1、Designation: E 291 04Standard Test Methods forChemical Analysis of Caustic Soda and Caustic Potash(Sodium Hydroxide and Potassium Hydroxide)1This standard is issued under the fixed designation E 291; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase of revision, 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 These t
3、est methods cover only the analyses usuallyrequired on the following commercial products:1.1.1 Caustic soda (sodium hydroxide), 50 and 73 % li-quors; anhydrous (solid, flake, ground, or powdered), and1.1.2 Caustic potash (potassium hydroxide), 45 % liquor;anhydrous (solid, flake, ground, or powdered
4、).1.2 The analytical procedures appear in the following order:Alkalinity (Total), Titrimetric (for 50 to 100 %NaOH and 45 to 100 % KOH)8to14Carbonate, Gas-Volumetric (0.001 g CO2, min) 15 to 24Carbonate, Gravimetric (0.001 g CO2, min) 25 to 33Chloride, Titrimetric, (0.001 g Cl, min) 34 to 40Chloride
5、, Potentiometric Titration (0.3 to 1.2 %) 41 to 47Chloride, Ion Selective Electrode (0.6 to 120 ppm) 48 to 55Iron, Photometric (0.005 mg Fe, min) 56 to 64Sulfate, Gravimetric, (0.002 g SO3, min) 65 to 71Keywords 721.3 The values stated in inch-pound units are to be regardedas the standard. The value
6、s in parentheses are provided forinformation only.1.4 Review the current Material Safety Data Sheet (MSDS)for detailed information concerning toxicity, first-aid proce-dures, handling, and safety precautions.1.5 This standard does not purport to address all of thesafety concerns, if any, associated
7、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. Specific hazardstatements are given in Section 6.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specifi
8、cation for Reagent WaterE 60 Practice for Analysis of Metals, Ores, and RelatedMaterials for by Molecular Absorption SpectrometryE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial ChemicalsE 200 Practice for Preparation, Standardization, and Stor-age o
9、f Standard and Reagent Solutions for ChemicalAnalysis3. Significance and Use3.1 Caustic soda and caustic potash are used in a largenumber of manufacturing processes. The chemicals are avail-able in several grades depending on their intended use. The testmethods listed in 1.2 provide procedures for a
10、nalyzing causticsoda and caustic potash to determine if they are suitable fortheir intended use.4. Apparatus4.1 Photometers and Photometric PracticePhotometersand photometric practice used in these test methods shallconform to Practice E 60.5. Reagents5.1 Purity of ReagentsUnless otherwise indicated
11、, it isintended that all reagents shall conform to the specifications ofthe Committee on Analytical Reagents of the American Chemi-cal Society, where such specifications are available.3Othergrades may be used, provided it is first ascertained that thereagent is of sufficiently high purity to permit
12、its use withoutlessening the accuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean Type II or Type IIIreagent water conforming to Specification D 1193.1These test methods are under the jurisdiction of ASTM Committee E15 onIndustri
13、al and Specialty Chemicals and are the direct responsibility of Subcommit-tee E15.01 on General Standards.Current edition approved Oct. 1, 2004. Published October 2004. Originallyapproved in 1965. Last previous edition approved in 2001 as E 291 01.2For referenced ASTM standards, visit the ASTM websi
14、te, 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.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For sugge
15、stions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International,
16、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Hazards6.1 Sodium and potassium hydroxides are caustic alkalieswhich, in their anhydrous or strong solution form, are hazard-ous materials. In contact with the skin they produce burnswhich may be quite serious un
17、less promptly treated. Theiraction is insidious since they produce no immediate stinging orburning sensation and damage may result before their presenceis realized.6.2 Eyes are particularly vulnerable to severe damage fromthese alkalies.6.3 Laboratory workers handling these alkalies should usesafety
18、 goggles or face shields and rubber gloves and avoidspillage on clothing. These materials rapidly attack wool andleather.6.4 Spilled caustic should be flushed away with water wherepossible, or covered with absorbent material (such as sawdust,vermiculite, or baking soda) and swept up and discarded in
19、accordance with all applicable federal, state, and local healthand environmental regulations. Last traces may be neutralizedwith dilute acetic acid and the area washed with water.6.5 Perchloric acid is toxic, corrosive, and a strong oxidizer.Laboratory workers handling this acid should use safetygog
