KR20220083902A - Method of fabricating thin-film composite membrane with interlayer structure and its applications - Google Patents

Abstract

The present invention relates to a method of manufacturing a high-performance thin-film composite separator including an intermediate layer structure, and more particularly, by mixing carbon nanotube (CNT), a one-dimensional nanomaterial, and MXene, a two-dimensional nanomaterial, to form a porous After coating on the surface of the support, comprising the step of forming an active layer using interfacial polymerization, the method for manufacturing a thin film composite separation membrane for reverse osmosis, forward osmosis, and nanofiltration, which can improve water permeability and salt selectivity, and its application it's about

Description

Method of fabricating thin-film composite membrane with interlayer structure and its applications

The present invention relates to a method of manufacturing a high-performance thin-film composite separator including an intermediate layer structure, and more particularly, by mixing carbon nanotube (CNT), a one-dimensional nanomaterial, and MXene, a two-dimensional nanomaterial, to form a porous After coating on the surface of the support, comprising the step of forming an active layer using interfacial polymerization, the method for manufacturing a thin film composite separation membrane for reverse osmosis, forward osmosis, and nanofiltration, which can improve water permeability and salt selectivity, and its application it's about

In the forward osmosis process, water from the low salinity side (feed solution) passes through the semipermeable membrane spontaneously by osmotic pressure without external driving pressure and moves to the high salinity side (derivation solution) to concentrate and induce the feed solution. As a process technology that can dilute a solution, the forward osmosis process and the hybrid process using forward osmosis can reduce energy consumption and lower membrane contamination compared to the existing reverse osmosis and nanofiltration processes. It is being actively researched and applied in a wide range of fields such as fertilizer dilution for agriculture.

This forward osmosis membrane has been developed in the form of a thin-film composite (TFC) composed of a porous support and a selective layer, similar to a reverse osmosis membrane, and, in addition, a support or a selective layer is formed using a nanomaterial. It is generally developed in the form of a modified thin-film nanocomposite (TFN).

TFC and TFN membranes have a wide operating pH (pH 2 - 11) and good heat resistance at a level of 60 ° C. However, the process application is limited due to the trade-off of water permeability-selectivity. are receiving That is, TFC and TFN separation membranes have a disadvantage in that they have relatively low water permeability (1-20 LMH/bar) under salt selection performance conditions above a certain level.

In order to increase the water permeability and salt selectivity of the forward osmosis membrane, it is necessary to improve the porous support as well as the selective layer. In order to minimize the internal concentration polarization (ICP) phenomenon that reduces the efficiency of the forward osmosis process inside the support, a polyethersulfone microfiltration membrane is used instead of the commonly used ultrafiltration membrane (UF). MF), it is preferable to use a support having a higher porosity and higher hydrophilicity than a conventional UF membrane. However, when such a support with high porosity and large surface voids is used, the polyamide selective layer easily penetrates into the support as shown in FIG. is accompanied by

Accordingly, the present inventors made diligent efforts to solve the above problems (trade-off, ICP, etc.). As a result, a microfiltration membrane with large pores is applied as a support as a selective layer, but a thin film including an intermediate layer structure between the two layers. Developing a method for manufacturing a composite separation membrane, and confirming that the separation membrane including the intermediate layer structure has better performance than the separation membrane without the intermediate layer structure, and can be applied to various fields such as useful resource recovery and fertilizer dilution, The invention was completed.

It is an object of the present invention to provide a method for manufacturing a thin film composite separator having high water permeability and salt selectivity including an intermediate layer structure.

In addition, an object of the present invention is to provide an environmental application (useful resource recovery and fertilizer dilution, etc.) using the separation membrane manufactured by the above manufacturing method.

In order to solve the above problems, the present invention provides a method for manufacturing a composite separator having an intermediate layer structure comprising the following steps:

(a) preparing an interlayer preliminary solution for the interlayer structure shape;

(b) coating the intermediate layer preliminary solution on the surface of the porous support; and

(c) forming a selective layer/active layer on the support coated with the intermediate layer.

According to the present invention, the intermediate layer preliminary solution of step (a) is nanoparticles (ZnO, TiO ₂ ), one-dimensional (SWCNT, MWCNT), two-dimensional (GO, MXene, MoS ₂ ) nanomaterials and modified nanomaterials thereof , or may be a material containing a polymer (polydopamine, polyvinyl alcohol) capable of interfacial coating.

