KR20120126812A - Titania asymmetric membrane and method for preparation thereof - Google Patents

Abstract

PURPOSE: A titania-based asymmetric membrane and a manufacturing method of the same are provided to include a filtering membrane containing titania particles grown in the shape of needles. CONSTITUTION: A titania-based asymmetric membrane includes a titania-based porous ceramic support, a titania-based primary filtering membrane, and a titania-based secondarily filtering membrane. The titania-based primarily filtering membrane includes titania particles grown in the shape of needles. The titania-based porous ceramic support includes protruded titania and fine titania. The porosity of the titania-based porous ceramic support is in a range between 27 and 42%.

Description

Titania asymmetric membrane and method for preparation thereof

The present invention relates to a titania asymmetric membrane and a method for preparing the same, and more particularly, to a titania asymmetric membrane having excellent chemical resistance, stability, and filtration flow rate.

Due to the recent serious pollution of the water environment and the lack of water, the development of new water resources is emerging as a research project. Water pollution research aims to treat high quality living and industrial water, various kinds of domestic sewage and industrial wastewater, and interest in water treatment processes using membranes has advantages of energy saving.

In general, various methods used for separation are known, but the process using the membrane has a number of characteristics compared to the conventional separation and concentration process. In other words, the membrane separation process selectively separates materials without a phase change, and thus has a simple process and an energy efficiency superior to other separation processes. Existing methods tend to consume more energy than membrane separation processes because they mainly separate phases by inducing phase changes, and the characteristics of the separating materials often change because they require high temperatures for phase change. However, the membrane separation process is applied as a mechanical pressure, so that the separation of the material is applied as a new alternative in the separation, purification and concentration process of specific components, and the application range is gradually widening. Applications include the separation and concentration of raw materials in the food industry, the production of ultrapure water for boiler and semiconductor cleaning processes, the recovery of active substances in wastewater and recycling technologies.

In addition, since the overall system configuration is simpler than other processes, the membrane separation process is simpler when the information on the design factors is secured after the pilot experiment, so that the actual process design and facility expansion are convenient and the volume of the facility itself can be reduced. It has the advantage of being minimally derived. In particular, when the wastewater is treated by using a membrane separation process, the amount of sludge generated can be minimized because there is less chemical use in the treatment process. The treated water obtained in the membrane process can be used as raw water or directly in the manufacturing process depending on the water quality.

However, generally used alumina separators have a problem in that durability deteriorates when used for a long time. This is because the silica component added for low temperature firing and mechanical strength improvement in the preparation of the alumina separator is eluted by the alkaline solution component to lower the mechanical strength of the separator. In order to solve this problem, if the alumina content in the alumina membrane is increased, the chemical resistance is improved, but when the membrane is manufactured, a higher firing temperature is required. Therefore, new equipment is required and the firing cost is expected to increase. It was a situation.

The present invention is to provide a titania asymmetric membrane having improved chemical resistance, excellent stability and filtration flow rate without increasing the firing temperature.

Asymmetric separator according to an aspect of the present invention is a titania porous ceramic support; A titania-like primary filtration membrane containing needle-grown titania particles; And titania secondary filtration membranes.

In the above, the titania-like porous ceramic support may include molten titania, and fine titania.

In addition, the titania porous ceramic support may have a porosity of 27 to 42%.

In addition, the titania primary filtration membrane may have a pore size of 0.1 to 2.3㎛.

In addition, the titania secondary filtration membrane may have a pore size of 0.1 to 0.9㎛.

According to another aspect of the invention, preparing a titania porous ceramic support; Forming a titania-based primary filtration membrane containing titania particles grown on a needle on the support; And forming a titania secondary filtration membrane on the support.

In the above, preparing the titania-like porous ceramic support may include mixing and extruding the raw material including the molten titania and the finely divided titania, and drying and calcining the extruded raw material. .

Here, the drying may be carried out at 50 to 100 ℃.

Here, the firing may be performed at 1300 to 1400 ° C.

The forming of the titania primary filtration membrane may include preparing a coating solution by mixing anatase-like titania and alumina, and injecting the coating solution to coat the support. And drying and firing the coated support.

Here, the concentration of the coating solution may be 15 to 19% by weight, firing may be performed at 1000 to 1100 ℃.

The forming of the titania secondary filtration membrane may include preparing a coating solution by mixing raw materials including anatase and rutile titania, and injecting the coating solution to coat the support. And drying and firing the coated support.

Here, the concentration of the coating solution may be 6 to 10% by weight, firing may be performed at 700 to 900 ℃.

