 3 These are optical images of silicon nanoparticle suspensions of different concentrations in Example 1 of the present invention;

[0026] Figure 4 These are absorption spectra of silicon nanoparticle suspensions of different concentrations in Example 1 of the present invention;

[0027] Figure 5 This is a graph showing the relationship between the concentration of the silicon nanoparticle suspension and the absorbance at 460 nm in Example 1 of this invention.

[0028] Figure 6 This is a graph showing the change in absorbance of each suspension over reaction time in Example 2 of the present invention;

[0029] Figure 7 This is the absorption spectrum of the suspension in Example 3 of the present invention;

[0030] Figure 8 These are the absorption spectra of each suspension in Example 4 of the present invention;

[0031] Figure 9 This is a graph showing the relationship between the change in absorbance of the suspension and the concentration of fluoride ions after 30 minutes of reaction in Example 4 of this invention.

[0032] Figure 10 These are optical images of each suspension after reacting for 30 minutes in Example 4 of this invention;

[0033] Figure 11 This is the absorption spectrum of the suspension in Example 5 of the present invention;

[0034] Figure 12 This is a graph showing the change in absorbance of each suspension after 30 minutes of reaction in Example 6 of the present invention;

[0035] Figure 13 This is a graph showing the change in absorbance of each suspension after 30 minutes of reaction in Example 7 of the present invention;

[0036] Figure 14 This is the absorption spectrum of the suspension in Comparative Example 1 of the present invention;

[0037] Figure 15 This is the absorption spectrum of the suspension in Comparative Example 2 of this invention. Detailed Implementation

[0038] The specific embodiments of the present invention will be described in detail below with reference to the examples, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0039] It should be noted that, unless otherwise specified, all figures used in this specification and claims to represent feature dimensions, quantities, and physical properties should be understood to be modified by the term "about" in all cases. Therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired characteristics using the teachings disclosed herein. The use of numerical ranges indicated by endpoints includes all numbers within that range and any range within that range; for example, 1 to 5 includes 1, 1.2, 1.4, 1.55, 2, 2.75, 3, 3.8, 4, and 5, etc.

[0040] In existing technologies, fluoride ion detection methods often rely on complex instruments, cumbersome operating procedures, and highly skilled operators. These factors limit the widespread application of fluoride ion detection technology, especially in environments requiring rapid on-site detection. Furthermore, traditional methods suffer from deficiencies in sensitivity, stability, and interference resistance, problems that are particularly pronounced in field testing and low-cost applications.

[0041] From a chemical perspective, fluoride ions readily undergo specific chemical reactions with silicon. For example, in an environment containing oxidizing agents, silicon can react with the oxidizing agents and fluorine to form colorless fluorosilicate ions (a specific Si-F reaction). The specific chemical reaction equation is as follows:

[0042]

[0043] Utilizing this specific reaction, silicon nanoparticle suspensions can be used as indicators for fluoride ion detection. The system is decolorized through the reaction, achieving highly selective colorimetric detection of fluoride ions in the aqueous phase. However, because the stoichiometric ratio of silicon to fluoride in this reaction is 1:6, a large amount of fluoride ions is required for the silicon nanoparticles to react and change color noticeably, making it difficult to use for detecting low concentrations of fluoride ions (e.g., 10 ppm).

[0044] The inventors noted that fluorosilicates can hydrolyze in hot water into hydrogen fluoride, silicic acid, and fluoride ions, releasing fluoride ions (as shown in chemical reaction equation 2). In other words, at appropriate temperatures, fluoride ions can be recycled in the presence of a silicon suspension through the reaction shown in chemical reaction equation (2), and essentially act as a catalyst throughout the reaction. Thus, a small amount of fluoride ions can catalyze a significant reaction in a large amount of silicon, resulting in a noticeable color change. This principle can be used to detect low concentrations of fluoride ions using silicon nanoparticle suspensions, thereby significantly improving the sensitivity of fluoride ion detection.

