Method for treating a metal-containing liquid and method for producing an organic solvent

Abstract

To provide a metal-containing liquid processing method and an organic solvent manufacturing method which can adsorb and remove metal ions contained in an organic solvent.SOLUTION: In the metal-containing liquid processing method, liquid to be processed containing metal ions is broight into contact with H-type magadiite in the presence of an organic solvent, and the metal ions are made to be adsorbed onto the H-type magadiite, so as to obtain the processed liquid in which at least some of the metal ions are removed from the liquid to be processed. In the organic solvent manufacturing method, the processed liquid containing the organic solvent is obtained by the processing method, and the processed liquid is separated from the H-type magadiite contacting the processed liquid, so as to obtain the organic solvent in which the content of the metal ions are reduced.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for treating a metal-containing liquid and a method for producing an organic solvent.

Background Art

[0002] A metal ion adsorbent for adsorbing metal ions contained in an aqueous solution and a method for producing the same are disclosed in Patent Document 1. This metal ion adsorbent is obtained by siloxane-bonding a silane compound having a functional group capable of adsorbing metal ions to the surface of silica hollow particles encapsulating magnetic particles.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, cation-exchangeable clay minerals are cited as practical materials for adsorbing metal ions in an aqueous solution, and it is said that the metal ion adsorbent of Patent Document 1 is easier to recover from an aqueous solution than such clay minerals. On the other hand, inorganic substances having a layer structure such as clay minerals and layered polysilicates (layered silicates) are produced naturally and a simple synthesis method has been established, so the attractiveness as a material for an easily available metal adsorbent remains great.

[0005] By the way, the application of clay minerals and layered polysilicates as metal adsorbents has been exclusively carried out for metal ions contained in an aqueous solution. The present inventors have earnestly studied and considered that removing metal ions contained in an organic solvent will greatly contribute to future industries. As a result, it was found that the H-type magadiite obtained by acid-treating the layered silicate has an increased layer structure thickness, that is, the internal space of the channel structure within the layer expands, in the presence of an organic solvent. Further investigation revealed that metal ions can be adsorbed into the expanded channel structure, thus completing the present invention.

[0006] The present invention provides a method for treating a metal-containing liquid and a method for producing an organic solvent, which are capable of adsorbing and removing metal ions contained in the organic solvent.

Means for Solving the Problems

[0007] [1] A method for treating a metal-containing liquid, including bringing a liquid to be treated containing metal ions into contact with H-type magadiite in the presence of an organic solvent, and adsorbing the metal ions onto the H-type magadiite to obtain a treated liquid in which at least a part of the metal ions has been removed from the liquid to be treated (however, excluding the case where the organic solvent is PGMEA). [2] The method for treating a metal-containing liquid according to [1], wherein the H-type magadiite has a channel structure, and the metal ions are adsorbed into the channel structure. [3] The method for treating a metal-containing liquid according to [2], wherein the channel structure has an oxygen eight-membered ring skeleton. [4] By adding an acid to the liquid to be treated, maintaining the state where the interlayer of the H-type magadiite is closed, and preferentially adsorbing the metal ions to the channel structure, the method for treating a metal-containing liquid according to [2] or [3]. [5] The method for treating a metal-containing liquid according to any one of [1] to [4], wherein the metal ions include one or more ions selected from transition metals, alkali metals, and alkaline earth metals. [6] The method for treating a metal-containing liquid according to any one of [1] to [5], wherein the metal ions contained in the liquid to be treated form a complex. [7] The method for treating a metal-containing liquid according to [6], wherein the complex contains water molecules. [8] The method for treating a metal-containing liquid according to any one of [1] to [7], wherein the organic solvent is a polar organic solvent. [9] A method for producing an organic solvent, comprising obtaining the treated liquid containing the organic solvent by the treatment method according to any one of [1] to [8], and separating the treated liquid from the H-type magadiite that has come into contact with the treated liquid, thereby obtaining an organic solvent with a reduced metal ion content.

[0008] The following are aspects related to the present invention.

[10] A metal adsorbent composition comprising an organic solvent and H-type magadiite.

