JP6417183B2 - Metal ion collector - Google Patents

Description

  The present invention relates to a metal ion collector.

  In order to collect metal ions from an aqueous solution, polystyrene-based materials such as amberlite are mainly used. However, polystyrene is a chemically synthesized product. Considering global warming and depletion of fossil fuels, replacement with natural materials that are more environmentally friendly is desired. In recent years, in a fiber molecule of natural fiber or regenerated fiber, via a crosslinking reactive compound having a reactive double bond and a glycidyl group in the molecule, aminodicarboxylic acid, aminocarboxylic acid having reactivity with glycidyl group, There has been proposed a metal chelate-forming fiber to which at least one metal chelate-forming compound selected from the group consisting of thiocarboxylic acid and phosphoric acid is bound (for example, see Patent Document 1).

JP 2000-248467 A

  The metal chelate-forming fiber of Patent Document 1 has advantages such as easy incineration, but further improvement in the selectivity of metal ions that can be collected is desired.

  From the background as described above, an object of the present invention is to provide a global environment-friendly metal ion collector that can collect metal ions and can selectively collect metal ions. Yes.

In order to solve the above problems, the metal ion scavenger of the present invention comprises a banana fiber, and a graft chain composed of a crosslinking agent is introduced into a reactive functional group in the molecule of the banana fiber. A Schiff base type ligand represented by the following formula (I) is introduced via:
(In the formula, R ₁ represents a hydrogen atom, and R ₂ represents a bromine atom or a chlorine atom.)

In the metal ion trapping material, the banana fibers may be banana fiber portion of the lignin components contained in the banana fibers are removed.

  In this metal ion scavenger, the cross-linking agent may be a compound having a vinyl group and an epoxy group in the molecule.

  ADVANTAGE OF THE INVENTION According to this invention, the metal ion collection material which can collect a metal ion and can collect selectively depending on a metal ion can be provided to a global environment.

It is the schematic of the synthesis | combination of a banana fiber-g-GMA. (2,2'-iminobis [etane-2,1-diylnitrilo (E) methylidine]) is a schematic diagram of the synthesis of a bisphenol derivative. It is the schematic of the synthesis | combination of the collection material by which the Schiff base type ligand was introduce | transduced into banana fiber-g-GMA. 5 is a graph showing the amount of metal ions adsorbed on the collection material 3. 5 is a graph showing the amount of metal ions adsorbed on the collection material 3. It is the graph which showed the adsorption amount of the metal ion of the collection material 1 and the collection material 2. FIG. 5 is a graph showing the amount of metal ions adsorbed on the collection material 4. 5 is a graph showing the amount of metal ions adsorbed on the collection material 5. 4 is a graph showing the amount of metal ions (rare earth element ions) adsorbed on the collection material 3. 1 is a schematic diagram of the synthesis of N- (4-aminophenyl) aza-18-crown-6 ether. FIG. It is the schematic of the synthesis | combination of the collection material by which the cyclic ligand was introduce | transduced into banana fiber-g-GMA. It is the graph which showed the adsorption rate of the cesium ion of the collection material 2 and the collection material 6. FIG. It is the graph which showed the adsorption rate of the cesium ion of the collection material. 5 is a graph showing the adsorption rate of cesium ions of the collection material 8. 3 is a graph showing the cesium ion adsorption rate of the collection material 1. It is the graph which showed the adsorption rate of the cesium ion of the collection material. It is the graph which showed the adsorption rate of the cesium ion of the collection material. 3 is a graph showing the cesium ion adsorption rate of the collection material 10. It is the graph which showed the adsorption rate of the cesium ion of the collection material. It is the graph which showed the adsorption rate of the strontium ion of the collection material.

  Hereinafter, embodiments of the present invention will be described.

