JPH105554A - Fluid separation element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage due to deformation of a separation membrane caused by the surface shape of a separation material flow path material under high pressure, and to prevent a decrease in the amount of permeate due to blockage of a groove of the separation material flow path material, and to prevent deformation. The life of the spiral-type fluid separation element is significantly increased by preventing the resulting membrane from being scratched and damaged by the projections of the separation membrane and the feed channel material. SOLUTION: A porous or water-permeable sheet material is provided between both surfaces of a separation material channel material and a separation membrane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral type fluid separation element using a liquid or gas separation membrane.
More specifically, the separation element generally relates to a spiral fluid separation element used for a reverse osmosis separation device, an ultrafiltration device, a precision filtration device, a gas separation device, or the like, and particularly when the separation element is used at a high pressure. In the improvement of durability.

[0002]

2. Description of the Related Art As a fluid separation element used in a fluid separation device such as a reverse osmosis separation device, a first separation membrane, a separation material flow path material, a second separation membrane, and a supply flow path material are provided on the outer periphery of a central pipe. There is a spiral fluid separation element formed by winding a single set or multiple sets of units. As the spiral type fluid separation element, those utilizing principles such as dialysis, ultrafiltration, and reverse osmosis are known. In particular, those used for seawater desalination and recovery of useful materials based on the principle of reverse osmotic pressure have higher durability than the others, due to the higher pressure applied to the undiluted solution (the liquid to be treated). There is a disadvantage that it is low.

[0003] Known fluid separation elements which remedy this drawback include: As disclosed in JP-A-54-31087, there is known a method of interposing a porous sheet-like material between a separation membrane 1 and a separation material channel material 2.

[0004]

As shown in FIG. 1, the surface of the separated material flow path member 2 has concave and convex grooves on both surfaces.
As shown in FIG. 5, one surface has uneven grooves and the other surface has small convex protrusions.

[0005] In the above method, when there are irregular grooves on both surfaces of the separation material channel material 2 between the separation membranes 1 and 3 and the separation material channel material 2, the separation into the separation material channel material 2 is performed as shown in FIG. 3. As a result of the membranes 1 and 3 being pressed at a high pressure, the separation membranes 1 and 3 are deformed into a shape along the grooves of the separation material channel member 2 and become distorted, thereby preventing the flow of the liquid permeating the separation membrane. The amount of the permeate is reduced, and when the deformation is further advanced, the water quality of the permeate is reduced by partially cracking or breaking. Also, as shown in FIG. 4, when a small convex protrusion is provided on the back surface of the separation material channel material 2, the separation membrane 3 is pressed at a high pressure on the back surface of the separation material flow material 2. Cracks or tears will reduce the water quality of the permeate. Furthermore, the supply flow path member 4 and these protruding portions can be used to start and stop the apparatus repeatedly,
In some cases, the membrane may be broken by rubbing due to the vibration of the water supply pump, and the water quality of the permeated liquid may be reduced. These phenomena cannot avoid the defect that progresses with time in high-pressure, long-time operation.

An object of the present invention is to solve the above-mentioned deficiencies of the prior art and to provide a fluid separation element capable of exhibiting high performance for a long time without damaging the separation membranes 1, 3.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is basically to provide "a water-permeable sheet is interposed between the flow path material and the separation membrane on both sides of the flow path material. Characterized in that the fluid separation element is characterized in that:

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 5 is a cross sectional view of a spiral type fluid separation element. The spiral type fluid separation element includes a central pipe 5, a separation membrane 1, a separation material flow path material 2, a separation membrane 3, and a supply flow path material 4, and a fluid adhesive is usually provided on the outer peripheral portion of the separation flow path material 2. Is applied and wound around the central tube 5.

