Sodium alginate-coated ceramic hollow fiber membrane and manufacturing method thereof

Abstract

The present invention relates to a sodium alginate-coated ceramic hollow fiber membrane and a manufacturing method thereof. More specifically, the present invention provides a coated ceramic hollow fiber membrane and a manufacturing method thereof, the coated ceramic hollow fiber membrane comprising: a hollow tubular ceramic support having pores; and a coating layer disposed on the outer circumferential surface of the ceramic support, wherein the coating layer is a sodium alginate coating layer obtained by coating with sodium alginate. According to the present invention, a sodium alginate-coated ceramic hollow fiber membrane for water treatment has a lower filtration reduction rate due to having a sodium alginate coating layer, and thus is not only able to retain filtration performance, but also has superior ion removal performance, for example, fluoride removal performance, compared to an uncoated ceramic hollow fiber membrane, and has an economical coating layer due to having a low coating unit cost. Therefore, the present invention has the advantage of providing a sodium alginate-coated ceramic hollow fiber membrane for water treatment in which the filtration performance is improved.

Description

Ceramic hollow fiber membrane coated with sodium alginate and method for manufacturing the same

[0001] The present invention relates to a ceramic hollow fiber membrane and a method for manufacturing the same, specifically, a coated ceramic hollow fiber membrane for water treatment and a method for manufacturing the same.

[0002] With the advancement of industry, the harmful effects of hazardous substances generated in various industrial processes, such as dust, soot, exhaust gases, smoke, and volatile organic compounds (VOCs), are on the rise. Consequently, while polymer filters are used in some areas to prevent the release of these pollutants, they have drawbacks regarding heat resistance, chemical resistance, wear resistance, and flame retardancy.

[0003] Therefore, ceramic filters have been developed to solve these problems. Ceramic filters have characteristics such as heat resistance, chemical resistance, and wear resistance that are much superior to those of polymer filters. In particular, they have excellent heat resistance, so there is no need to install a separate cooling device in the exhaust system, which has the advantage of reducing installation and maintenance costs.

[0004]

[0005] Membrane filtration processes using nanofiltration membranes (NF) are gaining attention as advanced water treatment processes because they have the advantage of being able to maintain a relatively high membrane flux compared to reverse osmosis (RO) filtration processes and remove even low molecular weight organic matter.

[0006] Filtration membrane materials primarily used in nanofiltration (NF) processes are composed of polymers that are relatively inexpensive and easy to manufacture, but they have the disadvantage of being vulnerable to high temperatures and organic solvents. To overcome this, active research and technological development are currently underway, primarily in Japan, on ceramic nanofiltration membranes made of inorganic materials that offer excellent heat resistance, chemical resistance, and pressure resistance, as well as semi-permanent usability, utilizing various materials such as Al2O3, TiO2, and ZrO2. However, ceramic membranes are currently limited to the level of microfiltration and ultrafiltration, and ceramic nanofiltration technology has not advanced significantly. In particular, domestic ceramic nanofiltration technology is virtually non-existent.

[0007]

[0008] Meanwhile, ceramic hollow fiber membranes offer excellent and cost-effective performance for fluid filtration applications. As they are inherently chemically inert, ceramics are superior materials for process applications where conventional polymer membranes are unsuitable due to high pressure, high temperature, or extreme pH. Ceramic hollow fiber membranes prevent bacteria and other impurities from adhering to the membrane surface, thereby extending the lifespan of filtration systems and lowering the total cost of ownership. Ceramic hollow fiber membranes are widely used in industries such as biotechnology, chemical processing, water and wastewater treatment, pharmaceuticals, and food and beverage processing.

[0009] However, in order to further improve filtration and removal performance and provide ceramic hollow fiber membranes usable in advanced water purification processes, research is needed not only on the materials, size, and structure of the ceramic hollow fiber membranes but also on the coating layer appropriately applied to them.

[0010]

[0011] The prior art in the technical field described above is as follows.

