KR20160121987A - Monomer Limited Interfacial Polymerization Method and Separation Membrane Prepared by the Same - Google Patents
Monomer Limited Interfacial Polymerization Method and Separation Membrane Prepared by the Same Download PDFInfo
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- KR20160121987A KR20160121987A KR1020150051941A KR20150051941A KR20160121987A KR 20160121987 A KR20160121987 A KR 20160121987A KR 1020150051941 A KR1020150051941 A KR 1020150051941A KR 20150051941 A KR20150051941 A KR 20150051941A KR 20160121987 A KR20160121987 A KR 20160121987A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/14—Ultrafiltration; Microfiltration
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0006—Organic membrane manufacture by chemical reactions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/38—Graft polymerization
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Abstract
Description
The present invention relates to a novel limiting interface polymerization method and a separation membrane produced using the same.
Interfacial polymerization is a method of polymerizing a polymer by bringing each monomer into contact at the interface between solutions using two solutions which are not mixed with each other. Nylon, and aramid are manufactured through this method, and they are the most widely used technology in the membrane field at present.
The commercially available reverse osmosis membranes generally include a thin film composite (TFC) membrane comprising a combination of a support such as polysulfone and a selective layer formed thereon by interfacial polymerization of an amine monomer in an aqueous solution and an acyl chloride monomer in an organic solvent. I have.
Interfacial polymerization membranes made in this format have been sold by DuPont since 1977 and have now achieved many of the commercial membrane markets with superior performance over previous membranes. However, current commercial reverse osmosis membranes are not only effective for salt removal but also excessively thick in the selective layer, and are highly contaminated by surface irregularities, and polysulfone as a support is not excellent in chemical durability, Have.
Therefore, it is desirable to use a material having excellent chemical durability to diversify the utilization field and to control the concavo-convex structure of the surface to increase the service life. Of the population. In addition, it is expected that the technique of maintaining the density of the selective layer to preserve the salt removal ratio and to increase the water permeability by lowering the thickness is also expected to attract attention in the market.
It is known that the structure of the polysulfone interfacial polymerization separator is formed by the characteristics of the polysulfone support itself. Since the polysulfone support is relatively hydrophobic, the hydrophilic monomer actively participates in the reaction, and the thickness of the selective layer becomes thick. As a result, the hydrophilic monomer existing in a larger amount than the membrane surface in the pores due to the pores is over- The surface irregularity structure is formed. However, using the existing interfacial polymerization method, it is not possible to construct a selective layer which is stable on a support other than polysulfone and has excellent salt removal performance, because the speed and progress of the polymerization reaction depend entirely on the characteristics of the support as described above .
Therefore, in order to obtain a selective layer having a small thickness at the high-durability support and low water-repellency and high water permeability, the support should have sufficient water permeability without voids on the surface thereof, The reaction of the monomer can be appropriately controlled so that a layer with a thin thickness and a low concavity and convexity and a dense structure can be formed.
Numerous references are referenced throughout the specification and are cited therein. The disclosure of the cited document is incorporated herein by reference in its entirety to more clearly describe the state of the art to which the present invention pertains and the content of the present invention.
The present inventors have made efforts to solve the problem of excessive thickness and surface irregularity of a selective layer which occurs when the conventional interfacial polymerization method is used. As a result, when introducing the intermediate layer on the porous support layer and introducing the selective layer using the new interfacial polymerization method in which the existing interfacial polymerization method is modified, the thickness of the selective layer can be minimized and the problem of concavity and convexity can be solved , Thereby completing the present invention.
It is therefore an object of the present invention to provide a novel TFC separator wherein an intermediate layer is introduced and a selective layer is introduced using a new interfacial polymerization method.
Another object of the present invention is to provide a separator having a novel structure including an intermediate layer and a selective layer having a minimum thickness and no external surface irregularities.
It is still another object of the present invention to provide a method for producing the separator.
Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention, claims and drawings.
In one aspect of the present invention, there is provided a thin film composite (TFC) separator comprising a porous support and a polymer selective layer formed on the support, wherein a thin film composite separator is provided between the support and the polymer selection layer, And the selective layer is a monolayer.
Porous support
The term thin film composite (TFC) refers to a composite membrane structure that is currently the most widely sold commercially available, and refers to a complex structure in which a polymeric selective layer is formed on a porous support.