In the present invention, as shown in FIGS. 6 and 7, between the first separation membrane 1 and the separation material channel material 2 and between the second separation membrane 3
Porous or water-permeable sheets 6 and 7 are interposed on both surfaces between the material and the separation material channel material 2. As a result, as shown in FIG. 6, when the separation membrane 3 has an uneven groove on both surfaces of the separation material channel material 2 between the separation film 3 and the separation material channel material 2, Even when pressed, the separation membranes 1 and 3 are not deformed into a shape along the grooves of the separation material flow path material 2 and do not become distorted, so that there is no resistance to the flow of the liquid permeating the separation membrane, In addition, partial cracks and tears do not occur. Further, as shown in FIG.
When the second separation membrane 3 is pressed at a high pressure against the separated material flow path material 2, the small projections are not cracked or broken when the back surface has small convex protrusions. Therefore, the water quality of the permeate is not reduced. Furthermore, a porous or water-permeable sheet-like material 6 is provided on both surfaces between the separation membranes 1 and 3 and the separation material channel material 2.
The presence of the protrusion 7 eliminates the protrusion, so that the feed flow path material 4 and the film of the protrusion are not broken by the repeated start and stop of the apparatus or by the vibration of the water supply pump. The water quality will not be reduced.

These effects are stably exhibited in high-pressure, long-time operation.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 6 to 8, but the present invention is not limited thereto.

A single or multiple units of a unit including the first separation membrane 1, the separation material flow path material 2, the second separation membrane 3, and the supply flow path material 4 are wound around the outer periphery of the central tube 5. In this spiral type fluid separation element, porous or water-permeable sheets 6 and 7 are temporarily fixed to both surfaces of the separated material channel material 2 using a double-sided tape 8 as shown in FIG.

Next, the temporarily fixed sheets 6 and 7 are coated with an adhesive 9 on the outer peripheral portion of the separated material channel member 2 to form the constituent members 1 and 2.
Around the center tube 5 together with 2, 3, and 4, the adhesive is cured.

FIG. 6 shows a porous or water-permeable sheet-like material 6 on both surfaces when there are concave and convex grooves on both surfaces of the separation material channel material 2.
FIG. 7 is a cross-sectional view in the case where a semiconductor device 7 is interposed. As is clear from FIG. 6, the permeate passed through the separation membranes 1 and 3 passes through the pores of the porous sheet or the water-permeable sheets 6 and 7 and further on both surfaces of the separation material channel member 2. At the center tube 5.

FIG. 7 shows a case where a porous or water-permeable sheet-like material 6, 7 is interposed on both surfaces when an uneven groove is formed on one surface of the separated material channel material 2 and a small convex protrusion is formed on the other surface. It is sectional drawing in the case of having made it. As is clear from FIG. 7, the permeated liquid that has passed through the separation membranes 1 and 3 passes through the pores of the porous sheet or the water-permeable sheets 6 and 7 and further to one side of the separation material channel member 2. At the center tube 5. When a reverse osmosis membrane is used for the separation membrane, a high pressure exceeding the osmotic pressure in the system is applied to the stock solution in order for the solvent to be separated from the feed solution through the reverse osmosis membrane, resulting in the reverse osmosis membrane 1, 3 is strongly pressed against the surfaces of the sheet-like materials 6 and 7 on both surfaces of the separated material channel material 2, respectively. The pressure may be, for example, 50 kg / cm ² or more when water is separated from seawater, or 100 kg / cm ² when recovering useful substances.

In the spiral type fluid separation element according to the present invention, as shown in FIGS. 6 and 7, the separation membranes 1 and 3 are first made of a porous or water-permeable sheet 6 made of a material having a flat and rigid surface. , 7 against the surface. Therefore,
Although the separation membranes 1 and 3 are compressed and deformed as a whole due to pressurization, the phenomenon that the separation membranes 1 and 3 are locally strongly deformed by grooves or small protrusions scattered on both surfaces of the separated material channel material 2 disappears.

Further, the sheets 6 and 7 are separated material passage material 2.
The groove 2 or the small convex protrusion is strongly pressed to deform it. However, the flow path material 2 is made of a fibrous material such as a tricot knitted fabric, and is reinforced by a melamine resin or a fusion process. Because it is rigid, it is designed to sufficiently withstand this external force.

