Method and device for evaluating performance of scale inhibitor based on electrochemical impedance spectroscopy

Abstract

This application discloses a method and apparatus for evaluating the performance of scale inhibitors based on electrochemical impedance spectroscopy. The method includes: adding the scale inhibitor to be evaluated to a prepared simulated circulating cooling water to obtain a water sample; performing electrochemical impedance spectroscopy scanning on the water sample to extract electrical parameters under the initial state; performing dynamic concentration treatment on the water sample to continuously increase the ion concentration at a preset rate; acquiring impedance spectrum sequences at fixed intervals under different concentration ratios; performing equivalent circuit fitting on the impedance spectrum sequences to extract electrical parameters under different concentration ratios; plotting a degradation curve and determining the concentration ratio corresponding to the inflection point as the critical failure concentration ratio of the scale inhibitor to be evaluated. This application simulates the continuous enrichment of salt through a dynamic concentration process, combined with EIS multi-parameter tracking and inflection point detection, to quantify the tolerance limit of the scale inhibitor using the critical failure concentration ratio, achieving rapid, multi-dimensional, quantitative, and comparable performance evaluation.

Description

Technical Field

[0001] This application relates to the field of water treatment agent performance evaluation technology, and in particular to a method and apparatus for evaluating the performance of scale inhibitors based on electrochemical impedance spectroscopy. Background Technology

[0002] In circulating cooling water systems of industrial sectors such as thermal power plants, chemical plants, and data centers, the concentration ratio of the water continuously increases, leading to salt accumulation and exacerbating scaling, which seriously affects heat exchange efficiency and equipment safety. Adding scale inhibitors is one of the most economical and effective means of controlling scaling. However, with increasing requirements for energy conservation and emission reduction, circulating cooling water systems tend to operate at high concentration ratios, which places higher demands on the performance durability and tolerance limits of scale inhibitors under high salt stress.

[0003] In related technologies, dynamic simulation and rapid electrochemical indexing methods are employed. The dynamic simulation method involves constructing a dynamic simulation device to reproduce the hydraulic, thermal, and concentration conditions of a circulating cooling water system, causing metal samples to scale under conditions similar to actual industrial environments. Electrochemical impedance spectroscopy (EIS) is used to periodically monitor the electrochemical response at the metal / solution interface, and scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are used after the experiment to characterize the scale morphology and composition. However, this method suffers from problems such as extremely long experimental cycles, complex operation, high cost, poor repeatability, and the need for comprehensive evaluation results, making it difficult to elucidate the microscopic mechanisms.

[0004] The electrochemical rapid index method utilizes the characteristic that the interfacial impedance increases significantly after scale inhibitors form a film on the metal surface, using the low-frequency impedance modulus as the core quantitative indicator. However, this method suffers from problems such as a single evaluation dimension, severe information loss, inability to assess performance degradation under continuous salt accumulation, and inability to distinguish the mechanism of action of scale inhibitors.

[0005] In summary, existing methods suffer from problems such as long evaluation cycles, limited evaluation dimensions, and neglect of long-term performance evolution. They are unable to evaluate the performance of scale inhibitors under conditions of continuous salt enrichment and even extreme concentration. Summary of the Invention

[0006] This disclosure provides a method and apparatus for evaluating the performance of scale inhibitors based on electrochemical impedance spectroscopy, in order to at least solve the above-mentioned technical problems existing in the prior art.

[0007] According to a first aspect of this application, a method for evaluating the performance of scale inhibitors based on electrochemical impedance spectroscopy is provided, the method comprising:

[0008] The scale inhibitor to be evaluated was added to the prepared simulated circulating cooling water to obtain the water sample to be tested;

[0009] Electrochemical impedance spectroscopy was performed on the water sample to be tested to obtain the impedance spectrum and extract the electrical parameters of the impedance spectrum in the initial state.

[0010] The water sample to be tested is subjected to dynamic concentration treatment, so that the ion concentration in the water sample to be tested continues to rise at a preset rate.

[0011] The current concentration ratio of the water sample to be tested is acquired in real time. Concentration is paused and the water sample to be tested is stabilized at fixed concentration ratio increments. Then, the water sample to be tested is scanned with full-frequency electrochemical impedance spectroscopy to obtain impedance spectrum sequences at different concentration ratios.

[0012] Equivalent circuit fitting was performed on the impedance spectrum sequences at each concentration factor to extract the electrical parameters at different concentration factors.

[0013] Based on the electrical parameters under the initial state and the electrical parameters at different concentration ratios, degradation curves of electrochemical parameters as a function of concentration ratio were plotted.

[0014] The inflection point of the degradation curve is detected, and the concentration ratio corresponding to the inflection point is determined as the critical failure concentration ratio of the scale inhibitor to be evaluated.

[0015] In one possible implementation, the electrical parameters include at least:

[0016] Charge transfer resistance, film resistance, and indices of constant phase angle elements in films; among which,

[0017] The charge transfer resistor is used to characterize the degree to which the charge transfer process at the electrode / solution interface is affected by scale deposition;

[0018] The film resistance is used to characterize the ability of the scale layer or scale inhibitor adsorption film on the electrode surface to hinder the interfacial mass transfer process.

[0019] The constant phase angle element index of the film layer is used to characterize the uniformity and density of the scale surface.

[0020] In one embodiment, the dynamic concentration process employs either constant-temperature heating evaporation or constant-current electrolysis.

[0021] The constant temperature heating evaporation method includes:

[0022] Place the water sample to be tested into the reaction vessel;

[0023] The reaction vessel is placed in a constant temperature heating device, so that the water sample to be tested is heated at a preset temperature to evaporate the water.

[0024] During the heating process, a water bath is used for uniform heating and the water sample to be tested is magnetically stirred to maintain the spatial uniformity of solution temperature and ion concentration.

[0025] The constant current electrolysis method includes:

[0026] The inert electrodes, serving as both anode and cathode, are immersed in the water sample to be tested.

[0027] Electrolysis is performed on the water sample to be tested by applying a constant current density, so that the anode of the water sample undergoes an oxygen evolution reaction that consumes water molecules and generates hydrogen ions, and the cathode undergoes a hydrogen evolution reaction that consumes water molecules.

[0028] In one possible implementation, the real-time acquisition of the current concentration ratio of the water sample to be tested includes: real-time measurement of the conductivity of the water sample to be tested, and calculation using the conductivity, or real-time weighing of the mass of the water sample to be tested, and calculation using the mass.

[0029] The process includes real-time measurement of the conductivity of the water sample to be tested, and calculation using the conductivity, including:

[0030] The current conductivity value of the water sample to be tested is measured in real time using a conductivity electrode;

[0031] Based on the initial conductivity value and the current conductivity value of the water sample to be tested, the current concentration ratio of the water sample to be tested is calculated.

[0032] The real-time weighing of the water sample to be tested, and the calculation using the mass, include:

[0033] The total mass of the reaction vessel and the water sample to be tested was weighed using a balance.

[0034] Based on the initial mass and current mass of the water sample to be tested, the current concentration ratio of the water sample to be tested is calculated.

[0035] In one embodiment, the impedance spectrum sequence at each concentration factor is fitted with an equivalent circuit using the complex nonlinear least squares method.

[0036] The equivalent circuit structure includes: a parallel branch consisting of solution resistance, film resistance and film constant phase angle element, and a parallel branch consisting of charge transfer resistance and double layer constant phase angle element connected in series.

[0037] Among them, solution resistance characterizes the ohmic resistance of the bulk solution between the working electrode and the reference electrode, film resistance is used to quantify the hindering effect of scale or adsorption film on interfacial mass transfer, film constant phase angle element is used to describe the capacitive behavior of scale as a dielectric layer, charge transfer resistance reflects the ease of charge transfer process at the electrode / solution interface, and double layer constant phase angle element is used to describe the capacitive behavior of the double layer at the metal / solution interface.

