JPH0368434A - Radiation resistant porous polymer membrane and membrane separating apparatus - Google Patents

Abstract

PURPOSE:To prolong the service life of a porous polymer membrane by forming a porous layer contg. a polymer which is cross-linked by irradiation on the surface of a base material. CONSTITUTION:A structure composed of two or more layers is rendered to a porous polymer membrane. At least one of the layers contains a hydrophobic polymer such as PE, paraffin, polystyrene, nylon, PP or polymethyl acrylate and the membrane has 0.05-10.5kgf/cm<2> bubble point and such a property that the Young's modulus decreases by <=5% or increases when at least one side of the membrane receives 10<4>-10<8>rad radiation. The reliability of the porous polymer membrane is enhanced and the service life is prolonged.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a porous polymer membrane used for separating and purifying or concentrating liquids, gases, or solids, and a membrane distillation apparatus using the same. This article relates to a porous polymer membrane that is optimal for use in environmental conditions and a membrane distillation device using the same.

[Conventional technology]

Separation operations using membranes are widely used industrially, such as in liquid-solid, gas-solid, gas-liquid, etc. filtration devices, gas separation devices, and ILI' (also referred to as thermopervaporation) devices. In these separation operations, metal sintered bodies and porous ceramic bodies are used in some cases, and
Polymer membranes are mainly used. Furthermore, various membrane shapes such as a flat membrane type, a spiral type, and a hollow fiber membrane type have been put into practical use. Various polymer membrane components are actually used, such as polyethylene, polypropylene, polyvinyl acetate, polysulfone, and polytetrafluoroethylene. Further, as described in Japanese Patent Application Laid-Open No. 588510, a composite membrane has also been devised in which a thin layer of metal or metal compound is provided on a polymer membrane to impart gas fluid selectivity.

A membrane distillation device consists of an evaporation section that passes a high-temperature stock solution through one side of a hydrophobic porous polymer membrane that allows gases to pass through but not aqueous solutions, and an evaporation section that passes a high-temperature stock solution through one side of a hydrophobic porous polymer membrane that allows gas to pass through but not an aqueous solution. It has a condensation section that cools and condenses on the other side of the membrane, and concentrates the stock solution on one side of the polymer membrane.
This is a device for obtaining condensate on the other side. Examples of hydrophobic porous polymer membranes that allow gas to pass through but not aqueous solutions include polytetrafluoroethylene (polytetrafluoroethylene), as described in JP-A-57-113801. Polypropylene or the like is used.

The structure of the condensing section of a membrane distillation device is described in Japanese Patent Publication No. 49-45461.
As described in the above publication, it generally consists of a space (vapor layer) in which the vapor that has passed through the porous polymer membrane diffuses, and a low-temperature heat transfer wall that extends vertically parallel to the membrane surface. It is. In this case, the vapor that has passed through the porous polymer membrane condenses on the low-temperature heat transfer wall surface and flows down. Also, JP-A-60
- Like the one described in Publication No. 64603, it does not have a vapor space in the condensing part and allows gas to pass through, but not an aqueous solution) Liquid exists in the hollow part and outside of the hydrophobic porous hollow fiber membrane. Furthermore, a membrane distillation apparatus has also been devised that performs distillation using the vapor pressure difference between volatile components.

Separation devices using membranes as described above have been applied to various fields, and have come to be used in radiation irradiation environments and in the separation and concentration of radioactive substances.

Hollow fiber membrane filters are used to filter and separate solids from radioactive waste fluids from nuclear power plants, and the application of membrane distillation equipment to the concentration of radioactive waste fluids is being considered.

However, in general, radiation irradiation causes molecular chain scission in polymer films, resulting in a decrease in strength. In particular, polytetrafluoroethylene (PTFE), which is a typical material for hydrophobic porous polymer membranes used in membrane distillation apparatuses, is greatly affected by molecular decay due to radiation irradiation. For this reason, the frequency of membrane replacement increases, and pinholes are more likely to be formed in the membrane, which may lead to a decrease in the purity of the separated and purified product. Particularly in the case of radioactive waste liquid treatment, high reliability is required for the equipment performance, and a decrease in membrane strength has been a major issue. In addition, porous polymer membranes with a layer of metal or ceramics on the membrane surface have slightly better radiation resistance, but when the membrane is incinerated after use, metal oxides are generated as secondary radioactive waste. There was a major problem in that the membrane separation device remained in a radioactive environment and lost the benefits of the membrane separation device in a radiation environment.

