ASTM D6851-02

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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