[0038] When a 45-degree straight line segment appears in the low-frequency region of the impedance spectrum, i.e., a diffusion characteristic, a diffusion element is added to the equivalent circuit, and the equivalent circuit is expanded to a parallel branch of solution resistance, film resistance and film constant phase angle element, and a parallel branch of charge transfer resistance, double layer constant phase angle element and diffusion element connected in series.

[0039] In one embodiment, a degradation curve is plotted with the concentration factor on the x-axis and the values ​​of each electrochemical parameter on the y-axis.

[0040] In one possible implementation, detecting the inflection point of the degradation curve includes:

[0041] The determination shall be made by at least two of the following methods: the slope change rate method, the second derivative zero point method, and the exponential step change criterion of constant phase angle element of film layer;

[0042] The method of detecting the inflection point of the degradation curve using the slope change rate method includes:

[0043] The degradation curve is smoothed.

[0044] Calculate the slope of the smoothed degradation curve at each point;

[0045] Calculate the rate of change of the slope;

[0046] The inflection point of the degradation curve is defined as the point where the absolute value of the rate of change of the slope is the maximum value.

[0047] The inflection point of the degradation curve is detected using the second derivative zero-point method, including:

[0048] Take the second derivative of the degradation curve;

[0049] The inflection point is the point where the second derivative of the degradation curve crosses zero.

[0050] The inflection point of the degradation curve is detected by an exponential step abrupt change using a constant phase angle element of the film layer, including:

[0051] Calculate the change in the exponent of the constant phase angle element of the film layer between adjacent concentration ratio points;

[0052] When two consecutive changes are both negative and their absolute values ​​both exceed the first preset value, or when the absolute value of a single change exceeds the second preset value, it is determined that a significant change has occurred.

[0053] The inflection point is defined as the data point preceding the first significant mutation.

[0054] The x-coordinate value corresponding to the inflection point is taken as the critical failure concentration factor.

[0055] In one possible implementation, determining the concentration ratio corresponding to the inflection point as the critical failure concentration ratio of the scale inhibitor to be evaluated includes:

[0056] Under the same conditions, obtain at least three experimental critical failure concentration ratio values;

[0057] Calculate the average and standard deviation of the critical failure concentration ratio values ​​from the three tests;

[0058] When the critical failure concentration ratio value of the test deviates from the average value by more than three times the standard deviation, it is judged as an outlier and removed; among them, the number of valid tests after removal is greater than or equal to three.

[0059] Different scale inhibitors were ranked in descending order of performance based on their average critical failure concentration ratio.

[0060] In one possible implementation, the method further includes: after each electrochemical impedance spectroscopy scan, verifying the data validity of the obtained impedance spectrum, including:

[0061] The impedance spectrum was subjected to Nyquist plot integrity verification, high-frequency scattering threshold verification, and Kramers-Kronig consistency verification.

[0062] If any verification fails, the current scan data is deemed invalid and re-acquired.

[0063] According to a second aspect of this application, a scale inhibitor performance evaluation device based on electrochemical impedance spectroscopy is provided, the device comprising:

[0064] The configuration module is used to add the scale inhibitor to be evaluated to the configured simulated circulating cooling water to obtain the water sample to be tested.

[0065] The scanning module is used to perform electrochemical impedance spectroscopy scanning on the water sample to be tested, obtain the impedance spectrum, and extract the electrical parameters of the impedance spectrum in the initial state.

[0066] The concentration module is used to dynamically concentrate the water sample to be tested, so that the ion concentration in the water sample to be tested continues to rise at a preset rate.

[0067] The acquisition module is used to acquire the current concentration ratio of the water sample to be tested in real time. After pausing the concentration and stabilizing the water sample with a fixed concentration ratio increment, the module performs a full-frequency electrochemical impedance spectroscopy scan on the water sample to be tested to acquire impedance spectrum sequences at different concentration ratios.

[0068] The fitting module is used to perform equivalent circuit fitting on the impedance spectrum sequences at each concentration factor to extract the electrical parameters at different concentration factors.

[0069] The plotting module is used to plot the degradation curves of electrochemical parameters as a function of concentration ratio, based on the electrical parameters in the initial state and the electrical parameters at different concentration ratios.

[0070] The determination module is used to detect the inflection point of the degradation curve and determine the concentration ratio corresponding to the inflection point as the critical failure concentration ratio of the scale inhibitor to be evaluated.

[0071] According to a third aspect of this application, an electronic device is provided, comprising: at least one processor;

[0072] and a memory communicatively connected to the at least one processor; wherein,

[0073] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the method described in this application.

[0074] According to a fourth aspect of this application, a non-transitory computer-readable storage medium is provided storing computer instructions for causing the computer to perform the methods described in this application.

[0075] According to a fifth aspect of this application, a computer program product is provided, comprising a computer program or instructions that, when executed by a processor, implement the method described in this application.

[0076] By utilizing the technical solution of this application, the continuous enrichment of salt is simulated through a dynamic concentration process. Combined with EIS multi-parameter tracking and inflection point detection, the tolerance limit of the scale inhibitor is quantified by the critical failure concentration ratio, thereby achieving rapid, multi-dimensional, quantitative, and comparable performance evaluation.

[0077] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0078] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which:

[0079] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0080] Figure 1 A schematic diagram illustrating the implementation process of the scale inhibitor performance evaluation method based on electrochemical impedance spectroscopy in the embodiments of this application is shown.

[0081] Figure 2 A schematic diagram of the equivalent circuit in an embodiment of this application is shown;

[0082] Figure 3 The typical scale inhibitor degradation curve and CRCC inflection point diagram of the embodiments of this application are shown;

[0083] Figure 4 This paper shows a block diagram of the implementation of the scale inhibitor performance evaluation device based on electrochemical impedance spectroscopy in an embodiment of this application;

[0084] Figure 5 A schematic diagram of the composition structure of the electronic device in an embodiment of this application is shown. Detailed Implementation

[0085] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0086] In the following description, the terms "first" and "second" are used merely to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first" and "second" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0087] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0088] The following description, in conjunction with the accompanying drawings, introduces a method and apparatus for evaluating the performance of scale inhibitors based on electrochemical impedance spectroscopy, provided in this application.

[0089] like Figure 1 As shown, this application provides a method for evaluating the performance of scale inhibitors based on electrochemical impedance spectroscopy, the method comprising:

[0090] S101, add the scale inhibitor to be evaluated to the prepared simulated circulating cooling water to obtain the water sample to be tested.

[0091] In this step, firstly, simulated circulating cooling water containing scale-forming ions such as Ca²⁺ and HCO⁻ is prepared. Then, the scale inhibitor to be evaluated is added to the simulated circulating cooling water. After the scale inhibitor is fully dissolved and stabilized, the water sample to be tested is obtained.

[0092] Scale inhibitors are water treatment agents that can inhibit the crystallization, deposition, and adhesion of sparingly soluble salts in water. They mainly reduce the risk of scale formation, such as calcium carbonate and calcium sulfate, through lattice distortion, adsorption dispersion, and complexation. In circulating cooling water systems, scale inhibitors can increase the system's concentration ratio, reduce wastewater discharge, and improve water resource utilization efficiency.

[0093] S102, perform electrochemical impedance spectroscopy scanning on the water sample to be tested, obtain the impedance spectrum, and extract the electrical parameters of the impedance spectrum in the initial state.

