Maintenance method of electroplating solution and nickel-based electroplating solution for preparing alkaline electrolytic water hydrogen production electrode

Abstract

According to the maintenance method of the electroplating liquid and the nickel-based electroplating liquid for preparing the alkaline electrolytic water hydrogen production electrode, the electroplating liquid can be recovered to a standard state through reasonably designed steps and a parameter adjusting process, it is ensured that the electroplating process is stably carried out, the service life of the electroplating liquid is prolonged, and meanwhile the replacement cost and the waste liquid discharge amount are reduced. The maintenance method comprises the following steps: analyzing and adjusting the metal main salt concentration of the electroplating solution by combining a titration method, adjusting the concentration of a buffering agent by combining a hydrometer, adjusting the pH value of the solution, retesting and finely adjusting the adjusted electroplating solution, and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of electroplating, and more specifically, to a method for maintaining an electroplating solution and a nickel-based electroplating solution for preparing an electrode for producing hydrogen by alkaline water electrolysis. Background Art

[0002] Electroplating is a process technology that uses electrochemical principles to deposit a layer of metal or alloy film on the surface of an object. It is widely used in the fields of automobiles, electronics, aerospace, and decorative processing. The electroplating solution is usually composed of metal salts, buffers, brighteners, wetting agents, etc. to ensure the quality of the coating and the efficiency of electroplating. However, as the electroplating process continues, the components in the electroplating solution will undergo complex physical and chemical changes, causing its performance to gradually deviate from the initial state, affecting the gloss, hardness, and corrosion resistance of the coating. Therefore, how to maintain the stability of the electroplating solution components has become a key issue affecting the quality and cost control of the electroplating process.

[0003] The electrodes for hydrogen production by alkaline water electrolysis are usually porous metal substrates with nickel-based catalysts electroplated on the surface. Taking nickel-based electroplating solution as an example, the electroplating solution is mainly composed of nickel salts (such as nickel chloride, nickel sulfate or nickel sulfamate) and buffers (such as boric acid or ammonium sulfate). During the coating formation process, the nickel block on the anode will dissolve into nickel ions and enter the solution, while nickel ion reduction deposition occurs at the cathode. However, in addition to the main metal deposition reaction, there are also side reactions at the cathode, including the electrolysis of water to produce hydrogen (HER reaction) and the consumption of buffer cations. For example, in an electroplating solution containing ammonium sulfate, ammonium ions will gradually decrease with the cathode reduction reaction. These side reactions lead to an imbalance in the composition of the electroplating solution, which is manifested as an increase in metal ion concentration, a decrease in buffer concentration, and an increase in pH, which ultimately leads to a decrease in coating quality and an unstable electroplating process.

[0004] There are two main methods for maintaining the traditional plating solution: one is to replace the entire plating solution regularly, and the other is to gradually replenish the missing buffers and acid-base regulators. However, regular replacement of the plating solution not only causes material waste, but also produces a large amount of waste liquid containing heavy metals, which has high treatment costs and pollutes the environment. The gradual replenishment method is difficult to accurately adjust to the ideal range due to the complex composition of the plating solution and the influence of various ion concentrations on each other, resulting in the need to replace the entire solution after long-term use. Therefore, these traditional methods have the disadvantages of high cost, short maintenance cycle, and serious environmental pollution. A more efficient and economical plating solution adjustment method is urgently needed.

[0005] In recent years, in order to solve the problem of electroplating solution maintenance, researchers have proposed some improvement methods, such as using online monitoring equipment to detect the composition of the electroplating solution in real time, and accurately replenishing the composition of the electroplating solution through automatic dosing devices. However, this type of automated equipment is expensive and not suitable for small and medium-sized enterprises. In addition, these devices can often only monitor a single parameter, such as pH or the concentration of a specific metal ion, and it is difficult to balance the changes in multiple components at the same time, resulting in unsatisfactory adjustment effects. Therefore, it is of great industrial application value to develop a technical method that is simple to operate, low-cost, and can simultaneously adjust metal ions, buffers, and pH values ​​in the electroplating solution. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention proposes a maintenance method for an electroplating solution and a nickel-based electroplating solution for preparing an alkaline water electrolysis hydrogen production electrode. Through reasonably designed steps and parameter adjustment processes, the electroplating solution can be restored to a standard state, thereby ensuring a stable electroplating process, extending the service life of the electroplating solution, and reducing replacement costs and waste liquid emissions.

