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Method for detecting COD in sewage and reclaimed water

A detection method and technology for regenerating water, applied in the field of chemical analysis, can solve the problems of long reflux time, loss of precious metals, large amount of reagents, etc., and achieve the effect of small titration error, preventing interference of chloride ions, and improving oxidation efficiency.

Inactive Publication Date: 2018-12-25
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0023] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a COD detection method in sewage and reclaimed water to solve the problems in the prior art such as too long reflux time, large amount of reagents, loss of a large amount of precious metals, etc.

Method used

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  • Method for detecting COD in sewage and reclaimed water
  • Method for detecting COD in sewage and reclaimed water
  • Method for detecting COD in sewage and reclaimed water

Examples

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Effect test

Embodiment 1

[0054] Refining clean water. Carry out a blank test first, and input the parameters into the formula. Add 10mL of water sample, 14mL of sulfuric acid and phosphoric acid with a volume ratio of 3:1, and manganese sulfate-copper sulfate-aluminum potassium sulfate with a mass ratio of 3:1:1:1 in a self-made large-volume sealed digestion / titration bottle. -Chromium potassium sulfate 0.4g, 0.05mol / L potassium dichromate 10mL, closed microreflux digestion, 162°C for 30min, after cooling, rinse the lid and inner wall with a small amount of distilled water to make the total volume 70-80mL, directly use gold composite electrode The potentiometric titration method is used for detection, and the results and other relevant information are automatically displayed; the measured chemical oxygen demand (COD) of clean refinery water is 32.2mg / L.

Embodiment 2

[0056] Saline primary clarifier pool water. 10mL of water sample, 15mL of sulfuric acid and phosphoric acid at a volume ratio of 4:1, 0.5g of manganese sulfate-copper sulfate-aluminum potassium sulfate-chromium potassium sulfate at a mass ratio of 3:1:1:1, and 0.05mol / L of dichromic acid Potassium 10mL, closed micro-reflux digestion, 163 ° C for 30min, after cooling, rinse the lid and inner wall with a small amount of distilled water to make the total volume 70-80mL, directly use the gold composite electrode potentiometric titration method for detection, and automatically display the results and other relevant information; The chemical oxygen demand (COD) of the primary clarifier water is 220mg / L.

Embodiment 3

[0058] Aggregated sewage. 10mL of water sample, 17mL of sulfuric acid and phosphoric acid at a volume ratio of 3:1, 0.6g of manganese sulfate-copper sulfate-aluminum potassium sulfate-chromium potassium sulfate at a mass ratio of 3:1:1:1, and 0.05mol / L of dichromic acid Potassium 10mL, closed micro-reflux digestion, 165 ℃ for 28min, after cooling, rinse the lid and inner wall with a small amount of distilled water to make the total volume 70-80mL, directly use the gold composite electrode potentiometric titration method for detection, and automatically display the results and other relevant information; aggregated sewage The chemical oxygen demand (COD) is 63.8mg / L.

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Abstract

The invention discloses a method for detecting COD in sewage and reclaimed water. The detection mechanism, the water sampling amount and the addition amount of oxidant of the invention are the same asthe method of HJ 828-2017. A precious metal silver reagent is replaced by 4 kinds of metal ion sulfates with different catalytic activities and selectivity such as manganese sulfate, copper sulfate,potassium aluminum sulfate. The oxidizing property of potassium dichromate is reduced by using the reduction of acidity of sulfur-phosphorus mixed acid, the adsorption of phosphoric acid, and the presence of chromium potassium sulfate, and a large volume closed digestion is used to shorten the digestion time to 25 min, thereby achieving mercury-free to prevent the interference of chloride ions. Atthe same time, the reaction pressure is increased, the digestion temperature is increased to 165 DEG C, so that the oxidation efficiency is improved. The digestion / titration bottle is integrated, amanual indicator titration is replaced by a gold composite electrode potentiometric titration, and the COD in the water sample is calculated. The 5 kinds of metal ion sulfates of the method for detecting the COD in sewage and reclaimed water are non-toxic, easily available and cheap; the sample of the sulfur-phosphorus mixed acid large volume closed digestion has a good adaptability, the COD results are consistent with the method of HJ 828-2017, and the rapid determination and green determination of the COD are achieved.

Description

technical field [0001] The invention relates to the technical field of chemical analysis, in particular to a method for indirect detection of COD in sewage and regenerated water by means of silver-free and mercury-closed micro-pressure catalytic digestion and gold indicator electrode potentiometric titration. Background technique [0002] Chemical-Oxygen-Demand (Chemical-Oxygen-Demand), referred to as COD, refers to the mass concentration of oxygen corresponding to the strong oxidant potassium dichromate consumed by dissolved substances and suspended solids in water under certain conditions, expressed in mg / L meter. It is a comprehensive indicator of reducing substances in water. The COD in the water body is too high, indicating that the organic pollution is very serious, which will destroy the balance of the environment and biological communities, and cause the deterioration of the water body. Therefore, COD is an important parameter of sewage treatment plants and an imp...

Claims

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Application Information

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IPC IPC(8): G01N1/44G01N31/16G01N27/26
CPCG01N1/44G01N27/26G01N31/164
Inventor 陆克平刘浩黄劲松周剑平朱四九
Owner CHINA PETROLEUM & CHEM CORP
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