ASTM_C_837_-_09_2014.pdf

Designation:C83709(Reapproved 2014)Standard Test Method forMethylene Blue Index of Clay1This standard is issued under the fixed designation C837;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 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 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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C324 Test Method for Free Moisture in Ceramic WhitewareClays3.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 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 adsorption).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 defined 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 specific 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 theparticle 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,25 mL.4.6 Medicine Dropper or Glass Stirring Rod.4.7 Filter Paper.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 available.3Other 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 water ofequal purity.5.3 Methylene Blue Solution(1 mL=0.01 meq)3Store indarkness.1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and Related Productsand is the direct responsibility of SubcommitteeC21.04 on Raw Materials.Current edition approved Dec.1,2014.Published December 2014.Originallyapproved in 1976.Last previous edition approved in 2009 as C837 09.DOI:10.1520/C0837-09R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Reagent 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 LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeiaand National Formulary,U.S.Pharmacopeial Convention,Inc.(USPC),Rockville,MD.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 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 C324 and placein the 600-mL beaker.If the clay cannot be tested immediatelyafter drying,it should be stored in a desiccator.6.2 Add 300 mLof 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 2.5 to 3.8.Continue stirring while the pH is being adjusted and continu