JP2018202374A - Moisture absorbent, draw solution and forward osmosis water treatment method - Google Patents

Abstract

To provide a moisture absorbent easily recycling a dilute moisture absorbent absorbed with moisture by making concentration high and having low viscosity and to provide a forward osmosis water treatment method using the moisture absorbent as a draw solution.SOLUTION: Moisture in a supply solution is removed by a forward osmosis water treatment method that a moisture absorbent including: diamides such as N,N,N',N'-tetrapropyl malonamide, N,N,N',N'-tetraisopropyl malonamide and the like; triamides such as N,N',N"-triethylbenzene-1,3,5-tricarboxamide, N,N',N"-tripropyl benzene-1,3,5-tricarboxamide and the like; and amido amines such as N-(2-(diethyl amino)ethyl) butane amide, N-(3-(dimethyl amino)propyl)butane amide and the like, and the supply solution containing moisture as a draw solution are in contact via a semi-permeable membrane.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a water absorbing liquid that absorbs moisture in a gas by contact with the gas and a method for regenerating the same. The present invention also relates to a draw solution and a forward osmosis water treatment method in the forward osmosis method.

As a technique for absorbing moisture in the gas, Patent Document 1 describes a technique related to a dehumidifying apparatus using polyethylene glycol (M = 400), triethylene glycol, and tetraethylene glycol as a hygroscopic liquid.
Patent Document 2 discloses an organic aqueous solution selected from the group of triethylene glycol, tetraethylene glycol, glycerin and the like as an absorbing solution, or an inorganic system selected from the group of lithium chloride, lithium bromide, lithium iodide, calcium chloride and the like. Techniques relating to wet desiccant air conditioners using aqueous solutions are described.
Patent Document 3 describes a technique relating to a low-temperature humidity control apparatus that uses ethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol as a moisture absorbing liquid.

However, in the technique described in Patent Document 1, a hygroscopic liquid is held in a porous membrane, moisture is absorbed on one surface of the porous membrane, and moisture absorbed is removed as water vapor by reducing the pressure on the other surface. Regenerating hygroscopic liquid.
In the technique described in Patent Document 2, the absorbing liquid that has absorbed moisture is removed by vaporizing the moisture with a membrane separation device.
In the techniques of Patent Documents 1 and 2, decompression is required for regeneration of the hygroscopic liquid or absorbent, and a decompression device and energy are required. In the technique described in Patent Document 3, warm air is brought into contact with the moisture absorbent that has absorbed moisture. It is removed by evaporating the water. In this technique, it is necessary to evaporate water at normal pressure, and a high temperature is required.
As described above, the conventional techniques have problems.

Next, in the forward osmosis method, two types of solutions having different concentrations or osmotic pressures are brought into contact with each other through a semipermeable membrane, and the difference in osmotic pressure between these two types of solutions is reduced, that is, from a solution having a low concentration. This utilizes the phenomenon of water moving to a solution having a high concentration. Here, a solution having a low osmotic pressure is referred to as a supply liquid, and a solution having a high osmotic pressure is referred to as a draw solution (water absorption liquid).
The inventor has applied for a technique relating to a glycol ether-based water-soluble liquid compound as a draw solution (Patent Document 4).
However, in the technique described in Patent Document 4, since a glycol ether-based water-soluble liquid compound is used for the draw solution, there is a concern that a peroxide is generated during long-term use.
As described above, the conventional techniques have problems.

JP 2000-350918 A JP 2009-180433 A Japanese Patent Laying-Open No. 2015-175553 Japanese Patent Laid-Open No. 2006-49500

An object of the present invention is to provide a water-absorbing solution that is easy to recycle by diluting a diluted water-absorbing solution that has absorbed moisture, and has a low viscosity.
In addition, the object of the present invention is to use a non-ether compound with a low risk of generating a peroxide as a draw solution, to easily recycle the diluted draw solution at a high concentration, and to have a low viscosity and high penetration. A pressure draw solution is provided, and a forward osmosis water treatment method using the draw solution is provided.

［式中、Ｒ２、Ｒ３は互いに独立して、水素原子、炭素数１〜４の直鎖状もしくは分岐状アルキル基を表し、Ｒ４は炭素数１〜６の直鎖状もしくは環状のアルキレン基またはフェニレン基を表し、Ｒ２、Ｒ３、Ｒ４の炭素数の和が８〜１４である。］

［式中、Ｒ１は炭素数炭素数３〜６の直鎖状もしくは分岐状アルキル基、または炭素数３〜６環状アルキル基、または置換されてもよいフェニル基を表し、Ｒ２は水素原子、炭素数１〜３の直鎖状もしくは分岐状アルキル基を表し、Ｒ５は炭素数１〜４の直鎖状のアルキレン基を表し、Ｒ６、Ｒ７は互いに独立して、水素原子、炭素数１〜４の直鎖状もしくは分岐状アルキル基を表し、Ｒ１、Ｒ２、Ｒ５、Ｒ６，Ｒ７の炭素数の和が８〜１２である。］

