Rapid determination method for phosphorus element in rare earth fluoride

Abstract

The invention discloses a rapid determination method for phosphorus element in rare earth fluoride. The method provided by the invention comprises the following steps: 1) dissolving a sample with aqua regia, and adding perchloric acid for smoking; 2) in a nitric acid medium, adding ammonium molybdate to enable phosphoric acid to generate phosphomolybdic heteropoly acid, and adding tartaric acid to eliminate interference of silicon; 3) adding tin dichloride to reduce phosphomolybdenum yellow into phosphomolybdenum blue; and 4) measuring the absorbance, and calculating the phosphorus content through the calibration curve. According to the method, accurate data can be provided for the content of phosphorus in rare earth fluoride, the blank of a method for measuring the content of phosphorus in rare earth fluoride is filled, and a reliable and rapid detection method can be provided for personnel engaged in detection and analysis of the content of phosphorus in rare earth fluoride.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgical analysis, and particularly relates to a rapid determination method of phosphorus in fluorinated rare earth, and especially relates to a method for determining the content of phosphorus in fluorinated rare earth by using phosphorus molybdenum blue spectrophotometry. BACKGROUND

[0002] Phosphorus, as one of the common impurity elements in fluorinated rare earth, directly affects the performance (such as catalytic activity, magnetic properties, etc.) of the material and the stability of the production process. Therefore, the accurate detection of phosphorus is crucial for the quality control of fluorinated rare earth products. The application expansion of fluorinated rare earth in the fields of new energy, electronics (such as rare earth permanent magnet materials, lithium battery electrolyte) puts forward higher requirements for the detection accuracy and efficiency of phosphorus. For example, the accurate control of the content of phosphorus in lithium hexafluorophosphate directly affects the electrochemical performance of lithium ion batteries. So far, there is no rapid detection method for the content of phosphorus in fluorinated rare earth. Based on the above status, we developed an analysis method for determining the content of phosphorus in fluorinated rare earth by using phosphorus molybdenum blue spectrophotometry. SUMMARY

[0003] In order to rapidly determine the content of phosphorus in fluorinated rare earth, an analysis method for determining the content of phosphorus in fluorinated rare earth by using phosphorus molybdenum blue spectrophotometry is invented. This method has been successfully applied in production practice, and is simple, rapid and accurate in the determination process, which is an effective and practical analysis method.

[0004] The application is mainly realized through the following technical solutions.

[0005] The application provides a rapid determination method of phosphorus in fluorinated rare earth, which comprises the following steps:

[0006] 1) Dissolve the sample with aqua regia, and add perchloric acid to smoke;

[0007] 2) In the nitric acid medium, add ammonium molybdate to generate phosphomolybdic acid from phosphoric acid, and add tartaric acid to eliminate the interference of silicon;

[0008] 3) Add tin dichloride to reduce phosphomolybdenum yellow to phosphomolybdenum blue; and

[0009] 4) Measure the absorbance and calculate the content of phosphorus through the calibration curve.

[0010] In some embodiments, the method provided by the application comprises the following steps:

[0011] Put the weighed 0.0500g sample in a 250mL polytetrafluoroethylene beaker, add 10mL aqua regia, 3mL perchloric acid (ρ about 1.69g / mL) and heat to dissolve until the perchloric acid fume is clean, cool slightly, add 10mL nitric acid (2+5), heat to dissolve the salts, remove, transfer to a 250mL high beaker, heat to boiling, add three drops of potassium permanganate (40g / L) dropwise, remove after boiling for 10s, immediately add 10mL potassium sodium tartrate-ammonium molybdate mixed solution, shake for 10s, add 40mL tin dichloride solution, shake well, measure the absorbance at a wavelength of 680nm on an NXS-3A intelligent high-speed analyzer or a spectrophotometer, and find the corresponding phosphorus content from the calibration curve.

[0012] In some embodiments, the determination range of the method is 0.005% to 0.0700%.

[0013] In some embodiments, the calibration curve is drawn in the following manner:

[0014] Take different amounts of phosphorus standard solution (10.0μg / mL) 5 times, color according to the method of claim 2, then measure the absorbance value of the solution, take the content value as the abscissa and the absorbance value as the ordinate to draw a calibration curve or calculate a regression equation.

[0015] Currently, there is no rapid detection method for the phosphorus content in fluorinated rare earth. The present application is suitable for detection and analysis in the metallurgical industry and related scientific research institutes, and provides a reliable and rapid detection method for personnel engaged in the detection and analysis of the phosphorus content in fluorinated rare earth. DETAILED DESCRIPTION

[0016] The present application aims to provide a method for determining the phosphorus content in fluorinated rare earth, and the principle is that the sample is dissolved in acid, and in the nitric acid medium, potassium permanganate is used to oxidize the metaphosphoric acid to orthophosphoric acid, ammonium molybdate is added to form phosphomolybdic acid with phosphoric acid, and tartaric acid is added to eliminate the interference of silicon. Finally, tin dichloride is used to reduce the phosphomolybdate yellow to phosphomolybdate blue, and the absorbance is measured to obtain the phosphorus content through the calibration curve.

[0017] The present application will be described in more detail by the following examples. These examples are only a description of the best mode of the present application, and do not have any limitation on the content of the present application.

