Precipitant for precipitating silver base body, method of production and use

Abstract

The application provides a precipitant for precipitating a silver base body, a preparation method and application, and the precipitant comprises potassium thiocyanate, an auxiliary complexing agent, trace rare earth elements, a synergist and trace selenium compounds; wherein the auxiliary complexing agent is at least one of pyrrolidone, N-ethyl-N-methyl aminoacetic acid or a combination thereof; the trace selenium compounds are sodium selenite or sodium selenate, the addition amount of the trace selenium compounds is 0.001%-0.05% of the total mass of the precipitant; and the mass ratio of the auxiliary complexing agent to the trace selenium compounds is 20:1-60:1. Through optimization of component allocation and auxiliary additives, rapid precipitation of silver elements is realized, and the application is suitable for various scenes such as element content analysis of silver alloy products and harmful element migration amount detection of silver tableware.

Description

Technical Field

[0001] This invention relates to the field of silver precipitant technology, and more particularly to a precipitant for precipitating silver matrix, its preparation method, and its application. Background Technology

[0002] Silver matrix precipitation is widely used in metallurgy, chemical analysis, and materials science, playing a crucial role, especially in the recovery of silver alloys and the detection of impurities in high-purity silver. Traditional precipitation methods typically use precipitants such as chlorides and sulfides, but these methods suffer from slow precipitation rates, poor selectivity, and unstable results, leading to separation purity and efficiency that cannot meet the requirements of precision analysis and quality control.

[0003] Therefore, this invention is proposed. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a precipitant for silver matrix precipitation. By rationally proportioning potassium thiocyanate, auxiliary complexing agent, trace rare earth elements, synergist, and trace selenide, it significantly improves the separation efficiency and analytical accuracy of silver matrix, meeting the practical needs for silver alloy element content detection and high-purity silver impurity content detection. This provides a reliable, stable, and cost-effective technical solution for related industries and analytical testing.

[0005] In order to achieve the objective of this invention, the following technical solution is adopted: This invention provides a precipitant for precipitating a silver matrix, the precipitant comprising potassium thiocyanate, an auxiliary complexing agent, trace rare earth elements, a synergist, and trace selenides; The auxiliary complexing agent is at least one of pyrrolidone, N-ethyl-N-methylaminoacetic acid, or a combination thereof; the trace selenide is sodium selenite or sodium selenate, and the amount of the trace selenide added is 0.001%-0.05% of the total mass of the precipitant; the mass ratio of the auxiliary complexing agent to the trace selenide is 20:1-60:1.

[0006] Furthermore, the auxiliary complexing agent is a mixture of pyrrolidone and N-ethyl-N-methylaminoacetic acid, wherein the mass ratio of pyrrolidone to N-ethyl-N-methylaminoacetic acid is 1:1 to 2:1.

[0007] Furthermore, the trace rare earth element is any one of lanthanum, cerium, samarium, or yttrium, and the amount of the trace rare earth element added is 0.001%-0.1% of the total mass of the precipitant.

[0008] Further, the synergist is at least one selected from sodium dihydrogen phosphate, malic acid, tartaric acid, or a combination thereof, and the mass ratio of the synergist to the trace selenide is 10:1-30:1.

[0009] Furthermore, the synergist is a mixture of sodium dihydrogen phosphate and malic acid, wherein the mass ratio of sodium dihydrogen phosphate to malic acid is 1:1-5:1.

[0010] Furthermore, the mass ratio of potassium thiocyanate to the auxiliary complexing agent is 10:1-30:1.

[0011] The present invention also provides a method for preparing the above-mentioned precipitant for a silver-based precipitate, comprising the following steps: Dissolve potassium thiocyanate in water to form a mother liquor; The auxiliary complexing agent is dissolved in water and mixed with the mother liquor to obtain a mixture; Trace amounts of rare earth elements are added to the mixture in the form of soluble salts, along with an synergist, and stirred until homogeneous. After dissolving trace amounts of selenide, add it to the mixture, stir until homogeneous, and adjust the pH of the solution to 4.5-6 to obtain the precipitant.

[0012] The present invention also provides a method for separating a silver matrix using the above-mentioned precipitant, comprising the following steps: The silver-containing solution is mixed with the precipitant to obtain a mixture; A complexing regulator is added to the mixture, and the mixture is allowed to stand for a certain period of time to form a precipitate; Separate the precipitate to obtain the liquid after precipitation.

[0013] Furthermore, the complexing regulator is mannitol or sorbitol, and the amount of the complexing regulator added is 0.1%-0.5% of the total mass of the precipitant solution.