The porous support included in the TFC structure functions to impart excellent mechanical strength to the separation membrane, and may be formed on a non-woven fabric support such as a nonwoven fabric.
The porous support used in the separator of the present invention may be a microfiltration (MF) membrane or an ultrafiltration (UF) membrane having a pore size of 1 nm to 1 μm.
Preferably, an ultrafiltration membrane having a pore size of 1 nm to 1 m can be used as the porous support.
The material of the porous support can be used without limitation as long as it is commonly used in microfiltration or ultrafiltration membrane production. In one embodiment, the porous support is made of polyacrylonitrile, polysulfone, polycarbonate, , Cellulose, cellulose acetate, polyethersulfone, polyvinylpyrrolidone, laminated polysulfone, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, May contain at least one polymer component selected from the group consisting of polyvinylidene fluoride, polypropylene, polyvinyl chloride, polyetherimide, polyphenylene sulfide and polyether ether ketone, But is not limited thereto.
Middle layer
The separation membrane of the present invention is characterized in that it comprises an intermediate layer in the form of a film between the porous support and the polymer selection layer to close the pores of the support.
In the case of the conventional TFC separator, since a large amount of monomers is introduced into the pores of the support during the manufacturing process, the monomers are excessively reacted, thereby increasing the thickness of the selective layer and forming a surface irregular structure. On the other hand, The separation membrane is formed by introducing a film-like intermediate layer composed of a polymer or an inorganic material onto a porous support before the interfacial polymerization, thereby solving the problem of irregularities due to the pores of the support, and thereby manufacturing an interfacial polymerization selective layer .
The method of attaching the intermediate layer to the support may be any method that can be used without limitation as long as it is attached to the support in a flat shape and can close the pores and may be manufactured by layer-by-layer assembly (LBL) But is not limited to.
In one embodiment, the intermediate layer may be attached to the surface of the support by a covalent bond, a charge bond, an electrostatic bond, a van der Waals force or a hydrogen bond.
In other embodiments, the intermediate layer of the present invention may have a pore size of less than 1 nm.
The material of the intermediate layer can be used without limitation such as an inorganic material or a polymer material as long as it can be attached to the support in a flat shape and can close the pores. For example, the intermediate layer may be made of polyethyleneimine, polyacrylic acid, Acrylamide-co-diallyldimethylammonium chloride, poly 2-acrylamido-2-methyl-1-propanesulfonic acid 2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylonitrile) acrylonitrile (hereinafter referred to as " acrylonitrile & ), Polyallylamine, polyallylamine hydrochloride, polyanetholesulfonic acid, poly [bis (2-chloroethyl) ether-alt-1,3-bis [3 - (diethylamino) propyl] (Dimethylamino) propyl] urea] quaternized), poly (diallyldimethylammonium chloride), polydimethylamine (poly (dimethylamino) Co-ethylenediamine, poly 2-ethyl-2-oxazoline, polysodium 4-styrene (co-ethylenediamine) Poly 4-styrenesulfonic acid, Poly 4-styrenesulfonic acid-co-maleic acid, Polyvinylsulfonic acid-co-maleic acid, But is not limited to, one or more polymer components selected from the group consisting of polyvinyl sulfate and polyvinylsulfonic acid.
Selective layer
In addition, the separator of the present invention is characterized in that a selective layer is formed on the intermediate layer as described above, and in particular, the selective layer is formed as a monolayer.
In order to solve the problem of unevenness of the selective layer, the present inventors have recently developed a separator using a porous support and an intermediate layer, and then used a layer-by-layer assembly (LBL) , A selective layer having a small thickness and small irregularities has been produced. In this case, since the selective layer is produced through a sequential reaction through a repetitive layer of the monomer, the selective layer is formed of a polymer multilayer.
In the case of using this method, the repeating layer reaction of 10 to 15 cycles is required for the production of the selective layer of the desired thickness, which is a difficulty in commercialization of the technology, while the separator of the present invention does not require the repetitive layer reaction , And a monolayer selective layer formed by a 1-step polymerization reaction.
The 1-step polymerization used for introducing the single-layer selective layer of the present invention into the intermediate layer is an interfacial polymerization method instead of the layer-by-layer assembly (LBL) As a new interfacial polymerization method, the present inventors named it a limit interface polymerization method. This will be described below in detail in the manufacturing method section.
