Method for detecting gelatin concentration in electrolyte for copper electrolytic refining

Abstract

The application provides a detection method for gelatin concentration in electrolyte for copper electrolytic refining, comprising: forming a precipitate by reacting the filtered copper electrolytic refining electrolyte with a cyanidin solution; dissolving the precipitate with a precipitate dissolving agent and then reacting with a chromogenic agent; determining the strongest absorption wavelength U and its absorbance value by using an ultraviolet-visible spectrophotometer; preparing a control solution, and obtaining a net absorbance value by background deduction; preparing 5-10 standard copper solutions with known gelatin concentrations, and determining the net absorbance value of each standard copper solution; and calculating the gelatin concentration in the electrolyte according to the gelatin concentration and the net absorbance value of the standard copper solution fitting a standard exponential equation curve. The combined process of specific precipitation separation-dissolution-color development reaction-ultraviolet spectrophotometric detection realizes accurate determination of the gelatin concentration in the complex copper electrolyte system, and has the technical effects of strong anti-interference, simple operation, wide detection range, high precision and low equipment dependency.

Description

Technical Field

[0001] This invention relates to the field of copper electrolytic refining technology, and more specifically, to a method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining. Background Technology

[0002] Copper electrolytic refining is a key process in the production of high-purity cathode copper, and the precise control of additives in the electrolyte directly affects product quality. Gelatin, as an important organic additive in the copper electrolysis process, mainly increases electrochemical polarization, inhibits dendrite growth, and refines the grain structure by forming an adsorption film on the cathode surface, thereby obtaining a smooth and dense cathode copper deposition layer. In the copper electrolytic refining process, precise control of gelatin concentration is crucial: too low a concentration will lead to a rough cathode copper surface and nodule formation, while too high a concentration will increase electrolyte viscosity and hinder Cu production. 2+ Migration reduces current efficiency and triggers hydrogen evolution side reactions.

[0003] Copper electrolyte systems are complex and typically contain high concentrations of Cu. 2+ Sulfuric acid and other organic additives (such as thiourea, polyethylene glycol, etc.) are present. Furthermore, gelatin is easily hydrolyzed and degraded under strong acid and high temperature (60-65℃) conditions, leading to a rapid decrease in its effective concentration. These factors collectively constitute the technical challenge for accurate detection of gelatin concentration. Currently, the main methods for detecting gelatin concentration in copper electrolytes include: electrochemical methods (such as cyclic voltammetry dissolution method) which indirectly determine the concentration by measuring the polarization ability of gelatin. However, gelatin's electrochemical properties are unstable in acidic electrolytes, and its polarization ability changes over time, easily leading to a false impression of "concentration increase." It is also significantly affected by other additives, resulting in large deviations in the detection results. CN112798674B discloses a method for detecting the effective gelatin concentration in copper electrolytes using hydrodynamic voltammetry, which improves detection accuracy but still cannot completely eliminate the interference of other additives. Liquid chromatography-mass spectrometry requires complex pretreatment processes such as solid-phase extraction and elution, resulting in long analysis cycles and high equipment costs, making it difficult to meet the real-time requirements of industrial online monitoring. CN113466148A discloses a method for separating impurities such as ions and small-molecule organic matter in copper electrolytes by referencing biodialysis technology. This method can intercept and enrich large-molecule organic matter (including effective gelatin) that has not yet decomposed, but the operation process remains relatively complex. Traditional ultraviolet spectrophotometry is limited by the high concentration of Cu in the copper electrolyte. 2+Strong blue background absorption interference makes it difficult to accurately detect gelatin characteristic peaks and distinguish between effective gelatin and degradation products, resulting in poor quantitative accuracy. CN120142205A discloses an analytical detection method for gelatin content in electrolytes, using a spectrophotometer to measure absorbance at 595 nm, but it is insufficient for handling interfering substances in complex electrolyte systems. CN117890317A discloses a method for determining gelatin content in copper electrodeposition solutions, using cerium sulfate to oxidize and decompose gelatin, and calculating gelatin content by measuring the change in absorbance before and after the reaction using spectrophotometry, but this method has difficulty distinguishing between effective gelatin and degradation products. CN119198693A discloses a reagent composition and method for detecting additive content in electroplating solutions, including a precipitant, a precipitant solvent, and a colorimetric agent, but it is mainly for electroplating solutions rather than copper electrolyte systems. Gravimetric methods are cumbersome and time-consuming, requiring multiple steps such as precipitation, filtration, drying, and weighing, making them unsuitable for rapid batch detection and difficult to guarantee detection accuracy.

[0004] In summary, existing methods for detecting gelatin concentration in electrolytes used in copper electrolysis suffer from technical defects such as poor anti-interference ability, complex operation, long detection cycle, and insufficient accuracy, making it difficult to meet the needs of rapid and accurate detection of gelatin concentration in industrial production.

[0005] Therefore, developing a method for detecting gelatin concentration in electrolyte used in copper electrolytic refining that is highly resistant to interference, easy to operate, accurate in detection, and applicable to industrial sites, so as to provide a reliable basis for the precise replenishment of additives in copper electrolytic production, is one of the important technical problems that need to be solved in this field. Summary of the Invention

[0006] The main objective of this invention is to provide a method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining, in order to solve the problems of existing methods for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining, which have poor anti-interference capabilities, are complex to operate, are not accurate enough, and are not suitable for industrial sites.

[0007] To achieve the above objectives, the present invention provides a method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining, comprising: step S1, filtering the electrolyte used in copper electrolytic refining to obtain the electrolyte to be tested; reacting the electrolyte to be tested with an anthocyanin solution at a concentration of 0.5±0.05 g / L to obtain a precipitate product; step S2, dissolving the precipitate product with a precipitant to obtain a first solution; reacting the first solution with an iron-containing indicator to obtain a second solution; detecting the strongest absorption wavelength of the second solution using a UV-Vis spectrophotometer and recording it as U; step S3, detecting the net absorption... Photometric value ΔW: Step S3-1, within the wavelength range of U±5nm, the absorbance value of the second solution is detected using a UV-Vis spectrophotometer, and the stable absorbance value is recorded as W1. Step S3-2, a control solution is prepared using an equal amount of precipitant and dissolving agent as in Step S2, and an equal amount of display agent as in Step S2. Within the wavelength range of U±5nm, the control solution is used as a blank sample for background subtraction to obtain the net absorbance value, which is recorded as ΔW0. Step S4-1, n standard copper solutions containing gelatin are prepared and denoted as solutions An respectively. Each solution An is reacted with Cu in the electrolyte to be tested. 2+ The concentrations are the same; the gelatin concentration in each solution An is denoted as Pn, and the n Pn are all different and each is independently 0.01ppm~1000ppm; n is 5~10; in step S4-2, referring to step S3, the net absorbance value ΔW of each solution An is detected and denoted as ΔWn; based on the n Pn and n ΔWn, the absorbance-gelatin concentration standard exponential equation curve is fitted, and then the gelatin concentration in the electrolyte used for copper electrolytic refining is calculated.

[0008] Furthermore, n is 5, P1 of solution A1 is 0.01ppm~0.012ppm, P2 of solution A2 is 1±0.02ppm, P3 of solution A3 is 10±1ppm, P4 of solution A4 is 100±10ppm, and P5 of solution A5 is 950ppm~1000ppm.

