A metal ring water channel membrane and a preparation method and application thereof
By introducing metal ring compounds onto the surface of the base membrane, a metal ring water channel membrane is constructed, which solves the problems of low water flux, insufficient retention selectivity and poor stability of existing polyamide membranes in the treatment of dyeing and printing wastewater, and achieves efficient dye separation and low-cost operation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TIANJIN POLYTECHNIC UNIV
- Filing Date
- 2026-04-30
- Publication Date
- 2026-07-14
Smart Images
Figure CN122098277B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of separation membrane technology, and in particular to a metal ring water channel membrane, its preparation method, and its application. Background Technology
[0002] The dyeing and printing industry is an important part of the textile industry, but its production process generates a large amount of highly polluting wastewater. This type of wastewater contains a wide variety of pollutants, with high concentrations, deep colors, and large fluctuations in water quality. Many of the dye molecules contained in this wastewater are chemically stable and difficult to be degraded by microorganisms. Direct discharge of such wastewater would seriously pollute surface and groundwater resources, disrupt the ecological balance, and waste water resources.
[0003] Membrane separation technology, as a highly efficient and environmentally friendly separation method, utilizes its physical retention mechanism to separate dyes and water at room temperature without the need for chemical reagents, making it one of the core technologies for the treatment and reuse of dyeing and printing wastewater. Polyamide membranes, due to their excellent hydrophilicity, mechanical strength, and chemical stability, are widely used in the field of dyeing and printing wastewater treatment. However, existing conventional polyamide membranes still face several technical challenges in practical applications, as detailed below:
[0004] I. Unreasonable membrane structure design: Conventional membranes have a thick separation layer and lack dedicated water molecule transport channels, which means that water molecules need to diffuse randomly over long distances within the membrane, resulting in high transport resistance, low water flux, and difficulty in meeting the efficiency requirements of industrial-scale treatment.
[0005] 2. Insufficient selectivity: The membrane has a wide pore size distribution, which makes it less effective at retaining some small molecule dyes, and the color of the effluent is difficult to meet the direct discharge requirements in the relevant industry emission standards.
[0006] Third, poor operational stability: Dye molecules are easily adsorbed on the membrane surface, leading to prominent membrane fouling problems. After long-term operation, the flux declines significantly, requiring frequent cleaning, which in turn increases operating costs.
[0007] Therefore, there is an urgent need to develop a membrane material that combines thin separation layer, high retention selectivity, high water flux and strong operational stability. Summary of the Invention
[0008] The present invention aims to at least solve one of the technical problems existing in the related art. Therefore, the first objective of the present invention is to provide a method for preparing a metal ring water channel membrane; the second objective of the present invention is to provide a metal ring water channel membrane; and the third objective of the present invention is to provide applications of the metal ring water channel membrane.
[0009] To achieve the first objective, the technical solution adopted by this invention is as follows:
[0010] A method for preparing a metal ring water channel membrane includes the following steps:
[0011] S100. The base membrane is immersed in a mixed solution containing metal ring compound and MPD. After immersion, a base membrane adsorbed with MPD and metal ring compound is obtained.
[0012] The metal ring compound is Pt-4 or Pt-6, and MPD is m-phenylenediamine;
[0013] The structural formula for Pt-4 is shown below:
[0014] ;
[0015] The structural formula for Pt-6 is shown below:
[0016] ;
[0017] S200. Place the base film adsorbed with MPD and metal ring compounds in a TMC solution, so that one side of the base film adsorbed with MPD and metal ring compounds forms an interface with the TMC solution. A polymerization reaction occurs at the interface. After the reaction is complete, a composite film loaded with metal ring compounds is obtained.
[0018] TMC stands for trimesoyl chloride;
[0019] S300. The composite membrane loaded with the metal ring compound is cured in an oven to obtain a metal ring water channel membrane.