[0094] In this step, the water sample to be tested is placed in a three-electrode system, which includes a working electrode made of titanium alloy or stainless steel, a reference electrode made of saturated calomel electrode, and an auxiliary electrode made of platinum. At room temperature and open circuit potential, a first full-frequency electrochemical impedance spectroscopy scan is performed on the water sample, with a scan frequency range of 0.01 Hz to 100 kHz and an AC perturbation signal amplitude of 10 mV. The initial impedance spectrum is recorded as a reference. The electrical parameters of the impedance spectrum in its initial state are then extracted.

[0095] Electrochemical impedance spectroscopy (EIS) is an electrochemical testing method that analyzes the properties of electrode interfaces by applying a small-amplitude AC perturbation signal and measuring the changes in the system's response signal. This method can obtain parameters such as solution resistance, interfacial film resistance, and charge transfer resistance, and can be used to study the changes in corrosion product layers, scale deposits, and scale inhibitor protective films formed during the contact between metals and cooling water.

[0096] In the three-electrode system of this application, the working electrode is made of industrial pure titanium TA1 or 304 stainless steel as the substrate, and is processed into a cylindrical shape with an exposed bottom working surface area of ​​0.5~1.0 mm. The electrode is cm², with sides and back encapsulated by PTFE or epoxy resin to ensure that only the working surface comes into contact with the solution. Before use, it is polished sequentially with 400#, 800#, 1200#, and 2000# metallographic sandpaper, with each polishing direction perpendicular to the previous one to eliminate scratches. Then, it is polished to a mirror finish on a polishing cloth with alumina polishing paste with a particle size of 0.3μm and 0.05μm, so that the surface roughness Ra≤0.05μm. After polishing, it is ultrasonically cleaned for 5 minutes each in deionized water, anhydrous ethanol, and deionized water. Finally, it is dried with high-purity nitrogen and immediately immersed in the test solution. The above pretreatment process must be repeated before each test to ensure the consistency of the surface condition. TA1 titanium alloy is the preferred material for the working electrode because its corrosion resistance is better than that of stainless steel and it is more suitable for high concentration ratio simulated water systems containing chloride ions and scale-forming ions. In this application, the reference electrode is a saturated calomel electrode, silver electrode, or silver chloride electrode, placed in a Luggin capillary tube with the capillary tip 2-5 mm from the surface of the working electrode to reduce the interference of solution resistance on potential control. Before use, the liquid level inside the reference electrode and the filling state of the saturated potassium chloride solution must be checked to ensure a smooth liquid junction. The auxiliary electrode is a platinum sheet electrode with a purity ≥99.95%, placed parallel to and directly opposite the working electrode with a spacing of 10-15 mm to ensure a uniform electric field distribution.

[0097] The EIS scanning parameters in this application are set based on the following:

[0098] The scanning frequency range is set to 0.01 Hz to 100 kHz. This is because the upper limit of 100 kHz ensures the capture of high-frequency responses of solution resistance and film capacitance, while the lower limit of 0.01 Hz allows for the acquisition of low-frequency information on charge transfer and diffusion processes. If a complete diffusion arc has not yet appeared in the low-frequency region within the scanning time, the lower limit can be extended to 0.001 Hz. However, attention should be paid to the impact of extended testing time on the stability of the solution state. In this application, the amplitude of the AC disturbance signal is set to 10 mV, which is sufficient to ensure both the signal-to-noise ratio and that the system response is within the linear range. For high concentration ratio systems, the amplitude can be further reduced to 5 mV to verify the linear response. In this application, the sampling density adopts a logarithmically evenly spaced distribution, with 10 frequency points collected every ten octaves, achieving a balance between ensuring spectral resolution and controlling the test duration. EIS testing is performed at open circuit potential without applying DC bias potential. The open circuit potential value is recorded before each scan to ensure that fluctuations during the test are within the preset range; otherwise, the scan is performed only after the open circuit potential has stabilized.

[0099] S103, the water sample to be tested is subjected to dynamic concentration treatment, so that the ion concentration in the water sample to be tested continues to rise at a preset rate.

[0100] This step allows for dynamic concentration of the water sample using various treatment methods. The dynamic concentration process removes water while retaining scale-forming ions such as Ca²⁺ and HCO₃⁻, thus gradually increasing the ion concentration. In this application, the concentration rate can be controlled to approximately 0.1 times per hour by adjusting the heating temperature, gas-liquid interface area, and the liquid surface purging gas flow rate.

[0101] S104, the current concentration ratio of the water sample to be tested is obtained in real time. Concentration is paused and the water sample to be tested is stabilized at fixed concentration ratio increments. Then, the water sample to be tested is scanned with full-frequency electrochemical impedance spectroscopy to obtain impedance spectrum sequences at different concentration ratios.

[0102] In this step of the dynamic concentration process, the current concentration ratio can be monitored using various methods. When the concentration ratio increases by a fixed increment preset factor compared to the previous test point, such as 0.5 times, a pause command is automatically issued, the heating power is turned off, and the purge airflow is stopped. The water sample is allowed to stand and stabilize for 5 minutes under constant temperature conditions, with the open circuit potential change rate ≤1 mV / min as the stabilization criterion. After the stabilization period, a full-frequency EIS scan is performed on the water sample to obtain the impedance spectrum data at the concentration ratio. After the scan is completed, heating is resumed, the dynamic concentration process is restarted, and the temperature continues to rise until the next target concentration ratio increment is reached. Concentration is then paused again, and the above scanning operation is repeated. This cycle is repeated to obtain the impedance spectrum sequence at each concentration ratio point: COC = 1.0 (initial), 1.5, 2.0, 2.5... until the scale inhibitor fails. Throughout the process, the open circuit potential is recorded before and after each scan to ensure that the open circuit potential fluctuation during the scan does not exceed ±3 mV; otherwise, the data is considered invalid and re-acquired.

[0103] Specifically, this application employs an intermittent timing control strategy to ensure effective coordination between EIS scanning and the concentration process. First, the concentration process is initiated. Once the solution temperature reaches the set value and stabilizes, continuous evaporation or electrolytic concentration begins. During concentration, the concentration ratio is monitored in real time. When the concentration ratio reaches the preset target increment, the control system immediately issues a pause command, stopping heating or electrolysis and shutting off the purge airflow. This allows the water sample to stabilize under constant temperature conditions for 3-5 minutes, eliminating local concentration gradients and temperature fluctuations caused by evaporation or electrolysis, ensuring the solution reaches a uniform equilibrium state, and restoring the double-layer structure of the electrode surface to a stable configuration at that concentration. After the stabilization period, the electrochemical workstation is activated to perform a full-frequency EIS scan of the water sample at the concentration ratio, acquiring impedance spectral data. After the scan is completed, the control system immediately resumes the concentration operation, entering the next "concentration-pause-scan-resume" cycle. The timing control strategy in this application ensures that each EIS test is performed under stable solution conditions, avoiding interference from the impedance spectrum caused by the solution being in a non-equilibrium state during concentration, while also ensuring consistency of test conditions between different concentration ratio points.

[0104] S105, equivalent circuit fitting is performed on the impedance spectrum sequences at each concentration factor to extract the electrical parameters at different concentration factors.

[0105] This step involves using the complex nonlinear least squares method to fit the equivalent circuit of the impedance spectrum data collected at various concentration ratios. Electrical parameters at different concentration ratios are then extracted.

[0106] S106. Based on the electrical parameters in the initial state and the electrical parameters at different concentration ratios, plot the degradation curves of electrochemical parameters as a function of concentration ratio.

[0107] This step uses the concentration factor as the x-axis and electrical parameters as the y-axis. The electrical parameter values ​​in the initial state are taken as the starting point of the curve. The corresponding electrical parameter values ​​extracted from the fitting at each concentration factor are marked into the coordinate system one by one. Spline interpolation or local weighted regression smoothing method is used to connect the data points and draw the degradation curves respectively.

