JP2022126355A - Fine particle removal device and fine particle removal method - Google Patents

Abstract

To maintain fine particle removal performance of a size exclusion film over a long period of time, and extend its use life.SOLUTION: A fine particle removal device for removing fine particles in a liquid has a filtration film having charging property, and a size exclusion film arranged at a rear stage of the filtration film having the charging property, wherein the liquid is made to pass through the filtration film having the charging property and the size exclusion film in this order. Fine particle removal performance is maintained over a long period of time by reducing a fine particle integral load of the size exclusion film, and its use life can be extended.SELECTED DRAWING: Figure 1

Description

The present invention relates to a microparticle removal apparatus and a microparticle removal method for removing microparticles in a liquid in a pure water or ultrapure water manufacturing process, or in an electronic component manufacturing process, a semiconductor cleaning process, or the like, and a pure water or ultrapure It relates to water production equipment. In particular, the present invention is highly effective in removing fine particles with a particle diameter of 50 nm or less in liquids in systems such as subsystems and water supply lines before the point of use in ultrapure water production and supply systems, and electronic component manufacturing processes and semiconductor cleaning processes. It is useful as a technique for removing

Size exclusion membranes such as microfiltration membranes and ultrafiltration membranes are generally used as filtration filters for manufacturing semiconductors and electronic parts and as filtration filters used in semiconductor and electronic part manufacturing processes.
In addition to the size exclusion membrane, a positively charged membrane, specifically a polyketone membrane, may be added to the group consisting of primary amino groups, secondary amino groups, tertiary amino groups, and quaternary ammonium salts. There is a method of using a membrane having one or more cationic functional groups (Patent Document 1).
On the other hand, as the negatively charged membrane, 1 selected from the group consisting of a polyketone membrane, a sulfonic acid group, a sulfonic acid ester group, a carboxylic acid group, a carboxylic acid ester group, a phosphoric acid group, a phosphoric acid ester group, and a hydroxyl group There is also a method of using a membrane with one or more anionic functional groups (Patent Document 2).

JP 2014-173013 A JP 2014-171979 A

In general, size exclusion membranes such as microfiltration membranes and ultrafiltration membranes need to have smaller pore diameters as the particles to be removed become smaller. The problem was that the removal rate of fine particles decreased.

The present invention provides a particle removing apparatus and a particle removing method capable of improving such drawbacks of the size exclusion membrane, maintaining the particle removing performance of the size exclusion membrane for a long period of time, and prolonging the service life of the particle removing apparatus and the particle removing method. An object of the present invention is to provide a pure water or ultra-pure water production device including the device.

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that by providing an electrically charged filtration membrane in series in front of the size exclusion membrane, the integrated fine particle load of the size exclusion membrane can be reduced and fine particles can be collected. We have found a method to maintain the removal performance for a long period of time and extend the service life.
That is, the gist of the present invention is as follows.

[1] A microparticle removal apparatus for removing microparticles in a liquid, comprising a chargeable filtration membrane and a size exclusion membrane disposed downstream of the chargeable filtration membrane, wherein the liquid is the chargeable , and a fine particle removal device characterized in that water is passed through the size exclusion membrane in this order.

[2] The microparticle removal device according to [1], wherein the chargeable filtration membrane is a positively charged membrane or a negatively charged membrane.

[3] In [1], as the chargeable filtration membranes, two or more chargeable filtration membranes are used via a size exclusion membrane different from the size exclusion membrane or without a size exclusion membrane. 1. A particle removing device, characterized in that it is arranged in series and has the size exclusion membrane in the rear stage of the membrane group arranged in series.

[4] A pure water or ultrapure water production apparatus comprising the particle removal device according to any one of [1] to [3].

[5] A method for removing particles in a liquid using the particle removing apparatus according to any one of [1] to [3].

According to the present invention, it is possible to reduce the cumulative particle load of the size exclusion membrane that removes particles, maintain the particle removal performance over a long period of time, and extend the service life of the membrane.
According to the present invention, fine particles are stably and efficiently removed over a long period of time from water systems in general, particularly pure water and ultrapure water production processes, or from various liquids used in electronic component production and semiconductor cleaning processes to achieve high purification. can be achieved.

