KR102287610B1 - Method for manufacturing water treatment membrane forming composition - Google Patents

Abstract

The present invention relates to a method for manufacturing a composition for forming a water treatment separation membrane which comprises: a step of cooling raw materials comprising a carbon nano material comprising a hydrophilic functional group and a polymer resin; a step of manufacturing powder by pulverizing the cooled raw materials through a pulverizer combined with a screening net; and a step of manufacturing a carbon nano material-polymer resin composite through a mechanical-chemical combining device. According to the present invention, the method can exhibit a high water treatment capability.

Description

Method for manufacturing a composition for forming a water treatment separation membrane {METHOD FOR MANUFACTURING WATER TREATMENT MEMBRANE FORMING COMPOSITION}

The present invention relates to a method for preparing a composition for forming a water treatment separation membrane.

Recently, water shortage is emerging as an important issue in most countries around the world due to the increase in water consumption due to population growth and rapid industrialization and water pollution due to environmental pollution. In addition, it is expected that the demand for water will continue to increase due to the growth of the economy and the development of industries in the future, and the need to secure stable and innovative new water resources is emerging more than ever in preparation for a water shortage in the future.

Research on water environment pollution aims to treat high-quality living and industrial water, various domestic sewage and industrial wastewater, and interest in water treatment processes using separation membranes, which have the advantage of saving energy, is growing. In addition, the accelerating strengthening of environmental regulations is expected to accelerate the activation of 　 separator 　 technology.

Although it is difficult to meet the stricter regulations with the traditional water treatment process, the separation membrane technology guarantees excellent treatment efficiency and stable treatment, so it is expected to become a leading technology in the water treatment field in the future.

Contaminated water separation methods are classified into micro filtration, ultra filtration, nano filtration, reverse osmosis, acupuncture, active transport and electrodialysis according to the pores of the membrane. In addition, according to the shape, it may be classified into a tubular membrane module, a hollow fiber membrane module, a flat membrane module, a spiral wound type module, and the like.

However, in the case of the conventional water treatment membrane, the problem of membrane contamination caused by the deposition of suspended particles on the membrane surface or the deposition of a soluble polymer material or an adhesive material on the membrane is inevitable, and the separation membrane is damaged by a chemical reaction with the substances present in the contaminated water. There is a problem in that the functionality of the separation membrane is gradually reduced due to a change in material, a collision with a solid or the like, or a permanent deformation of the membrane structure due to high pressure.

Therefore, in order to solve the problems of the water treatment separation membrane, it is necessary to develop a separation membrane including a new alternative material.

An object of the present invention is to provide a method for manufacturing a composition for forming a water treatment separation membrane that can prevent membrane contamination, improve durability as it has high mechanical strength, and exhibit high water treatment capability.

An embodiment of the present invention comprises the steps of cooling a raw material comprising a carbon nanomaterial and a polymer resin including a hydrophilic functional group, pulverizing the cooled raw material through a pulverizer coupled with a screen network to prepare a powder, and a machine -Provides a method for preparing a composition for forming a water treatment separation membrane, comprising the step of preparing a carbon nanomaterial-polymer resin composite including a hydrophilic functional group through a chemical bonding device.

The average particle diameter of the powder may be 1.0 mm or less.

The carbon nanomaterial may include at least one selected from the group consisting of graphite, graphene, carbon black, carbon nanotube, carbon fiber, carbon nanoribbon, carbon nanobelt, carbon nanorod, and activated carbon.

The hydrophilic functional group may be selected from a hydroxyl group, a carboxyl group, a carbonyl group, an oxide group, a thiol group, an amine group, or a combination thereof.

As described above, according to the composition for forming a water treatment separation membrane of the present invention, since the carbon nanomaterial contains a hydrophilic functional group, it is possible to efficiently adsorb a very small amount of organic substances or heavy metals present in contaminated water, and compatibility with polymer resins This is excellent, and it is possible to prevent film contamination according to the inherent antibacterial properties of the carbon material.

In addition, there is an effect of improving the physical and mechanical durability of the separation membrane formed therefrom and at the same time exhibiting high filtration performance.

1 is a manufacturing process diagram of a composition for forming a water treatment separation membrane according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

Hereinafter, a method for manufacturing a composition for forming a water treatment separation membrane according to an embodiment will be described.

The present invention exhibits high water treatment ability by efficiently adsorbing a very small amount of organic substances or heavy metals present in contaminated water, prevents membrane contamination according to the inherent antibacterial properties of carbon materials, and has excellent compatibility with polymer resins to improve durability. It relates to a method for preparing a composition for forming an improved water treatment separation membrane.

