1、Designation: D 2331 08Standard Practices forPreparation and Preliminary Testing of Water-FormedDeposits1This standard is issued under the fixed designation D 2331; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. 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 directions for the preparation ofthe sample for analysis, the preliminary examination of thesample, a
3、nd methods for dissolving the analytical sample orselectively separating constituents of concern.1.2 The general practices given here can be applied toanalysis of samples from a variety of surfaces that are subjectto water-formed deposits. However, the investigator mustresort to individual experienc
4、e and judgement in applying theseprocedures to specific problems.1.3 The practices include the following:SectionsPreparation of the Analytical Sample 8Preliminary Testing of the Analytical Sample 9Dissolving the Analytical Sample 101.4 The values stated in SI units are to be regarded asstandard. No
5、other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, 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-bilit
6、y of regulatory limitations prior to use. For a specificwarning statement, see Note 2.2. Referenced Documents2.1 ASTM Standards:2D 887 Practices for Sampling Water-Formed DepositsD 932 Test Method for Iron Bacteria in Water and Water-Formed DepositsD 933 Practice for Reporting Results of Examination
7、 andAnalysis of Water-Formed DepositsD 934 Practices for Identification of Crystalline Com-pounds in Water-Formed Deposits By X-Ray DiffractionD 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 1245 Practice for Examination of Water-Formed Depositsby Chemical MicroscopyD 233
8、2 Practice for Analysis of Water-Formed Deposits byWavelength-Dispersive X-Ray FluorescenceE11 Specification for Wire Cloth and Sieves for TestingPurposes3. Terminology3.1 For definitions of terms used in these practices, refer toTerminology D 1129.4. Significance and Use4.1 Deposits in piping from
9、aqueous process streams serveas an indicator of fouling, corrosion or scaling. Rapid tech-niques of analysis are useful in identifying the nature of thedeposit so that the reason for deposition can be ascertained.4.2 Possible treatment schemes can be devised to preventdeposition from reoccurring.4.3
10、 Deposits formed from or by water in all its phases maybe further classified as scale, sludge, corrosion products orbiological deposits. The overall composition of a deposit orsome part of a deposit may be determined by chemical orspectrographic analysis; the constituents actually present aschemical
11、 substances may be identified by microscope or X-ray.5. Reagents and Materials5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to specifications of the Committeeon Analytical Reagents of the American Ch
12、emical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.1These practices are under the jurisdiction of ASTM Committee D19 on W
13、aterand 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. Published November 2008. Originallyapproved in 1965
14、. Last previous edition approved in 2003 as D 2331 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 standards Document Summary page onthe ASTM website.
15、3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacope
16、iaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean water tha
17、t meets orexceeds the quantitative specifications for Type I or Type IIreagent water conforming to Specification D 1193, Section 1.1.6. Sampling6.1 Collect and preserve the sample in accordance withPractices D 887.7. Preparation of Analytical Sample7.1 Preliminary ExaminationExamine the sample as co
18、l-lected, using a microscope if available, for structure, color,odor, oily matter, appearance of mother liquor if any, and othercharacteristics of note (for example, attraction to magnet).Record results for future reference.7.1.1 Filtration and other steps in the preparation of theanalytical sample
19、may frequently be bypassed; for example, amoist sample that contains no separated water shall be startedin accordance with 7.3.1, and a dry sample shall be started inaccordance with 7.4, 7.5,or7.6. Partitioning, 7.4, is not alwayspractical or even desirable. Solvent extraction, 7.5, is unnec-essary
20、if the sample contains no oily or greasy matter.7.2 Filtration of Sample (see Note 1)If the sample in-cludes an appreciable quantity of separated water, remove thesolid material by filtration. Save the filtrate, undiluted, pendingdecision as to whether or not its chemical examination isrequired. Tra
