Electrochemical method for detecting copper ion impurities in zinc electrolyte

Abstract

The application discloses an electrochemical detection method for copper ion impurities in zinc electrolyte, wherein acetic acid-sodium acetate solution is used as a background solution, then mixed with an equal volume of zinc electrolyte to obtain a to-be-detected solution, and the pH value of the to-be-detected solution is adjusted to 3.0-4.0; silver nanowires are dispersed in an ethanol solution, then coated on FTO conductive glass as a working electrode, a platinum sheet is used as a counter electrode, and an Ag / AgCl electrode is used as a reference electrode; and an electrochemical workstation is used to obtain the oxidation current of copper ions after reduction deposition in the to-be-detected solution by differential pulse anodic stripping voltammetry I Cu , in the unit of muA; the concentration of copper ions in the to-be-detected solution C Cu is obtained by the following formula: C Cu ( I Cu + 2.69) / 151.55, in the unit of mg / L. The application realizes the detection of trace copper ion impurities in high-zinc-concentration electrolyte, is convenient to operate, does not need expensive equipment, and is suitable for real-time detection in a production environment.

Description

Technical Field

[0001] This invention belongs to the field of zinc metallurgy, and specifically relates to an electrochemical detection method for copper ion impurities in zinc electrolyte. Background Technology

[0002] In the zinc hydrometallurgical process, the concentration of impurity ions such as copper, cobalt, and nickel must be strictly controlled, otherwise it will cause abnormalities in the electrolysis process. For example, excessive copper ion content during electrolysis can cause adverse factors such as cathode burn-out and a decrease in zinc electrodeposition current density. Therefore, rapid and convenient detection of impurity ion concentration in the electrolyte is crucial.

[0003] The zinc ion concentration in zinc electrolytes is as high as 40 g / L to 50 g / L, while the concentration of impurity ions is as low as below 1 mg / L, showing a significant difference. The excessively high zinc ion concentration in the background solution severely interferes with the detection of trace impurities. For example, the copper impurity content in zinc electrolytes is required to be no more than 0.5 mg / L, and the Zn / Cu ratio in the electrolyte exceeds 80,000. The excessively high zinc concentration in the background solution makes the detection of copper in the electrolyte difficult.

[0004] Chinese patent (CN201810830599.X, Optimization Method of Masking Test System for Trace Ion Concentration Detection in Zinc Solution) proposes a method to mask background zinc ions to achieve the detection of trace impurities. However, this method requires the introduction of EDTA, the colorimetric reagent nitrosoR salt, and the use of a UV-Vis absorption spectrometer with high requirements for the working environment. Chinese patent (CN201710517844.7, A Method for Simultaneous Determination of Copper, Cadmium, Nickel and Cobalt Content in Zinc Electrolyte) proposes a method for simultaneously determining multiple trace impurities such as copper, cadmium, nickel, and cobalt in zinc electrolyte. However, this method requires the introduction of dimethylglyoxime contaminant and the measurement conversion method is complex. Chinese patent (CN201911100771.7, Preparation of a Copper Ion Electrochemical Sensor) proposes an electrochemical detection method for heavy metal copper ions, but it is not aimed at the detection of trace copper ions in zinc electrolyte and does not solve the interference problem of high concentration of zinc ions in the background solution. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide an electrochemical detection method for copper ion impurities in zinc electrolytes, which has the following significant advantages: 1) The influence of zinc ion concentration on trace copper ion detection can be essentially eliminated by diluting the zinc ion concentration in the electrolyte by half, making the operation extremely simple; 2) The test substrate solution used is an acetate-sodium acetate solution, which does not require volatile or toxic organic compounds, making it environmentally friendly; 3) No expensive analytical detection equipment is required, only an electrochemical workstation is needed, allowing for detection and analysis to be carried out in complex on-site working environments, facilitating rapid online analysis. The specific process is as follows:

[0006] An electrochemical detection method for copper ion impurities in zinc electrolyte includes the following steps:

[0007] S1. Use 0.05mol / L~0.2mol / L acetate-sodium acetate solution as background solution, then add zinc electrolyte. The volume of zinc electrolyte added must be strictly controlled to be equal to the volume of the background solution to obtain a mixed test solution. The pH value of the test solution is adjusted to 3.0~4.0 with NaOH.

[0008] S2. Silver nanowires were dispersed in an ethanol solution and then coated onto FTO conductive glass as the working electrode. A platinum sheet was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. The oxidation current after copper ion reduction and deposition in the test solution was obtained using differential pulse anodic stripping voltammetry on an electrochemical workstation. I Cu The unit is μA;

[0009] S3. Concentration of copper ions in the solution to be tested C Cu Obtain it using the following formula: C Cu =( I Cu +2.69) / 151.55, unit is mg / L.