In one embodiment, the selective layer is characterized by having no irregularities on its outer surface, with a pore size of 0.1 nm or less, or substantially no pore, and the thickness is within 50 nm.
As described above, in the present invention, since the reaction of the monomers can be appropriately controlled during the production of the selective layer, it is possible to produce a layer having a small thickness of the selective layer formed on the intermediate layer and a compact structure and a dense structure.
As the material of the selective layer, any material capable of exhibiting characteristics inherent to the separation membrane can be used without limitation. Examples of the selective layer include polyamide, polyfurane, polyether-polyfurane, But are not limited to, sulfonated polysulfone, polyamide via polyethylenimine, polyamide via polyepiamine, polyvinylamine, polypyrrolidine, polypiperazine- Amorphous polyamide, polypiperazine-amide, Fully Aromatic Polyamide, Cross-linked Polyamide, Cross-linked Fully Aromatic Polyamide, Cross-linked aralkyl polyamide (Cross-linked Aralkyl Polyamide), and Resorcinol based polymer. But is not necessarily limited thereto.
Another aspect of the separation membrane of the present invention is that it comprises a porous support, an intermediate layer formed on the support to close the pores, and a polymer selected by interfacial polymerization on the intermediate layer. Layer, wherein the thickness of the selective layer is within 50 nm, and there is no surface irregularity on the outside of the separating film.
In the case of the separator according to the present invention, although the selective layer is formed by the interfacial polymerization method, the selection layer is thinner and focuses on the absence of external irregularities. Instead, But is not limited to.
The TFC separation membrane of the present invention can be used as a separation membrane for water treatment, which is utilized for living and industrial water, various domestic sewage and industrial wastewater treatment, water treatment of drinking water and water, and contaminants such as inorganic ions, bacteria, viruses, organic and colloid; Or as a separation membrane for gas treatment which is used for separating or removing hydrogen, helium, oxygen, nitrogen, carbon monoxide, carbon dioxide, water vapor, ammonia, sulfur compounds, hydrocarbon gases and biogas or for removing moisture in compressed air.
In addition, the separation membrane of the present invention can be used for desalination of seawater, recycling of concentrated water, softening, ion separation, production of pure water, preparation of pure water for medical use, production of fixed water, concentration of liquid, Separation of alkali metal, recovery of acid alkali, etc., as a reverse osmosis membrane for separation of ultrafine solute having a molecular size of 10 Å or less; Microparticles such as microparticles, bacteria, proteins, thickeners, pigments and organic compounds in the molecular weight range of 250 to 1000 MW, such as high flow nano filtration, chemical precipitation nanofiltration, nanofiltration for removal of airborne fine particles, To remove nanoparticles.
Yet another aspect of the present invention is a method of preparing a porous support, comprising: (i) preparing a porous support; (ii) forming a film-form intermediate layer on the surface of the porous support to close the pores of the porous support; And (iii) forming a selective layer on the intermediate layer by an interfacial polymerization method.
In an embodiment of the present invention, the intermediate layer in the film form in the step (ii) may be formed by a layer-by-layer assembly (LBL) method.
The LBL method comprises the steps of: a) adsorbing a polymer electrolyte A having an opposite charge to a surface of a support on a surface thereof by using a) a dip coating on the porous support; b) applying a polymer electrolyte B having a charge opposite to that of the previously adsorbed polymer electrolyte, And c) removing the residual adsorbate by washing. The process of steps a) to c), if necessary, may be carried out in the same manner as the steps of a) to c) Can be repeatedly performed.
On the other hand, in the method of the present invention, the interfacial polymerization method of step (iii) is not a conventional interfacial polymerization method but is a limiting interfacial polymerization method developed for the present inventors.
The inventors of the present invention have found that when a layer-by-layer assembly (LBL) method is used to form a selective layer on an intermediate layer, repetitive lamination is required. Therefore, in order to solve the problem that a long time is consumed and a large amount of organic solvent is used, We tried to apply the interfacial polymerization method instead of the existing LBL method.