[11] A metal adsorbent comprising H-type magadiite and an organic compound contained in the channel structure of the H-type magadiite.

[12] A metal adsorption device comprising the metal adsorbent composition according to

[10] or the metal adsorbent according to

[11] housed in a treatment container.

[13] A composite comprising H-type magadiite and metal ions other than Na ions contained in the channel structure of the H-type magadiite.

[14] A method for producing a metal-containing material, comprising performing a treatment to remove the solvent compound from within the channel structure of a composite comprising H-type magadiite and metal ions other than Na ions and a solvent compound contained in the channel structure of the H-type magadiite, thereby changing the chemical state of the metal ions in the composite to obtain a metal-containing material. [The effects of the invention]

[0009] According to the method for treating a metal-containing liquid of the present invention, metal ions contained in the metal-containing liquid can be adsorbed onto H-type magadiite. According to the method for producing an organic solvent of the present invention, an organic solvent from which at least a part of the metal ions have been removed can be obtained. According to the metal adsorbent composition and the metal adsorbent related to the present invention, metal ions contained in a liquid or gas to be treated can be adsorbed. The complex related to the present invention can be used as a reaction field for reacting metal ions contained in the channel structure. However, since Na ions are the metal ions originally possessed by magadiite, they do not correspond to the metal ions possessed by the complex of the present invention. In the method for producing a metal-containing substance related to the present invention, by using H-type magadiite as a reaction field for metal ions, a metal-containing substance obtained by changing the chemical state of the metal ions can be obtained.

Brief Description of the Drawings

[0010]

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Mode for Carrying Out the Invention

[0011] ≪Method for Treating Metal-Containing Liquid≫ The first aspect of the present invention includes bringing a liquid to be treated containing metal ions into contact with H-type magadiite in the presence of an organic solvent, and adsorbing the metal ions onto the H-type magadiite, thereby obtaining a treated liquid in which at least a part of the metal ions has been removed from the liquid to be treated (however, excluding the case where the organic solvent is PGMEA).

[0012] The organic solvent is preferably contained in the channel structure of the H-type magadiite. When the organic solvent is contained in the channel structure of the H-type magadiite, the internal space of the channel structure expands, and a space in which metal ions are easily adsorbed is formed. In order for the organic solvent to stably exist in the channel structure of the H-type magadiite, it is preferable that the liquid to be treated sufficiently contains the organic solvent.

[0013] [Liquid to be Treated] The organic solvent contained in the liquid to be treated is not particularly limited, and an organic solvent that can increase the thickness of the layer of the contacted H-type magadiite is preferable. For example, a polar organic solvent is preferable. Examples of the polar organic solvent include aprotic solvents such as acetonitrile, acetone, ethyl acetate, chloroform, dichloromethane, diethyl ether, tetrahydrofuran, ethyl acetate, dimethyl sulfoxide, and dimethylformamide, and protic solvents such as isopropanol, ethanol, methanol, acetic acid, and propylene glycol 1-monomethyl ether (PGME). Among these organic solvents, aprotic solvents are preferable because it is easy to maintain the state where the interlayer of the H-type magadiite is closed, and it is easy to preferentially expand the channel structure.

[0014] The metal ions contained in the liquid to be treated may be one type or two or more types. The specific metal ions are not particularly limited. When classified by chemical properties, for example, alkali metals such as lithium, sodium, potassium, rubidium, cesium, etc.; alkaline earth metals such as calcium, strontium, barium, radium, etc.; magnesium group elements such as beryllium, magnesium, zinc, cadmium, mercury, etc.; aluminum group elements such as aluminum, gallium, indium, etc.; rare earth elements such as yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, etc.; tin group elements such as titanium, zirconium, tin, hafnium, lead, thorium, etc.; iron group elements such as iron, cobalt, nickel, etc.; tungstic acid group elements such as vanadium, niobium, tantalum, etc.; chromium group elements such as chromium, molybdenum, tungsten, uranium, etc.; manganese group elements such as manganese, rhenium, etc.; noble metals such as copper, silver, gold, etc.; platinum group elements such as ruthenium, rhodium, palladium, osmium, iridium, platinum, etc.; natural radioactive elements such as uranium, thorium, radium, radon, actinoid, etc.; transuranium elements such as neptunium, plutonium, americium, curium, berkelium, californium, etc.; and other ions can be mentioned.