[0009] Furthermore, in step S1, the Cu in the electrolyte used for copper electrolytic refining 2+ The concentration of SO4 is 40 g / L~60 g / L. 2+ The concentration is 100g / L~200g / L, and the concentration of gelatin is ≤1000ppm.

[0010] Further, in step S1, the volume ratio of the electrolyte to the anthocyanin solution is (2~30):(5~20); and / or, the anthocyanin solution also contains a complexing agent with a concentration of 0.5mol / L~2.0mol / L, and the complexing agent is selected from one or more of citric acid, sodium citrate, sodium gluconate, tartaric acid, potassium sodium tartrate, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, and diethanolamine; the precipitation reaction is carried out by ultrasonic treatment at 25℃~35℃, and the ultrasonic treatment power is 300W~500W for 5min~15min; or, the precipitation reaction is carried out by oscillation treatment at 25℃~35℃, and the oscillation treatment rate is 100rpm~300rpm for 5min~15min.

[0011] Furthermore, in step S1, filtration is performed using a filter membrane with a pore size of 0.2μm to 0.25μm.

[0012] Further, in step S2, the precipitant is selected from one of sodium hydroxide solution, sodium chloride solution, weakly alkaline buffer solution, alkaline complexing solution, and ethanol-hydrochloric acid mixture, more preferably ethanol-hydrochloric acid mixture; preferably, the weakly alkaline buffer solution is selected from one or more of borax-sodium hydroxide buffer solution, ammonia-ammonium chloride buffer solution, and sodium carbonate-sodium bicarbonate buffer solution; preferably, the alkaline complexing solution is sodium dodecyl sulfate-triethanolamine mixture, and in the sodium dodecyl sulfate-triethanolamine mixture, the concentration of sodium dodecyl sulfate is 10 g / L to 50 g / L, and the concentration of triethanolamine is 10 mL / L to 50 mL / L; preferably, in the ethanol-hydrochloric acid mixture, the volume fraction of ethanol is 30% to 40%, and the concentration of hydrochloric acid is 0.05 mol / L to 0.3 mol / L.

[0013] Furthermore, in step S2, the colorimetric reagent includes Fe at a concentration of 1 g / L to 15 g / L. 3+ ; and / or, the color developer further includes hydrochloric acid and optional auxiliaries, wherein the auxiliaries are selected from one or more of acetic acid, citric acid, propylene glycol, and glycerol; preferably, Fe 3+ It exists in the form of potassium ferricyanide, ferric sulfate, ferric chloride, or ferric tribromide; preferably, the colorimetric reagent includes Fe at a concentration of 10±2 g / L. 3+ Preferably, the color developer also includes hydrochloric acid and an auxiliary agent, and the volume ratio of hydrochloric acid to the auxiliary agent is (1~5):(0.1~1).

[0014] Furthermore, in step S2, dissolution is performed by ultrasonic treatment, with a power of 300W~500W and a time of 5min~15min; and / or, the colorimetric reaction is carried out at 25℃~35℃, and the temperature fluctuation during the colorimetric reaction is ≤±2℃.

[0015] Furthermore, in step S2, the photometric repeatability of the UV-Vis spectrophotometer is ≤0.001Abs, the noise is ≤0.0002Abs, and the scan rate is 100nm / min~200nm / min.

[0016] Further, in step S4, at least three parallel tests are performed for each ΔWn, and the average value is taken; the goodness of fit R 2 ≥0.998.

[0017] By applying the technical solution of this invention, through a combined process of "specific precipitation separation - targeted dissolution - colorimetric reaction - ultraviolet spectrophotometric detection," coupled with the establishment of a standard curve, the goal of accurately determining gelatin concentration in the electrolyte system used in complex copper electrolytic refining is achieved. This results in strong anti-interference capabilities, simple operation, wide detection range, high precision, and low equipment dependence. Specifically: anthocyanins, as a precipitant, can form hydrophobic and hydrogen bonds with peptide groups in gelatin, selectively precipitating gelatin without interacting with copper ions, sulfate ions, or other organic additives, achieving highly selective precipitation separation of gelatin and effectively eliminating interfering substances in the copper electrolyte; secondly, the precipitate is dissolved using a precipitant dissolving agent, and a reliable light absorption signal is provided for subsequent quantitative detection through a colorimetric reaction; and the influence of solvent, indicator itself, and instrument background is effectively eliminated through the calculation of the net absorbance value ΔW0; finally, by constructing a standard curve, qualitative analysis is transformed into quantitative analysis, avoiding interference caused by Cu... 2+ The deviation in colorimetric effect caused by concentration differences ensures the applicability and accuracy of the standard curve. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 This is the absorbance-gelatin concentration standard index equation curve obtained by fitting in Example 1 of the present invention;

[0020] Figure 2 This is the standard linear equation curve of absorbance-gelatin concentration obtained by fitting in Example 1 of the present invention. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0022] As described in the background art, existing methods for detecting gelatin concentration in electrolytes used in copper electrolytic refining suffer from poor anti-interference capabilities, complex operation, insufficient detection accuracy, and unsuitability for industrial settings. To address these technical problems, this invention provides a method for detecting gelatin concentration in electrolytes used in copper electrolytic refining, comprising: Step S1, filtering the electrolyte used in copper electrolytic refining to obtain a test electrolyte; reacting the test electrolyte with an anthocyanin solution at a concentration of 0.5 ± 0.05 g / L to obtain a precipitate; Step S2, dissolving the precipitate with a precipitant dissolving agent to obtain a first solution; reacting the first solution with an iron-containing indicator to obtain a second solution; detecting the strongest absorption wavelength of the second solution using a UV-Vis spectrophotometer and recording it as U; Step S3, detecting the net... Absorbance value ΔW: Step S3-1, within the wavelength range of U±5nm, the absorbance value of the second solution is detected using a UV-Vis spectrophotometer, and the stable absorbance value is recorded as W1. Step S3-2, a control solution is prepared using an equal amount of precipitant and dissolving agent as in Step S2, and an equal amount of display agent as in Step S2. Within the wavelength range of U±5nm, the control solution is used as a blank sample for background subtraction to obtain the net absorbance value, which is recorded as ΔW0. Step S4-1, n standard copper solutions containing gelatin are prepared and denoted as solutions An respectively. Each solution An is reacted with Cu in the electrolyte to be tested. 2+ The concentrations are the same; the gelatin concentration in each solution An is denoted as Pn, and the n Pn are all different and each is independently 0.01ppm~1000ppm; n is 5~10; in step S4-2, referring to step S3, the net absorbance value ΔW of each solution An is detected and denoted as ΔWn; based on the n Pn and n ΔWn, the absorbance-gelatin concentration standard exponential equation curve is fitted, and then the gelatin concentration in the electrolyte used for copper electrolytic refining is calculated.