However, when the known interfacial polymerization method is applied as it is, the thickness of the selective layer becomes excessively thick, and the surface irregularity problem is still not solved in spite of the presence of the intermediate layer. As a result, It was impossible to form a monolayer selective layer having a small thickness and no surface irregularities.
Conventional interfacial polymerization may include the step of removing excess monomer present in the pores using a roller or washing to control the thickness of the selective layer, but when the cleaning is performed strongly, the monomer adsorbed on the surface is excessively removed And there is a problem that defects are generated in the selective layer. Therefore, generally, only a weak washing process is performed in the solvent so as to shake the support.
Under such circumstances, the present inventors have surprisingly found that, when an intermediate layer free of voids is first introduced onto a support and a monomer for interfacial polymerization is introduced, the defect of the selective layer does not occur even if a very strong washing process is performed . Accordingly, the limiting interface polymerization method of the present invention is characterized in that a strong washing process is performed to remove excess monomers at a high strength.
Thus, in the interfacial polymerization step (iii) of the present invention, the porous support on which the intermediate layer is formed is supported on the solution containing the interfacially polymerized monomer in step (a), and the monomer is adsorbed to the functional group in the interfacial layer ; (b) Strongly washing the monomer in an amount such that the equivalent ratio of the functional group to the monomer in the middle layer does not exceed 1: 1 to remove excess monomer; And (c) polymerizing the adsorbed monomer.
The limiting interfacial polymerization method of the present invention may further comprise, after the step (c), (d) removing the residual monomer by washing with the same solvent to complete the interfacial polymerization, (D) may be repeatedly performed.
In one embodiment of the invention, the cleaning procedure may be performed with an intensity such that the equivalence ratio of functional groups to monomers in the interlayer is greater than 1: 1 to 1: 1.
According to another embodiment, the cleaning process may be carried out at a strong enough strength to leave only the monolayer of monomers on the intermediate, which is then thoroughly soaked in a solvent free of monomers and then vigorously agitated so that the physical The friction can be performed in a manner of repeatedly applying the friction for 1 minute to 5 minutes.
As described above, the limiting interface polymerization method of the present invention is a technique for improving the excess solution removal process so that a smaller amount of monomer reacts with the interfacial polymerization than the conventional interfacial polymerization, so that the monomer is adsorbed on the surface The amount of the monomer to be reacted on the surface is minimized through strong washing in the solvent and removal of the residual solution, thereby minimizing the thickness of the selective layer and solving the irregularity problem.
The present invention relates to an interfacial polymerization selective layer having a high density and a small surface irregularity with a low thickness regardless of the type of support, introducing an intermediate layer having a high water permeability on a porous support, And a high water permeability can be realized.
FIG. 1 is a schematic view showing a step according to an embodiment of the present invention. (A) shows an enlarged view of the pores of the porous membrane to be used as a support, and (B) shows a film-like intermediate layer introduced by the LBL method (red: polymer layer having opposite charge to the surface of the support, A polymer layer having opposite charge to the red polymer layer). (C) shows a state in which a hydrophilic interfacially polymerized monomer is adsorbed on an intermediate layer in the form of a film. (D) shows a state in which a selective layer is formed as a single layer by a one-step polymerization reaction by inducing interfacial polymerization with a hydrophilic interfacial polymerizable monomer with a hydrophilic organic monomer (yellow: a single selective layer formed by one step interfacial polymerization, : Organic solvent).
2 shows the result of observing the surface structure of the film using a scanning transfer microscope (SEM). 2A is a separation membrane prepared by general interface polymerization, and FIG. 2B is a separation membrane manufactured by limiting interface polymerization. In the case of the separation membrane of FIG. 2B, unlike FIG. 2A, it can be seen that there are almost no external surface irregularities.
Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for describing the present invention more specifically and that the scope of the present invention is not limited by these embodiments.
Example
Material selection
As the porous support, a PAN support having a pore size of about 20 nm was used.
The middle layer was prepared by using LbL using a polymer electrolyte. Poly (ethyleneimine) (PEI) was selected as a polymer having a positive charge and poly (acrylic acid) (PAA) as a polymer having a negative charge, and each aqueous solution was prepared using a supporting method. Alternately stacked.
In relation to the interfacially polymerized monomer and the solvent, m-phenylenediamine (MPD) was used as a hydrophilic solvent and water, and n-hexane was used as an organic solvent and trimesoyl chloride (TMC) was used as a monomer. .
