Preparation method and application of loose surface metal ion imprinting composite film

Abstract

The application provides a preparation method and application of a loose surface metal ion imprinting composite film. The surface metal ion imprinting composite film is prepared by using interface polymerization as a surface ion imprinting technology, and belongs to the ion imprinting technical field. The method comprises the following steps: a porous support film is prepared, a water phase solution composed of sodium dodecyl sulfate, metal template ions and polyethylene polyamine is poured on the surface of the porous support film, the solution is poured out after a period of time, and the porous support film is placed until no obvious liquid drops are present on the surface; then, an aldehyde compound / ether solution is added for reaction, the reaction is subjected to heat treatment, the porous support film is placed in a hydrochloric acid solution for elution, and a surface loose surface metal ion imprinting composite film is prepared. The ion imprinting separation layer prepared by the application is located on the surface of the film and is uniformly distributed, and the problem that the recognition sites are embedded too deeply and are not easy to elute is avoided. The metal ion imprinting film has good removal capacity for heavy metal wastewater.

Description

[Technical Field]

[0001] This invention relates to a method for preparing and applying a porous surface metal ion-imprinted film, belonging to the field of ion imprinting technology. [Background Technology]

[0002] Currently, there are many methods for removing heavy metal ions, and membrane separation technology is widely used due to its advantages such as low energy efficiency, high removal efficiency, and simple operation. This method offers advantages in removing metal ions, including high removal efficiency, simple operation, and energy saving, but it also has disadvantages such as membrane pore blockage and low permeate flux. However, for ions with similar structural radii and properties, the separation efficiency of membrane separation is not high.

[0003] Ion imprinting technology uses target ions as templates, binding them with functional monomers through specific forces. Through cross-linking and elution processes, it forms imprinted cavities that match the template ions, enabling specific recognition of the target ions. Ion-imprinted membranes combine membrane separation technology and ion imprinting technology, possessing the advantages of both, and can efficiently and selectively separate target ions.

[0004] Ion-imprinted membranes are formed by a ternary complex of template ions, functional monomers, and ligands, which then forms a polymer under the action of a crosslinking agent. After thermal or photoinitiation, the polymer binds to the membrane in a filling, homogeneous blend, or layered manner. After elution to remove the template ions, an ion-imprinted membrane with specific recognition sites is obtained. Ion-imprinted composite membranes can be prepared through interfacial polycondensation, coating, surface grafting, and surface polymerization. The ion-imprinted layer is located on the membrane surface, ensuring maximum exposure of the ion-imprinted recognition sites. Interfacial polymerization is a commonly used method for preparing composite membranes. Using this method to prepare ion-imprinted membranes ensures that the ion-imprinted recognition sites are located on the membrane surface, and the interfacial polymerization occurs between small molecules, allowing for controllable polymer layer thickness and a relatively uniform distribution of ion-imprinted recognition sites.

[0005] Compared to the high reactivity of acyl chlorides and amines at room temperature, aldehydes and amines exhibit lower reactivity, which is advantageous for preparing loose nanofiltration membranes. Recently, the reaction between aldehydes and amines has been used to prepare nanofiltration membranes of covalent organic frameworks and conjugated microporous polymers, showing high separation performance. However, due to their low reaction rates, the reaction time must be long enough to ensure the formation of a complete membrane. Therefore, the reaction between aldehydes and amines shows great potential for preparing loose nanofiltration membranes, which have high flux and are beneficial for water permeation.

[0006] Therefore, based on the interfacial polymerization method, template ions are added to the aqueous solution of amine and reacted with the ether solution of aldehyde to develop a loose metal ion imprinted composite membrane. Through the specific binding of the surface imprinted sites and template ions, efficient and selective adsorption and separation are achieved. [Summary of the Invention]

[0007] To address the shortcomings of existing technologies, the technical problems that this invention aims to solve are the issues of ion-imprinted sites being too deeply embedded and difficult to elute, and efficient selective adsorption.

[0008] The present invention addresses the problem of ion imprinted sites being too deeply embedded and difficult to wash off. The technical solution for efficiently and selectively adsorbing and separating target ions is to prepare an ion imprinted separation layer on the surface of a porous support membrane, thereby obtaining a loose surface metal ion imprinted composite membrane.

[0009] This invention provides a method for preparing a porous surface metal ion imprinted film and its application, characterized by comprising the following steps:

[0010] a) Preparation of the support layer: The polymer polyethersulfone used to prepare the support membrane was dissolved in N,N-dimethylacetamide, and N-methylpyrrolidone was added as a pore-forming agent to prepare a casting solution. The polyethersulfone support membrane was then prepared by phase inversion.

