JPWO2019189548A1 - Method for producing a solution with reduced solute concentration - Google Patents

Abstract

The solution FS is supplied to the region on one surface side of the normal osmotic film including the semitransparent film and the porous substrate arranged on at least one surface thereof, and the solute from the solution FS is supplied to the region on the other surface side. A method for producing a solution in which the solute concentration of the solution DS is lowered by supplying a high-concentration solution DS and moving the solvent contained in the solution FS to the solution DS through the normal osmotic membrane. A method in which the supply pressure P1 of the solution FS and the supply pressure P2 of the solution DS satisfy the formula: 0.5 kPa ≦ P1-P2 ≦ 700 kPa.

Description

The present invention relates to a solution treatment method using a forward osmosis membrane. More specifically, the present invention relates to a method for producing a solution having a reduced solute concentration by moving a solvent contained in a low solute concentration solution to a high solute concentration solution using a forward osmosis membrane.

Semipermeable membranes are useful for selectively separating certain components from liquid or gas mixtures, and are preferably used, for example, in the production of high-purity water or in the separation of specific solutes from a solution.

Of the reverse osmosis method and the forward osmosis method, which are membrane separation methods using a semipermeable membrane, the reverse osmosis membrane is exposed to high pressure in the conventional mainstream reverse osmosis method. Therefore, the reverse osmosis membrane includes a porous support (for example, a non-woven fabric), a porous polymer layer (for example, a polysulfone layer), and a layer (skin layer, a separation layer) that actually functions as a semipermeable membrane in order to obtain high strength. , Etc.) are laminated in this order, and a composite semipermeable membrane is the mainstream.

On the other hand, in the forward osmosis method, the osmotic pressure generated between the solvents having different solute concentrations separated by the forward osmosis membrane is used as a driving force to move from the low solute concentration side (for example, fresh water) to the high solute concentration side (for example, seawater). And the solvent (eg water) move. Therefore, unlike the reverse osmosis method, it is not necessary to apply a high pressure or film strength to overcome the osmotic pressure, and it is expected to have advantages such as excellent energy saving and a simple structure of the osmotic membrane.

However, the forward osmosis method has a problem that the permeation flux is small (for example, Patent Document 1), and low solute is used when treating a large amount of water such as for agricultural water and water purification using a forward osmosis membrane. Further improvement of the permeation flux from the concentration side to the high solute concentration side is required.

Japanese Unexamined Patent Publication No. 2014-21262

One aspect of the present invention is to obtain a higher permeation flux of the solvent when moving the solvent contained in the low solute concentration solution to the high solute concentration solution through the forward osmosis membrane. Further, in the present invention, it is also one aspect to reduce the back diffusion of the salt.

The forward osmosis membrane technology uses the osmotic pressure generated between a low-solute concentration solution and a high-solute concentration solution for treatment, but studies have also been made to further apply external pressure.

However, in the prior art, it is necessary to apply a pressure difference of more than 1 MPa between the low solute concentration solution and the high solute concentration solution, and the merit of low energy cost inherent in the forward osmosis membrane is impaired.

According to the study by the present inventors, when a slight pressure difference of 700 kPa or less is applied between the low solute concentration solution and the high solute concentration solution, only the osmotic pressure generated between the solutions is used as the driving force. In comparison, it was found that a dramatically higher osmotic flux can be obtained.

That is, the present invention relates to the following [1] to [5].

[1] A solution FS is supplied to a region on one surface side of a normal permeable membrane including a semitransparent film and a porous substrate arranged on at least one surface thereof, and the solution is supplied to a region on the other surface side. A method for producing a solution in which the solute concentration of the solution DS is lowered by supplying a solution DS having a higher solute concentration than the FS and moving the solvent contained in the solution FS to the solution DS through the normal osmotic membrane. Yes, the supply pressure P1 of the solution FS and the supply pressure P2 of the solution DS are of the formula: 0.5 kPa ≦ P1-P2 ≦ 700 kPa.
How to meet.

[2] The method according to the above [1], wherein the forward osmosis membrane further includes a mesh-like support base material between the semipermeable membrane and the porous base material.

[3] The method according to the above [1] or [2], wherein the thickness of the semipermeable membrane is 3.0 μm or less.

[4] The semipermeable membrane comprises a protonic acid group-containing aromatic polyether resin containing a structural unit (1) represented by the following formula (1) and a structural unit (2) represented by the following formula (2). ^{Containing, the porous substrate has a breathability of 100-400 cm 3} / cm ² / s and a thickness of 50-700 μm as measured by method A (Frazier form) as described in JIS L 1096. The method according to any one of the above [1] to [3].

［式（１）および（２）において、
Ｒ¹〜Ｒ¹⁰は、それぞれ独立して、Ｈ、Ｃｌ、Ｆ、ＣＦ₃またはＣ_mＨ_2m+1（ｍは１〜１０の整数を示す。）であり、
Ｒ¹〜Ｒ¹⁰の少なくとも１つはＣ_mＨ_2m+1（ｍは１〜１０の整数を示す。）であり、
Ｒ¹〜Ｒ¹⁰は、それぞれ芳香環に２つ以上存在してもよく、１つの芳香環にＣ_mＨ_2m+1が２つ以上存在する場合には、各Ｃ_mＨ_2m+1は互いに同一であっても異なっていてもよい。

[In equations (1) and (2)
R ^{1 to} R ¹⁰ are independently H, Cl, F, CF ₃ or C _m H _{2m + 1} (m indicates an integer of 1 to 10).
At least one of ^{R 1 to} R ¹⁰ _{is C m} H _{2m + 1} (m indicates an integer of 1 to 10).
Two or more of R ^{1 to} R ¹⁰ may be present in each aromatic ring, and when two or more C _m H _{2 m + 1} are present in one _{aromatic ring, each C m} H _{2 m + 1} is present with each other. It may be the same or different.

X ^{1 to} X ⁵ are independently H, Cl, F, CF ₃ or protonic acid groups, respectively.
At ^{least one of X 1 to} X ⁵ is a protonic acid group and
Two or more of X ^{1 to} X ⁵ may be present in each aromatic ring, and when two or more protonic acid groups are present in one aromatic ring, the protonic acid groups are different even if they are the same as each other. May be.

A ^{1 to} A ⁶ are independently directly bonded, −CH ₂ −, −C (CH ₃ ) ₂₋ , −C (CF ₃ ) ₂₋ , −O− or −CO−, respectively.

i, j, k and l independently represent 0 or 1, respectively. ]
[5] Any of the above [1] to [4], wherein both the solution FS and the solution DS are aqueous solutions containing a salt, and the salt concentration of the solution DS is higher than the salt concentration of the solution FS. The method according to item 1.

According to the present invention, by applying a slight pressure difference of 700 kPa or less between a low solute concentration solution and a high solute concentration solution, a leap compared to the case where only the osmotic pressure generated between the solutions is used as the driving force. It was found that a particularly high osmotic flux was obtained.

FIG. 1 is a schematic view illustrating an embodiment of the manufacturing method of the present invention.

Hereinafter, the present invention will be specifically described.

In the present invention, the solution FS is formed in a region on one surface side of a forward osmosis membrane (hereinafter, also referred to as “first region”) including a semipermeable membrane and a porous substrate arranged on at least one surface thereof. Is supplied, a solution DS having a higher solute concentration than the solution FS is supplied to the other surface side region (hereinafter, also referred to as “second region”), and the solvent contained in the solution FS is used as the forward osmosis membrane. It is a method of producing a solution in which the solute concentration of the solution DS is lowered by moving the solution DS through the solution DS.
The supply pressure P1 of the solution FS and the supply pressure P2 of the solution DS are
Formula: 0.5 kPa ≤ P1-P2 ≤ 700 kPa
The P1-P2 preferably satisfies 1.0 kPa ≦ P1-P2 ≦ 200 kPa. A more preferable lower limit value of P1-P2 is 1.5 kPa. On the other hand, the more preferable upper limit value of P1-P2 is 100 kPa, and more preferably 50 kPa.

