ASTM D6019-96

Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate Oxidation)

SCOPE
1.1 This test method covers the determination of chromic oxide in chrome tanning liquors, either simple, with added aluminum or zirconium, or with the usual masking complexing agents.  
1.2 The values stated in SI units are to be regarded as the standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Oct-1996
• Technical Committee: D31 - Leather
• Drafting Committee: D31.06 - Chemical Analysis

Relations

• Replaced By: ASTM D6019-96(2001) - Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate Oxidation)
• Effective Date: 10-Oct-1996
• Referred By: ASTM D3897-18 - Standard Test Method for Calculation of Basicity of Chrome Tanning Liquors
• Effective Date: 10-Oct-1996

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 6019 – 96
Test Method for
Determination of Chromic Oxide in Basic Chromium
Tanning Liquors (Ammonium Persulfate Oxidation)
This standard is issued under the fixed designation D 6019; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope where such specifications are available. Other grades may be
used, provided it is first ascertained that the reagent is of
1.1 This test method covers the determination of chromic
sufficiently high purity to permit its use without lessening the
oxide in chrome tanning liquors, either simple, with added
accuracy of the determination.
aluminum or zirconium, or with the usual masking complexing
4.2 Purity of Water—Unless otherwise indicated, reference
agents.
to water shall be understood to mean distilled water or water of
1.2 The values stated in SI units are to be regarded as the
equal purity.
standard.
4.3 Ammonium Persulfate—20 % solution 100 gm of per-
1.3 This standard does not purport to address all of the
sulfate into 500 mL water.
safety concerns, if any, associated with its use. It is the
4.4 Starch Indicator, 1 %—Make a paste of1gof soluble
responsibility of the user of this standard to establish appro-
starch in about 10 mL of water, add 90 mL water, and boil for
priate safety and health practices and determine the applica-
1 min with stirring. Cool and add one drop of chloroform. The
bility of regulatory limitations prior to use.
solution is subject to decomposition and should be renewed if
2. Summary of Test Method a deep blue color is not obtained on addition of one drop of
indicator to a solution of 1 drop tincture of iodine in 100 mL of
2.1 The solution is oxidized with ammonium persulfate
water.
until the chromium is completely converted to the chromate
4.5 Sodium Thiosulfate Solution, 0.1 N—Dissolve 24.85 g
ion. The solution is boiled to complete oxidation of organic
of Na S O ·5H O in water, add1gNa CO , and dilute to 1 L.
materials and to destroy excess ammonium persulfate; it is then 2 2 3 2 2 3
4.5.1 Standardization—Dry potassium dichromate
cooled and acidified. Potassium iodide is added, and the
(K Cr O ) in an oven at 130°C for 2 h and cool in a desiccator.
2 2 7
liberated iodine is titrated with standardized sodium thiosul-
Weigh into a glass stoppered Erlenmeyer flask (500 mL) about
fate.
0.2 g of potassium dichromate to an accuracy of 0.1 mg.
3. Significance and Use
Dissolve in 250 mL water, add 15 mL 1:4 hydrochloric acid, 20
mL of 10 % potassium iodide solution, stopper the flask, and
3.1 The procedure described is for the quality control for
allow to stand 5 min in the dark. Titrate with the sodium
manufacturing liquors and specifications for the purchase of
thiosulfate to be standardized. When the color of the solution
such liquors.
has faded to a brownish-green, add 2 mL of 1 % starch
3.2 The chromium content of the liquors determines the
solution, and continue titrating until the deep blue color
amount to be used to obtain the desired degree of tannage, and
changes to a clear green. Record the titration.
hence may be a matter for specification in the purchase of
leather.
weight potassium dichromate
normality of sodium thiosulfate 5
0.04903 3 mL titration
4. Reagents and Materials
(1)
4.1 Purity of Reagents—Reagent grade chemicals shall be
The thiosulfate solution is quite stable but should be restan-
used in all tests. Unless otherwise indicated, it is intended that
dardized at least once a month.
all reagents shall conform to the specifications of the Commit-
4.6 Potassium Dichromate,K Cr O , primary standard
2 2 7
tee on Analytical Reagents of The American Chemical Society,
grade.
4.7 Potassium Iodide, 6 %—Dissolve6gKIin100 mL
water.
This test method is under the jurisdiction of ASTM Committee D-31 on Leather
and is the direct responsibility of Subcommittee D31.06 on Chemical Analysis—
Reagent Chemicals, American Chemical Society Specifications, American
General. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Current edition approved Oct. 10, 1996. Published December 1996. listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 6019
A 3
...