[Problem to be solved by the invention]

The present invention solves the above-mentioned problems in the conventional technology in a separation device having a membrane used in a radiation environment or used for separating and concentrating radioactive substances, and improves the longevity of the porous polymer membrane used in the device. The purpose is to provide a porous polymer membrane with high radiation resistance, and also to provide a membrane distillation device with a device structure that reduces the amount of radiation irradiated to the porous polymer membrane. It's about doing.

[Means to solve the problem]

The present invention relates to a porous membrane based on a hydrophobic polymer, which has a porous layer on at least one surface thereof containing a polymer that crosslinks when irradiated with radiation. It is a radiation-resistant porous polymer membrane. Porous layers containing polymers that crosslink when exposed to radiation include, for example, polyethylene, paraffin, polystyrene, nylon, natural rubber, gutta percha, polypropylene, polyacrylic acid, polymethyl acrylate, and polyacrylic. The porous layer is a porous layer containing at least one of polyvinyl chloride, polyvinyl allyl ester, polyvinyl methyl ketone, and polydimethyl siloxane.

Further, the present invention provides a porous polymer membrane having a structure of two or more layers, in which at least IJi contains a hydrophobic polymer, and the entire layer has a bubble point of 0.05 to 10.0 kgf/
cm2, 10' to 10' rad on either side.

A radiation-resistant porous polymer membrane characterized in that the Young's modulus decreases by 5% or less or the Young's modulus increases when exposed to a radiation dose of .

Furthermore, the present invention provides a membrane distillation apparatus having an evaporation section containing a liquid to be evaporated, a condensation section containing a condensate, and a porous polymer membrane between the evaporation section and the condensation section. A membrane distillation apparatus characterized by being a radiation-resistant porous polymer membrane for membrane distillation according to any one of Items 1 to 3.

The present invention also provides a membrane distillation apparatus having an evaporation section containing a liquid to be evaporated, a condensation section containing a condensate, and a porous polymer membrane between the evaporation section and the condensation section. A layered material that contains a metal element or carbon between a porous polymer membrane and allows gas or liquid to pass through, or a porous material that is similar to ceramics, or a porous material that contains a polymer that crosslinks when exposed to radiation. This is a membrane distillation apparatus characterized in that a membrane is arranged.

Furthermore, the present invention provides a membrane distillation apparatus having an evaporation section containing a liquid to be evaporated, a condensation section containing a condensate, and a porous polymer membrane between the evaporation section and the condensation section. This membrane distillation apparatus is characterized by being loaded with an insert.

The present invention also provides a membrane distillation apparatus in which a liquid containing radiation is caused to flow in contact with a porous polymer membrane, and the vapor of the liquid is condensed. This is a membrane distillation method characterized by using a radiation-resistant porous polymer membrane.

The hydrophobic polymer used as the base material of the porous membrane is mainly a fluorine-based hydrophobic resin, specifically, for example, PTF.
E (polytetrafluoroethylene) can be mentioned.

Polymers that crosslink when exposed to radiation include polyethylene, paraffin, nylon, natural rubber, gutta percha, polypropylene, polyacrylic acid, polymethyl acrylate, polyacrylamide, polyvinyl chloride, polyvinyl allyl ester, polyvinyl methyl ketone, and Examples include polydimethylsiloxane, and a porous layer containing one or more of these is formed on at least one surface of the porous polymer membrane. This can improve the radiation resistance of the porous polymer membrane.

