Method for determining in-membrane concentration of membrane inlet side in micro-pollutant cross-nanofiltration membrane mass transfer process

Abstract

The invention discloses a method for determining the in-membrane concentration of a membrane inlet side in a micro-pollutant cross-nanofiltration membrane mass transfer process, and belongs to the technical field of membranes. The method comprises the following steps: measuring the membrane interception performance by using a cross-flow filtration device; carrying out desorption on the nanofiltration membrane after cross-flow filtration, and measuring the adsorption quantity of micropollutants; calculating by combining with a model, and solving a distribution coefficient for describing the non-electrostatic interaction between the micropollutants and the membrane; establishing a quantitative incidence relation between the distribution coefficient and the membrane adsorption capacity based on a large number of experiment fitting; and determining a non-electrostatic distribution coefficient by utilizing the incidence relation, and calculating the in-membrane concentration of the micropollutants at the membrane inlet side by combining a steric hindrance coefficient and a south coefficient. According to the method disclosed by the invention, quantitative expression of complex non-electrostatic interaction is realized by introducing adsorption quantity parameters which are relatively easy to measure, so that the accuracy of calculating the concentration in the membrane at the membrane inlet side is improved. An interaction mechanism between the micropollutants and the membrane can be deeply analyzed, and a reference is provided for selection and design optimization of a membrane material.

Description

Technical Field

[0001] This invention relates to the field of membrane technology, and in particular to a method for determining the concentration of micropollutants in the membrane on the inlet side during the mass transfer of micropollutants across a nanofiltration membrane. Background Technology

[0002] Nanofiltration membrane treatment technology has shown significant development potential in the field of micropollutant water treatment due to its advantages such as stable operation, low energy consumption, and no toxic byproduct generation. However, due to the wide variety and complex structure of micropollutants, existing nanofiltration technologies are not effective in removing some micropollutants. The transmembrane mass transfer process of micropollutants is affected not only by molecular size (steric hindrance effect) and charge properties (Downan effect), but also by hydrogen bonds, van der Waals forces, and other factors between the solute and the membrane. Complex non-electrostatic interactions, such as those between the membrane and the micro-pollutant membrane, also have a crucial impact. However, the widely used Dornan stereopore model (DSPM) and its modified models still lack a comprehensive description of these non-electrostatic interactions. This limitation leads to inaccurate calculations of micro-pollutant concentrations within the membrane, hindering further analysis of the transmembrane mass transfer mechanism of micro-pollutants and restricting the targeted design and control of the structure and function of next-generation nanofiltration membranes.

[0003] To address the aforementioned issues, there is an urgent need to develop a novel, efficient, and accurate method for quantifying the effects of non-electrostatic interactions, accurately calculating the intramembrane concentration of micropollutants during transmembrane mass transfer, and thus deepening our understanding of the transmembrane behavior of micropollutants. While existing studies have attempted to incorporate the potential impact of non-electrostatic interactions by modifying or supplementing parameters, most rely on time-consuming and complex experimental measurements for estimation. The quantitative correlations established by these methods are often limited to specific systems, restricting their application. Therefore, it is necessary to develop a general method that combines experimental measurements with mass transfer model calculations, directly correlating readily available membrane characteristic parameters with non-electrostatic partition coefficients, thereby quantitatively characterizing membrane-solute non-electrostatic interactions. This method is expected to overcome the limitations of existing models and provide a new tool for in-depth analysis of the mass transfer mechanism of micropollutants. Summary of the Invention

[0004] To address the technical challenges of characterizing non-electrostatic interactions and inaccurately calculating intramembrane concentrations during the mass transfer of micropollutants across nanofiltration membranes, this invention provides a method for determining the intramembrane concentration on the feed side during this process. The proposed method is characterized by its broad applicability, readily available parameters, and high coupling with mass transfer models. It enables the quantitative characterization of membrane-solute non-electrostatic interactions and accurate calculation of the feed side intramembrane concentration, providing new theoretical tools and technical support for elucidating the transmembrane mass transfer mechanism of micropollutants and guiding the design and optimization of membrane materials.

