CN115078488A - Quantitative analysis method for organic additive in copper electrolytic refining - Google Patents

Abstract

The invention discloses a quantitative analysis method for organic additives in copper electrolytic refining. First, a series of standard solutions containing different concentrations of organic additives are prepared, and then the chronoamperometry is used to measure and repeat three times to obtain the absolute value of the corresponding current average value. , take the concentration of the organic additive as the abscissa and the absolute value of the current as the ordinate, draw the corresponding standard curve to obtain the corresponding linear regression equation; then measure the absolute value of the current for different electrolytes to be tested, according to the corresponding linear regression The equation calculates the content of the organic additives in the electrolyte to be tested; the present invention uses the chronoamperometry method, which can eliminate the interference of the hydrogen evolution reaction, the test steps are simple, the measurement time is short, and the content of the organic additives in the electrolyte can be accurately detected. Quantitative testing of organic additives in production provides a convenient means.

Description

A quantitative analysis method of organic additives in copper electrolytic refining

technical field

The invention relates to the technical field of copper electrolytic refining production, in particular to a quantitative analysis method for organic additives in copper electrolytic refining.

Background technique

In the production process of copper electrorefining, in order to ensure that the obtained cathode copper crystals are dense, flat and smooth, it is necessary to add a certain amount of organic additives to the electrolyte. At present, the organic additives commonly used in the domestic copper electrolytic refining industry are mainly bone glue and thiourea.

The electrorefining of copper is essentially the process of copper dissolution at the anode and subsequent reduction at the cathode. Numerous studies have shown that different additives affect the quality of the final cathode copper by affecting the copper cathode reduction process. Bone glue is often used as an inhibitor to help inhibit nodule. It will hydrolyze to generate positively charged bone glue ions, which are adsorbed on the surface of the cathode where the copper deposition rate is too fast, hindering the reduction and deposition of copper. Thiourea generally has a brightening effect. Studies have found that thiourea can form a cuprous complex with copper ions, so that copper ions cannot be directly reduced on the cathode, but are first resolved from the complex, and then can be reduced and precipitated on the cathode. This also acts to hinder the reduction and deposition of copper. In general, the addition of bone glue and thiourea can affect the reduction process of copper ions at the cathode, and play a crucial role in obtaining a dense, flat and smooth cathode copper surface.

However, due to factors such as process conditions or production requirements, it is necessary to adjust the amount of organic additives from time to time to keep the content of the additives within an appropriate range. If the adjustment is not timely, the quality of cathode copper may deteriorate rapidly and increase production. cost. In addition, because organic additives are unstable and prone to hydrolysis in acidic electrolytes, they cannot be quantitatively analyzed by conventional chemical methods. Engineers usually analyze and determine the amount of additives based on experience. This method has serious hysteresis and is difficult to analyze. The amount of additives added should be adjusted in time, and the symptoms of insufficient and excessive additives in the initial stage of electrolysis are relatively similar, and it is easy to make mistakes in judgment. Therefore, it is of great significance to develop a method that can quickly and effectively determine the concentration of organic additives.

At present, there have been some research results on the quantitative analysis methods of organic additives at home and abroad. Patent US4834842 discloses a method, which uses movable metal wires as cathodes and anodes, and measures the cathode overpotential by galvanostatic method, which can determine the concentration of animal glue or synthetic glue. In this method, copper deposition is carried out at a given current, and the concentration of animal glue or synthetic glue in the electrolyte is monitored by measuring the overpotential according to the correlation of "glue concentration-cathode overpotential". However, when this method performs copper deposition under a given current, due to the existence of hydrogen evolution reaction, it will cause fluctuations in overpotential and cause test errors. Patent CN112798674A uses cyclic voltammetry to first carry out copper deposition in the process of negative scanning, then carry out positive scanning, and integrate the oxidation peak area generated by the scanning to establish the corresponding relationship between "oxidation peak area-gelatin concentration", The gelatin concentration in the solution was monitored by measuring the oxidation peak area. However, this method cannot directly read the data of the oxidation peak, it needs to integrate the oxidation peak area, and the steps are cumbersome, and when calculating the integral area, it is greatly affected by the artificially set baseline, especially when the baseline is not equal to the peak area obtained There will be big errors. Therefore, it is of great significance to design a method that is simple to operate and can rapidly and accurately quantitatively analyze organic additives in copper electrorefining.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the present invention provides a quantitative analysis method for organic additives in copper electrolytic refining, so as to solve the problem that the dosage of additives in copper electrolytic production is difficult to control timely and accurately.