  The metal ion collection material which concerns on embodiment of this invention is a collection material which collects the metal ion in solutions, such as aqueous solution. This collection material consists of natural fibers. Here, the trapping material made of natural fibers may be made only of natural fibers, or chelate-forming groups that form chelates with metal ions are directly bonded to reactive functional groups in the molecules of natural fibers. It may be what has been done. In addition, a graft chain composed of a crosslinking agent is introduced into a reactive functional group in the molecule of the natural fiber, or the chelate-forming group passes through a graft chain composed of a crosslinking agent in the reactive functional group in the molecule of the natural fiber. May be introduced.

  Examples of natural fibers used in the metal ion collecting material according to this embodiment include banana fibers, kenaf fibers, bamboo fibers, sugarcane fibers, corn fibers, hemp fibers, and the like. Among these, banana fibers are preferably used from the viewpoint of metal selectivity.

Natural fibers usually have a lignin component. Although natural fiber can be used without removing the lignin component, a part of the lignin component, for example, one from which the lignin component contained on the surface of the fiber has been removed can be used. For metal ion collectors using natural fibers that do not remove lignin components and metal ion collectors using natural fibers from which some of the lignin components have been removed, the reason for the metal ion collection ability is unknown. Behave differently. For example, metal ion collectors using natural fibers from which some of the lignin components have been removed tend to have higher metal ion collection capacity than metal ion collectors using natural fibers that do not remove lignin components. is there. Any natural fiber may be appropriately selected and used in accordance with the processing cost for removing the lignin component and the use for collecting the metal ions.
The lignin component can be removed by immersing the natural fiber for a predetermined time in an alkaline aqueous solution such as 1 to 20 wt% sodium hydroxide aqueous solution. The reason why a part of the lignin contained in the natural fiber is removed is that when the lignin component is completely removed, the strength as a collecting material is lowered.

Natural fibers generally have reactive functional groups such as hydroxyl groups and amino groups in the molecule. When the natural fiber itself does not have such a reactive functional group, the reactive functional group can be introduced into the molecule by performing a treatment such as oxidation. In addition, as a reactive functional group, functional groups, such as an imino group, an aldehyde group, a carboxyl group, and a thiol group, may be sufficient.
A graft chain composed of a chelate-forming group or a crosslinking agent can be easily introduced into the reactive functional group by using the reactive functional group contained in the molecule of the natural fiber.

  Examples of the crosslinking agent that forms a graft chain introduced into a reactive functional group in a natural fiber molecule include a compound having a vinyl group and an epoxy group in the molecule (for example, a vinyl monomer having an epoxy group). be able to. Specific examples include glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, glycidyl vinyl ether, 2-vinyloxirane, 2-methyloxylanylmethyl (meth) acrylate, diglycidyl itaconate, glycidyl pentenoate, glycidyl hexenoate, heptene Examples include glycidyl acid.

  In order to introduce a graft chain into a reactive functional group in a natural fiber molecule using such a cross-linking agent, for example, diammonium cerium nitrate salt, ion-exchanged water, nitric acid, acetone as in the examples described later And a natural fiber is immersed in a mixed solution of a crosslinking agent and allowed to react for a predetermined time (graft polymerization reaction) at room temperature for graft addition.

  The metal ion scavenger according to this embodiment has a Schiff base type ligand having three nitrogen atoms and two phenol residues in one molecule as a chelate-forming group in the natural fiber molecule. Also good. The Schiff base type ligand may be directly bonded to the reactive functional group in the natural fiber molecule, or introduced into the reactive functional group in the natural fiber molecule through a graft chain composed of a crosslinking agent. It may be. When the Schiff base type ligand is directly bonded to the reactive functional group in the natural fiber molecule, it may be reacted with the reactive functional group in the natural fiber molecule, and when introduced through the graft chain. May be reacted with a reactive functional group (for example, an epoxy group) of the crosslinking agent.

