Method for analyzing and detecting thiourea in copper electrolyte

Abstract

The invention discloses a method for analyzing and detecting thiourea in a copper electrolyte, relates to the technical field of copper smelting, and particularly relates to a method for drawing a relation curve of TMB absorbance and thiourea concentration according to the principle that thiourea concentration is in direct proportion to TMB absorbance change. Pb3O4 nanoparticles or PbO2 is adopted as an oxidizing agent, the absorbance of oxidized TMB in a system is measured by using an ultraviolet and visible spectrophotometer, and the concentration of thiourea under the absorbance of TMB can be obtained according to a relation curve, so that the concentration of thiourea in the copper electrolyte is analyzed and detected. The method for analyzing and detecting the thiourea in the copper electrolyte is easy to operate, adopts simple experimental equipment, is suitable for conventional laboratories or production analysis, can avoid interference and guarantee the detection precision, reduces the detection difficulty through the principle that the concentration of the thiourea is in direct proportion to the absorbance change of the TMB, is easy to implement, and can select a proper catalyst according to requirements.

Description

Technical Field

[0001] The invention relates to the technical field of copper smelting, and in particular to an analysis and detection method for thiourea in a copper electrolyte. Background Art

[0002] Thiourea is a compound containing nitrogen and sulfur. As a simple and important sulfur-containing material, thiourea has been widely used in several scientific and technological fields such as agriculture, analytical chemistry and industry. In the field of analytical chemistry, it is an important spectrophotometric reagent for the determination of metals. Due to its high binding affinity to metal ions, the use of thiourea is closely related to metal leaching, electroplating and electrorefining. In particular, in the process of copper electrorefining, thiourea can react with Cu 2+ The reaction generates formamidine disulfide and Cu + Thiourea reacts with CuSO4 to form CuSO4-H2SO4-thiourea complex. + Formation of complex, Cu + It can also form a complex with formamidine disulfide. Thiourea and its various complexes can be adsorbed on the surface of the copper electrode, affecting the nucleation process of copper deposition. Therefore, it is necessary to accurately detect the concentration of thiourea in the copper electrolyte.

[0003] In the related art, the methods for detecting thiourea concentration in copper electrolyte usually include:

[0004] 1. Fluid dynamic impedance method: Using a rotating disk electrode as the working electrode, the electrochemical impedance is tested at 0V (vs SCE) to obtain the charge transfer resistance of the copper ion reduction reaction. By establishing the corresponding relationship between the charge transfer resistance and the thiourea concentration, a standard curve is obtained to quickly determine the thiourea concentration. However, this method requires specific electrodes and test equipment, and may be interfered by other electrolytes and impurities.

[0005] 2. Ultraviolet spectrophotometry: First, use LD-150 polished mixed bed resin to adsorb the copper electrolyte, and then use ultraviolet spectrophotometry to measure the adsorbed liquid; this method needs to handle a large amount of adsorbent and solvent when used, and may introduce errors in the adsorption process;

[0006] 3. Iodine spectrophotometry: The thiourea content is determined by spectrophotometry using the complex formed by thiourea and copper that has characteristic absorption of ultraviolet light. This method requires complex sample processing;

[0007] 4. Ethyl acetate extraction spectrophotometry: Thiourea reacts with iodine to form iodinated thiourea, which is then extracted with ethyl acetate and the thiourea content is determined by spectrophotometry. This method uses toxic toluene reagents, which is harmful to the health of analysts.

[0008] 5. Linear potential scanning method: The adsorption behavior of thiourea on the copper cathode surface is studied by linear potential scanning, and the effect of adsorption on the cathode copper crystal structure is tested by X-ray diffraction method; this method requires complex experimental equipment and operation when used.

[0009] In summary, the existing method for detecting thiourea concentration in copper electrolyte has the disadvantages of impurity interference, complex operation, high requirements for experimental equipment, and impact on the health of analysts. Based on this, the present application proposes a method for analyzing and detecting thiourea in copper electrolyte. Summary of the invention

[0010] The present invention provides a method for analyzing and detecting thiourea in a copper electrolyte, which solves the problems of the existing method for detecting the thiourea concentration of the copper electrolyte proposed in the above background technology, such as impurity interference, complex operation, high requirements for experimental equipment, and impact on the health of analysts.