A layered body that contains a metal element and is permeable to gas or liquid, installed between the liquid to be distilled in the evaporation section and a hydrophobic porous polymer membrane, or a porous body that is protected from ceramics, or that is exposed to radiation. Porous membranes containing crosslinkable polymers can have various configurations, such as a thin metal layer, a layered structure in which fine metal particles are dispersed in a porous polymer that crosslinks when irradiated with radiation, A porous metal plate, a porous ceramic plate, a porous plate mainly composed of carbon, etc. can be used. Instead of the porous plate described above, a mesh body having a similar structure can also be used. As for the metal used in this case, with the exception of hydrogen, the higher the atomic number, the greater the radiation shielding effect, so materials with high density containing heavy elements such as iron, barium, and lead are more effective.

The above-mentioned layered body and porous plate are placed between the porous polymer membrane and the liquid to be evaporated in the evaporation section, but they can be placed apart from the membrane, in contact with the membrane, or easily peeled off. It may be in any state where it is bonded to the membrane to the extent possible.

Specifically, metals, ceramics, glass, plastics, carbon fibers, or other polymers are used as the insert to be loaded into the liquid to be evaporated in the evaporation section, and the shape may be spherical or plate-like. It is not particularly limited to a body, a rod-shaped body, etc.

A radiation-resistant porous polymer membrane having a porous layer containing a polymer that crosslinks when irradiated with radiation on one surface of a hydrophobic porous polymer membrane, which will be described in detail later as an example of the present invention. A typical example is the effect of radiation irradiation on the stress-strain curve of a porous polymer membrane with a porous layer of polystyrene formed on one surface of polytetrafluoroethylene (PTFE). Figure 15 shows the results of the experiment.

PTFE disintegrates when irradiated with radiation and becomes extremely brittle. When PTFE is irradiated with more than 1 O'rad, molecular chain scission becomes noticeable and the melt viscosity decreases. If it is further exposed to a considerable amount of irradiation, it will crumble into powder.

However, based on the present invention, PTFE with a porous layer made of polystyrene formed on its surface was not irradiated with radiation, as is clear from FIG.
It can be seen that the Young's modulus of the material irradiated with radiation is larger (that is, the slope of the stress-strain curve is larger) than that of the material irradiated with radiation (non) in the figure, and the strength is increased.

The above has described the case where the radiation-resistant porous polymer membrane and distillation apparatus of the present invention are used for membrane distillation. It can also be applied to membrane separation in which substances are separated using a porous polymer membrane. In this case, it is preferable that part or all of the porous polymer membrane contains a polymer that crosslinks upon irradiation with radiation. By providing the tint pattern ray shielding layer and loading an interpolant, membrane separation can be made more dense in t#, and deterioration in the strength of the porous polymer membrane can be prevented.

[For production]

The radiation-resistant porous polymer membrane for membrane distillation of the present invention is a porous membrane that contains a polymer that crosslinks when irradiated with radiation on at least one surface of a porous membrane that is made of a hydrophobic polymer as a base material. Since the porous layer contains a polymer that crosslinks when irradiated with radiation, it not only shields the porous polymer membrane made of a base material that is sensitive to radiation from radiation, but also
By being irradiated with radiation, the porous layer containing a polymer that crosslinks upon being irradiated with radiation increases in strength, thereby increasing the strength of the entire layer.

The 3JX shielding effect of radiation increases as the atomic number increases, with the exception of hydrogen. In practical terms, dense materials containing heavy elements such as iron, barium, and lead are effective as radiation shielding materials; If formed on the surface of a porous polymer membrane, metal oxides and the like will remain as radioactive secondary waste when the membrane is incinerated after use. However, in the porous polymer membrane for membrane distillation of the present invention, since the shielding layer is also made of polymer, it can be incinerated, and no secondary waste is generated.

Polyfluoroethylene, polyisobutylene, polymethyl acrylic acid, etc. are polymers whose molecular chains break and disintegrate when exposed to radiation, but polystyrene, polyethylene, paraffin, nylon, natural rubber, gutta percha, polypropylene, and Acrylic acid, polymethyl acrylate, polyacrylamide, polyvinyl chloride, polyvinyl allyl ester, polyvinyl methyl ketone, polydimethyl siloxane, and the like are crosslinked and have a large Young's modulus when irradiated with radiation. Therefore, when a layer containing these polymers is formed on the surface of a porous polymer membrane,
In addition to its radiation shielding effect, it has the effect of increasing its strength when exposed to radiation.