20、gles or face shields and rubber gloves.7. Sampling7.1 GeneralThe nature of the caustic alkalies is such as torequire special care at all points of sampling and preparationfor analysis. The following information is included in orderthat representative samples may be ensured. Additional pre-cautions m
21、ay be necessary if trace constituents, not covered inthese test methods, are to be determined. Instructions for suchprocedures may be obtained from the publications of mostmajor producers. Sampling techniques must be such as to limitor prevent atmospheric exposure since sodium and potassiumhydroxide
22、s, both as aqueous solutions and as anhydrousproducts, rapidly absorb moisture and carbon dioxide (andother acid gases) from the atmosphere. The aqueous solutionsare corrosive and sampling devices and sample containers mustbe selected to avoid contamination with any constituent later tobe determined
23、. Strong aqueous solutions of these alkalies areavailable commercially under the names liquid caustic sodaand liquid caustic potash. Liquid caustic potash at a concen-tration of 45 % remains liquid at temperatures down to 20F(29C), and freezing or crystallization will only be encoun-tered under seve
24、re cold weather. Caustic soda liquors areusually shipped in insulated tank cars at elevated temperatures,and minimum temperatures must be maintained if unloadingand sampling problems are to be avoided. Viscosity increasesnear the freezing point and creates pumping problems. Evenpartial freezing chan
25、ges the composition of the remainingliquor and causes sampling and analysis problems. Be surecontents are completely liquid and well mixed before sam-pling. The following minimum temperatures should be main-tained for proper sampling of bulk shipments:50 % NaOH liquor 68F (20C)53 % NaOH liquor 86F (
26、30C)70 to 73 % NaOH liquor 160F (71C)7.2 Sample ContainersThe choice of container construc-tion material is important for caustic liquor samples, especiallyfor those to be taken or held at elevated temperatures. Glasscan be used except where silica is to be determined. Polyeth-ylene or polypropylene
27、 containers which have high-temperature properties may also be used. Nickel is the bestpractical metal for a metallic sample container for causticliquors. For the analysis of 73 % caustic soda, the entire sampleshould be in the liquid state before removing any portion, andsuch portions must then be
28、used in their entirety to avoid thefactor of segregation on freezing. Caustic soda of 73 %concentration may also be “cast” into glass or plastic bottles ortubes, or nickel or silver metallic molds. The molds are laterremoved and the samples chipped or crushed for analysis. Ifthis is done, the factor
29、s of segregation on freezing andatmospheric exposure while crushing must be borne in mind.7.3 Sampling Devices and Techniques:7.3.1 Liquid CausticSimple “dipper” or “tap” samplesfrom large quantity shipments or tanks of caustic liquor areinadequate for purchaser and vendor purposes. Numerousspeciall
30、y designed devices are available to procure samplesfrom various levels in tanks. A useful type of such samplers forsmall tanks has three or five containers mounted on a single rodso that when the device is lowered into a tank and the stoppersare pulled, samples are simultaneously taken at the differ
31、entlevels. These are then combined to provide a representativeaverage sample. Shipments should be sampled at least at theupper, middle, and lower thirds. Samples should never be takenat the surface of the liquid. If it is not necessary to analyze theliquor before unloading, sampling may be accomplis
32、hed by a“continuous drip” from a small tap-off with the regulatingvalve in a vertical section of the unloading line. The “drip” isso timed as to collect the desired amount of sample uniformlyduring the time of unloading.7.3.2 Anhydrous Products:7.3.2.1 Commercial anhydrous caustic soda or caustic po
33、t-ash is packaged in drums in solid, flake, ground, or powderedforms. Sampling and handling of these materials must be donewith minimum atmospheric exposure.7.3.2.2 In the case of flake, ground, or powdered sodium orpotassium hydroxides, the top 3 or 4 in. (75 or 100 mm) ofmaterial in a drum should
34、first be removed and a sample thentaken from the center part of the drum. The sample should beplaced immediately in a suitable wide-mouth container thenclosed and sealed with taps or wax.7.3.2.3 Solid caustic shall be packaged by filling metaldrums with molten anhydrous product and allowing drums an
