WO2025135120A1 - Adsorbent for polar molecules, concentration method and recovery method for polar molecules, and indicator - Google Patents

Abstract

A molecular adsorbent according to the present invention adsorbs polar molecules and contains, as an active ingredient, an ion exchanger having: an ion exchange resin comprising ion exchange groups that are strongly acidic groups; and a metal ion complex or metal ions ion-exchanged by the ion exchange groups. The polar molecules include nitrogen atoms that have unshared electron pairs. The metal ions are one or more species of trivalent or higher metal ions from among Co²⁺, Cu²⁺, Ni²⁺, Mn²⁺, V²⁺, Cs⁺, Rb⁺, and K⁺.

Description

Adsorbent for polar molecules, method for concentrating and recovering polar molecules, and indicator

This application relates to a molecular adsorbent that adsorbs polar molecules present in a gas or liquid, a method for concentrating polar molecules using the active ingredient of this molecular adsorbent, and an indicator for determining the adsorption of ammonia and/or amines.

Molecules such as ammonia and nitrogen dioxide contained in gas, and molecules such as ammonia and urea contained in solution, are harmful. For this reason, these molecules are rendered harmless by combustion, biodegradation, and adsorption with adsorbents. Among these detoxification processes, adsorption with adsorbents involves using an adsorbent that highly selectively adsorbs harmful molecules to adsorb and recover the harmful molecules, and then desorbing and concentrating them, allowing the harmful molecules to be used as a resource. For example, in a liquid containing toluene, a hydrophobic molecule, and water molecules, the toluene can be reused as a resource by adsorbing the toluene onto activated carbon and then desorbing it.

On the other hand, polar molecules containing nitrogen atoms with unshared electron pairs, such as ammonia and urea, are difficult to separate from water molecules containing oxygen atoms with unshared electron pairs. For this reason, it has been difficult to develop an adsorbent that selectively adsorbs polar molecules in water and in a gas containing water vapor. In addition, in order to reuse them as resources, it is desirable to recover them in the form of a single molecule or an aqueous solution. For example, if ammonia and urea can be recovered as a high-concentration aqueous solution, the recovered ammonia and urea can be used as fertilizer or a reagent for removing _NOx from exhaust gas.

A neutralization reaction using an ion exchanger containing protons allows the ion exchanger to selectively adsorb polar molecules containing nitrogen atoms with unshared electron pairs, such as ammonia and trimethylamine. However, a large amount of energy is required to separate the basic molecules adsorbed on the ion exchanger from the protons. In addition, a technique is known in which ammonia is adsorbed on an ion exchange resin containing zinc ions (Zn ²⁺ ) and then desorbed as ammonium ions using an acid (Patent Documents 1 to 3).

In these techniques, molecules are recovered not as a solution but as a salt such as sulfate, making it difficult to isolate the molecules. In order to reuse the recovered polar molecules as a resource, it is desirable to desorb the molecules without using chemicals such as acids. In Patent Document 1, zinc ions are supported on an ion exchange resin, ammonia is adsorbed, and the resin is washed with a solution containing sulfuric acid and zinc sulfate, recovering the adsorbed ammonia as an aqueous solution of ammonium zinc sulfate. However, in order to separate zinc sulfate and ammonia from the liquid recovered as an aqueous solution of ammonium zinc sulfate, reagents and a large amount of energy are required, which is a cost factor.

Similarly, in Patent Documents 2 and 3, an acid such as sulfuric acid is used to desorb ammonia adsorbed on an ion exchange resin. This ammonia is recovered as ammonium ions by reaction with the acid. Ammonia recovered as ammonium ions cannot be reused as ammonia unless it is separated from the acid by ammonia stripping or the like. For this reason, in practice, it is desirable to recover polar molecules as a single molecule or as an aqueous solution using water and air, rather than using an acid to desorb polar molecules adsorbed on an ion exchange resin. There is no problem with heating during desorption, so long as the temperature range is such that polar molecules such as ammonia are not burned or thermally decomposed.

It is also known that ammonia is coordinated to metal ions such as Ni2 ⁺ introduced into an ion exchanger having a carboxyl group (Non-Patent Document 1). However, Non-Patent Document 1 does not mention the effect of the functional group responsible for ion exchange on molecular adsorption, the amount of ammonia adsorbed, or whether ammonia can be recovered. Furthermore, when a polar molecule containing a nitrogen atom having an unshared electron pair is analyzed using a conventional ion exchanger, if the polar molecule is ammonia, it can cause bad odors and water pollution, so a simple analysis method is required.

　Ion chromatography, which converts ammonia into ammonium ions in the acidic range, and the indophenol method are known as analytical methods for ammonia. However, ion chromatography requires large equipment, and the indophenol method is complicated to operate. Passive indicators and gas detector tubes that change color depending on the ammonia concentration are known as methods for easily detecting ammonia in gas. However, these utilize color changes due to irreversible reactions, so time and reaction volume management are required. In order to easily monitor the concentration of ammonia and/or amines, it is desirable to develop an indicator for ammonia and/or amines that adsorbs ammonia and/or amines at any concentration and changes color using a reversible reaction that allows desorption.

Special Publication No. 2002-501427 U.S. Pat. No. 4,263,145 U.S. Pat. No. 4,695,387

Ligand Exchange. I. Equilibria, F. Hefferich Journal of American Chemical Society,1962, 84, P 3237-3242

The present application has been made in view of the above circumstances, and aims to provide an adsorbent that can recover a substance containing a polar molecule, such as ammonia, that contains a nitrogen atom having an unshared electron pair when the polar molecule is adsorbed. It also aims to provide a method for concentrating a polar molecule that contains a nitrogen atom having an unshared electron pair using the active ingredient of the adsorbent. It also aims to provide an indicator for ammonia and/or amines that changes color by utilizing a reversible, detachable reaction.

　It is generally known that the selectivity of metal ions adsorbed to ion exchange groups differs depending on whether the ion exchange groups in the ion exchange resin are strongly acidic sulfonic acid groups or weakly acidic carboxyl groups. However, it was not known that the adsorption capacity of polar molecules containing a nitrogen atom with an unshared electron pair of the metal ion exchanged with the ion exchange group differs depending on the difference in these ion exchange groups. The inventors of the present application ion-exchanged metal ions with the ion exchange groups of various ion exchange resins and evaluated their adsorption capacity for polar molecules. As a result, they found that metal ions exchanged with strongly acidic sulfonic acid groups are effective for polar molecule adsorption.

The molecular adsorbent according to one embodiment of the present invention has as its active ingredient an ion exchanger having an ion exchange resin with ion exchange groups that are strong acidic groups, and a metal ion or a complex of a metal ion that has been ion-exchanged by the ion exchange groups, and adsorbs polar molecules. The polar molecule contains a nitrogen atom having an unshared electron pair. The metal ion is one or more of trivalent or higher metal ions, Co2 ⁺ , Cu2 ⁺ , Ni2 ⁺ , Mn2 ⁺ , V2 ⁺ , Cs ⁺ , Rb ⁺ , and K ⁺ .

The indicator for ammonia and/or amine according to one embodiment of the present invention contains as its active ingredient an ion exchanger having an ion exchange resin with ion exchange groups that are strongly acidic groups, and a metal ion or a complex of a metal ion that has been ion-exchanged by the ion exchange groups, and can determine the adsorption of ammonia and/or amine to the ion exchanger by a color change. The metal ion is Co2 ⁺ , Ni2 ⁺ , Cu2 ⁺ , Fe3 ⁺ , or Mn2 ⁺ .

