1、Designation: D 934 08Standard Practices forIdentification of Crystalline Compounds in Water-FormedDeposits By X-Ray Diffraction1This standard is issued under the fixed designation D 934; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These practices provide for X-ray diffraction analysis ofpowdered crystalline compounds in water-forme
3、d deposits.Two are given as follows:SectionsPractice ACamera 12 to 21Practice BDiffractometer 22 to 301.2 Both practices yield qualitative identification of crystal-line components of water-formed deposits for which X-raydiffraction data are available or can be obtained. Greaterdifficulty is encount
4、ered in identification when the number ofcrystalline components increases.1.3 Amorphous phases cannot be identified without specialtreatment. Oils, greases, and most organic decompositionproducts are not identifiable.1.4 The sensitivity for a given component varies with acombination of such factors
5、as density, degree of crystalliza-tion, particle size, coincidence of strong lines of componentsand the kind and arrangement of the atoms of the components.Minimum percentages for identification may therefore rangefrom1to40%.1.5 This standard does not purport to address all of thesafety concerns, if
6、 any, associated with its use. It is theresponsibility of the user of this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.Specific precautionary statements are given in Section 8 andNote 20.2. Reference
7、d Documents2.1 ASTM Standards:2D 887 Practices for Sampling Water-Formed DepositsD 933 Practice for Reporting Results of Examination andAnalysis of Water-Formed DepositsD 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2331 Practices for Preparation and Preliminary Testing
8、ofWater-Formed DepositsE11 Specification for Wire Cloth and Sieves for TestingPurposes3. Terminology3.1 For definitions of terms used in these practices, refer toTerminology D 1129.4. Summary of Practices4.1 Powdered samples are irradiated with a monochromaticX-ray beam of short wavelength (from abo
9、ut 0.05 to 0.25 nm).The X rays interact with the atoms in the crystal and arescattered in a unique diffraction pattern which produces afingerprint of the crystals atomic or molecular structure. Theanalytical instrumentation used in X-ray diffraction includesthe powder camera and the diffractometer (
10、1-5).35. Significance and Use5.1 The identification of the crystalline structures in water-formed deposits assists in the determination of the depositsources and mode of deposition. This information may lead tomeasures for the elimination or reduction of the water-formeddeposits.1These practices are
11、 under the jurisdiction of ASTM Committee D19 on Waterand are the direct responsibility of Subcommittee D19.03 on Sampling Water andWater-Formed Deposits, Analysis of Water for Power Generation and Process Use,On-Line Water Analysis, and Surveillance of Water.Current edition approved Oct. 1, 2008. P
12、ublished November 2008. Originallyapproved in 1947. Last previous edition approved in 2003 as D 934 80 (2003).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 st
13、andards Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to the references listed at the end ofthese practices.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Purity of Reagents6.1 Reagent grade
14、chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.4Other grades may be used, pro-vided it is first ascert
15、ained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.6.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean water that meets orexceeds the quantitative specifications for Type I or Type IIreage
16、nt water conforming to Specification D 1193, Section 1.1.7. Sampling7.1 Collect the sample in accordance with Practices D 887.7.2 A suitable amount of sample should be obtained so thatit is representative of the deposit under investigation.7.3 Deposits shall be removed and protected in such a waytha
17、t they remain as nearly as possible in their original states.8. Safety Precautions8.1 The potential danger of high-voltage and X-ray radia-tion makes it mandatory for anyone operating X-ray apparatusto be thoroughly familiar with basic safety precautions.8.2 Place colorful signs displaying the inter
18、national radia-tion symbol near X-ray equipment.8.3 When X-ray equipment is producing radiation, illumi-nate a conspicuous light. There should be no X rays if the bulbburns out. Equipment without this feature can be modified.8.4 Use a portable counter periodically to test for leakage ofX rays from e
