GOST 23862.32-79
GOST 23862.32−79 Rare-earth metals and their oxides. Methods of determination of fluoride (with Change No. 1)
GOST 23862.32−79
Group B59
INTERSTATE STANDARD
RARE EARTH METALS AND THEIR OXIDES
Methods of determination of fluorine
Rare-earth metals and their oxides. Methods of determination of fluorine
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 fluoride (2.5·10% 1·10
%) in rare earth metals and their oxides and ionometric method for determination of fluoride (from 1·10
% 1·10
%) in the oxides of rare earth metals.
(Changed edition, Rev. N 1).
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 23862.0−79.
THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF FLUORIDE
The method is based on formation of colored complex compounds of fluoride with lanthanum alizarinsulfonate. The definition is preceded by the Stripping of fluorine in the catalyst is acid pyrohydrolysis.
(Changed edition, Rev. N 1).
2. APPARATUS, REAGENTS AND SOLUTIONS
Photoelectrocolorimeter FEK-56 or similar device.
Magnetic hanger.
Tile electric.
Installation for pyrohydrolysis (drawing) consists of a tubular resistance electric furnace of SUOL-0,25·1/12-M1. In the oven is inserted into a quartz tube with a diameter of 20−25 mm, a length of 460−500 mm drawn at a right angle discharge tube length of 260 mm and a diameter of 12 mm To the top of the outlet tube is soldered coupler for refrigerator a length of 150 mm and a diameter of 25 mm. the end of the outlet tube equipped with a bubbler with holes 1 mm. Vapor used in the process of pyrohydrolysis, is formed in the steam generator, connected to the quartz tube through a rubber tube, and fed into the furnace by using gaseous nitrogen or oxygen from a cylinder, passed through a pre-cleaning of bottles filled in part:
— solution of potassium permanganate at a concentration of 10 g/DM
solution of sodium hydroxide (50 g/DM
); b — water. The heating of the steam generator (conical flask with a capacity of 750 cm
) held on a hot plate.
1 — a gas cylinder; 2 — cleaning of the flask; and the solution of KMPOin NaOH solution, b — distilled water; 3 — hot plate; 4 — steam generator; 5 — tubular electric resistance furnace; 6 — quartz boat; 7 — platinum-platinum / rhodium thermocouple; 8 — quartz tube; 9 — refrigerator; 10 — breather pipe; 11 — flask-receiver; 12 — millivoltmeter; 13 — voltage transformer to control the temperature of the furnace
Quartz boats with a length of 70 mm and a width of 10 mm pre-calcined at 950−1000 °C in a current of steam for 30−40 min.
The hook is made of quartz glass tubes with a diameter of 5 mm and a length of 500 mm.
Volumetric flasks.
Pipettes without dividing, with a capacity of 5, 10 and 15 cm.
Plastic cans with a capacity of 500 and 1000 cm.
The measuring cylinders.
Filters «white» or «red» tape.
Paper universal indicator.
The gaseous nitrogen according to GOST 9293−74 or oxygen gas GOST 5583−78.
Hydrochloric acid by the GOST 3118−77, h. e. a., 12; 2 and 0.5 mol/DMsolutions.
Acetic acid GOST 61−75, ice, h. e. a.
Sodium hydroxide according to GOST 4328−77, H. C., 1; 0.1 and 0.02 mol/DMsolutions.
Sodium acetate according to GOST 199−78, h.d. a.
Acetone according to GOST 2603−71*, h.d. a.
______________
* On the territory of the Russian Federation GOST 2603−79. — Note the manufacturer’s database.
Potassium permanganate according to GOST 20490−75, h.d. a.
Silicon dioxide according to GOST 9428−73, h.d. a.
Cobalt oxides according to GOST 4467−79.
Sodium fluoride according to GOST 4463−76, h.d. a.
