GOST 22536.12-88

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  ГОСТ 22536.12-88

GOST 22536.12−88 carbon Steel and unalloyed cast iron. Methods for determination of vanadium

GOST 22536.12−88

Group B09

STATE STANDARD OF THE USSR

CARBON STEEL AND UNALLOYED CAST IRON

Methods for determination of vanadium

Carbon steel and unalloyed cast iron. Methods for determination of vanadium

AXTU 0809

Valid from 01.01.90
to 01.07.95*
______________________________
* Expiration removed
Protocol N 4−93 inter-state Council
for standardization, Metrology and certification.
(IUS N 4, 1994). — Note the CODE.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of ferrous metallurgy of the USSR

PERFORMERS

D. K. Nesterov, PhD. tech. Sciences; S. I. Rudyuk, PhD. tech. Sciences; S. V. Spirina, PhD. chem. Sciences (head of subject); V. F. Kovalenko, PhD.tech. science; N. N. Gritsenko, PhD.tech. Sciences; E. V. Podpruzhnikov; L. I. birch

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 25.08.88 N 3018

3. REPLACE GOST 22536.12−77

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies the photometric (with a mass fraction of vanadium of 0.05 to 0.25%), titrimetric (mass fraction in vanadium 0,02−0,25%) and coulometric (with the mass fraction of vanadium 0,005−0,25%) methods for determination of vanadium.

Extraction-photometric method for the determination of vanadium given in the Appendix.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 22536.0−87.

1.2. The error of the result of the analysis (under confidence probability =0,95) does not exceed the limit given in table. 1, when the conditions are met:

the discrepancy between the results of two (three) parallel dimensions should not exceed (with a confidence probability =0,95) of the values () given in table. 1;

played in the standard sample, the value of the mass fraction of vanadium should not differ from the certified more than acceptable (at a confidence level =0,85) the value given in table.1.

If any of the above conditions, a second measurement of the mass fraction of vanadium. If in repeated measurements the precision requirement of the results are not met, the results of the analysis recognize the incorrect measurements cease to identify and eliminate the causes of violation of the normal course of analysis.

The divergence of the two middle results of an analysis performed under different conditions (for example, when the control intralaboratory reproducibility) shall not exceed (at p = 0.95) values are given in table. 1.

Table 1

2. PHOTOMETRIC METHOD

2.1. The essence of the method

The method is based on formation of yellow colored sandiegohotelreviews of heteroalicyclic in an acidic environment by the interaction of vanadium (V) with phosphoric acid and the tungstate of sodium and measuring the optical density of colored solution at =400 nm.

The interfering influence of iron can be eliminated by addition of phosphoric acid.

2.2. Equipment and reagents

Spectrophotometer or photoelectrocolorimeter.

Sulfuric acid GOST 4204−77 or GOST 14262−78 diluted 1:4.

Orthophosphoric acid according to GOST 6552−80.

Nitric acid GOST 4461−77 or GOST 11125−84.

Ammonia water according to GOST 3760−79.

Potassium permanganate according to GOST 20490−75, a solution with a mass concentration of 40 g/DM.

Sodium atomistically according to GOST 4197−74, a solution with a mass concentration of 100 g/DM.

Ammonium undeviatingly meta GOST 9336−75.

Sodium volframovich 2-water according to GOST 18289−78, a solution with a mass concentration of 50 g/DM.

Radio engineering carbonyl iron according to GOST 13610−79.

Standard solutions of vanadium.

Solution a: 2,296 g vadeevaloo ammonium dissolved in 100 cmof water, add 2−4 drops of ammonia solution was transferred into a measuring flask with a capacity of 1 DM, dilute to the mark with water and mix.

1 cmof the solution contains 0.001 g of vanadium.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, adjusted to the mark with water and mix thoroughly.

1 cmof a solution contains 0.0001 g wand

ia.