1 is a system diagram showing an embodiment of a particle removing device of the present invention; FIG. FIG. 4 is a schematic diagram for explaining a fine particle trapping mechanism by a membrane having a cationic functional group or an anionic functional group. FIG. 2 is a system diagram showing test equipment used in a reference example and a comparative example; It is a systematic diagram which shows the test apparatus used in the Example.

Embodiments of the present invention will be described in detail below.

[mechanism]
In the present invention, by arranging in series a filtration membrane having chargeability (hereinafter referred to as "chargeable membrane") in front of the size exclusion membrane, fine particles in the liquid to be treated are removed in advance in front of the size exclusion membrane. It is possible to reduce the particulate load on the subsequent size exclusion membrane and reduce the cumulative load.

For example, as shown in FIG. 2(a), a film having a cationic functional group does not easily adsorb positively charged fine particles, but easily adsorbs negatively charged fine particles. Can be efficiently captured and removed.
Conversely, as shown in FIG. 2(b), the film having an anionic functional group does not easily adsorb negatively charged fine particles, but easily adsorbs positively charged fine particles. Fine particles can be efficiently captured and removed.

In general, fine particles in a liquid are often positively or negatively charged. Therefore, by providing a chargeable membrane in front of the size exclusion membrane, these fine particles can be efficiently removed in advance. can reduce the particle loading of the size exclusion membrane and extend its service life.

Regarding the size exclusion membrane, it is desirable to suppress the integrated particle load to 10% or less when the entire membrane area is 100%, in order to maintain high particle removal performance. By providing a chargeable membrane in front of the size exclusion membrane, the ratio of the cumulative particle load (the ratio of the total amount of particles loaded to the membrane area covering the membrane area) to 10% or less of the entire membrane area. It is preferable to

[Particle removal device]
An embodiment of the particle removing apparatus of the present invention will be described in detail below with reference to FIG. 1, but the particle removing apparatus of the present invention is not limited to that shown in FIG.

For example, in FIG. 1, the chargeable membrane module 1 and the size exclusion membrane module 2 are provided in series. Alternatively, another membrane module may be arranged between the chargeable membrane module 1 and the size exclusion membrane module 2 .

In the particle removal apparatus of FIG. 1, the liquid to be treated introduced through the pipe 10 is introduced into the chargeable membrane module 1 and subjected to particle removal treatment, and then introduced through the pipe 11 into the size exclusion membrane module 2. After the fine particle removal treatment, the treated water is discharged out of the system through the pipe 12 .

<Liquid to be treated>
In the present invention, the liquid to be treated from which fine particles are removed is not particularly limited. Aqueous solution, thinner, carbonated water, hydrogen peroxide solution, hydrogen fluoride solution, etc., and typical alkaline liquids with a pH of 7 or higher include ammonia water, sodium hydroxide solution, etc., but not limited to these.
The present invention can be applied to the treatment of liquids in all pH ranges of pH 1-14.
Liquids in the neutral pH range include ultrapure water, typical acidic liquids with a pH of 7 or less include carbonated water, aqueous hydrochloric acid, and hydrogen fluoride solutions, and typical alkaline liquids with a pH of 7 or higher include Ammonia water, aqueous sodium hydroxide solution, etc. are available, but are not limited to these.

The present invention is effective in removing ultrafine particles having a particle size of 50 nm or less, for example, about 3 to 30 nm, in these liquids.

Although the fine particles are not particularly limited, fine particles of inorganic oxides such as silica, alumina, titania, and iron oxide, fluorine-based fine particles, organic resin fine particles, and the like can be mentioned.
Also, the fine particle concentration in the liquid to be treated is not particularly limited, but is usually 100 μg/L or less, or 1 to 10 ¹⁰ particles/mL.

