COFs composite membrane based on multi-scale simulation, preparation method and application

Abstract

The invention discloses a COFs composite membrane based on multi-scale simulation, a preparation method and application, and belongs to the technical field of theoretical computation.The COFs composite membrane based on multi-scale simulation is prepared by simulating interaction energy between polymers and COFs at the full-atomic scale, then simulating data of the polymer-COFs membrane at the overall and mesoscale by taking molecular fragments as a whole, and then replacing different membrane-forming polymers to obtain the COFs composite membrane based on multi-scale simulation. The method comprises the following steps: by taking COFs as a raw material, simulating the influence of the COFs on compatibility and a membrane structure, changing solvent types, simulating the influence of the COFs on a phase separation behavior and a pore structure in a membrane forming process, finally obtaining a simulated polymer-COFs, and preparing and verifying a theoretical result; the COFs composite membrane prepared through the simulation method is applied to a water body containing heavy metal ions, selective adsorption of gold ions is achieved, the composite membrane can be recycled for 5 times or above, and the Au < 3 + > adsorption amount still keeps 85% or above of the initial value.

Description

Technical Field

[0001] This invention relates to the field of theoretical calculation technology, specifically to the design and preparation of COFs composite membranes based on multi-scale simulation and their application in the selective adsorption of gold ions. Background Technology

[0002] With the development of industries such as gold mining and electronic waste dismantling, the discharge of wastewater containing heavy metal ions (especially gold ions) poses a serious threat to the environment. At the same time, as a high-value precious metal, gold has significant economic value in its efficient recycling.

[0003] Currently, covalent organic frameworks (COFs) have shown potential in the adsorption of heavy metal ions due to their regular pores and tunable functional groups. However, the preparation of existing COF composite membranes largely relies on experimental trial and error, which has the following shortcomings: The compatibility of COFs with polymer matrices lacks precise prediction, leading to agglomeration and resulting in uneven pore structure in the composite membrane, making it difficult to achieve both adsorption selectivity and flux. Furthermore, the design of gold ion adsorption sites lacks molecular-level guidance, resulting in insufficient selective adsorption of gold ions and the coexistence of metal ions (such as Cu). 2+ Pb 2+ Cd 2+ It is prone to interference; the efficiency of optimizing experimental parameters is low, and the screening of parameters such as temperature, concentration, and solvent depends on a large number of repeated experiments, resulting in a long research and development cycle.

[0004] Currently, COFs materials have become a research hotspot in the field of heavy metal ion adsorption due to their regular channels and tunable functional groups. Among them, TpPa series COFs (such as TpPa, TpBD, etc.) bind to Au through imine bonds, phenolic hydroxyl groups, and other functional groups. 3+ Coordination occurs, showing certain adsorption potential. However, pure COFs powder has problems such as easy agglomeration, difficulty in recovery, and poor dispersibility in water, which has promoted the research and development of COFs composite membranes.

[0005] Current methods for preparing COF composite membranes mainly rely on experimental trial-and-error approaches such as physical blending and in-situ growth. Physical blending often involves simply mixing COF powder with polymers such as polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF). However, the compatibility between COF and the polymer matrix lacks precise prediction, and aggregation easily occurs when the doping concentration exceeds 10 wt%, leading to uneven membrane pore size and Au content. 3+ It is difficult to simultaneously achieve high adsorption flux and selectivity; the in-situ growth method generates a COF layer on the polymer surface through interfacial polymerization, but crystal defects are prone to occur during the growth process, affecting Au. 3+ The selective adsorption coefficient is mostly below 30.

[0006] In terms of simulation technology applications, existing research mostly remains at a single scale: all-atom simulations are only used to calculate the effect of COFs on Au. 3+ The adsorption energy was not correlated with the compatibility of COFs and polymers and the macroscopic properties of the membrane; the mesoscopic simulation multi-focus membrane structure characterization did not incorporate kinetic parameters to guide actual processes. Overall, existing technologies lack a systematic approach for multi-scale simulation and co-design, failing to accurately guide the component matching and structural optimization of COFs composite membranes, leading to Au... 3+ The improvement in adsorption performance is limited, and the adsorption capacity decreases by more than 20% after three regeneration cycles.