[0011] The present invention provides the following technical scheme: a method for analyzing and detecting thiourea in a copper electrolyte: based on the principle that the concentration of thiourea is proportional to the absorbance change of TMB, a relationship curve between the concentration of TMB and the concentration of thiourea is drawn, and then Pb3O4 or PbO2 nanoparticles are used for oxidation, and the absorbance of TMB is measured by an ultraviolet-visible spectrophotometer. The concentration of thiourea under the absorbance of TMB can be obtained according to the relationship curve, thereby realizing the analysis and detection of the concentration of thiourea in the copper electrolyte;

[0012] The specific operation of the above analysis and detection method is as follows:

[0013] Step 1: Pre-treat all glassware used in the experiment and wash them thoroughly with ultrapure water before use;

[0014] Step 2: prepare the required oxidant, which is Pb3O4 or PbO2 nanoparticles;

[0015] Wherein: the synthesis steps of Pb3O4 nanoparticles are: about 10g of lead acetate solid is completely dissolved in 100mL of ultrapure water, and 0.5g of sodium hydroxide solid particles are added to the solution; after stirring for 10min, sodium hypochlorite solution and sodium hydroxide solid are added to adjust the pH value of the obtained solution to 14, magnetic stirring is performed at a temperature of 90°C for 6h to obtain brown precipitate β-PbO2, the brown precipitate is washed with ultrapure water and filtered, and then transferred to a crucible, and pyrolysis treatment is performed at a temperature of 420°C in a muffle furnace for 6h to finally obtain orange-red Pb3O4 nanoparticles, and 1mg of Pb3O4 nanoparticles are weighed and dispersed in 10mL of ultrapure water after grinding to obtain a suspension of Pb3O4 nanoparticles;

[0016] Step 3: Study the effect of the detection system environment on the catalytic activity of the oxidant and determine the concentration of the oxidant. The detection system environment includes but is not limited to the pH value, temperature, reaction time and concentration of the oxidant;

[0017] Wherein: at room temperature, the concentration of Pb3O4 nanoparticles is 10ug / mL; PbO2 and Pb3O4 nanoparticles have the same function and can replace each other;

[0018] Step 4: prepare the experimental sample, add the thiourea solution of known concentration into the prepared sample to obtain the test solution, test it with a UV-visible spectrophotometer and record the spectral data, and draw the thiourea detection working curve according to the spectral data;

[0019] Wherein: the preparation method of experimental sample 1 required for drawing the working curve of Pb3O4 nanoparticle thiourea detection and the working curve of PbO2 thiourea detection is: 200uL TMB solution, deionized water, 100uL sulfuric acid solution, 200uL 10ug / mL Pb3O4 nanoparticle suspension or PbO2 suspension, and different amounts of 0.1mg / mL thiourea solution are added to a 5mL centrifuge tube in sequence, and the prepared experimental sample capacity is 2mL, and the test solution prepared using the experimental sample needs to be placed at room temperature for 10 minutes before testing; the preparation method of experimental sample 2 is: several uL of HAc / NaAc buffer, 40uL TMB solution, 20uL catalyst solution, and 20-200uL thiourea standard solution are added to a 5mL centrifuge tube in sequence, and the prepared experimental sample capacity is 2mL, and the test solution prepared using the experimental sample needs to be reacted in a 37°C constant temperature water bath for 5 minutes before testing;

[0020] Step 5, prepare a test sample, add an oxidant and the like to the test sample to obtain a test solution, place the test solution at room temperature for 10 minutes or react in a 37° C. constant temperature water bath for 5 minutes, test it using a UV-visible spectrophotometer and record spectral data, calculate the thiourea concentration under the corresponding spectral data using the working curve in step 4, and then realize the analysis and detection of the thiourea concentration in the copper electrolyte sample;

[0021] When Pb3O4 nanoparticles or PbO2 particles are used as oxidants, the first method for preparing the test sample is as follows: dilute the copper electrolyte to be tested 10 times to obtain an unknown thiourea sample, and add 20uLTMB solution, deionized water, 100uL of sulfuric acid solution, 200uL of 100ug / mL Pb3O4 nanoparticle suspension or PbO2 suspension, and an equal amount of unknown thiourea sample to a 5mL centrifuge tube in sequence, and the prepared experimental sample capacity is 2mL; the second method for preparing the test sample is as follows: dilute the copper electrolyte to be tested 4 times to obtain an unknown thiourea sample, and add HAc / NaAc buffer solution, unknown thiourea sample, TMB solution, and oxidant solution to a 5mL centrifuge tube in sequence, and the prepared test sample capacity is 2mL.