Standard solution of fluoride (spare) containing 1 mg/cmfluoride: a sample of sodium fluoride with a mass of 2.21 g dissolved in water and bring the volume of solution in a volumetric flask to 1000 cm
water; store in a plastic container.
The working solution containing 5 ág/cmfluorine, is prepared by dilution of a spare of a standard solution with water to 200 times; store in a plastic container.
Buffer acetate (pH=4,5): 100 g sodium acetate and dissolve in water, add 50 cmof glacial acetic acid and the volume was adjusted with water in a volumetric flask to 1000 cm
.
Alizarincomplexon (1,2-dihydroxyanthraquinone-3-methylamine-N, N-luxusny acid), h. e. a., 0,002 mol/DMsolution: weighed lisaraniray a mass of 0.79 g was suspended in a small amount of water in a beaker or conical flask while stirring with a magnetic stirrer. Add dropwise a minimum required amount of 0.1 mol/DM
of sodium hydroxide solution to dissolve the reagent. After dissolution, add dropwise 2 mol/DM
hydrochloric acid solution to pH~4−5, filtered into a measuring flask with volume capacity of 1000 cm
and the volume was adjusted solution to the mark with water.
Lanthanum nitrate, h, 0,002 mol/DMsolution: weighed lanthanum nitrate mass 0,866 g dissolved in a small amount of water, transfer the solution into a measuring flask with volume capacity of 1000 cm
and the volume was adjusted solution to the mark with water.
Water-acetone solution of the mixed reagent: to 5 volumes of acetone is added 1 volume of acetate buffer, 2 volumes of a solution of elizarenkova and 2 volumes of solution of nitrate of lanthanum. Strictly observe the order of addition of reagents; prepared on the day of use.
Sec. 2. (Changed edition, Rev. N 1).
3. PREPARATION FOR ASSAY
3.1. Prepare the installation for pyrohydrolysis, visually inspecting the condition of furnace, electric, insulation of the live wires, grounding connection; includes a hot plate for heating water in the steam generator to boil, turn on the oven, adjust the gas flow by setting the rate of 1−2 bubbles per second. A bubbler is immersed in the receiver (a crystal or a plastic glass with a capacity of 100 cm) containing 10 cm of 0.02 mol/DM of sodium hydroxide solution. Oven heated to 400 °C.
4. ANALYSIS
4.1. A portion of the metal (fine shavings) or oxides of the REE mass 0.2−1.0 g (depending on the content of fluorine) mixed with 0.5 g of silicon dioxide and 0.1 g of cobalt oxide, pre-calcined at 750−800 °C, transferred to a quartz boat which is placed in a quartz tube installation for pyrohydrolysis in the center of the oven, and immediately connect the steam generator to the device for pyrohydrolysis. Include oven, raise the temperature to 1100 °C and hold pyrohydrolysis for 20 minutes, then oven off and disconnect the steam generator tube from the device.
Received in the receiver solution is neutralized with 0.5 mol/DMhydrochloric acid solution (universal indicator paper) to pH~4−5, transferred to a volumetric flask with a capacity of 100 cm
, adjusted to the mark with water and mix. Select aliquot part of the solution was 10 cm
in a volumetric flask with a capacity of 25 cm
, add a 10 cm
water-acetone solution of the mixed reagent and then do as under construction of calibration curve. A lot of fluoride found by the calibration schedule.
(Changed edition, Rev. N 1).
4.2. Construction of calibration curve
In a volumetric flask with a capacity of 25 cmis introduced 0,50; 1,00; 2,00; 3,00; 4,00 and 5,00 cm
working solution of fluoride (containing 5 g/cm
fluorine). Add 10 cm
of water-acetone solution of the mixed reagent, the volume was adjusted to the mark with water and mix thoroughly. Optical density of the solution is measured after 20 min on photoelectrocolorimeter at
According to the obtained results build a calibration curve, causing the y-axis the value of the optical density of the solution, and on the x — axis is the mass of fluoride in milligrams.