［式中、Ｒ２、Ｒ３は互いに独立して、水素原子、炭素数１〜４の直鎖状もしくは分岐状アルキル基を表し、Ｒ４はベンゼントリイル基を表し、Ｒ２、Ｒ３、Ｒ４の炭素数の和が６〜１８である。］
〔２〕 前記一般式（１）の水溶性化合物が、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトラプロピルマロンアミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトライソプロピルマロンアミド、Ｎ，Ｎ‘−ジプロピルスクシンアミド、Ｎ，Ｎ’−ジイソプロピルスクシンアミド、Ｎ，Ｎ‘−ジブチルスクシンアミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトラエチルスクシンアミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトラプロピルスクシンアミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトライソプロピルスクシンアミド、Ｎ，Ｎ‘−ジプロピルアジピンアミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトラエチルアジピンアミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトラメチルシクロヘキサン−１，４−ジカルボキサミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトラエチルシクロヘキサン−１，４−ジジカルボキサミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトラエチルフタルアミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘−テトラエチルイソフタルアミドのいずれかであることを特徴とする〔１〕に記載の水吸収液。
〔３〕 前記一般式（２）の水溶性化合物が、Ｎ−（２−（ジエチルアミノ）エチル）ブタンアミド、Ｎ−（３−（ジメチルアミノ）プロピル）ブタンアミド、Ｎ−（３−（ジエチルアミノ）プロピル）ブタンアミド、Ｎ−（２−（ジメチルアミノ）エチル）ヘキサンアミド、Ｎ−（２−（ジエチルアミノ）エチル）ヘキサンアミド、Ｎ−（３−（ジメチルアミノ）プロピル）ヘキサンアミド、Ｎ−（３−（ジエチルアミノ）プロピル）ヘキサンアミド、Ｎ−（２−（ジメチルアミノ）エチル）シクロヘキサンカルボキサミド、Ｎ−（３−（ジメチルアミノ）プロピル）シクロヘキサンカルボキサミド、Ｎ−（２−（ジメチルアミノ）エチル）ベンズアミド、Ｎ−（３−（ジメチルアミノ）プロピル）ベンズアミドのいずれかであることを特徴とする〔１〕に記載の水吸収液。
〔４〕 前記一般式（３）の水溶性化合物が、Ｎ，Ｎ‘，Ｎ“−トリエチルベンゼン−１，３，５−トリカルボキサミド、Ｎ，Ｎ‘，Ｎ“−トリプロピルベンゼン−１，３，５−トリカルボキサミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘，Ｎ“Ｎ“−ヘキサエチルベンゼン−１，３，５−トリカルボキサミド、Ｎ，Ｎ‘，Ｎ“−トリエチルベンゼン−１，２，４−トリカルボキサミド、Ｎ，Ｎ‘，Ｎ“−トリプロピルベンゼン−１，２，４−トリカルボキサミド、Ｎ，Ｎ，Ｎ‘，Ｎ‘，Ｎ“Ｎ“−ヘキサエチルベンゼン−１，２，４−トリカルボキサミド、のいずれかであることを特徴とする〔１〕に記載の水吸収液。
〔５〕 水分を含む溶液と半透膜を介して接触させるドロー溶液であって、前記ドロー溶液が〔１〕〜〔４〕のいずれかに記載の水吸収液からなることを特徴とするドロー溶液。
〔６〕 〔５〕に記載のドロー溶液と、水分を含む供給溶液とを半透膜を介して接触させることで、供給溶液中の水分をドロー溶液に吸収させることを特徴とする正浸透水処理方法。
〔７〕 供給溶液から水分を吸収した希薄ドロー溶液を下限臨界溶液温度より高い温度に加熱することで相分離させ、液体‐液体の分液により水分を分離しドロー溶液を高濃度化して再生することを特徴とする〔６〕に記載の正浸透水処理方法。 In order to solve the above-mentioned problems, the present inventors have intensively studied and as a result, completed the present invention. That is, the present invention comprises the following technical means.
[1] A water-absorbing solution, which has absorbed water and becomes a dilute solution by contact with a gas containing water, and has a reduced ability to absorb water, is phase-separated by heating to a temperature higher than the lower critical solution temperature. -A water absorption liquid which can be regenerated by separating water by liquid separation and increasing the concentration of the water absorption liquid, wherein the water absorption liquid is represented by the general formula (1), the general formula (2) and the general formula (3 Or any one or more of the water-soluble compounds represented by the general formula (1), the general formula (2) and the general formula (3) and water. A characteristic water absorption liquid.

[Wherein, R2 and R3 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, and R4 represents a linear or cyclic alkylene group having 1 to 6 carbon atoms or Represents a phenylene group, and the sum of carbon numbers of R2, R3, and R4 is 8-14. ]

[Wherein R 1 represents a linear or branched alkyl group having 3 to 6 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms, or an optionally substituted phenyl group, and R 2 represents a hydrogen atom, carbon Represents a linear or branched alkyl group having 1 to 3 carbon atoms, R5 represents a linear alkylene group having 1 to 4 carbon atoms, R6 and R7 are each independently a hydrogen atom, 1 to 4 carbon atoms. The sum of the carbon number of R1, R2, R5, R6, R7 is 8-12. ]

[Wherein, R2 and R3 each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, R4 represents a benzenetriyl group, and the carbon number of R2, R3, or R4 Is the sum of 6-18. ]
[2] The water-soluble compound of the general formula (1) is N, N, N ′, N′-tetrapropylmalonamide, N, N, N ′, N′-tetraisopropylmalonamide, N, N′— Dipropyl succinamide, N, N'-diisopropyl succinamide, N, N'-dibutyl succinamide, N, N, N ', N'-tetraethylsuccinamide, N, N, N', N'- Tetrapropylsuccinamide, N, N, N ′, N′-tetraisopropylsuccinamide, N, N′-dipropyladipamide, N, N, N ′, N′-tetraethyladipinamide, N, N, N ′, N′-tetramethylcyclohexane-1,4-dicarboxamide, N, N, N ′, N′-tetraethylcyclohexane-1,4-didicarboxamide, N, N, N ′, N′-tetraethylphthalamide , N, N, N ′, '- Water absorption liquid according to [1], wherein the either of tetraethyl isophthalamide.
[3] The water-soluble compound of the general formula (2) is N- (2- (diethylamino) ethyl) butanamide, N- (3- (dimethylamino) propyl) butanamide, N- (3- (diethylamino) propyl) Butanamide, N- (2- (dimethylamino) ethyl) hexanamide, N- (2- (diethylamino) ethyl) hexanamide, N- (3- (dimethylamino) propyl) hexanamide, N- (3- (diethylamino) ) Propyl) hexaneamide, N- (2- (dimethylamino) ethyl) cyclohexanecarboxamide, N- (3- (dimethylamino) propyl) cyclohexanecarboxamide, N- (2- (dimethylamino) ethyl) benzamide, N- ( It is one of 3- (dimethylamino) propyl) benzamide The water absorbing liquid according to [1].
[4] The water-soluble compound of the general formula (3) is N, N ′, N “-triethylbenzene-1,3,5-tricarboxamide, N, N ′, N“ -tripropylbenzene-1,3. , 5-tricarboxamide, N, N, N ', N', N "N" -hexaethylbenzene-1,3,5-tricarboxamide, N, N ', N "-triethylbenzene-1,2,4- Tricarboxamide, N, N ', N "-tripropylbenzene-1,2,4-tricarboxamide, N, N, N', N ', N" N "-hexaethylbenzene-1,2,4-tricarboxamide The water-absorbing solution according to [1], which is any one of the above.
[5] A draw solution that is brought into contact with a water-containing solution through a semipermeable membrane, wherein the draw solution is composed of the water-absorbing solution according to any one of [1] to [4]. solution.
[6] A forward osmosis water characterized in that the draw solution absorbs moisture in the supply solution by contacting the draw solution according to [5] and the supply solution containing moisture through a semipermeable membrane. Processing method.
[7] Dilute draw solution that has absorbed moisture from the supplied solution is phase-separated by heating to a temperature higher than the lower critical solution temperature, and water is separated by liquid-liquid separation to increase the concentration of the draw solution and regenerate it. The forward osmosis water treatment method according to [6].