A method for concentrating polar molecules according to one embodiment of the present invention includes an adsorption step of contacting a gas or liquid containing polar molecules with an ion exchanger having an ion exchange resin with ion exchange groups that are strong acidic groups and a metal ion having a valence of three or more, one or more of Co2 ⁺ , Cu2 ⁺ , Ni2 ⁺ , Mn2 ⁺ , V2 ⁺ , Zn2 ⁺ , Cs ⁺ , Rb ⁺ , and K ^+, which has been ion-exchanged by the ion exchange groups, to adsorb the polar molecules, and a condensation step of heating the ion exchanger with the polar molecules adsorbed thereon and condensing the gas generated from the ion exchanger.

　The molecular adsorbent of the present application makes it possible to recover polar molecules containing a nitrogen atom having an adsorbed unshared electron pair by a simple operation such as heating. According to the method for concentrating polar molecules of the present application, a polar molecule containing a nitrogen atom having an unshared electron pair is adsorbed onto a specific ion exchanger, and then the ion exchanger is heated to condense the resulting gas, thereby concentrating the polar molecule. Furthermore, according to the indicator for ammonia and/or amines of the present application, the adsorption of ammonia and/or amines can be determined by a color change.

Graph showing the relationship between the ion exchanger of Example 1 and the amount of urea adsorption. Graph showing the relationship between the ion exchanger of Example 2 and the amount of urea adsorption. Graph showing the relationship between the ion exchanger or ion exchange resin of Example 5 and the ammonia adsorption amount. Graph showing the relationship between the ion exchanger of Example 6 and the amount of ammonia released from the acid. 1 is a graph showing the change in the amount of ammonia desorbed when ammonia adsorption and desorption are repeated using the strongly acidic ion exchanger containing Ni ²⁺ in Example 9. 1 is a graph showing the change in the amount of urea desorbed when urea adsorption and desorption are repeated on the Ti ⁴⁺ -containing strongly acidic ion exchanger of Example 10. 1 is a graph showing the cumulative amount of urea adsorbed when urea was adsorbed again on the strongly acidic ion exchanger having Ti ⁴⁺ in Example 10 after 30 cycles of urea adsorption and desorption were repeated. 1 is a graph showing the cumulative amount of urea desorbed when urea was re-adsorbed on the Ti ⁴⁺ -containing strongly acidic ion exchanger of Example 10 after 30 cycles of urea adsorption and desorption were repeated and then the urea was desorbed. FIG. 13 is a schematic diagram showing the recovery of urea from an adsorbent made of a strongly acidic ion exchanger containing metal ions in Example 11. 1 is an image showing a glass container in which solid urea was collected in Example 11. Graph showing the adsorption amount of trimethylamine in an aqueous solution of Example 12. Graph showing the amount of butylamine adsorbed in an aqueous solution in Example 13.

The molecular adsorbent of one embodiment of the present application has a specific ion exchanger (hereinafter sometimes referred to as the "ion exchanger of this embodiment") as an active ingredient. The molecular adsorbent of this embodiment adsorbs polar molecules containing a nitrogen atom with an unshared electron pair (hereinafter sometimes referred to as the "specific polar molecule"). There are no particular limitations on the specific polar molecule as long as it can be coordinated to the metal of the ion exchanger of this embodiment. Examples of such specific polar molecules include ammonia in which a nitrogen atom is coordinated to a metal, nitrogen oxides in which an oxygen atom is coordinated to a metal, organic compounds such as urea having a keto group, and organic compounds having an amino group or an amide group.

Among these, the specified polar molecule is preferably at least one of ammonia, amine, and urea, which are highly valuable for reuse, and may be, for example, ammonia, amine, or urea. In addition, there are no particular limitations on the form in which the specified polar molecule exists, so long as it can come into contact with the molecular adsorbent. In other words, the specified polar molecule may be in a state in which it is contained in a gas, or in a state in which it is contained in a liquid such as water or an organic medium, for example, dissolved in water or an organic solvent.

The polar molecular amine adsorbed by the molecular adsorbent of this embodiment may be, for example, at least one of trimethylamine and butylamine, or may be an amine other than monomethylamine and dimethylamine (amines other than monomethylamine and dimethylamine are adsorbed). In other words, the molecular adsorbent of this embodiment may be a molecular adsorbent for adsorbing the above-mentioned polar molecules. The present invention can also provide an adsorbent material containing the molecular adsorbent of this embodiment.

The ion exchanger of this embodiment includes an ion exchange resin and a metal ion or a complex of this metal ion. The ion exchange resin includes an ion exchange group that is a strongly acidic group. The type of the ion exchange resin is not particularly limited as long as it has a strongly acidic group, and for example, a commercially available ion exchange resin can be used. An example of the strongly acidic group is a sulfonic acid group. The metal ion or the complex of this metal ion is ion-exchanged with the ion exchange group, more specifically, with a cation such as an H ion or a Na ion of the ion exchange group. In other words, the metal ion or the complex of this metal ion is bonded to the ion exchange group. The metal ion is one or more of trivalent or higher metal ions, Co2 ⁺ , Cu2 ⁺ , Ni2 ⁺ , Mn2 ⁺ , V2 ⁺ , Cs ⁺ , Rb ⁺ , and K ⁺ , and may be one or more of trivalent or higher metal ions, Co2 ⁺ , Ni2 ⁺ , ^{Mn2 +} , V2+, Cs ⁺ , Rb ⁺ , and K ⁺ . Copper ions may be excluded from the metal ions of the ion exchanger (in other words, metal ions other than copper ions may be bonded to the above ion exchange groups).

Examples of trivalent or higher metal ions include at least one of Fe ³⁺ , Cr ³⁺ , Al ³⁺ , Ti ³⁺ , In ³⁺ , Ru ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , Sn ⁴⁺ and Hf ⁴⁺ . When the metal ion is at least one of Fe ³⁺ , Ti ³⁺ , Ru ³⁺ , Zr ⁴⁺ , Hf ⁴⁺ , Sn ⁴⁺ and Cs ⁺ , the amount of urea that can be adsorbed by the molecular adsorbent of this embodiment is large. Therefore, when the molecular adsorbent of this embodiment is used as a urea adsorbent, it is preferable that the metal ion is one of these metal ions. In addition, when the metal ion is Ni ²⁺ and/or Cu ²⁺ , the amount of ammonia that can be adsorbed by the molecular adsorbent of this embodiment is large. Therefore, when the molecular adsorbent of this embodiment is used as an ammonia adsorbent, it is preferable that the metal ion is at least one of Ni ²⁺ and Cu ²⁺ .

Furthermore, when the polar molecule is particularly an amine (e.g., at least one of trimethylamine and butylamine), the metal ion may be one or more selected from the group consisting of Co2 ⁺ , Ni2 ⁺ , Cu2 ⁺ , Mn2 ⁺ and Fe3 ⁺ , or may be one or more selected from the group consisting of Co2 ⁺ , Ni2 ⁺ , Mn2 ⁺ and Fe3 ⁺ .

In the molecular adsorbent of this embodiment, Zn ²⁺ is not ion-exchanged with an ion exchange group. Zn ²⁺ is an ion that is toxic to living organisms depending on the concentration. For this reason, in Japan, Zn ²⁺ has a strict discharge standard of less than 2 mg/L according to the general wastewater standard of the Water Pollution Prevention Law. Trivalent or higher metal ions, Co ²⁺ , Cu ²⁺ , Ni ²⁺ , Mn ²⁺ , V ²⁺ , Cs ⁺ , Rb ⁺ , Sn ⁴⁺ and K ⁺ have higher general wastewater standard concentration standard values than Zn ²⁺ , or are not regulated by the Water Pollution Prevention Law. In other words, these metals are less toxic than Zn ²⁺ , so that the safety of using the molecular adsorbent of this embodiment is improved. If the substance amount (so-called molar amount) of the metal ion contained in the ion exchanger of this embodiment is large, the adsorption amount of polar molecules will also be large. The metal ion concentration of the ion exchanger (amount of substance of metal ion/mass of ion exchanger) is preferably 0.05 mmol/g or more, more preferably 0.2 mmol/g or more, and particularly preferably 0.5 mmol/g or more.

