What is the difference between COD and Permanganate Index?
The difference between cod and permanganate index is: cod is an index representing two methods, and permanganate index is one of them.
COD includes manganese method and chromium method. Permanganate index refers to the detection value of manganese method.
The permanganate index is mainly used to measure low-concentration COD, which is used for the detection of tap water and deep well water. The COD of this type of water is very low <5mg.l, and an accurate value cannot be measured by the chromium method. The high concentration of COD is mostly detected by the chromium method.
Introduction to Permanganate Index
In the past water quality monitoring and analysis, there is also a potassium permanganate method called chemical oxygen demand. However, because this method can only partially oxidize the organic matter in the water under the specified conditions, it is not a theoretical oxygen demand, nor is it a measure of the total organic matter content in the water body. Therefore, the term permanganate index is used. As an indicator of water quality, the chemical oxygen demand, which is different from the potassium dichromate method, is more in line with objective reality.
The chemical oxygen consumption measured with potassium permanganate solution as the oxidant was formerly known as the chemical oxygen consumption of manganese method. In my country's new environmental water quality standards, this value has been renamed the permanganate index, and only the value measured by the acid potassium dichromate method is called the chemical oxygen demand. The International Organization for Standardization (ISO) recommends that the potassium permanganate method is limited to the determination of surface water, drinking water and domestic sewage, and is not applicable to industrial wastewater.
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