The technical scheme of the present invention is as follows:

A quantitative analysis method for organic additives in copper electrorefining, comprising the following steps:

S1, electrode pretreatment

A rotating disk platinum electrode is used as the working electrode, the platinum sheet electrode is used as the auxiliary electrode, and the saturated Ag/AgCl electrode is used as the reference electrode to form a three-electrode system. The three electrodes are placed in an electrolytic cell and connected to an electrochemical workstation; Sulfuric acid aqueous solution, use cyclic voltammetry to pretreat the electrode, record the obtained voltammetry curve until the curve and the characteristic curve basically coincide, at this time the electrode pretreatment is completed, rinse with deionized water for use;

The diameter of the rotating disk platinum electrode is 3 mm, and the area of the platinum sheet electrode is 1 cm×1 cm;

The concentration of the sulfuric acid aqueous solution is 0.5mol/L;

The parameters of the cyclic voltammetry are set as: potential window -0.17-1.4V, scanning speed 100mV/s, and cycle times 10 circles;

The characteristic curve is shown in FIG. 1, and the requirement that the voltammetry curve and the characteristic curve basically coincide is: a pair of hydrogen adsorption peaks and a pair of hydrogen desorption peaks appear on the curve at the same time;

S2, draw a standard curve

Use deionized water as the solvent to prepare the reference standard solution V, add the organic additives to the reference standard solution V, change the amount of the organic additives added, and configure the standard solutions V1, V2, V3, V4, V5 containing different concentrations of organic additives respectively, among which The concentrations of organic additives are respectively denoted as C ₁ , C ₂ , C ₃ , C ₄ , and C ₅ ;

Add the standard solution V1 into the electrolytic cell, insert the pretreated working electrode in S1, insert the auxiliary electrode and reference electrode in S1 to form a three-electrode system, connect the electrochemical workstation, set the rotating disk electrode rotation speed, and set the chronoamperometry. The experimental parameters are tested. During the test, the constant temperature is 25°C, repeated three times, the current value at the end of each test is recorded, and the absolute value of the current average value of the three measurements is taken, and is recorded as I ₁ ;

Replace the standard solutions V2, V3, V4, V5 respectively, and measure the corresponding absolute value of the current according to the steps of measuring I ₁ , denoted as I ₂ , I ₃ , I ₄ , I ₅ ; with the concentration of organic additives (C _n , n =1 to 5) as the abscissa, and the corresponding absolute value of the current (I _n , n=1 to 5) as the ordinate, and a standard curve is obtained by linear fitting;

The composition of the reference standard solution V is: copper sulfate pentahydrate 187g/L, sulfuric acid 170g/L;

The organic additive is bone glue or thiourea;

The concentration range of the organic additive is 4-12 ppm;

The rotating disk electrode rotating speed is 2000rpm;

The experimental parameters of the chronoamperometry are set as follows: the initial potential is the open circuit potential, the low potential is -0.15～-0.2V, the high potential is the open circuit potential, the initial step is negative, the number of steps is 1, and the pulse width is 30～60s;

Specifically preferred:

When the organic additive is bone glue, the concentrations C ₁ , C ₂ , C ₃ , C ₄ , and C ₅ of the organic additives in the standard solutions V1, V2, V3, V4, and V5 are respectively 4 ppm, 5 ppm, 6 ppm, 7 ppm, and 8 ppm, The remaining components are the same as those in the benchmark standard solution V, the linear regression equation of the fitted standard curve is y=-0.0027x+0.0364, and the linear correlation coefficient R=0.9984;

When the organic additive is thiourea, the concentrations C ₁ , C ₂ , C ₃ , C ₄ , and C ₅ of the organic additives in the standard solutions V1, V2, V3, V4, and V5 are respectively 4ppm, 6ppm, 8ppm, 10ppm, 12ppm , the remaining components are the same as those in the benchmark standard solution V, the linear regression equation of the fitted standard curve is y=-0.001x+0.0324, and the linear correlation coefficient R=0.9991;

S3. Sample detection

The electrolyte to be tested containing organic additives is added in the electrolytic cell, and the test is carried out according to the chronoamperometry in S2, the absolute value I of the corresponding current average value is obtained and _measured , and the corresponding organic additive concentration C is obtained by calculating according to the standard curve in S2. _test .

