ASTM_D_1993_-_03_2013.pdf

Designation:D199303(Reapproved 2013)Standard Test Method forPrecipitated Silica-Surface Area by Multipoint BET NitrogenAdsorption1This standard is issued under the fixed designation D1993;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.Scope1.1 This test method covers a procedure which is used tomeasure the surface area of precipitated hydrated silicas by theconventional Brunauer,Emmett,and Teller(BET)2theory ofmultilayergasadsorptionbehaviorusingmultipointdeterminations,similar to that used for carbon black in TestMethods D4820.This test method specifies the sample prepa-ration and treatment,instrument calibrations,required accuracyand precision of experimental data,and calculations of thesurface area results from the obtained data.1.2 This test method is used to determine the nitrogensurface area of precipitated silicas with specific surface areas inthe range of 1 to 50 hm2/kg(10 to 500 m2/g).1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 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.The minimumsafety equipment should include protective gloves,sturdy eyeand face protection,and means to deal safely with accidentalmercury spills.2.Referenced Documents2.1 ASTM Standards:3D1799 Practice for Carbon BlackSampling PackagedShipmentsD1900 Practice for Carbon BlackSampling Bulk Ship-mentsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustriesD4820 Test Methods for Carbon BlackSurface Area byMultipoint B.E.T.Nitrogen Adsorption(Withdrawn2000)43.Significance and Use3.1 This test method is used to measure the surface area ofprecipitated,hydrated silicas that is available to the nitrogenmolecule using the multipoint(B.E.T.)method.3.2 Solids adsorb nitrogen and,under specific conditions,the adsorbed molecules approach a monomolecular layer.Thequantity in this hypothetical monomolecular layer is calculatedusing the BET equation.Combining this with the area occupiedby the nitrogen molecule yields the total surface area of thesolid.3.3 This test method measures the estimated quantity ofnitrogen in the monomolecular layer by adsorption at liquidnitrogen temperature and at several(at least five)partialpressures of nitrogen.3.4 Before a surface area determination can be made it isnecessary that the silica be stripped of any material which mayalready be adsorbed on the surface.The stripping of adsorbedforeign material eliminates two potential errors.The first erroris associated with the weight of the foreign material.Thesecond error is associated with the surface area that the foreignmaterial occupies.4.Apparatus4.1 Commercial instruments are available5for the measure-ment of nitrogen surface area by the multipoint BET method.These may be of the“flowing gas”or the“vacuum-volumetric”type.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.20 on Compounding Materialsand Procedures.Current edition approved Nov.1,2013.Published January 2014.Originallyapproved in 1991.Last previous edition approved in 2008 as D1993 03(2008).DOI:10.1520/D1993-03R13.2Brunauer,Emmett,and Teller,Journal of the American Chemical Society,Vol60,1938,p.309.3For 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.4The last approved version of this historical standard is referenced onwww.astm.org.5Commercial automated instruments found satisfactory may be obtained fromMicromeritics Instrument Corporation,One Micromeritics Drive,Norcross,GA300931877,website:,and Quantachrome Instruments,1900 Corporate Drive,Boynton Beach,FL 33426,website:www.quantachrome-.com.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 NOTE1Automated instruments will provide results equivalent to theprocedure described herein if careful calibration of the instrument,equivalent sample preparation,adherence to manufacturers instructionfor instrument operation,and equivalent data handling and calculationsare performed.4.2 Sample Cells,and other peripheral equipment as recom-mended by the manufacturer for the instrument used.4.3 Balance,Analytical,with 0.1-mg sensitivity.4.4 Heating Mantles,or other sample preparation station,capable of maintaining a temperature of 160 6 5