[0023] This invention overcomes the limitations of traditional single detection technologies by constructing a multi-dimensional synergistic analysis system encompassing "specific precipitation separation - dissolution - colorimetric reaction - ultraviolet spectrophotometric detection." Based on the theoretical support of molecular recognition, phase transfer regulation, and the Lambert-Beer law, it achieves precise quantification of the effective gelatin concentration in copper electrolytic refining electrolytes. Its core technical logic and theoretical basis are as follows:

[0024] Targeted enrichment based on intermolecular interactions: Gelatin, as a water-soluble natural polymer, is rich in polar groups such as hydroxyl (-OH), amino (-NH2), and carboxyl (-COOH) groups on its molecular chain; gelatin denatures upon contact with acids or alkalis (H... + )NH 3+ -Gel-COOH—NH3 + -Gel-COO - —NH3-Gel-COO- (OH - When the pH of the solution deviates too far from the isoelectric point of gelatin, the gelatin molecules become unbalanced and aggregate, protonating or deprotonating, leading to precipitation. Anthocyanins, under certain pH conditions, dissociate into hydrogen ions, exhibiting weak acidity and carrying a negative charge. Meanwhile, gelatin, a hydrolysis product of collagen, contains numerous amino and carboxyl groups. Its charge is determined by pH (when the pH is higher than the isoelectric point of gelatin, gelatin carries a negative charge, increasing electrostatic repulsion with anthocyanins, reducing or even dissolving precipitation; the lower the pH, the stronger the positive charge of gelatin, and the more pronounced the precipitation); when the system pH is lower than the isoelectric point of gelatin (approximately pH = 5.0 ± 0.3), gelatin molecules carry a positive charge.

[0025] In other words, during the precipitation reaction, anthocyanin solution is added to the electrolyte to gradually raise the pH of the reaction system to 5.0 ± 0.3. At this point, the negatively charged anthocyanins and the positively charged gelatin combine through electrostatic attraction, forming molecular aggregates via electrostatic interaction and hydrogen bonding, which then precipitate from the solution. This reaction exhibits significant molecular recognition specificity—Cu in the electrolyte... 2+ (Inorganic cations), SO4 2- / Cl - (Inorganic anions) and possibly thiourea (one of the small molecule organic additives) lack polar groups and spatial structures that match anthocyanins, thus preventing them from participating in the formation of complex precipitates and achieving efficient separation of gelatin from interfering components. Dissolution is then performed to avoid uneven colorimetric reactions caused by molecular aggregation.

[0026] Precipitation and dissolution: The dissolution reaction of anthocyanin-gelatin precipitate involves breaking the binding force between the two. Adding an alkaline solution (NaOH) increases the pH, causing the gelatin molecules to become negatively charged, resulting in electrostatic repulsion between them and anthocyanins. At the same time, the anthocyanin structure transforms into a quinone form under alkaline conditions, increasing its solubility. Alternatively, adding NaCl can achieve precipitation and dissolution by competing for hydrogen bond binding sites through the salting-out effect.

[0027] Color reaction: The first solution after dissolution contains anthocyanins, which can undergo a complexation reaction with ferric ions to produce a color reaction (after the anthocyanins dissociate, the catechol / pyrogallol groups in the solution can act as polydentate ligands and react with the Fe in the color reagent). 3+ A complexation reaction occurs, forming a stable chelate; the chelate molecule contains "Fe". 3+ -O - (Coordination conjugated system), generating characteristic colored compounds.

[0028] Subsequently, ultraviolet spectrophotometric detection was performed, with signal amplification and interference subtraction based on high-precision instruments; the "Fe" of the gelatin-anthocyanin-ferric chloride chelate was analyzed. 3+ -O - "Coordinate bonds can undergo dd transitions and charge transfer transitions. The molar absorptivity of charge transfer transitions is higher than that of dd transitions, forming a strong absorption band in the 400-700 nm range, ensuring the strength and stability of the detection signal. The process of determining the optimal detection wavelength U is based on a dual-objective optimization of 'signal strength - interference avoidance': on the one hand, the principle of maximizing signal strength; U corresponds to the maximum absorption wavelength of the mixed system, at which point the absorbance value of the system is the largest. According to the Lambert-Beer law (A=εbc), the linear correlation between absorbance and concentration is the strongest (correlation coefficient R)." 2 ≥0.999) can reduce concentration calculation errors; on the other hand, the principle of minimizing interference: in the 400~700nm range, Cu in the electrolyte 2+ The interference from the characteristic absorption peak (≈800nm) and reagent background (e.g., ferric chloride, which has weak absorption in the 500~600nm range) is negligible. Furthermore, the wavelength range of U±5nm is further confined within the full width at half maximum (FWHM) of the characteristic absorption peak, effectively avoiding interference from scattered light from other trace impurities (such as suspended particles in the electrolyte), ensuring a direct correlation between the detection signal and the gelatin concentration. Simultaneously, detection within the U±5nm range, combined with a blank control, conforms to differential spectrophotometry, ensuring that the measured absorbance originates solely from the gelatin colorimetric product. Moreover, the narrow wavelength range of U±5nm reduces errors caused by instrument wavelength drift and avoids the influence of ambient light on detection. Combined with the instrument's baseline correction function, background interference can be controlled within ±0.0001Abs, meeting the theoretical requirements for high-precision detection.

[0029] In summary, this invention, through theoretical synergy and parameter optimization of various technical steps, forms a closed loop of "separation-dissolution-color development-detection," effectively solving the technical bottlenecks of poor anti-interference and insufficient accuracy of traditional methods. It enables rapid, accurate, and on-site detection of gelatin concentration in copper electrolytic refining electrolyte, providing reliable analytical technical support for real-time control of electrolysis process parameters.

[0030] To further reduce errors, the actual implementation also includes washing the resulting precipitate. Water can be used as the washing solution, and the washing process should be repeated at least three times. This is because the copper electrolyte contains a high concentration of Cu. 2+ It can complex with anthocyanins and iron ions, interfering with color development. Therefore, after precipitation, it must be washed with deionized water.

[0031] In several typical implementations: n is 5, P1 of solution A1 is 0.01ppm~0.012ppm, P2 of solution A2 is 1±0.02ppm, P3 of solution A3 is 10±1ppm, P4 of solution A4 is 100±10ppm, and P5 of solution A5 is 950ppm~1000ppm. In this preferred embodiment, by detecting the net absorbance value ΔWn of the above five solutions on a UV-Vis spectrophotometer, and fitting an absorbance-gelatin concentration standard curve accordingly, the accurate correction of gelatin concentration in electrolytes used in industrial settings can be achieved more efficiently. Compared to fewer standard points, five concentration points can better depict the correspondence between absorbance values ​​and gelatin concentration (concentration (x) - signal value (absorbance, y)), further improving the goodness of fit of the standard curve, and ultimately significantly improving the accuracy and reliability of concentration calculation.

[0032] Optimizing the standard curve can improve its accuracy and stability, thereby enhancing the precision of gelatin content analysis and detection. When gelatin concentration is too high (>1.5 ppm), the UV signal is prone to saturation, and the linear equation will deviate significantly. However, the exponential equation can accurately fit the concentration-signal relationship during the signal saturation phase, covering the low concentration range of 0.01~10 ppm, eliminating the need for interval fitting. Furthermore, in the complex copper electrolyte system, the gelatin signal is susceptible to interference from coexisting ions (such as Cu). + SO4 2- The influence of this factor leads to distortion of the linear response, resulting in an incorrect R-value after fitting the exponential equation. 2 Higher accuracy and more precise quantification; furthermore, during testing, trace amounts of gelatin (<0.01 mg / mL) produce weak signals, and when the signal saturates at high concentrations, the error of the linear equation increases significantly. In contrast, the exponential equation accurately captures the exponential changes in the signal, reducing the detection error of trace amounts to ±0.0005 mg / mL, and achieving an RSD ≤1.5% for high concentrations. When gelatin reacts with the chromogenic agent, the signal often increases exponentially with concentration (slow at low concentrations, rapid at medium and high concentrations). The exponential equation shows a 15%–18% better fit than the linear equation.