[0045]

[0046] Against this backdrop, the inventors proposed a novel strategy to improve the detection sensitivity of fluoride ions by controlling the reaction temperature, transforming the role of fluoride ions from reactant to catalyst or catalyst-like intermediate reactant. This eliminates the requirement of a six-fold increase in fluoride ion quantity for high-temperature silicon corrosion reactions. By setting the experimental temperature to 70–100 degrees Celsius, fluoride ions as low as 0.5 ppm caused a 48.3% decrease in the light absorption of a 40 ppm silicon nanoparticle suspension within half an hour, producing a significant color change and enabling effective detection of 0.5 ppm fluoride ions. Using this system, it is possible to accurately distinguish the fluoride content in water samples at the ppm level, effectively determining whether the water sample meets the wastewater discharge standard (10 ppm) and the drinking water standard (1 ppm). Simultaneously, the system exhibits high selectivity and interference resistance. In a broader context, this method may enable reasonable, convenient, and low-cost fluoride detection in drinking water and industrial wastewater. Furthermore, the strategy of transforming the role of the analyte from reactant to catalyst can also provide insights for developing new analyte chemisenting strategies.

[0047] The fluoride ion concentration detection method provided by one embodiment of the present invention specifically includes the following steps:

[0048] S101: Mix silicon nanoparticles with the test solution to form a mixed solution.

[0049] In one exemplary embodiment, mixing silicon nanoparticles with the test solution to form a mixed solution specifically includes: adding a mixed powder of silicon nanoparticles and a surfactant to the test solution and mixing to form a mixed solution.

[0050] It should be noted that silicon nanoparticles can be stably dispersed in water with the help of surfactants, and their large specific surface area is conducive to their rapid reaction.

[0051] In other embodiments, the mixed powder of silicon nanoparticles and surfactant can be first prepared into a silicon nanoparticle suspension, and then the test solution can be added to the silicon nanoparticle suspension to form a mixed solution.

[0052] Specifically, the silicon nanoparticle content in the silicon nanoparticle suspension is preferably 0.01–0.04 g / L, the silicon nanoparticle size is preferably between 10 and 1000 nm, and the average particle size of the silicon nanoparticles is preferably 95–105 nm.

[0053] S102: A high-temperature silicon corrosion reaction is carried out at 70–100°C. After a predetermined reaction time, the color change of the mixed solution is observed to determine the concentration of fluoride ions in the test solution; wherein the high-temperature silicon corrosion reaction can be carried out under the action of fluoride ions.

[0054] Specifically, the high-temperature silicon corrosion reaction includes the reaction shown in the following reaction equation:

[0055]

[0056] It should be noted that heating the mixed solution containing silicon nanoparticles to 70–100°C can be achieved by using a heater, water bath, or other heating equipment.

[0057] The reaction is maintained at the above temperature for a predetermined time, which can be 5–150 min. The reaction time affects the degree of corrosion of the silicon nanoparticles, and thus the degree of color change.

[0058] After the reaction is complete, observe the color change of the mixed solution. The color change is directly proportional to the fluoride ion concentration, and quantitative analysis can be performed by referring to a standard color chart or using a spectrometer.

[0059] The invention will be further illustrated below with specific examples.

[0060] Example 1

[0061] Preparation of silicon nanoparticle suspension

[0062] The morphology of the purchased silicon nanoparticle sample with a diameter of 100 nm was observed; it appeared as a brownish-yellow powder (e.g., ...). Figure 1 First, its structure and optical properties were characterized. SEM images showed that the sample consisted of many spherical nanoparticles (e.g., Figure 2 Random samples were taken and their particle diameters were statistically analyzed. The particle diameters ranged from 55 to 120 nm, with 83.3% falling within the range of 80 to 120 nm. The average diameter was 100.57 nm.

[0063] Using surfactants, silicon nanoparticle samples were stably dispersed in water to prepare homogeneous and stable suspensions with silicon nanoparticle concentrations of 0.01 g / L, 0.02 g / L, 0.03 g / L, and 0.04 g / L, respectively. Figure 3 ).Depend on Figure 3 It can be seen that as the concentration of the suspension increases, the yellow color of the suspension becomes darker.

[0064] The absorption spectra of the four suspensions at different concentrations were quantitatively characterized using a UV-Vis spectrophotometer, revealing that their absorption peaks were all around 460 nm (e.g., Figure 4 The peak value is directly proportional to the concentration of silicon nanoparticles (e.g., Figure 5 As can be seen, changing the content of silicon nanoparticles in the suspension can alter the absorption spectrum and color intensity of the suspension. These results indicate that the quantitative detection of fluoride ions can be achieved by utilizing the specific reaction between fluoride ions and silicon nanoparticles.