The pH of the liquid to be treated is preferably in a region where the zeta potential of fine particles in the liquid is not reversed (a region where the isoelectric point is not crossed). For example, for alumina fine particles that are positively or negatively charged at pH 8, the range is always pH 8 or lower or always pH 8 or higher, and silica fine particles that are negatively or positively charged at pH 3 are always pH 3 or lower or pH 3 or higher. is preferably

<Chargeable membrane>
The chargeable membrane preferably used in the present invention will be described below.
In the following, a positively charged film is referred to as a "positively charged film" and a negatively charged film is referred to as a "negatively charged film".

The form of the chargeable membrane may be hollow fiber membrane, flat membrane, fiber, or the like. Hollow fiber membranes are generally used as terminal membrane modules for removing fine particles in ultrapure water production processes. On the other hand, a pleated flat membrane can also be used for the filter attached to the process washing machine.

<Porous membrane>
The porous membrane that serves as the base material of the chargeable membrane may be a polymer membrane, an inorganic membrane, or a metal membrane.

Polymer membranes include polyolefins such as polyethylene and polypropylene, polyethers such as polyethylene oxide and polypropylene oxide, fluororesins such as PTFE, CTFE, PFA, and polyvinylidene fluoride (PVDF), halogenated polyolefins such as polyvinyl chloride, and nylon. -6, polyamides such as nylon-66, urea resins, phenolic resins, melamine resins, polystyrene, cellulose, cellulose acetate, cellulose nitrate, polyetherketones, polyetherketoneketones, polyetheretherketones, polysulfones, polyarylsulfones, poly Materials such as ethersulfone, polyimide, polyetherimide, polyamideimide, polybenzimidazole, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyacrylonitrile, polyethernitrile, polyvinyl alcohol, and copolymers thereof can be used. However, it is not limited to this. There is no particular limitation to one type of material, and various materials can be selected as required.
Other polymers such as polyolefins and polyethers may be mixed with the chargeable or conductive polymer.

Materials such as alumina, zirconia, and titania can be used as the inorganic film, but the materials are not limited to these.

A material such as stainless steel can be used as the metal film, but the material is not limited to this.

<Chargeable functional group>
The charged functional groups to be introduced into the porous membrane include sulfonic acid groups, phosphoric acid groups, phosphonic acid groups, phosphinic acid groups, carboxylic acid groups, hydroxyl groups, phenol groups, quaternary ammonium groups, and primary to tertiary amines. groups, pyridine groups, amide groups, etc., but are not limited to these. These functional groups may be not only H-type and OH-type but also salt-type such as Na.

<Method for Introducing Chargeable Functional Group>
A method for introducing the chargeable functional group is not particularly limited, and various methods can be adopted. For example, in the case of polystyrene, sulfonic acid groups can be introduced by adding an appropriate amount of paraformaldehyde to a sulfuric acid solution and heat-crosslinking. In the case of polyvinyl alcohol, a functional group can be introduced by reacting a hydroxyl group with a trialkoxysilane group, a trichlorosilane group, an epoxy group, or the like. If it is not possible to directly introduce a functional group depending on the material, first introduce a highly reactive monomer (called a reactive monomer) such as styrene, and then introduce the functional group in two or more steps. The target functional group may be introduced through the process. These reactive monomers include, but are not limited to, glycidyl methacrylate, styrene, chloromethylstyrene, acrolein, vinylpyridine, acrylonitrile, and the like.

<Cationization Method and Functional Group>
The cationization method for introducing the positively charged functional group is not particularly limited, but examples include a coating method and a combination of these methods. A dehydration condensation reaction etc. are mentioned as the method by a chemical reaction. Plasma treatment, corona treatment and the like can also be used. The coating method includes a method of impregnating with an aqueous solution containing a polymer.

(1) Direct introduction of cationic functional groups into porous membrane by chemical modification For example, chemical modification methods for imparting cationic amino groups to polyketone membranes include chemical reaction with primary amines. ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,2-cyclohexanediamine, N-methylethylenediamine, N-methylpropanediamine, N,N-dimethylethylenediamine, N,N-dimethylpropanediamine, N Polyfunctionalized amines such as diamines, triamines, tetraamines, polyethylenimines, including primary amines such as acetylethylenediamine, isophoronediamine, N,N-dimethylamino-1,3-propanediamine, etc., have many activities. It is preferable because points can be given.