19、quipment. Lead or lead glass shielding issometimes needed. X rays of shorter wavelength require morecaution.8.5 Film badges, dosimeters, or other monitoring devicesshall be worn by personnel who regularly work with X-rayequipment.9. Preliminary Testing of Analytical Sample9.1 It may be advantageous
20、and even necessary to performother analytical investigative methods to aid in the rapididentification of crystalline components in water-formed de-posits. For other testing methods refer to Practices D 2331.10. Preparation of Sample10.1 ApparatusThe apparatus used for preparing thesample is as follo
21、ws:10.1.1 Mullite or Agate Mortar.10.1.2 SievesA series of sieves from No. 100 mesh(150-m) to No. 325 mesh (45-m) as specified in Specifica-tion E11.10.1.3 Soxhlet Extractor.10.2 ProcedureThe following procedure is to be used inpreparing the sample:10.2.1 Air-dry moist samples before grinding. If th
22、ere isspecial need to preserve the nature or composition of theoriginal deposit, special handling must be observed. Handledeliquescent deposits in a dry-box atmosphere. Handle samplessubject to oxidation in an inert atmosphere.10.2.2 If samples contain oil or grease, prepare achloroform-insoluble fr
23、action by first drying the specimen for1 h at 105C and then extracting for 2 h using chloroform in aSoxhlet extracting apparatus. Air-dry to remove solvent fromspecimen.10.2.3 Grind the sample in a mullite or agate (mechanical orhand) mortar until approximately 98 % passes a No. 325 mesh(45-m) sieve
24、 (see Note 1). Remove fragments of fiber, wood,and metal. If the specimen is not sufficiently brittle at ordinarytemperatures to be ground to a fine powder or if it is suspectedthat certain crystallites may be plastically deformed during thegrinding, the deposit can be subjected to dry-ice temperatu
25、resand then ground immediately. Grind hydrated samples underalcohol, if indicated, to prevent structural damage.NOTE 1Most materials found in water-formed deposits are suffi-ciently brittle to be reduced to 45 m and this crystallite dimension willgenerally give good identifiable diffraction patterns
26、. However, it may notalways be practical or possible to reduce certain materials to 45 m. Oftengood diffraction results can be obtained from larger crystallite sizes (No.200 mesh (75-m) to No. 270 mesh (53-m). The only practical test forproper grain size is in reproducibility of diffraction line int
27、ensities. Theideal grain size may be in the subsieve range as small as 1 m, butreduction to this size may be impractical.11. Selective Segregation of Analytical Sample11.1 Chemical and Physical Treatment of SamplesDepending on the contents of the sample, it may or may not benecessary to concentrate
28、or segregate components by chemicalor physical treatment (see Note 2). Many crystalline materialsproduce sharp diffraction patterns and they are identifiablewhen present to 1 or 2 % in a mixture. Other substances thatcan be readily identified alone are difficult to detect in mixtureseven when they a
29、re present to the extent of 50%. Separation ofphases by density, acid solubility, or magnetic propertiesfollowed by diffraction analysis of the separated phase(s) mayhelp to identify various deposit components. Separation treat-ment is also helpful in resolving line coincidence in complexmixtures. I
30、f concentration or segregation is not deemed neces-sary, disregard any treatment and proceed in accordance withSection 10. When treatment is necessary, use one or more ofthe following chemical or physical treatments described in 11.2to 11.7. It must be pointed out that the treatments provide noabsol
31、ute separation, but serve only to concentrate or partiallysegregate specific components.NOTE 2It should be emphasized that water-formed deposits oftenoccur in clearly defined layers and that physical separation at the time ofsampling is more advantageous than later treatment.11.2 Water-Insoluble Fra
32、ctionThis treatment removes thewater soluble from the water insoluble components. Solubleconstituents would include most sodium, potassium, andlithium compounds (see Note 3).4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the
33、 testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D93408211.2.1 Weigh 0.5 g or more of sample
34、 that has been groundand passed through a No. 100 mesh (150-m) sieve. Add 100mL of water to a beaker containing the powdered specimen.Heat to boiling and then cool. Allow 30 min of reaction time,filter through a 45-m membrane filter, wash, and air-dry theresidue. Regrind to pass through a No. 325 me
35、sh (45-m)sieve.NOTE 3The filtrate may be evaporated and the residue examined bydiffraction. Although the crystalline structure may have changed from theoriginal sample, it is often helpful in identifying simplified variations ofthe original crystals. Sodium phosphate compounds found dispersed inboil