The titania asymmetric separator according to the present invention includes a titania support and a filtration membrane including titania particles grown in the form of needles in the filtration membrane, thereby improving chemical resistance, increasing chemical resistance, and improving stability and filtration compared to the conventional alumina separator. Excellent flow rate

Figure 1 shows the overall cross-sectional structure of the titania asymmetric membrane according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Asymmetric separator according to an aspect of the present invention is a titania porous ceramic support; A titania-like primary filtration membrane containing needle-grown titania particles; And titania secondary filtration membranes. According to another aspect of the invention, preparing a titania porous ceramic support; Forming a titania-based primary filtration membrane containing titania particles grown on a needle on the support; And forming a titania secondary filtration membrane on the support.

Hereinafter, the titania asymmetric membrane and its manufacturing method will be described in more detail with reference to the description of the preparation of the titania asymmetric membrane according to the embodiment of the present invention.

Preparation of the titania asymmetric membrane comprises the steps of preparing a titania porous ceramic support; Forming a titania-based primary filtration membrane containing titania particles grown on a needle on the support; And forming a titania secondary filtration membrane. The prepared titania asymmetric separator includes a porous ceramic support and two layers of filtration membranes. Generally, asymmetric membranes The term "membrane" refers to membranes having different structures on both sides of the membrane in the separation membrane. In this specification, the pore size and crystal structure of the support and the filtration membrane are used to refer to membranes having different structures.

First, a porous ceramic support is prepared by including molten titania as a main raw material and fine titania as a sintering additive. Mixing and extruding the raw material comprising such molten titania and finely divided titania; and drying and firing the extruded raw material. In this case, a binder (MC) may be selectively added as a dry organic material and a wetting agent, a dispersant, a plasticizer, a lubricant, a solvent, or the like as a dry organic material for extrusion molding.

In addition, the drying in the above may be carried out at 50 to 100 ℃, the drying method is not particularly limited, but may be carried out in a hot air dryer, it may be preferable to dry for about 24 hours. In addition, the firing step may be performed at 1300 to 1400 ° C. Preferably, the drying support may be calcined on a firing pedestal of SiC material for about 4 hours.

In addition, the molten titania may preferably have a particle size of 10 to 20 μm, and the finely divided titania may have a particle size of 0.1 to 1.0 μm. In addition, the titania porous ceramic support may have a porosity of 27 to 42%. This is because the strength of the support is excellent within the porosity range and the plastic shrinkage ratio is good.

Conventionally, SiO ₂ was prepared while preparing a support using a main material as alumina. The support was prepared by adding a separate source, but by using the molten and finely divided titania as described above, it is possible to prepare a support having excellent chemical resistance even at a firing temperature of 1300 to 1400 ° C. without improving the existing firing temperature.

Next, a titania-like primary filtration membrane containing titania particles grown needle-like on the support is formed.

The primary filtration membrane is prepared by mixing anatase-like titania, and alumina-containing raw materials to prepare a coating solution, injecting the coating solution to coat the support, and drying and firing the coated support. Steps.

First, a coating solution is prepared by mixing raw materials including anatase titania and alumina, and organic materials such as a dispersant, a binder, and a binder may be selectively added to disperse the coating solution, adjust the viscosity, and prevent dry cracking. Can be. The raw materials are mixed by ball milling the raw materials.

Here, the concentration of the coating liquid is preferably 15 to 19% by weight. This is because when the concentration is 15% by weight or less, no coating film is formed on the surface of the support during coating, so that the coating solution penetrates into the support, and thus the film cannot be manufactured, and from 19% by weight or more, the thickness of the film is too thick.

Next, the coating solution is coated on the inner surface of the support. Although not particularly limited, coating may be performed using dip coating, which is generally used.

After coating, it is dried and calcined. The drying step may be carried out after the natural drying at room temperature, 30 to 75 ℃, the drying method is not particularly limited, but may be carried out in a hot air dryer, it may be preferable to dry for about 24 hours.

Here, the firing step may be performed at 1000 to 1100 ° C, and the drying support may be fired on a firing pedestal of SiC material for about 4 hours.

Under the influence of alumina, titania grows acicularly during grain growth. The needle-grown titania particles act as an interlayer in the filtration membrane to provide a filtration membrane having excellent stability and flow rate.

The titania-based primary filtration membrane prepared as described above includes anatase titania, and alumina, and may have a pore size of about 0.1 μm to about 0.9 μm. This is because an appropriate range of removal rate and flow rate can be exhibited when the pore size is within the above range.