[0108] Critical Concentration of Cooling Water (CRCC) refers to the maximum concentration at which a scale inhibitor can maintain its effective scale inhibition function during the continuous concentration of circulating cooling water. Once this concentration ratio is exceeded, the interfacial impedance parameters in the system will change significantly due to increased salt ion concentration, enhanced scale formation tendency, or decreased scale inhibitor effectiveness, indicating that the scale inhibitor's performance has begun to fail. CRCC is a core indicator used to quantify the high-concentration performance of scale inhibitors.

[0109] S107, detect the inflection point of the degradation curve, and determine the concentration ratio corresponding to the inflection point as the critical failure concentration ratio of the scale inhibitor to be evaluated.

[0110] This step involves detecting the inflection point of the plotted degradation curve using a combination of three methods: the slope change rate method, the second derivative zero-point method, and the exponential step abrupt change criterion for constant phase angle elements in the film layer. The concentration ratio corresponding to the inflection point is determined as the critical failure concentration ratio of the scale inhibitor to be evaluated.

[0111] The scale inhibitor performance evaluation method based on electrochemical impedance spectroscopy provided in this application involves preparing a simulated water sample using the makeup water quality of power plant circulating cooling water, adding a scale inhibitor, and obtaining the test water sample. The test water sample is placed in a three-electrode system, and an initial full-frequency EIS scan is performed at open-circuit potential. Electrical parameters under the initial state are extracted through equivalent circuit fitting. The water sample is then concentrated, and the concentration ratio is monitored. Heating is paused every 0.5-fold increase, and after stabilization, an EIS scan is performed to obtain the impedance spectrum data at that concentration ratio. Concentration is resumed, and the process is repeated. Equivalent circuit fitting is performed on the impedance spectra at each concentration ratio, and electrical parameters are extracted to plot the degradation curves of each parameter as a function of the concentration ratio. The inflection point is determined as the critical failure concentration ratio of the scale inhibitor being evaluated.

[0112] This application utilizes dynamic concentration and continuous full-frequency EIS monitoring to plot electrochemical parameter degradation curves. The concentration ratio corresponding to the inflection point is used as the critical failure concentration ratio (CRCC), quantifying the high-concentration tolerance limit of the scale inhibitor. This application enables rapid tracking of the complete degradation process of the scale inhibitor from effectiveness to failure, with an evaluation cycle of only a few days. The evaluation results can be presented as numerical CRCC, ensuring consistency and comparability between different scale inhibitors. By quantifying the scale inhibitor's tolerance limit using the critical failure concentration ratio, it achieves rapid, multidimensional, quantitative, and comparable performance evaluation.

[0113] In some embodiments, the electrical parameters include at least:

[0114] Charge transfer resistance, film resistance, and indices of constant phase angle elements in films; among which,

[0115] The charge transfer resistor is used to characterize the degree to which the charge transfer process at the electrode / solution interface is affected by scale deposition;

[0116] The film resistance is used to characterize the ability of the scale layer or scale inhibitor adsorption film on the electrode surface to hinder the interfacial mass transfer process.

[0117] The constant phase angle element index of the film layer is used to characterize the uniformity and density of the scale surface.

[0118] In this application, the electrical parameters include at least the charge transfer resistance Rct, the film resistance Rf, and the constant phase angle element index nf of the film. Rct is obtained by fitting the charge transfer branch in the equivalent circuit. Its value directly reflects the ease of electrochemical reaction at the metal-solution interface. The more severe the scale deposition on the electrode surface, the greater the obstacle to the charge transfer process, and the higher the Rct value. Rf is obtained by fitting the film branch and is used to quantify the ability of the scale layer or scale inhibitor adsorption film on the electrode surface to hinder the mass transfer of ions from the bulk solution to the metal surface. The denser and more complete the film, the higher the Rf value. nf is the dispersion index of the constant phase angle element of the film, obtained by fitting the film capacitance branch. Its value ranges from 0 to 1. The closer to 1, the more uniform, dense, and smooth the surface of the scale layer or adsorption film; the further away from 1, the rougher, more porous, or uneven the scale surface. By tracking the step decrease of nf as the concentration ratio increases, the abrupt destruction of the scale structure when the scale inhibitor fails can be effectively identified. These three electrical parameters comprehensively evaluate the performance of scale inhibitors from three dimensions: interfacial charge transfer, film mass transfer resistance, and scale surface state. By combining the differential evolution of the above electrical parameters with the concentration ratio, the critical failure concentration ratio of the scale inhibitor can be determined.

[0119] In some embodiments, the dynamic concentration process employs a constant-temperature heating evaporation method or a constant-current electrolysis method;

[0120] The constant temperature heating evaporation method includes:

[0121] Place the water sample to be tested into the reaction vessel;

[0122] The reaction vessel is placed in a constant temperature heating device, so that the water sample to be tested is heated at a preset temperature to evaporate the water.

[0123] During the heating process, a water bath is used for uniform heating and the water sample to be tested is magnetically stirred to maintain the spatial uniformity of solution temperature and ion concentration.

[0124] The constant current electrolysis method includes:

[0125] The inert electrodes, serving as both anode and cathode, are immersed in the water sample to be tested.

[0126] Electrolysis is performed on the water sample to be tested by applying a constant current density, so that the anode of the water sample undergoes an oxygen evolution reaction that consumes water molecules and generates hydrogen ions, and the cathode undergoes a hydrogen evolution reaction that consumes water molecules.

[0127] In this application, the constant-temperature heating evaporation method specifically involves placing the reaction vessel containing the water sample to be tested in a constant-temperature heating device, which can be a constant-temperature water bath or an electric constant-temperature bath, and heating it to a set temperature, typically 40~65℃, and maintaining this temperature. Heating causes the water in the solution to continuously evaporate, escaping as water vapor, while scale-forming ions such as Ca²⁺ and HCO₃⁻ remain in the solution, thus achieving a gradual increase in ion concentration. To prevent localized overheating that could lead to premature scale deposition on the container wall and interfere with the test, the heating method should employ uniform water bath heating or magnetic stirring to assist heat transfer, ensuring a uniform temperature field in the solution.

[0128] The constant current electrolysis method involves immersing inert electrodes, such as platinum or titanium-coated electrodes, into the water sample under test and applying a constant current density, for example, 5–20 mA / cm². During electrolysis, the anode undergoes an oxygen evolution reaction, consuming water molecules and generating H⁺, while the cathode undergoes a hydrogen evolution reaction, also consuming water molecules. This continuous electrolysis removes water, gradually increasing the ion concentration in the water sample. Constant current electrolysis can be performed at room temperature without heating, avoiding the impact of temperature rise on the scale inhibitor's performance. Furthermore, the microbubbles generated during electrolysis act as a stirrer. In actual concentration processes, heating evaporation more closely approximates the concentration mechanism of a real circulating cooling water system, while electrolysis is more suitable for temperature-sensitive scale inhibitor systems, ensuring the accuracy and reliability of impedance spectral data at various concentration ratios. The two concentration methods can be selected based on actual needs.

[0129] Furthermore, to ensure the ion concentration in the water sample increases continuously at a preset rate, the rate needs to be controlled. The rate control for heating evaporation can be achieved by adjusting three parameters: heating temperature, liquid surface exposure area, and surface air velocity. Specifically: ① Higher heating temperature results in a faster evaporation rate, but the temperature should not exceed 65°C to avoid thermal decomposition of the scale inhibitor or simulated changes in water composition. ② The larger the diameter of the reaction vessel, i.e., the gas-liquid interface area, the greater the evaporation rate per unit time. ③ Continuously blowing dry air or nitrogen onto the liquid surface can accelerate the removal of surface water vapor, significantly increasing the evaporation rate. In actual experiments, by calibrating the relationship between the above parameters and the evaporation rate through preliminary experiments, a stable concentration rate can be achieved after selecting a set of fixed parameters.