[0007] Therefore, there is an urgent need for a COFs composite membrane design method based on precise simulation guidance to achieve efficient and selective adsorption of gold ions. Summary of the Invention

[0008] This invention precisely designs a composite system of TpPa-based COFs and polymers from three dimensions: high-precision density functional theory (DFT), all-atom simulation, and coarse-grained mesoscopic modeling. It screens the optimal matching polymer matrix and process parameters to prepare a COFs composite membrane with ultra-high selectivity for gold ions, solving the problems of high trial-and-error costs and poor adsorption performance in existing technologies.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: A COFs composite membrane based on multi-scale simulation was obtained through the following steps: S1. Perform full atomic-scale simulations to screen COFs that are compatible with Au. 3+ Polymers with selective adsorption properties; S2. Perform mesoscale simulations to screen the relationship between the amount of COFs added and the porosity of the composite membrane; S3. Based on the simulation results of S1 and S2, the structure and composition of the polymer-COFs composite membrane are determined.

[0010] Furthermore, step S1 includes: S101. Construct polymer molecular chain models and COF crystal molecular models; S102. Calculate the interaction energy and segment diffusion coefficient between COFs and polymers; S103. Screening polymer-COF combinations with interaction energies of -200 to -400 kJ / mol; S104. Based on the results of S103, calculate the effect of polymer-COFs on Au. 3+ And the adsorption energy of at least one coexisting metal ion, to screen for Au 3+ The adsorption energy of polymer-COFs is 20 to 80 kJ / mol higher than that of coexisting metal ions.

[0011] Furthermore, the molecular simulation calculations in step S102 are performed using ORCA, CP2K, and GROMACS.

[0012] Furthermore, ORCA uses the DFT-based M06-2X / 6-31+G* method to calculate the interaction energy of gas-phase molecular complexes; CP2K uses the DFT-based PBE-D3 / TZVP method to calculate the interaction energy of periodic materials; and GROMACS uses the OPLS force field to perform all-atom molecular dynamics simulations to calculate the chain segment diffusion coefficient.

[0013] Furthermore, step S2 includes: S201. Based on the polymer-COF combination screened in S1, construct an all-atom initial mixing system model, perform molecular dynamics simulations until system equilibrium, and extract the all-atom non-bonded interaction energy and radial distribution function. S202. Based on the data from S201, calculate the interaction strength ε and particle radius σ of the Lennard-Jones potential to coarsen the polymer-COFs. S203. Based on the results of S202, construct a polymer-COF mesoscopic model to simulate the solvent evaporation film formation process or equilibrium film structure, and perform pore analysis. S204. Screening polymer-COF combinations with a porosity of 20-60% when the COF doping amount is 0.1-30 wt%.

[0014] Furthermore, the polymer-COFs composite membrane is selected from: PAN / TpBD-COFs, PVDF / TpBD-Me2-COFs or PES / TpPa-COFs.

[0015] A method for preparing a COFs composite membrane based on multi-scale simulation includes the following steps: Preparation of COFs precursors: Organic aldehyde monomers and organic amine monomers are mixed at a molar ratio of 1:(0.8~1.2), dissolved in solvent, and reacted at 50~200℃ for 6~24 h. After separation, washing and drying, COFs powder is obtained. Preparation of casting solution: Dissolve the polymer in a solvent, add 0.1~30 wt% COFs powder, stir at 25~80℃ for 1~12 h, ultrasonically disperse for 0.5~6 h and then degas to obtain a uniform casting solution; Composite film forming: The casting solution is made into a base film by casting, scraping, electrospinning or dip-coating method, and then heat-treated at 50~300℃ for 1~12 h; Crosslinking treatment: Immerse the base film in a crosslinking agent solution and react at 50~150℃ for 1~8 h to obtain a COFs composite film.

[0016] Furthermore, the organic aldehyde monomer is 2,4,6-tricarboxymethyl phloroglucinol, and the organic amine monomer is selected from at least one of p-phenylenediamine, benzylenediamine, 2,2'-bipyridine-5,5'-diamine or 2-amino-p-phenylenediamine; the solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or acetone.

[0017] Furthermore, the polymer is selected from at least one of polyimide (PI), polyamide (PA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyethersulfone (PES), or polyetherketone (PEEK).

