GB/T 11892-1989Water quality. Determination of permanganate index (English PDF)

1.1 Subject

This Standard specified the method for determination of permanganate index in water.

1.2 Scope

This Standard is applicable to the determination of drinking water, water-source water and ground water. The determination scope is 0.5 ~ 4.5 mg/L. For heavy-polluted water, it shall take few water sample for determination after dilution.

This Standard is not applicable to the determination of the amount of organic pollution in industrial waste. If the determination is required, potassium dichromate can be used to determine the chemical oxygen demand.

The inorganic reducing substances in sample such as , S2- and Fe2+ can be determined. When chloride ion concentration is greater than 300 mg/L, it shall use the method for the determination of oxidation in alkaline media.

4.8 Potassium permanganate standard solution, concentration C3 (1/5

KMnO4) of about 0.01 mol/L. pipet 100 mL of potassium permanganate standard stock solution (4.7) in a 1000 mL volumetric flask; use water to dilute to the scale; well mix. This solution can be stored in the dark for several months. Use the same day to calibrate its concentration.

7.1 Pipet 100.0 mL of sample that has been thoroughly shaken and well

mixed (or pipet appropriate amount for several times; use water to dilute to 100 mL). Place in a 250 mL conical flask. Add 5 ± 0.5 mL of sulfuric acid (4.3).

Use a burette to add 10.00 mL of potassium permanganate standard solution (4.8). Shake well. Place the conical flask in a boiling water bath for 30 min (starts timing when water bath boils).

7.2 After removal, use a burette to add 10 mL of sodium oxalate solution

(4.6) till the solution turns colorless. When it is still heated, use potassium permanganate solution (4.8) to titrate till pink just appears and maintain for 30s. Record the volume of potassium permanganate solution consumed.

7.3 Blank test. use 100 mL of water to replace sample; determine according

to 7.1, 7.2; record the volume of potassium permanganate solution dropped (4.8).

7.4 Add 10.00 mL of sodium oxalate solution (4.6) into the solution that has

been titrated by the blank test (7.3). If necessary, heat the solution to 80°C.

Use potassium permanganate solution (4.8) to carry out the continuous titration till pink just appears and maintain for 30s. Record the volume of ......