JP2018008228A - Drive solution for positive-osmotic pressure utilization system and drive solution regeneration method - Google Patents

Drive solution for positive-osmotic pressure utilization system and drive solution regeneration method Download PDF

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JP2018008228A
JP2018008228A JP2016139271A JP2016139271A JP2018008228A JP 2018008228 A JP2018008228 A JP 2018008228A JP 2016139271 A JP2016139271 A JP 2016139271A JP 2016139271 A JP2016139271 A JP 2016139271A JP 2018008228 A JP2018008228 A JP 2018008228A
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隆志 宮田
Takashi Miyata
隆志 宮田
暁文 河村
Akifumi Kawamura
暁文 河村
高典 中里
Takanori Nakazato
高典 中里
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Kansai University
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

PROBLEM TO BE SOLVED: To provide a drive solution having a possibility of sufficiently suppressing energy consumption during concentration and regeneration in a positive-osmotic pressure utilization system.SOLUTION: The drive solution according to the present invention is a drive solution for a positive-osmotic pressure utilization system 100 and has a lower critical solution temperature, and comprises as a solute a polymer which reversibly shifts the lower limit critical solution temperature in response to light in a specific wavelength range. In the drive solution, the polymer preferably has a photoresponsive group that reversibly becomes hydrophobic and hydrophilic in response to light in the specific wavelength range. In such a case, the lower critical solution temperature reversibly shifts in accordance with the hydrophobilization and hydrophilization of the photoresponsive group.SELECTED DRAWING: Figure 9

Description

本発明は、正浸透圧利用システムの駆動溶液およびその再生方法に関する。 The present invention relates to a driving solution for a forward osmotic pressure utilization system and a regeneration method thereof.

従前から正浸透圧を利用した水処理システムや浸透圧発電システム等(以下これらのシステムをまとめて「正浸透圧利用システム」と称する。)が提案されている。   Conventionally, water treatment systems using osmotic pressure, osmotic pressure power generation systems, and the like (hereinafter these systems are collectively referred to as “positive osmotic pressure utilization system”) have been proposed.

ところで、近年、このよう正浸透圧利用システムにおいて、曇点を有する感温性高分子と塩析効果物質とを含有する溶液を駆動溶液として利用することが提案されている(例えば、特開2016−067989号公報等参照。)。このような正浸透圧利用システムでは、浸透水で希釈された駆動溶液を曇点以上に加熱して「感温性高分子を高濃度に含有する駆動溶液相」と「浸透水を主とする水相」との二相に分離させた後、水相を取り除き、残った駆動溶液相を曇点以下に冷却して感温性高分子を再溶解させることによって駆動溶液を再生する。   In recent years, it has been proposed to use a solution containing a temperature-sensitive polymer having a cloud point and a salting-out effect substance as a driving solution in such a forward osmotic pressure utilization system (for example, JP-A-20162016). -See Japanese Patent No. 0667989). In such a system using forward osmotic pressure, a driving solution diluted with osmotic water is heated to a cloud point or higher to produce a “driving solution phase containing a temperature-sensitive polymer at a high concentration” and “osmotic water as a main component. After separation into two phases, “aqueous phase”, the aqueous phase is removed, the remaining driving solution phase is cooled below the cloud point, and the temperature sensitive polymer is re-dissolved to regenerate the driving solution.

特開2016−067989号公報Japanese Patent Application Laid-Open No. 2006-067989

ところが、上述のような正浸透圧利用システムでは、上述の通り、駆動溶液の濃縮時に駆動溶液を加熱する必要があると共に、駆動溶液の再生時に駆動溶液を冷却する必要がある。したがって、この駆動溶液では、正浸透圧利用システムにおけるエネルギー消費量を十分に抑制することは極めて難しい。   However, in the system using positive osmotic pressure as described above, it is necessary to heat the driving solution when the driving solution is concentrated, and it is necessary to cool the driving solution when the driving solution is regenerated. Therefore, with this driving solution, it is extremely difficult to sufficiently suppress the energy consumption in the forward osmotic pressure utilization system.

本発明の課題は、正浸透圧利用システムにおいて濃縮時および再生時にエネルギー消費量を十分に抑制することができる可能性を秘めた駆動溶液を提供することである。   An object of the present invention is to provide a driving solution having a possibility of sufficiently suppressing energy consumption during concentration and regeneration in a system using forward osmotic pressure.

本発明の一局面に係る駆動溶液は、正浸透圧利用システムの駆動溶液(ドロー溶液と称されることもある。)であって、「特定波長域の光に応答して可逆的に下限臨界溶液温度をシフトする高分子」を溶質として含有する。なお、以下、説明の便宜上、このような高分子を「LCST光シフト高分子」と称する。また、この駆動溶液には、本発明の趣旨を損ねない範囲で他の成分が含まれていてもよい。   A driving solution according to one aspect of the present invention is a driving solution for a system using a forward osmotic pressure (sometimes referred to as a draw solution), which is reversibly lower critical in response to light in a specific wavelength range. "Polymer that shifts solution temperature" is contained as a solute. Hereinafter, for convenience of explanation, such a polymer is referred to as “LCST light shift polymer”. Further, the driving solution may contain other components as long as the gist of the present invention is not impaired.

この駆動溶液では、例えば、第1特定波長域の光が照射されると下限臨界溶液温度が低温側にシフトし、第2特定波長域の光が照射されると下限臨界溶液温度が高温側にシフトする。このため、この駆動溶液の温度を低温側の下限臨界溶液温度と高温側の下限臨界溶液温度との間に設定することができれば、特定波長域の光を選択的に照射することによって駆動溶液中の高分子を沈殿させたり再溶解させたりすることができる。そして、例えば、高温側および低温側の下限臨界溶液温度を共に室温付近に設定することができれば、駆動溶液の温調が不要となり、延いては正浸透圧利用システムにおいて駆動溶液を濃縮および再生する際のエネルギー消費量を十分に抑制することができる。また、下限臨界溶液温度をシフトさせるためのエネルギーが光であるため、エネルギー源として比較的低消費電力の発光ダイオード(LED)を利用することができる。このため、この駆動溶液を利用することによって正浸透圧利用システムにおいて駆動溶液を濃縮および再生する際のエネルギー消費量を十分に抑制することができる。さらに、第1特定波長域の光および第2特定波長域の光のいずれか一方の光を可視光とすることができれば、その光の光源として自然エネルギーである太陽光を利用することができ、上述のエネルギー消費量をさらに抑制することができる。したがって、本発明の一局面に係る駆動溶液は、正浸透圧利用システムにおいて駆動溶液の濃縮時および再生時にエネルギー消費量を十分に抑制することができる可能性を秘めている。   In this driving solution, for example, when the light in the first specific wavelength region is irradiated, the lower critical solution temperature shifts to the low temperature side, and when the light in the second specific wavelength region is irradiated, the lower critical solution temperature increases to the high temperature side. shift. For this reason, if the temperature of the driving solution can be set between the lower critical solution temperature on the low temperature side and the lower critical solution temperature on the high temperature side, the light in the specific wavelength region is selectively irradiated in the driving solution. The polymer can be precipitated or redissolved. For example, if the lower critical solution temperature on both the high temperature side and the low temperature side can be set to around room temperature, the temperature control of the driving solution becomes unnecessary, and the driving solution is concentrated and regenerated in the forward osmotic pressure utilization system. Energy consumption can be sufficiently suppressed. Moreover, since the energy for shifting the lower critical solution temperature is light, a relatively low power consumption light emitting diode (LED) can be used as an energy source. For this reason, the energy consumption at the time of concentrating and reproducing | regenerating a drive solution in a forward osmotic pressure utilization system by using this drive solution can fully be suppressed. Furthermore, if any one of the light in the first specific wavelength region and the light in the second specific wavelength region can be made visible light, sunlight that is natural energy can be used as the light source of the light, The above-mentioned energy consumption can be further suppressed. Therefore, the driving solution according to one aspect of the present invention has the potential to sufficiently suppress the energy consumption during concentration and regeneration of the driving solution in the forward osmotic pressure utilization system.