Does the sheet-like material 6, 7 used in the present invention have such a rigidity that it is not deformed by the grooves or small protrusions in the separating material flow path member 2 even under the strong external force. The separators 1 and 3 are rigidly processed by a melamine resin or a fusion bonding process, and are designed so that the separation membranes 1 and 3 are not pushed into the small holes formed in the porous sheet and are embossed. A material that does not contain a substance that dissolves in the permeate or reacts with the permeate and has flexibility is preferable. Polyester, polyamide, polyacryl, polypropylene, polyethylene, polystyrene, polycarbonate, polyvinyl chloride
Sheet or non-woven fabric made of synthetic high molecular polymer such as cellulose, natural polymer sheet or non-woven fabric made of acetate or cellulose, and inorganic material such as thin metal plate or foil Sheets can be used effectively.

The diameter and density of the pores confined in the porous sheet are determined by the type of the separation membrane, the type and concentration of the supply liquid, and the shape of the groove or the small convex portion in the flow channel material 2 for the separation. Depending on the size, its diameter is 50-1000μ
m and the pitch can be appropriately selected in the range of 1 to 20 mm. However, considering the flow resistance of the permeated liquid, the pore size is 100 to 70.
0 μm and the pitch is preferably 5 to 10 mm. The thickness of the sheet varies depending on the material and other factors, but is 25 μm to 400 μm in consideration of the shape of the separation channel material 2, the rigidity and flexibility of the sheet, and the like.
Preferably, the thickness is about 70 μm to 150 μm.

In the present invention, a cloth can be used as the water-permeable sheet. Although the degree of water permeability of the fabric, that is, the water permeability is not particularly specified, the permeation coefficient of pure water at 25 ° C. is 0.5 m ³ / (m ² · MPa · min) or more, and the permeation resistance of the nonwoven fabric is reduced. This is preferable for reducing the size. More preferably, 0.8 m ³ / (m ² · MPa ·
min) or more.

Further, the present invention does not limit the thickness of the fibers used for the fabric at all, and any fabric having the above-mentioned water permeability and sufficient rigidity can be obtained as the fabric. Fiber may be used.

The surface of the water-permeable fabric of the present invention preferably has an average roughness Rz of 20 μm or less.
5 μm or less is more preferable. Here, the average surface roughness R
z is the average of the heights of the peaks from the highest to the fifth measured in the vertical direction from a straight line parallel to the average line of the cross-section and not crossing the cross-sectional curve, and It is obtained by calculating the difference between the value and the average value of the fifth valley bottom. Although there is no particular lower limit for the surface roughness, it is preferably 2 μm or more in consideration of resistance and manufacturing cost.

In order to obtain the above-mentioned surface roughness, in the present invention, the fabric may be subjected to calendering to make the surface smooth. The resulting damage to the reverse osmosis membrane can be reduced, and the durability can be improved. Although not particularly limited, as the conditions of the calendering treatment, for example, in the case of polyester fiber, preferably, the heating temperature is 50 to 150 ° C., and the weight per 1 m width is 20 to 8;
0t, and more preferably the heating temperature is 60 to 100.
The load per ° C and 1 m width is 40-60t. Of course, for fibers of materials other than polyester fiber,
The conditions of the calendering process may be appropriately changed according to the difference in physical properties such as the melting point and the elasticity.

In the present invention, the type of the fabric is not particularly limited, but any type of fabric having the above-described water permeability, surface smoothness and rigidity may be used. Further, it is preferable to use a water-permeable nonwoven fabric from the viewpoint that the above-mentioned characteristics can be easily obtained.

For nonwoven fabrics, generally several mm to several c
It is a structure in which short fibers with a length of about m are intricately entangled with each other. Depending on the density of the fibers and the degree of post-processing, there are no gaps between the fibers at all, and there is no liquid permeation. There are various types such as those having a large gap and allowing liquid to easily permeate, but in the present invention, in order to smoothly guide the liquid permeated through the reverse osmosis membrane to the groove of the woven or knitted fabric which is the flow path, the permeated liquid flow path is used. The non-woven fabric used for the material must have a liquid-permeable property, that is, it must have water permeability.

The non-woven fabric is classified into a non-oriented state in which the fiber has no orientation depending on the manufacturing method, a so-called non-oriented state, a fiber in which fibers are oriented in a certain direction, and an intermediate state between the two. It is preferable to use one in which the fibers are oriented in a certain direction.

Further, it is preferable that, when the nonwoven fabric in which the fibers are oriented in a certain direction is arranged on the surface of the woven or knitted fabric, the orientation direction of the fibers is orthogonal to the direction of the groove of the woven or knitted fabric.

