ASTM D1067-2011 Standard Test Methods for Acidity or Alkalinity of Water《测定水酸碱性的标准测试方法》.pdf

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1、Designation:D106706 Designation: D1067 11An American National StandardStandard Test Methods forAcidity or Alkalinity of Water1This standard is issued under the fixed designation D1067; 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 () 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 test methods2cov

3、er the determination of acidity or alkalinity of all types of water. Three test methods are given asfollows:SectionsTest Method A (Electrometric Titration) 7to15Test Method B (Electrometric or Color-Change Titration) 16 to 24Test Method C (Color-Change Titration After HydrogenPeroxide Oxidation and

4、Boiling)25 to 331.2 In all of these test methods the hydrogen or hydroxyl ions present in water by virtue of the dissociation or hydrolysis of itssolutes, or both, are neutralized by titration with standard alkali (acidity) or acid (alkalinity). Of the three procedures, Test MethodA is the most prec

5、ise and accurate. It is used to develop an electrometric titration curve (sometimes referred to as a pH curve),which defines the acidity or alkalinity of the sample and indicates inflection points and buffering capacity, if any. In addition, theacidity or alkalinity can be determined with respect to

6、 any pH of particular interest. The other two methods are used to determineacidity or alkalinity relative to a predesignated end point based on the change in color of an internal indicator or the equivalentend point measured by a pH meter. They are suitable for routine control purposes.1.3 When titr

7、ating to a specific end point, the choice of end point will require a careful analysis of the titration curve, the effectsof any anticipated changes in composition on the titration curve, knowledge of the intended uses or disposition of the water, anda knowledge of the characteristics of the process

8、 controls involved. While inflection points (rapid changes in pH) are usuallypreferred for accurate analysis of sample composition and obtaining the best precision, the use of an inflection point for processcontrol may result in significant errors in chemical treatment or process control in some app

9、lications. When titrating to a selectedend point dictated by practical considerations, (1) only a part of the actual neutralizing capacity of the water may be measured,or (2) this capacity may actually be exceeded in arriving at optimum acidity or alkalinity conditions.1.4 A scope section is provide

10、d in each test method as a guide. It is the responsibility of the analyst to determine theacceptability of these test methods for each matrix.1.5 Former Test Methods C (Color-Comparison Titration) and D (Color-Change Titration After Boiling) were discontinued.Refer to Appendix X4 for historical info

11、rmation.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to est

12、ablish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D596 Guide for Reporting Results of Analysis of WaterD1066 Practice for Sampling SteamD1129 Terminology Relating to Water1These test methods

13、 are under the jurisdiction of ASTM Committee D19 on Water and are the responsibility of Subcommittee D19.05 on Inorganic Constituents in Water.Current edition approved Dec. 15, 2006. Published January 2007. Originally approved in 1949. Last previous edition approved in 2002 as D106702. DOI:10.1520/

14、D1067-06.Current edition approved April 1, 2011. Published April 2011. Originally approved in 1949. Last previous edition approved in 2006 as D1067 06. DOI:10.1520/D1067-11.2The basic procedures used in these test methods have appeared widespread in the technical literature for many years. Only the

15、particular adaptation of the electrometrictitration appearing as the Referee Method is believed to be largely the work of Committee D19.3For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume i

16、nformation, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequate

17、ly depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standard.Copyright ASTM Int

18、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D1193 Specification for Reagent WaterD1293 Test Methods for pH of WaterD2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on WaterD3370 Practices for Sampli

19、ng Water from Closed ConduitsD5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water AnalysisE200 Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical Analysis3. Terminology3.1 DefinitionsThe terms in these test m

20、ethods are defined in accordance with Terminology D1129.3.1.1 Certain uses of terminology exist in the water treatment industry which may differ from these definitions. A discussionof terms is presented in Appendix X1.4. Significance and Use4.1 Acidity and alkalinity measurements are used to assist

21、in establishing levels of chemical treatment to control scale,corrosion, and other adverse chemical equilibria.4.2 Levels of acidity or alkalinity are critical in establishing solubilities of some metals, toxicity of some metals, and thebuffering capacity of some waters.5. Purity of Reagents5.1 Reag

22、ent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conformto the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications areavailable.4Other grades may be used, provided it is f

23、irst ascertained that the reagent is of sufficiently high purity to permit its usewithout lessening the accuracy of the determination.5.2 Unless otherwise indicated, references to water shall be understood to mean reagent water conforming to SpecificationD1193, Type I. In addition, reagent water for

24、 this test shall be free of carbon dioxide (CO2) and shall have a pH between 6.2 and7.2 at 25C. Other reagent water types may be used provided it is first ascertained that the water is of sufficiently high purity topermit its use without adversely affecting the precision and bias of the test method.

25、 Type III water was specified at the time of roundrobin testing of this test method. A procedure for the preparation of carbon dioxide-free water is given in Practice E200.6. Sampling6.1Collect6.1 Collect the sample in accordance with Practice D1066 and Practices D3370 as applicable.6.2 The time int

26、erval between sampling and analysis shall be as short as practically possible in all cases. It is mandatory thatanalyses by Test Method A be carried out the same day the samples are taken; essentially immediate analysis is desirable for thosewaste waters containing hydrolyzable salts that contain ca

27、tions in several oxidation states.TEST METHOD AELECTROMETRIC TITRATION7. Scope7.1 This test method is applicable to the determination of acidity or alkalinity of all waters that are free of constituents thatinterfere with electrometric pH measurements. It is used for the development of a titration c

