Method for measuring nickel content in catalyst powder for artificial diamond

Abstract

The invention discloses a method for determining the content of nickel in catalyst powder for artificial diamond, which belongs to the technical field of physical and chemical detection, and is specifically implemented according to the following steps: S1, developing by taking a blank sample as a reference; s2, developing according to the developing step in the S1 by taking a reagent blank as a reference, recording an absorbance value, drawing a standard working curve, searching a corresponding nickel amount from the working curve, and calculating to obtain the nickel content in the sample. According to the method, the catalyst powder for the artificial diamond in the field is designed, the key steps of sampling, sample dissolving, diluting, developing and the like are accurately controlled and optimized, accurate and rapid determination of the high-nickel material through the spectrophotometric method is achieved, and the range of determining the nickel content through the spectrophotometric method is expanded. In addition, the determination method is simple and convenient to operate and high in applicability, can effectively solve the problems of harsh measurement conditions, complicated operation procedures and the like of a gravimetric method, and facilitates development of conventional detection work.

Description

Technical Field

[0001] The invention belongs to the technical field of physical and chemical detection, and in particular relates to a method for determining the nickel content in catalyst powder for artificial diamond. Background Art

[0002] Catalyst powder for artificial diamond is made of iron, nickel and cobalt metals as the main raw materials. It is made through production processes such as batching, smelting, atomization, dehydration and screening. It is a "catalytic" substance that can greatly reduce the temperature and pressure required for synthetic diamond. It is mainly used for synthesizing artificial diamond.

[0003] The nickel content in catalyst powder for artificial diamond not only affects the growth rate of diamond crystals, but also affects the shape, size and overall quality of the crystals. At present, the methods for determining the nickel content in metals or alloys are: GB / T223.25-94 "Methods for Chemical Analysis of Steel and Alloys - Determination of Nickel Content by Dimethylglyoxime Gravimetric Method" and GB / T223.23-2008 "Determination of Nickel Content in Steel and Alloys - Dimethylglyoxime Spectrophotometric Method". The operation of the GB / T223.25-94 gravimetric method is too cumbersome and time-consuming, and cannot meet the daily production testing needs; the measurement range of nickel content in GB / T223.23-2008 does not exceed 2.00%, which is not applicable to catalyst powder for artificial diamond with a nickel content of about 30%. Therefore, it is urgent to develop an analytical method that can accurately and quickly determine the high content of nickel in batch catalyst powder for artificial diamond to meet daily production needs. Summary of the invention

[0004] The purpose of the present invention is to provide a method for determining the nickel content in catalyst powder for artificial diamond, which solves the technical problems that the existing determination method is complicated to operate and is not applicable to catalyst powder for artificial diamond with a nickel content of about 30%.

[0005] The technical solution adopted by the present invention is a method for determining the nickel content in catalyst powder for artificial diamond, which is specifically implemented according to the following steps: S1: color development with the sample blank as reference; S2: Use the reagent blank as a reference to develop color according to the color development steps in S1, record the absorbance value, draw a standard working curve, find the corresponding nickel amount from the working curve, and calculate the nickel content in the sample.

[0006] The present invention is also characterized in that: S1 specifically includes the following steps: S11: Weigh 0.1000g of the sample into a 100mL conical flask, slowly add 10mL of the mixed acid solution along the mouth of the conical flask, after the violent reaction is over, add another 10mL of the mixed acid solution into the conical flask, and then place the conical flask on an electric hot plate and heat until the solution inside the conical flask is clear and no obvious brown-yellow smoke is emitted; then add 3mL of perchloric acid into the conical flask, continue heating until perchloric acid smoke continues to be emitted for 1 minute, then remove the conical flask from the electric hot plate and cool it to obtain mother solution A; S12: Add 10 mL of distilled water to the mother solution A, then transfer the solution in the conical flask to a 200 mL volumetric flask, shake to volume, and dry filter to obtain test solution B; S13: Pipette 1.00 mL of test solution B in two portions and place each portion in a 50 mL volumetric flask; Add 10 mL of sodium tartrate solution, 10 mL of sodium hydroxide solution, 2 mL of dimethylglyoxime solution and 5 mL of ammonium persulfate solution to one portion of test solution B in sequence. Shake well after adding each reagent, dilute to the scale with water, mix well, let stand and allow color to develop. To another portion of test solution B, add 10 mL of sodium tartarate solution, 10 mL of sodium hydroxide solution, 2 mL of ethanol and 5 mL of ammonium persulfate solution in sequence. Shake well after adding each reagent, dilute to the scale with water, mix well and let stand.

