1、Designation: C 837 09Standard 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 number in parentheses
2、 indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the measurement of the adsorp-tion of methylene blue dye by a clay, which is calculated as amethylene blue index for a clay.1.2 The
3、 values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 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-priat
4、e safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:C 324 Test Method for Free Moisture in Ceramic Whitew-are Clays3. Significance and Use3.1 Tests run on many clays generally indicate that astraight-line rel
5、ationship exists between the methylene blueindex (MBI) and such fundamental clay properties as cationexchange 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 adsorpti
6、on). Where the colloidal portion containssignificant amounts of illite or montmorillonite, the same closecorrelation 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 defin
7、ed as the 0.5- to 0.001-m range), determinesthe strictly colloidal properties of the clay and, together withthe 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 spec
8、ific surface of a clay is a function of the particlesize and morphology and a relationship exists between 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 theparticl
9、e size distribution. This procedure describes the deter-mination of the dye adsorption (in this case, methylene blue) ofa clay.4. Apparatus4.1 Balance, accurate to 0.01 g.4.2 Mixer.4.3 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.
10、 Baroid No. 987.5. Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless 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
11、available.2Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently 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 wa
12、ter ofequal purity.5.3 Methylene Blue Solution (1 mL = 0.01 meq)3Store indarkness.5.4 Sulfuric Acid (0.1N).6. Procedure6.1 Weigh out 2.00 g of clay that has been dried inaccordance with the procedure in Test Method C 324 and placein the 600-mL beaker. If the clay cannot be tested immediatelyafter dr
13、ying, 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.1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and Related Products and is the direct responsibility of Subcom
14、mitteeC21.04 on Raw Materials.Current edition approved Jan. 1, 2009. Published February 2009. Originallyapproved in 1976. Last previous edition approved in 2003 as C 837 99(2003).2Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions o
15、n the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1*A Summary of Changes section appears
16、 at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 Determine the pH of the slurry and add sufficientsulfuric acid to bring the pH within the range from 2.5 to 3.8.Continue stirring while the pH is being a
17、djusted 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 withthe methylene blue solution, add 5 ml of the solu
18、tion 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 by the formation of a light blue haloaround the drop
19、. 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 start after two or even three 5-mL additions havebeen ma
20、de 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 obtained.7. Calculation7.1 Calculate the methylene bl
21、ue 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 of dry material.7.2 The calculations may be facilitate
22、d 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 method is the calculatedmethylene blue index (MBI) 6
23、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.9. Keywords9.1 bond strength; casting rate; cation exchange capacity;clay; colloidal range; MBISUMMARY OF CHANGESCommittee C21
24、has identified the location of selected changes to this standard since the last issue(C 83799 (2003) that may impact the use of this standard.(1) Addition of 1.2, describing the use of units in this testmethod, with renumbering of the subsequent sections of theScope.ASTM International takes no posit
25、ion respecting the validity 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 responsibilit
26、y.This standard is subject 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
27、 International Headquarters. 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 s
28、hown below.This standard is copyrighted by 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).C837092
