1、Designation: D 7373 07An American National StandardStandard Test Method forPredicting Biodegradability of Lubricants Usinga Bio-kinetic Model1This standard is issued under the fixed designation D 7373; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 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.1. Scope1.1 This test method covers a procedure for predictingbiodegradability of lubricants using
3、 a bio-kinetic model.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 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 stan
4、dard 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:2D 2549 Test Method for Separation of Representative Aro-matics and Nonaromatics Fractions of High-Boiling Oilsby Elution Chrom
5、atographyD 5864 Test Method for Determining Aerobic Aquatic Bio-degradation of Lubricants or Their ComponentsD 6731 Test Method for Determining the Aerobic, AquaticBiodegradability of Lubricants or Lubricant Componentsin a Closed Respirometer3. Terminology3.1 Definitions:3.1.1 aromatics fraction, np
6、ortion of the sample desorbedwith the polar eluants. The aromatics fraction is divided intononpolar and polar based. They may contain aromatics, con-densed naphthenic-aromatics, aromatic olefins, and com-pounds containing sulfur, nitrogen, and oxygen atoms.3.1.2 bio-kinetic model, nmodel that can pr
7、edict thebiodegradability of a lubricant.3.1.3 biodegradability, nability of a substance to bebroken down into simpler substances by bacteria.3.1.4 effective composition to biodegradation (ECB),ncomponent of material that can be biodegradable bybacteria.3.1.4.1 DiscussionThe term ECB is a part of bi
8、o-kineticmodel is sum of non-aromatic components in a lubricant.3.1.5 nonaromatics fraction, nportion of the sampleeluted with n-pentane. The nonaromatics fraction is a mixtureof paraffinic and naphthenic hydrocarbons if sample is astraight-run material. If the sample is a cracked stock, thenonaroma
9、tics fraction will also contain aliphatic and cyclicolefins.4. Summary of Test Method4.1 A weighed amount of sample is charged to the top of aglass chromatographic column packed with activated bauxiteand silica gel. To elute the nonaromatics, n-pentane is added tothe column. When all of the nonaroma
10、tics are eluted, non-polararomatics fraction is eluted by additions of an equal mixture oftoluene and n-pentane. The ester fraction is eluted by additionsof diethyl ether. Then, the polar-aromatics is eluted by chloro-form and ethyl alcohol.4.2 The solvents are completely removed by evaporation,and
11、the residues are weighed and calculated as the nonaromat-ics, nonpolar aromatics, ester fractions, and polar aromatics ofthe sample.4.3 ECB is calculated based on the amount of nonaromaticsand ester fractions with their material ECB coefficients. Then,the biodegradability of a lubricant is calculate
12、d using thebio-kinetic model.5. Significance and Use5.1 This procedure is able to predict the biodegradability oflubricants within a day without dealing with microorganisms.3Excellent correlation is established between the test results andthe conventional biodegradation tests (see Test Method D 5864
13、and Test Method D 6731).1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.12 on Environmental Standards for Lubricants.Current edition approved July 15, 2007. Published August 2007.2For referenced
14、 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.3Rhee, In-Sik, “Development of Bio-kinetic Model for Lubricants,” NLGISpokes
15、man, Volume 69, 2005, pp. 22-29.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 Chromatographic Columnsas shown in Fig. 1 (seeTest Method D 2549).6.2 Beakers (100, 250, and 600-mL)inverted-rim type.6.3 Steam Bath.6.4
16、Electric Vibratorfor packing column.6.5 Weighing Bottles or Erlenmeyer Flasks25 and 50 mL.6.6 Graduated Cylinders50 mL, 100 mL, and 250 mL.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in this test. Unless otherwise indicated, it is intended thatall reagents sha
17、ll conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available. Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy
18、 of the determination.7.2 Bauxite, 20- to 60-meshBefore use, activate the baux-ite by heating at 538C (1000F) for 16 h. Transfer theactivated material to an airtight container while still hot andprotect thereafter from atmospheric moisture.7.3 Chloroform(WarningToxic. May be fatal if swal-lowed.)7.4