  ADVANTAGE OF THE INVENTION According to this invention, it is easy to recycle | recycle the dilute water absorption liquid which absorbed the water | moisture content, and it can provide a low viscosity water absorption liquid.

According to the present invention, it is possible to provide a draw solution that can be easily recycled by separating the draw solute and water from the dilute draw solution to increase the concentration of the draw solution. Moreover, according to the present invention, it is possible to provide a draw solution having a low viscosity and a high osmotic pressure.
In addition, the water-absorbing liquid of the present invention has a feature that there is no concern that peroxides are generated even when used for a long time.

Moreover, according to this invention, it is possible to provide the normal osmosis water processing method which can absorb a water | moisture content from a treated water with low energy.

FIG. 1 is a flowchart showing an example of the processing procedure of the forward osmosis water treatment method of the present invention. FIG. 2 is a schematic view showing an example of an apparatus for carrying out the forward osmosis water treatment method of the present invention.

  The water-absorbing liquid of the present invention is a water-absorbing liquid whose mixture with water has a lower critical solution temperature and has a reduced ability to absorb water by absorbing water by contacting water-containing gas. A water-absorbing liquid that is phase-separated by heating to a temperature higher than the lower critical solution temperature, can be separated by liquid-liquid separation, and can be regenerated by increasing the concentration of the water-absorbing liquid. The liquid is one or more of water-soluble compounds represented by general formula (1), general formula (2) and general formula (3), or general formula (1), general formula (2) and general formula (3). A water-absorbing solution comprising one or more water-soluble compounds represented by the formula (1) and water. It is.

  In the general formula (1) described in [1] above, a water-soluble liquid compound having a sum of carbon atoms of R2, R3, and R4 of 7 or less is miscible with pure water at an arbitrary ratio, but the volume ratio is 1: 1. Even if the aqueous solution is heated, it does not undergo phase separation and does not have a lower critical solution temperature. If the sum of carbon numbers is 15 or more, the volume ratio is 1: 1, and it is not miscible with pure water.

  More preferable water-soluble liquid compounds represented by the general formula (1) include N, N, N ′, N′-tetrapropylmalonamide, N, N, N ′, N′-tetraisopropylmalonamide, N, N′-dipropylsuccinamide, N, N′-diisopropylsuccinamide, N, N′-dibutylsuccinamide, N, N, N ′, N′-tetraethylsuccinamide, N, N, N ′, N′-tetrapropylsuccinamide, N, N, N ′, N′-tetraisopropylsuccinamide, N, N′-dipropyladipinamide, N, N, N ′, N′-tetraethyladipinamide, N , N, N ′, N′-tetramethylcyclohexane-1,4-dicarboxamide, N, N, N ′, N′-tetraethylcyclohexane-1,4-didicarboxamide, N, , N ', N'- tetraethyl phthalamide, N, N, N', can be exemplified N'- tetraethyl isophthalamide.

  In the general formula (2) described in the above [1], a water-soluble liquid compound having a sum of carbon atoms of R1, R2, R3, R4, R5, R6 of 7 or less is miscible with pure water at an arbitrary ratio. Even when an aqueous solution with a volume ratio of 1: 1 is heated, it does not undergo phase separation and does not have a lower critical solution temperature. Further, when the sum of the carbon numbers is 13 or more, it is not miscible with pure water at a volume ratio of 1: 1.

  More preferable water-soluble liquid compounds represented by the general formula (2) include N- (2- (diethylamino) ethyl) butanamide, N- (3- (dimethylamino) propyl) butanamide, N- (3- (diethylamino). ) Propyl) butanamide, N- (2- (dimethylamino) ethyl) hexanamide, N- (2- (diethylamino) ethyl) hexanamide, N- (3- (dimethylamino) propyl) hexanamide, N- (3 -(Diethylamino) propyl) hexanamide, N- (2- (dimethylamino) ethyl) cyclohexanecarboxamide, N- (3- (dimethylamino) propyl) cyclohexanecarboxamide, N- (2- (dimethylamino) ethyl) benzamide, N- (3- (dimethylamino) propyl) benzamide It can be exemplified.

  In the general formula (3) described in [1] above, an aqueous solution having a sum of carbon atoms of R2 and R3 of 5 or less is miscible with pure water at an arbitrary ratio. Even when heated, it does not phase separate and does not have a lower critical solution temperature. When the sum of carbon numbers is 19 or more, the volume ratio is 1: 1 and the mixture is not miscible with pure water.

  More preferable water-soluble liquid compounds represented by the general formula (3) include N, N ′, N ″ -triethylbenzene-1,3,5-tricarboxamide, N, N ′, N ″ -tripropylbenzene- 1,3,5-tricarboxamide, N, N, N ', N', N "N" -hexaethylbenzene-1,3,5-tricarboxamide, N, N ', N "-triethylbenzene-1,2 , 4-tricarboxamide, N, N ', N "-tripropylbenzene-1,2,4-tricarboxamide, N, N, N', N ', N" N "-hexaethylbenzene-1,2,4 -Tricarboxamide can be exemplified.

  The water-soluble liquid compound represented by the general formulas (1) to (3) described in [1] is mixed with pure water at an arbitrary ratio at a temperature of 15 ° C., and when gently mixed with pure water. The mixed liquid maintains a uniform appearance even after the flow has stopped. The mixture of the water-soluble liquid compound and water has a lower critical solution temperature.

In the water-absorbing liquid of the present invention, water-soluble compounds represented by the general formula (1), the general formula (2), and the general formula (3) can be used alone. (2) and a mixture of two or more water-soluble liquid compounds represented by the general formula (3) may be used (hereinafter referred to as “the general formula (1), the general formula (2) and the general formula (3)”. The water-soluble compounds shown may be referred to as “the water-soluble compound of the present invention (1), the water-soluble compound of the present invention (2) and the water-soluble compound of the present invention (3)”, respectively, They may be collectively referred to as “water-soluble compounds of the present invention”).
The water-soluble compound of the present invention may be used as an aqueous solution comprising the water-soluble compound of the present invention and water. In that case, the composition ratio of the water-soluble compound of the present invention is not limited as long as it can absorb moisture from the gas, but in order to increase the amount of water absorbed from the gas, the composition ratio of the water-soluble compound of the present invention is as small as possible. Larger is preferable. Usually, it is necessary to contain 50% or more of the water-soluble compound of the present invention in the water absorbing solution.

  The draw solution of the present invention is a draw solution brought into contact with a water-containing solution through a semipermeable membrane, and the draw solution is a solution comprising the water-soluble compound of the present invention or the water-soluble compound of the present invention and water. is there.

