Method for measuring seawater chemical oxygen demand by photometry

Abstract

The invention discloses a photometric method for measuring the chemical oxygen demand of seawater. In the method, the seawater sample is firstly pretreated, and then the alkaline potassium permanganate is used as the reaction system, so that the organic matter in the seawater is strongly alkaline Rapid reaction with excess potassium permanganate in the medium, potassium permanganate is quantitatively reduced by organic matter to generate manganate, with pure water or a blank solution as a reference, measure its absorbance A at the maximum absorption wavelength of manganate at 430nm , the absorbance A has a positive correlation with the content of organic matter in the seawater sample. Draw the working curve of A~COD value, and the concentration of organic matter in seawater can be obtained through the working curve according to the absorbance value, that is, the COD value of seawater. The method is easy to operate, fast and accurate, reduces environmental pollution, and can easily realize the automation of seawater COD measurement.

Description

technical field [0001] The present invention relates to a method for measuring chemical oxygen demand (Chemical Oxygen Demand, sometimes abbreviated as COD hereinafter), in particular to a method for measuring seawater chemical oxygen demand by photometry. Background technique [0002] The chemical oxygen demand of seawater is a comprehensive index to characterize the pollution of seawater by organic matter, and it is a basic environmental ecological element to measure the quality of seawater. At present, the standard determination method of seawater COD in my country is the alkaline potassium permanganate method (GB17378.4-1998). This method is to react the seawater sample with excess potassium permanganate under heating conditions in an alkaline medium. The organic matter in seawater quantitatively reduces potassium permanganate to manganate. Then add sulfuric acid to acidify, then add solid potassium iodide to reduce the remaining potassium permanganate and the generated ...

AI Technical Summary

Problems solved by technology

It can be seen that this method is cumbersome to operate, time-consuming and labor-intensive, coupled with the strong corrosiveness of the reaction system, etc., and is not suitable for rapid on-site monitoring of seawater COD. It is of great significance to improve the working environment, especially the establishment of my country's coastal pollution / ecological environment monitoring network, to meet the needs of the national digital ocean technology support system, and to maintain the sustainable development of the marine economy.

Images