[0033] For the electrolyte used in copper electrolytic refining, Cu is preferred. 2+ The concentration of SO4 is 40 g / L~60 g / L. 2+ The concentration of Cu is 100g / L~200g / L, and the concentration of gelatin is ≤1000ppm. That is to say, Cu... 2+ and SO4 2+The high concentration of sulfuric acid will not interfere with the gelatin detection method provided by this invention. Furthermore, setting the upper limit of the detectable gelatin concentration to 1000 ppm effectively covers the typical concentration range of gelatin added during copper electrolysis, allowing the detection method provided by this invention to better adapt to various industrial production conditions and meet the needs of real-time online monitoring.

[0034] In practical applications, when the gelatin concentration in the copper electrolyte to be tested exceeds 1000 ppm, a blank electrolyte (dissolved in the copper electrolyte to be tested) must be used. 2+ The solution (with consistent sulfuric acid concentration but without gelatin) is diluted to ≤1000ppm (specifically, 0.01~1000ppm) before the above tests are performed. Furthermore, the electrolyte used in the electrolytic refining of copper may contain additives such as accelerators (e.g., sodium polydithiopropane sulfonate) and inhibitors (e.g., polyethylene glycol). However, because the anthocyanins selected in this invention can specifically bind and precipitate with gelatin, they are not affected by the aforementioned additives.

[0035] In step S1, based on considerations of reaction equilibrium and precipitation efficiency, the preferred volume ratio of the electrolyte to the anthocyanin solution is (2~30):(5~20), more preferably (1~2.5):1, so as to facilitate the anthocyanin solution to more effectively bind with the gelatin molecules in the electrolyte, forming a sufficient amount of complex, thereby further improving the integrity and recovery rate of the precipitation, and ultimately obtaining a more accurate gelatin concentration detection result. Simultaneously, the anthocyanin solution preferably also contains a complexing agent with a concentration of 0.5 mol / L~2.0 mol / L, and the complexing agent is selected from one or more of citric acid, sodium citrate, sodium gluconate, tartaric acid, potassium sodium tartrate, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, and diethanolamine. In this preferred embodiment, the complexing agent in the anthocyanin solution, such as citric acid, is a polydentate ligand that can react with Cu... 2+ (The electrolyte used in copper electrolytic refining is an acidic copper sulfate solution with a pH of approximately 1.5–2.5) forming a more stable soluble chelate [Cu(Cit)]. - This can reduce free Cu 2 + Concentration, causing ion accumulation Q c is further reduced to avoid Cu(OH)2 precipitate not forming when the pH is 5.0±0.3.

[0036] To achieve more efficient precipitation separation while maintaining the stability of gelatin-containing precipitates, the precipitation reaction is preferably carried out at 25°C to 35°C by ultrasonic treatment, with a power of 300W to 500W and a duration of 5 to 15 minutes; alternatively, the precipitation reaction is carried out at 25°C to 35°C by oscillation treatment, with an oscillation rate of 100rpm to 300rpm and a duration of 5 to 15 minutes, in order to further improve the accuracy and reproducibility of the detection.

[0037] Generally, in copper electrolytic refining, the electrolyte often contains undissolved anode mud particles and other tiny suspended matter. These impurities not only interfere with the selective precipitation of anthocyanins but may also clog the filtration equipment, affecting the integrity and purity of the precipitate. Therefore, it is preferable to use a filter membrane with a pore size of 0.2μm~0.25μm in step S1 to effectively retain these tiny particles and better maintain the anthocyanin precipitation reaction undisturbed, thereby further optimizing the subsequent dissolution and detection processes.

[0038] Further, in step S2, the preferred precipitant is selected from sodium hydroxide solution, sodium chloride solution, weakly alkaline buffer solution, alkaline complexing solution, and ethanol-hydrochloric acid mixture. The ethanol-hydrochloric acid mixture, in particular, achieves better dissolution, even "targeted dissolution." Specifically, the dissolution process of the gelatin-anthocyanin complex precipitate needs to balance "efficient dissociation" with the "protection of gelatin molecular integrity." This invention further prefers the ethanol-hydrochloric acid mixture as the precipitant, its function being, on the one hand, the protonation effect of hydrochloric acid: the H+ provided by hydrochloric acid... + It can bind to the phenolic hydroxyl groups in anthocyanin molecules, disrupting the hydrogen bonds between them and gelatin, thus shifting the dissociation equilibrium of the precipitated complex further towards dissolution. On the other hand, ethanol has solubilizing and stabilizing effects: it reduces the hydrophobic aggregation tendency of gelatin molecules and inhibits the polymerization reaction of anthocyanins due to protonation, promoting a more stable monodisperse state of gelatin in solution (particle size distribution range of approximately 10-20 nm), reducing uneven color development caused by molecular aggregation. To further enhance these effects, it is preferable that the volume fraction of ethanol in the ethanol-hydrochloric acid mixture is 30%-40%, and the concentration of hydrochloric acid is 0.05 mol / L-0.3 mol / L.

[0039] In practical applications: the sodium hydroxide solution, sodium chloride solution, and weakly alkaline buffer solution are selected from one or more of the following: borax-sodium hydroxide buffer solution, ammonia-ammonium chloride buffer solution, and sodium carbonate-sodium bicarbonate buffer solution. To more efficiently dissolve the precipitate and achieve more accurate gelatin concentration detection, the alkaline complexing solution is a sodium dodecyl sulfate-triethanolamine mixture, wherein the concentration of sodium dodecyl sulfate in the sodium dodecyl sulfate-triethanolamine mixture is 10 g / L to 50 g / L, and the concentration of triethanolamine is 10 mL / L to 50 mL / L.

[0040] To further accelerate the dispersion and dissolution of the precipitate, in preferred step S2, dissolution is performed by ultrasonic treatment with a power of 300W~500W for 5min~15min. In this preferred scheme, the cavitation effect generated by ultrasound more thoroughly disrupts the hydrogen bonds and hydrophobic interactions in the gelatin-anthocyanin precipitate, promoting faster dissolution of the precipitate. Simultaneously, it reduces the destruction of gelatin molecules, thereby better maintaining the accuracy of subsequent colorimetric reactions and ultimately obtaining more precise test results.

