Method for characterizing ion exchange membrane pollution and online monitoring method

Abstract

The invention discloses a method for characterizing ion exchange membrane pollution and an online monitoring method. The method for characterizing ion exchange membrane pollution comprises the following steps: S1, acquiring impedance data of an ion exchange membrane; s2, constructing a pollution-free and polluted ion exchange membrane equivalent circuit model based on the obtained impedance data; s3, acquiring resistance data and capacitance data of the pollution-free and polluted ion exchange membranes according to the equivalent circuit model; and S4, determining the pollution degree of the ion exchange membrane according to the resistance data and the capacitance data. The method for characterizing ion exchange membrane pollution provided by the invention can accurately detect the influence of a pollution layer on the ion exchange membrane on ion transport, and can test the impedance of the pollution membrane off line; the method for characterizing the pollution of the ion exchange membrane provided by the invention can determine the pollution degree of the ion exchange membrane.

Description

Technical Field

[0001] The invention relates to an electrochemical testing device and method, in particular to a method for characterizing ion exchange membrane pollution and an online monitoring method, belonging to the technical field of electrochemical testing. Background Art

[0002] The main methods for extracting lithium from salt lake brine are adsorption, extraction, nanofiltration and electrodialysis. Among them, electrodialysis has the advantages of few operating parameters, easy control, low energy consumption, low cost, no need to add chemical reagents, little environmental harm, simple pretreatment, low device loss, long life, and high recovery rate of raw water. It is one of the most widely used membrane technologies. Electrodialysis is a highly selective electro-membrane separation process. It uses potential difference as a driving force to transfer ions from one side of the membrane to the other side through a membrane stack equipped with an ion-selective exchange membrane, thereby achieving the concentration and desalination of the raw material solution. However, salt lake brine also contains a large amount of other impurities such as calcium and magnesium ions. When electrodialysis is used to treat such brine, inorganic scaling of the ion membrane is prone to occur, resulting in a decrease in desalination efficiency, affecting the stability of the electrodialysis system operation, and limiting the large-scale application of electrodialysis technology. Therefore, it is of great significance to study the pollution mechanism and prevention and control measures of ion exchange membranes during electrodialysis, which can provide theoretical support for the widespread application of electrodialysis technology in lithium extraction from salt lake brine and provide a theoretical basis for solving membrane pollution. However, the study of membrane fouling requires the use of efficient characterization methods to accurately analyze the fouling mechanism.

[0003] The commonly used methods for characterizing membrane fouling include:

[0004] Scanning electron microscopy (SEM) can provide high-resolution images of the membrane surface micromorphology and pollutant morphology, and can intuitively observe the type and distribution of pollutants.

[0005] Energy Dispersive Spectroscopy (EDS), used in conjunction with SEM, can determine the chemical composition of contaminants, providing qualitative and quantitative information for elemental analysis.

[0006] Contact angle measurement,Contact angle measurement can evaluate the changes in the hydrophilicity or hydrophobicity of the membrane surface, thereby indirectly reflecting the fouling of the membrane surface.

[0007] Membrane surface conductivity measurement: Since pollutants usually affect the conductivity of the membrane, the degree of membrane contamination can be indirectly assessed by measuring the conductivity changes on the membrane surface.

[0008] XRD and FTIR, etc.

[0009] Although these characterization methods can analyze the morphology and chemical composition of membrane surface pollutants, since the ion exchange membrane is always in a DC electric field during the electrodialysis process, the above-mentioned characterizations cannot timely reflect the ion electrical migration state at the membrane interface and inside, and it is difficult to detect the impact of the contamination layer on the ion exchange membrane on ion transport. At the same time, the above-mentioned characterization methods are single. Summary of the invention

[0010] In view of the deficiencies of the prior art, the object of the present invention is to provide a method for characterizing ion exchange membrane contamination and an online monitoring method that can realize online monitoring of the contamination process and can also perform impedance testing on ion exchange membranes that are contaminated by different types of contamination.