As the Schiff base type ligand, those represented by the above formula (I) are preferable from the viewpoint of metal ion collection ability and metal selectivity. When a Schiff base ligand represented by the formula (I) in which R ₁ is a hydrogen atom and R ₂ is a bromine atom is used, the formula (I) in which R ₁ is a hydrogen atom and R ₂ is a hydrogen atom Compared to the case where the Schiff base ligand represented by the formula (I) in which the Schiff base ligand represented by R ₁ is a hydrogen atom and R ₂ is a chlorine atom is used, the metal ion collector The metal adsorption rate tends to increase. In particular, it exhibits a high adsorption rate for cobalt ions.

  The Schiff base type ligand represented by the formula (I) can be obtained, for example, by reacting 2 equivalents of salicylaldehyde with 1 equivalent of diethylenetriamine at room temperature in an ethanol solvent and then distilling off the solvent under reduced pressure. Can do.

  Moreover, the metal ion trapping material according to the present embodiment may have a cyclic ligand having a cyclic polyether structure as a chelate-forming group in the natural fiber molecule. The cyclic ligand may be directly bonded to a reactive functional group in the molecule of the natural fiber, or may be introduced to the reactive functional group in the molecule of the natural fiber via a graft chain made of a crosslinking agent. Also good. When the cyclic ligand is directly bonded to the reactive functional group in the natural fiber molecule, it may be reacted with the reactive functional group in the natural fiber molecule. What is necessary is just to make it react with the reactive functional group (for example, epoxy group) of an agent.

  Examples of the cyclic ligand include compounds having crown ethers such as crown ether, azacrown ether, thiacrown ether, and azathiacrown ether. From the viewpoint of metal ion collection ability and metal selectivity, the cyclic ligand is preferably a compound represented by the above formula (II).

  Since the metal ion trapping material according to the present embodiment uses natural fibers, it is friendly to the global environment. Since unused natural fibers that have been discarded so far can be used as the natural fibers of the metal ion collector, it can be said that this is also friendly to the global environment. The metal ion collector according to the present embodiment includes copper and zinc, rare earth such as thulium, ytterbium, scandium, yttrium, and further cesium, cobalt, nickel, lithium, vanadium, chromium, manganese, selenium, rubidium, Ions of various metals including rare metals such as strontium, zirconium, niobium, rhodium, palladium, indium, antimony, tellurium, hafnium, tantalum, tungsten, rhenium and platinum can be collected. In addition, these various metal ions can be selectively collected.

  Hereinafter, examples will be shown and described in more detail. Of course, the present invention is not limited to the following examples.

<Manufacture of collection material 1>
In order to remove the lignin component contained on the surface of the banana fiber, the banana fiber was immersed in a 10-20 wt% sodium hydroxide aqueous solution for 2 hours. After immersion, the banana fibers were washed with ion exchanged water until the pH reached 7. Then, it was dried at 70 ° C. for 1 day. Thus, an alkali-treated banana fiber from which a part of the lignin component contained in the banana fiber was removed was obtained. This alkali-treated banana fiber was used as the collection material 1.

<Manufacture of collection material 2>
After immersing 10 g of the alkali-treated banana fiber in a mixed solution of 0.5 g of diammonium cerium nitrate, 10 mL of ion-exchanged water, 2 g of nitric acid, 10 mL of acetone, and 10 g of glycidyl methacrylate (GMA) for 24 hours at room temperature. Reacted. After the reaction, for purification, ion-exchanged water and ethanol were washed in this order, and then dried at 70 ° C. to obtain banana fiber-g-GMA. This banana fiber-g-GMA was used as the collection material 2. FIG. 1 shows an outline of synthesis of banana fiber-g-GMA. In the chemical formula representing the alkali-treated banana fiber in FIG. 1, n and m in the chemical formula representing the banana fiber-g-GMA are each a positive integer.

