ASTM D3516-1989(2011) Standard Test Methods for Ashing Cellulose《灰分纤维素的标准试验方法》.pdf

1、Designation: D3516 89 (Reapproved 2011)Standard Test Methods forAshing Cellulose1This standard is issued under the fixed designation D3516; 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 pare

2、ntheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover four ashing methods forcellulose. These are intended for use on unbleached andbleached cellulose in sheeted or bulk fiber fo

3、rm. Each one ofthe test methods has advantages, so that preference applica-tions exist for all four.1.2 The test methods appear as follows:SectionsTest Method AAsh in Cellulose at 575C6 to 11Test Method BSulfated Ash in Cellulose at 575C 12 to 17Test Method CAshing Cellulose by Schoniger Oxidation 1

4、8 to 22Test Method DWet Ashing of Cellulose for Inorganics 23 to 291.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It

5、 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 20.6.1.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent Wate

6、rD1348 Test Methods for Moisture in Cellulose3. Summary of Test Methods3.1 Test Method A, Ash in Cellulose at 575CThis testmethod measures the ash content of cellulose, which is definedfor this test as the residue remaining after ignition at 575 625C until all carbon has been burned off. It is the s

7、implest ofthe four test methods for the determination of ash content only,and it should not be considered as a standard preparativeprocedure for elemental analysis.NOTE 1The ash content at this ignition temperature is a reasonablemeasure of the mineral salts and inorganic foreign matter in the cellu

8、lose.The weight of ash obtained varies with the temperature of ignition. Highertemperatures (850C) will convert calcium carbonate and other carbonatesto the oxides and thus give lower values for ash. The composition of ashmay vary with the pulping process employed for manufacture, whichlimits the si

9、gnificance of the ash determination in absolute terms.3.2 Test Method B, Sulfated Ash in Cellulose at 575CInthis ashing procedure the metal salts are converted to sulfatesby treatment with sulfuric acid and ignition at 575 6 25C toovercome limitations of Test Method A. It should not beconsidered as

10、a standard preparative test method for elementalanalysis.NOTE 2Conventional dry ashing at high temperature (over 850C)results in loss of carbon dioxide from metal carbonates, decomposition ofmagnesium sulfate, and loss of sodium salts.Ashing at lower temperatures(575C) gives a better estimate of the

11、 inorganic impurities, but has thedisadvantage of requiring a long ignition time and also the heat producedby the burning pulp can raise the temperature far above 575C for a shortperiod of time, converting calcium carbonate to the oxide in varyingamounts. The sulfated ash method overcomes these obje

12、ctionable featuresand has additional advantages. It is relatively insensitive to ignition time.Ash weight remains constant during weighing, and because the ash doesnot melt it will not attack the crucible.3.3 Test Method C, Ashing Cellulose by SchonigerOxidationThis test method is generally applicab

13、le to ashingcellulose for subsequent analysis of inorganic constituents. Theprocedure utilizes the Schoniger technique in which the cellu-lose is burned in a combustion flask and all combustionproducts are dissolved in an aqueous medium, thus avoidingthe possibility of physical loss of sample such a

14、s can occur indry ashing (Test Methods A and B). A limitation is therelatively small sample of 1 g, which can be ashed withoutexcessively large apparatus in which to carry out the oxidationstep. Small specimens may not be adequately representativewhere a particulate contaminate is involved.3.4 Test

15、Method D, Wet Ashing of Cellulose forInorganicsThis test method is recommended for ashingcellulose for subsequent analysis of inorganic constituents. Theprocedure employs saturation of the cellulose with a concen-trated solution of hydrogen peroxide followed by incrementaladdition to a small volume

16、of concentrated sulfuric acid. It has1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved June 1, 2011. Pu

17、blished June 2011. Originallyapproved in 1976. Last previous edition approved in 2006 as D3516 89 (2006).DOI: 10.1520/D3516-89R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informat

18、ion, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the advantage over Test Method C of not requiring specialapparatus and can be readily applied to samples of 5 to 10

19、g.The test method becomes tedious and less convenient for usewhere larger specimens such as 50 or 100 g are required.Specimens this large, although not generally required, may benecessary for the determination of trace levels of constituentssuch as manganese or silica. Smaller samples may not beadeq

20、uately representative where a particulate contaminate isinvolved.4. Significance and Use4.1 Ash content gives an estimation of the inorganic contentof cellulose samples. The presence of high levels of ash can beexpected to be detrimental to the process of making cellulosederivatives. It also provide

