KR100531118B1 - The Submerged Membrane System and preparation thereof - Google Patents

Abstract

The present invention relates to an immersion type membrane and a method for manufacturing the same, and more particularly, to form a tubular support made of a polymer fiber woven with a yarn of a specific thickness, and to form a hydrophilic polymer and silica containing an amine group on the surface of the support. And after coating a hydrophobic polymer solution including a predetermined amount of an organic / inorganic hybrid compound coordinating an inorganic material selected from titania, and coating the organic / inorganic hybrid compound again to improve mechanical properties and improve the permeability and the membrane. The present invention relates to an immersion type membrane having improved stain resistance and a method of manufacturing the same.

Description

Immersion type separation membrane and preparation method thereof The Submerged Membrane System and preparation

The present invention relates to an immersion type membrane and a method for manufacturing the same, and more particularly, to form a tubular support made of a polymer fiber woven with a yarn of a specific thickness, and to form a hydrophilic polymer and silica containing an amine group on the surface of the support. And after coating a hydrophobic polymer solution including a predetermined amount of an organic / inorganic hybrid compound coordinating an inorganic material selected from titania, and coating the organic / inorganic hybrid compound again to improve mechanical properties and improve the permeability and the membrane. The present invention relates to an immersion type membrane having improved stain resistance and a method of manufacturing the same.

Various kinds of separators are used in many fields until now, and various kinds of polymer hollow fiber membranes have been developed and manufactured as separators used for water treatment. The polymers generally used for these hollow fiber membranes include polysulfone, polyimides, polyacrylonitrile, and polyvinylidene fluoride, and a wide variety of polymers are used. In addition, in order to improve the permeability and selectivity of the hollow fiber membranes, the structure of the separator was controlled by a phase transition process in which various additives were added to the polymer.

The most common way to control the structure of the membrane is to control the rate of exchange between solvent and non-solvent of polymer and thermodynamic stability of the dope solution when the polymer solution is phase-changed into polymer membrane. Phosphorus polyethyleneglycol etc. are added and used. The various hollow fiber membranes thus prepared have no difficulty in having desired permeability and selectivity in the field, and they are already commercially available because they are manufactured with very excellent ultrafiltration membranes and microfiltration membranes.

However, the biggest problem of these membranes in which permeability and selectivity have been solved is contamination of the membrane. In other words, when the manufactured hollow fiber membrane is made into a module and applied to wastewater treatment, the contaminants in the wastewater contaminate the surface of these membranes at a very high speed, which brings limitations in the field of application of the membrane. In order to solve the contamination problem of the separator, an immersion type membrane system has been developed, which has been recognized as a very good low pollution membrane system.

On the other hand, there are some problems in applying the existing hollow fiber membrane to the immersion type membrane system, a representative one of them is mechanical strength, to be precise, flexural strength. In the submerged membrane, the membrane is shaken without pause by using air bubbles to prevent contamination of the membrane. In this process, the existing hollow fiber membranes are easily broken. In order to solve this strength problem, a fiber-shaped tube support was put inside the hollow fiber to compensate for the mechanical strength problem. However, the hollow fiber membrane including the support thus far is somewhat insufficient to solve all problems such as permeability, selectivity and mechanical strength.

The present inventors have made efforts to solve the mechanical strength and permeability problems of the membrane at the same time, as a result of forming a tubular support with a polymer fiber woven with a certain thickness of the yarn improves the mechanical strength of the membrane, and also the amine group When the organic / inorganic hybrid compound formed by the coordination bond of the hydrophilic polymer and the inorganic material selected from silica or titania is mixed and coated with a hydrophobic polymer in a predetermined content range, and then coated with an organic / inorganic hybrid compound, The present invention has been completed by knowing that the hydrophilicity can be improved.

Accordingly, the present invention is to provide an immersion type membrane and a method for producing the same, which has a high mechanical strength by providing a hydrophilicity by coating a certain amount of organic / inorganic hybrid compound with a hydrophobic polymer on a tubular support, and having excellent mechanical strength and its resistance to fouling. There is this.

