Determination of Oxidizability of Waste with Potentiometric Method

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

Method documentation

'pa
751 GPD Titrino 15215 751.0010
MET U Oxidiza.
parameters
>titration parameters
V step 0.10 ml
dos.rate max. ml/min
signal drift 20 mV/min
equilibr.time 38 s
start V: OFF
pause 0 s
dos.element: internal D0
meas.input: 1
temperature 25.0 °C
>stop conditions
stop V: abs.
stop V 7.5 ml
stop U OFF mV
stop EP 9
filling rate max. ml/min
>statistics
status: OFF
>evaluation
EPC 30 mV
EP recognition: all
fix EP1 at U OFF mV
pK/HNP: OFF
>preselections
req.ident: OFF
req.smpl size: OFF
activate pulse: OFF
------------
'fm
751 GPD Titrino 15215 751.0010
MET U Oxidiza.
>calculations

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

C00= 25
C01= 0.316
C02= 1000
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) -174 mV MET U Oxidiza.
smpl size 25 ml
EP1 3.682 ml -437 mV
Oxidiza. 46.540 mg/L
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml MET U Oxidiza.
1.0 ml/div dU=100.0 mV/div
============