1、Designation: D 6647 01 (Reapproved 2006)Standard Test Method forDetermination of Acid Soluble Iron Via Atomic Absorption1This standard is issued under the fixed designation D 6647; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. 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 test method covers the determination of the acidsoluble iron content of granular and powdered activate
3、dcarbons, using an atomic absorption spectroscopy method bydirect aspiration. Hydrochloric acid is used to extract the iron.This test method is not directly usable to determine the totaliron concentration of a sample.1.2 This standard does not purport to address all of thesafety concerns, if any, as
4、sociated 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 a specifichazard statement, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D 2652 T
5、erminology Relating to Activated CarbonD 1193 Specification for Reagent WaterE11 Specification for Wire Cloth and Sieves for TestingPurposesE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 287 Specification for Laboratory Glass Graduated BuretsE 288 Specification for Labor
6、atory Glass Volumetric FlasksE 300 Practice for Sampling Industrial Chemicals2.2 NIST Publication:Circular 602 Testing of Glass Volumetric Apparatus33. Terminology3.1 DefinitionsTerms relating to this standard are definedin Terminology D 2652.3.1.1 atomic absorptionin flame atomic absorption spec-tr
7、ometry, a sample is aspirated into a flame and atomized. Alight beam is directed through the flame, into a monochroma-tor, and onto a detector that measures the amount of lightabsorbed by the atomized element in the flame. Because eachmetal has its own characteristic absorption wavelength, asource l
8、amp of that element is used. The amount of energy atthe characteristic wavelength absorbed in the flame is propor-tional to the concentration of the element in the sample over alimited concentration range.4. Summary of Test Method4.1 Arepresentative sample of the material to be analyzed iscollected
9、according to E 300. A known weight of the sample isground until 95 % or more of the sample passes 325 mesh. Theground sample is oven dried, and then mixed with a dilutehydrochloric acid. The solution is boiled for 5 minutes toconvert the iron into a soluble chloride, and then cooled andfiltered. The
10、 filter cake is washed with water. Then the filtrateis transferred quantitatively to a beaker. The concentration ofiron in the filtrate is measured by atomic absorption against aset of standards. The acid soluble iron concentration is thencalculated against the weight of the original sample.5. Signi
11、ficance and Use5.1 In certain applications, such as acid purification, acidicfood or chemical purification or decolorization, or otherapplications wherein iron may be leached out of the carbon, theuse of acid-washed carbons will reduce or eliminate colorpickup in the effluent or in the product. The
12、acid soluble ironcontent is usually specified by the carbon supplier to preventunacceptable levels of iron leach occurring.5.2 Detection limits, sensitivity, and optimum ranges willvary with the models of atomic absorption spectrophotometers.General instrumental parameters are as follows:5.2.1 Iron
13、hollow cathode lamp.5.2.2 Wavelength: 248.3 nm.5.2.3 Fuel: acetylene (high purity).5.2.4 Oxidant: air (from compressed air line, laboratorycompressor, or a cylinder of compressed airall need to beclean and dry).5.2.5 Type of flame: oxidizing.5.2.6 The following lines may also be used:248.8 nm Relati
14、ve Sensitivity 2271.9 nm Relative Sensitivity 4302.1 nm Relative Sensitivity 51This test method is under the jurisdiction of ASTM Committee D28 onActivated Carbon and is the direct responsibility of Subcommittee D28.02 on LiquidPhase Evaluation.Current edition approved Oct. 1, 2006. Published Novemb
15、er 2006 Originallyapproved in 2001. Last previous edition approved in 2001 as D 6647 01.2For 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 Summa
16、ry page onthe ASTM website.3Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.252.7 nm Rela
17、tive Sensitivity 6372.0 nm Relative Sensitivity105.3 The method, as written, is intended for carbons havingan acid soluble iron content of 0.0030 to 0.050 % For carbonshaving higher iron contents, larger dilutions or smaller aliquotsmay be used.5.4 The user should validate that there are no interfer
18、encesfrom other metals in the sample matrix.5.5 To prevent erroneous results, the user should ensure thatno iron instruments contact any of the sample or the solutionsused in this procedure. Only glass, ceramics, or plastic shouldbe allowed to contact the sample or solutions.6. Apparatus6.1 Atomic a