[0015] In addition, as the metal ions contained in the liquid to be treated, one or more selected from transition metals (Groups 3 to 12 of the periodic table), alkali metals (Group 1 of the periodic table), and alkaline earth metals (Group 2 of the periodic table) can be mentioned.

[0016] The metal ions contained in the liquid to be treated may form a complex. The complex containing metal ions is preferably a neutral complex in which the positive charge of the metal ions is neutralized. The ligands other than the metal ions constituting the complex are not particularly limited, and may be organic substances, inorganic substances, water molecules, or molecules of other solvents. Further, the liquid to be treated may contain a counter ion (counter anion) of a metal ion. In this case, a counter anion may be present in the vicinity of the metal ion adsorbed on the H-type magadiite. That is, the counter anion may be adsorbed simultaneously with the metal ion.

[0017] The liquid to be treated may contain water. The water contained in the liquid to be treated may be water molecules constituting the complex or bulk water as a solvent. The water contained in the liquid to be treated is preferably miscible with the organic solvent contained in the same liquid to be treated. That is, when the organic solvent contained in the liquid to be treated is polar, it may contain water miscible with the organic solvent.

[0018] When the liquid to be treated contains water, the water content with respect to the total mass of the liquid to be treated is preferably, for example, 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, and particularly preferably 10% by mass or less. The lower limit may be 0% by mass. Within these preferred ranges, the labor for removing water molecules is reduced in the method for producing an organic solvent described later.

[0019] The H-type magadiite brought into contact with the liquid to be treated is one in which at least a part of the Na ions of magadiite (Na2Si 14 O 29 ·nH2O), which is a known layered polysilicate, are replaced with protons (H + ). Although it may be regarded as not being a salt strictly because the Na ions are replaced, in this specification, H-type magadiite may be referred to as a layered silicate, disregarding strictness.

[0020] Magadiite occurs naturally, and its hydrothermal synthesis method is also known. Examples of the hydrothermal synthesis method include a method in which an aqueous alkaline solution containing a silica material is placed in a heat-resistant and pressure-resistant container and treated at 140 to 160 °C for several days. Examples of the silica material include silica gel and colloidal silica. Examples of the alkali source include inorganic alkalis such as sodium hydroxide, sodium carbonate, and sodium hydrogen carbonate. Whether the crystal obtained by the hydrothermal synthesis method is magadiite can be confirmed by examining the XRD diffraction pattern.

[0021] The layer structure of magadiite is formed by stacking a plurality of unit layers. The unit layer is formed by stacking a plurality of sheets formed by two-dimensionally polymerizing SiO4 tetrahedrons. FIG. 1 is a schematic diagram showing an example of the layer structure in which the first layer and the second layer of magadiite (Na-Mag) are stacked (for convenience, the chemical bonds shown in the figure are not necessarily accurate). On the surface of each layer, there are silanol groups (≡Si-OH), Na ions as interlayer cations, and ionized oxygen (≡Si-O - ) that maintains electrical neutrality. Also, inside each layer, there is a channel structure composed of an oxygen eight-membered ring, and it is considered that water molecules are present inside.

[0022] H-type magadiite (H-Mag) can be obtained by subjecting magadiite to acid treatment by a known method. Its theoretical composition formula is considered to be H2Si 14 O 29 ·nH2O (n < 0.3). Examples of the acid used for the acid treatment include inorganic acids such as hydrochloric acid and nitric acid. As a specific acid treatment method, there is a method in which an acid is dropped into an aqueous solution in which magadiite is dispersed to perform ion exchange. By dropping the acid until the equivalent point, H-type magadiite close to the above theoretical composition formula can be obtained.

[0023] In the case of H-type magadiite, since the Na ions between the layers are replaced by protons, the surfaces of the respective layers approach each other due to hydrogen bonding by the silanol groups on the layer surface and van der Waals forces between the layers, and the space between the layers becomes closed. For this reason, since the interlayer distance is close to zero, the lattice plane spacing d(001) of the XRD diffraction of H-type magadiite is an approximate value of the thickness of the unit layer of magadiite.

