JP4863712B2 - Film for producing hydrogen carbonate ion and method for producing the same, porous laminate for producing hydrogen carbonate ion, and method for producing hydrogen carbonate ion - Google Patents

Description

  The present invention relates to a composite film in which a zinc complex is formed in a side chain group of an organic polymer. Moreover, this invention relates to a porous laminated body provided with this composite material film, and its manufacturing method.

  Conventionally, methods for depositing minerals such as carbonates (particularly calcium carbonate) using the surface of natural or artificial organic substances as a reaction field have been studied. In the case of such a method, generally, an organic substance is allowed to stand in a supersaturated aqueous solution of carbon dioxide for a long period of time (usually several days or more) to precipitate a mineral on the surface of the organic substance.

Organic substances used in this method include functional groups such as hydroxyl groups that form hydrogen bonds with metals, carboxyl groups and sulfo groups that have ion exchange capabilities, and amino groups and thiol groups that coordinate with metals to form chelate complexes. There is. As a typical research example, there is a method of depositing calcium carbonate on a monomolecular layer of stearic acid (CH ₃ (CH ₂ ) ₁₆ COOH) (Non-patent Document 1). In this method, it is considered that the production of calcium carbonate is promoted by capturing the calcium ions by the carboxyl group of stearic acid. In addition, a method using a zinc substrate produced by the silane method technique has been reported (Non-patent Document 2).
BR Heywood et al., Advanced Materials, 1994, Vol. 6, p. 9-20 Ichikawa et al., European Journal of Chemistry, 2003, Vol. 9, p. 3235-3241

By the way, in order to efficiently produce calcium carbonate in an aqueous solution containing calcium ions, it is desired to supply hydrogen carbonate ions (HCO ₃ ⁻ ) at as high a concentration as possible. Therefore, when carbon dioxide is taken in to produce calcium carbonate, it is important to sufficiently enhance the activity of the hydration reaction of carbon dioxide that generates hydrogen carbonate ions from carbon dioxide.

  However, in the case of conventional methods including the method described in Non-Patent Document 1, organic substances such as stearic acid have a function of capturing calcium ions, but increase the activity of carbon dioxide hydration. There was no function, and calcium carbonate could not be produced from carbon dioxide sufficiently efficiently. Therefore, a process involving a large energy consumption such as the use of a salt composed of hydrogen carbonate ions or a high-pressure gas containing carbon dioxide has been required.

  Then, an object of this invention is to provide the material which can fully raise the activity of the hydration reaction of a carbon dioxide.

［式中、Ｒは窒素原子及び硫黄原子のうち少なくとも一方を有する複素環からなる側鎖基を示す。］
で表されるモノマー単位を含むポリマーと、当該ポリマー中の複素環が配位して亜鉛錯体を形成している亜鉛イオンと、を含有する多孔質状の複合材フィルムである。 The present invention provides the following structural formula (1):

[In formula, R shows the side chain group which consists of a heterocyclic ring which has at least one among a nitrogen atom and a sulfur atom. ]
A porous composite film containing a polymer including a monomer unit represented by formula (I) and a zinc ion in which a heterocyclic ring in the polymer is coordinated to form a zinc complex.

  This composite film was made porous by introducing a zinc complex in the side chain of the polymer, and the activity of the carbon dioxide hydration reaction could be sufficiently increased. In the natural enzyme that promotes the hydration reaction of carbon dioxide, it is considered that the zinc complex is involved in the expression of its activity, but the zinc complex part in the composite film has the same action as the zinc complex in the natural enzyme. The present inventors speculate that the activity of promoting hydration reaction is expressed by the above.

  The heterocyclic ring in the composite film is preferably at least one selected from the group consisting of imidazole, imidazoline, pyrazole, pyridine, pyrimidine, pyrazine, thiophene and thiazole. These heterocycles coordinate zinc ions, so that the activity of promoting the hydration reaction of carbon dioxide is particularly enhanced.

  The porous laminate of the present invention comprises a substrate and the porous composite film according to the present invention formed on the substrate. By immersing this laminate in an aqueous solution, the hydration reaction of carbon dioxide can be promoted easily and sufficiently efficiently.

  The present invention also includes a step of forming a polymer film containing a polymer containing the monomer unit represented by the general formula (1), and bringing the polymer film into contact with a solution of zinc ions. And a step of producing a porous composite film containing zinc ions in which the heterocycle is coordinated to form a zinc complex.

  According to this production method, a porous composite film having a card house-like form with a large specific surface area and capable of promoting the hydration reaction of carbon dioxide particularly efficiently can be obtained.