[0005] The purpose of this invention is to provide a method for determining the concentration of micro-pollutants on the inlet side of a nanofiltration membrane during mass transfer, comprising the following steps: S1. The membrane retention performance of nanofiltration membranes for micro-pollutants was determined using a cross-flow filtration device; S2. Desorb the nanofiltration membrane after cross-flow filtration in step S1 and measure the concentration of micro-pollutants in the desorbate. The membrane saturation adsorption capacity was obtained by calculation. and adsorption mass per unit volume of active layer ; S3. Based on the model calculation, solve for the partition coefficients that describe the non-electrostatic interaction between micro-pollutants and nanofiltration membrane; S4. Based on extensive experimental fitting, establish a quantitative correlation between the partition coefficient of the non-electrostatic interaction described in step S3 and the amount of micropollutants adsorbed by the nanofiltration membrane. S5. Use this correlation to determine the non-electrostatic distribution coefficient, and combine the steric hindrance coefficient and the Donnan coefficient to calculate the concentration of micro-pollutants inside the membrane on the inlet side. The calculation formula is as follows: , , ; in, Non-electrostatic interaction partition coefficient and membrane saturation adsorption capacity Quantitative correlation between them The thickness of the active layer of the nanofiltration membrane. This represents the external concentration of micro-pollutants on the inlet side of the membrane. The concentration of micro-pollutants inside the membrane on the inlet side. , and These are the steric hindrance allocation coefficient, the Dornan allocation coefficient, and the non-electrostatic interaction allocation coefficient, respectively.

[0006] In some embodiments of the present invention, in step S1, the cross-flow filtration duration is 12 to 24 hours; the cross-flow velocity is 0.05 to 0.5 m / s; the nanofiltration membrane pore size is in the nanometer range; and the membrane retention performance includes the influent concentration and effluent concentration of micropollutants.

[0007] In some embodiments of the present invention, in step S2, the desorption step involves: magnetically stirring the nanofiltration membrane obtained after cross-flow filtration in step S1 in an organic solvent at a speed of 50-150 rpm for 24-48 h, and analyzing the concentration of adsorbed solute in the desorption solution using high performance liquid chromatography or liquid chromatography-mass spectrometry.

[0008] In some embodiments of the present invention, in step S2, the membrane saturation adsorption amount and adsorption mass per unit volume of active layer The calculation formula is as follows: , ; in, For the effective filtration area of ​​the membrane, The thickness of the active layer of the membrane.

[0009] In some embodiments of the present invention, the steric hindrance allocation coefficient The calculation formula is as follows: , in, This represents the ratio of the Stokes radius of micropollutants to the pore radius of the nanofiltration membrane.

[0010] In some embodiments of the present invention, the Daonan allocation coefficient The calculation formula is as follows: , in, It is the charge of the solute. It is electron charge. It is Boltzmann's constant. It is absolute temperature. It is the potential difference between the inside and outside of the membrane, i.e., the Dornan potential, which is calculated by the ratio of the activities of the co-ion and counter-ion: , in, It is the ideal gas constant. It is Faraday's constant. and These refer to the solute concentrations in the bulk solution and inside the membrane, respectively. and It is the activity coefficient of the bulk solution and the solute in the membrane.

[0011] In some embodiments of the present invention, during cross-flow filtration, due to concentration polarization, there is a difference between the solute concentration at the membrane surface and the feed concentration, and the membrane surface concentration is: , Note: This membrane concentration is an approximate result calculated based on an empirical formula.

[0012] in, and These are the solute concentration in the feed solution and the water permeation flux, respectively. The mass transfer coefficient is obtained using Sherwood's Sh-related formula: , in, The hydraulic diameter of the filtration tank. The solute diffusion coefficient is... The density of the feed liquid, For cross-flow velocity, The dynamic viscosity coefficient of the feed liquid. This is the length of the filter tank.

[0013] In this invention, the feed liquid refers to the original solution used in the cross-flow filtration experiment, which contains micro-contaminants and other possible solutes.

[0014] Bulk solution refers to feed solution that is homogeneous in composition and far from the membrane surface and is not affected by the membrane surface boundary layer or concentration polarization.

