JP2686949B2 - Selective adsorption functional microfilter and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to general industrial water and waste water, for example, washing rice water used for the purification of sake that requires iron removal in particular, or squeegee of sake (deproteinized protein). ), Or especially in nuclear condensate where removal of iron ions is required, a useful and novel selective adsorption functionality capable of simultaneously removing trace amounts of iron ions and fine particles such as colloidal substances, bacteria, and clats that are simultaneously included. The present invention relates to a microfilter and a method for manufacturing the same.

[Conventional technology]

Conventionally, for example, process water used for sake production affects the flavor of sake even if it contains an extremely small amount of iron, and therefore water from an extremely high-quality water source has been used.

If it is unavoidable to use underground water near the city, activated carbon or tannin products (such as immobilized tannin from Tanabe Seiyaku) are used to remove iron mixed in the water due to soil contamination in recent years. Has been used. Other water and other micro-organisms are contained in the water and it is necessary to remove these as well.

On the other hand, it is often not necessary to remove trace amounts of metal ions contained in water, such as sodium ions and calcium ions.

Up to now, a method for efficiently removing special ions such as iron ions, bacteria, and fine particles at the same time has not been known.

[Problems to be solved by the present invention]

An object of the present invention is to provide a novel and useful selective adsorption functional microfilter capable of efficiently removing a trace amount of iron ions and / or proteins and fine particles contained in water at the same time, and a method for producing the same. It is a thing.

[Means for solving the problem]

The present inventors have found that the above objects can be achieved by the following means.

That is, the present invention comprises a polyolefin, a copolymer of an olefin and a halogenated olefin, or polyvinylidene fluoride having an average pore diameter of 0.01 to 5 µ and a porosity of 20 to 80.
% To a porous membrane having a substantially three-dimensional network structure,
Weight% tannin is preferentially distributed and fixed at least on the surface of the pores of the porous membrane. Inner diameter 0.05-10 mm, wall thickness 0.05-5 m
The present invention relates to a hollow fiber-shaped selective adsorption functional microfilter of m, and a method for producing the above microfilter, which comprises irradiating the porous membrane with ionizing radiation, grafting grindyl methacrylate, and then reacting and adding tannin.

 Hereinafter, the present invention will be described in more detail.

The material of the porous membrane used in the present invention is polyolefin, a copolymer of olefin and halogenated olefin,
Alternatively, it needs to be made of polyvinylidene fluoride or the like and have hydrophobicity, which helps maintain the mechanical properties required as a base film.

Specific examples of polyolefins and copolymers of olefins and halogenated olefins include polyolefin resins, for example, homopolymers of olefins such as polyethylene, polypropylene and polybutylene, or a mixture of two or more thereof; or ethylene and propylene. , A copolymer of two or more kinds of olefins such as butene, pentene, and hexene; a copolymer of one or more kinds of the above olefins and a halogenated olefin such as tetrafluoroethylene or chlorotrifluoroethylene. It

The microfilter of the present invention preferably has an average pore size in the range of 0.01 μ to 5 μ in terms of ion adsorption, colloidal substance removability and permeation rate.

Here, the average pore size indicates the value obtained by the method described in ASTM F316-70, which is usually called the air flow method, and the air permeation flux of a dry membrane and a wet membrane is measured by changing the air pressure. Then, it is obtained from the ratio.

The range of the average pore size in the present invention is set from the viewpoint of practical performance, and in the range other than this range, it is inappropriate in terms of the transmission rate or the effect of removing fine particles.

The porosity is preferably in the range of 20 to 80%.
Here, the porosity is measured by previously immersing the microfilter in a liquid such as water, drying it, and measuring the weight change before and after the drying.

When the porosity is out of the range of the present invention, it is not preferable in terms of the transmission speed, mechanical properties, and the like.

The pore structure of the substrate porous membrane which is the base of the microfilter of the present invention can be obtained by various molding processing means.

Specifically, a stretching method or a so-called etching method, which is produced by chemical treatment after electron beam irradiation, is also applicable, but the pore structure of the porous membrane is a straight hole obtained by the stretching method or etching method. Rather than the through-hole structure, it is formed by the microphase separation method or the mixed extraction method disclosed in, for example, Japanese Patent Publication No. 40-957, Japanese Patent Publication No. 47-17460 and Japanese Patent Publication No. 59-37292. Those having a three-dimensional network structure are preferable.

The shape of the microfilter may be a flat membrane, a tube, or a hollow fiber membrane, and for the purpose of the present invention, a hollow having an inner diameter of 0.05 to 10 mm and a thickness of 0.05 to 5 mm. Use a thread-shaped one.

The microfilter of the present invention must have 1 to 25% by weight of tannin immobilized. Here, the tannin content of the microfilter is represented by (W ₂ −W ₁ ) / W ₂ × 100.

In the above formula, W ₁ and W ₂ are the weights of the film before and after the reaction with tannin.

When the tannin content is less than 1% by weight, the adsorption function is small, and when it is 25% by weight or more, the filtration rate of water is decreased more than the effect of the adsorption function, and the function of the microfilter is greatly deteriorated.

Here, the tannin content is a value based on a considerably macroscopic weight of the film, and does not mean, for example, a weight obtained by taking out only a part of the film surface or a part of the inside. In order to treat the porous membrane as a substrate while maintaining the excellent mechanical properties, it is easier to achieve the purpose by preferentially reacting (grafting) tannin to the surface of the pores as much as possible. Therefore, the meaning of the tannin content referred to here is a value which is averaged and measured over the entire surface of the film, and does not mean the weight (%) from a microscopic viewpoint.