[0011] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0012] In one aspect, the present invention discloses a method for characterizing ion exchange membrane contamination, comprising the following steps:

[0013] S1. Obtaining impedance data of ion exchange membrane;

[0014] S2. constructing equivalent circuit models of non-polluted and polluted ion exchange membranes based on the obtained impedance data;

[0015] S3. Obtaining resistance data and capacitance data of the non-polluted and polluted ion exchange membranes according to the equivalent circuit model;

[0016] S4. Determine the contamination degree of the ion exchange membrane based on the resistance data and the capacitance data.

[0017] Furthermore, the method for characterizing ion exchange membrane contamination is based on an EIS test device, which is connected to an impedance analyzer. The impedance analyzer performs an electrochemical impedance test on the ion exchange membrane in the preset EIS test device to obtain impedance data.

[0018] Furthermore, the equivalent circuit model includes an equivalent circuit model of a pure ion exchange membrane, and the equivalent circuit model of the pure ion exchange membrane is a [R(RQ)(RQ)] model, and the [R(RQ)(RQ)] model includes an equivalent resistance R of the electrolyte in the electrolytic cell of the EIS test device. s , the equivalent resistance R of the ion exchange membrane m , the equivalent resistance R of the double layer of the ion exchange membrane edl And constant phase angle element Q edl , the equivalent resistance R of the diffusion layer of the ion exchange membrane dbl Its constant phase angle element Q dbl , where the equivalent resistance of the electrolyte solution is R s , the equivalent resistance R of the ion exchange membrane m, the equivalent resistance R of the double layer of the ion exchange membrane edl and the equivalent resistance R of the diffusion layer of the ion exchange membrane dbl In series, the equivalent resistance R of the double layer of the ion exchange membrane edl And its constant phase angle element Q in parallel, the equivalent resistance R edl and its constant phase angle element Q in parallel.

[0019] Furthermore, the equivalent circuit model includes an equivalent circuit model of a contaminated film, and the equivalent circuit model of the contaminated film is a [R(RQ)(RC)(RQ)] model, and the [R(RQ)(RC)(RQ)] model is a model in which an equivalent resistor R is connected in series with the [R(RQ)(RQ)] model. p , R p Then connect C in parallel p , where R p is the equivalent resistance of the contamination layer of the contaminated membrane, C p is the capacitance of the contamination layer of the contamination membrane.

[0020] The present invention also discloses an online monitoring method for characterizing ion exchange membrane pollution. The online monitoring method is based on an online monitoring device for ion exchange membrane pollution, and includes placing an ion exchange membrane to be tested in the online monitoring device for ion exchange membrane pollution, injecting a pollutant solution into the online monitoring device, starting a power switch, and online monitoring the process of ion exchange membrane pollution.

[0021] Furthermore, the online monitoring device for ion exchange membrane pollution includes more than two compartments, wherein the ion exchange membrane to be detected is placed between two compartments, a salt bridge is arranged in the two compartments, the salt bridge is filled with an electrolyte solution, electrodes are arranged in the electrolyte solution, inert metal electrode sheets are arranged on the back surfaces of the two compartments, and electrode plates are arranged on the sides of the two compartments at both ends.

[0022] Furthermore, the online monitoring device for ion exchange membrane pollution includes five compartments, the two middle compartments are provided with salt bridges, the salt bridges are filled with electrolyte solution, electrodes are provided in the electrolyte solution, inert metal electrode sheets are provided on the back surfaces of the two compartments, and electrode plates are provided on the sides of the two compartments at both ends.

[0023] Furthermore, the salt bridge is an L-type ceramic core salt bridge.

[0024] Furthermore, the electrode plate is embedded in the ends of two compartments at both ends, the electrode plate is connected to the compartment in a detachable manner, and the electrode plate is an inert metal electrode plate.

[0025] Furthermore, each of the compartments is provided with a water inlet and a water outlet.