[0130] For rate control in constant current electrolysis, the rate of water consumption during electrolysis can be controlled by adjusting the applied constant current density. A higher current density results in more water being consumed per unit time, leading to a faster concentration rate. Understandably, in actual experiments, the relationship between current density and the rate of change in concentration ratio needs to be pre-calibrated based on the electrode area and solution volume.

[0131] In some embodiments, the real-time acquisition of the current concentration ratio of the water sample to be tested includes: measuring the conductivity of the water sample to be tested in real time and using the conductivity to perform calculations, or weighing the mass of the water sample to be tested in real time and using the mass to perform calculations.

[0132] The process includes real-time measurement of the conductivity of the water sample to be tested, and calculation using the conductivity, including:

[0133] The current conductivity value of the water sample to be tested is measured in real time using a conductivity electrode;

[0134] Based on the initial conductivity value and the current conductivity value of the water sample to be tested, the current concentration ratio of the water sample to be tested is calculated.

[0135] The real-time weighing of the water sample to be tested, and the calculation using the mass, include:

[0136] The total mass of the reaction vessel and the water sample to be tested was weighed using a balance.

[0137] Based on the initial mass and current mass of the water sample to be tested, the current concentration ratio of the water sample to be tested is calculated.

[0138] In this application, the concentration rate is characterized by the "concentration ratio change rate," which is the increase in the concentration ratio per unit time (e.g., 0.05~0.1 times / hour). The concentration ratio (Cycles of Concentration, COC) is defined as the ratio of the current concentration of a certain conservative ion (e.g., Cl⁻ or Ca²⁺) in the solution to its initial concentration.

[0139] Furthermore, to achieve precise control of the concentration process, real-time monitoring of the concentration ratio is required. This can be achieved by measuring the conductivity of the water sample in real time and using that conductivity for calculations, or by weighing the water sample in real time and using that mass for calculations.

[0140] The calculation utilizes conductivity. Specifically, an online conductivity electrode is installed in the reaction vessel to measure the solution's conductivity in real time. Since there is a strong positive correlation between ion concentration and conductivity, the current concentration ratio can be calculated by comparing the real-time conductivity with the initial conductivity. The specific calculation formula is as follows:

[0141] COC=κ0 / κ t

[0142] in, Let t be the conductivity of the solution at time t (μS / cm). The conductivity of the initial solution is given in μS / cm. The conductivity method offers rapid response and enables continuous online monitoring.

[0143] The calculation utilizes mass; specifically, it involves weighing the total mass of the reaction vessel and solution in real time, combining this with the initial solution mass to calculate the amount of water evaporation, and then extrapolating the current concentration ratio. The calculation formula is as follows:

[0144] COC = m0 / m

[0145] Where m0 is the initial solution mass (g), m t Let t be the mass of the solution at time t (g).

[0146] It should be noted that this application also provides auxiliary control over the temperature, liquid level, and solution homogeneity of the water sample during the dynamic concentration process to ensure the stability of the concentration process and the reliability of the EIS test data. Specifically, for temperature control, this application employs a constant temperature control system. Through closed-loop feedback adjustment between the heating device and the temperature sensor, the temperature of the water sample is stabilized within ±0.5℃ of the set value, avoiding the impact of temperature fluctuations on electrochemical processes such as charge transfer and diffusion, and ensuring the consistency of EIS test conditions at each concentration ratio. For liquid level control, since continuous evaporation of water will cause the liquid level to drop, changing the immersion area of ​​the working electrode and thus affecting the EIS test results, this application installs a liquid level sensor in the reaction vessel. When the liquid level drops to the preset lower limit, the control system can automatically activate the replenishment device to add deionized water to the initial liquid level. It should be noted that the amount of water added is included in the total amount of water evaporated in the concentration ratio calculation, thereby ensuring that the immersion area of ​​the working electrode remains constant throughout the entire experiment. To control solution homogeneity, a magnetic stirrer was placed at the bottom of the reaction vessel to continuously stir the water sample at 100-200 rpm. This ensured a spatially uniform distribution of solution temperature and ion concentration, preventing localized supersaturation and premature scaling. Accelerated water vapor diffusion at the gas-liquid interface further stabilized the evaporation rate, thus maintaining a homogeneous solution during EIS testing and ensuring that the test results represent the average response of the entire system rather than a localized state. These methods effectively guaranteed the accuracy and repeatability of subsequent electrochemical impedance spectroscopy data acquisition.

[0147] In some embodiments, the complex nonlinear least squares method is used to perform equivalent circuit fitting on the impedance spectrum sequences at each concentration factor;

[0148] The equivalent circuit structure includes: a parallel branch consisting of solution resistance, film resistance and film constant phase angle element, and a parallel branch consisting of charge transfer resistance and double layer constant phase angle element connected in series.

[0149] Among them, solution resistance characterizes the ohmic resistance of the bulk solution between the working electrode and the reference electrode, film resistance is used to quantify the hindering effect of scale or adsorption film on interfacial mass transfer, film constant phase angle element is used to describe the capacitive behavior of scale as a dielectric layer, charge transfer resistance reflects the ease of charge transfer process at the electrode / solution interface, and double layer constant phase angle element is used to describe the capacitive behavior of the double layer at the metal / solution interface.

[0150] When a 45-degree straight line segment appears in the low-frequency region of the impedance spectrum, i.e., a diffusion characteristic, a diffusion element is added to the equivalent circuit, and the equivalent circuit is expanded to a parallel branch of solution resistance, film resistance and film constant phase angle element, and a parallel branch of charge transfer resistance, double layer constant phase angle element and diffusion element connected in series.

[0151] Specifically, such as Figure 2 As shown, the equivalent circuit structure consists of a parallel branch composed of the solution resistance R_s, the film layer resistance Rf, and the film layer constant phase angle element Qf, and a parallel branch composed of the charge transfer resistance Rct and the double layer constant phase angle element Qdl, connected in series. The solution resistance R_s reflects the ohmic resistance of the bulk solution between the working electrode and the reference electrode, typically ranging from 1 to 20 Ω·cm², decreasing with increasing ion concentration as the concentration ratio increases. The film layer resistance Rf characterizes the ability of the electrode surface deposit to impede interfacial mass transfer processes; its variation reflects the scale formation state and interfacial structure changes. The film layer constant phase angle element Qf describes the capacitive behavior of the scale layer or adsorption membrane as a dielectric layer; the thicker the scale layer, the smaller the admittance modulus of the film layer capacitance; the denser and more uniform the scale layer, the closer the dispersion index of the film layer capacitance is to 1. The charge transfer resistance Rct reflects the ease of charge transfer at the electrode-solution interface; when the scale inhibitor is effective, Rct remains relatively stable, but after its failure, rapid scale formation causes a significant change in Rct. The constant phase angle element Qdl of the electric double layer is used to describe the capacitive behavior of the electric double layer at the metal-solution interface. The value of ndl is generally between 0.8 and 1.0. The rougher the electrode surface or the more adsorbed species, the further the diffusion index of the electric double layer capacitance deviates from 1. When a 45° straight line segment appears in the low frequency region, i.e., the Warburg diffusion characteristic, a diffusion element W is added. A diffusion element is added to the equivalent circuit to reflect the diffusion mass transfer process of scale-forming ions.

[0152] This application employs the complex nonlinear least squares method to perform equivalent circuit fitting on the impedance spectrum sequences at each concentration factor. The fitting convergence criterion is that the chi-square value χ² < 1×10⁻³, and the rate of change of each parameter in three consecutive iterations during the fitting iteration is less than 0.1%.