[0012] Korean Patent Registration No. 10-2641726 (Registration Date: February 23, 2024) relates to a ceramic hollow fiber membrane for water treatment, a water treatment module, and a method for manufacturing a ceramic hollow fiber membrane for water treatment. Specifically, it relates to a ceramic hollow fiber membrane for water treatment comprising: a hollow tubular ceramic support having pores formed therein; and a coating layer disposed on the outer surface of the ceramic support containing activated carbon particles.

[0013] The above patent only uses activated carbon particles as a coating layer and does not teach or imply a sodium alginate coating layer having excellent filtration and removal performance while having a low coating cost, as in the present invention.

[0014]

[0015] In addition, Korean Patent Registration No. 10-2427811 (Registration Date: July 27, 2022) relates to a surface-modified ceramic hollow fiber membrane, a membrane contactor including the same, and a method for manufacturing the same. Specifically, it relates to a surface-modified ceramic hollow fiber membrane comprising a hydrophilic inorganic material; and a hydrophobic surface modification layer formed on the surface of the hydrophilic ceramic hollow fiber membrane and comprising a hydrophobic material, a membrane contactor including the same, and a method for manufacturing the same.

[0016] The aforementioned patent includes only a hydrophobic surface modification layer as a coating layer and does not teach or imply a sodium alginate coating layer having excellent filtration and removal performance while having a low coating cost, as in the present invention; furthermore, the aforementioned patent discloses only the treatment of high-temperature exhaust gas and does not teach or imply a ceramic hollow fiber membrane usable in the advanced water purification process of the present invention.

[0017] The present invention aims to provide a coated ceramic hollow fiber membrane and a method for manufacturing the same, which can be used in advanced water purification processes by maintaining improved filtration performance compared to uncoated ceramic hollow fiber membranes for water treatment and having excellent removal performance.

[0018] In addition, the present invention is intended to provide a water treatment module having a coated ceramic hollow fiber membrane of the present invention.

[0019] Furthermore, the present invention aims to provide a ceramic hollow fiber membrane coated with sodium alginate and a method for manufacturing the same, in conjunction with the following national research and development project.

[0020] [National R&D projects that supported this invention]

[0021] [Project ID] 2710018395

[0022] [Assignment No.] 00445094

[0023] [Ministry Name] Ministry of Science and ICT

[0024] [Name of Project Management (Specialized) Agency] National Research Foundation of Korea

[0025] [Research Project Name] Original Technology Development Project (Integrated) - Nano & Materials Technology Development Project - Nano Future Materials Original Technology Development Project

[0026] [Research Project Title] Development of Manufacturing Technology for Environmental Nanomaterial-Based Ceramic Membranes for Public Safety and Resource Recovery from Wastewater from New Industries

[0027] [Name of Project Performing Organization] Ewha Womans University

[0028] [Research Period] 2024.01.01 ~ 2028.12.31

[0029]

[0030] Meanwhile, the technical problems to be solved by the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0031] To achieve the above objective, one aspect of the present invention provides a coated ceramic hollow fiber membrane comprising: a hollow tubular ceramic support having pores formed therein; and a coating layer disposed on the outer surface of the ceramic support, wherein the coating layer is a sodium alginate coating layer coated with sodium alginate, which is a surface-modified nanomaterial.

[0032] A preferred embodiment of one aspect of the present invention is characterized in that the ceramic support comprises at least one of alumina (Al2O3), titania (TiO2), zirconia (ZrO2), and silicon carbide (SiC).

[0033] A preferred embodiment of one aspect of the present invention is characterized by the pore size of the ceramic support being 0.01 μm to 2 μm.

[0034] A preferred embodiment of one aspect of the present invention is characterized in that the sodium alginate has a size of 300 nm to 600 nm and the thickness of the coating layer is 50 μm to 200 μm.

[0035]

[0036] Another aspect of the present invention provides a water treatment module comprising: a hollow fiber membrane module comprising at least one ceramic hollow fiber membrane of the present invention; a housing in which a long-term hollow fiber membrane module is disposed therein; and an inlet and an outlet formed spaced apart from each other in the housing.