[0007] In S11, the mixed acid solution is a hydrochloric acid-nitric acid mixed solution, wherein the volume ratio of hydrochloric acid, nitric acid and water is 1:1:2.

[0008] In S13, the concentration of sodium tartrate solution is 300 g / L, the concentration of sodium hydroxide solution is 100 g / L, the concentration of dimethylglyoxime is 10 g / L, and it is prepared with ethanol having a volume fraction of more than 95%, and the concentration of ammonium persulfate solution is 40 g / L.

[0009] Step S2 specifically includes the following steps: S21: Prepare nickel standard solution: accurately weigh 0.1000g pure nickel, place it in a 150mL conical flask, add 20mL nitric acid, heat to dissolve, cool to room temperature, transfer to a 1000mL volumetric flask, dilute to scale with water, mix well, and obtain nickel stock solution; transfer 25.00mL nickel stock solution, place it in a 250mL volumetric flask, add 5mL nitric acid solution, dilute to scale with water, and mix well; S22: Draw a nickel standard working curve: pipette 0 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, and 10.00 mL of the nickel standard solution into a 50 mL volumetric flask, respectively, perform color development according to step S13, record the absorbance value, draw a standard working curve with the absorbance as the abscissa and the nickel amount as the ordinate, and then find the measured value of the nickel amount corresponding to the sample from the working curve; S23: Calculate the nickel content in the catalyst powder sample for artificial diamond: Calculate the nickel content in the sample according to the following formula, with mass fraction W Ni The value is expressed in %:

[0010] Where: m is the value of the corresponding nickel mass obtained from the calibration curve, in micrograms (µg); M is the value of the sample amount, in grams (g); V1 is the value of the total volume of the test solution, in milliliters (mL); V2 is the value of the volume of the test solution taken, in milliliters (mL).

[0011] In S21, the mass fraction of pure nickel is ≥99.99%.

[0012] In S21, the volume ratio of nitric acid to water in the nitric acid solution is 1:1.

[0013] In S22, the absorption wavelength selected for measuring absorbance is 530 nm.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention is designed for catalyst powder for artificial diamond in the field, and realizes accurate and rapid determination of such high-nickel materials by spectrophotometry through precise control and optimization of key steps such as sampling-dissolving-dilution-color development, and expands the scope of spectrophotometric determination of nickel content. In addition, the determination method of the present invention is simple to operate, has strong applicability, can effectively solve the problems of harsh measurement conditions and complicated operating procedures of the gravimetric method, and is convenient for the development of routine detection work. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of a standard working curve in the method for determining the nickel content in the catalyst powder for artificial diamond of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0017] During the specific operation of the present invention, the test environment and conditions are as follows: room temperature 5°C ~ 35°C, relative humidity ≤85%, no strong electromagnetic interference source and toxic and harmful gases in the room, the instrument is placed on a stable workbench, and the power supply used is: voltage 220V±22V, frequency 50Hz±1Hz single-phase alternating current.

[0018] Detection equipment: T10S double beam UV-visible spectrophotometer. The present invention is suitable for the determination of high nickel samples with a mass fraction of 10% to 50%.

[0019] Example 1 The method for determining the nickel content in the catalyst powder for artificial diamond disclosed in this embodiment is specifically implemented according to the following steps: S1: color development with the sample blank as reference; S2: Use the reagent blank as a reference to develop color according to the color development steps in S1, record the absorbance value, draw a standard working curve, find the corresponding nickel amount from the working curve, and calculate the nickel content in the sample.

[0020] In this embodiment, color development with the sample blank as a reference means that in the color development reaction, a solution containing no sample but all other reagents is used as a reference solution to eliminate the influence of other components in the sample on the color development reaction. In spectrophotometry, the color development reaction usually involves multiple reagents and samples. If the sample contains other components, these components may absorb light at the measurement wavelength, thereby affecting the accuracy of the color development reaction. In order to eliminate these interferences, the sample blank can be used as a reference solution. The sample blank refers to the measurement using the same reagents and solvents as the color development reaction without adding a sample, which ensures that the measurement results only reflect the influence of the color developer and other reagents, thereby more accurately reflecting the true situation of the sample. In specific operations, the absorbance of the sample blank and the sample is usually detected at the measurement wavelength. By subtracting the absorbance of the sample blank from the absorbance of the sample, a more accurate color development reaction result can be obtained. This method is very common in spectrophotometry, especially when determining specific components in a solution, such as iron content.