The present invention is a hydrophobic polymer formed by coating a hydrophobic polymer solution comprising 2 to 6 wt% of a hydrophilic polymer including an amine group and an organic / inorganic hybrid compound in which an inorganic material selected from silica and titania is coordinated on the surface of a tubular polymer support. A coating layer and an immersion type separator in which the coating layer of the organic / inorganic hybrid compound is laminated on the polymer coating layer are characterized in that the layer.

The present invention also provides a hydrophobic polymer solution comprising 2 to 6 wt% of a hydrophilic polymer containing an amine group and an organic / inorganic hybrid compound in which an inorganic material selected from silica and titania is coordinated on the surface of a tubular polymer support. In, after the coating treatment for 5 seconds to 1 minute, there is another feature in the method for producing an immersion type membrane by coating the organic / inorganic hybrid compound on the polymer coating layer for 5 seconds to 1 minute at room temperature.

Referring to the present invention in more detail as follows.

The present invention is prepared by immersion coating on a surface of a tubular support using a hydrophobic polymer solution such as polyvinylidene fluoride including an organic / inorganic hybrid compound as a coating solution, and then immersed and coated again with an organic / inorganic hybrid compound solution. The present invention relates to an immersion type membrane for improving membrane fouling resistance and mechanical strength, and a method for manufacturing the same. An organic / inorganic hybrid compound formed by coordination of a hydrophilic polymer and an inorganic compound on a tubular support formed of polymer fibers is mixed with an existing hydrophobic polymer material. After coating with a solution, it is again coated with an organic / inorganic hybrid compound to prepare an immersion type membrane.

Hereinafter, the method of manufacturing the immersion type separation membrane according to the present invention will be described in detail.

First, a tubular support made of polymer fibers is prepared. The polymer fiber used for preparing the support is selected from polypropylene, polyester, and nylon 6,6, and a yarn having a thickness of 200 to 500 deniers is produced in a tube shape by braiding method. The prepared tubular support forms an inner diameter of 0.5 to 3.0 mm and an outer diameter of about 1.0 to 4.0 mm.

The surface of the tubular support thus formed is generally coated with a polymer material to prepare a separator in a form in which the polymer layer is covered. The polymer material layer has a sponge structure formed by round pores and a lower portion formed by finger-shaped pores lengthened in the thickness direction of the polymer layer, and forms a surface of very small pores that the polymer solution cannot easily pass through at a size of 0.01 to 0.5 μm. do.

In the present invention, in forming the polymer material layer, an organic / inorganic hybrid material is contained in a hydrophobic polymer selected from polyvinylidene fluoride, polysulfone, polyethersulfone, polyacrylonitrile and polyimide which are conventional polymers. 6 wt% of the mixed polymer solution is coated, and then the upper part of the polymer layer is coated with the organic / inorganic hybrid compound solution to give hydrophilicity. When the amount of the organic / inorganic hybrid material included in the hydrophobic polymer solution is less than 2% by weight, the hydrophilic effect is insignificant, and when the amount of the organic / inorganic hybrid material is less than 6% by weight, a problem may occur in forming a desired separator structure. An inorganic hybrid material is a hydrophilic polymer containing an amine group such as polyvinylpyrrolidone and an inorganic material selected from silica or titania coordinating in a sol to form a network structure, which is dried to form a fine powder and added to the polymer. Use it. In preparing the organic / inorganic hybrid material described above, 70 to 90 wt% of the hydrophilic polymer is contained and exhibits the best hydrophilic effect in the above range.

In addition, in the present invention, a separate additive may be added and used to control the pore size of the separator to be prepared, which is a well-known method in the art, and selects an appropriate amount by selecting a known pore control agent suitable for the desired pore size. Will be used. As pore regulators, poly (ethylene glycol), poly (vinylpyrrolidone), and poly (vinyl alcohol) of various molecular weights can be selected to increase pore size, and 1,4-dioxane and diethylene can be used to reduce pore size. Glycol dimethyl ether etc. can be used selectively.