[0010] In step S2, the anodic stripping voltammetry deposition time is 10 minutes, and the deposition potential relative to the reference electrode is -0.6 to -0.8 V.

[0011] The zinc ion concentration in the zinc electrolyte described in step S1 is 40 g / L ~ 50 g / L, Cu 2+ The concentration is 0.1 mg / L to 1 mg / L.

[0012] The silver nanowire electrode described in step S2 can be reused at least 10 times.

[0013] The measurement error of copper ions in step S3 is less than 5%.

[0014] The significant advantages of this invention are:

[0015] 1) Simply diluting the zinc ion concentration in the electrolyte by half can essentially eliminate the influence of zinc ion concentration on the detection of trace copper ions, making the operation extremely simple.

[0016] 2) The test substrate solution used is an acetic acid-sodium acetate solution, which does not require volatile or toxic organic compounds and is environmentally friendly;

[0017] 3) No expensive analytical testing equipment is required; only an electrochemical workstation is needed. Detection and analysis can be carried out in complex on-site working environments, facilitating rapid online analysis. Attached Figure Description

[0018] Figure 1 The relationship between the electrochemical detection signal of copper ions and the zinc ion concentration after mixing electrolytes with different zinc ion concentrations and an equal volume of acetic acid-sodium acetate solution;

[0019] Figure 2 The linear relationship between the detection signal of copper ions and the concentration after diluting the electrolyte by half (45 g / L). Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0021] like Figure 1 As shown, the zinc ion concentration in the electrolyte significantly affects the electrochemical response signal value of copper ions, but the effect is minimal when it does not exceed 30 g / L. Considering that the actual zinc ion concentration in the electrolyte is between 40 g / L and 50 g / L, a 1 / 2 dilution falls exactly within the 20 g / L to 25 g / L range where the effect is minimal. Although further dilution over a larger range would not significantly reduce the concentration of the mixed solution, excessively large dilutions would further reduce the concentration of copper ions in the diluted solution, resulting in a lower electrochemical signal and increased difficulty in identification. Therefore, this invention mixes an equal volume of zinc electrolyte with a background acetic acid-sodium acetate solution, diluting the zinc electrolyte to be tested by exactly 1 / 2, thus avoiding the influence of high zinc concentration on copper ion detection while ensuring that the electrochemical signal of trace copper ions is easily identifiable.

[0022] like Figure 2 As shown, for a zinc electrolyte with a zinc ion concentration of 45 g / L, after mixing it with an equal volume of acetic acid and sodium acetate, the zinc ion concentration in the mixture is 22.5 g / L. By changing the copper ion concentration in the zinc electrolyte, the corresponding electrochemical response current signal was obtained and linearly fitted with the copper ion concentration. The resulting standard curve y = 151.55x - 2.69 showed a high degree of fit of 0.9980, demonstrating the reliability of copper ion detection. The above-mentioned inventive concept is further illustrated by the following embodiments:

[0023] Example 1

[0024] Prepare 100 mL of 0.05 mol / L acetic acid-sodium acetate solution, then add 100 mL of zinc electrolyte, wherein the zinc ion concentration in the zinc electrolyte is 50 g / L. -1 The zinc ion concentration in the mixed solution is 25 g / L. -1The pH of the mixed solution was adjusted to 3.0 using NaOH solution. A platinum sheet was used as the counter electrode, an Ag / AgCl electrode as the reference electrode, and FTO conductive glass coated with silver nanowires was used as the working electrode. The response current signal was measured using differential pulse anodic stripping voltammetry on an electrochemical workstation. I Cu The value is 32 μA, where the precipitation potential is controlled to be -0.6 V relative to the reference electrode, according to the formula... C Cu =( I Cu +2.69) / 151.55, then the Cu in the zinc electrolyte to be tested... 2+ The concentration was 0.23 mg / L. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to determine the concentration of Cu in the test solution. 2+ The concentration was 0.25 mg / L, with an error of 8%. After repeated testing 10 times with this working electrode, the Cu in the zinc electrolyte was measured. 2+ The concentration is 0.24 mg / L.

