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A method for preliminary screening of chemical oxygen demand in chlorine-containing wastewater

A chemical oxygen demand and waste water technology, applied in the direction of testing water, measuring devices, scientific instruments, etc., can solve the problems of high testing cost, not enough environmental protection, a large number of toxic and harmful reagents, etc., to reduce the use of precious metals, high COD conversion rate , The effect of saving testing cost

Active Publication Date: 2021-10-08
上海华测品标检测技术有限公司 +1
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Problems solved by technology

[0003] At present, there are automated equipment on the market to automatically test the chemical oxygen demand (COD), but none of them have realized the automatic preliminary screening of COD. During the test, it is necessary to pass the manual preliminary judgment before realizing the subsequent automatic test, so the COD has not been realized. Fully automated testing, COD automated primary screening is a lack of technology
In addition, the existing COD determination method, whether it is the reflux digestion method or the rapid closed digestion method, uses potassium dichromate as the oxidant, silver sulfate as the catalyst, and mercury sulfate as the chloride ion masking agent, and measures COD under sulfuric acid acidic conditions. All the methods of determination need to use a large amount of toxic and harmful reagents, the test cost is high, and it is not environmentally friendly.

Method used

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  • A method for preliminary screening of chemical oxygen demand in chlorine-containing wastewater

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Experimental program
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Effect test

specific Embodiment 1

[0029] (1) Take sample 1, according to the low-concentration primary screening system 0.5mL sample+5mL 0.025mol / L potassium dichromate solution+8mL sulfuric acid, take a sample, add reagents, use the residual heat of sulfuric acid to react, and cool to room temperature;

[0030] (2) test at the 440nm place of the spectrophotometer, obtain the absorbance value A=-0.125 after deducting the blank, and calculate the absorbance value into the low concentration standard curve to obtain the chlorine-containing COD=289ppm of sample 1;

[0031] (3) test with chloride ion selective electrode, obtain sample 1 chloride ion concentration and be 939ppm, so chloride ion conversion COD=939ppm*0.22=207ppm;

[0032] (4) COD primary screening result of sample 1 = (chlorine-containing COD-chlorine ion conversion COD) / conversion rate correction factor=(289ppm-207ppm) / 0.6=137ppm;

[0033] (5) According to the COD preliminary screening results of sample 1, the dilution factor of sample 1 is determin...

specific Embodiment 2

[0035] (1) Take sample 2, according to the low-concentration primary screening system 0.5mL sample+5mL 0.025mol / L potassium dichromate solution+8mL sulfuric acid, take a sample, add reagents, use the residual heat of sulfuric acid to react, and cool to room temperature;

[0036](2) Test at 440nm of the spectrophotometer, get the absorbance value A=-0.560 after deducting the blank, and substitute the absorbance value into the low concentration standard curve to calculate, and obtain the chlorine-containing COD of the actual sample=1325ppm, divide it by the conversion rate of the low concentration sample to correct Coefficient 0.6, COD preliminary screening result > 2000ppm, need to use high concentration preliminary screening system to continue preliminary judgment;

[0037] (3) Take sample 2, according to the high-concentration primary screening system 0.5mL sample+5mL 0.25mol / L potassium dichromate solution+8mL sulfuric acid, take a sample, add reagents, use the residual heat ...

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Abstract

A method for preliminary screening of chemical oxygen demand (COD) in chlorine-containing wastewater, characterized in that it comprises the following steps: (1) establishing a preliminary screening system, and establishing the relationship between COD and light absorption value after the solutions of different COD are reacted by the preliminary screening system (2) Determine the COD contribution rate of chloride ions under the primary screening system; (3) After the sample to be tested reacts according to the primary screening system, calculate the chlorine-containing COD with the standard curve according to the absorbance value; (4) Test chlorine After the ion concentration, according to the COD contribution rate of chloride ions, the conversion of chloride ions to COD is obtained; (5) the chlorine-containing COD minus the conversion of chloride ions to COD, that is, the COD of the sample to be tested under the primary screening system, and then the sample under the primary screening system The conversion rate correction coefficient correction, that is, the COD range of the sample to be tested. The method has the advantages of rapidity, low consumption and easy automation.

Description

technical field [0001] The invention relates to a chemical oxygen demand preliminary screening method, in particular to a chemical oxygen demand preliminary screening method suitable for chlorine-containing wastewater. Background technique [0002] Chemical oxygen demand (COD) 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 the amount of reducing substances in water. The reducing substances in water include various organic substances, nitrite, sulfide, ferrous salt, etc., but the main ones are organic substances. Therefore, chemical oxygen demand (COD) is often used as an index to measure the content of organic substances in water. The greater the COD, the more serious the water body is polluted by organic matter. The determination of chemical oxygen demand (COD) varies with the determination of reducing substances in water samples and the determination methods, and it...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N33/18
CPCG01N33/1806
Inventor 陈桂淋田倩陈卫东
Owner 上海华测品标检测技术有限公司
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