[0065] Example 2

[0066] Using a water bath, 10 ppm of fluoride ions were added to the 0.04 g / L silicon nanoparticle suspension prepared in Example 1 at temperatures of 50, 70, and 90 °C. The absorbance of each suspension was measured as a function of reaction time. The results are as follows: Figure 6 As shown.

[0067] Depend on Figure 6 It can be seen that the absorbance of the suspension at 460 nm decreased to 85.2% (50℃), 53.5% (70℃), and 8.7% (90℃), respectively. This means that as the temperature increases, the upper limit of the reaction determined by the low concentration of fluoride ions is broken, indicating that fluoride ions are no longer the main reactant in the overall reaction at this point. The absorption peak of the suspension decreases at a faster rate with increasing temperature, indicating that the silicon nanoparticles react more rapidly.

[0068] In Example 2, the optimal detection conditions for the aqueous solution were found to be approximately 90°C. At this temperature, fluoride ions up to 10 ppm can be detected very easily.

[0069] Example 3

[0070] Using a water bath heating method, at a temperature of 90°C, 0.5 ppm of fluoride ions were added to the 0.04 g / L silicon nanoparticle suspension prepared in Example 1. The absorption spectrum of the suspension was measured every 10 minutes, and the results are as follows: Figure 7 As shown.

[0071] Depend on Figure 7 It can be seen that the addition of fluoride ions can continuously reduce the absorption peak of the suspension. After 30 minutes, the absorbance of the suspension becomes 30% of the initial value, and the suspension becomes visibly transparent.

[0072] Example 4

[0073] Using a water bath at a temperature of 90°C, 0.5, 1, 5, and 10 ppm of fluoride ions were added to the 0.04 g / L silicon nanoparticle suspension prepared in Example 1, respectively. After reacting for 30 min, the absorption spectra of each suspension were measured, and the results are as follows: Figure 8 As shown.

[0074] Depend on Figure 8 It can be seen that after 30 min of reaction, the light absorption intensities of each suspension at 450 nm were 51.7% (0.5 ppm), 30.2% (1 ppm), 21.1% (5 ppm), and 8.7% (10 ppm), respectively, which were the initial values.

[0075] Figure 9 This is a graph showing the relationship between the change in absorbance of the suspension and the concentration of fluoride ions after 30 minutes of reaction. Figure 9 It can be seen that as the concentration of fluoride ions increases, the change in absorbance gradually increases, meaning that more silicon nanoparticles undergo the reaction.

[0076] Figure 10 Optical images of each suspension after 30 minutes of reaction. Figure 10 It can be seen that after 30 minutes, the suspension of different concentrations of fluoride ions exhibits different shades of yellow visible to the naked eye, indicating that under 90℃ conditions, silicon nanoparticles can accurately and visually detect whether the water quality meets the drinking water standard (1ppm).

[0077] Based on the experimental results of Example 4, it can be concluded that fluoride ions at a concentration as low as 0.5 ppm can cause a 48.3% change in absorbance of a silicon nanoparticle suspension at a concentration of 40 ppm. That is, the ratio of the amount of fluoride ions to the amount of silicon reacting is approximately 1:54. It can be inferred that fluoride ions no longer act as reactants in the decolorization reaction of silicon nanoparticles, but most likely act as catalysts. The specific chemical reaction is shown in chemical reaction equation 3.

[0078] Example 5

[0079] Verification of the high-temperature silicon corrosion reaction mechanism

[0080] To confirm the reaction mechanism of the high-temperature silicon corrosion reaction (chemical reaction equation 3), the silicate ions generated were quantitatively analyzed using the silicomolybdate yellow spectrophotometric method. Silicate ions can react with molybdate under acidic conditions of approximately pH 1.2 to form yellow 12-molybdic acid, as shown in chemical reaction equation 4.

[0081]

[0082] The amount of silicate ions can be obtained by comparing the absorbance of the resulting solution with that of the standard solution.

