ASTM D3838-23

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Designation: D3838 − 05 (Reapproved 2017) D3838 − 23
Standard Test Method for
pH of Activated Carbon
This standard is issued under the fixed designation D3838; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers determination of the pH of a water extract of activated carbon.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 6.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D1293 Test Methods for pH of Water
D2867 Test Methods for Moisture in Activated Carbon
D6851 Test Method for Determination of Contact pH with Activated Carbon
E300 Practice for Sampling Industrial Chemicals
E1272 Specification for Laboratory Glass Graduated Cylinders
3. Summary of Test Method
3.1 An activated carbon sample is boiled in reagent water using a reflux condenser to recycle water vapor. The particles of carbon
are filtered out, the filtrate cooled to 50 °C and the pH of the filtrate determined by electrometic measurement.
4. Significance and Use
4.1 When a fluid containing an adsorbate is passed through a bed of activated carbon, chemical reactions may take place between
the activated carbon, its other noncarbonaceous constituents, and the adsorbate-containing fluid. The pH of the carbon may be a
significant parameter of such a reaction and therefore may be an important characteristic of the carbon.
This test method is under the jurisdiction of ASTM Committee D28 on Activated Carbon and is the direct responsibility of Subcommittee D28.02 on Liquid Phase
Evaluation.
Current edition approved March 1, 2017Dec. 1, 2023. Published March 2017January 2024. Originally approved in 1980. Last previous edition approved in 20112017 as
D3838 – 05 (2011).(2017). DOI: 10.1520/D3838-05R17.10.1520/D3838-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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D3838 − 23
5. Apparatus and Materials
NOTE 1—The graduated cylinder used for measuring must be “Class A,” and should meet or exceed the requirements of Specification E1272.
5.1 Analytical Balance, capacity 100 g, precision 6 0.01 60.01 g.
5.2 Hot Plate.
5.3 Glassware for Boiler-Reflux Condenser Apparatus (Fig. 1)—Items shown are for guidance only, providing a convenient set
of equipment available off-the-shelf from many laboratory supply houses. The “all-glass” elements, with standard-taper and ball
joints, provide freedom from contamination and maintenance. A check valve in the position shown is essential to relieve pressure
buildup while minimizing loss of vapor.
5.4 Thermometer, glass, approximately 0 to 120 °C, long enough subdivision 1 °C, range 0 °C to 120 °C, with sufficient length
to be read at 100 °C when inserted to bottom of Erlenmeyer flask in Fig. 1. ; or equivalent thermometer.
5.5 Thermometer, glass, approximately 20 to 55 °C. subdivision 1 °C, range 20 °C to 55 °C; or equivalent thermometer.
5.6 Graduated Cylinder, 100-mL. 100 mL, Class A.
5.7 Beaker, 200-mL.200 mL.
5.8 Filter Funnel.
5.9 Filter Paper, qualitative, medium flow rate, 12.5 cm or larger in diameter.
FIG. 1 Boiler-Reflux Condenser Apparatus
D3838 − 23
5.10 Timer.
5.11 pH Meter, in accordance with Test Methods D1293, Type II (automatic thermal compensation preferred).
5.12 Reagent Water, in
...