JPH0871380A - Novel module - Google Patents

Abstract

PURPOSE: To provide a module developing high-degree separating and purifying capacity by holding the strength of the hollow yarn function membrane charged in the module and making the flow of the fluid to be treated flowing along the outside of hollow yarn turblent or preventing channeling. CONSTITUTION: In a module wherein a housing is packed with a hollow yarn membrane, the space part between the housing and the hollow yarn is filled with a sponge structure mainly constituted of org. matter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a module filled with a hollow fiber functional membrane. More specifically, it is possible to impart strength while maintaining the separation performance of the functional membrane, and
The present invention relates to a module filled with a hollow fiber-shaped functional film capable of ensuring a high contact efficiency of a treatment fluid with the surface of the functional film.

[0002]

2. Description of the Related Art A separation functional membrane has a high separation coefficient, a large amount of treatment, and strength and durability capable of withstanding long-term use or repeated use.
The history of technological development was how to adjust the points and improve efficiency. In order to increase both the separation coefficient and the throughput, a thin film, a small pressure loss, and a highly reliable separation / purification capability have been demanded. However, the thinner the film, the lower the physical strength, and the longer it becomes unable to withstand. In order to solve this problem, the methods that have been used so far have adopted a multi-layered membrane having both a thin active layer for separation and purification and a supporting layer for holding the active layer and maintaining strength. Method.
For ultrafiltration membranes and reverse osmosis membranes, the development of spinning technology has led to the development of high-performance membranes with an active layer on the surface, and the coating technology for porous membranes has led to the development of membranes with similar functions. Has been done.

However, in these techniques, for example, in the case of a method of obtaining both an active layer and a support layer by spinning, the strength of the support layer is maintained, the separation performance of the active layer and the amount of treated water due to the influence of both are secured. Therefore, it is difficult to obtain structural control of both the active layer and the support layer under one spinning condition,
The limits to high functionality are beginning to be seen. Also. Also in the coating method, the separation performance of the active layer and the adhesive property to the support layer are not necessarily compatible with each other, and there is a problem that the coating peels off during use.

Therefore, in the research and development of the active layer, while a high level separation and purification technique can be obtained by controlling at the molecular level, there is no means for holding it, so the film thickness should be increased to maintain the strength. Was needed, and in the end there was a dilemma that the throughput could not be obtained. In order to solve the above-mentioned problems, it is necessary to ensure the separation performance in the active layer and the durability in the membrane system independently.

It is to be noted that what is expected to be put to practical use in the future as a high-performance film is a type in which a processing fluid is brought into contact with the surface of the functional film and only a specific substance in the processing fluid is permeated. In the case of such a membrane, the contact efficiency between the processing fluid and the membrane surface becomes a problem. In order to increase the contact area of the fluid per unit volume in the module, a hollow fiber shape is desirable as the functional membrane shape, but in the case of the hollow fiber shape, the flow outside the membrane does not necessarily become turbulent and the target substance in the fluid is In some cases, the fluid may not sufficiently contact with the membrane surface, or channeling may occur, and the fluid may actively contact only with the particular membrane surface, and the other portion may remain. Therefore, the Donnan dialysis membrane or the like has no choice but to rely on a method of adopting a flat membrane and making the separator between the membranes turbulent. Further, a method of winding another kind of fiber or the like on the surface of the hollow fiber membrane for the purpose of maintaining strength has been proposed (Japanese Patent Laid-Open No. 63-31502). It is enough.

Although a ceramic filter has a structure similar to that of the present invention, the ceramic filter has an active layer formed on the inner surface of a cavity corresponding to a hole of a lotus root-shaped porous body having a cylindrical cavity. It has been coated. Since a ceramic filter undergoes a high temperature sintering process in its production process, it is not necessary to form a lotus root-like ceramic porous body on the outside of the hollow fiber membrane having a high separation and purification capability. Absent. Therefore, the method is limited to a method in which a lotus root-like ceramic porous body having a hollow structure is manufactured in advance, and then an active layer is introduced in the form of an inner surface coating, which is a problem such as stability of a conventional coating. Will remain as usual.

Further, in the module using this ceramic filter, the inner diameter of the lotus root-like hollow structure is stably small, and it is difficult to introduce a large number, so that the area of the active layer in the module is not always sufficiently large. There is also a drawback. As described above, in the field of functional membranes, despite the fact that many excellent separation and purification capacities have been confirmed on a lab scale, major problems remain unsolved for practical use.

