Air flow-back detection method for chemical oxygen demand (COD) in water

Abstract

The invention relates to an air flow-back detection method for chemical oxygen demand (COD) in water. The method comprises the following steps of: adjusting the temperature of a COD constant temperature heater to between 170 and 180 DEG C; putting a water sample in a heating tube; simultaneously adding potassium dichromate standard solution, solution of sulfuric acid-silver sulfate and a plurality of small explosion-proof ceramic pieces into the heating tube and slightly shaking the heating tube; connecting a condensation tube to the heating tube; placing the heating tube in a heating hole to heat; flowing back the solution for 2 hours after boiling; taking the heating tube and the condensation tube out and naturally cooling the tubes; washing the wall and the ground of the condensation tube with pure water; taking the condensation tube down and adding the condensation tube into a stirrer; adding water to 140ml and performing electromagnetic stirring on the solution; adding a phenanthroline indicator into the solution dropwise; titrating the solution with solution of ammonium ferrous sulfate; finishing the titration when the color of the solution changes from yellow to blue to red brown; and recording the consumed volume of the solution of ammonium ferrous sulfate. The COD constant temperature heater adopted by the method has the advantages of small occupied space, constant temperature, simple maintenance, reliable performance, safe use and high detection accuracy.

Description

technical field [0001] The invention relates to an air backflow detection method for chemical oxygen demand in water. Background technique [0002] Chemical oxygen demand means the amount of oxygen required by potassium dichromate to oxidize organic matter in one liter of sewage under strong acid heating conditions, which can roughly indicate the relative content of organic matter in sewage. COD index is an important index of organic pollution of water body, which can reflect the pollution degree of water body by reducing substances. [0003] The so-called 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 indicator of the amount of reducing substances in water. Reducing substances in water include various organic matter, nitrite, sulfide, ferrous salt, etc. But mostly organic matter. Therefore, chemical oxygen demand (COD) is often used as an index to measure the ...

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Problems solved by technology

[0006] 1. The reflow device adopts an all-glass reflow device with a huge structure;

[0007] 2. The reflow device is heated by a 600-800W electric furnace, and the heating is uneven;

[0008] 3. It is necessary to manually add silver sulfate-sulfuric acid reagent from the upper end of the condensation tube, and concentrated sulfuric acid is a strong corrosive liquid, which may pose a safety threat to the testing personnel

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