[0015] In some embodiments of the present invention, step S3, the mass transfer process within the micro-pollutant membrane, i.e., the process of solving the partition coefficient describing the non-electrostatic interaction between the micro-pollutant and the nanofiltration membrane, is expressed as follows: , in, This represents the solute transmembrane flux. For the dimensionless position of the membrane, The dimensionless potential inside the membrane. and The retardation coefficients under convection and diffusion conditions are respectively calculated using the following formula: , , , , when hour, , when hour, , in, It is the charge of the solute. The mass of solute adsorbed per unit volume of the active layer of the membrane. The porosity of the active membrane layer; using the experimental results obtained in steps S1 and S2, the concentration inside the membrane on the inlet side can be solved by solving the above equations. , This represents the ratio of the Stokes radius of the micropollutant to the pore radius of the nanofiltration membrane; furthermore, the intramembrane ion concentration and the membrane volume charge density X satisfy the following relationship: , Among them, z cation,m and z anion c represents the charge of positively charged and negatively charged substances, respectively. cation,m and c anion,mThese represent the concentrations of positively charged and negatively charged substances, respectively. Combining membrane surface concentration and steric hindrance partition coefficient, Dornan partition coefficient, and formula This allows for the determination of the non-electrostatic partition coefficient under a specific membrane-micropollutant system. .

[0016] The intramembrane solute concentration is a variable representing the position along the membrane crossing direction, and the intramembrane concentration on the inlet side is x=0. + The concentration at time (i.e., the concentration inside the membrane on the inlet side) can be obtained by inverse solving these equations from experimental results.

[0017] In some embodiments of the present invention, in step S4, the quantitative correlation relationship is at least one of linear relationship, exponential relationship, logarithmic relationship or power function relationship.

[0018] The technical solution of the present invention has the following advantages compared with the prior art: Based on extensive experimental data, this invention establishes a quantitative correlation between the non-electrostatic partition coefficient and the adsorption capacity of micropollutants by nanofiltration membranes. By incorporating this relationship into a mass transfer model, combined with steric hindrance and Donnan coefficients, the intramembrane concentration of micropollutants on the feed side during transmembrane mass transfer can be accurately calculated. The method employed is simple to operate, with clear parameter acquisition pathways, and the calculation process is efficient and reliable, exhibiting good universality and reproducibility. This method helps to quantitatively characterize the complex non-electrostatic interactions between the membrane and the solute, deeply elucidate the transmembrane mass transfer mechanism of micropollutants, and provide new ideas and technical support for the structural design and functional optimization of high-performance nanofiltration membrane materials. Attached Figure Description

[0019] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 This is a schematic diagram of the operation process of the present invention; Figure 2 The results of the cross-flow filtration experiment for micro-pollutants are shown in the examples. Figure 3 The nanofiltration membrane in this example represents the saturated adsorption capacity for micropollutants. Figure 4 The non-electrostatic interaction partition coefficients are calculated based on experimental results in the examples; Figure 5 The figures show the fitting results of the non-electrostatic partition coefficient and the membrane adsorption amount in the examples; Figure 6 The results of the comparison of the concentration deviation on the membrane side calculated based on the correlation between the obtained non-electrostatic partition coefficient and the membrane adsorption amount are shown in the examples. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0021] The five nanofiltration membranes used in this invention are conventional nanofiltration membranes in the art, and their specific information is as follows: Commercially available NF270 nanofiltration membranes were used. Polyelectrolyte membranes were prepared on the surface of NF270 using a layer-by-layer self-assembly (LBL) method, alternating between polydimethyldiallylammonium chloride (PDADMAC) and polystyrene sulfonic acid (PSS). Depending on the number of layers, PE1 and PE were obtained. 1.5 Using a similar method, Fe-TA was prepared by coating the surface of NF270 with ferric chloride and tannic acid (TA), respectively. PEI-TA was prepared by coating the surface of NF270 with a mixture of polyethyleneimine (PEI) and tannic acid (TA) under alkaline conditions.

