CN111007027A - Method for measuring iron content in thiourea dioxide - Google Patents
Method for measuring iron content in thiourea dioxide Download PDFInfo
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- CN111007027A CN111007027A CN201911408130.8A CN201911408130A CN111007027A CN 111007027 A CN111007027 A CN 111007027A CN 201911408130 A CN201911408130 A CN 201911408130A CN 111007027 A CN111007027 A CN 111007027A
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- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
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Abstract
The invention provides a method for measuring the iron content in thiourea dioxide, which comprises the following steps of 1) sample pretreatment 2) preparation of an iron standard substance; 3) determination of the maximum absorption wavelength; 4) establishing an iron standard curve; 5) and (4) measuring the iron content in the thiourea dioxide. The method provided by the invention has the advantages of good color development effect, capability of accurately measuring the iron content in thiourea dioxide, high analysis speed, good reproducibility and high standard recovery rate.
Description
Technical Field
The invention belongs to the technical field of thiourea dioxide, and particularly relates to a method for measuring the iron content in thiourea dioxide.
Background
Thiourea dioxide is widely used in chemical industry and textile industry, is a strong reducing agent, and increasingly replaces sodium hydrosulfite to occupy a remarkable position in the field of printing and dyeing. The thiourea dioxide is obtained by reacting thiourea with hydrogen peroxide: adding distilled water into a reaction pot, stirring, cooling the temperature in the pot to 8-10 ℃ by using frozen saline, adding thiourea and dropwise adding hydrogen peroxide, and controlling the dropwise adding speed to keep the reaction temperature below 20 ℃. After the pH value is 3-5, the feeding can be repeated. At the end of the reaction, water may be added so that the reaction temperature does not rise any more. When the pH value is 2-3 and the temperature of the material is reduced to about 5 ℃, the oxidation product can be put into a centrifuge for spin-drying and then dried to obtain the thiourea dioxide. 1t of the product consumes 98% of thiourea and 3.4t of 30% of hydrogen peroxide. In addition, the product can also be prepared by taking ozone and thiourea as raw materials or taking calcium cyanamide, ammonium sulfide and hydrogen peroxide as raw materials. The thiourea dioxide is inevitably doped with impurity iron in the production process, and the use effect of the thiourea dioxide is affected when the content of the impurity iron is too much, so that the detection test of the iron content of the thiourea dioxide is usually needed.
At present, the method for determining the iron content in thiourea dioxide is to add 10mL of sulfuric acid 1+1 into the thiourea dioxide, then put the mixture on an electric furnace for drying by distillation, the required time is long, a large amount of harmful gas is generated in the experimental process, and the harm is also generated to human bodies while the environment is polluted.
Disclosure of Invention
Aiming at the problems existing in the detection of the iron content in thiourea dioxide in the prior art, the invention provides the method for determining the iron content in the thiourea dioxide, which has good color rendering stability and can accurately determine the iron content in the thiourea dioxide.
The invention adopts the following technical scheme:
a method for measuring the iron content in thiourea dioxide comprises the following steps:
1) sample treatment: accurately weighing 2g of thiourea dioxide sample to be detected, adding a small amount of water for wetting, then dropwise adding 1mL of hydrochloric acid solution, then adding 50mL of water, then heating until the solution is clear, continuing to heat and evaporate the clear solution until the balance is 20mL, and finally transferring the clear solution into a 100mL volumetric flask for later use;
2) preparing a standard solution: preparing 0.1mg/mL FeSO4A standard solution;
3) determination of the maximum absorption wavelength: taking the FeSO prepared in the step 2)4Adding lmL hydrochloric acid solution into the standard solution, shaking uniformly, adding ascorbic acid, phenanthroline and acetic acid-sodium acetate buffer solution, shaking uniformly, standing for color development, scanning within the range of 400-700nm by using an ultraviolet-visible spectrophotometer, and determining that the maximum absorption wavelength is 510 nm;
4) establishing an iron standard curve: measuring the FeSO prepared in the step 2)4Adding 10mL of standard solution into a 100mL volumetric flask, adding 1mL of hydrochloric acid solution, and diluting with water to prepare 100mL of FeSO4Working solution is 0, 2, 4, 6, 8, 10mLFeSO4Adding ascorbic acid, phenanthroline and acetic acid-sodium acetate buffer solution into a 100mL volumetric flask, shaking uniformly, standing for color development, measuring the absorbance of the solution at 510nm by using an ultraviolet-visible spectrophotometer, and establishing a standard curve by taking the mass of Fe-containing elements per 100mL as a horizontal coordinate x and the absorbance as a vertical coordinate y;
5) taking the sample treated in the step 1), adding ascorbic acid, phenanthroline and acetic acid-sodium acetate buffer solution, shaking uniformly, standing for color development, and measuring the absorbance of the sample at the wavelength of 510nm by using an ultraviolet-visible spectrophotometer;
6) calculating the iron content in the sample: (ii) a
Wherein k represents the slope of the iron standard curve, A represents the absorbance determined in step 5), and m represents the mass of thiourea dioxide to be detected.
