1、Designation:D685102(Reapproved 2011)Standard Test Method forDetermination of Contact pH with Activated Carbon1This standard is issued under the fixed designation D6851;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last
2、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 method is to be used in the determination of the pHof water on initial contact with activated carbon.This testmethod is not
3、 meant as a replacement for Test Method D3838and may give a different value.1.2 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 to determi
4、ne theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1293 Test Methods for pH of WaterD3838 Test Method for pH of Activated CarbonE300 Practice for Sampling Industrial Chemicals3.Summary of Test Method3.1 A sample
5、of carbon is stirred with water and the pH ofthe suspension is measured.4.Significance and Use4.1 The determination of contact pH can be used as a simpleand fast measurement that can allow activated carbon produc-ers and users to have a standard method for assessing the effectvarious carbons will ha
6、ve on the initial pH of the water incontact with the carbon.It has been determined that there is abias between this method and Test Method D3838;they are notequivalent.5.Interferences5.1 pH electrodes used to measure this quantity can even-tually become clogged over time with carbon fines.Suitableel
7、ectrodes can be found which have a detachable junctionallowing the user when necessary to discard a fouled pHmembrane.5.2 Distilled water can become acidic on standing.Makesure that the water used meets the minimum requirements forASTM Type II water.Determine the pH as indicated in TestMethod D1293.
8、6.Apparatus6.1 A pH meter(ambient temperature of 25 C is assumed;if otherwise,temperature compensation is required for accuratepH measurement.6.2 A combination pH electrode,or glass-calomel elec-trodes used together.6.3 A100 mL(TD)graduated cylinder6.4 A250 mL glass beaker(for each sample)6.5 A poly
9、mer-coated magnetic stir bar(for each sample)6.6 Magnetic stir plate6.7 A balance capable of accurately measuring to 0.1 g7.Reagents and Materials7.1 Distilled or de-ionized water that meets theASTM TypeII requirements7.2 Buffers to calibrate the pH meter;typically pH 4.0,pH7.0,and/or pH 10.08.Hazar
10、ds8.1 The water in contact with the carbon may have either alow or high pH.Take precautions accordingly and wearnecessary protective equipment to prevent injuries from spillsand splashes.9.Sampling,Test Specimens,and Test Units9.1 Follow Practice E300 in the collection and preparationof samples.10.P
11、reparation of Apparatus10.1 Use the procedure of Test Methods D1293 to standard-ize the pH meter before measurement.11.Calibration and Standardization11.1 See above section.1This specification is under the jurisdiction of ASTM Committee D28 onActivated Carbon and is the direct responsibility of Subc
12、ommittee D28.02 on LiquidPhase Evaluation.Current edition approved Sept.1,2011.Published November 2011.Originallyapproved in 2002.Last previous edition approved in 2007 as D6851 02(2007).DOI:10.1520/D6851-02R11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Custome
13、r Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 12.Conditioning12.1 The sample should be test
14、ed as received.13.Procedure13.1 A representative sample should be taken from thequantity to be tested and prepared for testing(as received).13.2 Ten(10)grams of sample(as received)will be used forthe test.Place 10 g of a representative sample into a 250 mLbeaker.13.3 The pH of the water to be used s
15、hould be determinedand recorded before use.13.4 Using a graduated cylinder,measure and add 100 mLof water to the ten gram sample in the beaker.13.5 Add one stir bar and stir for ten minutes with sufficientturbulence to fluidize the sample in the beaker.(Warningtoovigorous stirring should be avoided
16、as this may introduce airinto the sample affecting pH.)13.6 Stop stirring,and without delay or filtering,measurethe pH of the suspension.14.Calculation or Interpretation of Results14.1 No calculations are necessary if the meter results arealready temperature corrected.15.Report15.1 Report the value from step 13.6 as the contact pH.16.Precision and Bias16.1 Based on limited information from one laboratory withone sample tested in triplicate,the repeatability standarddeviations and the 95%repeatab