The form of the metal ion exchanged in the ion exchanger may be not only the metal ion but also a metal ion complex, even if it is coordinated with hydration water or a chelate, as long as it does not inhibit the adsorption of a specific polar molecule to the ion exchanger. For example, the form of the metal ion exchanged in the ion exchanger may be an ammine complex in which ammonia is coordinated to the metal ion. The molecular adsorbent of this embodiment may contain, in addition to the ion exchanger, a thickener, a binder, or a base material that ensures the strength of the molecular adsorbent itself.

In one embodiment, the present invention can provide an adsorption method for adsorbing polar molecules using the molecular adsorbent described above. In this embodiment, the polar molecules are as described above.

In one embodiment, the present invention can provide the use of the above-mentioned molecular adsorbent for adsorption (or recovery) of the above-mentioned polar molecules.

The inventors of the present application have also found that when ammonia or amine is adsorbed onto some of the ion exchangers of this embodiment, the adsorption of ammonia or amine onto the ion exchanger can be ascertained by the color change of the ion exchanger. In these ion exchangers, it is believed that the amino group of the amine is coordinated to the metal ion contained in the ion exchanger. Ion exchangers that include metal ions that have electrons in their d orbitals but where the d orbitals are not completely filled with electrons generally have a visible color because the energy difference when an electron in a d orbital transitions to an empty d orbital generally corresponds to the energy of visible light.

It is speculated that the color of these ion exchangers appears to change when the amino group coordinates with the metal ion because the energy level of the d orbital changes. This speculation is supported by the fact that ion exchangers with sodium ions that do not have electrons in the d orbital did not change color upon adsorption of ammonia. Therefore, it is thought that amines in general that have amino groups, other than ammonia, will also change color when adsorbed onto these ion exchangers. The ammonia and/or amine indicator of the embodiment of the present application has as its active ingredient an ion exchanger that has an ion exchange resin with an ion exchange group that is a strongly acidic group, and a metal ion or a complex of a metal ion that has been ion-exchanged by this ion exchange group.

In the indicator for ammonia and/or amine of this embodiment, the adsorption (presence or absence of adsorption and the amount of adsorption) of ammonia and/or amine to the ion exchanger is judged by the color change of the ion exchanger. Therefore, the indicator of this embodiment may be an indicator for judging the presence or absence and amount of ammonia, or may be an indicator for judging the presence or absence and amount of amine. The metal ion is Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Fe ³⁺ , or Mn ²⁺ , and may be Co ²⁺ , Ni ²⁺ , Fe ³⁺ , or Mn ²⁺ . In addition, the color change increases with an increase in the amount of ammonia and/or amine adsorbed to the ion exchanger. Therefore, the indicator for ammonia and/or amine of this embodiment can quantitatively evaluate the amount of adsorption of ammonia and/or amine. The amine may be, for example, at least one of trimethylamine, butylamine, diethylamine, and monoethanolamine, at least one of trimethylamine and butylamine, or an amine other than monomethylamine and dimethylamine.

The specific color change of the ion exchanger when it adsorbs polar molecules varies depending on the types of metal ions and ammonia and/or amines, but examples of the color change include the following:
Co ²⁺ : reddish brown to blackish brown Ni ²⁺ : yellowish green to blue or green Cu ²⁺ : green to blue-purple or blue Fe ³⁺ : reddish brown to blackish brown Mn ²⁺ : orange (reddish brown) to blackish brown

The ion exchanger according to the embodiment of the molecular adsorbent and the indicator for ammonia and/or amine can be prepared, for example, as follows: First, an ion exchange resin having an ion exchange group that is a strongly acidic group is prepared. Such ion exchange resins are commercially available. When the cation of the ion exchange group is an H ion, the ion exchange resin is placed in an aqueous NaOH solution and stirred or shaken to convert the cation of the ion exchange group to a Na ion. This is to facilitate the exchange of the cation of the ion exchange resin with the target metal ion, such as Ni2 ⁺ or Mn2 ⁺ .

Next, the Na ions of the ion exchange resin are exchanged for the desired metal ions. This is done by placing the ion exchange resin in an aqueous solution of the desired metal ions (metal salt aqueous solution) and stirring or shaking the resin. After repeating the washing process with ultrapure water several times, the resin is subjected to a dehydration process such as suction filtration and a drying process at a temperature of about 40°C to 60°C, and the ion exchanger of this embodiment is obtained.

The ion exchanger of this embodiment can desorb a high concentration of adsorbed specific polar molecules by heating. Note that there are other ion exchangers other than the ion exchanger of this embodiment that can desorb a high concentration of adsorbed specific polar molecules by heating.

The method for concentrating polar molecules according to one embodiment of the present application includes an adsorption step and a condensation step. In the adsorption step, a gas or liquid containing a specific polar molecule is brought into contact with the ion exchanger described above to adsorb the polar molecule containing a nitrogen atom having an unshared electron pair. As described above, the ion exchanger used in the concentration method according to this embodiment is similar to the ion exchanger according to the embodiment of the molecular adsorbent described above, and includes an ion exchange resin having ion exchange groups that are strong acidic groups, and a metal ion or a complex of this metal ion that has been ion-exchanged by the ion exchange groups.

The metal ion is one or more of the trivalent or higher metal ions Co2 ⁺ , Cu2 ⁺ , Ni2 ⁺ , Mn2 ⁺ , V2 ⁺ , Zn2 ⁺ , Cs ⁺ , Rb ⁺ , and K ⁺ . The trivalent or higher metal ion may be one or more of Fe3 ⁺ , Cr3 ⁺ , Al3 ⁺ , Ti3 ⁺ , In3 ⁺ , Ru3 ⁺ , Ti4 ⁺ , Zr4 ⁺ , Sn4 ⁺ , and Hf4 ⁺ as described above.

The polar molecule is preferably at least one of ammonia and urea. Since the adsorption phenomenon is generally an exothermic reaction, it is preferable to carry out the adsorption process at a low temperature. The temperature at which the adsorption process is carried out is preferably 50°C or less, more preferably 30°C or less, and even more preferably 10°C or less.

In the condensation process, the ion exchanger to which the above-mentioned polar molecules are adsorbed is heated, and the gas generated from the ion exchanger is condensed. The above-mentioned polar molecules are contained in the condensed liquid. The concentration of the above-mentioned polar molecules in this liquid is greater than the concentration of the specified polar molecules in the gas or liquid that was brought into contact with the ion exchanger in the adsorption process. In the condensation process, it is preferable to heat the ion exchanger to a temperature that is 60°C or higher and lower than the heat resistance temperature of the ion exchanger. The heating temperature of this ion exchanger is more preferably 80°C or higher, and even more preferably 100°C or higher. This is because the higher the temperature, the greater the amount and speed of desorption of the specified polar molecules.

In the condensation process, the ion exchanger may be heated while being brought into contact with water vapor. This is because a condensed liquid containing a higher concentration of the specified polar molecule is obtained. Furthermore, in the condensation process, the specified polar molecule may be desorbed from the ion exchanger by flowing water or gas around the ion exchanger. In addition to inert gases such as nitrogen, argon, or helium, air containing oxygen may be used as the gas as long as it does not decompose the specified polar molecule to be desorbed.

In another preferred embodiment, the present invention provides a method for recovering urea (an example of a polar molecule) concentrated by the above-mentioned method for concentrating a polar molecule, in which the trivalent or higher metal ion used in the concentration method may be one or more selected from the group consisting of Fe ³⁺ , Cr ³⁺ , Al ³⁺ , Ti ³⁺ , In ³⁺ , Ru ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , Sn ⁴⁺ , and Hf ⁴⁺ .