As described above, the immersed membrane of the present invention increases the mechanical strength by the use of a tubular support, increases the permeation rate and improves the fouling resistance of the membrane due to the use of an organic / inorganic hybrid material, which is useful for water permeation and treatment of difficult degradable wastewater. It can be applied to the back.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are not intended to limit the present invention.

Example 1

80% by weight of polyvinylpyrrolidone and 20% by weight of titania were mixed and dried to prepare an organic / inorganic hybrid material as a fine powder. 5% by weight of the organic / inorganic hybrid material and 80% by weight of dimethylacetamide %, 15% by weight of polyvinylidene fluoride was mixed at room temperature and normal pressure to prepare a polymer solution.

The polymer solution prepared above was coated on a polypropylene polymer fiber of 350 denier yarn by immersion method at 15 ° C. for 1 minute, and then the organic / inorganic hybrid material was coated on the surface of the coated polymer support at room temperature for 1 minute. Recoating to prepare an immersion type membrane having a tubular support.

In order to measure the permeation characteristics of the prepared immersed membrane having a tubular support, the immersed membrane was consolidated for 2 hours at 25 ° C. and 1 bar using a solute 1,000 ppm aqueous solution having a polyethylene glycol (PEG) molecular weight of 100,000 and 200,000. The results of the permeation performance and rejection rate of the membrane after operation until the steady state was reached are shown in Table 2 below. In this case, the permeation rate and solute rejection rate were calculated by the following equations (1) and (2).

Example 2

It was prepared in the same manner as in Example 1, but an immersion type membrane was prepared by replacing the polymer fibers with polyester. In order to measure the permeation characteristics of the prepared immersed membrane having a tubular support, the immersed membrane was consolidated for 2 hours at 25 ° C. and 1 bar using a solute 1,000 ppm aqueous solution having a polyethylene glycol (PEG) molecular weight of 100,000 and 200,000. The results of the permeation performance and rejection rate of the membrane after operation until the steady state was reached are shown in Table 2 below.

Example 3

Prepared in the same manner as in Example 1, except that the immersion type membrane was prepared by replacing the polymer fibers with nylon. In order to measure the permeation characteristics of the prepared immersed membrane having a tubular support, the immersed membrane was consolidated for 2 hours at 25 ° C. and 1 bar using a solute 1,000 ppm aqueous solution having a polyethylene glycol (PEG) molecular weight of 100,000 and 200,000. The results of the permeation performance and rejection rate of the membrane after operation until the steady state was reached are shown in Table 2 below.

Example 4

Prepared in the same manner as in Example 1, but instead of the powder of the content shown in Table 1 to prepare an immersion type separation membrane. In order to measure the permeation characteristics of the prepared immersed membrane having a tubular support, the immersed membrane was consolidated for 2 hours at 25 ° C. and 1 bar using a solute 1,000 ppm aqueous solution having a polyethylene glycol (PEG) molecular weight of 100,000 and 200,000. The results of the permeation performance and rejection rate of the membrane after operation until the steady state was reached are shown in Table 2 below.

Example 5

Prepared in the same manner as in Example 1, but instead of the organic / inorganic hybrid compound to the content shown in Table 1 to prepare an immersion type separation membrane. In order to measure the permeation characteristics of the prepared immersed membrane having a tubular support, the immersed membrane was consolidated for 2 hours at 25 ° C. and 1 bar using a solute 1,000 ppm aqueous solution having a polyethylene glycol (PEG) molecular weight of 100,000 and 200,000. The results of the permeation performance and rejection rate of the membrane after operation until the steady state was reached are shown in Table 2 below.

Example 6

The same procedure as in Example 1 was performed except that the process of recoating with an organic / inorganic compound was performed to prepare an immersion type separation membrane. In order to measure the permeation characteristics of the prepared immersed membrane having a tubular support, the immersed membrane was consolidated for 2 hours at 25 ° C. and 1 bar using a solute 1,000 ppm aqueous solution having a polyethylene glycol (PEG) molecular weight of 100,000 and 200,000. The results of the permeation performance and rejection rate of the membrane after operation until the steady state was reached are shown in Table 2 below.

