CN101344489B - Method for measuring calcium constituent in silicon aluminum calcium barium alloy - Google Patents

Abstract

The invention discloses a method used for measuring the calcium element in a silicon, aluminum, calcium and barium alloy, which comprises the following steps: a test sample is placed in a beaker, and deionized water is added until the test sample is wet; 9.5 to 10.5 millimeter of nitric acid is added; 1 to 2 millimeter of hydrofluoric acid is titrated; the mixture solution is heated until completely dissolved; perchloric acid is added; the mixture solution is heated until the sample volume is reduced to 1 to 2 millimeter; the mixture solution is naturally cooled; the perchloric acid is further added, and the mixture solution is heated until the sample volume is reduced to 1 to 2 millimeter; the hydrochloric acid and the deionized water are further added; the mixture solution is heated until all salts are dissolved, and the mixture solution is naturally cooled until the temperature is lower than 40 DEG C; the test sample is placed into a volumetric flask with scales and diluted with the deionized water; a mother solution is placed into a trigonal cup, the deionized water, trolamine (1 added by 1), lemery, bitter salt and an calcon-carboxylic acid are added, and the mother solution is adjusted to be red with potassium hydroxide; the potassium hydroxide is further added; EDTA is titrated until an end point that the mother solution becomes blue; and an analyzing result is computed. The method does not need precipitation separation and filtration, and has the acute end point without intermediate color and improved measuring accuracy.

Description

A kind of method for measuring calcium element in silicon-aluminum-calcium-barium alloy

technical field

The invention relates to the field of analytical chemistry, and more belongs to an analysis method for determining calcium element in silicon-aluminum-calcium-barium alloy by adopting EDTA direct titration method.

Background technique

At present, the detection method of calcium in silicon-aluminum-calcium-barium alloy generally adopts ammonia water to separate iron and aluminum, ammonium persulfate to separate manganese, potassium sulfate to precipitate barium, calcium indicator as indicator, and EDTA titration. This method is cumbersome to operate, has a long analysis cycle and high cost.

In order to improve the work efficiency of analysis and detection, people have done a lot of work on elemental analysis in silicon-aluminum-calcium-barium alloys and achieved certain results. Determination of Barium and Calcium in "Meter" article discloses a method for simultaneously measuring barium and calcium content only by dissolving the sample once. After analysis, although this method can measure the content of barium and calcium at the same time, its disadvantages are: the first is that the calcium in the solution is not fully released due to the one-time addition of 20 ml of perchloric acid; the second is that the discoloration reaction at the end of the solution is slow , there is a transitional color; the third is that the pH value of the solution is unstable due to the one-time addition of 20 milliliters of potassium hydroxide, and the reproducibility is poor; the fourth is that the environment is polluted due to the addition of more hydrofluoric acid; five. It is necessary to filter.

Contents of the invention

The object of the present invention is to overcome the above-mentioned deficiencies, and to provide a method for analyzing and measuring calcium in silicon-aluminum-calcium-barium alloys with short time, sufficient calcium release, sensitive discoloration reaction at the end of the solution, stable pH value of the solution, and high accuracy of analysis and determination. Analytical method for calcium element in aluminum calcium barium alloy.

Technical measures to achieve the above purpose:

A method for measuring calcium element in silicon-aluminum-calcium-barium alloy, its steps:

1) Take 0.1-1.0 g of the sample and place it in a polytetrafluoroethylene beaker, and add deionized water until the sample is wet;

2) Add 9.5-10.5 ml of nitric acid;

3) Add 1-2 ml of hydrofluoric acid dropwise;

4) Heating on the electric heating plate until the sample is completely dissolved;

5) Add 4.5-5.5 ml of perchloric acid;

6) Heating at 170-190°C until the volume of the sample shrinks to 1-2 ml;

7) Cool naturally to 25-35°C;

8) Add 4.5-5.5 ml of perchloric acid, and heat at 170-190°C until the volume of the sample shrinks to 1-2 ml;

9) Add 9.5-10.5 ml of hydrochloric acid and 45-55 ml of deionized water;

10) Heat at 100-120°C until the salt dissolves, take it off, and cool the sample to below 40°C by natural cooling;