21、nsfer all of the solid portion to the filter, using thefiltrate to rinse the sample container if necessary. Air-drying orpartial air-drying of the filter is frequently helpful towardeffecting a clean separation of the deposit.NOTE 1If the sample obviously contains oily matter, its extractionwith a s
22、uitable solvent (see 7.5) is essential before filtration or air-dryingis attempted. Likewise, if the sample is suspected to contain easilyoxidizable materials, such as sulfide, analysis for these materials should becompleted before air-drying.7.3 Air-DryingRemove the drained solid sample from thefil
23、ter, being careful to avoid gross contamination with filterpaper.7.3.1 Air-dry the entire quantity of solid, spread in a thinlayer on a nonreactive, impervious surface.Arecord of the lossof weight during air-drying is often used.7.4 Partitioning the SampleMany samples are obviouslyheterogeneous. If
24、useful to explain the occurrence of thewater-formed deposit, separate clearly defined layers or com-ponents, and approximate the relative percentages.7.4.1 Retain the individual air-dried fractions for separateanalysis, preferably storing over an effective desiccant such asanhydrite.7.5 Solvent Extr
25、actionThis step is essential only if theair-dried sample smears or agglomerates when tested forpulverization (smears caused by graphite are possible but rarewith water-formed deposits).7.5.1 Weigh no more than 10 g of air-dried sample and placethis, wrapped in fine-textured filter paper, in a prepar
26、ed(extracted and dried) Soxhlet thimble. Paper clips are useful forpreventing unfolding of the paper. Weigh the thimble and itscontents and extract in a Soxhlet apparatus until the solvent(chloroform) in the extraction chamber is colorless. Record theloss in weight of the thimble and contents, dried
27、 at 105C, aschloroform-extracted matter. If important to the solution of theproblem, evaporate the solvent, and examine the residue.7.5.2 The extraction may be repeated with other volatileorganic solvents if exploratory tests warrant such procedure.7.6 PulverizingWhether the sample is dry as receive
28、d,air-dried or air-dried extracted, it must be pulverized toadequate homogeneity. Grind the entire sample, or enough of itto be representative of the whole, to pass a No. 100 (150-m)sieve, as specified in Specification E11. Continue the grindinguntil all the material passes through the sieve, except
29、 forfragments such as splinters of fiber, wood, and metal.7.6.1 Identify fragments separated from the sample duringgrinding by standard methods if this information is valuable.7.6.2 Mix the sieved material thoroughly by tumbling in aclosed dry container that is no more than two thirds full.7.6.3 Tra
30、nsfer 5 to 10 g of the thoroughly mixed material toa weighing bottle. This is the analytical sample. Unless thedeterminations are to be made on an air-dried basis, dry at105C and store in a desiccator.8. Preliminary Testing of Analytical Sample8.1 This section outlines methods for the preliminary ex
31、-amination of samples of water-formed deposits. Use one ormore of these methods to disclose the component elements ofthe sample and whether the concentrations are major, minor, ortrace, an essential guide to planning the analysis. This prelimi-nary testing frequently also provides important guidance
32、 to-ward defining technological problems associated with theoccurrence of the deposits. The methods include spectrogra-phy, atomic absorption spectrophotometry, X-ray diffraction,X-ray fluorescence, microscopy, and ordinary qualitativeanalysis.8.2 SpectrographyMake the spectrographic analysis by asu
33、itable method, for example, as outlined in 8.2.2 to 8.2.7.8.2.1 Although superior results are obtainable with a spec-trograph and associated equipment, data of lesser degree ofaccuracy can frequently be obtained with less formal equip-ment such as a visual-arc spectroscope.8.2.2 For best results use
34、 a spectrograph having a suitablereciprocal linear dispersion, associated adjuncts and optics, amicrophotometer for measuring the transmittances of spectra-line images, and associated equipment for determining inten-sity ratios.8.2.3 Mix 50 mg of the pulverized sample, obtained inaccordance with 7.6
35、.2, with 900 mg of graphite powder and250 mg of lithium carbonate. Pack the mixture into graphite-cup electrodes.8.2.4 Record the spectra obtained upon excitation with a d-carc.8.2.5 Measure the transmittances of the analytical andlithium lines (internal standards other than lithium are pre-ferred b
