GOST 11739.24-98

• gost-1173924-98.pdf (426.25 KiB)
  ГОСТ 11739.24-98

GOST 11739.24−98 Alloys, aluminum casting and wrought. Methods for determination of zinc

GOST 11739.24−98

Group B59

INTERSTATE STANDARD

ALLOYS ALUMINIUM CAST AND WROUGHT

Methods for determination of zinc

Aluminium casting and wrought alloys.
Methods for determination of zinc

ISS 77.120.10
AXTU 1709

Date of implementation 2000−01−01

Preface

1 DEVELOPED by JSC «Russian Institute of light alloys» (JSC VILS), the Interstate technical Committee MTC 297 «Materials and semi-finished products from light and special alloys"

INTRODUCED by Gosstandart of Russia

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol of 12 November 1998 No. 14−98)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization and Metrology, dated April 21, 1999 No. 132 inter-state standard GOST 11739.24−98 introduced directly as state standard of the Russian Federation from January 1, 2000

4 REPLACE GOST 11739.24−82

1 Scope

This standard establishes titrimetric (mass fraction in range from 0.1 to 12.0%) and atomic absorption (at a mass fraction of from 0.01 to 6.0%) methods for determination of zinc.

2 Normative references

The present standard features references to the following standards:

GOST 61−75 acetic Acid. Specifications

GOST 1277−75 Silver nitrate

GOST 2603−79 Acetone. Specifications

GOST 3117−78 Ammonium acetate. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3640−94 Zinc. Specifications

GOST 3760−79 Ammonia water. Specifications

GOST 4038−79 Nickel (II) chloride 6-water. Specifications

GOST 4139−75 Potassium rodanistye. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4328−77 Sodium hydroxide. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 10484−78 hydrofluoric Acid. Specifications

GOST 10652−73 Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B)

GOST 10727−91 unidirectional glass Threads. Specifications

GOST 10929−76 Hydrogen peroxide. Specifications

GOST 11069−74 Aluminium primary. Brand

GOST 18300−87 ethyl rectified technical. Specifications

GOST 20301−74 ion-exchange Resins. The anion exchange resin. Specifications

GOST 25086−87 non-ferrous metals and their alloys. General requirements for methods of analysis

3 General requirements

3.1 General requirements for methods of analysis GOST 25086 with the Supplement.

3.1.1 the result of the analysis be the arithmetic mean of results of two parallel measurements.

4 Titrimetric method for the determination of zinc

4.1 the essence of the method

The method is based on dissolving the samples in hydrochloric acid in the presence of hydrogen peroxide, the separation of zinc from interfering components by ion exchange on strong-base resin, the titration of zinc with a solution of Trilon B with ditizona or kylinalove orange as indicator.

4.2 Equipment, reagents and solutions

Glass ion-exchange column with a diameter of 25−30 mm, a height of 350−400 mm, expanded at the top and a spigot at the bottom. As speakers are allowed to use a burette with a capacity of 50 cm, with a diameter of 12−15 mm, height 450 to 500 mm.

the pH-meter.

Hydrochloric acid according to GOST 3118 density of 1.19 g/cm, mortar 1:1, 1:20 and the molar concentration of 2; 1 and 0.005 mol/DM.

Nitric acid according to GOST 4461 density of 1,35−1,40 g/cm.

Acetic acid according to GOST 61 density of 1.05 g/cmand a solution with molar concentration of 1 mol/l: 58 cmof acetic acid are placed in a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

Ammonia water according to GOST 3760, solution 1:5.

Ammonium acetate according to GOST 3117, a solution of 500 g/DM.

Buffer solution with a pH of 5.8: 500 g of ammonium acetate are placed in a measuring flask with volume capacity of 1000 cm, is dissolved in 800 cmof water, made up to the mark with water and mix. Using pH-meter set pH at 5.8, if necessary, by adding acetic acid.

Sodium hydroxide according to GOST 4328, solutions of 50 and 100 g/DM.

Hydrogen peroxide according to GOST 10929.

Acetone according to GOST 2603.

The technical rectified ethyl alcohol according to GOST 18300.

Potassium rodanistye according to GOST 4139, a solution of 10 g/DM.

Silver nitrate according to GOST 1277, a solution of 10 g/DM.

Universal indicator paper.

The indicator Congo red: 0.1 g of the reagent dissolved in 100 cmof water at weak heating, the solution was cooled and stirred.

Indicator paper Congo: medium-density filters («white ribbon») is impregnated with a solution of Congo red, dried in a drying Cabinet at a temperature of 100−105 °C, sliced and stored in boxe. The paper is suitable for use within one month.

Wool glass according to GOST 10727.