19、bsorption spectrometer, consisting of a lightsource emitting the line spectrum of an element (see 5.2.1above), a device for vaporizing the sample (usually a flame), ameans for isolating an absorption line (monochromator or filterand adjustable slitsee 5.2.2 and 5.2.6 above), and a photo-electric det
20、ector with its associated electronic amplifying andmeasuring equipment.6.2 BeakersGriffen, low form, 400 ml., Pyrex or equiva-lent.6.3 CylinderASTM, graduated, 100 ml.6.4 FlaskFiltering, with side tube, 250 ml.6.5 Buchner FunnelSize D, 71 mm. ID.6.6 Filter PaperWhatman No. 3, 7.0 cm. or equivalent.6
21、.7 FlasksVolumetric, 50, 100. 250, 500, and 1000 ml.6.8 PipettesVolumetric, 1,2,5,10,25, and 100 ml.6.9 325 Mesh Screen (U.S. Sieve series).6.10 Analytical Balance, accuracy plus or minus 0.0001 g.6.11 Hot Plate.NOTE 1All volumetric measuring equipment should meet or exceedthe requirements of NIST C
22、ircular 602. Volumetric glassware meetingthose specifications is normally designated as “Class A”. See alsospecifications E 287 and E 288.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to t
23、he specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available. Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determi
24、nation.7.2 Purity of WaterReferences to water shall be under-stood to mean reagent water conforming to specificationD 1193 for Type II reagent water.7.3 Standard Iron Solution ICompletely dissolve 0.1000grams of iron wire, C.P., in 20 ml. of hydrochloric acid,concentrated ACS hydrochloric acid grade
25、, and 50 ml. ofwater. Allow to stand overnight. Quantitatively transfer thesolution into a one liter volumetric flask and dilute to the markwith water. Mix thoroughly. This solution contains 0.1 mg. ofiron per ml.7.4 Standard Iron Solution IIPipette 100.0 ml. of standardiron solution I into a one li
26、ter volumetric flask. Dilute to themark with water. Mix thoroughly. This solution contains 0.01mg. of iron/ml.NOTE 2Commercially available iron solutions obtained from chemi-cal supply houses have been found to be acceptable, provided the accuracyof the solution meets specified requirements.8. Hazar
27、ds8.1 Several potential hazards are associated with conductingthis test procedure. It is not the purpose of this standard toaddress all potential health and safety hazards associated withits use. The user is responsible for establishing appropriatehealth and safety practices and to determine the app
28、licability ofany federal and state regulations before attempting to use thistest method.8.1.1 Since this procedure involves the use of hydrochloricacid, all necessary personal protective equipment for handlingacids should be used, including rubber gloves, lab apron, andgoggles. Careful handling and
29、good laboratory techniqueshould always be used when working with chemicals. Avoidcontact with hydrochloric acid or acid vapor. Care should betaken to prevent burns during handling of various solutionsduring this test procedure.8.1.2 The atomic absorption spectrometer should be ventedappropriately as
30、 recommended by the instrument manufacturerto dissipate fumes and vapors generated by the combustion theflame. This precaution protects laboratory personnel from toxicvapors, protects the instrument from corrosive vapors, andprevents flame stability from being affected by room drafts.8.1.3 The user
31、of this test should comply with all federal,state, and local regulations for safe disposal of all samples andreagents used.9. Sampling9.1 Collect a representative sample of the carbon to betested using Standard Practice E 300. Approximately 10 gramsof if the representative sample will be needed for
32、this test.10. Procedure10.1 Calibration Standards10.1.1 For those instruments which do not read out directlyin concentration, a calibration curve is prepared to cover theappropriate concentration range. Usually, this means the prepa-ration of standards which produce an absorbance of 0.0 to 0.7.Calib
33、ration standards are prepared by diluting the stock metalsolutions at the time of analysis. For best results, calibrationstandards should be prepared fresh each time a batch ofsamples is analyzed.10.1.2 Prepare a blank and several calibration standards asfollows: For the blank, pipette 25.0 ml. of c
34、oncentratedhydrochloric acid into a 250 ml. volumetric flask, and dilute tothe mark with water. Follow sections 10.12-10.16 to determinethe absorbance relative to 0 % acid soluble iron. For thestandards, pipette 1.0, 3.0, 5.0, and 10.0 ml. of Standard IronSolution II, from paragraph 7 above, into se