[0022] Preferably, the glassware pretreatment method is: all glassware used in the experiment are soaked in aqua regia for 30 minutes.

[0023] Preferably, during the synthesis process of the Pb3O4 nanoparticles, the brown precipitate needs to be washed with ultrapure water and filtered three times; and the obtained orange-red solid particles need to be tested to confirm that the prepared nanomaterial is Pb3O4 nanoparticles; the prepared Pb3O4 nanoparticles have a size of about 100 nm, but a relatively irregular shape.

[0024] Preferably, the Pb3O4 nanoparticle suspension needs to be ultrasonically treated before each use to make it evenly dispersed.

[0025] Preferably, the method for detecting the orange-red solid particles is: performing XRD analysis on both the synthesized orange-red solid particles and the analytically pure AR-polar Pb3O4, and comparing the obtained XRD patterns. Figure 1 If the results are consistent, it means that the nanomaterials prepared in the experiment are Pb3O4 nanoparticles.

[0026] Preferably, in step 4, the known thiourea concentrations in the experimental sample 1 are 0 mg / L, 1 mg / L, 2.5 mg / L, 5 mg / L and 10 mg / L respectively; the 200 uL TMB solution is dissolved in 5 mM ethanol solution;

[0027] The known thiourea concentrations in experimental sample 2 were 10ug / mL, 20ug / mL, 40ug / mL, 70ug / mL, and 100ug / mL;

[0028] The preparation method of TMB solution is as follows: accurately weigh 30 mg of TMB, dissolve it in anhydrous ethanol solution and dilute it to 5 mL;

[0029] The preparation method of thiourea standard solution is as follows: accurately weigh 10 mg of thiourea, add 10 mL of buffer solution and dissolve completely.

[0030] Preferably, a comparative experiment is used to verify that the strong oxidizing property of Pb3O4 comes from PbO2. According to the comparative experiment, it is concluded that PbO2 and Pb3O4 can be relatively replaced. The reagents used in the comparative experiment are 10mM TMB solution, water, Pb3O4 solution and PbO2 solution. The capacity of the reagents configured in the comparative experiment is 2mL.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The analytical detection method for thiourea in copper electrolyte draws a relationship curve between TMB concentration and thiourea concentration based on the principle that the thiourea concentration is proportional to the absorbance change of TMB, then uses Pb3O4 and PbO2 nanoparticles to oxidize TMB in the test sample, and uses a UV-visible spectrophotometer to measure the TMB absorbance. The thiourea concentration under the TMB absorbance can be obtained according to the relationship curve, thereby realizing the analytical detection of the thiourea concentration in the copper electrolyte.

[0033] 2. The analytical detection method of thiourea in the copper electrolyte is simple to operate and uses simple experimental equipment. It is suitable for conventional laboratories or production analysis, and can avoid interference and ensure detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The UV-visible spectra of different systems of the present invention when the reaction time is 10 min;

[0035] Figure 2 Schematic diagram of the effect of pH value on the catalytic ability of Pb3O4 nanoparticles;

[0036] Figure 3 Schematic diagram of the effect of temperature on the catalytic ability of Pb3O4 nanoparticles;

[0037] Figure 4 This is a schematic diagram of the change of system absorbance with temperature after adding 5 mg / L thiourea;

[0038] Figure 5 Schematic diagram of the effect of temperature on the sensitivity of the yellow system;

[0039] Figure 6 Schematic diagram of the change of absorbance over time in the presence of Pb3O4 nanoparticles;

[0040] Figure 7 Schematic diagram of the effect of Pb3O4 nanoparticle concentration;

[0041] Figure 8 Schematic diagram of comparative experimental verification results;

[0042] Fig. 9This is the relationship between the absorbance decrease ΔA at 450nm and the TU concentration when Pb3O4 nanoparticles or PbO2 are used as catalysts. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] The present invention provides an analytical detection method for thiourea in a copper electrolyte. According to the principle that the concentration of thiourea is proportional to the absorbance change of TMB, a relationship curve between the concentration of TMB and the concentration of thiourea is drawn, and then Pb3O4 nanoparticles and PbO2 are used to oxidize TMB in a detection sample, and the absorbance of TMB is measured by an ultraviolet visible spectrophotometer. The thiourea concentration under the absorbance of TMB can be obtained according to the relationship curve, thereby realizing the analytical detection of the thiourea concentration in the copper electrolyte.

