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Method for determining chemical oxygen demand of high-chlorine waste water

A chemical oxygen demand and water sample technology, which is applied in the direction of material analysis by observing the influence of chemical indicators, and analysis by making materials undergo chemical reactions, can solve the difficulties of mercury sulfate recovery, personal injury, secondary environment, etc. Pollution and other problems, to achieve the effect of ensuring catalytic oxidation ability, preventing secondary pollution, and easy operation

Inactive Publication Date: 2014-09-03
CNOOC ENERGY TECH & SERVICES +1
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0010] In addition, mercury sulfate is used as a chloride ion shielding agent in the standard method of potassium dichromate. Mercury sulfate will produce mercury vapor into the air during the high-temperature digestion process, which will cause personal injury to the experimenters who have been engaged in monitoring work for a long time. Difficult to recycle, easy to cause secondary environmental pollution

Method used

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  • Method for determining chemical oxygen demand of high-chlorine waste water
  • Method for determining chemical oxygen demand of high-chlorine waste water
  • Method for determining chemical oxygen demand of high-chlorine waste water

Examples

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Embodiment 1

[0036]Use sodium chloride and potassium hydrogen phthalate to prepare a series of standard solutions with a certain concentration of chloride ion and chemical oxygen demand value. The chloride ion is set to 3000, 5000, 8000, 12000, 15000, 18000, 20000mg / L7 gradients, chemical Oxygen demand is set to 6 gradients of 50, 100, 200, 300, 500, 700mg / L, a total of 42 samples. According to the assay method provided by the invention ((1) add potassium dichromate solution in the water sample of packing into Erlenmeyer flask, then mix homogeneously; (2) adopt silver nitrate to add the water sample of Erlenmeyer flask as chloride ion shielding agent In the process, after the chlorine ions and silver nitrate in the water sample completely form a silver chloride precipitate, the excess silver nitrate combines with potassium dichromate to form a brick red silver chromate precipitate, and the brick red precipitate in the Erlenmeyer flask is the end point of silver nitrate addition. (3) add th...

Embodiment 2

[0041] Use sodium chloride and potassium hydrogen phthalate to prepare a series of standard solutions with a certain concentration of chloride ion and chemical oxygen demand value. The chloride ion is set to 10000, 20000mg / L2 gradients, and the chemical oxygen demand is set to 100, 300mg / L2. Gradient, a total of 4 samples, according to the method in Example 1, each sample was repeatedly measured 6 times, and the relative standard deviation was calculated. The results are shown in Table 2.

[0042] Table 3 Precision test results Unit: mg / L

[0043]

[0044] It can be seen from Table 3 that under the conditions of this example, the relative standard deviation of multiple determinations of samples by the method of the present invention is between 1.9% and 3.6%, and the precision is good.

Embodiment 3

[0046] Adopt the method of the present invention to measure the chemical oxygen demand value of 4 different samples respectively (domestic sewage sample 1, domestic sewage sample 2, production wastewater sample 1, production wastewater sample 2), then add standard to 4 samples respectively (standard substance Potassium hydrogen phthalate), and adopt the method in embodiment 1 to measure the COD value after standard addition, calculate standard addition recovery, experimental result is shown in Table 4.

[0047] Table 4 The experimental results of the standard recovery rate

[0048]

[0049] As can be seen from Table 3, under the conditions of this example, the standard addition recovery rate of the method of the present invention is between 94.0%-109.8%, and the standard addition recovery rate is good.

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Abstract

The invention discloses a method for determining the chemical oxygen demand of high-chlorine waste water. The method comprises the following steps: (1) adding a potassium dichromate solution into a water sample put in a conical flask, and then uniformly mixing; (2) adding silver nitrate adopted as a chloride ion screening agent into the water sample put of the conical flask; after chloride ions and silver nitrate in the water sample completely form silver chloride precipitation, combining excessive silver nitrate with potassium dichromate to generate brick-red silver chromate precipitation, wherein when the brick-red precipitation appears in the conical flask, silver nitrate is not added; (3) adding 20mL15g / L of sulfuric acid-silver sulfate solution into the water sample of the conical flask, and then carrying out operation according to a standard potassium dichromate method to calculate the chemical oxygen demand value through a formula; (4) subtracting a modified value from the calculated chemical oxygen demand value to obtain the chemical oxygen demand value in the water sample. The method can prevent mercury sulfate from harming health of experimenters, prevents secondary pollution, is easy and convenient to operate, and can improve accuracy.

Description

technical field [0001] The invention relates to a water quality environment monitoring method, in particular to a method for measuring the chemical oxygen demand of high-chlorine wastewater. Background technique [0002] Chemical oxygen demand refers to the amount of oxidant consumed when treating water samples with a certain oxidant under certain conditions. It is an important indicator and an important item of water quality monitoring. [0003] At present, the determination of chemical oxygen demand is generally carried out by "The Determination of Chemical Oxygen Demand in Water Quality Dichromate Method" (GBT11914-1989). The principle is that in a strong acid solution, a certain amount of potassium dichromate oxidizes the reducing substances in the water sample under the condition of silver sulfate as a catalyst, and the excess potassium dichromate uses 1,10-phenanthroline as an indicator , back-drip with ferrous ammonium sulfate solution, and calculate the oxygen cons...

Claims

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Application Information

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IPC IPC(8): G01N21/82
Inventor 张保华李波王亮岳美荣孔祥军张楠王静付胜楠雷岗星
Owner CNOOC ENERGY TECH & SERVICES
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