Method for analyzing content of COD (chemical oxygen demand) in sewage with high chloride ion concentration

A technology of chloride ion content and ion concentration, which is applied in the direction of material analysis by observing the influence of chemical indicators, analysis by making materials undergo chemical reactions, preparation of test samples, etc., can solve the negative deviation of results and the measurement results High, can not truly reflect the chemical oxygen demand of sewage and other problems, to reduce the impact, eliminate the interference of accuracy, and improve the effect of accuracy

Inactive Publication Date: 2014-03-19
南京中锗科技有限责任公司
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Problems solved by technology

[0003] There are many methods for analyzing chemical oxygen demand (COD), such as potassium dichromate method, potassium permanganate method and rapid closed catalytic digestion method, etc., but with these methods, the measurement results are much higher for sewage with high chlorine content It cannot truly reflect the content of chemical oxygen demand (COD) in sewage, and is not suitable for the determination of sewage soluti

Method used

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Embodiment

[0008] Embodiment: a kind of analytical method of COD content in high chloride ion concentration sewage, comprises the following steps:

[0009] (1) Draw 5mL of a sample with a high chloride ion concentration, add a standard solution of potassium hydrogen phthalate with a COD theoretical value of 1000mg / L, and 5mL of 1mol / L AgNO 3 The solution was mixed and shaken, precipitated, diluted with water, adjusted to 25mL, centrifuged, and then 3mL of the supernatant was placed in a clean digestion tube, and 1mL of mercuric sulfate solution with a mass fraction of 10%, 1mL of 0.025mol / L Potassium dichromate oxidant solution and 5mL sulfuric acid-silver sulfate catalyst solution with a mass fraction of 1%, shake well with a stopper, at this time there should be no white precipitate, to ensure complete removal of chloride ions;

[0010] (2) Insert the digestion tubes into the holes of the digestion furnace one by one, cover with a protective cover, set the digestion temperature to 165°...

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Abstract

The invention discloses a method for analyzing the content of COD (chemical oxygen demand) in sewage with high chloride ion concentration. The method comprises the following steps: adding 5ml of 1mol/L silver nitrate solution into a sewage sample, mixing, uniformly shaking, precipitating, adding water for dilution till 25mL, performing centrifugal separation, taking 3mL of supernatant liquid, placing into a digestion pipe, adding 1mL of 10% mercury sulfate solution, 1mL of 0.025mol/L potassium dichromate oxidant solution and 5mL of 1% sulfuric acid-silver sulfate catalyst solution, plugging, uniformly shaking, digesting for 15min, taking out, cooling, and determining the COD content in the sample by applying a colorimetric method. According to the method, a silver salt precipitation method and a dilution method are combined and applied, AgNO3 is added into the chlorine-containing sewage sample to precipitate the chloride ions and further eliminate the interference of the chloride ions on the accuracy of COD determination result, the dilution method is further adopted to reduce the influence of nitrate radicals introduced by silver nitrate on an analytical system, the method is suitable for analyzing the content of COD in the sewage sample with the chlorine content of 1200-10000mg/L, and the accuracy in detection result is greatly improved.

Description

technical field [0001] The invention relates to a method for measuring COD content, in particular to an analysis method for COD content in sewage with high chloride ion concentration. Background technique [0002] Chemical oxygen demand (COD) refers to the amount of oxidant consumed when reducing substances in water are oxidized and decomposed under the action of an external strengthening oxidant under certain strict conditions, expressed in mg / L of oxygen. COD reflects the degree of water pollution by reducing substances, including organic matter, nitrite, ferrous salt, sulfide, etc. In general, the amount of inorganic reducing substances in water and wastewater is relatively small, but it is very common to be polluted by organic substances. Therefore, COD can be used as a comprehensive indicator of the relative content of organic substances. [0003] There are many methods for analyzing chemical oxygen demand (COD), such as potassium dichromate method, potassium permangan...

Claims

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Application Information

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IPC IPC(8): G01N21/78G01N1/34
Inventor 郑华荣刘英杰俞义海柯尊斌
Owner 南京中锗科技有限责任公司
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