[0025] Example 2

[0026] Prepare 50 mL of a 0.2 mol / L acetic acid-sodium acetate solution, then add 50 mL of zinc electrolyte, wherein the zinc ion concentration in the zinc electrolyte is 40 g / L. -1 The zinc ion concentration in the mixed solution is 20 g / L. -1 The pH of the mixed solution was adjusted to 4.0 using NaOH solution. A platinum sheet was used as the counter electrode, an Ag / AgCl electrode as the reference electrode, and FTO conductive glass coated with silver nanowires was used as the working electrode. The response current signal was measured using differential pulse anodic stripping voltammetry on an electrochemical workstation. I Cu The value is 72 μA, where the precipitation potential is controlled at -0.8 V relative to the reference electrode, according to the formula... C Cu =( I Cu +2.69) / 151.55, then the Cu in the zinc electrolyte to be tested... 2+ The concentration was 0.49 mg / L. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to determine the concentration of Cu in the test solution. 2+ The concentration was 0.51 mg / L, with an error of 4%. After repeated testing 10 times with this working electrode, the Cu in the zinc electrolyte was measured. 2+ The concentration is 0.48 mg / L.

[0027] Example 3

[0028] Prepare 50 mL of a 0.1 mol / L acetic acid-sodium acetate solution, then add 50 mL of zinc electrolyte, wherein the zinc ion concentration in the zinc electrolyte is 45 g / L. -1The zinc ion concentration in the mixed solution was 22.5 g / L. -1 The pH of the mixed solution was adjusted to 3.5 using NaOH solution. A platinum sheet was used as the counter electrode, an Ag / AgCl electrode as the reference electrode, and FTO conductive glass coated with silver nanowires was used as the working electrode. The response current signal was measured using differential pulse anodic stripping voltammetry on an electrochemical workstation. I Cu The value is 110 μA, where the precipitation potential is controlled to be -0.7 V relative to the reference electrode, according to the formula... C Cu =( I Cu +2.69) / 151.55, then the Cu in the zinc electrolyte to be tested... 2+ The concentration was 0.74 mg / L. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to determine the Cu concentration in the test solution. 2+ The concentration was 0.78 mg / L, with an error of 5%. After repeated testing 10 times with this working electrode, the Cu in the zinc electrolyte was measured. 2+ The concentration is 0.75 mg / L.

[0029] Example 4

[0030] Prepare 80 mL of a 0.15 mol / L acetic acid-sodium acetate solution, then add 80 mL of zinc electrolyte, wherein the zinc ion concentration in the zinc electrolyte is 45 g / L. -1 The zinc ion concentration in the mixed solution was 22.5 g / L. -1 The pH of the mixed solution was adjusted to 3 using NaOH solution. A platinum sheet was used as the counter electrode, an Ag / AgCl electrode as the reference electrode, and FTO conductive glass coated with silver nanowires was used as the working electrode. The response current signal was measured using differential pulse anodic stripping voltammetry on an electrochemical workstation. I Cu The value is 152 μA, where the precipitation potential is controlled to be -0.7 V relative to the reference electrode, according to the formula... C Cu =( I Cu +2.69) / 151.55, then the Cu in the zinc electrolyte to be tested... 2+ The concentration was 1.02 mg / L. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to determine the Cu concentration in the test solution. 2+ The concentration was 1.00 mg / L, with an error of 2%. After repeated testing 8 times with this working electrode, the Cu in the zinc electrolyte was measured. 2+ The concentration was 1.03 mg / L.

[0031] Table 1 Comparison of Parameters in Examples

[0032]

[0033] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the protection scope of the claims of this invention.

Claims

1. An electrochemical detection method for copper ion impurities in zinc electrolyte, characterized in that, Includes the following steps: S1. Use 0.05mol / L~0.2mol / L acetate-sodium acetate solution as background solution, then add zinc electrolyte. The volume of zinc electrolyte added must be strictly controlled to be equal to the volume of the background solution to obtain a mixed test solution. The pH value of the test solution is adjusted to 3.0~4.0 with NaOH. S2. Silver nanowires were dispersed in an ethanol solution and then coated onto FTO conductive glass as the working electrode. A platinum sheet was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. The oxidation current after copper ion reduction and deposition in the test solution was obtained using differential pulse anodic stripping voltammetry on an electrochemical workstation. I Cu The unit is μA; S3. Concentration of copper ions in the solution to be tested C Cu Obtain it using the following formula: C Cu =( I Cu +2.69) / 151.55, unit is mg / L; In step S2, the anodic stripping voltammetry deposition time is 10 minutes, and the deposition potential relative to the reference electrode is -0.6 to -0.8 V; The zinc ion concentration in the zinc electrolyte is 40 g / L ~ 50 g / L, Cu 2+ The concentration is 0.1 mg / L to 1 mg / L.

2. The electrochemical detection method for copper ion impurities in zinc electrolyte according to claim 1, characterized in that, The silver nanowire working electrode can be reused at least 10 times.

3. The electrochemical detection method for copper ion impurities in zinc electrolyte according to claim 1, characterized in that... The measurement error of copper ions is less than 5%.

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