1、Designation: D 2710 99 (Reapproved 2004)e1Designation: 299/92 (98)An American National StandardStandard Test Method forBromine Index of Petroleum Hydrocarbons by ElectrometricTitration1This standard is issued under the fixed designation D 2710; the number immediately following the designation indica
2、tes the year oforiginal adoption or, in the case 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.e1NOTEWarning notes were editorially moved into the sta
3、ndard text in May 2004.1. Scope1.1 This test method covers the determination of the amountof bromine-reactive material in petroleum hydrocarbons and isthus a measure of trace amounts of unsaturates in thesematerials. It is applicable to materials having bromine indexesbelow 1000.1.2 This test method
4、 is applicable only to essentially olefin-free hydrocarbons or mixtures that are substantially free frommaterial lighter than isobutane and have a distillation end pointunder 288C (550F).1.3 The values stated in SI units are to be regarded asstandard. The values stated in inch-pound units are for in
5、for-mation only.1.4 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-bility of regulatory limitations prior to use
6、.NOTE 1This procedure has been cooperatively tested on materialswith bromine indexes in the range from 100 to 1000. These materialsinclude petroleum distillates such as straight-run and hydrocrackednaphtha, reformer feed, kerosine, and aviation turbine fuel.NOTE 2Materials with bromine index greater
7、 than 1000 should betested for bromine number using Test Method D 1159/IP 130.NOTE 3Bromine index of industrial aromatic hydrocarbons should bedetermined using Test Method D 1492 or D 5776.2. Referenced Documents2.1 ASTM Standards:2D 1159 Test Method for Bromine Numbers of PetroleumDistillates and C
8、ommercial Aliphatic Olefins by Electro-metric TitrationD 1492 Test Method for Bromine Index of Aromatic Hy-drocarbons by Coulometric TitrationD 5776 Test Method for Bromine Index of Aromatic Hy-drocarbons by Electrometric Titration3. Terminology3.1 Definition:3.1.1 bromine indexthe number of milligr
9、ams of brominethat will react with 100 g of sample under the conditions of thetest.4. Summary of Test Method4.1 A known mass of the sample dissolved in a specifiedsolvent is titrated with standard bromide-bromate solution. Theend point is indicated by a dead stop electrometric titrationapparatus whe
10、n the presence of free bromine causes a suddenchange in the electrical conductivity of the system.5. Significance and Use5.1 This test method provides a measure of trace amounts ofunsaturated hydrocarbons in petroleum distillates boiling up to288C (550F). An estimate of the quantity of these materia
11、lsis useful in assessing the suitability of the lighter fractions foruse as reaction solvents.6. Apparatus6.1 Electrometric End Point Titration ApparatusAny ap-paratus designed to perform titrations to pre-set end points (seeNote 4) may be used in conjunction with a high-resistancepolarizing current
12、 supply capable of maintaining approxi-mately 0.8 V across two platinum electrodes and with asensitivity such that a voltage change of approximately 50 mVat these electrodes is sufficient to indicate the end point. Othertypes of commercially available electric titrimeters, includingcertain pH meters
13、, have also been found to be suitable.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04 on Hydrocarbon Analysis.Current edition approved May 1, 2004. Published May 2004. Originallyapproved in 1
14、968. Last previous edition approved in 1999 as D 2710 99.In the IP, this test method is under the jurisdiction of the StandardizationCommittee.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards vo
15、lume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 4Pre-set end point indicated with polarized electrodes providesa detection technique similar to th
16、e dead stop technique specified inprevious versions of this test method.6.2 Titration VesselA jacketed glass vessel of approxi-mately 150-mL capacity of such a form that can be conve-niently maintained at 0 to 5C (32 to 41F). A pair of platinumelectrodes spaced not more than 5 mm apart shall be moun
17、tedto extend well below the liquid level. Stirring shall be by amechanical or electromagnetic stirrer and shall be rapid, butnot so vigorous as to draw air bubbles down to the electrodes.6.3 Burets, 10 and 50-mL capacity.6.4 Iodine Number Flasks, glass-stoppered, 500-mL capac-ity.7. Reagents7.1 Puri
18、ty of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the AmericanChemical Society where such specifications are available.3Other grades may be used, providing it is first ascertained thatth