[0022] Example This embodiment provides a method for determining the concentration of micropollutants on the inlet side of the nanofiltration membrane during mass transfer, including the following steps: S1, using commercial polyamide nanofiltration membrane NF270 and four nanofiltration membranes PE1, PE 1.5 Cross-flow filtration experiments were conducted using PEI-TA and Fe-TA membranes. The membrane cells were 0.025 m in length and width, with a hydraulic diameter of 0.0037 m. The cross-flow velocity was 0.2 m / s, and the test temperature was 20℃. All four modified nanofiltration membranes were prepared by surface coating NF270 using commonly used surface modification reagents in the field. The rejection rate of each nanofiltration membrane for micropollutants, including p-chloroaniline (PCA), salicylic acid (SA), isopropylantipyrine (PPZ), carbamazepine (CBZ), and trimethoprim (TMP), was determined individually. The specific steps include: the feed solution contains 200 μg / L micropollutants and 100 mg / L sodium chloride; all nanofiltration membranes are soaked in ultrapure water for 24 h before use, and pre-compacted in a cross-flow filtration unit using ultrapure water at 10 bar pressure for 2 h, followed by filtration with the feed solution at 5 bar pressure for 12 h. After filtration, the feed solution and leachate are collected, and the concentration of micropollutants is determined using high-performance liquid chromatography (HPLC). During the cross-flow filtration process, the leachate and concentrate are recycled back to the feed solution. Various membranes exhibit different micropollutant rejection rates, such as... Figure 2 As shown.

[0023] S2, desorb the nanofiltration membrane after the cross-flow filtration experiment in step S1. After removing the nanofiltration membrane, use lint-free paper to remove residual solution from the membrane surface. Immerse the membrane in 20 mL of methanol and magnetically stir at 50 rpm for 24 h. Take the desorption solution and determine the concentration of micro-contaminants in the desorbate using high-performance liquid chromatography (HPLC). Then, through... The membrane saturation adsorption capacity was calculated. The results are as follows: Figure 3 As shown.

[0024] S3, combining the membrane property parameters such as nanofiltration membrane pore radius, water permeability coefficient, and charge density with the experimental data obtained in steps S1 and S2, calculates the non-electrostatic partition coefficients between the four modified nanofiltration membranes and different micropollutants. The results are as follows: Figure 4 As shown.

[0025] The detailed calculation process is as follows: , in, and These represent the external and internal concentrations of micropollutants on the inlet side of the membrane. , and These are the steric hindrance allocation coefficient, the Dornan allocation coefficient, and the non-electrostatic interaction allocation coefficient, respectively.

[0026] Potential resistance distribution coefficient The ratio of the Stokes radius of micro-pollutants to the pore radius of the nanofiltration membrane can be used. Solve the following: , At the membrane surface, charged solutes are affected by the Donnan potential, which can be expressed by the Donnan partition coefficient as follows: , in, It is the charge of the solute. It is electron charge. It is Boltzmann's constant. It is absolute temperature; The potential difference between the inside and outside of the membrane, i.e., the Dornan potential, can be calculated from the ratio of the activities of the co-ion and counter-ion: , in, It is the ideal gas constant. It is Faraday's constant. and These are the solute concentrations in the bulk solution and inside the membrane, respectively. and This is the activity coefficient. In addition, the intramembrane solute concentration and membrane volume charge density... The following relationship must be satisfied: , Among them, z cation,m and z anion c represents the charge of positively charged and negatively charged substances, respectively. cation,m and c anion These represent the concentrations of positively charged and negatively charged substances, respectively. In cross-flow filtration, due to concentration polarization, there is a difference between the solute concentration at the membrane surface and the feed concentration. It can be approximated as: , in, and These represent the solute concentration in the feed solution and the water permeation flux, respectively. The mass transfer coefficient can be obtained from Sherwood ( Related findings: , in, The hydraulic diameter of the filtration tank. The solute diffusion coefficient is... The density of the feed liquid, For cross-flow velocity, denoted as the dynamic viscosity coefficient of the feed liquid, and L as the length of the filter tank.

[0027] The mass transfer process of micro-pollutants within the membrane can be represented as: , in, This represents the solute transmembrane flux. For the dimensionless position of the membrane, This represents the dimensionless potential within the membrane. and The retardation coefficients under convection and diffusion conditions are respectively, and can be calculated using the following formula: , , , , when hour, , when hour, , in, The mass of solute adsorbed per unit volume of the active layer of the membrane. The porosity of the active membrane layer is given. Using the experimental results obtained in steps S1 and S2, the concentration inside the membrane on the inlet side can be calculated by simultaneously solving the above equations. This, combined with the membrane surface concentration, steric hindrance, Donald distribution coefficient, and the formula... The non-electrostatic partition coefficients of a specific membrane-micropollutant system can then be determined.