[0014] The present invention also provides an application of the above-mentioned precipitant in the determination of the content of 21 impurity elements in high-purity silver.

[0015] The present invention has the following technical effects: The precipitant provided by this invention achieves highly efficient precipitation of silver ions through a rational ratio of potassium thiocyanate and auxiliary complexing agent. The precipitation is rapid and produces a uniform precipitate, avoiding the problems of incomplete reaction or precipitate redissolution in traditional precipitation methods. This significantly improves the efficiency and reliability of silver matrix separation, meeting the high purity requirements of precision analysis and industrial applications. The introduction of trace rare earth elements and synergists enhances the stability and controllability of the precipitant during precipitation. Trace rare earth elements improve the physicochemical properties of the precipitate, while synergists enhance precipitation selectivity, ensuring high efficiency under different conditions and significantly improving the accuracy and repeatability of analytical results. The application of trace selenides enables the precipitant to exhibit excellent selectivity in complex systems, allowing for precise precipitation of silver ions. Furthermore, the synergistic effect of the auxiliary complexing agent and synergist makes the precipitation process mild and controllable, resulting in stable and easily separated precipitates. This further improves the reliability and ease of operation for elemental detection in silver alloy products and the testing of high-purity silver impurity content. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0017] In a first aspect, the present invention provides a precipitant for precipitating a silver matrix, the precipitant comprising potassium thiocyanate, an auxiliary complexing agent, trace rare earth elements, a synergist, and trace selenides; The auxiliary complexing agent is at least one of pyrrolidone, N-ethyl-N-methylaminoacetic acid, or a combination thereof; the trace selenide is sodium selenite or sodium selenate, and the amount of the trace selenide added is 0.001%-0.05% of the total mass of the precipitant; the mass ratio of the auxiliary complexing agent to the trace selenide is 20:1-60:1.

[0018] In some embodiments, the auxiliary complexing agent is a mixture of pyrrolidone and N-ethyl-N-methylaminoacetic acid, wherein the mass ratio of pyrrolidone to N-ethyl-N-methylaminoacetic acid is 1:1 to 2:1.

[0019] In some embodiments, the trace rare earth element is any one of lanthanum, cerium, samarium or yttrium, and the amount of the trace rare earth element added is 0.001%-0.1% of the total mass of the precipitant.

[0020] In some embodiments, the synergist is at least one selected from sodium dihydrogen phosphate, malic acid, tartaric acid, or combinations thereof, and the mass ratio of the synergist to the trace selenide is 10:1-30:1.

[0021] In some embodiments, the synergist is a mixture of sodium dihydrogen phosphate and malic acid, wherein the mass ratio of sodium dihydrogen phosphate to malic acid is 1:1 to 5:1.

[0022] In some embodiments, the mass ratio of potassium thiocyanate to the auxiliary complexing agent is 10:1 to 30:1.

[0023] Secondly, the present invention also provides a method for preparing the above-mentioned precipitant for a silver-based precipitate, characterized by comprising the following steps: Dissolve potassium thiocyanate in water to form a mother liquor; The auxiliary complexing agent is dissolved in water and mixed with the mother liquor to obtain a mixture; Trace amounts of rare earth elements are added to the mixture in the form of soluble salts, along with an synergist, and stirred until homogeneous. After dissolving trace amounts of selenide, add it to the mixture, stir until homogeneous, and adjust the pH of the solution to 4.5-6 to obtain the precipitant.

[0024] Preferably, the trace rare earth element is added to the mixture in the form of nitrate.

[0025] Thirdly, the present invention also provides a method for separating a silver matrix using the above-mentioned precipitant solution, comprising the following steps: The silver-containing solution is mixed with the precipitant to obtain a mixture; A complexing regulator is added to the mixture, and the mixture is allowed to stand for a certain period of time to form a precipitate; Separate the precipitate to obtain the liquid after precipitation.

[0026] In some embodiments, the complexing regulator is mannitol or sorbitol, and the amount of the complexing regulator added is 0.1%-0.5% of the total mass of the precipitant solution.

[0027] Fourthly, the present invention also provides the application of the precipitant as described above in the determination of the content of 21 impurity elements in high-purity silver.