Beneficial effects of the present invention:

Chronoamperometry can effectively eliminate the interference of the hydrogen evolution reaction in the cathode process in the aqueous system, and accurately measure the concentration of organic additives in the electrolyte; the current value can be directly read from the test results, no complicated data processing is required, and the test steps are simple; The measurement time is short, and the test step does not exceed 60 seconds, which can accurately detect the content of organic additives in the electrolyte. The invention provides a convenient means for quantitative testing of organic additives in copper electrolytic refining production.

Description of drawings

Figure 1 is the characteristic curve of electrode pretreatment.

Figure 2 is the chronoamperometry curve of bone glue.

Figure 3 is a standard curve of the absolute value of the current of the glue and its concentration.

Figure 4 is a chronoamperometry curve of thiourea.

Figure 5 is a standard curve of the absolute value of the current of thiourea and its concentration.

Detailed ways

For better understanding of the present invention, the present invention will be further described below through specific embodiments, but the protection scope of the present invention is not limited to this.

Example 1

(1) Electrode pretreatment

A rotating disc platinum electrode with a diameter of 3 mm was used as the working electrode, the platinum sheet electrode with an area of 1 cm × 1 cm was used as the auxiliary electrode, and the saturated Ag/AgCl electrode was used as the reference electrode to form a three-electrode system. ChemStation. Add 0.5mol/L sulfuric acid aqueous solution to the electrolytic cell, and preprocess the electrode by cyclic voltammetry. A pair of hydrogen adsorption peaks and a pair of hydrogen desorption peaks appear on the test curve and characteristic curve at the same time. After the pretreatment, rinse the working electrode with deionized water for use.

(2) Draw the standard curve

Deionized water was used as the solvent to prepare the standard standard solution V, and the specific composition was: copper sulfate pentahydrate 187g/L, sulfuric acid 170g/L. The organic additive bone glue was added to the reference standard solution V, and standard solutions V1, V2, V3, V4, and V5 containing different concentrations of bone glue were respectively configured, wherein the concentration of the bone glue was 4ppm, 5ppm, 6ppm, 7ppm, 8ppm, respectively, denoted as C ₁ , C ₂ , C ₃ , C ₄ , C ₅ .

Add the standard solution V1 into the electrolytic cell, insert the pretreated working electrode, insert the 1cm×1cm platinum sheet electrode as the auxiliary electrode, insert the saturated Ag/AgCl electrode as the reference electrode to form a three-electrode system, and connect to Chenhua CHI660C electrochemical workstation , set the rotating disk electrode speed to 2000rpm, set the chronoamperometry experimental parameters to test, the parameters are set as: the initial potential is open circuit potential, the low potential is -0.2V, the high potential is open circuit potential, the initial step is negative, the number of steps is 1, The pulse width is 60s. During the test, the temperature was kept at 25°C, repeated three times, the current value at the end of each test was recorded, and the absolute value of the average value of the current measured three times was taken and recorded as I ₁ .

Replace the standard solutions V2, V3, V4, and V5 respectively, and measure the corresponding absolute values of the currents according to the steps of measuring _I1 , which are recorded as _I2 , _I3 , _I4 , and _I5 ; with the concentration of bone glue (C _n , n= 1 to 5) as the abscissa, and the corresponding absolute value of the current (I _n , n=1 to 5) as the ordinate, the standard curve is obtained by linear fitting; the linear regression equation of the fitted standard curve is y=-0.0027 x+0.0364, the linear correlation coefficient R=0.9984.