ところで、上述の駆動溶液において、LCST光シフト高分子は、特定波長域の光に応答して可逆的に疎水化あるいは親水化する光応答基を有することが好ましい。かかる場合、下限臨界溶液温度は、光応答基の疎水化あるいは親水化に応じて可逆的にシフトする。なお、具体的には、この高分子の光応答基は、第1特定波長域の光に応答して疎水化し、第2特定波長域の光に応答して親水化する。ここで、第1特定波長域と第2特定波長域とは異なる波長領域であり、重複していないことが好ましいが、一部重複していてもかまわない。また、ここで、光応答基は、特定波長域の光に応答して可逆的にイオン化および非イオン化することが好ましい。かかる場合、下限臨界溶液温度は、光応答基のイオン化および非イオン化に応じて可逆的にシフトすることになる。   By the way, in the driving solution described above, the LCST light-shifting polymer preferably has a photoresponsive group that reversibly becomes hydrophobic or hydrophilic in response to light in a specific wavelength range. In such a case, the lower critical solution temperature is reversibly shifted according to the hydrophobicity or hydrophilicity of the photoresponsive group. Specifically, the photoresponsive group of the polymer is hydrophobized in response to light in the first specific wavelength region and is hydrophilized in response to light in the second specific wavelength region. Here, the first specific wavelength range and the second specific wavelength range are different wavelength ranges and preferably do not overlap, but may partially overlap. Here, the photoresponsive group is preferably ionized and non-ionized reversibly in response to light in a specific wavelength range. In such a case, the lower critical solution temperature shifts reversibly according to the ionization and non-ionization of the photoresponsive group.

上述の駆動溶液において、正浸透圧利用システムが浸透圧発電システムである場合、LCST光シフト高分子は、メトキシポリ(エチレングリコール)メタクリレートとスピロピランメタクリレートのビニル共重合体であることが好ましい。このビニル共重合体は、駆動溶液の浸透圧を高めることができるからである。   In the above driving solution, when the forward osmotic pressure utilization system is an osmotic pressure power generation system, the LCST light-shifting polymer is preferably a vinyl copolymer of methoxypoly (ethylene glycol) methacrylate and spiropyran methacrylate. This is because this vinyl copolymer can increase the osmotic pressure of the driving solution.

本発明の他の局面に係る正浸透圧利用システムの駆動溶液の再生方法は、沈殿工程、排出工程および再生工程を備える。沈殿工程では、上述の駆動溶液に第1特定波長域の光が照射されることによって下限臨界溶液温度が低温側にシフトし、その結果、LCST光シフト高分子が沈殿する。排出工程では、LCST光シフト高分子が沈殿した状態の駆動溶液から液体の一部が排出される。なお、この液体の一部には、正浸透圧利用後の駆動溶液よりも低濃度のLCST光シフト高分子が含まれていてもかまわない。再生工程では、LCST光シフト高分子の沈殿物に第2特定波長域の光が照射されることによって下限臨界溶液温度が高温側にシフトし、その結果、駆動溶液が再生される。   A driving solution regeneration method for a forward osmotic pressure utilization system according to another aspect of the present invention includes a precipitation step, a discharge step, and a regeneration step. In the precipitation step, the lower critical solution temperature is shifted to a lower temperature side by irradiating the above-mentioned driving solution with light in the first specific wavelength region, and as a result, the LCST light-shifted polymer is precipitated. In the discharging step, a part of the liquid is discharged from the driving solution in a state where the LCST light shift polymer is precipitated. In addition, a part of this liquid may contain LCST light shift polymer having a lower concentration than the driving solution after using the forward osmotic pressure. In the regeneration step, the LCST light-shifting polymer precipitate is irradiated with light in the second specific wavelength region, whereby the lower critical solution temperature is shifted to a higher temperature side, and as a result, the driving solution is regenerated.

このため、この駆動溶液の再生方法では、例えば、高温側および低温側の下限臨界溶液温度を共に室温付近に設定することができれば、駆動溶液の温調が不要となり、延いては正浸透圧利用システムにおいて駆動溶液を濃縮および再生する際のエネルギー消費量を十分に抑制することができる。また、下限臨界溶液温度をシフトさせるためのエネルギーが光であるため、エネルギー源として比較的低消費電力の発光ダイオード(LED)を利用することができる。このため、この駆動溶液の再生方法を利用することによって正浸透圧利用システムにおいて駆動溶液を濃縮および再生する際のエネルギー消費量を十分に抑制することができる。さらに、第1特定波長域の光および第2特定波長域の光のいずれか一方の光を可視光とすることができれば、その光の光源として自然エネルギーである太陽光を利用することができ、上述のエネルギー消費量をさらに抑制することができる。したがって、本発明の他の局面に係る駆動溶液の再生方法は、正浸透圧利用システムにおいて駆動溶液の濃縮時および再生時にエネルギー消費量を十分に抑制することができる可能性を秘めている。   For this reason, in this regeneration method of the driving solution, for example, if the lower critical solution temperature on both the high temperature side and the low temperature side can be set to around room temperature, the temperature control of the driving solution becomes unnecessary, and thus the forward osmotic pressure is used. Energy consumption when the driving solution is concentrated and regenerated in the system can be sufficiently suppressed. Moreover, since the energy for shifting the lower critical solution temperature is light, a relatively low power consumption light emitting diode (LED) can be used as an energy source. For this reason, by using this driving solution regeneration method, it is possible to sufficiently suppress the energy consumption when the driving solution is concentrated and regenerated in the forward osmotic pressure utilization system. Furthermore, if any one of the light in the first specific wavelength region and the light in the second specific wavelength region can be made visible light, sunlight that is natural energy can be used as the light source of the light, The above-mentioned energy consumption can be further suppressed. Therefore, the method for regenerating the driving solution according to another aspect of the present invention has the potential to sufficiently suppress the energy consumption during the concentration and regeneration of the driving solution in the forward osmotic pressure utilization system.

本発明の実施の形態の一応用例に係る浸透圧発電システムの模式図である。It is a schematic diagram of an osmotic pressure power generation system according to an application example of an embodiment of the present invention. 実施例1に係る5.0mg/mlのP(NIPAAm−co−SPAA)水溶液に対して波長254nmの紫外光を所定時間照射した際の紫外可視吸収スペクトル変化を示す図である。It is a figure which shows the ultraviolet visible absorption spectrum change at the time of irradiating the ultraviolet light of wavelength 254nm with respect to the 5.0 mg / ml P (NIPAAm-co-SPAA) aqueous solution which concerns on Example 1 for a predetermined time. 実施例1に係る5.0mg/mlのP(NIPAAm−co−SPAA)水溶液に対して波長400nm以上の可視光を所定時間照射した際の紫外可視吸収スペクトル変化を示す図である。It is a figure which shows the ultraviolet visible absorption spectrum change at the time of irradiating visible light with a wavelength of 400 nm or more to the 5.0 mg / ml P (NIPAAm-co-SPAA) aqueous solution which concerns on Example 1 for a predetermined time. 実施例1に係るP(NIPAAm−co−SPAA)水溶液の光線透過率の温度依存性を示す図である。It is a figure which shows the temperature dependence of the light transmittance of P (NIPAAm-co-SPAA) aqueous solution which concerns on Example 1. FIG. 実施例1に係るP(NIPAAm−co−SPAA)水溶液に29℃で波長400nm以上の可視光を10秒照射した際の写真図である。It is a photograph figure at the time of irradiating the P (NIPAAm-co-SPAA) aqueous solution which concerns on Example 1 with visible light with a wavelength of 400 nm or more at 29 degreeC for 10 second. 実施例1に係るP(NIPAAm−co−SPAA)水溶液の圧力差の経時変化を示す図である。It is a figure which shows the time-dependent change of the pressure difference of P (NIPAAm-co-SPAA) aqueous solution which concerns on Example 1. FIG. 実施例2に係る5.0mg/mlのP(PEGMA−co−SPMA)水溶液に対して波長254nmの紫外光を所定時間照射した際の紫外可視吸収スペクトル変化を示す図である。It is a figure which shows the ultraviolet visible absorption spectrum change at the time of irradiating ultraviolet light with a wavelength of 254 nm with respect to the 5.0 mg / ml P (PEGMA-co-SPMA) aqueous solution which concerns on Example 2 for a predetermined time. 実施例2に係る5.0mg/mlのP(PEGMA−co−SPMA)水溶液に対して波長400nm以上の可視光を所定時間照射した際の紫外可視吸収スペクトル変化を示す図である。It is a figure which shows the ultraviolet visible absorption spectrum change at the time of irradiating visible light with a wavelength of 400 nm or more with respect to the 5.0 mg / ml P (PEGMA-co-SPMA) aqueous solution which concerns on Example 2 for a predetermined time. 実施例2に係るP(PEGMA−co−SPMA)水溶液の光線透過率の温度依存性を示す図である。It is a figure which shows the temperature dependence of the light transmittance of P (PEGMA-co-SPMA) aqueous solution which concerns on Example 2. FIG. 実施例2に係るP(PEGMA−co−SPMA)水溶液に42℃で波長400nm以上の可視光を30秒照射した際の写真図である。It is a photograph at the time of irradiating visible light with a wavelength of 400 nm or more for 30 second at 42 degreeC to P (PEGMA-co-SPMA) aqueous solution which concerns on Example 2. FIG. 実施例2に係るP(PEGMA−co−SPMA)水溶液の圧力差の経時変化を示す図である。FIG. 5 is a graph showing the change over time in the pressure difference of an aqueous P (PEGMA-co-SPMA) solution according to Example 2.

