1、Designation: D 6407 99 (Reapproved 2004)Standard Test Method forAnalysis of Iron and Copper in Vegetable Tanning Materials1This standard is issued under the fixed designation D 6407; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、the 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 is intended for use in determining ironand copper content in vegetable tanning materials
3、. This testmethod is applicable to liquid, solid, pasty and powderedextracts, to raw and spent materials, and to tannery liquors.1.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its us
4、e. 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.2. Referenced Documents2.1 ASTM Standards:2D 4901 Practice for Preparation of Solution of Liquid Veg-etable Tannin Ext
5、ractsD 4902 Test Method for Evaporation and Drying of Ana-lytical SolutionsD 4905 Practice for Preparation of Solution of Solid, Pasty,and Powdered Vegetable Tannin ExtractsD 6404 Practice for Sampling of Vegetable Materials Con-taining TanninD 6405 Practice for Extraction of Tannins from Raw andSpe
6、nt Materials2.2 ALCA Methods:A31 Method for Copper and Iron in Tanning Materials33. Summary of Test Method3.1 A specified quantity of the tanning material is analyzedfor iron and copper and content.4. Significance and Use4.1 This test method is used to determine the quantity ofiron and copper presen
7、t in vegetable tanning materials orvegetable tannin extracts prepared using Practices D 4901,D 6404,orD 6405.4.2 Because of the possibility of errors in this test method itis essential that the method be followed exactly in order toobtain reproducible results both among specimens within alaboratory
8、and for analyses between laboratories.5. Apparatus and Reagents5.1 Sulfuric Acid, concentrated (96 %).5.2 Sulfuric Acid Solution, diluted 1:20 with distilled water.5.3 Nitric Acid, fuming.5.4 Hydrochloric Acid, concentrated (36 %).5.5 Hydrochloric Acid Solution, 0.1 N.5.6 Bromine Water, saturated so
9、lution.5.7 Ammonium Hydroxide Solution, concentrated diluted1:1 with distilled water.5.8 Potassium Permanganate Solution, 0.1 N.5.9 Potassium (or Ammonium) Thiocyanate Solution,10gshall be dissolved in distilled water and diluted to 100 mL withdistilled water.5.10 Stock Iron Solution, This may be a
10、purchased ironstandard solution or may be prepared as follows:5.10.1 0.70 g of crystallized ferrous ammonium sulfateFeSO4(NH4)2SO46H2O shall be dissolved in 50 mL ofdistilled water and 20 mL of dilute sulfuric acid (diluted 1:4).5.10.2 This solution shall be titrated with 0.1 N potassiumpermanganate
11、 solution until a faint pink persists for 1 minuteand the iron is completely oxidized.5.10.3 Dilute this solution to 1 L with distilled water. 1 mLof this solution is equivalent to 0.0001 g Fe. This solution shallbe stored in brown bottles and be protected from light.5.10.4 Standard Iron Solution, 1
12、0 mL of the prepared stocksolution, or its equivalent of purchased iron standard solution,shall be diluted to 100 mL with distilled water. 1 mL of thisstandard solution is equivalent to 0.00001 g Fe. The standardsolution shall be freshly prepared for each analysis.5.11 Stock Copper Solution, 3.9283
13、g of copper sulfatecrystals (CuSO45H2O) shall be dissolved in distilled waterand diluted to 1 L with distilled water. 1 mL of this solution isequivalent to 0.001 g Cu.1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.01 o
14、n Vegetable Leather. Thistest method has been adapted from and is a replacement for Method A31 of theOfficial Methods of the American Leather Chemists Association.Current edition approved April 1, 2004. Published May 2004. Originallyapproved in 1999. Last previous edition approved in 1999 as D 6407
15、99.2For 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.3Official Methods of the American Leather Chemists Associa
16、tion. Availablefrom the American Leather Chemists Association, University of Cincinnati, P.O.Box 210014, Cincinnati, OH 45221-0014.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.11.1 Standard Copper Solution, 10 mL of the stock co
17、ppersolution shall be diluted to 1 L with distilled water and the pHadjusted to between 5.5 and 6.0. 1 mL of this standard solutionis equivalent to 0.00001 g Cu. The standard solution shall befreshly prepared for each analysis.5.12 Xanthate Solution, 1.0 g of potassium ethyl xanthateshall be dissolv
18、ed in distilled water and diluted to 1 L withdistilled water. The solution shall be freshly prepared for eachanalysis.5.13 Matched Nessler Tubes and Supporting Rack.5.14 Balance, analytical balance which will weigh up to 100g with an accuracy of 6 0.1 mg (6 0.0001 g).5.15 Drying Oven, a forced-air c