This is because if the fibers of the nonwoven fabric are oriented in a certain direction, anisotropy occurs in the strength and rigidity of the nonwoven fabric, and a deformation parallel to the orientation direction of the fibers against deformation such as bending and bending. Because the vertical direction is stronger than the vertical direction, by making the groove direction of the woven or knitted fabric orthogonal to the orientation direction of the fibers of the nonwoven fabric,
This is because deformation of the nonwoven fabric under high pressure and falling into the groove of the woven or knitted fabric can be suppressed.

[0030] The permeated liquid channel material used in the present invention is not particularly limited, but a preferred example is a structure having grooves parallel to each other on both surfaces. At this time, the directions of the grooves on both surfaces of the structure are preferably parallel to each other. If the directions of the grooves on both surfaces are provided so as to be orthogonal to each other, the direction of the grooves on either side is parallel to the longitudinal direction of the central pipe, so that the permeate cannot be smoothly guided to the water collecting holes of the central pipe, The flow resistance becomes extremely large and the performance deteriorates.

As for the positions of the grooves on both surfaces of the permeated liquid flow path material, the same positions are provided on both sides, but the deformation of the flow path material itself under high pressure is reduced, and the increase in flow resistance is suppressed. Is preferred in that Although not particularly limited,
The deviation of the center position of the grooves on both sides is preferably 40 μm or less,
More preferably, it is 20 μm or less.

The width of the groove of the permeated liquid channel material is set at 100 to prevent the reverse osmosis membrane from falling into the groove under high pressure.
The thickness is preferably in the range of 200 to 200 μm. More preferably, it is in the range of 100 to 150 μm. This is because a reverse osmosis membrane used for a liquid separation element usually has a thickness of about 200 to 300 μm.
m, but the width of the groove is substantially equal to or smaller than the thickness of the reverse osmosis membrane, thereby substantially preventing the reverse osmosis membrane from falling into the groove of the permeated liquid flow path material. Because you can do it. Considering the lower limit of the groove width from the viewpoint of suppressing the fall of the reverse osmosis membrane into the groove, 1
A thickness of at least 00 μm is sufficient, while a thickness of at most 100 μm is not preferred because it only increases the flow resistance of the permeate.

As for the depth of the groove of the permeate flow path material, the flow path of the permeate becomes smaller when the depth of the groove is 50 μm or less, and the flow resistance is increased even by slight deformation of the reverse osmosis membrane under high pressure. May change. On the other hand, when the thickness is 200 μm or more, the thickness of the permeate flow path material becomes large, and the area of the packed membrane of the reverse osmosis membrane when incorporated in the liquid separation element becomes small. In addition, the thickness is preferably in the range of 50 to 200 μm so that the flow resistance of the permeate is small. More preferably, it is in the range of 80 to 150 mm.

Further, as described above, the flow resistance of the permeate flow path material changes depending on the groove density, that is, the number of grooves per unit length. Is preferably in the range of 45 to 70 grooves per inch. More preferably, the number is 50 to 60 per inch. Groove density 45 per inch
Below this, the number of flow paths is small, so that the overall flow path area is reduced and the flow resistance is increased. Further, the upper limit of the groove density is desirable to reduce the flow resistance, but when the groove density is substantially 70 or more per inch, the flow path material for supporting the reverse osmosis membrane under high pressure is preferably used. Since the width of the convex portion is reduced and the area of the portion receiving the pressure is reduced, the flow path material itself is deformed. for that reason,
There is a risk that the depth of the groove becomes smaller and the flow resistance increases.

The structure of the permeate flow channel material in the present invention may be any structure having the above-mentioned structural characteristics, and the type of the structure is not particularly limited. It is preferable to use a double tricot in that the structural characteristics of the above can be realized at high quality and at low cost. In addition, for the double tricot, for example, double half, double denbi, Queen's cord, three-piece, etc., depending on the difference in knitting organization, there are various types, but secure the flow path of the permeate, and even under high pressure Any material that is not easily deformed may be used, and is not particularly limited.

