1、Designation: D5356 10 (Reapproved 2015)D5356 17Standard Test Method forpH of Chrome Tanning Solutions1This standard is issued under the fixed designation D5356; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the pH of chrome tanning solutions.1.2 The values stated in SI units are to be rega
3、rded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and deter
4、mine the applicability of regulatorylimitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations i
5、ssuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D3898 Test Method for Chromic Oxide in Basic Chromium Tanning LiquorsE70 Test Method for pH of Aqueous Solutions With the Glass Electrode3. Terminology3.1 Definitions of Terms
6、Specific to This Standard:3.1.1 pH, of a solutionthe negative logarithm of the hydrogen ion activity.3.1.1.1 DiscussionA solution of pH 7 is neutral at 24C. 24 C. Lower numbers indicate increasing acidity, higher numbers indicate increasingalkalinity.4. Summary of Test Method4.1 The chrome tanning l
7、iquor is diluted to a concentration of 25.0 6 0.5 g chromic oxide equivalent per litre, allowed to cometo equilibrium and the pH is then measured with the appropriate meter. For general details of a procedure, Test Method E70 shouldbe consulted. The provisions of the standard shall be governing exce
8、pt where the text of this test method specifically deviates.5. Significance and Use5.1 This test method is designed to measure the pH of a chrome tanning solution which has been diluted to a specificconcentration. This is considered to be a measure of the acidity or alkalinity of the solution.5.2 Th
9、is test method is suitable for quality control in the manufacture of leather.6. Apparatus6.1 pH Meter, either battery or line-operated equipped with appropriate electrodes. The meter shall have a maximum scaledivision of 0.1 pH unit and reproducibility of 0.05 pH unit.NOTE 1Sellers list reasonably p
10、riced models having more sensitivity and greater reproducibility.1 This test method is under the jurisdiction of ASTM Committee D31 on Leather and is the direct responsibility of Subcommittee D31.06 on Chemical AnalysisCurrent edition approved Dec. 1, 2015May 15, 2017. Published December 2015May 201
11、7. Originally approved in 1993. Last previous edition approved in 20102015 asD5356 10.D5356 10(2015). DOI: 10.1520/D5356-10R15.10.1520/D5356-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvo
12、lume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to ade
13、quately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
14、cken, PA 19428-2959. United States17. Reagents7.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch
15、specifications are available.3 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mea
16、n distilled water water,deionized water, or water of equal purity.7.3 Buffer SolutionsCommercially available buffer solutions of 2.00 6 0.02 pH and 4.00 6 0.02 pH shall be used for meterstandardization, in accordance with the manufacturers recommendations and the provisions set forth in Test Methodr
17、ecommendations.E70.8. Standardization8.1 Standardize the meter against the pH 4.00 standard, in accordance with the manufacturers recommendations and theprovisions set forth in Test Method recommendations. E70. The buffer standard shall be at room temperature and the temperaturecompensator shall be
18、set at this temperature.8.2 Read the pH of the 2.00 standard with no adjustment of the meter. The standard shall be at a temperature no more than 2C2 C different from that at which the meter was standardized against the pH 4.00 standard, and the temperature compensator setaccordingly.8.3 If the read
19、ing of the pH 2.00 buffer does not differ by more than 0.05 pH from the published value under the temperatureconditions, the standardization is satisfactory and the meter ready for use. If the error exceeds 0.05 pH, the meter and electrodesmust be checked and the necessary adjustments made to obtain
20、 conformity.9. Procedure9.1 The sample shall be representative of the chrome tanning liquor to be tested. It shall be adjusted to an equivalent chromicoxide concentration of 25.0 6 0.5 g/L (Note 21) and allowed to stand at room temperature for at least 60 min before measuringpH in order to attain di
21、lution equilibrium (Note 32).NOTE 1The concentration adjustment shall be based on the analysis of the liquor for chromium as based on Test Method D3898. In most cases, theconcentration of the sample will be above 25 g chromic oxide per litre and measurement of the appropriate quantity of liquor in a
22、 graduate graduatedcylinder or weighed quantity shall be transferred to a 100-mL volumetric flask. Diluting with water at room temperature,temperature will give sufficientlyaccurate dilution. Spent chrome tanning liquor does not require dilution.NOTE 2If the dilution described in Note 21 takes place
23、 essentially at room temperature, the change in pH is sufficiently slight that 60-min equilibrationwill suffice. If the pH is measured before 60 min has elapsed, report the time. If it is necessary to concentrate the solution by boiling, or the originalsolution was hot, then the diluted sample shoul
24、d be held at least 24 hallowed to reach room temperature before testing, or the pH test may be repeateduntil constant to 0.1 pH are obtained.NOTE 3If measuring the pH of spent chrome tanning solutions, it may be necessary to remove grease and sediment prior to measurement.9.2 After standardization o
25、f the meter (Section 8), rinse the electrodes three times with water and remove surplus water witha soft, nonabrasive tissue. Do not let the electrodes dry. Immediately immerse the electrodes in the prepared sample to a depthrecommended by the manufacturer, set the temperature compensator to the tem
26、perature of the solution (25 6 5C), 5 C), allowthe meter to equilibrate, and read the pH to the nearest pH unit of the meter.10. Report10.1 Report the following information:10.1.1 pH of sample = A (25 g Cr2O3 per litre)where:A = pH reading obtained in Section 9.10.1.2 pH of spent chrome tanning liqu
27、or = B (undiluted)where:B (undiluted) = pH reading obtained in Section 9.3 Reagent Chemicals, American Chemical Society Specifications , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laborato
28、ry Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.D5356 17211. Keywords11.1 chrome tanning solutions; pH ; pH; spent tanning liquorASTM International takes no position respecting the valid
29、ity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subje
30、ct to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarte
31、rs. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard
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