In the present invention, by setting the supply pressure P1 of the solution FS higher than the supply pressure P2 of the solution DS so as to have the above pressure difference, a large permeation flux can be obtained in the forward osmosis method. Further, according to the studies by the present inventors, it has been found that the semipermeable membrane showing a high permeation flux tends not to have a low backdiffusion of salt. In the present invention, there is a tendency that the backdiffusion of this salt can also be reduced. That is, in the present invention, the amount of backdiffusion of the solute contained in the solution DS into the solution FS with respect to the permeated flux can be greatly reduced. In the present invention, the effect can be obtained by applying, for example, a pressure difference of about 3 orders of magnitude smaller than the pressure applied by the usual reverse osmosis method to the solution.

The supply pressures P1 and P2 can be measured by a pressure gauge provided in the flow path. These supply pressures can be adjusted, for example, by the pressure applied by the liquid feed pump of each solution and / or by the opening degree adjusting valve that adjusts the flow rate of each solution.

In the present specification, the solution FS is also referred to as "feed solution" or abbreviated as "FS", and the solution DS is also referred to as "draw solution" or abbreviated as "DS". The solute concentration of the solution DS is higher than the solute concentration of the solution FS. According to the production method of the present invention, the solute concentration of the solution DS can be reduced.

The liquid temperatures of the solution FS and the solution DS are not particularly limited, but are, for example, normal temperature.

The solvent in the solution FS and the solution DS is not particularly limited as long as it is a liquid that permeates the forward osmosis membrane, and examples thereof include water, alcohols, and hydrocarbons, and water is preferable. Therefore, the solution FS and the solution DS are preferably aqueous solutions.

The solution FS is not particularly limited as long as it is a solution having a solute concentration and therefore a lower osmotic pressure than the solution DS. For example, purified water, drinkable water, river water, groundwater, agricultural water, etc. Examples include fresh water, domestic wastewater, industrial wastewater, groundwater, brackish water, and seawater.

The solution DS is not particularly limited as long as it is a solution having a solute concentration and therefore a higher osmotic pressure than the solution FS, and the solute is not particularly limited. Solution DS can be prepared using a solute that is sufficiently soluble. Examples of the solute include water-soluble salts such as sodium chloride, potassium chloride, calcium chloride, sodium sulfate, magnesium sulfate, ammonium chloride, ammonium sulfate, and ammonium carbonate; methanol, ethanol, 1-propanol, 2-propanol, and the like. Alcohols; glycols such as ethylene glycol and propylene glycol; ketones such as acetone and methyl ethyl ketone; polymers such as polyethylene oxide and propylene oxide are mentioned, and among these, salts are preferable. Examples of solution DS include seawater, concentrated seawater produced by reverse osmosis, fertilizer solutions, and solutions made with solutes that are sufficiently soluble to achieve high osmotic pressure. ..

Both the solution FS and the solution DS are aqueous solutions containing a salt, and it is preferable that the salt concentration of the solution DS is higher than the salt concentration of the solution FS.

According to the method of the present invention, a solution having a reduced solute concentration can be efficiently obtained. The method of the present invention is suitably used for, for example, desalination of seawater, wastewater treatment, treatment of accompanying water in oil / gas excavation, power generation using two liquids having different osmotic pressures, dilution of sugars and fertilizers, and the like. Can be done.

The forward osmosis membrane used in the present invention is preferably housed in a container, that is, it is preferable to use a forward osmosis membrane module in which the forward osmosis membrane is housed in a container. The inside of the container is divided into the above-mentioned first region and the second region by the forward osmosis membrane. The solution FS is supplied from the tank of the solution FS to the first region, and the solution DS is supplied from the tank of the solution DS to the second region. In the forward osmosis membrane module, the solution FS and the solution DS come into contact with both sides of the forward osmosis membrane, and the solution contained in the solution FS moves from the solution FS to the solution DS through the forward osmosis membrane. The transferred solvent dilutes the solution DS flowing through the second region.

The solution FS and the solution DS are supplied to the first region and the second region, respectively, across the forward osmosis membrane, but the supply directions of these solutions may be the same or opposite to each other. However, it is preferable that the direction is opposite, that is, cross flow. FIG. 1, which will be described later, is an example of cross flow.

Hereinafter, a liquid feeding system preferably used in the method of the present invention will be described.

The liquid feeding system is for flowing FS from the FS tank, the DS tank, the forward osmosis membrane module having the first region, the forward osmosis membrane and the second region, and the FS tank to the first region. with the a flow path _FS, a flow path _DS for supplying a DS from the tank of the DS in the second region.

The liquid feed system may be a circulation passage _FS for returning the FS to the tank of the FS from the first region, and a circulation channel _DS for returning the DS to the tank of the DS from the second region.

The liquid feeding system has a bypass flow path _{FS branched from the flow path FS} for returning the FS to the FS tank without passing through the forward osmosis membrane module, and a DS tank without passing the DS through the forward osmosis membrane module. It is possible to have a bypass flow path _{DS branched from the flow path DS} for returning to.

In one embodiment, the liquid feeding system includes a liquid feeding pump for flowing FS in a first region and a liquid feeding pump for flowing DS in a second region. The supply pressures P1 and P2 can be adjusted by a liquid feed pump (hereinafter, also referred to as “pump”). The pump can be provided, for example, in the middle of the _{flow path FS} and the flow path _{DS, respectively.}

The liquid feeding system, in the middle of the flow path _FS, it can have a degree of opening adjustment valve for adjusting the FS flow to the first region, in the middle of the channel _DS, DS to the second region It can have an opening adjustment valve that adjusts the flow rate. The supply pressures P1 and P2 can be adjusted by the opening degree adjusting valve. The opening degree adjusting valve can be provided, for example, on the flow path between each pump and the first and second regions.

The liquid feeding system may have an opening adjustment valve for adjusting the flow rate of returning the FS to the tank of the _{FS in} the middle of the bypass flow path FS, and DS to the tank of the _{DS in the middle of the bypass flow path DS.} It can have an opening adjustment valve that adjusts the flow rate to return. The supply pressures P1 and P2 can be adjusted by the opening degree adjusting valve.

FIG. 1 shows an embodiment of a liquid feeding system preferably used in the present invention.

The FS tank 1 is connected to the forward osmosis membrane module 21 by a flow path 2 such as a pipe, specifically to the inlet of the first region, and a pump 3 is provided in the middle of the flow path 2.

The forward osmosis membrane module 21 has a forward osmosis membrane 22.

The forward osmosis membrane module 21, specifically, the first region outlet is connected to the FS tank 1 by a circulation flow path 2-1 such as a pipe. Further, from the flow path 2, a bypass flow path 2-2 for returning the FS to the tank 1 branches and is connected to the circulation flow path 2-1.

An opening adjustment valve B1 for adjusting the FS flow rate to the forward osmosis membrane module 21 is provided on the flow path 2, and an opening adjustment valve B1 for adjusting the FS flow rate to the bypass flow path side is provided in the bypass flow path 2-2. A valve B2 is provided.

A pressure gauge, various valves, and the like may be arranged in the middle of each flow path.