The fiber material of the woven or knitted fabric may be any material as long as it retains the shape of the channel material and has a small amount of components eluted into the permeate. Fiber, polyester fiber, polyacrylonitrile fiber, polyolefin fiber such as polyethylene and polypropylene, polyvinyl chloride fiber,
Polyvinylidene chloride-based fibers, polyfluoroethylene-based fibers, carbon fibers, and the like can be mentioned.In particular, in consideration of the strength that can withstand high pressure and the ease of processing of a woven or knitted fabric described later, polyester fibers are used. Is preferred.

Also in the present invention, it is preferable to carry out a hardening treatment for increasing the rigidity of the woven or knitted fabric in order to suppress deformation of the flow path material itself under high pressure. Examples of the curing method include a method of impregnating a woven or knitted product with a resin such as melamine or epoxy, or a method of applying a heat fusion process of fusing and solidifying fibers to each other by heating the woven or knitted material. ,
In the present invention, any method can be used as long as it is a processing method capable of obtaining a hardness such that the channel material itself is not deformed under high pressure.

Further, in the present invention, when the convex portion of the woven or knitted fabric of the permeated liquid channel material is not flat, in order to prevent local or non-uniform deformation of the reverse osmosis membrane under high pressure, Preferably, the woven or knitted material of the permeate flow path material is calendered. Although not particularly limited, as the conditions of the calendering treatment, for example, in the case of polyester fiber, preferably, the heating temperature is 50 to 150 ° C. and the width is 1
The weight per m is 20 to 80 t, more preferably the heating temperature is 60 to 100 ° C., and the weight per 1 m width is 40 to 60 t. Needless to say, with respect to fibers of a material other than the polyester fiber, the conditions of the calendering treatment may be appropriately changed according to the difference in physical properties such as the melting point and elasticity. By performing the calendering process, the surface of the woven or knitted fabric is crushed with fine undulations due to the shape of the fiber, and the convex portions become very smooth and flat. For this reason, when calendering is performed with respect to the case where calendering is not performed, the contact area between the reverse osmosis membrane and the convex portion of the flow path material increases, and the entire surface comes into uniform contact, The reverse osmosis membrane receives less damage under high pressure, and as a result,
The decrease in performance such as the rejection rate and the concentration rate is reduced, and the durability is improved.

A feature of the present invention resides in an improved permeate flow path material, and is a member of a liquid separation element other than the permeate flow path material, that is, a hollow central tube having a hole on its surface, a semi-circular tube, The permeable membrane and the supply liquid channel material are not specified at all. Therefore, for these members, for example, conventional members can be used as they are.

The use conditions are not particularly limited. However, as described above, the effects of the present invention can be excellently exerted particularly under high pressure conditions. The pressure applied is preferably 5 to
15 MPa, more preferably 7 to 12 MPa. Suitable application fields include desalination by reverse osmosis of 0.5% or more of salt water, particularly seawater.
This is suitable when the high-pressure concentrated water is further subjected to reverse osmosis membrane treatment.

[0041]

【Example】

Example 1 Polyester fibers are knitted in a double denbi structure, and one surface has a groove width of 150 μm, a groove depth of 150 μm, a groove density of 40 per inch, and the other surface has a height of 50 μm and a pitch of 47 μm. A channel material having a thickness of 270 μm was produced.

As the water-permeable sheet, a 50 μm-thick polyester sheet in which small holes having a diameter of 100 μm were perforated at intervals of 10 mm was used and laid on both sides of the flow path material.

Each of these was incorporated between two reverse osmosis membranes, and a polypropylene net was incorporated outside the reverse osmosis membrane as a feed liquid flow path material (FIG. 7).
Wrap around the center pipe made of RP, 2 inches of outer diameter 4 inches
Liquid separation elements of various types were obtained. (FIGS. 5 and 8) These were loaded into a pressure vessel of a liquid separation apparatus, and a separation experiment was performed using a saline solution as a supply liquid. As the experiment conditions, the salt concentration of the supply liquid was 3.5%, the operation pressure was 5.6 MPa, the supply liquid flow rate was 20 liters / min, and the liquid temperature was 25 ° C., and the operation was continued for 100 hours. No abnormalities were observed in the water permeability.

