i have be trying to find the COD by using Dichromate and i found that the values of COD are coming in multiples of 4 i.e., 16,32,48,64,96.....which i find very absurd?What may be the possible cause for such results and i also wanted to know if there is any alternative to this?
Hi Ong
Me too I have a problem with determination of COD.
I calculated by open reflux method.
The Protocol is bellowing:
In a test tube:
- 2.5 ml of sample
- 3.5 ml of sulfuric acid 36 N
-1.5 ml Potassium bichromate
After we have put the heating tubes in a 150 ° c for 2 hours. after it is done by titration Sel Mohr in the presence of the indicator color feroine.
My problem is haw i will prepare solution of Bichromate.
Hi Ong... With troublesome samples we may try dividing the sample and give to two different chemist to do the analysis using the same procedure. You may then discover the causes of any discrepancy. Any how chemical procedures like the COD are reliable and rarely suffer from problems. Readily available kits like that of Hach may reduce the human factor in the error... Regards..
Thanks Kaja For your answer
Yes but how much of Ag2SO4 and HgSO4? because it is necessary this products
Thanks again
Plz refer APHA procedures to avoid as for as possible experimental procedures. If the COD value is very high, dilute the sample and perform the experiment.
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