Specifically, the method for producing a composition for forming a water treatment membrane according to an embodiment of the present invention comprises a step of cooling a raw material comprising a carbon nanomaterial and a polymer resin including a hydrophilic functional group (S1), a pulverizer coupled with a screen network A step of preparing a powder by pulverizing the cooled raw material through (S2) and a step (S3) of manufacturing a carbon nanomaterial-polymer resin composite including the hydrophilic functional group through a mechanical-chemical coupling device (S3).

The manufacturing method of the composition for forming a water treatment separation membrane according to the present invention uses a high-speed rotational mixing device, that is, a fine particle-shaped powder instead of a conventional pellet-type raw material for the formation of a carbon nanomaterial-polymer resin composite through a mechanical-chemical coupling device. It is possible to improve the dispersing power of the carbon nanomaterial-polymer resin composite by using it. If the raw material is not a powder having a fine particle shape, the dispersibility of the carbon nanomaterial-polymer resin composite may not be improved, and the carbon nanomaterial-polymer resin composite may not be smoothly formed through the mechanical-chemical coupling device.

Accordingly, the present invention further includes the step of cooling the raw material before grinding it in order to prevent thermal deformation of the raw material due to frictional heat in the process of pulverizing the raw material in the conventional pellet form, and manufacturing the raw material in the form of fine particles In order to do this, the above problem was solved by using a grinder with a screen net of a certain size.

First, the step (S1) is a step of rapidly cooling the raw material including the carbon nanomaterial and the polymer resin including the hydrophilic functional group in order to facilitate the pulverization of the raw material.

The cooling may be performed rapidly by, for example, introducing the carbon nanomaterial and the polymer resin including the hydrophilic functional group into a flask left by liquid nitrogen. As the raw material including the carbon nanomaterial and the polymer resin including the hydrophilic functional group is rapidly cooled, its properties are further solidified, and there is an advantage in that it can be more efficiently produced in the form of a powder even by the same shear force in the grinding step.

In one embodiment, the carbon nano material is graphite, 　 graphene (graphene), carbon black (carbon black), 　 carbon nanotube (carbon nanotube, CNT), carbon fiber (carbon fiber), 　 carbon nano ribbon (carbon) nano-riboon), carbon nano-belt, carbon nano-rod, and activated carbon may be at least one selected from the group consisting of, preferably graphene (graphene). ), carbon nanotube (CNT), or a combination thereof. The carbon nanotube may be a single-wall nanotube, a multi-wall nanotube, a rope nanotube, or a mixture thereof.

The carbon nanomaterial is included in the composition for forming a water treatment separation membrane due to its high aspect ratio, etc., and may exhibit the effect of improving the physical and mechanical strength of the water treatment separation membrane prepared therefrom. Thus, membrane contamination can be prevented.

The carbon nanomaterial may be included in an amount of 0.1 part by weight to 1 part by weight, for example, 0.5 part by weight to 1 part by weight, based on 100 parts by weight of the composition for forming a water treatment separation membrane. If the content of the carbon nanomaterial is less than 0.1 part by weight, the physical and chemical durability and mechanical properties of the water treatment membrane may not be completely secured, and if it exceeds 1 part by weight, the dispersibility of the composition for forming a water treatment membrane may be reduced. there is.

The carbon nanomaterial is a hydroxyl group (-OH), a carboxyl group (-COOH), a carbonyl group (-COO-), an oxide group (-O-), a thiol group (-SH), an amine group (-NH ₂ ) or these It may include a hydrophilic functional group selected from combinations, for example, a hydroxyl group, a carboxyl group or an oxide group. As the carbon nanomaterial contains a hydrophilic functional group, the dispersibility in the composition for forming a water treatment separation membrane is improved, the compatibility with the polymer resin is increased, and a very small amount of organic substances or heavy metals such as dyes or pharmaceuticals in contaminated water. Adsorption of inorganic materials such as may be increased.

The hydrophilic functional group may be, for example, introduced by reacting the carbon nanomaterial with an acidic or basic solution and a catalyst. As the acidic solution, sulfuric acid (H ₂ SO ₄ ), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), or a mixture of these solutions may be used, and potassium permanganate (KMnO ₄ ) or chloric acid to promote oxidation An oxidizing agent such as potassium (KClO ₃ ) may be added.

When the carbon nanomaterial includes a hydrophilic functional group, the ratio of the hydrophilic functional group to 100% of carbon atoms contained in the carbon nanomaterial may be 5 to 40 atomic%. When the ratio of hydrophilic functional groups is less than 5 atomic%, the hydrophilicity of the carbon nanomaterial is not sufficiently imparted, so it is difficult to properly improve the filtration performance of the water treatment membrane. Since the viscosity of the composition is excessively increased, the inflow of the nonsolvent may be inhibited, and thus the filtration performance of the prepared water treatment separation membrane may be reduced.