This recovery method includes a step of heating a container that contains the ion exchanger (adsorbent) with urea adsorbed thereon, and applying negative pressure to the top of the container to suck in and precipitate solid urea. As will be described in detail later in the Examples, by placing the ion exchanger with urea adsorbed in a container and sucking in from the top of the container while heating it (in other words, applying negative pressure), urea can be precipitated on the top of the container or the like, and solid urea can be recovered.

Preparation Example 1
A 50 mL centrifuge tube was charged with 4 g of a strongly acidic ion exchange resin having sulfonic acid groups (Muromachi Chemical Co., Ltd., Muromax XSC-1614-Na (hereinafter sometimes referred to as "XSC.Na ⁺ ")) and 40 mL of a 0.2 mol/L metal salt aqueous solution. The centrifuge tube was shaken overnight at a temperature of 25°C and a rotation speed of 400 rpm. The centrifuge tube was then centrifuged at a centrifugal acceleration of 3000G for 1 minute, the supernatant was discarded, and 10 mL of ultrapure water (Milli-Q water (hereinafter the same)) was added. This process was repeated three times, and the tube was dehydrated by suction filtration. After dehydration, the tube was dried at a temperature of 60°C to obtain various ion exchangers, which are ion exchange resins in which Na ions have been exchanged for various metal ions.

The names of the metal salt aqueous solutions or the metal salts contained in the metal salt aqueous solutions and the ion exchangers obtained from the metal salt aqueous solutions are listed below.
Cobalt (II) nitrate hexahydrate: XSC.Co2 ⁺
Nickel (II) nitrate hexahydrate: ^XSC.Ni
Copper (II) sulfate pentahydrate: XSC. Cu ²⁺
Iron (III) nitrate nonahydrate: XSC. Fe ³⁺
Chromium(III) chloride hexahydrate: XSC.Cr3 ⁺
Manganese(II) chloride tetrahydrate: XSC.Mn2 ⁺
Aluminum nitrate nonahydrate: XSC.Al ³⁺
Indium(III) chloride tetrahydrate: XSC.In3 ⁺
Vanadium(II) chloride: XSC.V2 ⁺
Titanium(III) chloride 20 wt% aqueous solution: XSC.Ti3 ⁺
Vanadium(III) chloride: XSC.V3 ⁺
Zirconium chloride (IV): XSC.Zr4 ⁺
Ruthenium(III) chloride n-hydrate: XSC.Ru3 ⁺
Zinc sulfate (II) heptahydrate: XSC.Zn2 ⁺
Strontium(II) chloride hexahydrate: XSC.Sr2 ⁺
Calcium chloride (II): ^XSC.Ca
Magnesium(II) chloride hexahydrate: XSC.Mg2 ⁺
Cesium chloride: XSC.Cs ⁺
Rubidium chloride: XSC.Rb ⁺
Potassium chloride: XSC.K ⁺
Hafnium(IV) chloride: XCS.Hf4 ⁺

Preparation Example 2
Various ion exchangers in which Na ions were exchanged for various metal ions were obtained in the same manner as in Preparation Example 1, except that a weakly acidic ion exchange resin having a carboxyl group (Organo Corporation, FPC3500) was treated with NaOH to exchange H ions for Na ions instead of the strongly acidic ion exchange resin in Preparation Example 1, and that the metal salts contained in the aqueous metal salt solution were partially different.

The names of the metal salt aqueous solutions or the metal salts contained in the metal salt aqueous solutions and the ion exchangers obtained from the metal salt aqueous solutions are listed below.
Nickel (II) nitrate hexahydrate: FPC3500. ^Ni
Iron (III) nitrate nonahydrate: FPC3500 ^{. Fe3+}
Chromium(III) chloride hexahydrate: FPC3500. ^Cr3+
Manganese(II) chloride tetrahydrate: FPC3500. ^Mn2+
Aluminum nitrate nonahydrate: FPC3500. ^{Al 3+}
Titanium chloride (III) 20 wt% aqueous solution: FPC3500. ^Ti3+

Preparation Example 3
Various ion exchangers in which Na ions were exchanged with various metal ions were obtained in the same manner as in Preparation Example 2, except that instead of the weakly acidic ion exchange resin in Preparation Example 2, a weakly acidic ion exchange resin having a carboxyl group (Organo Corporation, Amberlite irc-76) was used which was treated with NaOH to exchange H ions with Na ions.

The names of the metal salt aqueous solutions or the metal salts contained in the metal salt aqueous solutions and the ion exchangers obtained from the metal salt aqueous solutions are listed below.
Nickel (II) nitrate hexahydrate: irc-76. ^{Ni 2+}
Iron (III) nitrate nonahydrate: irc-76. Fe ³⁺
Chromium(III) chloride hexahydrate: IRC-76.Cr3 ⁺
Manganese(II) chloride tetrahydrate: irc-76.Mn2 ⁺
Aluminum nitrate nonahydrate: irc-76. ^{Al 3+}
Titanium chloride (III) 20 wt% aqueous solution: irc-76. ^{Ti 3+}

Preparation Example 4
Various ion exchangers in which Na ions were exchanged with various metal ions were obtained in the same manner as in Preparation Example 2, except that instead of the weakly acidic ion exchange resin in Preparation Example 2, a strongly acidic ion exchange resin having sulfonic acid groups (Alfa Aesar, Amberlite ir-120) was used which was treated with NaOH to exchange H ions with Na ions.

The names of the metal salt aqueous solutions or the metal salts contained in the metal salt aqueous solutions and the ion exchangers obtained from the metal salt aqueous solutions are listed below.
Nickel (II) nitrate hexahydrate: ir-120. ^Ni
Iron (III) nitrate nonahydrate: ir-120.Fe3 ⁺
Chromium(III) chloride hexahydrate: ir-120.Cr3 ⁺
Manganese(II) chloride tetrahydrate: ir-120.Mn2 ⁺
Aluminum nitrate nonahydrate: ir-120. ^{Al 3+}
Titanium(III) chloride 20 wt% aqueous solution: ir-120. ^Ti3+

Preparation Example 5
Various ion exchangers in which Na ions were exchanged with various metal ions were obtained in the same manner as in Preparation Example 2, except that instead of the weakly acidic ion exchange resin in Preparation Example 2, a strongly acidic ion exchange resin having sulfonic acid groups (Alfa Aesar, Amberlyst 15) was used which was treated with NaOH to exchange H ions with Na ions.

The names of the metal salt aqueous solutions or the metal salts contained in the metal salt aqueous solutions and the ion exchangers obtained from the metal salt aqueous solutions are listed below.
Nickel (II) nitrate hexahydrate: A15. ^Ni
Iron (III) nitrate nonahydrate: A15. ^Fe3+
Chromium(III) chloride hexahydrate: A15. ^Cr3+
Manganese(II) chloride tetrahydrate: A15. ^Mn2+
Aluminum nitrate nonahydrate: A15. Al ³⁺
Titanium chloride (III) 20 wt% aqueous solution: A15. ^Ti3+

Preparation Example 6
Various ion exchangers in which Na ions were exchanged with various metal ions were obtained in the same manner as in Preparation Example 2, except that a weakly acidic ion exchange resin having a carboxyl group (Mitsubishi Chemical Corporation, Relite WK60L) was treated with NaOH to exchange H ions with Na ions instead of the weakly acidic ion exchange resin in Preparation Example 2.