[0018] Application of a COFs composite membrane based on multi-scale simulation in the selective adsorption of gold ions in water containing heavy metal ions.

[0019] The beneficial effects of this invention are as follows: The COFs composite membrane prepared using the simulation method of this invention is applied to water containing heavy metal ions to achieve selective adsorption of gold ions. The composite membrane can be recycled more than 5 times. 3+ The adsorption capacity remains above 85% of the initial value. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the molecular structure of the TpPa-COFs series.

[0021] Figure 2 For polymer-COFs to Au 3+ Pb 2+ Cu 2+ Cd 2+ The adsorption energy curve.

[0022] Figure 3 The composite membranes of Examples 1-3 are for Au 3+ The adsorption capacity bar chart.

[0023] Figure 4 Au 3+ A comparison chart of selectivity coefficients relative to other metal ions. Detailed Implementation

[0024] Figure 1 The molecules in the first row are monomers used in the synthesis of COFs, abbreviated as Tp. The molecules in the second row (Pa, BD, etc.) polymerize to form various types of COFs, such as TpPa and TpBD. This invention aims to calculate the relationship between the polymer-COF complex and Au. 3+The adsorption energy of coexisting metal ions; "TpPa, TpBD, TpBD-Me2, TpBD-(OMe)2 and TpTGcl" are themselves COFs, various types of COFs.

[0025] COFs composite membrane design method based on multi-scale simulation S1 Full Atom-Scale Simulation (Screening Matching Systems) S101 Model Construction: COF crystal molecular model and polymer molecular chain model were constructed in the software Avogadro; COFs are selected from one or more of TpPa, TpBD, TpBD-Me2, TpBD-(OMe)2 and TpTGcl; The polymer is selected from one or more of PI, PA, PAN, PVDF, PES, and PEEK.

[0026] S102 compatibility screening: molecular simulations using ORCA, CP2K, and GROMACS were performed. The software simulates the cluster model of COFs and polymers, and calculates the interaction energy between the COF crystal molecular model and the polymer molecular chain model; The periodic model of COFs and polymers is simulated in the software to calculate the interaction energy and segment diffusion coefficient of the COF crystal molecular model and the polymer molecular chain model.

[0027] S103 screens COFs and polymer combinations with interaction energies of -200 to -400 kJ / mol to ensure excellent compatibility between the two. High interaction energy ensures compatibility, which is common knowledge in this field.

[0028] Among them, ORCA obtained high-precision interaction energy of gas-phase molecular complexes based on DFT's M06-2X / 6-31+G* method, CP2K obtained interaction energy of periodic materials based on DFT's PBE-D3 / TZVP method, and GROMACS simulated segment diffusion coefficients at the whole atomic scale based on OPLS force field.

[0029] S104 Adsorption Site Optimization: Based on the results of S103, the adsorption sites of polymer-COFs on Au were calculated using Monte Carlo simulations (using MUSIC, RASPA, etc.). 3+ And the adsorption energy of coexisting metal ions, screening Au 3+ It can adsorb polymer-COFs with adsorption energies 20 to 80 kJ / mol higher than other metal ions, ensuring selectivity.

[0030] Step S2: Mesoscale simulation (predicting and optimizing the microstructure of the composite membrane) Objective: Based on the optimal polymer-COF combination screened by S1, a coarse-grained mesoscopic model of COFs, film-forming polymer matrix, and solvent is established to simulate the dispersion behavior and aggregated structure of COFs during film formation, thereby predicting and optimizing the microstructure of the composite film and providing a theoretical basis for actual preparation process parameters.

[0031] S201: Constructing an initial all-atom model and simulation The optimal polymer-COFs selected by S1 were used as the core. The polymer-COFs were regarded as functional units, and the data of functional units and solvent molecules were simulated to construct an all-atom initial mixing system model.

[0032] Using GROMACS software, molecular dynamics simulations were performed on the all-atom initial mixture model to extract the all-atom non-bonded interaction energies, including van der Waals forces and electrostatic interaction energies; the all-atom radial distribution function (RDF) was extracted to characterize the spatial distribution correlation of all atoms.

