Document 93k4D9G8gG1GegdLdOXjjxDMR

September 30, 1968 Method No. TC-AM-68-15 itu m is . DETERMINATION OP ACID-SOLUBLE IRON IN ASBESTOS 1. Scope --' This method is suitable for the determination of 0.2# ^ or more of acid-soluble Iron in asbestos. 2. Principle Iron is solubilized by digestion of the asbestos with hot hydrochloric acid. The iron Is reduced with stannous chloride and then measured by titration with standard * potassium dichromate. 3- Safety Precautions Strong mineral acids are used In this procedure. Care should be exercised to prevent spilling of the acids on the skin or clothing. If this occurs, wash the affected areas immediately with large quantities of water. The eyes should be protected with safety glasses or chemical goggles. 4. Reagents (a^ Hydrochloric acid, ACS reagent. (b) Stannous chloride solution. Weigh 6 grams of the dihydrate (Sn C12*2H20) into a 250 ml beaker and add approximately 60 ml concentrated hydrochloric acid. Heat gently for solution, and then dilute to approximately 100 ml with water. Store in an amber bottle. (c) Mercuric chloride, saturated aqueous solution. Add approximately 10 grams of reagent grade HgCl2 to a glass bottle for each 100 ml solution required. Add distilled water and shake the solution vigorously for approximately oneminute. < de- C-r- ^ 1 of 3 pages ,< 4. September 50, 1968 2 of 5 pages Method No. TC-AM-68-15 S TU D TU (d) Diphenylamine indicator solution, 1% dissolved in concentrated sulfuric acid. Alternate preparation: To one gram of barium diphenylamine sulfonate in 100 ml water, add approximately 0.5 grams sodium sulfate. Acidify the solution with dilute sulfuric acid and heat gently on the hot plate. Stir occasionally to aid precipitation. Filter the hot solution through a close-textured filter paper catching the filtrate in an amber dropper bottle. Discard the paper and precipitate. (e) Sulfuric-phosphoric acid mixture. While stirring, add 150 ml concentrated ACS reagent sulfuric acid to 500 ml cold distilled water. Follow this by adding, while stirring, 150 ml concentrated phosphoric acid. Dilute the mixture to approximately 1,000 ml. with distilled water. (f) Potassium dichromate, 0.1N solution. Weigh 4.904 grams of dried K2Cr207. Dissolve in distilled water and dilute to one liter in a liter volumetric flask. Standardize the solution as follows: Weigh to the nearest 0.1 mg approximately 0.2 grams high purity iron wire in a 400 ml beaker and add 20 ml concentrated hydrochloric acid. Attach cover glass and heat the solution gently until the iron is dissolved. Complete the standardization according to the following procedure beginning with the addition of stannous chloride and continuing throughout the procedure. 5. Procedure (a) Weigh approximately 2 grams of the asbestos to three decimal places on the analytical balance and transfer to 400 ml beakers. Add 100 ml distilled water and 50 ml concen trated hydrochloric acid. Add cover glasses and boiling chips to the beakers and place on the hot plate. Boil gently for a minimum of one hour, adding more water as needed to maintain the volume essentially constant. (b) To the hot solutions, add while stirring stannous chloride drop by drop until the solutions are colorless. Now add 5 to 5 drops in excess. Place the solutions in an ice bath for cooling. When cold, quickly add 20 ml satu rated mercuric chloride solution while stirring vigorously (note 7a). Continue stirring for approximately 50 seconds. Place the beakers in the cold bath for 5 to 10 minutes. (c) Dilute the solutions to approximately 250 ml with distilled water and add 15 ml of the sulfuric acid-phosphoric acid mixture. Add about 10 drops of the diphenylamine indicator solution. While stirring, titrate with 0.1N potassium dichromate until a permanent dark blue color is reached. This color should persist for 50 seconds. * September 30, 1968 3 of 3 pages Method No. TC-AM-68-15 6. Calculations Normality of K2Cr207 = grams of pure iron taken ml titrant x 0.05585 # Iron (Fe) = ml x Normality of K2Cr207 x 5 grams sample % Iron Oxide (Fe20s) = $ Iron (Fe) x 1.43 7. Notes A white feathery precipitate should appear at this point. If no precipitate is evident, not enough stannous chloride was added; if a dark precipitate appears, too much stannous chloride was added. If either of the latter two situations develops, the test must be repeated using a greater or lesser quantity of the stannous chloride. tiU M L S . W. F. Crawford Central Laboratory A-1203 Building ga b -/qo70 H K tZ O iS MIDLAND October 10, 1968 0 R. A. Smith B-205 Freeport, Texas PAPER: Determination of Acid-Soluble Iron in Asbestos. W. F. Cravford This method, containing the standard liability clause, is approved for outside distribution. We are retaining three copies for our files. Comments: E. E. Schilling-Disclaimer stamp should be applied to copies going outside Dow. F. W. Koerker-Omit Author's name and add legal paragraph to copies for outside distribution. E. Monroe Corporate R. & D. ram B-1U070 i g ROUTING SHEET FOR THE RELEASE OF TECHNICAL INFORMATION \ TECHNICAL INFORMATION SERVICES 566 BLDG.. MIDLAND. MICHIGAN 0 IN ORDER TO SAFEGUARD THE INTEREST OF THE DOW CHEMICAL COMPANY AND ITS AUTHORS, ALL TALKS. PAPERS, PUBLICATIONS, ARTICLES, NEWS RELEASES, > ETC.. FOR RELEASE OUTSIDE THE COMPANY, MUST FIRST BE APPROVED. TECHNICAL INFORMATION MUST BE APPROVED BY MIDLAND TECHNICAL INFORMA- ^ TION SERVICES AND OTHER MATERIAL BY THE PUBLIC RELATIONS DEPARTMENT. 