36、er deposits are often noncrystalline or are so complex that they are noteasily identified. The water soluble residue from these deposits afterevaporation is often more easily identified.11.3 Hydrochloric Acid-Insoluble FractionThis treatmentremoves carbonates, phosphates, and hydroxides. Partial de-
37、composition occurs to some silicates such as serpentine,xonotlite, and analcite. Components such as anhydrite undergoonly partial dissolution.11.3.1 ReagentThe reagent used for this treatment is asfollows:11.3.1.1 Hydrochloric Acid (1 + 6)Mix 1 volume of con-centrated HCl (sp gr 1.19) with 6 volumes
38、 of water.11.3.2 Weigh approximately 0.5 g of the sample that hasbeen ground and passed through a No. 100 mesh (150-m)sieve. Add 100 ml of HCl (1 + 6) to a beaker containing thepowdered specimen. Allow 30 min of reaction time, filterthrough a membrane filter, wash and air-dry the residue.Regrind to
39、pass through a No. 325 mesh (45-m) sieve.11.4 Nitric Acid-Insoluble FractionThis treatment re-moves all the components indicated in 11.3 in addition tocopper and most copper compounds.11.4.1 ReagentThe reagent used for this treatment is asfollows:11.4.1.1 Nitric Acid (1 + 13)Mix 1 volume of concen-t
40、rated HNO3(sp gr 1.42) with 13 volumes of water).11.4.2 Weigh 0.5 g or more of the sample which has beenground and passed through a No. 100 mesh (150-m) sieve.Add 100 ml of HNO3(1 + 13) to a beaker containing thepowdered specimen. Allow 30 min of reaction time, filterthrough a membrane filter, wash
41、and air-dry the residue.Regrind to pass through a No. 325 mesh (45-m) sieve.11.5 Density FractionThis treatment separates com-pounds in water-formed deposits which differ appreciably indensity such as copper oxide and calcite.11.5.1 Weigh 0.5 g or more of sample that has been groundand passed throug
42、h a 100 mesh (150-m) sieve. Add 100 mLof water to a beaker containing the powdered specimen. Stirthe liquid with a mechanical stirrer, but do not use a magneticstirrer (Note 4). The denser particles will settle to the bottomand the less dense particles will remain suspended. Withcontinued stirring,
43、withdraw sufficient liquid and filter througha membrane filter. Varying the speed of the stirrer will put moreor less of the powdered sample into suspension. Air-dry theresidue and regrind to pass through a No. 325 mesh (45-m)sieve.NOTE 4A magnetic stirrer would attract any particle that was mag-net
44、ic and might prevent segregation of particles of different densities.11.6 Magnetic and Nonmagnetic FractionThis treatmentseparates the magnetic components from the nonmagneticcomponents such as magnetite from hydroxyapatite.11.6.1 Weigh 0.5 g or more of sample that has been groundand passed through
45、a No. 325 mesh (45-m) sieve. Add 100mL of water to a beaker containing the powdered specimen.Stir with a mechanical stirrer for several minutes and thenattach a magnet to the outside of the beaker (see Note 4). Whilestirring continues, magnetic components will be attracted to thearea in front of the
46、 magnet, while the nonmagnetic componentswill remain in suspension. After 30 min, pour off the liquidwhile the magnet remains in place and filter. The residueshould be essentially nonmagnetic. Remove the magnet fromthe side of the beaker, rinse the magnetic portion down the sideof the beaker, swirl,
47、 and filter. Air-dry the residues and regrindto pass through a No. 325 mesh (45-m) sieve.11.7 Brittle FractionThis treatment concentrates the morebrittle or friable components from those that are less brittle orless friable such as calcite from silica.11.7.1 ApparatusThe apparatus necessary for this
48、 treat-ment is as follows:11.7.1.1 Electrical Mechanical Sieve Shaker.11.7.2 Weigh 0.5 g or more of sample and hand grind in amullite mortar until the largest particle size is approximately 1mm in diameter. Set up the sieve-shaker apparatus with fourdifferent size sieves; No. 100 mesh (150-m), No. 1
49、40 mesh(105-m), No. 200 mesh (75-m) and No. 325 mesh (45-m).Shake the sample for several minutes and then collect thevarious fractions from each sieve. The most friable portion ofthe deposit should have passed to the bottom-most sieve. Eachfraction may be examined separately after regrinding to pass aNo. 325 mesh (45-m) sieve.PRACTICE ACAMERA12. Scope12.1 This method covers the qualitative X-ray diffractionanalysis of powdered crystalline substances using photographicfilm as the detector. The film-camera technique has theadvantage of
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1