Although the water-soluble compounds (1) to (3) of the present invention can be used alone in the draw solution of the present invention, they are used as a mixture of two or more of the water-soluble compounds (1) to (3) of the present invention. May be.
Moreover, you may use as aqueous solution which consists of the water-soluble compound of this invention, and water. In that case, the composition ratio of the water-soluble compound and water of the present invention is not limited as long as an osmotic pressure higher than that of the supply solution can be achieved, but in order to increase the amount of water supplied from the supply solution, the supply solution is also used. In order to increase the concentration ratio, it is preferable that the composition ratio of the water-soluble compound of the present invention is as large as possible. Usually, it is necessary to contain 30% or more of the water-soluble compound of the present invention in the draw solution.

  Then, the procedure of the forward osmosis water processing method of this invention is demonstrated. FIG. 1 is a flowchart showing the processing procedure of the forward osmosis water treatment method of the present invention when a draw solution comprising the water-soluble compound of the present invention and water is used as the draw solution.

  First, the first step (S01) of preparing a draw solution by mixing the water-soluble compound of the present invention and water is performed. This first step (S01) can be omitted when the draw solution comprising the water-soluble compound of the present invention and water is used as the draw solution. Next, a second step (S02) is performed in which the draw solution and the supply solution are brought into contact with each other through the semipermeable membrane and the water in the supply solution is absorbed by the draw solution. Subsequently, the diluted draw solution that has absorbed moisture is heated to a temperature higher than the lower critical solution temperature (LCST), and the phase is separated into a high-concentration draw solution layer and an aqueous layer in an upper layer and a lower layer according to the density ( S03) is performed. Subsequently, a fourth step (S04) is performed in which the lower or upper water layer is recovered as clear water, and at the same time, the upper layer or lower layer highly concentrated draw solution layer is recovered.

  In the first step (S01), the water-soluble compound of the present invention and water are mixed at a predetermined composition ratio to prepare a draw solution. The water-soluble compound of the present invention can be used as it is as a draw solution without using water. The first step may be performed in a draw liquid preparation container or in a draw liquid / water separation system described later. Moreover, a high concentration draw solution can be prepared by using the water-soluble compound of the present invention mixed with water at an arbitrary ratio as a draw solute.

In the second step (S02), the draw solution and the supply solution are brought into contact with each other through the semipermeable membrane, so that the water in the supply solution is absorbed by the draw solution.
The supply solution is not particularly limited as long as it is necessary to remove water in the supply solution and concentrate other components. For example, seawater, various wastewaters, beverages, fruit juices, dilute containing useful substances A solution etc. can be mentioned.
The semipermeable membrane is not particularly limited, and a commercially available semipermeable membrane can be usually used.

  As described above, since the draw solution has a high osmotic pressure, moisture can be efficiently absorbed from the supply solution. Since the absorption of moisture from the supply solution having a low osmotic pressure into the draw solution having a high osmotic pressure occurs naturally by a phenomenon called forward osmosis, in the second step (S02), the water can be absorbed from the supply solution with low energy. . When the forward osmosis water treatment method of the present invention is used for the purpose of concentration of the feed solution, the feed solution that has been absorbed and concentrated in the second step is the target product. The second step is performed in the moisture absorption system.

  In the third step (S03), the diluted draw solution that has absorbed moisture is heated to a temperature higher than the lower critical solution temperature (LCST). By heating to a temperature higher than the lower critical solution temperature (LCST), the dilute draw solution is phase-separated into a high concentration draw solution and water. When the density of the high-concentration draw solution is smaller than 1.00, the lower layer is an aqueous layer and the upper layer is a high-concentration draw solution layer. When the density of the high-concentration draw solution is larger than 1.00, the lower layer is high. The concentration draw solution layer and the upper layer become an aqueous layer. The third step is performed in a draw liquid / water separation system.

  In the fourth step (S04), the lower or upper aqueous layer and the upper or lower high-concentration draw solution layer are separated. Since the draw solute is a liquid, this separation does not require a filtration system and can be easily separated by liquid separation. The high-concentration draw solution separated in the fourth step can be used as it is as the draw solution in the first step (S01).

  The aqueous layer separated in the fourth step is recovered as clear water. The clarified water obtained by the forward osmosis water treatment method of the present invention may contain a draw solute, and the clarified water undergoes further purification steps depending on the application. For example, the acquisition of pure water by distillation or reverse osmosis membrane. The impurity of the clear water of the present invention is only the draw solute, and the load on the apparatus is smaller than when pure water is obtained directly from the supply solution by distillation or reverse osmosis membrane. For example, there are advantages such as very small contamination of impurities during distillation, no corrosion of the apparatus, no distillation residue, and very little fouling and deterioration of the reverse osmosis membrane.

  FIG. 2 is a schematic view showing an example of an apparatus for carrying out the forward osmosis water treatment method of the present invention.

[Synthesis Example 1-1]
34.5 g of dipropylamine and 36.6 g of triethylamine were dissolved in 50 mL of dichloromethane. While this solution was cooled in an ice bath, a solution of 15.6 g of malonyl chloride dissolved in 30 mL of dichloromethane was added dropwise. Water was added to the reaction solution to separate the organic phase. The organic phase was washed twice with 2 mol / L hydrochloric acid and then once with a saturated aqueous sodium bicarbonate solution. The resulting solution was dehydrated with anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain 14.4 g of oily N, N, N ′, N′-tetrapropylmalonamide.
1H-NMR / CDCl3 δ / ppm: 3.35 (2H, s), 3.23 (8H, m), 1.56 (8H, m), 0.90 (12H, m)

