1、Designation:D389791(Reapproved 2012)Standard Practice forCalculation of Basicity of Chrome Tanning Liquors1This standard is issued under the fixed designation D3897;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last rev
2、ision.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 practice is intended to show how the results of thechromium analysis(Test Method D3898)and the aciditydetermination(Test Metho
3、d D3913)can be combined to permitcalculation of the basicity of a chrome tanning liquor.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
4、 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:2D3898 Test Method for Chromic Oxide in Basic ChromiumTanning Liqu
5、orsD3913 Test Method for Acidity in Basic Chromium TanningLiquors3.Significance and Use3.1 Basicity is a ratio.In any chromic salt solution,theelectrovalence of the chromium(+3)is satisfied by the hy-droxyl ions and by acid ions.The extent to which thiselectravalence is satisfied by the hydroxyl ion
6、s,expressed as apercentage,is the basicity.The basicity of a chrome tanningliquid is closely related to the tanning behavior of the solution.4.Procedure4.1 Determine the chromic oxide as described in TestMethod D3898.Determine the acid as described in TestMethod D3913.5.Results5.1 The basicity of th
7、e liquor shall be expressed accordingto the Schorlemmer system.In this system,the basicity is theper cent of the total chromic oxide that is combined withhydroxyl and is calculated as follows:Basicity,%5A 2 BA3100(1)where:A=the amount of thiosulfate,as mL of 0.1 N solutionrequired to titrate the 25
8、mL aliquot as the specimen inTest Method D3898,B=the amount of sodium hydroxide,as mL of 0.1 Nsolution required to titrate the 25 mL aliquot of thespecimen in Test Method D3913.6.Precision and Bias6.1 Because basicity is in effect a ratio,the precisionindexes are transmitted by the laws governing ra
9、tios.If theprecision of accuracy of the chromic oxide determination or ofthe titratable acidity is expressed in the same relative units;forexample,percent of value being determined,the precision withwhich the basicity is known will be:PB5=PCR21PA2(2)where:PA=precision of acidity in basic chromium ta
10、nning liquors,PCR=precision of chromic oxide in basic chromium tanningliquors,PB=precision of basicity in basic chromium tanning li-quors.6.2 For the reported reproducibility figures for the chromicoxide from Test Method D3898(d=0.90%)and for acidityfrom Test Method D3913(Procedure I,s=1.84%),dBisgi
11、ven as 2.05%.This number has the units of basicity.Similarly,repeatability has d=0.52%basicity.Caution shouldbe employed in insisting on extremely close agreementsbetween laboratories or replicates unless a background of highprecision has been established.31This practice is under the jurisdiction of
12、ASTM Committee D31 on Leather andis the direct responsibility of Subcommittee D31.06 on Chemical Analysis.Current edition approved April 1,2012.Published April 2012.Originallyapproved in 1991.Last previous edition approved in 2006 as D3897-91(2006).DOI:10.1520/D3897-91R12.2For referenced ASTM standa
13、rds,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.3Hartford,W.H.,The Journal of the Leather Chemists Assoc.,Vol 56,1961,p.568.Copyright ASTM In
14、ternational,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Keywords7.1 basicity;chrome tanning liquor;SchorlemmerASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard.Users
15、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 responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five
16、 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 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 shown below.This standard is