2.3. Analysis

2.3.1. The weight of steel or cast iron weighing 0.5 g (when the mass fraction of vanadium of 0.05−0.10%) or 0.3 g (with a mass fraction of vanadium 0,10−0,25%) was placed in a conical flask with a capacity of 100 cmand dissolved in 15 cmof sulphuric acid (1:4), with moderate heat.

After complete dissolution of the sample poured dropwise nitric acid until the termination of foaming solution. The solution was evaporated until the appearance of sulphuric acid fumes. The contents of the flask cooled, poured 30 cmof water and heated to dissolve the salts. If there is a precipitate (graphite, silicic acid), it is filtered off and washed five or six times with hot water. The filter with the sediment is discarded and the filtrate evaporated to a volume of 30 — 50 cm. The solution was transferred to volumetric flask with a capacity of 100 cm.

The cooled solution was added a solution of potassium permanganate to the formation of stable color. After 3−5 minutes, the excess potassium permanganate restore solution azotistykh sodium, adding it slowly, one drop to a bleaching solution with continuous stirring.

Then pour 5 cmof phosphoric acid, heat the solution to boiling, add 10 cmof a solution of sodium volframovich, stand the solution at 80−90 °C for 2−3 min, cooled, made up to the mark with water and mix.

Optical density of the solution measured on a spectrophotometer at a wavelength of 400 nm or photoelectrocolorimeter with a filter having a region of transmittance in the wavelength range of 400−450 nm. As a solution comparison using the solution of the test sample, prepared without added sodium volframovich.

The analysis results calculated by a calibration chart or by comparison with a standard sample similar in composition to the sample and carried through all stages of the analysis

.

2.3.2. Build graduirovannam graphics

In six conical flasks with a capacity of 100 cmis placed 0.3−0.5 g carbonyl iron depending on sample samples, five of them consistently poured a standard solution B in an amount of 2,0; 4,0; 5,0; 6,0; 8,0 cm, which corresponds to 0,0002; 0,0004; 0,0005; about 0.0006; 0.0008 g of vanadium. The sixth linkage is used for the reference experiment.

In the flask is poured at 15 cmsulphuric acid and dissolved iron at a moderate heat. Further analysis is carried out as specified in clause 2.3.

As a solution comparison solution is used in the reference experiment.

The found values of optical density and corresponding values of the mass of the vanadium build the calibration graph. Allowed construction of calibration curve in the coordinates: the optical density is the mass fraction of vanadium.

2.4. Processing of the results

2.4.1. Mass fraction of vanadium () in percent is calculated by the formula

,

where  — weight of vanadium was found in the calibration schedule g;

 — the weight of the portion of the sample,

2.4.2. Norms of accuracy and norms of accuracy control of determination of mass fraction of vanadium are given in table. 1.

3. TITRIMETRIC METHOD

3.1. The essence of the method

The method is based on the oxidation of vanadium (IV) with potassium permanganate in sulfuric acid medium and titration of vanadium (V) salt solution, the ammonium-iron (II) sulfate. The endpoint of a titration is determined amperometric, potentiometric or visual.

3.2. Equipment and reagents

The setup for potentiometric or amperometric titration of vanadium-defined metrological characteristics of accuracy.

Sulfuric acid GOST 4204−77 or GOST 14262−78 diluted 1:1, 1:4 and 1:50.

Nitric acid GOST 4461−77 or GOST 11125−84.

Orthophosphoric acid according to GOST 6552−80.

Potassium permanganate according to GOST 20490−75, a solution with a mass concentration of 25 g/DM.

Iron (II) sulfate 7-water according to GOST 4148−78, a freshly prepared solution of 2 g of iron sulfate (II) dissolved in water, add 5 cmof sulphuric acid, diluted the solution to 100 cmand mixed.

Sodium atomistically according to GOST 4197−74, a freshly prepared solution with a mass concentration of 20 g/DM.

Urea according to GOST 6691−77, a freshly prepared solution with a mass concentration of 200 g/DM.

Sodium carbonate according to GOST 83−79, a solution with a mass concentration of 2 g/DM.