[0028] S4. The saturated adsorption capacity of the four modified nanofiltration membranes obtained in step S2 is fitted with the non-electrostatic partition coefficients between the corresponding nanofiltration membranes and micropollutants calculated in step S3. The results are as follows: Figure 5 As shown, numerous experimental results demonstrate a quantitative correlation between the membrane saturation adsorption capacity and the partition coefficient proposed in this invention to describe non-electrostatic interactions. And the fitting effect is good (R 2 =0.80).

[0029] S5. Based on the quantitative correlation between the membrane saturated adsorption capacity and the non-electrostatic partition coefficient obtained in step S4, calculate the inlet-side membrane concentrations of five micropollutants (PCA, SA, PPZ, CBZ, and TMP) during mass transfer across the NF270 nanofiltration membrane under the same cross-flow filtration conditions as in step S1. The detailed calculation process is as follows: , , in, and These represent the concentrations of micropollutants outside and inside the membrane on the inlet side, respectively. , and These are the partition coefficients for steric hindrance, Donald's effect, and non-electrostatic interaction, respectively. The steric hindrance partition coefficient can be obtained by comparing the ratio of the Stokes radius of the micro-pollutant to the pore radius of the nanofiltration membrane. Please solve: , At the membrane surface, charged solutes are affected by the Donnan potential, which can be expressed by the Donnan partition coefficient as follows: , in, It is the charge of the solute. It is electron charge. It is Boltzmann's constant. It is absolute temperature. The potential difference between the inside and outside of the membrane, i.e., the Dornan potential, can be calculated from the ratio of the activities of the co-ion and counter-ion: , in, It is the ideal gas constant. It is Faraday's constant. and These are the solute concentrations in the bulk solution and inside the membrane, respectively. and This is the activity coefficient. Since the membrane itself remains electrically neutral, the ion concentration within the membrane is affected by the membrane's volume charge density. Limitations: , In cross-flow filtration, due to concentration polarization, there is a difference between the solute concentration at the membrane surface and the feed concentration. The membrane surface concentration can be approximately estimated as follows: , in, and These represent the solute concentration in the feed solution and the water permeation flux, respectively. The mass transfer coefficient can be obtained from Sherwood ( Related findings:

[0030] in, The hydraulic diameter of the filtration tank. The solute diffusion coefficient is... The density of the feed liquid, For cross-flow velocity, The dynamic viscosity coefficient of the feed liquid. This is the length of the filter tank.

[0031] The calculated concentration of micropollutants on the inlet side of the membrane, considering non-electrostatic interactions, was compared with the calculated value obtained through step S3 based on the cross-flow filtration experimental results to verify the accuracy of the method. For comparison, the membrane concentration without considering non-electrostatic interactions was calculated using the same approach. Similarly, the calculated value obtained through step S3 based on the cross-flow filtering experiment results is compared with the calculated value obtained through step S3. The closer the ratio of the directly calculated value from the model to the calculated value obtained through step S3 based on the cross-flow filtering experiment results is to 1, the more accurate the model's calculation effect. The results are as follows... Figure 6 As shown, based on the numerical relationship obtained in step S4, the non-electrostatic partition coefficients of the NF270 nanofiltration membrane and five micropollutants were determined by the membrane saturation adsorption capacity. After incorporating these partition coefficients into the model calculation, the accuracy of the prediction of micropollutant concentrations on the inlet side of the membrane was significantly improved compared with the case where non-electrostatic interactions were not considered, thus verifying the reliability and universality of the method.

[0032] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for determining the concentration of micropollutants on the inlet side of a nanofiltration membrane during mass transfer, characterized in that, Includes the following steps: S1. The membrane retention performance of nanofiltration membranes for micro-pollutants was determined using a cross-flow filtration device; S2. Desorb the nanofiltration membrane after cross-flow filtration in step S1 and measure the concentration of micro-pollutants in the desorbate. The membrane saturation adsorption capacity was obtained by calculation. and adsorption mass per unit volume of active layer ; S3. Based on the model calculation, solve for the partition coefficients that describe the non-electrostatic interaction between micro-pollutants and nanofiltration membrane; S4. Based on extensive experimental fitting, establish a quantitative correlation between the partition coefficient of the non-electrostatic interaction described in step S3 and the amount of micropollutants adsorbed by the nanofiltration membrane. S5. Use this correlation to determine the non-electrostatic distribution coefficient, and combine the steric hindrance coefficient and the Donnan coefficient to calculate the concentration of micro-pollutants inside the membrane on the inlet side. The calculation formula is as follows: ， ， ； in, Non-electrostatic interaction partition coefficient and membrane saturation adsorption capacity Quantitative correlation between them The thickness of the active layer of the nanofiltration membrane. This represents the external concentration of micro-pollutants on the inlet side of the membrane. The concentration of micro-pollutants inside the membrane on the inlet side. , and These are the steric hindrance allocation coefficient, the Dornan allocation coefficient, and the non-electrostatic interaction allocation coefficient, respectively.