[0020] By introducing metal ring compounds onto the surface of the base membrane through interfacial polymerization, the microstructure of the base membrane is altered. The polyamide composite membrane loaded with metal ring compounds formed by interfacial polymerization on the base membrane surface reduces the resistance to water molecule transport by thinning the base membrane, thereby increasing water flux. At the same time, the synergistic effect between the metal ring compounds and the base membrane can optimize the retention performance of the base membrane, thereby achieving effective interception of different dye molecules.
[0021] Therefore, the metal ring water channel membrane has significant advantages over traditional base membranes, specifically as follows:
[0022] I. Membrane Structure Optimization: The spatial configuration of metal ring compounds has a regular pore structure, which serves as a dedicated channel for water molecule transport. This can reduce the random diffusion of water molecules within the membrane, lower transport resistance, and thus achieve high water flux.
[0023] II. Excellent retention performance: The cross-linked structure formed by the interfacial polymerization of metal ring compounds with MPD and TMC monomers can optimize the pore size distribution of the membrane. The formed pores can effectively intercept dye molecules while allowing water molecules to pass freely, achieving a synergistic effect of high efficiency retention and high water flux.
[0024] III. Structural stability: The metal ring compound forms a stable macrocycle through N-Pt coordination bonds. At the same time, the amino groups on the ligands can undergo amidation reactions with TMC, covalently anchoring the metal ring compound in the base film, preventing detachment and structural collapse, thereby improving the long-term stability of the film.
[0025] Further, in step S100, the solvent of the mixed solution is water, and the MPD in the mixed solution is 1.5 to 2.5% (w / v).
[0026] Furthermore, in step S100, the soaking time is 30s to 90s.
[0027] Furthermore, in step S100, the base film is made of nylon-6.
[0028] Further, in step S200, the solvent of the TMC solution is n-hexane with a concentration of 0.05–0.15% (w / v).
[0029] Furthermore, in step S300, the oven temperature is 60℃~70℃, and the curing time is 4~6min.
[0030] Furthermore, in step S200, the interfacial reaction time is 1.5 to 2.5 min.
[0031] To achieve the second objective, the technical solution adopted by this invention is as follows:
[0032] A metal ring water channel membrane is prepared using any of the above-described methods for preparing metal ring water channel membranes.
[0033] To achieve the third objective, the technical solution adopted by this invention is as follows:
[0034] An application of a metal ring water channel membrane, specifically its application in the treatment of dyeing and printing wastewater.
[0035] Furthermore, the dyeing and printing wastewater contains one or more of the following dyes: methylene blue, methylene blue, methyl orange, and crystal violet.
[0036] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:
[0037] This invention provides a metal ring water channel membrane and its preparation method. By utilizing interfacial polymerization technology to introduce a metal ring compound into the base membrane structure, the microstructure of the base membrane can be effectively controlled, thereby constructing a metal ring water channel membrane. This membrane reduces the resistance to water molecule transport by thinning the base membrane, thus significantly increasing water flux. Simultaneously, the synergistic effect between the metal ring compound and the base membrane optimizes the base membrane's retention performance, achieving highly efficient and selective interception of different types of dye molecules. Scanning electron microscopy (SEM) observations confirmed that the thickness of the metal ring water channel membrane is approximately 163 nm, significantly thinner than the original base membrane without the metal ring compound (approximately 220 nm thick). Membrane separation performance tests show that the introduction of the metal ring compound into the base membrane significantly improves its water permeability without reducing its interception efficiency for various dye molecules, successfully achieving a synergistic balance between high flux and high retention rate.
[0038] Metal ring water channel membranes have significant advantages over traditional base membranes, mainly because:
[0039] I. Metal ring compounds, with their regular pore structure, can serve as dedicated transport channels for water molecules, effectively inhibiting the random diffusion of water molecules within the membrane, reducing transport resistance, and achieving high water flux characteristics.