[0037]

[0038] Another aspect of the present invention provides a method for manufacturing a ceramic hollow fiber membrane for water treatment, comprising the steps of: providing a hollow tubular ceramic support having pores formed therein (Step 1); and forming a coating layer on the outer surface of the ceramic support (Step 2), wherein Step 2 comprises dissolving sodium alginate, which is a surface-modified nanomaterial, in a solvent to prepare a sodium alginate solution, coating the outer surface of the ceramic support with the sodium alginate solution, and drying the same.

[0039] A preferred embodiment of another aspect of the present invention is characterized in that the concentration of the sodium alginate solution in step 2 is 1200 mg / L to 2500 mg / L.

[0040] A preferred embodiment of another aspect of the present invention is characterized in that, in step 2, the coating is performed by at least one of dip coating, spray coating, and pressure filtration coating.

[0041] A preferred embodiment of another aspect of the present invention is characterized in that the thickness of the coating layer dried in step 2 is 50 μm to 200 μm.

[0042] According to the present invention, a ceramic hollow fiber membrane for water treatment coated with sodium alginate, a surface-modified nanomaterial, has the advantage of being able to maintain filtration performance by forming a sodium alginate coating layer, thereby lowering the reduction rate of filtration volume, and also having superior ion removal performance, such as fluoride removal performance, compared to an uncoated ceramic hollow fiber membrane, and having an economical coating layer with a low coating cost, thereby providing a ceramic hollow fiber membrane for water treatment coated with sodium alginate that has excellent filtration performance.

[0043]

[0044] However, the effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below.

[0045] Figure 1 is a schematic diagram showing the hollow fiber membrane coating and filtration experiment of Example 1 of the present invention.

[0046] FIG. 2 is a drawing showing a photograph and specifications of a hollow fiber membrane used in Example 1 of the present invention and a filtration system including the same.

[0047] Figure 3 is a photograph and graph showing the coating solution and coating volume of Example 1 of the present invention.

[0048] Figure 4 is a photograph showing whether the hollow fiber membrane of Example 1 of the present invention is coated.

[0049] Figure 5 is a graph showing the reduction rate of filtration of ultrapure water before and after coating in Experimental Example 1 of the present invention.

[0050] Figure 6 is a graph showing the reduction rate of high-concentration fluoride wastewater filtration amount before and after coating in Experimental Example 1 of the present invention.

[0051] Figure 7 is a graph showing the high-concentration fluoride wastewater removal performance before and after coating of Experimental Example 1 of the present invention.

[0052] Figure 8 is a graph comparing the standard unit price of the mass of the coating material and the volume of the solution coated on the hollow fiber membrane of the present invention.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a skilled expert in the art to which this invention pertains. In general, the nomenclature used herein is well known and commonly used in the art.

[0054] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0055]

[0056] The present invention will be described in detail below.

[0057] One aspect of the present invention provides a ceramic hollow fiber membrane coated with sodium alginate, a surface-modified nanomaterial.

[0058] Specifically, the ceramic hollow fiber membrane of the present invention

[0059] A hollow tubular ceramic support with formed pores; and

[0060] It includes a coating layer disposed on the outer surface of the ceramic support, and

[0061] The above coating layer is characterized as being a sodium alginate coating layer coated with sodium alginate, which is a surface-modified nanomaterial.

[0062]

[0063] The first component of the ceramic hollow fiber membrane of the present invention comprises a ceramic support that is a hollow tubular ceramic support having pores formed therein.

[0064] The ceramic support forms the overall appearance of the ceramic hollow fiber membrane according to one embodiment of the present invention. The ceramic support can impart rigidity to the ceramic hollow fiber membrane of the present invention.

[0065] The ceramic support is formed in the shape of a hollow tube. That is, the ceramic support may be in the shape of a cylinder with a hollow formed inside. The hollow may be formed in a shape that extends from one end to the other end facing each other in one direction of the ceramic support. Water to be treated may be introduced into the ceramic support through at least one of the one end and the other end of the hollow.

[0066] The ceramic support comprises at least one of alumina (Al2O3), titania (TiO2), zirconia (ZrO2), and silicon carbide (SiC). For example, the ceramic support may be composed of at least one of alumina (Al2O3), titania (TiO2), zirconia (ZrO2), and silicon carbide (SiC), but the scope of the present invention is not limited thereto.