[0026] Compared with the prior art, the advantages of the present invention include:

[0027] 1) The method for characterizing ion exchange membrane contamination provided by the present invention can accurately detect the influence of the contamination layer on the ion exchange membrane on ion transport and can test the impedance of the contaminated membrane offline;

[0028] 2) The method for characterizing ion exchange membrane contamination provided by the present invention can determine the degree of ion exchange membrane contamination;

[0029] 3) The method for characterizing the pollution of ion exchange membranes provided by the present invention can more intuitively determine the pollution degree of ion exchange membranes; the method for characterizing the pollution of ion exchange membranes provided by the present invention is simple, and only needs to obtain the resistance value of the corresponding part through reasonable fitting, and the resistance value of the pollution layer can be quantified. The pollution degree can be analyzed by comparing the size and increase degree of the resistance value, and there is no need to obtain the pollution degree through a large amount of calculation;

[0030] 4) The present invention provides an online monitoring method for characterizing ion exchange membrane contamination, which can monitor the electrochemical characteristics of the ion exchange membrane contamination process online. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of a method for characterizing ion exchange membrane contamination provided by the present invention;

[0032] Figure 2 It is a structural schematic diagram of a four-electrode EIS testing device provided by the present invention;

[0033] Figure 3 It is a structural schematic diagram of the online monitoring device for ion exchange membrane pollution provided by the present invention;

[0034] Figure 4 The Nyquist equivalent circuit fitting diagram of the electrochemical impedance spectrum of the contaminated cation exchange membrane in the low frequency range (1000Hz-0.01Hz) under different conditions;

[0035] Figure 5 A schematic diagram of the [R(RQ)(RQ)] model provided by the present invention;

[0036] Figure 6 A schematic diagram of the [R(RQ)(RC)(RQ)] model provided by the present invention;

[0037] Figure 7a This is a figure fitted using the forward osmosis membrane characterization method in Comparative Example 1 of the present invention;

[0038] Figure 7b This is a figure fitted using the characterization method of the present invention in Comparative Example 1 of the present invention;

[0039] Explanation of the accompanying drawings: 1. compartment; 2. salt bridge; 3. electrode plate; 4. electrode; 5. water inlet; 6. water outlet; 7. electrode sheet. DETAILED DESCRIPTION

[0040] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

[0041] In one aspect, the present invention discloses a method for characterizing ion exchange membrane contamination, the method comprising the following steps:

[0042] S1. Obtain impedance data of the ion exchange membrane; wherein the impedance data includes the resistance R of the ion exchange membrane and the electrolyte m+s (That is, the equivalent resistance R of the electrolyte s The equivalent resistance R of the ion exchange membrane m The sum of the double layer resistance R edl , the equivalent resistance R of the contamination layer of the contaminated film p , the equivalent resistance R of the diffusion layer of the ion exchange membrane dbl The ion exchange membrane includes a contaminated ion exchange membrane and an uncontaminated ion exchange membrane.

[0043] S2. constructing equivalent circuit models of non-contaminated and contaminated ion exchange membranes based on the obtained impedance data;

[0044] S3. Obtaining resistance data and capacitance data of the non-polluted and polluted ion exchange membranes according to the equivalent circuit model;

[0045] S4. Determine the contamination degree of the ion exchange membrane based on the resistance data and the capacitance data.

[0046] The method for characterizing ion exchange membrane pollution is based on a four-electrode EIS testing device, which comprises two compartments, an ion exchange membrane to be tested is placed between the two compartments, a salt bridge is arranged in each of the two compartments, the salt bridge is an L-shaped ceramic core salt bridge, a 3.5 mol / L KCl solution is filled in the salt bridge, a silver chloride electrode is arranged in the electrolyte solution, and the electrode is used to connect a reference electrode and a sensing electrode of an electrochemical workstation; ruthenium-plated titanium electrode plates are arranged on opposite surfaces of the two compartments, the ruthenium-plated titanium electrode plates are detachably embedded in the compartments, and the two electrode plates and the two compartments form a cavity for placing a solution to be tested.

