GB/T 1626-2008 PDF English
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Oxalic acid for industrial use
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GB/T 1626-1988 | English | 279 |
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Oxalic acid for industrial use
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GB/T 1626-2008: PDF in English (GBT 1626-2008) GB/T 1626-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.060.30
G 17
Replacing GB/T 1626-1988
Oxalic acid for industrial use
ISSUED ON: JUNE 04, 2008
IMPLEMENTED ON: DECEMBER 01, 2008
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Classification and naming ... 6
4 Appearance ... 6
5 Requirements ... 6
6 Test method ... 7
7 Inspection rules ... 14
8 Marking, packaging, transportation and storage ... 15
Oxalic acid for industrial use
1 Scope
This standard specifies the technical requirements, test methods, inspection
rules, marking, packaging, transportation and storage of oxalic acid for
industrial use.
This standard is applicable to the production, inspection and sales of industrial
oxalic acid produced by the synthesis of producer gas and sodium hydroxide
(hereinafter referred to as the synthesis method) or the oxidation of glucose
with nitric acid (hereinafter referred to as the oxidation method).
Molecular formula: H2C2O4·2H2O
Relative molecular mass: 126.07 (according to the international relative atomic
mass in 2005)
2 Normative references
The provisions in following documents become the provisions of this Standard
through reference in this Standard. For the dated references, the subsequent
amendments (excluding corrections) or revisions do not apply to this Standard;
however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
GB/T 601-2002 Chemical reagent - Preparations of standard volumetric
solutions
GB/T 602-2002 Chemical reagent - Preparations of standard solutions for
impurity (ISO 6353-1:1982, NEQ)
GB/T 603-2002 Chemical reagent - Preparations of reagent solution for use
in test method (ISO 6353-1:1982, NEQ)
GB/T 1250 Rules for expression and judgement of limiting values
GB/T 3049-2006 Chemical products for industrial use - General method for
determination of iron content - 1,10-Phenanthroline spectrophotometric
method (ISO 6685: 1982, IDT)
GB/T 6678-2003 General principles for sampling chemical products
6 Test method
Unless otherwise specified, only use reagents confirmed to be analytically pure
and grade 3 water that meets the requirements of GB/T 6682-2008 in the
analysis.
The standard titration solutions, preparations and products used in the analysis
shall be prepared in accordance with GB/T 601-2002, GB/T 602-2002, GB/T
603-2002, when other requirements are not specified.
6.1 Determination of oxalic acid content
6.1.1 Method summary
Acid-base titration. Use phenolphthalein as an indicator; use sodium hydroxide
standard titration solution to make titration; calculate the oxalic acid content.
6.1.2 Reagents
6.1.2.1 Sodium hydroxide standard titration solution: c(NaOH) = 0.5 mol/L;
6.1.2.2 Phenolphthalein indicator solution: 10 g/L.
6.1.3 Analytical procedures
Weigh 1 g of specimen, accurate to 0.002 g; place it in a 250 mL conical flask;
add 30 mL of carbon dioxide-free water to dissolve the specimen; add 2 ~ 3
drops of phenolphthalein indicator solution; use sodium hydroxide standard
titration solution to titrate, until a pale pink color appears; when this color does
not fade in 30 s, it is the end point.
6.1.4 Result calculation
The mass fraction of oxalic acid (calculated as H2C2O4 • 2H2O) is w1; the value
is expressed in %, calculated according to formula (1):
Where:
V1 - The volume value of the standard titration solution (6.1.2.1) of sodium
hydroxide consumed by the sample, in milliliters (mL);
c - The exact value of the concentration of the sodium hydroxide standard
titration solution, in moles per liter (mol/L);
a high-temperature furnace at 850 °C for 5 min. After cooling, add 10 mL of
water and 2 mL of hydrogen peroxide to the residue. After a short time of boiling,
add 1 mL of hydrochloric acid solution; then evaporate to dryness on a water
bath. Add a small amount of water and 0.5 mL of hydrochloric acid solution to
dissolve the residue; use water to wash it into a 50 mL colorimetric tube; add
water to 25 mL (if the solution is turbid, filter it); use it as a specimen solution.
6.2.4.2 Preparation of standard turbidity solution of sulfate radical
Add 0.5, 0.7, 1.0, 1.5, 2.0, 3.0, 4.0, ... mL of sulfate standard solution to each
evaporating dish; then add 0.5 mL of sodium carbonate solution, 10 mL of water,
2 mL of hydrogen peroxide, 1 mL of hydrochloric acid solution, respectively;
evaporate it to dryness on a water bath; add a small amount of water and 0.5
mL of hydrochloric acid solution into each residue; dissolve the residue; use an
appropriate amount of water to rinse it into a 50 mL colorimetric tube; add water
to 25 mL, as the standard turbidity solution of sulfate radical.
