ASTM_D_1926_-_00_2011.pdf

Designation:D192600(Reapproved 2011)Standard Test Methods forCarboxyl Content of Cellulose1This standard is issued under the fixed designation D1926;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 These test methods cover the determination of thecarboxyl content,or ion-exchange capacity,of cellulose fromany source.Two test methods are described,the sodiumchloride-sodium bicarbonate method(1)2and the methyleneblue method(2).The test methods must be used within theirlimitations,and it must be recognized that there is no way ofdetermining the accuracy of any method for the determinationof carboxyl.The precision of the sodium chloride-sodiumbicarbonate method is low in the lower range of carboxylvalues.The methylene blue method can be used over the wholerange of carboxyl values;it is especially useful in the lowrange.It is not applicable to the determination of carboxyl insoluble carbohydrate material.Although these test methodsmay be used to determine the ion-exchange capacity ofunbleached pulps,the residual lignin will cause an undeter-mined error,especially the sulfonic acid groups in unbleachedsulfite pulps(3).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:3D1193 Specification for Reagent Water3.Significance and Use3.1 These test methods measure the amount of carboxylgroups present in wood or cotton linter pulp.Carboxyl groupsare indicative of the surface charge of the pulp which is a veryimportant quantity for use in the papermaking industry.4.Purity of Reagents4.1 Reagent-grade chemicals shall be used in all tests.Unless otherwise indicated,it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society,where suchspecifications are available.4Other grades may be used,pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.4.2 Unless otherwise indicated,references to water shall beunderstood to mean reagent water conforming to SpecificationD1193.SODIUM CHLORIDE-SODIUM BICARBONATEMETHOD5.Summary of Test Method5.1 In the sodium chloride-sodium bicarbonate method thespecimen is de-ashed with hydrochloric acid,washed,soakedin sodium chloride-sodium bicarbonate solution,filtered,andan aliquot of the filtrate titrated with 0.01 N hydrochloric acidto a methyl red end point.The difference between the concen-tration of the filtrate and of the sodium chloride-sodiumbicarbonate solution is a measure of the ion-exchange capacityof the cellulose.6.Reagents6.1 Hydrochloric Acid,Standard(0.01 N)Prepare andstandardize a 0.01 N solution of hydrochloric acid(HCl).6.2 Hydrochloric Acid(1+99)Dilute 1 volume of con-centrated HCl(sp gr 1.19)with 99 volumes of water.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings,Materials,and Applications and are the directresponsibility of Subcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved June 1,2011.Published June 2011.Originallyapproved in 1961.Last previous edition approved in 2006 as D1926 00(2006).DOI:10.1520/D1926-00R11.2The boldface numbers in parentheses refer to the list of references at the end ofthese test methods.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.4Reagent 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.3 Methyl Red Indicator Solution.6.4 Sodium Chloride-Sodium Bicarbonate SolutionDissolve 5.85 g of sodium chloride(NaCl)and 0.84 g ofsodium bicarbonate(NaHCO3)in water and dilute to 1 L.6.5 Sodium Hydroxide Solution(0.4 g/L)Dissolve 0.4 g ofsodium hydroxide(NaOH)in water and dilute to 1 L.7.Procedure7.1 Condition the specimen in the atmosphere near thebalance for at least 20 min befo