19、e reagent is of sufficiently high purity to permit its usewithout lessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean distilled water, or waterof equivalent purity.7.3 Preparation and Standardization:7.3.1 Bromide-
20、Bromate Standard Solution (0.05 N)Dissolve 5.1 g of potassium bromide (KBr) and 1.4 g potas-sium bromate (KBrO3) in water and dilute to 1 L. Standardizeto four significant figures as follows: Place 50 mL of glacialacetic acid (WarningPoison. Combustible. May be fatal ifswallowed. Causes severe burns
21、. Harmful if inhaled) and 1 mLof concentrated hydrochloric acid (HCl, sp gr 1.19)(WarningPoison. Corrosive. May be fatal if swallowed.Liquid and vapor cause severe burns. Harmful if inhaled.) in a500-mL iodine number flask. Chill the solution in an ice bathfor approximately 10 min, and with constant
22、 swirling of theflask, add from a 50-mL buret 40 to 45 mL of bromide-bromatesolution, estimated to the nearest 0.01 mL, at a rate such thatthe addition takes between 90 and 120 s. Stopper the flaskimmediately, shake the contents, place it again in the ice bath,and add 5 mL of potassium iodide (KI) s
23、olution in the lip of theflask. After 5 min, remove the flask from the ice bath and allowthe KI solution to flow into the flask by slowly removing thestopper. Shake vigorously, add 100 mL of water in such amanner as to rinse the stopper, lip, and walls of the flask, andtitrate promptly with the stan
24、dard sodium thiosulfate(Na2S2O3) solution. Near the end of the titration, add 1 mL ofstarch indicator solution and titrate slowly to the disappearanceof the blue color. Calculate the normality of the bromide-bromate solution as follows:N15 A2N2/A1(1)where:N1= normality of the bromide-bromate solutio
25、n,A1= millilitres of the bromide-bromate solution,N2= normality of the Na2S2O3solution, andA2= millilitres of the Na2S2O3solution required for titra-tion of the bromide-bromate solution.7.3.2 Potassium Iodide Solution (150 g/L)Dissolve 150 gof KI in water and dilute to 1 L.7.3.3 Sodium Thiosulfate,
26、Standard Solution (0.05 N)Dissolve 12.5 g of sodium thiosulfate pentahydrate (Na2S2O35H2O) in water and add 0.01 g of sodium carbonate (Na2CO3)to stabilize the solution. Dilute to 1 L and mix thoroughly byshaking. Standardize by any accepted procedure that deter-mines the normality with an error not
27、 greater than 60.0002.Restandardize at intervals frequent enough to detect changes of0.0005 in normality.7.3.4 Starch Indicator SolutionMix5gofsoluble starchwith approximately 3 to 5 mL of water. If desired, add about0.65 g salicylic acid as preservative. Add the slurry to 500 mLof boiling water and
28、 continue boiling for 5 to 10 min. Allow tocool and decant the supernatant liquid into glass bottles andseal well. Starch solutions (some preserved with salicylic acid)are also commercially available and may be substituted.7.3.5 Sulfuric Acid (1+5)Carefully add 1 volume ofconcentrated sulfuric acid
29、(H2SO4, sp gr 1.84) to 5 volumes ofwater and thoroughly mix. (WarningPoison. Corrosive.Strong oxidizer. Contact with organic material may cause fire.May be fatal if swallowed.)7.3.6 Titration SolventPrepare 1 L of titration solvent bymixing the following volumes of materials: 714 mL of glacialacetic
30、 acid, 134 mL of 1,1,1-trichloroethane or dichlo-romethane, 134 mL of methanol, and 18 mL of H2SO4(1+5)(see 7.3.5).7.4 Solvents:7.4.1 Acetic Acid, glacial. (WarningPoison. Combus-tible. May be fatal if swallowed. Causes severe burns. Harmfulif inhaled.)7.4.2 Methanol (WarningFlammable. Vapor harmful
31、.May be fatal if swallowed. Causes severe burns. Harmful ifinhaled.)7.4.3 1,1,1-Trichloroethane (WarningHarmful if inhaled.High concentrations may cause unconsciousness or death.Contact may cause skin irritation and dermatitis.)7.4.4 Dichloromethane (WarningHarmful if inhaled.High concentrations may
32、 cause unconsciousness or death.Contact may cause skin irritation and dermatitis.)NOTE 5The replacement of 1,1,1-trichloroethane, an ozone-depletingchemical, is necessary because its manufacture and import has beendiscontinued. Dichloromethane is temporarily being allowed as an alter-native to 1,1,1
33、-trichloroethane until a permanent replacement can beidentified and adopted by ASTM.NOTE 6The user of this test method may choose to use either1,1,1-trichloroethane or dichloromethane to the exclusion of the othersolvent. The selected solvent is to be used for all operations, including thepreparatio
34、n of the titration solvent and the dilution of samples, ifapplicable.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 LaboratoryChemi
