In water quality analysis, cod is a common detection parameter, which reflects the pollution degree of water by reducing substances, mainly including nitrite, ferrous salt, organic matter and sulfide. The main purpose of COD determination is to measure the content of organic matter in water. The larger the COD, the more serious the pollution of water body. At present, the common methods of COD water quality analysis are potassium dichromate oxidation method and acid potassium permanganate oxidation method. However, potassium permanganate method is suitable for the determination of cleaner water sources. Generally, the domestic and industrial sewage with serious pollution uses dichromate Potassium oxidation method.
Advantages of common methods for COD water quality analysis
The advantage of potassium dichromate oxidation method in the analysis of COD is that potassium dichromate is easy to purify, can be made into reference material after drying, can be directly prepared with standard solution, the concentration can be kept unchanged for a long time, it can be titrated in hydrochloric acid medium, but the oxidation effect of aromatic organic matter is not obvious.
The advantage of acid potassium permanganate oxidation method is its strong oxidation ability, which can directly or indirectly determine a variety of inorganic and organic substances under different conditions, but the disadvantage is that it can not be placed for a long time and needs to be calibrated frequently.
Monitoring indexes of COD parameters in water quality
The results of the quantitative method of COD vary with the type and concentration of oxidant, solution acidity, reaction temperature, time and catalyst. Moreover, under the same conditions, the oxidation degree varies with the type and concentration of reducing substances in water. Therefore, cod is a conditional index and must be carried out in strict accordance with the operation steps.