  Also in this production method, the heterocyclic ring is preferably at least one selected from the group consisting of imidazole, imidazoline, pyrazole, pyridine, pyrimidine, pyrazine, thiophene and thiazole.

  The present invention is also a method for producing hydrocarbon ions, wherein hydrogen carbonate ions are produced by a hydration reaction of carbon dioxide in the presence of the composite film of the present invention. According to this method, hydrogen carbonate ions can be generated from carbon dioxide with sufficiently high efficiency. In this method, it is presumed that bicarbonate ions are generated by a carbonic anhydrase enzyme-like reaction.

  According to the composite film of the present invention, the activity of hydration reaction of carbon dioxide is sufficiently high, and a large driving force for producing calcium carbonate can be obtained. The activity of promoting the carbon dioxide hydration reaction of the composite film of the present invention and its stability were improved as compared with, for example, the zinc substrate described in Non-Patent Document 2 described above. The reason is considered to be due to the increase in the number of sites that promote the carbon dioxide hydration reaction and the increase in density due to the porous structure of the composite film. The decisive reason is that the polymer having such a site in the repeating structural unit was targeted at the design and synthesis stage. The synthesis method is relatively easy, and the development to a larger scale is easy in the production of the porous laminate. Therefore, it is expected that carbon dioxide absorption / fixation and calcium carbonate synthesis apparatus will be realized by energy saving and clean green process using the composite film of the present invention.

  The solubility of hydrogen carbonate ions in water is about two orders of magnitude greater than that of carbon dioxide, and if the composite film of the present invention is used to efficiently convert carbon dioxide into hydrogen carbonate ions by a hydration reaction, It becomes possible to increase carbon dioxide absorption. Conventionally, in industrial processes, hydrogen carbonate ions are supplied using high-pressure carbon dioxide gas or sodium hydrogen carbonate, but by using the composite film of the present invention, high-pressure gas production or sodium hydrogen carbonate synthesis is performed. This makes it possible to use carbon dioxide in the atmosphere or waste gas as a raw material without requiring the energy required for this.

  Further, the composite film of the present invention can be applied to an air purification device that removes carbon dioxide in a closed room environment or the like in a high yield by utilizing the effect of promoting carbon dioxide absorption. When the carbon dioxide concentration is 1000 ppm (0.1% v / v) or more, it is said that the function of the respiratory organs, circulatory organs, and cerebrum is affected. It is considered that the carbon dioxide concentration can be controlled to a concentration lower than this.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  In the composite film of the present invention, a zinc complex is formed by coordination of the heterocyclic ring of the monomer unit represented by the structural formula (1) to zinc ions. However, it is not always necessary that all the heterocyclic rings in the polymer are complexed with zinc ions.

  In the structural formula (1), R represents a side chain group composed of a heterocyclic ring having at least one of a nitrogen atom and a sulfur atom. R in the polymer may be the same as or different from each other.

  The heterocyclic ring as R is not particularly limited as long as it can form a zinc complex with a zinc ion, but is at least one selected from the group consisting of imidazole, imidazoline, pyrazole, pyridine, pyrimidine, pyrazine, thiophene and thiazole. Preferably there is. Among these, imidazole or imidazoline is particularly preferable. That is, the polymer constituting the composite film particularly preferably includes a monomer unit represented by the following structural formula (1a) or (1b).

  The polymer containing the monomer unit of the formula (1) can be synthesized, for example, by polymerization of a vinyl monomer represented by the following structural formula (2). As is apparent to those skilled in the art, the polymerization of the vinyl monomer can be performed by a conventionally known method such as radical polymerization.

  The substrate on which the polymer is adsorbed does not necessarily have a plate shape, and may have another shape such as a spherical shape. Examples of the material constituting the substrate include glass and mica. Further, if desired, a porous composite containing a polymer containing the monomer unit represented by the formula (1) and a zinc ion in which a heterocyclic ring in the polymer is coordinated to form a zinc complex. The material can also be used in a form other than a film.

  The composite film includes, for example, a step of forming a polymer film containing a polymer containing the monomer unit represented by the structural formula (1), and the polymer film by contacting the polymer film with a solution of zinc ions. And a step of producing a porous composite film containing a zinc ion in which a heterocycle in the polymer is coordinated to form a zinc complex. FIG. 1 is a perspective view schematically showing a coordination form of zinc ions in a composite film formed on a substrate. As shown in FIG. 1, a zinc complex is formed by an imidazole group of a polymer adsorbed on a substrate 1 and zinc ions, and a composite film 2 is formed from these polymers and zinc ions.