The FS is sent to the forward osmosis membrane module 21 by using the pump 3. For example, the pressure setting by the pump 3, the opening degree of the opening degree adjusting valve B1 and the opening degree of the opening degree adjusting valve B2 are appropriately adjusted. Thereby, the supply pressure P1 and the flow rate can be adjusted to the set values.

The DS can also use the same device as the liquid feeding method of the FS, and can appropriately adjust the supply pressure P2 and the flow rate to the set values.

For example, the flow rates of FS and DS are 0.6 L / min, respectively, the supply pressure P1 of FS is 28 kPa, the supply pressure P2 of DS is 24 kPa, and the differential pressure of P1-P2 = 4 kPa is applied to operate. Let me.

[Forward osmosis membrane]
Hereinafter, preferred embodiments of the forward osmosis membrane used in the present invention will be described.

In the present invention, a forward osmotic membrane including a semipermeable membrane and a porous base material arranged on at least one surface thereof is used, and a mesh-like support is provided between the semipermeable membrane and the porous base material. A forward osmotic membrane further comprising a substrate is preferred. Further, it is preferable to use a forward osmosis membrane module in which the forward osmosis membrane is housed in a container. As the container, a conventionally known container used for the forward osmosis membrane module can be used.

The forward osmotic membrane comprises the semipermeable membrane and preferably the porous substrate disposed on at least one surface thereof, and has a high permeation rate while maintaining a high filtration function and a salt blocking rate. Performance can be achieved.

The forward osmosis membrane may include the porous substrate on both sides of the semipermeable membrane. In this embodiment, the strength of the forward osmosis membrane is further improved.

The forward osmosis membrane may include layers other than the porous substrate on both sides or one side of the semipermeable membrane in the order of the semipermeable membrane / the layer other than the porous substrate / the porous substrate. .. A polyamide layer may be included as a layer other than the porous substrate, but the thickness thereof is preferably 100 μm or less.

<Semipermeable membrane>
The semipermeable membrane is not particularly limited, but is preferably a membrane containing a material capable of forming a self-supporting membrane. As the reason for this, the present inventors consider the following hypothesis.

The semipermeable membrane used in the present invention is exposed to a certain amount of pressure as described above. Therefore, depending on the material, deformation or structural transformation may occur at the micro level. If the material is capable of forming a self-supporting film, the above-mentioned deformation and structural transformation are suppressed, so that it is considered that the material can more easily exhibit the effects of the present invention. Alternatively, the above-mentioned pressure may cause a slight conversion to a structure preferable for water permeation, and may exhibit the effect of suppressing the water permeation flux and the back diffusion of salts, which is the object of the present invention.

Further, the semipermeable membrane may preferably contain a plurality of types of polymers. In particular, it is preferable to contain polymers having different contents of hydrophilic groups such as sulfonic acid groups. With such a combination of polymers, a large number of phase-separated structures derived from a plurality of polymers are expressed, and the structure between the phases improves the water permeation flux (effect of sites with many hydrophilic groups) and salts. It is possible that the suppression of reverse diffusion (effect of the site with few hydrophilic groups) shows specific behavior.

The semipermeable membrane preferably contains a protonic acid group-containing aromatic polyether resin. A semipermeable membrane using the aromatic polyether resin as a raw material can be produced as a self-supporting membrane, and by laminating this semipermeable membrane and a porous base material, water permeability is high and the salt blocking rate is high. A forward osmotic membrane can be obtained.

The semipermeable membrane is substantially composed of the protonic acid group-containing aromatic polyether resin, but a small amount (for example, 1% by mass or less, or 0.1) of other components is not impaired in the effect of the present invention. May contain (% by mass or less).

The thickness of the semipermeable membrane is usually 3.0 μm or less, preferably 0.01 to 3.0 μm, and more preferably 0.01 to 1.5 μm. A forward osmotic membrane using a semipermeable membrane whose thickness is within this range has sufficient membrane strength and exhibits a practically sufficiently large permeation flux of water. As described above, even if the supply pressure difference is as low as 700 kPa or less for P1-P2, a high permeation flux can be obtained with such a film thickness. The thickness of the semipermeable membrane can be controlled by the manufacturing conditions of the semipermeable membrane, for example, the temperature and pressure during press molding, the varnish concentration during casting, the coating thickness, and the like. The thickness of the semipermeable membrane does not include the thickness of the porous substrate.

(Aromatic polyether resin containing protonic acid group)
The protonic acid group-containing aromatic polyether resin preferably contains a structural unit represented by the following formula (1) and a structural unit (2) represented by the following formula (2).

式（１）および（２）において、
ｉ，ｊ，ｋおよびｌは、それぞれ独立して、０または１を示す。

In equations (1) and (2)
i, j, k and l independently represent 0 or 1, respectively.

R ^{1 to} R ¹⁰ are independently H, Cl, F, CF ₃ or C _m H _{2 m + 1} (m indicates an integer of 1 to 10), and C _m H 2 m + 1 is used as _{C m H 2 m + 1.} For example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group can be mentioned.

At least one of ^{R 1 to} R ¹⁰ _{is C m} H _{2m + 1} (m indicates an integer of 1 to 10). Specifically, i, j, k and l and R ^{1 to} R ¹⁰ contain at least a group in which the structural unit (1) and / or the structural unit (2) is _{represented by C m} H _{2 m + 1.} Selected to have one. That is, when i, j, k and l are all 1, at least one of ^{R 1 to} R ¹⁰ _{is C m} H _{2 m + 1} , but for example i = 0, j = 1, k = 0 and l. When = 1, at least one of ^{R 1 to} R ³ , R ^{5 to} R ⁸ and R ¹⁰ _{is C m} H _{2 m + 1} .

Two or more of R ^{1 to} R ¹⁰ may be present in each aromatic ring, and when two or more C _m H _{2 m + 1} are present in one _{aromatic ring, each C m} H _{2 m + 1} is present with each other. It may be the same or different.

X ^{1 to} X ⁵ are independently H, Cl, F, CF ₃ or protonic acid groups.

At ^{least one of X 1 to} X ⁵ is a protonic acid group. Specifically, i and j and X ^{1 to} X ⁵ are selected such that the structural unit (1) has at least one protonic acid group. That is, when i = 1 and j = 1, ^{at least one of X 1 to} X ⁵ is a protonic acid group, but when j = 0 ^{, at least one of X 1 to} X ³ is a protonic acid group. , I = 0 and j = 1 ^{, at least one of X 1 to} X ³ and X ⁵ is a protonic acid group.

Two or more of X ^{1 to} X ⁵ may be present in each aromatic ring, and when two or more protonic acid groups are present in one aromatic ring, the protonic acid groups are different even if they are the same as each other. May be.

A ^{1 to} A ⁶ are independently directly bonded, −CH ₂ −, −C (CH ₃ ) ₂ −, −C (CF ₃ ) ₂ −, −O− or −CO−, and A ¹ At least one of ~ A ⁶ is preferably −CO−.

The lines at both ends of equations (1) and (2) indicate the connection with adjacent structural units.

In the present invention, the protonic acid group means a functional group that easily releases a proton or a hydrogen atom thereof substituted with Na or K, and examples thereof include a sulfonic acid group (-SO ₃ H) and a carboxylic acid. Acid group (-COOH), phosphonic acid group (-PO ₃ H ₂ ), alkyl sulfonic acid group (-(CH ₂ ) _n SO ₃ H), alkyl carboxylic acid group (-(CH ₂ ) _n COOH), alkyl phosphon Examples thereof include an acid group (-(CH ₂ ) _n PO ₃ H ₂ ), a hydroxyphenyl group (-C ₆ H ₄ OH) and those in which the terminal hydrogen atom thereof is substituted with Na or K. n is an integer of 1-10. Examples of the protonic acid _{group, -C n 'H 2n' -SO} 3 Y (n ' is an integer of 0, preferably 0, Y is H, Na or K) are preferred.

