1、Designation: E 291 09Standard 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 () 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. Scope*1.1 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) 15to24Carbonate, Gravimetric (0.001 g CO2,min) 25to33Chloride, Titrimetric, (0.001 g Cl,min) 34to40Chloride, Potenti
5、ometric Titration (0.3 to 1.2 %) 41 to 47Chloride, Ion Selective Electrode (0.6 to 120 g/g) 48 to 55Iron, Photometric (0.005 mg Fe, min) 56 to 64Sulfate, Gravimetric, (0.002 g SO3,min) 65to71Keywords 721.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are
6、 included in thisstandard with the exception of inch-pound units for apparatusdescriptions.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 o
7、f 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-bility of regulatory limitations prior to use. Specific hazardstatements are given in Section 6.2. Referenced Do
8、cuments2.1 ASTM Standards:2D 1193 Specification for Reagent WaterE60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption SpectrometryE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty ChemicalsE 200 Practi
9、ce for Preparation, Standardization, and Stor-age of 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
10、 testmethods listed in 1.2 provide procedures for analyzing 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 E60.5. Reagen
11、ts5.1 Purity of ReagentsUnless otherwise indicated, it isintended that all reagents shall conform to the specifications ofthe Committee onAnalytical Reagents of theAmerican Chemi-cal Society, where such specifications are available.3Othergrades may be used, provided it is first ascertained that ther
12、eagent is of sufficiently high purity to permit 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 t
13、he jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and are the direct responsibility of Subcommit-tee E15.01 on General Standards.Current edition approved April 1, 2009. Published April 2009. Originallyapproved in 1965. Last previous edition approved in 2004 as E 291 04.2For
14、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.3Reagent Chemicals, American Chemical Society Specifications , Ame
15、ricanChemical Society, Washington, DC. For suggestions 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. (US
16、PC), Rockville,MD.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 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
17、 solution form, are hazard-ous materials. In contact with the skin they produce burnswhich may be quite serious unless 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 particula
18、rly vulnerable to severe damage fromthese alkalies.6.3 Laboratory workers handling these alkalies should usesafety 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 wherepossib
19、le, or covered with absorbent material (such as sawdust,vermiculite, or baking soda) and swept up and discarded inaccordance 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 Per
20、chloric acid is toxic, corrosive, and a strong oxidizer.Laboratory workers handling this acid should use safetygoggles 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. T
21、he following information is included in orderthat representative samples may be ensured. Additional pre-cautions may 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 producer
22、s. Sampling techniques must be such as to limitor prevent atmospheric exposure since sodium and potassiumhydroxides, both as aqueous solutions and as anhydrousproducts, rapidly absorb moisture and carbon dioxide (andother acid gases) from the atmosphere. The aqueous solutionsare corrosive and sampli
23、ng devices and sample containers mustbe selected to avoid contamination with any constituent later tobe determined. 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 % rem
24、ains liquid at temperatures down to 29C,and freezing or crystallization will only be encountered undersevere cold weather. Caustic soda liquors are usually shippedin insulated tank cars at elevated temperatures, and minimumtemperatures must be maintained if unloading and samplingproblems are to be a
25、voided. Viscosity increases near thefreezing point and creates pumping problems. Even partialfreezing changes the composition of the remaining liquor andcauses sampling and analysis problems. Be sure contents arecompletely liquid and well mixed before sampling. The fol-lowing minimum temperatures sh
26、ould be maintained for propersampling of bulk shipments:50 % NaOH liquor 20C53 % NaOH liquor 30C70 to 73 % NaOH liquor 71C7.2 Sample ContainersThe choice of container construc-tion material is important for caustic liquor samples, especiallyfor those to be taken or held at elevated temperatures. Gla