[Synthesis Examples 1-2 to 1-10]
In the same manner as in Synthesis Example 1-1, from a predetermined amine, triethylamine, and a predetermined acid chloride,
Synthesis Example 1-2: N, N, N ′, N′-tetraisopropylmalonamide,
1H-NMR / CDCl3 δ / ppm: 3.90 (2H, m), 3.53 (2H, m), 3.35 (2H, s), 1.37 (12H, d), 1.21 (12H D)
Synthesis Example 1-3: N, N′-dipropylsuccinamide,
1H-NMR / CDCl3 δ / ppm: 6.68 (2H, brs), 3.19 (4H, q), 2.50 (4H, s), 1.51 (4H, m), 0.92 (6H , T)
Synthesis Example 1-4: N, N′-diisopropylsuccinamide,
1H-NMR / CDCl3 δ / ppm: 5.55 (2H, brs), 4.08 (2H, m), 2.50 (4H, s), 1.14 (12H, d)
Synthesis Example 1-5: N, N′-dibutylsuccinamide,
1H-NMR / CDCl3 δ / ppm: 6.87 (2H, brs), 3.22 (4H, q), 2.50 (4H, s), 1.52 (4H, m), 1.37 (4H , M), 0.91 (6H, t)
Synthesis Example 1-6: N, N, N ′, N′-tetraethylsuccinamide,
1H-NMR / CDCl3 δ / ppm: 3.38 (4H, q), 3.31 (4H, q), 2.50 (4H, s), 1.17 (3H, t), 1.11 (3H , T)
Synthesis Example 1-7: N, N, N ′, N′-tetrapropylsuccinamide,
1H-NMR / CDCl3 δ / ppm: 3.25 (4H, m), 3.19 (4H, m), 2.50 (4H, s), 1.58 (8H, m), 0.90 (12H) , M)
Synthesis Example 1-8: N, N, N ′, N′-tetraisopropylsuccinamide,
1H-NMR / CDCl3 δ / ppm: 3.90 (2H, m), 3.53 (2H, m), 2.50 (4H, s), 1.37 (12H, d), 1.21 (12H D)
Synthesis Example 1-9: N, N′-dipropyladipamide,
1H-NMR / CDCl3 δ / ppm: 6.03 (2H, brs), 3.27 (4H, m), 2.18 (4H, m), 1.64 (4H, m), 1.53 (4H , M), 0.92 (6H, t)
Synthesis Example 1-10: N, N, N ′, N′-tetraethyladipinamide,
1H-NMR / CDCl3 δ / ppm: 3.36 (4H, q), 3.30 (4H, q), 2.33 (4H, m), 1.70 (4H, m), 1.17 (6H) , T), 1.11 (6H, t)

[Synthesis Example 1-11]
24.9 g of triethylamine was dissolved in 183 mL of dimethylamine in tetrahydrofuran (2 mol / L) (corresponding to 16.5 g of dimethylamine). While this solution was cooled in an ice bath, a solution prepared by dissolving 5.2 g of cyclohexane-1,4-dicarbonyl chloride in 30 mL of dichloromethane was added dropwise. After the reaction solution was concentrated under reduced pressure, 50 mL of water and dichloromethane were added to separate the organic phase. The organic phase was washed twice with 2 mol / L hydrochloric acid and then once with a saturated aqueous sodium bicarbonate solution. After the resulting solution was dehydrated with anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure to obtain 10.8 g of oily N, N, N ′, N′-tetramethylcyclohexane-1,4-dicarboxamide.
1H-NMR / CDCl3 δ / ppm: 3.47 (12H, s), 2.38 (2H, m), 1.80 (4H, m), 1.55 (4H, m)

[Synthesis Examples 1-12 to 1-14]
In the same manner as in Synthesis Example 1-1, from a predetermined amine, triethylamine, and a predetermined acid chloride,
Synthesis Example 1-12: N, N, N ′, N′-tetraethylcyclohexane-1,4-dicarboxamide,
1H-NMR / CDCl3 δ / ppm: 3.36 (4H, q), 3.30 (4H, q), 2.38 (2H, m), 1.80 (4H, m), 1.55 (4H M), 1.17 (6H, t), 1.11 (6H, t)
Synthesis Example 1-13: N, N, N ′, N′-tetraethylphthalamide,
1H-NMR / CDCl3 δ / ppm: 7.40 (4H, m), 3.53 (4H, brs), 3.26 (4H, brs), 1.24 (6H, brs), 1.11 (6H) , Brs)
Synthesis Example 1-14: N, N, N ′, N′-tetraethylisophthalamide 1H-NMR / CDCl 3 δ / ppm: 7.36 (2H, m), 7.28 (2H, m), 3.48 (4H, q), 3.25 (4H, q), 1.20 (6H, t), 1.08 (6H, t)
Got.

[Synthesis Comparative Examples 1-1 and 1-2]
In the same manner as in Synthesis Example 1-1, from a predetermined amine, triethylamine, and a predetermined acid chloride,
Synthesis Comparative Example 1-1: N, N′-dipropylmalonamide,
1H-NMR / CDCl3 δ / ppm: 6.68 (2H, brs), 3.19 (4H, q), 3.35 (2H, s), 1.51 (4H, m), 0.92 (6H , T)
Synthesis Comparative Example 1-2: N, N, N ′, N′-tetrapropyladipamide,
1H-NMR / CDCl3 δ / ppm: 3.23 (8H, m), 2.18 (4H, m), 1.64 (4H, m), 1.56 (8H, m), 0.90 (12H) , M)
Got.

The types of amines and acid chlorides of Synthesis Examples 1-1 to 1-14 and Synthesis Comparative Examples 1-1 and 1-2, and the amounts of amine, triethylamine, acid chloride, and amide obtained are shown in Table 1-1. .

[Synthesis Example 2-1]
N, N-diethylethylenediamine 18.9 and 19.2 g of triethylamine were dissolved in 50 mL of dichloromethane. While this solution was cooled in an ice bath, a solution of 17.7 g of butyryl chloride dissolved in 30 mL of dichloromethane was added dropwise. Water was added to the reaction solution to separate the organic phase. The organic phase was washed twice with water and then once with saturated aqueous sodium bicarbonate solution. The obtained solution was dehydrated with anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure to obtain 14.4 g of oily N- (2- (diethylamino) ethyl) butanamide.
1H-NMR / CDCl3 δ / ppm: 7.50 (1H, brs), 3.29 (2H, 2.42 (2H, m), 2.17 (2H, t), 1.64 (2H, m) 1.04 (6H, t), 0.94 (3H, t)