[0045] The specific operation of the above analysis and detection method is as follows:

[0046] Step 1: Pre-treat all glassware used in the experiment. The glassware pre-treatment method is: soak all glassware used in the experiment in aqua regia (V HNO3 / V HCL =1:3) for 30 min and rinse thoroughly with ultrapure water before use;

[0047] Step 2: prepare the required oxidant, which is Pb3O4 nanoparticles and PbO2 nanoparticles;

[0048] Wherein: the synthesis steps of Pb3O4 nanoparticles are: about 10g of lead acetate solid is completely dissolved in 100mL of ultrapure water, and 0.5g of sodium hydroxide solid particles are added to the solution; after stirring for 10min, sodium hypochlorite solution and sodium hydroxide solid are added to adjust the pH value of the obtained solution to 14, magnetic stirring is carried out at a temperature of 90°C for 6h, and brown precipitate β-PbO2 is obtained, the brown precipitate is washed with ultrapure water and filtered (3 times), and then transferred to a crucible, and pyrolysis treatment is carried out at a temperature of 420°C in a muffle furnace for 6h, and finally orange-red Pb3O4 nanoparticles are obtained. In addition, it can be seen from the scanning electron microscope (SEM) image that the size of the prepared Pb3O4 nanoparticles is about 100nm, but the shape is relatively irregular. After grinding, 1mg of Pb3O4 nanoparticles is weighed and dispersed in 10mL of ultrapure water to obtain a suspension of Pb3O4 nanoparticles. The suspension of Pb3O4 nanoparticles needs to be ultrasonically treated before each use to make it evenly dispersed.

[0049] During the synthesis of Pb3O4 nanoparticles, the orange-red solid particles need to be tested to confirm that the prepared nanomaterials are Pb3O4 nanoparticles. The method for testing the orange-red solid particles is as follows: XRD analysis is performed on the synthesized orange-red solid particles and analytical pure AR Pb3O4, and the obtained XRD patterns are compared. If the two XRD patterns are Figure 1 If the results are consistent, it means that the nanomaterials prepared in the experiment are Pb3O4 nanoparticles.

[0050] Step 3: Study the effect of the detection system environment on the catalytic activity of the oxidant and determine the concentration of the oxidant. The detection system environment includes but is not limited to the pH value, temperature, reaction time and concentration of the oxidant;

[0051] The catalytic activity of Pb3O4 nanoparticles was studied using a colorimetric system: 3,3′,5,5′-tetramethylbenzidine (TMB) was selected as a chromogenic substrate to study the enzyme-like activity of Pb3O4 nanoparticles, such as Figure 1 As shown in the figure (reaction conditions: pH 3.0 acetate buffer, room temperature, reaction time 10 min), Pb3O4 nanoparticles can catalyze the oxidation of TMB to generate a blue solution and induce significant absorbance changes in the presence of hydrogen peroxide. At the same time, Pb3O4 nanoparticles can also catalyze the oxidation of TMB in the absence of hydrogen peroxide, and the effect is better than that in the presence of hydrogen peroxide. Therefore, hydrogen peroxide is not required in this research system. The research systems are divided into TMB+H2O2, TMB+H2O2+Pb3O4, and TMB+Pb3O4.

[0052] Taking the colorimetric system as an example, the effect of pH value on the catalytic ability of Pb3O4 nanoparticles was studied. Figure 2As shown, Pb3O4 nanoparticles have good catalytic activity in the pH range of 2-5, and the absorbance of the system is the highest at pH 3. Therefore, the pH value of 3 is the best in the blue color development system.

[0053] Taking the yellow system as an example, Figure 3 It can be seen that the catalytic activity of Pb3O4 nanoparticles is best at 20℃, but overall, its catalytic activity does not change much in the range of 5-30℃, and the absorbance changes with temperature after adding 5mg / L thiourea in the system. Figure 4 and Figure 5 As shown in the figure, it can be seen that in the range of 5-30℃, the absorbance change (ΔA) is basically consistent. Therefore, in order to facilitate the experiment, the experiment was carried out at room temperature. Figure 6 It can be seen that the absorbance rises rapidly within 0-5 minutes, the curve begins to become smooth within 5-10 minutes, and the absorbance begins to rise slowly after 10 minutes. Therefore, it is more appropriate to choose 5-10 minutes as the reaction time. This application chooses 10 minutes as the reaction time. Figure 6 The assay conditions were: 0.1 mM TMB, 10 ug / mL catalyst, and room temperature. Figures 2 to 5 The assay conditions are: blue system: 0.5 mM TMB, 5 mM hydrogen peroxide, 10 ug / mL catalyst, 5 min; yellow system: 0.1 mM TMB, 10 ug / mL catalyst at pH 1-2, 10 min.