Selenology orange, a solution of 10 g/DMfreshly prepared.

1,5-diphenylthiourea (ditson) [1], a solution of 0.25 g/DMfreshly made: 0.05 g dithizone dissolved in 200 cmof ethanol.

Ion-exchange resin is a strongly basic polystyrene anion exchange resin chetyrehmagnitnoy the type of brands АН31, АВ17, EDE-10P, or other anion of this group according to GOST 20301 with a particle size of from 0,150 to 0,300 mm. allowed the use of imported resin Dowex 12, De Acidic FFSR A62.

Zinc GOST 3640 brand CV00.

Standard solution of zinc, 1 g of zinc is placed in a conical flask with a capacity of 250 cm, 50 cm pour thewater, carefully, in small portions 50 cmof a hydrochloric acid solution of 1:1 and dissolved under moderate heating. The solution was cooled to room temperature, transferred to a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.001 g of zinc.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B) according to GOST 10652, solution with molar concentration 0,01 mol/DM: 7.5 g Trilon B, is placed in a beaker with a capacity of 250 cm, and dissolved in 100 cmof water. The solution is optionally filtered, transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix. The solution was stored in a plastic container.

The mass concentration of the solution Trilon B in the zinc install one

of the following methods.

4.2.1 three conical flasks with a capacity of 250 cmis placed 10 cmstandard solution, equivalent to 10 mg of zinc, pour 100 cmof water and ammonia until the blue color of the transfer paper, Congo red, pH 5−5,5. The solution is poured 20 cmof acetic acid, 10 cmof a solution of ammonium acetate (pH 5−5,5 test universal indicator paper, if necessary adding a solution of acetic acid), 50 cmof acetone, 2 cmdithizone solution and titrated with a solution of Trilon B to the transition of the red color of the solution yellow. The color of the solution should not change from the addition of two excess drops of solution Trilon B

.

4.2.2 three conical flasks with a capacity of 250 cmis placed 10 cmstandard solution, equivalent to 10 mg of zinc, pour 100 cmwater, 10 cmbuffer solution, three drops of the solution kylinalove orange and titrated with a solution of Trilon B to switch the crimson color of the solution in light yellow.

The mass concentration of the solution Trilon B for zinc , g/cm, determined with every batch of samples analysed and calculated by the formula

, (1)

where mass concentration of a standard solution of zinc, g/cm;

 — the volume of standard zinc solution used for titration, cm;

 — volume of solution Trilon B, spent on titration, sm.

4.3 Preparation for analysis

4.3.1 50 g of resin is placed in a beaker with capacity of 500 cmand washed by decantation with hydrochloric acid 1:20 to a negative reaction for iron with thiocyanate-ion (no pink color). Then pour 400 cmof a hydrochloric acid solution 0.005 mol/DMand incubated at room temperature for 24 h.

On the bottom of the column on the crane put a small layer of glass wool, then fill the column with a slurry of resin with a height of 200−250 mm (at a diameter of 25−30 mm column) or 350 to 400 mm (when the diameter of the column 12−15 mm), avoiding formation of air bubbles or air channels.

In the preparation of resin columns, and when performing the analysis, the resin should be coated with a layer of liquid of a height of not less than 10−20 mm.

The resin column was washed successively with sodium hydroxide solution 50 g/land 100 g/cmwith a volumetric flow rate of 2−3 cm/min until a negative reaction for chloride ion with silver nitrate (absence of white turbidity), then with water until the reaction is slightly alkaline washing liquid (pH 8 test universal indicator paper). After that, the resin was treated three times with portions of 100 cmof solution hydrochloric acid 2 mol/DMwith a volumetric flow rate of 2−3 cm/m

in.

4.3.2 Upon completion of the chromatographic separation resin is regenerated by flushing with water until slightly acidic wash liquid (pH 5−6 by universal indicator paper), then skip 100 cmof solution hydrochloric acid 2 mol/DMwith a volumetric flow rate of 2−3 cm/min and fill the column with a solution of the same acid.

4.4 analysis

4.4.1 Sample the sample weight in accordance with table 1 was placed in a conical flask with a capacity of 250 cm, 5−10 cm pouredwater carefully, in small portions, 50 cmhydrochloric acid solution 1:1 and heated to dissolution.


Table 1

Then add dropwise hydrogen peroxide (about 1 cm) until complete dissolution of copper, is evaporated to wet salts, pour 100 cmof solution hydrochloric acid 2 mol/land heated to dissolve the salts. The solution is filtered through a dense filter («blue ribbon»), previously washed with hot hydrochloric acid 1:1 and hot water, the filter residue was washed with 30−50 cmof hot hydrochloric acid 2 mol/DM.