Next, a titania secondary filtration membrane is formed on the support. In general, titania has three crystal structures on rutile, anatase, and brookite, and the crystal structures have the same chemical formula but different crystal structures. Titania has a brookite, anatase phase structure at low temperatures, and a rutile structure at about 700 ° C. or more.

The secondary filtration membrane may be prepared by mixing raw materials including anatase and rutile titania to prepare a coating solution, injecting the coating solution to coat the support, and drying the coated support. And calcining.

First, a coating solution is prepared by mixing raw materials including anatase and rutile titania, and organic materials such as a dispersant, a binder, and a binder are selectively selected to disperse the coating solution, adjust the viscosity, and prevent dry cracking. Can be added. The raw materials are mixed by ball milling the raw materials.

Here, the concentration of the coating liquid is preferably 6 to 10% by weight. This is because when the concentration is 6 wt% or less, there is a problem that the thickness of the film is too thin during coating, and from 10 wt% or more, there is a problem that the thickness of the film becomes too thick.

Next, the coating solution is coated on the inner surface of the support. Although not particularly limited, coating may be performed using dip coating, which is generally used.

After coating, drying and firing are carried out. The drying step may be carried out after the natural drying at room temperature, 30 to 75 ℃, the drying method is not particularly limited, but may be carried out in a hot air dryer, it may be preferable to dry for about 24 hours.

Here, the firing step may be performed at 700 to 900 ° C, and the drying support may be calcined on a firing pedestal of SiC material for about 4 hours.

The titania secondary filtration membrane prepared as described above includes anatase and rutile titania, and may have a pore size of 0.1 to 2.3 μm. This is because an appropriate range of removal rate and flow rate can be exhibited when the pore size is within the above range.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that these examples are for illustrative purpose only and are not to be construed as limiting the scope of the present invention

Example  One

Melt-type titania (# 1000) with a particle size of 15 μm as a main raw material and fine-grained titania (KA100) with 0.3 μm as a sintering material are mixed in a weight ratio of 7: 3, and binder (MC40H) is added, followed by sigma mixer 30 Mix for a minute. Next, water, a wet organic substance (WAX, PEG, PVA) and the like were added to the mixture and mixed for 10 minutes using a sigma mixer to prepare a dough. The kneaded raw material was put into an extrusion molding machine and subjected to one drill. Thereafter, extrusion was carried out to perform extrusion in a multi-channel structure having an outer diameter of 40 mm, 37 holes (4 mm) and 19 holes (6 mm) in the cross section. Next, after drying at 60 degrees for 24 hours in a hot air dryer, the dried support was calcined at 1400 degrees for 4 hours on a pedestal made of SiC material to complete the support.

Then, 97.5% by weight of titania (KA100) on anatase and 2.5% by weight of titania (R8600) on alumina-coated rutile were mixed, followed by the addition of a dispersant (5468CF), a binder (CMC), and ball milling in a ball mill vessel. It was performed for 4 hours at 200 RPM. The prepared coating liquid was coated on the prepared support using a coating machine at an injection rate of 5 to 20 cm / sec, a holding time of 5 to 10 sec, and a varnish rate of 5 to 20 cm / sec. The coated support was naturally dried in a vertical state at room temperature for 12 hours, and then dried in a hot air dryer for 24 hours at 30 to 75 degrees. Next, by firing on a pedestal of SiC material for 4 hours at 1000 to 1100 degrees to complete the primary filter membrane coating.

Next, 95% by weight of titania on anatase (KA100) and 5% by weight of titania on rutile (R8600) were mixed, followed by addition of a dispersant (5468CF), a binder (CMC) and the like. It was carried out for hours. The prepared coating liquid was coated on the prepared support using a coating machine at an injection rate of 5 to 20 cm / sec, a holding time of 5 to 10 sec, and a varnish rate of 5 to 20 cm / sec. After completing the coating, the support was naturally dried at room temperature for 12 hours in a vertical state and then dried with a hot air dryer for 24 hours at 30 to 75 degrees. Next, by firing on a pedestal of SiC material for 4 hours to 700 to 900 degrees to complete the secondary filter membrane coating to prepare a titania asymmetric membrane.

Example  2

Melt-type titania (# 1000) with a particle size of 15 μm as a main raw material and fine-grained titania (KA100) with 0.3 μm as a sintering material are mixed at a weight ratio of 11: 9, and a binder (MC40H) is added, followed by a sigma mixer. Mix for a minute. Next, water, wet organic matter (WAX, PVA, PEG) and the like were added to the mixture and mixed for 10 minutes using a sigma mixer to prepare a dough. The kneaded raw material was put into an extrusion molding machine and subjected to one drill. Thereafter, extrusion was carried out to perform extrusion in a multi-channel structure having an outer diameter of 40 mm, 37 holes (4 mm) and 19 holes (6 mm) in the cross section. Next, after drying at 60 degrees for 24 hours in a hot air dryer, the dried support was calcined at 1400 degrees for 4 hours on a pedestal made of SiC material to complete the support.