35、dcontents to cool before sealing air tight. On cooling andsolidifying, impurities present in the caustic tend to segregateand concentrate in the bottom section. To sample such materialproperly, the metal drum must be opened at the vertical seamand removed. The solid cake may then be sampled either b
36、ydrilling at representative levels with a34-in. (19-mm) auger bit(may cause metal contamination) or by splitting the cake inhalf vertically with hammer and chisel and chiseling offrepresentative small fragments so that the total sample repre-sents a vertical cross section through the cake. In either
37、 case,the sample shall be promptly bottled and sealed in a wide-mouth container. In the laboratory, the lumps shall be reducedto convenient size by enclosing in several thicknesses of cleanE291042cloth or kraft paper and pounding with a hammer. The crushedmaterial shall be bottled and thoroughly mix
38、ed before analysis.TOTAL ALKALINITY8. Scope8.1 This test method covers the determination of the totalalkalinity of 50 and 73 % liquid caustic soda, 45 % liquidcaustic potash, and anhydrous caustic soda and caustic potash.9. Summary of Test Method9.1 Total alkalinity is determined by titration with s
39、tandardhydrochloric acid solution using methyl orange indicatorsolution or modified methyl orange indicator solution.10. Reagents10.1 Hydrochloric (or Sulfuric Acid), Special (1.0 N)Prepare in accordance with Practice E 200.10.2 Methyl Orange Indicator SolutionSee PracticeE 200.10.3 Modified Methyl
40、Orange Indicator SolutionSeePractice E 200.10.4 Water, Distilled, carbon dioxide-free (freshly boiledand cooled).11. Procedure11.1 Transfer to a tared, covered weighing bottle a sampleof such size as determined from Table 1.11.2 Weigh the sample to the nearest 1 mg and transfer it toa 1-L volumetric
41、 flask using several rinses of water to removeall traces of caustic from the weighing bottle. Dilute thesolution to about 400 mL with water and cool to roomtemperature. After cooling, dilute to 1 L and mix thoroughly.11.3 With a volumetric pipet, transfer 50 mL (see Note 1) ofthe prepared solution t
42、o a 500-mL Erlenmeyer flask and add 2to 4 drops of modified methyl orange indicator solution (seeNote 2). Titrate this solution with standard 1.0 N acid to a grayend point (see Note 3) and record the volume and temperatureof acid used. Correct the acid normality for any difference fromthe standardiz
43、ation temperature by use of the factor DN/C = 0.00035 between 20 and 30C adding the correction whentemperature of use is below (subtracting when above) thetemperature of standardization. (See Practice E 200.)NOTE 1If a 100-mL buret is to be used for this titration use a 100-mLaliquot.NOTE 2If desire
44、d, methyl orange indicator solution may be used.NOTE 3The analyst should attempt to end the titration at the sameshade of color as was used for the end point in the standardization of theacid.12. Calculation12.1 Calculate the total alkalinity as percent sodium oxideor potassium oxide as follows:Sodi
45、um oxide, wt % 5A 3 B 3 0.030990W3 100 (1)Potassium oxide, wt % 5A 3 B 3 0.047102W3 100 (2)where:A = acid required for titration of the sample, mLB = corrected normality of the acid, andW = weight of sample in the aliquot, g.12.2 Calculate the total alkalinity as the respective hydrox-ide as follows
46、:Sodium hydroxide, wt % 5 1.2907 3 percent Na2O (3)Potassium hydroxide, wt % 5 1.19123 percent K2O (4)12.3 If actual hydroxide content is desired, the carbonatecontent must be determined separately as described in Sections15-24 or Sections 25-33. Then:Sodium hydroxide actual!,wt%5 A 2 B 3 0.755! (5)
47、Potassium hydroxide actual!,wt%5 C 2 D 3 0.812! (6)where:A = percent NaOH (total alkali),B = percent Na2CO3,C = percent KOH (total alkali), andD = percent K2CO3.13. Report13.1 Report the percentage of sodium oxide or potassiumoxide to the nearest 0.01 %.14. Precision and Bias14.1 The following crite
48、ria should be used in judging theacceptability of results (Note 4):14.1.1 Repeatability (Single Analyst)The standard devia-tion for a single determination has been estimated to be0.057 % absolute at 144 DF. The 95 % limit for the differencebetween two such runs is 0.16 % absolute.14.1.2 Laboratory P
49、recision (Within-Laboratory, Between-Days Variability)The standard deviation of results (each theaverage of duplicates), obtained by the same analyst ondifferent days, has been estimated to be 0.17 % absolute at 72df. The 95 % limit for the difference between two suchaverages is 0.48 % absolute.14.1.3 Reproducibility (Multilaboratory)The standard de-viation of results (each the average of duplicates), obtained byanalysts in different laboratories, has been estimated to beTABLE 1 Sample Size for Total AlkalinitySample Sample Size, g50 % NaOH 65 to 7873
