CN103616273A - Chemical oxygen demand determination method - Google Patents
Chemical oxygen demand determination method Download PDFInfo
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- CN103616273A CN103616273A CN201310499933.5A CN201310499933A CN103616273A CN 103616273 A CN103616273 A CN 103616273A CN 201310499933 A CN201310499933 A CN 201310499933A CN 103616273 A CN103616273 A CN 103616273A
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- oxygen demand
- chemical oxygen
- digestion
- cod
- potassium dichromate
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Abstract
The invention relates to a chemical oxygen demand determination method in the technical field of chemical oxygen demand determination. The method includes adding a water sample and concentrated sulfuric acid into a digestion tube according to a volume ratio of 1:4-9, piping an inert gas to remove chloride ion in the water sample in a form of hydrogen chloride, adding a potassium dichromate solution to perform digestion, cooling the solution in the digestion tube to room temperature when digestion is completed, and finally measuring the content of the redundant potassium dichromate and calculating the COD value. The method can eliminate chloride ion interference and achieve rapid digestion of the potassium dichromate without the need of using mercury salts or silver slats.
Description
[technical field]
The present invention relates to chemical oxygen demand (COD) determination technical field, especially relate to a kind of for eliminate chloride ion interference, clear up and measure the method for remaining potassium dichromate when measuring chemical oxygen demand (COD).
[background technology]
Known, chemical oxygen demand (COD), namely COD refers under certain condition, the amount of the oxygenant consuming during with certain oxidizer treatment water sample, it is subject to degree of reducing substances pollution for reflecting water body, can be used as the overall target of organism relative content; Meanwhile, for protection of the environment, be convenient to China and aspect water quality management, carry out overall control, chemical oxygen demand (COD) just becomes one of necessary control project; At present, China utilizes potassium dichromate to measure the standard method of chemical oxygen demand (COD), all in the situation that silver salt is made catalyzer, in sulfuric acid medium, under uniform temperature, by oxidation operation in water sample, clear up, and then measure remaining potassium dichromate by corresponding assay method, and calculate COD value, as the mensuration of the mensuration of the mensuration of GB11914 water chemical oxygen demand, dichromate titration, HJ/T 399-2007 water chemical oxygen demand, rapid-digestion spectrophotometric method, HJ/T 70 2001 chemical oxygen demand of high-chloride wastewater and chlorine correction method etc.; Yet, owing to having chlorion in water sample, chlorion also can be by potassium dichromate oxidation, thereby make measurement result value higher, therefore, existing assay method all needs to add poisonous mercury salt, so that itself and chlorion form the interference that complex compound is eliminated chlorion, in addition, in order to accelerate to clear up, this method will add silver salt as catalyzer toward contact; But, because the toxicity of mercury salt and silver salt is larger, in implementation process, easily to environment, cause severe contamination, therefore, need now a kind of assay method that does not use the chemical oxygen demand (COD) of mercury salt and silver salt.
[summary of the invention]
In order to overcome the deficiency in background technology, the invention discloses a kind of assay method of chemical oxygen demand (COD), described method does not need to use mercury salt and silver salt just can eliminate the interference of chlorion, and completes fast clearing up potassium dichromate.
For achieving the above object, the present invention adopts following technical scheme:
An assay method for chemical oxygen demand (COD), described method adopts the by volume ratio of 1:4～9 to add water sample and the concentrated sulphuric acid in digestion tube, then in digestion tube, passes into inert gas at normal temperatures; After utilizing inert gas that the chlorion in water sample is removed with the form of hydrogen chloride, then add potassium bichromate solution to clear up in digestion tube, digestion condition is 165～180 ℃, and digestion time is 15～25 minutes; When having cleared up, the solution temperature in digestion tube is down to room temperature, finally measure unnecessary potassium dichromate content and calculate COD value.
The assay method of described chemical oxygen demand (COD), flow velocity when described inert gas passes into is 70～120ml/min, duration of ventilation is 10～15 minutes.
The assay method of described chemical oxygen demand (COD), described inert gas is argon gas or nitrogen.
The assay method of described chemical oxygen demand (COD), described method adopts microcoulomb method or the content of spectrophotometry potassium dichromate the COD value that converts.
