GOST 23862.25-79

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  ГОСТ 23862.25-79

GOST 23862.25−79 Rare-earth metals and their oxides. Methods for determination of cobalt and Nickel (with Change No. 1)

GOST 23862.25−79

Group B59

INTERSTATE STANDARD

RARE EARTH METALS AND THEIR OXIDES

Methods for determination of cobalt and Nickel

Rare-earth metals and their oxides. Methods of determination of cobalt and nickel

ISS 77.120.99
AXTU 1709

Date of introduction 1981−01−01

The decision of the State Committee USSR on standards on October 19, 1979 N 3989 date of introduction is established 01.01.81

Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)

EDITION with Change No. 1, approved in April 1985 (IUS 7−85).


This standard specifies the extraction-photometric method for the determination of cobalt (at a mass fraction of 2·10% 1·10%) in rare earth metals and their oxides and photometric method for the determination of Nickel and cobalt (at a mass fraction of 5·10% to 5·10%) in rare earth metals and their oxides (except cerium dioxide and cerium).

(Changed edition, Rev. N 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 23862.0−79.

EXTRACTION-PHOTOMETRIC METHOD FOR THE DETERMINATION OF COBALT IN RARE-EARTH METALS AND THEIR OXIDES

The method is based on the extraction concentration of an impurity of cobalt with a mixture of trioctylamine, dioxane, and carbon tetrachloride and subsequent photometric determination of cobalt by the reaction with nitroso-R-salt.

2. APPARATUS, REAGENTS AND SOLUTIONS

Tile electric.

The chemical glasses with a capacity of 50 and 100 cm.

Separating funnel with a capacity of 50 cm.

Watch-glasses.

Cylinders for colorimetrically of colorless glass with ground stoppers, diameter 8 mm, height 200 mm.

Nitric acid of high purity according to GOST 11125−84, concentrated, dilute 1:1 and 0.01 mol/DMsolution.

Hydrochloric acid of high purity according to GOST 14261−77; 1 and 8 mol/DMsolutions.

Hydrogen peroxide according to GOST 10929−76, OS.h.

The water is deionized.

Ammonium radamisty, h.d. a.

Ascorbic acid.

Trioctylamine, CH.

Sulfuric acid GOST 4204−77, H. h, of 0.0005 mol/DMsolution.

Cobalt sulfate according to GOST 4462−78.

Dioxane according to GOST 10455−80, h. d. a.

Carbon tetrachloride according to GOST 20288−74.

Trioctylamine solution in carbon tetrachloride of 1:5, kept for at least 4 days.

Extractant: mix two parts of 4 days aged solution trioctylamine in carbon tetrachloride and one part dioxane; stand before use 6 hours.

Sodium acetate according to GOST 199−78, H. h, solution with a concentration of 100 g/DM.

Nitroso-R-salt NTD, h, a solution with a concentration of 2 g/DM.

Standard solution of cobalt (spare) containing 0.1 mg/cmcobalt: 0,0475 g of cobalt sulfate dissolved in of 0.0005 mol/DMsulfuric acid and bring the volume of solution in a volumetric flask with a capacity of 100 cmmark of 0.0005 mol/DMsulfuric acid.

A solution of cobalt (working) containing 1 µg/cmfor cobalt, prepared on the day of use by dilution of a standard solution of cobalt in 0.01 mol/DMnitric acid 100 times.

Sec. 2. (Changed edition, Rev. N 1).

3. ANALYSIS

3.1. A portion of the sample (except cerium dioxide) with a mass of 1−5 g, depending on the content of cobalt was placed in a beaker with a capacity of 100 cm, moistened with a few drops of water, poured 30 cm8 mol/DMof hydrochloric acid and dissolved by heating. The solution was transferred to a separatory funnel with a capacity of 50 cmand twice extracted cobalt portions of the extractant to 3 cm, shake vigorously for 2 min.

After separation the organic phase was transferred to a clean, dry separating funnel with a capacity of 50 cm.

The combined organic phase is vigorously shaken with 10 cmof a solution of sodium acetate for 1 min. After separation the organic phase is collected and regeniriruyut according to claim 3.5, and in the aqueous phase determine the cobalt according to claim 3.3

.

