Definition and scope of application
Permanganate index refers to the amount consumed in the treatment of water samples in acid or alkaline medium with potassium permanganate as oxidant, expressed in mg / L of oxygen. Potassium permanganate can be consumed by reducing inorganic substances such as nitrite, ferrous salt and sulfide in water and organic substances that can be oxidized under this condition. Therefore, permanganate index is often used as a comprehensive indicator of the pollution degree of surface water by organic pollutants and reducing inorganic substances.
This method is applicable to surface water, groundwater, domestic sewage and industrial wastewater
When the volume of water sample is 20ml and the diameter of 25 mm colorimetric tube is used, when the permanganate index of water sample is more than 10.0mg/l, a small number of samples shall be divided as appropriate, and the determination shall be carried out after dilution with water.
After adding sulfuric acid to the water sample to make it acidic, add excess potassium permanganate to oxidize the reducing substance in the water, and heat it in the boiling water bath for a certain time. Because potassium permanganate is purple red, the content of the remaining potassium permanganate is determined by spectrophotometry, the standard curve of CODMn and absorbance is established, and the CODMn of the water sample is calculated by the curve.
The CODMn test method developed by Shenzhen Changhong science and Technology Co., Ltd. (hereinafter referred to as "shenchanghong") is simple, fast and economic in operation, with accurate and reliable test results. Shenchanghong can provide a complete analysis scheme of CODMn test method, and users do not need to prepare their own CODMn reagents. The scheme includes CODMn analyzer, CODMn reagent and so on. CODMn reagent is used together with CODMn analyzer. The analytical procedure is simple and convenient, which meets the requirements of national industry standards.
● there is no need to prepare CODMn reagent: the reagent prepared by a certain proportion of chemical components required for CODMn analysis can greatly save the preparation time of CODMn reagent;
● time saving: the whole analysis process, including water sampling, colorimetric determination and other steps, takes much less time than traditional methods;
● simple operation and easy to learn: the operation guide with pictures and texts is convenient for mastering the analysis method of CODMn in a short time.
Analysis steps of total chromium micro reflux method of shenchanghong:
(1) Preparation of CODMn reagent and water sample
Each CODMn tube is filled with the reagents required for CODMn analysis. According to the instructions, add a proper amount of water sample, and then tighten the cap.
(2) Water Bath Digestion
Put the digestion colorimetric tube that has been added with water sample and reagent into the water bath pot, select the appropriate water bath temperature and time according to the requirements of reagent for digestion, take out the CODMn test tube from the water bath pot after the digestion process, and cool it to room temperature.
(3) CODMn colorimetric determination
The CODMn tester of shenchanghong (chcm-101 / mulp-8a / C / D / pmulp-4c / 8C / mulp-4b / gw-2000 / chmm-900, etc.) selects the corresponding CODMn test program in the main menu, does not need to re-establish the standard curve, only needs to put the digested CODMn test tube into the instrument to read the CODMn value expressed in concentration units, and can save the record results.