[0047] Specifically, a method for characterizing ion exchange membrane contamination comprises the following steps:

[0048] S1. Place the ion exchange membrane to be tested between the two compartments;

[0049] S2. preparing an electrolyte solution, and injecting the prepared electrolyte solution into the two compartments;

[0050] S3, connect one of the electrode plates to the counter electrode (CE) of the electrochemical workstation channel, and connect the reference electrode close to this electrode plate to the reference electrode (RE) of the electrochemical workstation channel; connect the other electrode plate to the working electrode (WE) of the electrochemical workstation channel, and connect the reference electrode close to this electrode plate to the sensing electrode (SE) of the electrochemical workstation channel;

[0051] S4. Open the EIS test project on the computer connected to the electrochemical workstation, set the test frequency to 1000 Hz to 0.01 Hz, the AC voltage amplitude to 0.01 V, and collect multiple impedance data;

[0052] S5. After the test is completed, the impedance data of the ion exchange membrane is collected, and the equivalent circuit models of the uncontaminated and contaminated cation exchange membranes are constructed based on the collected impedance data, and the resistance and capacitance values ​​of the uncontaminated and contaminated cation exchange membranes are obtained according to the equivalent circuit model.

[0053] The equivalent circuit model includes an equivalent circuit model of a pure ion exchange membrane (a pure ion exchange membrane is an uncontaminated ion exchange membrane), wherein the equivalent circuit model of the pure ion exchange membrane is a [R(RQ)(RQ)] model, wherein the [R(RQ)(RQ)] model includes an equivalent resistance R of the electrolyte in the compartment of the EIS test device. s , the equivalent resistance R of the ion exchange membrane m , the equivalent resistance R of the double layer of the ion exchange membrane edl And constant phase angle element Q edl , the equivalent resistance R of the diffusion layer of the ion exchange membrane dbl Its constant phase angle element Q dbl， Q edl and Q dbl It is a device in the circuit, and the corresponding data is obtained after fitting. The equivalent resistance R of the electrolyte solution s , the equivalent resistance R of the ion exchange membrane m , the equivalent resistance R of the double layer of the ion exchange membrane edl and the equivalent resistance R of the diffusion layer of the ion exchange membrane dbl Series, equivalent resistance R edl Its constant phase angle element Q edl Parallel connection, equivalent resistance R edl Its constant phase angle element Q dblIn the present invention, the ion exchange membrane system is generally equivalent to a resistor. The [R(RQ)(RQ)] model in the present invention involves fewer circuit elements and a simpler connection method. The model can more accurately describe the circuit behavior of the ion exchange membrane.

[0054] In the contaminated film, the equivalent resistance R is connected in series in the [R(RQ)(RQ)] model p , R p Then connect C in parallel p , forming the [R(RQ)(RC)(RQ)] model, where R p is the equivalent resistance of the contamination layer of the contaminated membrane, and Cp is the capacitance of the contamination layer of the contaminated membrane.

[0055] Embodiment 1:

[0056] This example uses Fuji's Type 12 cation exchange membrane and its different concentrations of Ca 2+ , different Ca 2+ The solution system contaminated membrane is used as the membrane to be tested. The EIS test is carried out using a four-electrode EIS test device, and relevant impedance data are collected to establish a model. The data is analyzed to obtain the electrochemical properties of the contaminated membrane. The operation steps and data analysis are as follows:

[0057] (1) Ion exchange membrane (pure cation exchange membrane: CEM, membrane contaminated with 0.5 g / L CaCl2 solution: Ca 2+ -0.5gM, 2g / L CaCl2 solution contaminated membrane: Ca 2+ -2g-M, 0.5g / L CaSO4 solution contaminated membrane: Ca 2+ -SO4 2- -0.5gM, 0.9g / L CaSO4 solution contaminated membrane: Ca 2+ -SO4 2- -0.9gM) is placed in an electrolytic cell, the electrolytic cell is divided into two electrolytic chambers, ruthenium-plated titanium electrode plates are placed on both sides of the two electrolytic chambers (i.e., compartments) as working electrodes and counter electrodes, two saturated AgCl electrodes connected to an L-shaped ceramic core salt bridge are respectively used as reference electrodes and sensing electrodes and are symmetrically arranged on both sides of the ion exchange membrane, and the four electrodes and the electrolytic cell constitute a four-electrode EIS test device. Subsequently, the electrolytic cell is filled with an electrolyte solution (the electrolyte is a 1g / L LiCl solution).

