Method for measuring iron ion concentration by full-automatic potentiometric titration method

A potentiometric titration method and iron ion concentration technology, applied in the field of chemical analysis, can solve problems such as difficult control of experimental operating conditions, influence on measurement accuracy, increase measurement error, etc., and achieve low cost, high accuracy, and the effect of inhibiting hydrolysis

Pending Publication Date: 2022-07-12
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method usually needs to consume multiple reagents such as sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, titanium trichloride, sodium tungstate, sodium diphenylamine sulfonate, potassium dichromate standard solution, etc. The variety of reagents is inconvenient to operate, and a large amount of Ti 3+ In reducing Fe 3+ will later become Ti 4+ , Ti 4+ It will be hydrolyzed to produce white colloidal precipitate, which will affect the accuracy of measurement
In addition, the end point of the titration needs to be identified by the color of the indicator, which makes it more difficult to control the experimental operating conditions and further increases the measurement error

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] A method for measuring iron ion concentration by automatic potentiometric titration, comprising the following steps:

[0026] (1) Weigh 2.7030g ferric chloride hexahydrate sample in a beaker, add 50 mL of hydrochloric acid solution with a concentration of 4mol / L, stir the mixture and sonicate, after the ferric chloride hexahydrate is completely dissolved, remove the solution Put it into a 100mL volumetric flask, shake it to a constant volume, and test it;

[0027] (2) Pipette 3mL of the solution to be tested to the titration cup of the automatic potentiometric titrator, and add 30mL of 0.5mol / L LiCl+1mol / L NH to the titration cup 2 SO 3 The base solution of H and 15mL of titanium trichloride solution with a concentration of 0.2mol / L formed a mixed solution, and the pre-stirring time of the automatic potentiometric titrator was set to 100 seconds, and the rotation speed was set to 1000 revolutions per minute. Titrator, use (1 / 6) 0.05mol / L potassium dichromate standard ...

Embodiment 2

[0034] A method for measuring iron ion concentration by automatic potentiometric titration, comprising the following steps:

[0035] (1) Weigh 2.9733g ferric chloride hexahydrate sample in a beaker, add 60 mL of hydrochloric acid solution with a concentration of 4 mol / L, stir the mixture and sonicate, after the ferric chloride hexahydrate is completely dissolved, transfer the solution to Put it into a 100mL volumetric flask, shake it to a constant volume, and test it;

[0036] (2) Pipette 2mL of the solution to be tested to the titration cup of the automatic potentiometric titrator, and add 40mL of LiCl with a concentration of 0.5mol / L+1mol / L NH to the titration cup 2 SO 3The base solution of H and 20 mL of titanium trichloride solution with a concentration of 0.1 mol / L formed a mixed solution, and the pre-stirring time of the automatic potentiometric titrator was set to 120 seconds, and the rotation speed was set to 1500 rpm. Titrator, use (1 / 6) 0.01mol / L potassium dichroma...

Embodiment 3

[0043] A method for measuring iron ion concentration by automatic potentiometric titration, comprising the following steps:

[0044] (1) Weigh 4.0545g ferric chloride hexahydrate sample in a beaker, add 65 mL of hydrochloric acid solution with a concentration of 2 mol / L, stir the mixture and sonicate, after the ferric chloride hexahydrate is completely dissolved, remove the solution Put it into a 100mL volumetric flask, shake it to a constant volume, and form the solution to be tested;

[0045] (2) Pipette 2mL of the solution to be tested to the titration cup of the automatic potentiometric titrator, and add 30mL of LiCl with a concentration of 0.5mol / L+1mol / L NH to the titration cup 2 SO 3 The base solution of H and 15 mL of titanium trichloride solution with a concentration of 0.1 mol / L formed a mixed solution, and the pre-stirring time of the automatic potentiometric titrator was set to 180 seconds, and the rotation speed was set to 1500 rpm. Titrator, use (1 / 6) 0.03mol / L...

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PUM

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Abstract

The method comprises the following steps: reducing Fe < 3 + > in a sample into Fe < 2 + > by using a titanium trichloride solution as a reducing agent, titrating a solution to be detected by using a potassium dichromate standard solution, judging a titration end point according to the change of potential in the titration process, and determining the concentration of iron ions according to the consumed volume of the potassium dichromate solution. And calculating the concentration of iron ions in the test sample. Meanwhile, a proper amount of a substrate solution of lithium chloride and sulfamic acid is added into a test solution, so that errors caused by precipitation formed by hydrolysis of Fe < 3 + > and Ti < 4 + > are reduced. According to the method, an indicator does not need to be added in the whole process, and the measurement stability and accuracy are improved by setting proper pre-stirring time and rotating speed. Compared with the prior art, the testing method is economical, environmentally friendly, good in stability, easy to operate and high in accuracy.

Description

technical field [0001] The invention belongs to the technical field of chemical analysis methods, in particular to a method for measuring iron ion concentration by an automatic potentiometric titration method. Background technique [0002] As a common metal element in the field of chemical analysis, iron has a huge demand for analysis. At present, the commonly used measurement methods of iron ion concentration are spectrophotometry, ICP-AES analysis method and titanium trichloride-potassium dichromate titration method. Among them, the spectrophotometric method generally requires adding hydroxylamine hydrochloride to the sample to be tested to convert Fe 3+ reduced to Fe 2+ , and then add o-phenanthroline. In order to ensure the measurement accuracy, it is usually necessary to adjust the pH of the solution to about 5, and the sample measurement can only be carried out after the standard curve is drawn. Compared with the spectrophotometric method, the ICP-AES analysis metho...

Claims

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Application Information

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IPC IPC(8): G01N31/16G01N27/26G01N1/28
CPCG01N31/16G01N27/26G01N1/28
Inventor 赵耀林闫正阳聂晓朦贾梓琦王杰韩子彤
Owner XI AN JIAOTONG UNIV
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