JPH04293581A - Method for purifying liquid - Google Patents

Abstract

PURPOSE:To perform the treatment of various liquids, that is, the treatment of industrial water represented by the preparation of pure water or desalted water, the treatment of industrial waste water represented by the removal of heavy metals, the separation and recovery of valuable metals in seawater or the purification of medicines. CONSTITUTION:In the treatment of various liquids, a fibrous polymer having an ion exchange group introduced thereinto by radiation graft polymerization and activated carbon are used.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to the treatment of industrial water such as the production of pure water and desalinated water, the treatment of industrial wastewater such as the removal of heavy metals, the separation and recovery of useful heavy metals from seawater, and the treatment of industrial water such as the production of pure water and desalinated water. It relates to methods for processing various liquids, such as purification of liquids.

0002

2. Description of the Related Art Impurities in liquids are generally divided into dissolved components and insoluble components such as suspended matter and colloidal substances. Dissolved components can be divided into ionic and nonionic components. As a technique for removing each impurity, ions are removed using an ion exchange resin, a reverse osmosis membrane, etc. Reverse osmosis membranes are suitable for desalinating water with relatively high salt concentrations, such as seawater, but there are differences in how they are used to desalinate river water, well water, etc., where the salt concentration is low, or to almost completely remove ionic components. However, ion exchange resins are used. Coagulation sedimentation and filtration have been used for a long time to remove insoluble components, but there is a limit to the size of particles that can be removed, and with the development of industry, further membrane treatment is often required at the end of use. . Membranes can be porous or non-porous, and can have shapes such as hollow fibers or flat membranes. Non-porous reverse osmosis membranes are also effective in removing particulates. Nonionic dissolved components are removed by activated carbon adsorption or the like.

[0003] As described above, methods for removing impurities from liquids have already been established and have many achievements.

Recent advances in science and technology have extended to the field of material development, and functional materials have gradually been applied to the above-mentioned prior art. For example, the inventor of the present invention
35432, we introduced ion-exchange groups into fibers, hollow fibers, and their processed products, which were originally only capable of removing particles, by using radiation graft polymerization. We are developing materials that can simultaneously remove particles and particles. However, since this method does not take into account the removal of nonionic components in the dissolved components, a separate operation is required to remove them, which reduces the benefits of composite functionalization by half.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently removing impurities in a liquid, that is, dissolved and undissolved components at the same time.

[0006]

[Means for Solving the Problems] The present invention is characterized by the use of activated carbon and a fibrous polymer into which ion exchange groups have been introduced by radiation graft polymerization.

[0007] Graft polymerization is called graft polymerization, and from a microscopic perspective, a graft side chain is protruded from the main chain of the base material by a covalent bond, and if a functional group is introduced into this,
New functions can be added while maintaining the physical and chemical properties of the base material, which is the main chain. If an ion exchange group or one that can be converted into an ion exchange group is selected as the functional group, an ion exchange fiber not only has excellent strength but also hardly peels or falls off. Furthermore, radiation graft polymerization can be applied to substrates with complex shapes. For example, by changing the fiber diameter, producing long fibers and processed products thereof, short fibers, aggregates of short fibers and processed products thereof, hollow fibers and porous hollow fibers, as well as fibers with non-circular cross sections and cut short pieces thereof. By using it appropriately, the function can be further enhanced. By using a plurality of fibers with different specific gravities, the used short fibers in a mixed state can be backwashed and separated, and each can be recycled. When disposed of without recycling, the fibers have the property of being easily combustible because there is no crosslinked structure within the fibers.

The ionizing radiation used in the radiation graft polymerization includes α, β, γ rays, electron beams, and ultraviolet rays, and any of them can be used, but γ rays, electron beams, etc. are suitable for the present invention. There is.

The fibrous polymers used in radiation graft polymerization include, among organic polymer compounds, polyolefins represented by polyethylene, polypropylene, etc., halogenated polyolefins represented by PTFE, vinyl chloride, etc. Ethylene-tetrafluoroethylene copolymer, ethylene-vinyl alcohol copolymer (EVA
), etc., but is not limited to this range.

The ion exchange groups introduced into the fibrous polymer include sulfone groups, carboxyl groups and phosphoric acid groups for cation exchange groups, and strongly basic quaternary ammonium groups and lower amines for anion exchange groups. weakly basic,
Furthermore, in addition to general acidic/basic ion exchange groups such as viridinium groups, chelate groups such as iminodiacetic acid groups can also be used, and are not particularly limited, depending on the type of liquid to be used and the required water quality. It can be selected appropriately in consideration of the following.