<正浸透圧利用システムの駆動溶液の構成>
本発明の実施の形態に係る正浸透圧利用システムの駆動溶液は、主に、LCST光シフト高分子および溶媒から構成されている。なお、ここで、「正浸透圧利用システム」には、例えば、浸透圧発電システムや、海水の淡水化システム、排水処理システム、ジュース等の飲食品の濃縮システム等が含まれ得る。また、この駆動溶液には、本発明の趣旨の範囲を逸脱しない範囲で他の成分が含まれていてもかまわない。以下、このLCST光シフト高分子および溶媒それぞれについて詳述する。
<Configuration of driving solution for forward osmotic pressure system>
The driving solution of the forward osmotic pressure utilization system according to the embodiment of the present invention is mainly composed of an LCST light shift polymer and a solvent. Here, the “forward osmotic pressure utilization system” may include, for example, an osmotic pressure power generation system, a seawater desalination system, a wastewater treatment system, a concentration system for food and drink such as juice. Further, the driving solution may contain other components without departing from the scope of the gist of the present invention. Hereinafter, each of the LCST light-shifting polymer and the solvent will be described in detail.

(1)LCST光シフト高分子
本発明の実施の形態に係るLCST光シフト高分子は、異なる2つ以上の特定波長域の光に応答して可逆的に下限臨界溶液温度(LCST:Lower Critical Solution Temperature)をシフトさせる性質を有する高分子であって、例えば、異なる2つ以上の特定波長域の光に応答して可逆的に疎水化あるいは親水化する光応答基を有する高分子等が挙げられる。なお、このような光応答基としては、異なる2つ以上の特定波長域の光に応答して可逆的にイオン化および非イオン化する官能基やシス−トランス異性化する官能基、例えば、以下の化学式に示されるようなスピロピラン基(可逆的に双性イオン化/非イオン化する)やアゾベンゼン基等が挙げられる。
(1) LCST light-shifting polymer The LCST light-shifting polymer according to an embodiment of the present invention is reversibly reduced in response to light in two or more different specific wavelength ranges (LCST: Lower Critical Solution Temperature). (Temperature) is a polymer having a property of shifting, for example, a polymer having a photoresponsive group that reversibly becomes hydrophobic or hydrophilic in response to light of two or more different specific wavelength ranges. . In addition, as such a photoresponsive group, a functional group that reversibly ionizes and deionizes in response to light of two or more different specific wavelength ranges, a functional group that undergoes cis-trans isomerization, for example, the following chemical formula And spiropyran groups (reversibly zwitterionized / non-ionized) and azobenzene groups.

このLCST光シフト高分子の合成に際しては、上述のような光応答基を有する単量体(以下「光応答官能基含有単量体」という。)と、下限臨界溶液温度を有する単独重合体(ホモポリマー)を構成する単量体とを共重合することが好ましいが、光応答官能基含有単量体と、下限臨界溶液温度を有しない単独重合体を構成する単量体とを共重合した結果、その共重合体が下限臨界溶液温度を有するようになるのであれば、合成方法は上記の方法に限られない。   In synthesizing this LCST light-shifting polymer, a monomer having a photoresponsive group as described above (hereinafter referred to as “photoresponsive functional group-containing monomer”) and a homopolymer having a lower critical solution temperature ( It is preferable to copolymerize a monomer that constitutes a homopolymer), but a photoresponsive functional group-containing monomer is copolymerized with a monomer that constitutes a homopolymer that does not have a lower critical solution temperature. As a result, the synthesis method is not limited to the above method as long as the copolymer has a lower critical solution temperature.

なお、光応答官能基含有単量体としては、例えば、スピロピランアクリレートや、スピロピランメタクリレート、スピロピランノルボルネンカルボキシレート、メタクリル酸アゾベンゼン、メタクリル酸スチルベン、レチノールメタクリル酸エステル、ジアリールエテン4ビニル安息香酸エステル等が挙げられる。   Examples of the photoresponsive functional group-containing monomer include spiropyran acrylate, spiropyran methacrylate, spiropyran norbornene carboxylate, azobenzene methacrylate, stilbene methacrylate, retinol methacrylate, diarylethene 4-vinylbenzoate, and the like. .

また、下限臨界溶液温度を有する単独重合体(ホモポリマー)を構成する単量体としては、例えば、N−イソプロピルアクリルアミド,N−nプロピルアクリルアミド,N−nプロピルメタクリルアミド,N,N−ジエチルアクリルアミド等のアクリルアミド類や、メタクリル酸−2−(N,N−ジメチルアミノ)エチル,メトキシポリ(エチレングリコール)メタクリレート等のメタクリル酸エステル類、酢酸ビニル(重合後に部分ケン化を要する)、ビニルメチルエーテル、N−ビニルイソブチルアミド、Nービニルカプロラクタム、N−ポリエチレングリコールノルボルネンジカルボキシイミド、その他、ヒドロキシプロピルセルロース骨格,ポリエチレンオキシド骨格,ポリプロピレンオキシド骨格,ポリエチレンオキシド−ポリプロピレン共重合体骨格を有するビニル基含有単量体等のビニル基含有単量体等が挙げられる。   Moreover, as a monomer which comprises the homopolymer (homopolymer) which has a lower critical solution temperature, N-isopropyl acrylamide, Nn propyl acrylamide, Nn propyl methacrylamide, N, N-diethyl acrylamide is mentioned, for example. Acrylamides such as methacrylic acid esters such as methacrylic acid-2- (N, N-dimethylamino) ethyl, methoxypoly (ethylene glycol) methacrylate, vinyl acetate (requires partial saponification after polymerization), vinyl methyl ether, N-vinylisobutyramide, N-vinylcaprolactam, N-polyethylene glycol norbornene dicarboximide, other, hydroxypropylcellulose skeleton, polyethylene oxide skeleton, polypropylene oxide skeleton, polyethylene oxide-polypropyl Vinyl group-containing monomer such as a vinyl group-containing monomer having a pyrene copolymer skeleton.

このLCST光シフト高分子の合成に際し、上記以外の単量体、例えば、下限臨界溶液温度を調整するための単量体を共重合してもかまわない。なお、下限臨界溶液温度を高温側に設定する場合は親水性基を有する単量体を共重合し、下限臨界溶液温度を低温側に設定する場合は疎水性基を有する単量体を共重合すればよい。   In synthesizing this LCST light-shifting polymer, a monomer other than the above, for example, a monomer for adjusting the lower critical solution temperature may be copolymerized. When the lower critical solution temperature is set on the high temperature side, a monomer having a hydrophilic group is copolymerized. When the lower critical solution temperature is set on the low temperature side, a monomer having a hydrophobic group is copolymerized. do it.