3.2. A sample of cerium dioxide 1−5 g were placed in a glass with a capacity of 100 cm, moistened with a few drops of water, pour 5−10 cmof concentrated nitric acid, 10−20 cmof hydrogen peroxide, stirred, closed glass watch glass and dissolved under heating. The solution is evaporated to wet salts and add a few drops of hydrogen peroxide. The residue is dissolved in ~30 cmof water (pH ~1−1,5 control is carried out according to universal indicator paper), add 0.5 g of ammonium Rodenstock, was stirred until complete dissolution of the precipitate. The solution was transferred to a separatory funnel with a capacity of ~50 cm, pour 4 cmof the extractant and vigorously shaken for 2 min. After separation the organic phase was transferred to a clean, dry separating funnel with a capacity of 50 cm, flow 20 cmof water being injected at the tip of a spatula of 20−30 mg of ascorbic acid and vigorously stirred for a few seconds. It should disappear the red coloration of the organic phase.

The Stripping of cobalt is carried out by shaking the organic layer with a mixture of 10 cmof a solution of sodium acetate and 2 cmof mortar, nitroso-R-salt for 1

min.

3.3. Reextract washed 1 cmof carbon tetrachloride and transfer to a glass with a capacity of 50 cm, add 3 cm1 mol/DMhydrochloric acid (to pH 5.5), 2 cmof mortar, nitroso-R-salt, and boil the solution for 1 min. Then add 3 cmof hydrogen peroxide, 2 cm8 mol/DMof hydrochloric acid and is evaporated by boiling to a volume of ~5 cm.

The solution is transferred to a cylinder for colorimetrically with a glass stopper and intensity of the color is compared on white background with the color intensity of the solutions scale comparison, watching the painting from top to bottom. Simultaneously with the analysis of samples carried out control experience in the chemicals through all stages of the analysis and introduce the amendment.

The amount of cobalt in a control experiment should not exceed 0.05 m

kg.

3.4. Preparation of the scale comparison

In glasses with a capacity of 50 cmis administered at 3 cmof a solution of sodium acetate, 1 cm1 mol/DMof hydrochloric acid, 1 cmof the solution, nitroso-R-salt, and 5 cmof water, poured 0; 0,05; 0,10; 0,20; 0,30; 0,40; 0,50 and 1.0 cmof a solution of cobalt (containing 1 µg/cmof cobalt) was mixed and boiled for 1 min. Then add 3 cmof hydrogen peroxide, 2 cmof hydrochloric acid diluted 1:1, and is evaporated by boiling to a volume of ~5 cm.

The solution is transferred to a cylinder for colorimetrically with a glass of samples

coy.

3.5. Regeneration of the extractant

30−50 cmof the used extractant was placed in a separating funnel with a capacity of 200 cmand washed twice with 100 cmof 0.1 mol/DMhydrochloric acid for 2 min, the aqueous phase is discarded. The organic layer was washed with 100 cmof water for 2 min. the Regenerated organic phase is mixed with dioxane in a ratio of 2:1 and allowed to stand before use for 6 hours.

4. PROCESSING OF THE RESULTS

4.1. Mass fraction of cobalt () in percent is calculated by the formula

,

where is the mass of cobalt in the specimen, found on a scale of comparison, the mcg;

 — the mass of cobalt in a control experiment, µg;

 — the weight of the portion of the sample,

The result of the analysis taking the arithmetic mean of two parallel definitions, drawn from separate batches.

4.2. Discrepancies in the results of two parallel determinations or the results of the two tests should not exceed values of allowable differences specified in table.1.

Table 1

5. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF NICKEL AND COBALT IN RARE-EARTH METALS AND THEIR OXIDES (EXCEPT CERIUM DIOXIDE AND CERIUM)

The method is based on the preconcetration of impurities of Nickel and cobalt sorption on their diethyldithiocarbamate porous fluoropolymer followed by desorption with acetone, the mineralization of organic solution and the photometric determination of Nickel in a compound with -furildioxime and cobalt in the form of complex compounds with nitroso-R-salt.

5.1. Apparatus, reagents and solutions

Spectrophotometer «Pye Unicam» SP 8−100 or similar device.

Analytical scale.

Bunsen flask with a capacity of 1000 cm.

Columns made of PTFE-4 height 15 mm, diameter 20 mm.

The cylinders with a lateral branch with a capacity of 30 cm.

The chemical glasses with a capacity of 50 and 100 cm.

The quartz Cup with a capacity of 30 cm.

Volumetric flasks with a capacity of 25, 100 and 250 cm.

Glass pipettes with volume capacity of 1, 5 and 10 cm.

Distilled water GOST 6709−72.

Hydrochloric acid of high purity according to GOST 14261−77, concentrated, diluted 1:1, 1:10 and 1 mol/DMsolutions.