[0011] b) Preparation of composite membrane: Fix the support membrane obtained in step a) in a polytetrafluoroethylene frame, pour a mixed aqueous solution of polyethylene polyamine and metal template ions onto the surface of the porous support membrane, let it stand for 1-60 min, pour out the excess mixed aqueous solution, let the membrane stand and dry at room temperature for 5-60 min, then pour an ether solution of aldehyde compound onto the membrane surface, let it stand for 1-60 min, and then rinse the membrane surface with ether solution.

[0012] c) Heat treatment: Dry the composite film obtained in step b) in an oven at 30-80℃ for 10-60 min;

[0013] d) Elution: Immerse the composite membrane obtained in step c) in a 0-10 mol / L hydrochloric acid solution to elute the metal ions and obtain a loose surface metal ion imprinted composite membrane.

[0014] e) The loose surface ion-imprinted composite membrane obtained in step d) is placed in a membrane pool for adsorption and separation of metal ions, and the ion removal rate reaches more than 95%.

[0015] The porous support membrane described in this invention has a thickness of 100-1000 μm, an average pore size of 0.04-1 μm, and a pure water flux of 100-500 L·m⁻¹ at room temperature and an operating pressure of 1 bar. -2 ·h -1 .

[0016] In the preparation of the composite membrane described in this invention, the preferred standing time is 1-60 min, the drying time is 5-60 min, and the reaction time is 1-60 min;

[0017] The preferred heat treatment temperature in this invention is 30-80℃, and the time is 10-60 min;

[0018] The polyethylene polyamine described in this invention is one or more of the following: m-phenylenediamine, p-phenylenediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and polyethyleneimine.

[0019] The polymer described in this invention is one or more of polysulfone, polyethersulfone, polyetherketone, sulfonated polyethersulfone, polyvinylidene fluoride, polyimide, polyacrylonitrile, polypropylene, and cellulose acetate, and the mass percentage of the polymer in the casting solution is 5%-30%.

[0020] The metal ions mentioned in this invention are one or more of copper ions, zinc ions, lead ions, cobalt ions, cadmium ions, nickel ions, and manganese ions.

[0021] The aldehyde compounds described in this invention are one or more of the following: glutaraldehyde, formaldehyde, acetaldehyde, adipaldehyde, octanaldehyde, lauraldehyde, citral, citric acid, benzaldehyde, phenylacetaldehyde, lily of the valley aldehyde, citronellol, perillaldehyde, and 2,4,6-trihydroxybenzene-1,3,5-trioxymethylene.

Detailed Implementation Methods

[0022] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0023] The separation and permeation performance of the metal ion-imprinted composite membrane prepared in this invention was measured using a cross-flow filtration device, namely, the membrane flux and removal rate:

[0024] Flux (J) reflects the membrane's permeation performance, J = V / (A·t·P). Where V is the volume of permeate on the permeate side (L); A is the effective area of ​​the membrane (m²). 2 ); t is the infiltration time (h); P is the operating pressure.

[0025] Removal rate (R) reflects the separation performance of the membrane, R = (1-C) / (1-C) e / C0)×100%. Where C0 and C e These represent the concentrations of the solute components in the feed solution and the permeate, respectively.

[0026] The porous surface metal ion-imprinted composite membrane prepared by this invention was tested for pure water flux and adsorption separation performance at an operating pressure of 5 bar.

[0027] The following describes specific embodiments of the present invention, but the present invention is not limited to these embodiments.

[0028] Example 1.

[0029] a) Preparation of porous supported membrane: Polyethersulfone particles were dissolved in N-methylpyrrolidone, and polyvinylpyrrolidone (PVP) was added as a pore-forming agent to prepare a casting solution with a polyethersulfone content of 16.5%. A planar supported membrane was prepared by phase inversion method, with a membrane thickness of 250 μm and a pure water flux of 266.97 L·m at room temperature. -2 ·h -1 ·bar;

[0030] b) Preparation of composite membrane: The polyethersulfone flat sheet membrane obtained in step a) is fixed in a polytetrafluoroethylene frame. A mixed aqueous solution of m-phenylenediamine and copper ions is poured onto the membrane surface. After standing for 5 minutes, the excess mixed aqueous solution is poured out. The membrane is allowed to stand and dry at room temperature for 5 minutes. Then, a glutaraldehyde ether solution is poured onto the membrane surface. After standing for 10 minutes, the membrane surface is rinsed with ether.

[0031] c) Heat treatment: Dry the composite film obtained in step b) in an oven at 30°C for 60 min;

[0032] d) Elution: The composite membrane obtained in step c) is immersed in 1 mol / L hydrochloric acid solution for 4 h to elute copper ions and obtain a loose surface copper ion imprinted composite membrane.

[0033] e) The porous surface copper ion-imprinted composite membrane obtained in the above steps is placed in a membrane tank for copper ion adsorption and separation, with a water flux of 28.37 L·m⁻¹. -2 ·h -1 ·bar -1 Its copper ion removal rate is 98.15%.

[0034] Example 2.

