GB/T 16484.13-2017 English PDF (GB/T16484.13-2017)

GB/T 16484.13-2017: Chemical analysis methods for rare earth chloride and light rare earth carbonate -- Part 13: Determination of ammonium chloride content
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GB/T 16484.13-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.120.99
H 14
Replacing GB/T 16484.13-2009
Chemical analysis methods for rare earth chloride and light
rare earth carbonate -- Part 13: Determination of
ammonium chloride content
ISSUED ON: OCTOBER 14, 2017
IMPLEMENTED ON: MAY 01, 2018
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Method 1: Distillation-titration ... 6
3 Method 2: distillation-colorimetry ... 11
Chemical analysis methods for rare earth chloride and light
rare earth carbonate -- Part 13: Determination of
ammonium chloride content
1 Scope
This Part of GB/T 16484 specifies the method for determining the amount of
ammonium chloride in rare earth chlorides and light rare earth carbonates.
This Part is applicable to the determination of ammonium chloride content in rare earth
chloride and light rare earth carbonate. There are two methods in total. Method 1 is
distillation-titration method. Method 2 is distillation-colorimetry method. In Method 1,
the determination range (mass fraction) of rare earth chloride is 0.30% ~5.00%, and the
determination range of light rare earth carbonate is 0.30% ~30.00%. In Method 2, the
determination range (mass fraction) of rare earth chloride and light rare earth carbonate
is: 0.005 0% ~1.50%.
2 Method 1: Distillation-titration
2.1 Method principle
Add excess sodium hydroxide solution to the aqueous solution of rare earth chloride
and light rare earth carbonate (dissolved with hydrochloric acid). Heat and distill to
absorb the decomposed ammonia and water vapor with excess sulfuric acid standard
solution. Titrate the excess sulfuric acid with sodium hydroxide standard solution to
calculate the amount of ammonium chloride.
2.2 Reagents
Unless otherwise specified, the reagents used in this Part are analytically pure reagents
that meet national standards or industry standards. The water used is ammonia-free
water. It can be prepared by ion exchange or distillation.
2.2.1 Hydrochloric acid (1+1).
2.2.2 Sulfuric acid (ρ = 1.84 g/mL).
2.2.3 Phenolphthalein indicator: Weigh 0.1 g of phenolphthalein and dissolve it in 100
mL of ethanol (3+2).
2.2.4 Sodium hydroxide solution (250 g/L): Weigh 250 g of sodium hydroxide. Add 1
000 mL of water to dissolve. Stir thoroughly and set aside.
2.2.5 Sodium hydroxide standard titration solution [c (NaOH) ≈ 0.2 mol/L]:
a) Preparation: Transfer 15 mL of sodium hydroxide solution (2.2.4) into a 500 mL
volumetric flask. Dilute to volume with water. Mix well.
b) Calibration: Weigh 0.50 g of potassium hydrogen phthalate dried at 105°C for 2
h, accurate to 0.0001 g, into a 300 mL conical flask. Dissolve in 100 mL of water.
Add a few drops of phenolphthalein indicator (2.2.3). Titrate with the above
sodium hydroxide solution [2.2.5a)] until the red color does not fade, which is the
end point. Titrate 4 times in parallel. When the difference in the volume of the
consumed sodium hydroxide solution [2.2.5a)] is not greater than 0.10 mL, take
the average value.
Calculate the actual concentration of the sodium hydroxide standard titration
solution according to formula (1):
Where,
c1 - actual concentration of sodium hydroxide standard titration solution, in moles
per liter (mol/L);
m - mass of potassium hydrogen phthalate, in grams (g);
V1 - volume of sodium hydroxide standard solution consumed during titration, in
milliliters (mL);
204.22 - relative molar mass of potassium hydrogen phthalate, in grams per mole
(g/mol).
2.2.6 Bromocresol green-methyl red indicator: Weigh 0.1 g of bromocresol green and
dissolve it in 100 mL of ethanol (1+4). Weigh 0.1 g of methyl red and dissolve it in 100
mL of ethanol (3+2). Take 30 mL of the prepared bromocresol green solution and 10
mL of the methyl red solution. Mix them thoroughly.
2.2.7 Sulfuric acid standard solution [c (1/2H2SO4) ≈0.2 mol/L]:
a) Preparation: Take 5 mL of sulfuric acid (2.2.2). Transfer it into a 500 mL
volumetric flask. Dilute to volume with water. Mix well.
b) Calibration: Pipette 25.00 mL of sodium hydroxide standard titration solution
(2.2.5) into a 250 mL conical flask. Add 80 mL of water. Add 3 drops of
bromocresol green-methyl red indicator (2.2.6). Titrate with sulfuric acid standard
Weigh two specimens for parallel determination. Take the average value.
