1、Designation: D2896 11D2896 15Standard Test Method forBase Number of Petroleum Products by PotentiometricPerchloric Acid Titration1This standard is issued under the fixed designation D2896; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, 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 U.S. Department of Defense.1. Scope*1.1 This test met
3、hod covers the determination of basic constituents in petroleum products by titration with perchloric acid inglacial acetic acid.1.2 Procedures A and B use different titration solvent volumes and sample weights.NOTE 1A round robin on a series of new and used oils and additive concentrates has shown
4、that the two procedures give statistically equivalentresults.1.3 Appendix X2 provides the use of an alternative solvent system which eliminates the use of chlorobenzene in this testmethod. The use of the alternative solvent gives statistically equivalent results; however, the precision is worse. Par
5、agraph X2.5.5provides guidance when comparing results using the two different solvents.1.4 The constituents that may be considered to have basic characteristics include organic and inorganic bases, aminocompounds, salts of weak acids (soaps), basic salts of polyacidic bases, and salts of heavy metal
6、s.NOTE 2This test method is applicable to both fresh oils and used oils as described in Sections 16, 17, and 19 and Appendix X1.1.5 This test method can be used to determine base number 300 mg 300 mg KOH/g. However, the precision statement inSection 19 has been obtained only on base number 300 mg 30
7、0 mg KOH/g.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
8、establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific warning statements, see Section 7, Section 10, and X2.2.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent Water3. Terminology3.1 Definitions:
9、3.1.1 base numberthe quantity of a specified acid, expressed in terms of the equivalent number of milligrams of potassiumhydroxide per gram of sample, required to titrate a sample in a specified solvent to a specified endpoint using a specified detectionsystem.4. Summary of Test Method4.1 The sample
10、 is dissolved in an essentially anhydrous mixture of chlorobenzene and glacial acetic acid and titrated with asolution of perchloric acid in glacial acetic acid using potentiometric titrimeter. A glass indicating electrode and a reference1 This test method is under the jurisdiction of ASTM Committee
11、 D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.Current edition approved May 15, 2011Dec. 1, 2015. Published July 2011February 2016. Originally approved in 1970. Last previous edition
12、approved in 20072011 asD2896D2896 11.07a. DOI: 10.1520/D2896-11.10.1520/D2896-15.This test method has been approved by the sponsoring committees and accepted by the cooperating societies in accordance with established procedures.2 For referencedASTM standards, visit theASTM website, www.astm.org, or
13、 contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes hav
14、e been made to the previous version. Becauseit may not be technically possible to adequately 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 doc
15、ument.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1electrode are used, the latter being connected with the sample solution by means of a salt bridge. The meter readin
16、gs are plottedagainst the respective volumes of titrating solution, and the end point is taken at the inflection in the resulting curve.4.2 Procedure A uses 120 mL 120 mL of titration solvent. Procedure B uses 60 mL 60 mL of titration solvent. In addition, thetwo procedures use different equations f
17、or the calculation of appropriate sample weights. Since many portions of the test methodare identical for ProceduresAand B, only the unique sections will be described separately for the two versions of the test method.4.3 Occasionally certain used oils give no inflection in the forward titration mod
18、e, in which case a back titration modificationwith sodium acetate titrant is employed.5. Significance and Use5.1 New and used petroleum products can contain basic constituents that are present as additives. The relative amounts of thesematerials can be determined by titration with acids. The base nu
19、mber is a measure of the amount of basic substance in the oil,always under the conditions of the test. It is sometimes used as a measure of lubricant degradation in service; however, anycondemning limits must be empirically established.6. Apparatus6.1 Potentiometric Titrimeters , Titrimeters, either
20、 automatic recording or manual.6.2 Glass Electrode, pH 0 to 11, general-purpose type.6.3 Reference Electrode, silver/silver chloride (Ag/AgCl) reference electrode with a nonaqueous bridge as described in Section10. (See also 19.1.)NOTE 3Some reference electrodes with fritted or fiber diaphragms and
21、some combined glass plus reference electrodes systems are commerciallyavailable, such as the single-rod glass plus silver/silver chloride electrode assembly. During the development of this test method, the use of electrodesof these types gave problems in some laboratories, but not in others. Accordi
22、ngly, these electrodes are permitted in this test method, provided that thesodium perchlorate bridge is used; however, when stability or other problems arise with their use, the sleeve-type electrode should be used.6.4 Stirrer, either mechanical or electrical, with variable speeds and with propeller
23、 or paddle of chemically inert material. Whenan electrical stirrer is used, it must be grounded so that disconnecting or connecting the power to the motor will not produce apermanent change in meter reading during the course of a titration. A magnetic stirrer with stirring bar can be used provided i
24、tmeets these conditions.6.5 Buret, 1010 mL or 20-mL,20 mL, graduated in 0.05-mL0.05 mL divisions and calibrated with an accuracy of 60.02 mL,60.02 mL, or an automatic buret of similar accuracy.6.6 Titration Beaker, made of borosilicate glass or other suitable titration beaker, tall form recommended.