(2) Substitution of at least one hydrogen atom constituting the porous membrane with another group from the viewpoint of imparting a positive zeta potential Substitution methods include, for example, irradiation with electron beams, γ-rays, plasma, etc. After generating radicals by graft polymerization, a monomer having a reactive side chain such as glycidyl methacrylate is polymerized, and a reactive monomer having a functional group that expresses the desired function is added. Examples of reactive monomers include derivatives of acrylic acid, methacrylic acid, vinylsulfonic acid including primary amines, secondary amines, tertiary amines, quaternary ammonium salts, allylamine, p-vinylbenzyltrimethylammonium chloride, and the like. be done. More specific examples include 3-(dimethylamino)propyl acrylate, 3-(dimethylamino)propyl methacrylate, N-[3-(dimethylamino)propyl]acrylamide, N-[3-(dimethylamino) propyl]methacrylamide, (3-acrylamidopropyl)trimethylammonium chloride, trimethyl[3-(methacryloylamino)propyl]ammonium chloride and the like.

(3) Polymers having a positive zeta potential Examples of polymers for imparting a positive zeta potential include PSQ (polysilsesquioxane), polyethyleneimine, polydiallyldimethylammonium chloride, amino group-containing cationic poly(meth) Acrylic acid ester, amino group-containing cationic poly(meth)acrylamide, polyamineamide-epichlorohydrin, polyallylamine, polydicyandiamide, chitosan, cationized chitosan, amino group-containing cationized starch, amino group-containing cationized cellulose, amino Group-containing cationized polyvinyl alcohols and acid salts of the above polymers are included. Further, the polymer or the acid salt of the polymer may be a copolymer with another polymer.

<Anionization method and functional group>
The anionization method for introducing the negatively chargeable functional group is not particularly limited, but the following methods may be mentioned.

(1) From the viewpoint of imparting a negative zeta potential, negatively chargeable functional groups include a sulfonic acid group, a sulfonic acid ester group, a carboxylic acid group, a carboxylic acid ester group, a phosphoric acid group, a phosphoric acid ester group, One or more functional groups selected from the group consisting of hydroxyl groups are included.
Examples of forms having these functional groups include chemical bonding and physical bonding states. A chemical bond may be such as a covalent bond. A covalent bond includes a CC bond, a C=N bond, a bond via a pyrrole ring, and the like. A chemically bonding substance may be a polymer or a monomer having a small molecular weight. On the other hand, the physically bonded state includes states such as adsorption and adhesion in which intermolecular forces such as hydrogen bonding, van der Waals force, electrostatic attraction, and hydrophobic interaction are bonded without chemical bonding. be done.

Polymers for imparting negative zeta potential include polystyrenesulfonic acid, sodium polystyrenesulfonate, polyvinylsulfonic acid, sodium polyvinylsulfonate, poly(meth)acrylic acid, sodium poly(meth)acrylate, anionic polyacrylamide , poly(2-acrylamido-2-methyl group propanesulfonic acid), poly(2-acrylamido-2-methyl group sodium propanesulfonate), carboxymethylcellulose, anionized polyvinyl alcohol, polyvinyl phosphonic acid and the like.

(2) From the viewpoint of imparting negative zeta, the porous membrane may be attached or coated with a polymer having a negative zeta potential. As described above, polymers having a negative zeta potential include polystyrenesulfonic acid, polystyrenesulfonic acid, sodium polystyrenesulfonate, polyvinylsulfonic acid, sodium polyvinylsulfonate, poly(meth)acrylic acid, and sodium poly(meth)acrylate. , anionic polyacrylamide, poly(2-acrylamide-2-methyl group propanesulfonic acid), poly(2-acrylamido-2-methyl group sodium propanesulfonate), carboxymethylcellulose, anionized polyvinyl alcohol, polyvinyl phosphonic acid, etc. mentioned. Further, the polymer or the acid salt of the polymer may be a copolymer with another polymer.