[0007] To achieve the above object, in a first aspect, the present invention provides a method for maintaining an electroplating solution, comprising:

[0008] Step S1, analyzing and adjusting the concentration of the main metal salt in the electroplating solution: by titration, quickly detecting the current concentration of metal ions in the electroplating solution on site, and comparing it with the standard concentration, and restoring the metal ion concentration to the standard range by supplementing the main metal salt solid or extracting the electroplating solution;

[0009] Step S2, adjusting the buffer concentration: first, place the hydrometer in the standard electroplating solution for calibration, and record the hydrometer reading as the reference value; then place the hydrometer in the electroplating tank solution that needs to be adjusted, and then restore the buffer concentration to the standard range by adding buffer solid or extracting the electroplating solution, and adding deionized water;

[0010] Step S3, adjusting the pH value of the solution: using a high concentration acid having the same anion as the main salt to adjust the pH value to a standard range;

[0011] Step S4, retest and fine-tune the adjusted electroplating solution: If there is a deviation between the retest result and the standard electroplating solution concentration, one or more steps of steps S1 to S3 are implemented until all indicators fully meet the process requirements.

[0012] The maintenance method ensures that various parameters are restored to the standard range through a multi-step combination of supplementing reagents or extracting solutions to balance the metal salt concentration, restoring the buffer concentration by a hydrometer method, and controlling the pH value with an acidic regulator, thereby significantly improving the stability of the electroplating solution and the electroplating quality, and avoiding defects such as pinholes, roughness or peeling of the coating.

[0013] Furthermore, in step S1, for the case where the concentration of the main metal salt is reduced, the reduced total metal ion content is calculated by the total volume of the plating tank and the metal ion concentration obtained by titration, and is directly added in solid form for dissolution; for the case where the concentration of the main metal salt is increased, the liquid volume corresponding to the excess metal salt is calculated, and the excess part of the solution is extracted to restore the metal ion concentration to the standard range. The calculation formula for the extracted volume is: extracted volume = total volume × excess concentration / current concentration.

[0014] Furthermore, in step S2, when the buffer concentration decreases, the buffer and deionized water are gradually added so that the reading of the hydrometer gradually approaches the standard value, and the total liquid level is restored to the original volume; when the buffer concentration increases, part of the plating solution is first discharged, and then deionized water is added so that the reading of the hydrometer gradually approaches the standard value, and the total liquid level is restored to the original volume.

[0015] Furthermore, the situation where the concentration of the main metal salt decreases includes the situation where the electroplating tank uses an insoluble anode including but not limited to a titanium plate and graphite; the situation where the concentration of the main metal salt increases includes the situation where the electroplating tank uses a soluble anode.

[0016] Furthermore, the electroplating solution is a nickel-based electroplating solution; the main metal salt includes nickel sulfamate and nickel sulfate; and the buffer is ammonium sulfate.

[0017] Furthermore, the high concentration acid in step S3 is a 10% sulfuric acid solution.

[0018] Furthermore, the electroplating solution is a copper-based electroplating solution or a zinc-based electroplating solution.

[0019] In a second aspect, the present invention provides a nickel-based electroplating solution for preparing an alkaline water electrolysis hydrogen production electrode, and the nickel-based electroplating solution is maintained using the electroplating solution maintenance method as described above.

[0020] Compared with the prior art, the present invention has the following technical effects:

[0021] (1) The method of the present invention is simple and easy to operate, does not require complex equipment or expensive analytical instruments, and can complete the adjustment process of the electroplating solution by relying only on conventional detection tools (such as a hydrometer and a pH meter), thereby reducing maintenance costs and technical barriers, and is suitable for large-scale production and application in small and medium-sized enterprises.

[0022] (2) The method of the present invention ensures that various parameters are restored to the standard range through a multi-step combination of solution extraction to balance the metal salt concentration, hydrometer method to restore the buffer concentration, and acidic regulator to control the pH value, thereby significantly improving the stability of the electroplating solution and the electroplating quality, and avoiding defects such as pinholes, roughness or peeling of the coating.

[0023] (3) The present invention can effectively extend the service life of the electroplating solution and reduce the need for frequent replacement of the electroplating solution, thereby reducing the cost of raw materials and waste liquid treatment, while reducing the amount of waste liquid discharged, which meets the requirements of green manufacturing and environmental protection.

[0024] (4) This method has a wide range of applications. It is not only suitable for nickel-based electroplating solution systems, but can also be extended to other systems such as copper-based electroplating solution and zinc-based electroplating solution. It has good versatility and industrial promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a flow chart of a method for maintaining electroplating solution in one embodiment of the present invention.

