1、Designation: C 837 99 (Reapproved 2003)Standard Test Method forMethylene Blue Index of Clay1This standard is issued under the fixed designation C 837; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the adsorp-tion of methylene blue dye by a clay, which is calculated as amethylene blue index
3、for a clay.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. R
4、eferenced Documents2.1 ASTM Standards:C 324 Test Method for Free Moisture in Ceramic Whitew-are Clays23. Significance and Use3.1 Tests run on many clays generally indicate that astraight-line relationship exists between the methylene blueindex (MBI) and such fundamental clay properties as cationexch
5、ange capacity, dry bond strength, and casting rate. Wherethe colloidal portion of the clay is kaolinite, there is also adirect correlation with specific surface (as determined bynitrogen adsorption). Where the colloidal portion containssignificant amounts of illite or montmorillonite, the same close
6、correlation does not exist. The MBI better correlates with theceramic-forming properties than does the specific surface.3.2 That portion of a clay lying within the colloidal range(generally defined as the 0.5- to 0.001-m range), determinesthe strictly colloidal properties of the clay and, together w
7、iththe amount and type of organic material associated with theclay and the 2- to 0.2-m fraction, largely determines theproperties of the clay when used in ceramic-forming processes.While the specific surface of a clay is a function of the particlesize and morphology and a relationship exists between
8、 dyeadsorption and specific surface, the MBI should not be con-sidered to be a particle size analysis since the value obtained isdominated by the character of only the very fine end of theparticle size distribution. This procedure describes the deter-mination of the dye adsorption (in this case, met
9、hylene blue) ofa clay.4. Apparatus4.1 Balance, accurate to 0.01 g.4.2 Mixer.34.3 pH Meter or pH Paper.4.4 Beaker, 600 mL.4.5 Buret,25mL.4.6 Medicine Dropper or Glass Stirring Rod.4.7 Filter Paper, Baroid No. 987.45. Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unl
10、ess otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently
11、 high purity to permit its use without lessening theaccuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean distilled water or water ofequal purity.5.3 Methylene Blue Solution (1 mL = 0.01 meq)4Store indarkness.5.4 Sulfuric Acid (0.
12、1N).6. Procedure6.1 Weigh out 2.00 g of clay that has been dried inaccordance with the procedure in Test Method C 324 and place1This test method is under the jurisdiction of ASTM Committee C-21 onCeramic Whitewares and Related Products and is the direct responsibility ofSubcommittee C 21.04 on Clays
13、.Current edition approved Oct. 1, 2003. Published October 2003. Originallyapproved in 1976. Last previous edition approved in 1999 as C 837 99.2Annual Book of ASTM Standards, Vol 15.02.3This test method is based on the use of the Model F Lightnin mixer, which isavailable from Mixing Equipment Co., I
14、nc., Rochester, NY. However, it has beenfound that some clays are not completely dispersed in this apparatus, and so resultsmay be spurious. It has been found that the Waring Blender, available from WaringProducts Division, Dynamics Corporation of America, New Hartford, CT 06057, issuccessful in dis
15、persing all clays.4Available from Baroid Div., National Lead Co., No. 425-15.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for Laborat
16、oryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.in the 600-mL beaker. If
17、the clay cannot be tested immediatelyafter drying, it should be stored in a desiccator.6.2 Add 300 mL of distilled water to the beaker and stir withthe mixer until the clay is uniformly dispersed.6.3 Determine the pH of the slurry and add sufficientsulfuric acid to bring the pH within the range from
18、 2.5 to 3.8.Continue stirring while the pH is being adjusted and continuestirring for 10 to 15 min after the last addition of acid.6.4 Again test the slurry for pH, adding additional acid ifnecessary to restore the pH to the 2.5 to 3.8 range.6.5 With the slurry still under the mixer, fill the buret
19、withthe methylene blue solution, add 5 ml of the solution to theslurry, and stir for 1 to 2 min.6.6 Remove a drop of the slurry, using the dropper or theglass stirring rod, and place on the edge of the filter paper.6.7 Observe the appearance of the drop on the filter paper.The end point is indicated
20、 by the formation of a light blue haloaround the drop. Continue adding the methylene blue solutionto the slurry in 1.0-mL increments with 1 to 2 min of stirringafter each addition, then testing, until the end point is reached.For ball clays with relatively high methylene blue indexes,testing may sta
21、rt after two or even three 5-mL additions havebeen made to save time. Allow 1 to 2 min of stirring after each5-mL increment.6.8 After the end point is reached, continue stirring for 2min and retest.NOTE 1Greater precision can be obtained by using larger sampleswith only minor influence on the value
22、obtained.7. Calculation7.1 Calculate the methylene blue index as follows:MBI 5E 3 VW3 100where:MBI = methylene blue index for the clay in meq/100 g clay,E = milliequivalents of methylene blue per millilitre(see 5.3),V = millilitres of methylene blue solution required forthe titration, andW = grams o
23、f dry material.7.2 The calculations may be facilitated by using a multipli-cation factor where the specimen size is 2.00 g and themethylene blue titrating solution is 0.01N:MBI 50.01 3 V23 1005 0.5 V7.3 Record the methylene blue index for the clay.8. Precision and Bias8.1 The precision of this test
24、method is the calculatedmethylene blue index (MBI) 6 0.25 meq/100 g clay. The MBIvalue cannot be directly related to any single, simply measured,characteristic of the clay; thus the bias of this test methodcannot be specified.ASTM International takes no position respecting the validity of any patent
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26、 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 Headquarters. Your comment
27、s 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 is copyrighted b
28、y ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 837 99 (2003)2