Then, 97.5% by weight of titania (KA100) on anatase and 2.5% by weight of alumina (AES11) were mixed, followed by addition of a dispersant (5468CF), a binder (CMC), and ball milling at 200 RPM for 4 hours in a ball mill vessel. It was. The prepared coating liquid was coated on the prepared support using a coating machine at an injection rate of 5 to 20 cm / sec, a holding time of 5 to 10 sec, and a varnish rate of 5 to 20 cm / sec. The coated support was naturally dried in a vertical state at room temperature for 12 hours, and then dried in a hot air dryer for 24 hours at 30 to 75 degrees. Next, by firing on a pedestal of SiC material for 4 hours at 1000 to 1100 degrees to complete the primary filter membrane coating.

Next, 90% by weight of titania (KA100) on anatase and 10% by weight of titania (R8600) on rutile were mixed, followed by addition of a dispersant (5468CF), a binder (CMC), and ball milling at 200 RPM for 4 hours in a ball mill vessel. Was performed. The prepared coating solution was coated on the support at an injection rate of 5 to 20 cm / sec, a holding time of 5 to 10 sec, and a varnish rate of 5 to 20 cm / sec using a coating machine. The coated support was naturally dried in a vertical state at room temperature for 12 hours, and then dried in a hot air dryer for 24 hours at 30 to 75 degrees. Next, by firing on a pedestal of SiC material for 4 hours to 700 to 900 degrees to complete the secondary filter membrane coating to prepare a titania asymmetric membrane.

Comparative example

Except that alumina having a particle size of 20 μm is used as a main raw material and 10 μm clay and talc are used as a raw material in the support manufacturing process, and that titania on rutile coated with alumina is not used in the secondary filter membrane manufacturing process. Asymmetric separator was prepared in the same manner as in 1.

Test Example

After the separation membranes prepared in Examples 1 and 2 and Comparative Example were immersed in 24% NaOH at 100 ° C. for 24hr for 24hr, the change rate of strength before and after loading was measured to be 20.7%, 17.0%, and 90.0%, respectively. As a result, it was found that the chemical resistance of the separator according to the embodiment of the present invention is excellent.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (16)

Titania porous ceramic support;
A titania-like primary filtration membrane containing needle-grown titania particles; And
Titania secondary filtration membranes;
Asymmetric separator comprising a. The asymmetric separator of claim 1, wherein the titania-like porous ceramic support comprises molten titania and finely divided titania. The asymmetric separator of claim 1, wherein the titania-based porous ceramic support has a porosity of 27 to 42%. The asymmetric membrane of claim 1, wherein the titania primary filtration membrane has a pore size of 0.1 to 2.3 μm. The asymmetric separation membrane of claim 1, wherein the titania secondary filtration membrane has a pore size of 0.1 to 0.9 μm. Preparing a titania porous ceramic support;
Forming a titania-based primary filtration membrane containing titania particles grown on a needle on the support; And
A method for producing an asymmetric separator comprising the step of forming a titania secondary filtration membrane on the support. The method of claim 6, wherein the preparing of the titania-based porous ceramic support comprises mixing and extruding a raw material including molten titania and finely divided titania, and drying and firing the extruded raw material. Method for producing an asymmetric separation membrane comprising. The method of claim 7, wherein the drying is performed at 50 to 100 ° C. 9. The method of claim 7, wherein the firing is performed at 1300 to 1400 ° C. 9. The method of claim 6, wherein forming the titania primary filtration membrane,
Asymmetric separation membrane comprising the steps of preparing a coating solution by mixing anatase (titania) and raw materials comprising alumina, injecting the coating solution to coat the support, and drying and firing the coated support Manufacturing method. The method of claim 10, wherein the concentration of the coating solution is 15 to 19% by weight. The method of claim 10, wherein the firing is performed at 1000 to 1100 ° C. 12. The method of claim 6, wherein the forming of the titania secondary filtration membrane comprises: preparing a coating solution by mixing raw materials including anatase and rutile titania, and injecting the coating solution into the support Coating method, and drying and baking the coated support. The method of claim 13, wherein the concentration of the coating solution is 6 to 10% by weight. The method of claim 13, wherein the firing is performed at 700 to 900 ° C. Asymmetric separation membrane prepared according to any one of claims 6 to 15.

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