[0083] 0.5 ppm of fluoride ions was added to the 0.04 g / L silicon nanoparticle suspension prepared in Example 1 (absorption spectrum as shown in Figure 1). Figure 11 The system was reacted (as shown in curve I) in a 90°C water bath for 120 minutes, and then became transparent (absorption spectrum as shown in curve I). Figure 11 Curve II in the figure indicates that the silicon nanoparticles have completely reacted. After adding acidic ammonium molybdate, the system turns yellow (absorption spectrum as shown in Figure II). Figure 11 (Curve III in the figure). Its absorption peak at 380 nm comes from 12-molybdenum silicate, indicating the presence of silicate ions in the detection system.

[0084] For quantitative analysis, a silicate solution with the same concentration of silicon as the initial silicon nanoparticle suspension was prepared, and acidic ammonium molybdate was added to this solution. The absorption spectrum of the above solution (e.g.) was observed. Figure 11 Curve IV in the middle) and Figure 11 Curve III is almost identical to the curve in the figure. According to Beer-Lambert law, silicon in silicon nanoparticles is completely converted into silicate ions under the catalytic reaction of fluoride ions, which verifies the mechanism by which fluoride ions are transformed from reactants into catalysts.

[0085] Example 6

[0086] Selective Validation

[0087] Common ions found in groundwater and industrial wastewater were selected as interfering ions, such as Cl. - ,Br - H2PO4 - SO4 2- NO3 - K + Na + Mg 2+ The selectivity and anti-interference properties of fluoride ion detection in silicon nanoparticle systems were studied.

[0088] Under reaction conditions of 90°C, 1 mmol / L of fluoride ions, blank solution (deionized water), and interfering ions were added to the 0.04 g / L silica nanoparticle suspension prepared in Example 1, respectively. After reacting for 30 min, the absorbance of each suspension was measured, and the results are as follows. Figure 12 As shown.

[0089] Depend on Figure 12As can be seen, the absorbance of the suspension with added fluoride ions decreased by 90%, and the suspension became visibly transparent. In contrast, the absorbance decrease of other suspensions was relatively small, not exceeding 16%, and the color change of the suspensions was not perceptible to the naked eye. The results indicate that silicon nanoparticles have excellent selectivity for the detection of fluorides.

[0090] Example 7

[0091] Anti-interference verification

[0092] Common ions found in groundwater and industrial wastewater were selected as interfering ions, such as Cl. - ,Br - H2PO4 - SO4 2- NO3 - K + Na + Mg 2+ The anti-interference ability of silicon nanoparticle system for fluoride ion detection was studied.

[0093] Under reaction conditions of 90°C, a mixture of 1 mmol / L fluoride ions and 1 mmol / L interfering ions was added to the 0.04 g / L silica nanoparticle suspension prepared in Example 1. After reacting for 30 min, the absorbance of each suspension was measured, and the results are as follows. Figure 13 As shown.

[0094] Depend on Figure 13 As can be seen, after reacting at 90℃ for 30 minutes, all suspensions became visibly transparent, and the absorbance decreased significantly by more than 84%. The results indicate that silicon nanoparticles exhibit excellent anti-interference properties for the detection of fluorides.

[0095] Comparative Example 1

[0096] At room temperature, fluoride ions at a concentration of 0.02 mol / L were added to the 0.04 g / L silicon nanoparticle suspension prepared in Example 1. The absorption spectrum of the suspension was measured every 30 minutes, and the results are as follows: Figure 14 As shown.

[0097] Depend on Figure 14 It can be seen that the absorbance of the suspension at 460 nm decreased by 25% after 30 minutes; and by 65% ​​after 120 minutes. The color change of the suspension was also discernible to the naked eye, which confirms that the specific reaction of Si-F can be used to achieve visual detection of fluoride ions.

[0098] Comparative Example 2

[0099] Adding 10 ppm of fluoride ions to the 0.04 g / L (40 ppm) silica nanoparticle suspension prepared in Example 1 at room temperature resulted in a decrease in absorbance of only 4.5% after 120 min (e.g., ...). Figure 15 Furthermore, the color change of the suspension is difficult to discern with the naked eye.