  The polymer film can be formed, for example, by a method in which a liquid material in which a polymer is dispersed or dissolved in a solvent such as ethanol is applied on a substrate and the solvent is removed. The method of application in this case is not particularly limited, but can be applied by, for example, a spin coat method. The removal of the solvent can be performed by an ordinary drying method such as freeze drying. In the polymer film after drying, the polymer which does not contain a zinc complex usually has a layered form.

  The step of generating a porous composite film can be performed, for example, by immersing a polymer film formed on a substrate in a zinc ion solution. As the zinc ion solution, an aqueous solution of zinc salt is preferably used. As the zinc salt, for example, zinc nitrate is used. In order to stably form the zinc complex, it is preferable that the pH of the zinc ion solution is adjusted to about 7 to 7.5. Usually, the formation of the zinc complex in the polymer film sufficiently proceeds by immersion at room temperature overnight.

  It can be confirmed by elemental analysis or the like on the surface that a zinc complex is formed in the composite film of the laminate after immersion. Elemental analysis can be performed using, for example, an energy dispersive X-ray analyzer (EDAX).

  By generating hydrogen carbonate ions in a carbon dioxide carbonic anhydrase enzyme-like hydration reaction in the presence of the composite film, hydrocarbon ions can be generated in the solution with sufficiently high efficiency. In this case, for example, by immersing the laminate in the reaction solution, the hydration reaction of carbon dioxide proceeds, and hydrocarbon ions are generated in the reaction solution. The reaction solution is preferably adjusted to a pH of about 8.5 to 9 with a buffer solution or the like. In order to continue the activity, it is preferable to dissolve zinc ions in the reaction solution.

  If calcium ions are present in the reaction solution, calcium carbonate is generated by reaction with the generated hydrocarbon ions. By using a substrate having a function of capturing calcium ions, calcium carbonate having a controlled crystal system can be efficiently deposited on the substrate.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

(Synthesis example)
Synthesis of poly (4-vinylimidazole) (hereinafter referred to as “P4-VI”) 4-vinylimidazole 85 mg (0.6 mmol) and 2,2-azobis (isobutylnitrile) 1.5 mg (based on 4-vinylimidazole) 1.0 mol%) was added to 5 mL of a mixed solvent in which benzene / ethanol was mixed at a ratio of 1: 1 to prepare a reaction solution. This reaction solution was placed in a 20 mL sample tube, placed in a vacuum distillation vessel containing about 5 mL of benzene, and the reaction solution was frozen with liquid nitrogen. The mixture obtained by freezing the reaction solution was dried by degassing the inside of the vacuum distillation vessel using a rotary pump. And it returned to room temperature, the mixture was melt | dissolved, and the deaerated reaction liquid was obtained.

Subsequently, the reaction solution was heated to 65 ° C. and refluxed in a vacuum distillation vessel. After 13 hours, a pale yellow precipitate was filtered off and dried to obtain a product (solid, light beige) containing P4-VI (yield 62%).
¹ H NMR (C ₆ D ₆ / C ₂ D ₅ OH (1: 1 v / v)) δ (ppm): 1.6 (broad, CH ₂ in the main chain, 2.0-2.5 (broad, CH in the main chain) 6.2-6.4 (broad, imidazole ring H-5), 7.3-7.6 (broad, imidazole ring H-2)

(1) Production of Laminate Cover Glass (25 × 25 mm) of P4-VI ethanol solution (0.5 wt%) 7 × 10 ⁻⁵ L obtained above using a microsyringe (for 10 ⁻⁴ L) It was supplied to the top and developed by the spin coat method. Spin coating is performed at a rotational speed of 900 rpm, SLsec. The test was performed under conditions of 10 seconds and a rotation time of 300 seconds. After spin coating, the film was dried in a desiccator reduced in pressure with a diaphragm pump for 2 hours to obtain a laminate in which a polymer film containing P4-VI was formed on a cover glass as a substrate.

This laminate was immersed in an aqueous solution of Zn (NO ₃ ) ₂ .6H ₂ O (5 × 10 ⁻³ M, adjusted to pH 7 with an aqueous NaOH solution) overnight, thereby converting the imidazole ring in P4-VI to zinc. Coordinated to ions. Thereafter, the laminate was taken out from the aqueous solution, and the aqueous solution adhering to the surface was washed away with distilled water. Subsequently, it was dried in a desiccator whose pressure was reduced by a diaphragm pump for 3 hours to obtain a porous laminate in which a porous composite film was formed on a cover glass.