[0011] Methods for irradiating radiation to the fibrous polymer that is the base material include a simultaneous irradiation method in which radiation is irradiated while the base material and monomer coexist, and a simultaneous irradiation method in which the base material is irradiated in advance and then before contact with the monomer. There is an irradiation method, but any method can be used. In contacting the substrate and the monomer, the monomer may be either a vapor or a liquid.

On the other hand, activated carbon has excellent adsorption properties for organic matter, which is a nonionic dissolved component, so by using activated carbon and ion exchange fibers produced by graft polymerization, it is possible to simultaneously remove ions, particles, and organic matter. be. Activated carbon can be used in any of granular, powdered, and fibrous forms, and can be selected depending on the purpose. Fibrous activated carbon is extremely easy to mold and is particularly preferred in the present invention, which aims to provide multiple functions. Methods for using each of the materials described above are not particularly limited, and various methods can be considered that take advantage of the ease of molding, which is a characteristic of fibrous materials. The nonwoven fabric made of each fiber may be used as it is, may be cut, or both may be used in combination. . It is also possible to precoat the hollow fibers into which ion exchange groups have been introduced with powder or short activated carbon fibers.

For example, cut short pieces of ion-exchange fiber produced by radiation graft polymerization are mixed with powdered activated carbon, or mixed with cut pieces of fibrous activated carbon to form a filtration layer such as precoat filtration, and liquid can be filtered. Processing also represents an embodiment of the invention. In nuclear power plants, measures to reduce radioactive waste are important, and it is preferable to select materials that are advantageous for combustion, as in the present invention.

[0014]

[Example] Strongly acidic powder cation exchange resin (manufactured by Epicor, trade name PD3) 0.4 g, strong basic powder anion exchange resin (manufactured by Epicor, trade name PD1) 0.2 g, diameter produced by radiation graft polymerization 35μm, length 0.5
Strongly acidic cation exchange fiber consisting of 0.6 mm *0.6 g and activated carbon (trade name Evadia) are crushed in a roll mill to 200 g.
0.8g of powdered activated carbon that has passed through a mesh sieve was added to 11g of pure water in advance.
The mixture was mixed and stirred for 1 hour. This was packed into an acrylic column with a diameter of 50 mm with a saran net at the bottom, and iron hydroxide was injected into pure water to reach an iron concentration of 50 μg/las.
Synthetic raw water adjusted to contain Fe was passed through at a rate of 20 l/h. In addition, the electrical conductivity is 0.3 μs/cm, and the TOC is 0.
．． It was 23 mg/l. The quality of the treated water after 1 hour of water flow has an electrical conductivity of 0.06 μs/cm and an Fe content of 0.02 μg/cm.
l, TOC was 0.08 mg/l. *Production of strongly acidic cation exchange fibers by radiation graft polymerization After irradiating polypropylene long fibers with a diameter of approximately 30 μm with an accelerated electron beam of 20 Mrad, the fibers were brought into contact with styrene vapor for 20 hours to perform graft polymerization. Next, sulfonation was performed with chlorosulfonic acid to obtain a strongly acidic cation exchange fiber having an ion exchange capacity (neutral salt decomposition capacity) of 2.9 meq/g.

(Comparative Example) PD1 used in the example was 1.
A water flow test was conducted in the same manner as in the example except that 5g of PD3 and 0.5g of Fe
is 0.02μg/lasFe, TOC is 0.19mg/
It was clear that the removal performance of nonionic dissolved components shown in TOC was lower than that of the present invention.

[0016]

[Effects of the Invention] According to the present invention, impurities in a liquid, that is, ions, particles, and nonionic dissolved components, can be simultaneously removed using a fibrous material. In the treatment of liquids that require a high level of quality, for example in nuclear power plants, trace impurities in pure water are removed by precoding filtration for condensate treatment, and the ion exchange fiber of the present invention is used as a filter aid. By using powdered activated carbon or activated carbon fiber in an appropriate length, it is possible to reduce the leakage of fine powdered ion exchange resin from the precoat filament without losing ion and particle removal performance. It is now possible to remove non-ionic dissolved components. This will greatly contribute to the sound operation of the plant, the reduction of radiation exposure, and the reduction of radioactive waste. Furthermore, with the development of cutting-edge industries, demands on peripheral industries and peripheral technologies are becoming increasingly high. The highly functional material according to the present invention can provide those industries with a technical means to meet the demands for sophistication.

Claims (3)

[Claims] 1. A method for purifying a liquid, which uses activated carbon and a fibrous polymer into which ion exchange groups have been introduced by radiation graft polymerization. 2. Selected from long fibers spun from the fibrous polymer and processed products thereof, short fibers, aggregates of short fibers and processed products thereof, hollow fibers, porous hollow fibers, and cut short pieces thereof. The method according to claim 1, wherein [Claim 3]
The method according to claim 1 or 2, wherein the activated carbon is selected from granules, powders, and fibers.