Phenylantranilic acid solution with a mass concentration of 2 g/DM: 0.2 g phenylanthranilic acid are dissolved in 100 cmof hot sodium carbonate solution with a mass concentration of 2 g/DM.

Standard solutions of vanadium according to claim 2.2.

Ammonium-iron (II) sulfate (Mohr salt) according to GOST 4208−72, standard solutions with molar concentration of equivalent of 0.01 mol/DM(solution A) and 0,002 mol/l(solution B).

Solution a: 4 g of Mohr salt dissolved in 1 DMof sulphuric acid (1:50).

Solution B: 200 cmof the solution And placed in a volumetric flask with a capacity of 1 DM, dilute to the mark with water and mix.

The mass concentration of salt solution Mora set by the standard solution of vanadium. For that 5−10 cmof a standard solution of vanadium A or 10−20 cmof solution B were placed in a glass with a capacity of 250 cm, 50−70 cm addedsulfuric acid (1:4), 10 cmof iron sulfate solution and carried through all stages of the analysis as given in claim 3.3. The resulting solution was titrated with the appropriate salt solution Mora, setting the endpoint of a titration amperometric or potentiometric or visual method, as given in sect. 3.3.

Mass concentration solution of salt Mora (), expressed in grams of vanadium per cubic centimeter of solution is calculated by the formula

,

where mass concentration of a standard solution of vanadium A or B, g/cm;

 — the volume of a standard solution of vanadium A or B, is taken to establish the mass concentration of salt solution Mora, cm;

 — the volume of salt solution Mora, used for titration, sm.

3.3. Analysis

3.3.1. The weight of steel or cast iron with a mass of 2 g (for mass fraction of vanadium 0,02−0,05%) or 1 g (in mass fraction of vanadium of 0.05−0.25%) were placed in a glass with a capacity of 250 cm, pour 50−70 cmof sulphuric acid (1:4) and heated until complete dissolution. To the solution are added dropwise nitric acid until the termination of foaming and advanced 2−3 cm. The solution was evaporated until the appearance of sulphuric acid fumes, cooled. Wash the side of the Cup with water and re-evaporated prior to the allocation of sulphuric acid fumes. The contents of the beaker cooled, poured 50−60 cmof water and heated to dissolve the salts.

If formed insoluble precipitate containing silicic acid and carbon, it was filtered on the filter «white ribbon» and washed 5−6 times with hot water collecting the filtrate and washings in a beaker with a capacity of 400 cm. Filter the precipitate discarded. To the solution in the beaker was added 50 cmof sulphuric acid (1:4), cool, add 5−10 cmof a solution of sulphate ferrous iron, dilute with water to 150 cmand again cooled to 17−20 °C.

To the cooled solution under constant stirring added dropwise a solution of potassium permanganate until a stable pink color. After 1−2 min added dropwise a solution of sodium attestatio until complete disappearance of the pink color and immediately add 10 cmof urea.

After 3 min into the solution immerse a selected pair of electrodes (installed in the amperometric titration of the required voltage), turn on the millivolt-ammeter, magnetic stirrer and titrated amperometric or potentiometric salt solution Mora A or B (depending on the mass fraction of vanadium), adding it in small portions from microburette and noting the reading after each addition of titrant (if the amperometric titration or until a sharp deflection of the device (when potentiometric titration).

By visual determination of the titration end point to the solution prepared for titration, add 5−6 drops of a solution phenylanthranilic acid and titrated with a solution of salt Mora before moving cherry color of the solution yellow-green.

In all cases the addition of salt solution Mora is made from microburette small portions, and at the end of the titration — at kapl

pits.

3.4. Processing of the results

3.4.1. Mass fraction of vanadium () in percent is calculated by the formula

,

where is the mass concentration of salt solution Mora, expressed in g/cmvanadium;

 — the volume of salt solution Mora, corresponding to the end point of the titration, cm;

 — the weight of the portion of the sample,

3.4.2. Norms of accuracy and norms of accuracy control of determination of mass fraction of vanadium are given in table. 1.