In addition, in the membrane distillation apparatus of the present invention, a layered body containing a metal element and permeable to gas or liquid, or a porous body made of seratonx, or Since a porous membrane containing a polymer that crosslinks when irradiated with radiation is installed, the porous membrane containing a polymer that crosslinks when irradiated with radiation reduces the irradiation of radiation to the hydrophobic polymer membrane. Provides a radiation shielding effect.

In this case, since the porous polymer membrane is separate from the layered body, porous body, and membrane, or is easily peeled off and bonded to the membrane, there is no risk of causing any problem in incineration of the membrane after use.

Furthermore, the membrane distillation apparatus of the present invention includes metal plates, ceramic plates, plastic plates, metal balls, etc. in the liquid to be evaporated in the evaporation section.
Since an insert such as a ceramic pole is loaded, the insert itself acts as a radiation shielding material for the hydrophobic polymer membrane, and the amount of liquid to be evaporated (liquid to be treated) in the evaporator is reduced. The amount of radioactivity irradiated to the hydrophobic porous polymer membrane is reduced. This is because the amount of radioactivity irradiated to the hydrophobic porous polymer membrane is proportional to the amount of the liquid to be treated containing the radioactive substance. Therefore, it has the effect of making the hydrophobic polymer membrane of the membrane distillation apparatus last longer.

The above-mentioned shields and interpolators are different from porous polymer membranes,
Since there is no need to replace it, it is not considered secondary radioactive waste.

〔Example〕

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

<Example 1> Radiation-resistant material having a porous layer containing a polymer that crosslinks when irradiated with radiation on at least one surface of a hydrophobic porous polymer base material that allows gases to pass through but not aqueous solutions. It is a porous polymer membrane.

1 to 8 show specific examples of the radiation-resistant porous polymer membrane of the present invention.

What is shown in FIG. 1 is a porous polymer membrane in which a radiation shielding layer 2 is formed on one side of a hydrophobic porous polymer substrate 1 that allows gas to pass through but not an aqueous solution.

Radiation shielding layers such as polyethylene, paraffin, polystyrene, nylon, natural rubber, gutta percha, polypropylene, polyacrylic acid, polymethyl acrylate, polyacrylamide, polyvinyl chloride, polyvinyl allyl ester, polyvinyl methyl ketone, and polydimethyl siloxane. When a porous layer containing one or more of the polymers that crosslinks upon irradiation is formed, the radiation shielding layer itself increases in strength due to the irradiation, thereby increasing the radiation resistance of the porous polymer film.

What is shown in FIG. 2 is a cross section of a porous polymer membrane in which radiation shielding N2 is formed on both sides of a hydrophobic porous polymer base material 1. The radiation shielding layer is similar to that shown in FIG.

What is shown in FIG. 3 is a hydrophobic porous polymer base material 1 with a radiation shielding N2 formed on one side and a porous polymer membrane formed on the other side.
FIG. 2 is a cross-sectional view of a structure in which a metal thin film layer 3 separate from a hydrophobic porous polymer base material 1 is arranged.

What is shown in FIG. 4 is a porous polymer film in which a radiation shielding layer 2 similar to that shown in FIG. It is a sectional view of what N3 is arranged.

FIG. 5 shows a cross section of a porous polymer membrane consisting of five layers. It has a structure in which a hydrophobic porous polymer base material 1 and the same radiation shielding layers 2 are alternately laminated, and the surface thereof is a porous polymer film consisting of the radiation shielding layers 2.

The one shown in Figure 6 is a polymer that crosslinks when exposed to radiation, and a porous polymer that crosslinks when exposed to radiation, in which fine metal particles are dispersed on one side of a hydrophobic porous polymer base material l. It is a cross section of a porous polymer membrane in which layer 4 is arranged.

What is shown in FIG. 7 is a cross section of a hollow fiber membrane having a two-layer structure according to the present invention, in which a radiation shielding layer similar to that shown in FIG. 2 was formed.

What is shown in FIG. 8 is a cross section of a hollow fiber membrane having a 3N structure according to the present invention. A radiation shielding layer 2 similar to that shown in FIG. 1 is formed on the outer and inner surfaces of a hollow hydrophobic porous polymer substrate 1.