11) Place the cooled sample into a volumetric flask with a scale of 100 milliliters, dilute to the scale of 100 milliliters with deionized water and shake evenly, and the preparation of the mother liquor is completed;

12) Take 20-30 ml of the mother liquor and place it in a triangular cup or beaker, and add no more than 50 ml of deionized water, 20 ml of triethanolamine solution mixed with 1 part of water and 1 part of triethanolamine, 10% (mass concentration 10 milliliters of potassium sulfate ), 5 milliliters of magnesium sulfate of 5% (mass concentration), 0.1 to 0.2 grams of calcium indicator, and the solution is adjusted to red with the potassium hydroxide whose volume mass concentration is 200 grams/liter;

13) adding 10 milliliters of potassium hydroxide whose volume mass concentration is 200 grams per liter;

14) Use EDTA to titrate to blue as the end point;

15) Calculation of analysis results: Calculate the mass percentage (%) of calcium according to the following formula:

$\mathrm{<span\; class="notranslate">\; Ca</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 40.08</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 1000</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 100</span>}$

In the formula: C——concentration mol/L of EDTA standard titration solution;

V—the volume of EDTA standard titration solution consumed by the test solution, ml;

m——The amount of the test material taken from the test solution, g;

40.08—the molar mass of calcium, g/mol.

Compared with the prior art, the present invention does not need to use ammonia water to separate iron and aluminum, ammonium persulfate to separate manganese, and directly uses triethanolamine to cover iron, aluminum, manganese and other components; no precipitation and separation are required, which reduces the number of operating links and measurement Uncertainty; sulfate precipitates barium, eliminates the interference of barium, and does not need to be filtered; adding a small amount of magnesium sulfate makes the end point sharp and improves the accuracy of the measurement.

Detailed ways

Calculation of the analytical results of the following examples: all calculate the mass percentage (%) of calcium according to the following formula:

$\mathrm{<span\; class="notranslate">\; Ca</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 40.08</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 1000</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; .</span>$

Example 1

A method for measuring calcium element in silicon-aluminum-calcium-barium alloy, its steps:

1) Take 0.1000 g of the sample (YSB14612Ca: 9.25%) and place it in a polytetrafluoroethylene beaker, and add deionized water until the sample is wet;

2) Add 10 milliliters of nitric acid;

3) Add 1 ml of hydrofluoric acid dropwise;

4) Heating on the electric heating plate until the sample is completely dissolved;

5) Add 4.5 milliliters of perchloric acid;

6) Heating at 170°C until the volume of the sample is reduced to 2 ml;

7) Natural cooling to 25°C;

8) Add 4.5 ml of perchloric acid, and heat at 170°C until the volume of the sample is reduced to 2 ml;

9) Add 10 milliliters of hydrochloric acid and 50 milliliters of deionized water;

10) Heat at 100°C until the salt dissolves, remove the sample and cool it to 38°C by natural cooling;

11) Place the cooled sample into a volumetric flask with a scale of 100 milliliters, dilute to the scale of 100 milliliters with deionized water and shake evenly, and the preparation of the mother liquor is completed;

12) Take 20 milliliters of the mother liquor and place it in a triangular cup or beaker, and add no more than 50 milliliters of deionized water, 20 milliliters of triethanolamine (1+1), 10 milliliters of potassium sulfate of 10% (mass concentration), 5 % (mass concentration) magnesium sulfate 5 milliliters, calcium indicator 0.1 gram, and be 10 milliliters of potassium hydroxides of 200 grams per liter that solution is adjusted to red with volume mass concentration;

13) adding 10 milliliters of potassium hydroxide with a volume mass concentration of 200 grams per liter;

14) Use 0.005 mol/liter of EDTA to titrate to blue as the end point, and the titration volume of EDTA is 9.25 milliliters.