25、6.6.1 For Procedure A, use a beaker of 250250 mL or 300 mL 300 mL capacity. For Procedure B, use a beaker of about 150mL 150 mL capacity such that 60 mL 60 mL of titration solvent will cover the electrodes.NOTE 4Other beakers of suitable size capacity may be used.6.7 Titration Stand, suitable to sup
26、port the beaker, electrodes, stirrer, and buret. An arrangement that allows for the removal ofthe beaker without disturbing the electrodes, buret, and stirrer is desirable.NOTE 5Some apparatus may be sensitive to interference by static electricity, shown by erratic movements of recorder pen or meter
27、 indicator, whenthe titration assembly (beaker and electrodes) is approached by the operator. In this case surround the beaker closely with a cylinder of copper gauze thatis electrically grounded.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unles
28、s otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.3 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently
29、 highpurity to permit its use without lessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water that meets therequirement of either Type I, II, or III of Specification D1193.7.3 Acetic Acid, glacial (Warni
30、ngToxic and irritant).7.4 Acetic Anhydride (WarningToxic and irritant).7.5 Chlorobenzene (WarningToxic and irritant).3 Reagent Chemicals, American Chemical Society Specifications , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemica
31、l Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D2896 1527.6 Perchloric Acid, Standard Solution in Acetic Acid (0.1 N)4 (WarningPowerful oxidan
32、t when dry or heated. Great careshould be taken to avoid contact with organic matter under conditions that may result in subsequent drying or heating, and spillsshould be washed immediately and thoroughly with water)Mix 8.5 mL 8.5 mL of 7070 % to 72 % perchloric acid (HClO4,7070 % to 72 %) (or 10.2
33、mL 10.2 mL of 6060 % to 62 % HClO4 solution) with 500 mL 500 mL of glacial acetic and 30 mL (or35 mL 30 mL (or 35 mL if the 6060 % to 62 % HClO4 solution is used) of acetic anhydride. Dilute to 1 L 1 L with glacial aceticacid. Allow the solution to stand for 24 h.NOTE 6Excess acetic anhydride should
34、 be avoided to prevent acetylation of any primary or secondary amines that may be present.7.7 Potassium Hydrogen Phthalate(KHC8H4O4).7.8 Sodium Perchlorate Electrolyte(WarningSodium perchlorate is toxic and an irritant. It is also a powerful oxidizingagent when heated. Great care should be taken to
35、avoid contact with organic matter under conditions that may result in subsequentdrying or heating, and spills should be washed immediately and thoroughly with water.) Prepare a saturated solution of sodiumperchlorate (NaClO4 ) in glacial acetic acid.An excess of undissolved NaClO4 shall always be pr
36、esent at the bottom of the solution.7.9 Titration SolventAdd one volume of glacial acetic acid to two volumes of chlorobenzene.7.10 Sodium Carbonate, anhydrous (Na2CO3).7.11 Sodium Acetate Solution, 0.1 N in acetic acid (for back titration, see Sections 16 and 17)Dissolve 5.3 g 5.3 g ofanhydrous Na2
37、CO3 in 300 mL 300 mL of glacial acetic acid. Dilute to 1 L 1 L with acetic acid after solution is complete.8. Standardization of Reagents8.1 Perchloric Acid SolutionThe standardization of the perchloric acid solution (HClO4) differs for the two procedures asfollows:8.1.1 Procedure A (120 mL)(120 mL)
38、Heat a quantity of potassium hydrogen phthalate in an oven at 120C120 C for 2 h 2hand allow it to cool. Take 0.10.1 g to 0.2 g 0.2 g of the potassium hydrogen phthalate weighed to the nearest 0.1 mg 0.1 mg anddissolve it in 40 mL40 mLof warm glacial acetic acid.Add 80 mL80 mLof chlorobenzene, cool,
