ASTM_D_3872_-_05_2011.pdf

Designation:D387205(Reapproved 2011)Standard Test Method forFerrous Iron in Iron Oxides1This standard is issued under the fixed designation D3872;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 the quantitative determinationof ferrous oxide(FeO)by oxidation of ferrous iron(Fe+)in anacid solution to the ferric state(Fe+)and titration withpotassium dichromate using diphenylamine as the indicator.1.2 This test method is applicable to synthetic black ironoxide,natural black iron oxide,magnetite or brown iron oxidewhere part of the iron content is present in the ferrous state(Note 1).It is applicable to iron oxides where the ferrous ironcontent ranges from 50 to 0.20%.NOTE1Natural iron oxides and magnetite may contain traces ofmetallic iron that will be combined with and analyzed as FeO.1.3 This standard does not purport to address the safetyconcerns if any,problems 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:2D50 Test Methods for ChemicalAnalysis of Yellow,Orange,Red,and Brown Pigments Containing Iron and Manga-neseD280 Test Methods for Hygroscopic Moisture(and OtherMatter Volatile Under the Test Conditions)in PigmentsD769 Specification for Black Synthetic Iron OxideD1193 Specification for Reagent WaterD3722 Specification for Natural Red and Brown Iron OxidePigmentsD3724 Specification for Synthetic Brown Iron Oxide Pig-ment3.Significance and Use3.1 This test method may be used for production qualitycontrol or specification acceptance.4.Apparatus4.1 The digestion apparatus consists of a standard 500-mLErlenmeyer flask fitted with a two-hole rubber stopper andglass tubing,as shown in Fig.1,to provide for the introductionof the inert gas and vent for gas and digestion fumes.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 Type II of SpecificationD1193.5.3 Diphenylamine IndicatorDissolve 1 g of diphenylam-ine in 100 mL of concentrated(H2SO4)(sp gr 1.84).5.4 Hydrochloric Acid(1+1)Dilute concentrated hydro-chloric acid(HCl,sp gr 1.19)with an equal volume of reagentwater.5.5 Iron Ore,Standard,Sibley No.27-f.45.6 Potassium Dichromate,Standard Solution(0.1 N)Dissolve 4.904 g of K2Cr2O7in water and dilute to 1 L.Standardize against National Institute of Standards and Tech-nology standard sample No.27f of Sibley iron ore.Calculatethe Fe factor in grams per millilitre for the solution as:1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.31 on Pigment Specifications.Current edition approved June 1,2011.Published June 2011.Originallyapproved in 1979.Last previous edition approved in 2005 as D3872 05.DOI:10.1520/D3872-05R11.2For 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.4May be secured from National Institute of Standards and Technology,Depart-ment of Commerce,Washington,DC 20234.Other recognized primary ironstandard may be substituted.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 Fe5 W/V1(1)where:W=weight of Fe in the standard iron ore(not the solution,as there is none),andVV1=K2Cr2O7required for titration of standard,mL.5.7 Sulfuric-Phosphoric Acid SolutionPrepare by care-fully adding 600 mL of concentrated sulfuric acid(H2SO4)(spgr 1.84)to 800 mL of water while stirring,then add 600 mL ofphosphoric acid(85 to 87%)mixing thoroughly.Cool andstore.6.Preparation of Sample(Note 2)6.1 Mix the sample thoroughly and take a representa