(3) Sample detection

Take two reference standard solutions V, add 5.5 ppm and 7.5 ppm bone glue to them respectively, and configure them as the solution to be tested, denoted as N1 and N2. Measure the absolute values of currents corresponding to N1 and N2 according to the steps of measuring I ₁ , and denote them as I _N1 and I _N2 . According to the linear regression equation y=-0.0027x+0.0364 of the standard curve, the concentration of bone glue in the solution to be _tested is calculated. The concentration of bone glue obtained in N1 is 5.58ppm, and the relative error is 1.4%; the concentration of bone glue obtained in N2 is _{measured as 2} . 7.32ppm, relative error 2.4%.

(2) Example 2

The difference between this example and Example 1 is that the organic additive is thiourea, and the concentrations of thiourea in the standard solutions V1, V2, V3, V4, and V5 are respectively 4ppm, 6ppm, 8ppm, 10ppm, and 12ppm. The concentrations of thiourea in the solutions N1 and N2 to be tested were 5 ppm and 9 ppm, respectively. The rest of the steps are the same as in Example 1. The linear regression equation of the fitted standard curve is y=-0.001x+0.0324, and the linear correlation coefficient R=0.9991. Calculate the thiourea concentration in the solution to be tested according to the linear regression equation y=-0.001x+0.0324 of the standard curve, the thiourea concentration C obtained from the _test in N1 is 4.9ppm, and the relative error is 2.0%; the thiourea concentration C obtained from the test in N2 _{Test 2} was 8.73ppm, with a relative error of 3.0%.

(3) Embodiment 3

The difference between this example and Example 1 is that the experimental parameters of the chronoamperometry are set as: the initial potential is the open circuit potential, the low potential is -0.15V, the high potential is the open circuit potential, the initial step is negative, the number of steps is 1, the pulse width 30s. The rest of the steps are the same as in Example 1. The linear regression equation of the fitted standard curve is y=-0.0026x+0.0286, and the linear correlation coefficient R=0.9993. According to the linear regression equation y=-0.0026x+ _0.0286 of the standard curve, the concentration of bone glue in the solution to be tested is calculated. The concentration of bone glue obtained in N1 is 5.37 ppm, and the relative error is 2.3%; the concentration of bone glue obtained in N2 is _{measured 2} : 7.41ppm, relative error 1.2%.

(4) Embodiment 4

The difference between this example and Example 1 is that the organic additive is thiourea, and the concentrations of standard solutions V1, V2, V3, V4, and thiourea are respectively 4ppm, 6ppm, 8ppm, and 10ppm; the chronoamperometry experimental parameter settings are: the initial potential is the open circuit potential, the low potential is -0.15V, the high potential is the open circuit potential, the initial step is negative, the number of steps is 1, and the pulse width is 30s; the concentrations of thiourea in the solutions N1 and N2 to be tested in the sample detection are 5ppm and 5ppm respectively. 9ppm. The rest of the steps are the same as in Example 1. The linear regression equation of the fitted standard curve is y=-0.001x+0.0222, and the linear correlation coefficient R=0.9990. Calculate the thiourea concentration in the solution to be tested according to the linear regression equation y=-0.001x+0.0222 of the standard curve, the thiourea concentration C obtained by the _test in N1 is 5.04ppm, and the relative error is 0.8%; the thiourea concentration C obtained by the test in N2 _{Test 2} was 9.1pm, with a relative error of 1.1%.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent changes and modifications made to the above-mentioned embodiments according to the technical essence of the present invention shall be included in the scope of the present invention. scope of protection, etc.

Claims (10)

1. A quantitative analysis method for organic additives in copper electrolytic refining is characterized by comprising the following steps:

s1 pretreatment of electrode

A rotating disc platinum electrode is used as a working electrode, a platinum sheet electrode is used as an auxiliary electrode, a saturated Ag/AgCl electrode is used as a reference electrode to form a three-electrode system, and the three electrodes are placed in an electrolytic tank and connected with an electrochemical workstation; adding a sulfuric acid aqueous solution into an electrolytic cell, pretreating an electrode by adopting a cyclic voltammetry method, recording an obtained voltammetry curve until the curve is basically overlapped with a characteristic curve, finishing electrode pretreatment, and washing the electrode by using deionized water for later use;

s2, drawing a standard curve

Preparing a standard solution V by taking deionized water as a solvent, adding an organic additive into the standard solution V, changing the amount of the added organic additive, and respectively preparing standard solutions V1, V2, V3, V4 and V5 containing organic additives with different concentrations, wherein the concentrations of the organic additives are respectively marked as C ₁ 、C ₂ 、C ₃ 、C ₄ 、C ₅ ；