The names of the metal salt aqueous solutions or the metal salts contained in the metal salt aqueous solutions and the ion exchangers obtained from the metal salt aqueous solutions are listed below.
Nickel (II) nitrate hexahydrate: ^WK60.Ni
Iron (III) nitrate nonahydrate: WK60. Fe ³⁺
Chromium(III) chloride hexahydrate: WK60.Cr3 ⁺
Manganese(II) chloride tetrahydrate: WK60.Mn2 ⁺
Aluminum nitrate nonahydrate: WK60.Al ³⁺
Titanium chloride (III) 20 wt% aqueous solution: WK60.Ti3 ⁺

Preparation Example 7
Various ion exchangers in which Na ions were exchanged with various metal ions were obtained in the same manner as in Preparation Example 2, except that a weakly acidic ion exchange resin having a carboxyl group (Mitsubishi Chemical Corporation, Relite WK100) was treated with NaOH to exchange H ions with Na ions instead of the weakly acidic ion exchange resin in Preparation Example 2.

The names of the metal salt aqueous solutions or the metal salts contained in the metal salt aqueous solutions and the ion exchangers obtained from the metal salt aqueous solutions are listed below.
Nickel (II) nitrate hexahydrate: ^WK100.Ni
Iron (III) nitrate nonahydrate: WK100.Fe3 ⁺
Chromium(III) chloride hexahydrate: WK100.Cr3 ⁺
Manganese(II) chloride tetrahydrate: WK100.Mn2 ⁺
Aluminum nitrate nonahydrate: WK100.Al ³⁺
Titanium chloride (III) 20 wt% aqueous solution: WK100. ^Ti3+

Preparation Example 8
In a beaker, 420 g of the same ion exchange resin as in Preparation Example 1 and 700 mL of an aqueous _TiCl3 solution containing about 6 wt% Ti were placed and stirred with a magnetic stirrer for 4 hours. In order to wash and remove the salt in the water, the process of discarding the supernatant and adding 700 mL of water was repeated six times. The water was filtered to recover the wet ion exchange resin, which was then dried at a temperature of 60°C. The ion exchange resin after drying exhibited the purple color of Ti3 ⁺ .

In order to oxidize Ti ³⁺ in the ion exchange resin to Ti ⁴⁺ , 230 g of the ion exchange resin and 500 mL of ultrapure water were placed in a 5 L beaker and stirred with a mechanical stirrer for 3 hours. After suction filtration and drying at 60°C, XSC.Ti ⁴⁺ , which is an ion exchange resin with Ti ⁴⁺ adsorbed thereon, was obtained. XSC.Ti ⁴⁺ exhibited the original orange color of the ion exchange resin.

Preparation Example 9
In a 1 L container, 100 g of the same ion exchange resin as in Preparation Example 1 and 400 mL of a 0.4 mol/L metal salt aqueous solution were placed. The container was shaken at room temperature and a rotation speed of 400 rpm for three nights. After shaking, the mixture was filtered by suction and dried at a temperature of 60° C. to obtain various ion exchangers, which are ion exchange resins in which Na ions were exchanged with various metal ions.

The names of the metal salt aqueous solutions or the metal salts contained in the metal salt aqueous solutions and the ion exchangers obtained from the metal salt aqueous solutions are listed below.
Silver nitrate: gXSC (for gas, same as XSC above). Ag ⁺
Chromium(III) chloride hexahydrate: gXSC.Cr3 ⁺
Manganese(II) chloride tetrahydrate: gXSC.Mn2 ⁺
Iron (III) nitrate nonahydrate: gXSC. Fe ³⁺
Cobalt (II) nitrate hexahydrate: gXSC.Co2 ⁺
Nickel (II) nitrate hexahydrate: ^gXSC.Ni
Copper (II) sulfate pentahydrate: gXSC. Cu ²⁺
Zinc sulfate (II) heptahydrate: XSC.Zn2 ⁺

Preparation Example 10
The outlet of the gas pump was connected to the inlet of a column containing 200 g of gXSC.Ni2 ⁺ . The outlet of the column was connected to the inlet of a gas phase containing ammonia gas volatilized from ammonia water at the top of a 20 L tank containing 7 L of 4 wt% ammonia water. The ammonia concentration in the gas phase measured with a gas detector was 32000 ppmv. The outlet of the gas phase at the top of the tank was connected to the inlet of the gas pump. That is, the ammonia gas at the top of the tank was allowed to circulate through the tank, gas pump, and column. The gas at the top of the tank was circulated overnight at a flow rate of about 0.5 L/min by the gas pump, and an ion exchanger XSC.Ni2 ⁺ _NH3 in which ammonia was adsorbed on gXSC.Ni2 ⁺ was obtained.

Preparation Example 11
Nickel (II) nitrate hexahydrate was dissolved in ultrapure water, and a 0.3 mol/L aqueous solution of nickel nitrate was prepared. 0.4 L was added to a 1 L capacity I-Boy, and 100 g of Amberlite CT200 Na, a strong acid cation exchange resin with a sulfo group (sulfonic acid group) as a functional group, was added. This was shaken at 180 rpm at room temperature for 71 hours in a shaking machine TS-20 manufactured by Taitec Co., Ltd., and adsorbed. After that, the solid-liquid separation was performed by suction filtration, and the mixture was washed three times with 0.4 L of ultrapure water, suction filtration, and then dried in a dryer at 60 ° C. for 17 hours to obtain 200 CT. Ni ²⁺ . The change in nickel ions in the liquid before and after adsorption was measured by MP-AES, and the amount of nickel ions exchanged, calculated by dividing the amount of nickel ions in the liquid by the mass of the ion exchange resin, was 0.68 mmol/g.

Preparation Example 12
Tin (IV) chloride pentahydrate was dissolved in ultrapure water to prepare a 0.4 mol/L tin chloride aqueous solution, and 0.08 L of the solution was placed in a 1 L I-Boy, and 100 g of Amberlite CT200 Na, a strong acid cation exchange resin with sulfo groups as functional groups, was added. This was shaken at 180 rpm at room temperature for 71 hours in a shaking machine TS-20 manufactured by Taitec Co., Ltd., and adsorbed. After that, the solid-liquid separation was performed by suction filtration, followed by washing with ultrapure water and suction filtration, and then drying in a dryer at 60 ° C for 17 hours to obtain 200 CT. Sn ⁴⁺ .

Example 1
2 g of urea was dissolved in 98 g of ultrapure water to obtain 2 wt% urea water. 4 mL of this urea water and 0.4 g of each of the ion exchangers prepared in Preparation Example 1 were placed in a 15 mL centrifuge tube and shaken overnight at a rotation speed of 900 rpm to allow urea to be adsorbed onto the ion exchanger. Then, the tube was centrifuged at a rotation speed of 3000 rpm for 5 minutes, and the urea concentration in the supernatant was evaluated by HPLC. The amount of urea in the urea water before and after adsorption of urea onto the ion exchanger was divided by the mass of the ion exchanger to calculate the urea adsorption amount (mmol/g).

The results are shown in Figure 1. Figure 1 shows the relationship between the ion exchanger and the amount of urea adsorption. As shown in Figure 1, the urea adsorption amount of ion exchangers containing metal ions with high valences, such as Fe3 ⁺ , Ti3 ⁺ , Zr4 ⁺ , Ru3 ⁺ , and Hf4 ⁺ , tended to be large. Also, among the ion exchangers containing alkali metal ions, the urea adsorption amount of the ion exchanger containing Cs ⁺ was the largest.

Example 2
In order to investigate whether the urea adsorption amount differs depending on the ion exchange resin (XSC-1614-Na, FPC3500, Amberlite irc-76, Amberlite ir-120, Amberlyst 15, ReliteWK60L, and ReliteWK100) used in the ion exchangers exchanged with the same metal ions in Preparation Examples 1 to 7, the urea adsorption amounts of various ion exchangers containing Ni ²⁺ , Fe ³⁺ , Cr ³⁺ , Mn ²⁺ , Al ³⁺ , or Ti ³⁺ were calculated in the same manner as in Example 1.