Comparative example

In the same manner as in Example 1, a polyvinylidene fluoride / dimethylacetamide (15/85 weight ratio) solution was used as the coating solution, and a separator was prepared without coating with an organic / inorganic hybrid. In order to measure the permeation characteristics of the prepared immersed membrane having a tubular support, the immersed membrane was consolidated for 2 hours at 25 ° C. and 1 bar using a solute 1,000 ppm aqueous solution having a polyethylene glycol (PEG) molecular weight of 100,000 and 200,000. The results of the permeation performance and rejection rate of the membrane after operation until the steady state was reached are shown in Table 2 below.

Classification (wt%) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example Polymer fiber Polypropylene polyester nylon Polypropylene Polypropylene Polypropylene Polypropylene Dimethylacetamide (DMAc) 80 85 80 80 85 Polyvinylidene fluoride 15 13 15 15 15 Organic / Inorganic Hybrid 5.0 3.0 5.0 5.0 Polyvinylpyrrolidone (PVP) (80) + Titania (TiO ₂ ) (20) PVP (85) + TiO ₂ (15) PVP (80) + TiO ₂ (20)

division PEO 100,000 PEO 200,000 Transmission rate (ton / m ² · day) % Rejection Transmission rate (ton / m ² · day) % Rejection Example 1 1.5 80 1.8 90 Example 2 1.7 80 1.7 90 Example 3 1.5 80 1.6 90 Example 4 1.0 80 1.2 90 Example 5 1.3 85 1.5 93 Example 6 1.2 80 1.2 85 Comparative example 0.5 75 0.6 80

As shown in Table 1, it was confirmed that the immersion type separation membranes of Examples 1 to 5 according to the present invention have superior permeability of 1.0 ton / m ² · day and rejection rate of 80% or more compared with the conventional separation membrane. In addition, in the case of Example 6 was not carried out the recoating process was confirmed excellent results in the transmittance and rejection rate.

As described above, in the present invention, after coating a polymer solution containing an organic / inorganic hybrid material together with a hydrophobic polymer on the surface of the tubular support, it is coated with an organic / inorganic hybrid material again to prepare an immersion type separation membrane. Compared with the improvement of mechanical strength, high water permeation rate and excellent fouling resistance of membrane, it is effective for water permeation and treatment of hardly degradable wastewater.

Claims (7)

On the surface of the tubular polymer support, A hydrophobic polymer coating layer formed by coating a hydrophobic polymer solution including 2 to 6 wt% of a hydrophilic polymer including an amine group and an organic / inorganic hybrid compound in which an inorganic material selected from silica and titania is coordinated; Immersion type separator, characterized in that the coating layer of the organic / inorganic hybrid compound is laminated on the polymer coating layer. The method of claim 1, wherein the tubular polymer support is made of a polymer fiber woven from 200 to 500 denier yarn (Yarn) is characterized in that the inner diameter is 0.5 to 3.0 mm, the outer diameter is 1.0 to 4.0 mm Immersion type separator. The immersion type membrane of claim 2, wherein the polymer fiber is at least one selected from polyester, polypropylene, and nylon 6,6. delete The immersion type membrane of claim 1, wherein the organic / inorganic hybrid compound is formed by coordinating 70 to 90 wt% of a hydrophilic polymer of polyvinylpyrrolidone and 10 to 30 wt% of an inorganic material selected from silica or titania. On the surface of the tubular polymer support, A hydrophobic polymer solution comprising 2 to 6 wt% of a hydrophilic polymer containing an amine group and an organic / inorganic hybrid compound coordinating inorganic materials selected from silica and titania is coated at a temperature of 10 to 30 ° C. for 5 seconds to 1 minute. after, Method for producing an immersion type separation membrane, characterized in that the organic / inorganic hybrid compound on the polymer coating layer on the coating for 5 seconds to 1 minute at room temperature. delete