21、s a rough estimate of silica contentwhich can have a significant effect on the performance of filtersin cellulose derivative manufacturing facilities.5. Purity of Reagents5.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents shallconform

22、to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.3Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe det

23、ermination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedin Specification D1193.TEST METHOD AASH IN CELLULOSE AT 575C6. Apparatus6.1 Balance, with an accuracy to 0.05 g is required forweighing cellulose samples.6.2 Analytical Ba

24、lance, with a sensitivity of 0.1 mg isrequired. It should be checked with Class S weights.6.3 Drying Oven, with the capability of maintaining atemperature of 105 6 2C.6.4 Desiccator, such as silica gel, indicating drierite, ormagnesium perchlorate are suitable.6.5 Muffle Furnace, electric, capable o

25、f maintaining a tem-perature of 575 6 25C, is recommended.NOTE 3Back to front temperatures in muffle furnaces frequentlyexceed the 625C range, so that operating limits should be established fora given furnace.6.6 Dish, platinum, 100-mL capacity or larger. Porcelaincrucibles are not recommended.6.7 T

26、ongs, approximately 0.5 m (20 in.) long, with nickel-chromium or platinum tips.7. Test Specimen7.1 The amount of cellulose selected for each ash determi-nation depends on the ash content of the test specimen andshould be varied so that the weight of the ash will be not lessthan 10 mg and preferably

27、over 20 mg. Table 1 gives suggestedsample sizes.7.2 Selection of the specimen shall be in such a manner asto be representative of the lot being tested.NOTE 4No set sampling procedure has been established to beapplicable to all samples. It will suffice to specify that the specimen shallbe representat

28、ive of the lot being sampled.8. Procedure8.1 Weigh out, to the nearest 0.05 g, sufficient cellulose togive the correct range of ash weight (see Table 1). At the sametime, a separate specimen (3 to 5 g) should be weighed anddried at 105C for a moisture determination.NOTE 5Test Methods D1348, Method B

29、 is suitable. However, accu-racy of the moisture test is not critical for the ash determination and anymethod capable of obtaining the percent oven dry within 0.5 % of the truevalue is adequate.8.2 Heat the platinum dish in the muffle furnace at 575Cfor 15 min, cool and weigh to the nearest 0.1 mg.

30、Place theweighed cellulose in the platinum dish and place the dish onthe open door of the muffle furnace, previously set and allowedto reach equilibrium at 575C. Allow the cellulose to charwithout flame by gradually moving the dish into the muffle,and continue ashing with the door closed for 1 h.NOT

31、E 6With some pulps, the character of the ash inhibits completecarbon removal and gray or black specks persist after3hofignition. Theaddition of a few drops of distilled water to the ash after 8.3 followed bydrying and reignition at 575C for1hormore may be required. Extremecases may require a second

32、treatment with water.NOTE 7If the sample is too large, either separate ashings are requiredor successive additions of cellulose are made with extreme care so as notto disturb the ash. 8.2 is then repeated between each addition.8.3 Remove the dish from the muffle furnace and allow tocool somewhat. Pl

33、ace it in the desiccator and allow it to cool toroom temperature.NOTE 8Care must be taken at all times to keep drafts away from thelight, fluffy ash.8.4 Weigh the dish and ash to the nearest 0.1 mg. Reignitefor a 15-min period and reweigh. Repeat as required to obtainconstant weight.9. Calculation9.

34、1 Calculate the ash percent of moisture-free cellulose, E,as follows:3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemi

35、cals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.TABLE 1 Suggested Sample SizesAsh, % Moisture-Free Cellulose, gOver 0.5 50.20 to 0.5 100.12 to 0.2 200.08 to 0.12 300.04 to 0.08 40Less than 0.04 5

36、0D3516 89 (2011)2E 5C 2 B!100!100!A! D!(1)where:A = weight of specimen as is, g,B = weight of dish, g,C = weight of dish plus ash, g, andD = oven dry cellulose in specimen, %10. Report10.1 Report the results to the nearest 0.01 %. Duplicatedeterminations should check within approximately 5 %.11. Pre

37、cision and Bias11.1 Aprecision of 8 % relative at the 95 % confidence levelis found for specimens at the 0.05 % ash level.11.2 No statement of bias can be made as no suitablereference material exists for determining bias.TEST METHOD BSULFATED ASH INCELLULOSE AT 575C12. Apparatus and Reagent12.1 Hot