[0067] The pore size may be between 0.01 μm and 2 μm, which is the level of microfiltration (MF) or ultrafiltration (UF). If the pore size is less than 0.01 μm, the pressure for water treatment of the target water increases significantly, and the water treatment speed may decrease. If the pore size exceeds 2 μm, the rigidity of the ceramic support may decrease. Meanwhile, in the present invention, the pore size may refer to the diameter of the pore. The pore diameter may, for example, mean selecting one of the pores shown in a scanning electron microscope (SEM) image of a cross-section of the ceramic support, measuring the diameter of the pore at least three times at mutually spaced points, and then calculating and averaging these values. Alternatively, it may mean determining the pore size for each of the at least three pores shown in the image using the method described above and averaging the values ​​based on the number of measured pores.

[0068]

[0069] In addition, the second component of the ceramic hollow fiber membrane of the present invention includes a coating layer.

[0070] The coating layer is a layer coated with sodium alginate, a surface-modified nanomaterial.

[0071] Here, surface-modified nanomaterials can play a role in increasing the specific surface area by modifying the surface through coating and further improving filtration and removal performance.

[0072] In particular, sodium alginate has the chemical formula (C6H7O6Na) nIt is a white to pale yellow fibrous, granular, granular, or powdered substance that is almost odorless and tasteless. It does not dissolve in alcohol or organic solvents such as chloroform, but dissolves slowly in sodium carbonate, sodium hydroxide, and sodium phosphate. When dissolved in water, it becomes viscous and is highly effective as a stabilizer and thickener. The pH of a 1% aqueous solution is 6 to 8. The viscosity may decrease if the aqueous solution is kept at high temperatures for a long time, but there is no change in viscosity below 80°C. Therefore, when preparing an aqueous solution, it is preferable to mix it with alcohol or propylene glycol and then add water to dissolve it.

[0073] As described above, this sodium alginate is a surface-modified nanomaterial, and in order to perform the role described above, its size is preferably 300 nm to 600 nm, preferably 400 nm to 500 nm.

[0074] In addition, the sodium alginate coating layer is a coating layer containing positive and negative ions, which acts as a negative / positive ion exchanger and can further improve filtration and removal performance by filtering unnecessary substances from contaminated water according to its ionic characteristics.

[0075] The sodium alginate coating layer of the present invention is disposed on the outer surface of the ceramic support. For example, the coating layer may cover a portion of the outer surface of the ceramic support, and as another example, the coating layer may cover the entire outer surface of the ceramic support. In the present invention, the outer surface of the ceramic support may refer to the surface of the cylinder, i.e., the side surface of the cylinder, excluding the two bottom surfaces of the cylinder and the inner surface defining the hollow, for example, when the ceramic support has a cylindrical shape overall.

[0076] In the present invention, the thickness of the coating layer is preferably 50 μm to 200 μm.

[0077] By coating the ceramic hollow fiber membrane with this coating layer, the rate of reduction in filtration volume is lowered, allowing the filtration performance to be maintained. Furthermore, compared to an uncoated ceramic hollow fiber membrane, it exhibits superior ion removal performance, such as fluoride removal performance (see FIGS. 5 to 7). In addition, it has the advantage of forming an economical coating layer as the unit cost of coating is very low compared to other coating materials (see FIG. 8).

[0078]

[0079] In addition, another aspect of the present invention provides a water treatment module comprising at least one ceramic hollow fiber membrane of the present invention.

[0080] Specifically, the water treatment module of the present invention is,

[0081] A hollow fiber membrane module comprising at least one ceramic hollow fiber membrane of the present invention;

[0082] A housing in which an internal long-term hollow fiber membrane module is placed; and

[0083] The above housing includes an inlet and an outlet formed spaced apart from each other,

[0084] A porting section may be additionally included.

[0085]

[0086] The housing can form the overall exterior of the water treatment module according to the present invention. The housing may include a main body and a cap portion. A hollow fiber membrane module is disposed inside the main body of the housing. To accommodate the hollow fiber membrane module inside the main body of the housing, the main body of the housing may be formed in a shape corresponding to the shape of the hollow fiber membrane module. The housing cap portion can seal the hollow fiber membrane module disposed within the main body together with the main body. The housing cap portion may be disposed at least one of one end and the other end of the hollow fiber membrane module and may be coupled to at least one of one end and the other end of the main body.

