AWWA B403-16 pdf download.Aluminum Sulfate—Liquid, Ground, or Lump
5.5.10.1 The computation given for the quantity of sulfuric acid to be added to acidifed alum solutions will result in the addition of 0 to 19 drops of the 1:1 acid for alums being produced currently. If a particular computation should result in a small negative value for the number of drops (that is, one to three), the number of drops to be added is taken as zero. If a signifcant negative value (that is, four or more drops) results from the computation, add three drops of 6N NaOH solution for each drop of 1:1 H 2 SO 4 computed.
5.5.10.2 Te aliquot of sample solution used for titration should contain 0.110 to 0.125 g of aluminum calculated as Al 2 O 3 . If too large a sample size is taken for the test, the color change may occur when the frst drop of zinc sulfate is added. In this event, rerun the analysis using a 25-mL aliquot of the prepared sample solution.
5.5.10.3 Te sample solution, the added standard excess EDTA solution, and the ammonium acetate bufer solution are boiled together to ensure quantita- tive complexation of the aluminum with EDTA. A boiling time of 2 to 3 minutes is adequate. Close control over the volume of liquid is not required; however, do not let the sample evaporate to dryness.
5.6.3.1 To a 100-mL volumetric fask, using a pipette, add 1.00 mL of 0.10 mg Fe/mL standard iron solution, 50 mL of water, 10.0 mL of 1:1 sulfuric acid, and 1 percent potassium permanganate, drop by drop, to obtain a persistent pink color. Add 10.0 mL of 10 percent potassium thiocyanate and dilute to the mark. Measure in a spectrophotometer at 475 nm within 10 minutes against a blank. Prepare the blank solution by transferring 10 mL of a 10 percent potas- sium thiocyanate solution and 10 mL of 1:1 sulfuric acid to a 100-mL volumetric fask. Dilute to the mark with water and mix.AWWA B403-16 pdf download.