Examples of the structural unit (1) include structural units represented by the following equation (1-1) or the following equation (1-2), and in these structures, A ¹ is −CO−. Is preferable

さらに具体的には下式（１−３）または下式（１−４）で表される構造単位が挙げられる。

More specifically, structural units represented by the following equation (1-3) or the following equation (1-4) can be mentioned.

（式中、Ｚはそれぞれ独立に前記プロトン酸基であり、ｓはそれぞれ独立に０〜３の整数であり、ｔはそれぞれ独立に０〜４の整数であり、両末端の線は隣り合う構造単位との結合を示す。これら以外の記号の定義は前述したとおりである。）
また、構造単位（２）の例としては、下式（２−１）または下式（２−２）で表される構造単位が挙げられ、

(In the formula, Z is the protonic acid group independently, s is an integer of 0 to 3 independently, t is an integer of 0 to 4 independently, and the lines at both ends are adjacent to each other. Indicates a combination with a unit. Definitions of symbols other than these are as described above.)
Further, as an example of the structural unit (2), a structural unit represented by the following equation (2-1) or the following equation (2-2) can be mentioned.

さらに具体的には、下式（２−３）または下式（２−４）で表される構造単位が挙げられる。

More specifically, structural units represented by the following equation (2-3) or the following equation (2-4) can be mentioned.

（式中、ｔはそれぞれ独立に０〜４の整数であり、両末端の線は隣り合う構造単位との結合を示す。ｔ以外の記号の定義は前述したとおりである。）
前記構造単位（１）および前記構造単位（２）の合計量に対する前記構造単位（１）のモル分率は、水透過性の高い半透膜を形成できることや、本発明の加圧による水透過流束向上効果の観点から、好ましくは０．１以上、より好ましくは０．２以上、さらに好ましくは０．３以上、特に好ましくは０．３５以上であり；また、塩阻止率が高く、かつゲル化しない半透膜を形成できることから、好ましくは０．９以下、より好ましくは０．７以下、さらに好ましくは０．６以下である。

(In the formula, t is an integer of 0 to 4 independently, and the lines at both ends indicate the connection with the adjacent structural unit. The definitions of symbols other than t are as described above.)
The mole fraction of the structural unit (1) with respect to the total amount of the structural unit (1) and the structural unit (2) can form a semipermeable membrane having high water permeability, and the water permeation by pressurization of the present invention. From the viewpoint of the flux improving effect, it is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and particularly preferably 0.35 or more; Since a semipermeable membrane that does not gel can be formed, it is preferably 0.9 or less, more preferably 0.7 or less, and further preferably 0.6 or less.

The protonic acid group-containing aromatic polyether resin may further contain a structural unit derived from a polyfunctional compound described later.

The protonic acid group-containing aromatic polyether resin may be a crosslinked product or a non-crosslinked product.

The weight average molecular weight (Mw) of the protonic acid group-containing aromatic polyether resin measured by the GPC (Gel Permeation Chromatography) method under the following conditions (1) to (6) is preferably 70,000 or more. , More preferably 80,000 or more, still more preferably 90,000 or more. When the molecular weight is in the above range, the obtained semipermeable membrane has high mechanical properties and is not easily torn during film formation or use. The weight average molecular weight is preferably 180,000 or less from the viewpoint of gel generation rate.

(1) Measurement temperature: 40 ° C
(2) Developing solvent: N, N-dimethylformamide (DMF)
(3) Flow rate: 1.0 ml / min
(4) Injection amount: 500 μl
(5) Detector: UV detector
(6) Molecular weight standard substance: Standard polystyrene The weight average molecular weight is controlled by adjusting the molar ratio of the raw material monomer and the amount of the end-capping agent when producing the protonic acid group-containing aromatic polyether resin. can do.

The protonic acid group equivalent of the protonic acid group-containing aromatic polyether resin, that is, the mass of the protonic acid group-containing aromatic polyether resin per mol of the protonic acid group was not dissolved in water or methanol, and swelling was suppressed. Since a semitransparent film having a small amount of electrolyte permeated through the film can be obtained, the amount is preferably 200 g / mol or more. Further, since a semipermeable membrane having a large permeation flux of water and high economy can be obtained, it is preferably 5000 g / mol or less, more preferably 1000 g / mol or less.

(Manufacturing method of aromatic polyether resin containing protonic acid group)
The protonic acid group-containing aromatic polyether resin can be obtained by condensing a monomer having an aromatic ring according to a conventionally known method (for example, the method described in International Publication No. 2003/3566). For example, the following equations (1a) and (2a)

で表されるハロゲン置換基を有する単量体と、下式（１ｂ）および（２ｂ）：

A monomer having a halogen substituent represented by the following formulas (1b) and (2b):

で表される水酸基を有する単量体との縮合重合によって、前記樹脂を得ることができる。

The resin can be obtained by condensation polymerization with a monomer having a hydroxyl group represented by.

In the formula, Y is a halogen atom, and the meaning of each of the other codes is the same as the meaning of the same code used in the above formulas (1) and (2). Preferred examples of the halogen atom include fluorine and chlorine.

It is preferable to use a basic catalyst such as K ₂ CO _{3 for condensation.}

Examples of the monomer represented by the above formula (1a) ( ^{where at least one of X 1 to} X ² is a protonic acid group) include 5,5'-carbonylbis (2-fluorobenzenesulfonic acid). Examples thereof include protonic acid group-containing aromatic dihalide compounds such as sodium) and 5,5'-carbonylbis (sodium 2-chlorobenzenesulfonate).

Examples of the monomer represented by the above formula (2a) include, for example.
4,4'-difluorobenzophenone, 3,3'-difluorobenzophenone, 4,4'-dichlorobenzophenone, 3,3'-dichlorobenzophenone, 4,4'-difluorobiphenyl, 4,4'-difluorodiphenylmethane, 4, Aromatic dihalide compounds such as 4'-dichlorodiphenylmethane, 4,4'-difluorodiphenyl ether; and 3,3'-dimethyl-4,4'-difluorobenzophenone, 3,3'-diethyl-4,4'-difluorobenzophenone , 3,3', 5,5'-tetramethyl-4,4'-difluorobenzophenone, 3,3'-dimethyl-4,4'-dichlorobenzophenone, 3,3', 4,4'-tetramethyl- Examples thereof include alkyl group-containing aromatic dihalide compounds such as 5,5'-dichlorobenzophenone.

Monomer represented by the formula (2b) (or the monomer (however represented by the formula (1b), X ³ to X ⁵ are those wherein all hydrogen atoms.)) As, for example,
4,4'-Dihydroxybiphenyl, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxybenzophenone, 2,2-bis (4-hydroxyphenyl) propane, 1,1,1 , 3,3,3-hexafluoro-2,2-bis (4-hydroxyphenyl) propane, 1,4-bis (4-hydroxyphenyl) benzene, α, α'-bis (4-hydroxyphenyl) -1 , 4-Dimethylbenzene, α, α'-bis (4-hydroxyphenyl) -1,4-diisopropylbenzene, α, α'-bis (4-hydroxyphenyl) -1,3-diisopropylbenzene, 1,4- Aromatic dihydroxy compounds such as bis (4-hydroxybenzoyl) benzene, 3,3'-difluoro-4,4'-dihydroxybiphenyl; and 3,3'-dimethyl-4,4'-dihydroxybiphenyl, 3,3'. , 5,5'-Tetramethyl-4,4'-dihydroxybiphenyl, 3,3'-dimethyl-4,4'-dihydroxydiphenylmethane, 3,3', 5,5'-Tetramethyl-4,4'- Dihydroxydiphenylmethane (also known as bis (3,5-dimethyl-4-hydroxyphenyl) methane), 3,3', 5,5'-tetraethyl-4,4'-dihydroxydiphenylmethane, 3,3'-dimethyl-4, 4'-Dihydroxydiphenyl ether, 3,3', 5,5'-tetramethyl-4,4'-dihydroxydiphenyl ether, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis ( 3-Ethyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, α, α'-bis (3-methyl-4-hydroxyphenyl) -1,4 -Diisopropylbenzene, α, α'-bis (3,5-dimethyl-4-hydroxyphenyl) -1,4-diisopropylbenzene, α, α'-bis (3-methyl-4-hydroxyphenyl) -1,3 Examples thereof include alkyl group-containing aromatic dihydroxy compounds such as −diisopropylbenzene and α, α'-bis (3,5-dimethyl-4-hydroxyphenyl) -1,3-diisopropylbenzene.