In one embodiment, the polymer resin is a polymer that is the main component of the separator, and there is no particular limitation as long as it can be effectively mixed with carbon nanomaterials to manufacture a separator, polyamide-based, polysulfone-based, polycarbonate-based, fluorine-based, One containing at least one selected from the group consisting of cellulose acetate may be used.

The polymer resin may be included in an amount of 0.1 parts by weight to 10 parts by weight, for example, in an amount of 0.9 parts by weight to 9 parts by weight, based on 100 parts by weight of the composition for forming a water treatment separation membrane. If the content of the polymer resin is out of the range, there may be a problem that may occur as the content of the carbon nanomaterial is out of the range.

Next, the step (S2) is a step of pulverizing the raw material rapidly cooled in the step (S1) and manufacturing it in the shape of a powder. can be manufactured.

The diameter of the screen net may be 0.6 mm to 1.0 mm, for example, 0.7 mm to 0.9 mm, and preferably a screen net having a diameter of 0.8 mm may be used. If the diameter of the screen mesh is smaller than 0.6 mm, the cooled raw material cannot pass through, resulting in clogging. It is preferable to use that which is

The pulverizer may be, for example, a mixer-type machine and a pulverizer.

In one embodiment, the average particle diameter of the powder that has undergone the grinding step may be 1.0 mm or less, preferably 0.8 mm or less. As the particle size of the powder increases, the surface area thereof increases, so that the carbon nanomaterial-polymer resin composite including a hydrophilic functional group can be easily formed. The average particle diameter of the powder may be measured using an Anton-Paar particle size analyzer (Litesizer 500).

Next, step (S3) is a step of manufacturing a carbon nanomaterial-polymer resin composite including a hydrophilic functional group through a mechano-chemical bonding device using the powder prepared in step (S2).

The raw material prepared as a uniform granular powder through the pulverizer can prevent the aggregation of conductive fillers such as carbon nanomaterials containing hydrophilic functional groups through a mechanical-chemical bonding device, so that the dispersing power of the conductive fillers in the polymer resin can be maximized. Accordingly, there is an effect of improving the physical durability and mechanical properties of the polymer resin composite material separator even when a small amount of conductive filler is added to the composition for forming a water treatment separator, and the amount of conductive filler such as carbon nanomaterial in the composition is reduced. There is also an advantage in that the production cost of the water treatment separation membrane can be lowered by reducing it.

The mechanochemical coupling device may include an outer container in a stationary state, a rotatable inner container, and an armor comprising a scraper stationary installed within the inner container and an armhead.

The step of preparing the carbon nanomaterial-polymer resin composite including the hydrophilic functional group is performed under conditions of 0.1 to 2 mm spacing between the inner container and the armhead and 1,000 to 3,500 rpm in revolutions per minute of the inner container for 1 to 60 minutes. can be performed.

In the case of using the device having the above configuration, as the distance between the armor and the inner container is adjusted and then rotated at high speed, the carbon nanomaterial and the polymer resin are complexed with high mechanical and chemical energy due to friction with the armor, and each component The dispersibility of the carbon nanomaterial is improved, and accordingly, a carbon nanomaterial-polymer resin composite precisely mixed at the nanoscale can be prepared without a separate solvent or binder.

In this case, the mechanochemical coupling device is as defined above, and as long as it is a device capable of exhibiting an effect equivalent to that in the present invention, it can be used without limitation in its configuration.

According to an exemplary embodiment of the present specification, the 　 water treatment 　 separation membrane may be used as a micro filtration membrane, an ultra filtration membrane, a nano filtration membrane, or a reverse osmosis membrane, and specifically, a reverse osmosis membrane. can be used

Another exemplary embodiment of the present specification provides a water treatment module including one or more of the aforementioned water treatment membranes.

The specific type of the water treatment module is not particularly limited, and examples thereof include a plate & frame module, a tubular module, a hollow & fiber module, or a spiral wound module. In addition, as long as the 　 water treatment module includes the water treatment 　 separation membrane according to an exemplary embodiment of the present specification, other configurations and manufacturing methods are not particularly limited, and general means known in this field may be employed without limitation. there is.