(3) From the viewpoint of imparting a negative zeta potential to the porous membrane, when at least one hydrogen atom of the polymer constituting the porous membrane is replaced with another group, examples of the replacement method include electron beams, gamma rays, A method of generating radicals by irradiation with plasma or the like and then adding a reactive monomer having a functional group that exhibits a desired function can be mentioned.
Examples of reactive monomers include sulfonic acid groups, sulfonic acid ester groups, carboxylic acid groups, carboxylic acid ester groups, phosphoric acid groups, phosphoric acid ester groups, acrylic acid containing hydroxyl groups, methacrylic acid, vinyl sulfonic acid derivatives, and the like. is mentioned. More specific examples include acrylic acid, methacrylic acid, vinylsulfonic acid, styrenesulfonic acid and sodium salts thereof, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid , 2-acrylamido-2-methylpropanecarboxylic acid, 2-methacrylamido-2-methylpropanecarboxylic acid, and the like.

<Size exclusion filter>
The fine particle removal apparatus of the present invention comprises a chargeable membrane module 1 followed by a size exclusion membrane module 2 in series.
The size exclusion membrane is a porous membrane that does not intentionally introduce the anionic or cationic functional group described above, or a porous membrane that is not intentionally modified to have chargeability, and has a predetermined particle size. The object is to eliminate the fine particles described above.
If the membrane material itself has an electric charge, it is included in the size exclusion membrane.

As for the porous membrane that constitutes the size exclusion membrane, the same ones as in the chargeable membrane described above can be employed.

<Example of Arrangement Configuration of Chargeable Membrane and Size Exclusion Membrane>
In the microparticle removing apparatus of the present invention, the chargeable membrane and the size exclusion membrane are connected in series in this order. A different membrane may be provided in the subsequent stage.

The arrangement of the films that can be employed in the present invention includes the following, but the present invention is not limited to the following arrangement.
Negatively charged membrane → Size exclusion membrane Positively charged membrane → Size exclusion membrane Negatively charged membrane → Positively charged membrane → Size exclusion membrane Positively charged membrane → Negatively charged membrane → Size exclusion membrane Positively charged membrane → Size exclusion membrane → Negatively charged membrane → Size exclusion Membrane Negatively charged membrane → Size exclusion membrane → Positively charged membrane → Size exclusion membrane Negatively charged membrane → Size exclusion membrane → Positively charged membrane Positively charged membrane → Size exclusion membrane → Negatively charged membrane

<Preferred application area>
INDUSTRIAL APPLICABILITY The particle removal apparatus of the present invention is suitably used as a subsystem for producing ultrapure water from a primary pure water system in an ultrapure water production/supply system, particularly as a particle removal apparatus at the final stage of the subsystem. It may also be provided in a water supply line that delivers ultrapure water from the subsystem to the point of use. Furthermore, it can also be used as a final particle removal device at the point of use.

EXAMPLES The present invention will be described more specifically with reference to examples below.

In the following, a fine particle removal test was performed using the test apparatus shown in FIG. 3 or FIG.
The test apparatus shown in FIG. 3 prepares fine particle-containing test water by injecting fine particles from a fine particle tank 12 into a flow path 11 of a liquid to be treated by a pump P, and removes fine particles in the test water with a fine particle removal membrane module 13. The microparticle monitors 14 and 15 provided at the inlet and outlet of the microparticle removal membrane module 13 measure the concentration of microparticles in the inlet water and the outlet water, and the microparticle removal rate is calculated from these results. .
The test apparatus shown in FIG. 4 prepares fine particle-containing test water by injecting fine particles from a fine particle tank 12 into a flow path 11 of a liquid to be treated by a pump P, and using fine particle removal membrane modules 13A and 13B arranged in series. Fine particles in the test water are sequentially removed, and the fine particle concentration is measured by fine particle monitors 14 and 15 provided at the inlet of the fine particle removal membrane module 13A and the outlet of the fine particle removal membrane module 13B, respectively. configured to calculate a rate.
The water flow condition (water flow rate) of the liquid to be treated was set to 10 m/d.
The following microparticle monitors were used.
Particle monitor: UDI20 (manufactured by PMS)