A polyfunctional compound may be copolymerized with the monomer as long as the solvent solubility of the protonic acid group-containing aromatic polyether resin is not impaired. By copolymerizing the polyfunctional compound, the protonic acid group-containing aromatic polyether resin can have a microcrosslinked structure. Examples of the polyfunctional compound include those having three or more hydroxyl groups in one molecule, for example, (2,4-dihydroxyphenyl) (4-hydroxyphenyl) methanone, 4- [1- (4-hydroxyphenyl) -1. -Methylethyl] -1,3-benzenediol, 4-[(2,3,5-trimethyl-4-hydroxyphenyl) methyl] -1,3-benzenediol, 4-[(4-hydroxyphenyl) methyl] -1,2,3-benzenetriol, (4-hydroxyphenyl) (2,3,4-trihydroxyphenyl) methanone, 4-[(3,5-dimethyl-4-hydroxyphenyl) methyl] -1,2 , 3-benzenetriol, 4-[(2,3,5-trimethyl-4-hydroxyphenyl) methyl] -1,2,3-benzenetriol, 4,4'-[1,4-phenylenebis (1-4-phenylenebis) Methylethylidene)] bis [benzene-1,2-diol], 5,5'-[1,4-phenylene bis (1-methylethylidene)] bis [benzene-1,2,3-triol], α, α , Α'-Tris (4-hydroxyphenyl) -1-ethyl-4-isopropylbenzene, fluoroglucin, pyrogallol and the like.

These copolymerization amounts are determined from the viewpoint of preventing a decrease in solvent solubility of the protonic acid group-containing aromatic polyether resin, a decrease in fluidity during film formation of the resin, and a decrease in the elongation rate of the semipermeable membrane. Preferably, out of 0 to 8 mol% / total OH equivalent (that is, the total amount (100 mol%) of OH groups contained in the monomer of the above formula (1b), the monomer of the formula (2b) and the polyfunctional monomer). 0 to 8 mol% is an OH group derived from a polyfunctional monomer), more preferably 0 to 5 mol% / total OH equivalent.

(Varnish of aromatic polyether resin containing protonic acid group)
Since the molecular structure of the protonic acid group-containing aromatic polyether resin is basically linear, and even if it has a crosslinked structure derived from the polyfunctional compound, the amount thereof is small. Excellent solvent solubility. Therefore, the resin can be in the form of a varnish dissolved in a solvent.

Examples of the solvent are not particularly limited, and alcohols such as water, methanol, ethanol, 1-propanol, 2-propanol and butanol, hydrocarbons such as toluene and xylene, and halogenated carbides such as methyl chloride and methylene chloride are used. Hydrogens, dichloroethyl ethers, ethers such as 1,4-dioxane and tetrahydrofuran, fatty acid esters such as methyl acetate and ethyl acetate, ketones such as acetone and methyl ethyl ketone, cellosolves such as 2-methoxyethanol and 2-ethoxyethanol. Examples include aprotic polar solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and dimethyl carbonate. These can be used alone or in admixture of two or more. Among them, lower alcohols (methanol, ethanol, 1-propanol, 2-propanol, t-butyl alcohol, etc.), tetrahydrofuran, N, N-dimethylformamide, N-methyl-2-pyrrolidone, etc. are preferable because they are water-soluble. Further, a mixed solvent of these and water is also preferable. The resin concentration in the varnish can be selected depending on the method of using the varnish, but is preferably 1% by mass or more and 80% by mass or less.

<< Tensile elastic modulus, tensile breaking strength and elongation >>
The tensile elastic modulus of the semipermeable membrane is preferably 0.8 to 2.0 GPa, more preferably 1.2 to 1.6 GPa. The tensile breaking strength of the semipermeable membrane is preferably 40 MPa or more, and the upper limit thereof is, for example, 100 MPa. The elongation rate of the semipermeable membrane is preferably 40% or more, and the upper limit thereof is, for example, 200%. These tensile elastic modulus, tensile strength at break and elongation are measured under the following conditions.

Prepare a test piece of length x width x thickness = 100 mm x 10 mm x 5 μm, pull it at a speed of 50 mm / min using a tensile tester, and test the strength (tensile load value) when the test piece is cut (broken). (Value divided by the cross-sectional area of one piece) and the elongation rate are obtained.

The growth rate is calculated by the following formula.

Elongation rate (%) = 100 x (L-L ₀ ) / L ₀
(L ₀ : Test piece length before test L: Test piece length at break)
The tensile elastic modulus is a value obtained by dividing the load at break by the cross-sectional area of the test piece and the strain amount at break, that is, (L−L ₀ ) / L _0.

The tensile strength at break and the elongation rate can be increased, for example, by increasing the molecular weight of the protonic acid group-containing aromatic polyether resin.

<< Solubility and mass reduction rate >>
The solubility of the semipermeable membrane in dimethyl sulfoxide (hereinafter, also referred to as "DMSO") and water can be evaluated by the following mass reduction rates. The mass reduction rate is preferably less than 2% by mass, more preferably 1.0% by mass or less, and particularly preferably 0.5% by mass or less.

The semipermeable membrane is allowed to stand at 150 ° C. for 4 hours under a nitrogen atmosphere to dry, and then weighed. The semipermeable membrane is immersed in DMSO or water and allowed to stand at 25 ° C. for 24 hours. The semipermeable membrane is removed from DMSO or water, allowed to stand at 150 ° C. for 4 hours in a nitrogen atmosphere, dried, and then weighed. Based on the mass before and after immersion of the semipermeable membrane, the mass reduction rate is calculated from the following formula.

Mass reduction rate = (mass before immersion of semipermeable membrane-mass after immersion of semipermeable membrane) / mass before immersion of semipermeable membrane x 100
The dissolved amount can be reduced, for example, by cross-linking the protonic acid group-containing aromatic polyether resin, and therefore the dissolved amount can be within the above range even if the proton acid group equivalent is small.

(Manufacturing method of semipermeable membrane)
The semipermeable membrane can be produced as a self-supporting membrane from the protonic acid group-containing aromatic polyether resin.

The semipermeable membrane can be easily produced by press-molding or extruding the protonic acid group-containing aromatic polyether resin. Further, the film of the protonic acid group-containing aromatic polyether resin may be subjected to a stretching treatment or the like.

The semipermeable membrane can also be produced from the above-mentioned varnish by a casting method. That is, a semipermeable membrane can be obtained by applying the varnish on the support and volatilizing and removing the solvent. Further, the semipermeable membrane may be peeled off from the support to form a self-supporting membrane.