Sulfuric acid GOST 4204−77, h. e. a., concentrated, and 0.0005 to 0.005 mol/DMsolutions.

Ammonia water according to GOST 3760−79, h. e. a., diluted 1:1 and 1:10.

-furildioxime, a solution with a concentration of 5 g/DM(prepared by dissolving -furildioxime in acetone, then dilute the resulting solution with distilled water in the ratio 1:9).

Nickel sulfate according to GOST 4465−74, h.d. a.

Nitroso-R-salt NTD, h, a solution with a concentration of 2 g/DM.

Sodium acetate according to GOST 199−78, H. h, solution with a concentration of 100 g/DM.

Hydrogen peroxide according to GOST 10929−76, OS.h.

Cobalt sulfate according to GOST 4462−78, h.d. a.

Sodium N, N'-diethyldithiocarbamate according to GOST 8864−71, solutions with concentrations of 20 and 1 g/DM.

Acetone according to GOST 2603−79.

A standard solution of Nickel (spare) containing 100 µg/cmof Nickel: 0,120 g of Nickel sulfate dissolved in 0.005 mol/DMsulfuric acid. The solution was transferred to a volumetric flask with a capacity of 250 cmand label is adjusted to 0.005 mol/DMsulfuric acid.

A solution of Nickel containing 1 µg/cmof Nickel, prepared on the day of use by dilution of a standard solution 100 times 0.005 mol/lsulfuric acid solution.

Standard solution of cobalt (spare) containing 100 µg/cmcobalt: 0,0475 g of cobalt sulfate dissolved in of 0.0005 mol/DMsulfuric acid. The solution was transferred to a volumetric flask with a capacity of 100 cmand topped to the mark of 0.0005 mol/DMsulfuric acid.

A solution of cobalt, containing 1 µg/cmfor cobalt, prepared on the day of use by dilution of a standard solution is 100 times of 0.0005 mol/DMRast

thief of sulfuric acid.

5.2. Construction of calibration graphs

5.2.1. Construction of calibration curve for the determination of Nickel

In a number of chemical glasses with a capacity of 100 cmis placed 2 g of an oxide of re (mass fraction of Nickel which does not exceed 5·10%), 0; 0,1; 0,2; 0,3; 0,5; 1,0; 1,5 cmof a solution of Nickel containing 1 µg/cmNickel 7 cmof hydrochloric acid diluted 1:1, and heat the beaker contents to completely dissolve the oxides of the REE. The solution is evaporated to moist salts, diluted with distilled water to 50 cmand set pH 2 with aqueous ammonia, diluted 1:10, or a solution hydrochloric acid, diluted 1:10, pH is controlled by universal indicator paper.

The resulting solutions are heated to 90 °C, poured to him 2.5 cmof a solution of N, N'-diethyldithiocarbamate sodium concentration of 20 g/DM(pH is 5.5), cooled to room temperature and passed through a PTFE column installed in flasks Bunsen.

Then each column was washed with 30 cmof a solution of N, N'-diethyldithiocarbamate sodium with a concentration of 1 g/DMportions of 5 cm, set the speaker in the cylinder with side outlet and desorber impurities 15 cmof acetone in the vacuum created a water vacuum pump. Organic solutions are transferred to a quartz Cup, evaporated to dryness on the water bath and mineralized remains of 3 cmof concentrated sulfuric acid and 3 cmof hydrogen peroxide (up to the complete decomposition of organic substances). Dry residue is treated with 2 cmof concentrated hydrochloric acid, dryness, and transferred with distilled water in flasks with a capacity of 25 cm(the volume of solutions should not exceed 15 cm). Ammonia solution, diluted 1:10 or 1:1, set pH to 7.5−9 (control by universal indicator paper), pour 1 cmof solution — furildioxime, top up with distilled water to the mark and leave the contents of the flasks for 30 min, the test solution placed in the cuvette with optical path length of 100 mm and the optical density of test solution is measured on the spectrophotometer at a wavelength of 486 nm in a cuvette with optical path length of 100 mm. as a solution comparison, use water. Simultaneously conduct control experience in the chemicals through all stages of the analysis and introduce amendments. Calibration curve constructed in the coordinates , (where is the mass of Nickel in mcg, the corresponding optical density). Individual points of the graph to check not less than one

times in a month.