Owing to adopting technical scheme as above, the present invention has following beneficial effect:
The assay method of chemical oxygen demand (COD) of the present invention not only can be measured chemical oxygen demand (COD) simply, fast and accurately, and also do not need to add mercury salt just can remove the interference of chlorion when measuring chemical oxygen demand (COD), do not need to add silver salt just can complete fast clearing up of potassium dichromate, thereby when completing chemical oxygen demand (COD) determination, reached free of contamination object simultaneously yet.
[embodiment]
By the following examples, can explain in more detail the present invention, disclose object of the present invention and be intended to protect all changes and improvements in the scope of the invention, the present invention is not limited to the following examples:
The assay method of described chemical oxygen demand (COD) adopts the by volume ratio of 1:4～9 to add water sample and the concentrated sulphuric acid in digestion tube, in digestion tube, pass into argon gas or nitrogen at normal temperatures again, the argon gas passing into or the flow velocity of nitrogen are 70～120ml/min, duration of ventilation is 10～15 minutes, thereby reaches the object that the hydrogen chloride that utilizes the argon gas pass into or nitrogen that the chlorion in water sample and sulfuric acid reaction are generated is taken away completely; Next, in digestion tube, add potassium bichromate solution, start to clear up operation, digestion condition is 165～180 ℃, and digestion time is 15～25 minutes, when having cleared up, after organic substance in water sample is oxidized, solution temperature in digestion tube is down to room temperature, then adopts the content of microcoulomb method or the remaining potassium dichromate of spectrophotometry, and be converted into COD value.
Part not in the detailed description of the invention is prior art, therefore the present invention is not described in detail.
Claims (4)
1. an assay method for chemical oxygen demand (COD), is characterized in that: described method adopts the by volume ratio of 1:4～9 to add water sample and the concentrated sulphuric acid in digestion tube, then in digestion tube, passes into inert gas at normal temperatures; After utilizing inert gas that the chlorion in water sample is removed with the form of hydrogen chloride, then add potassium bichromate solution to clear up in digestion tube, digestion condition is 165～180 ℃, and digestion time is 15～25 minutes; When having cleared up, the solution temperature in digestion tube is down to room temperature, finally measure unnecessary potassium dichromate content and calculate COD value.
2. the assay method of chemical oxygen demand (COD) according to claim 1, is characterized in that: flow velocity when described inert gas passes into is 70～120ml/min, and duration of ventilation is 10～15 minutes.
3. the assay method of chemical oxygen demand (COD) according to claim 1, is characterized in that: described inert gas is argon gas or nitrogen.
4. the assay method of chemical oxygen demand (COD) according to claim 1, is characterized in that: in described method, adopt the content of microcoulomb method or spectrophotometry potassium dichromate the COD value that converts.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310499933.5A CN103616273A (en) | 2013-10-23 | 2013-10-23 | Chemical oxygen demand determination method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201310499933.5A CN103616273A (en) | 2013-10-23 | 2013-10-23 | Chemical oxygen demand determination method |
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| CN103616273A true CN103616273A (en) | 2014-03-05 |
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| CN201310499933.5A Pending CN103616273A (en) | 2013-10-23 | 2013-10-23 | Chemical oxygen demand determination method |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104297197A (en) * | 2014-09-22 | 2015-01-21 | 江苏骏龙电力科技股份有限公司 | Water pollution collection device and method |
| CN105223168A (en) * | 2015-10-29 | 2016-01-06 | 伊创仪器科技（广州）有限公司 | Online metal analysis system |
| CN106872388A (en) * | 2017-03-08 | 2017-06-20 | 上海纺织节能环保中心 | A kind of assay method of super chemical oxygen demand of high-chloride wastewater |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104297197A (en) * | 2014-09-22 | 2015-01-21 | 江苏骏龙电力科技股份有限公司 | Water pollution collection device and method |
| CN105223168A (en) * | 2015-10-29 | 2016-01-06 | 伊创仪器科技（广州）有限公司 | Online metal analysis system |
| CN106872388A (en) * | 2017-03-08 | 2017-06-20 | 上海纺织节能环保中心 | A kind of assay method of super chemical oxygen demand of high-chloride wastewater |
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Application publication date: 20140305 |