If an organic solvent or the like at the time of casting remains in the semipermeable membrane, the mechanical strength of the semipermeable membrane may decrease and the semipermeable membrane may be easily damaged. Therefore, it is preferable that the semipermeable membrane produced by the casting method is sufficiently dried and / or washed with water, an aqueous sulfuric acid solution, hydrochloric acid or the like.

When the protonic acid group contained in the protonic acid group-containing aromatic polyether resin used for producing the semitransparent film has a hydrogen atom substituted with Na or K in a functional group that easily releases a proton. A film of the protonic acid group-containing aromatic polyether resin may be formed, and then Na or K of the protonic acid group may be replaced with a hydrogen atom by contacting the film with hydrochloric acid, an aqueous solution of sulfuric acid, or the like. ..

<Porous medium>
The air permeability of the porous substrate ^{is preferably 100 to 400 cm 3} / cm ² / s. This air permeability is measured as follows based on the A method (Frazier type method) described in JIS L 1096.

A 20 cm × 20 cm test piece is attached to the testing machine, the suction fan and the air hole are adjusted so that the inclined barometer has a pressure of 125 Pa, and the pressure indicated by the vertical barometer is measured. From the measured pressure and the type of air holes, determine the amount of air passing through the test piece from the conversion table attached to the testing machine.

The thickness of the porous substrate is usually 50 to 700 μm, preferably 80 to 600 μm, and more preferably 100 to 500 μm.

As the forward osmosis membrane, a thin porous substrate having such high air permeability is preferably used, so that the concentration polarization generated inside the porous substrate when the forward osmosis membrane is used is suppressed, and water is used. It is considered that the fluid resistance when permeating through the forward osmosis membrane can be reduced, and as a result, the permeation flux of water in the forward osmosis membrane can be increased. The air permeability and thickness of the porous substrate can be controlled by a conventional method.

Preferred materials constituting the porous base material include synthetic resins and natural fibers.

Examples of the synthetic resin include a thermoplastic resin and a thermosetting resin, and the thermoplastic resin is preferable. Specific examples of the thermoplastic resin include olefin polymers, polyester resins, polyamide resins, polyvinyl chlorides, and (meth) acrylic resins. Of these, olefin-based polymers and polyester resins are preferable, and olefin-based polymers are particularly preferable.

Specifically, the olefin-based polymer is a homopolymer or copolymer of an α-olefin, or a copolymer of an α-olefin and another monomer. Examples of the α-olefin include α-olefins having 2 to 8 carbon atoms such as ethylene, propylene and 1-butene. Olefin-based polymers include polypropylene, polyethylene, poly1-butene, poly4-methyl-1-pentene, ethylene / propylene copolymer, ethylene / 1-butene copolymer, and ethylene / 4-methyl-1-pentene. Copolymers, polyolefin resins such as propylene / 1-butene copolymers, 4-methyl-1-pentene / 1-decene copolymers, α-olefins such as ethylene / vinyl alcohol copolymers and other monomers Contains copolymers.

Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate. Examples of the polyamide resin include nylon 6 and nylon 66.

Examples of natural fibers include plant fibers such as cotton and hemp, and animal fibers such as silk and wool. Of these, cotton and silk are preferred.

Examples of the porous base material include woven fabrics, non-woven fabrics, cloth-based materials such as knitted fabrics, and foamed sheets. Among them, cloth-based materials are preferable, woven fabrics and non-woven fabrics are more preferable, and non-woven fabrics are particularly preferable.

Examples of the non-woven fabric include long-fiber non-woven fabric by the spunbond method, short-fiber non-woven fabric by the melt blown method, long-fiber non-woven fabric such as flash-spun non-woven fabric, spunlace non-woven fabric, air-laid non-woven fabric, thermal bond non-woven fabric, needle punch non-woven fabric, and chemical bond non-woven fabric. However, spunbonded non-woven fabrics and melt-blown non-woven fabrics are preferable. Of these, spunbonded non-woven fabrics are preferable, and polyethylene terephthalate or polypropylene spunbonded non-woven fabrics are particularly preferable.

The non-woven fabric may be a core-sheath type or side-by-side type composite fiber in which the constituent fibers are composite fibers made of different resins and different resins are arranged on the outer surface side of the fibers. Examples of the composite fiber include a polyethylene / polypropylene core-sheath type or side-by-side type composite fiber.

The non-woven fabric may be a laminated non-woven fabric. Examples of the laminated non-woven fabric include a laminated non-woven fabric including a spunbonded non-woven fabric and a melt-blown non-woven fabric, in which a spun-bonded non-woven fabric and a melt-blown non-woven fabric are laminated (SM), and a spun-bonded non-woven fabric, a melt-blown non-woven fabric and a spunbonded non-woven fabric are used. Examples thereof include those laminated in order (SMS).

In order to obtain such a laminated non-woven fabric, a spunbonded non-woven fabric and a melt-blown non-woven fabric are laminated and both are integrally formed. Examples of the method of integrating are a method of superimposing a spunbonded non-woven fabric and a melt blown non-woven fabric and heating and pressurizing them, a method of adhering them with an adhesive such as a hot melt adhesive or a solvent-based adhesive, and a method of adhering them on a spunbonded non-woven fabric. Examples thereof include a method of depositing fibers by a melt blown method and heat-sealing them.

The non-woven fabric may be a laminated non-woven fabric in which a porous film having micropores is sandwiched between the non-woven fabrics. Examples of such a laminated non-woven fabric include polypropylene (PP) non-woven fabric, porous PP film, and PP non-woven fabric (SFS) laminated in this order, PP non-woven fabric, porous PP film, and rayon PP non-woven fabric (SFR). ) And are laminated in this order.

Basis weight of the nonwoven fabric (basis weight of the laminated nonwoven fabric in the case of a layered nonwoven fabric) is preferably 10 to 80 g / m ^2, more preferably about 20 to 40 g / m ² approximately.

<Mesh-like support base material>
The mesh-like support base material may have sufficient strength to support the semipermeable membrane and sufficient solvent permeability so as not to resist permeation, and the shape is not particularly limited, but is a lattice-like material made of threads or fibers. Is preferable.

The number of meshes of the mesh-like support base material is preferably 20 to 300 pieces / inch.

The mesh size of the mesh-like support base material is preferably 40 × 40 to 6,000 × 6,000 (μm × μm).

The fiber diameter of the mesh-like support base material is preferably 20 to 300 μm.

The aperture ratio of the mesh-like support base material is preferably 30 to 90%.

The material of the mesh-shaped support base material is not particularly limited as long as it has the strength to support the semipermeable membrane, and examples thereof include a base material made of resin, metal, glass fiber, ceramic, or the like. Among these, a resin base material that is lightweight and has excellent workability is preferable.

Examples of the resin include polyethylene, polypropylene, polyester, polyamide, and polyimide. Examples of such a resin mesh-like support base material include products manufactured by Kuruba.

In order to hold the semipermeable membrane with the mesh-like support base material, the mesh-like support base material and the semipermeable membrane may be bonded to each other via an adhesive, or the mesh-like support base material and the semipermeable membrane may simply be attached to each other. The periphery may be sandwiched between frame materials and fixed by simply stacking them. From the viewpoint of handling, it is preferable to bond the mesh-like support base material and the semipermeable membrane via an adhesive. The adhesive is preferably applied only to the fiber portion so as not to block the opening of the mesh-like support base material.

<Manufacturing method of forward osmosis membrane>
The forward osmosis membrane can be manufactured, for example, by manufacturing the semipermeable membrane as a self-supporting membrane and sandwiching the semipermeable membrane between two porous substrates from both sides thereof.