(2)溶媒
本発明の実施の形態において、溶媒は、低温側および高温側の下限臨界溶液温度よりも低い温度で上述のLCST光シフト高分子に対して高い溶解度を示し、同下限臨界溶液温度よりも高い温度で同LCST光シフト高分子に対して低い溶解度を示す液状体であればよい。この溶媒は典型的には水であるが、有機溶媒であってもよく、正浸透圧利用システムに供される被処理溶液(フィード溶液とも称されることもある)に応じて適宜選択すればよい。
(2) Solvent In the embodiment of the present invention, the solvent exhibits high solubility with respect to the above-mentioned LCST light-shifting polymer at a temperature lower than the lower critical solution temperature on the low temperature side and the high temperature side. Any liquid that shows low solubility in the LCST light-shifting polymer at a higher temperature may be used. This solvent is typically water, but may be an organic solvent, and may be appropriately selected depending on the solution to be treated (sometimes referred to as a feed solution) supplied to the forward osmotic pressure utilization system. Good.

<本発明の実施の形態に係る駆動溶液の一応用例に係る浸透圧発電システムの詳細>
本発明の実施の形態に係る駆動溶液の一応用例に係る浸透圧発電システム100は、図1に示されるように、主に、容器110、半透膜120、発電機130、三方弁140、駆動溶液再生回路150、紫外線ランプ160およびシャッター170から構成されている。以下、これらの構成要素について説明する。
<Details of Osmotic Pressure Power Generation System According to One Application of Driving Solution According to Embodiment of the Present Invention>
As shown in FIG. 1, an osmotic pressure power generation system 100 according to an application example of a driving solution according to an embodiment of the present invention mainly includes a container 110, a semipermeable membrane 120, a generator 130, a three-way valve 140, a drive. It consists of a solution regeneration circuit 150, an ultraviolet lamp 160, and a shutter 170. Hereinafter, these components will be described.

容器110は、図1に示されるように、供給液および駆動溶液を収容する容器である。   As shown in FIG. 1, the container 110 is a container that stores a supply solution and a driving solution.

半透膜120は、図1に示されるように容器110の内部空間を供給液循環側空間Ssと駆動溶液循環側空間Sdとに区画するように配設されている。なお、図1に示されるように、供給液循環側空間Ssには供給液が充填され、駆動溶液循環側空間Sdには駆動溶液が充填される。なお、この半透膜の機能は後述する。   As shown in FIG. 1, the semipermeable membrane 120 is disposed so as to partition the internal space of the container 110 into a supply liquid circulation side space Ss and a drive solution circulation side space Sd. As shown in FIG. 1, the supply liquid circulation side space Ss is filled with the supply liquid, and the drive solution circulation side space Sd is filled with the drive solution. The function of this semipermeable membrane will be described later.

発電機130は、図1に示されるように、駆動溶液循環側空間Sdの循環経路Cdの駆動溶液流れ上流側に配設されている。そして、供給液循環側空間Ssから半透膜120を介して駆動溶液循環側空間Sdに流入してくる供給液によって循環経路Cdに水流が生じ、その水流によってタービン131が回転駆動されて発電が行われる。   As shown in FIG. 1, the generator 130 is disposed on the upstream side of the drive solution flow in the circulation path Cd of the drive solution circulation side space Sd. Then, a water flow is generated in the circulation path Cd by the supply liquid flowing into the drive solution circulation side space Sd through the semipermeable membrane 120 from the supply liquid circulation side space Ss, and the turbine 131 is rotationally driven by the water flow to generate electric power. Done.

三方弁140は、図1に示されるように、循環経路Cdにおいて発電機130の駆動溶液流れ下流側に配設されている。この三方弁140は、「発電機130から流れ出た駆動溶液を循環経路Cdに流す状態」と「循環経路Cdにおける駆動溶液の流れを堰き止めて同駆動溶液を駆動溶液再生回路150へ流す状態」とを切り換える切換弁として機能する。   As shown in FIG. 1, the three-way valve 140 is disposed on the downstream side of the driving solution flow of the generator 130 in the circulation path Cd. The three-way valve 140 is “a state in which the driving solution flowing out from the generator 130 is caused to flow to the circulation path Cd” and “a state in which the flow of the driving solution in the circulation path Cd is blocked and the driving solution is caused to flow to the driving solution regeneration circuit 150”. Functions as a switching valve.

駆動溶液再生回路150は、図1に示されるように、三方弁140によって循環経路Cdから分岐し、三方弁140の駆動溶液流れ下流側において循環経路Cdに合流している。そして、この駆動溶液再生回路150には、図1に示されるように、主に、沈殿槽151および戻し弁152が配設されている。沈殿槽151には、窓部(図示せず)が2つ設けられている。そして、これらの窓部の外側には、それぞれ紫外線ランプ160およびシャッター170が配設されている。また、この沈殿槽151には、排出弁152が取り付けられていると共に、排出弁152の入口側にメッシュフィルタFmが配設されている。なお、この排出弁152およびメッシュフィルタFmの役割については後述する。戻し弁152は、開閉操作により、沈殿槽151に一時的に駆動溶液を貯める状態(閉状態)と、沈殿槽151に貯めた駆動溶液を循環経路Cdに戻す状態(開状態)とを切り換える切換弁として機能する。   As shown in FIG. 1, the driving solution regeneration circuit 150 is branched from the circulation path Cd by the three-way valve 140 and merges with the circulation path Cd on the downstream side of the driving solution flow of the three-way valve 140. The drive solution regeneration circuit 150 is mainly provided with a settling tank 151 and a return valve 152 as shown in FIG. The precipitation tank 151 is provided with two windows (not shown). And the ultraviolet lamp 160 and the shutter 170 are arrange | positioned on the outer side of these windows, respectively. In addition, a discharge valve 152 is attached to the settling tank 151, and a mesh filter Fm is disposed on the inlet side of the discharge valve 152. The roles of the discharge valve 152 and the mesh filter Fm will be described later. The return valve 152 switches between a state in which the driving solution is temporarily stored in the settling tank 151 (closed state) and a state in which the driving solution stored in the settling tank 151 is returned to the circulation path Cd (open state) by an opening / closing operation. Acts as a valve.

紫外線ランプ160は、図示しない制御装置によって点灯制御されている。   The ultraviolet lamp 160 is controlled to be turned on by a control device (not shown).

シャッター170は、開閉操作により、太陽光を遮る状態(閉状態)と、窓部を介して沈殿槽内部に太陽光を照射させる状態(開状態)とを切り換える役目を有する。   The shutter 170 has a role of switching between a state of blocking sunlight (closed state) and a state of irradiating sunlight inside the sedimentation tank (open state) through the window by an opening / closing operation.

<本発明の実施の形態に係る浸透圧発電システムにおける駆動溶液の再生方法>
浸透圧発電システム100では、上述の通り、供給液循環側空間Ssに供給液を充填すると共に駆動溶液循環側空間Sdに駆動溶液を充填しただけで、浸透現象により供給液循環側空間Ssから半透膜120を介して駆動溶液循環側空間Sdに供給液が流入してくる。このため、駆動溶液循環側空間Sd中の駆動溶液は、供給液との圧力差がなくなるまで徐々に希釈されることになる。そして、駆動溶液と供給液との間で圧力差がなくなると、駆動溶液循環側空間Sdへの供給液の流入がなくなり、発電機130のタービン131を回すことができなくなる。このため、このような浸透圧発電システム100では駆動溶液の再生操作が必要になる。以下、上述のLCST光シフト高分子の性質を利用した駆動溶液の再生方法について説明する。
<Method for Regenerating Drive Solution in Osmotic Pressure Power Generation System According to Embodiment of the Present Invention>
In the osmotic pressure power generation system 100, as described above, the supply liquid circulation side space Ss is filled with the supply liquid and the drive solution circulation side space Sd is filled with the drive solution. The supply liquid flows into the driving solution circulation side space Sd through the permeable membrane 120. For this reason, the driving solution in the driving solution circulation side space Sd is gradually diluted until the pressure difference from the supply liquid disappears. When the pressure difference between the driving solution and the supply liquid disappears, the supply liquid does not flow into the driving solution circulation side space Sd, and the turbine 131 of the generator 130 cannot be turned. For this reason, in such an osmotic pressure power generation system 100, it is necessary to regenerate the driving solution. Hereinafter, a method for regenerating the driving solution using the properties of the above-described LCST light-shifting polymer will be described.