Preferably, in the step 1), the hydrochloric acid solution is hydrochloric acid 1+1, and the hydrochloric acid 1+1 is common commercial concentrated hydrochloric acid and distilled water in a volume ratio of 1: 1.
Preferably, in step 4), the standard curve is linearly back-curvedThe return equation is: 0.2534x, R2Linear range 0.9998, 0-0.1 mg.
Preferably, in the step 5), the concentration of the ascorbic acid solution is 100g/L, the pH of the acetic acid-sodium acetate buffer solution is 4.5 at 20 ℃, and the concentration of the phenanthroline solution is 1 g/L.
The invention has the following beneficial effects:
the method provided by the invention has good color development effect and can realize accurate determination of the content of trace iron in thiourea dioxide. The detection method adopted by the detection method provided by the invention has good color development stability, and can accurately detect the iron content in thiourea dioxide; the detection method has the characteristics of high analysis speed, high accuracy, good reproducibility and high standard recovery rate.
Drawings
Fig. 1 is a standard graph.
Detailed Description
In order to make the technical purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention are further described below with reference to the accompanying drawings and specific embodiments.
Examples
A method for measuring the iron content in thiourea dioxide comprises the following steps:
1) and (3) processing of a sample: 6 identical thiourea dioxide samples (of which 4 were used for iron content determination and the remaining two were used for standard recovery determination) were weighed out, and approximately 2g thiourea dioxide per set (to the nearest 0.0001 g) were processed as follows: pouring thiourea dioxide into a 100mL beaker, adding a small amount of water for wetting, dropwise adding 1mL of hydrochloric acid 1+1 solution, then adding about 50mL of water into the beaker, heating the solution by using an electric furnace until the solution is clear, continuing heating until the solution is evaporated until the volume of the residual solution is about 20mL, and transferring the solution into a 100mL volumetric flask for later use;
2) preparation of a standard solution: preparing 0.1mg/mL FeSO4A standard solution;
3) determination of the maximum absorption wavelength: putting 10mL of the iron standard solution prepared in the step 2) into a 100mL volumetric flask, adding lmL hydrochloric acid 1+1 solution, shaking uniformly, adding 2mL of ascorbic acid solution, 5mL of phenanthroline solution and 10mL of acetic acid-sodium acetate solution, shaking uniformly, diluting with water to scale, standing for 10min after shaking uniformly, putting a small amount of the solution into a cuvette, scanning by using an ultraviolet-visible spectrophotometer within the range of 400 plus 700nm, and determining the maximum absorption wavelength of 510 nm;
4) establishing an iron standard curve: measuring the FeSO prepared in the step 2)4Adding 10mL of standard solution into a 100mL volumetric flask, adding 1mL of hydrochloric acid 1+1 solution, diluting with water to prepare 100mL of FeSO4Working solution (0.01 mg/mL) was prepared as 0, 2, 4, 6, 8, 10mLFeSO4Adding 2mL of ascorbic acid solution, 10mL of acetic acid-sodium acetate buffer solution and 5mL of phenanthroline solution into a 100mL volumetric flask, adding water to dilute the solution to a scribed line, shaking the solution uniformly, placing the solution for 15min for color development, measuring the absorbance of the solution by using a 2cm cuvette under the condition of 510nm of an ultraviolet-visible spectrophotometer (721G), and establishing a standard curve by taking the mass (mg) of Fe-containing element of every 100mL as a horizontal coordinate x and the absorbance as a vertical coordinate y, wherein the standard curve equation is y =0.2534 x;
TABLE 1 iron Standard Curve corresponding concentration and Absorbance statistics
5) Taking 4 groups of samples treated in the step 1), adding 2mL of ascorbic acid solution, 10mL of acetic acid-sodium acetate buffer solution and 5mL of phenanthroline solution, diluting to a volumetric flask for scribing, shaking uniformly, placing for 15min for color development, and measuring the absorbance of the samples at the wavelength of 510nm by using an ultraviolet-visible spectrophotometer.
In the steps (3), (4) and (5), the concentration of the ascorbic acid solution is 100g/L, the pH of the acetic acid-sodium acetate buffer solution is 4.5 at 20 ℃, and the concentration of the phenanthroline solution is 1 g/L.
6) The method for calculating the iron content in the sample comprises the following steps:
wherein k represents the slope of the iron standard curve, k =0.2534, a represents the absorbance measured by the ultraviolet-visible spectrophotometer, and m represents the mass of the thiourea dioxide of the sample to be tested.