On the other hand, the 　 water treatment module according to an exemplary embodiment of the present specification has excellent salt removal rate and permeate flow rate, and excellent chemical stability, so that it can be usefully used in water treatment equipment such as household/industrial water purification equipment, sewage treatment equipment, sea desalination equipment, etc. there is.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples for a method for producing a composition for forming a water treatment separation membrane according to the present invention. However, the following examples are provided only to help the understanding of the present invention, and the scope of the present invention is not limited thereto.

Preparation Example 1: Preparation of surface-modified carbon nanotubes

Put 5 g of carbon nanotubes (CNTs) into an O ₂ plasma device and apply plasma for 2 to 10 minutes using a voltage of 70 to 120 W to obtain surface-modified carbon nanotubes (Functionalized Carbon Nanotubes, F-CNTs). produced.

Preparation Example 2: Preparation of a composite for forming a PA/F-CNT (90/10) water treatment separation membrane

180 g of polyamide (PA) and 20 g of the surface-modified carbon nanotubes prepared in Preparation Example 1 were put into a flask for liquid nitrogen and rapidly cooled. Thereafter, the cooled polyamide (PA) and F-CNT mixture is pulverized using a polymer pulverizer coupled with a 0.8 mm screen to prepare fine powder having an average particle diameter of 0.8 mm or less.

Next, the prepared powder is put into a mechanical-chemical bonding device and operated at 2,000 rpm for 10 minutes to prepare an F-CNT/PA composite.

Example 1: Preparation of PVDF/F-CNT/PA (90/1/9) water treatment separation membrane

A composition for forming a water treatment membrane was prepared by mixing 180 g of polyvinylidene fluoride (PVDF) and 20 g of the F-CNT/PA composite prepared in Preparation Example 2, which was then used with a twin-screw extruder to produce PVDF/F- CNT/PA was manufactured in the form of a hollow fiber membrane and a flat membrane, and then, a water treatment separation membrane was manufactured through a stretching process.

Example 2: Preparation of PVDF/F-CNT/PA (93/0.7/6.3) water treatment membrane

A polymer composite water treatment membrane was manufactured in the same manner as in Example 1, except that 186 g and 14 g of PVDF and F-CNT/PA were used, respectively.

Example 3: Preparation of PVDF/F-CNT/PA (95/0.5/4.5) water treatment separation membrane

A polymer composite water treatment membrane was manufactured in the same manner as in Example 1, except that 190 g and 10 g of PVDF and F-CNT/PA were used, respectively.

Example 4: Preparation of PVDF/F-CNT/PA (97/0.3/2.7) water treatment membrane

A polymer composite water treatment membrane was manufactured in the same manner as in Example 1, except that 194 g and 6 g of PVDF and F-CNT/PA were used, respectively.

Example 5: Preparation of PVDF/F-CNT/PA (99/0.1/0.9) water treatment separation membrane

A polymer composite water treatment membrane was manufactured in the same manner as in Example 1, except that 198 g and 2 g of PVDF and F-CNT/PA were used, respectively.

Comparative Example 1: PVDF/F-CNT/PA (90/1/9) water treatment separation membrane

PVDF 180g, F-CNT 2g, and PA 18g were simply mixed, and a PVDF/F-CNT/PA composite material was produced in the form of a hollow fiber membrane and a flat membrane using a twin screw extruder, and stretched in the same manner as in Example 1 above. Through the process, a water treatment separation membrane was manufactured.

Comparative Example 2: Preparation of PVDF/F-CNT/PA (93/0.7/6.3) water treatment separation membrane

Except that PVDF 186g, F-CNT 1.4g, and PA 12.6g were used, a polymer composite water treatment membrane was manufactured in the same manner as in Comparative Example 1.

Comparative Example 3: Preparation of PVDF/F-CNT/PA (95/0.5/4.5) water treatment separation membrane

Except for using PVDF 190g, F-CNT 1g, and PA 9g, a polymer composite water treatment membrane was manufactured in the same manner as in Comparative Example 1 above.

Comparative Example 4: Preparation of PVDF/F-CNT/PA (97/0.3/2.7) water treatment separation membrane

A polymer composite water treatment membrane was manufactured in the same manner as in Comparative Example 1, except that 194 g of PVDF, 0.6 g of F-CNT, and 5.4 g of PA were used.

Comparative Example 5: Preparation of PVDF/F-CNT/PA (99/0.1/0.9) water treatment separation membrane

A polymer composite water treatment membrane was manufactured in the same manner as in Comparative Example 1, except that PVDF 198 g, F-CNT 0.2 g, and PA 1.8 g were used.

Evaluation Example 1: Evaluation of contact angle of polymer composite water treatment membrane

In order to evaluate the contact angle of the water treatment separation membranes according to the Examples and Comparative Examples, a flat membrane was manufactured according to ASTM D7490 standard and the contact angle was measured.