2.5.3 Blank test
Carry out a blank test along with the specimen.
2.5.4 Determination
2.5.4.1 Dissolution of test material
2.5.4.1.1 Rare earth chloride test material: Place the test material (2.5.1) in a 100 mL
beaker. Dissolve it in water. Transfer it to a 100 mL volumetric flask. Dilute to the
volume with water. Mix well.
2.5.4.1.2 Light rare earth carbonate test material: Place the test material (2.5.1) in a 100
mL beaker. Add 30 mL of water. Add hydrochloric acid (2.2.1) dropwise to dissolve.
After complete dissolution, transfer to a 100 mL volumetric flask. Dilute to the volume
with water. Mix well.
2.5.4.2 Distillation
Take the test solution according to Table 1 and inject it from the feed port into the
distillation flask pre-filled with 20 mL of sodium hydroxide solution (2.2.4). Rinse the
wall of the flask several times with a small amount of water to make the volume of the
solution in the distillation flask about 100 mL. Connect the distillation device. Heat and
distill to boiling and keep it for 40 min. The outlet of the condenser (immersed below
the liquid surface) is received by a conical flask pre-filled with 15 mL of sulfuric acid
standard solution (2.2.7) and 60 mL of water. After the reaction is completed, rinse the
wall of the condenser 5 times with water until the volume of the receiving liquid is
about 150 mL.
2.5.4.3 Titration
Add 5 drops of bromocresol green-methyl red indicator (2.2.6) and titrate with sodium
hydroxide standard titration solution (2.2.5) until the solution turns blue-green, which
is the end point.
2.6 Calculation and presentation of analysis results
Calculate the mass fraction of ammonium chloride w(NH4Cl) according to formula (3):
Where,
c2 - concentration of sulfuric acid standard solution, in mol/L;
The effectiveness of the analytical method in this Part shall be verified once a week
using self-made control standards (if national or industry standards are available, they
shall be used first). When the process is out of control, the cause shall be found. The
error shall be corrected. The verification shall be repeated.
3 Method 2: distillation-colorimetry
When the measurement ranges of Method 1 and Method 2 overlap, Method 2 shall be
used as the arbitration method.
3.1 Method principle
Add excess sodium hydroxide solution to an aqueous solution of rare earth chloride and
light rare earth carbonate (dissolved with hydrochloric acid). Heat and distill. The
decomposed ammonia and water vapor are absorbed by excess sulfuric acid solution.
In a strong alkaline system, nitrogen in the form of free ammonia or ammonium ions
reacts with Nessler's reagent to form a yellow-brown complex. Measure its absorbance
at a wavelength of 420 nm on a spectrophotometer to calculate the amount of
ammonium chloride.
3.2 Reagents
Unless otherwise specified, the reagents used in this Part are analytically pure reagents
that meet national standards or industry standards. The water used is ammonia-free
water. It can be prepared by ion exchange or distillation.
3.2.1 Hydrochloric acid (1+1).
3.2.2 Sodium hydroxide solution: Pass 20 mL of sodium hydroxide solution (250 g/L)
through a distillation apparatus to remove nitrogen.
3.2.3 Sulfuric acid: 0.2 mol/L.
3.2.4 Potassium sodium tartrate solution: Weigh 50 g of potassium sodium tartrate.
Dissolve it in 100 mL of water. Heat to boil to drive off nitrogen. Cool thoroughly and
dilute to 100 mL.
3.2.5 Nessler's reagent:
a) Weigh 16 g of sodium hydroxide and dissolve it in 100 mL of water. Cool to room
temperature.
b) Weigh 7 g of potassium iodide and 10 g of mercuric iodide and dissolve them in
200 mL~300 mL of water. Then slowly add this solution to the sodium hydroxide
solution [3.2.5a)] while stirring. Dilute to 500 mL. Store in a brown bottle. Seal
with a rubber stopper. If precipitation occurs, take the supernatant when using.
about 150 mL. Transfer the receiving liquid into a 250 mL volumetric flask. Add water
to dilute to the volume.
3.5.6 Determination
3.5.6.1 Accurately transfer 5.00 mL to 25.00 mL of receiving solution (depending on
the content) into a 50 mL colorimetric tube. Add water to make up to 25 mL.
3.5.6.2 Add 1 mL of potassium sodium tartrate (3.2.4). Shake well. Add 5 mL of
Nessler's reagent (3.2.5). Dilute to the volume with water. Shake well. Let it stand for
10 min.
3.5.6.3 Pipette part of the solution (3.5.6.2) into a 2 cm cuvette. Use the blank solution
as a reference. Measure its absorbance at a wavelength of 420 nm on a
spectrophotometer. Obtain the amount of ammonium chloride from the working curve.