19、 Cleaning SolutionChromic-sulfuric acid.(WarningCauses severe burns. A recognized carcinogen,strong oxidizer, contact with organic material may cause fire.)7.5 Diethyl EtherAnhydrous. (WarningExtremelyflammable.) The ethyl ether used in this test method should befree of peroxides as determined by th
20、e procedure in ReagentChemicals, American Chemical Society Specifications.47.6 Ethyl Alcohol, DenaturedConforming to Formula 2Bof the U.S. Bureau of Internal Revenue. (WarningFlammable.)7.7 Pressuring GasDry air or nitrogen, delivered to thetop of the column at a regulated gage pressure of 0 to 2 ps
21、i(13.8 kPa). (WarningCompressed gas.)7.8 n-pentaneCommercial grade, aromaticfree. Somesamples of waxy stocks may not dissolve completely inn-pentane, in which case cyclohexane, commercial grade,aromatic-free, may be substituted for n-pentane. (WarningExtremely flammable liquid.)4Reagent Chemicals, A
22、merican Chemical Society Specifications, AmericanChemical 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 Formul
23、ary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Test ApparatusD73730727.9 Silica Gel100- to 200-mesh.7.10 TolueneReagent grade minimum purity.(WarningToluene is flammable. Vapor harmful.)8. Procedure for Composition Analysis8.1 Clean the column with chromic-sulfuric acid (7.4),f
24、ollowed by distilled or demineralized water, acetone, and dryair or nitrogen.8.2 Introduce a small plug of glass wool into column,pressing it firmly into the lower end to prevent the flow of silicagel from the column.8.3 Clamp the column in a vertical position. Add smallincrements of silica gel, whi
25、le vibrating the column along itslength, until the tightly packed silica gel extends to the lowermark on the chromatographic column.8.4 Continue to vibrate the column and add bauxite until thebauxite layer extends to the upper mark on the chromato-graphic column. Vibrate the column for an additional
26、 3 minafter filling is completed8.5 If the sample is viscous, warm it with intermittentmixing or shaking until it is completely fluid.8.6 Transfer a representative sample (approximately 2 g) toa 25-mL weighing bottle or flask. Determine the weight of thesample to the nearest 1 mg by weighing the fla
27、sk before andafter sample transfer.8.7 Add 10 mL of n-pentane (7.8) to the flask and dissolvethe sample.8.7.1 If the sample does not dissolve completely in coldn-pentane, warm it in warm water or over a steam bath.8.7.2 If the sample does not dissolve in warm n-pentane,take a fresh sample and substi
28、tute cyclohexane for then-pentane.NOTE 1This procedure is only applicable to liquid-based lubricants.Solid or semisolid lubricants can not be analyzed due to their formations.Therefore, the lubricating grease cannot be analyzed, but its extracted oilcan be analyzed using this procedure.8.8 Add 10 mL
29、 of n-pentane to the top of the column toprewet the adsorbent.8.9 When the liquid level reaches the top of the bauxite bed,transfer the sample solution from the weighing flask to the topof the column.8.10 Rinse the flask with three successive 3-mL washes ofn-pentane. Add each wash to the top of the
30、column.8.11 Then rinse the walls of the column bulb with two 3-mLportions of n-pentane, allowing the liquid level to reach the topof the bauxite bed before adding the next portion.8.12 Finally add 35-mL of n-pentane to the column bulb.8.13 Place a 50-mL graduate beneath the column to collectthe elua
31、te. The elution rate should be approximately 1 mL/min.8.14 When the n-pentane level reaches the top of the bauxitebed, add 80 mL of an equal mixture of n-pentane and toluene(50:50 vol %). Connect the pressuring gas to the top of thecolumn and adjust the pressure to maintain an elution rate of 1to 2
32、mL/min. Collect 50 mL of n-pentane eluate in thegraduate. Rinse the tip of the column with 1 to 2 mL ofn-pentane, adding this to the 50 mL in the graduate. Label the50 mL graduate as n-pentane eluate.8.15 When the 50:50 vol % mixture of toluene and pentanelevel reaches the top of the bauxite bed, re
33、lease the gaspressure and add 80 mL of diethyl ether (7.5) to the top of thecolumn. Reconnect the gas pressuring system and continue theelution. When 80 mL of elute haven collected in the graduate,rinse the column tip with 1 mL of the 50:50 vol % mixture oftoluene and pentane and add the rinse to th
34、e 100 mL graduate.Change the receiver to a 100 mL graduate. Label the 100 mLgraduate as nonpolar aromatic fraction.8.16 When the ether level reaches the top of the bauxite bed,release the gas pressure and add 100 mL of chloroform (7.3)tothe top of the column. Reconnect the gas pressuring system andc
