ASTM E649-2017a red 7500 Standard Test Method for Bromine in Chlorine《氯中溴含量的标准试验方法》.pdf

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1、Designation: E649 17E649 17aStandard Test Method forBromine in Chlorine1This standard is issued under the fixed designation E649; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses in

2、dicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of bromine in liquid chlorine and in gaseous chlorine with a lower limit ofdetection of 4 ug/kg by weight.1.2 Review

3、 the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first-aid procedures, handling,and safety precautions.1.3 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

4、 establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Specific hazard statements are given in Section 7.1.3 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first-aid procedures, handling,and

5、 safety precautions.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Tech

6、nical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related MaterialsE180 Practice for Determining the Precision of ASTM Methods for Anal

7、ysis and Testing of Industrial and Specialty Chemicals(Withdrawn 2009)3E200 Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical Analysis3. Summary of Test Method3.1 Chlorine gas is sampled by absorption in aqueous sodium hydroxide (NaOH). Liquid chlo

8、rine is first vaporized, and thevapor is absorbed in aqueous sodium hydroxide.An aliquot of the sample solution is reduced with an excess of sulfite ion, acidified,and excess sulfur dioxide (SO2) boiled out. In a carefully buffered solution, bromide is oxidized to bromate by hypochlorite. Excesshypo

9、chlorite is reduced to chloride by formate. In the presence of molybdate catalyst, bromate is reduced to bromide by iodide,and the liberated iodine is titrated with standard sodium thiosulfate solution.4. Significance and Use4.1 Low levels of bromine contaminant in chlorine cause problems in some in

10、dustrial uses. This test method may be used todetermine bromine in liquid or gaseous chlorine at levels as low as 4 ug/kg.5. Apparatus5.1 The construction of the chlorine gas sampling apparatus and of the assembled sampling equipment is shown in Figs. 1 and2. Modification of the equipment to deal wi

11、th special sampling circumstances may be necessary. In Fig. 2, the control valve is1 This test method is under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons Aromatic, Industrial, Specialty and Related Chemicals and is the directresponsibility of Subcommittee D16.16 on Industrial an

12、d Specialty Product Standards.Current edition approved March 1, 2017July 1, 2017. Published March 2017July 2017. Originally approved in 1978. Last previous edition approved in 20112017 asE649 00 (2011).E649 17. DOI: 10.1520/E0649-17.10.1520/E0649-17a.2 For referencedASTM standards, visit theASTM web

13、site, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an

14、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 adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In

15、 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 standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1FIG. 1

16、Chlorine Gas Sampling Apparatus1. Inverted liquid chlorine cylinder2. Chlorine cylinder valve3. Control valve (14-in. 316 stainless steel needle valve)4. 14-in. PTFE instrument air tubing5. Small pail or 2-L beaker filled with water6. Evaporating coil (two loops held with tape at indicated points)7.

17、 Gas sampling apparatus of Fig. 1FIG. 2 Liquid Chlorine Sampling EquipmentE649 17a2shown with an adaptor for connection to a chlorine cylinder valve. Other adaptors will be required when sampling liquid chlorinein liquefaction plant streams or from large shipping or storage containers.5.2 A 10-mL bu

18、ret calibrated in 0.05-mL divisions is used when titrating with 0.01 N standard sodium thiosulfate solution.6. Reagents6.1 Purity of ReagentsUnless otherwise indicated, it is intended that all reagents should conform to the specifications of theCommittee on Analytical Reagents of the American Chemic

19、al Society, where such specifications are available.4 Other grades maybe used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracyof the determination.6.2 Purity of WaterUnless otherwise indicated, references to water shal

20、l be understood to mean Type II or Type III reagentwater conforming to Specification D1193.6.3 Chloride SolutionDissolve 200 g of sodium chloride (NaCl) in 940 mL of water.6.4 Formate SolutionDissolve 50 g of sodium formate in 175 mL of water.6.5 Hypochlorite SolutionDissolve 6.2 g of NaOH in 190 mL

21、 of water and chlorinate slowly, with stirring, to give a gain inweight of 5.0 g.NOTE 1If desired, a commercial hypochlorite bleach solution may be used as the hypochlorite solution. Although such commercial bleach solutionsare not made from reagent grade chemicals, the reagent blank determination (

