1、Designation: D 3838 05Standard Test Method forpH of Activated Carbon1This standard is issued under the fixed designation D 3838; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses ind
2、icates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers determination of the pH of awater extract of activated carbon.1.2 This standard does not purport to address all of thesafety concerns,
3、if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Section 6.2. Referenced Documents2.1 ASTM Standards:
4、2D 1193 Specification for Reagent WaterD 1293 Test Methods for pH of WaterD 2867 Test Method for Moisture in Activated CarbonD 6851 Test Method for Determination of Contact pH withActivated CarbonE 300 Practice for Sampling Industrial Chemicals3. Summary of Test Method3.1 An activated carbon sample
5、is boiled in reagent waterusing a reflux condenser to recycle water vapor. The particlesof carbon are filtered out, the filtrate cooled to 50C and the pHof the filtrate determined by electrometic measurement.4. Significance and Use4.1 When a fluid containing an adsorbate is passed througha bed of ac
6、tivated carbon, chemical reactions may take placebetween the activated carbon, its other noncarbonaceous con-stituents, and the adsorbate containing fluid. The pH of thecarbon may be a significant parameter of such a reaction andtherefore may be an important characteristic of the carbon.5. Apparatus
7、 and Materials5.1 Analytical Balance, capacity 100 g, precision 6 0.01 g.5.2 Hot Plate.5.3 Glassware for Boiler-Reflux Condenser Apparatus (Fig.1)Items shown are for guidance only, providing a convenientset of equipment available off-the-shelf from many laboratorysupply houses. The “all-glass” eleme
8、nts, with standard-taperand ball joints, provide freedom from contamination andmaintenance. A check valve in the position shown is essentialto relieve pressure buildup while minimizing loss of vapor.5.4 Thermometer, glass, approximately 0 to 120C, longenough to be read at 100C when inserted to botto
9、m ofErlenmeyer flask in Fig. 1.5.5 Thermometer, glass, approximately 20 to 55C.5.6 Graduated Cylinder, 100-mL.5.7 Beaker, 200-mL.5.8 Filter Funnel.5.9 Filter Paper, qualitative, medium flow rate, 12.5 cm orlarger in diameter.5.10 Timer.5.11 pH Meter, in accordance with Test Methods D 1293,Type II (a
10、utomatic thermal compensation preferred).5.12 Reagent Water, in accordance with SpecificationD 1193, Type II.6. Hazards6.1 The test method involves transfer of boiling waterbetween containers; appropriate tongs or gloves should beused. In addition, the use of an electric hot plate and pH meter(if li
11、ne-powered) poses a shock hazard. This equipment mustbe grounded and insulated in accordance with UL standardsand electrical codes.7. Sampling7.1 Guidance in sampling activated carbon is given inPractice E 300.8. Calibration and Standardization8.1 Use the procedure of Test Methods D 1293 to standard
12、-ize the pH meter.9. Procedure9.1 Determine the moisture content of the carbon in accor-dance with Test Method D 2867. Calculate the weight of moistcarbon equivalent to 10 g on a dry basis.9.2 Weigh out a sample of carbon equivalent to 10.00 60.01 g on a dry basis. Remove boiler flask from apparatus
13、 andadd carbon sample.1This test method is under the jurisdiction of ASTM Committee D28 onActivated Carbon and is the direct responsibility of Subcommittee D28.04 on GasPhase Evaluation Tests.Current edition approved April 1, 2005. Published April 2005. Originallyapproved in 1980. Last previous edit
14、ion approved in 1999 as D 3838 80 (1999).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 Inte
15、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.9.3 Bring approximately 110 mL of reagent water to agentle boil. Measure 100.0 6 0.1 mL in graduated cylinderwhile water is hot. Immediately add this water to the carbon inthe flask. Reconnect joints to fl
16、ask seated on hot plate.9.4 Bring water in flask to a boil, using thermometer readingto assure that no false boiling, due to gases trapped in carbon,occurs.9.5 Boil gently for 900 6 10 s.9.6 Remove the flask from the hot plate and filter itscontents immediately through the filter paper premoistenedw
17、ith the distilled water used for the test. Catch the filtrate in a500-mL vacuum filter flask, being careful to prevent carbon-fines from overrunning into the flask.9.7 Cool the filtrate to 50 6 5C.9.8 Measure pH as described in Test Methods D 1293.10. Calculation10.1 If the pH meter is calibrated in
18、 pH units, read valuefrom pH meter. If the meter reading is in voltage units, use theequation from the Terminology section of Test MethodsD 1293.11. Report11.1 Report the following information:11.1.1 Source of sample,11.1.2 Type or designation of activated carbon,11.1.3 Supplier name,11.1.4 Supplier
19、 grade designation,11.1.5 Supplier lot and batch number,11.1.6 Moisture content in accordance with Test MethodD 2867,11.1.7 pH to the nearest 0.1 unit,11.1.8 Temperature of measurement to the nearest 1C,11.1.9 Date of test,11.1.10 Name and signature of technician performing test,and11.1.11 Name and
20、signature of supervisor approving test.12. Precision and Bias12.1 An interlaboratory comparison of the pH of four typesof activated carbons using essentially the above procedure wascarried out by four laboratories (see Test Method D 6851). Theresults were as follows:Sample Number of Tests Average pH
21、 Standard Deviation2N 11 3.65 0.1811N 12 3.64 0.1912N 11 3.56 0.141D 11 5.57 0.674D 12 5.62 0.609D 12 5.65 0.603B 11 8.82 0.385B 12 8.93 0.3010B 12 8.90 0.296P 11 7.91 0.177P 12 8.07 0.418P 12 7.85 0.2312.2 The measured pH values are in agreement with theactivated carbon types (N, wood-base; D, lign
22、ite; B and P,bone-char). The standard deviations also appear in agreementwith other work, in that they are higher for neutral conditions(near pH 7) than for strongly acidic or basic conditions. Someof the observed variation is in the samples themselves. Astandard deviation of 0.6 for pH values near
23、7 and 0.3 forvalues at the ends of the pH scale appears readily achievable bythis test method.ASTM 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 determinat
24、ion 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 withd
25、rawn. 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
26、 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).FIG. 1 Boiler-Reflux Condenser ApparatusD3838052