The results are shown in Figure 2. Figure 2 shows the relationship between the ion exchanger and the amount of urea adsorption. As shown in Figure 2, the urea adsorption amount of ion exchangers using strong acid ion exchange resins (XSC-1614-Na, Amberlite ir-120, and Amberlyst 15) was greater than the urea adsorption amount of ion exchangers using weak acid ion exchange resins (FPC3500, Amberlite irc-76, ReliteWK60L, and ReliteWK100).

The reason why the amount of urea adsorbed by the ion exchanger using a weakly acidic ion exchange resin was low is thought to be because urea is difficult to adsorb to the carboxyl groups coordinated with metal ions in the weakly acidic ion exchange resin. In contrast, the amount of urea adsorbed by the ion exchanger using a strongly acidic ion exchange resin was high is thought to be because the sulfonic acid groups contained in the strongly acidic ion exchange resin have a weak ability to coordinate metal ions, and urea is preferentially adsorbed to the sulfonic acid groups rather than metal ions. These results make it clear that ion exchangers using ion exchange resins that use strongly acidic groups such as sulfonic acid groups as ion exchangers are effective as molecular adsorbents that adsorb polar molecules such as urea.

Example 3
The XSC.Ti ⁴⁺ prepared in Preparation Example 8 was packed into a column, and 2 wt% urea water was continued to flow through the column until the concentration of the urea water coming out of the column reached 2 wt%, allowing urea to be adsorbed onto the XSC.Ti ⁴⁺ . 2 g of the XSC.Ti ⁴⁺ with urea adsorbed thereon was placed in a glass tube and heated at a temperature of 150° C. for 19 hours. When the FTIR spectra of XSC.Ti ⁴⁺ before and after heating were compared, a urea peak was confirmed before heating, but the urea peak disappeared after heating, confirming that urea had been desorbed.

Example 4
In the same manner as in Example 3, XSC.Ti4 ⁺ with urea adsorbed thereon was obtained in the column. Ultrapure water at a temperature of 80°C was passed through the column while the temperature inside the column was kept at 80°C. The urea concentration of the aqueous solution coming out of the column was a maximum of 9.2 wt%. In other words, it was confirmed that the urea adsorbed XSC.Ti4 ⁺ could be desorbed and concentrated by heating the urea.

Example 5
270g of ultrapure water was added to 10g of 28wt% ammonia water to prepare 1wt% ammonia water. 3mL of this ammonia water and 0.1g of the ion exchanger or ion exchange resin XSC.Na ⁺ prepared in Preparation Example 1 were placed in a 15mL centrifuge tube, and the tube was shaken overnight at a rotation speed of 900 rpm to adsorb ammonia to the ion exchanger or ion exchange resin. Then, the tube was centrifuged at a rotation speed of 3000 rpm for 5 minutes to collect the supernatant. 50μL of this supernatant was mixed with 4950μL of 5g/L boric acid aqueous solution to neutralize the ammonia. The ammonium ion concentration in this mixture was evaluated by ion chromatography.

The ammonia concentration in the supernatant was calculated assuming that the obtained ammonium ion concentration was equivalent to the ammonia concentration. The amount of ammonia adsorption (mmol/g) was calculated by dividing the amount of ammonia change in the ammonia water before and after adsorption of ammonia onto the ion exchanger or ion exchange resin by the mass of the ion exchanger or ion exchange resin. The results are shown in Figure 3. Figure 3 shows the relationship between the ion exchanger or ion exchange resin and the amount of ammonia adsorption.

As shown in Figure 3, the amount of ammonia adsorption of the ion exchanger in which the Na ions of the ion exchange resin XSC.Na ⁺ were ion-exchanged with other metal ions was greater than the amount of ammonia adsorption of the ion exchange resin XSC.Na ⁺ . In addition, the color of the ion exchanger changed before and after ammonia adsorption in the cases of XSC.Co2 ⁺ , XSC.Ni2 ⁺ , XSC.Cu2 ⁺ , XSC.Fe3 ⁺ , and XSC.Mn2 ⁺ .

That is, gXSC.Co2 ⁺ changed from reddish brown to blackish brown, gXSC.Ni2 ⁺ changed from yellowish green to blue, gXSC.Cu2 ⁺ changed from green to blue purple, gXSC.Fe3 ⁺ changed from reddish brown to blackish brown, and gXSC.Mn2 ⁺ changed from orange to blackish brown. It is considered that the color change occurred due to ammonia being coordinated to the metal ions of the ion exchanger. From this result, these ion exchangers can be used as molecular ammonia indicators that show the presence of ammonia in a liquid by color change. As mentioned above, it is considered that these ion exchangers change color when general amines having amino group moieties are adsorbed in addition to ammonia.

Example 6
A beaker containing 500 mL of 2 wt% ammonia water was prepared. Eight petri dishes containing 5 g each of ion exchangers of gXSC.Ag ⁺ , gXSC.Cr3 ⁺ , gXSC.Mn2 ⁺ , gXSC.Fe3 ⁺ , ^gXSC.Co2 +, gXSC.Ni2 ⁺ , gXSC.Cu2 ⁺ , and gXSC.Zn2 ⁺ were prepared. The beaker and the petri dishes were placed in a desiccator with a capacity of about 10 L and left at room temperature for 46.5 hours to allow ammonia gas to be adsorbed by the ion exchanger. The ammonia gas concentration in the desiccator at the end was 12,000 ppmv.

As in the case of ammonia adsorption in aqueous ammonia in Example 5, some ion exchangers changed color before and after ammonia gas adsorption. That is, gXSC.Co ²⁺ changed from reddish brown to blackish brown, gXSC.Ni ²⁺ changed from yellowish green to blue, gXSC.Cu ²⁺ changed from green to blue-purple, gXSC.Fe ³⁺ changed from reddish brown to blackish brown, and gXSC.Mn ²⁺ changed from orange to blackish brown. These ion exchangers can be used as molecular ammonia indicators that show the presence of ammonia in gas by color change.

0.1 g of these ion exchangers with adsorbed ammonia gas was placed in 5 mL of 30 mmol/L sodium hydrogen sulfate aqueous solution and shaken overnight at 25° C. and 400 rpm to desorb ammonia with acid. Then, solid-liquid separation was performed by suction filtration, and the ammonia concentration in the obtained liquid was evaluated by ion chromatography to calculate the amount of ammonia desorbed from the ion exchanger. The results are shown in FIG. 4. This amount of ammonia desorbed corresponds to the amount of ammonia adsorbed from the gas phase. As shown in FIG. 4, gXSC.Ni ²⁺ , gXSC.Cu ²⁺ , and gXSC.Zn ²⁺ had high ammonia adsorption performance.

Example 7
8 g of gXSC.Ni2 ⁺ _NH3 was placed in a stainless steel column, the inlet was closed, and the column was heated to a temperature of 140°C. The gas discharged from the outlet was condensed in a stainless steel tube cooled with ice water, and then collected in a gas bag. The ammonia concentration of the liquid in the gas bag was 12.1 wt%. It was found that ammonia adsorbed on the ion exchanger could be recovered at a high concentration by heating.

Example 8
8 g of gXSC.Ni2 ⁺ _NH3 was placed in a stainless steel column, and while the stainless steel column was kept at a temperature of 140°C, a liquid pump was used to heat ultrapure water to a temperature of 140°C and introduce the steam obtained from the inlet at 0.5 mL/min. The gas discharged from the outlet was condensed in a stainless steel tube cooled with ice water and recovered as an aqueous ammonia solution. The ammonia concentration of the recovered aqueous ammonia solution was a maximum of 22.1 wt%. It was found that the ammonia adsorbed on the ion exchanger could be recovered at a high concentration by heating and introducing steam.

