Analysis method for detecting chemical oxygen demand in water

A chemical oxygen demand and analysis method technology, applied in the field of water quality detection and analysis, can solve the problems of COD time-consuming, low efficiency, inability to measure a large number of samples at the same time, etc. Effect

Inactive Publication Date: 2017-07-07
CHENGDU MEIFUTE MEMBRANE TECHNOLOGY CO LTD
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Problems solved by technology

[0004] In the process of measuring COD by the above-mentioned potassium dichromate method, it takes a certain time for pretreatment, sampling, and dilution of water samples in the early stage, and the heating and reflux time is 2 hours. time, then the en

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  • Analysis method for detecting chemical oxygen demand in water

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Embodiment 1

[0040] Embodiment 1: an analytical method for detecting chemical oxygen demand in water, it comprises the following steps:

[0041] (1) Take 20.0mL of 500mg / L COD equivalent potassium hydrogen phthalate standard solution and place it in the reaction vessel, add 0.4g of mercury sulfate and stir until the mercury sulfate is completely dissolved;

[0042] (2) Add 10mL of 0.25mol / L potassium dichromate standard solution to the solution in (1);

[0043] (3) Connect a condenser to the reaction vessel, add 60mL of the prepared sulfuric acid-silver sulfate solution from the top of the condenser, and shake the vessel while adding;

[0044] (4) Place the reaction vessel in the heating device, heat it under reflux for 20 minutes, and then remove it until the test solution is cooled; at the same time, rinse the inner wall of the condenser with distilled water and remove the condenser; add 140 mL of distilled water to the cooled sample, shake well;

[0045] (5) Add 2 drops of ferrous sul...

Embodiment 2

[0048] Embodiment 2: an analytical method for detecting chemical oxygen demand in water, it comprises the following steps:

[0049] (1) Take 20.0mL of 500mg / L COD equivalent potassium hydrogen phthalate standard solution and place it in the reaction vessel, add 0.5g of mercury sulfate and stir until the mercury sulfate is completely dissolved;

[0050] (2) Add 15mL of 0.25mol / L potassium dichromate standard solution to the solution in (1);

[0051] (3) Connect a condenser to the reaction vessel, add 20mL of the prepared sulfuric acid-silver sulfate solution from the top of the condenser, and shake the vessel while adding;

[0052] (4) Place the reaction vessel in a heating device, heat it under reflux for 5 minutes, and remove it until the test solution is cooled; at the same time, rinse the inner wall of the condenser with distilled water and remove the condenser; add 80 mL of distilled water to the cooled sample, shake uniform;

[0053](5) Add 2 drops of ferrous sulfate in...

Embodiment 4

[0056] Embodiment 4: an analytical method for detecting chemical oxygen demand in water, it comprises the following steps:

[0057] (1) Take 20.0mL of 500mg / L COD equivalent potassium hydrogen phthalate standard solution and place it in the reaction vessel, add 0.6g of mercury sulfate and stir until the mercury sulfate is completely dissolved;

[0058] (2) Add 20mL of 0.25mol / L potassium dichromate standard solution to the solution in (1);

[0059] (3) Connect a condenser to the reaction vessel, add 40mL of the prepared sulfuric acid-silver sulfate solution from the top of the condenser, and shake the vessel while adding;

[0060] (4) Place the reaction vessel in a heating device, heat it under reflux for 10 minutes, and then remove it until the test solution is cooled; at the same time, rinse the inner wall of the condenser with distilled water and remove the condenser; add 100 mL of distilled water to the cooled sample, shake uniform;

[0061] (5) Add 2 drops of ferrous su...

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Abstract

The invention discloses an analysis method for detecting chemical oxygen demand (COD) in water. The method comprises the steps of: putting a water sample into a reaction container, adding mercury sulfate and stirring till the mercury sulfate is completely dissolved; adding a potassium dichromate standard solution; connecting a condenser to the reaction container, and adding a sulfuric acid-silver sulfate solution from the upper opening of the condenser while shaking the container; placing the reaction container over a heating device, performing reflux heating, and taking the reaction container down till the test solution is cooled; flushing the inner wall of a condensation tube with distilled water, and taking the condensation tube down; adding distilled water into the cooled test sample, and shaking uniformly; adding a ferroin indicator solution into the diluted test sample, titrating with a ferrous sulfate standard solution till the test solution suddenly becomes red brown, and recording the milliliter value of the used ferrous sulfate standard solution. By partially optimizing and improving the original national method, the method can greatly shorten the time of COD detection.

Description

technical field [0001] The invention belongs to the field of water quality detection and analysis, and relates to a detection method of chemical oxygen demand, in particular to an analysis method for detection of chemical oxygen demand in water. Background technique [0002] COD (Chemical Oxygen Demand) 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 organic pollution in water bodies, often represented by the symbol COD. The determination of chemical oxygen demand (COD) varies with the determination of reducing substances in the chemical oxygen demand of water samples and the measurement methods, and the measured values ​​are also different. At present, the main determination methods are: dichromate method, potassium permanganate method, spectrophotometric method, rapid digestion method, rapid digestion spectrophotometric method, etc. Among them, the most commonly used ...

Claims

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Application Information

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IPC IPC(8): G01N31/16G01N31/10
CPCG01N31/10G01N31/162
Inventor 宋岱峰蒲亮
Owner CHENGDU MEIFUTE MEMBRANE TECHNOLOGY CO LTD
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