How do you make sulphuric acid reagent for COD?

1.84): Concentrated H2SO4. 7.1 Pipet a 50.0 mL aliquot of sample not to exceed 800 mg/L of COD into a 500 ml, flat bottom, Erlenmeyer flask. Add HgSO4 (6.4) in the ratio of 10 mg to 1 mg chloride, based upon the mg of chloride in the sample aliquot and 5 mL of sulfuric acid (6.7).

Which reagent is used for COD analysis?

potassium dichromate (K2Cr2O7)
The most general COD determination uses potassium dichromate (K2Cr2O7) in excess in an acidic medium with the aid of silver sulfate (Ag2SO4) as a catalyst, and mercuric sulfate (HgSO4) added to remove interference of chlorides.

What is the chemical oxidant used for the COD test?

The COD is often measured using a strong oxidant (e.g. potassium dichromate, potassium iodate, potassium permanganate) under acidic conditions.

Why FAS is used in COD?

In the titration method for determining COD, the excess dichromate is reacted with a reducing agent, ferrous ammonium sulfate. As the ferrous ammonium sulfate (FAS) is added slowly, the excess dichromate is converted into its trivalent form. As soon as all the excess dichromate reacts, an equivalence point is reached.

Which indicator is used in COD?

Most commonly, a 0.25 N solution of potassium dichromate is used for COD determination, although for samples with COD below 50 mg/L, a lower concentration of potassium dichromate is preferred.

Which COD oxidizing agent needed?

potassium dichromate
COD is measured via a laboratory assay in which a sample is incubated with a strong chemical oxidant for a specified time interval and at constant temperature (usually 2 h at 150°C). The most commonly used oxidant is potassium dichromate, which is used in combination with boiling sulphuric acid.

Which indicator is used for COD?

Using potassium dichromate . Most commonly, a 0.25 N solution of potassium dichromate is used for COD determination, although for samples with COD below 50 mg/L, a lower concentration of potassium dichromate is preferred.

How do you test for COD?

COD is measured via a laboratory assay in which a sample is incubated with a strong chemical oxidant for a specified time interval and at constant temperature (usually 2 h at 150°C). The most commonly used oxidant is potassium dichromate, which is used in combination with boiling sulphuric acid.

Why k2cr2o7 is used in COD measurement?

Currently, most COD tests use potassium dichromate as the oxidant. Potassium dichromate is a hexavalent chromium salt that is bright orange in color and is a very strong oxidant. Between 95-100% of organic material can be oxidized by dichromate.

How do you check for COD?

Why potassium dichromate is used in COD?

What is COD method?

COD measures how much DO is consumed by the oxidation of organic matter and inorganic compounds such as ammonia or nitrite under controlled conditions. COD testing typically involves digestion of the water sample in a sealed vial with potassium dichromate and sulfuric acid at 150C for 2 hours.

How do you treat high COD?

You can reduce COD and BOD by adding hydrogen peroxide to the wastewater solution. The hydrogen peroxide will chemically attack the organics in the wastewater, degrading them and reducing the measured COD and BOD.

How is high COD effluent treated?

There are various proven methods for COD reduction in wastewater management. Two of the most common techniques for COD wastewater removal are: Wastewater separation (coagulation and flocculation) COD removal by microbial action.

Which is used as indicator in COD?

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