[0021] Using reagent blank as reference for color development means that in the color development reaction, the same reagent and solvent as the sample are used, but no sample solution is added, so as to eliminate the influence of solvent and other components on the color development reaction. In the color development reaction, the role of reagent blank is to ensure the accuracy of the measurement results. Specifically, the reagent blank is to eliminate the interference of solvent and other components on the color development reaction by measuring under the same conditions but without adding sample solution. This can more accurately reflect the concentration of the target component in the sample. When determining the iron content by spectrophotometry, the reagent blank solution is used as a reference, and the absorbance of iron is calculated by measuring the difference in absorbance between the sample solution and the reagent blank. This method can eliminate the absorption of light by solvents and other ions, thereby improving the accuracy of measurement. The use of reagent blank is very important in experiments because it can eliminate the interference of other substances in the solution that do not need to be measured and improve the accuracy of measurement. In various analytical methods, the use of reagent blank is to eliminate the interference caused by various coexisting colored substances in the color developer and the sample, offset the influence of the cuvette and reagent on the incident light, and thus adjust the percentage transmittance of the instrument to 100%.

[0022] Example 2 On the basis of Example 1, S1 specifically includes the following steps: S11: Weigh 0.1000g of the sample into a 100mL conical flask, slowly add 10mL of the mixed acid solution along the mouth of the conical flask, after the violent reaction is over, add another 10mL of the mixed acid solution into the conical flask, and then place the conical flask on an electric hot plate and heat until the solution inside the conical flask is clear and no obvious brown-yellow smoke is emitted; then add 3mL of perchloric acid into the conical flask, continue heating until perchloric acid smoke continues to be emitted for 1 minute, then remove the conical flask from the electric hot plate and cool it to obtain mother solution A; S12: Add 10 mL of distilled water to the mother solution A, then transfer the solution in the conical flask to a 200 mL volumetric flask, shake to volume, and then dry filter to obtain test solution B; S13: Pipette 1.00 mL of test solution B in two portions and place each portion in a 50 mL volumetric flask; Add 10 mL of sodium tartrate solution, 10 mL of sodium hydroxide solution, 2 mL of dimethylglyoxime solution and 5 mL of ammonium persulfate solution to one portion of test solution B in sequence. Shake well after adding each reagent, dilute to the scale with water, mix well, let stand and allow color to develop. To another portion of test solution B, add 10 mL of sodium tartarate solution, 10 mL of sodium hydroxide solution, 2 mL of ethanol and 5 mL of ammonium persulfate solution in sequence. Shake well after adding each reagent, dilute to the scale with water, mix well and let stand.

[0023] In this embodiment, diluting with water to the scale line means that when preparing the solution, the solution is added to the volumetric flask until the liquid level reaches the scale line on the volumetric flask. The specific steps are as follows: Preparation: Pour the solution to be diluted (such as concentrated sulfuric acid) into a volumetric flask; Dilution: Add an appropriate amount of solvent (such as water) to a volumetric flask, stirring while adding until the volume of the solution is close to the scale line of the volumetric flask; Volume adjustment: When the volume of the solution is close to the scale line, use a rubber-tipped dropper to add the solvent dropwise until the lowest point of the concave liquid surface of the solution is tangent to the scale line. This process ensures the accuracy of the volume of the solution, thereby obtaining a solution of accurate concentration.

[0024] Example 3 On the basis of Example 2, in S11, the mixed acid solution is a hydrochloric acid-nitric acid mixed solution, wherein the volume ratio of hydrochloric acid, nitric acid and water is 1:1:2.

[0025] Example 4 On the basis of Example 2, in S13, the concentration of sodium tartrate solution is 300 g / L, the concentration of sodium hydroxide solution is 100 g / L, the concentration of dimethylglyoxime is 10 g / L, and the solution is prepared with ethanol having a volume fraction of 95% or more, and the concentration of ammonium persulfate solution is 40 g / L.

[0026] Example 5 Based on Example 1, step S2 specifically includes the following steps: S21: Prepare nickel standard solution: accurately weigh 0.1000g pure nickel, place it in a 150mL conical flask, add 20mL nitric acid, heat to dissolve, cool to room temperature, transfer to a 1000mL volumetric flask, dilute to scale with water, mix well, and obtain nickel stock solution; transfer 25.00mL nickel stock solution, place it in a 250mL volumetric flask, add 5mL nitric acid solution, dilute to scale with water, and mix well; S22: Draw a nickel standard working curve: Pipette 0 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, and 10.00 mL of nickel standard solution into a 50 mL volumetric flask, develop color according to step S13, record the absorbance value, and draw the nickel standard working curve with the absorbance as the horizontal axis and the nickel content as the vertical axis. Figure 1 The standard working curve shown in the figure is used to find the measured value of the nickel content corresponding to the sample from the working curve; S23: Calculate the nickel content in the catalyst powder sample for artificial diamond: Calculate the nickel content in the sample according to the following formula, with mass fraction W Ni The value is expressed in %:

[0027] Where: m is the value of the corresponding nickel mass obtained from the calibration curve, in micrograms (µg); M is the value of the sample amount, in grams (g); V1 is the value of the total volume of the test solution, in milliliters (mL); V2 is the value of the volume of the test solution taken, in milliliters (mL).