Specifically, the forward osmosis membrane can be produced by the following procedure. For example, a dilute solution of the protonic acid group-containing aromatic polyether resin is applied onto a substrate made of PET or the like so that the thickness after drying becomes the desired thickness, and after drying, the formed film is peeled off as a self-supporting film. .. The free-standing membrane can be sandwiched between two porous substrates such as non-woven fabric to produce a forward osmosis membrane. When the area of the forward osmosis membrane is large, in order to maintain the distance between the semipermeable membrane and the porous substrate, both are adhered with an adhesive to the extent that they do not affect the permeation flux. May be good.

The forward osmosis membrane can also be produced by producing the semipermeable membrane as a self-supporting membrane and laminating it on the porous substrate. At this time, the two may be bonded together using an adhesive.

When a mesh-like support base material is used, the mesh-like support base material is provided between the semipermeable membrane and the porous base material in the manufacturing method. When the porous base material is provided on both sides of the semipermeable membrane, the mesh-like support base material is provided on at least one of the semipermeable membrane and the porous base material.

According to the manufacturing method, the semipermeable membrane described above is first manufactured as a self-supporting membrane, and this is laminated on a porous base material (nonwoven fabric, etc.) or sandwiched between two porous base materials (nonwoven fabric, etc.). Therefore, since the forward osmosis membrane is produced, the thickness of the semipermeable membrane is controlled, and the forward osmosis membrane exhibiting high water permeability and high salt blocking rate can be easily produced.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The contents of the abbreviations used in this embodiment are shown.

(1) Solvent DMSO: Dimethyl sulfoxide DMF: N, N-dimethylformamide (2) Constituents of aromatic polyether DFBP: 4,4'-difluorobenzophenone DSDFBP:
5,5'-carbonylbis (sodium 2-fluorobenzenesulfonate)
TMBPF:
The test methods for various tests of 3,3', 5,5'-tetramethyl-4,4'-dihydroxydiphenylmethane are as follows.

Evaluation of Resin-Weight Average Molecular Weight (Mw)
Using the GPC (Gel Permeation Chromatography) method, the weight average molecular weight (Mw) was determined under the following conditions.

(1) Measurement temperature: 40 ° C
(2) Developing solvent: DMF
(3) Flow rate: 1.0 ml / min
(4) Injection amount: 500 μl
(5) Detector: UV detector
(6) Molecular Weight Standard Material: Standard Polystyrene More specifically, the high performance liquid chromatograph (HPLC) used for the GPC measurement uses the following devices in combination by a conventional method.
HPLC: Shimadzu RID-10A-LC-10AT type system Column oven: Shimadzu CTO-10A type equipment
UV detector: 875-UV type device guard column manufactured by JASCO Corporation (JASCO): MD-G type column manufactured by Nitto Denko Corporation
GPC column: Two KD805M type columns, one KD8025 type column, and one 802 type column manufactured by Nitto Denko were connected in series and used.

Evaluation of Semipermeable Membrane-Thickness The thickness of the semipermeable membrane was measured using a spectrophotometer (ellipsometry) manufactured by JASCO Corporation. Specifically, when light is incident on a film having a refractive index n at a certain angle (θ), the reflected light A from the front surface of the film and the reflected light B from the back surface interfere with each other to generate a wavy interference spectrum. The thickness (d) was calculated from Eq. (1) by counting the number (Δm) of the peaks (peaks or valleys) of the interference spectrum within a certain wavelength range (λ _{1 to λ 2).}

（単量体合成例１）
特開２０１４−５３３号公報の［００６１］段落（合成例１）に記載の方法で、下式で表されるＤＳＤＦＢＰの白色結晶を得た。収量は１５５．２ｇ（０．３８６ｍｏｌ、収率７０％）であった。

(Example 1 of monomer synthesis)
White crystals of DSDFBP represented by the following formula were obtained by the method described in paragraph [0061] (Synthesis Example 1) of JP-A-2014-533. The yield was 155.2 g (0.386 mol, yield 70%).

（樹脂合成例１）
窒素導入管、温度計、還流冷却器、及び撹拌装置を備えた５つ口反応器に、単量体合成例１で得られたＤＳＤＦＢＰ６４．２ｇ（０．１５２ｍｏｌ）、ＤＦＢＰ４９．８ｇ（０．２２８ｍｏｌ）、ＴＭＢＰＦ９７．４ｇ（０．３８０ｍｏｌ）および炭酸カリウム６５．７ｇ（０．４７５ｍｏｌ）を秤取した。これにＤＭＳＯ８４５．４ｇとトルエン２８１．８ｇを加え、窒素雰囲気下で撹拌し、１３０℃で１２時間加熱し、生成する水を系外に除去した後、トルエンを留去した。

(Resin Synthesis Example 1)
DSDFBP 64.2 g (0.152 mol) and DFBP 49.8 g (0.228 mol) obtained in Monomer Synthesis Example 1 were placed in a five-port reactor equipped with a nitrogen introduction tube, a thermometer, a reflux condenser, and a stirrer. ), TMBPF 97.4 g (0.380 mol) and potassium carbonate 65.7 g (0.475 mol) were weighed. To this, DMSO 845.4 g and toluene 281.8 g were added, stirred under a nitrogen atmosphere, heated at 130 ° C. for 12 hours, the water produced was removed from the system, and then toluene was distilled off.

Subsequently, the reaction was carried out at 160 ° C. for 12 hours to obtain a viscous polymer solution. After diluting by adding 570 g of toluene to the obtained solution, it is discharged to 2400 g of methanol, the precipitated polymer powder is filtered, washed, and dried at 150 ° C. for 4 hours to 168.7 g of polyetherketone powder (yield 86%). ) (Resin 1) was obtained.

The resin (1) is used as the structural unit (1).

で表される構造を、前記構造単位（２）として

The structure represented by is used as the structural unit (2).

で表される構造を有している。ここで、前記構造単位（１）：前記構造単位（２）＝４０ｍｏｌ：６０ｍｏｌである。また、Ｍｗ＝１２６，０００であった。

It has a structure represented by. Here, the structural unit (1): the structural unit (2) = 40 mol: 60 mol. Moreover, Mw = 126,000.

(Resin Synthesis Example 2)
Resin raw materials and solvents such as DSDFBP 40.1 g (0.095 mol), DFBP 62.2 g (0.284 mol), TMBPF 97.4 g (0.380 mol) and potassium carbonate 65.7 g (0.475 mol), and DMSO 798.4 g and 156.5 g (yield 85%) (resin 2) of the polymer powder was obtained in the same manner as in Resin Synthesis Example 1 except that the amount of the solvent was 266.2 g. Here, the structural unit (1): the structural unit (2) = 25 mol: 75 mol. Moreover, Mw = 123,000.

(Resin Synthesis Example 3)
Resin synthesis except that the raw material and solvent of the resin were DSDFBP 24.1 g (0.057 mol), DFBP 70.7 g (0.323 mol), TMBPF 97.4 g (0.380 mol) and potassium carbonate 65.7 g (0.475 mol). A polymer powder (resin 3) was obtained in the same manner as in Example 1. Here, the structural unit (1): the structural unit (2) = 15 mol: 85 mol. Moreover, Mw = 134,000.

[Manufacturing Examples 1 to 3]
Resin 1 produced in Resin Synthesis Example 1 is dissolved in DMF to prepare a varnish having a resin concentration of 5% by mass, the varnish is cast on a release sheet, and dried at 150 ° C. for 10 minutes to form a film of resin 1. Obtained. This was peeled off from the release sheet to form a self-supporting membrane, and a semipermeable membrane 1 having a thickness of 0.6 μm was obtained. In the same manner, a semipermeable membrane 2 was obtained using the resin 2 and a semipermeable membrane 3 was obtained using the resin 3.

