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.

What is an oxidizable compound?

Definition. Substance that can undergo a chemical reaction with oxygen.

What is the difference between BOD and COD?

Biochemical oxygen demand (BOD) is the amount of oxygen required by the microorganisms to break down the organic materials, whereas chemical oxygen demand (COD) is the amount of oxygen required to break down the organic material via oxidation.

What should be the COD of drinking water?

According to standards of Central Pollution Control Board, permissible value of BOD is 30 mg/l and COD is 250 mg/l. Hope this helps, it mentions standards for India relating to different uses.

Why sulphuric acid is used in COD?

Chemical Oxygen Demand (COD) 1% Silver Sulphate in Sulphuric Acid (conc.) provides the primary and secondary digestion catalysts for oxidation of carbon during chemical oxidation.

Why potassium dichromate is used in COD?

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.

What is meant by over oxidation?

Noun. overoxidation (usually uncountable, plural overoxidations) Excessive oxidation (or to a greater than normal extent)

What are the advantages of COD over BOD?

COD is normally higher than BOD because more organic compounds can be chemically oxidised than biologically oxidised. This includes chemicals toxic to biological life, which can make COD tests very useful when testing industrial sewage as they will not be captured by BOD testing.

What is mean by BOD and COD?

The biochemical oxygen demand (BOD) represents the amount of dissolved oxygen (DO) consumed by biological organisms when they decompose organic matter in water. The chemical oxygen demand (COD) is the amount of oxygen consumed when the water sample is chemically oxidised.

What is good COD level?

Influent COD in normal domestic sewage is therefore generally 600 – 900 mg/l and it is then treated to at least 75 -100 mg/l before discharge to minimise pollution potential.

What is a high COD value?

Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen (DO) levels. A reduction in DO can lead to anaerobic conditions, which is deleterious to higher aquatic life forms.

Why K2Cr2O7 is used in COD measurement?

Which method is used for COD?

The traditional chemical oxygen demand (COD) analysis method is the wet chemistry method. This involves a two hour digestion at high heat under acidic conditions in which potassium dichromate acts as the oxidant for any organic material present in a water sample.

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.

What is the difference between oxidation and oxidizing agent?

The substance that loses electrons is being oxidized and is the reducing agent. The substance that gains electrons is being reduced and is the oxidizing agent….8.2: Oxidizing and Reducing Agents.

	Oxidizing Agents	Reducing Agents
Oxidation State	Decreases	Increases
# of Electrons	Gained	Lost
Substance is…	Reduced	Oxidized

What is difference between reduction and oxidation?

When reduction oxidation reactions occur simultaneously it is called as redox reaction or reduction- oxidation reaction. These are balanced chemical reactions….Reduction:

Difference between Oxidation and Reduction
OXIDATION	REDUCTION
Losing electrons	Gaining electrons
Increase in oxidation number	Decrease in oxidation number

What is the difference between BOD and CBOD?

BOD results are based on DO depletion from both carbonaceous and nitrogenous actors in a wastewater sample. CBOD measures DO depletion from only carbonaceous sources. Regulators may assign either BOD or CBOD, or both, to wastewater treatment facilities.

What is the limitation of COD test?

One of the main limitations of the COD test is its inability to differentiate between biodegradable and biologically inert organic matter on its own. The use of chemicals such as chromium and strong acids produce hazardous liquid waste, which requires careful disposal.