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Method for determination of chemical oxygen demand in water

A technology of water quality chemistry and oxygen demand, applied in the direction of testing water, using combustion for chemical analysis, material inspection products, etc., can solve the problems of high oxidation capacity, long oxidation time, large amount of reagents, etc., and achieve simple test steps and determination The effect of high precision and small reagent volume

Inactive Publication Date: 2018-01-26
广东盈峰科技有限公司
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Problems solved by technology

But these two kinds of methods have their shortcomings respectively, the hexavalent chromium, mercuric sulfate, silver and other heavy metal ions produced in the determination process of potassium dichromate method will produce larger secondary pollution; the chloride ion concentration in water is higher than 10000mg / L When the shielding agent can not completely shield chloride ions, it needs to be diluted for the second measurement; the oxidation time is long, and it needs to be carried out for 2.5 hours; the acidic solution of potassium dichromate has a high oxidation ability but still cannot 100% reflect the chemical oxygen demand; reagent Large volume, at least 50mL, and the reflux device occupies a large space, consumes a lot of water and electricity, is inconvenient to operate, and is difficult to quickly measure in large quantities
However, the potassium permanganate index method has the following problems: the oxidation ability is weak, and it can only reflect the chemical oxygen demand in 20-30% of the water body; the manganese ion has secondary pollution to the environment during the reaction process; the reagent consumption is large, and it needs 120mL once.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] The present embodiment provides a kind of method for measuring the chemical oxygen demand of water quality, and it comprises the steps:

[0025] a. Acidify 1 mL of water sample with 1% hydrochloric acid by volume to obtain acidified water sample, the volume ratio of hydrochloric acid to water sample is 1:10.

[0026] b. Take 25 μL of acidified water sample and purified air (air from which carbon dioxide, sulfur dioxide, and nitrogen dioxide have been removed by drying method) into the high-temperature combustion tube, and burn at a high temperature at 600°C. Carbon, sulfur, nitrogen, and hydrogen are combusted to generate carbon dioxide, nitrogen dioxide, sulfur dioxide, and water. Inorganic carbonates and nitrates are combusted to generate carbon dioxide and nitrogen dioxide. Liquid water is converted to gaseous water by combustion. Take 25 μL of water samples and purify them. The treated air is introduced into the low-temperature combustion tube and burned at a low te...

Embodiment 2

[0030] The present embodiment provides a kind of method for measuring the chemical oxygen demand of water quality, and it comprises the steps:

[0031] a. Acidify 10 mL of the water sample with hydrochloric acid with a volume concentration of 10% to obtain an acidified water sample, and the volume ratio of the hydrochloric acid to the water sample is 1:50.

[0032] b. Take 5mL of acidified water sample and purified air (air from which carbon dioxide, sulfur dioxide, and nitrogen dioxide have been removed by drying method) into the high-temperature combustion tube, and burn at a high temperature at 1200°C. Carbon, sulfur, nitrogen, and hydrogen are combusted to produce carbon dioxide, nitrogen dioxide, sulfur dioxide and water; inorganic carbonates and nitrates are combusted to produce carbon dioxide and nitrogen dioxide; liquid water is converted to gaseous water by combustion; 5mL water samples are taken and purified The treated air is introduced into the low-temperature comb...

Embodiment 3

[0036] The present embodiment provides a kind of method for measuring the chemical oxygen demand of water quality, and it comprises the steps:

[0037] a. Acidify 5 mL of the water sample with hydrochloric acid with a volume concentration of 5% to obtain an acidified water sample, and the volume ratio of the hydrochloric acid to the water sample is 1:20.

[0038] b. Take 2mL of acidified water sample and purified air (air from which carbon dioxide, sulfur dioxide, and nitrogen dioxide have been removed by drying method) into the high-temperature combustion tube, and burn at a high temperature at 800°C. Carbon, sulfur, nitrogen, and hydrogen are combusted to generate carbon dioxide, nitrogen dioxide, sulfur dioxide, and water. Inorganic carbonates and nitrates are combusted to generate carbon dioxide and nitrogen dioxide. Liquid water is converted to gaseous water by combustion. Take 3mL of water samples and purify them. The treated air is introduced into the low-temperature co...

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Abstract

The invention discloses a method for determination of chemical oxygen demand in water, wherein the method comprises the following steps: a, carrying out acidification treatment of a water sample withhydrochloric acid with the volume concentration of 1-10%, to obtain an acidified water sample; b, taking 20 [mu]L-2.5 mL of the acidified water sample and carrying out high temperature combustion at the temperature of 600-1200 DEG C, taking 20 [mu]L-2.5 mL of the acidified water sample and carrying out low temperature combustion at the temperature of 100-300 DEG C; c, determining the composition and content of gas generated in high temperature combustion and low temperature combustion respectively; and d, calculating the chemical oxygen demand. The method has simple test steps; the reagent amount is low, only needs 40 [mu]L-5 mL and is far lower than 50-120 mL in the traditional test method; and moreover, the test method is green and environmentally friendly and has no need of use of potassium dichromate, potassium permanganate, mercury sulfate, silver sulfate, concentrated sulfuric acid and other reagents which can produce secondary pollution.

Description

technical field [0001] The invention belongs to the technical field of environmental monitoring, in particular to a method for measuring the chemical oxygen demand of water quality. Background technique [0002] Chemical oxygen demand, also known as chemical oxygen demand (Chemical Oxygen Demand, COD for short), is an important parameter in the process of wastewater detection, and it is an index to measure the content of organic matter in water. more serious. The so-called chemical oxygen demand refers to the amount of oxidant consumed when a certain strong oxidant is used to treat water samples under certain conditions, and it is also an indicator of the amount of reducing substances in water. Reducing substances in water include various organic matter, nitrite, sulfide, ferrous salt, etc., but they are mainly organic matter. Organic matter is mainly composed of carbon, nitrogen, sulfur, and hydrogen. During the determination of chemical oxygen demand, Organic matter is o...

Claims

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Application Information

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IPC IPC(8): G01N31/12G01N33/18
Inventor 肖研戈燕红谢广群
Owner 广东盈峰科技有限公司
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