[0153] It should be noted that the equivalent circuit fitting in this application must simultaneously meet the following quality control indicators: the relative error of each fitted element, i.e., the ratio of the fitting standard deviation to the fitted value, should be less than 5%. If the relative error of a certain element is ≥5%, it indicates that the element's contribution to the spectrum is insignificant or there is overfitting, and the rationality of the equivalent circuit model needs to be checked. The chi-square value χ² should be controlled within 1×10⁻ 5 Between ~1×10⁻³, below 1×10⁻ 5 Excessive model parameters indicate overfitting, while parameters exceeding 1×10⁻³ indicate underfitting. Any parameters exceeding this limit require adjustment of the circuit model and refitting. The fitting residuals, the difference between measured and fitted values, should be randomly distributed within the frequency domain, without a clear trend or periodic fluctuations. If the residuals exhibit systematic deviations, such as consistently positive residuals in the low-frequency region, it indicates that the equivalent circuit model fails to adequately describe the physical processes in that frequency band, necessitating the addition of appropriate components. The parameters of each component obtained from the fitting should exhibit a physically reasonable trend with changes in the concentration factor, such as R... s If a parameter exhibits a drastic jump that violates physical laws as the concentration factor increases, such as a monotonous decrease with increasing concentration factor or a sudden drop in Rf after the failure point, it indicates abnormal spectral data or that the equivalent circuit model is no longer applicable at that concentration factor point, and data verification is required.

[0154] In some embodiments, degradation curves are plotted with the concentration factor on the x-axis and the values ​​of each electrochemical parameter on the y-axis.

[0155] It should be noted that after obtaining the Rct, Rf, and n values ​​at each concentration ratio, this application plotted a degradation curve with the concentration ratio COC as the x-axis and the parameter values ​​as the y-axis. For example... Figure 3 As shown, with the increase of concentration ratio COC, Rct first rises slowly, indicating that the scale layer gradually thickens, and then drops sharply after reaching the critical point; nf remains stable before failure, and drops sharply when the scale layer structure changes abruptly; the abrupt change points of the two curves both point to CRCC=5.0, indicating that the scale inhibitor fails at this concentration ratio.

[0156] In some embodiments, detecting the inflection point of the degradation curve includes:

[0157] The determination shall be made by at least two of the following methods: the slope change rate method, the second derivative zero point method, and the exponential step change criterion of constant phase angle element of film layer;

[0158] The method of detecting the inflection point of the degradation curve using the slope change rate method includes:

[0159] The degradation curve is smoothed.

[0160] Calculate the slope of the smoothed degradation curve at each point;

[0161] Calculate the rate of change of the slope;

[0162] The inflection point of the degradation curve is defined as the point where the absolute value of the rate of change of the slope is the maximum value.

[0163] The inflection point of the degradation curve is detected using the second derivative zero-point method, including:

[0164] Take the second derivative of the degradation curve;

[0165] The inflection point is the point where the second derivative of the degradation curve crosses zero.

[0166] The inflection point of the degradation curve is detected by an exponential step abrupt change using a constant phase angle element of the film layer, including:

[0167] Calculate the change in the exponent of the constant phase angle element of the film layer between adjacent concentration ratio points;

[0168] When two consecutive changes are both negative and their absolute values ​​both exceed the first preset value, or when the absolute value of a single change exceeds the second preset value, it is determined that a significant change has occurred.

[0169] The inflection point is defined as the data point preceding the first significant mutation.

[0170] The x-coordinate value corresponding to the inflection point is taken as the critical failure concentration factor.

[0171] In this application, three methods are used to comprehensively determine the critical failure concentration ratio: the slope change rate method, the second derivative zero-point method, and the exponential step change criterion for constant phase angle elements of the membrane layer. The consistency of results from at least two methods is considered the criterion. The slope change rate method involves smoothing the Rct-COC or Rf-COC degradation curve and calculating the slope at each point on the curve. The rate of change of the slope, i.e., the second derivative, is then calculated. The point where the absolute value of the second derivative reaches its maximum is taken as the inflection point, and the concentration ratio corresponding to this point is the CRCC. Physically, this means that before this point, Rct or Rf can still be maintained or slowly increase, while after this point, the degradation accelerates, indicating that the scale layer or adsorbent membrane structure has collapsed and the scale inhibitor has lost its effective protective ability. The second derivative zero-point method directly calculates the second derivative of the degradation curve, taking the point where the second derivative crosses zero as the inflection point, and using the concentration ratio corresponding to the inflection point as the CRCC. The exponential step mutation criterion for constant phase angle elements in the membrane layer involves plotting the curve of NF as a function of concentration ratio. When the scale inhibitor is effective, NF remains between 0.85 and 0.95 with a gradual change. When the scale inhibitor fails, the uniformity of the scale surface decreases sharply, and NF will experience a step drop exceeding 0.1 within a small concentration ratio increment. The initial concentration ratio at this mutation point is used as an auxiliary criterion for CRCC. Furthermore, the NF step mutation often occurs earlier than the inflection point of Rct or Rf, serving as an early warning indicator of scale inhibitor failure. In comprehensive judgment, when the deviation between the CRCC values ​​determined by the slope change rate method and the second derivative zero-point method does not exceed 0.3 times the concentration ratio, the arithmetic mean of the two is taken as the final CRCC. If the deviation exceeds 0.3 times, the exponential step mutation criterion for constant phase angle elements in the membrane layer is introduced for arbitration, and the result of at least two of the three methods being consistent is taken as the standard.

[0172] The quantitative criterion for a step change in the constant phase angle element index nf of the film layer is as follows: Calculate the change in nf between adjacent concentration ratio points, Δnf = nf(i+1) - nf(i). When two consecutive Δnf values ​​are negative and their absolute values ​​both exceed 0.08, or when the absolute value of a single Δnf exceeds 0.12, it is judged as a "significant change," and the concentration ratio point before the first significant change occurs is used as the reference value for the CRCC nf criterion. The physical meaning of this criterion is that when the scale inhibitor is effective, the scale surface is relatively uniform, and the nf value changes slowly; when the scale inhibitor fails, the uniformity of the scale surface deteriorates sharply due to peeling, porosity, or local thickening, and the nf value drops sharply. Moreover, this change often occurs earlier than the inflection point of Rct or Rf, and can be used as an early warning indicator of scale inhibitor failure.

[0173] In some embodiments, determining the concentration ratio corresponding to the inflection point as the critical failure concentration ratio of the scale inhibitor to be evaluated includes:

[0174] Under the same conditions, obtain at least three experimental critical failure concentration ratio values;

[0175] Calculate the average and standard deviation of the critical failure concentration ratio values ​​from the three tests;

[0176] When the critical failure concentration ratio value of the test deviates from the average value by more than three times the standard deviation, it is judged as an outlier and removed; among them, the number of valid tests after removal is greater than or equal to three.

[0177] Different scale inhibitors were ranked in descending order of performance based on their average critical failure concentration ratio.

[0178] In this application, to eliminate random errors from a single test, each scale inhibitor is subjected to at least three independent repeated tests under the same conditions, with one CRCC value obtained independently for each test. The final result is expressed as the average ± standard deviation of the results from multiple tests.

[0179]

[0180]

[0181]

[0182] in, SD represents the critical failure concentration ratio, and SD represents the standard deviation. Let i be the concentration ratio value of the i-th experiment. is the average concentration ratio, and n is the number of experiments.

[0183] The smaller the standard deviation, the better the repeatability of the method, and a standard deviation not exceeding 0.3 times the concentration ratio is considered to be acceptable for repeatability. When comparing the performance of multiple scale inhibitors, they are sorted from high to low according to the average CRCC value. The larger the average value, the stronger the high concentration tolerance of the scale inhibitor.