[0026] Figure 2 Schematic diagram of the operation of the electroplating solution maintenance process in one embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0028] The execution order of actions, steps, etc. in the devices and methods shown in the claims, specifications and drawings can be implemented in any order as long as there is no special explicit limitation on the order and as long as the output of the previous processing is not used in the subsequent processing.

[0029] Example 1

[0030] See also Figure 1 This embodiment provides a method for maintaining an electroplating solution, comprising the following specific steps:

[0031] S1. Analyze and adjust the concentration of the main metal salt in the electroplating solution.

[0032] Through the titration method, the current concentration of metal ions in the plating solution can be quickly detected on site and compared with the standard concentration.

[0033] (1) When the concentration of the main metal salt decreases

[0034] Reasons for the decrease in the concentration of metal main salts:

[0035] During the electroplating process, if an insoluble anode (such as titanium plate, graphite, etc.) is used, the anode will undergo an oxidation reaction of the anions in the solution (such as chlorine evolution, oxygen evolution, etc.), while the cathode will mainly undergo a metal ion reduction reaction, which will cause the metal salt concentration to gradually decrease.

[0036] Solutions to reduce the concentration of main metal salts:

[0037] The reduced total metal ion content is calculated by the total volume of the plating tank and the metal ion concentration obtained by titration and is directly added in solid form to dissolve.

[0038] (2) For situations where metal ion concentration increases:

[0039] Reasons for the increase in the concentration of metal main salts:

[0040] In the electroplating process, if a soluble anode (such as nickel plate, nickel particles, etc.) is used, the anode will undergo an oxidation reaction of metal ions (such as nickel metal oxidizing to nickel ions), and the cathode will undergo other competitive reactions (such as hydrogen precipitation, etc.) in addition to the reduction reaction of metal ions. This situation will cause the concentration of the main metal salt to gradually increase.

[0041] Solutions to increased concentration of metal main salts:

[0042] By calculating the liquid volume corresponding to the excess metal salt, the excess solution is extracted to restore the metal ion concentration to the standard range.

[0043] The specific calculation formula is as follows: Extraction volume = total volume × excess concentration / current concentration.

[0044] For example, in a standard electroplating solution, the initial concentration of nickel sulfamate is 200 g / L and the total volume is 3000 L. After a period of use, the concentration rises to 210 g / L. According to the above formula, 3000 × (10 / 210) = 143 L of solution needs to be extracted to restore the metal salt concentration to 200 g / L.

[0045] S2. Adjust the buffer concentration.

[0046] The salt content of the buffer cannot generally be measured by chemical calibration methods, so this embodiment uses a hydrometer method to restore the buffer concentration.

[0047] (1) When the buffer concentration is reduced

[0048] Reasons for decreased buffer concentration:

[0049] Since the cations in the buffer (such as ammonium ions in ammonium sulfate) are consumed in the cathode reaction during the electroplating process, the buffer concentration gradually decreases, affecting the buffering capacity and conductivity of the electroplating solution.

[0050] Solution for reduced buffer concentration:

[0051] First, prepare a standard plating solution in the laboratory, place the hydrometer in the standard solution for calibration, and record the hydrometer reading as the baseline value. Then place the hydrometer in the plating tank solution that needs to be adjusted, and gradually add buffers (such as ammonium sulfate) and deionized water to gradually bring the hydrometer reading close to the standard value, and ensure that the total liquid level returns to the original volume.

[0052] For example, if the hydrometer reading of the standard solution is 1.25 g / cm³, and the specific gravity of the solution in the electroplating tank is 1.28 g / cm³, it means that the buffer concentration is too high, then gradually add deionized water to dilute it; on the contrary, if the specific gravity is too low, then gradually add buffer until the specific gravity returns to the standard value. This adjustment method is simple and easy, and can accurately restore the buffer concentration without the need for complex testing equipment.

[0053] (2) When the buffer concentration increases

[0054] Reasons for increased buffer concentration:

[0055] The plating solution is left for a long time, causing the water to evaporate, or the same components as the buffer are introduced during electroplating.

[0056] Solutions for increased buffer concentration:

[0057] First, prepare a standard plating solution in the laboratory, place the hydrometer in the standard solution for calibration, and record the hydrometer reading as the reference value. Then place the hydrometer in the plating tank solution that needs to be adjusted, drain part of the plating solution first, and then add deionized water to make the hydrometer reading gradually approach the standard value, and ensure that the total liquid level returns to the original volume.