5.2.2. Construction of calibration curve for the determination of cobalt

In the chemical glasses with a capacity of 100 cmis placed 2 g of an oxide of re (mass fraction of cobalt which does not exceed 5·10%), 0; 0,1; 0,2; 0,3; 0,5; 1,0; 1,5 cmof a solution of cobalt, containing 1 µg/cmcobalt and then do as under construction of calibration curve for the determination of Nickel according to claim 5.2.1 (starting with «7 cmof hydrochloric acid diluted 1:1, and the beaker contents heated until complete dissolution of oxides REE» and before the words «Dry residue is treated with 2 cmof concentrated hydrochloric acid, without drying»). Next, the contents of the quartz Cup tolerate distilled water in beakers with a capacity of 50 cm, pour 3 cmof a solution of sodium acetate, 1 cm1 mol/DMof hydrochloric acid, 2cmof a solution of nitroso-R-salt, mix and boil for 1 min. Then add 3 cmof hydrogen peroxide, 2 cmof hydrochloric acid diluted 1:1 and boiled until the destruction of the green color of solutions. The resulting solutions are transferred to volumetric flasks with a capacity of 25 cmand was adjusted to the mark with water. The optical density of test solution is measured on the spectrophotometer at a wavelength of 415 nm in a cuvette with optical path length of 100 mm. as a solution comparison, use water. Simultaneously conduct control experience in the chemicals through all stages of the analysis and introduce amendments. Calibration curve constructed in the coordinates , (where is the mass in micrograms of cobalt, the corresponding optical density). Individual points of the graph to check not less than one RA

for a month.

5.3. Analysis

5.3.1. The concentration of impurities

A portion of the sample weighing 2−4 g REE oxide or the corresponding amount of metal is placed in a beaker with a capacity of 100 cmand dissolved in 7−15 cmof hydrochloric acid diluted 1:1. Then do as under construction of calibration curve for the determination of Nickel according to claim 5.2.1 (beginning with the words: «the Solutions are evaporated to wet salts» and before the words «Dry residue is treated with 2 cmof concentrated hydrochloric acid, without drying»). Next, the contents of the quartz Cup was transferred into a measuring flask with a capacity of 25 cmand adjusted to the mark with distilled water. 10 cmsolution is transferred into chemical glass with a capacity of 50 cmand determine the content of cobalt in the solution according to claim 5.3.3. The solution remaining in the flask used for the determination of Nickel according to claim 5.3.2.

5.3.2. The determination of Nickel

To the solution, in a volumetric flask with a capacity of 25 cm, pour the ammonia solution, diluted 1:10 or 1:1, until reaching pH 7.5−9 (control by universal indicator paper). Next, pour 1 cmof solution -furildioxime, the volume was adjusted solution to the mark with distilled water and leave the contents of the flask for 30 min. Optical density of test solution is measured on the spectrophotometer at a wavelength of 486 nm in a cuvette with optical path length of 100 mm. as a solution comparison, use water. Simultaneously conduct control experience in the chemicals through all stages of the analysis and introduce the amendment. The mass of Nickel in the solution found by the calibration schedule.

5.3.3. Definition of cobalt

In chemical beaker with a capacity of 50 cmcontaining an aliquot of the analyzed solution pour 3 cmof a solution of sodium acetate, 1 cm1 mol/DMof hydrochloric acid, 2cmof a solution of nitroso-R-salt, mix and boil the contents of the beaker for 1 min. Then poured 3 cmof hydrogen peroxide, 2 cmof hydrochloric acid diluted 1:1, boiled until the destruction of the greenish color of the solution. The resulting solution was transferred to a volumetric flask with a capacity of 25 cmand the volume was adjusted solution to the mark with distilled water. The optical density of test solution is measured on the spectrophotometer at a wavelength of 415 nm in a cuvette with optical path length of 100 mm. as a solution comparison, use water.

Simultaneously conduct control experience in the chemicals through all stages of the analysis and introduce the amendment. The mass of cobalt in the solution found by calibration curve

.

5.3.4. Regeneration of the column

After desorption of the impurity elements with acetone column of Teflon-4 are set in the Bunsen flask and washed with 30 cmof hydrochloric acid diluted 1:1, portion of 5 cmthen 50 cmof distilled water. After that, the column is ready for use.

5.4. Processing of the results

5.4.1. Mass fraction of the element in percent () is calculated by the formula

,

where is the mass of the element in aliquote part of the solution, found on the schedule, mcg;

 — the weight of the portion of the sample, g;

 — volume aliquote part of the solution, cm;

25 — capacity volumetric flasks, cm.

The result of the analysis taking the arithmetic mean of two parallel definitions, drawn from separate batches.

5.4.2. Discrepancies in the results of two parallel determinations or the results of the two tests should not exceed the values of permissible differences given in table.2.

Table 2