Determination of Oxidizability of Waste Water with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0431.100 Pt Titrode; input 1

Reagents
c(1/5KMnO4) = 0.01 mol/L; D0

Sample
25 mL waste water
5 mL w(H2SO4) = 0.35 (35%)
75 mL dist. water
15 mL c(1/5KMnO4) = 0.01 mol/L
15 mL c(1/2Oxalic acid) = 0.01 mol/L

Remarks
· Prepare sample as follows:
Add 75 mL dist. water and 5 mL w(H2SO4) = 0.35 (35%) to 25 mL of sample and heat up to a boiling mixture.

Add 15.00 mL of c(1/5KMnO4) = 0.01 mol/L and keep boiling for 10 minutes. Then add 15 mL c(1/2Oxalic acid) =0.01 mol/L.
Titrate with c(1/5KMnO4) = 0.01 mol/L according to parameters.

· Calculations:

Oxidiza.=EP1*C01*C02/C00;3;mg/L

Oxidiza. = oxidizability in mg/L permanganate consumption
C01 = molecular mass of KMnO4 * concentration of titrating agent / normality (158 * 0.01 / 5 = 0.316 g/L)
C02 = conversion g Þ mg for result expression in mg/L KMnO4 (1000)

. Answer

Oxidiza = 3.682 x 0.316 x 1000 / 25 = 46.540 mg/L

Literature
· Deutsche Einheitsverfahren zur Wasseruntersuchung Kapitel H4, Abschnitt 1