[Synthesis Examples 2-2 to 2-11]
In the same manner as in Synthesis Example 2-1, from a predetermined amine, triethylamine, and a predetermined acid chloride,
Synthesis Example 2-2: N- (3- (dimethylamino) propyl) butanamide,
1H-NMR / CDCl3 δ / ppm: 7.50 (1H, brs), 3.31 (2H, m), 2.36 (2H, t), 2.23 (6H, s), 2.17 (2H , T), 1.64 (4H, m), 0.94 (3H, t)
Synthesis Example 2-3: N- (3- (diethylamino) propyl) butanamide,
1H-NMR / CDCl3 δ / ppm: 7.49 (1H, brs), 3.33 (2H, m), 2.52 (6H, m), 2.11 (2H, t), 1.64 (4H , M), 1.04 (6H, t), 0.94 (3H, t)
Synthesis Example 2-4: N- (2- (dimethylamino) ethyl) hexanamide,
1H-NMR / CDCl3 δ / ppm: 6.25 (1H, brs), 3.32 (2H, t), 2.40 (2H, t), 2.23 (6H, s), 2.18 (2H , M), 1.63 (2H, m), 1.30 (4H, m), 0.89 (3H, t)
Synthesis Example 2-5: N- (2- (diethylamino) ethyl) hexanamide,
1H-NMR / CDCl3 δ / ppm: 6.55 (1H, brs), 3.33 (2H, m), 2.52 (6H, m), 2.18 (2H, m), 1.63 (2H M), 1.30 (4H, m), 1.04 (6H, t), 0.89 (3H, t),
Synthesis Example 2-6: N- (3- (dimethylamino) propyl) hexanamide,
1H-NMR / CDCl3 δ / ppm: 7.19 (1H, brs), 3.31 (2H, m), 2.36 (2H, t), 2.23 (6H, s), 2.16 (2H , M), 1.64 (4H, m), 1.31 (4H, m), 0.89 (3H, t)
Synthesis Example 2-7: N- (3- (diethylamino) propyl) hexanamide,
1H-NMR / CDCl3 δ / ppm: 6.86 (1H, brs), 3.33 (2H, m), 2.52 (6H, m), 2.18 (2H, m), 1.63 (2H M), 1.30 (4H, m), 1.04 (6H, t), 0.89 (3H, t),
Synthesis Example 2-8: N- (2- (dimethylamino) ethyl) cyclohexanecarboxamide,
1H-NMR / CDCl3 δ / ppm: 6.08 (1H, brs), 3.31 (2H, t), 2.39 (2H, t), 2.22 (6H, s), 2.08 (1H , M), 1.82 (5H, m), 1.41 (5H, m)
Synthesis Example 2-9: N- (3- (dimethylamino) propyl) cyclohexanecarboxamide,
1H-NMR / CDCl3 δ / ppm: 7.09 (1H, brs), 3.32 (2H, t), 2.37 (2H, t), 2.23 (6H, s), 2.05 (1H , M), 1.78 (5H, m), 1.66 (2H, m) 1.29 (5H, m)
Synthesis Example 2-10: N- (2- (dimethylamino) ethyl) benzamide
1H-NMR / CDCl3 δ / ppm: 8.45 (1H, brs), 7.78 (2H, t), 7.10 (3H, m), 3.52 (2H, m), 2.45 (2H) , T), 2.26 (6H, s), 1.74 (2H, m)
Synthesis Example 2-11: N- (3- (dimethylamino) propyl) benzamide 1H-NMR / CDCl 3 δ / ppm: 7.80 (2H, t), 7.41 (3H, m), 7.10 ( 1H, brs), 3.50 (2H, m), 2.49 (2H, t), 2.24 (6H, s)
Got.

[Synthesis Comparative Examples 2-1 and 2-2]
In the same manner as in Synthesis Example 2-1, from a predetermined amine, triethylamine, and a predetermined acid chloride,
Synthesis Comparative Example 2-1: N- (3- (dimethylamino) propyl) propanamide,
1H-NMR / CDCl3 δ / ppm: 7.50 (1H, brs), 3.31 (2H, m), 2.36 (2H, t), 2.23 (6H, s), 2.15 (2H , Q), 1.14 (3H, t)
Synthesis Comparative Example 2-2: N- (3- (diethylamino) propyl) cyclohexanecarboxamide,
1H-NMR / CDCl3 δ / ppm: 6.86 (1H, brs), 3.33 (2H, m), 2.52 (6H, m), 2.05 (1H, m), 1.78 ( 5H, m), 1.66 (2H, m), 1.04 (6H, t), 1.29 (5H, m)
Got.

The types of amines and acid chlorides of Synthesis Examples 2-1 to 2-11 and Synthesis Comparative Examples 2-1 and 2-2, the amounts of amine, triethylamine, acid chloride, and amide obtained are shown in Table 1-2. .

[Synthesis Example 3-1]
14.8 g of triethylamine was dissolved in 124 mL of ethylamine in tetrahydrofuran (2 mol / L) (equivalent to 11.2 g of ethylamine). While this solution was cooled in an ice bath, a solution of 10.0 g of benzene-1,3,5-tricarbonyl chloride dissolved in 30 mL of dichloromethane was added dropwise. After the reaction solution was concentrated under reduced pressure, 50 mL of water and dichloromethane were added to separate the organic phase. The organic phase was washed twice with 2 mol / L hydrochloric acid and then once with a saturated aqueous sodium bicarbonate solution. The resulting solution was dehydrated with anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain 8.4 g of N, N ′, N ″ -triethylbenzene-1,3,5-tricarboxamide.
1H-NMR / CDCl3 δ / ppm: 8.47 (3H, d), 8.30 (3H, s), 3.47 (6H, m), 1.27 (9H, t)

[Synthesis Example 3-2]
Propylamine (13.2 g) and triethylamine (14.8 g) were dissolved in dichloromethane (50 mL). While this solution was cooled in an ice bath, a solution obtained by dissolving 10.4 g of benzene-1,3,5-tricarbonyl chloride in 30 mL of dichloromethane was added dropwise. Water was added to the reaction solution to separate the organic phase. The organic phase was washed twice with 2 mol / L hydrochloric acid and then once with a saturated aqueous sodium bicarbonate solution. The obtained solution was dehydrated with anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain 14.4 g of N, N ′, N ″ -tripropylbenzene-1,3,5-tricarboxamide.
1H-NMR / CDCl3 δ / ppm: 8.48 (3H, d), 8.31 (3H, s), 3.24 (6H, m), 1.54 (6H, m), 0.92 (9H , T)
[Synthesis Example 3-3]
N, N, N ′, N ′, N “N” -hexaethylbenzene-1,3,5-tricarboxamide from a predetermined amine, triethylamine, and a predetermined acid chloride in the same manner as in Synthesis Example 3-2 ,
1H-NMR / CDCl3 δ / ppm: 7.27 (3H, s), 3.54 (6H, brs), 3.27 (6H, brs), 1.23 (9H, brs), 1.11 (9H , Brs)

[Synthesis Example 3-4]
In the same manner as in Synthesis Example 3-1, N, N ′, N ″ -triethylbenzene-1,2,4-tricarboxamide 1H— was prepared from ethylamine, triethylamine, and benzene-1,2,4-tricarbonyl chloride. NMR / CDCl3 δ / ppm: 8.47 (3H, brs), 8.43 (1H, m) 8.20 (H, m), 8.01 (1H, m), 3.48 (6H, m) 1.28 (9H, m)
Got

[Synthesis Examples 3-5 and 3-6]
In the same manner as in Synthesis Example 3-2, from a predetermined amine, triethylamine, and a predetermined acid chloride,
Synthesis Example 3-5: N, N ′, N ″ -tripropylbenzene-1,2,4-tricarboxamide,
1H-NMR / CDCl3 δ / ppm: 8.47 (3H, brs), 8.43 (1H, m) 8.20 (H, m), 8.01 (1H, m), 3.24 (6H, m), 1.54 (6H, m), 0.92 (9H, t)
Synthesis Example 3-6: N, N, N ′, N ′, N “N” -hexaethylbenzene-1,2,4-tricarboxamide,
1H-NMR / CDCl3 δ / ppm: 8.47 (3H, brs), 8.43 (1H, m) 8.20 (H, m), 8.01 (1H, m), 3.54 (6H, brs), 3.27 (6H, brs), 1.23 (9H, brs), 1.11 (9H, brs)
Got.

