Preparation method and application of loose surface metal ion imprinted composite membrane

Abstract

The invention provides a preparation method and application of a loose surface metal ion imprinting composite membrane, the surface metal ion imprinting composite membrane is prepared by adopting interfacial polymerization as a surface ion imprinting technology, and the preparation method belongs to the technical field of ion imprinting and comprises the following steps: preparing a porous support membrane; pouring a water-phase solution consisting of lauryl sodium sulfate, metal template ions and polyethylene polyamine on the surface, keeping for a period of time, pouring out, standing until no obvious liquid drops exist on the surface, then adding an aldehyde compound / diethyl ether solution for reaction, carrying out heat treatment reaction, then putting into a hydrochloric acid solution for elution, and carrying out vacuum drying to obtain the metal template. The surface metal ion imprinting composite membrane with the loose surface is prepared. The prepared ion imprinting separation layer is located on the surface of the membrane, site distribution is uniform, and the problem that recognition sites are embedded too deep and are not prone to elution is solved. The metal ion blotting membrane has good removal capability on heavy metal wastewater.

Description

[Technical field]

[0001] The invention relates to a preparation method and application of a loose surface metal ion imprinted membrane, belonging to the technical field of ion imprinting. [Background technology]

[0002] At present, there are many methods to remove heavy metal ions. Membrane separation technology is widely used due to its advantages such as low energy efficiency, high removal efficiency and simple operation. This method has the advantages of high removal efficiency, simple operation, energy saving and consumption reduction in removing metal ions, but it also has disadvantages such as membrane pore blockage and low permeation flux. However, for ions with similar structure radius and properties, the separation efficiency of membrane separation is not high.

[0003] Ion imprinting technology uses the target ion as a template, combines with the functional monomer through a certain force, and forms an imprinted cavity that matches the template ion through the cross-linking and elution process, which has the specific recognition ability for the target ion. The ion imprinting membrane combines membrane separation technology and ion imprinting technology, and has the advantages of both, and can efficiently and selectively separate the target ions.

[0004] Ion-imprinted membranes are ternary complexes formed by template ions, functional monomers and ligands, which form polymers under the action of crosslinkers. After thermal initiation or photoinitiation, the polymers will be combined with the membrane in a filling, uniformly blended 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 by interfacial polycondensation, coating, surface grafting and surface polymerization. The ion-imprinted layer is located on the membrane surface, ensuring the maximum exposure of the ion-imprinted recognition sites. Interfacial polymerization is a common method for preparing composite membranes. If this method is used to prepare ion-imprinted membranes, it not only ensures that the ion-imprinted recognition sites are located on the membrane surface, but also that interfacial polymerization occurs between small molecules, the thickness of the polymer layer is controllable, and the ion-imprinted recognition sites are distributed more evenly.

[0005] Compared with the high reactivity of acyl chlorides and amines at room temperature, the reactivity of aldehydes and amines is low, which is beneficial for the preparation of 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 rate, the reaction time must be long enough to ensure the formation of a complete membrane. Therefore, the reaction of aldehydes with amines has great potential in the preparation of loose nanofiltration membranes, which have high flux and are conducive to water permeation.

[0006] Therefore, based on the interfacial polymerization method, the template ions were added to the aqueous solution of amines and reacted with the ether solution of aldehydes to develop a loose metal ion imprinted composite membrane, which achieved efficient selective adsorption and separation through the specific binding of surface imprinted sites and template ions. [Summary of the invention]

[0007] In view of the shortcomings of the prior art, the technical problem that the present invention intends to solve is the problem of ion imprinting sites being embedded too deeply and difficult to elute and the problem of efficient and selective adsorption.

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

[0009] The present invention provides a preparation method and application of a loose surface metal ion imprinted membrane, which is characterized by comprising the following steps:

[0010] a) Preparation of the support layer: dissolving the high molecular weight polymer polyethersulfone for preparing the support membrane in N,N-dimethylacetamide, adding N-methylpyrrolidone as a porogen, preparing a casting solution, and preparing the polyethersulfone support membrane by a phase inversion method;

[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 on the surface of the porous support membrane, let it stand for 1-60 minutes, pour out the excess mixed aqueous solution, let the membrane stand and dry for 5-60 minutes at room temperature, then pour an ether solution of aldehyde compound on the membrane surface, let it stand for 1-60 minutes, and then rinse the membrane surface with ether solution;

[0012] c) heat treatment: drying the composite film obtained in step b) in an oven at 30-80° C. for 10-60 min;

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

[0014] e) placing the loose surface ion imprinted composite membrane obtained in step d) in a membrane pool to perform adsorption and separation of metal ions, with the ion removal rate reaching more than 95%.

