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OCR for page 30
30 Name: FERRIC CHLORIDE CAS No.: 7705-08-0 Chemical Formula: FeC13 - Description: NAS/CWTC 012-82 Formula Weight: 162.3 Dark brown to yellow lumps or crystals. Solids are very hydroscopic. Solutions are corrosive. Usually available as a dark orange-brown liquid containing approximately 30% FeC13 by weight in water. May also be obtained as dark crystals with the formula FeC13 6H2O. Use: Used in coagulation. Purity Requirements: The RMIC values are based on a maximum dosage of 60 mg of ferric chloride/liter of water and are to be compared to impurity concentrations obtained by using sample proce- dures described in this monograph. If the actual dosage is other than 60 mg/liter, the user is cautioned to consult Table 2 for appropriate RMIC values. Impurity Arsenic Cadmium Chromium Lead Mercury Selenium Silver RMIC mg Impurity/kg Ferric Chloride 80 20 80 80 20 80

OCR for page 30
31 Bulk Sample Collection: Sample in accordance with Standard for Alum, AWWA B403-82, American Water Works Association, Denver, Colorado (1982). Analytical Sample Preparation: In preparing samples, use acid-washed glassware and make all dilutions with deionized distilled water. Weigh 0.6 g of ferric chloride (dry weight basis), dissolve, and make up to 1 liter in a volumetric flask. Transfer the solution to a 1.5-liter beaker, add 1 N NaOH dropwise with constant stirring to adjust to pH 6. Mix well, let stand for 1 hour, and filter through a GF/C filter (or equivalent) with vacuum. Quantitatively transfer filtrate into a beaker, adjust to pH 2 or less with concentrated HNO3, and evaporate on a hot plate, without boiling, to reduce the volume to less than 1 liter. Cool, quantita- tively transfer to a 1-liter volumetric flask, and make up to volume. Similarly treat a reagent blank. Sample Analyses: The analyses are to be performed on the ferric chloride solution in accordance with: Standard Methods for the Examination of Water and Waste- water, 15th Edition, American Public Health Association, Washington, D.C. (1981). Arsenic Cadmium Chromium Lead Mercury Selenium Silver Section 304 Section 304 Section 304 Section 304 Section 303F Section 304 Section 304