Reagent combination and detection method for detecting the concentration of silicon dioxide in boiler water vapor

Abstract

The present invention provides a reagent combination for detecting the concentration of silicon dioxide in boiler water vapor for silicon analyzer detection, including molybdate reagent, masking agent and reducing agent; the masking agent is prepared from citric acid, propionic acid and ultrapure water; the reducing agent is made from cysteine, 2-amino-2-methyl-1-propanol, sodium metabisulfite and ultrapure water. A detection method is also provided, including cleaning the detection vessel and adding the sample to be tested; adding the molybdate reagent to the sample to be tested and mixing evenly; after the molybdate reagent fully reacts, adding the masking agent and mixing evenly; after the masking agent fully reacts and eliminates the interference of phosphate, adding the reducing agent and mixing evenly to obtain a mixed solution; putting the mixed solution into a silicon analyzer to detect the concentration of silicon dioxide in the sample to be tested. In the reagent combination and detection method of the present invention, the detection color reaction is sensitive, and a lower measurement lower limit value is obtained, that is, the silicon detection range can reach less than 10 ug / L, and the lowest can reach 3 ug / L.

Description

Technical Field

[0001] The present invention relates to the technical field of boilers, and specifically to a reagent combination and a detection method for detecting the concentration of silicon dioxide in boiler water vapor. Background Art

[0002] In GB12149-2017 "Determination of Silicon in Industrial Recirculating Water and Boiler Water", the monitoring method for 10-200 μg / l silicon in boiler water is as follows: at (27±5) °C, silicate reacts with molybdate to produce silicon molybdenum yellow, and silicon molybdenum yellow is reduced to silicon molybdenum blue by the reducing agent 1-amino-2-naphthol-4-sulfonic acid, and is determined by spectrophotometry (light source wavelength 640 nm). The specific principle is: when monochromatic light passes through the measured solution, the amount absorbed by the substance is proportional to the concentration of the substance and the thickness of the liquid layer. The relationship is as follows:

[0003] A = -lg(I / I0) = -lgT = kLC

[0004] In the formula: A is the absorbance; I0 is the intensity of the incident monochromatic light; I is the intensity of the transmitted monochromatic light; T is the transmittance of the substance; k is the molar absorption coefficient; L is the optical path of the analyzed substance, that is, the side length of the cuvette; c is the concentration of the substance. This method has the following problems:

[0005] 1. The lack of a masking agent results in the detection results being interfered by phosphates and tannins;

[0006] 2. The product formed by the reaction of water samples below 10 μg / l with molybdate and 124 acid has weak absorption ability for visible light with a wavelength of 640 nm, and the color reaction is not sensitive. Therefore, the lower limit of silicon detection is 10 μg / l.

[0007] However, for some high-parameter boiler steam, the required silicon content is less than or equal to 5 μg / l. When using the method in GB12149 to detect silicon, the silicon detection range no longer matches. Summary of the Invention

[0008] I. Technical Problems to be Solved

[0009] In view of the deficiencies of the prior art, the present invention provides a reagent combination and a detection method for detecting the concentration of silicon dioxide in boiler water vapor, which solves the problem that the prior art cannot accurately detect the silicon concentration below 10 μg / l.

[0010] II. Technical Solutions

[0011] To achieve the above object, the present invention provides the following technical solutions:

[0012] A reagent combination for detecting the concentration of silicon dioxide in boiler water vapor, including a molybdate reagent for detecting by a silicon analyzer. The key lies in that the reagent combination further includes a masking agent and a reducing agent;

[0013] The masking agent is prepared from citric acid, propionic acid and ultrapure water;

[0014] The reducing agent is made from cysteine, 2-amino-2-methyl-1-propanol, sodium metabisulfite and ultrapure water.

[0015] Optionally, the molybdate reagent is made from sulfuric acid at 7-13 wt%, sodium bisulfate at 7-13 wt%, (T-4)-molybdic acid at 5-10 wt% and the balance being ultrapure water;

[0016] Optionally, the masking agent is made from citric acid at 10-20 wt%, propionic acid at 0.1-1 wt% and the balance being ultrapure water;

[0017] Optionally, the reducing agent is made from cysteine at 0.1-1 wt%, 2-amino-2-methyl-1-propanol at 2-10 wt%, sodium metabisulfite at 5-10 wt% and ultrapure water.

[0018] Optionally, the molybdate reagent, the masking agent and the reducing agent are aqueous solution reagents.

[0019] There is also provided a detection method for detecting the concentration of silicon dioxide in boiler water vapor using the reagent combination shown in any of the above examples. The key lies in the following steps:

[0020] S1. Clean the detection vessels and add the sample to be tested;

[0021] S2. Add the molybdate reagent to the sample to be tested and mix evenly;

[0022] S3. After the molybdate reagent has fully reacted, add the masking agent and mix evenly;

[0023] S4. After the masking agent has fully reacted and eliminated the interference of phosphates and tannins, add the reducing agent and mix evenly to obtain a mixed solution;

[0024] S5. Put the mixed solution into a silicon analyzer to detect the concentration of silicon dioxide in the sample to be tested.