<Example 2> This is an example of a membrane distillation apparatus of the present invention.

What is shown in FIG. 9 is a flow path diagram of the membrane distillation apparatus of the present invention.

The evaporation chamber 5 is supplied with the liquid to be evaporated from the concentrate tank 16 and heated by the heater 15 from the evaporator 11 .

The liquid to be evaporated is passed from the evaporation chamber through the evaporation liquid outlet 12.
It forms the circulation system that returns to the liquid tank.

Steam that has passed through the hydrophobic porous polymer membrane 8 flows into the condensation chamber 6, and the steam condenses on the surface of the cooling heat transfer surface 7 parallel to the hydrophobic porous polymer membrane and flows down to form condensed water. From the outlet 10 it flows into the condensate tank.

The cooling water enters the membrane distillation apparatus main body from the cooling water port 13 and exits from the cooling water outlet 14.

In the evaporation chamber 5, the liquid to be evaporated and the hydrophobic porous polymer membrane 8
A radiation-shielding porous plate 9 that has a radiation-shielding effect and allows gas or liquid to pass through is arranged between the two. As the radiation shielding porous plate, a porous metal plate, a porous ceramic plate, or a porous plate mainly composed of carbon is used.

FIG. 10 is a configuration diagram showing the main body portion of the membrane distillation apparatus similar to FIG. 9.

In the evaporation chamber 5, near the hydrophobic porous polymer membrane 8,
Liquid-permeable net-like or porous polymer membrane protection plate 1
9 and filled with a spherical insert 20 made of ceramics (including glass), metal, or polymer. The spherical insert itself acts as a radiation shield, and also has the effect of reducing the amount of liquid to be evaporated in the evaporation chamber, thereby reducing the amount of radiation irradiated to the hydrophobic porous polymer membrane.

FIG. 11 shows the main body of a membrane distillation apparatus similar to that in FIG. 9, but with different specifications from that shown in FIG. 10! This is the 14th power map.

The condensation chamber 6 is filled with cooling water and has a hydrophobic porous polymer membrane 8
The steam passing through is directly cooled and condensed by the cooling water, and flows out together with the cooling water and the condensed ice water outlet 22.

In the evaporation chamber 5, a liquid-permeable net or porous polymer protection plate 19 is installed in the same way as shown in FIG. An insert 21 is installed.

FIG. 12 is a configuration diagram showing the main body portion of a membrane distillation apparatus having a plurality of distillation sections similar to that shown in FIG. 10.

This device is composed of a cooling water chamber 29, a cooling heat transfer surface 7, a condensation chamber 6, a hydrophobic porous polymer membrane 8, a condensation chamber, and a cooling heat transfer surface, and the evaporation chamber has a 10th Similar to the one shown in the figure, a net-like or porous polymer membrane protection plate 19 that allows liquid to pass through is installed near the polymer membrane, and a spherical inner layer made of ceramics (including glass), metal, polymer, etc. Fill with inserts 20.

<Example 3> Similar to the one shown in Figure 11, the 'a condensation chamber (part) does not have a vapor space or a cooling heat transfer surface, and the steam and cooling water that have permeated through the hydrophobic porous polymer membrane. This is a membrane distillation device that directly contacts and condenses.

As the hydrophobic porous polymer membrane used in this type of membrane distillation apparatus, hollow fiber membranes are efficient in that they have a large contact area.

FIG. 13 shows a block diagram of a hollow fiber membrane module according to the present invention.

The hollow fiber membrane 26 made of a hydrophobic porous polymer is fixed at both ends above and below the module, and cooling water flows through the hollow part.

The evaporated liquid flows into the module from the evaporated liquid population 11 on the side of the module and exits from the evaporated liquid outlet 12.

Steam permeates from the outer surface of the hollow fiber membrane into the hollow section, comes into direct contact with the cooling water flowing through the hollow section, and condenses.

A liquid-permeable or porous polymer membrane protection plate 19 similar to that shown in FIG. 1O is installed near the outer surface of the hollow fiber membrane. ), a spherical insert 20 of metal, polymer, etc. is filled.