7) And (3) a standard adding recovery experiment, namely adding an iron standard solution into the remaining 2 groups of thiourea dioxide sample solutions, and detecting the standard adding recovery rate of the sample according to the method.
Table 26 statistics of iron content test results and spiking recovery test results for thiourea dioxide samples
As can be seen from Table 2, the detection method provided by the invention can accurately determine the iron content in thiourea dioxide, and has the characteristics of high analysis speed, good reproducibility and high standard addition recovery rate.
Finally, it should be noted that: the above embodiments are merely illustrative and not restrictive of the technical solutions of the present invention, and any equivalent substitutions and modifications or partial substitutions made without departing from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.
Claims (4)
1. The method for measuring the iron content in thiourea dioxide is characterized by comprising the following steps of:
1) sample treatment: accurately weighing 2g of thiourea dioxide sample to be detected, adding a small amount of water for wetting, then dropwise adding 1mL of hydrochloric acid solution, then adding 50mL of water, then heating until the solution is clear, continuing to heat and evaporate the clear solution until the balance is 20mL, and finally transferring the clear solution into a 100mL volumetric flask for later use;
2) preparing a standard solution: preparing 0.1mg/mL FeSO4A standard solution;
3) determination of the maximum absorption wavelength: taking the FeSO prepared in the step 2)4Adding lmL hydrochloric acid solution into the standard solution, shaking uniformly, adding ascorbic acid, phenanthroline and acetic acid-sodium acetate buffer solution, shaking uniformly, standing for color development, scanning within the range of 400-700nm by using an ultraviolet-visible spectrophotometer, and determining that the maximum absorption wavelength is 510 nm;
4) establishing an iron standard curve: measuring the FeSO prepared in the step 2)4Standard of meritAdding 10mL of the product solution into a 100mL volumetric flask, adding 1mL of hydrochloric acid solution, and adding water for dilution to prepare 100mL of FeSO4Working solution is 0, 2, 4, 6, 8, 10mLFeSO4Adding ascorbic acid, phenanthroline and acetic acid-sodium acetate buffer solution into a 100mL volumetric flask, shaking uniformly, standing for color development, measuring the absorbance of the solution at 510nm by using an ultraviolet-visible spectrophotometer, and establishing a standard curve by taking the mass of Fe-containing elements per 100mL as a horizontal coordinate x and the absorbance as a vertical coordinate y;
5) taking the sample treated in the step 1), adding ascorbic acid, phenanthroline and acetic acid-sodium acetate buffer solution, shaking uniformly, standing for color development, and measuring the absorbance of the sample at the wavelength of 510nm by using an ultraviolet-visible spectrophotometer;
6) calculating the iron content in the sample: (ii) a
Wherein k represents the slope of the iron standard curve, A represents the absorbance determined in step 5), and m represents the mass of thiourea dioxide to be detected.
2. The method for measuring the iron content of thiourea dioxide according to claim 1, wherein in the step 1), the hydrochloric acid solution is hydrochloric acid 1+ 1.
3. The method for determining the iron content of thiourea dioxide according to claim 1, wherein in step 4), the linear regression equation of the standard curve is: 0.2534x, R2Linear range 0.9998, 0-0.1 mg.
4. The method for determining the iron content in thiourea dioxide according to claim 1, wherein in the step 5), the concentration of the ascorbic acid solution is 100g/L, the pH of the acetic acid-sodium acetate buffer solution is 4.5 at 20 ℃, and the concentration of the phenanthroline solution is 1 g/L.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113267461A (en) * | 2021-06-25 | 2021-08-17 | 山东益丰生化环保股份有限公司 | Method for detecting sulfide content in electronic-grade thiourea |
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| CN103528973A (en) * | 2012-07-04 | 2014-01-22 | 北京当升材料科技股份有限公司 | Method for precisely detecting phosphorus content and iron content of iron phosphate |
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| WO2018130476A1 (en) * | 2017-01-11 | 2018-07-19 | Akzo Nobel Chemicals International B.V. | Method for determining iron |
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Patent Citations (4)
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| CN102608047A (en) * | 2012-03-26 | 2012-07-25 | 新疆美克化工股份有限公司 | Method for measuring trace content of iron in 1, 4-butanediol |
| CN103528973A (en) * | 2012-07-04 | 2014-01-22 | 北京当升材料科技股份有限公司 | Method for precisely detecting phosphorus content and iron content of iron phosphate |
| WO2018130476A1 (en) * | 2017-01-11 | 2018-07-19 | Akzo Nobel Chemicals International B.V. | Method for determining iron |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113267461A (en) * | 2021-06-25 | 2021-08-17 | 山东益丰生化环保股份有限公司 | Method for detecting sulfide content in electronic-grade thiourea |
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