[0025] Optionally, the reaction time of the molybdate reagent with the sample to be tested is 4-5 minutes.

[0026] Optionally, the reaction time after adding the masking agent is 1-2 minutes.

[0027] Optionally, the reaction time after adding the reducing agent is 15-20 seconds.

[0028] Optionally, for the detection method of detecting the concentration of silicon dioxide in boiler water vapor, the lowest detection range of the silicon dioxide concentration is 3 μg / L.

[0029] III. Beneficial Effects

[0030] The present invention provides a reagent combination and a detection method for detecting the concentration of silicon dioxide in boiler water vapor. After the water sample reacts with the molybdate reagent, the interference of phosphate and tannin is eliminated by adding a masking agent, and then it is reduced with a reducing agent. The resulting product has a strong absorption capacity for visible light with a wavelength of 815 nm, and the color reaction is sensitive, obtaining a lower measurement lower limit value, that is, the silicon detection range can reach less than 10 μg / L, and the lowest can reach 3 μg / L. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a comparison curve graph of absorbance between the detection method of the present invention and the standard method. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0033] Component description: The reagents used in the present invention are all chemically pure.

[0034] Example 1 A reagent combination for detecting the concentration of silicon dioxide in boiler water vapor, which is composed of a molybdate reagent, a masking agent, and a reducing agent.

[0035] The molybdate reagent is prepared with 7% sulfuric acid, 7% sodium bisulfate, 5% (T-4)-molybdic acid, and ultrapure water.

[0036] The masking agent is prepared with 10% citric acid, 0.1% propionic acid, and ultrapure water.

[0037] The reducing agent is prepared with 0.1% cysteine, 2% 2-amino-2-methyl-1-propanol, 5% sodium metabisulfite, and ultrapure water.

[0038] Example 2 A reagent combination for detecting the concentration of silicon dioxide in boiler water vapor, which is composed of a molybdate reagent, a masking agent, and a reducing agent.

[0039] The molybdate reagent is prepared with 13% sulfuric acid, 13% sodium bisulfate, 10% (T-4)-molybdic acid, and ultrapure water.

[0040] The masking agent is prepared with 20% citric acid, 1% propionic acid, and ultrapure water.

[0041] Prepare a reducing agent by mixing 1% cysteine, 10% 2-amino-2-methyl-1-propanol, 10% sodium metabisulfite and ultrapure water.

[0042] Example 3 A reagent combination for detecting the concentration of silicon dioxide in boiler water vapor, which consists of a molybdate reagent, a masking agent and a reducing agent.

[0043] Prepare a molybdate reagent by mixing 10% sulfuric acid, 10% sodium bisulfate, 8% (T-4)-molybdic acid and ultrapure water.

[0044] Prepare a masking agent by mixing 15% citric acid, 0.5% propionic acid and ultrapure water.

[0045] Prepare a reducing agent by mixing 0.5% cysteine, 6% 2-amino-2-methyl-1-propanol, 8% sodium metabisulfite and ultrapure water.

[0046] Example 4

[0047] I. Preparation of 2 μg / l silicon dioxide standard solution

[0048] Weigh 0.5 g of primary reagent grade silicon dioxide and place it in a platinum crucible. Add 4 g of analytical reagent grade anhydrous sodium carbonate, mix well, and melt in a high-temperature furnace at 1000 °C for 1 hour. After taking it out and cooling, put it into a plastic beaker and dissolve it with hot water (all the water taken below is ultrapure water). Wash the crucible and its cover with water, transfer it into a 250 ml volumetric flask, dilute it to the mark with water, and mix well to obtain a 2 μg / l silicon dioxide standard solution. Measure 3 portions, each portion being 50 ml.

[0049] II. Preparation of 3 μg / l silicon dioxide standard solution

[0050] Weigh 0.75 g of primary reagent grade silicon dioxide and place it in a platinum crucible. Add 4 g of analytical reagent grade anhydrous sodium carbonate, mix well, and melt in a high-temperature furnace at 1000 °C for 1 hour. After taking it out and cooling, put it into a plastic beaker and dissolve it with hot water (all the water taken below is ultrapure water). Wash the crucible and its cover with water, transfer it into a 250 ml volumetric flask, dilute it to the mark with water, and mix well to obtain a 3 μg / l silicon dioxide standard solution. Measure 3 portions, each portion being 50 ml.

[0051] III. Preparation of 5 μg / l silicon dioxide standard solution

[0052] Weigh 1.25 g of primary reagent grade silicon dioxide and place it in a platinum crucible. Add 4 g of analytical reagent grade anhydrous sodium carbonate, mix well, and melt in a high-temperature furnace at 1000 °C for 1 hour. After taking it out and cooling, put it into a plastic beaker and dissolve it with hot water (all the water taken below is ultrapure water). Wash the crucible and its cover with water, transfer it into a 250 ml volumetric flask, dilute it to the mark with water, and mix well to obtain a 5 μg / l silicon dioxide standard solution. Measure 3 portions, each portion being 50 ml.