通常運転時、三方弁140は「発電機130から流れ出た駆動溶液を循環経路Cdに流す状態」になっているが、駆動溶液と供給液との間で圧力差がなくなってしまう前のあるタイミングで三方弁140を「循環経路Cdにおける駆動溶液の流れを堰き止めて同駆動溶液を駆動溶液再生回路150へ流す状態」に切り換える。すると、発電機130から流れ出た駆動溶液が沈殿槽151に流れ込む。なお、このとき、駆動溶液中の溶質であるLCST光シフト高分子はイオン化された状態すなわち親水性が強い状態になっており、LCST光シフト高分子が溶媒に溶解するように駆動溶液の温度が同状態時の下限臨界溶液温度よりも低く保たれている。そして、ここで、シャッター170を開けて沈殿槽151内の駆動溶液に太陽光を供給すると、上述のLCST光シフト高分子が非イオン化された状態すなわち疎水性が強い状態になる。このとき、LCST光シフト高分子の下限臨界溶液温度が低温側にシフトして駆動溶液の温度よりも低くなり(すなわち、駆動溶液の温度が疎水化LCST光シフト高分子の下限臨界溶液温度より高くなり)、LCST光シフト高分子が沈殿する。LCST光シフト高分子の沈殿後に排出弁152を開状態にして一定量の液(主として水)を排出した後に、排出弁152を閉状態とする。そして、ここで、紫外線ランプ160を点灯させると、上述のLCST光シフト高分子がイオン化された状態すなわち親水性が強い状態に戻る。このとき、LCST光シフト高分子の下限臨界溶液温度が高温側にシフトして駆動溶液の温度よりも高くなり(すなわち、駆動溶液の温度が親水化LCST光シフト高分子の下限臨界溶液温度よりも低くなり)、LCST光シフト高分子が再溶解する。このようにして駆動溶液が再生される(言い換えると、希釈された駆動溶液中の溶質濃度が再度高められる。)。最後に、紫外線ランプ160の照射開始から一定時間経過後に戻し弁153を開状態として、再生された駆動溶液を循環経路Cdに戻す。   During normal operation, the three-way valve 140 is in a “state in which the driving solution flowing out of the generator 130 flows into the circulation path Cd”, but at a certain timing before the pressure difference between the driving solution and the supply liquid disappears. Then, the three-way valve 140 is switched to “a state in which the flow of the driving solution in the circulation path Cd is blocked and the driving solution is allowed to flow to the driving solution regeneration circuit 150”. Then, the driving solution that has flowed out of the generator 130 flows into the settling tank 151. At this time, the LCST light shift polymer, which is a solute in the drive solution, is in an ionized state, that is, in a highly hydrophilic state, and the temperature of the drive solution is adjusted so that the LCST light shift polymer is dissolved in the solvent. It is kept lower than the lower critical solution temperature in the same state. When the shutter 170 is opened and sunlight is supplied to the driving solution in the sedimentation tank 151, the LCST light shift polymer described above is in a non-ionized state, that is, in a highly hydrophobic state. At this time, the lower critical solution temperature of the LCST light-shifting polymer shifts to a lower temperature side and becomes lower than the temperature of the driving solution (that is, the temperature of the driving solution is higher than the lower critical solution temperature of the hydrophobic LCST light-shifting polymer). The LCST light-shifting polymer is precipitated. After the LCST light shift polymer is precipitated, the discharge valve 152 is opened to discharge a certain amount of liquid (mainly water), and then the discharge valve 152 is closed. And here, when the ultraviolet lamp 160 is turned on, the above-mentioned LCST light-shifting polymer returns to an ionized state, that is, a hydrophilic state. At this time, the lower critical solution temperature of the LCST light-shifting polymer is shifted to a higher temperature side and becomes higher than the temperature of the driving solution (that is, the temperature of the driving solution is lower than the lower critical solution temperature of the hydrophilic LCST light-shifting polymer). The LCST light-shifting polymer is redissolved). In this way, the driving solution is regenerated (in other words, the solute concentration in the diluted driving solution is increased again). Finally, the return valve 153 is opened after a lapse of a certain time from the start of irradiation of the ultraviolet lamp 160, and the regenerated drive solution is returned to the circulation path Cd.

なお、上述の再生方法を実行する際、駆動溶液は、低温側の下限臨界溶液温度(すなわち、LCST光シフト高分子が非イオン化された状態すなわち疎水性が強い状態になった際の下限臨界溶液温度)と、高温側の下限臨界溶液温度(すなわち、LCST光シフト高分子がイオン化された状態すなわち親水性が強い状態になった際の下限臨界溶液温度)との間の温度に温調される必要があるが、この温調は浸透圧発電システム全体で行われてもよいし、沈殿槽151の内部のみで行われてもよい。   When the above regeneration method is performed, the driving solution is a lower critical solution temperature on the low temperature side (that is, the lower critical solution when the LCST light-shifting polymer is in a non-ionized state, that is, in a highly hydrophobic state). Temperature) and the lower critical solution temperature on the high temperature side (that is, the lower critical solution temperature when the LCST light-shifting polymer is ionized, that is, when the hydrophilicity becomes strong). Although it is necessary, this temperature control may be performed in the entire osmotic pressure power generation system, or may be performed only in the precipitation tank 151.

<実施例および比較例>
以下、実施例および比較例を示して本発明をより詳細に説明する。ただし、本発明は、以下に示す実施例に限定されない。
<Examples and Comparative Examples>
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

1.合成
(1)スピロピランアクリレートの合成
先ず、遮光のナスフラスコに0.6355g(1.8mmol)の1−(2−ヒドロキシエル)−3,3−ジメチルインドリノ−6−ニトロベンゾピリロスピランと、0.72ml(5.14mmol)のトリエチルアミンと、5.0mlのテトラヒドロフランとを加えた。次に、先のナスフラスコを氷浴しながらそのナスフラスコに0.20mlの塩化アクリロイルを滴下し、そのナスフラスコ中の内容物を1日撹拌した。次いで、減圧留去により先のナスフラスコからテトラヒドロフランを除去した後、ナスフラスコに酢酸エチルを加えてナスフラスコ中の残渣を酢酸エチルに溶解させた。続いて、その残渣の酢酸エチル溶液を200mLの飽和炭酸水素ナトリウム水溶液で6回、200mLの飽和塩化ナトリウム水溶液で4回洗浄した。その後、減圧留去によりその酢酸エチル溶液から酢酸エチルを除去し、その残渣を減圧下で乾燥させて桃色の固体を得た。そして、得られた桃色の固体を、ヘキサン:酢酸エチル=6:4(v/v)の混合溶媒を展開溶媒とするカラムクロマトグラフィーによって精製した。最後にその精製物を減圧乾燥させて黄色の固体を得た。なお、スピロピランアクリレートの収率は67%であった。また、このときの化学反応は以下の化学反応式に示される通りである。
1. Synthesis (1) Synthesis of Spiropyran Acrylate First, 0.6355 g (1.8 mmol) of 1- (2-hydroxyl) -3,3-dimethylindolino-6-nitrobenzopyrospirane in a light-shielded eggplant flask, 0.72 ml (5.14 mmol) triethylamine and 5.0 ml tetrahydrofuran were added. Next, 0.20 ml of acryloyl chloride was dropped into the eggplant flask while the previous eggplant flask was ice bathed, and the contents in the eggplant flask were stirred for one day. Next, tetrahydrofuran was removed from the previous eggplant flask by distillation under reduced pressure, ethyl acetate was added to the eggplant flask, and the residue in the eggplant flask was dissolved in ethyl acetate. Subsequently, the ethyl acetate solution of the residue was washed 6 times with 200 mL of saturated aqueous sodium bicarbonate solution and 4 times with 200 mL of saturated aqueous sodium chloride solution. Thereafter, ethyl acetate was removed from the ethyl acetate solution by distillation under reduced pressure, and the residue was dried under reduced pressure to obtain a pink solid. The obtained pink solid was purified by column chromatography using a mixed solvent of hexane: ethyl acetate = 6: 4 (v / v) as a developing solvent. Finally, the purified product was dried under reduced pressure to obtain a yellow solid. The yield of spiropyran acrylate was 67%. The chemical reaction at this time is as shown in the following chemical reaction formula.