28、urve that will define inflection pointsand indicate buffering capacity, if any. The acidity or alkalinity of the water or that relative to a particular pH is determined fromthe curve.8. Summary of Test Method8.1 To develop a titration curve that will properly identify the inflection points, standard

29、 acid or alkali is added to the samplein small increments and a pH reading is taken after each addition. The cumulative volume of solution added is plotted against theobserved pH values. All pH measurements are made electrometrically.9. Interferences9.1 Although oily matter, soaps, suspended solids,

30、 and other waste materials may interfere with the pH measurement, thesematerials may not be removed to increase precision, because some are an important component of the acid- or alkali-consumingproperty of the sample. Similarly, the development of a precipitate during titration may make the glass e

31、lectrode sluggish and causehigh results.10. Apparatus10.1 Electrometric pH Measurement Apparatus, conforming to the requirements given in Test Methods D1293.4Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reag

32、ents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopoeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D1067 11211. Reagents411.1 Hydrochloric Acid, Standard (

33、0.02 N) (see Note 1)Prepare and standardize as directed in Practice E200, except that thetitration shall be made electrometrically. The inflection point corresponding to the complete titration of carbonic acid salts will bevery close to pH 3.9.NOTE 1Sulfuric acid of similar normality may be used ins

34、tead of hydrochloric acid. Prepare and standardize in like manner.11.2 Sodium Hydroxide, Standard (0.02 N)Prepare and standardize as directed in Practice E200, except that the titration shallbe made electrometrically. The inflection point corresponding to the complete titration of the phthalic acid

35、salt will be very closeto pH 8.6.12. Procedure12.1Mount12.1 Mount the glass and reference electrodes in two of the holes of a clean, threehole rubber stopper chosen to fita 300-mL, tall-form Berzelius beaker without spout, or equivalent apparatus.Alternatively, a combination pH electrode can be used

36、that has both a glass and a reference electrode in an integral unit. Place the electrodes in the beaker and standardize the pH meter,using a reference buffer having a pH approximating that expected for the sample (see Test Methods D1293). Rinse the electrodes,first with reagent water, then with a po

37、rtion of the sample. Following the final rinse, drain the beaker and electrodes completely.12.2 Pipette 100 mL of the sample, adjusted, if necessary, to room temperature, into the beaker through the third hole in thestopper. Hold the tip of the pipette near the bottom of the beaker while discharging

38、 the sample.12.3 Measure the pH of the sample in accordance with Test Methods D1293.12.4 Add either 0.02 N acid or alkali solution, as indicated, in increments of 0.5 mL or less (see Note 2). After each addition,mix the solution thoroughly. Determine the pH when the mixture has reached equilibrium a

39、s indicated by a constant reading (seeNote 3). Mechanical stirring, preferably of the magnetic type, is required for this operation; mixing by means of a gas stream isnot permitted. Continue the titration until the necessary data for the titration curve have been obtained.NOTE 2If the sample require

40、s appreciably more than 25 mL of standard solution for its titration, use a smaller aliquot, or a 0.1 N solution, preparedand standardized in the same manner (see Practice E200).NOTE 3An electrometric titration curve is smooth, with the pH changing progressively in a single direction, if equilibrium

41、 is achieved after eachincremental addition of titrant, and may contain one or more inflection points. Ragged or irregular curves may indicate that equilibrium was not attainedbefore adding succeeding increments. The time required will vary with different waters as the reaction rate constants of dif

42、ferent chemical equilibria vary.In some instances the reaction time may be an interval of a few seconds while other slower, more complex reactions may require much longer intervals.It is important, therefore, that the period be sufficient to allow for any significant pH changes, yet consistent with

43、good laboratory practices.12.5 To develop a titration curve, plot the cumulative milliliters of standard solution added to the sample aliquot against theobserved pH values. The acidity or alkalinity relative to a particular pH may be determined from the curve.13. Calculation13.1 Calculate the acidit

44、y or alkalinity, in milliequivalents per litre, using Eq 1:Acidity or alkalinity!, meq/L epm!5AN/B 3 1000(1)where:1000 = 1000 mL / literA = standard acid or alkali required for the titration, mL,N = normality of the standard solution, andB = sample titrated, mL.14. Report14.1 Report the results of t

45、itrations to specific end points as follows: “The acidity (or alkalinity) to pH at C = meq/L (epm).”14.2 Appropriate factors for converting milliequivalents per litre (epm) to other units are given in Guide D596.15. Precision and Bias515.1 The precision and bias data presented in Table 1 for this te

46、st method meet the requirements of Practice D2777.15.2 The collaborative test of this test method was performed in reagent waters by six laboratories using one operator each,using three levels of concentration for both the acidity and alkalinity.15.3 Precision and bias for this test method conforms

47、to Practice D277777, which was in place at the time of collaborativetesting. Under the allowances made in 1.4 of Practice D277798,08, these precision and bias data do meet existing requirementsfor interlaboratory studies of Committee D19 test methods.TEST METHOD BELECTROMETRIC OR COLOR-CHANGE TITRAT

48、ION16. Scope16.1 This test method covers the rapid, routine control measurement of acidity or alkalinity to predesignated end points of5Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D19-1149.D1067 113waters that contain no mat

49、erials that buffer at the end point or other materials that interfere with the titration by reasons that mayinclude color or precipitation.17. Summary of Test Method17.1 The sample is titrated with standard acid or alkali to a designated pH, the end point being determined electrometrically orby the color change of an internal indicator.18. Interferences18.1 Natural color or the formation of a precipitate while titrating the sample may mask the color change of an internal indicator.Suspended solids may interfere in electrometric titrations by making the glass elect