[0058] S3. Adjust the pH value of the solution.

[0059] During the electroplating process, due to the consumption of hydrogen ions, the pH value of the solution will gradually increase, affecting the deposition rate of metal ions and the quality of the coating. The present invention uses a high-concentration acid with the same anion as the main salt to adjust the pH value to the standard range. For example, when the standard pH value is 3.5-4.5, if the pH value of the electroplating solution is detected to be high at 4.8, sulfuric acid is slowly added dropwise, and a pH meter is used to monitor the changes in real time until the pH value of the solution returns to 4.0. The choice of acid in the present invention matches the main salt to ensure that the ion balance of the solution is not destroyed, while avoiding the introduction of other unnecessary impurities, further ensuring the stability and consistency of the electroplating solution. The high-concentration acid ensures that the total volume of the solution is not changed as much as possible.

[0060] S4. Retest and fine-tune the adjusted electroplating solution.

[0061] After completing the above steps, retest the metal ion concentration, buffer concentration and pH value in the plating solution to ensure that all indicators are restored to the standard range. If there is a deviation in the test results, further fine-tuning can be done by adding or diluting the solution in small amounts until all indicators fully meet the process requirements. For example, the metal ion concentration is tested by titration, the buffer concentration is verified by the hydrometer method, and the pH value is tested using a precision pH meter to ensure that the adjustment results are accurate and reliable.

[0062] See also Figure 2 The concentration adjustment of nickel sulfamate electroplating solution is taken as a typical example to illustrate the implementation process of the present invention.

[0063] 1. Experimental conditions:

[0064] Electroplating solution composition: 200 g / L nickel sulfamate, 100 g / L nickel sulfate, 50 g / L ammonium sulfate.

[0065] Electroplating tank capacity: 3000 L.

[0066] The test results after one production cycle were: nickel sulfamate 210 g / L, nickel sulfate 105 g / L, and the ammonium sulfate concentration could not be titrated on site and was unknown.

[0067] 2. Adjust the metal salt concentration.

[0068] (1) The actual concentrations of nickel sulfamate and nickel sulfate in the plating solution were measured and compared with the standard concentrations. It was found that nickel sulfamate exceeded 10 g / L and nickel sulfate exceeded 5 g / L.

[0069] (2) Calculate the volume of solution that needs to be extracted to restore the metal salt concentration:

[0070] Nickel sulfamate and nickel sulfate adjustment:

[0071] V 抽取 = 3000 × (10 / 210) = 143L

[0072] (3) After extracting 143 L of solution, the metal salt concentration in the remaining solution returned to the standard value.

[0073] 3. Buffer concentration is restored.

[0074] (1) Using the laboratory-prepared standard plating solution, the standard reading of the hydrometer is 1.25 g / cm³.

[0075] (2) The hydrometer was placed in the electroplating tank solution and the specific gravity was measured to be 1.22 g / cm³, indicating that the concentration of the buffer (ammonium sulfate) was low.

[0076] (3) Gradually add ammonium sulfate and deionized water while observing the changes in the hydrometer reading.

[0077] (4) When the hydrometer reaches 1.25 g / cm³ and the total liquid level returns to 3000 L, the buffer concentration adjustment is considered complete.

[0078] 4. Adjust pH value.

[0079] (1) The pH value of the plating solution was measured using a pH meter and was found to be 4.8, which was slightly higher than the standard value (3.5-4.5).

[0080] (2) Slowly add 10% sulfuric acid solution while stirring and monitoring the pH change in real time.

[0081] (3) When the pH value is adjusted to 4.0, stop adding sulfuric acid to complete the pH adjustment.

[0082] 5. Verification and fine-tuning.

[0083] (1) Re-test the metal salt concentration, buffer concentration and pH value.

[0084] (2) The measured nickel sulfamate was 200 g / L, the nickel sulfate was 100 g / L, the pH value was 4.0, and the hydrometer showed 1.25 g / cm³, all of which met the standard requirements.

[0085] (3) If the deviation of a certain parameter exceeds the allowable range, further adjustment can be made by trace addition or dilution.

[0086] As a comparative example, if the concentration of the above-mentioned nickel sulfamate electroplating solution is adjusted by first adjusting the buffer concentration and pH value to reach the standard value, and then adjusting the concentration of the main metal salt, if the main metal salt concentration is measured to be too high, the corresponding solution volume must be discharged to reduce the main salt concentration. At this time, part of the buffer component is also discharged, and the buffer needs to be replenished, which makes the process complicated and wastes materials.

