Method for on-line monitoring COD in water by stopping flow-sequential injection-cerium oxidation

Abstract

The present invention relates to one in-situ automatic water COD monitoring method including sequential injection, flow stopping, sandwich sampling and other technological process. The SI process has the features of autoamtic measurement, fast speed, good repeatability, etc., cerium oxidant with less pollution and milk reaction condition is used, and the flow stopping and sandwich sampling processes have improve reaction stability and sensitivity. The combination of the said process makes the monitoring of enviroment water COD measurement simple, autoamtic, fast, wide in linear range, good in repeatability, high in stability, high in sensitivity, low in cost and suitable for monitoring domestic sewage, river and lake water and industrial sewage.

Description

[0001] 1. Field [0002] The invention relates to an automatic on-line monitoring method of chemical oxygen demand (COD) in environmental water, and further relates to a method for on-line monitoring of chemical oxygen demand (COD) in environmental water combined with stop-flow-sequential injection and cerium oxidation. 2. Background technology [0003] At present, the automatic monitoring methods for COD in environmental water in domestic and foreign literature and patents mainly include: coulometric automatic titrator based on titration and photometric detector based on flow injection (FI). Potassium chromate, potassium permanganate and cerium oxidation. The coulometric automatic titration method consumes a lot of samples and reagents and takes a long time; the FI method has relatively high measurement speed and sampling frequency, and the main problem at present is the poor stability of long-term operation, especially the used The peristaltic pump must frequently replace t...

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Problems solved by technology

The coulometric automatic titration method consumes a lot of samples and reagents and takes a long time; the FI method has relatively high measurement speed and sampling frequency, and the main problem at present is the poor stability of long-term operation, especially the used The peristaltic pump must frequently replace the pump tube, and the consumption of reagents during operation is relatively large, which causes secondary pollution that cannot be ignored

[0005] Although the above literatures mentioned about sequential injection, chemical oxygen demand, stopped flow, cerium oxidant, etc., most of the literatures mainly used the FI method, even the combination of stopped flow-reverse flow injection analysis and cerium oxidation, but There are no domestic and foreign literature reports on the use of stop-flow-sequential injection (SI) system for continuous determination of COD

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