According to the present invention, the support of step (b) is PSF (polysulfone), SPSF (sulfonated polysulfone), PES (polyethersulfone), SPES (sulfonated polyethersulfone), PVDF (polyvinylidene fluoride), PAN (polyacrylonitrile), PTFE (polytetra fluoroethylene) ) and the like, and may be made of a material including at least one of the above material groups.

According to the present invention, the coating of step (b) may be performed by vacuum filtration, spraying, electrospinning, brushing, or the like.

According to the present invention, the selective layer / active layer of step (c) is interfacial polymerization (interfacial polymerization), dipping (dipping), layer-by-layer (layer-by-layer) or double-layer slot coating (dual layer slot coating) by can be formed.

At this time, the interfacial polymerization includes the steps of i) forming an interface between the two solutions using a polar solution in which the first monomer is dissolved in a polar solvent and a non-polar solution in which the second monomer is dissolved in a non-polar solvent, and ii) the formed Inducing a polymerization reaction between the first monomer and the second monomer at the interface may include forming a selective layer.

In this case, the first monomer is an aromatic and aliphatic amine, alcohol or a molecule having a hydroxyl end group, MPD (m-phenylene diamine), OPD (1,2-phenylene diamine), PPD (1,4-phenylene diamine), MDA(methane diamine), MXDA(M-xylene diamine), IPDA(isophoroediamine), DETA(diethylene triamine), TETA(triethylene tetramine), EDA(ethylenediamine), DEPA(diethyl propyl amine), PIP(piperazine), PEI( Polyetherimide), N-AEP (N-aminoethyl piperazine), and PVA (polyvinyl alcohol) may be selected from the group consisting of,

The second monomer is a molecule having an acyl chloride end group, TMC (trimesoyl chloride), PC (phthaloyl chloride), IPC (isophthaloyl chloride), TPC (terephthaloyl chloride), HTC (cyclohexane-1,3,5tricarbonyl chloride) consisting of may be selected from the group.

In addition, the polar solvent may be at least one selected from the group consisting of water, methanol, ethanol, propanol, butanol, isopropanol, ethyl acetate, acetone and chloroform.

In addition, the non-polar solvent may be at least one selected from the group consisting of hexane, pentane, cyclohexane, heptane, octane, carbon tetrachloride, tetrahydrofuran, benzene, and toluene.

The present invention also provides a composite separator prepared according to the above manufacturing method and including an intermediate layer structure between the porous support and the selective layer/active layer.

The present invention also provides a water treatment method using a composite separator including the intermediate layer structure.

The present invention also provides a method for recovering and concentrating useful resources using the composite membrane including the intermediate layer structure.

The present invention also provides a method for diluting high-concentration wastewater/fertilizer using a composite membrane including the intermediate layer structure.

According to the present invention, it is possible to manufacture a composite separation membrane including an intermediate layer structure having various supports other than the conventional ultrafiltration membrane (UF) support, in particular, a support having larger pores than a UF support, and the prepared separation membrane is not only forward osmosis but also forward osmosis. , can be effectively applied to separation membranes such as reverse osmosis and nanofiltration. In addition, the prepared separation membrane has high water permeability and high specific solute selectivity, and can alleviate trade-off and internal concentration polarization (ICP) problems of existing separation membranes, water treatment, useful resource recovery and high concentration wastewater, fertilizer It can be usefully used in various fields such as dilution.

1 shows a manufacturing process of a composite separator (TFNi) including an interlayer structure according to the present invention, (a) is a manufacturing process of a thin film composite (TFC) membrane without an existing interlayer structure, (b) is the present invention The TFNi film manufacturing process is shown.
Figure 2 shows the performance of the TFC membrane and the TFNi membrane according to various loads of the intermediate layer structure, (a) is the water permeability ( Jw ) and reverse salt permeability ( Js ), (b) is the specific salt permeability ( Js/Jw ) ) is indicated.
3 shows the performance of the TFC membrane and the TFNi membrane according to the concentration of the draw solution, (a) is the water permeability ( Jw ), (b) is the reverse salt permeability ( Js ), (c) is the specific salt permeability ( Js/ Jw ).
4 is a comparison of the application performance of the TFC membrane and the TFNi membrane, (a) is the concentration efficiency of the wastewater, (b) is a change in the water flux according to the increase in the wastewater recovery rate, (c) is a specific ammonia nitrogen flux and accumulation It represents the mass of ammonia nitrogen.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is those well known and commonly used in the art.