[0100] This phenomenon occurs because the fluoride concentration in the suspension is below the stoichiometric requirement for the Si-F specific reaction. In a system containing 10 ppm fluoride ions, the fluoride ion concentration is 5.26 × 10⁻⁶. -4 The silicon concentration is 1.42 × 10 mol / L. -3 mol / L. The product of the reaction is a colorless fluorosilicate, that is, SiF6 is formed when fluoride ions react completely. 2- At that time, according to the Si-F specific reaction (chemical reaction equation 1), the total amount of silicon nanoparticles reacted did not exceed 6.16%, and Figure 15 The spectral data shown are consistent.

[0101] This indicates that due to the relatively small number of fluoride ions at low concentrations, the amount of silicon reacted is also small, making it difficult to produce a color change that can be observed with the naked eye. Therefore, this system cannot be used for the visual detection of low-concentration fluoride ions.

[0102] Based on the above results, one embodiment of the present invention provides a fluoride ion indicator, which is a solution (such as a silicon nanoparticle suspension) or powder (such as a mixed powder of silicon nanoparticles and surfactant) containing silicon nanoparticles; wherein, the silicon nanoparticles in the fluoride ion indicator can undergo a high-temperature silicon corrosion reaction under the action of fluoride ions at a temperature of 70-100°C.

[0103] One embodiment of the present invention also provides a method for detecting fluoride ion concentration, which can detect fluoride ion concentration by visual colorimetry using the aforementioned fluoride ion indicator.

[0104] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for detecting fluoride ion concentration, characterized in that, include: Silicon nanoparticles are mixed with the solution to be tested to form a mixed solution; The mixed solution is heated to 70~100℃ and maintained at 70~100℃ for a predetermined time, so that the silicon nanoparticles undergo a high-temperature silicon corrosion reaction under the action of fluoride ions; After the predetermined reaction time, the color change of the mixed solution is observed to determine the concentration of fluoride ions in the test solution; In the high-temperature silicon corrosion reaction, silicon nanoparticles are used as the response material. The fluorosilicate generated by the reaction of silicon nanoparticles with fluoride ions is hydrolyzed into hydrogen fluoride, silicic acid and fluoride ions at 70~100℃, so that fluoride ions are recycled in the mixed solution and catalyze the corrosion reaction of silicon nanoparticles. The corrosion reaction causes at least part of the silicon in the silicon nanoparticles to be converted into silicic acid and / or silicate ions, and causes the mixed solution to produce a color change related to the concentration of fluoride ions.

2. The fluoride ion concentration detection method as described in claim 1, characterized in that, The high-temperature silicon corrosion reaction includes the reaction shown in the following reaction equation: 。 3. The method for detecting fluoride ion concentration as described in claim 1, characterized in that, The silicon nanoparticles are mixed with the test solution to form a mixed solution, specifically including: A mixture of silicon nanoparticles and surfactant powder is added to the solution to be tested, and the mixture is mixed to form a mixed solution.

4. The method for detecting fluoride ion concentration as described in claim 1, characterized in that, The silicon nanoparticle suspension contains 0.01~0.04 g / L of silicon nanoparticles.

5. The method for detecting fluoride ion concentration as described in claim 1, characterized in that, The silicon nanoparticles have a particle size between 10 and 1000 nm.

6. The fluoride ion concentration detection method as described in claim 5, characterized in that, The average particle size of the silicon nanoparticles is 95~105 nm.

7. The method for detecting fluoride ion concentration as described in claim 1, characterized in that, The reaction temperature for the high-temperature silicon etching reaction is 90°C.

8. The method for detecting fluoride ion concentration as described in claim 1, characterized in that, The reaction time for the high-temperature silicon etching reaction is 5 to 150 minutes.

9. A fluoride ion indicator for use in the fluoride ion concentration detection method according to any one of claims 1 to 8, characterized in that, The fluoride ion indicator is a solution or powder containing silicon nanoparticles; wherein, the silicon nanoparticles in the fluoride ion indicator can undergo a high-temperature silicon corrosion reaction under the action of fluoride ions at 70~100℃.

10. A method for detecting fluoride ion concentration, characterized in that, The method uses the fluoride ion indicator of claim 9 to detect the fluoride ion concentration by visual colorimetry.

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