[0040] II. The cross-linked structure formed by the interfacial polymerization reaction of metal ring compounds with MPD and TMC monomers can precisely control the pore size distribution of the membrane. The constructed pores can efficiently intercept dye molecules while allowing water molecules to pass through freely, achieving synergistic optimization of efficient retention and high water flux.
[0041] Third, the metal ring compound forms a stable macrocyclic structure through N-Pt coordination bonds. The amino groups on its ligands can undergo amidation reactions with TMC, covalently anchoring the metal ring compound to the base membrane system, effectively preventing its desorption and membrane structure collapse, and significantly improving the long-term operational stability of the membrane.
[0042] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0043] Figure 1 These are the Fourier Transform Infrared (FT-IR) spectra of the metal ring compounds Pt-4 and Pt-6 provided in the embodiments of the present invention.
[0044] Figure 2 These are scanning electron microscope (SEM) images of the nylon-6 base membrane and the metal ring water channel membrane (using the metal ring compound Pt-6 as raw material) provided in the embodiments of the present invention.
[0045] Figure 3 This is a cross-sectional SEM image of the nylon-6 base membrane and the metal ring water channel membrane (using the metal ring compound Pt-6 as raw material) provided in the embodiments of the present invention.
[0046] Figure 4 These are surface atomic force microscopy (AFM) images of the nylon-6 base membrane and the metal ring water channel membrane (using the metal ring compound Pt-6 as raw material) provided in the embodiments of the present invention.
[0047] Figure 5 This is a comparison chart of different membrane separation performances provided in the test examples of this invention. Detailed Implementation
[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention, but cannot be used to limit the scope of this invention.
[0049] In the following embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available, unless otherwise specified, and are carried out in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.
[0050] Example
[0051] The preparation process of the metal ring water channel membrane is as follows:
[0052] I. Preparation of the metal ring compound Pt-4 .
[0053] organic ligands (2 mmol) and metal ligands 2 mmol was added to anhydrous methanol (20 mL), and the reaction was carried out under nitrogen protection at room temperature (about 25 °C) with stirring for 12 h. After the reaction was completed, anhydrous diethyl ether (50 mL) was slowly added dropwise to the reaction system, and the mixture was stirred thoroughly during the addition to ensure that the metal ring product was completely precipitated. Then, the mixture was centrifuged (8000 r / min for 10 min). After centrifugation, the precipitate was collected and washed three times with anhydrous diethyl ether. The washed precipitate was placed in a vacuum drying oven and dried under vacuum at 40 °C for 6 h to obtain the metal ring compound Pt-4.
[0054] II. Preparation of the metal ring compound Pt-6 Its preparation process, besides replacing the metal ligand with The remaining process is the same as that for Pt-4. The FT-IR spectra of the metal ring compounds Pt-4 and Pt-6 are shown below. Figure 1 As shown in the figure, both Pt-6 and Pt-4 exhibit a red shift in the C=N peak of the pyridine ring, and a new peak for the Pt–N coordination bond appears. This directly confirms the successful synthesis of the macrocyclic metal ring and the integrity of its structure. The subtle differences in the peak positions of the two characteristic peaks are attributed to the spatial configuration of the skeleton and steric hindrance effects, which are direct manifestations of their structural differences in spectroscopy.
[0055] 3. Preparation of a mixed solution containing 0.5% (w / v) Pt-4 (or Pt-6) and 2% (w / v) MPD: Add MPD (2g) to water (100mL) and stir to dissolve. Then add Pt-4 (0.5g) or Pt-6 (0.5g) and stir magnetically for 30min to disperse it evenly in the solution.
[0056] IV. Preparation of 0.1% (w / v) TMC solution: Add TMC (0.1g) to n-hexane (100mL) and sonicate for 10min to obtain the solution.
[0057] V. Pretreatment of Nylon-6 base film: Soak the Nylon-6 base film in deionized water for 2 hours to remove residual production additives on the surface of the base film, and then dry it in an oven at 60℃ for 30 minutes to obtain a clean Nylon-6 base film.