3.5.7 Drawing of working curve
3.5.7.1 Pipette 0 mL, 0.50 mL, 1.00 mL, 2.00 mL, 4.00 mL, 6.00 mL, and 8.00 mL of
ammonium chloride standard solution (3.2.7) into a set of 50 mL colorimetric tubes.
Dilute to 25 mL with water. Proceed as in 3.5.6.2.
3.5.7.2 Pipette part of the solution (3.5.7.1) into a 2 cm cuvette. Use the reagent blank
solution as a reference. Measure its absorbance at a wavelength of 420 nm on a
spectrophotometer. Draw a working curve with the amount of ammonium chloride as
the horizontal axis and the absorbance as the vertical axis.
3.6 Calculation and presentation of analysis results
Calculate the mass fraction of ammonium chloride w (NH4Cl) according to formula
(4):
Keys:
m1 - amount of ammonium chloride obtained from the working curve, in micrograms
(μg);
V0 - volume of the dissolved test solution, in milliliters (mL);
V1 - volume of the test solution taken out, in milliliters (mL);
V2 - volume of the receiving solution, in milliliters (mL);
V3 - volume of the receiving solution taken out, in milliliters (mL);
GB/T 16484.13-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.120.99
H 14
Replacing GB/T 16484.13-2009
Chemical analysis methods for rare earth chloride and light
rare earth carbonate -- Part 13: Determination of
ammonium chloride content
ISSUED ON: OCTOBER 14, 2017
IMPLEMENTED ON: MAY 01, 2018
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Method 1: Distillation-titration ... 6
3 Method 2: distillation-colorimetry ... 11
Chemical analysis methods for rare earth chloride and light
rare earth carbonate -- Part 13: Determination of
ammonium chloride content
1 Scope
This Part of GB/T 16484 specifies the method for determining the amount of
ammonium chloride in rare earth chlorides and light rare earth carbonates.
This Part is applicable to the determination of ammonium chloride content in rare earth
chloride and light rare earth carbonate. There are two methods in total. Method 1 is
distillation-titration method. Method 2 is distillation-colorimetry method. In Method 1,
the determination range (mass fraction) of rare earth chloride is 0.30% ~5.00%, and the
determination range of light rare earth carbonate is 0.30% ~30.00%. In Method 2, the
determination range (mass fraction) of rare earth chloride and light rare earth carbonate
is: 0.005 0% ~1.50%.
2 Method 1: Distillation-titration
2.1 Method principle
Add excess sodium hydroxide solution to the aqueous solution of rare earth chloride
and light rare earth carbonate (dissolved with hydrochloric acid). Heat and distill to
absorb the decomposed ammonia and water vapor with excess sulfuric acid standard
solution. Titrate the excess sulfuric acid with sodium hydroxide standard solution to
calculate the amount of ammonium chloride.
2.2 Reagents
Unless otherwise specified, the reagents used in this Part are analytically pure reagents
that meet national standards or industry standards. The water used is ammonia-free
water. It can be prepared by ion exchange or distillation.
2.2.1 Hydrochloric acid (1+1).
2.2.2 Sulfuric acid (ρ = 1.84 g/mL).
2.2.3 Phenolphthalein indicator: Weigh 0.1 g of phenolphthalein and dissolve it in 100
mL of ethanol (3+2).
2.2.4 Sodium hydroxide solution (250 g/L): Weigh 250 g of sodium hydroxide. Add 1
000 mL of water to dissolve. Stir thoroughly and set aside.
2.2.5 Sodium hydroxide standard titration solution [c (NaOH) ≈ 0.2 mol/L]:
a) Preparation: Transfer 15 mL of sodium hydroxide solution (2.2.4) into a 500 mL
volumetric flask. Dilute to volume with water. Mix well.
b) Calibration: Weigh 0.50 g of potassium hydrogen phthalate dried at 105°C for 2
h, accurate to 0.0001 g, into a 300 mL conical flask. Dissolve in 100 mL of water.
Add a few drops of phenolphthalein indicator (2.2.3). Titrate with the above
sodium hydroxide solution [2.2.5a)] until the red color does not fade, which is the
end point. Titrate 4 times in parallel. When the difference in the volume of the
consumed sodium hydroxide solution [2.2.5a)] is not greater than 0.10 mL, take
the average value.
Calculate the actual concentration of the sodium hydroxide standard titration
solution according to formula (1):
Where,
c1 - actual concentration of sodium hydroxide standard titration solution, in moles
per liter (mol/L);
m - mass of potassium hydrogen phthalate, in grams (g);
V1 - volume of sodium hydroxide standard solution consumed during titration, in
milliliters (mL);
204.22 - relative molar mass of potassium hydrogen phthalate, in grams per mole
(g/mol).
2.2.6 Bromocresol green-methyl red indicat...