Rapid determination method of CODmn in water

Abstract

The invention discloses a rapid determination method of CODmn in water. The method is a spectrophotometric method for determining CODmn in water by using a sodium oxalate solution as a standard solution, comprising the following detection steps of: (1) preparing 0.05 mol / L of the sodium oxalate standard solution; (2) preparing a detection reagent; (3) drafting a calibration curve; (4) performing water sample colorimetric determination; and (5) calculating the concentration of CODmn in the water sample to be measured in the calibration curve obtained in the step (3) according to absorbance detected in the step (4). The invention has the following advantages: the detection steps are simple; the standard solution can be preserved for more than six months at normal temperature; the oxidation efficiency is high; and in comparison with the results of a national standard titration method, relative standard deviation is little and the detection cost is low in the invention.

Description

technical field [0001] The invention relates to an environment monitoring method, in particular to a method capable of rapidly measuring CODmn content in water. Background technique [0002] CODmn, also known as potassium permanganate index / oxygen consumption, is a comprehensive indicator that reflects the degree of pollution of surface water by organic pollutants and reducing inorganic substances, and is an important indicator to measure environmental quality. The latest version of the "Drinking Water Sanitation Standard" "(GB5749-2006) sets oxygen consumption as a routine water quality inspection index. Basically, all water quality monitoring agencies have to test this item every day. At present, in the determination of freshwater CODmn, the commonly used method is acidic potassium permanganate. determined by titration. These titration methods have some disadvantages, such as frequent calibration of the reagents, cumbersome operation, high requirements for the operator’s ...

AI Technical Summary

Problems solved by technology

Because glucose and potassium hydrogen phthalate can not be fully oxidized by potassium permanganate, the efficiency of being oxidized is a fluctuation range when participating in the reaction, so the correlation of its standard curve is poor when the two substances are made into standard solution. This directly affects the accuracy of CODmn test results

The standard solution prepared by using the above two substances can only be stored in the refrigerator for about one to two months, and the oxidation efficiency is low. The oxidation efficiency of the standard solution prepared with glucose is only 50%-60%, and the standard solution prepared with potassium hydrogen phthalate The solution oxidation efficiency is only 10%-20%, and the relative standard deviation of the spectrophotometric method using the above two reagents and the national standard titration method can reach 30% to 40%.

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