[0024] When the present inventors measured the lattice plane spacing d(001) of H-type magadiite in a state of being in contact with an organic solvent, they found that it clearly increased as compared with the dry state. In the measurement results of XRD diffraction, since there was no state in which the organic solvent broke through the hydrogen bonding and van der Waals forces and entered between the unit layers, it was found that the thickness of the unit layer increased rather than the interlayer distance. It is reasonable to consider that the internal space of the channel structure swelled in order for the thickness of the unit layer to increase. That is, it was found that the organic solvent entered the channel structure and swelled its internal space.

[0025] By bringing a treatment target liquid containing an organic solvent into contact with H-type magadiite, the organic solvent flows into the channel structure within the layer of H-type magadiite. At this time, the metal ions contained in the treatment target liquid are accommodated in the channel structure together with the organic solvent, or a part or all of the organic solvent that has previously flowed into the channel structure is exchanged (substituted) and accommodated in the channel structure. An example of this state is shown in the schematic diagram of FIG. 2 (for convenience, the chemical bonds shown in the figure are not necessarily accurate). The example in the figure shows a state in which metal ions are adsorbed in the channel structure. In the channel structure, it is considered that the hydroxyl groups (OH - ) generated by the hydrolysis of the water hydrated to the metal ions neutralize the positive charge of the metal ions.

[0026] The method of bringing the treatment target liquid into contact with H-type magadiite is not particularly limited, and examples thereof include a method of adding the powder of H-type magadiite to the treatment target liquid and stirring it. The addition amount of H-type magadiite with respect to the total mass of the liquid to be treated is not particularly limited, and from the viewpoint of easy stirring, for example, it can be 1 to 10% by mass. Also, as another contact method, there is a method of flowing the liquid to be treated through a column filled with H-type magadiite. At this time, the liquid to be treated may be circulated and contacted with the column a plurality of times. The contact time between the liquid to be treated and H-type magadiite is not particularly limited, and for example, it may be appropriately adjusted within the range of several minutes to several tens of hours according to the adsorption amount of metal ions. The temperature at the time of contacting the liquid to be treated with H-type magadiite is not particularly limited, and for example, it may be adjusted within the range of 4°C to 40°C.

[0027] As shown in the examples described later, since the adsorption power of metal ions in H-type magadiite is very excellent, by passing the liquid to be treated only once through a layer composed of H-type magadiite with a thickness of 1 μm to 100 μm, it is possible to sufficiently adsorb the metal ions contained in the liquid to be treated.

[0028] The liquid to be treated may contain inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid. By making the liquid to be treated acidic, the interlayer of H-type magadiite can be surely closed as described above, so that metal ions can be preferentially adsorbed into the channel structure. From this viewpoint, when the liquid to be treated contains water, the pH of the liquid to be treated is preferably 4 or less, more preferably 3 or less, and even more preferably 2 or less. Note that, as described later, when H-type magadiite adsorbed with metal ions comes into contact with acidic water having a high acid concentration, the metal ions desorb from the channel structure of H-type magadiite due to the influence of the acid. From the viewpoint of preventing this desorption, the pH of the liquid to be treated containing water is preferably 1 or more.

[0029] By the above treatment method, a treated liquid can be obtained in which at least a part of the metal ions are removed by adsorbing them onto H-type magadiite from the metal-containing liquid as the liquid to be treated.

[0030] ≪Method for producing organic solvent≫ According to a second aspect of the present invention, by the treatment method of the first aspect, the treated liquid containing the organic solvent is obtained, and the organic solvent with a reduced metal ion content is obtained by separating the treated liquid from the H-type magadiite that has come into contact with the treated liquid. This is a method for producing an organic solvent.

[0031] When H-type magadiite is added to the liquid to be treated in the treatment method of the first aspect, the obtained treated liquid contains H-type magadiite adsorbed with metal ions. As a method for separating this H-type magadiite from the treated liquid, for example, known solid-liquid separation methods such as filtration, decantation, and centrifugation can be applied.