4. COULOMETRIC METHOD

4.1. The essence of the method

The method is based on the interaction of vanadium (V) with electrochemically generated iron ions (II). The endpoint of a titration set limperatrice with two polarized platinum electrodes.

4.2. Equipment and reagents

The potentiostat P-5827, P-5848, or any other operating mode of the specified current.

Setup for amperometric titrations with two polarized indicating electrodes.

Working generating electrode and tungsten with square visible surface of 1.0−2.0 cm.

The auxiliary platinum electrode with an area of 0.5−1.0 cm.

Indicator system: two identical platinum electrodes with an area of 1 cm.

A voltage source providing a voltage to the electrodes of at least 100 mV.

The stopwatch according to GOST 5072−79.

Tungsten metal electrode to the generator (purity not less than 99%).

Alum salesonline according to GOST 4205−77, solution with a molar concentration of 0.5 mol/DM: 240 g gentoomaniac alum dissolved in 500 cmof water, gently poured 100 cmof sulphuric acid and heated until complete dissolution of salts. The solution was cooled, top up with water to 1 DM, thoroughly mixed and filtered through a filter of medium density.

Ammonium-iron (II) sulfate (Mohr salt) according to GOST 4208−72, a solution with a mass concentration of 12 g/DM: 12 g of salt Mora dissolve and 400−500cmof water, carefully pour 50 cmof sulphuric acid, cool, add water to 1 DM, stirred and filtered through a dry filter of medium density.

Sulfuric acid GOST 4204−77 or GOST 14262−78, solution with molar concentration of the equivalent 0,1 mol/DM.

The other reagents and solutions for

claim 3.2.

4.3. Analysis

The weight of steel or cast iron depending on the mass fraction of vanadium (see table. 2) dissolve and prepare a solution for titration until its cooling according to claim 3.3.1.

Table 2

To the obtained solution pour 1−2 cmof salt Mora.

The glass of the analyzed solution set on the mixer include stirring, add a 10 cmsolution gentoomaniac alum, are added dropwise a solution of potassium permanganate until stable for 1 min the pink color of the solution. After 1−2 min added dropwise a solution of sodium attestatio until complete disappearance of the pink color and immediately 1−2 g of urea.

In the glass down the generator and indicator electrodes, is applied to the display electrodes, the polarization voltage of 50−100 mV. In another glass filled with sulfuric acid solution with molar concentration of the equivalent 0,1 mol/DM, lower platinum electrode and close the circuit with a salt bridge filled with a solution of sulfuric acid of the same concentration.

Note the initial position of the indicator of the measuring instrument (microammeter), are included in the indication of the titration end point, at the same time include a current generator and a stopwatch. The electrolysis was carried out until until the indicator of the measuring device begins to deviate from the original position. At this point, turn off the generator current, simultaneously stop the stopwatch and record the indicator readings (microammeter) and time. In the course of the titration control is still 2−3 times the indicator system, including the generator current and the stopwatch at 3−10 seconds and recording the readings.

Build a graph of the readings of the indicator system against time and find the time corresponding to the end point of the titration. It will correspond to the point of intersection of the straight sections of the two branches of the curve.

4.4. Processing of the results

4.4.1. Mass fraction of vanadium () in percent is calculated by the formula of Faraday:

;

;

where is the number of Faraday (=96500 C);

 — the atomic weight of vanadium (=50,95 g);

 — the number of electrons involved in the recovery of vanadium (=1);

 — force generating current, A;

 — the time corresponding to the end point of titration, C;

 — the weight of the portion of the sample,

G.

4.4.2. Norms of accuracy and norms of accuracy control of determination of mass fraction of vanadium are given in table. 1.

APPLICATION (recommended). EXTRACTION-PHOTOMETRIC METHOD FOR THE DETERMINATION OF VANADIUM WITH BPHA WHEN THE MASS FRACTION OF 0,02−0,25%

APP

Recommended

1. The essence of the method

The method is based on formation of colored in purple color complex compounds of vanadium (V) -phenylbenzimidazole acid in the hydrochloric acid solution with molar concentration of equivalent of 6 mol/l, extracting it with chloroform, and measuring the optical density of the colored solution at a wavelength of 530 nm.