Another method of membrane distillation in this embodiment using a hollow fiber membrane is a method in which the liquid to be evaporated is allowed to flow through the hollow part and the vapor is permeated from the hollow part to the outer surface. In this case, the evaporation chamber (parts)
In addition to filling the hollow parts of the hollow fiber membranes with spheres of ceramics (including glass), metals, polymers, etc. as inserts, as shown in Fig. 14, the hollow parts of the hollow fibers 11!26 are filled with A rod-shaped insert 27 made of metal, polymer, carbon fiber or ceramics can be installed.

[Effects of the Invention] As described above, the radiation-resistant porous polymer membrane of the present invention is a porous membrane based on a hydrophobic polymer, and at least one surface thereof is crosslinked by irradiation with radiation. It has a porous layer containing a polymer, and the porous layer containing a polymer that crosslinks when irradiated with the radiation is polyethylene, paraffin, polystyrene, nylon, natural rubber, gutta percha, polypropylene, polyacrylic acid, Since it is a porous layer containing at least one of polymethyl acrylate, polyacrylamide, polyvinyl chloride, polyvinyl allyl ester, polyvinyl methyl ketone, and polydimethyl siloxane, it is a porous layer that crosslinks when irradiated with the radiation. By forming a radiation shielding layer on the surface of a hydrophobic porous polymer membrane such as PTFB, whose strength decreases due to radiation irradiation, the porous layer containing molecules can be This makes the use of molecular membranes advantageous, and has the effect of increasing the reliability of porous polymer membranes used in the treatment of radioactive liquids and extending the lifetime of the nuclear layer.

Furthermore, the radiation-resistant porous polymer membrane of the present invention is a porous membrane having a structure of two or more layers, in which at least one layer contains a hydrophobic polymer, and the entire membrane has a bubble point of 0.0.
5 to 10.0 kgf/c1i, and when either side receives a radiation dose of 10' to 108 rad, the Young's modulus decreases by 5% or less, or the Young's modulus increases. Therefore, during membrane distillation or membrane separation in a radiation irradiation environment, it is possible to prevent the strength of the distillation membrane or separation membrane from decreasing due to radiation, and to obtain a membrane that can withstand long-term use.

Furthermore, the membrane distillation apparatus of the present invention includes an evaporation section containing a liquid to be evaporated, a condensation section containing a condensate, and a hydrophobic polymer membrane between the evaporation section and the condensation section. The molecular membrane is the radiation-resistant porous polymer membrane of the present invention as described above, and contains a metal element or carbon between the liquid to be evaporated and the hydrophobic polymer membrane in the evaporation section to allow gas or liquid to pass through. It has a layered body made of ceramic, a porous body made of ceramics, or a porous membrane containing a polymer that crosslinks when exposed to radiation, and an insert is loaded in the liquid to be evaporated in the evaporation section. Therefore, compared to conventional membrane distillation equipment, the layered body, porous body, or porous membrane installed in the evaporation section acts as a radiation shielding layer for the hydrophobic polymer membrane, and It has the effect of reducing the decrease in strength of the membrane due to radiation irradiation and extending the life of the hydrophobic polymer membrane in a radiation irradiation environment.

In addition, since the layered body, porous body, or porous membrane is separate from the porous membrane or is easily peeled off and joined, secondary waste is not generated when the porous membrane is incinerated after use. This has the effect that membrane distillation can always be carried out safely without causing any problems such as discharge.

By loading the insert into the liquid to be evaporated, the insert itself acts as a radiation shield, and the evaporator (
By reducing the amount of liquid to be evaporated in the chamber), it is possible to reduce the amount of radiation irradiated to the hydrophobic porous polymer membrane and extend the life of the membrane when treating radioactive liquid.

Furthermore, when radioactive waste liquid is treated with a membrane distillation device or a membrane separation device, the polymer membrane used for treatment also becomes radioactive waste, but by making it like the radiation-resistant porous polymer membrane of the present invention, The radiation-resistant porous polymer membrane and membrane distillation apparatus of the present invention can be disposed of by incineration and do not produce secondary waste, and the membrane can be replaced less frequently due to the extended membrane life. This has the great effect of significantly reducing the amount of radioactive waste, and also greatly reduces the amount of radiation exposure for workers, allowing them to work safely. It is something that has both.