[0028] The following is a detailed explanation using specific embodiments: Example 1: Preparation and use of precipitants for silver matrix precipitation Step 1: Preparation of precipitant Dissolve 20g of potassium thiocyanate in 100mL of deionized water and stir until completely dissolved to obtain the mother liquor; Take a mixture of 10g pyrrolidone and 5g N-ethyl-N-methylaminoacetic acid, add it to 100mL of deionized water and stir until completely dissolved; Take 1g of rare earth element lanthanum salt and add it to a solution containing pyrrolidone and N-ethyl-N-methylaminoacetic acid. Continue stirring to ensure that the lanthanum is completely dissolved. Take a mixture of 1g sodium dihydrogen phosphate and 2g malic acid, add it to the above solution, and stir until well mixed; Take 0.05g of sodium selenite, dissolve it in 50mL of deionized water, add it to the above solution, and continue to stir until the sodium selenite is completely dissolved. Adjust the pH of the solution to 5.5, and finally, the precipitant solution is obtained.

[0029] Experimental Example 1: Determination of the content of 21 impurity elements in high-purity silver 1.1 Preparation of a mixed standard solution of 21 elements Prepare mixed standard solutions of Sb, Se, Te, Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Si, Sn, Ti, Zn, Ba, and Hg, with mass concentrations of 0, 0.5, 1.0, 1.5, 2.0, and 4.0 mg / L, respectively.

[0030] 1.2 Sample Preparation Accurately weigh 0.50g of silver granules into a 50mL polytetrafluoroethylene beaker, dissolve the sample in nitric acid solution, and gently heat until the brownish-yellow fumes disappear.

[0031] After the sample has cooled, take 5.00 mL of the above silver-containing solution into a 100 mL centrifuge tube or beaker; Add 5 mL of the precipitant solution prepared in Example 1 and shake gently. Add approximately 0.25% mannitol (based on the total volume of the precipitant solution) and mix thoroughly. After standing for 30 minutes, a yellowish-white precipitate was observed to have completely formed. The precipitate was then centrifuged at 4000 rpm for 10 minutes.

[0032] Collect the supernatant or filtrate and record it as the test solution.

[0033] 1.3 ICP-OES determination 1.3.1 Selection of Spectral Lines ICP-OES determination of the test solution The preferred analytical spectra are those specified in GB / T 38162-2019 and those recommended by the instrument. Since the silver matrix is ​​separated by a precipitant, the high concentration of silver matrix is ​​filtered out as a precipitate. The analytical spectra after eliminating interfering spectra are shown in Table 1 below.

[0034] Table 1 Analytical Spectral Lines of Elements 1.3.2 Linear Equation and Detection Limit According to IUPAC regulations, the limit of detection is calculated as three times the standard deviation of 20 consecutive measurements of the blank solution.

[0035] The linear equations, correlation coefficients, and detection limits for the 21 elements are shown in Table 2. Table 2 shows that within the mass concentration range of 0-4.0 mg / L, the spectral intensity exhibits a good linear relationship with the concentration, with correlation coefficients all greater than 0.9946. The detection limits range from 0.0001 to 0.0205 mg / L, indicating that this method has high sensitivity.

[0036] Table 2 Linear equations, correlation coefficients, and detection limits 1.3.3 Precision and Spike Recovery Test Eighteen standard silver samples were weighed and processed according to the sample method described in section 1.2 above. Then, mixed standard solutions of different concentrations (0.5, 1.0, and 2.0 mg / L) were added to the test solutions. The samples were tested according to the instrument operating conditions. The relative standard deviation (n=6) and average spike recovery rate of the sample determination results are shown in Table 3.

[0037] Table 3. Results of precision and spike recovery experiments The results show that, within the linear range of 0-4.0 mg / L, the relative standard deviations (RSD, n = 6) for spiking amounts of 0.5, 1.0, and 2.0 mg / L were 0.29%-1.78%, 0.41%-2.32%, and 0.29%-2.24%, respectively, with recoveries of 85.7%-106.2%, 85.9%-103.7%, and 86.7%-102.1%, respectively. These results indicate that this method is suitable for the determination of 21 impurity elements, including tin and arsenic, in high-purity silver.

[0038] (4) Determination of actual samples The high-purity silver jewelry sold on the market was tested according to the above testing methods, and the results are shown in Table 4 below.

[0039] Table 4 shows that antimony, zinc, lead, nickel, silicon, manganese, iron, magnesium, copper, aluminum, chromium, and barium were detected in the tested samples. In comparison, the current national standard GB / T 38162-2019 does not include barium in its test elements, and the GB / T 11067 series standards do not include test methods for nickel, manganese, silicon, magnesium, aluminum, chromium, and barium. Therefore, the precipitant provided in this application is suitable for determining the content of impurity elements in high-purity silver products.

[0040] Table 4. Measurement results of actual samples Based on the experimental process and results of Example 1, it can be seen that the precipitant of the silver matrix prepared by the present invention has significant advantages in the separation and determination of impurity elements in high-purity silver samples.

