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

A sequential injection and syringe pump technology, applied in the direction of analysis materials, instruments, etc., can solve the problems of high speed, high sampling frequency, large sample and reagent consumption, and large reagent consumption, so as to achieve low consumption and prolong life , increase the effect of retention time

Inactive Publication Date: 2004-03-10
XI AN JIAOTONG UNIV
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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

Method used

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

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Effect test

Embodiment

[0049] Embodiment: obtain from several sewage outlets such as factories, moats, etc., use 800 # After the sieve is filtered, the filtrate is divided into two parts, one part is sent to Shaanxi Provincial Environmental Monitoring Station for detection, and one part is used to monitor the chemical oxygen demand (COD) in environmental water on-line with the stop-flow-sequential injection of the present invention combined with cerium oxidation. method of monitoring.

[0050] According to the method of the present invention, the specific operation steps of the present invention are:

[0051] When the instrument just started measuring, the pump and valve were in a stopped state; at the first second, the valve turned to the water-carrier liquid 2 position; from the second to the 32nd second, the pump reversed to absorb the water-carrier liquid and then stopped; at the 34th second, the valve Turn to the position of sample 1; from 35 seconds to 36 seconds, the pump reverses to suck th...

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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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N35/00G01N35/08
Inventor 梁恒武亚艳
Owner XI AN JIAOTONG UNIV
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