36、y some operators). Determine intensity ratios fromthese data.8.2.6 Use the intensity ratios to estimate concentrationsfrom standard analytical curves.8.2.7 The metallic constituents can frequently be deter-mined within 20 % of their content in the deposit, which issufficiently close for classificati
37、on as major, minor, or trace.D23310828.3 Atomic AbsorptionMake the atomic absorption analy-sis in accordance with appropriate method.8.3.1 The required apparatus shall include an atomizer andburner, suitable pressure-regulating devices, a multielementhollow-cathode lamp (alternatively, a hollow-cath
38、ode lamp foreach metal to be tested), an optical system capable of isolatingthe desired wavelengths of radiation as lines, and adjuncts forobtaining amplified measurements and readout.8.3.2 Prepare standards as in the selected or multiple stan-dards if a multielement is used. Follow the manufacturer
39、srecommendations for instrument start-up and optimization oftest conditions. Calibrate the instrument for each element to bedetermined by aspirating prepared standard solutions andnoting the corresponding instrument read out. Aspirate a blanksolution between each standard to assure instrument stabil
40、ity.Each element absorbs energy from the line source at acharacteristic wavelength which results in a decrease in energynoted at the detector. Record the instrument readings, and plotagainst the occurrence of the absorbing atom in milligrams perlitre of the aspirated solution.8.3.3 Prepare the solub
41、ilized sample (9.2, 9.3,or9.4,depending on the solubility of the water-formed deposit).Using volumetric flasks, make 100 mL each of the twodilutions, 1 + 9 and 1 + 99, by adding enough water to 10 and1 mL of the solubilized sample, respectively.8.3.4 Aspirate the solubilized sample and the two dilut
42、ionsprepared from it, aspirating water before going from onedilution to another. Record the instrument readings for thewavelengths of interest.8.3.5 Determine the concentration of each metal tested ineach dilution of the solubilized sample by referring theabsorbance obtained to a prepared calibratio
43、n curve that relatesthe concentration of prepared standard solutions and theircorresponding absorbances. Alternatively, when direct readoutin terms of concentration is possible, note the concentration ofmetal for each sample aspirated. Correct the sample readingsfor baseline drift or contaminants, o
44、r both, in the reagents usedto solubilize the sample by subtracting the blank reading fromthe sample reading.8.3.6 Calculate the concentration of each element deter-mined in the original sample as follows:Concentration, mg/L 5C 3 FD3 106where:C = concentration of element in the solubilized sample,mg
45、/L,F = dilution of the solubilized test sample, if required, andD = weight of the original deposit sample diluted to a 1-Lvolume, mg.8.3.7 Atomic absorption may be increased or decreased bychemical interferences. For example, calcium absorbance islowered in the presence of phosphate, silica can inte
46、rfere withiron, and aluminum interferes with the determination of mag-nesium. If these constituents are suspected to be present andmore quantitative results are desired, refer to the methodsprovided by the manufacturers of the equipment for suppress-ing these interferences.8.4 X-Ray DiffractionPerfo
47、rm the X-ray diffraction analy-sis in accordance with Practices D 934.8.4.1 The required apparatus shall include a radiationsource, of which more than one may be needed, a camera orother device for sensing or recording radiation intensity, andadjuncts for interpreting the recorded data.8.4.2 Regrind
48、 a portion of the pulverized sample, obtainedin accordance with 7.6.2, to pass a No. 270 (53-m) sieve (oras directed by a specific manufacturer). Mount the powderedmaterial in the shape or form required for the sensing devicethat is used.8.4.3 Record the diffraction pattern on photographic film, ori
49、ts equivalent while the mounted sample is exposed to theX-ray beam for the required interval.8.4.4 The radiation pattern shall be translated into lines andintensities, using the adjuncts available for this purpose, andthese shall be compared with standard diffraction patterns forknown compounds.8.4.5 Identification of a substance is made when sufficientcharacteristic lines of a standard pattern occur in the patternderived from the sample, in essentially the same relativeintensity. However, owing to the poor crystallization charac-teristic of many water-formed deposit
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