GOST 23862.20-79
GOST 23862.20−79 Rare-earth metals and their oxides. Method for the determination of vanadium (Change No. 1)
GOST 23862.20−79
Group B59
INTERSTATE STANDARD
RARE EARTH METALS AND THEIR OXIDES
Method for the determination of vanadium
Rare-earth metals and their oxides. Method of determination of vanadium
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 sets the photometric method for the determination of vanadium (1·10% 1·10%) in rare earth metals and their oxides (except cerium and its dioxide).
The method is based on catalytic action of Vanadate ions on the oxidation of h-acid by potassium bromate. The optical density of test solution is measured on a photoelectrocolorimeter. The content of vanadium in the sample find for the calibration schedule.
(Changed edition, Rev. N 1).
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 23862.0−79.
2. APPARATUS, REAGENTS AND SOLUTIONS
Photoelectrocolorimeter FEK-56 or similar device.
Bath water.
Pipettes with a capacity of 2 cm.
Apparatus for distillation with a quartz or platinum tube.
Glasses with a capacity of 250, 1000 cm.
The quartz cylinders with ground stoppers with a capacity of 15 cm, calibrated to 5 and 10 cm; before operation, the cylinders are thoroughly washed distilled with sulphuric acid diluted 1:1, rinse bidistillate was placed in a beaker with a capacity of 1000 cmand steamed in boiling water for 30−40 min.
Paper universal indicator.
The water is deionized.
Sulfuric acid GOST 4204−77, H. C., optionally distilled in a quartz apparatus (selected middle fraction), diluted 1:1, 1:3.
The aqueous ammonia of high purity according to GOST 24147−80 diluted 1:4.
Nitric acid of high purity according to GOST 11125−84 additionally distilled in the apparatus with a quartz or platinum bulb (take the middle fraction) and diluted 1:3, prepared on the day of use.
Oxalic acid according to GOST 22180−76, H. h, solution with concentration of 1 g/DM.
Potassium permanganate according to GOST 20490−75, H. h, solution with a concentration of 20 g/DM.
Acetic acid according to GOST 18270−72, H. h, optionally double-distilled in quartz apparatus (selected middle fraction), diluted 1:20.
Potassium branovitsky according to GOST 4457−74, H. h, optionally recrystallized twice from aqueous solutions; a solution with a concentration of 10 g/DM. For recrystallization polnovatogo potassium weighed weighing 200−240 g were placed in a glass with a capacity of 1000 cm, 800 cm, addhot water, the solution was filtered through a filter previously washed several times with hot water, the filtrate is evaporated until the appearance of the surface of the crystalline film is cooled to 15 °C. the Precipitated crystals are filtered off, dissolved in 700 cmof hot water, filtered, evaporated to the appearance of the surface of the crystalline film is cooled to 15 °C. the Precipitated crystals are filtered off and dried at 80−85 °C. Recrystallized branovitsky potassium store in a dark jar with a glass lid.
1-amino-8-naphthol-3,6-disulfonate monogalia salt (H-acid), h, optionally recrystallized from aqueous solutions of 0.02 mol/DMsolution: weighed Ash-acid weight 0,073 g is placed in a quartz cylinder, was adjusted to the mark with water of 10 cm, immersed in water with a temperature of 70−80 °C for 30−40 s, cooled to room temperature. Cylinder wrapped in dark paper. For recrystallization of Al-acid cook it hot saturated solution, filter through a filter washed several times with hot water, the filtrate is cooled to a temperature of 10−12 °C. the Precipitated crystals are filtered and dried between sheets of filter paper.
Recrystallized Ash-acid is prepared on the day of use and stored in a dark jar with a glass lid.
Vanadium metal.
A standard solution of vanadium (spare) containing 1 mg/cmvanadium: vanadium metal charge mass of 0.1 g was placed in a beaker with a capacity of 250 cm, add 10 cmsulphuric acid diluted 1:3, 1 cmof concentrated nitric acid. After complete dissolution of the samples the contents of the beaker is evaporated to fumes of sulphuric anhydride, cooled to room temperature, washed walls of glass with water and again evaporated to fumes of sulphuric anhydride, cooled to room temperature, add 10−15 cmof water and poured dropwise a solution of potassium permanganate until a stable pink color. The excess potassium permanganate is destroyed, by adding dropwise a solution of oxalic acid with stirring until the disappearance of the pink color. The beaker content was transferred into a measuring flask with a capacity of 100 cm, adjusted to the mark with water and mix.
A solution of vanadium containing 0.1 µg/cmvanadium, prepare serial standard dilution water (emergency) solution vanadium 10,000 times. The solution is prepared the day of use.
Sec. 2. (Changed edition, Rev. N 1).
3. ANALYSIS
3.1. A portion of the sample oxide REE weight of 0.5 g or the corresponding amount of metal is placed in a quartz cylinder with a capacity of 15 cm, pour 1.5−2 cmof water, 3 cmof a solution of nitric acid, diluted 1:3, mix. The cylinder is placed in a glass of water, heated to 70−80 °C and kept therein until complete dissolution of the sample, cooled to room temperature, set pH 2−2,5 ammonia solution (checked by universal indicator paper); adjusted with water to a volume of 10 cmand mixed.
From the resulting solution are taken 2 cmin a quartz cylinder with a capacity of 15 cm, set with ammonia solution pH of 2−2. 5 on the universal indicator paper, add 0.4 cmpolnovatogo potassium solution, adjusted with acetic acid to the mark of 5 cm, mix, add 0.2 cmsolution, PH-acid mix. The cylinders with the solutions immersed in a water bath with a temperature of 50−52 °C and kept at this temperature for 15 min, quickly cooled to room temperature. The optical density of test solution is measured on a photoelectrocolorimeter (490 nm) in a cuvette with a thickness of the light absorbing layer 10 mm. as a solution comparison, use water.
Simultaneously with the analysis of the sample through all stages of the analysis carried out control experience in chemicals. The value of the optical density of the solution in the reference experiment is subtracted from the value of optical density of test solution and according to the obtained value of the optical density find the mass of vanadium in the calibration schedule.
(Changed edition, Rev. N
1).
3.2. Construction of calibration curve
3.2.1. In a quartz cylinder with a capacity of 15 cmis administered at 0,1; 0,2; 0,3; 0,4 cmof a solution of vanadium (containing 0.1 µg/cmvanadium), go for 0.4 cmof a solution of potassium Bromeliaceae, adjusted with acetic acid to the mark of 5 cm, mix, add 0.2 cmof the solution, PH is acid and mix. In one of the cylinders is introduced all the reagents, except vanadium (zero solution). The cylinders with the solutions immersed in a water bath with a temperature of 50−52 °C and kept at this temperature for 15 min, quickly cooled to room temperature. Absorbance is measured on a photoelectrocolorimeter (490 nm) in a cuvette with a thickness of the light absorbing layer 10 mm. as a solution comparison, use water. The value of optical density of the zero solution is subtracted from the values of optical densities of standard solutions. The measurement is repeated at least three times.
The found average values of optical densities and corresponding mass of vanadium build the calibration graph, the abscissa shows the delay weight of vanadium, and the ordinate — optical density of the solution. Separate test points of the graph along with the analysis of samples.
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of vanadium () in percent is calculated by the formula
,
where is the mass of vanadium in the sample, µg;
— the weight of the portion of the sample,
4.2. Discrepancies in the results of two parallel determinations or the results of the two tests should not exceed the values permitted discrepancies listed in the table.
Mass fraction of vanadium, % |
Allowable difference, % |
1·10 |
1·10 |
5·10 |
2·10 |
1·10 |
5·10 |