[0015] The thickness of the porous support membrane of the present invention is 100-1000 μm, the average pore size of the porous support membrane is 0.04-1 μm, and the pure water flux at room temperature and 1 bar operating pressure is 100-500 L·m -2 ·h -1 .

[0016] In the preparation of the composite film of the present 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 heat treatment temperature of the present invention is preferably 30-80°C and the time is 10-60min;

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

[0019] The high molecular polymer of the present 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 high molecular polymer in the casting solution is 5%-30%.

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

[0021] The aldehyde compound described in the present invention is one or more of glutaraldehyde, formaldehyde, acetaldehyde, adipaldehyde, octanal, lauryl aldehyde, isocyclocitral, citronellal, benzaldehyde, phenylacetaldehyde, lily of the valley aldehyde, citronellal, perillaldehyde, and 2,4,6-trihydroxybenzene-1,3,5-trioxyformaldehyde. [Specific implementation method]

[0022] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0023] The separation and permeability performance of the metal ion imprinted composite membrane prepared by the present invention, namely the flux and removal rate of the membrane, is measured by a cross-flow filtration device:

[0024] The flux (J) reflects the permeability of the membrane, J = V / (A·t·P). In the formula, V is the permeate volume on the permeation side (L); A is the effective area of ​​the membrane (m 2 ) ; t is the penetration time (h); P is the operating pressure.

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

[0026] The loose surface metal ion imprinted composite membrane prepared by the present invention is used to measure the pure water flux and adsorption separation performance of the ion imprinted composite membrane under an operating pressure of 5 bar.

[0027] Specific embodiments of the present invention are described below, but the present invention is not limited to the embodiments.

[0028] Example 1.

[0029] a) Preparation of porous support membrane: Polyethersulfone particles were dissolved in N-methylpyrrolidone, and porogen polyvinylpyrrolidone was added to prepare a casting solution with a polyethersulfone mass percentage of 16.5%. A flat support membrane was prepared by a phase inversion method. The membrane thickness was 250 μm, and the pure water flux at room temperature was 266.97 L·m -2 ·h -1 bar;

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

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

[0032] d) elution: soaking the composite membrane obtained in step c) in a 1 mol / L hydrochloric acid solution for 4 hours to elute the copper ions and obtain a loose surface copper ion imprinted composite membrane;

[0033] e) The loose surface copper ion imprinted composite membrane obtained in the above step was placed in a membrane pool for adsorption and separation of copper ions. The water flux was 28.37 L·m -2 ·h -1 bar -1 , and its removal rate for copper ions is 98.15%.

[0034] Example 2.

[0035] a) Preparation of porous support membrane: Polyethersulfone particles were dissolved in N-methylpyrrolidone, and porogen polyvinylpyrrolidone was added to prepare a casting solution with a polyethersulfone mass percentage of 18%. A flat support membrane was prepared by a phase inversion method. The membrane thickness was 250 μm and the pure water flux at room temperature was 217.68 L·m -2 ·h -1 bar;

[0036] b) Preparation of composite membrane: The polyethersulfone flat membrane obtained in step a) is fixed in a polytetrafluoroethylene frame, a mixed aqueous solution of m-phenylenediamine and copper ions is poured on the membrane surface, and the excess mixed aqueous solution is poured out after standing for 60 minutes, and the membrane is left to stand and dry at room temperature for 60 minutes, and then a diethyl ether solution of glutaraldehyde is poured on the membrane surface, and the membrane surface is rinsed with diethyl ether after standing for 60 minutes;

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

[0038] d) elution: soaking the composite membrane obtained in step c) in a 2 mol / L hydrochloric acid solution for 4 hours; eluting the copper ions to obtain a loose surface copper ion imprinted composite membrane;

[0039] e) The loose surface copper ion imprinted composite membrane obtained in the above step was placed in a membrane pool for adsorption and separation of copper ions. The water flux was 17.87 L·m -2 ·h -1 bar -1 , and its removal rate for copper ions is 98.60%.