[0028] Example 6 On the basis of Example 5, in S21, the mass fraction of pure nickel is ≥99.99%.

[0029] Example 7 Based on Example 5, in S21, the volume ratio of nitric acid to water in the nitric acid solution is 1:1.

[0030] Example 8 On the basis of Example 5, in S22, the absorption wavelength selected for measuring the absorbance is 530 nm.

[0031] Catalyst powder for artificial diamonds is mainly composed of iron and nickel. The effective ingredients and content requirements of common formulas are: iron accounts for about 70%, nickel accounts for about 30%, and other trace metals account for less than 3%.

[0032] The trivalent iron forms a light-colored complex with dimethylglyoxime, and this color has a small amount of absorption at 530nm. The present invention verifies whether the trivalent iron interferes with the determination of nickel through the following conditions test.

[0033] Take 2.00mL of nickel standard solution and add different amounts of Fe 3+ , the test was carried out according to the measuring steps of the present invention, and the measuring results are shown in Table 1.

[0034] Table 1

[0035] It can be seen from Table 1 that under the conditions of 50.0 μg nickel and 500 μg iron in the color developing solution, the absorbance values ​​of three parallel measurements of test group 7 are basically stable and the nickel content is consistent with that of test group 1 without iron addition. In the actual test, the sample size is 0.1000 g, corresponding to a total element content of 500 μg in the color developing solution, and the nickel content is about 150 μg, so the iron in the actual sample will not interfere with the determination of nickel.

[0036] If the sample contains cobalt, copper or manganese, it may also interfere with the determination of nickel due to the formation of colored complexes with the color developer dimethylglyoxime.

[0037] The interference test of cobalt on the determination of nickel content was carried out according to the following scheme, and the results are shown in Table 2.

[0038] Table 2

[0039] The test results in Table 2 show that 100 μg of cobalt in the colorimetric solution will not affect the nickel measurement results, that is, cobalt within 20% in the sample will not interfere with the nickel determination, while the cobalt content in the actual sample is far less than 20%. Therefore, cobalt will not interfere with the nickel determination.

[0040] 2.00 mL of nickel standard solution was taken, different amounts of copper were added, and the nickel content in the solution was analyzed according to the determination method of the present invention. The results are shown in Table 3.

[0041] Table 3

[0042] As can be seen from Table 3, when the content of trace elements in the actual sample accounts for 3% as the copper addition amount (test group 2), the measured nickel content is basically consistent with the nickel standard solution of test group 1. The copper content in the actual sample was increased by 10 times for interference test. The measurement results of test group 3 were the same as those of 1 and 2, and the repeatability of the three parallel determination results was good. Therefore, the copper in the actual sample will not interfere with the determination of nickel.

[0043] The interference test of manganese on nickel content determination was carried out according to the above copper scheme, and the results are shown in Table 4.

[0044] Table 4

[0045] As shown in Table 4, when the interference experiment was conducted with 10 times the highest content of trace elements in the actual sample, the absorbance of the solution was consistent with the measurement results of the actual sample and the nickel standard solution, and the numerical stability was consistent with the theoretical value. Therefore, the manganese element in the catalyst powder for artificial diamond will not interfere with the determination of nickel.

[0046] Example 9 According to the present invention, 10 parallel measurements were performed on the standard sample and the actual sample, and the measurement results are shown in Table 5.

[0047] Table 5

[0048] It can be seen from Table 5 that the determination method of the present invention has higher measurement precision.

[0049] Example 10 The 25.0 μg / mL standard solution prepared from the pure nickel standard sample YSBC11907Z was used to conduct a spike recovery test on the actual sample. The test plan and results are shown in Table 6.

[0050] Table 6

[0051] As can be seen from Table 6, the recovery of the amount of nickel is in the range of 99% to 101%. Therefore, the determination method of the present invention has a high accuracy.

[0052] Combining Table 5 and Table 6, it can be obtained that the determination precision represented by relative standard deviation and the correctness represented by spiked recovery rate of the present invention are both high, that is, the accuracy of the determination method is high.

