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Method for digesting sample in process of measuring chemical oxygen demand (COD)

A chemical oxygen demand and sample technology, which is applied in the preparation of test samples, test water, material inspection products, etc., can solve the problem of high acid consumption, and achieve the effect of low analysis cost and accurate chemical analysis method

Inactive Publication Date: 2011-06-29
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Patent CN200610047838.1 used in 100ml H 2 SO 4 -H 3 PO 4 MnSO was added to the mixed acid 4 -CuSO 4 Catalyst and Oxidant K 2 Cr 2 o 7 , to obtain a digestion solution, but the consumption of acid is more than that of the classical method

Method used

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  • Method for digesting sample in process of measuring chemical oxygen demand (COD)
  • Method for digesting sample in process of measuring chemical oxygen demand (COD)
  • Method for digesting sample in process of measuring chemical oxygen demand (COD)

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] (1) Accurately measure 10.00ml of the prepared 50mg / L COD standard sample into the Erlenmeyer flask with a single-marked pipette;

[0035] (2) Accurately measure 5.00ml of potassium dichromate standard solution of 0.0250mol / L in the above-mentioned Erlenmeyer flask with a single-marked pipette;

[0036] (3) Add respectively 3.3ml of manganese sulfate solution of 50g / L with graduated pipette in the above-mentioned conical flask, add 1.0ml of 50g / L cerium sulfate solution;

[0037] (4) Measure 18ml of concentrated sulfuric acid with a graduated cylinder and slowly add it to the above-mentioned triangular flask, shake gently while adding, and cover the bottle mouth with a small petri dish after adding;

[0038] (5) Put the triangular flask in an oven at 160°C, start timing and heating for 30 minutes from the oven temperature of 160°C, stop heating in the oven, turn on the blast, and take the triangular flask out of the oven when the temperature drops slightly.

[0039] (6...

Embodiment 2

[0046] Determination of the actual water sample in a water purification plant was performed according to the analysis and determination steps described in Example 1. At that time, the calibration concentration of ammonium ferrous sulfate was 0.02505 mol / L, and the calculation results are shown in Table 2.

[0047] Table 2 CODcr measurement results of actual water samples in the factory

[0048] .

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Abstract

The invention relates to a method for digesting a sample in the process of measuring chemical oxygen demand (COD). The method comprises the following steps of: taking 10.00ml of COD standard sample, and taking distilled water in blank; adding 5.00ml of 0.0250mol / L potassium dichromate standard solution into a water sample; respectively adding 3.3ml of 50g / L manganese sulfate solution, 1.0ml of 50g / L cerium sulfate solution and 18ml of concentrated sulfuric acid, and mixing; putting into a 160 DEG C drying box, and heating for 30 minutes; cooling to room temperature, adding 3 drops of 1,10-phenanthroline-ferrous indicator, titrating by using 0.02510mol / L ammonium ferrous sulfate, and taking a point at which the color of solution is turned from yellow to blue green to red brown as a finishing point; and recording the consumption milliliter number V1 of ammonium ferrous sulfate standard titration solution and a blank test titration consumption milliliter number V0. By the method for digesting the sample, the common drying box is used for heating, the operation process is simple and is easy to master, acid consumption is lower than that in a classical method, digestion time is short, and batch processing can be realized.

Description

technical field [0001] The invention relates to a sample digestion method during the determination of chemical oxygen demand index in water quality monitoring, which belongs to the field of chemical analysis of water quality monitoring. Background technique [0002] Chemical oxygen demand (usually represented by the symbol COD) refers to the amount of oxygen consumed when reducing substances in water are oxidized by chemical oxidants under certain conditions. Chemical oxygen demand is one of the important indicators to comprehensively evaluate the degree of water pollution. It can be used as an indicator to measure the relative content of organic matter in water. It is a must-check item in environmental monitoring and water quality investigation. [0003] At present, there are two kinds of chemical oxygen demand indicators: manganese method and chromium method. [0004] Manganese method chemical oxygen demand in terms of permanganate index COD Mn According to the test stan...

Claims

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Application Information

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IPC IPC(8): G01N1/44G01N33/18
Inventor 郭景玉李红郭亚丽赵新枝
Owner PETROCHINA CO LTD
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