[0032] When the liquid to be treated is passed through a column filled with H-type magadiite in the treatment method of the first aspect, the treated liquid flowing out of the column is naturally separated from the H-type magadiite remaining in the column. That is, when the column method is adopted, the adsorption treatment of metal ions and the separation treatment of the treatment liquid and H-type magadiite can be continuously performed.

[0033] Alternatively, the liquid to be treated may be passed through an adsorption layer composed of H-type magadiite formed on a liquid permeable membrane such as filter paper or a polymer membrane. The thickness of the adsorption layer is, for example, 1 μm to 1000 μm, and may be 1 μm to 100 μm. Since the individual particle diameters of H-type magadiite are about 1 μm to 100 μm, when the particles of H-type magadiite are uniformly dispersed on the liquid permeable membrane so that they do not stack up, an adsorption layer of about 1 μm to 100 μm is formed. Specifically, an adsorption layer in which H-type magadiite is uniformly dispersed can be formed by filtering a dispersion liquid in which H-type magadiite is dispersed in a dispersion medium with a liquid permeable membrane.

[0034] When water is contained in the treated liquid, an organic solvent from which water has been removed can be obtained by a known distillation method. Also, even when the treated liquid contains a plurality of types of organic solvents, they can be separated by type by a known distillation method.

[0035] The H-type magadiite separated from the treated liquid of this embodiment is a complex containing metal ions in its channel structure. The metal ions adsorbed in the channel structure of the H-type magadiite can be desorbed by contacting with an acidic aqueous solution. That is, the adsorptive power of the H-type magadiite can be restored by acid treatment and reused. Examples of the acidic aqueous solution used for desorbing metal ions from the complex include aqueous inorganic acid solutions such as nitric acid, hydrochloric acid, and sulfuric acid. From the viewpoint of promoting the desorption of metal ions, the pH of the acidic aqueous solution is preferably less than 1. Further, the acid concentration of the aqueous inorganic acid solution is preferably 0.2N or more, more preferably 0.3N or more, and still more preferably 0.6N or more.

[0036] ≪Metal adsorbent composition≫ A third aspect related to the present invention is a metal adsorbent composition containing an organic solvent and H-type magadiite. In the metal adsorbent composition, the H-type magadiite is in contact with the organic solvent. In this state, as described above, the interlayer of the H-type magadiite is closed, and the channel structure into which the organic solvent has entered is in an expanded state. When metal ions come into contact with such a metal adsorbent composition, the metal ions are adsorbed into the channel structure of the H-type magadiite. Examples of the organic solvent constituting the metal adsorbent composition include those exemplified in the first aspect. Examples of the metal ions that can be adsorbed by the metal adsorbent composition include those exemplified in the first aspect. The mass ratio of the mass M1 of the organic solvent constituting the metal absorbent composition to the mass M2 of the H-type magadiite is not particularly limited, and for example, M1:M2 = 1:100 to 100:1 can be set. At least, it is preferable that the whole of the H-type magadiite constituting the metal adsorbent composition is in contact with each other to such an extent that it is wetted by the organic solvent. Examples of the method of using the metal adsorbent composition include, for example, a method of bringing the metal adsorbent composition into contact with the liquid to be treated, and a method of bringing a "liquid or gas containing metal ions" different from the above-described liquid to be treated into contact with the metal adsorbent composition. The above liquid may or may not contain an organic solvent. When the above liquid contains an organic solvent, it is preferable that the organic solvent is the same as the organic solvent contained in the metal adsorbent composition because it is easy to maintain the expansion of the channel structure of H-type magadiite.