<Manufacture of collection material 3>
2 equivalents of salicylaldehyde and 1 equivalent of diethylenetriamine were reacted at room temperature in an ethanol solvent. Thereafter, the solvent was distilled off under reduced pressure, and the desired product (2,2′-iminobis [etane-2,1-diylnitrilo (E) methylidine]) bisphenol derivative (Schiff base type represented by the above formula (I)) Ligand) was obtained. FIG. 2 shows an outline of the synthesis of (2,2′-iminobis [etane-2,1-diylnitrilo (E) methylidine]) bisphenol derivative.
Next, 5 g of (2,2′-iminobis [etane-2,1-diylnitrilo (E) methylidine]) bisphenol derivative was added to 10 g of the banana fiber-g-GMA and reacted for 24 hours. After the reaction, the surface of the banana fiber was washed with acetone and ethanol, and dried at 70 ° C. for 1 day with a drier to obtain the collection material 3. FIG. 3 shows an outline of the synthesis of a trapping material in which a Schiff base ligand is introduced into banana fiber-g-GMA.

<Metal ion collection ability 1 of collection material>
The aqueous phase is metal ions (Co ²⁺ , Ni ²⁺ , Zn ²⁺ , Cu ²⁺ ) 1.0 × 10 ⁻⁴ mol / L, sodium chlorate 1.0 × 10 ⁻¹ mol / L, MES (2-Morpholinoethanesulfonic acid) The concentration was adjusted to 1.0 × 10 ⁻² mol / L, acetic acid 1.0 × 10 ⁻² mol / L, and sodium acetate 1.0 × 10 ⁻² mol / L. 0.3 g of the collection material 1 was added to a centrifugal sedimentation tube for 30 cm ^{3 of the} aqueous phase, and shaken for 5 days. After 5 days, the collection material 1 was filtered, the pH of the aqueous phase was measured, and the adsorption amount of metal ions was measured using ICP-AES. The adsorption amount of metal ions in the aqueous phase with different pH was measured in the same manner.

  For the collection material 2 and the collection material 3, the adsorption amount of metal ions was measured in the same manner as the collection material 1. Furthermore, the trapping material 4 manufactured in the same manner as the trapping material 3 and the commercially available trapping material 5 (amberlite) except that a commercial cellulose was used in place of the banana fiber in the trapping material 3. The amount of adsorbed metal ions was measured in the same manner as in the collector 1.

  The results are shown in FIGS. 4 to 8 are graphs showing the relationship between the adsorption rate of various metal ions and the pH of the aqueous phase. The vertical axis of the graph represents the adsorption rate of metal ions, and the horizontal axis represents the pH of the aqueous phase.

  4 and 5 show the amount of metal ions adsorbed on the collection material 3. FIG. 4A shows the result of the trapping material 3 into which the Schiff base ligand (the functional group R is a hydrogen atom) shown in FIG. 3 is introduced. FIG. 4B shows the result of the trapping material 3 into which the Schiff base ligand (the functional group R is a chlorine atom) shown in FIG. 3 is introduced. FIG. 5 shows the results for the trapping material 3 into which the Schiff base ligand (the functional group R is a bromine atom) shown in FIG. 3 is introduced.

  From the results of FIGS. 4 and 5, the scavenger 3 into which the Schiff base type ligand (functional group R is a bromine atom) is introduced with the Schiff base type ligand (functional group R is a hydrogen atom). The adsorption rate of metal ions is higher than that of the collection material 3 and the collection material 3 into which the Schiff base type ligand (the functional group R is a chlorine atom) is introduced, and in particular, the adsorption rate of cobalt ions is high. Was confirmed. Moreover, the result of FIG.4 and FIG.5 has shown that the collection material 3 can selectively collect a metal ion.

  FIG. 6A shows the amount of metal ions adsorbed on the collection material 1. FIG. 6B shows the amount of metal ions adsorbed on the collection material 2. The results in FIG. 6 indicate that metal ions can be selectively collected without having a Schiff base type ligand.