[0053] IV. Preparation of 10 μg / L Silicon Dioxide Standard Solution

[0054] Weigh 2.5 g of analytical reagent grade silicon dioxide and place it in a platinum crucible. Add 4 g of analytical reagent grade anhydrous sodium carbonate, mix well, and melt it in a high-temperature furnace at 1000 °C for 1 hour. After taking it out and cooling, put it into a plastic beaker and dissolve it with hot water (all water taken hereinafter is ultrapure water). Wash the crucible and its cover with water, transfer them into a 250 ml volumetric flask, dilute it to the calibration line with water, mix well to obtain a 10 μg / L silicon dioxide standard solution, and measure 3 portions, each portion being 50 ml.

[0055] V. Detection

[0056] Use the molybdate solvent, masking agent, and reducing agent prepared in Examples 1 - 3 to detect 2 μg / L, 3 μg / L, 5 μg / L, and 10 μg / L silicon dioxide standard solutions respectively according to the following detection methods.

[0057] Detection Method:

[0058] 1. Rinse a plastic conical flask clean with ultrapure water and add 50 ml of the sample to be measured.

[0059] 2. Add 1 ml of molybdate reagent to each conical flask, shake well, and react for 4 minutes.

[0060] 3. Add 1 ml of masking agent to the conical flask, shake well, and react for 1 minute to eliminate the interference of phosphate and tannin.

[0061] 4. Add 1 ml of cysteine reagent to the conical flask, shake well, and after 15 seconds, use a silicon analyzer with a light source of wavelength 815 nm to detect the silicon concentration by spectrophotometry.

[0062] VI. Obtain the silicon dioxide concentration value and compare it one - to - one with the silicon dioxide concentration value in the standard solution. The results are shown in the following table:

[0063] Standard solution Measured value Standard solution Measured value Standard solution Measured value Standard solution Measured value Example 1 2 ug / l 0 3 ug / l 3 ug / l 5 ug / l 5 ug / l 10 ug / l 10 ug / l Example 2 2 ug / l 0 3 ug / l 3 ug / l 5 ug / l 5 ug / l 10 ug / l 10 ug / l Example 3 2 ug / l 0 3 ug / l 3 ug / l 5 ug / l 5 ug / l 10 ug / l 10 ug / l

[0064] VII. Compare the absorbance of the detection method of the present invention with that of the GB12149 - 2017 Boiler Water Silicon Standard Detection Method. The results are as Figure 1 shown. The lowest measurement lower limit value of the standard detection method can only reach 10 μg / L, while the detection method of the present invention can reach a lower measurement lower limit value, and the lowest can reach 3 μg / L.

[0065] It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0066] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A reagent combination for detecting the silica concentration in boiler water vapor, including a molybdate reagent for detection by a silicon analyzer, characterized in that: The reagent combination further includes a masking agent and a reducing agent; The masking agent is made of citric acid at 10-20% by weight, propionic acid at 0.1-1% by weight, and the balance being ultrapure water; The reducing agent is made of cysteine, 2-amino-2-methyl-1-propanol, sodium metabisulfite, and ultrapure water.

2. The reagent combination for detecting the concentration of silicon dioxide in boiler water vapor according to claim 1, characterized in that: The molybdate reagent is made of sulfuric acid at 7-13% by weight, sodium bisulfate at 7-13% by weight, (T-4)-molybdic acid at 5-10% by weight, and the balance being ultrapure water.

3. A reagent combination for detecting the concentration of silicon dioxide in boiler water vapor according to claim 1 or 2, characterized in that: The reducing agent is made of cysteine at 0.1-1% by weight, 2-amino-2-methyl-1-propanol at 2-10% by weight, sodium metabisulfite at 5-10% by weight, and ultrapure water.

4. A reagent combination for detecting the concentration of silicon dioxide in boiler water vapor according to claim 3, characterized in that: The molybdate reagent, the masking agent, and the reducing agent are aqueous solution reagents.

5. A detection method for detecting the concentration of silicon dioxide in boiler water vapor using the reagent combination according to any one of claims 1 to 4, characterized in that, It is carried out in the following manner: S1. Clean the test vessel and add the sample to be tested; S2. Add the molybdate reagent to the sample to be tested and mix evenly; S3. After the molybdate reagent has fully reacted, add the masking agent and mix evenly; S4. After the masking agent has fully reacted and eliminated the interference of phosphate, add the reducing agent and mix evenly to obtain a mixed solution; S5. Put the mixed solution into a silicon analyzer to detect the concentration of silicon dioxide in the sample to be tested.

6. The detection method for detecting the concentration of silicon dioxide in boiler water vapor according to claim 5, characterized in that: The reaction time of the molybdate reagent and the sample to be tested is 4-5 minutes.

7. The detection method for detecting the concentration of silicon dioxide in boiler water vapor according to claim 5, characterized in that: The reaction time after adding the masking agent is 1-2 minutes.

8. The detection method for detecting the concentration of silicon dioxide in boiler water vapor according to claim 5, characterized in that: The reaction time after adding the reducing agent is 15-20 seconds.

9. The detection method for detecting the concentration of silicon dioxide in boiler water vapor according to claim 5, characterized in that: The detection range of the silicon dioxide concentration is at least 3 μg / L.

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