[Synthesis Comparative Example 3-1]
14.8 g of triethylamine was dissolved in 124 mL of methylamine in tetrahydrofuran (2 mol / L) (equivalent to 7.7 g of methylamine). While this solution was cooled in an ice bath, a solution obtained by dissolving 10.4 g of benzene-1,3,5-tricarbonyl chloride in 30 mL of dichloromethane was added dropwise. After the reaction solution was concentrated under reduced pressure, 50 mL of water and dichloromethane were added to separate the organic phase. The organic phase was washed twice with 2 mol / L hydrochloric acid and then once with a saturated aqueous sodium bicarbonate solution. The obtained solution was dehydrated with anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain 7.1 g of N, N ′, N ″ -trimethylbenzene-1,3,5-tricarboxamide.
1H-NMR / CDCl3 δ / ppm: 8.47 (3H, d), 8.30 (3H, s), 3.01 (9H, s),

[Synthesis Comparative Example 3-2]
In the same manner as in Synthesis Example 3-2, N, N, N ′, N ′, N “N” -hexapropylbenzene-1,3,5-trimethyl is obtained from a predetermined amine, triethylamine, and a predetermined acid chloride. 12.5 g of carboxamide was obtained.
1H-NMR / CDCl3 δ / ppm: 8.30 (3H, s), 3.17 (12H, t), 1.49 (12H, m), 0.92 (18H, d)

The types of amines and acid chlorides of Synthesis Examples 3-1 to 3-6 and Synthesis Comparative Examples 3-1 and 3-2, and the amounts of amine, triethylamine, acid chloride, and amide obtained are shown in Table 1-3. .

[Phase Separation Example 1-1]
5 g of N, N, N ′, N′-tetrapropylmalonamide obtained in Synthesis Example 1-1 and 5 g of water were placed in a 30 ml screw tube and mixed by shaking at 20 ° C. by hand. This mixed liquid maintained a uniform appearance even after the flow stopped. Changes in the appearance were observed while heating the mixture. The lower critical solution temperature (LCST) at which the mixed solution did not show a uniform appearance was 49 ° C. The N, N, N ′, N′-tetrapropylmalonamide concentration in the organic phase at 60 ° C. was 72%, and the N, N, N ′, N′-tetrapropylmalonamide concentration in the aqueous phase was 20%.

[Phase Separation Examples 1-2 to 1-14]
Phase separation In the same manner as in Example 1-1, phase separation was evaluated using 5 g of a predetermined amide and 5 g of water.
[Phase separation comparative example 1-1]
5 g of N, N′-dipropylmalonamide obtained in Synthesis Comparative Example 1-1 and 5 g of water were placed in a 30 ml screw tube and mixed by shaking at 20 ° C. by hand. This mixed liquid maintained a uniform appearance even after the flow stopped. Changes in the appearance were observed while heating the mixture. The mixture was heated to 90 ° C., but phase separation did not occur while maintaining a uniform appearance.

[Phase separation comparative example 1-2]
5 g of N, N, N ′, N′-tetrapropyladipinamide obtained in Synthesis Comparative Example 1-2 and 5 g of water were placed in a 30 ml screw tube and mixed by shaking at 20 ° C. by hand. Even after the flow stopped, this mixed liquid did not show a uniform appearance and remained phase-separated.

Table 2-1 shows the appearance of Phase Separation Examples 1-1 to 1-14 and Phase Separation Comparative Examples 1-1 and 1-2 at 20 ° C., LCST, amide concentrations of organic phase and aqueous phase at 60 ° C. or predetermined temperature. It was described in.

[Phase Separation Examples 2-1 to 2-11]
Phase separation In the same manner as in Example 1-1, phase separation was evaluated using 5 g of a predetermined amide and 5 g of water.

[Phase separation comparative example 2-1]
5 g of N- (3- (dimethylamino) propyl) propanamide obtained in Synthesis Comparative Example 2-1 and 5 g of water were put in a 30 ml screw tube and mixed by shaking at 20 ° C. by hand. This mixed liquid maintained a uniform appearance even after the flow stopped. Changes in the appearance were observed while heating the mixture. The mixture was heated to 90 ° C., but phase separation did not occur while maintaining a uniform appearance.

[Phase separation comparative example 2-2]
5 g of N- (3- (diethylamino) propyl) cyclohexanecarboxamide obtained in Synthesis Comparative Example 2-2 and 5 g of water were placed in a 30 ml screw tube and mixed by shaking at 20 ° C. by hand. Even after the flow stopped, this mixed liquid did not show a uniform appearance and remained phase-separated.

Table 2-2 shows the appearance at 20 ° C., LCST, 60 ° C. or the amide concentrations of the organic phase and the aqueous phase at 20 ° C. in Phase Separation Examples 2-1 to 2-11 and Phase Separation Comparative Examples 2-1 and 2-2. It was described in.

[Phase Separation Examples 3-1 to 3-6]
Phase separation In the same manner as in Example 1-1, phase separation was evaluated using 5 g of a predetermined amide and 5 g of water.

[Phase separation comparative example 3-1]
5 g of N, N ′, N ″ -trimethylbenzene-1,3,5-tricarboxamide obtained in Synthesis Comparative Example 3-1 and 5 g of water are placed in a 30 ml screw tube and mixed by shaking at 20 ° C. by hand. The mixed liquid maintained a uniform appearance even after the flow stopped, and the change in the appearance was observed while the mixed liquid was heated. Not separated.

[Phase separation comparative example 3-2]
N, N, N ', N', N "N" -hexapropylbenzene-1,3,5-tricarboxamide 5 g obtained in Synthesis Comparative Example 3-2 and 5 g of water were placed in a 30 ml screw tube. Shake and mix by hand at 20 ° C. Even after the flow stopped, this mixed liquid did not show a uniform appearance and remained phase-separated.

Table 2-3 shows the appearance at 20 ° C. of the phase separation examples 3-1 to 3-6 and the phase separation comparative examples 3-1, 3-2, LCST, amide concentrations of the organic phase and the aqueous phase at 60 ° C. or a predetermined temperature. It was described in.