2. Equipment and reagents

Instrument and reagent according to claim 2.2 of this standard, with additions.

Spectrophotometer or photoelectrocolorimeter.

Hydrochloric acid by the GOST 3118−77 or GOST 14261−77.

Sulfuric acid GOST 4204−77 or GOST 14262−78 diluted 1:4.

Nitric acid GOST 4461−77 or GOST 11125−84.

Orthophosphoric acid according to GOST 6552−80.

-phenylbenzimidazole acid (BPHA), a solution with a mass concentration of 2 g/lin chloroform.

Ammonia water according to GOST 3760−79.

Chloroform according to GOST 20015−84.

Potassium permanganate according to GOST 20490−75, a solution with a mass concentration of 0.3 g/DM.

Ammonium undeviatingly meta GOST 9336−75.

Standard solutions of vanadium A and B prepared as given in claim 2.2 of this standard.

Radio engineering carbonyl iron according to GOST 13610−79.

3. Analysis

3.1. The weight of steel or cast iron weighing 0.5 g (when the mass fraction of vanadium is 0.02−0.1%) or 0.25 g (when the mass fraction of vanadium of 0.1−0.25%) was placed in a beaker with a capacity of 200 cm, add 30 cmof sulphuric acid (1:4), 5 cmof phosphoric acid and dissolved with moderate heating.

After complete dissolution of the sample poured dropwise nitric acid until the termination of foaming solution. The solution was evaporated until the appearance of sulphuric acid fumes. Wash the side of the Cup with water and again evaporated to the appearance of sulphuric acid fumes. Salt is dissolved in 20 cmof water under heating, cooled and transferred to volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. In the case of the analysis of cast iron the solution was filtered on a medium density filter and the precipitate washed 5−6 times with hot water collecting the filtrate and washings in a volumetric flask with a capacity of 100 cm. Filter the precipitate discarded.

Aliquot part of the solution is 15 cmis placed in a separating funnel with a capacity of 100 cm, successively, with stirring, was added a solution of potassium permanganate until a stable pink coloring and 3−4 drops in excess, allowed to stand for 1 min, add 15 cmof a hydrochloric acid solution, 10 cm, BPHA solution in chloroform and shake for 1 min.

The chloroform extract is poured into a measuring flask with a capacity of 25 cm. To the solution in separating funnel add 5 cmof the solution, BPHA in chloroform and shaken for 30 s. the Obtained extracts combine, add chloroform to the mark, stirred for 1 hour and measure the absorbance on the spectrophotometer at a wavelength of 530 nm or photoelectrocolorimeter with a filter having a region of transmittance in the wavelength range of 500−560 nm. As a comparison, using a solution of chloroform.

The analysis results calculated by a calibration chart or by comparison with a standard sample similar in composition to the sample and carried through all stages of the analysis.

From the values of absorbance of each test solution subtract the value of the optical density of the control

experience.

3.2. Construction of calibration curve

Six glasses with a capacity of 200 cmis placed 0.5 or 0.25 g of carbonyl iron (depending on sample tests). Five of them poured 0,5; 1,0; 3,0; of 5.0 and 7.0 cmstandard solution B, which corresponds to 0,00005; 0,00010; 0,00030; 0,00050; 0,00070 g of vanadium. The sixth glass is used for the reference experiment. All the glasses are poured at 30 cmof sulphuric acid (1:4), 5 cmof phosphoric acid and dissolved iron at a moderate heat. Then do as given in claim 3.

On the found values of optical density and corresponding weight values of vanadium build the calibration graph. Allowed construction of calibration curve in the coordinates: the optical density is the mass fraction of vanadium.

4. Processing of the results

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

,

where is the mass of the vanadium in the sample was found in the calibration schedule g;

 — the weight of the portion of the sample,

4.2. Norms of accuracy and norms of accuracy control of determination of mass fraction of vanadium are given in table. 1.