  Moreover, when the adsorption amount of a metal ion was measured similarly to the collection material 1 about the banana fiber (banana fiber before alkali treatment: banana fiber which has not removed the lignin component) used as the raw material of alkali treatment banana fiber, It was confirmed that ions can be selectively collected.

  FIG. 7 shows the amount of metal ions adsorbed on the collector 4. The result of FIG. 7 shows that the behavior of the adsorption rate of various metal ions is different from that of FIGS.

  FIG. 8 shows the amount of metal ions adsorbed on a commercially available collection material 5 (amberlite). The result of FIG. 8 shows that various metal ions are adsorbed 100% on the collection material 5 and there is no selectivity for collection of metal ions.

<Metal ion collection ability 2 of collection material>
The aqueous phase was metal ions (Yb ²⁺ , Tm ²⁺ ) 1.0 × 10 ⁻⁴ mol / L, sodium perchlorate 1.0 × 10 ⁻¹ mol / L, acetic acid 5.0 × 10 ⁻³ mol / L, MES (2-Morpholinoethanesulfonic acid) was adjusted to 5.0 × 10 ⁻³ mol / L. Add 0.3 g of collection material (collection material 3 into which a Schiff base ligand (functional group R is a bromine atom)) is added to 30 cm ^{3 of the} aqueous phase to the centrifugal settling tube and shake for 5 days. I let you. After 5 days, the collection material 3 was filtered, the pH of the aqueous phase was measured, and the adsorption amount of metal ions was measured using ICP-AES. The adsorption amount of metal ions in the aqueous phase with different pH was measured in the same manner.

The result is shown in FIG. FIG. 9 is a graph showing the relationship between the adsorption rate of various metal ions and the pH of the aqueous phase. The vertical axis of the graph represents the adsorption rate of metal ions, and the horizontal axis represents the pH of the aqueous phase.
The result of FIG. 9 has shown that the collection material 3 can collect a ytterbium ion and a thulium ion favorably. This result suggests that other rare earth ions can be well collected.

<Manufacture of collection material 6>
6.4 g of sodium hydride was placed in a bifurcated flask containing 300 ml of THF (tetrahydrofuran) and refluxed in a nitrogen atmosphere. Thereafter, a mixed solution of 14.5 g of N-phenyldiethanolamine and 40.2 g of tetraethylene alcohol ditosylate was dropped over 5 hours, and then refluxed for 3 hours. After cooling, the residue was filtered while washing with THF. The obtained THF filtrate was distilled off under reduced pressure to obtain the desired product. 10 ml of methanol was added to the obtained object, and a solution obtained by dissolving 11.3 g of sodium perchlorate in 15 ml of methanol was added and refluxed for 10 minutes. Methanol was distilled off under reduced pressure and then recrystallized with ethyl acetate to obtain 12.2 g of N-phenylaza-18-crown-6 perchloric acid sodium salt. Thereafter, decomposition treatment was carried out in a methylene chloride: water (1: 1) solution, and methylene chloride was recovered and distilled under reduced pressure to obtain 7.49 g of N-phenylaza-18-crown-6.

N-phenylaza-18-crown-6 (3.39 g) was dissolved in 5 ml of warm 37% hydrochloric acid and cooled to 5 ° C. with ice water. A solution of 0.7 g NaNO ₂ dissolved in ₂ ml water was slowly added and stirred for 20 minutes. 30 ml of ice water and 20 ml of methylene chloride were added and stirred. Next, when saturated sodium carbonate was added, the organic layer became green. The obtained organic phase was distilled off under reduced pressure to obtain N- (nitrosophenyl) aza-18-crown-6 which was the target product.