22、see 9.4) corrects for the bromine and any chlorate content in such solutions.A proprietary 5.25 % sodium hypochlorite bleach solution is satisfactory for this use. Because the sodium chloride and hypochlorite solutions contributemost to the reagent blanks, dispense these solutions by pipet to ensure

23、 uniformity of blanks and determinations (see 9.1 and 9.2).6.6 Molybdate Solution (44 g/L)Dissolve 4.4 g of ammonium molybdate (NH4)6Mo7O244H2O) in 10 mL of 6 N ammoniumhydroxide (NH4OH) and dilute with 90 mL of water.6.7 Phenolphthalein Indicator Solution (1 g/L)Dissolve 0.1 g of phenolphthalein an

24、d 0.1 g sodium carbonate (Na2CO3) in 5mL of water and dilute to 100 mL.6.8 Phosphate Solution (100 g/L)Dissolve 50 g of monobasic sodium phosphate (NaH2PO4H2O) in 500 mL of water.6.9 Sodium Hydroxide Solution (10 %)Dissolve 1 part by weight of sodium hydroxide (NaOH) in 9 parts of water.6.10 Sodium

25、Thiosulfate, Standard Solution (0.01 N)Prepare 0.01 N sodium thiosulfate solution fresh daily by accuratedilution of standard 0.1 N sodium thiosulfate solution. Prepare, standardize, and restandardize 0.1 N sodium thiosulfate solutionin accordance with Practice E200.6.11 Starch Solution (10 g/L)Diss

26、olve 1 g of soluble starch in 100 mL of boiling water. Make up fresh daily.6.12 Sulfuric Acid (6 N)Add slowly and cautiously with constant stirring, 1 volume of concentrated sulfuric acid (sp gr 1.84,H2SO4) to 5.5 volumes of water. Warning: Use goggles when preparing this solution. Cool to room temp

27、erature before use.6.13 Sulfuric Acid (1 + 1)Add slowly with stirring 1 volume of concentrated sulfuric acid (H2SO4, sp gr 1.84) to 1 volumeof water. Warning: Use goggles when preparing this solution.7. Hazards7.1 Concentrated sulfuric acid, sodium hydroxide, and sodium hypochlorite solutions are ra

28、pidly corrosive to skin and eyes. Incase of accidental contact with skin, immediately flush affected part with large volumes of water. For eyes, immediately flush withwater for at least 15 min; then get prompt medical attention. Goggles should be worn when handling these chemicals.7.2 Chlorine sampl

29、ing should be performed only by persons thoroughly familiar with handling this material and with operationof the sampling system. Personnel should be equipped with a respirator, goggles, faceshield, and gloves. If possible, performsampling in a hood or other well-ventilated area. In sampling liquid

30、chlorine, do not leave the space between two closed valvesfilled with liquid chlorine (see 8.6).7.3 When sampling and working with chlorine out of doors, people downwind from such operation should be warned of thepossible release of chlorine vapors.7.4 It is recommended that means be available for d

31、isposal of excess chlorine in an environmentally safe and acceptable manner.If chlorine cannot be disposed of in a chlorine-consuming process, a chlorine absorption system should be provided. When theanalysis and sampling regimen requires an initial purging of chlorine from a container, the purged c

32、hlorine should be similarlyhandled. Purging to the atmosphere should be avoided.7.5 In the event chlorine is inhaled, first aid should be summoned immediately and oxygen administered without delay.4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, D

33、C. For suggestions on the testing of reagents not listed bythe American Chemical 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.E649 17a37.6 Chl

34、orine is a corrosive and toxic material. A well-ventilated fume hood should be used to house all test equipment whenthis product is analyzed in the laboratory.8. Sampling8.1 Record to the nearest 0.1 g the tare of the clean and dry chlorine gas sampling apparatus of Fig. 1, except for the insulating

35、jacket. Add 150 mL of 10 % NaOH solution and seal the stopper firmly in place. Record the tare of this assembly to the nearest0.1 g. Place the apparatus in the insulating jacket and allow to stand to reach temperature equilibrium.8.2 Saturated chlorine vapor will contain only about 0.3 as much bromi