[0033] S202: Coarse-grained mapping scheme formulation Using the potential energy matching method or the inverse Monte Carlo (IMC) method, based on the all-atom data extracted from S201, the interaction strength ε of the Lennard-Jones potential and the particle radius σ are calculated. The 1-10 structural units of polymer-COFs are mapped to a single coarse-grained particle.

[0034] Map 1-10 solvent molecules to a coarse-grained particle.

[0035] This mapping significantly reduces the number of particles in the system, allowing for the simulation of larger-scale systems.

[0036] S203: Mesoscale Structural Simulation and Performance Prediction Based on the S202 simulation results, a mesoscopic model of the functional unit and solvent is constructed, and the dynamic process of solvent evaporation to form a film is simulated, or the microstructure of the composite film under equilibrium conditions is simulated.

[0037] Analyze the distribution of polymer-COF functional units in the solvent. Observe whether they are uniformly dispersed or form aggregates, and calculate the size distribution of the aggregates.

[0038] Pore ​​analysis was performed on the final mesoscopic structure model to calculate the theoretical porosity, pore size distribution, and connectivity of the membrane.

[0039] By analyzing the diffusion paths of solvent coarsened particles, the possible mass transfer channels within the membrane can be visually demonstrated.

[0040] S204: Process Parameter Optimization and Screening Based on the mesoscopic model established using S203, the following variables were systematically changed to study their effects on the membrane structure: The COF doping amount was used to simulate the changes in COF dispersion and membrane pore structure under different addition amounts.

[0041] By changing the type of solvent, we simulated its effect on phase separation behavior and pore structure during film formation.

[0042] When the COFs doping amount is 0.1~30wt%, the optimal structure has a porosity of 20~60%, uniform texture, and no phase separation.

[0043] S3 obtained the final confirmed polymer-COFs through calculation.

[0044] The polymer-COFs are PAN / TpBD-COFs, PVDF / TpBD-Me2-COFs, and PES / TpPa-COFs.

[0045] Preparation method of COFs composite membrane Based on the above simulation screening results, the composite membrane was prepared using the following steps: Preparation of TpPa-based COFs precursor: Organic aldehyde monomers and organic amine monomers are mixed at a molar ratio of 1:(0.8~1.2), and one or more mixed solvents selected from N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and acetone are added until dissolved. The mixture is reacted at 50~200 °C for 6~24 h, and obtained by centrifugation, washing, and drying. The organic aldehyde monomer is 2,4,6-tricarboxymethylphloroglucinol.

[0046] The organic amine monomer is selected from p-phenylenediamine, biphenylenediamine, 2,2'-bipyridine-5,5'-diamine, and 2-amino-p-phenylenediamine.

[0047] Preparation of casting solution: The selected polymer (at least one selected from polyimide PI, polyamide PA, polyacrylonitrile PAN, polyvinylidene fluoride PVDF, polyethersulfone PES, and polyetherketone PEK) is dissolved in one or more mixed solvents selected from N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and acetone. 0.1-30 wt% of TpPa-based COFs powder is added, and the mixture is stirred at 100-2000 rpm for 1-12 h at 25-80 °C. After ultrasonic dispersion for 0.5-6 h, the mixture is degassed to obtain a uniform casting solution. Composite membrane forming: The casting solution is used to form a base membrane by casting, blade coating, electrospinning or dip-coating method, and then heat-treated at 50~300 ℃ for 1~12 h; optional crosslinking treatment: The base membrane is immersed in one or more crosslinking agent solutions of ethylenediamine, melamine, epichlorohydrin, and reacted at 50~150 ℃ for 1~8 h to obtain COFs composite membrane.