[0087] The inlet and the outlet are formed spaced apart from each other. The inlet introduces the water to be treated into the water treatment module of the present invention, and the outlet discharges the treated purified water from the water treatment module of the present invention to the outside. Meanwhile, each of the inlet and the outlet may be formed at least once as needed, and their functions are interchangeable regardless of their names. Additionally, the inlet and the outlet may be arranged in a form formed together on the housing body, or in a form where one is formed on the housing body and the other is formed on the housing cap.

[0088] The potting portion can be positioned at least one end and the other end of the hollow fiber membrane module to support the hollow fiber membrane module.

[0089] Meanwhile, although not specifically described above, the present invention also includes, as an example, a water treatment device and a water treatment system utilizing the aforementioned ceramic hollow fiber membrane for water treatment and a water treatment module. For example, it may include a fluid connection pipe connected to each of the inlet and outlet of the water treatment module. As a non-limiting example, the fluid connection pipe may include one or more of a supply line for water to be treated, an air injection line, a purified water discharge line, and a concentrated water discharge line.

[0090]

[0091] In addition, another aspect of the present invention provides a method for manufacturing a sodium alginate-coated ceramic hollow fiber membrane.

[0092] Specifically, the above method

[0093] A step of providing a hollow tubular ceramic support with formed pores (Step 1); and

[0094] It includes the step (step 2) of forming a coating layer on the outer surface of the ceramic support.

[0095]

[0096] First, Step 1 provides a hollow tubular ceramic support with formed pores.

[0097] The hollow tubular ceramic support having the above-mentioned pores may use a conventional hollow tubular ceramic support known in the art, and the present invention does not make any specific limitations thereon. Furthermore, the hollow tubular ceramic support of the present invention may be manufactured as follows as an example.

[0098] Step 1 above comprises forming a spinning solution containing ceramic particles and a polymer resin, degassing the spinning solution under reduced pressure, spinning the degassing spinning solution to form a hollow tubular ceramic support green body with pores, and sintering the ceramic support green body.

[0099] Specifically, a spinning solution comprising ceramic particles and a polymer resin is formed. The spinning solution may further include organic solvents such as 1-methyl-2-pyrrolidone, triethyl phosphate, dimethylformamide, dimethylacetamide, dimethylformaldehyde, dimethyl sulfoxide, trimethyl phosphate, and dispersants such as polyvinylpyrrolidone.

[0100] Ceramic particles may include alumina (Al2O3), titania (TiO2), zirconia (ZrO2), and silicon carbide (SiC). The ceramic particles may have a size of 0.1 μm or more and 10 μm or less.

[0101] The polymer resin may include at least one of polyethersulfone, polysulfone, polyetherimide, polyamide, polyethylene, polypropylene, polyacrylate, polyacrylonitrile, polysulfide, polyketone, polyetherketone, and polyetheretherketone.

[0102] In addition, the concentration of the solution and other process conditions can be easily selected by those skilled in the art, and the present invention does not specifically limit them.

[0103]

[0104] Subsequently, Step 2 forms a coating layer on the outer surface of the ceramic support.

[0105] Specifically, step 2 above includes preparing a sodium alginate solution by dissolving sodium alginate in a solvent, coating the sodium alginate solution onto the outer surface of the ceramic support, and drying it.

[0106] In step 2 above, the concentration of the sodium alginate solution is preferably 1200 mg / L to 2500 mg / L.

[0107] It is preferable that the solvent used to prepare the above sodium alginate solution be ultrapure water.

[0108] The coating method may utilize various coating methods known in the field, and preferably, at least one method among dip coating, spray coating, and pressure filtration coating may be utilized.

[0109] As an example, when using dip coating, one end of the ceramic support can be blocked, and the ceramic support can be vertically dipped into the coating solution using a dip-coater.