[0053] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0054] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0055] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining the nickel content in catalyst powder for artificial diamond, characterized in that: Follow the steps below to implement it: S1: color development with the sample blank as reference; S2: Use the reagent blank as a reference to develop color according to the color development steps in S1, record the absorbance value, draw a standard working curve, find the corresponding nickel amount from the working curve, and calculate the nickel content in the sample.

2. The method for determining the nickel content in catalyst powder for artificial diamond according to claim 1, characterized in that: The S1 specifically includes the following steps: S11: Weigh 0.1000g of the sample into a 100mL conical flask, slowly add 10mL of the mixed acid solution along the mouth of the conical flask, after the violent reaction is over, add another 10mL of the mixed acid solution into the conical flask, and then place the conical flask on an electric hot plate and heat until the solution inside the conical flask is clear and no obvious brown-yellow smoke is emitted; then add 3mL of perchloric acid into the conical flask, continue heating until perchloric acid smoke continues to be emitted for 1 minute, then remove the conical flask from the electric hot plate and cool it to obtain mother solution A; S12: Add 10 mL of distilled water to the mother solution A, then transfer the solution in the conical flask to a 200 mL volumetric flask, shake to volume, and then dry filter to obtain test solution B; S13: Pipette 1.00 mL of test solution B in two portions and place each portion in a 50 mL volumetric flask; Add 10 mL of sodium tartrate solution, 10 mL of sodium hydroxide solution, 2 mL of dimethylglyoxime solution and 5 mL of ammonium persulfate solution to one portion of test solution B in sequence. Shake well after adding each reagent, dilute to the scale with water, mix well, let stand and allow color to develop. To another portion of test solution B, add 10 mL of sodium tartarate solution, 10 mL of sodium hydroxide solution, 2 mL of ethanol and 5 mL of ammonium persulfate solution in sequence. Shake well after adding each reagent, dilute to the scale with water, mix well and let stand.

3. The method for determining the nickel content in the catalyst powder for artificial diamond according to claim 2, characterized in that: In S11, the mixed acid solution is a hydrochloric acid-nitric acid mixed solution, wherein the volume ratio of hydrochloric acid, nitric acid and water is 1:1:

2.

4. The method for determining the nickel content in catalyst powder for artificial diamond according to claim 2, characterized in that: In S13, the concentration of sodium tartrate solution is 300 g / L, the concentration of sodium hydroxide solution is 100 g / L, the concentration of dimethylglyoxime is 10 g / L, and the solution is prepared with ethanol having a volume fraction of 95% or more, and the concentration of ammonium persulfate solution is 40 g / L.

5. The method for determining the nickel content in catalyst powder for artificial diamond according to claim 1, characterized in that: The step S2 specifically includes the following steps: S21: Prepare nickel standard solution: accurately weigh 0.1000g pure nickel, place it in a 150mL conical flask, add 20mL nitric acid, heat to dissolve, cool to room temperature, transfer to a 1000mL volumetric flask, dilute to scale with water, mix well, and obtain nickel stock solution; transfer 25.00mL nickel stock solution, place it in a 250mL volumetric flask, add 5mL nitric acid solution, dilute to scale with water, and mix well; S22: Draw a nickel standard working curve: pipette 0 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, and 10.00 mL of the nickel standard solution into a 50 mL volumetric flask, respectively, perform color development according to step S13, record the absorbance value, draw a standard working curve with the absorbance as the abscissa and the nickel amount as the ordinate, and then find the measured value of the nickel amount corresponding to the sample from the working curve; S23: Calculate the nickel content in the catalyst powder sample for artificial diamond: Calculate the nickel content in the sample according to the following formula, with mass fraction W Ni The value is expressed in %: Where: m is the value of the corresponding nickel mass obtained from the calibration curve, in micrograms (µg); M is the value of the sample amount, in grams (g); V1 is the value of the total volume of the test solution, in milliliters (mL); V2 is the value of the volume of the test solution taken, in milliliters (mL).

6. The method for determining the nickel content in catalyst powder for artificial diamond according to claim 5, characterized in that: In the S21, the mass fraction of pure nickel is ≥99.99%.

7. The method for determining the nickel content in catalyst powder for artificial diamond according to claim 5, characterized in that: In S21, the volume ratio of nitric acid to water in the nitric acid solution is 1:

1.

8. The method for determining the nickel content in catalyst powder for artificial diamond according to claim 5, characterized in that: In S22, the absorption wavelength selected for measuring absorbance is 530 nm.

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