[0040] Example 3.

[0041] a) Preparation of porous support membrane: Polyethersulfone particles were dissolved in N-methylpyrrolidone, and porogen polyvinylpyrrolidone was added to prepare a casting solution with a polyethersulfone mass percentage of 17%. A flat support membrane was prepared by a phase inversion method. The membrane thickness was 250 μm and the pure water flux at room temperature was 379.13 L·m -2 ·h -1 bar;

[0042] b) Preparation of composite membrane: The polyethersulfone flat membrane obtained in step a) is fixed in a polytetrafluoroethylene frame, a mixed aqueous solution of m-phenylenediamine and zinc ions is poured on the membrane surface, and the excess mixed aqueous solution is poured out after standing for 30 minutes, and the membrane is left to dry at room temperature for 30 minutes, and then a glutaraldehyde ether solution is poured on the membrane surface, and the membrane surface is rinsed with ether after standing for 30 minutes;

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

[0044] d) elution: immersing the composite membrane obtained in step c) in a 5 mol / L hydrochloric acid solution for 4 hours; eluting the ionic zinc to obtain a loose surface zinc ion imprinted composite membrane;

[0045] e) The loose surface zinc ion imprinted composite membrane obtained in the above step was placed in a membrane pool for zinc ion adsorption and separation, and the water flux was 25.32 L·m -2 ·h -1 bar -1 , and its removal rate of zinc ions is 98.87%.

Claims

1. A preparation method and application of a loose surface metal ion imprinted composite membrane, characterized in that: The following steps are involved: a) Preparation of porous support membrane: dissolving the high molecular weight polymer polyethersulfone for preparing the support membrane in N,N-dimethylacetamide, adding N-methylpyrrolidone as a porogen, preparing a casting solution, and preparing the polyethersulfone support membrane by a phase inversion method; 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 on the surface of the porous support membrane, pour out the excess mixed aqueous solution after standing for 1-60 minutes, let the membrane stand and dry for 5-60 minutes at room temperature, then pour an ether solution of aldehyde compound on the membrane surface, react for 1-60 minutes, and then rinse the membrane surface with ether; c) heat treatment: drying the composite film obtained in step b) in an oven at 30-80° C. for 10-60 min; d) elution: immersing the composite membrane obtained in step c) in a 0-10 mol / L hydrochloric acid solution to elute the metal ions to obtain a loose surface metal ion imprinted composite membrane; e) placing the loose surface ion imprinted composite membrane obtained in step d) in a membrane pool to perform adsorption and separation of metal ions, with the ion removal rate reaching more than 95%.

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

3. The preparation method and application of a loose surface metal ion imprinted composite membrane according to claim 1, characterized in that: The preferred standing time in the preparation of the composite film is 1-60 min, the drying time is 5-60 min, and the reaction time is 1-60 min; 4. The preparation method and application of a loose surface metal ion imprinted composite membrane according to claim 1, characterized in that: The heat treatment temperature is preferably 30-80°C and the time is 10-60min; 5. The preparation method and application of a loose surface metal ion imprinted composite membrane according to claim 1, characterized in that: The polyethylene polyamine is one or more of m-phenylenediamine, p-phenylenediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethyleneimine.

6. The preparation method and application of a loose surface metal ion imprinted composite membrane according to claim 1, characterized in that: The metal ions are one or more of copper ions, zinc ions, lead ions, cobalt ions, cadmium ions, nickel ions and manganese ions.

7. The preparation method and application of a loose surface metal ion imprinted composite membrane according to claim 1, characterized in that: The aldehyde compound is one or more of glutaraldehyde, formaldehyde, acetaldehyde, adipaldehyde, octanal, lauryl aldehyde, isocyclocitral, citronellal, benzaldehyde, phenylacetaldehyde, lily of the valley aldehyde, citronellal, perillaldehyde, and 2,4,6-trihydroxybenzene-1,3,5-trioxyformaldehyde.