ASTM D6851-02(2007)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D 6851– 02 (Reapproved 2007)
Standard Test Method for
Determination of Contact pH with Activated Carbon
This standard is issued under the fixed designation D 6851; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 5. Interferences
1.1 This method is to be used in the determination of the pH 5.1 pH electrodes used to measure this quantity can even-
of water on initial contact with activated carbon. This test tually become clogged over time with carbon fines. Suitable
method is not meant as a replacement for Test Method D 3838 electrodes can be found which have a detachable junction
and may give a different value. allowing the user when necessary to discard a fouled pH
1.2 This standard does not purport to address all of the membrane.
safety concerns, if any, associated with its use. It is the 5.2 Distilled water can become acidic on standing. Make
responsibility of the user of this standard to establish appro- sure that the water used meets the minimum requirements for
priate safety and health practices and to determine the ASTM Type II water. Determine the pH as indicated in Test
applicability of regulatory limitations prior to use. Method D 1293.
2. Referenced Documents 6. Apparatus
2.1 ASTM Standards: 6.1 A pH meter (ambient temperature of 25 °C is assumed;
D 1193 Specification for Reagent Water ifotherwise,temperaturecompensationisrequiredforaccurate
D 1293 Test Methods for pH of Water pH measurement.
D 3838 Test Method for pH of Activated Carbon 6.2 A combination pH electrode, or glass-calomel elec-
E 300 Practice for Sampling Industrial Chemicals trodes used together.
6.3 A 100 mL (TD) graduated cylinder
3. Summary of Test Method
6.4 A 250 mL glass beaker (for each sample)
3.1 A sample of carbon is stirred with water and the pH of
6.5 A polymer-coated magnetic stir bar (for each sample)
the suspension is measured. 6.6 Magnetic stir plate
6.7 A balance capable of accurately measuring to 0.1 g
4. Significance and Use
7. Reagents and Materials
4.1 ThedeterminationofcontactpHcanbeusedasasimple
and fast measurement that can allow activated carbon produc- 7.1 Distilled or de-ionized water that meets theASTM Type
ers and users to have a standard method for assessing the effect
II requirements
various carbons will have on the initial pH of the water in 7.2 Buffers to calibrate the pH meter; typically pH 4.0, pH
contact with the carbon. It has been determined that there is a
7.0, and/or pH 10.0
bias between this method and Test Method D 3838; they are
8. Hazards
not equivalent.
8.1 The water in contact with the carbon may have either a
low or high pH. Take precautions accordingly and wear
This specification is under the jurisdiction of ASTM Committee D28 on
necessary protective equipment to prevent injuries from spills
ActivatedCarbonandisthedirectresponsibilityofSubcommitteeD28.02onLiquid
and splashes.
Phase Evaluation.
Current edition approved Oct. 1, 2007. Published November 2007. Originally
approved in 2002. Last previous edition approved in 2002 as D 6851 – 02.
9. Sampling, Test Specimens, and Test Units
For referenced ASTM standards, visit the ASTM website, w
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