[0087] Example 2

[0088] This embodiment provides a nickel-based electroplating solution for preparing an alkaline water electrolysis hydrogen production electrode, and the nickel-based electroplating solution is maintained using the electroplating solution maintenance method described in Example 1.

[0089] As an example, the main metal salts of the nickel-based electroplating solution are nickel sulfamate and nickel sulfate, the buffer is ammonium sulfate, and the electroplating solution is maintained using the concentration adjustment method described in Example 1.

[0090] In summary, the present invention provides a maintenance method for an electroplating solution and a nickel-based electroplating solution for preparing an alkaline water electrolysis hydrogen production electrode. Through reasonably designed steps and parameter adjustment processes, the electroplating solution can be restored to a standard state, ensuring that the electroplating process is stable, extending the service life of the electroplating solution, and reducing replacement costs and waste liquid discharge. The maintenance method includes analyzing and adjusting the concentration of the main metal salt of the electroplating solution in combination with a titration method, adjusting the concentration of the buffer in combination with a hydrometer, adjusting the pH value of the solution, and retesting and fine-tuning the adjusted electroplating solution.

[0091] Those skilled in the art should understand that those skilled in the art can implement variations by combining the prior art and the above embodiments, which will not be described in detail here. Such variations do not affect the essential content of the present invention, and will not be described in detail here.

[0092] The above describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the systems and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes, which does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention are still within the scope of protection of the technical solutions of the present invention.

Claims

1. A method for maintaining an electroplating solution, characterized in that: include: Step S1, analyzing and adjusting the concentration of the main metal salt in the electroplating solution: by titration, quickly detecting the current concentration of metal ions in the electroplating solution on site, and comparing it with the standard concentration, and restoring the metal ion concentration to the standard range by supplementing the main metal salt solid or extracting the electroplating solution; Step S2, adjusting the buffer concentration: first, place the hydrometer in the standard electroplating solution for calibration, and record the hydrometer reading as the reference value; then place the hydrometer in the electroplating tank solution that needs to be adjusted, and then restore the buffer concentration to the standard range by adding buffer solid or extracting the electroplating solution, and adding deionized water; Step S3, adjusting the pH value of the solution: using a high concentration acid having the same anion as the main salt to adjust the pH value to a standard range; Step S4, retest and fine-tune the adjusted electroplating solution: If there is a deviation between the retest result and the standard electroplating solution concentration, one or more steps of steps S1 to S3 are implemented until all indicators fully meet the process requirements.

2. The method for maintaining the electroplating solution according to claim 1, characterized in that: In the step S1, when the concentration of the main metal salt is reduced, the reduced total metal ion content is calculated by the total volume of the plating tank and the metal ion concentration obtained by titration, and the metal ion is directly added in solid form for dissolution; when the concentration of the main metal salt is increased, the liquid volume corresponding to the excess metal salt is calculated, and the excess part of the solution is extracted to restore the metal ion concentration to the standard range. The calculation formula for the extracted volume is: extracted volume = total volume × excess concentration / current concentration.

3. The method for maintaining the electroplating solution according to claim 1 or 2, characterized in that: In step S2, when the buffer concentration decreases, the buffer and deionized water are gradually added to make the hydrometer reading gradually approach the standard value, and the total liquid level is restored to the original volume; when the buffer concentration increases, part of the plating solution is first discharged, and then deionized water is added to make the hydrometer reading gradually approach the standard value, and the total liquid level is restored to the original volume.

4. The method for maintaining the electroplating solution according to claim 2, characterized in that: The situation where the concentration of the main metal salt is reduced includes the case where the electroplating tank uses an insoluble anode including but not limited to titanium plate and graphite; the situation where the concentration of the main metal salt is increased includes the case where the electroplating tank uses a soluble anode.

5. The method for maintaining the electroplating solution according to claim 3, characterized in that: The electroplating solution is a nickel-based electroplating solution; the main metal salt includes nickel sulfamate and nickel sulfate, and the buffer is ammonium sulfate.

6. The method for maintaining the electroplating solution according to claim 5, characterized in that: The high concentration acid in step S3 is a 10% sulfuric acid solution.

7. The method for maintaining the electroplating solution according to claim 3, characterized in that: The electroplating solution is a copper-based electroplating solution or a zinc-based electroplating solution.

8. A nickel-based electroplating solution for preparing an alkaline water electrolysis hydrogen production electrode, characterized in that: The nickel-based electroplating solution is maintained using the electroplating solution maintenance method as described in any one of claims 1 to 6.

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