[0018] The main instruments and reagents used in the following examples are as follows:

[0019] 1. Nitric acid, ρ about 1.42g / mL, 2+5;

[0020] 2. Hydrochloric acid, ρ about 1.19g / mL;

[0021] 3. Perchloric acid, ρ about 1.69g / mL;

[0022] 4. Potassium permanganate solution, 40 g / L;

[0023] 5. Ammonium molybdate solution, 200 g / L;

[0024] 6. Potassium sodium tartrate solution, 200 g / L;

[0025] 7. Ammonium molybdate-sodium potassium tartrate mixture: Mix equal volumes of ammonium molybdate solution (200 g / L) and sodium potassium tartrate solution (200 g / L).

[0026] 8. For tin dichloride solution, dissolve 2g of tin dichloride in each liter of water and shake well.

[0027] 9. Phosphorus stock solution (50.0 μg / mL)

[0028] Weigh 0.2197g of potassium dihydrogen phosphate (GR), dissolve it in water, transfer it to a 1000mL volumetric flask, dilute it to the mark with water and mix well;

[0029] 10. Phosphorus standard solution (10.0 μg / mL)

[0030] Take 50.00 mL of phosphorus stock solution (50.0 μg / mL) into a 250 mL volumetric flask, dilute with water to the mark and mix well.

[0031] 11. Instruments

[0032] NXS-3A intelligent high-speed analyzer or spectrophotometer.

[0033] Example 1: Method for determining phosphorus content in rare earth fluorides

[0034] 1.1 Determination of phosphorus content in rare earth fluorides

[0035] Weigh 0.0500g of the sample, accurate to 0.0001g.

[0036] Place the weighed sample in a 250 mL PTFE beaker, add 10 mL aqua regia and 3 mL perchloric acid (ρ approximately 1.69 g / mL), and heat until the perchloric acid fumes disappear. Let it cool slightly, then add 10 mL nitric acid (2+5), and heat until the salts dissolve. Remove the beaker and transfer the mixture to a 250 mL tall beaker, heat to boiling, add three drops of potassium permanganate (40 g / L), boil for 10 seconds, and immediately add 10 mL of a potassium sodium tartrate-ammonium molybdate mixture. Shake for 10 seconds, add 40 mL of tin dichloride solution, and shake well. Measure the absorbance at 680 nm using an NXS-3A intelligent high-speed analyzer or spectrophotometer, and determine the corresponding phosphorus content from the calibration curve. Perform a blank test along with the sample.

[0037] 1.2 Plotting the Calibration Curve

[0038] Take five portions of phosphorus standard solution (10.0 μg / mL) of different amounts, perform color development according to the above experimental method, and measure the absorbance value of the solution. Plot a calibration curve or calculate a regression equation with the content value on the x-axis and the absorbance value on the y-axis.

[0039] 1.3 Results and Discussion

[0040] Accuracy and precision experiments

[0041] According to the selected test conditions, spiked recovery test and precision test were carried out on rare earth fluoride samples. The analysis results are shown in Table 1 and Table 2.

[0042] Table 1: Spiked Recovery Test (%)

[0043]

[0044] The data in Table 1 above show that the recovery rate of the spiked experiments is between 95% and 105%, indicating that the accuracy of this analytical method is high.

[0045] Table 2: Precision Test (%) (n=11)

[0046]

[0047] The data in Table 2 above show that the detection method has good precision.

[0048] 1.4 Conclusion

[0049] This method allows for the accurate and rapid determination of phosphorus content in rare earth fluorides. The analytical method is simple, fast, and accurate, meeting the needs of on-site production.

[0050] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapid method for determining phosphorus in rare earth fluorides, comprising the following steps: 1) Dissolve the sample in aqua regia, then add perchloric acid until fumes are produced; 2) In nitric acid medium, ammonium molybdate is added to generate phosphomolybdic acid from phosphoric acid, and tartaric acid is added to eliminate the interference of silicon. 3) Add tin dichloride to reduce phosphomolybdic yellow to phosphomolybdic blue; and 4) Calculate the phosphorus content by measuring the absorbance and then using the calibration curve.

2. The method according to claim 1, comprising the following steps: Place 0.0500g of the sample in a 250mL PTFE beaker, add 10mL aqua regia and 3mL perchloric acid (ρ approx. 1.69g / mL), heat to dissolve until the perchloric acid fumes are clear, cool slightly, add 10mL nitric acid (2+5), heat until the salts dissolve, remove from heat, transfer to a 250mL tall beaker, heat to boiling, add three drops of potassium permanganate (40g / L), boil for 10s, remove from heat, immediately add 10mL of potassium sodium tartrate-ammonium molybdate mixture, shake for 10s, add 40mL of tin dichloride solution, shake well, and measure the absorbance at a wavelength of 680nm using an NXS-3A intelligent high-speed analyzer or spectrophotometer. Determine the corresponding phosphorus content from the calibration curve.

3. The method according to claim 1 or 2, wherein the determination range is 0.005% to 0.0700%.

4. The method according to any one of claims 1-3, wherein the calibration curve is plotted as follows: Take five portions of phosphorus standard solution (10.0 μg / mL) of different amounts, develop color according to the method described in claim 2, and measure the absorbance value of the solution. Plot a calibration curve or calculate a regression equation with the content value on the x-axis and the absorbance value on the y-axis.

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