Next, the air permeability measured by the A method (Frazier method) described in JIS L 1096 is 300 cm ³ / cm ² / s, the thickness is 290 μm, and the material is polypropylene. 105 Two sheets manufactured by Mitsui Kagaku Co., Ltd. are prepared, the semipermeable membranes 1 to 3 are sandwiched between these non-woven materials, and these are integrated to form a forward osmosis membrane A having a semipermeable membrane 1 and a semipermeable membrane. A forward osmosis membrane B having 2 and a forward osmosis membrane C having a semipermeable membrane 3 were obtained.

[Examples and Comparative Examples]
-Forward osmosis membranes A to C were used. The osmosis membrane was evaluated by cross-flow using a cell having an effective area of osmosis membrane of 86 × 40 mm ^2.

A schematic diagram of the apparatus 10 used for the evaluation is shown in FIG. The device 10 includes an FS tank 1, each flow path 2, 2-1 and 2-2, a pump 3, a DS tank 11, each flow path 12, 12-1, 12-2, a pump 13, and a forward osmosis membrane module 21. Each valve B1 to B4 is provided. The FS tank 1 and the DS tank 11 are installed on the balances 4 and 14, respectively, and these are provided with electric conductivity meters 5 and 15, respectively. The FS flowing through the flow path 2 and the DS flowing through the flow path 12 come into contact with each other inside the forward osmosis membrane module 21 via the forward osmosis membrane 22 (the above forward osmosis membranes A to C) having an ^{effective membrane area of 86 × 40 mm 2.} A part of FS moves to DS through the forward osmosis membrane 22, and a part of salt (NaCl) in DS moves (backflow) to FS.

Set Milli-Q water having an electric conductivity of 50 μS / cm or less in the DS tank 11 and Milli-Q water having an electric conductivity of 50 μS / cm or less in the FS tank 1, and adjust the flow rate to 0.6 L / min respectively. Then, the opening degree of the needle valve was adjusted so that the supply pressure of each water at that time was balanced between FS and DS. The supply pressure at that time was 25 kPa, respectively. Next, 0.6 mol / L saline solution was set in the DS tank 11 and the flow rate was set to 0.6 L / min. After adjusting the FS and DS to a pressure that balances the FS and DS at a flow rate of 0.6 L / min, the pressure on the FS side is 1 kPa, 5 kPa or 10 kPa higher than the pressure on the DS side, or the pressure on the FS side is increased. The flow rate was maintained at 0.6 L / min while adjusting the supply pressures of FS and DS so as to be the same as the pressure on the DS side.

Here, the weight of the solution and the electrical conductivity of the solution were measured every 1 minute on the FS side and the DS side, respectively. From the change in weight and electrical conductivity for one minute, the unit time, the water permeation flux Jw (LMH: L / (m ² · h)), which is the amount of permeated water per unit area of the forward osmosis membrane, and the unit time, ^{The amount of reverse diffusion of salt Js (gMH: g / (m 2} · h)), which is the amount of salt movement per unit area of the forward osmosis membrane, was determined, and after about 10 minutes, Jw and Js were measured in a stable state. It was set as a value.

At this time, a calibration curve of electrical conductivity and salt concentration was prepared in advance, and the salt concentration was calculated from the electrical conductivity and volume change. From the amount of change in salt concentration on the FS side, the amount of salt transferred from DS to the FS side per hour was calculated, and Js (gMH) was calculated.

The measurement results are shown in Table 1.

正浸透膜Ａを用いた例において、差圧が０ｋＰａ（比較例）の場合、Ｊｗが小さく、Ｊｓが大きい値となったが、差圧が１、５または１０ｋＰａ（実施例）の場合、Ｊｗが大きく、また差圧が５または１０ｋＰａ（実施例）の場合、Ｊｓが小さい値となった。Ｊｓ／Ｊｗも、比較例に比べて実施例は小さい値となった。

In the example using the forward osmosis membrane A, when the differential pressure was 0 kPa (comparative example), Jw was small and Js was large, but when the differential pressure was 1, 5 or 10 kPa (example), Jw. Was large, and when the differential pressure was 5 or 10 kPa (Example), Js was a small value. The values of Js / Jw in the examples were smaller than those in the comparative examples.

In the example using the forward osmosis membrane B or C, when the differential pressure was 0 kPa (comparative example), Jw was a small value, but when the differential pressure was 1, 5 or 10 kPa (example), Jw was large. It became a value.

1 Solution FS tank 2, 12 Flow path 2-1, 12-1 Circulation flow path 2-2, 12-2 Bypass flow path 3, 13 Pump 4, 14 Balance 5, 15 Electrical conductivity meter (conductivity meter)
10 Liquid transfer system (evaluation device)
11 Solution DS tank 15 Electrical conductivity meter (conductivity meter)
21 Forward osmosis membrane module (evaluation cell)
22 Forward osmosis membrane DS draw solution FS feed solution B (B1 to B4) Opening adjustment valve P Pressure gauge

Claims (5)

The solution FS is supplied to the region on one surface side of the forward osmosis membrane provided with the semitransparent film and the porous substrate arranged on at least one surface thereof, and the solute from the solution FS is supplied to the region on the other surface side. This is a method for producing a solution in which the solute concentration of the solution DS is lowered by supplying a high-concentration solution DS and moving the solvent contained in the solution FS to the solution DS through the forward osmosis membrane.
The supply pressure P1 of the solution FS and the supply pressure P2 of the solution DS are
Formula: 0.5 kPa ≤ P1-P2 ≤ 700 kPa
How to meet. The method according to claim 1, wherein the forward osmosis membrane further includes a mesh-like support base material between the semipermeable membrane and the porous base material. The method according to claim 1 or 2, wherein the thickness of the semipermeable membrane is 3.0 μm or less. The semipermeable membrane comprises a protonic acid group-containing aromatic polyether resin containing a structural unit (1) represented by the following formula (1) and a structural unit (2) represented by the following formula (2). ,
^{The porous substrate has an air permeability of 100 to 400 cm 3} / cm ² / s and a thickness of 50 to 700 μm as measured by the method A (Frazier method) described in JIS L 1096.
The method according to any one of claims 1 to 3.

[In equations (1) and (2)
R ^{1 to} R ¹⁰ are independently H, Cl, F, CF ₃ or C _m H _{2m + 1} (m indicates an integer of 1 to 10).
At least one of ^{R 1 to} R ¹⁰ _{is C m} H _{2m + 1} (m indicates an integer of 1 to 10).
Two or more of R ^{1 to} R ¹⁰ may be present in each aromatic ring, and when two or more C _m H _{2 m + 1} are present in one _{aromatic ring, each C m} H _{2 m + 1} is present with each other. It may be the same or different.
X ^{1 to} X ⁵ are independently H, Cl, F, CF ₃ or protonic acid groups, respectively.
At ^{least one of X 1 to} X ⁵ is a protonic acid group and
Two or more of X ^{1 to} X ⁵ may be present in each aromatic ring, and when two or more protonic acid groups are present in one aromatic ring, the protonic acid groups are different even if they are the same as each other. May be.
A ^{1 to} A ⁶ are independently directly bonded, −CH ₂ −, −C (CH ₃ ) ₂₋ , −C (CF ₃ ) ₂₋ , −O− or −CO−, respectively.
i, j, k and l independently represent 0 or 1, respectively. ] The method according to any one of claims 1 to 4, wherein both the solution FS and the solution DS are aqueous solutions containing a salt, and the salt concentration of the solution DS is higher than the salt concentration of the solution FS. ..

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