[0048] Example 1: Preparation and application of PAN / TpBD-COFs composite membrane Simulation screening: Molecular dynamics simulations show that the interaction energy between PAN and TpBD-COFs is -280 to -320 kJ / mol, indicating excellent compatibility; Monte Carlo simulations show that TpBD-COFs interact with Au... 3+ The adsorption energy is -420 to -480 kJ / mol, which is much higher than that of Cu. 2+ -50 to -200 kJ / mol; mesoscopic simulations show that the film structure is optimal when the COFs doping amount is 10 to 20 wt%. Composite membrane preparation: PAN was dissolved in DMF, 10-20 wt% of TpBD-COFs powder was added, and the mixture was stirred at 500-1500 rpm for 3-8 h at 30-60℃. After ultrasonic dispersion for 1-3 h, the membrane was degassed. The membrane was formed by casting and heat-treated at 100-200℃ for 2-6 h. Gold ion adsorption experiment: Take Au-containing... 3+ 5~20 mg / L, Cu 2+ Simulated wastewater with concentrations of 10–30 mg / L was treated, and the pH was adjusted to 3–6. The composite membrane was then contacted with the wastewater at 20–40 °C for 2–12 h. The results showed that Au 3+ The adsorption capacity is 120~180 mg / g, Au 3+ With Cu 2+ The selectivity coefficient is 55-70; after 5 regenerations, the adsorption capacity still maintains more than 88% of the initial value.

[0049] Example 2: Preparation and application of PVDF / TpBD-Me2-COFs composite membrane Simulation screening: The interaction energy between PVDF and TpBD-Me2-COFs is -220 to -320 kJ / mol. The interaction energy of TpBD-Me2-COFs with Au... 3+ The adsorption energy is -380 to -450 kJ / mol, which is superior to that of Pb. 2+ -180 to -220 kJ / mol; Composite membrane preparation: PVDF is dissolved in DMAc, 5~15wt% of TpBD-Me2-COFs powder is added, and the mixture is stirred at 300~1800 rpm for 2~10 h at 40~70℃, and ultrasonically dispersed for 0.5~4 h; after being coated into a film, it is heat-treated at 150~250 ℃ for 1~8 h. Gold ion adsorption experiment: containing Au 3+ 3~15mg / L, Pb 2+ Wastewater with a concentration of 15-40 mg / L, pH 2-5, temperature 15-35℃, and contact time 1-10 h; Au 3+ The adsorption capacity is 100~160 mg / g, Au 3+ With Pb 2+ The selectivity coefficient is 50~65.

[0050] Example 3: Preparation and application of PES / TpPa-COFs composite membrane Simulation screening: The interaction energy between PES and TpPa-COFs is -200 to -300 kJ / mol, and the interaction energy between TpPa-COFs and Au... 3+ The adsorption energy is -350 to -420 kJ / mol, which is much higher than that of Cd. 2+ -150 to -200 kJ / mol; Composite membrane preparation: PES was dissolved in DMSO, and 15-25 wt% of TpPa-COFs powder was added. The mixture was stirred at 400-1600 rpm for 4-9 h at 35-65 ℃ and ultrasonically dispersed for 1-5 h. After electrospinning to form a film, it was heat-treated at 80-180 ℃ for 3-7 h. Gold ion adsorption experiment: containing Au 3+ 10~30 mg / L, Cd 2+ Wastewater with a concentration of 20-50 mg / L, pH 4-7, temperature 25-50℃, and contact time 3-15 h; Au 3+ The adsorption capacity is 130~200 mg / g, Au 3+ with cd 2+ The selectivity coefficient is 60~75.

[0051] The prepared COFs composite membrane was applied to water containing heavy metal ions to achieve selective adsorption of gold ions: Target objects: those containing Au 3+ and coexisting Cu 2+ Pb 2+ Cd 2+ Fe 3+ Wastewater containing metal ions such as ~; Adsorption process: The composite membrane is brought into contact with wastewater for 0.5 to 24 hours at a temperature of 10 to 60 ℃ and a pH of 2 to 10. Desorption and regeneration: After adsorption saturation, desorption is performed using 0.1–5 mol / L hydrochloric acid, nitric acid, or thiourea solution at a temperature of 20–80 °C for 1–6 h. The regenerated composite membrane can be recycled more than 5 times. 3+ The adsorption capacity remains above 85% of the initial value; Performance metrics: Au 3+ Adsorption capacity not less than 100 mg / g, Au 3+ Initial concentration (c0) Au The initial concentration of other metal ions (c0) is 1-100 ppm. M The concentration of Au is 10-1000 ppm. 3+ The selectivity coefficient (S) with other metal ions is not less than 50, and its calculation formula is as follows: S=(c0 Au c t M ) / (c t Au c0 M )*100% Among them, c t Au c t M Au at time t 3+ Concentration of other metal ions.

