A method for determining low-content boron oxide in glass by photometric analysis

Abstract

The invention discloses a method for determining low-content boron oxide in glass by photometric analysis, S1, grinding the glass sample into powder, drying, digesting after adding alkali solution, acidifying, and finally constant volume to make sample solution; S2, preparing standard solution, adding acetic acid-ammonium acetate buffer solution and azomethine-H color developer, placing in a dark place for color development after ultrasonic oscillation, and finally measuring absorbance at 420nm on a UV-visible spectrophotometer, and drawing a standard curve; S3, adding buffer solution and color developer to the sample solution, measuring absorbance after ultrasonic oscillation and color development, and calculating the concentration of boron element in the sample according to the standard curve obtained by S2. The present invention provides a method for detecting boron oxide element in glass with quick and simple operation, low detection limit and good reproducibility, which is suitable for detection in most glass factories.

Description

Technical Field

[0001] The present invention relates to the technical field of glass production and to the control of glass quality, and in particular to a method for determining low-content boron oxide in glass by photometric analysis. Background Art

[0002] The determination of boron oxide content in glass mostly adopts the national standard GB / T 1549-2008 "Chemical Analysis Method for Fiber Glass". In terms of pretreatment, a nickel crucible is used with NaOH as a flux, and an appropriate amount of sample is added to melt on an electric furnace. After cooling, it is washed out with hydrochloric acid and hot water. This operation is relatively cumbersome, the melting time is long, and temperature control is particularly important. Impurities are also easily introduced during acidification and washing, affecting the final detection. In addition, high-aluminum glass is often unable to be completely dissolved.

[0003] In GB / T 1549-2008 "Chemical Analysis Methods for Fiber Glass", boric oxide detection adopts the mannitol volumetric method, using phenolphthalein as the indicator, requiring the titration endpoint to be slightly red, and the pH range of phenolphthalein color change is 8.0-9.6. The color change process is not easy to identify, and the human operation error is large. In addition, some metal oxides in electronic glass will also affect the final reaction. The precision of this method for determining boric oxide requires a repeatability limit of 0.20% and a reproducibility limit of 0.25%. Obviously, the error is large and it is not suitable for low-content boric oxide detection in glass.

[0004] In view of this, some testing agencies have proposed using inductively coupled plasma optical emission spectrometry to determine the boron content in glass. This method is accurate and rapid, but the equipment cost is often millions, and the cost is relatively high, making it unsuitable for promotion and use in ordinary glass factories. Summary of the invention

[0005] The invention provides a method for determining low-content boron oxide in glass by photometric analysis. The detection is fast and accurate. The equipment involved is also a spectrophotometer commonly available in glass factories, and the detection cost is low.

[0006] The technical solution of the present invention is a method for determining low-content boron oxide in glass by photometric analysis, comprising the following steps:

[0007] S1. Grind the glass sample into powder, dry it, then add alkali solution to digest it, add acid solution to neutralize it after digestion, and finally make a fixed volume to prepare a sample solution;

[0008] S2. Prepare standard solutions with different concentrations of boric oxide, add acetic acid-ammonium acetate buffer solution and azomethine-H color developer to each standard solution, place in a dark place for color development after ultrasonic oscillation, and finally measure the absorbance at 420 nm on a UV-visible spectrophotometer. During the measurement, use the reagent blank as a reference, the absorbance as the X-axis, and the concentration as the Y-axis to obtain a working curve, make a linear regression equation, and calculate the correlation coefficient;

[0009] S3. Add acetic acid-ammonium acetate buffer solution and azomethine-H color developer to the sample solution, place in a dark place for color development after ultrasonic oscillation, and finally measure the absorbance at 420 nm on a UV-visible spectrophotometer. Calculate the boron oxide content in the sample based on the standard curve obtained in S2.

[0010] Furthermore, the glass sample in S1 is ground by a vibration mill, an automatic sample grinder or an agate mortar, passed through a 200-mesh sieve, and the sieve-undergrowth is taken out and dried in an oven at 100-120° C. for 1-2 hours.

[0011] Furthermore, the glass in S1 is high-aluminum glass. When weighing the sample and grinding it to prepare the sample solution in S1, the sample mass is less than 0.1 g, and KOH is used as the alkali solution for digestion. Otherwise, the sample will not be dissolved.

[0012] Furthermore, the alkaline solution during the digestion of S1 is KOH or NaOH, and a polytetrafluoroethylene digestion tank is used for digestion, and the digestion is performed in a microwave digestion instrument; after the digestion is completed, 15 mL to 30 mL of ultrapure water is added to the digestion tank and heated in an acid removal instrument to remove the acid.