Example 9
In order to confirm the change in the amount of ammonia desorbed when the adsorption and desorption of ammonia were repeated, the following ammonia adsorption/desorption cycle test was carried out.
First, as an adsorption test, 20 g of an ion exchanger (200CT.Ni ²⁺ obtained in Preparation Example 11) in which Na ⁺ of a strongly acidic ion exchange resin (Amberlite 200CT Na) having sulfonic acid groups was exchanged for Ni ²⁺ was placed in a stainless steel column, the port of the column was connected to the inlet of a diaphragm pump, the outlet of the diaphragm pump was connected to one of two ports in the upper air part of a 20 L tank containing 7 L of ammonia water with a concentration of 3 wt%, and the other port was connected to the inlet of the column. In this state, the diaphragm pump was operated for 16.5 hours, a mixed gas of water vapor with a concentration of 24000 ppmv and 2 vol% ammonia was passed through the column, and ammonia was adsorbed on the ion exchanger 200CT.Ni ²⁺ .

Further, as a desorption test, the piping was replaced, and the ultrapure water and the column containing 200 CT. Ni ²⁺ were heated to 140°C with a mantle heater, and the ultrapure water was pumped into the column at 0.1 mL/min with a plunger pump. The liquid leaving the column was cooled with a stainless steel tube immersed in ice water and trapped with boric acid. The concentration of the desorbed ammonia water was calculated by dividing the change in ammonia ion concentration in boric acid by the increased weight.

After cooling the column with air, the piping was replaced and the above-mentioned adsorption and desorption tests were repeated a total of 30 times to evaluate the cumulative (total) amount of ammonia desorbed per gram of adsorbent and the maximum ammonia concentration in the ammonia water obtained after desorption.

FIG. 5 is a graph showing the change in the amount of ammonia desorbed when ammonia adsorption and desorption are repeated on a strongly acidic ion exchanger containing Ni ²⁺ .
As shown in Fig. 5, the maximum ammonia concentration in the ammonia water was about 20 wt%, and the cumulative ammonia amount was generally 3 mmol/g or more. This result makes it clear that the ammonia adsorbent using the strongly acidic ion exchanger can be used repeatedly.

Example 10
In this example, in order to confirm the change in the amount of urea desorbed when the adsorption and desorption of urea were repeated, the following urea adsorption/desorption cycle test was carried out.
First, for the adsorption test, 1 g of ion exchanger XSC.Ti4 ⁺ (Na ⁺ of a strongly acidic ion exchange resin having sulfonic acid groups was exchanged for Ti4 ⁺ ) was packed into a stainless steel column, and 2 wt% urea water was passed through the column at room temperature at 0.5 mL/min.
Next, the urea concentration of the liquid coming out of the column was evaluated by HPLC, and the amount of adsorption was calculated by dividing the product of the liquid volume and the concentration change by the mass of the adsorbent (ion exchanger). As a desorption test after adsorption, the column was heated to 80°C, ultrapure water heated to 80°C was pumped into the column by a plunger pump, and the urea concentration of the liquid collected from the outlet was evaluated by HPLC, and the amount of desorption was calculated by dividing the product of the liquid volume and the concentration change by the mass of the adsorbent. This adsorption/desorption test was repeated 30 times.

FIG. 6 is a graph showing the change in the amount of urea desorbed when urea adsorption and desorption are repeated on a strongly acidic ion exchanger containing Ti ⁴⁺ .
Fig. 7 is a graph showing the cumulative amount of urea adsorbed and desorbed by a Ti4 ⁺ -containing strongly acidic ion exchanger after 30 cycles of urea adsorption and desorption, and Fig. 8 is a graph showing the cumulative amount of urea desorbed by a Ti4 ⁺ -containing strongly acidic ion exchanger after 30 cycles of urea adsorption and desorption.

As shown in Figure 6, the amount of urea desorbed was constant at approximately 40 mg/g, regardless of the number of cycles. In addition, as shown in Figures 7 and 8, even after 30 cycles of urea adsorption and desorption, no decrease in the amount of urea adsorbed or desorbed was observed. These results demonstrate that the urea adsorbent using a strongly acidic ion exchanger containing metal ions can be used repeatedly.

Example 11
In this example, in order to adsorb urea, 0.5 g of an ion exchanger (200CT.Sn ⁴⁺ obtained in Preparation Example 12) in which Na ⁺ of a strongly acidic ion exchange resin (Amberlite 200CT Na) having sulfonic acid groups was exchanged for Sn ⁴⁺ was placed in a 15 mL centrifuge tube together with 5 mL of 10 wt % urea water and shaken at 900 rpm for 5 hours. After shaking, the solid-liquid separation was performed using a paper filter, washed with ultrapure water, and the adsorbent (200CT.Sn ⁴⁺ ) was dried at 60 ° C for 17 hours or more. The adsorption amount was calculated by dividing the product of the liquid volume and the concentration change by the mass of the adsorbent, and the urea adsorption amount was 126 mg / g.

Figure 9 is a schematic diagram showing how urea is recovered from an adsorbent made of a strongly acidic ion exchanger containing metal ions. Figure 10 is an image showing a glass container in which solid urea has been recovered.

1 g of the above adsorbent with urea adsorbed was placed in the tall glass container shown in Figure 10, and vacuum was applied from above at 100°C for 43.5 hours, resulting in the generation of 2 mg of a white solid on the glass surface. When this solid was dissolved in water and measured by HPLC, a peak was confirmed at the position corresponding to urea. This made it clear that solid urea could be recovered using this method.

Example 12
In this embodiment, in order to adsorb trimethylamine, 0.1 g of XSC.Co ²⁺ , XSC.Ni ²⁺ , XSC.Cu ²⁺ , XSC.Mn ²⁺ , XSC.Fe ³⁺ , or XSC.Na ⁺ ion exchanger was placed in a 15 mL centrifuge tube together with 0.4 mL of 12 wt% trimethylamine aqueous solution and left to stand for 24 hours. After that, the supernatant aqueous solution was collected, and the concentration of the trimethylamine aqueous solution in the supernatant was measured from the intensity change of the trimethylamine spectrum of FTIR, and the adsorption amount was calculated by dividing the product of the liquid volume and the concentration change by the mass of the adsorbent.

11 is a graph showing the amount of trimethylamine adsorbed in the aqueous solution of Example 12. As shown in FIG. 11, XSC.Co ²⁺ , XSC.Ni ²⁺ , XSC.Cu ²⁺ , XSC.Mn ²⁺ and XSC.Fe ³⁺ showed higher adsorption amounts than XSC.Na ⁺ (FIG. 11). In XSC.Co ²⁺ , XSC.Ni ²⁺ , XSC.Cu ²⁺ and XSC.Fe ³⁺ , the color of the ion exchanger changed before and after trimethylamine adsorption. That is, XSC.Co ²⁺ changed from reddish brown to blackish brown, gXSC.Ni ²⁺ changed from yellowish green to green, gXSC.Cu ²⁺ changed from green to blue purple, and gXSC.Fe ³⁺ changed from reddish brown to blackish brown. The color change is believed to be due to coordination of ammonia with the metal ions of the ion exchanger. These results demonstrate that these ion exchangers can be used as trimethylamine indicators that show the presence of trimethylamine in liquids by a color change.

Example 13
In this example, in order to adsorb butylamine, 0.1 g of XSC.Co ²⁺ , XSC.Ni ²⁺ , XSC.Cu ²⁺ , XSC.Mn ²⁺ , XSC.Fe ³⁺ or XSC.Na ⁺ ion exchanger was placed in a 15 mL centrifuge tube together with 0.4 mL of 15 wt% butylamine aqueous solution and left to stand for 24 hours. After that, the supernatant aqueous solution was collected, and the concentration of the butylamine aqueous solution in the supernatant was measured from the intensity change of the butylamine spectrum of FTIR, and the adsorption amount was calculated by dividing the product of the liquid volume and the concentration change by the mass of the adsorbent.