Example 2 The same flow path material as in Example 1 had a thickness of 100
μm, the basis weight is 86.9 g / m ² , and the permeability of pure water at 25 ° C. is 0.8 m ³ / (m ² · MPa · mi.
n) laying a water-permeable non-woven fabric made of polyester staple fiber to form a liquid separation element in the same manner as in the example,
As a result of the evaluation, no abnormality was recognized in the exclusion rate or the water permeability.

[0045]

As described above, the spiral fluid separation element of the present invention has a high flexibility between both surfaces of the separation channel material 2 having grooves or small projections on its surface and the separation membranes 1 and 3, In addition, by interposing the porous or water-permeable sheets 6 and 7 having a flat surface and high rigidity, deformation at the high pressure due to the separation material flow path material or rubbing between the projecting portion generated as a result of the deformation and the feed flow path material. It is intended to prevent a reduction in the amount of permeate due to breakage of the separation membrane and blockage of the groove in the concave portion of the separation material flow path material, and to significantly increase the life of the spiral type fluid separation element.

The fluid separation element according to the present invention can be applied to all liquid and gas separation devices having a structure using a flow path material such as a tuber type, other than the spiral type shown in the embodiment. Its field of application is extremely wide.

Even when a single composite membrane and a membrane having a laminated composite structure reinforced with a plain woven fabric are used, the same effect as described above can be obtained with the apparatus according to the present invention.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a separation material channel material 2 having grooves on both surfaces.

FIG. 2 is a cross-sectional view of the separated material channel material 2 having a groove on one surface and small convex protrusions on the other surface.

FIG. 3 is an explanatory view showing deformation of a separation membrane under high pressure and occurrence of membrane breakage due to rubbing in a separation material flow path material having grooves on both surfaces.

FIG. 4 is an illustration of a separation channel material having a groove on one surface and small convex protrusions on the other surface, showing the conventional occurrence of membrane breakage due to deformation and rubbing of the separation membrane under high pressure. FIG.

FIG. 5 is a sectional view of a spiral type fluid separation element.

FIG. 6 is an example in which the present invention is applied to a separated material channel material having grooves on both surfaces.

FIG. 7 is an example in which the present invention is used for a separation channel material having a groove on one surface and small convex protrusions on the other surface.

FIG. 8 is a development view of a spiral fluid separation element.

[Explanation of symbols]

 1: First separation membrane 2: Separator flow path material 3: Second separation membrane 4: Feed flow path material 5: Central tube having holes 6: Porous or water-permeable sheet 7: Porous or Water permeable sheet 8: Double-sided tape 9: Adhesive

Claims (9)

[Claims] 1. A fluid separation element wherein a water-permeable sheet is interposed between a flow path member and a separation membrane on both surfaces of the flow path member. 2. The fluid separation element according to claim 1, wherein the water-permeable sheet is a porous sheet. 3. The fluid separation element according to claim 1, wherein the water-permeable sheet is a sheet made of a synthetic polymer, a natural polymer, or an inorganic material. 4. A sheet-like material having a large number of small holes having a diameter of 50 μm to 1000 μm and a pitch of 1 mm to 20 mm as said porous sheet-like material according to claim 2. 2. The fluid separation element according to 1. 5. The fluid separation element according to claim 1, wherein a nonwoven fabric is used for the water-permeable sheet. 6. The nonwoven fabric according to claim 4, which has a water permeability of 0.1.
^2. The fluid separation element according to claim 1, wherein the flow rate is 3 m ³ / m ² · MPa · min or more. 7. The fluid separation element according to claim 1, wherein the thickness of the porous or water-permeable sheet is 50 μm to 400 μm. 8. The fluid separation element according to claim 1, wherein the fluid separation element is used at a pressure of 50 kg / cm ² or more. 9. A spiral type in which a single set or a plurality of sets of a unit having a first separation membrane, a separation material flow path material, a second separation membrane, and a supply flow path material as one set are wound around the outer periphery of the central pipe. In the fluid separation element, an uneven groove is provided on a surface of the separated material flow path material, and a flow path material having an uneven groove or a small convex protrusion is provided on a back surface, and further, the first separation membrane and the separated material flow path are provided. A spiral fluid separation element comprising a porous or water-permeable sheet-like material interposed on both surfaces between the material and between the second separation membrane and the separated material channel material.