[0058] VI. Immersion Treatment: The pretreated nylon-6 membrane is completely immersed in a mixed solution containing Pt-4 (or Pt-6) and MPD for about 1 minute at room temperature (about 25°C) to ensure that MPD and metal ring compounds are fully adsorbed on the surface and in the pores of the base membrane, thus obtaining a base membrane adsorbed with MPD and metal ring compounds.
[0059] VII. Interfacial Polymerization Reaction: The base membrane adsorbed with MPD and metal ring compounds was removed from the soaking solution, and excess MPD solution on the membrane surface was removed by purging with nitrogen (purging pressure was 0.05 MPa, purging time was 30 s). Then the membrane was transferred to a reaction tank containing 0.1% (w / v) TMC solution, so that the adsorption surface of the membrane formed an interface with the TMC solution. Interfacial polymerization reaction was carried out at room temperature (about 25°C) for 2 min to obtain a composite membrane loaded with metal ring compounds.
[0060] 8. Curing treatment: Remove the composite membrane loaded with metal ring compound from the reaction system and place it in a constant temperature oven at 65°C for curing treatment (to promote the chemical bonding between the metal ring compound and the polymer network and enhance the stability of the membrane structure). The curing time is 5 minutes to obtain the metal ring water channel membrane. Store it in deionized water in a sealed container for later use.
[0061] IX. Characterization: SEM images of the surface of nylon-6 base film and metal ring water channel film (using metal ring compound Pt-6 as raw material), as shown below. Figure 2 As shown;
[0062] Figure A shows the SEM image of the base membrane, and Figure B shows the SEM image of the metal ring water channel membrane.
[0063] from Figure 2 It can be seen that by introducing metal ring compounds into the base membrane, the metal ring water channel membrane successfully constructs nanoscale ordered water channels, transforming the originally macroporous and loose base membrane into a functional membrane with efficient separation and transport capabilities.
[0064] Cross-sectional SEM images of nylon-6 base membrane and metal ring water channel membrane (using metal ring compound Pt-6 as raw material), as shown. Figure 3 As shown;
[0065] Figure A shows the SEM image of the base membrane, and Figure B shows the SEM image of the metal ring water channel membrane.
[0066] from Figure 3 It can be seen that reducing the membrane thickness from 220nm to 163nm significantly shortens the water transport path and directly increases the water flux. Although the thickness of the metal ring water channel membrane is thinner, the network structure constructed by the metal rings maintains extremely high density. Not only does it not sacrifice retention performance, but it also enhances the orderliness of the water channels. The metal ring water channel membrane maintains nanoscale channel size while keeping the thickness thinner, laying the structural foundation for achieving the dual goals of high flux and high retention.
[0067] AFM images of nylon-6 base membranes and metal ring water channel membranes (using Pt-6 metal ring compound as raw material), as shown below. Figure 4 As shown;
[0068] Figure A shows the AFM image of the base membrane, and Figure B shows the AFM image of the metal ring water channel membrane.
[0069] from Figure 4It can be seen that the surface of the base membrane is relatively flat and lacks obvious functional micro / nano structures; while the surface of the metal ring water channel membrane exhibits a three-dimensional interconnected fibrous / network structure induced by the metal ring compound, forming a well-developed surface channel network. This morphological change not only significantly increases the surface roughness and specific surface area of the membrane, providing more rapid transport sites for water molecules, but also helps to reduce the direct contact area between pollutants and the membrane surface, providing an important structural basis for the membrane's high water flux and excellent antifouling performance.
[0070] Test Example
[0071] Using methylene blue, methylene blue, methyl orange, and crystal violet as model dye wastewater, the permeation flux and dye retention performance of nylon-6 based membrane, metal ring water channel membrane (with Pt-4 as the introduced metal ring compound), and metal ring water channel membrane (with Pt-6 as the introduced metal ring compound) were investigated.