[0054] like Figure 7 As shown, in the blue colorimetric system, the effect of the concentration of Pb3O4 nanoparticles was studied, and it was found that after the concentration of Pb3O4 nanoparticles was 10ug / mL, the change in absorbance was negligible. Therefore, the present invention selected 10ug / mL as the optimal reaction concentration of the oxidant. Detection conditions: 0.5mM TMB, 5mM hydrogen peroxide, pH 3, and reaction time of 10min.

[0055] Considering the color of the copper refinery electrolyte itself (yellow-green) and the influence of the strong acidic environment, the copper electrolyte solution was analyzed using pH and found that its pH value was very low. Therefore, this application selected the yellow colorimetric system for the determination of thiourea.

[0056] According to the results of the above optimization conditions, it is concluded that the concentration of Pb3O4 nanoparticles is 10ug / mL at room temperature.

[0057] Since Pb3O4 can be written as 2PbO·PbO2, it is inferred that the strong oxidizing property of Pb3O4 comes from PbO2. A comparative experiment is now used to verify that the strong oxidizing property of Pb3O4 comes from PbO2. Based on the comparative experiment, it is concluded that PbO2 and Pb3O4 can be relatively replaced. The reagents used in the comparative experiment are shown in Table 1:

[0058]

[0059] The results are as follows Figure 8 As shown, from Figure 8 It can be seen that the strong oxidizing property of Pb3O4 comes from PbO2, so PbO2 and Pb3O4 nanoparticles have the same function and can replace each other.

[0060] Step 4: prepare the experimental sample, add the thiourea solution of known concentration into the prepared sample to obtain the test solution, test it with a UV-visible spectrophotometer and record the spectral data, and draw the thiourea detection working curve according to the spectral data;

[0061] Wherein: the preparation method of experimental sample 1 required for drawing the working curve of Pb3O4 nanoparticle thiourea detection and the working curve of PbO2 thiourea detection is: add 100uL of sulfuric acid solution (0.2mol / L, ph1-2), 200uLTMB solution (5mM, ethanol solution), 200uL of 100ug / mL Pb3O4 nanoparticle suspension or PbO2 suspension, different amounts of 0.1mg / mL thiourea solution and deionized water into a 5mL centrifuge tube in sequence, the prepared experimental sample capacity is 2mL, the known thiourea concentrations in experimental sample 1 are 0mg / L, 1mg / L, 2.5mg / L, 5mg / L and 10mg / L respectively, and the test solution prepared using the experimental sample needs to be placed at room temperature for 10 minutes before testing; the test results are as follows Fig. 9 As shown, the results show that 10ug / mL of Pb3O4 nanoparticle suspension can detect thiourea within 10mg / L, and the absorbance at 450nm is proportional to the thiourea concentration in the range of 1-10mg / L. The linear regression equation is: ΔA = 0.0779c-0.08807 (R 2 =0.99), where ΔA is the absorbance change at 450 nm and c is the concentration of thiourea.

[0062] The preparation method of the experimental sample 2 required for drawing the working curve of the blue thiourea detection system is as follows: add a certain amount of HAc / NaAc buffer, 40uL of TMB solution, 20uL of oxidant solution, and 20-200uL of thiourea standard solution to a 5mL centrifuge tube in sequence, and the prepared experimental sample is 2mL. The known thiourea concentrations in the experimental sample 2 are 10ug / mL, 20ug / mL, 40ug / mL, 70ug / mL and 100ug / mL respectively; the preparation method of the HAc / NaAc buffer solution is as follows: take 10mL of HAc solution and 2.5g of NaAc powder, dissolve and dilute to 1L with ultrapure water, measure the pH of the resulting solution with pH test paper, and fine-tune with sodium hydroxide and acetic acid solution until the solution pH = 4; the preparation method of the TMB solution is as follows: accurately weigh 30mg TMB was dissolved in anhydrous ethanol solution and diluted to 5 mL; the catalyst solution was prepared by accurately weighing 1 mg of nanocatalyst, adding 1 mL of buffer solution, and shaking to disperse evenly; the thiourea standard solution was prepared by accurately weighing 10 mg of thiourea, adding 10 mL of buffer solution, and dissolving completely. The test solution prepared using the experimental sample needs to react in a 37°C constant temperature water bath for 5 minutes, and then tested with absorbance at 652 nm as the ordinate and thiourea concentration as the abscissa to establish a thiourea detection working curve, and the linear regression equation is: y = -0.0211x + 2.8.