As the positively charged membrane, the negatively charged membrane, and the size exclusion membrane, the following were used.
Positively charged membrane: "Qyu speed D" manufactured by Asahi Kasei Medical
DEA-diol (diethylamine-diol) is added to the polyethylene porous membrane
Membrane introduced Negatively charged membrane: Pall: "ABDIUPW3EH1"
Membrane in which a sulfone group is introduced into a polyethylene porous membrane Size exclusion membrane: "APDG1HSVH3EH1K13C Ulti-pleated G2SPDR" manufactured by Nippon Pall Co., Ltd., exclusion diameter 10 nm

The following microparticles were used.
Silica fine particles: manufactured by Sigma-Aldrich, average particle size 22 nm
Alumina fine particles: manufactured by Sigma-Aldrich, average particle size 22 nm

In each of Reference Examples 1 to 3 below, a fine particle removal test was performed using the test apparatus shown in FIG.

[Reference example 1]
Ultrapure water with a neutral pH, carbonated water with a pH of 4.5, or ammonia water with a pH of 10.5 is used as the liquid to be treated. The removal rate was examined for each.
Table 1 shows the results.

[Reference example 2]
A positively charged membrane module was used in place of the negatively charged membrane module, and the fine particle removal rate was examined in the same manner as in Reference Example 1.
Table 1 shows the results.

[Reference example 3]
A size exclusion membrane module was used in place of the negatively charged membrane module, and the fine particle removal rate was examined in the same manner as in Reference Example 1.
Table 1 shows the results.

From Table 1, regardless of the water flow conditions (particles used, liquid pH), the particle removal performance of the positively charged membrane and the negatively charged membrane is equal to or higher than the particle removal performance of the size exclusion membrane. can efficiently remove fine particles in the liquid.

[Example 1]
Using the test apparatus shown in FIG. 4, a positively charged membrane module was arranged as the particle removal membrane module 13A, and a size exclusion membrane module was arranged as the particle removal membrane module 13B, and 1×10 ⁷ particles/mL of silica particles were added to the ultrapure water. A fine particle removal test was performed on the injected test water, and changes over time in the fine particle removal rate were investigated.
Table 2 shows the results.

[Example 2]
A particle removal test was conducted in the same manner as in Example 1, except that a negatively charged membrane module was used instead of the positively charged membrane module, and alumina particles were injected instead of the silica particles.

[Comparative Example 1]
Using the test apparatus of FIG. 3, a fine particle removal test was performed on the same test water as in Example 1, except that only the size exclusion membrane module was used, and the results are shown in Table 2.

[Comparative Example 2]
Using the test apparatus of FIG. 3, a fine particle removal test was performed on the same test water as in Example 2, except that only the size exclusion membrane module was used, and the results are shown in Table 2.

As is clear from Table 2, when the size exclusion membrane alone was used, the performance of removing fine particles decreased after about 5 days. No decrease was observed.
It can be seen that placing the chargeable membrane in front of the size exclusion membrane suppresses deterioration of the fine particle removal performance of the size exclusion membrane and extends the service life.

1 Chargeable Membrane Module 2 Size Exclusion Membrane Module 12 Particle Tank 13A, 13B Particle Removal Membrane Module 14, 15 Particle Monitor

Claims (5)

A particle removal device for removing particles in a liquid, comprising a chargeable filtration membrane and a size exclusion membrane disposed downstream of the chargeable filtration membrane, wherein the liquid has the chargeability A fine particle removing device, wherein water is passed through a membrane and said size exclusion membrane in this order. 2. The fine particle removing apparatus according to claim 1, wherein the chargeable filtration membrane is a positively charged membrane or a negatively charged membrane. 2. According to claim 1, as the chargeable filtration membranes, two or more chargeable filtration membranes are arranged in series via a size exclusion membrane separate from the size exclusion membrane or without a size exclusion membrane. and having the size exclusion membrane in the rear stage of the group of membranes arranged in series. A pure water or ultrapure water producing apparatus comprising the fine particle removing apparatus according to any one of claims 1 to 3. A method for removing fine particles in a liquid using the fine particle removing apparatus according to any one of claims 1 to 3.

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