(2)N−イソプロピルアクリルアミド−スピロピランアクリレート共重合体の合成
554.5mgの(4.90mmol)のN−イソプロピルアクリルアミドと、40.64mg(0.10mmol)のスピロピランアクリレートと、49.3mg(0.30mmol)のアゾビスイソブチロニトリル(開始剤)とをジメチルスルホキシドに溶解させた。そして、その溶液をアルゴン雰囲気下65℃で10時間撹拌することにより、N−イソプロピルアクリルアミドとスピロピランアクリレートとを共重合させた。得られた溶液を分画分子量3500のセルロース透析膜で3日間透析することによりその溶液から不純物を取り除いた。さらにその後、その溶液を凍結乾燥させることでN−イソプロピルアクリルアミド−スピロピランアクリレート共重合体(以下「P(NIPAAm−co−SPAA)」と略する。)を得た。なお、得られたP(NIPAAm−co−SPAA)の重量収率は41%であった。また、このときの共重合反応は以下の化学反応式に示される通りである。さらに、スピロピランアクリレート由来のユニットの含有率は1.3mol%であった。
(2) Synthesis of N-isopropylacrylamide-spiropyran acrylate copolymer 554.5 mg (4.90 mmol) N-isopropylacrylamide, 40.64 mg (0.10 mmol) spiropyran acrylate, 49.3 mg (0. 30 mmol) of azobisisobutyronitrile (initiator) was dissolved in dimethyl sulfoxide. The solution was stirred at 65 ° C. for 10 hours under an argon atmosphere to copolymerize N-isopropylacrylamide and spiropyran acrylate. The resulting solution was dialyzed with a cellulose dialysis membrane having a molecular weight cut off of 3500 for 3 days to remove impurities. Thereafter, the solution was freeze-dried to obtain an N-isopropylacrylamide-spiropyran acrylate copolymer (hereinafter abbreviated as “P (NIPAAm-co-SPAA)”). In addition, the weight yield of obtained P (NIPAAm-co-SPAA) was 41%. The copolymerization reaction at this time is as shown in the following chemical reaction formula. Furthermore, the content rate of the unit derived from spiropyran acrylate was 1.3 mol%.

2.物性測定
(1)スピロピラン基の光異性化反応の確認
上述のP(NIPAAm−co−SPAA)の可逆的な光異性化反応を紫外可視吸収スペクトル測定により確認した。図2には、5.0mg/mlのP(NIPAAm−co−SPAA)水溶液に対して波長254nmの紫外光を所定時間照射した際の紫外可視吸収スペクトル変化を示した。また、図3には、同一の水溶液に対して波長400nm以上の可視光を所定時間照射した際の紫外可視吸収スペクトル変化を示した。図2より、紫外線照射時間の増加に伴いスピロピラン基の開環体状態に由来する550nm付近の吸光度が増加したことがわかる。また、図3より、可視光照射時間の増加に伴いスピロピラン基の開環体状態に由来する吸光度が減少したことがわかる。これは、紫外線照射によりスピロピラン基が閉環体から開環体に異性化し、可視光照射によりスピロピラン基が開環体から閉環体に異性化したためである。これらの結果より、P(NIPAAm−co−SPAA)中のスピロピラン基が可逆的な光異性化反応を示すことが確認された。
2. Physical property measurement (1) Confirmation of photoisomerization reaction of spiropyran group The reversible photoisomerization reaction of P (NIPAAm-co-SPAA) was confirmed by ultraviolet-visible absorption spectrum measurement. FIG. 2 shows changes in the UV-visible absorption spectrum when a 5.0 mg / ml P (NIPAAm-co-SPAA) aqueous solution is irradiated with ultraviolet light having a wavelength of 254 nm for a predetermined time. Further, FIG. 3 shows a change in ultraviolet-visible absorption spectrum when the same aqueous solution is irradiated with visible light having a wavelength of 400 nm or more for a predetermined time. From FIG. 2, it can be seen that the absorbance near 550 nm derived from the ring-opened state of the spiropyran group increased as the ultraviolet irradiation time increased. In addition, FIG. 3 shows that the absorbance derived from the ring-opened state of the spiropyran group decreased with increasing visible light irradiation time. This is because the spiropyran group isomerized from the ring-closed product to the ring-opened product by ultraviolet irradiation, and the spiropyran group was isomerized from the ring-opened product to the closed ring by irradiation with visible light. From these results, it was confirmed that the spiropyran group in P (NIPAAm-co-SPAA) exhibits a reversible photoisomerization reaction.

(2)光照射による下限臨界溶液温度シフト現象の確認
波長400nm以上の可視光の照射前後におけるP(NIPAAm−co−SPAA)水溶液(5.0mg/ml)の各温度における光線透過率を測定した。図4には、その結果、すなわちP(NIPAAm−co−SPAA)水溶液の光線透過率の温度依存性を示した。図4より、可視光照射前後のP(NIPAAm−co−SPAA)水溶液の光線透過率が共に温度の増加に伴って急激に減少したことがわかる。また、P(NIPAAm−co−SPAA)水溶液の可視光照射後の光線透過率の減少が可視光照射前と比較して低温で生じた。これは、可視光照射によりP(NIPAAm−co−SPAA)中のスピロピラン基が開環体から閉環体に異性化し、P(NIPAAm−co−SPAA)の疎水性が増加したためと考えられる。したがって、P(NIPAAm−co−SPAA)には、光照射により水溶性が大きく変化する温度域が存在することが明らかになった。
(2) Confirmation of lower critical solution temperature shift phenomenon by light irradiation The light transmittance at each temperature of an aqueous solution of P (NIPAAm-co-SPAA) (5.0 mg / ml) before and after irradiation with visible light having a wavelength of 400 nm or more was measured. . FIG. 4 shows the result, that is, the temperature dependence of the light transmittance of a P (NIPAAm-co-SPAA) aqueous solution. FIG. 4 shows that both the light transmittances of the P (NIPAAm-co-SPAA) aqueous solutions before and after the visible light irradiation decreased rapidly with increasing temperature. In addition, a decrease in light transmittance after irradiation with visible light of a P (NIPAAm-co-SPAA) aqueous solution occurred at a lower temperature than before irradiation with visible light. This is presumably because the spiropyran group in P (NIPAAm-co-SPAA) isomerized from the open ring to the closed ring by irradiation with visible light, and the hydrophobicity of P (NIPAAm-co-SPAA) increased. Therefore, it has been clarified that P (NIPAAm-co-SPAA) has a temperature range in which water solubility changes greatly by light irradiation.

図5には、P(NIPAAm−co−SPAA)水溶液に29℃で波長400nm以上の可視光を10秒照射した際の写真を示した。図5より、可視光照射によりP(NIPAAm−co−SPAA)水溶液が白濁したことがわかる。これは、P(NIPAAm−co−SPAA)中のスピロピラン基が開環体から閉環体に異性化し、P(NIPAAm−co−SPAA)が下限臨界溶液温度を超えたためと考えられる。したがって、P(NIPAAm−co−SPAA)は特定の温度において光を照射することにより水溶性が変化し、沈殿することが明らかになった。   FIG. 5 shows a photograph when a P (NIPAAm-co-SPAA) aqueous solution is irradiated with visible light having a wavelength of 400 nm or more at 29 ° C. for 10 seconds. FIG. 5 shows that the aqueous solution of P (NIPAAm-co-SPAA) became clouded by irradiation with visible light. This is probably because the spiropyran group in P (NIPAAm-co-SPAA) isomerized from the ring-opened form to the ring-closed form, and P (NIPAAm-co-SPAA) exceeded the lower critical solution temperature. Therefore, it was revealed that P (NIPAAm-co-SPAA) was precipitated by changing water solubility when irradiated with light at a specific temperature.