Figure 12 is a graph showing the amount of butylamine adsorbed in the aqueous solution of Example 13. As shown in Figure 12, XSC.Co ²⁺ , XSC.Ni ²⁺ , XSC.Cu ²⁺ , XSC.Mn ²⁺ and XSC.Fe ³⁺ showed higher adsorption amounts than XSC.Na ⁺ . The color of the ion exchanger changed before and after butylamine adsorption in XSC.Co ²⁺ , XSC.Ni ²⁺ , XSC.Cu ²⁺ and XSC.Fe ³⁺ . That is, XSC.Co ²⁺ changed from reddish brown to blackish brown, XSC.Ni ²⁺ changed from yellowish green to green, XSC.Cu ²⁺ changed from green to blue purple, and XSC.Fe ³⁺ and XSC.Mn ²⁺ changed from reddish brown to blackish brown. The color change is believed to be due to coordination of butylamine with the metal ions of the ion exchanger. These results demonstrate that these ion exchangers can be used as butylamine indicators that show the presence of butylamine in liquids by a color change.

Example 14
A glass petri dish was prepared in which 2 mL of 12 wt% trimethylamine water and about 0.01 g of gXSC.Co ²⁺ , XSC.Ni ²⁺ , gXSC.Cu ²⁺ , gXSC.Mn ²⁺ or gXSC.Fe ³⁺ ion exchanger were placed in a PP dish so that the ion exchanger and trimethylamine water did not come into contact with each other. The glass petri dish was left at room temperature for 20 hours, and the vaporized trimethylamine gas was adsorbed by each ion exchanger. As with the adsorption of trimethylamine in water in Example 12, some ion exchangers changed color before and after adsorption of trimethylamine gas. That is, gXSC.Co ²⁺ changed from reddish brown to blackish brown, gXSC.Ni ²⁺ changed from yellowish green to green, gXSC.Cu ²⁺ changed from green to blue, gXSC.Fe ³⁺ changed from reddish brown to blackish brown, and gXSC. The color of ^Mn changed from orange to dark brown, respectively. This result demonstrated that these ion exchangers can be used as trimethylamine indicators that show the presence of trimethylamine in gas by a color change.

Example 15
A glass petri dish was prepared in which 2 mL of 15 wt% butylamine water and about 0.01 g of gXSC.Co ²⁺ , XSC.Ni ²⁺ , gXSC.Cu ²⁺ , gXSC.Mn ²⁺ or gXSC.Fe ³⁺ ion exchanger were placed in a PP dish so that the ion exchanger and the butylamine water did not come into contact with each other. The glass petri dish was left at room temperature for 20 hours, and the vaporized butylamine gas was adsorbed by each ion exchanger. As with the butylamine adsorption in water in Example 13, some ion exchangers changed color before and after butylamine gas adsorption. That is, gXSC.Co ²⁺ changed from reddish brown to blackish brown, gXSC.Ni ²⁺ changed from yellowish green to green, gXSC.Cu ²⁺ changed from green to blue, gXSC.Fe ³⁺ changed from reddish brown to blackish brown, and gXSC. The color of ^Mn changed from orange to dark brown, respectively. This result demonstrated that these ion exchangers can be used as butylamine indicators that show the presence of butylamine in gas by a color change.

Claims (15)

A molecular adsorbent for adsorbing polar molecules, comprising an ion exchanger as an active ingredient, the ion exchanger comprising an ion exchange resin having an ion exchange group which is a strongly acidic group, and a metal ion or a complex of the metal ion which has been ion-exchanged by the ion exchange group,
The polar molecule contains a nitrogen atom having an unshared electron pair,
The molecular adsorbent, wherein the metal ion is one or more of a trivalent or higher metal ion, Co2 ⁺ , Cu2 ⁺ , Ni2 ⁺ , Mn2 ⁺ , V2 ⁺ , Cs ⁺ , Rb ⁺ , and K ⁺ . In claim 1,
The molecular adsorbent, wherein the trivalent or higher metal ion is one or more of Fe3 ⁺ , Cr3 ⁺ , Al3 ⁺ , Ti3 ⁺ , In3 ⁺ , Ru3 ⁺ , Ti4 ⁺ , Zr4 ⁺ , Sn4 ⁺ and Hf4 ⁺ . In claim 1,
The molecular adsorbent, wherein the polar molecule is at least one of ammonia, amines, and ureas. In claim 3,
the polar molecule is urea;
A molecular adsorbent, wherein the metal ion is one or more of Fe3 ⁺ , Ti3 ⁺ , Ru3 ⁺ , Zr4 ⁺ , Hf4 ⁺ , Sn4 ⁺ and Cs ⁺ . In claim 3,
the polar molecule is ammonia,
A molecular adsorbent, wherein the metal ion is at least one of Ni ²⁺ and Cu ²⁺ . In claim 3,
the polar molecule is at least one of trimethylamine and butylamine,
The molecular adsorbent, wherein the metal ion is one or more selected from the group consisting of Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Mn ²⁺ and Fe ³⁺ . An indicator for ammonia and amines, comprising an ion exchanger containing an ion exchange resin having an ion exchange group which is a strongly acidic group, and a metal ion or a complex of the metal ion which has been ion-exchanged at the ion exchange group, and determining adsorption of at least one of ammonia and an amine to the ion exchanger by a color change,
An indicator wherein the metal ion is Co2 ⁺ , Ni2 ⁺ , Cu2 ⁺ , Fe3 ⁺ , or Mn2 ⁺ . In claim 7,
An indicator that determines the adsorption of ammonia by a color change. The indicator according to claim 7, wherein the amine is at least one of trimethylamine and butylamine. an adsorption step of contacting a gas or liquid containing polar molecules containing a nitrogen atom having an unshared electron pair with an ion exchanger having an ion exchange resin having ion exchange groups which are strong acidic groups and a trivalent or higher metal ion, one or more of Co2 ⁺ , Cu2 ⁺ , Ni2 ⁺ , ^{Mn2+ ,} V2 ⁺ , Zn2+, Cs ⁺ , Rb ⁺ , and K ⁺ or a complex thereof, which has been ion-exchanged with the ion exchange groups, to adsorb the polar molecules;
a condensation step of heating the ion exchanger to which the polar molecules are adsorbed and condensing the gas generated from the ion exchanger;
A method for concentrating polar molecules comprising: In claim 10,
The method for concentrating polar molecules, wherein the condensation step comprises heating the ion exchanger to a temperature of 60° C. or higher and lower than the heat resistance temperature of the ion exchanger. In claim 10 or 11,
The method for concentrating polar molecules comprises heating the ion exchanger while contacting it with water vapor in the condensation step. In claim 10 or 11,
the trivalent or higher metal ion is one or more of Fe ³⁺ , Cr ³⁺ , Al ³⁺ , Ti ³⁺ , In ³⁺ , Ru ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , Sn ⁴⁺ and Hf ⁴⁺ ;
The method for concentrating polar molecules, wherein the polar molecule is at least one of ammonia and urea. In claim 12,
the trivalent or higher metal ion is one or more of Fe ³⁺ , Cr ³⁺ , Al ³⁺ , Ti ³⁺ , In ³⁺ , Ru ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , Sn ⁴⁺ and Hf ⁴⁺ ;
The method for concentrating polar molecules, wherein the polar molecule is at least one of ammonia and urea. A method for recovering polar molecules concentrated by the method for concentrating polar molecules according to claim 10 or 11, comprising:
the polar molecule is urea;
The recovery method includes a step of heating a container containing the ion exchanger having urea adsorbed thereon and applying negative pressure to an upper portion of the container to cause suction, thereby precipitating solid urea.

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