[0008]

DISCLOSURE OF THE INVENTION In a module filled with a hollow fiber-shaped functional film, strength is imparted while maintaining the separation performance of the functional film, and high contact efficiency of the treatment fluid with the surface of the functional film is secured. The purpose is to provide a new module that can do.

[0009]

[Means for solving the problem] As a result of earnest research,
The following inventions have been achieved. That is, according to the present invention, in a module in which a hollow fiber membrane is filled in a housing, a space portion between the housing and the hollow fiber membrane is filled with a sponge-like structure mainly composed of an organic substance. This is a new module.

By adopting such a structure, the strength of the hollow fiber membrane is maintained, and high contact efficiency between the outside of the hollow fiber membrane inside the module and the fluid is ensured, and the separation performance, throughput, and durability are improved. In all cases, excellent new modules could be obtained. An example is shown in FIG.
The present invention will be described in more detail.

A very wide range of hollow fiber membranes can be applied to the module. Basically, since the outside of the hollow fiber membrane is filled with a sponge-like structure, the strength characteristics are such that it is resistant to internal pressure rupture, and the treatment liquid becomes turbulent when it circulates outside the membrane. Or the channeling can be prevented, and high contact efficiency can be obtained.

Ultrafiltration membrane, reverse osmosis membrane, nanofilter,
When applied to a filtration membrane such as a microfiltration membrane, by basically filling a hollow fiber membrane having only the active layer with the desired separation performance and permeation amount, and filling the outside of the hollow fiber membrane with a sponge-like structure. It is possible to configure a module having excellent internal pressure burst strength, and for example, it is possible to obtain a cross-flow type internal pressure type high performance separation membrane module.

Considering application to a dialysis membrane, a Donnan dialysis membrane, a membrane having a fixed carrier such as crown ether, an active transport membrane, or a supported liquid membrane, the treatment liquid is in a sponge-like structure outside the hollow fiber membrane. Since the flow is turbulent and the flow is turbulent or the channeling is suppressed, it is possible to secure high contact efficiency with the membrane surface and maintain high membrane permeation efficiency of specific substances in the treatment fluid. can do. In this case, the pressure difference between the inside and outside of the hollow fiber membrane can be alleviated by adjusting the pressure of the liquid that is filled or circulated inside the hollow fiber membrane, and the collapse of the membrane due to external pressure compression can be prevented.

When a membrane for pervaporation is applied, a method in which the treatment fluid is circulated inside the hollow fiber and the pressure is depressurized outside the hollow fiber is because the pressure on the membrane becomes the internal pressure, and therefore the strength is stabilized. Then it is preferable. However, in order to ensure a high contact efficiency with the membrane surface, it is preferable that the treatment fluid be circulated outside the membrane, and in this case, in order to stabilize the strength, by circulating a carrier gas inside the hollow fiber, It is possible to reduce the influence of pressure from the outside of the hollow fiber membrane.

Further, for example, a film thickness of 5000 Å such as a Langmuir-Blodgett film or a bimolecular film similar to a biological film.
When a functional membrane whose structure is controlled at the molecular level is applied to this system with the following membranes, the outer surface of the hollow fiber-like porous support is coated with these membranes, and after filling the module, it is further externally applied. It is possible to obtain high durability by fixing with a sponge-like structure, that is, by sandwiching these membranes between the hollow fiber-like support and the sponge-like structure. In this system, high contact efficiency with the hollow fiber membrane surface can be obtained.

Further, when a gas separation membrane is applied to this module, the membrane having a high separation coefficient for gas permeation and a high permeation flow rate is an ultra-thin film whose structure is controlled at the molecular level, so that it is hollow. It is preferable to coat the filamentous support, then fill the module and fix the exterior of the membrane with a sponge-like structure to achieve high strength. By allowing the processing fluid to flow through the outside of the membrane to obtain high contact efficiency, it is possible to obtain a gas separation module with high accuracy and high permeation amount. In the case of a gas separation membrane, a new high-efficiency gas separation membrane module can be constructed by a system in which a liquid having a high solubility for a specific gas is circulated inside the hollow fiber membrane and a treated gas is circulated outside the membrane. it can. Further, in that case, the load on the membrane due to external pressure compression is reduced, which is preferable.