36、ne as the liquid chlorine with which it is in equilibrium.Hence, when sampling containers of liquid chlorine, it is necessary to make sure that only the liquid phase is sampled. Gaseouschlorine sources may be sampled directly, using a small valve to control the chlorine flow. Feed the liquid chlorin

37、e throughvaporizing equipment before passing the resulting vapor into the chlorine gas sampling apparatus. There is no need for a vaporizerwhen sampling a source of gaseous chlorine.8.3 Asatisfactory vaporizer for sampling liquid chlorine is readily prepared from a 1.5 to 2-m length of 14-in. (6.35-

38、mm) outsidediameter polytrafluoroethylene (PTFE) instrument air tubing. This had adequate flexibility, and is easily coiled to form a 120-mmdiameter evaporating coil. When sampling a liquid chlorine cylinder, invert the cylinder and connect the apparatus as shown in Fig.2. Do not wire the tubing con

39、nections. This will allow the tube to blow off in case of excessive pressure. With the small controlvalve closed, open the liquid chlorine supply valve about a half turn to bring the liquid chlorine to the control valve.8.4 Swirl the NaOH solution in the chlorine sampling apparatus thoroughly and no

40、te the initial temperature; then very carefullyopen the control valve to allow a small stream of chlorine gas to purge the air from the line leading to the sampling apparatus.Lift the sampling apparatus partially out of its insulating jacket to observe the bubbles rising from the fritted gas sparger

41、. As theair is purged from the system, increase the chlorine flow, so that the chlorine bubbles entering the solution from the sparger shrinkto minimum size about 20 mm below the surface of the liquid. Lower the sampling bottle into the insulating jacket and observethe temperature of the solution.8.

42、5 The temperature should rise at 2 to 5C/min. If the rate of temperature rise is higher or lower than this, adjust the chlorineflow accordingly. Swirl the sampling apparatus frequently to mix thoroughly and achieve temperature uniformity. When thetemperature reaches 20C above the initial temperature

43、, remove the sampling apparatus from the insulating jacket, turn off thecontrol valve, and immediately disconnect the PTFE tubing from the control valve. With an aspirator bulb, blow air through thetubing to force all chlorine in the PTFE tubing into the sample solution.8.6 Close the chlorine supply

44、 valve and immediately open slightly the control valve to vent liquid chlorine trapped between thevalves. Direct the vented chlorine into a hood or a chlorine disposal system. Warning: Do not overlook this venting procedure.If the space between the closed supply and control valves is left completely

45、 filled with liquid chlorine, dangerous pressures rapidlybuild up when the temperature is allowed to rise.8.7 Thoroughly blend the sample solution while using the aspirator bulb to push the sample solution back and forth through thesparger frit. Carefully clean and dry the outside of the sampling as

46、sembly and weigh to the nearest 0.1 g. The gain in weight ofthe apparatus is the weight of chlorine absorbed. The final weight less the tare of the empty apparatus is the weight of the samplesolution.9. Procedure9.1 Take about one third of the sample solution (61 g), weigh to the nearest 0.1 g, and

47、transfer into a 500-mL Erlenmeyer flaskwith a volume calibration mark at 100 mL. Add by pipet, 25 mL of chloride solution, add 9 g of sodium sulfite (Na2SO3), and 25mL of water, swirl, and warm, to dissolve; then add slowly, while swirling, 9 mL of H2SO4 (1 + 1). Add three boiling beads, heatto boil

48、ing, and immediately test the vapor with moist starch iodide paper that has been treated with a trace of chlorine vapor togive a light blue color. The starch iodide paper should be bleached colorless, indicating an excess of sulfite over the chlorine inthe sample. Continue to boil for 10 min, adding

49、 water if necessary to bring any deposited salts into solution. At this point, thesolution volume should be less than 100 mL.9.2 Cool the sample to below 50C, add 1 drop of phenolphthalein indicator solution, and neutralize to within 1 drop excessof 10 % NaOH solution. Add 20 mL of phosphate solution, and add by pipet, 10 mL of hypochlorite solution. Heat the solutionnearly to boiling for 5 min, then boil the solution for 2 min. At the end of this boiling period, the steam from the sample solutionshould rapidly turn moist starch iodide paper blue. This in