[0184] If the EIS spectrum of a certain test fails to meet the data validity criteria at three or more consecutive concentration ratio points, or if the degradation curve of the test differs significantly from the typical curve of similar scale inhibitors (e.g., abnormal fluctuations before the inflection point or a sudden drop of less than 20% at the inflection point that cannot be reasonably explained), or if the CRCC value of the test deviates from the average value of other repeated tests by more than three times the standard deviation, then it is considered an outlier and the test data should be identified as abnormal and removed. After removing the abnormal data, the CRCC average value and standard deviation should be recalculated using the remaining valid test data. The number of valid tests should not be less than three; otherwise, additional tests should be conducted. The final results should clearly indicate the number of data points removed and the basis for removal.

[0185] In some embodiments, the method further includes: after each electrochemical impedance spectroscopy scan, performing data validity verification on the obtained impedance spectrum, including:

[0186] The impedance spectrum was subjected to Nyquist plot integrity verification, high-frequency scattering threshold verification, and Kramers-Kronig consistency verification.

[0187] If any verification fails, the current scan data is deemed invalid and re-acquired.

[0188] In this application, to ensure that the quality of the EIS spectra used in the fitting meets the requirements of subsequent analysis, the following data validity criteria are established: First, Nyquist plot integrity criterion: It should be noted that a valid spectrum should simultaneously contain both the capacitive arc in the high-frequency region and the diffusion characteristics in the low-frequency region. If the spectrum shows severe truncation in the high-frequency region or complete divergence in the low-frequency region without any arc characteristics, the spectrum is deemed invalid and needs to be re-acquired; Second, high-frequency region scattering threshold criterion: High-frequency region (10 kHz~100 kHz) The relative standard deviation between data points (kHz) should not exceed 5%. If it exceeds this value, it indicates insufficient signal-to-noise ratio or the presence of high-frequency electromagnetic interference, and the data set should be discarded or retested. Third, Kramers-Kronig consistency test: Perform a KK transform test on each spectrum to verify whether the real and imaginary parts of the impedance meet the causality, linearity, and stability conditions. If the relative error exceeds 3%, it indicates that the system does not meet the stability conditions or has a nonlinear response during the test, and the spectrum should be reacquired or labeled as low-quality data. Fourth, open-circuit potential stability criterion: Record the open-circuit potential value before and after each EIS scan. If the change in open-circuit potential before and after the scan exceeds a preset range, such as ±3... The mV value indicates that the interface state drifted during the test. This spectral data is abnormal and cannot be used for subsequent fitting; it needs to be re-acquired at the same concentration point. Fifth, repeatability criteria: EIS tests at the same concentration point should be repeated at least three times independently. If the relative standard deviation of each characteristic parameter (Rct, Rf) obtained from the three measurements does not exceed 10%, the data repeatability is considered qualified, and the average of the three measurements can be used for subsequent analysis. If it exceeds 10%, the system state should be checked and the test should be repeated. When any of the above criteria is not met, the scan data is deemed invalid and needs to be re-acquired.

[0189] like Figure 4 As shown, this application provides a scale inhibitor performance evaluation device based on electrochemical impedance spectroscopy, the device comprising:

[0190] Configuration module 401 is used to add the scale inhibitor to be evaluated into the configured simulated circulating cooling water to obtain the water sample to be tested.

[0191] The scanning module 402 is used to perform electrochemical impedance spectroscopy scanning on the water sample to be tested, obtain the impedance spectrum, and extract the electrical parameters of the impedance spectrum in the initial state.

[0192] The concentration module 403 is used to perform dynamic concentration processing on the water sample to be tested, so that the ion concentration in the water sample to be tested continues to rise at a preset rate.

[0193] The acquisition module 404 is used to acquire the current concentration ratio of the water sample to be tested in real time. After pausing the concentration and stabilizing the water sample to be tested at fixed concentration ratio increments, the water sample to be tested is scanned by full-frequency electrochemical impedance spectroscopy to acquire impedance spectrum sequences at different concentration ratios.

[0194] The fitting module 405 is used to perform equivalent circuit fitting on the impedance spectrum sequences at each concentration factor to extract the electrical parameters at different concentration factors.

[0195] The plotting module 406 is used to plot the degradation curve of electrochemical parameters as a function of concentration ratio based on the electrical parameters in the initial state and the electrical parameters at different concentration ratios.

[0196] The determination module 407 is used to detect the inflection point of the degradation curve and determine the concentration ratio corresponding to the inflection point as the critical failure concentration ratio of the scale inhibitor to be evaluated.

[0197] According to embodiments of this application, this application also provides an electronic device and a readable storage medium.

[0198] The electronic device includes at least one processor and a memory communicatively connected to the at least one processor. The memory stores instructions executable by the at least one processor, which, when executed, enable the at least one processor to perform the scale inhibitor performance evaluation method based on electrochemical impedance spectroscopy as described in this application. The computer instructions are used to cause the computer to perform the scale inhibitor performance evaluation method based on electrochemical impedance spectroscopy as described in this application.

[0199] This application also provides a computer program product, including a computer program / instructions, which, when executed by a processor, implements the electrochemical impedance spectroscopy-based method for evaluating the performance of scale inhibitors of this application.

[0200] Figure 3A schematic block diagram of an example electronic device 800 that can be used to implement embodiments of this application is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the application described and / or claimed herein.

[0201] like Figure 3 As shown, the electronic device 800 includes a computing unit 801, which can perform various appropriate actions and processes based on a computer program stored in a read-only memory (ROM) 802 or a computer program loaded from a storage unit 808 into a random access memory (RAM) 803. The RAM 803 may also store various programs and data required for the operation of the electronic device 800. The computing unit 801, ROM 802, and RAM 803 are interconnected via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0202] Multiple components in electronic device 800 are connected to I / O interface 805, including: input unit 806, such as keyboard, mouse, etc.; output unit 807, such as various types of displays, speakers, etc.; storage unit 808, such as disk, optical disk, etc.; and communication unit 809, such as network card, modem, wireless transceiver, etc. Communication unit 809 allows electronic device 800 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0203] The computing unit 801 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the computing unit 801 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 801 performs the various methods and processes described above, such as the electrochemical impedance spectroscopy-based scale inhibitor performance evaluation method. For example, in some embodiments, the electrochemical impedance spectroscopy-based scale inhibitor performance evaluation method can be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as storage unit 808. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 800 via ROM 802 and / or communication unit 809. When the computer program is loaded into RAM 803 and executed by the computing unit 801, one or more steps of the electrochemical impedance spectroscopy-based scale inhibitor performance evaluation method described above can be performed. Alternatively, in other embodiments, the computing unit 801 may be configured by any other suitable means (e.g., by means of firmware) to perform a scale inhibitor performance evaluation method based on electrochemical impedance spectroscopy.

[0204] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0205] The program code used to implement the methods of this application may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0206] In the context of this application, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0207] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the computer. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0208] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as a data server), or computing systems that include middleware components (e.g., an application server), or computing systems that include frontend components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., a communication network). Examples of communication networks include local area networks (LANs), wide area networks (WANs), and the Internet.

[0209] Computer systems can include clients and servers. Clients and servers are generally located far apart and typically interact via communication networks. Client-server relationships are created by computer programs running on the respective computers and having a client-server relationship with each other. Servers can be cloud servers, servers in distributed systems, or servers incorporating blockchain technology.