4.4.2 for the mass concentration of zinc of 0.1 to 1.5%

The filtrate and the washings collected in a conical flask with a capacity of 250 cm, was cooled to room temperature, poured hydrochloric acid of 2 mol/DMto a volume of 150 cmand add 0.5 cmof nitric acid.

4.4.3 When the mass fraction of zinc St of 1.5 to 12.0%

The filtrate and the washings collected in a volumetric flask with a capacity of 200 cm, cooled to room temperature, add hydrochloric acid 2 mol/DMup to the mark and mix.

4.4.4 the Solution obtained in 4.4.2, or aliquot part of the solution obtained in 4.4.3 in accordance with table 1, passed through an ion exchange column with a volumetric flow rate of 2−3 cm/min. the Flask and the column was washed four times with hydrochloric acid 2 mol/DMportions 25 cmand then 100 cmof hydrochloric acid of 1 mol/DMwith the same volumetric rate. If the lead alloy is present, the volume of the solution hydrochloric acid 1 mol/DMincreased to 200 cm.

Zinc eluted in 250 cmof solution hydrochloric acid 0.005 mol/DMwith a volumetric flow rate of 2−3 cm/min, collecting the eluate in a conical flask with a capacity of 500 cm. Titration of the eluate with a solution of Trilon B is carried out by one of the following.

mandatory.

4.4.4.1 Solution obtained in 4.4.4, evaporated to a volume of 100 cm, pour the ammonia until the blue color of the transfer paper, Congo red, pH 5−5,5. The solution is poured 20 cmof acetic acid, 10 cmof a solution of ammonium acetate (pH 5−5.5 test universal indicator paper, if necessary adding a solution of acetic acid), 50 cmof acetone, 2 cmdithizone solution and titrated with a solution of Trilon B to the transition of the red color of the solution yellow. The color of the solution should not change from the addition of two excess drops of solution Trilon B.

4.4.4.2 In the solution obtained in 4.4.4, add three drops of the solution kylinalove orange, solution of ammonia until you move the yellow color of the solution in raspberry, 15 cmbuffer solution and titrated with a solution of Trilon B to switch the crimson color of the solution in light yellow.

4.4.5 Solution of the reference experiment is prepared according to 4.4.1−4.4.4 with all the reagents used in the analysis.

4.5 Processing of results

4.5.1 Mass fraction of zinc , %, is calculated by the formula

, (2)

where  — volume of solution Trilon B, used for titration of the sample solution, cm;

 — volume of solution Trilon B, used for titration of the solution in the reference experiment, cm;

 — established mass concentration of the solution Trilon B for zinc, g/cm;

 — the weight of the portion of the sample or the weight of the portion of the sample in aliquote part of the solution, g

.

4.5.2 discrepancies in the results must not exceed the values given in table 2.


Table 2

Percentage

5 Atomic absorption method for determining zinc

5.1 the essence of the method

The method is based on dissolving the samples in hydrochloric acid in the presence of hydrogen peroxide and measurement of atomic absorption of zinc in the flame of acetylene-air at a wavelength of 213,9 nm.

5.2 the Instrument, reagents and solutions

Spectrophotometer of atomic absorption with a radiation source for zinc.

Hydrochloric acid according to GOST 3118 density of 1.19 g/cm, mortar 1:1 and 1:99.

Zinc GOST 3640 brand CV00.

Standard solutions of zinc.

Solution a: 1 g of zinc is placed in a conical flask with a capacity of 250 cm, carefully, in small portions pour 50 cmof a hydrochloric acid solution of 1:1 and dissolved under moderate heating. Cooled to room temperature, the solution is transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.001 g of zinc.

Solution B: 5 cmmortar And transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmof the solution contains of 0.00005 g of zinc. The solution is prepared immediately before use.

Nickel (II) chloride according to GOST 4038, a solution of 2 g/DM.

Sulfuric acid according to GOST 4204 density 1.84 g/cm.

Nitric acid according to GOST 4461 density of 1,35−1,40 g/cm.

Acetylene according to GOST 5457.

Hydrofluoric acid according to GOST 10484.

Hydrogen peroxide according to GOST 10929.

Aluminium GOST 11069 brand А999.

Solutions of aluminium

Solution a 20 g/l: 10 g of aluminum is placed in a conical flask with a capacity of 500 cm, poured in small portions with 300 cmof a hydrochloric acid solution of 1:1 and dissolved at a moderate heat, adding 1 cmof a solution of Nickel chloride (II). Add 3−5 drops of hydrogen peroxide and boil the solution for 3−5 min. the Solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

Solution B 2 g/DM: 50 cmsolution And placed in a volumetric flask with a capacity of 500 cm, 270 cm pour thehydrochloric acid solution of 1:1, made up to the mark with water and

mix.