[0035] a) Preparation of porous supported membrane: Polyethersulfone particles were dissolved in N-methylpyrrolidone, and polyvinylpyrrolidone (PVP) was added as a pore-forming agent to prepare a casting solution with a polyethersulfone content of 18%. A planar supported membrane was prepared by phase inversion method, with a membrane thickness of 250 μm and a pure water flux of 217.68 L·m at room temperature. -2 ·h -1 ·bar;

[0036] b) Preparation of composite membrane: The polyethersulfone flat sheet membrane obtained in step a) is fixed in a polytetrafluoroethylene frame. A mixed aqueous solution of m-phenylenediamine and copper ions is poured onto the membrane surface. After standing for 60 min, the excess mixed aqueous solution is poured out. The membrane is dried at room temperature for 60 min. Then, a glutaraldehyde ether solution is poured onto the membrane surface. After standing for 60 min, the membrane surface is rinsed with ether.

[0037] c) Heat treatment: Dry the composite film obtained in step b) in an oven at 80°C for 10 min;

[0038] d) Elution: Immerse the composite membrane obtained in step c) in a 2 mol / L hydrochloric acid solution for 4 h; elute copper ions to obtain a loose surface copper ion imprinted composite membrane.

[0039] e) The porous surface copper ion-imprinted composite membrane obtained in the above steps is placed in a membrane tank for copper ion adsorption and separation, with a water flux of 17.87 L·m⁻¹. -2 ·h -1 ·bar -1 Its copper ion removal rate is 98.60%.

[0040] Example 3.

[0041] a) Preparation of porous supported membrane: Polyethersulfone particles were dissolved in N-methylpyrrolidone, and polyvinylpyrrolidone (PVP) was added as a pore-forming agent to prepare a casting solution with a polyethersulfone content of 17%. A planar supported membrane was prepared by phase inversion method, with a membrane thickness of 250 μm and a pure water flux of 379.13 L·m at room temperature. -2 ·h -1 ·bar;

[0042] b) Preparation of composite membrane: The polyethersulfone flat sheet membrane obtained in step a) is fixed in a polytetrafluoroethylene frame. A mixed aqueous solution of m-phenylenediamine and zinc ions is poured onto the membrane surface. After standing for 30 minutes, the excess mixed aqueous solution is poured out. The membrane is dried at room temperature for 30 minutes. Then, a glutaraldehyde ether solution is poured onto the membrane surface. After standing for 30 minutes, the membrane surface is rinsed with ether.

[0043] c) Heat treatment: Dry the composite film obtained in step b) in an oven at 40°C for 30 min;

[0044] d) Elution: Immerse the composite membrane obtained in step c) in a 5 mol / L hydrochloric acid solution for 4 h; elute the zinc ions to obtain a loose surface zinc ion imprinted composite membrane.

[0045] e) The porous surface zinc ion imprinted composite membrane obtained in the above steps is placed in a membrane bath for zinc ion adsorption and separation, with a water flux of 25.32 L·m⁻¹. -2 ·h -1 ·bar -1 Its zinc ion removal rate is 98.87%.

Claims

1. A method for preparing a loose surface metal ion-imprinted composite film, characterized in that, The method comprises the following steps: a) Preparation of porous support membrane: a polymer polyether sulfone used to prepare the support membrane is dissolved in N, N-dimethylacetamide, N-methyl pyrrolidone is added as a porogen, a casting solution is prepared, and a polyether sulfone support membrane is prepared by a phase inversion method; b) Preparation of composite membrane: the support membrane obtained in step a) is fixed in a polytetrafluoroethylene frame, a mixed aqueous solution of m-phenylenediamine and metal template ions is poured on the surface of the porous support membrane, the excess mixed aqueous solution is poured out after standing for 1-60 min, the membrane is left to dry at room temperature for 5-60 min, and then an ethyl ether solution of glutaraldehyde is poured on the surface of the membrane, the membrane surface is washed with ethyl ether after reacting for 1-60 min; c) Heat treatment: the composite membrane obtained in step b) is dried in an oven at 30-80 ℃ for 10-60 min; d) Elution: the composite membrane obtained in step c) is soaked in a 0-10 mol / L hydrochloric acid solution to elute the metal ions, and a loose surface metal ion imprinted composite membrane is obtained; e) The loose surface ion imprinted composite membrane obtained in step d) is placed in a membrane cell for adsorption and separation of metal ions, and the removal rate of ions reaches more than 95%.

2. The method for preparing a loose surface metal-ion imprinted composite film according to claim 1, characterized in that: The average pore size of the porous support film is 0.04-1 μm, and the pure water flux at room temperature is 100-500 L·m -2 ·h -1 ·bar -1 .

3. The method according to claim 1, wherein the method is characterized by: The metal ions are one or more of copper ions, zinc ions, lead ions, cobalt ions, cadmium ions, nickel ions, and manganese ions.