[0041] In step S2, the colorimetric agent preferably includes Fe at a concentration of 1 g / L to 15 g / L (more preferably 10 ± 2 g / L). 3+ ; and / or, the colorimetric reagent further includes hydrochloric acid and optional auxiliaries, wherein the auxiliaries are selected from one or more of acetic acid, citric acid, propylene glycol, and glycerol. In the detection method provided by the present invention, the colorimetric reaction is preferably based on the complexation reaction of ferric chloride and gelatin. In the ferric chloride-hydrochloric acid colorimetric system, Fe 3+ It forms a purplish-red complex with the amino and carboxyl groups in gelatin molecules, and the intensity of the color is directly proportional to the gelatin concentration. The presence of hydrochloric acid is to inhibit Fe... 3+ Hydrolysis (i.e., preventing Fe) 3+ Insoluble Fe(OH)3 precipitate forms in the aqueous phase, thus maintaining the stability of the colorimetric system. Based on this, further optimization of the concentrations of both components, as described above, promotes the formation of Fe... 3+ It can bind more fully and stably with gelatin, thereby further improving the sensitivity and accuracy of detection. In practical applications, Fe is preferred. 3+ It exists in the form of potassium ferricyanide, ferric sulfate, ferric chloride, or ferric tribromide, and the mass concentration of HCl in hydrochloric acid can be 36%~38%. Furthermore, in order to further maintain Fe... 3+ - The stability of the gelatin complex is improved, and the consistency of the colorimetric reaction is better maintained. The colorimetric reaction is preferably carried out at 25℃~35℃, and the temperature fluctuation during the colorimetric reaction process is ≤±2℃, which further enhances the comparability and accuracy of the test results.

[0042] Meanwhile, among the aforementioned additives, acetic acid and citric acid are used to adjust pH and to complex and stabilize Fe. 3+ Propylene glycol and glycerol can act as co-solvents to improve the stability of the system. In several more typical embodiments, the colorimetric reagent includes both hydrochloric acid and an auxiliary agent, and the volume ratio of hydrochloric acid to the auxiliary agent is (1~5):(0.1~1). More specifically, the colorimetric reagent preferably contains hydrochloric acid and acetic acid in a volume ratio of 4:(0.5~1) to achieve a more stable complexation effect and further improve the detection accuracy.

[0043] In several more typical embodiments, the preferred color developer also includes ninhydrin at a concentration of 1 g / L to 5 g / L. For gelatin, which is composed of amino acid residues, the free amino groups (-NH2) in basic amino acids such as lysine and arginine can undergo a Ruhemann purple color reaction with ninhydrin (the color developer). (The π-π conjugated system of the Ruhemann purple molecule can absorb photons in the 400-700 nm visible light region, undergoing a π→π reaction.) Electron transitions, their maximum absorption wavelength (λ) max The absorbance is approximately 570 nm, corresponding to the characteristic absorption of the purplish-red product. Under conditions of 30±5℃, ninhydrin, as one of the colorimetric agents, first condenses with an amino group to form an imine intermediate, followed by intramolecular rearrangement, decarboxylation, and redox reactions, ultimately generating a stable purplish-red product. The π-π conjugated system of this purplish-red product can form a synergistic absorption effect with the gelatin-anthocyanin-ferric chloride chelate, and the absorption peaks of the latter partially overlap, forming a strong absorption band in the 400~700 nm range. This further enhances the absorbance signal at the characteristic wavelength, lowering the detection limit to 0.001 ppm, better meeting the quantitative requirements for trace gelatin.

[0044] For the UV-Vis spectrophotometer used in step S2 to determine the strongest absorption wavelength U, it is preferred to have a photometric repeatability ≤0.001Abs, noise ≤0.0002Abs, and a scan rate of 100nm / min~200nm / min. This is to maintain sufficient data sampling rate and spectral resolution while improving detection efficiency, and to reduce the problem of spectral information loss or signal-to-noise ratio reduction caused by excessively fast scanning. More importantly, this scan rate can be used in gelatin complexes (specifically, Fe...). 3+ Within the stability window of the gelatin complex, the spectral scan is completed more rapidly, thereby capturing the optimal absorption peak and reducing the photodegradation or thermal decomposition that may occur under long-term exposure, thus more effectively ensuring the authenticity and validity of the test results.

[0045] Of course, in addition to this, the UV-Vis spectrophotometer used in the other steps can also be preferably configured with the same accuracy and scanning rate as above, so as to more effectively improve the detection accuracy and reliability.

[0046] In step S4, to further improve the accuracy of the standard curve and obtain more precise gelatin concentration detection results, it is preferable to perform at least three parallel tests for each ΔWn and take the average value. Simultaneously, the goodness of fit R is preferably... 2 ≥0.998.

[0047] In summary, the detection method provided by this invention can selectively separate gelatin through the specific precipitation reaction of anthocyanins with gelatin, effectively avoiding Cu in the electrolyte. 2+ SO4 2+ The system mitigates interference from coexisting components such as thiourea; it also uses a control solution to subtract the reagent blank, further reducing systematic errors; and employs a high-precision UV-Vis spectrophotometer (with photometric repeatability ≤0.001Abs and noise ≤0.0002Abs), combined with a specific colorimetric system, achieving a detection limit of 0.008ppm, a relative standard deviation (RSD) ≤1%, and an absolute error ≤±0.001ppm (trace range) and ±0.2ppm (constant range). Furthermore, the entire detection process (including sample pretreatment, reaction, and detection) can be completed within 60 minutes, requiring no complex equipment and meeting the rapid detection needs of industrial sites; the concentration detection range covers 0.01ppm to 1000ppm, satisfying the gelatin concentration monitoring requirements at different stages of copper electrolytic refining.

[0048] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0049] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0050] Example 1

[0051] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0052] Step (S1): Copper electrolyte pretreatment and gelatin precipitation separation; the copper electrolyte to be tested is filtered through a 0.22μm microporous membrane, wherein the Cu in the copper electrolyte to be tested is separated. 2+ The concentration is 50 g / L, H2SO4 (i.e. SO42-) 2+The concentration was 150 g / L. The electrolyte was filtered through a 0.22 μm microporous membrane to remove suspended impurities such as anode mud particles, avoiding interference with subsequent precipitation separation and absorbance detection. 5 mL of the filtrate electrolyte was transferred to be tested, and 2 mL of a mixed solution of 0.5 g / L anthocyanin and 0.5 mol / L citric acid was added. The volume ratio of the mixed solution to the copper electrolyte was 2 mL:5 mL, resulting in a reaction system with a pH of approximately 5.0. The mixture was ultrasonically dispersed at 30°C using a 400 W ultrasonic device for 10 min to ensure a gelatin precipitation rate of 99%. After the reaction was complete, the mixture was centrifuged, and the precipitate was washed three times with deionized water to remove residual copper ions and sulfuric acid.

[0053] Step (S2): Precipitation dissolution and colorimetric reaction; The precipitate washed in step (S1) was ultrasonically dispersed with a precipitant dissolving agent, which was an aqueous solution containing 50 g / L sodium dodecyl sulfate and 50 mL / L triethanolamine, with a pH of 9.5. The ultrasonic power was set to 400 W, and the ultrasonic time was 10 min to promote complete dissolution of the precipitate, thus obtaining the first solution; After uniform dispersion, 5 mL of colorimetric reagent (containing 1 mL acetic acid and 4 mL of 36% hydrochloric acid, of which the concentration of ferric chloride was 10 g / L) was added. The colorimetric reaction temperature was controlled at 30 ± 1℃. After the reaction was complete, the second solution was obtained. The second solution was scanned at wavelengths of 400–700 nm using a UV-Vis spectrophotometer, with photometric repeatability ≤0.001 Abs, noise ≤0.0002 Abs, and a scan rate of 150 nm / min, and the strongest absorption wavelength U = 570 nm was determined.

