Preliminary screening system for COD (chemical oxygen demand ) automatic test

Abstract

The invention discloses a preliminary screening system for COD (chemical oxygen demand) automatic test. The preliminary screening system comprises an upper computer, a first injection pump mechanism,a spectrophotometer, a reagent bottle, a chloride ion selection electrode and a control module, wherein the spectrophotometer is used for testing the light absorption value; the reagent bottle is usedfor storing a preliminary screening reaction reagent; the chloride ion selection electrode is used for testing voltage information in a sample bottle and transmitting the voltage information to the control module; the control module is used for receiving a control instruction of the upper computer and performing the following operations of (1) sending a control signal to the first injection pumpmechanism; taking 0.5mL of samples; adding 5mL of potassium dichromate solution and 8mL of sulfuric acid for reaction; (2) testing the light absorption value at 440nm; (3) performing calculation to obtain the chlorine-containing COD of the sample; (4) calculating the chlorine ion concentration of the sample and the chlorine ion conversion COD; (5) calculating the sample COD and updating the resultto the upper computer. The preliminary screening system belongs to an automatic system for performing fast screening on the COD of the chlorine-containing wastewater.

Description

technical field [0001] The invention relates to a COD automatic test equipment, in particular to a primary screening system suitable for the COD automatic test. Background technique [0002] Chemical oxygen demand (COD) is the amount of oxidant consumed when a certain strong oxidant is used to treat water samples under certain conditions. It is an important indicator of the amount of reducing substances in water. The reducing substances in water include various organic substances, nitrite, sulfide, ferrous salt, etc., but the main ones are organic substances. Therefore, chemical oxygen demand (COD) is often used as an index to measure the content of organic substances in water. The greater the COD, the more serious the water body is polluted by organic matter. The determination of chemical oxygen demand (COD) varies with the determination of reducing substances in water samples and the determination methods, and its measurement values ​​are also different. At present, th...

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Problems solved by technology

[0003] At present, there are automated equipment on the market to automatically test the chemical oxygen demand (COD), but none of them have realized the automatic preliminary screening of COD. During the test, it is necessary to pass the manual preliminary judgment before realizing the subsequent automatic test, so the COD has not been realized. Fully automated testing, COD automated primary screening is a lack of technology

In addition, the existing COD determination method, whether it is the reflux digestion method or the rapid closed digestion method, uses potassium dichromate as the oxidant, silver sulfate as the catalyst, and mercury sulfate as the chloride ion masking agent, and measures COD under sulfuric acid acidic conditions. All the methods of determination need to use a large amount of toxic and harmful reagents, the test cost is high, and it is not environmentally friendly.

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