As described above, a wide range of hollow fiber membranes can be applied to the module. Since the present invention is particularly utilized by applying a functional film having a small film thickness and an excellent separation coefficient and transmission amount, the film thickness is 0.5.
μm to 1 mm is preferable, and 5 μm to 500 μm is more preferable. If the film thickness is too thick, the resistance to permeation through the film increases, and it is meaningless to increase the contact efficiency with the film surface according to the present invention. On the other hand, if the film thickness is too thin, the limit of the function of maintaining strength according to the present invention will be exceeded, and the risk of film breakage will still occur. In that case, it is preferable to apply a method in which the hollow fiber-shaped support is coated with the film so that the film thickness combined with the support falls within the above range, and the film is introduced into the module to introduce the sponge-like structure. .

The inner diameter of the membrane is preferably 50 μm to 5 mm,
More preferably, it is 100 μm to 1 mm. If the inner diameter of the membrane is too small, the pressure loss of the fluid flowing through the hollow portion increases. In addition, if the inner diameter of the membrane is too large, the membrane area per unit volume in the module will not be large and the treatment efficiency will be low.In addition, if the inner diameter of the membrane is too large in terms of strength characteristics, the internal pressure burst strength and the external compression strength will be reduced. Is low, which is inconvenient.

In the present invention, the sponge-like structure is mainly composed of an organic substance. The performance required of the sponge-like structure is that the conditions for degrading the hollow fiber membrane do not elapse in the process of forming the sponge-like structure. High temperature conditions such as the sintering process in ceramic filters are not applicable. Further, in the process of forming the sponge-like structure, it is required to smoothly enter between the hollow fiber membranes without damaging the outer wall of the hollow fiber membranes. When the module is used, it absorbs dimensional changes such as swelling of the membrane, and also has the flexibility to absorb the vibration of the membrane due to the flow of fluid, and functions as a support for the membrane. It is required that the foam has continuous pores so that the flow outside the membrane is efficiently turbulent and that the foam has a uniform sponge structure so that channeling does not occur.

As a method of forming a sponge-like structure which meets such conditions, a method of foaming various organic substances in a module is preferable. The sponge-like structure obtained by foaming is mainly composed of an organic substance. There are various types of organic materials that can be foamed, and they should be selected according to the purpose.For example, flexible polyurethane foam meets the above conditions, and various foaming conditions have been established depending on the purpose. And is preferred. Also, depending on the fluid used, chemical durability, particularly acid resistance, is required.
A silicon-based foam is suitable.

As a hollow fiber membrane having a separating function, a filtration membrane such as an ultrafiltration membrane, a reverse osmosis membrane, a nanofilter or a microfiltration membrane, as well as a dialysis membrane, a Donnan dialysis membrane or a pervaporation membrane is used. Membrane, membrane with fixed carrier,
Various functional membranes such as an active transport membrane and a gas separation membrane can be applied. In any of the functional films, the support layer for maintaining the strength is not always necessary. Basically, it is possible to fill strength with a thin membrane consisting only of an active layer that expresses separation and purification ability, and to maintain strength by a sponge-like structure in the module. In particular, in the above applications other than the filtration membrane, that is, when a functional membrane of a type in which a treatment fluid flows outside the membrane and only a specific substance in the fluid selectively permeates the membrane, the fluid is a membrane. Can be turbulent externally,
Alternatively, channeling can be prevented, and high contact efficiency between the surface of all functional membranes in the module and the fluid can be obtained, so that an even more highly efficient separation and purification unit can be constructed.

The field of application is extremely wide. Applicable to all fields where functional membrane applications such as metal removal from wastewater by Donnan dialysis, water and ethanol separation by pervaporation, selective recovery of specific enzymes and proteins, or separation of optical isomers are tried. it can. The present invention will be described below with reference to examples.

[0023]

【Example】

[0024]

Example 1 First, a hollow fiber-shaped separation functional membrane was synthesized. A polyethylene tube was obtained by a known method.
That is, by heating and melting the low-density polyethylene pellets,
It was extruded at 150 ° C. to obtain a polyethylene tube having a film thickness of 10 μm and an inner diameter of 200 μm. The tube used as a base material was irradiated with 20 kGy of γ-ray and subsequently put into a liquid of acrylonitrile to carry out a graft polymerization reaction. The reaction temperature was 40 ° C. and the reaction time was 11 hours. The obtained membrane was repeatedly washed with N, N-dimethylformamide. After drying, the weight increase rate was measured to be 86%
Met. Subsequently, hydroxylamine hydrochloride 6
% Aqueous solution was neutralized with potassium hydroxide, and the obtained membrane was put into a solution mixed with an equal amount of methanol to convert the introduced cyano group into an amidoxime group. 80 reactions
It was carried out at ℃ for 8 hours. The conversion rate from the cyano group to the amidoxime group was calculated from the weight increase rate before and after the reaction.
It was 6%.