N- (nitrosophenyl) aza-18-crown-6 was dissolved in 3 ml of 37% hydrochloric acid, and a solution of 1.85 g of tin chloride in 1.6 ml of water was added at 40 ° C. with stirring. After stirring for 20 minutes, water was added and the mixture was further stirred for 30 minutes. Thereafter, when 40% sodium hydroxide was added, a brown oily substance was precipitated. The precipitate was extracted with methylene chloride, and the solvent was distilled under reduced pressure to obtain N- (4-aminophenyl) aza-18-crown-6 ether (cyclic ligand represented by the above formula (II)). FIG. 10 shows an outline of the synthesis of N- (4-aminophenyl) aza-18-crown-6 ether.
1.5 g of the banana fiber-g-GMA was put in acetonitrile in which N- (4-aminophenyl) aza-18-crown-6 ether was dissolved, and the mixture was placed for one day. Then, it wash | cleaned with acetonitrile and acetone and the collection material 6 was obtained. FIG. 11 shows an outline of synthesis of a trapping material in which a cyclic ligand is introduced into banana fiber-g-GMA.

<Metal ion collection ability 3 of collection material>
30 ml of 1.0 × 10 ⁻⁴ M cesium solution and 0.3 g of the collecting material 6 were placed in a centrifuge tube and shaken for 5 days. Next, the solution collected in the shaking experiment was diluted 10 times, and cesium ions in the solution were quantified using atomic absorption. From this result, the adsorption rate of the cesium ions of the trapping material 6 was determined. For the collection material 2, the adsorption rate of cesium ions was determined in the same manner as the collection material 6.
The result is shown in FIG. The result of FIG. 12 has shown that the collection material 2 and the collection material 6 can collect a cesium ion. Moreover, from this result, it was confirmed that the adsorption capacity of the cesium ions of the collection material 6 is better than that of the collection material 2.

<Collector 7-11>
The banana fiber in the collection material 1 was used as it was without performing the alkali treatment for removing the lignin component, and this was used as the collection material 7.
About this collection material 7, the process similar to manufacture of the collection material 2 from the said collection material 1 was performed, and the banana fiber-g-GMA was obtained. This was designated as collection material 8.
Natural fiber hemp was used as the collection material 9, commercially available crystalline cellulose was used as the collection material 10, and zeolite was used as the collection material 11.

<Metal ion collection ability 4 of collection material>
0.3 g of each collection material was put into 30 cm ^{3 of} an aqueous phase adjusted to a cesium concentration of 10 to 1000 ppb and shaken for 1 hour. Thereafter, the residual cesium concentration in the aqueous phase was measured using an atomic absorption photometer, and the adsorption rate was determined.
The results are shown in FIGS. FIG. 13 is a collection material 7 (alkali untreated banana fiber), FIG. 14 is a collection material 8 (alkali untreated banana fiber-g-GMA), FIG. 15 is a collection material 1 (alkali treated banana fiber), and FIG. Is the collection material 2 (alkali-treated banana fiber-g-GMA), FIG. 17 is the collection material 9 (hemp), FIG. 18 is the collection material 10 (crystalline cellulose), and FIG. 19 is the collection material 11 (zeolite). It is a result.

<Metal ion collection ability 5 of collection material>
In 30 cm ^{3 of} the aqueous phase adjusted to a strontium concentration of 25 to 300 ppb, 0.3 g of the collection material 7 (alkali untreated banana fiber) was added and shaken for 1 hour. Thereafter, the residual strontium concentration in the aqueous phase was measured using an atomic absorption photometer to determine the adsorption rate.
The result is shown in FIG.

Claims (3)

Consists banana fiber, to a reactive functional group in a molecule of the banana fiber, a graft chain consisting of cross-linking agent is introduced, Schiff base ligand represented by the following formula (I) through the graft chain Is a metal ion collector.
(In the formula, R ₁ represents a hydrogen atom, and R ₂ represents a bromine atom or a chlorine atom.) The banana fibers, metal ion trapping material according to claim 1, characterized in that the banana fiber portion of the lignin components contained in the banana fibers are removed. The metal ion scavenger according to claim 1 or 2, wherein the cross-linking agent is a compound having a vinyl group and an epoxy group in a molecule .