Chapter 14 Tex-619-J, Analysis of Water for Chloride and Sulfate Ions

Transcription

1 Chapter 14 Tex-619-J, Analysis of Water for Contents: Section 1 Overview Section 2 Apparatus Section 3 Reagents Section 4 Procedures Section 5 Calculations Section 6 Archived Versions J, Chemical Test Procedures 14-1 TxDOT 08/02 07/05

2 Section 1 Overview Effective dates: August 2002 July Section 1 Overview This method covers the calculation of chloride and sulfate ions in water to determine its suitability for concrete, sprinkling or similar uses. Interference and methods of treating them may be found in ASTM D 512 and ASTM D 516. Units of Measurement The values given in parentheses (if provided) are not standard and may not be exact mathematical conversions. Use each system of units separately. Combining values from the two systems may result in nonconformance with the standard. 600-J, Chemical Test Procedures 14-2 TxDOT 08/02 07/05

3 Section 2 Apparatus Section 2 Apparatus The following apparatus is required: muffle furnace, 800 to 1100 C ( 1,472 to 2,012 F) oven, 100 C (212 F) balance, analytical magnetic stirrer desiccator hot plate Meeker burner filter papers, No. 2 and No. 42 Whatman or equals ph paper, range 8 to 9 platinum crucible volumetric flask, 500 ml (16.9 fl. oz.) beaker, 200 ml (6.76 fl. oz.) tall form beaker, 250 ml (8.5 fl. oz.) buret, 50 ml (1.7 fl. oz.) graduated cylinder, 25 ml (0.85 fl. oz.) filter funnel wash bottle. 600-J, Chemical Test Procedures 14-3 TxDOT 08/02 07/05

4 Section 3 Reagents Section 3 Reagents All reagents must be ACS reagent grade. Use deionized or distilled water to prepare solutions. Silver Nitrate Solution, 0.1 Normal. Standardize against a sodium chloride solution of known concentration Potassium Chromate Indicator Solution. Dissolve 50 g of potassium chromate (K 2 CrO 4 ) in 100 ml (3 fl. oz.) of water Nitric Acid (1+19). Mix 1 volume of concentrated nitric acid (70% by wt) with 19 volumes of water Sodium Hydroxide Solution (1 g/l). Dissolve 1 g of sodium hydroxide (NaOH, pellet form) in water and dilute to 100 ml (3 fl. oz.) Barium Chloride Solution, 10%. Dissolve 10 g of barium chloride (BaCl 2 2H 2 O) in 90 ml (3 fl. oz.) of water Hydrochloric Acid. Concentrated hydrochloric acid (HCl) (37% by wt.) 600-J, Chemical Test Procedures 14-4 TxDOT 08/02 07/05

5 Section 4 Procedures Section 4 Procedures Chloride Ion The following describes the steps required to determine chloride ion. Determining Chloride Ion Step Action 1 Filter 500 ml (16.9 fl. oz.) of the as-received water sample into a 500 ml (16.9 fl. oz.) volumetric flask using a No. 2 Whatman filter paper. 2 Weigh 50 g, to the nearest milligram, of the filtered sample into a 200 ml (7 fl. oz.) tall bottom beaker. 3 Adjust the sample ph to between 8 and 9 using nitric acid or sodium hydroxide solution. 4 Add 11 drops of the potassium chromate indicator and titrate using the silver nitrate solution in a 25 ml (0.85 fl. oz.) buret. 5 The end-point is reached when a brick-red color persists throughout the sample. Record the amount of silver nitrate solution used. 6 Determine the chloride ion concentration (weight percent) as indicated under 'Calculations.' Sulfate Ion The following describes the steps required to determine sulfate ion. Determining Sulfate Ion Step Action 1 Weigh 80 g, to the nearest milligram, of the filtered sample into a 250 ml (8.5 fl. oz.) beaker. 2 Add 10 ml (0.34 fl. oz.) of concentrated hydrochloric acid to the sample. 3 Heat to near boiling. 4 Add 25 ml (0.85 fl. oz.) of barium chloride solution and heat again for 10 minutes. 5 Remove from the hot plate and let cool for 15 minutes. 6 Filter through a No. 42 filter paper and wash the precipitate with hot water until the washings are free of chlorides, as indicated by testing the washings with silver nitrate. 7 Place the filter paper and precipitate in a weighed platinum crucible and dry in a 100 C (212 F) oven for 1 hour. 8 Remove crucible from oven and slowly char the paper to a white ash using a Meeker burner. 9 Place the crucible and residue into the muffle furnace at a temperature of 800 to 1100 C (1,472 to 2,012 F) for 1 hour 10 Cool in a desiccator and weigh. 11 Determine the concentration of sulfate as indicated under 'Calculations.' 600-J, Chemical Test Procedures 14-5 TxDOT 08/02 07/05

6 Section 5 Calculations Section 5 Calculations Use the following calculations to determine chloride ion concentration and sulfate concentration. Chloride Ion Concentration: % Chloride = VN / S Where: V = ml of silver nitrate solution N = normality of silver nitrate solution S = sample weight, grams. Sulfate Concentration: % Sulfate= R / S Where: R = residue weight, grams S = sample weight, grams. 600-J, Chemical Test Procedures 14-6 TxDOT 08/02 07/05

7 Section 6 Archived Versions Section 6 Archived Versions Archived versions of Test Method "Tex-619-J, Analysis of Water for Chloride and Sulfate Ions" are available through the following links: Click on for the test procedure effective August 1999 through July J, Chemical Test Procedures 14-7 TxDOT 08/02 07/05