[Brief explanation of drawings]

Figures 1 to 8 are cross-sectional views of radiation-resistant porous polymer membranes;
Figure 9 is a flow path diagram of a membrane distillation apparatus, Figures 10 to 12 are block diagrams of a membrane distillation apparatus, Figure 13 is a block diagram of a hollow fiber membrane modular type membrane distillation apparatus, and Figure 14 is a hollow fiber membrane diagram. Cross-sectional view of, 1st
Figure 5 shows PTFE with a polystyrene porous layer formed on its surface.
FIG. 3 is a diagram showing the influence of radiation irradiation on the stress-strain curve of . 1: Hydrophobic porous polymer base material. 2: Radiation shielding layer. 3: Metal thin film layer. 4: A layer in which fine metal particles are dispersed in a polymer that crosslinks when irradiated with radiation. 5: Evaporation chamber (part), 6: Condensation chamber (part). 7: Cooling heat transfer surface. 8: Hydrophobic porous polymer membrane. Radiation shielding porous plate. Evaporated liquid population, 12: Evaporated liquid outlet. Cooling water inlet, 14: Cooling water outlet. Heater. Concentrate tank. pump. Condensate tank. Polymer film protection plate. Spherical interpolant, 21: plate-like interpolant. Cooling water and condensate outlet. Condensate flow path. Liquid flow path to be evaporated, 25: Cooling water flow path. Hollow fiber membrane. Bar interpolation. Stock solution inlet. cooling water room

Claims (1)

[Claims] 1. A porous membrane based on a hydrophobic polymer, characterized in that at least one surface thereof has a porous layer containing a polymer that crosslinks when irradiated with radiation. Radiation-resistant porous polymer membrane for membrane distillation. 2. The porous layer containing a polymer that crosslinks when exposed to radiation is polyethylene, paraffin, polystyrene,
Nylon, natural rubber, gutta percha, polypropylene,
Polyacrylic acid, polymethyl acrylate, polyacrylamide, polyvinyl chloride, polyvinyl allyl ester,
The radiation-resistant porous polymer film according to claim 1, characterized in that the porous layer contains at least one of polyvinylmethylketone and polydimethylsiloxane. 3. In a porous membrane with a structure of two or more layers, at least one layer contains a hydrophobic polymer, the entire membrane has a bubble point of 0.05 to 10.0 kgf/cm^2, and one of the A radiation-resistant porous polymer characterized in that the Young's modulus decreases by 5% or less or the Young's modulus increases when the surface is exposed to a radiation dose of 10^4 to 10^8 rad. film. 4. A membrane distillation apparatus having an evaporation section containing a liquid to be evaporated, a condensation section containing a condensate, and a porous polymer membrane between the evaporation section and the condensation section, wherein the porous polymer membrane is 3. A membrane distillation apparatus comprising the radiation-resistant porous polymer membrane according to any one of 3. 5. In a membrane distillation apparatus having an evaporation section containing a liquid to be evaporated, a condensation section containing a condensate, and a porous polymer membrane between the evaporation section and the condensation section, the liquid to be evaporated in the evaporation section and the porous polymer membrane are provided. Placing a layered body containing a metal element or carbon and permeable to gas or liquid, a porous body made of ceramics, or a porous membrane containing a polymer that crosslinks when exposed to radiation between molecular membranes. A membrane distillation device featuring: 6. In a membrane distillation apparatus having an evaporating section containing a liquid to be evaporated, a condensing section containing a condensed liquid, and a porous polymer membrane between the evaporating section and the condensing section, the evaporating section is inserted into the liquid to be evaporated in the evaporating section. A membrane distillation device characterized by being loaded with a substance. 7. In a membrane distillation method in which a liquid containing radiation is passed through a porous polymer membrane and the vapor is condensed, the radiation-resistant porous polymer according to any one of claims 1 to 3 is used as the porous polymer membrane. A membrane distillation method characterized by using a membrane.