[0063] In some embodiments of the present application, the experimental sample reaction system constructed by the above method is shown in the following table:

[0064]

[0065]

[0066] Step 5, prepare a test sample, add an oxidant to the test sample to obtain a test solution, place the test solution at room temperature for 10 minutes or react in a 37°C constant temperature water bath for 5 minutes, test it using a UV-visible spectrophotometer and record spectral data, calculate the thiourea concentration under the corresponding spectral data using the working curve in step 4, and then realize the analysis and detection of the thiourea concentration in the copper electrolyte sample;

[0067] When Pb3O4 nanoparticles or PbO2 particles are used as oxidants, the preparation method of the test sample is as follows: the copper electrolyte to be tested is subjected to resin adsorption treatment and diluted 10 times to obtain an unknown thiourea sample, and 20uLTMB solution (10mM, ethanol solution), deionized water, 100uL of sulfuric acid solution (about 1.84M, concentrated sulfuric acid diluted 10 times), 200uL of 10ug / mL Pb3O4 nanoparticle suspension or PbO2 suspension, and an equal amount of unknown thiourea sample are added to a 5mL centrifuge tube in sequence, and the prepared experimental sample capacity is 2mL;

[0068] In summary: the analytical detection method for thiourea in copper electrolyte is simple to operate and uses simple experimental equipment, is suitable for conventional laboratories or production analysis, can avoid interference, and ensure detection accuracy. The principle that the thiourea concentration is proportional to the absorbance change of TMB reduces the detection difficulty, is easy to implement, and a suitable catalyst can be selected according to needs.

Claims

1. A method for analyzing and detecting thiourea in a copper electrolyte, characterized in that: Based on the principle that the concentration of thiourea is proportional to the absorbance change of TMB, a curve of the relationship between the absorbance of TMB and the concentration of thiourea is drawn. Pb3O4 nanoparticles or PbO2 are used to oxidize TMB in the detection system, and the absorbance of oxidized TMB is measured by a UV-visible spectrophotometer. The concentration of thiourea under the absorbance of TMB can be obtained according to the relationship curve, thereby realizing the analysis and detection of the concentration of thiourea in the copper electrolyte; The specific operation of the above analysis and detection method is as follows: Step 1: Pre-treat all glassware used in the experiment and wash them thoroughly with ultrapure water before use; Step 2: prepare the required oxidant, which is Pb3O4 or PbO2 nanoparticles; Wherein: the synthesis steps of nano Pb3O4 are: completely dissolving 10g of lead acetate solid in 100mL of ultrapure water, and adding 0.5g of sodium hydroxide solid particles to the solution; after stirring for 10min, adding sodium hypochlorite solution and sodium hydroxide solid, so that the pH value of the obtained solution is adjusted to 14, magnetically stirring at a temperature of 90°C for 6h, obtaining brown precipitate β-PbO2, washing the brown precipitate with ultrapure water and filtering, and then transferring it to a crucible, performing a pyrolysis treatment at a temperature of 420°C in a muffle furnace for 6h, and finally obtaining orange-red Pb3O4 nanoparticles, grinding and weighing 1mg of Pb3O4 nanoparticles and dispersing them in 10mL of ultrapure water to obtain a suspension of Pb3O4 nanoparticles; Step 3: Study the effect of the detection system environment on the catalytic activity of the oxidant and determine the concentration of the oxidant. The detection system environment includes but is not limited to the pH value, temperature, reaction time and concentration of the oxidant; Wherein: at room temperature, the concentration of Pb3O4 nanoparticles is 10ug / mL; PbO2 and Pb3O4 nanoparticles have the same function and can replace each other; Step 4: prepare the experimental sample, use the thiourea solution with known concentration as the test solution, test it with a UV-visible spectrophotometer and record the spectral data, and draw the thiourea detection working curve according to the spectral data; Wherein: the preparation method of experimental sample 1 required for drawing the working curve of Pb3O4 nanoparticle thiourea detection and the working curve of PbO2 thiourea detection is: 200uLTMB solution, deionized water, 100uL sulfuric acid solution, 200uL of 100ug / mL Pb3O4 nanoparticle suspension or PbO2 suspension, and different amounts of 0.1mg / mL thiourea solution are added to a 5mL centrifuge tube in sequence, and the prepared experimental sample capacity is 2mL, and the test solution prepared using the experimental sample needs to be placed at room temperature for 10 minutes before testing; the preparation method of experimental sample 2 is: HAc / NaAc buffer, 40uL of TMB solution, 20uL of oxidant solution, and 20-200uL of thiourea standard solution are added to a 5mL centrifuge tube in sequence, and the prepared experimental sample capacity is 2mL, and the test solution prepared using the experimental sample needs to be reacted in a 37°C constant temperature water bath for 5 minutes before testing; Step 5, prepare a test sample, add an oxidant to the test sample to obtain a test solution, place the test solution at room temperature for 10 minutes or react in a 37°C constant temperature water bath for 5 minutes, test it using a UV-visible spectrophotometer and record spectral data, calculate the thiourea concentration under the corresponding spectral data using the working curve in step 4, and then realize the analysis and detection of the thiourea concentration in the copper electrolyte sample; When Pb3O4 nanoparticles or PbO2 particles are used as oxidants, the preparation method of the test sample is as follows: dilute the copper electrolyte to be tested 10 times to obtain an unknown thiourea sample, and add 20uLTMB solution, deionized water, 100uL of sulfuric acid solution, 200uL of 100ug / mL Pb3O4 nanoparticle suspension or PbO2 suspension, and an equal amount of unknown thiourea sample to a 5mL centrifuge tube in sequence, and the prepared experimental sample capacity is 2mL.