Evaluation Example 2: Evaluation of antibacterial properties of polymer composite water treatment membranes

In order to evaluate the antibacterial properties of the water treatment membranes according to the Examples and Comparative Examples, E. coli and S. aureus bacteria were used to evaluate the antibacterial properties of the water treatment membranes according to ASTM F838 standard.

The results for the evaluation examples 1 and 2 are shown in Table 1 below.

division contact angle ( ^o ) S. aureus reduction rate (%) E. coli reduction rate (%) Example 1 70.2 91.7 92.1 Example 2 62.1 99.9 99.9 Example 3 71.3 92.3 93.3 Example 4 77.6 80.5 81.4 Example 5 84.1 61.1 63.1 Comparative Example 1 75.1 87.3 89.2 Comparative Example 2 70.3 96.7 97.4 Comparative Example 3 74.4 85.6 87.5 Comparative Example 4 80.9 77.6 79.1 Comparative Example 5 86.2 55.2 56.3 Comparative Example 6 124.5 17.7 21.5

Evaluation Example 3: Evaluation of Permeate Flow Performance of Polymer Composite Water Treatment Membrane

In order to evaluate the permeate flow performance of the water treatment membranes according to the Examples and Comparative Examples, the permeate flow performance of the water treatment membranes was evaluated by cross-flow filtration at a flow rate of 160 mL/min using a flat membrane of ^{23.7x10 -4} m ^{2 .}

The results for Evaluation Example 3 are shown in Table 2 below.

Water permeability (L/m ² hr) Example 2 19.8 Comparative Example 2 10.2 Comparative Example 6 5

Evaluation Example 4: Performance Evaluation of Polymer Composite Water Treatment Membrane by Long-Term Use

In order to evaluate the long-term performance of the water treatment membranes according to the Examples and Comparative Examples, the performance evaluation was measured by repeating filtration and backwashing of 200 NTU of turbidity on the water treatment membrane for 6 hours for 20 days.

The results for Evaluation Example 4 are shown in Table 3 below.

Measured elapsed time
(day) Example 2 Comparative Example 2 Comparative Example 6 Recovery (%) Recovery (%) Recovery (%) 5 92 85 79 10 90 79 71 15 87 76 60 20 85 70 40

In general, it has been known that oxidation surface-modified carbon nanotubes help to improve the hydrophilicity of the composite, and that even a small amount can be added not only to prevent membrane contamination of the water treatment membrane but also to obtain many effects in water permeability.

However, as can be seen from the results in Tables 1 to 3, it can be seen that even when the same amount of carbon nanotubes is added, the resultant aspect of the contact angle and water treatment characteristics (here, long-term recovery rate, water permeability) is different depending on the processing method. In addition, the composition for producing a polymer composite water treatment membrane of the present invention has improved water treatment characteristics and membrane contamination prevention due to increased dispersing power between highly branched resin and carbon nanomaterials through a mechanical-chemical bonding method using a high-speed rotary pulverizer. This could be confirmed through the comparison between the experimental example and the comparative example.

In the foregoing, specific embodiments of the present invention have been described and illustrated, but it is common knowledge in the art that the present invention is not limited to the described embodiments, and that various modifications and variations can be made without departing from the spirit and scope of the present invention. It is self-evident to those who have Accordingly, such modifications or variations should not be individually understood from the technical spirit or point of view of the present invention, and modified embodiments should be considered to belong to the claims of the present invention.

Claims (4)

Cooling a raw material including a carbon nanotube and a polymer resin including a hydrophilic functional group;
pulverizing the cooled raw material through a pulverizer coupled with a screen mesh to prepare a powder; and
Preparing a carbon nanotube-polymer resin composite including a hydrophilic functional group through a mechanical-chemical bonding device
As a method for producing a composition for forming a water treatment separation membrane comprising:
The carbon nanotubes are included in an amount of 0.1 parts by weight to 1 part by weight based on 100 parts by weight of the composition for forming a water treatment separation membrane,
The polymer resin is contained in 0.9 to 9 parts by weight based on 100 parts by weight of the composition for forming a water treatment separation membrane,
Method for producing a composition for forming a water treatment separation membrane
In claim 1,
The average particle diameter of the powder is 1.0 mm or less, the method for producing a composition for forming a water treatment separation membrane.
delete In claim 1,
The hydrophilic functional group will be selected from a hydroxyl group, a carboxyl group, a carbonyl group, an oxide group, a thiol group, an amine group, or a combination thereof, the method for producing a composition for forming a water treatment separation membrane.

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