Claims

1. A COFs composite membrane based on multi-scale simulation, characterized in that, The composite membrane was obtained through the following simulation steps: S1. Perform full atomic-scale simulations to screen COFs that are compatible with Au. 3+ Polymers with selective adsorption properties; S2. Perform mesoscale simulations to screen the relationship between the amount of COFs added and the porosity of the composite membrane; S3. Based on the simulation results of S1 and S2, the structure and composition of the polymer-COFs composite membrane are determined.

2. The COFs composite membrane according to claim 1, characterized in that, Step S1 includes: S101. Construct polymer molecular chain models and COF crystal molecular models; S102. Calculate the interaction energy and segment diffusion coefficient between COFs and polymers; S103. Screening polymer-COF combinations with interaction energies of -200 to -400 kJ / mol; S104. Based on the results of S103, calculate the effect of polymer-COFs on Au. 3+ And the adsorption energy of at least one coexisting metal ion, to screen for Au 3+ The adsorption energy of polymer-COFs is 20 to 80 kJ / mol higher than that of coexisting metal ions.

3. The COFs composite membrane according to claim 2, characterized in that, The molecular simulation calculations in step S102 are performed using ORCA, CP2K, and GROMACS.

4. The COFs composite membrane according to claim 3, characterized in that, ORCA uses the DFT-based M06-2X / 6-31+G* method to calculate the interaction energy of gas-phase molecular complexes; CP2K uses the DFT-based PBE-D3 / TZVP method to calculate the interaction energy of periodic materials. GROMACS performs all-atom molecular dynamics simulations based on the OPLS force field to calculate the chain segment diffusion coefficient.

5. The COFs composite membrane according to claim 1, characterized in that, Step S2 includes: S201. Based on the polymer-COF combination screened in S1, construct an all-atom initial mixing system model, perform molecular dynamics simulations until system equilibrium, and extract the all-atom non-bonded interaction energy and radial distribution function. S202. Based on the data from S201, calculate the interaction strength ε and particle radius σ of the Lennard-Jones potential to coarsen the polymer-COFs. S203. Based on the results of S202, construct a polymer-COF mesoscopic model to simulate the solvent evaporation film formation process or equilibrium film structure, and perform pore analysis. S204. Screening polymer-COF combinations with a porosity of 20-60% when the COF doping amount is 0.1-30 wt%.

6. The COFs composite membrane according to claim 1, characterized in that, The polymer-COFs composite membrane is selected from: PAN / TpBD-COFs, PVDF / TpBD-Me2-COFs or PES / TpPa-COFs.

7. A method for preparing a COFs composite membrane according to any one of claims 1-6, characterized in that, Includes the following steps: Preparation of COFs precursors: Organic aldehyde monomers and organic amine monomers are mixed at a molar ratio of 1:(0.8~1.2), dissolved in solvent, and reacted at 50~200℃ for 6~24 h. After separation, washing and drying, COFs powder is obtained. Preparation of casting solution: Dissolve the polymer in a solvent, add 0.1~30 wt% COFs powder, stir at 25~80℃ for 1~12 h, ultrasonically disperse for 0.5~6 h and then degas to obtain a uniform casting solution; Composite film forming: The casting solution is made into a base film by casting, scraping, electrospinning or dip-coating method, and then heat-treated at 50~300℃ for 1~12 h; Crosslinking treatment: The base film is immersed in a crosslinking agent solution and reacted at 50~150℃ for 1~8 h to obtain a COFs composite film.

8. The preparation method according to claim 7, characterized in that, The organic aldehyde monomer is 2,4,6-tricarboxyloylphloroglucinol, and the organic amine monomer is selected from at least one of p-phenylenediamine, biphenylenediamine, 2,2'-bipyridine-5,5'-diamine or 2-amino-p-phenylenediamine; the solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or acetone.

9. The preparation method according to claim 7, characterized in that, The polymer is selected from at least one of polyimide, polyamide, polyacrylonitrile, polyvinylidene fluoride, polyethersulfone, or polyetherketone.

10. The application of a COFs composite membrane according to any one of claims 1-6 in the selective adsorption of gold ions in water containing heavy metal ions.

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