Water quality COD specific detection method
In daily reference to the COD water quality tester, many people think that this parameter has little effect on water quality, so the instrument is not very useful. It is felt that the chemical oxygen demand has the most influence on animals and plants in the water. The interference to our daily water use is relatively small, but we tell you that this idea is wrong, because if the chemical oxygen demand is too high, it will lead to the death of aquatic organisms, and they will be born after the death due to low oxygen. Some toxic substances affect the overall water quality. Therefore, it is very important to understand the COD parameters on a daily basis.
Water quality COD specific detection method
COD can measure organic matter by using chemical oxidants. It is important to use a sufficiently strong oxidant to react with almost all organic matter in the sample. Historically, potassium permanganate has played this role, but its ability to oxidize all organic matter in various waste samples has been found to be inconsistent.
Most COD tests currently use potassium dichromate as the oxidant. Potassium dichromate is a hexavalent chromium salt with a bright color and is a very strong oxidant. 95-100% of the organic matter can be oxidized by dichromate. Once dichromate oxidizes a substance, it converts to trivalent chromium, which is a dull green color.
The sample was digested with a quantity of oxidant, sulfuric acid and heating at 150 °C. Metal salts typically include inhibition of any interference and catalytic digestion. Digestion usually takes two hours to complete.
There must be an excess of oxidant during the digestion process; this ensures complete oxidation of the sample. It is therefore important to determine the amount of excess oxidant. The two most common methods are titration and colorimetry.
Which water quality COD detection method is best for me?
Although both methods have been time-tested, they have their pros and cons.
Titration is less intensive equipment because the only equipment you need is the burette, heating block and digestion vial. However, this process requires more labor. An automatic titrator can reduce the amount of user input required and other applications that can be used in wastewater.
Although colorimetry requires a spectrophotometer or photometer, the digester. However, as most manufacturers provide, the LABII brand cod reagent, ammonia nitrogen reagent, provided by Zhejiang Ditexi Technology. All you have to do is run your sample with digestive juice and minimal contact.
Colorimetry also makes measurements simple, convenient, and efficient. Because the analyst needs to do the digestion of the sample, let the water quality testing instrument work. For these reasons colorimetry is the most common method of measuring COD.
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