30 cm of the film obtained as described above is
3000 pieces were filled in a module having an inner diameter of 4 cm. The membrane adhered only one end at the bottom in the module. Polyurethane was used as the sponge-like structure. The polyurethane foam was produced by a known method called the prepolymer method. Table 1 shows the method for producing the prepolymer. 100 parts by weight of polypropylene glycol and 0.4 parts by weight of water were mixed and heated at 35 to 40 ° C. for 30 minutes. Tolylene diisocyanate was added so that the NCO (isocyanate group) / OH ratio was 1.25 and the NCO / H ₂ O ratio was 1.0.
The temperature was raised to 0 ° C., kept at 120 ° C. for 90 minutes, cooled to 80 ° C., tolylene diisocyanate was added again so that the NCO content became 9.5%, mixed well, and then 40 ° C.
Cooled to. It was subsequently compounded according to Table 2 and injected into the module. The injection amount was about 40 g. The polyurethane foamed inside the module and could fill the space inside the module. After the foam solidified, the foam was cut so that the upper end portion of the film was horizontal. The target module could be obtained by bonding the upper end of the membrane.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

Comparative Example 1 The membrane synthesized in Example 1 was filled in the same module as in Example 1 to form a module without introducing the sponge-like structure. Using the above two types of modules,
The following evaluation was performed. First, strength measurement was performed. Air pressure was applied to the inside of the hollow fiber membrane filled in the module. 0.
At 5 kg / cm ² , the film of Comparative Example 1 ruptured within 10 seconds, but the film of Example 1 did not break even after 5 kg / cm ² was continued for 1 hour.

Further, the separation and purification capacities were compared. The experimental apparatus is shown in FIG. 0.5N sulfuric acid was circulated inside the hollow fiber membrane, and a 0.02 mol / liter copper sulfate solution was supplied to the outside of the hollow fiber membrane at 100 ml / min. The pressure loss of the treatment liquid flowing through the outside of the hollow fiber membrane in the module was 0.05 kg / cm ² or less in all the modules. The flow rate inside the hollow fiber membrane was adjusted by adjusting valve 1 so that an internal pressure of 0.2 kg / cm ² was applied. The change in copper ion concentration in the treatment liquid after passing through the module was measured by an atomic absorption method. The result of Example 1 is shown in FIG. 3, and the result of Comparative Example 1 is shown in FIG. The vertical axis represents the ratio of the copper ion concentration in the treatment liquid to the copper ion concentration in the supply liquid. Regarding the copper ion concentration in the treatment liquid, in Comparative Example 1, a leak of 50% or more was observed from the initial stage, but in the module of Example 1, the copper ion concentration was maintained at 5% or less, and the sponge-like structure was observed. The effect of improving the contact efficiency by introducing the body was remarkably recognized.

[0030]

EFFECTS OF THE INVENTION Strength is imparted to a high-performance film having a thin film and excellent functions in terms of separation coefficient and permeation amount.
In addition, the present invention provides a module in which high contact efficiency is ensured, and makes it possible to scale up any high-performance membrane to a practical scale.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a hollow fiber membrane filling module filled with a sponge-like structure.

FIG. 2 is a diagram of an experimental device for performance evaluation of modules manufactured according to Example 1 and Comparative Example 1.

FIG. 3 is a graph showing the change with time of copper ions in the treatment liquid in Example 1.

FIG. 4 is a graph showing changes with time of copper ions in a treatment liquid in Comparative Example 1.

[Explanation of symbols] 1 adhesive 2 sponge-like structure 3 hollow fiber membrane 4 valve 1 5 pump 6 0.5N sulfuric acid

Claims (1)

[Claims] 1. A module having a housing filled with a hollow fiber membrane, wherein a space between the housing and the hollow fiber membrane is filled with a sponge-like structure mainly composed of an organic substance. A new module to do.