2. The method according to claim 1, characterized in that, In step S1, the cross-flow filtration duration is 12 to 24 hours; the cross-flow velocity is 0.05 to 0.5 m / s; the nanofiltration membrane pore size is in the nanometer range; and the membrane retention performance includes the influent concentration and effluent concentration of micropollutants.

3. The method according to claim 1, characterized in that, In step S2, the desorption step involves magnetically stirring the nanofiltration membrane obtained after cross-flow filtration in the organic solvent at 50-150 rpm for 24-48 h. The resulting solution is then analyzed using high-performance liquid chromatography or liquid chromatography-mass spectrometry to determine the concentration of adsorbed solute in the desorption solution.

4. The method according to claim 1, characterized in that, In step S2, the membrane saturation adsorption capacity and adsorption mass per unit volume of active layer The calculation formula is as follows: ， ； in, For the effective filtration area of ​​the membrane, The thickness of the active layer of the membrane.

5. The method according to claim 1, characterized in that, The steric hindrance distribution coefficient The calculation formula is as follows: ， in, This represents the ratio of the Stokes radius of micropollutants to the pore radius of the nanofiltration membrane.

6. The method according to claim 1, characterized in that, The south allocation coefficient The calculation formula is as follows: ， in, It is the charge of the solute. It is electron charge. It is Boltzmann's constant. It is absolute temperature. It is the potential difference between the inside and outside of the membrane, i.e., the Dornan potential, which is calculated by the ratio of the activities of the co-ion and counter-ion: ， in, It is the ideal gas constant. It is Faraday's constant. and These refer to the solute concentrations in the bulk solution and inside the membrane, respectively. and It is the activity coefficient of the bulk solution and the solute in the membrane.

7. The method according to claim 1, characterized in that, During cross-flow filtration, due to concentration polarization, there is a difference between the solute concentration at the membrane surface and the feed concentration. The membrane surface concentration is: ， in, and These are the solute concentration in the feed solution and the water permeation flux, respectively. The mass transfer coefficient is obtained using Sherwood's Sh-related formula: ， in, The hydraulic diameter of the filtration tank. The solute diffusion coefficient is... The density of the feed liquid, For cross-flow velocity, The dynamic viscosity coefficient of the feed liquid. This is the length of the filter tank.

8. The method according to claim 1, characterized in that, In step S3, the mass transfer process of micro-pollutants within the membrane is represented as follows: ， in, This represents the solute transmembrane flux. For the dimensionless position of the membrane, The dimensionless potential inside the membrane. and The retardation coefficients under convection and diffusion conditions are respectively calculated using the following formula: ， ， ， ， when hour, ， when hour, ， in, It is the charge of the solute. The mass of solute adsorbed per unit volume of the active layer of the membrane. The porosity of the active membrane layer; using the experimental results obtained in steps S1 and S2, the concentration inside the membrane on the inlet side can be solved by simultaneously solving the above equations. , This represents the ratio of the Stokes radius of the micropollutant to the pore radius of the nanofiltration membrane; furthermore, the intramembrane ion concentration and the membrane volume charge density X satisfy the following relationship: ， Among them, z cation,m and z anion c represents the charge of positively charged and negatively charged substances, respectively. cation,m and c anion,m These represent the concentrations of positively charged and negatively charged substances, respectively. Combining membrane surface concentration and steric hindrance partition coefficient, Dornan partition coefficient, and This allows for the determination of the non-electrostatic partition coefficient under a specific membrane-micropollutant system. .

9. The method according to claim 1, characterized in that, In step S4, the quantitative correlation relationship is at least one of linear, exponential, logarithmic, or power function relationships.

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