[Water absorption example 1-1]
2 g of a 70% aqueous solution of N, N, N ′, N′-tetrapropylmalonamide obtained in Synthesis Example 1-1 was placed in a petri dish having a bottom area of 8 cm 2. 10 mL of water was placed in a petri dish having a bottom area of 8 cm2. Two petri dishes were placed in the same sealed container and left at room temperature for 17 hours. The amount of N, N, N ′, N′-tetrapropylmalonamide aqueous solution was 2.4 g.

[Water absorption examples 1-2 to 1-14, 2-1 to 2-11, 3-1 to 3-6]
Water absorption The water absorption of a predetermined amide was evaluated in the same manner as in Example 1-1.
Table 3-1 shows the amide aqueous solution concentration, amide aqueous solution initial weight, and amide aqueous solution initial weight after water absorption in Examples 1-1 to 1-14. The weight and the weight after absorption of the amide aqueous solution are shown in Table 3-2. The concentration of the amide aqueous solution, the initial weight of the amide aqueous solution, and the weight after absorption of the amide aqueous solution are shown in Table 3-3.

[Normal osmosis water absorption Example 1-1]
30 ml of 70% aqueous solution (calculated osmotic pressure 12 MPa) of N, N, N ′, N′-tetrapropylmalonamide obtained in Synthesis Example 1 and 30 ml of 3.5% saline (calculated osmotic pressure 2.9 MPa) Were brought into contact with each other via a cellophane sheet “wrap-in cello pack” manufactured by Horiaki Co., Ltd. having an area of 28 cm 2. After 17 hours, the aqueous N, N, N ′, N′-tetrapropylmalonamide solution was 50 ml and the saline solution was 10 ml.

[Normal osmosis water absorption Examples 1-2 to 1-14, 2-1 to 2-11, 3-1 to 3-6]
Forward osmosis water absorption The forward osmosis water absorption of a predetermined amide was evaluated in the same manner as in Example 1-1.
Table 4-1 shows the concentration of amide aqueous solution, the volume of amide aqueous solution after water absorption, and the volume of saline solution after water absorption in forward osmosis water absorption Examples 1-1 to 1-14. Table 4-2 shows the concentration, the volume of the amide after water absorption, and the volume of the saline after water absorption. 4-3.

The water absorbing liquid of the present invention is used for an air conditioner, a dehumidifier, and the like.
The forward osmosis water treatment method using the draw solution of the present invention is the recovery of drinking water, industrial water or agricultural water from seawater or wastewater, volume reduction of wastewater, forward osmosis power generation, concentration of favorite beverages, concentration of fruit juice, Used for concentration of dilute solutions containing useful substances.

Claims (7)

The water-absorbing solution, which has absorbed water and becomes a dilute solution due to contact with a gas containing water, and has a reduced ability to absorb water, is phase-separated by heating to a temperature higher than the lower critical solution temperature, and the liquid-liquid A water absorbing liquid that can be regenerated by separating water by separating the liquid and increasing the concentration of the water absorbing liquid. The water absorbing liquid is represented by general formula (1), general formula (2), and general formula (3). Or any one or more of the water-soluble compounds represented by general formula (1), general formula (2) and general formula (3), and water. Water absorption liquid.

[Wherein, R2 and R3 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, and R4 represents a linear or cyclic alkylene group having 1 to 6 carbon atoms or Represents a phenylene group, and the sum of carbon numbers of R2, R3, and R4 is 8-14. ]

[Wherein R 1 represents a linear or branched alkyl group having 3 to 6 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms, or an optionally substituted phenyl group, and R 2 represents a hydrogen atom, carbon Represents a linear or branched alkyl group having 1 to 3 carbon atoms, R5 represents a linear alkylene group having 1 to 4 carbon atoms, R6 and R7 are each independently a hydrogen atom, 1 to 4 carbon atoms. The sum of the carbon number of R1, R2, R5, R6, R7 is 8-12. ]

[Wherein, R2 and R3 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, R4 represents a benzenetriyl group, and the sum of carbon numbers of R2 and R3. Is 6-12. ]   The water-soluble compound represented by the general formula (1) is N, N, N ′, N′-tetrapropylmalonamide, N, N, N ′, N′-tetraisopropylmalonamide, N, N′-dipropylsuccin. Amides, N, N′-diisopropylsuccinamide, N, N′-dibutylsuccinamide, N, N, N ′, N′-tetraethylsuccinamide, N, N, N ′, N′-tetrapropylsuccinamide Synamide, N, N, N ′, N′-tetraisopropylsuccinamide, N, N′-dipropyladipinamide, N, N, N ′, N′-tetraethyladipinamide, N, N, N ′, N′-tetramethylcyclohexane-1,4-dicarboxamide, N, N, N ′, N′-tetraethylcyclohexane-1,4-didicarboxamide, N, N, N ′, N′-tetraethylphthal Amide, N, N, N ', water absorption solution according to claim 1, characterized in that either N'- tetraethyl isophthalamide.   The water-soluble compound of the general formula (2) is N- (2- (diethylamino) ethyl) butanamide, N- (3- (dimethylamino) propyl) butanamide, N- (3- (diethylamino) propyl) butanamide, N -(2- (dimethylamino) ethyl) hexanamide, N- (2- (diethylamino) ethyl) hexanamide, N- (3- (dimethylamino) propyl) hexanamide, N- (3- (diethylamino) propyl) Hexanamide, N- (2- (dimethylamino) ethyl) cyclohexanecarboxamide, N- (3- (dimethylamino) propyl) cyclohexanecarboxamide, N- (2- (dimethylamino) ethyl) benzamide, N- (3- ( It is one of dimethylamino) propyl) benzamide Water absorbing solution according to Motomeko 1.   The water-soluble compound of the general formula (3) is N, N ′, N ″ -triethylbenzene-1,3,5-tricarboxamide, N, N ′, N ″ -tripropylbenzene-1,3,5- Tricarboxamide, N, N, N ', N', N "N" -hexaethylbenzene-1,3,5-tricarboxamide, N, N ', N "-triethylbenzene-1,2,4-tricarboxamide, N, N ', N "-tripropylbenzene-1,2,4-tricarboxamide, N, N, N', N ', N" N "-hexaethylbenzene-1,2,4-tricarboxamide The water absorbing liquid according to claim 1, wherein   A draw solution that is brought into contact with a water-containing solution through a semipermeable membrane, wherein the draw solution comprises the water-absorbing solution according to claim 1.   A forward osmosis water treatment method, wherein the draw solution is absorbed by the draw solution by bringing the draw solution according to claim 5 into contact with the supply solution containing moisture through a semipermeable membrane. Dilute draw solution that has absorbed moisture from the supply solution is phase-separated by heating to a temperature higher than the lower critical solution temperature, and water is separated by liquid-liquid separation to increase the concentration and regenerate the draw solution. The forward osmosis water treatment method according to claim 6.

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