[0041] During the experiment, by precisely proportioning potassium thiocyanate, auxiliary complexing agent, trace rare earth elements, synergist, and trace sodium selenite, a precipitant was prepared that rapidly generated a uniform yellowish-white precipitate under controlled pH conditions of 5.5, achieving efficient removal of the silver matrix. Subsequently, by adding a small amount of mannitol to adjust the complexation, and after standing for 30 minutes, centrifugation was performed. The supernatant contained almost no silver, ensuring the accuracy of subsequent ICP-OES determinations.

[0042] Experimental results showed that, within the concentration range of 0-4.0 mg / L, the spectral intensity of the 21 analytes exhibited a good linear relationship with the concentration, with linear correlation coefficients all greater than 0.9946. The method detection limit was as low as 0.0001-0.0205 mg / L, indicating that the method has high sensitivity.

[0043] In the spiked recovery test, the relative standard deviation (RSD) at different concentrations was only 0.29%-2.32%, and the spiked recovery rate was between 85.7%-106.2%, further verifying the stability and reliability of the precipitant in the analysis. Determination on actual high-purity silver jewelry showed that the precipitant can effectively detect impurity elements including Sb, Zn, Pb, Ni, Si, Mn, Fe, Mg, Cu, Al, Cr, and Ba. Some of these elements are not fully covered by current standards, indicating that the precipitant of this invention not only improves the separation efficiency of the silver matrix in practical applications but also expands the detection range of impurity elements, meeting the needs of high-purity silver product quality control and food silverware safety testing.

[0044] Overall, this precipitant achieves rapid, controllable, stable, and easy separation through component optimization and synergistic effects, providing reliable technical support for high-precision elemental analysis and demonstrating broad potential for industrial and analytical applications.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not change the essence of the corresponding technical solutions.

Claims

1. A method for preparing a precipitant for precipitating a silver matrix, characterized in that, Includes the following steps: Dissolve potassium thiocyanate in water to form a mother liquor; The auxiliary complexing agent is dissolved in water and mixed with the mother liquor to obtain a mixture; Trace amounts of rare earth elements are added to the mixture in the form of soluble salts, along with an synergist, and stirred until homogeneous. The trace amount of selenide was dissolved and added to the mixture, stirred evenly, and the pH of the solution was adjusted to 4.5-6 to obtain the precipitant. The precipitant includes potassium thiocyanate, auxiliary complexing agent, trace rare earth elements, synergist and trace selenide; Wherein, the auxiliary complexing agent is at least one of pyrrolidone, N-ethyl-N-methylaminoacetic acid, or a combination thereof; the trace selenide is sodium selenite or sodium selenate, and the amount of the trace selenide added is 0.001%-0.05% of the total mass of the precipitant; the mass ratio of the auxiliary complexing agent to the trace selenide is 20:1-60:1; The amount of the trace rare earth element added is 0.001%-0.1% of the total mass of the precipitant; The synergist is selected from at least one of sodium dihydrogen phosphate, malic acid, tartaric acid, or combinations thereof, and the mass ratio of the synergist to the trace selenide is 10:1-30:

1.

2. The preparation method according to claim 1, characterized in that, The auxiliary complexing agent is a mixture of pyrrolidone and N-ethyl-N-methylaminoacetic acid, wherein the mass ratio of pyrrolidone to N-ethyl-N-methylaminoacetic acid is 1:1 to 2:

1.

3. The preparation method according to claim 1, characterized in that, The trace rare earth element is any one of lanthanum, cerium, samarium, or yttrium.

4. The preparation method according to claim 1, characterized in that, The synergist is a mixture of sodium dihydrogen phosphate and malic acid, wherein the mass ratio of sodium dihydrogen phosphate to malic acid is 1:1-5:

1.

5. The preparation method according to claim 1, characterized in that, The mass ratio of potassium thiocyanate to the auxiliary complexing agent is 10:1-30:

1.

6. A method for separating a silver matrix using a precipitate prepared by the method for preparing a precipitate according to any one of claims 1-5, characterized in that, Includes the following steps: The silver-containing solution is mixed with the precipitant to obtain a mixture; A complexing regulator is added to the mixture, and the mixture is allowed to stand for a certain period of time to form a precipitate; Separate the precipitate to obtain the liquid after precipitation.

7. The method according to claim 6, characterized in that, The complexing regulator is mannitol or sorbitol, and the amount of the complexing regulator added is 0.1%-0.5% of the total mass of the precipitant solution.

8. The application of a precipitant prepared by the preparation method according to any one of claims 1-5 in the determination of the content of 21 impurity elements in high-purity silver.

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