[0110] Afterward, the coating solution coated on the outer surface of the ceramic support is dried. Drying can be performed at a temperature of 80°C to 300°C for 1 to 24 hours. If the temperature is below the above, the coating layer may be insufficiently formed on the outer surface of the ceramic support due to insufficient drying of the coating layer, whereas if the temperature exceeds the above, a problem may occur in which the coating layer peels off from the ceramic support.

[0111]

[0112] Additionally, a washing process may be additionally performed after the above step 2.

[0113] Specifically, when the coating step is completed, solvent and free impurities may be present in the coated coating solution, causing the coating layer to be in an unstable state. Accordingly, a hydrothermal treatment step may be performed to remove the solvent and impurities while simultaneously stabilizing the coating layer. The cleaning process may, for example, be performed using water at room temperature for 1 to 12 hours, or for 3 to 8 hours, but is not limited thereto.

[0114]

[0115] The details of the process of the present invention will be explained below through examples and experimental examples. These are representative examples related to the present invention, and it should be noted that the scope of application of the present invention cannot be limited solely by these examples.

[0116]

[0117] <Example 1> Preparation of a hollow fiber membrane coated with sodium alginate

[0118]

[0119] Figure 1 is a schematic diagram illustrating the hollow fiber membrane coating and filtration experiments of Example 1 and Experimental Example 1 to aid understanding.

[0120]

[0121] First, the applicant utilized a hollow fiber membrane and a filtration system from Dongkook R&S. Refer to Fig. 2 for the hollow fiber membrane. Specifically, the hollow fiber membrane used in Example 1 has an outer diameter of 2.8 mm and an inner diameter of 2.2 mm, a length of 100 mm, and is manufactured from alumina (Al2O3). Its initial pure water permeability is 392.9 ± 153.9 Lm -2 h -1 ba r-1 It was.

[0122]

[0123] Meanwhile, sodium alginate (Sigma-Aldrich; MW=200,000 Da (=3.84 nm)) (ALG) was provided as a coating nanomaterial, and for comparison, carbon quantum dots (SAT NANO, MW=12.011 Da) (CQD), chitosan (Sigma-Aldrich; MW=1,250,000 Da (=12 nm)) (CS), carbon nanotubes (Sigma-Aldrich; MW=12.01 Da) (CNT), and fullerene C60 (SAT NANO; MW=720.64 Da) (C60) were used.

[0124] The above-mentioned coating nanomaterial was mixed, ultrasonically treated, and centrifuged using ultrapure water as a solvent to prepare a coating solution with the concentration and coating volume as shown in Fig. 3.

[0125] This was coated on the outer surface of the hollow fiber membrane with a coating amount of 1 mg / ㎠ using a dipping technique and dried.

[0126] The formed coated hollow fiber membrane is as shown in Fig. 4.

[0127]

[0128] <Experimental Example 1> Characterization of Sodium Alginate-Coated Hollow Fiber Membranes

[0129] (1) Measurement of the reduction rate of filtration in ultrapure water (DI) before and after coating

[0130] A filtration system comprising the coated hollow fiber membrane of Example 1 was used. Permeability was measured before and after coating according to the following filtration conditions, and the reduction rate of ultrapure water filtration before and after coating was calculated as shown on the left side of Fig. 5. Here, the filtration conditions were ultrapure water, 3 bar, and 30 minutes of filtration.

[0131]

[0132] The results are provided in Fig. 5.

[0133] As can be seen from the right side of Fig. 5, the filtration reduction rate was about 45 to 50% for the sodium alginate coating of the present invention, more than 50% for CS, and between 10 and 20% for CNT and C60.

[0134]

[0135] (2) Measurement of reduction rate in high-concentration fluoride wastewater filtration volume before and after coating

[0136] A filtration system comprising the coated hollow fiber membrane of Example 1 was used. The reduction rate of high-concentration fluoride wastewater filtration volume was measured before and after coating according to the following filtration conditions, and the reduction rate of high-concentration fluoride filtration volume was calculated as shown on the left side of Fig. 6. Here, the filtration conditions were NaF 1000 ppm, 5 bar, and 200 mL filtration.

[0137] The results are provided in Table 1 and Figure 6 below.

