The permanganate index, similar to COD, is an indicator reflecting the relative content of organic matter in water. But what kinds of water samples adopt permanganate index testing for water quality assessment? Let’s take a brief look together with a water quality online monitor manufacturer.

For permanganate index measurement, this test is applied to water samples with relatively low chemical oxygen demand, such as tap water, well water and other clean water sources. Potassium permanganate is used to oxidize organic matter and certain inorganic substances in water samples, and the measured data are used to evaluate water quality. In comparison, wastewater and other unclean water samples are analyzed by COD testing.

There are multiple methods to test permanganate index in water, and various types of monitors are available, including laboratory units, probe-type monitors and online analyzers. Users may select suitable equipment according to actual needs.

Hangzhou Modi has independently developed an online analyzer for permanganate index. This online monitoring device conducts real-time permanganate index measurement in water using the potassium permanganate colorimetric method.

After filtration, water samples are fed into the reaction tank. The heating system is controlled, and proper amounts of potassium permanganate and concentrated sulfuric acid are sequentially added into the reaction tank for digestion at 100°C. Based on raw water conditions, the digested sample is cooled for an appropriate duration before optical detection. The permanganate index concentration of the tested water is calculated by measuring absorbance.

The potassium permanganate colorimetric method for permanganate index testing includes acidic and alkaline approaches. The acidic method applies to routine surface water and groundwater monitoring. The alkaline method is suitable for industrial seawater and other common water bodies.