[0058] (2) Connect the EIS test device to an impedance analyzer, and perform an electrochemical impedance test on the ion exchange membrane in the preset EIS device through the impedance analyzer to obtain corresponding impedance data. Based on the impedance data, an equivalent circuit model of the ion exchange membrane is constructed to fit the impedance data diagram, such as Figure 4, according to the equivalent circuit model, the capacitance data, resistance data, and constant phase angle component data of the ion exchange membrane are obtained, as shown in Table 1

[0059] The impedance fitting diagram and related impedance data of the tested films in the above embodiment are as follows: Figure 4 Same as Table 1.

[0060] Table 1. Obtained from different equivalent circuits Figure 4 The impedance spectrum fitting results shown in

[0061]

[0062] Through the above embodiment, the impedance test of the diffusion layer and boundary layer of the contaminated ion exchange membrane was realized, and the data of the influence degree of different pollution systems and different pollution concentrations on the migration resistance of ions in the membrane were obtained. The above embodiment shows that as the concentration of the contaminated liquid increases, the resistance R of the contaminated membrane increases. m In the increase, the double layer resistance R of the polluted membrane eal and diffusion layer resistance R dbl Both increase, indicating that due to the increase in the resistance of the double electrical layer and the diffusion layer of the contaminated cation exchange membrane, the electrical migration of ions in the double electrical layer and the diffusion layer of the membrane is hindered, which reduces the migration efficiency and leads to a decrease in the membrane desalination performance. This also indirectly shows that the contamination of CaCl2 and CaSO4 solutions mainly occurs on the membrane surface, which changes the properties of the cation exchange membrane surface, causing it to lose its ion exchange membrane properties and making the path of ion migration in the solution more difficult and complicated. In addition, when the contaminated liquid is at the same concentration, the cation exchange membrane contaminated by CaSO4 exhibits a higher membrane resistance value than the membrane contaminated by CaCl2, and the diffusion layer resistance R dbl And the pollution layer resistance R p This indicates that the types and modes of contamination caused by CaCl2 and CaSO4 on cation exchange membranes are different. The contaminated membrane caused by CaSO4 has a thicker diffusion layer, which makes ion migration more difficult, and the scaling on the membrane has a greater barrier to ion migration. This indicates that membranes contaminated by CaCl2 and CaSO4 have different cleaning and repair methods, which provides a theoretical basis for the proposal of repair methods for contaminated membranes.

[0063] From Table 1 we can see that: p and R m+s The larger the value, the more serious the pollution of the ion exchange membrane; p and R m+s If the value is less increased than that of pure membrane, it is judged as light pollution; if the value is highly increased, it is judged as heavy pollution.

[0064] Comparative Example 1:

[0065] The ion exchange membrane to be tested is tested using a membrane pollution characterization method for a forward osmosis membrane, wherein the membrane pollution characterization method for a forward osmosis membrane comprises: obtaining impedance data, constructing an equivalent circuit of the forward osmosis membrane through the impedance data, wherein the equivalent circuit model includes an equivalent resistance R of the electrolyte in the preset electrolytic cell s , the equivalent capacitance C1 of the forward osmosis membrane, the equivalent resistance R of the forward osmosis membrane m , the inductance L1 of the forward osmosis membrane and the equivalent resistance R1 of the inductance, where the equivalent resistance R s In series with the equivalent capacitor C1, the equivalent capacitor C1 and the equivalent resistor R m In parallel, the inductor L1 is connected in series with the equivalent resistor R1 and then connected in parallel with the equivalent resistor R m The impedance data of the ion exchange membrane that has been measured is fitted with the equivalent circuit in the membrane pollution characterization method of the forward osmosis membrane. Figure 7a , the impedance data of the ion exchange membrane test is fitted using the equivalent circuit model in this application. Figure 7b ,from Figure 7a It can be clearly seen that the forward osmosis membrane pollution characterization method cannot fit the test data of the ion exchange membrane, nor can it accurately obtain the data of the membrane, double layer and diffusion layer. Therefore, the ion exchange membrane cannot be characterized using the forward osmosis membrane characterization method.