[Example]

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not to be construed as being limited by these examples. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

[ Example ]

Example 1: Manufacture of a composite separator including an intermediate layer structure

(1) material

Porous support : A microfiltration membrane with large pores (0.22 μm, PES MF) was used as a support.

Interlayer solution : A polydopamine (PDA)-modified one-dimensional nanomaterial, carbon nanotube (CNT) solution, and a two-dimensional nanomaterial, Ti ₃ C ₂ T _x maxine (MXene) solution were mixed and used.

Interfacial polymerization monomer and solvent : MPD ( m -Phenylenediamine) or PIP (piperazine) was used for the monomer contained in the hydrophilic solvent, water, and the monomer contained in the organic solvent, n-hexane, was TMC (1, 3,5-benzenetricarbonyl trichloride) was used.

(2) Manufacturing method

Interlayer solution preparation : The 1D and 2D nanomaterials were mixed at a mass ratio of 1:1, and after 10 minutes of sonication, a solution for forming an interlayer structure was prepared.

Interlayer coating : The PES MF support is fixed to a filtration device, the prepared intermediate layer solution is poured on the fixed PES MF support, and the nanomaterial is coated on the surface of the PES MF support through low pressure filtration (0.2 bar), in an oven at 60 ° C. An intermediate layer structure was prepared through drying. The amount of loading of the prepared intermediate layer structure was 4-66 μg/cm ² depending on the volume of the solution.

Selective layer shape : The support having the intermediate layer structure was fixed in a container, and MPD aqueous solution (for forward osmosis membrane/reverse osmosis membrane) or PIP aqueous solution (for nanofiltration membrane) was poured on the intermediate layer and waited for 3 minutes to completely submerge. After removing the remaining MPD aqueous solution, the TMC organic solution was poured, and after waiting 1 minute, a selective layer was prepared through an interfacial polymerization reaction.

Example 2: Including interlayer structure for forward osmosis Membrane performance test

In order to verify the performance of the membrane for forward osmosis prepared by the method of Example 1, feed solution Deionized water (deionized water), flow rate 0.3 L/min, temperature 25 ℃ conditions according to the following (1) or (2) conditions A comparative experiment on water permeability and salt selectivity was performed.

(1) Membrane performance change according to the load of the intermediate layer structure (draw solution concentration: 1.0 M NaCl )

As shown in FIG. 2 , the forward osmosis membrane (TFNi) including the intermediate layer structure has a water permeability (water flux, J _w ) 2 to 4 times higher overall than the control (ie, TFC membrane without the intermediate layer structure), and specific salts Permeability (specific salt flux, J _s / J _w ) was 2 to 4 times lower. In addition, when the loading of the intermediate layer structure was 24.9 μg/cm ² , a higher water permeability of 32.9 LMH than the control ( J _w : 11.2 LMH) was achieved, and the specific salt permeability was reduced from 0.72 g/L to 0.24 g/L. .

(2) Changes in membrane performance according to draw solution concentration (load of intermediate layer structure: 16.6 μg / cm ² )

As shown in FIG. 3, as the concentration of the draw solution increased, the water permeability increased, and when there was an intermediate layer structure, water permeability of 48.4 LMH and specific salt permeability of 0.48 g/L were exhibited in a NaCl draw solution of up to 3.0 M. and maintained higher water permeability and salt selectivity than the control group ( J _w : 24.7 LMH, J _s / J _w : 0.80 g/L).

Through the above results, it was confirmed that the separator for forward osmosis including the intermediate layer structure according to the present invention has very good performance.

Example 3: Including interlayer structure for forward osmosis Verification of actual sewage concentration and fertilizer dilution performance of the membrane

The membrane for forward osmosis prepared according to the method in Example 1 was used as a feed solution to verify the application performance in actual environmental applications, and as a feed solution, potassium chloride (KCl), a fertilizer, a flow rate of 0.3 L/min, temperature Comparative experiments were performed on wastewater concentration efficiency, stability, and selectivity for ammonia nitrogen under 25°C process conditions.