[0013] Furthermore, the acid added during the neutralization of S1 is hydrochloric acid, and the solution is neutral or weakly acidic after neutralization. After the acid is removed by the acid removal instrument, the instrument is turned off, and the residual temperature is used to continue heating for 5 minutes to 10 minutes. After clarification, the solution is taken out and cooled, and finally the volume is fixed.

[0014] Furthermore, the concentrations of the boron oxide standard solution in S1 are 0.08 mg / L, 0.16 mg / L, 0.24 mg / L, 0.32 mg / L, 0.40 mg / L, and 0.48 mg / L.

[0015] Furthermore, in S2 and S3, the pH of the acetic acid-ammonium acetate buffer solution is 5.4; the ultrasonic oscillation temperature is 35° C. to 40° C., the time is 10 min to 15 min, and the color development time is 1.5 hours to 2 hours.

[0016] Furthermore, in S2 and S3, the azomethine-H color developer is prepared and used immediately. Specifically, 0.5 g azomethine-H and 2.0 g ascorbic acid are added to 100 mL of water and ultrasonically oscillated at below 50° C. for 10 min to 15 min to dissolve the obtained color developer.

[0017] Furthermore, the calculation formula for the boron oxide content in the sample is:

[0018]

[0019] Where:

[0020] X-boron oxide content in the sample;

[0021] C- boron concentration in the sample solution, in milligrams per liter;

[0022] C0- boron concentration in blank solution, in milligrams per liter;

[0023] V-the volume of the solution aspirated in step 6, in milliliters;

[0024] M B2O3 - Boron oxide molecular weight;

[0025] M B -Molecular weight of the element boron.

[0026] Furthermore, in the method, the water used is ultrapure water, and the reagents are high-grade pure reagents.

[0027] The present invention has the following beneficial effects:

[0028] The invention provides a method for detecting boron oxide in glass, which has the advantages of quick and simple operation, low detection limit and good reproducibility, and is suitable for detection in most glass factories.

[0029] If the glass being tested is high-aluminum glass, when its mass fraction, measured in terms of aluminum oxide, is greater than or equal to 10%, KOH must be used for digestion. The remaining alkali solution cannot completely digest it, and the sampling volume must be controlled below 0.1g, otherwise a clear solution cannot be obtained later.

[0030] The present invention can greatly shorten the color development time in the later stage by performing ultrasonic oscillation treatment after adding the color developer. Similarly, during the preparation of the color developer, performing ultrasonic oscillation can also help shorten the color development time. See Table 2 in Example 1 for details. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the standard curve of the boron content in the standard solution of Example 1.

[0032] Figure 2 This is the standard curve of the boron content in the standard solution of Example 2.

[0033] Figure 3 This is the standard curve of the boron content in the standard solution of Example 3.

[0034] Figure 4This is the standard curve of the recovery rate of the boron content in the standard solution of Example 3. DETAILED DESCRIPTION

[0035] The embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0036] Embodiment 1:

[0037] Weigh 0.0701g of the ground, dried and cooled glass sample into a polytetrafluoroethylene digestion tank, add 7mL of 50% KOH solution, and digest according to the parameters shown in Table 1. After the digestion is completed, add 20mL of ultrapure water into the digestion tank, heat at 120℃ in an acid-dripping instrument for 5min, then add 10mL of hydrochloric acid (mixed with concentrated hydrochloric acid and water in a volume ratio of 1:1), turn off the acid-dripping instrument and continue heating for 5min with residual heat, take out and cool after clarification, transfer to a 100mL plastic volumetric flask and make up the volume, draw 5mL of the above solution into a 25mL plastic volumetric flask, add 6mL of buffer solution and 6mL of azomethine-H color developer and make up the volume, set the water temperature at 40℃ for ultrasonic oscillation for 15min, then place in the dark for color development for 1.5h, and measure the absorbance at 420nm on a UV-visible spectrophotometer.

[0038] Prepare standard solutions of different concentrations; the concentrations of the boron oxide standard solutions (unit: mg / L) are 0.08 mg / L, 0.16 mg / L, 0.24 mg / L, 0.32 mg / L, and 0.40 mg / L; add 6 mL of acetic acid-ammonium acetate buffer solution and 6 mL of azomethine-H color developer to each standard solution, set the water temperature at 40°C for ultrasonic oscillation for 15 minutes, and then place in the dark for color development for 1.5 hours. Finally, measure the absorbance at 420 nm on a UV-visible spectrophotometer using a 1 cm colorimetric dish. During the measurement, use the reagent blank as a reference, the absorbance as the X-axis, and the concentration as the Y-axis to obtain a working curve, make a linear regression equation, and calculate the correlation coefficient;

[0039] Regarding the color development test using ultrasonic oscillation, this embodiment uses no ultrasonic oscillation and different ultrasonic times and color development times as comparative tests. The result of using ultrasonic oscillation for 10 minutes and then placing it in a dark place for color development for more than 1 hour is similar to the result of not using ultrasonic oscillation and placing it in a dark place for color development for more than 3 hours. The test shows that accurate detection can be achieved by using ultrasonic oscillation for 10 minutes and then placing it in a dark place for color development for 1 to 1.5 hours, which greatly shortens the color development time. See Table 2 for details.