[0066] Another aspect of the present invention provides an online monitoring method for characterizing ion exchange membrane contamination. The online monitoring method is based on an online monitoring device for ion exchange membrane contamination, comprising:

[0067] 1) Place the ion exchange membrane to be monitored between two L-shaped ceramic core salt bridge separators and place a platinum electrode sheet. Place other ion exchange membranes in the order of electrodialysis.

[0068] 2) The silver chloride electrode is placed in an L-shaped ceramic core salt bridge, and then one silver chloride electrode is connected to the reference electrode on a specific channel of the electrochemical workstation of Princeton Applied Research, the platinum electrode close to the silver chloride electrode is connected to the counter electrode of the channel, the other silver chloride electrode is connected to the sensing electrode (SE) on a specific channel of the electrochemical workstation, and the platinum electrode close to the silver chloride electrode is connected to the working electrode (WE) of the channel. Two ruthenium-plated titanium electrodes are connected to an external power supply.

[0069] 3) Prepare the pollutant solution and use a peristaltic pump to inject the solution into the entire test device at a rate of 20 ml / min.

[0070] 4) After the solution fills the device, turn on the external power supply to provide an electric field to the entire device.

[0071] 5) Open the Chronopotentiometry test project on the computer connected to the electrochemical workstation. The solution circulation is guaranteed during the whole process, and the changes in the current of the membrane during the contamination process can be monitored throughout the process.

[0072] In some embodiments, the ion exchange membrane pollution online monitoring device includes more than two compartments, and the compartments can be set to four or five. The number of the compartments is set according to the number of ion exchange membranes that need to be detected, wherein the ion exchange membrane to be detected is placed between two compartments, and a salt bridge is arranged in the two compartments, and the salt bridge is filled with an electrolyte solution, and an electrode is arranged in the electrolyte solution. Inert metal electrode sheets are arranged on the opposite back surfaces of the two compartments, and electrode plates are arranged on the sides of the two compartments at both ends. The two electrode plates are both compartment plates and can be used as electrode plates; the compartments are provided with water inlets and outlets, which can ensure the circulation of the solution during the test. This device can be tested in a state where the solution to be tested is circulating, or it can be tested in a state where the solution to be tested is not circulating.

[0073] Embodiment 2:

[0074] like Figure 3 As shown, the online monitoring device for ion exchange membrane pollution includes five compartments 1, two electrode plates 3 and two platinum electrode sheets 7, wherein the five compartments 1 and the two electrode plates 3 at both ends form a closed cavity. Two compartments 1 are equipped with a detachable L-shaped ceramic core salt bridge 2, and the silver chloride electrode 4 is immersed in the L-shaped ceramic core salt bridge 2 filled with 3.5 mol / L KCl solution, and the silver chloride electrode 4 is connected to the reference electrode and the sensing electrode of the electrochemical workstation. Two platinum electrode sheets 7 are inserted on both sides of the compartment 1 with the L-shaped ceramic core salt bridge 2, and the two platinum electrode sheets 7 are connected to the working electrode and the counter electrode of the electrochemical workstation. Two ruthenium-plated titanium electrode plates 3 are detachably arranged on the opposite surfaces of the two compartments 1 at both ends, and the ruthenium-plated titanium electrode plates 3 are connected to an external power supply to provide direct current for the entire device. The size of each compartment 1 is 60×60×30mm, and the size of the electrode plate 3 is 40×40×3mm. The device can accommodate two pairs of ion exchange membranes, one pair of which is placed between two compartments 1 with L-shaped ceramic core salt bridges 2, and the other pair of ion exchange membranes is placed between two other adjacent compartments 1. In addition, each compartment 1 is provided with a water inlet 5 and a water outlet 6, and the solution circulates through the water inlet 5 and the water outlet 6.

[0075] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for characterizing ion exchange membrane contamination, characterized in that: The steps include: S1. Obtaining impedance data of ion exchange membrane; S2. constructing equivalent circuit models of non-contaminated and contaminated ion exchange membranes based on the obtained impedance data; S3. Obtaining resistance data and capacitance data of the non-polluted and polluted ion exchange membranes according to the equivalent circuit model; S4. Determine the contamination degree of the ion exchange membrane based on the resistance data and the capacitance data.