[0210] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for evaluating the performance of scale inhibitors based on electrochemical impedance spectroscopy, characterized in that, The method includes: The scale inhibitor to be evaluated was added to the prepared simulated circulating cooling water to obtain the water sample to be tested; Electrochemical impedance spectroscopy was performed on the water sample to be tested to obtain the impedance spectrum and extract the electrical parameters of the impedance spectrum in the initial state. The water sample to be tested is subjected to dynamic concentration treatment, so that the ion concentration in the water sample to be tested continues to rise at a preset rate. The current concentration ratio of the water sample to be tested is acquired in real time. Concentration is paused and the water sample to be tested is stabilized at fixed concentration ratio increments. Then, the water sample to be tested is scanned with full-frequency electrochemical impedance spectroscopy to obtain impedance spectrum sequences at different concentration ratios. Equivalent circuit fitting was performed on the impedance spectrum sequences at each concentration factor to extract the electrical parameters at different concentration factors. Based on the electrical parameters under the initial state and the electrical parameters at different concentration ratios, degradation curves of electrochemical parameters as a function of concentration ratio were plotted. The inflection point of the degradation curve is detected, and the concentration ratio corresponding to the inflection point is determined as the critical failure concentration ratio of the scale inhibitor to be evaluated.

2. The method according to claim 1, characterized in that, The electrical parameters include at least: Charge transfer resistance, film resistance, and indices of constant phase angle elements in films; among which, The charge transfer resistor is used to characterize the degree to which the charge transfer process at the electrode / solution interface is affected by scale deposition; The film resistance is used to characterize the ability of the scale layer or scale inhibitor adsorption film on the electrode surface to hinder the interfacial mass transfer process. The constant phase angle element index of the film layer is used to characterize the uniformity and density of the scale surface.

3. The method according to claim 1, characterized in that, The dynamic concentration process employs either constant-temperature heating evaporation or constant-current electrolysis. The constant temperature heating and evaporation method includes: Place the water sample to be tested into the reaction vessel; The reaction vessel is placed in a constant temperature heating device, so that the water sample to be tested is heated at a preset temperature to evaporate the water. During the heating process, a water bath is used for uniform heating and the water sample to be tested is magnetically stirred to maintain the spatial uniformity of solution temperature and ion concentration. The constant current electrolysis method includes: The inert electrodes, serving as both anode and cathode, are immersed in the water sample to be tested. Electrolysis is performed on the water sample to be tested by applying a constant current density, so that the anode of the water sample undergoes an oxygen evolution reaction that consumes water molecules and generates hydrogen ions, and the cathode undergoes a hydrogen evolution reaction that consumes water molecules.

4. The method according to claim 3, characterized in that, The real-time acquisition of the current concentration ratio of the water sample to be tested includes: real-time measurement of the conductivity of the water sample to be tested, and calculation using the conductivity, or real-time weighing of the mass of the water sample to be tested, and calculation using the mass; The calculation, which involves real-time measurement of the conductivity of the water sample to be tested and using the conductivity, includes: The current conductivity value of the water sample to be tested is measured in real time using a conductivity electrode; Based on the initial conductivity value and the current conductivity value of the water sample to be tested, the current concentration ratio of the water sample to be tested is calculated. The real-time weighing of the water sample to be tested, and the calculation using the mass, include: The total mass of the reaction vessel and the water sample to be tested was weighed using a balance. Based on the initial mass and current mass of the water sample to be tested, the current concentration ratio of the water sample to be tested is calculated.

5. The method according to claim 1, characterized in that, The impedance spectrum sequences at each concentration factor were fitted with equivalent circuits using the complex nonlinear least squares method. The equivalent circuit structure includes: a parallel branch consisting of solution resistance, film resistance and film constant phase angle element, and a parallel branch consisting of charge transfer resistance and double layer constant phase angle element connected in series. Among them, solution resistance characterizes the ohmic resistance of the bulk solution between the working electrode and the reference electrode, film resistance is used to quantify the hindering effect of scale or adsorption film on interfacial mass transfer, film constant phase angle element is used to describe the capacitive behavior of scale as a dielectric layer, charge transfer resistance reflects the ease of charge transfer process at the electrode / solution interface, and double layer constant phase angle element is used to describe the capacitive behavior of the double layer at the metal / solution interface. When a 45-degree straight line segment appears in the low-frequency region of the impedance spectrum, i.e., a diffusion characteristic, a diffusion element is added to the equivalent circuit, and the equivalent circuit is expanded to a parallel branch of solution resistance, film resistance and film constant phase angle element, and a parallel branch of charge transfer resistance, double layer constant phase angle element and diffusion element connected in series.

6. The method according to claim 1, characterized in that, Degradation curves were plotted with the concentration factor on the x-axis and the values ​​of each electrochemical parameter on the y-axis.

7. The method according to claim 1, characterized in that, The detection of the inflection point of the degradation curve includes: The determination shall be made by at least two of the following methods: the slope change rate method, the second derivative zero point method, and the exponential step change criterion of constant phase angle element of film layer; The method of detecting the inflection point of the degradation curve using the slope change rate method includes: The degradation curve is smoothed. Calculate the slope of the smoothed degradation curve at each point; Calculate the rate of change of the slope; The inflection point of the degradation curve is defined as the point where the absolute value of the rate of change of the slope is the maximum value. The inflection point of the degradation curve is detected using the second derivative zero-point method, including: Take the second derivative of the degradation curve; The inflection point is the point where the second derivative of the degradation curve crosses zero. The inflection point of the degradation curve is detected by an exponential step abrupt change using a constant phase angle element of the film layer, including: Calculate the change in the exponent of the constant phase angle element of the film layer between adjacent concentration ratio points; When two consecutive changes are both negative and their absolute values ​​both exceed the first preset value, or when the absolute value of a single change exceeds the second preset value, it is determined that a significant change has occurred. The inflection point is defined as the data point preceding the first significant mutation. The x-coordinate value corresponding to the inflection point is taken as the critical failure concentration factor.

8. The method according to claim 1, characterized in that, The step of determining the concentration ratio corresponding to the inflection point as the critical failure concentration ratio of the scale inhibitor to be evaluated includes: Under the same conditions, obtain at least three experimental critical failure concentration ratio values; Calculate the average and standard deviation of the critical failure concentration ratio values ​​from the three tests; When the critical failure concentration ratio value of the test deviates from the average value by more than three times the standard deviation, it is judged as an outlier and removed; among them, the number of valid tests after removal is greater than or equal to three. Different scale inhibitors were ranked in descending order of performance based on their average critical failure concentration ratio.

9. The method according to claim 1, characterized in that, Also includes: After each electrochemical impedance spectroscopy scan, the obtained impedance spectra are validated for data validity, including: The impedance spectrum was subjected to Nyquist plot integrity verification, high-frequency scattering threshold verification, and Kramers-Kronig consistency verification. If any verification fails, the current scan data is deemed invalid and re-acquired.

10. A scale inhibitor performance evaluation device based on electrochemical impedance spectroscopy, characterized in that, The device includes: The configuration module is used to add the scale inhibitor to be evaluated to the configured simulated circulating cooling water to obtain the water sample to be tested. The scanning module is used to perform electrochemical impedance spectroscopy scanning on the water sample to be tested, obtain the impedance spectrum, and extract the electrical parameters of the impedance spectrum in the initial state. The concentration module is used to dynamically concentrate the water sample to be tested, so that the ion concentration in the water sample to be tested continues to rise at a preset rate. The acquisition module is used to acquire the current concentration ratio of the water sample to be tested in real time. After pausing the concentration and stabilizing the water sample with a fixed concentration ratio increment, the module performs a full-frequency electrochemical impedance spectroscopy scan on the water sample to be tested to acquire impedance spectrum sequences at different concentration ratios. The fitting module is used to perform equivalent circuit fitting on the impedance spectrum sequences at each concentration factor to extract the electrical parameters at different concentration factors. The plotting module is used to plot the degradation curves of electrochemical parameters as a function of concentration ratio, based on the electrical parameters in the initial state and the electrical parameters at different concentration ratios. The determination module is used to detect the inflection point of the degradation curve and determine the concentration ratio corresponding to the inflection point as the critical failure concentration ratio of the scale inhibitor to be evaluated.

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