[0040] Sample test results and standard curves are shown in Figure 1The concentration of boron in the sample was calculated based on the obtained standard curve. The boron content in the sample solution was 0.36064 mg / L. The boron oxide content in the sample was calculated to be 0.83%. The sample was simultaneously detected by ICP-AES and the result was 0.83%, which was consistent with the detection result in the invention.

[0041]

[0042] Table 1

[0043]

[0044] Table 2

[0045] Example 2

[0046] Weigh 0.1007g of ground, dried and cooled glass sample into a polytetrafluoroethylene digestion tank, add 9mL of 50% KOH solution, and digest according to the parameters shown in Table 1. After digestion, add 20mL of ultrapure water into the digestion tank, heat at 120℃ in an acid remover for 5min, then add 12mL of hydrochloric acid (prepared with a volume ratio of concentrated hydrochloric acid to water of 1:1), turn off the acid remover and continue heating for 5min with residual heat, take out and cool after clarification, transfer to a 100mL plastic volumetric flask and make up to volume, draw 5mL of the above solution into a 25mL plastic volumetric flask, add 6mL of buffer solution and 5mL of azomethine-H color developer and make up to volume, set the water temperature at 40℃ for ultrasonic oscillation for 15min, place in the dark for color development for 1.5h, and measure the absorbance at 420nm on a UV-visible spectrophotometer.

[0047] Prepare standard solutions of different concentrations; the concentrations of the boron oxide standard solutions (unit: mg / L) are 0.08 mg / L, 0.16 mg / L, 0.24 mg / L, 0.32 mg / L, and 0.40 mg / L; add 6 mL of acetic acid-ammonium acetate buffer solution and 6 mL of azomethine-H color developer to each standard solution, set the water temperature at 40°C for ultrasonic oscillation for 15 minutes, and then place in the dark for color development for 1.5 hours. Finally, measure the absorbance at 420 nm on a UV-visible spectrophotometer using a 1 cm colorimetric dish. During the measurement, use the reagent blank as a reference, the absorbance as the X-axis, and the concentration as the Y-axis to obtain a working curve, make a linear regression equation, and calculate the correlation coefficient;

[0048] Sample test results and standard curves are shown in Figure 1 The concentration of boron in the sample was calculated based on the obtained standard curve. The boron content in the sample solution was 0.27442 mg / L, and the boron oxide content in the sample was calculated to be 0.44%. The sample test results and standard curve are shown in Figure 2 The result of simultaneous detection of the sample by ICP-AES was 0.45%, which is close to the detection result in the invention.

[0049] Example 3

[0050] Weigh 0.1203g of the ground, dried and cooled glass sample into a polytetrafluoroethylene digestion tank, add 10mL of 50% KOH solution, and digest according to the parameters shown in Table 1. After the digestion is completed, add 20mL of ultrapure water into the digestion tank, heat at 120℃ in an acid-dripping instrument for 5min, then add 13mL of hydrochloric acid (prepared with a volume ratio of concentrated hydrochloric acid to water of 1:1), turn off the acid-dripping instrument and continue heating for 5min with the residual temperature. After clarification, take out and cool, transfer to a 100mL plastic volumetric flask and make up the volume. Pipette 6mL of the above solution into a 25mL plastic volumetric flask, add 6mL of buffer solution and 5mL of azomethine-H color developer and make up the volume. Set the water temperature to 40℃ for ultrasonic oscillation for 15min and place in the dark for color development for 1.5h. Measure the absorbance at 420nm on a UV-visible spectrophotometer.