5. PROCESSING OF THE RESULTS
5.1. Mass fraction of fluorine () in percent is calculated by the formula
where is the mass of fluoride was found in the calibration graphics mg;
— aliquota part of the solution was taken to determine cm
;
— the weight of the portion of the sample, g;
— volume of the volumetric flask, cm
.
The result of the analysis taking the arithmetic mean of two parallel definitions, drawn from separate batches.
5.2. 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
| Mass fraction of fluorine, % |
Allowable difference, % |
2,5·10 |
2·10 |
5·10 |
2·10 |
1·10 |
2·10 |
6. IONOMETRIC METHOD FOR DETERMINATION OF FLUORIDE
The method is based on measuring the potential pereselencheskogo electrode with a membrane of lanthanum fluoride activated by divalent europium, relative to silver chloride electrode.
The measurement is performed in a solution with a high (of the order of 1.75 mol/l) ionic strength at pH=5−6 using ionomer EV-74 or similar device.
6.1. Apparatus, reagents and solutions
Electrode fluoride ЭF-U1.
Silver chloride electrode according to GOST 16286−84.
Ion meter EV-74 or similar device.
Tile laboratory electric power of 400 watts.
Muffle furnace with thermostatic control, providing heating of 400−600 °C.
The tank is made of organic glass with a capacity of 100−200 cm.
Key electrolytic ebonite with a diameter of 10−20 mm, a height of 100−120 mm, diameter of upper nozzle 5 to 7 mm.
Plastic cans with screw-caps, with a capacity of 1000 cm.
A Cup made of polyethylene or vinyl plastic with a capacity of 100 cm.
A glass chemical glass with a capacity of 1000 cm.
Stirrer magnetic type MSM with a magnet.
Volumetric flasks with a capacity of 50 and 1000 cm.
Pipettes with a capacity of 1 and 5 cm.
Obestochennye paper filter «white ribbon».
The Nickel crucible with a capacity of 25−30 cm.
Sodium chloride according to GOST 4233−77, h.d. a.
Sodium hydroxide according to GOST 4328−77, H. h, solution with concentration of 250 g/DM.
Sodium acetate 3-water according to GOST 199−78, h. d. a. and a solution with a concentration of 250 g/DM.
Sodium citrate according to GOST treasuremania 22280−76, h.d. a.
Sodium fluoride according to GOST 4463−76, H. h
Potassium chloride according to GOST 4234−77, H. h, a saturated solution.
Acetic acid GOST 61−75, ice, H. h
Lanthanum oxide (mass fraction of fluorine not more than 0.001% wt.).
Salt dinatria Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652−73, h.d. a.
Buffer solution with a pH of about 4.5 and an ionic strength of about 1.75 mol/DM(BROS), the concentration of the solution: 0,86 mol/l
in acetic acid, 1 mol/DM
for sodium chloride, 0.45 mol/DM
acetic acid on the sodium, 0,0116 mol/DM
for sodium citrate, 0,0008 mol/DM
at Trilon B; prepared as follows: 58,5 g of sodium chloride, 61,5 g sodium acetate, 3 g of sodium citrate and 0.3 g of Trilon B, is placed in a beaker with a capacity of 1000 cm
, dissolve in 500 cm
of water, add 50 cm
of acetic acid, transferred into a measuring flask with volume capacity of 1000 cm
, adjusted to the mark with water, mix.
Stock solution of fluoride (solution A) is prepared as follows: a sample of sodium fluoride mass 0,2210 g dissolved in water, transferred into a measuring flask with volume capacity of 1000 cm, adjusted to the mark with water, mix.
1 cmof a solution contains 0.01 mg of fluoride.
Store the solution not exceeding 30 days in a plastic jar.
Working solutions of fluorine (B, C):
Solution B is prepared as follows: 5 cmsolution And placed in a volumetric flask with a capacity of 50 cm
, adjusted to the mark, mix.
