GB/T 22597-2014Determination of chemical oxygen demand of reclaimed wastewater - Potassium dichromate method (English PDF)

4.1

standard reagent, unless otherwise specified, shall use analytical reagent and in line with GB/T 6682 stipulated three of water.

4.2

Test preparations and products required, in the absence of other specified requirements, prepared according to GB/T 603's.

4.3

sulfate (H2SO4).

4.4

mercury sulfate (HgSO4).

4.5 manganese sulfate (MnSO4 · H2O) solution

50g/L.

4.6 ceric sulfate [Ce (SO4) 2 · 4H2O] solution

50g/L.

4.7 potassium hydrogen phthalate standard solution

Weigh 0.4251g advance at 105 °C ~ 110 °C dried to a constant reference reagent phthalic

Potassium bicarbonate, dissolved in water and diluted to 1000mL, and mix. And then diluted 10-fold to give the theoretical COD value of 50mg/L of standard solution.

4.8 Potassium dichromate standard solution

c (1/6K2Cr2O7) = 0.05000mol/L. Weigh 2.4516g ± 2 °C pre-dried at 120 °C

The constant reference to the reagent potassium dichromate, dissolved in water and quantitatively transferred to a 1000mL volumetric flask, dilute to the mark, shake spare.

4.9 ferrous ammonium sulfate standard titration solution

c [(NH4) 2Fe (SO4) 2 · 6H2O] ~0.020mol/L.

a) preparation. dissolve 8g ferrous ammonium sulfate [(NH4) 2Fe (SO4) 2 · 6H2O] in water, adding 20mL sulfuric acid, until the solution was cooled

It was diluted to 1000mL. Just before each use, accurately calibrated with standard potassium dichromate solution concentration of this solution.