2. The method for analyzing and detecting thiourea in a copper electrolyte according to claim 1, characterized in that: The glassware pretreatment method is: all glassware used in the experiment are soaked in aqua regia for 30 minutes.

3. The method for analyzing and detecting thiourea in a copper electrolyte according to claim 1, characterized in that: During the synthesis process of the Pb3O4 nanoparticles, the brown precipitate needs to be washed with ultrapure water and filtered three times; and the obtained orange-red solid particles need to be tested to confirm that the prepared nanomaterial is Pb3O4 nanoparticles; the prepared Pb3O4 nanoparticles have a size of about 100nm, but a relatively irregular shape.

4. The method for analyzing and detecting thiourea in a copper electrolyte according to claim 1, characterized in that: The Pb3O4 nanoparticle suspension needs to be ultrasonically treated before each use to make it evenly dispersed.

5. The method for analyzing and detecting thiourea in a copper electrolyte according to claim 3, characterized in that: The method for detecting the orange-red solid particles is: perform XRD analysis on both the synthesized orange-red solid particles and analytically pure AR Pb3O4, and compare the obtained XRD patterns. If the two XRD patterns are consistent, it means that the experimentally prepared nanomaterial is Pb3O4 nanoparticles.

6. The method for analyzing and detecting thiourea in a copper electrolyte according to claim 1, characterized in that: In step 4, the known thiourea concentrations in the experimental sample 1 are 0 mg / L, 1 mg / L, 2.5 mg / L, 5 mg / L and 10 mg / L respectively; the 200 uL TMB solution is dissolved in a 5 mM ethanol solution; The known thiourea concentrations in experimental sample 2 were 10ug / mL, 20ug / mL, 40ug / mL, 70ug / mL, and 100ug / mL; The preparation method of TMB solution is as follows: accurately weigh 30 mg of TMB, dissolve it in anhydrous ethanol solution and dilute it to 5 mL; The preparation method of thiourea stock solution is as follows: accurately weigh 10 mg of thiourea, add 10 mL of buffer solution, and dissolve completely.

7. The method for analyzing and detecting thiourea in a copper electrolyte according to claim 1, characterized in that: A comparative experiment was used to verify that the strong oxidizing property of Pb3O4 comes from PbO2. Based on the comparative experiment, it was concluded that PbO2 and Pb3O4 can be relatively replaced. The reagents used in the comparative experiment were 10mM TMB solution, water, Pb3O4 solution and PbO2 solution, and the volume of the reagents configured in the comparative experiment was 2mL.

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