1、Designation: D 6851 02 (Reapproved 2007)1Standard Test Method forDetermination of Contact pH with Activated Carbon1This standard is issued under the fixed designation D 6851; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 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.1NOTEParagraphs 14.1 and 15.1 were updated editorially in April 2009.1. Scope1.1 This method is to be used in the determinatio
3、n of the pHof water on initial contact with activated carbon. This testmethod is not meant as a replacement for Test Method D 3838and 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 us
4、er of this standard to establish appro-priate safety and health practices and to determine theapplicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 1293 Test Methods for pH of WaterD 3838 Test Method for pH of Activate
5、d CarbonE 300 Practice for Sampling Industrial Chemicals3. Summary of Test Method3.1 A sample 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
6、 produc-ers and users to have a standard method for assessing the effectvarious carbons will have 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 D 3838; they arenot equivalent.5. Interferences5.1 pH electrodes
7、used to measure this quantity can even-tually become clogged over time with carbon fines. Suitableelectrodes 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 me
8、ets the minimum requirements forASTM Type II water. Determine the pH as indicated in TestMethod D 1293.6. 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 ele
9、c-trodes used together.6.3 A 100 mL (TD) graduated cylinder6.4 A 250 mL glass beaker (for each sample)6.5 A polymer-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 m
10、eets the ASTM TypeII requirements7.2 Buffers to calibrate the pH meter; typically pH 4.0, pH7.0, and/or pH 10.08. Hazards8.1 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 sp
11、lashes.9. Sampling, Test Specimens, and Test Units9.1 Follow Practice E 300 in the collection and preparationof samples.10. Preparation of Apparatus10.1 Use the procedure of Test Methods D 1293 to stan-dardize the pH meter before measurement.11. Calibration and Standardization11.1 See above section.
12、1This specification is under the jurisdiction of ASTM Committee D28 onActivated Carbon and is the direct responsibility of Subcommittee D28.02 on LiquidPhase Evaluation.Current edition approved Oct. 1, 2007. Published November 2007. Originallyapproved in 2002. Last previous edition approved in 2002
13、as D 6851 02.2For 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.1Copyright ASTM International, 100 Barr Harbor D
14、rive, PO Box C700, West Conshohocken, PA 19428-2959, United States.12. Conditioning12.1 The sample should be tested 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) w
15、ill 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 should 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 t
16、en minutes with sufficientturbulence to fluidize the sample in the beaker. (Warningtoovigorous stirring should be avoided 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 Re
17、sults14.1 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 standardde
18、viations and the 95 % repeatability limits are:Contact pH (avg. of 3) Standard Deviation 95 % Confidence Limits8.5 0.2 62.35 %16.2 The interlaboratory bias of this method has not beenquantitatively determined, but it has been observed that it is notequivalent to Test Method D 3838 and should not be
19、confusedwith, or meant to replace that method.17. Keywords17.1 activated carbon; contact; pHASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determinatio
20、n 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 years andif not revised, either reapproved or withdra
21、wn. 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 c
22、omments 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 copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 6851 02 (2007)12