As a result, as shown in FIG. 4 , the TFNi membrane having an intermediate layer structure exhibited very high concentration efficiency compared to the TFC membrane. In addition, it was confirmed that the recovery rate of wastewater, which is the feed solution, reached 50% in less than 24 hours using the TFNi membrane having an interlayer structure, but it was confirmed that it took 100 hours to reach the same recovery rate in the TFC membrane without the interlayer structure (Fig. 4a). This high concentration efficiency (~4.3 times) is due to the high water permeability shown in Example 2 above. Urban wastewater used as a sample was composed of many organic and inorganic contaminants, but no significant decrease in water permeability was seen when considering the dilution effect of the draw solution (FIG. 4b).

In addition, it was confirmed that ammonia nitrogen plus was lowered when a TFNi membrane having an interlayer structure was used (Fig. 4c). When the TFNi membrane was used, the amount of ammonia nitrogen accumulation was lower in the draw solution side than the control TFC membrane.

Through these results, it was confirmed that the separation membrane for forward osmosis including the intermediate layer structure according to the present invention exhibits improved ammonia nitrogen removal or selectivity due to the introduction of the intermediate layer structure as well as high concentration efficiency.

As described above in detail a specific part of the content of the present invention, for those of ordinary skill in the art, it is clear that this specific description is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Accordingly, it is intended that the substantial scope of the present invention be defined by the appended claims and their equivalents.

Claims (8)

(a) preparing an intermediate layer preliminary solution;
(b) coating the intermediate layer preliminary solution on the surface of the porous support; and
(c) a method of manufacturing a composite separator comprising the step of forming a selective layer / active layer on the coated porous support. According to claim 1,
The intermediate layer preliminary solution is one selected from the group consisting of ZnO, TiO ₂ , carbon nanotubes, graphene oxide (GO), maxine (MXene), MoS ₂ , polydopamine and polyvinyl alcohol. A method for manufacturing a composite separator comprising the above. According to claim 1,
The porous support is one selected from the group consisting of polysulfone (PSF), sulfonated polysulfone (SPSF), polyethersulfone (PES), sulfonated polyethersulfone (SPES), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polytetra fluoroethylene (PTFE). A method for manufacturing a composite separator comprising the above. The method of claim 1,
The coating is a method of manufacturing a composite separator, characterized in that the coating is performed by a method selected from the group consisting of vacuum filtration (vacuum filtration), spray (spray), electrospinning (electrospinning) and a brush (brush). According to claim 1,
The selective layer/active layer is formed by a method selected from the group consisting of interfacial polymerization, dipping, layer-by-layer and dual layer slot coating. A method for manufacturing a composite separator, characterized in that 6. The method of claim 5,
The selective layer/active layer by the interfacial polymerization comprises: i) forming an interface between a polar solution in which a first monomer is dissolved in a polar solvent and a non-polar solution in which a second monomer is dissolved in a non-polar solvent; and ii) forming a selective layer by inducing a polymerization reaction between the first monomer and the second monomer at the formed interface. 7. The method of claim 6,
The first monomer is an aromatic and aliphatic amine, an alcohol or a molecule having a hydroxyl end group, MPD (m-phenylene diamine), OPD (1,2-phenylene diamine), PPD (1,4-phenylene diamine), MDA ( methane diamine), MXDA(M-xylene diamine), IPDA(isophoroediamine), DETA(diethylene triamine), TETA(triethylene tetramine), EDA(ethylenediamine), DEPA(diethyl propyl amine), PIP(piperazine), PEI(Polyetherimide) and N-AEP (N-aminoethyl piperazine), and PVA (polyvinyl alcohol). 7. The method of claim 6,
The second monomer is a molecule having an acyl chloride end group, trimesoyl chloride (TMC), phthaloyl chloride (PC), isophthaloyl chloride (IPC), terephthaloyl chloride (TPC) and cyclohexane-1,3,5tricarbonyl chloride (HTC) consisting of Method for producing a composite separator, characterized in that selected from the group.

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