ASTM D5799-1995(2014) 8534 Standard Test Method for Determination of Peroxides in Butadiene《丁二烯中过氧化物测定的标准试验方法》.pdf

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1、Designation: D5799 95 (Reapproved 2014)Standard Test Method forDetermination of Peroxides in Butadiene1This standard is issued under the fixed designation D5799; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi

2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of peroxidesin butadiene.1.2 This test method covers the concentrations range of 1 to

3、10 ppm by mass (ppmw) as available oxygen.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of t

4、he user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1265 Practice for Sampling Liquefied Petroleum (LP)Gases, Manual MethodD3700 Practice for Obtaining LPG S

5、amples Using a Float-ing Piston Cylinder3. Summary of Test Method3.1 A known mass of the butadiene sample is placed in aflask and evaporated. The residue is then refluxed with aceticacid and sodium iodide reagents. The peroxides react toliberate iodine which is titrated with standard sodium thiosul-

6、fate solution using visual end-point detection. Interfering tracesof iron are complexed with sodium fluoride.4. Significance and Use4.1 Due to the inherent danger of peroxides in butadiene,specification limits are usually set for their presence. This testmethod will provide values that can be used t

7、o determine theperoxide content of a sample of commercial butadiene.4.2 Butadiene polyperoxide is a very dangerous product ofthe reaction between butadiene and oxygen that can occur. Theperoxide has been reported to be the cause of some violentexplosions in vessels that are used to store butadiene.5

8、. Apparatus5.1 Condensers, Liebig, with 24/40 standard-taperedground-glass joint connections.5.2 Cylinders, graduated, 100-mL capacity.5.3 Flask, Erlenmeyer, 250-mL capacity, with 24/40standard-tapered ground-glass connections with marking at100 mL.5.4 Heating Mantle, electric, for 250-mLErlenmeyer

9、flasks.5.5 Microburette, 10-mL capacity, graduated in 0.02-mLdivisions.5.6 Water Bath, a thermostatically controlled liquid bathcapable of maintaining a water temperature of 60 6 1C.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is

10、intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use

11、without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean deionized or distilledwater.6.3 Acetic Acid, 94 % by volume. Mix 60 mL of water with940 mL of glacial acetic acid (CH3COOH). (Warning1This test method is u

12、nder the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.D0.04 on C4 Hydrocarbons.Current edition approved May 1, 2014. Published July 2014. Originally approvedin 1995. Last previous edition approved in 2009 as

13、 D5799 95 (2009). DOI:10.1520/D5799-95R14.2For 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,

14、 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 LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Form

15、ulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Poisonous and corrosive. Combustible. May be fatal if swal-lowed. Causes severe burns. Harmful if inhaled.)6.4 Carbon Diox

16、ide, solid (dry ice). (WarningUse glovesto avoid frostbite when handling.)6.5 Potassium Dichromate Solution, Standard (0.1 N)Dissolve 2.452 g of potassium dichromate (K2Cr2O7) in waterand dilute to 500 mL in a volumetric flask. (WarningAvoidcontact with eyes and skin and avoid breathing of dust.)6.6

17、 Sodium Fluoride.6.7 Sodium Iodide.6.8 Sodium Thiosulfate Solution, Standard (0.1 N)Dissolve 12.5 g of sodium thiosulfate (Na2S2O35H2O) plus0.1 g of sodium carbonate (Na2CO3) in 500 mL of water (theNa2CO3is added to stabilize the Na2S2O3solution). Let thissolution stand a week or more before using.

18、Standardizeagainst 0.1 N K2Cr2O7solution. Restandardize at frequenciesto detect changes of 0.0005 in normality.7. Sampling7.1 Butadiene should be sampled in a metal container of atype which ensures maximum safety and which is resistant tobutadiene corrosion. The size of the container is dependentupo

19、n the number of times the test is to be performed accordingto this test method. Refer to Practice D1265 or Practice D3700for instructions on sampling.8. Procedure8.1 Remove the oxygen from a 250-mLErlenmeyer flask byadding several pellets (approximately 1 cm in size) of dry iceand allowing the CO2to

20、 displace the air. This will takeapproximately 5 min.8.2 Record the weight to one decimal place of the samplecylinder, and then transfer approximately 100 mLs of butadi-ene sample from the cylinder to the 250 mL Erlenmeyer flaskcontaining several pellets of dry ice. Reweigh the samplecylinder and re

21、cord the weight of the sample as the differenceof the two weights. (WarningButadiene is a flammable gasunder pressure.)8.3 Place the flask in a water bath at 60C in a wellventilated hood. Allow the butadiene to evaporate whilekeeping an inert atmosphere above the liquid butadiene bycontinuing to add

22、 pellets of dry ice at intervals until all thebutadiene has evaporated. (WarningPeroxides are unstableand react violently when taken to dryness. Peroxides at thelevels experienced during the test method evaluation have notcaused a problem, but caution needs to be exhibited in handlingby the use of p

23、ersonal protective equipment.)8.4 Remove the flask from the water bath and allow to coolto ambient temperature. Add 50 mL of 94 % acetic acid and0.20 6 0.02 g of sodium fluoride. Add several more pellets ofdry ice to the flask and allow to stand for 5 min.8.5 Add 6.0 6 0.2 g of sodium iodide to the

24、flask andimmediately connect to the Liebig condenser. Turn on theheating mantle and reflux the solution for 25 6 5 min. Keep theequipment away from strong light during refluxing.8.6 At the end of the reaction period, turn off the heatingmantle and remove the flask with condenser from the mantle.Imme

25、diately add 100 mL of water through the top of thecondenser followed by several pellets of dry ice.8.7 Maintaining an inert atmosphere with CO2pellets,remove the flask from the condenser and allow to cool toambient temperature. Cold water may be used to assist in thisstep. Titrate the liberated iodi

26、ne with 0.1 N sodium thiosulfateuntil a clear endpoint is reached.8.8 Repeat 8.4 through 8.7 for the reagent blank.9. Calculation9.1 Calculate the peroxide content as follows:peroxide, as O2, ppmw 5A 2 B! 3 N 316000W(1)where:A =Na2S2O3solution required for titration of thesample, mL,B =Na2S2O3soluti

27、on required for titration of theblank, mL,N = normality of the Na2S2O3solution,W = sample weight, g, and16 000 = milliequivalents of oxygen.10. Precision and Bias410.1 PrecisionThe precision of this test method as deter-mined by statistical examination of interlaboratory results is asfollows:10.1.1

28、RepeatabilityThe difference between two test re-sults obtained by the same operator with the same apparatusunder constant operating conditions on identical test materialswould, in the long run, in the normal and correct operation ofthe test method, exceed the following values only in one caseof twen

29、ty:R 5 1.4 ppmw10.1.2 ReproducibilityThe difference between two singleand independent results, obtained by different operators work-ing in different laboratories on identical test material, would, inthe long run and in the normal and correct operation of the testmethod, exceed the following values o

30、nly in one case intwenty.R 5 3.4 ppmw10.2 BiasAs no reliable source of butadiene polyperoxideis available, the actual bias of the test method is unknown; butpublished data reports that this test method determines 90 % ofthe polyperoxide.511. Keywords11.1 butadiene; butadiene polyperoxide; peroxide4S

31、upporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1372.5For a discussion of the background for this test method, see Mayo, Hendry,Jones, and Scheatzle, Industrial and Engineering Chemical , Product Research,Vol7, 1968, p. 145.D5

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