1 CORPORATE R & 0 NOTE: SEND 4 COPIES OF MATERIAL TO TECHNICAL INFORMATION SERVICES, 566 BLDG., MIDLAND, MICH. ALL INFORMATION ABOVE OF THIS FORM IS TO BE SUPPLIED AT SOURCE. 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MIOHIOAN CEMTRAl-5tMlCH'HDEX N A LYTIC AL METHOD THIS IS 'A FILF COPY- FOR DUTSiV'- OsSTKICUTjOW OBTAIN CC?'=5 VtTH UAB/LITT CLAUSE AND WITHOUT ^y-vsv/ otpPRtNCL September 30, 1968 ) * DETERMINATION OF ACID-SOLUBLE IRON IN ASBESTOS 3 1. Scope ~ This method is suitable for the determination of 0. 2% or more of acidvsoluble iron in asbestos. 2. Principle Iren is solubilized by digestion of the asbestos with hot hydrochloric s acid. The iron is reduced with stannous chloride and then measured by titration -with standard potassium dichromate. 3. Safety Precautions Strong mineral acids are used in this procedure. Care should be exercised to prevent spilling of the acids on the skin or clothing. If this occurs, wash the affected areas immediately with large quantities of water. The eyes shouLd be protected with safety glasses or chemical goggles. 4. Reagents (a) Hydrochloric acid, ACS reagent. (b) Stannous chloride solution. Weigh six grams of the dihydrate (SnCL>. 2HzO) into a 250 ml beaker and add approximately 60 ml concentrated hydrochloric acid. Heat gently for solution, then dilute to approximately 100 ml with water. Store in an amber bottle. (c) Mercuric chloride, saturated aqueous solution. Add approximately 10 grams of reagent grade HgCl^ to a glass bottle for each 100 ml solution required. Add distilled water and shake the solution vigorously for approxi mately one minute. (d) Diphenylamine indicator solution, 1% dissolved in concentrated sulfuric acid. Alternate preparation: To one gram of barium diphenylamine sulfonate in 100 ml water, add approximately 0. 5 grams sodium sulfate. Acidify the solution with dilute sulfuric acid and heat gently on the hot plate. Stir occasionally to aid precipitation. Filter the hot solution through a closetextured filter paper catching the filtrate in an amber dropper bottle. Discard the paper and precipitate. 1 of 3 pages . s. Cr- j September 30, 1968 2 of 3 pages Method No. TC-AM-68-15 ST0299938 (e) Sulfuric-phosphoric acid mixture. While stirring, add 150 ml concentrated ACS reagent sulfuric acid to 500 ml cold distilled water. Follow this by adding, while stirring, 150 ml concentrated phosphoric acid. Dilute the mixture to approximately 1, 000 ml with distilled water. (f) Potassium dichromate, 0. IN solution. Weigh 4. 904 grams of dried KjCrz07. Dissolve in distilled water and dilute to one liter in a liter volu metric flask. Standardize the solution as follows: Weigh to the nearest 0.1 mg approximately 0. 2 grams high purity iron wire in a 400 ml beaker and add 20 ml concentrated hydrochloric acid. Attach cover glass and heat the solution gently until the iron is dissolved. Complete the standardization according to the following procedure beginning with the addition of stannous chloride and continuing throughout the procedure. 5. Procedure (a) Weigh approximately 2 grams of the asbestos to three decimal places on the analytical balance and transfer to 400 ml beakers. Add 100 ml distilled water and 50 ml concentrated hydrochloric acid. Add cover glasses and boiling chips to the beakers and place on the hot plate. Boil gently for a minimum of one hour, adding more water as needed to maintain the volume essentially constant. (b) To the hot solutions, add while stirring stannous chloride drop by drop until the solutions are colorless. Now add 3 to 5 drops in excess. Place the solutions in an ice bath for cooling. When cold, quickly add 20 ml saturated mercuric chloride solution while stirring vigorously (see note). Continue stirring for approximately 30 seconds. Place the beakers in the cold bath for 5 to 10 minutes. (c) Dilute the solutions to approximately 250 ml with distilled water and add 15 ml of the sulfuric acid-phosphoric acid mixture. Add about 10 drops of the diphenylamine indicator solution. While stirring, titrate with 0. IN potassium dichromate until a permanent dark blue color is reached. This color should persist for 30 seconds. 6. Calculations Normality of I^Cr^ = grams of pure iron taken ml titrant x 0. 05585 % Iron (Fe) = ml x Normality of K,CrgQ7 x 5. 585 grams sample %Iron Oxide (Fe203) = %Iron (Fe) x 1. 43 cctcazois. September 30, 1968 3 of 3 pages Method No. TC-AM-68-15 7. Notes A white feathery precipitate should appear at this point. If no pre cipitate is evident, not enough stannous chloride was added; if a dark pre cipitate appears, too much stannous chloride was added. If either of the latter two situations develops, the test must be repeated using greater or lesser quantity of the stannous chloride. ******************** The analytical procedures given herein have been adapted from literature sources or developed upon the basis of experimental data which are believed to be reliable. In the hands of a qualified analyst they are expected to yield results of sufficiency accuracy for their intended purposes. However, The Dow Chemical Company makes no representation or warranty whatsoever concern ing the procedures or results to be obtained and assumes no liability in con nection with their use. Users are cautioned to confirm the suitability of the methods by appropriate tests. Anyone wishing to reproduce or publish the material in whole or in part should request written permission from The Dow Chemical Company. W. F. Crawford Central Laboratory