19、onvection oven (ormechanical-convection draft oven) capable of maintaining atemperature of 100 6 2.0C.5.16 Thermometer, accurate to 6 0.2C used to check andmonitor the oven set point.5.17 Dessicator, any convenient form or size, using anynormal desiccant.5.18 Glazed, Porcelain Dish or Crucible of Su
20、itable Size.5.19 Muffle Furnace, capable of maintaining a temperatureof 600 6 25C.5.20 Hotplate, ordinary lab grade.5.21 Steam Bath, ordinary lab grade.5.22 Volumetric Flasks, 200 and 250 mL capacity.5.23 Beakers, 250 mL.5.24 Filter Paper, quantitative, Whatman grade 40 or 52 orsimilar.5.25 Buret, 1
21、0 mL capacity is sufficient.6. Test Specimen6.1 The sample of material from which the test specimensare taken shall be prepared as described in Practice D 6404 forextracts and tannery liquor and as in the Preparation of Samplesection of Practice D 6405 for raw and spent materials.6.2 The specimen sh
22、all consist of5gofsolid extract or itsequivalent (that is 10 g of liquid extract; 25 to 50 g of tanneryliquor;5gofraworspent materials).7. General Instructions7.1 The distilled water shall be distilled from a glass,tin-lined, or block tin still and shall be stored in glass, tin-lined,or block tin co
23、ntainers.7.2 All apparatus used in this analysis shall be cleaned withhot hydrochloric acid solution (diluted 1 to 1) and rinsed withdistilled water before use.7.3 Blank determinations shall be made to minimize errorsdue to iron or copper either present in the reagents used orpicked up during the an
24、alysis.7.4 Duplicate determinations are recommended wheneverpossible.7.5 In the actual colorimetric determinations described be-low, the indicated volumes of reagents, and of the preparedsolutions of the specimens and of standards, are based on theuse 50 mL tall-form Nessler tubes. Other tube volume
25、s andforms may be used, provided: they be used in matched sets andthe volumes of reagents, specimen and standard solutions beadjusted so that similar color intensities are produced. Suchadjustments are automatic with, and familiar to, the experi-enced analyst and are not precluded by the method. If,
26、however, the analyst is in doubt as to the proper adjustment tobe made, it is recommended that 50 mL tall-form tubes be usedexactly as described.7.6 Comparison of the colors developed in the Nessler tubesshall be made under a source of daylight from the north, thetubes being held vertically two inch
27、es above an inclined sheetof white paper, and viewed downward through the full depth ofliquid.8. Procedure8.1 Transfer the specimen to a tared, glazed, porcelain dishor crucible of suitable size, taking care to avoid changes inmoisture content, and weigh to the nearest 0.1 mg (0.0001 g).Where necess
28、ary, place the dish and specimen in the oven andevaporate to dryness (Test Method D 4902).8.2 Ignite the dish containing the dried residue gently overa low flame, at as low a temperature as possible, until theresidue is thoroughly charred and all smoke driven off. Thenplace the dish and charred resi
29、due in a muffle furnace and ash,at a temperature not exceeding 600C, until all carbon has beenremoved.NOTE 1Occasionally, the specimen will be of such a nature that all thecarbon cannot be removed as described above. In such a case, saturate thecharred mass with hot distilled water and break it up a
30、s completely aspossible with a glass rod. Then add more of the hot distilled water anddigest the whole on the steam bath for a few minutes. Decant thesupernatant through a quantitative filter paper, collect the filtrate in asuitable receiver. Digest the charred residue twice more with hot distilledw
31、ater, decant the supernatant through the same filter each time, andcombine the filtrates. Finally transfer the char to the filter and wash severaltimes with hot distilled water, the washings being combined with thefiltrates. Then replace the filter and residue in the original dish, dry, andash the w
32、hole, as before, until all the carbon has been removed. Cool thedish, quantitatively transfer the combined filtrates and washings theretoand evaporate and dry. Then place the dish and contents in a cold mufflefurnace, raise the temperature, slowly at first to avoid loss by spurting, andfinally bring
33、 to a value not exceeding 600C.8.3 Cool the carbon-free ash, moisten with hot distilledwater, 5 mL of concentrated hydrochloric acid added, and heatthe mixture on the steam bath until the ash is dissolved. Addthe five drops of fuming nitric acid and five drops of brominewater and heat the mixture on
34、 the steam bath, gently at firstuntil evolution of gas ceases (use fume cupboard or hood), andfinally evaporate to dryness. Then moisten the residue withdistilled water, 5 mL of concentrated hydrochloric acid added,the mixture digested on the steam bath for a few minutes andfinally transfer, quantit