35、ontinue the elution. When 80 mL of eluate have beencollected in the graduate, rinse the column tip with 1 mL ofether and add the rinse to the 100 mL graduate. Change thereceiver to a 250 mL graduate. Label the 100 mL graduate asether-eluted fraction.8.17 When the chloroform level reaches the top of
36、thebauxite bed, release the gas pressure and add 75 mL of ethylalcohol (7.6). Reconnect the gas pressuring system and con-tinue the elution until the alcohol level reaches the top of thebauxite bed. Release the gas pressure. Rinse the column tipwith 1 mL of chloroform adding this to the graduate. La
37、bel the250 mL graduate as chloroform-alcohol-eluted fraction.8.18 Weigh a 100 mL inverted-rim beaker to the nearest1 mg. Quantitatively transfers the n-pentane eluate to thisbeaker and allows the n-pentane to evaporate at room tempera-ture. Cyclohexane, if used as the elution solvent, is evaporatedo
38、n a steam bath. Evaporation is accelerated in both cases bydirecting a controlled steam of dry nitrogen downward onto thesurface of the liquid.8.19 When all the solvent appears to be evaporated, stop thenitrogen flow, allow the beaker to come to room temperature,and dry the outside of the beaker to
39、remove any condensedmoisture. Reweigh the beaker to the nearest 1 mg.8.20 Repeat the evaporation step for 5-min periods until theweight loss between successive evaporations is less than 20mg. Heat from a stream bath is generally required during thefinal evaporation steps to remove completely the elu
40、tionsolvent. The weight of the residue in the beaker is the quantityof the nonaromatics friction.8.21 Weigh a 250 mL inverted-rim beaker to the nearest 1mg. Quantitatively transfer the chloroform-alcohol-eluted frac-tion to this beaker and evaporate on a stream bath with acontrolled stream of dry ni
41、trogen directed downward onto thesurface of the liquid. When the solvent is evaporated, removethe beaker from the steam bath, cool to room temperature, andadd quantitatively the ether-eluted fraction. Evaporate the etherat room temperature as described in 8.18-8.20. Determine theweight of the residu
42、e (ester fraction) to the nearest 1 mg.8.22 The weight of aromatics (polar and nonpolar), esterfraction plus the nonaromatics fraction recovered must equal atleast 95% of the sample charged. If 95% recovery is notobtained, repeat the test. Recoveries greater than 100% indicateincomplete removal of s
43、olvent or the condensation of moisturein the beakers.8.23 Transfer all sample fractions into suitable size ofsample vials for storage pending further analysis.D73730739. Calculation9.1 Calculate the percentage of the nonpolar aromatics andpolar aromatics fraction, nonaromatics and ester fraction asf
44、ollows:Nonaromatics, wt % 5 a/ total recovered!# 3100 (1)Nonpolar aromatic, wt % 5 b/ total recovered 3100 (2)Ester fraction, wt % 5 c/ total recovered 3100 (3)Polar aromatics, wt % 5 d/ total recovered 3100 (4)where:a = weight of nonaromatics recovered byn-pentane,b = weight of nonpolar aromatics r
45、ecoveredby 50:50 mixture of toluene andn-pentane,c = weight of ester fraction recovered bydiethyl ether,d = weight of polar aromatics recovered bychloroform and ethyl alcohol, andTotal recovered = a + b + c + d.9.2 Calculate ECB value of sample as follows:ECB 5(achaCa1hcCc(5)where:h = ECB coefficien
46、t listed in Table 1,Ca= Fraction of nonaromatics (n-pentane), andCc= Fraction of ester (diethyl ether).9.3 Calculate the biodegradability of a lubricant usingbio-kinetic model as follows:Bt! 5 B1! 10.49ln 6.8 3 ECB22.38!ln t (6)where:t = time, hours,B(t) = Biodegradability of a lubricant with time,
47、andB(1) = 0.01.10. Report10.1 The value calculated in 9.3 is reported as the biode-gradability of a lubricant.11. Precision and Bias11.1 PrecisionThe precision of this test method is notavailable at the present time. However, the repeatability of TestMethod D 2549 is being given as a preliminary pre
48、cision untila full interlaboratory study is carried out within five years.11.2 Preliminary PrecisionThe repeatability of TestMethod D 2549 (compositional analysis) is being cited toprovide a preliminary estimate of the precision of this testmethod under repeatability conditions.Test Method D 2549 re
49、peatability = 1.4%11.3 Repeatability and ReproducibilityTo be determined.11.4 BiasBias cannot be determined because there are noreference materials suitable for determining the bias in this test.12. Keywords12.1 bio-kinetic model; biodegradability of lubricant; ECB;lubricantASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risko
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