High chloride wastewater COD (chemical oxygen demand) rapid determination method

Abstract

The invention discloses a high chloride wastewater COD (chemical oxygen demand) rapid determination method which comprises the following steps: 1, chloride ion concentration in a water sample is tested; 2, according to the chlorine content, distilled water is added for dilution of the water sample for controlling the chlorine content below 2000mg / L; 3, a COD digestion solution is prepared, to be more specific, 2.65 grams of potassium dichromate is dissolved in a mixed solution of 30 ml of concentrated sulfuric acid and 60 ml of distilled water, the distilled water is added for titrating to 100 ml, and the mixture is mixed with 500 ml of 1% sulfuric acid-silver sulfate solution for storing and standby use; 4, 5 ml of COD the digestion solution is added into the 5 ml of the diluted water sample, or 5ml of the distilled water is added into the 5 ml of the diluted water sample, the diluted water samples are respectively digested by a COD digestion device for 12-25 minutes, and the diluted water samples are cooled to room temperature; and 5, the digested solutions are filled into titration flasks, 2-3 drops of a phenanthroline-iron(II) indicator are added, the digested solutions are titrated by use of 0.05 mol per liter of ammonium ferrous sulfate solution until the solution turns red brown, titration volumes V0 and V1 are recorded, and the method can more fast and accurately detect COD.

Description

technical field [0001] The invention belongs to the technical field of waste water COD detection, in particular to a method for quickly measuring high chlorine waste water COD. Background technique [0002] The prior art is mainly the traditional potassium dichromate method and the determination of the chemical oxygen demand of water quality rapid digestion spectrophotometry. The traditional potassium dichromate method is: add a known amount of potassium dichromate solution to the sample, use silver sulfate as a catalyst in a strong acid medium, and titrate with ferrous ammonium sulfate solution after high temperature digestion. The determination of water quality chemical oxygen demand is different from the rapid digestion spectrophotometric method in that the colorimetric method is used to measure COD after digestion. Disadvantages: The concentration of chloride ions in industrial wastewater is high, which has a great impact on the experimental results. Although a certain ...

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Problems solved by technology

Disadvantages: The concentration of chloride ions in industrial wastewater is high, which has a great impact on the experimental results. Although a certain amount of masking agent has been added, the effect is not very good; sulfuric acid has strong chemical corrosion, and it is easy to splash during the addition process The potassium dichromate method needs to add sample, potassium dichromate, mercury sulfate, sulfuric acid-silver sulfate solution, and distilled water successively during digestion with potassium dichromate method. longer

The experimental results are not very satisfactory. After digestion, precipitation and turbidity will occur. After centrifugation, the supernatant is taken for testing. The experimental results have great deviations.

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