5.3 analysis

5.3.1 Sample the sample weight in accordance with table 3 was placed in a conical flask with a capacity of 250 cm, flow 20 cmof water and carefully, in small portions, 30 cmof a hydrochloric acid solution 1:1. The beaker cover watch glass, heat to dissolve the sample, add 3−5 drops of hydrogen peroxide and boil the solution for 3−5 min.


Table 3

5.3.2 clear solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

5.3.3 If there is a precipitate, indicating the presence of silicon, the solution was filtered in a volumetric flask with a capacity of 500 cmthrough the filter medium density («white ribbon»), washing the precipitate on the filter 2−3 times with hot hydrochloric acid 1:99 in portions of 10 cm(core solution).

The filter with precipitate was placed in a platinum crucible, dried, incinerated, preventing ignition, and calcined at 500−600 °C for 2−3 min. After cooling in the crucible add five drops of sulfuric acid, 5 cmhydrofluoric acid and drop by drop nitric acid (approximately 1 cm) to obtain a transparent solution. The solution was evaporated to dryness, cooled, poured to the dry residue in the crucible 10 cmof hydrochloric acid 1:1 and dissolved under moderate heating. After cooling, the solution is attached to the main solution (filtered if necessary), top up with water to the mark and mix.

5.3.4 depending on the mass fraction of zinc aliquot part of the solution (see table 3) is placed in the appropriate volumetric flask, pour the appropriate amount of hydrochloric acid is 1:1, made up to the mark with water and mix.

5.3.5 Solution the reference experiment is prepared in accordance with 5.3.1 to 5.3.4 using is sample the sample the sample of aluminium.

5.3.6 Construction of calibration graphs

5.3.6.1 When the mass fraction of zinc from 0.01 to 0.1%

Eight volumetric flasks with a capacity of 100 cmpour 10 cmof a solution of aluminum And in seven of them measure 0,2; 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution B, which corresponds to 0,00001, 0,000025; 0,00005; 0,0001; 0,00015; 0,0002; 0,00025 g zinc.

5.3.6.2 When the mass fraction of zinc from 0.1 to 0.3%

In seven volumetric flasks with a capacity of 100 cmpour 5 cmof a solution of aluminium And, in six of them measure 1,0; 2,0; 3,0; 4,0; 5,0; 6,0 cmstandard solution B, which corresponds to 0,00005; 0,0001; 0,00015; 0,0002; 0,00025; 0,0003 g zinc.

5.3.6.3 When the mass fraction of zinc from 0.3 to 3.0%

Eight volumetric flasks with a capacity of 100 cmpour 5 cmof a solution of aluminium Used in seven of them measure 0,5; 1,0; 2,0; 3,0; 4,0; 5,0; 6,0 cmstandard solution B, which corresponds to 0,000025; 0,00005; 0,0001; 0,00015; 0,0002; 0,00025; 0,0003 g zinc.

5.3.6.4 When the mass fraction of zinc from 3.0 to 6.0%

In six volumetric flasks with a capacity of 100 cmpour 2.5 cmof a solution of aluminium B, 2 cmof hydrochloric acid 1:1 in five of them measure 2,0; 3,0; 4,0; 5,0; 6,0 cmstandard solution B, which corresponds to 0,0001; 0,00015; 0,0002; 0,00025; 0.0003 grams of zinc.

5.3.6.5 Solutions in 5.3.6.1 to 5.3.6.4 topped up to the mark with water and mix.

5.3.7 Solutions of the samples in the reference experiment and the solutions for constructing the calibration curve is sprayed into the oxidizing flame of acetylene-air and measure the atomic absorption with zinc at a wavelength of 213,9 nm.

According to the obtained values of atomic absorption and corresponding mass concentrations of zinc build a calibration curve in the coordinates «Value of atomic absorption — mass concentration of zinc, g/cm». The solution, in which zinc has not been introduced, serves as a solution control experience in construction of calibration curve.

Mass concentration of zinc in the sample solution and the solution of control and experience determined by the calibration schedule.

5.4 processing of the results

5.4.1 Mass fraction of zinc , %, is calculated by the formula

, (3)

where is the mass concentration of zinc in the sample solution found by the calibration schedule, g/cm;

 — mass concentration of zinc in solution in the reference experiment, was found in the calibration schedule, g/cm;

 — the volume of the sample solution, cm;

 — the weight of the portion of the sample or the weight of the portion of the sample in aliquote part of the solution, g

.

5.4.2 the Divergence of results should not exceed the values given in table 4.


Table 4

Percentage