Manufacturing method
(1) Preparation of the intermediate layer by using the selected polymer electrolyte on the selected porous support.
First, a polymer electrolyte A having an opposite charge to the surface of the support was adsorbed on the surface by dip coating on the porous support.
Next, the polymer electrolyte B having a charge opposite to that of the previously adsorbed polymer electrolyte was re-adsorbed using dip coating, and the intermediate layer was completed using the attraction force between the polymer electrolyte and the remaining adsorbate was removed through washing.
(2) Preparation of selective layer by interfacial polymerization on porous support with intermediate layer.
The intermediate layer prepared above was immersed in the amine aqueous solution for a sufficient time to adsorb the amine monomer. Then, the flat membrane on which the monomer was adsorbed was completely immersed in a solvent containing no monomer, and then strongly stirred to remove physical excess of monomer by repeatedly applying physical friction between the solvent and the membrane surface for 3 minutes.
Then, the solution was supported on an acyl chloride monomer solution prepared from a solvent which did not mix with an aqueous solution to induce interfacial polymerization. The degree of polymerization was controlled by controlling the reaction time.
Thereafter, the residual monomer was removed by washing with the same solvent to complete interfacial polymerization.
Separator Performance test
The interfacial polymerization conditions were 1 minute reaction time, and the PEI / PAA reaction time was 15/10 minutes. Two washings of 2 minutes each were used. The porous support was surface modified by hydrolysis of a commercial PAN ultrafiltration membrane (pore size ~ 20 nm) in aqueous NaOH solution.
The performance of the final membrane thus prepared was tested and the results are shown in Table 1 below.
(L / m 2 h)
As a result of the experiment, it was confirmed that a membrane having higher water permeability and salt rejection rate than those that can be achieved by the conventional interfacial polymerization method can be produced. In addition, the monomer used in the interfacial polymerization can be variously classified into various types. It is confirmed that it can be used.
It is expected that a separator that exhibits the above performance as a result of further process improvement and study of the middle layer and monomer is also expected to be manufactured.
Membrane surface characteristics
In order to more precisely confirm the surface state of the final membrane thus prepared, a scanning electron microscope (SEM) was used and the results are shown in FIG.
As a result, it was confirmed that although the same monomers were used on the same support, the irregularity of the surface was remarkably reduced in the film having the intermediate layer introduced therein.
Based on the results of previous studies, it is predicted that the membrane produced by this technique will have greater resistance to contamination than conventional membranes, as the surface irregularities are smaller.
Claims (15)
A film-form intermediate layer between the support and the polymeric selective layer to close the pores of the support,
RTI ID = 0.0 > 1, < / RTI > wherein the selective layer is a monolayer.
A film-form intermediate layer formed on the support to close the pores, and
And a polymer selective layer formed on the intermediate layer by interfacial polymerization,
Wherein the thickness of the selective layer is within 50 nm, and there is no surface unevenness on the outside.
(ii) forming a film-form intermediate layer on the surface of the porous support to close the pores of the porous support; And
(iii) forming a selective layer on the intermediate layer by an interfacial polymerization method
≪ / RTI >
(a) supporting a porous support having an intermediate layer formed thereon in a solution containing an interfacially polymerized monomer in step (ii), thereby adsorbing the monomer to the interfacial functional group;
(b) Strongly washing the monomer in an amount such that the equivalent ratio of the functional group to the monomer in the middle layer does not exceed 1: 1 to remove excess monomer; And
(c) polymerizing the adsorbed monomer
≪ / RTI >
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20210084268A (en) * | 2019-12-27 | 2021-07-07 | 닛토덴코 가부시키가이샤 | Composite semi-permeable membrane |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100480989B1 (en) | 1998-10-29 | 2005-10-06 | 주식회사 새 한 | Manufacturing method of reverse osmosis membrane with high flux and high exclusion ratio of salts |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100480989B1 (en) | 1998-10-29 | 2005-10-06 | 주식회사 새 한 | Manufacturing method of reverse osmosis membrane with high flux and high exclusion ratio of salts |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20210084268A (en) * | 2019-12-27 | 2021-07-07 | 닛토덴코 가부시키가이샤 | Composite semi-permeable membrane |
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