2. A method for characterizing ion exchange membrane contamination according to claim 1, characterized in that: The method for characterizing ion exchange membrane contamination is based on an EIS test device, wherein the EIS test device is connected to an impedance analyzer, and the impedance analyzer performs an electrochemical impedance test on the ion exchange membrane in the preset EIS test device to obtain impedance data.

3. A method for characterizing ion exchange membrane contamination according to claim 2, characterized in that: The equivalent circuit model includes an equivalent circuit model of a pure ion exchange membrane, wherein the equivalent circuit model of the pure ion exchange membrane is a [R(RQ)(RQ)] model, wherein the [R(RQ)(RQ)] model includes an equivalent resistance R of an electrolyte in an electrolytic cell of an EIS test device. s , the equivalent resistance R of the ion exchange membrane m , the equivalent resistance R of the double layer of the ion exchange membrane ed1 And constant phase angle element Q ed1 , the equivalent resistance R of the diffusion layer of the ion exchange membrane db1 Its constant phase angle element Q db1 , where the equivalent resistance of the electrolyte solution is R s , the equivalent resistance R of the ion exchange membrane m , the equivalent resistance R of the double layer of the ion exchange membrane ed1 and the equivalent resistance R of the diffusion layer of the ion exchange membrane db1 In series, the equivalent resistance R of the double layer of the ion exchange membrane edl Its constant phase angle element Q edl Parallel connection, equivalent resistance R dbl Its constant phase angle element Q dbl in parallel.

4. A method for characterizing ion exchange membrane contamination according to claim 3, characterized in that: The equivalent circuit model includes an equivalent circuit model of a contaminated film, wherein the equivalent circuit model of the contaminated film is a [R(RQ) (RC) (RQ)] model, wherein the [R(RQ) (RC) (RQ)] model is a model in which an equivalent resistor R is connected in series with the [R(RQ) (RQ)] model. p , R p Then connect C in parallel D , where R p is the equivalent resistance of the contamination layer of the contaminated membrane, C p is the capacitance of the contamination layer of the contamination membrane.

5. An online monitoring method for characterizing ion exchange membrane contamination, characterized in that: The online monitoring method is based on an online monitoring device for ion exchange membrane pollution, and includes placing an ion exchange membrane to be tested in the online monitoring device for ion exchange membrane pollution, injecting a pollutant solution into the online monitoring device, and online monitoring the process of ion exchange membrane pollution.

6. The on-line monitoring method for characterizing ion exchange membrane contamination according to claim 5, characterized in that: The online monitoring device for ion exchange membrane pollution includes more than two compartments, wherein two compartments are provided with salt bridges, the salt bridges are filled with electrolyte solution, electrodes are provided in the electrolyte solution, inert metal electrode sheets are provided on the back surfaces of the two compartments, and electrode plates are provided on the sides of the two compartments at both ends.

7. The on-line monitoring method for characterizing ion exchange membrane contamination according to claim 6, characterized in that: The online monitoring device for ion exchange membrane pollution includes five compartments, wherein salt bridges are arranged in the two middle compartments, the salt bridges are filled with electrolyte solution, electrodes are arranged in the electrolyte solution, inert metal electrode sheets are arranged on the back surfaces of the two compartments, and electrode plates are arranged on the sides of the two compartments at both ends.

8. The on-line monitoring method for characterizing ion exchange membrane contamination according to claim 7, characterized in that: The salt bridge is an L-type ceramic core salt bridge.

9. The on-line monitoring method for characterizing ion exchange membrane contamination according to claim 7, characterized in that: The electrode plate is embedded in the ends of two compartments at both ends, the electrode plate is connected to the compartment in a detachable manner, and the electrode plate is an inert metal electrode plate.

10. The online monitoring method for characterizing ion exchange membrane contamination according to claim 8, characterized in that: Each of the compartments is provided with a water inlet and a water outlet.

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