35、atively, into a 250 mL beaker.Adjust thevolume to about 75 mL by boiling if necessary. Then make thesolution faintly ammoniacal with ammonium hydroxide solu-tion (diluted 1 to 1) and boil gently to remove excess ammoniaand to coagulate the precipitated iron and aluminum hydrox-ides.8.4 Then allow th
36、e mixture to stand on the hotplate, for afew minutes, until the precipitate has settled. As soon aspossible thereafter, decant the hot supernatant through asuitable filter paper except when copper is to be determined, inwhich case use an asbestos-gooch filter (previously washedwith hot, 1:1 hydrochl
37、oric acid, distilled water, 1:1 ammoniumhydroxide, and distilled water) (ammoniacal copper solutionsD 6407 99 (2004)2combine with cellulose). Wash the precipitate three times, bydecantation, with hot, faintly ammoniacal, distilled water (fivedrops 1:1 ammonium hydroxide solution per liter of distill
38、edwater). Finally, quantitatively transfer the precipitate to thefilter and wash four times with the hot, faintly ammoniacaldistilled water. Reserve the residue on the filter for thedetermination of iron (8.5), and the combined filtrate andwashings reserved for determination of copper (8.6).8.5 Dete
39、rmination of Iron:8.5.1 Dissolve the residue on the filter by running onto ittwo portions of 1:20 sulfuric acid solution, of 20 mL each,collecting the solution in a suitable receiver. Then thoroughlywash the filter, four times, with 1:20 sulfuric acid solution, thewashings being added to the first 4
40、0 mL. Quantitativelytransfer the combined acid solution and washings to a suitablevolumetric flask (usually 200 mL is adequate), cool if neces-sary, and bring to the mark with 1:20 sulfuric acid solution.Make a quantitative test of this solution as a guide to the propersize of aliquot required in th
41、e quantitative determination below.8.5.2 Add to the known aliquot of the above solution in aNessler tube, sufficient 1:20 sulfuric acid solution to bring to avolume of 35 mL, two drops of 0.1 N potassium permanganatesolution, and mix the contents of the tube and then allow tostand for 5 min, add mor
42、e permanganate solution, if necessary,until a slight pink persists. (Where several specimens are beingexamined, prepare all the specimen tubes, as above, at the sametime.)8.5.3 Prepare a series of standard Nessler tubes similarly,containing 0.5 to 1.5 mL of standard iron solution in incre-ments of 0
43、.1 or 0.2 mL, add the iron solution from a buret. Mixthe contents of the tubes and then allow to stand for 5 min, addmore permanganate solution, if necessary, until a slight pinkpersists.8.5.4 If the color of the specimen tube be outside the rangeof the standards, repeat the comparison with fresh st
44、andardsand an aliquot of more suitable size from the solution preparedin 8.5.1.8.6 Determination of Copper:8.6.1 Adjust the pH of the combined ammoniacal filtrateand washings from 8.4 to between 5.5 and 6.0 by carefuladdition of 1.0 N hydrochloric acid. Then quantitativelytransfer the pH adjusted so
45、lution to a suitable volumetric flask(250 mL is usually adequate), cool if necessary, and bring tovolume with distilled water.8.6.2 Prepare a series of standard Nessler tubes containing 0to 4 mL of standard copper solution in 0.5 mL increments, addthe copper solution from a buret. To each standard t
46、ube, add 10mL xanthate solution and sufficient distilled water to bring tovolume. Then thoroughly mix the contents of the tubes byinverting several times.8.6.3 Add to another Nessler tube a known aliquot of thesolution prepared as in 8.6.1, followed by 10 mL of xanthatesolution and sufficient distil
47、led water to bring to volume.Thoroughly mix the contents of the tube by inverting severaltimes, and compare the color with that of the standards. Makethe comparison within 15 min of the addition of xanthate to thespecimen and standard tubes. Record the volume of standardcopper solution in that stand
48、ard whose color most closelymatches that of the specimen tube. (With care, the color can beestimated to the equivalent of 0.25 mL of standard coppersolution.)8.6.4 If the color of the specimen tube be deeper than that ofthe 4.0 mL standard, repeat the comparison using a lesseraliquot.9. Results9.1 I
49、ron:9.1.1 Calculate iron content as follows:iron %!5 MB! 3 V/1000 3 Q 3 W (1)where:M = mL of standard iron solution in the matching standard,B = mL of standard iron solution matching the Q mL of theblank,V = capacity of the volumetric flask used in 8.5.1 (usually200 mL),Q = aliquot (mL) taken in 8.5.2, andW = g of specimen taken in 8.1.9.1.2 Instead of the visual color comparison, the use of astandard photometer shall be permissible, provided the calibra-tion curve be established on standards made up following theprocedures in 8.5.2 and 8.5.3. (It is advisable to r
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