Adding a standard solution V1 into an electrolytic cell, inserting the working electrode pretreated in S1, forming a three-electrode system by an auxiliary electrode and a reference electrode inserted in S1, connecting an electrochemical workstation, setting the rotating speed of a rotating disk electrode, setting experimental parameters of a timing current method for testing, keeping the temperature at 25 ℃ in the testing process, repeating the testing process three times, recording the current value at the end of each test, taking the absolute value of the average value of the current measured three times, and marking the absolute value as I ₁ ；

The standard solutions V2, V3, V4 and V5 were replaced respectively according to measurement I ₁ Respectively measuring corresponding current absolute values, which are marked as I ₂ 、I ₃ 、I ₄ 、I ₅ (ii) a Taking the concentration of the organic additive as an abscissa and the corresponding absolute value of the current as an ordinate, and obtaining a standard curve through linear fitting;

s3, detecting the sample

Adding electrolyte to be tested containing organic additive into electrolytic cell, testing according to the chronoamperometry method in S2 to obtain absolute value I of corresponding current average value _Measuring And calculating according to a standard curve in S2 to obtain the corresponding organic additive concentration C _Measuring 。

2. The method of quantitative analysis of organic additives in copper electrorefining according to claim 1, wherein the diameter of the rotating disk platinum electrode in S1 is 3mm, and the area of the platinum sheet electrode is 1cm x 1 cm.

3. The method for quantitative analysis of organic additives in copper electrorefining according to claim 1, wherein the concentration of the sulfuric acid aqueous solution in S1 is 0.5 mol/L.

4. A method for quantitative analysis of organic additives in copper electrorefining as claimed in claim 1, wherein the parameters of cyclic voltammetry in S1 are set as: the potential window is-0.17-1.4V, the scanning speed is 100mV/s, and the cycle times are 10 circles.

5. The method for quantitatively analyzing an organic additive in electrolytic refining of copper according to claim 1, wherein the requirement that the voltammogram curve substantially coincides with the characteristic curve in S1 is: a pair of hydrogen adsorption peaks and a pair of hydrogen desorption peaks simultaneously appear on the curve.

6. The method for quantitatively analyzing an organic additive in copper electrorefining as set forth in claim 1, wherein the composition of said reference standard solution V in S2 is: 187g/L of blue vitriol and 170g/L of sulfuric acid.

7. The method for quantitatively analyzing an organic additive in copper electrorefining as claimed in claim 1, wherein the organic additive in S2 is bone glue or thiourea, and the concentration of the organic additive is in the range of 4 to 12 ppm.

8. The method for quantitative analysis of organic additives in copper electrorefining according to claim 1, wherein the rotation speed of the rotating disk electrode in S2 is 2000 rpm.

9. The method for quantitative analysis of organic additives in copper electrorefining according to claim 1, wherein said chronoamperometric experimental parameters in S2 are set as: the initial potential is open-circuit potential, the low potential is-0.15 to-0.2V, the high potential is open-circuit potential, the initial step is negative, the number of steps is 1, and the pulse width is 30 to 60 s.

10. The method for quantitatively analyzing an organic additive in electrolytic refining of copper according to claim 1, wherein when the organic additive in S2 is bone glue, the concentration C of the organic additive in the standard solutions V1, V2, V3, V4 and V5 is C ₁ 、C ₂ 、C ₃ 、C ₄ 、C ₅ 4ppm, 5ppm, 6ppm, 7ppm and 8ppm respectively, the linear regression equation of the fitted standard curve is that y is-0.0027 x +0.0364, and the linear correlation coefficient R is 0.9984;

when the organic additive is thiourea, the standard solutions V1, V2, V3,Concentration C of organic additives in V4, V5 ₁ 、C ₂ 、C ₃ 、C ₄ 、C ₅ 4ppm, 6ppm, 8ppm, 10ppm, 12ppm respectively, the linear regression equation of the fitted standard curve is-0.001 x +0.0324, and the linear correlation coefficient R is 0.9991.

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