The microfilter of the present invention is obtained by irradiating a porous membrane with ionizing radiation, preferably γ-rays or electron beams, and then graft-polymerizing glycidyl methacrylate, and then adding tannin, for example, quintuple tannin to the reaction. .

Irradiation with γ-rays or electron beams is usually performed in vacuum or in an inert gas. The graft polymerization is preferably carried out by gas phase polymerization. Further, if necessary, another functional monomer such as triethylene glycol dimethacrylate having two or more polymerization groups capable of copolymerization may be added together.

The reaction with tannin is carried out in solution under inert gas,
After that, it is washed with water and dried.

The thus-obtained selective adsorption functional microfilter of the present invention specifically adsorbs and reacts with iron ions and at the same time efficiently removes bacteria, fine particles and the like.

Hereinafter, the configuration and effects of the present invention will be specifically described by way of examples, but they do not limit the present invention.

(Examples and Comparative Examples)

22.1 parts by weight of finely powdered silicic acid (Nipsil VN3LP), 55.4 parts by weight of dioctyl phthalate (DOP), and 22.5 parts by weight of polyethylene resin powder [Asahi Kasei SH-800 grade] are premixed and then the inner diameter is 0.7 in a 30 mm twin-screw extruder. mm, thickness 0.2
After extrusion into a 5 mm hollow fiber, 1,1,1-trichloroethane [chlorocene VG (trade name)]
It was immersed in the solution for 60 minutes to extract DOP. Further, it was immersed in a 40% aqueous solution of caustic soda at a temperature of 60 ° C. for about 20 minutes to extract fine silicic acid, which was then washed with water and dried.

The obtained porous film was irradiated with 20 Mrad of electron beam in a nitrogen atmosphere using an electron accelerator (pressurization voltage: 1.5 MeV, electron beam current: 1 mA), and then glycidyl methacrylate was grafted in the gas phase.

Further, 30 mg of the porous membrane was immersed in 200 cc of 5% tannin tannin (Dainippon Pharmaceutical Co., Ltd.) 3% aqueous solution using a reflux type rotary evaporator, and under the condition of ph = 7, nitrogen was blown at 0-2 ml / min at 80 ° C. The reaction time was 1 hour.
After the reaction, the membrane was washed with water and vacuum dried to obtain the hollow fiber membrane of the example.

The comparative example was carried out in the same formulation as in the example, except that the reaction addition of quintile tannin was carried out under the condition of ph = 9 for a reaction time of 5 minutes.

The obtained hollow fiber membrane had the following physical properties. Examples Comparative Examples Porosity (%) 57 59 Average pore diameter (μ) 0.15 0.19 Tannin content (%) 15 0.2 The measuring method was the above-mentioned method.

Prior to the filtration test, the above two types of membranes were put into an aqueous solution of ferrous ammonium sulfate having a concentration of 5 g-Fe / m ³ and shaken. After confirming that the adsorption equilibrium was reached, iron was eluted with hydrochloric acid to measure the adsorption amount.
The quantitative determination of iron was according to the o-phenanthroline method.

 The amount of iron adsorption thus obtained is shown below.

(The measurement was performed at 30 ° C.) Iron concentration in the film (G.Fe / kg. Membrane) Example 8.5 Comparative Example 0.2 As shown in the table above, the microfilter of the present invention has a high iron adsorption capacity.

Next, a filtration test was actually conducted using the water quality liquid shown below.

(Undiluted solution) Fine particle concentration in undiluted solution ¹⁾ 2.5 × 10 ⁴ particles / cc Bacterial concentration ²⁾ 1.4 × 10 ³ particles / cc Iron ^{+ 3)} Ion concentration 0.15 mmol / sodium ion concentration 0.50 mmol / 1) Pore diameter 0.2μ Value directly measured with a microscope on a polycarbonate flat film 2) Value directly measured with a microscope after staining by Broca staining method.

The results are shown below. Example Comparative Example Initial transmission rate (/hr.m ² .atm) 100 150 Fine particle removal rate (%) 99.5 99.4 Iron removal rate (%) 95 5 Sodium removal rate (%) 5 3 The microfilter of the present invention is substantially It can be seen that it does not have a removing effect on sodium ions, while it has a particularly excellent removing efficiency for iron ions. Furthermore, after performing a filtration test for about 5 hours by this method,
When a microfilter was dipped in a strong hydrochloric acid solution to regenerate it and the iron ion removal rate was measured again, it was 98% of the initial removal rate.
The retention rate of

〔The invention's effect〕

The selective adsorption functional microfilter of the present invention has both an iron ion removing (adsorbing) function and a fine particle removing function, and in particular, iron ion and fine particles, water for sake industry that dislikes the presence of bacteria, and an undigested sake of sake. It is suitable for refining water for nuclear condensate.

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Claims (2)

(57) [Claims] 1. A porous membrane having a substantially three-dimensional network structure of polyolefin, a copolymer of olefin and halogenated olefin, or polyvinylidene fluoride having an average pore diameter of 0.01 to 5 μm and a porosity of 20 to 80%. A hollow fiber-shaped selective adsorption functional microfilter having an inner diameter of 0.05 to 10 mm and a wall thickness of 0.05 to 5 mm, in which 1 to 25% by weight of tannin is preferentially reactively fixed to at least the surface portion of the pores of a porous membrane. 2. The method for producing a microfilter according to claim 1, wherein the porous membrane is irradiated with ionizing radiation, grafted with glycidyl methacrylate, and then tannin is reactively added.