(2) Evaluation of carbon dioxide hydration activity _(CO 2 -Veronal method)
5 × 10 ⁻⁴ M Zn ²⁺ aqueous solution 9 × 10 ⁻³ L prepared using 2 × 10 ⁻² M TAPS buffer (about pH 9) was stirred under ice-cooling, and the porous material prepared above was stirred there. The porous laminate was immersed. Then, the time course of the pH definitive after addition of CO ₂ saturated aqueous solution (pH5) 6 × ^{10 -3} L to ^{Zn 2+} aqueous solution was measured by pH meter. As the CO ₂ saturated aqueous solution, one prepared by aeration of CO ₂ gas in distilled water under ice cooling at a flow rate of 50 mL / min for 1 hour was used. A plurality of porous laminates produced in the same manner were evaluated for carbon dioxide hydration activity. Further, as a blank test (blank), the change with time of pH was measured in the same manner when only the cover glass was immersed.

  FIG. 2 is a graph showing the change with time of pH in the carbon dioxide hydration activity test. As shown in FIG. 2, by immersing the porous laminate, the pH decrease clearly progressed faster than the blank. From this, it was confirmed that the composite film of the present invention exhibited a large carbon dioxide hydration activity.

(3) SEM Observation and Elemental Analysis of Composite Film FIG. 3 shows a polymer film before Zn ²⁺ is acted on, and FIG. 4 shows an SEM image of the composite film after Zn ²⁺ is coordinated. As shown in FIG. 3, the polymer film before being coordinated to Zn ²⁺ has a form of being deposited in layers. On the other hand, as shown in FIG. 4, by coordinating with Zn ²⁺ , a composite film is formed from the polymer film, and the form changes to a card house-like structure, and the porous laminate is formed. became. It is thought that the P4-VI polymer itself and the polymer deposited in layers changed in shape through Zn ²⁺ . Thus, it is thought that the increase in the specific surface area due to the porous composite film contributes to the development of high carbon dioxide hydration activity.

Further, the structure formed on the composite film was analyzed by an energy dispersive X-ray analyzer (EDAX). FIG. 5 is an EDAX elemental analysis spectrum of the composite film surface. As shown in FIG. 5, it was confirmed that Zn ²⁺ was present in the composite film. Note that the SEM observation and analysis by EDAX were performed on the composite material film formed on the mica substrate for the convenience of the experimental operation.

It is a perspective view which shows typically the coordination form of zinc in the composite material film which concerns on this invention. It is a graph which shows the time-dependent change of pH in the test of a carbon dioxide hydration activity. It is a SEM image of the polymer layer before making a zinc ion act. It is a SEM image of the composite film formed by making zinc ion act. It is an EDAX analysis spectrum of the composite film surface.

Explanation of symbols

1 ... substrate, 2 ... composite film.

Claims (6)

The following structural formula (1):

[In formula, R shows the side chain group which consists of a heterocyclic ring which has at least one among a nitrogen atom and a sulfur atom. ]
A polymer containing a monomer unit represented by:
A zinc ion in which a heterocycle in the polymer is coordinated to form a zinc complex;
The porous bicarbonate ion generation off Irumu containing. It said heterocycle imidazole, imidazoline, pyrazole, pyridine, pyrimidine, pyrazine, is at least one selected from the group consisting of thiophene and thiazole, claim 1 bicarbonate ion generation off Irumu according. Substrate and, bicarbonate ion generation porous laminate and a bicarbonate ion-generating off Irumu of formed claim 1 or 2, wherein on the substrate. The following structural formula (1):

[In formula, R shows the side chain group which consists of a heterocyclic ring which has at least one among a nitrogen atom and a sulfur atom. ]
Forming a polymer film containing a polymer containing a monomer unit represented by:
By contacting the polymer film with a solution of zinc ions, to produce a porous off Irumu containing zinc ions heterocyclic of the polymer and the polymer form a zinc complex coordinated Process,
Method for producing a hydrogen carbonate ion generation off Irumu comprising.   The production method according to claim 4, wherein the heterocyclic ring is at least one selected from the group consisting of imidazole, imidazoline, pyrazole, pyridine, pyrimidine, pyrazine, thiophene, and thiazole.   A method for producing hydrocarbon ions, wherein hydrogen carbonate ions are produced by a hydration reaction of carbon dioxide in the presence of the composite film for producing hydrogen carbonate ions according to claim 1 or 2.

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