35、cals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D 2710 99 (2004)e12NOTE 7Commercially available reagents can be used in place oflaboratory preparations.8. Procedure8.1 Switch on the titrimeter and
36、 allow the electrical circuitsto stabilize in accordance with the manufacturers instructions.8.2 Cool the titration vessel to 0 to 5C (32 to 41F) bycirculating a suitable coolant through the jacketed titrationvessel.8.3 Introduce 110 mL of titration solvent into the titrationvessel and pipet in a qu
37、antity of sample as indicated in Table 1.Switch on the stirrer and adjust to a rapid stirring rate, butavoid any tendency for air bubbles to be drawn down into thesolution. Allow the contents to cool to 0 to 5C (32 to 41F)and maintain at this temperature throughout the titration.(WarningHydrocarbon
38、samples, particularly those boilingbelow 205C (400F), are flammable.)8.3.1 Frequently the order of magnitude of the bromineindex of a sample is unknown. In this case, a trial test isrecommended using an 8 to 10-g sample in order to obtain theapproximate magnitude of the bromine index. This explorato
39、rytest should be followed with another determination using theappropriate sample size as indicated in Table 1.8.3.2 The sample mass can be determined by obtaining thedensity of the sample and calculating the mass of a measuredvolume.8.4 Set the end point potential. With each instrument, themanufactu
40、rers instructions should be followed for end pointsetting and to achieve the sensitivity in the platinum electrodecircuit specified in 6.1.8.5 Depending on the titrator apparatus, add the bromide-bromate solution manually or by microprocessor control insmall increments from the buret. The end point
41、of the titrationis achieved when the potential reaches the pre-set value (see8.4) and persists for more than 30 s.8.6 BlanksMake duplicate blank titrations on each batchof titration solvent and reagents. Less than 0.10 mL ofbromide-bromate solution should be required.9. Calculation9.1 Calculate the
42、bromine index as follows:Bromine index 5 A 2 B!N 3 7990/W (2)where:A = millilitres of bromide-bromate solution required fortitration of the sample,B = millilitres of bromide-bromate solution required fortitration of the blank,N = normality of bromide-bromate solution, andW = grams of sample.10. Prec
43、ision and Bias10.1 Precision:10.1.1 The precision of this test method as obtained bystatistical examination of interlaboratory test results is asfollows:10.1.1.1 RepeatabilityThe difference between successivetest results obtained by the same operator with the sameapparatus under constant operating c
44、onditions on identical testmaterial would, in the long run, in the normal and correctoperation of the test method, exceed 14 in only one case intwenty.10.1.1.2 ReproducibilityThe difference between twosingle and independent results, obtained by different operators,working in different laboratories o
45、n identical test material,would in the long run, in the normal and correct operation ofthe test method, exceed 118 in only one case in twenty.10.2 BiasThe procedure in this test method has no biasbecause the value of bromine index can be defined only interms of a test method.NOTE 8The precision for
46、this test method was not obtained inaccordance with RR:D02-1007.4NOTE 9It is not known whether the precision estimates are applicablewhen using dichloromethane as a constituent of the titration solvent.11. Keywords11.1 bromide-bromate solution; bromine index; electromet-ric titration; hydrocarbons;
47、petroleum4This research report is available from ASTM International Headquarters andmay be obtained by requesting Research Report RR: D021007.TABLE 1 Sample SizeBromine Index Sample Size,g100 to 500 10 to 8Over 500 to 1000 8 to 4D 2710 99 (2004)e13ANNEX(Mandatory Information)A1. RESULTS OF BROMINE I
48、NDEX COOPERATIVE PROGRAMA1.1 See Table A1.1 for the bromine index results.TABLE A1.1 Bromine IndexSample 1091 1092 1093 1094 1095 PooledLab. 1 1 1064 116 576 391 4472 1064 120 576 392 447avg 1064 118 576 392 4472 1 1081 115 573A349 4672 1102 119 604A368 474avg 1092 117 589 359 4713 1 1097 147 688 40
49、9 5442 1114 136 688 397 544avg 1106 142 688 403 5444 1 1120 124 582 397 4162 . 118 . 399 .avg (1120) 121 (582) 398 (416)5 1 1039 116 532 388 3892 1049 116 537 388 373avg 1044 116 535 388 3816 1 1055 113 549 395 3602 1055 115 548 390 366avg 1055 114 549 393 3637 1 1063 113 573 365 4432 1061 113 566 385 450avg 1062 113 570 375 4478 1 1277 142 718 449 6202 1274 141 719 451 621avg 1276B142 719B450 621BX, average 1078 123 584 395 438RepeatabilityDegrees of freedom 13 15 11 15 13 31sr, standard deviation 5.5 2.2 1.8 6.1 3.8 5r, repeata