[0051] Prepare standard solutions of different concentrations; the concentrations of the boron oxide standard solutions (unit: mg / L) are 0.08 mg / L, 0.16 mg / L, 0.24 mg / L, 0.32 mg / L, and 0.40 mg / L; add 6 mL of acetic acid-ammonium acetate buffer solution and 6 mL of azomethine-H color developer to each standard solution, set the water temperature at 40°C for ultrasonic oscillation for 15 minutes, and then place in the dark for color development for 1.5 hours. Finally, measure the absorbance at 420 nm on a UV-visible spectrophotometer using a 1 cm colorimetric dish. During the measurement, use the reagent blank as a reference, the absorbance as the X-axis, and the concentration as the Y-axis to obtain a working curve, make a linear regression equation, and calculate the correlation coefficient;

[0052] Sample test results and standard curves are shown in Figure 1 The concentration of boron in the sample was calculated based on the obtained standard curve. The boron content in the sample solution was 0.14016 mg / L, and the boron oxide content in the sample was calculated to be 0.16%. The sample test results and standard curve are shown in Figure 3 The result of simultaneous detection of the sample by ICP-AES was 0.16%, which is close to the detection result in the invention.

[0053] Example 3 Spiked Recovery

[0054] The steps are the same as those in Example 3. After 6 mL of the sample solution is drawn into a 25 mL plastic volumetric flask, 1 mL of a 0.2 mg / L boron standard solution is added and the test is performed in the same manner. The results and the standard curve are shown in FIG. Figure 4 The calculated spike recovery rate is (0.33882-0.14016) / 2×100%=99.33%.

[0055] According to the above method, 0.5mL and 1mL of 0.2mg / L boron standard solution were added respectively, and the detection was performed 6 times according to the same method. The calculated spiked recovery rate was 97.31% to 103.22%, which was a good effect.

Claims

1. A method for determining low-content boron oxide in glass by photometric analysis, characterized in that: The following steps are involved: S1. Grind the glass sample into powder, dry it, then add alkali solution to digest it, add acid solution to neutralize it after digestion, and finally make the sample solution by constant volume; the alkali solution for digestion is KOH or NaOH, and a polytetrafluoroethylene digestion tank is used for digestion, and digestion is carried out in a microwave digestion instrument; after digestion, 15mL to 30mL of ultrapure water is added to the digestion tank and heated in an acid removal instrument to remove acid; the acid added during neutralization is hydrochloric acid, and the solution is neutral or weakly acidic after neutralization. After the acid removal is completed by the acid removal instrument, the instrument is turned off, and the residual temperature is used to continue heating for 5min to 10min, and after clarification, it is taken out and cooled, and finally the volume is constant; S2. Prepare standard solutions with different concentrations of boric oxide, add acetic acid-ammonium acetate buffer solution and azomethine-H color developer to each standard solution, place in a dark place for color development after ultrasonic oscillation, and finally measure the absorbance at 420 nm on a UV-visible spectrophotometer. During the measurement, use the reagent blank as a reference, the absorbance as the X-axis, and the concentration as the Y-axis to obtain a working curve, make a linear regression equation, and calculate the correlation coefficient; S3, adding acetic acid-ammonium acetate buffer solution and azomethine-H color developer to the sample solution, placing it in a dark place for color development after ultrasonic oscillation, and finally measuring the absorbance at 420nm on a UV-visible spectrophotometer, and calculating the content of boron oxide in the sample according to the standard curve obtained in S2; the calculation formula for the content of boron oxide in the sample is: ； Where: X-boron oxide content in the sample; C- boron concentration in the sample solution, in milligrams per liter; C0- boron concentration in blank solution, in milligrams per liter; V-the volume of the solution aspirated in step 6, in milliliters; M B2O3 - Boron oxide molecular weight; M B - Molecular weight of boron; The pH value of the acetic acid-ammonium acetate buffer solution is 5.4; the ultrasonic oscillation temperature is 35°C to 40°C, the time is 10min to 15min, and the color development time is 1.5 hours to 2 hours; the azomethine-H color developer is prepared and used immediately, specifically using 0.5g of azomethine-H and 2.0g of ascorbic acid, adding 100mL of water, and dissolving after ultrasonic oscillation at below 50°C for 10min to 15min.

2. The method according to claim 1, characterized in that: The glass sample in S1 is ground by a vibration mill, an automatic sample grinder or an agate mortar, passed through a 200-mesh sieve, and the sieve-free material is taken and dried in an oven at 100-120°C for 1-2 hours.

3. The method according to claim 1, characterized in that: The glass in S1 is high aluminum glass. In S1, when the sample is weighed and ground to prepare the sample solution, the sample mass is less than 0.1 g; and KOH is used as the alkali solution for digestion.

4. The method according to claim 1, characterized in that: The concentrations of the boric oxide standard solution in S1 are 0.08 mg / L, 0.16 mg / L, 0.24 mg / L, 0.32 mg / L, 0.40 mg / L and 0.48 mg / L.

5. The method according to any one of claims 1 to 4, characterized in that: In this method, the water used is ultrapure water and the reagents are high-grade pure reagents.

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