1、Designation: D 6851 02Standard 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 of last revision.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 me
3、ant 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 user of this standard to establish appro-priate safety and health practices and to determ
4、ine theapplicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 1293 Test Methods for pH of water2D 3838 Test Method for pH of Activated Carbon3E 300 Practice for Sampling Industrial Chemicals43. Summary of Test Method3.1
5、 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 facts measurement that can allow activated carbon produc-ers and users to have a standard method for assessing the effectvarious car
6、bons 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 used to measure this quantity can even-tually become clogged over time with carbon
7、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 meets the minimum requirements forASTM Type II water. Determine the pH as indicated i
8、n 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 elec-trodes used together.6.3 A 100 mL (TD) graduated cylinder6.4 A 250 mL glass beake
9、r (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 meets the ASTM TypeII requirements7.2 Buffers to calibrate the pH meter; typically p
10、H 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 splashes.9. Sampling, Test Specimens, and Test Units9.1 Follow Practice E 300 in the
11、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.1This specification is under the jurisdiction of ASTM Committee D28 onActivated Car
12、bon and is the direct responsibility of Subcommittee D28.02 on LiquidPhase Evaluation.Current edition approved December 10, 2002. Published March 2003.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 15.01.4Annual Book of ASTM Standards, Vol 15.05.1Copyright ASTM Interna
13、tional, 100 Barr Harbor Drive, 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
14、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 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 on
15、e stir bar and stir for ten 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. Calculatio
16、n or Interpretation of Results14.1 No calculatioins are necessary if the meter results arealready temperature corrected.15. Report15.1 Report the value from step 14.6 as the contact pH.16. Precision and Bias16.1 Based on limited information from one laboratory withone sample tested in triplicate, th
17、e repeatability standarddeviations 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
18、 D 3838 and should not be 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
19、 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 years andif not revised, ei
20、ther 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 atten
21、d. 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 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 022