[0054] Step (S3-1): Absorbance measurement and data processing; In the wavelength range of 565~575nm, test the change of absorbance of the second solution over time. When the absorbance changes by 0.8% within 30~60s, record the stable absorbance value as 0.5682.

[0055] Step (S3-2): At the same time, prepare a mixture of precipitant solvent and color developer, with the same amount of both as in step S2. Use it as a blank sample in the wavelength range of strongest absorption U±5nm, i.e., 565~575nm, and perform background subtraction to obtain a net absorbance value ΔW0 of 0.5421.

[0056] Step (S4-1): Establishment of standard curve and concentration calculation; preparation of Cu in step S1 2+ Five standard electrolytes for copper electrolysis were prepared, with the same concentration (50 g / L) and sulfuric acid concentration (150 g / L), and gelatin concentrations of 0.01 ppm, 1 ppm, 10 ppm, 100 ppm, and 1000 ppm, respectively. Each concentration level was tested in three parallel trials.

[0057] Step (S4-2): For the electrolytes used in the five standard copper electrolysis processes mentioned above, repeat step S3 to determine the net absorbance values ​​corresponding to different gelatin concentrations. During the test, each concentration should be tested in triplicate, and the average value should be taken to reduce error.

[0058] Step (S4-3): Plot and fit the absorbance-gelatin concentration standard index equation curve y=0.0244x with each gelatin concentration as the x-axis and each net absorbance value as the y-axis. 1.244 Goodness of fit R 2 The value reached 0.998. The standard curve obtained from this fitting is shown in the same table. Figure 1 Meanwhile, the standard linear curve of absorbance-gelatin concentration obtained by fitting is shown below. Figure 2 In comparison, the exponential equation curve has a higher goodness of fit, which leads to more accurate concentration results.

[0059] Step (S4-4): Substitute the net absorbance value of 1.472 obtained in step S3 into the fitted standard curve to calculate the effective concentration of gelatin in the electrolyte used for copper electrolysis as 27 ppm.

[0060] The relative standard deviation (RSD) of the test results from the actual amount of gelatin added was 0.63%.

[0061] Example 2

[0062] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0063] Step (S1): Pretreatment of the electrolyte to be tested, and detection of Cu in the electrolyte to be tested using inductively coupled plasma atomic emission spectrometry. 2+ The concentration was 50 g / L; sulfuric acid (SO4) was detected by acid-base titration. 2+ The concentration was confirmed to be 180 g / L. The electrolyte was filtered through a 0.22 μm microporous membrane to remove suspended impurities such as anode mud particles, avoiding interference with subsequent precipitation separation and absorbance detection. 10 mL of the filtered electrolyte was placed in a 50 mL centrifuge tube, and 10 mL of a 10 g / L anthocyanin + 1 mol / L sodium citrate mixed solution (volume ratio 1:1) was added. At this point, the pH of the reaction system was approximately 5.0. The reaction was carried out in a 30℃ constant temperature water bath with shaking for 30 min (shaking rate 200 rpm) to completely convert the gelatin into a complex precipitate. The centrifuge tube was centrifuged at 4000 rpm for 5 min, and the supernatant was discarded. The precipitate was washed 5 times with deionized water (each time adding 10 mL of deionized water, shaking, and centrifuging) until no Cu was found in the washings. 2+ Residue.

[0064] Step (S2): Precipitation dissolution and colorimetric reaction; 10 mL of precipitant dissolving agent was added to the precipitate washed in step (S1) and ultrasonically dispersed. The precipitant dissolving agent was an aqueous solution containing 20 g / L sodium dodecyl sulfate and 50 mL / L triethanolamine, with a pH of 10. The solution was stirred at 30 °C for 20 minutes, followed by ultrasonic dissolution at 400 W for 10 minutes to ensure complete dissolution of the precipitate, thus obtaining the first solution. After uniform dispersion, the solution was transferred to a 50 mL volumetric flask, and 5 mL of colorimetric reagent (containing 1 mL of acetic acid and 4 mL of 38% hydrochloric acid, with a ferric chloride concentration of 10 g / L) was added. The solution was then diluted to the mark with deionized water, shaken well, and allowed to stand at 28 °C for 20 minutes to complete the colorimetric reaction, yielding the test solution. Transfer the test solution into a 1cm quartz cuvette. Use a mixture of "10mL precipitant solvent + 5mL colorimetric reagent + deionized water to a final volume of 50mL" as a blank sample. Perform wavelength scanning from 400 to 700nm on a UV-Vis spectrophotometer (photometric repeatability ≤0.001Abs, noise ≤0.0002Abs, scan rate 150nm / min). Record the wavelength corresponding to the maximum absorbance (stable at 520nm). At this wavelength, the colored complex absorbs the strongest light and is not affected by other components in the electrolyte.

[0065] Step (S3-1): Absorbance measurement and data processing; continuously monitor the absorbance value of the test liquid at the strongest absorption wavelength of 520±5nm, record the data once every 5 seconds, and when the absorbance change rate is ≤1% for 12 consecutive times (60s), the absorbance is determined to be stable, and the stable value is recorded as 0.685.

[0066] Step (S3-2): Simultaneously, prepare a mixture of precipitant solvent and color developer, with the same amount of both as in step S2. At the strongest absorption wavelength of 520 nm, use it as a blank sample for background subtraction (the stable absorbance value of the blank sample is 0.021), and obtain a net absorbance value ΔW0 of 0.664.

[0067] Step (S4-1): Establishment of standard curve and concentration calculation; preparation of Cu in step S1 2+ Five standard electrolytes for copper electrolysis were prepared, with the same concentration (50 g / L) and sulfuric acid concentration (180 g / L), and gelatin concentrations of 0.01 ppm, 1 ppm, 10 ppm, 100 ppm, and 1000 ppm, respectively. Each concentration level was tested in three parallel trials.

[0068] Step (S4-2): For the electrolytes used in the five standard copper electrolysis processes mentioned above, repeat step S3 to determine the net absorbance values ​​corresponding to different gelatin concentrations. During the test, each concentration should be tested in triplicate, and the average value should be taken to reduce error.

[0069] Step (S4-3): Plot the gelatin concentration (x, ppm) on the x-axis and the net absorbance value (y) on the y-axis, and perform equation fitting to obtain the standard exponential curve equation y = 0.025x. 1.238 The higher the gelatin concentration, the more fully it binds with anthocyanins, and the less complex is formed in the colorimetric reaction. The goodness of fit R of the fitted curve... 2 It reached 0.998.

[0070] Step (S4-4): Substitute the net absorbance value of the test solution obtained in step S3, 13.385, into the fitted standard curve to calculate the effective concentration x of gelatin in the electrolyte used for copper electrolysis, which is 160 ppm.

[0071] The relative standard deviation (RSD) of the test results from the actual gelatin addition of 158 ppm was 1.27%.