1 cmof a solution contains 0.01 mg of fluoride.
The solution is prepared as follows: 5 cmof solution B is placed in a volumetric flask with a capacity of 50 cm
, adjusted to the mark with a solution of BROS, mix.
1 cmof the solution contains 0.001 mg of fluoride.
Solutions B and C prepared
on the day of use.
6.2. Preparation for assay
6.2.1. The sensor arrangement
Strengthen the tripod tank: organic glass, connected with a displacement sensor electrolytic key. The tank and the electrolytic switch is filled with saturated solution of potassium chloride, is immersed in a tank hlorserebryany electrode.
The electrode ЭF-U1 and the electrolytic switch is placed in the working volume of the sensor — vinyl glass mounted on the table magnetic stirrer. In a glass place the magnet and poured 40 cmsolution, BROS, measure the electrode potential ЭF-U1 relative to silver chloride reference electrode after attaching the electrodes to the appropriate sockets of the ionomer in accordance with the passport electrode ЭF-U1. The potential value should be set to a constant 3−5 min and should be not less than 290 mV. Then in a glass pour the vinyl 40−50 cm
solution and after 1 min measure the electrode potential. The measurements are repeated two more times with new portions of solution fluoride. After obtaining a constant value of capacity (measured allowed difference between the highest and lowest value of the potential is not more than 4 mV), you can begin analysis.
6.2.2. Construction of calibration curve
Five batches of the oxides of lanthanum mass of 200.0 mg was placed in a Nickel crucible, add 0,25; 0,50; 1,0; 2,0 and 2.5 cmof solution B, flow 6−8 cm
of sodium hydroxide solution, evaporated to dryness by heating to 50−70 °C and fused in a muffle at 400−600 °C for 5−10 min, the melt was cooled to room temperature, add 20 cm
of water leached when heated to 50−70 °C. the Contents of the crucible was filtered, collecting the filtrate in a volumetric flask with a capacity of 50 cm
, the filter cake washed twice with 1−2 cm
of water collecting the flushing solution into the same volumetric flask and the filter with the sediment discarded. The solution in volumetric flask was adjusted to the mark with a solution of BROS. 1 cm
of the obtained solutions contain, respectively, 5·10
, 1·10
, 2·10
, 4·10
and 5·10
mg of fluoride. In the solutions measure the potentials of the electrode ЭF-U1 according to claim
According to the obtained results build a calibration curve, while the ordinate values of the electrode potential, mV, and x — axis is the negative logarithm of the concentration of fluorine (pF solution). Values pF for the solutions are, respectively, 5,58; 5,28; 4,98; 4.68 and 4,58.
The deviation of points of calibration curve from a straight line shall not exceed ±3 mV; the magnitude of potential per unit pF should be (56±3) mV. In the event of deviations from the specified values, replace the electrode.
Validation of calibration curve performed once in 10−15
days.
6.3 analysis
Two sample analyzed oxide REE weighing 0,200 g is placed in Nickel crucibles, poured 6−8 cmof sodium hydroxide solution and then act as indicated in item 6.2. In the resulting solutions measured electrode potential ЭF-U1 according to claim
Simultaneously with the sample hold control experience for contamination of reagents.
6.4. Processing of the results
6.4.1. Mass fraction of fluorine () in percent is calculated by the formula
where — the weight of the portion of the sample, mg;
— the concentration of fluoride in the measured amount of mg/cm
.
The value is determined as follows: according to the calibration schedule determines the pF value of the analyzed solution, from the values of the pF according to the table of logarithms find the concentration in mol/DM
and the value transferred in mg/cm
.
The result of the analysis taking the arithmetic mean of two parallel definitions, drawn from separate batches.
6.4.2. 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
| Mass fraction of fluorine, % |
Allowable difference, % |
| 0,005 |
0,0015 |
| 0,01 |
0,003 |
| 0,10 |
0,03 |