39、and titrate with 0.1 0.1 N HClO4solution, using the electrode system and procedures given in 10.1 to 10.4 and 11.4 to 11.7. Detect the end point by the sameprocedure used for base number determination (see 14.214.2).). Carry out a blank titration on 40 mL 40 mL of glacial acetic acidplus 80 mL 80 mL
40、 of chlorobenzene (see 11.8).8.1.2 Procedure B (60 mL)(60 mL)Heat a quantity of potassium hydrogen phthalate in an oven at 120C120 C for 2 h 2 hand allow it to cool. Take 0.050.05 g to 0.1 g 0.1 g of the potassium hydrogen phthalate weighed to the nearest 0.1 mg 0.1 mg anddissolve it in 20 mL of war
41、m glacial acetic acid. Add 40 mL of chlorobenzene, cool, and titrate with 0.1 N HClO4 solution asdescribed in 8.1.1. Carry out a blank titration on 20 mL 20 mL of glacial acetic acid and 40 mL of chlorobenzene (see 11.8).8.1.3 Calculate the normality, NA, of the HClO4 solution as follows:NA51000W/20
42、4.23V 2b!# (1)where:W = potassium hydrogen phthalate, g,V = HClO4 solution used, mL, andb = volume corresponding to V for the blank titration, mL.NOTE 7Because of the relatively large coefficient of volumetric expansion of organic liquids, the acetous HClO4 solution should be used within 65C 65 C of
43、 the temperature at which it was standardized. If used at a temperature more than 5C5 C higher, multiply the volume used by the factor1 (t0.001). If used at a temperature more than 5C5 C lower, multiply by the factor 1 + (t0.001), where tis the difference in degrees Celsius betweentemperatures of st
44、andardization and use and is always positive.8.2 Sodium Acetate SolutionThe standardization of the sodium acetate solution (Na2CO3) differs for the two procedures asfollows:8.2.1 Procedure A (120 mL)(120 mL)Use 120 mL 120 mL of titration solvent and 8.00 mL 8.00 mL of 0.1 NHClO4 solution.Titrate wit
45、h 0.1 N sodium acetate solution, using the electrode system and procedure given in 10.1 to 10.4 and 11.4 to 11.7. Detectthe end point by the same procedure as will be used for base number determination (see 14.2). Calculate the normality, NB, of thesodium acetate solution as follows:NB58.002b!NA#/G
46、(2)where:b = volume corresponding to V for the blank titration,NA = normality of the HClO4 solution, andG = volume of standard sodium acetate used in the standardization, mL.8.2.2 Procedure B (60 mL)(60 mL)Use 60 mL 60 mL of titration solvent and 4.00 mL 4.00 mL of 0.1 N HClO4 solution.Titrate as de
47、scribed in 8.2.1. Calculate the normality, NB , of the sodium acetate solution as follows:4 Available commercially for purchase already prepared.D2896 153NB54.002b!NA#/G (3)where:b = volume corresponding to V for the blank titration,NA = normality of the HClO4 solution, andG = volume of standard ace
48、tous sodium acetate used in the standardization, mL.9. Preparation of Sample9.1 It is essential to ensure that the sample is representative since any sediment can be acidic or basic or have adsorbed acidicor basic material from the sample. When necessary, samples are warmed to aid mixing. Used oils
49、should be vigorously shaken toensure homogeneity before sampling.NOTE 8As used oils can change appreciably in storage, samples should be tested as soon as possible after removal from the lubricating system andthe dates of sampling and testing, if known, should be noted.10. Preparation of Electrode System10.1 Preparation of ElectrodesWhen the reference electrode is to be changed from aqueous bridge to nonaqueous, drain outthe aqueous solution, wash out all crystals of KCl with water, then rinse the outer jacket (salt bridge) sev