[0072] Simulated wastewater: Wastewater containing methylene blue or methylene blue (macromolecule basic dye, initial concentration 50 mg / L), wastewater containing methyl orange (small molecule acid dye, initial concentration 60 mg / L), and wastewater containing crystal violet (macromolecule basic dye, initial concentration 80 mg / L) were collected and treated using cross-flow filtration (operating pressure 0.1 MPa) at room temperature (approximately 25°C). Each experiment ran continuously for 24 hours, recording the permeate volume and filtration time, and calculating the flux. The results are as follows: Figure 5 As shown in the figure, it can be seen that the flux of the base membrane to wastewater containing all dye molecules (methylene blue, methylene blue, methyl orange, and crystal violet) is very low (all below 10 L·m⁻¹). 2 ·h -1 The following results indicate that the base membrane has poor water permeability and low treatment efficiency; the water flux of both metal ring water channel membranes is significantly improved compared to the base membrane, with the water flux of the channel membrane with Pt-6 as the introduced metal ring compound being more significantly improved.
[0073] The stock solution and permeate were collected, and the absorbance was measured at the characteristic absorption wavelengths of each dye using a UV-Vis spectrophotometer. The concentration was converted using a standard curve, and the rejection rate was calculated. The results are as follows: Figure 5 As shown, the rejection rate of all three membranes for all dye molecules remained above 85%. This result indicates that introducing metal ring compounds into the base membrane can significantly improve water permeability without sacrificing the ability to intercept different dye molecules, thus achieving a balance between high throughput and high rejection rate.
[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a metal ring water channel membrane, characterized in that, Includes the following steps: S100. The base membrane is immersed in a mixed solution containing metal ring compound and MPD. After immersion, a base membrane adsorbed with MPD and metal ring compound is obtained. The metal ring compound is Pt-4 or Pt-6, and MPD is m-phenylenediamine; The structural formula for Pt-4 is shown below: ； The structural formula for Pt-6 is shown below: ； S200. The base film adsorbed with MPD and metal ring compounds is placed in a TMC solution, so that one side of the base film adsorbed with MPD and metal ring compounds forms an interface with the TMC solution. A polymerization reaction occurs at the interface, and after the reaction is completed, a composite film loaded with metal ring compounds is obtained. TMC stands for trimesoyl chloride; S300. The composite membrane loaded with the metal ring compound is cured in an oven to obtain a metal ring water channel membrane.
2. The method for preparing the metal ring water channel membrane as described in claim 1, characterized in that, In step S100, the solvent of the mixed solution is water, and the concentration of MPD in the mixed solution is 1.5-2.5% (w / v).
3. The method for preparing the metal ring water channel membrane as described in claim 1, characterized in that, In step S100, the soaking time is 30s to 90s.
4. The method for preparing the metal ring water channel membrane as described in claim 1, characterized in that, In step S100, the base film is made of nylon-6.
5. The method for preparing the metal ring water channel membrane as described in claim 1, characterized in that, In step S200, the solvent for the TMC solution is n-hexane with a concentration of 0.05–0.15% (w / v).
6. The method for preparing the metal ring water channel membrane as described in claim 1, characterized in that, In step S300, the oven temperature is 60℃~70℃, and the curing time is 4~6min.
7. The method for preparing the metal ring water channel membrane as described in claim 1, characterized in that, In step S200, the interface reaction time is 1.5 to 2.5 minutes.
8. A metal annular water channel membrane, characterized in that, It is prepared using the method for preparing a metal ring water channel membrane as described in any one of claims 1 to 7.
9. An application of a metal annular water channel membrane, characterized in that, The application of the metal annular water channel membrane as described in claim 8 in the treatment of dyeing and printing wastewater.
10. The application of the metal annular water channel membrane as described in claim 9, characterized in that, The dyeing and printing wastewater contains one or more of the following dyes: methylene blue, methylene blue, methyl orange, and crystal violet.