27、sscan be used except where silica is to be determined. Polyeth-ylene or polypropylene 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 sampleshou
28、ld be in the liquid state before removing any portion, andsuch portions must then be 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 lat
29、erremoved and the samples chipped or crushed for analysis. Ifthis is done, the factors 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 tank
30、s of caustic liquor areinadequate for purchaser and vendor purposes. Numerousspecially designed devices are available to procure samplesfrom various levels in tanks.Auseful type of such samplers forsmall tanks has three or five containers mounted on a single rodso that when the device is lowered int
31、o a tank and the stoppersare pulled, samples are simultaneously taken at the differentlevels. 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 i
32、t is not necessary to analyze theliquor before unloading, sampling may be accomplished 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 unloadi
33、ng.7.3.2 Anhydrous Products:7.3.2.1 Commercial anhydrous caustic soda or caustic pot-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 orp
34、otassium hydroxides, the top 75 or 100 mm of material in adrum should first be removed and a sample then taken from thecenter part of the drum. The sample should be placed imme-diately in a suitable wide-mouth container then closed andsealed with taps or wax.7.3.2.3 Solid caustic shall be packaged b
35、y filling metaldrums with molten anhydrous product and allowing drums andcontents 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 t
36、he vertical seamand removed. The solid cake may then be sampled either bydrilling at representative levels with a 19-mm auger bit (maycause metal contamination) or by splitting the cake in halfvertically with hammer and chisel and chiseling off represen-tative small fragments so that the total sampl
37、e represents avertical cross section through the cake. In either case, thesample shall be promptly bottled and sealed in a wide-mouthcontainer. In the laboratory, the lumps shall be reduced toconvenient size by enclosing in several thicknesses of cleanE291092cloth or kraft paper and pounding with a
38、hammer. The crushedmaterial shall be bottled and thoroughly mixed 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 Te
39、st Method9.1 Total alkalinity is determined by titration with standardhydrochloric acid solution using methyl orange indicatorsolution or modified methyl orange indicator solution.10. Reagents10.1 Hydrochloric (or Sulfuric Acid), Special (1.0 meq/mL)Prepare in accordance with Practice E 200.10.2 Met
40、hyl Orange Indicator SolutionSee PracticeE 200.10.3 Modified Methyl 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 Wei
41、gh the sample to the nearest 1 mg and transfer it toa 1-L volumetric 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 vol
42、umetric pipet, transfer 50 mL(see Note 1)ofthe prepared solution to 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 meq/mL acid toa gray end point (see Note 3) and record the volume andtemperature of acid
43、 used. Correct the acid meq/mL for anydifference from the standardization temperature by use of thefactor DN/C = 0.00035 between 20 and 30C adding thecorrection when temperature of use is below (subtracting whenabove) the temperature of standardization. (See PracticeE 200.)NOTE 1If a 100-mL buret is
44、 to be used for this titration use a 100-mLaliquot.NOTE 2If desired, 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 al
45、kalinity as % sodium oxide orpotassium oxide as follows:Sodium oxide, % mass 5A 3 B 3 0.030990W3 100 (1)Potassium oxide, % mass 5A 3 B 3 0.047102W3 100 (2)where:A = acid required for titration of the sample, mLB = corrected meq/mL of the acid, andW = mass of sample in the aliquot, g.12.2 Calculate t
46、he total alkalinity as the respective hydrox-ide as follows:Sodium hydroxide, % mass 5 1.2907 3 %mass Na2O (3)Potassium hydroxide, % mass 5 1.1912 3 %mass K2O (4)12.3 If actual hydroxide content is desired, the carbonatecontent must be determined separately as described in Sections15-24 or Sections
47、25-33. Then:Sodium hydroxide actual!, % mass 5 A 2 B 3 0.755! (5)Potassium hydroxide actual!, % mass 5 C 2 D 3 0.812! (6)where:A = % mass NaOH (total alkali),B = % mass Na2CO3,C = % mass KOH (total alkali), andD = % mass K2CO3.13. Report13.1 Report the % mass of sodium oxide or potassium oxideto the
48、 nearest 0.01 %.14. Precision and Bias14.1 The following criteria 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 differen
49、cebetween two such runs is 0.16 % absolute.14.1.2 Laboratory Precision (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