35、parate 50 ml.volumetric flasks. Repeat sections 10.12-10.16 to determinethe absorbance relative to each level of acid soluble ironmeasured. Plot the absorbance versus milligrams of iron perD 6647 01 (2006)2ml. on linear graph paper. This will give you four points on thecurve, representing 0.0002 mg/
36、ml., 0.0006 mg/ml., 0.001mg/ml., and 0.002 mg/ml. Retain the calibration curve for usein the final report.10.2 This procedure is applicable to either powdered orgranular activated carbon. When granular carbon is to betested, grind approximately 10 grams of the sample until 95 %or more of the sample
37、will pass through a 325 mesh screen (USSieve Series, see Specification E11). Carbon received in thepowder form may need additional grinding to meet the particlesize requirement given above.10.3 Oven dry the sample at 150C for three hours and coolto room temperature in a desiccator.10.4 Weigh 5.0 gra
38、ms of the dried sample to the nearest 0.1mg. and record the weight. This weight represents the sampleweight (SW) used in Section 11.10.5 Quantitatively transfer the sample to a clean 400 ml.beaker.10.6 Carefully add 100.0 ml. of water and 25.0 ml. ofconcentrated hydrochloric acid to the beaker and s
39、wirl thecontents until the carbon is wetted.10.7 Place the beaker on the hotplate and allow to boil for 5minutes. A watch glass placed on top of the beaker will reducewater loss during the 5 minute boil.10.8 Remove the beaker from the hotplate and allow to coolto room temperature.10.9 Filter the sam
40、ple by vacuum through a Buchner funnel,using Whatman No. 3 filter paper, or equivalent. The filtershould be prepared in advance by wetting the paper with water,and having the vacuum on before the sample is added to thefilter.10.10 Wash the carbon retained on the filter paper withseveral 5 ml. portio
41、ns of water.10.11 Quantitatively transfer the filtrate into a 250 ml.volumetric flask, and dilute to the mark with water. Mixthoroughly. If the carbon is suspected of having an acid solubleiron content above 0.03 %, the filtrate may be diluted to 500ml. This volume represents the initial volume (IV)
42、 used in thecalculation below, and should be recorded.10.12 Pipette a 25.0 ml. aliquot of the solution into a 50.0ml. volumetric flask. Dilute to the mark with water and mixthoroughly. This aliquot is the aliquot value (AT) used in thecalculation below, and the volume here represents the finalvolume
43、 value (FV) used in the calculation below. These valuesshould be recorded.10.13 Differences between the various makes and models ofsatisfactory atomic absorption spectrophotometers prevent theformulation of detailed instructions applicable to every instru-ment. The analyst should follow the manufact
44、urers operatinginstructions for a particular instrument. In general, after choos-ing the proper lamp for the analysis per step 5.2 above, allowthe lamp to warm up for a minimum of 15 minutes, unlessoperated in a double beam mode. During this period, align theinstrument, position the monochromator at
45、 the correct wave-length per step 5.2 above, select the proper monochromator slitwidth, and adjust the current according to the manufacturersrecommendation.10.14 Light the flame and regulate the flow of fuel andoxidant. Adjust the burner and nebulizer flow rate for maxi-mum percent absorption and st
46、ability. Balance the photometer.10.15 Aspirate the sample and determine the absorbance.Compare to the calibration curve to determine the concentra-tion of iron in mg./ml. of the diluted sample.10.16 Calculate the concentration of the acid soluble iron in% for the sample by the procedure in step 11 b
47、elow.11. Calculation11.1% Acid Soluble Iron 5C 3 IV 3 FV 3 100SW 3 AT 3 1000(1)where:C = concentration of iron in mg/ml. (section 10.15),IV = initial volume in ml. (section 10.11),FV = final volume in ml. (section 10.12),SW = sample weight in grams (section 10.4),AT = aliquot taken in ml. (section 1
48、0.12),1000 = conversion from g to mg, and100 = conversion decimal to percent.12. Report12.1 In the report of this test, include the values for initialvolume, final volume, aliquot taken, the conditions used for thespectrophotometer, and the calculated result for % acid solubleiron.13. Precision and
49、Bias13.1 This procedure has not been subjected to round-robintesting as yet.14. Keywords14.1 acid soluble iron; activated carbon; atomic absorption;direct aspirationASTM 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 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 t