(3)超純水に対する浸透圧の測定
次に、P(NIPAAm−co−SPAA)水溶液の浸透圧を測定した。P(NIPAAm−co−SPAA)水溶液の濃度を5.0mg/mlとし、スピロピランが開環体の状態で浸透圧の測定を行った。また、浸透圧は、半透膜(再生セルロース膜:膜面積12.25cm)を介して20mlの超純水と20mlのP(NIPAAm−co−SPAA)水溶液とを接触させた状態で超純水−P(NIPAAm−co−SPAA)水溶液間の圧力差を測定し、圧力差が平衡に達した時の値とした。図6には、P(NIPAAm−co−SPAA)水溶液の圧力差の経時変化を示した。図6より、P(NIPAAm−co−SPAA)水溶液の圧力差は時間と共に上昇した。この結果から、P(NIPAAm−co−SPAA)水溶液の浸透圧は0.36kPaであることがわかった。
(3) Measurement of osmotic pressure with respect to ultrapure water Next, the osmotic pressure of a P (NIPAAm-co-SPAA) aqueous solution was measured. The concentration of the aqueous solution of P (NIPAAm-co-SPAA) was 5.0 mg / ml, and the osmotic pressure was measured with spiropyran in the ring-opened state. In addition, the osmotic pressure is ultrapure in a state where 20 ml of ultrapure water and 20 ml of P (NIPAAm-co-SPAA) aqueous solution are contacted via a semipermeable membrane (regenerated cellulose membrane: membrane area 12.25 cm 2 ). The pressure difference between water-P (NIPAAm-co-SPAA) aqueous solution was measured, and it was set as the value when the pressure difference reached equilibrium. FIG. 6 shows the change over time in the pressure difference of the aqueous P (NIPAAm-co-SPAA) solution. From FIG. 6, the pressure difference of the P (NIPAAm-co-SPAA) aqueous solution increased with time. From this result, it was found that the osmotic pressure of the aqueous solution of P (NIPAAm-co-SPAA) was 0.36 kPa.

1.合成
(1)スピロピランメタクリレートの合成
0.20mlの塩化アクリロイルを0.20mlの塩化メタクリロイルに代えた以外は実施例1の「(1)スピロピランアクリレートの合成」に示される合成方法と同一の合成方法でスピロピランメタクリレートを合成した。なお、このときのスピロピランメタクリレートの収率は62%であった。また、このときの化学反応は以下の化学反応式に示される通りである。
1. Synthesis (1) Synthesis of spiropyran methacrylate The synthesis method was the same as the synthesis method shown in “(1) Synthesis of spiropyran acrylate” in Example 1 except that 0.20 ml of acryloyl chloride was replaced with 0.20 ml of methacryloyl chloride. Spiropyran methacrylate was synthesized. At this time, the yield of spiropyran methacrylate was 62%. The chemical reaction at this time is as shown in the following chemical reaction formula.

(2)メトキシポリ(エチレングリコール)メタクリレート−スピロピランメタクリレート共重合体の合成
554.5mg(4.90mmol)のN−イソプロピルアクリルアミドを0.200ml(0.70mmol)のメトキシポリ(エチレングリコール)メタクリレート(ポリ(エチレングリコール)ユニットの平均繰り返し単位数は約3〜4))に代えると共に、40.64mg(0.10mmol)のスピロピランアクリレートを126.0mg(0.30mmol)のスピロピランメタクリレートに代えた以外は実施例1の「(2)N−イソプロピルアクリルアミド−スピロピランアクリレート共重合体の合成」に示される合成方法と同一の合成方法でメトキシポリ(エチレングリコール)メタクリレート−スピロピランメタクリレート共重合体(以下「P(PEGMA−co−SPMA)」と略する。)を合成した。なお、得られたP(PEGMA−co−SPMA)の重量収率は70%であった。また、このときの共重合反応は以下の化学反応式に示される通りである。さらに、スピロピランメタクリレート由来のユニットの含有率は25.8mol%であった。
(2) Synthesis of methoxy poly (ethylene glycol) methacrylate-spiropyran methacrylate copolymer 554.5 mg (4.90 mmol) of N-isopropylacrylamide was added to 0.200 ml (0.70 mmol) of methoxy poly (ethylene glycol) methacrylate (poly (ethylene Example 1 except that the average number of repeating units of glycol) units was changed to about 3-4)) and 40.64 mg (0.10 mmol) of spiropyran acrylate was replaced with 126.0 mg (0.30 mmol) of spiropyran methacrylate. Methoxypoly (ethylene glycol) methacrylate-spiropyranmethacrylate by the same synthesis method as shown in “(2) Synthesis of N-isopropylacrylamide-spiropyranacrylate copolymer”. A relate copolymer (hereinafter abbreviated as “P (PEGMA-co-SPMA)”) was synthesized. In addition, the weight yield of obtained P (PEGMA-co-SPMA) was 70%. The copolymerization reaction at this time is as shown in the following chemical reaction formula. Furthermore, the content rate of the unit derived from spiropyran methacrylate was 25.8 mol%.

2.物性測定
(1)スピロピラン基の光異性化反応の確認
上述のP(PEGMA−co−SPMA)の可逆的な光異性化反応を紫外可視吸収スペクトル測定により確認した。図7には、5.0mg/mlのP(PEGMA−co−SPMA)水溶液に対して波長254nmの紫外光を所定時間照射した際の紫外可視吸収スペクトル変化を示した。また、図8には、同一の水溶液に対して波長400nm以上の可視光を所定時間照射した際の紫外可視吸収スペクトル変化を示した。図7より、紫外線照射時間の増加に伴いスピロピラン基の開環体状態に由来する550nm付近の吸光度が増加したことがわかる。また、図8より、可視光照射時間の増加に伴いスピロピラン基の開環体状態に由来する吸光度が減少したことがわかる。これは、紫外線照射によりスピロピラン基が閉環体から開環体に異性化し、可視光照射によりスピロピラン基が開環体から閉環体に異性化したためである。これらの結果より、P(PEGMA−co−SPMA)中のスピロピラン基が可逆的な光異性化反応を示すことが確認された。
2. Physical property measurement (1) Confirmation of photoisomerization reaction of spiropyran group The above-mentioned reversible photoisomerization reaction of P (PEGMA-co-SPMA) was confirmed by ultraviolet-visible absorption spectrum measurement. FIG. 7 shows changes in the UV-visible absorption spectrum when a 5.0 mg / ml P (PEGMA-co-SPMA) aqueous solution is irradiated with ultraviolet light having a wavelength of 254 nm for a predetermined time. Further, FIG. 8 shows changes in the ultraviolet-visible absorption spectrum when the same aqueous solution is irradiated with visible light having a wavelength of 400 nm or longer for a predetermined time. From FIG. 7, it can be seen that the absorbance near 550 nm derived from the ring-opened state of the spiropyran group increased as the ultraviolet irradiation time increased. In addition, FIG. 8 shows that the absorbance derived from the ring-opened state of the spiropyran group decreased as the visible light irradiation time increased. This is because the spiropyran group isomerized from the ring-closed product to the ring-opened product by ultraviolet irradiation, and the spiropyran group was isomerized from the ring-opened product to the closed ring by irradiation with visible light. From these results, it was confirmed that the spiropyran group in P (PEGMA-co-SPMA) exhibits a reversible photoisomerization reaction.

(2)光照射による下限臨界溶液温度シフト現象の確認
波長400nm以上の可視光の照射前後におけるP(PEGMA−co−SPMA)水溶液(5.0mg/ml)の各温度における光線透過率を測定した。図9には、その結果、すなわちP(PEGMA−co−SPMA)水溶液の光線透過率の温度依存性を示した。図9より、可視光照射前後のP(PEGMA−co−SPMA)水溶液の光線透過率が共に温度の増加に伴って急激に減少したことがわかる。また、P(PEGMA−co−SPMA)水溶液の可視光照射後の光線透過率の減少が可視光照射前と比較して低温で生じた。これは、可視光照射によりP(PEGMA−co−SPMA)中のスピロピラン基が開環体から閉環体に異性化し、P(PEGMA−co−SPMA)の疎水性が増加したためと考えられる。したがって、P(PEGMA−co−SPMA)には、光照射により水溶性が大きく変化する温度域が存在することが明らかになった。
(2) Confirmation of lower critical solution temperature shift phenomenon by light irradiation The light transmittance at each temperature of an aqueous solution of P (PEGMA-co-SPMA) (5.0 mg / ml) before and after irradiation with visible light having a wavelength of 400 nm or more was measured. . FIG. 9 shows the result, that is, the temperature dependence of the light transmittance of the P (PEGMA-co-SPMA) aqueous solution. FIG. 9 shows that both the light transmittances of the aqueous P (PEGMA-co-SPMA) solutions before and after the visible light irradiation decreased rapidly with increasing temperature. In addition, a decrease in light transmittance after irradiation with visible light of the P (PEGMA-co-SPMA) aqueous solution occurred at a lower temperature than before irradiation with visible light. This is presumably because the spiropyran group in P (PEGMA-co-SPMA) isomerized from an open ring to a closed ring by irradiation with visible light, and the hydrophobicity of P (PEGMA-co-SPMA) increased. Therefore, it has been clarified that P (PEGMA-co-SPMA) has a temperature range in which water solubility changes greatly by light irradiation.