15) After calculation, the content of calcium is 9.27%

Example 2

A method for measuring calcium element in silicon-aluminum-calcium-barium alloy, its steps:

1) Take 0.2800 g of the sample (YSB14612Ca: 9.25%) and place it in a polytetrafluoroethylene beaker, and add deionized water until the sample is wet;

2) Add 10 milliliters of nitric acid;

3) Add 1 ml of hydrofluoric acid dropwise;

4) Heating on the electric heating plate until the sample is completely dissolved;

5) Add 4.5 milliliters of perchloric acid;

6) Heating at 180°C until the volume of the sample is reduced to 1.5 ml;

7) Natural cooling to 25°C;

8) Add 4.5 milliliters of perchloric acid, and heat at 180°C until the volume of the sample is reduced to 1.5 milliliters;

9) Add 10 milliliters of hydrochloric acid and 50 milliliters of deionized water;

10) Heat at 100°C until the salts are dissolved, remove the sample and cool it to below 35°C by natural cooling;

11) Place the cooled sample into a volumetric flask with a scale of 100 milliliters, dilute to the scale of 100 milliliters with deionized water and shake evenly, and the preparation of the mother liquor is completed;

12) Take 20 milliliters of the mother liquor and place it in a triangular cup or a beaker, and add no more than 50 milliliters of deionized water, 20 milliliters of triethanolamine (1+1), 10 milliliters of potassium sulfate of 10% (mass concentration), 5 % (mass concentration) magnesium sulfate 5 milliliters, calcium indicator 0.15 gram, and be 200 g/L potassium hydroxide that solution 10 milliliters is adjusted to be red with volumetric mass concentration;

13) adding 10 milliliters of volume mass concentration is 200 g/L potassium hydroxide;

14) Use 0.01 mol/liter of EDTA to titrate to blue as the end point, and the titration volume of EDTA is 12.93 milliliters.

15) After calculation, the content of calcium is 9.25%

Example 3

A method for measuring calcium element in silicon-aluminum-calcium-barium alloy, its steps:

1) Take 0.6 grams of the sample (YSB14612Ca: 9.25%) and place it in a polytetrafluoroethylene beaker, and add deionized water until the sample is wet;

2) Add 10.5 milliliters of nitric acid;

3) 1.5 milliliters of hydrofluoric acid was added dropwise;

4) Heating on the electric heating plate until the sample is completely dissolved;

5) Add 5.0 milliliters of perchloric acid;

6) Heating at 185°C until the volume of the sample is reduced to 1.3 ml;

7) Natural cooling to 28°C;

8) Add 5.0 ml of perchloric acid, and heat at 190°C until the volume of the sample is reduced to 1.3 ml;

9) Add 9.5 milliliters of hydrochloric acid and 50 milliliters of deionized water;

10) Heat at 110°C until completely dissolved, take it off, and cool the sample to 30°C by natural cooling;

11) Place the cooled sample into a volumetric flask with a scale of 100 milliliters, dilute to the scale of 100 milliliters with deionized water and shake evenly, and the preparation of the mother liquor is completed;

12) Take 25 milliliters of mother liquor and place in a triangular cup, and add 50 milliliters of deionized water, 20 milliliters of triethanolamine (1+1), 10 milliliters of potassium sulfate of 10% concentration, 5 milliliters of magnesium sulfate of 5% concentration, Calcium indicator 0.1 gram, and be that 10 milliliters of potassium hydroxides of 200g/L are adjusted to red with volume mass concentration;

13) adding 10 milliliters of potassium hydroxide whose volume mass concentration is 200g/L;

14) Use 0.01 mol/L EDTA to titrate to blue as the end point, and the titration volume of EDTA is 34.60mL

15) After calculation, the content of calcium is 9.24%.

Example 4

A method for measuring calcium element in silicon-aluminum-calcium-barium alloy, its steps:

1) Take 1.0 g of the sample (YSB14612Ca: 9.25%) and place it in a polytetrafluoroethylene beaker, and add deionized water until the sample is wet;

2) Add 10.5 milliliters of nitric acid;

3) Add 2.0 milliliters of hydrofluoric acid dropwise;

4) Heating on the electric heating plate until the sample is completely dissolved;

5) Add 5.5 milliliters of perchloric acid;

6) Heating at 190°C until the volume of the sample is reduced to 1.0 ml;

7) Natural cooling to 30°C;

8) Add 5.5 ml of perchloric acid, and heat at 190°C until the volume of the sample is reduced to 1.0 ml;