38、Plate.12.2 Additional apparatus shall be in accordance with Sec-tion 6.12.3 Sulfuric AcidConcentrated H2SO4.13. Test Specimen13.1 The amount of cellulose selected for each ash deter-mination depends upon the sulfated ash content of the testspecimen and should be varied so that the weight of the ashw

39、ill be not less than 10 mg and preferably over 20 mg. Table1 gives suggested specimen sizes for Test Method A. The tableis applicable to sulfated ash also, providing the percent ashcolumn is taken as percent sulfated ash.NOTE 9The sulfated ash values will be higher than the ash obtainedby ignition o

40、f the cellulose without addition of the sulfuric acid. Themagnitude of the difference will depend upon the proportions of differentinorganic salts present, but based on the following conversion factors forthe salts commonly present, will generally be about twice the regular ash:MgSO4MgO5 2.99;CaSO4C

41、aO5 2.43;MgSO4MgCO35 1.43 (2)CaSO4CaSO35 1.36;Na2SO4Na2CO25 1.34 (3)13.2 Selection of the specimen shall be in such a manner asto be representative of the lot being tested (see Note 4).14. Procedure14.1 Weigh out to the nearest 0.05 g sufficient cellulose togive the correct range of ash weight (see

42、Table 1). At the sametime, weigh a separate specimen (3 to 5 g) and dry to constantweight at 105 6 2C for a moisture determination (see Note 5).14.2 See 8.2.14.3 Remove the dish and allow it to cool to room tempera-ture (see Note 7 and Note 8).14.4 Moisten the ash with 1 to 2 mL of concentrated H2SO

43、4and heat on a hot plate until all the dense white fumes of sulfurtrioxide (SO3) are liberated.14.5 Place in the muffle furnace and ignite at 575C for 1 h.If carbon persists repeat 14.3, 14.4, and 14.5.14.6 After the last trace of carbon has disappeared, ignite inthe muffle furnace for1hat575C.14.7

44、Remove the dish and allow it to cool somewhat beforeplacing it in desiccator and cooling to room temperature.14.8 Weigh the dish and sulfated ash to the nearest 0.1 mg.Reignite for a 15-min period and reweigh. Repeat as requiredto obtain constant weight.NOTE 10To remove the ash from the dish, clean

45、with boilinghydrochloric acid.NOTE 11On igniting sulfated ash at 575C, there should be no fusionwith the dishes, even when ashing cellulose that gives an alkaline ash.14.9 Prepare a reagent blank for the H2SO4correspondingto the number of millilitres of H2SO4used in 14.4 and 14.5,bythe addition of t

46、he acid to a platinum dish after ignition andtrue weight was determined, and carrying through 14.4-14.8 asthey apply.15. Calculation15.1 Calculate the sulfated ash, S, as percent of moisture-free cellulose, as follows:S 5C 2 B 2 R!100!100!A! D!(4)where:A = weight of specimen, g,B = weight of dish, g

47、,C = weight of dish plus sulfated ash, g,R = weight of H2SO4reagent blank residue, g, andD = oven-dry cellulose in specimen, %.16. Report16.1 Report the results to the nearest 0.01 %. Duplicatedeterminations should check within approximately 5 %.17. Precision and Bias17.1 A precision of 15 % relativ

48、e is found for specimens inthe 0.1 to 0.3 % ash range.17.2 No statement of bias can be made as no suitablereference material exists for determining bias.TEST METHOD CASHING CELLULOSE BYSCHONIGER OXIDATION18. Apparatus18.1 Combustion Flasks, 5000 mL, round bottom, borosili-cate glass, with 65/40 ball

49、 and joint stopper. The flasks areequipped with perforated platinum specimen carriers sealedinto the extended stem of the flask stopper.18.2 Igniter, suitable for igniting the specimen in the flask.An infrared igniter is preferred.18.3 Specimen Wrappers, black paper.18.4 Pipet, 5 mL.18.5 Volumetric Flask,50mL.D3516 89 (2011)319. Reagents19.1 Deionized Water, high-purity, with a conductivity 1.0mho/cm at 25C.19.2 Absorption Solution0.2 N H2SO4prepared fromconcentrated H2SO4.20. Procedure20.1 By hand, tear a 2- to 3-g air-d