[0072] Example 3

[0073] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0074] The only difference between this embodiment and Embodiment 1 is that:

[0075] Firstly, the precipitant solvent was changed to a 35% (v / v) ethanol-hydrochloric acid mixture (0.1 mol / L hydrochloric acid), with a volume of 5 mL. In this dissolution process, the hydrochloric acid provides H₂... + It can bind to the phenolic hydroxyl groups in anthocyanin molecules, disrupting the hydrogen bonds between them and gelatin, and further promoting the movement of the precipitated complex toward dissolution; while 35% ethanol can reduce the hydrophobic aggregation tendency of gelatin molecules, and better inhibit the polymerization reaction of anthocyanins due to protonation, so that gelatin exists in a more stable monodisperse state in the solution, reducing the uneven color reaction caused by molecular aggregation.

[0076] Secondly, 1 mL of a 2 g / L ninhydrin solution was added, which, together with the mixed solution of the colorimetric reagent in Example 1, served as the colorimetric reagent. During the colorimetric reaction in this example, the anthocyanin catechol / pyrogallol groups retained in the gelatin-anthocyanin complex after dissociation by the precipitant and solvent reacted with Fe... 3+ A complexation reaction occurs, forming a stable chelate. Simultaneously, the free amino groups of basic amino acids such as lysine and arginine in the gelatin molecule can undergo a Ruhemann purple color reaction with ninhydrin, ultimately generating a more stable purple-red product. Furthermore, in subsequent ultraviolet detection, the π-π conjugated system of the Ruhemann purple molecule absorbs photons in the 400–700 nm visible light region, undergoing a π→π reaction. Electron transitions; and the "Fe" in gelatin-anthocyanin-ferric chloride chelates 3+ -O- "Coordination bonds undergo dd transitions and charge transfer transitions, which together form a strong absorption band in the 400~700nm range, further enhancing the intensity and stability of the detection signal."

[0077] Example 4

[0078] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0079] The only difference between this embodiment and Embodiment 1 is that in step (S1), the volume of the electrolyte to be tested is changed from 5 mL to 2 mL, and the volume of the mixed solution of anthocyanins and citric acid is changed from 2 mL to 20 mL. At this time, the volume ratio of the electrolyte to be tested to the mixed solution of anthocyanins is changed to 2:20.

[0080] Example 5

[0081] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0082] The only difference between this embodiment and Embodiment 1 is that in step (S1), the volume of the electrolyte to be tested is changed from 5 mL to 30 mL, and the volume of the mixed solution of anthocyanins and citric acid is changed from 2 mL to 5 mL. At this time, the volume ratio of the electrolyte to be tested to the mixed solution of anthocyanins is changed to 30:5.

[0083] Example 6

[0084] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0085] The only difference between this embodiment and Embodiment 1 is that in step (S1), the conditions for the precipitation reaction are changed to ultrasonic dispersion at 35°C using an ultrasonic device with a power of 200W for 20 minutes.

[0086] Example 7

[0087] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0088] The only difference between this embodiment and Embodiment 1 is that in step (S1), the conditions for the precipitation reaction are changed to ultrasonic dispersion for 2 minutes at 35°C using an ultrasonic device with a power of 800W.

[0089] Example 8

[0090] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0091] The only difference between this embodiment and Example 1 is that in step (S2), the concentration of sodium dodecyl sulfate in the precipitant is changed to 5 g / L, and the concentration of triethanolamine is changed to 5 mL / L.

[0092] Example 9

[0093] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0094] The only difference between this embodiment and Example 1 is that in step (S2), the concentration of ferric chloride in the colorimetric reagent is changed to 1 g / L, and the volume of hydrochloric acid is changed to 2 mL, while the volume of acetic acid is changed to 3 mL. The mass concentration of HCl in the hydrochloric acid remains the same as in Example 1.

[0095] Example 10.

[0096] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0097] The only difference between this embodiment and Example 1 is that in step (S2), the concentration of ferric chloride in the colorimetric reagent is changed to 20 g / L, and it does not contain acetic acid. The mass concentration of HCl in the hydrochloric acid remains the same as in Example 1.

[0098] Example 11

[0099] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0100] The only difference between this embodiment and Embodiment 1 is that in step (S2), the temperature of the colorimetric reaction is controlled at 25°C to 35°C.

[0101] Example 12

[0102] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0103] The only difference between this embodiment and Embodiment 1 is that, in the process of determining the strongest absorption wavelength in step (S2), the scanning rate of the UV-Vis spectrophotometer used is changed to 80 nm / min.

[0104] Example 13

[0105] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0106] The only difference between this embodiment and Embodiment 1 is that, in the process of determining the strongest absorption wavelength in step (S2), the scanning rate of the UV-Vis spectrophotometer used is changed to 240 nm / min.

[0107] Example 14

[0108] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0109] The only difference between this embodiment and Embodiment 1 is that in step (S4-1), only a series of standard copper electrolytic electrolytes with gelatin concentrations of 0.01ppm, 100ppm and 1000ppm were prepared, totaling three, and thus the absorbance-gelatin concentration standard curve was obtained.

[0110] Comparative Example 1

[0111] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0112] The only difference between this comparative example and Example 1 is that in step (S1), an anthocyanin solution of equal concentration and volume is used instead of an anthocyanin solution.

[0113] Comparative Example 2

[0114] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0115] The only difference between this comparative example and Example 1 is that, in step (S1), the concentration of anthocyanins in the anthocyanin solution used is changed to 0.1 g / L.

[0116] Comparative Example 3

[0117] A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining:

[0118] The only difference between this comparative example and Example 1 is that, in step (S1), the concentration of anthocyanins in the anthocyanin solution used is changed to 1 g / L.

[0119] Comparative Example 4

[0120] This comparative example uses the gelatin concentration detection method provided in the existing technology CN120142205A.

[0121] Comparative Example 5

[0122] This comparative example uses the gelatin concentration detection method provided in the prior art CN 113466148 A.

[0123] The relative standard deviations (RSDs) of the gelatin concentrations measured in the above embodiments and comparative examples with the actual amount of gelatin added are shown in Table 1.

[0124] Table 1

[0125]

[0126] As can be seen from the above description, compared with the comparative examples, the above embodiments of the present invention, through the combined process of "specific precipitation separation - targeted dissolution - colorimetric reaction - ultraviolet spectrophotometric detection" and the establishment of a standard curve, achieve efficient and accurate determination of gelatin concentration in the electrolyte system used in complex copper electrolytic refining.

[0127] Specifically, in each embodiment:

[0128] Comparing Example 3 with Example 1, it can be seen that by further optimizing the types of colorimetric agents and precipitating solvents, better dissolution and color development can be achieved, thereby obtaining more accurate detection results.

[0129] Comparing Examples 4 and 5 with Example 1, it can be seen that by optimizing the volume ratio of the electrolyte to the anthocyanin solution, the anthocyanin solution can more effectively combine with the gelatin molecules in the electrolyte to form a sufficient amount of complex, thereby further improving the integrity and recovery rate of the precipitation, and ultimately obtaining a more accurate gelatin concentration detection result.

[0130] Comparing Examples 6 and 7 with Example 1, it can be seen that, by example, by optimizing the conditions of the precipitation reaction, it is possible to obtain a more efficient precipitation separation effect while more effectively maintaining the stability of gelatin-containing precipitates, thereby further improving the accuracy and reproducibility of the detection.

[0131] Comparing Example 8 with Example 1, it can be seen that by optimizing the specific composition of the precipitant solvent, the precipitate can be dissolved more efficiently, and more accurate gelatin concentration detection can be achieved.