[0138] Coating material Normalized permeability Before coating 0.82 CQD 0.68 CS 0.38 ALG (present invention) 0.85 CNT 0.80 C 60 0.45

[0139] As can be seen from Table 1 and the right-hand diagram of Figure 6 above, the sodium alginate coating of the present invention exhibits the highest permeability of 0.85, indicating that the reduction rate of high-concentration fluoride wastewater filtration is the lowest and the fluoride wastewater filtration amount is best maintained. On the other hand, the comparative examples of CQD, CS, CNT, and C60 coatings exhibit permeability of 0.68, 0.38, 0.80, and 0.45, respectively; in particular, CS and C60 show very high reduction rates of filtration amount, while CQD and CNT show higher reduction rates of filtration amount than the sodium alginate coating of the present invention.

[0140]

[0141] (3) Measurement of high-concentration fluoride wastewater removal performance before and after coating

[0142] A filtration system comprising the coated hollow fiber membrane of Example 1 was used. The removal performance of high-concentration fluoride wastewater was measured before and after coating according to the following filtration conditions. Here, the filtration conditions were NaF 1000 ppm, 5 bar, and 200 mL filtration.

[0143]

[0144] The results are provided in Fig. 7.

[0145] As can be seen from the figure of Fig. 7, in the case of the sodium alginate coating of the present invention, the residual rate of high-concentration fluoride wastewater (left figure) increased by 3 to 4 times compared to before coating (Pristine), and it can be seen that the increase in the residual rate is also excellent along with CQD and C60. Through these results, it has been proven that the sodium alginate coating of the present invention has excellent performance in removing high-concentration fluoride wastewater.

[0146] The ceramic hollow fiber membrane coated with sodium alginate and the method for manufacturing the same according to the present invention have the advantage of being able to provide a ceramic hollow fiber membrane for water treatment coated with sodium alginate, a surface-modified nanomaterial, which can maintain filtration performance by forming a sodium alginate coating layer, thereby lowering the reduction rate of filtration volume, and also having superior ion removal performance, such as fluoride removal performance, compared to an uncoated ceramic hollow fiber membrane, and having an economical coating layer with a low coating cost, thus having industrial applicability.

Claims

1. A hollow tubular ceramic support with formed pores; and It includes a coating layer disposed on the outer surface of the ceramic support, and A coated ceramic hollow fiber membrane characterized in that the above coating layer is a sodium alginate coating layer coated with sodium alginate, a surface-modified nanomaterial.

2. A coated ceramic hollow fiber membrane according to claim 1, characterized in that the ceramic support comprises at least one of alumina (Al2O3), titania (TiO2), zirconia (ZrO2), and silicon carbide (SiC).

3. A coated ceramic hollow fiber membrane according to claim 1, characterized in that the pore size of the ceramic support is 0.01 μm to 2 μm.

4. A coated ceramic hollow fiber membrane according to claim 1, characterized in that the sodium alginate has a size of 300 nm to 600 nm and the thickness of the coating layer is 50 μm to 200 μm.

5. A hollow fiber membrane module comprising at least one ceramic hollow fiber membrane of claim 1; A housing in which an internal long-term hollow fiber membrane module is placed; and A water treatment module comprising an inlet and an outlet formed spaced apart from each other in the above housing.

6. A step of providing a hollow tubular ceramic support having pores formed therein (Step 1); and The method includes the step (step 2) of forming a coating layer on the outer surface of the ceramic support, and The above step 2 is A sodium alginate solution is prepared by dissolving sodium alginate, a surface-modified nanomaterial, in a solvent, and The above sodium alginate solution is coated on the outer surface of the ceramic support, and including drying this A method for manufacturing a ceramic hollow fiber membrane for water treatment, characterized by 7. A method according to claim 6, characterized in that the concentration of the sodium alginate solution in step 2 is 1200 mg / L to 2500 mg / L.

8. A method according to claim 6, characterized in that the coating in step 2 is performed by at least one of dip coating, spray coating, and pressure filtration coating.

9. A method according to claim 6, characterized in that the thickness of the coating layer dried in step 2 is 50 μm to 200 μm.

Images