9) Add 9.5 milliliters of hydrochloric acid and 55 milliliters of deionized water;

10) Heat at 120°C until completely dissolved, take it off, and cool the sample to 28°C by natural cooling;

11) Place the cooled sample into a volumetric flask with a scale of 100 milliliters, dilute to the scale of 100 milliliters with deionized water and shake evenly, and the preparation of the mother liquor is completed;

12) Take 30 milliliters of the mother liquor and place it in a triangular cup, and add 50 milliliters of deionized water, 20 milliliters of triethanolamine (1+1), 10 milliliters of potassium sulfate at a concentration of 10%, 5 milliliters of magnesium sulfate at a concentration of 5%, and calcium 0.1 gram of indicator, and the solution is adjusted to red with 10 milliliters of potassium hydroxide of 200 g/L in volume mass concentration;

13) adding 10 milliliters of potassium hydroxide with a volume mass concentration of 200 g/L;

14) Use 0.02mol/L EDTA to titrate to blue as the end point, and the titration volume of EDTA is 34.6mL.

15) After calculation, the content of calcium is 9.26%.

The results of the experiment are as follows:

1. Precision experiment of the method: two standard samples were selected, each sample was measured 11 times, and the relative standard deviation (RSD) was calculated. See Table 1 for statistical data.

The measurement result (%) of calcium in the reagent blank solution of table 1

It can be seen from the data in Table 1 that the relative standard deviation of the analysis method is less than 1%, and the reproducibility of the analysis results is very good.

2, the accuracy test (recovery experiment) of method: select the number of production to be two standard samples of YSB14610 and YSB14613, add the standard solution of a certain amount of calcium, operate by sample analysis step, carry out recovery test, measurement result is shown in Table 2.

Table 2 recovery test measurement results (%)

It can be seen from the data in Table 2 that the recovery rate is between 98.1% and 101.4%, which can fully meet the detection requirements.

Claims (1)

1. method of measuring calcium constituent in the silicon aluminum calcium barium alloy, its step:

1) 0.1～1.0 gram of materialsing places polytetrafluoroethylene beaker, and it is moistening to sample to add deionized water;

2) add 9.5～10.5 milliliters in nitric acid;

3) drip 1～2 milliliter in hydrofluorite;

4) heat until sample at electric hot plate and dissolve fully;

5) add 4.5～5.5 milliliters in perchloric acid;

6) under 170～190 ℃ of conditions, be heated to volume of sample and narrow down to 1～2 milliliter;

7) naturally cool to 25～35 ℃;

8) add 4.5～5.5 milliliters in perchloric acid, and under 170～190 ℃ of conditions, be heated to volume of sample and narrow down to 1～2 milliliter;

9) add 9.5～10.5 milliliters of hydrochloric acid, 45～55 milliliters of deionized waters;

10) under 100-120 ℃ condition, be heated to the salt dissolving, take off, adopt the natural cooling mode that sample is cooled to be lower than 40 ℃;

11) cooled sample is inserted in the volumetric flask of 100 milliliters of scales, be diluted to 100 milliliters scale and shake evenly mother liquor preparation end with deionized water;

12) get mother liquor and place triangle cup or beaker for 20～30 milliliters, and add no more than 50 milliliters, 1 part water of deionized water and 20 milliliters of 1 part of mixed triethanolamine liquid of triethanolamine, 10 milliliters of the glazier's salts of 10% (mass concentration), 5 milliliters in the magnesium sulphate of 5% (mass concentration), calcon-carboxylic acid 0.1～0.2 gram respectively, and be that the potassium hydroxide of 200 grams per liters is adjusted to redness with solution with volume mass concentration;

13) adding 10 ml volumes mass concentrations again is the potassium hydroxide of 200 grams per liters;

14) adopting EDTA titration to blueness is that terminal point finishes;

15) calculating of analysis result: the mass percent (%) that is calculated as follows calcium:

$\mathrm{WCa}=\frac{C*V*40.08}{m*1000}*100$

In the formula: C---the concentration mol/L of EDTA standard titration solution;

V---test solution consumes the volume of EDTA standard titration solution, ml;

M---divide the test portion amount of getting test solution, g;

40.08---the molal weight of calcium, g/mol.