[0132] Comparing Examples 9 and 10 with Example 1, it can be seen that by optimizing the specific composition of the color-developing agent, Fe can be promoted. 3+ It can bind more fully and stably with gelatin, thereby further improving the sensitivity and accuracy of detection. Comparing Example 11 with Example 1, it can be seen that by optimizing the conditions of the colorimetric reaction, the Fe... 3+ - The stability of the gelatin complex also better maintains the consistency of the colorimetric reaction, ultimately further enhancing the comparability and accuracy of the test results.

[0133] Comparing Examples 12 and 13 with Example 1, it can be seen that in the process of determining the strongest absorption wavelength, by optimizing the scanning rate of the UV-Vis spectrophotometer used, the spectral scan can be completed more quickly within the stability window of the gelatin complex, thereby capturing the optimal absorption peak, reducing the photodegradation or thermal decomposition of the complex that may occur under long-term exposure, and more effectively ensuring the authenticity and validity of the detection results.

[0134] Comparing Example 14 with Example 1, it can be seen that in the process of testing and fitting the standard curve, by selecting more concentration points (specifically 5 concentration points), the linear relationship between absorbance value and gelatin concentration can be better depicted, further improving the goodness of fit of the standard curve, and ultimately significantly improving the accuracy and reliability of concentration calculation.

[0135] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining, characterized in that, include: Step S1: The electrolyte used in the copper electrolytic refining is filtered to obtain the electrolyte to be tested; The electrolyte to be tested was reacted with an anthocyanin solution with a concentration of 0.5±0.05 g / L to obtain a precipitate product. Step S2: Dissolve the precipitate product using a precipitant to obtain a first solution; The first solution reacts with an iron-containing indicator to produce a second solution through a colorimetric reaction. The strongest absorption wavelength of the second solution was detected using a UV-Vis spectrophotometer and denoted as U. Step S3, detect the net absorbance value ΔW: Step S3-1: Within the wavelength range of U±5nm, the absorbance value of the second solution is detected using a UV-Vis spectrophotometer, and the stable absorbance value is recorded as W1. Step S3-2: Prepare a control solution by mixing the same amount of the precipitant dissolving agent as in step S2 and the same amount of the display agent as in step S2; within a wavelength range of U±5nm, use the control solution as a blank sample for background subtraction to obtain the net absorbance value, denoted as ΔW0; Step S4-1: Prepare n standard copper solutions containing gelatin and denote them as solution An; each solution An is reacted with Cu in the electrolyte to be tested. 2+ The concentrations are the same; the gelatin concentration in each of the solutions An is denoted as Pn, and the n Pn are all different and each is independently 0.01ppm~1000ppm; n is 5~10; Step S4-2: Referring to step S3, the net absorbance value ΔW of each solution An is detected and recorded as ΔWn. Based on n Pn and n ΔWn, the absorbance-gelatin concentration standard index equation curve is fitted, and then the gelatin concentration in the electrolyte used for copper electrolytic refining is calculated.

2. The method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining according to claim 1, characterized in that, n is 5, P1 of solution A1 is 0.01ppm~0.012ppm, P2 of solution A2 is 1±0.02ppm, P3 of solution A3 is 10±1ppm, P4 of solution A4 is 100±10ppm, and P5 of solution A5 is 950ppm~1000ppm.

3. The method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining according to claim 1 or 2, characterized in that, In step S1, the Cu in the electrolyte used for copper electrolytic refining 2+ The concentration of SO4 is 40 g / L~60 g / L. 2+ The concentration is 100g / L~200g / L, and the concentration of gelatin is ≤1000ppm.

4. The method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining according to any one of claims 1 to 3, characterized in that, In step S1 The volume ratio of the electrolyte to be tested to the anthocyanin solution is (2~30):(5~20); and / or, The anthocyanin solution also contains a complexing agent with a concentration of 0.5 mol / L to 2.0 mol / L, and the complexing agent is selected from one or more of citric acid, sodium citrate, sodium gluconate, tartaric acid, potassium sodium tartrate, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, and diethanolamine. The precipitation reaction is carried out by ultrasonic treatment at 25℃~35℃, and the ultrasonic treatment power is 300W~500W for 5min~15min; or, the precipitation reaction is carried out by oscillation treatment at 25℃~35℃, and the oscillation treatment rate is 100rpm~300rpm for 5min~15min.

5. The method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining according to any one of claims 1 to 4, characterized in that, In step S1, the filtration is performed using a filter membrane with a pore size of 0.2μm to 0.25μm.

6. The method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining according to any one of claims 1 to 5, characterized in that, In step S2, the precipitant is selected from one of sodium hydroxide solution, sodium chloride solution, weakly alkaline buffer solution, alkaline complexing solution, and ethanol-hydrochloric acid mixture, more preferably the ethanol-hydrochloric acid mixture; Preferably, the weakly alkaline buffer solution is selected from one or more of borax-sodium hydroxide buffer solution, ammonia-ammonium chloride buffer solution, and sodium carbonate-sodium bicarbonate buffer solution; Preferably, the alkaline complexing solution is a sodium dodecyl sulfate-triethanolamine mixture, wherein the concentration of sodium dodecyl sulfate in the sodium dodecyl sulfate-triethanolamine mixture is 10 g / L to 50 g / L, and the concentration of triethanolamine is 10 mL / L to 50 mL / L. Preferably, in the ethanol-hydrochloric acid mixture, the volume fraction of ethanol is 30%~40%, and the concentration of hydrochloric acid is 0.05mol / L~0.3mol / L.

7. The method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining according to any one of claims 1 to 6, characterized in that, In step S2 The colorimetric reagent includes Fe at a concentration of 1 g / L to 15 g / L. 3+ ; and / or, The color developer also includes hydrochloric acid and optional auxiliaries, wherein the auxiliaries are selected from one or more of acetic acid, citric acid, propylene glycol and glycerol; Preferably, the Fe 3+ It exists in the form of potassium ferricyanide, ferric sulfate, ferric chloride, or ferric tribromide; Preferably, the colorimetric reagent includes Fe at a concentration of 10±2 g / L. 3+ ; Preferably, the color developer further includes the hydrochloric acid and the auxiliary agent, and the volume ratio of the hydrochloric acid to the auxiliary agent is (1~5):(0.1~1).

8. The method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining according to any one of claims 1 to 7, characterized in that, In step S2 The dissolution is performed by ultrasonic treatment, wherein the power of the ultrasonic treatment is 300W~500W and the time is 5min~15min; and / or, The colorimetric reaction is carried out at 25℃~35℃, and the temperature fluctuation during the colorimetric reaction is ≤±2℃.

9. The method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining according to any one of claims 1 to 8, characterized in that, In step S2, the photometric repeatability of the UV-Vis spectrophotometer is ≤0.001Abs, the noise is ≤0.0002Abs, and the scanning rate is 100nm / min~200nm / min.

10. The method for detecting the gelatin concentration in the electrolyte used in copper electrolytic refining according to any one of claims 1 to 9, characterized in that, In step S4 Perform at least three parallel tests on each ΔWn and take the average value; The goodness of fit R 2 ≥0.998.

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