図10には、P(PEGMA−co−SPMA)水溶液に42℃で波長400nm以上の可視光を30秒照射した際の写真を示した。図10より、可視光照射によりP(PEGMA−co−SPMA)水溶液が白濁したことがわかる。これは、P(PEGMA−co−SPMA)水溶液中のスピロピラン基が開環体から閉環体に異性化し、P(PEGMA−co−SPMA)が下限臨界溶液温度を超えたためと考えられる。したがって、P(PEGMA−co−SPMA)は特定の温度において光を照射することにより水溶性が変化し、沈殿することが明らかになった。   FIG. 10 shows a photograph of a P (PEGMA-co-SPMA) aqueous solution irradiated with visible light having a wavelength of 400 nm or more at 42 ° C. for 30 seconds. FIG. 10 shows that the aqueous solution of P (PEGMA-co-SPMA) is clouded by irradiation with visible light. This is presumably because the spiropyran group in the aqueous solution of P (PEGMA-co-SPMA) isomerized from the open ring to the closed ring, and P (PEGMA-co-SPMA) exceeded the lower critical solution temperature. Therefore, it was revealed that P (PEGMA-co-SPMA) was precipitated by changing water solubility when irradiated with light at a specific temperature.

(3)超純水に対する浸透圧の測定
次に、P(PEGMA−co−SPMA)水溶液の浸透圧を測定した。P(PEGMA−co−SPMA)水溶液の濃度を5.0mg/mlとし、スピロピランが開環体の状態で浸透圧の測定を行った。また、浸透圧は、半透膜(再生セルロース膜:膜面積12.25cm)を介して20mlの超純水と20mlのP(PEGMA−co−SPMA)水溶液とを接触させた状態で超純水−P(PEGMA−co−SPMA)水溶液間の圧力差を測定し、圧力差が平衡に達した時の値とした。図11には、P(PEGMA−co−SPMA)水溶液の圧力差の経時変化を示した。図11より、P(PEGMA−co−SPMA)水溶液の圧力差は時間と共に上昇した。この結果から、P(PEGMA−co−SPMA)水溶液の浸透圧は5.41kPaであることがわかった。
(3) Measurement of osmotic pressure with respect to ultrapure water Next, the osmotic pressure of a P (PEGMA-co-SPMA) aqueous solution was measured. The concentration of the aqueous solution of P (PEGMA-co-SPMA) was 5.0 mg / ml, and the osmotic pressure was measured with spiropyran in the ring-opened state. In addition, the osmotic pressure is ultrapure in a state where 20 ml of ultrapure water and 20 ml of P (PEGMA-co-SPMA) aqueous solution are contacted via a semipermeable membrane (regenerated cellulose membrane: membrane area 12.25 cm 2 ). The pressure difference between water-P (PEGMA-co-SPMA) aqueous solution was measured, and the value was taken when the pressure difference reached equilibrium. FIG. 11 shows the change over time in the pressure difference of the P (PEGMA-co-SPMA) aqueous solution. From FIG. 11, the pressure difference of the P (PEGMA-co-SPMA) aqueous solution increased with time. From this result, it was found that the osmotic pressure of the aqueous solution of P (PEGMA-co-SPMA) was 5.41 kPa.

本発明に係る正浸透圧利用システムの駆動溶液は、上述の浸透圧発電のみならず海水の淡水化や、排水処理、ジュースの濃縮等の食品プロセス等に利用可能である。   The driving solution of the forward osmotic pressure utilization system according to the present invention can be used not only for the above-described osmotic pressure power generation but also for food processes such as seawater desalination, wastewater treatment, and juice concentration.

100 浸透圧発電システム
110 容器
120 半透膜
130 発電機
131 タービン
140 三方弁
150 駆動溶液再生回路
151 沈殿槽
152 排出弁
153 戻し弁
160 紫外線ランプ
170 シャッター
Cd 駆動溶液循環経路
Fm メッシュフィルタ
Sd 駆動溶液循環側空間
Ss 供給液循環側空間
100 Osmotic pressure power generation system 110 Container 120 Semipermeable membrane 130 Generator 131 Turbine 140 Three-way valve 150 Drive solution regeneration circuit 151 Precipitation tank 152 Drain valve 153 Return valve 160 Ultraviolet lamp 170 Shutter Cd Drive solution circulation path Fm Mesh filter Sd Drive solution circulation Side space Ss Supply liquid circulation side space

Claims (5)

特定波長域の光に応答して可逆的に下限臨界溶液温度をシフトする高分子を溶質として含有する、正浸透圧利用システムの駆動溶液。   A driving solution for a forward osmotic pressure utilization system, containing as a solute a polymer that reversibly shifts the lower critical solution temperature in response to light in a specific wavelength range. 前記高分子は、前記特定波長域の光に応答して可逆的に疎水化あるいは親水化する光応答基を有し、
前記下限臨界溶液温度は、前記光応答基の疎水化あるいは親水化に応じて可逆的にシフトする
請求項1に記載の駆動溶液。
The polymer has a photoresponsive group that reversibly becomes hydrophobic or hydrophilic in response to light in the specific wavelength range,
The driving solution according to claim 1, wherein the lower critical solution temperature is reversibly shifted according to the hydrophobicity or hydrophilicity of the photoresponsive group.
前記光応答基は、前記特定波長域の光に応答して可逆的にイオン化および非イオン化し、
前記下限臨界溶液温度は、前記光応答基のイオン化および非イオン化に応じて可逆的にシフトする
請求項2に記載の駆動溶液。
The photoresponsive group is reversibly ionized and non-ionized in response to light in the specific wavelength range,
The driving solution according to claim 2, wherein the lower critical solution temperature is reversibly shifted according to ionization and nonionization of the photoresponsive group.
前記高分子は、メトキシポリ(エチレングリコール)メタクリレートとスピロピランメタクリレートのビニル共重合体であり、
前記正浸透圧利用システムは、浸透圧発電システムである
請求項1から3のいずれか1項に記載の駆動溶液。
The polymer is a vinyl copolymer of methoxypoly (ethylene glycol) methacrylate and spiropyran methacrylate,
The driving solution according to any one of claims 1 to 3, wherein the forward osmotic pressure utilization system is an osmotic pressure power generation system.
請求項1から4のいずれか1項に記載の駆動溶液に第1特定波長域の光を照射することによって前記下限臨界溶液温度を低温側にシフトさせて前記高分子を沈殿させる沈殿工程と、
前記高分子が沈殿した状態の前記駆動溶液から液体の一部を排出する排出工程と、
前記高分子の沈殿物に第2特定波長域の光を照射することによって前記下限臨界溶液温度を高温側にシフトさせて前記駆動溶液を再生する再生工程と
を備える、正浸透圧利用システムの駆動溶液の再生方法。
A precipitation step of precipitating the polymer by shifting the lower critical solution temperature to a low temperature side by irradiating the driving solution according to any one of claims 1 to 4 with light in a first specific wavelength range,
A discharging step of discharging a part of the liquid from the driving solution in a state where the polymer is precipitated;
Driving a forward osmotic pressure utilization system comprising: a regeneration step of regenerating the driving solution by shifting the lower critical solution temperature to a higher temperature side by irradiating the polymer precipitate with light in a second specific wavelength region Solution regeneration method.
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