6.2.4.3 Determination
Add 10 mL of barium chloride ethanol glycerol solution to the specimen solution
and the sulfate standard turbidity solution; shake well; place for 30 minutes. In
natural light or daylight, compare axially the specimen solution and the sulfate
standard turbidity solution. Take the turbidity closest to the standard turbidity
solution of sulfate as the test result. If the turbidity of the specimen solution is
between two standard turbidity sulfate solutions, the turbidity of the standard
turbidity sulfate solution with high turbidity is used as the test result.
6.2.5 Result calculation
For the mass fraction of sulphate (calculated as SO4) w2, the value is expressed
in % and calculated according to formula (2):
Where:
V2 - The value of the volume of the sulfate standard solution in the sulfate
standard turbidity solution, in milliliters (mL);
m - The value of the mass of the sample, in grams (g);
c - The value of the concentration of the sulfate standard solution, in
milligrams per milliliter (mg/mL) [c = 0.1].
Take the arithmetic mean of the two parallel determination results as the
determination result. The absolute difference between the two parallel
6.5.1.2.4 Iron (Fe) standard solution: 0.1 mg/mL.
6.5.1.3 Apparatus
6.5.1.3.1 Flame atomic absorption spectrometer: It is equipped with iron hollow
cathode lamp and flame atomizer, which meets the requirements of GB/T 9723;
6.5.1.3.2 Electric furnace: temperature adjustable.
6.5.1.4 Instrument operating conditions
The operating conditions of the instrument recommended by this standard:
wavelength 248.3 nm, slit width 0.2 nm, lamp current 2 mA.
6.5.1.5 Analytical procedures
6.5.1.5.1 Drawing of working curve
Take 0, 1.0, 2.0, 3.0, 4.0, 5.0 mL of the iron standard solution, respectively, in
six 100 mL volumetric flasks, respectively; add 5 mL of hydrochloric acid; use
water to dilute it to the mark; shake well, as an iron standard working solution.
Each millimeter of solution contains 0, 1, 2, 3, 4, 5 μg of iron.
Adjust to the best condition according to the performance of the instrument.
Under the given instrument operating conditions, determine the absorbance of
the iron standard working solution; take the absorbance as the ordinate and the
corresponding iron content (μg/mL) in the iron standard working solution as the
abscissa, to draw the working curve. The linear range of the working curve
reaches 5 μg/mL.
6.5.1.5.2 Determination of samples
Weigh 25 g of the specimen, accurate to 0.01 g; place it in a 100 mL quartz
beaker; use a watch glass to cover it; place it on an electric furnace and heat it
at low temperature, until the oxalic acid is completely decomposed and the gas
escapes. Remove and cool to room temperature; add 1.25 mL of hydrochloric
acid; use water to rinse it into a 25 mL volumetric flask; dilute to the mark; shake
well, as a specimen solution.
Measure the absorbance of the specimen solution according to the operating
conditions for drawing the working curve; find out the iron content in the
specimen on the working curve.
6.5.1.6 Result calculation
The mass fraction of iron (calculated as Fe), w3, is expressed in % and
calculated according to formula (3):
m - The value of the mass of the sample, in grams (g).
Take the arithmetic mean of the two parallel determination results as the
determination result.
When the mass fraction of iron is less than 0.003%, the absolute difference
between the two parallel determination results is not more than 20% of the
arithmetic mean of the two determination values.
When the mass fraction of iron is 0.003 ~ 0.01%, the absolute difference
between the two parallel determination results is not more than 10% of the
arithmetic mean of the two determination values.
6.6 Determination of chloride
6.6.1 Method summary
In an acidic solution, chloride and silver nitrate form a white precipitate of silver
chloride, whose turbidity is compared with the standard turbidity solution.
6.6.2 Reagents
6.6.2.1 Nitric acid solution: 1 + 2;
6.6.2.2 Silver nitrate solution: 17 g/L;
6.6.2.3 Chloride (Cl) standard solution: 0.1 mg/mL.
6.6.3 Analytical procedures
6.6.3.1 Preparation of chloride standard turbidity solution
According to different levels of chloride content index values, draw 0.05, 0.02,
0.40, 1.00 mL of chloride standard solutions, respectively, into a 50 mL
colorimetric tube; then add 5 mL of nitric acid solution; add water to 25 mL. This
solution is used as the standard turbidity solution of chloride.
6.6.3.2 Determination
Weigh 1 g of the specimen, accurate to 0.001 g; place it in a 50 mL colorimetric
tube; use a small amount of water to dissolve it; then add 5 mL of nitric acid
solution; add water to 25 mL. This solution is used as the specimen solution.
Add 1 mL of silver nitrate solution to the colorimetric tube containing the
specimen solution and the chloride standard turbidity solution; mix well; place it
for 15 minutes; compare the sample solution and the chloride standard turbidity
solution axially. The turbidity of the specimen solution shall not be deeper than
the turbidity of the chloride standard turbidity solution.
...... Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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