[0037] ≪Metal Adsorbent≫ A fourth aspect related to the present invention is a metal adsorbent comprising H-type magadiite and an organic compound contained in the channel structure of the H-type magadiite. The difference between the metal adsorbent of this aspect and the metal adsorbent composition of the third aspect is that it does not necessarily contain an organic solvent composed of a bulk organic compound. That is, it is sufficient that an organic compound is contained in the channel structure of H-type magadiite, and there may or may not be an organic solvent containing this outside the H-type magadiite. When an organic compound is contained in the channel structure, the internal space of the channel structure is in an expanded state. H-type magadiite having such an expanded channel structure easily adsorbs metal ions as a metal adsorbent. Examples of the organic compound constituting the metal adsorbent include the organic compounds constituting the organic solvents exemplified in the first aspect. Examples of the metal ions that can be adsorbed by the metal adsorbent include those exemplified in the first aspect. Examples of the method of using the metal adsorbent include, for example, a method of bringing the metal adsorbent into contact with the liquid to be treated, and a method of bringing a "liquid or gas containing metal ions" different from the above-described liquid to be treated into contact with the metal adsorbent. The above liquid may or may not contain an organic solvent. When the above liquid contains an organic solvent, it is preferable that the organic compound constituting the organic solvent is the same as the organic compound contained in the metal adsorbent because it is easy to maintain the expansion of the channel structure of H-type magadiite.

[0038] ≪Metal Adsorption Device≫ A fifth aspect related to the present invention is a metal adsorption device including the metal adsorbent composition of the third aspect or a treatment container containing the metal adsorbent of the fourth aspect. The treatment container is not particularly limited as long as it can bring the metal adsorbent into contact with the liquid to be treated. Examples thereof include known treatment containers for handling liquids and gases such as columns and flasks. As an example of the device configuration, a metal adsorption device including a column, the metal adsorbent composition or the metal adsorbent filled in the column, an introduction pipe connected to the inlet of the column, a lead-out pipe connected to the outlet of the column, and a pump connected to the introduction pipe or the lead-out pipe can be mentioned. As a method of using such a metal adsorption device, for example, the following method can be mentioned. First, the liquid to be treated is caused to flow into the column from the introduction pipe by a pump, the metal adsorbent in the column is brought into contact with the liquid to be treated, and metal ions contained in the liquid to be treated are adsorbed onto the H-type magadiite of the metal adsorbent. Next, by discharging the treated liquid from the lead-out pipe connected to the column, a treated liquid with at least a part of the metal ions removed can be obtained.

[0039] ≪Composite≫ A sixth aspect related to the present invention is a composite including H-type magadiite and metal ions (excluding Na ions) contained in the channel structure of the H-type magadiite. The composite of this aspect can be obtained, for example, by adsorbing metal ions into the channel structure of H-type magadiite by the method for treating a metal-containing liquid of the first aspect. In the composite of this aspect, the channel structure of H-type magadiite may contain substances other than metal ions or may contain only metal ions. Examples of substances other than metal ions include organic compounds constituting the organic solvent, water molecules, etc. Substances other than metal ions contained in the channel structure may be ligands coordinated to the metal ions contained in the channel structure or may simply coexist without coordination. The number of metal ions contained in a single channel structure of H-type magadiite may be one or two or more. When a plurality of metal ions are contained in a single channel structure, those metal ions may be bonded to each other or may exist independently separated from each other. In the composite of this aspect, with respect to the total number of a plurality of channel structures of H-type magadiite, the number of channel structures containing metal ions is preferably 3% or more, more preferably 5% or more, and even more preferably 10% or more. The content of metal ions with respect to the total mass of the composite of this aspect is, for example, preferably 0.001% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, and most preferably 1% by mass or more. The type of metal ions contained in the composite of this aspect may be one type or two or more types.

[0040] ≪Method for producing metal-containing substance≫ The seventh aspect related to the present invention is a method for producing a metal-containing substance, which includes performing a treatment to remove the solvent compound from within the channel structure on a composite including H-type magadiite, metal ions other than Na ions contained in the channel structure of the H-type magadiite, and a solvent compound, so as to change the chemical state of the metal ions in the composite. The composite of this aspect is the same as the composite of the sixth aspect except that it is essential that the channel structure contains a solvent compound. Examples of the solvent compound include organic compounds constituting the organic solvent of the first aspect, water molecules, and compounds constituting other known solvents. Here, the solvent compound refers to a compound that is liquid under standard conditions of 1 atm and 25°C. The metal ion contained in the complex used in this embodiment may be one type or two or more types. The solvent compound contained in the complex used in this embodiment may be one type or two or more types. Examples of the treatment for removing the solvent compound contained in the channel structure include a drying treatment and a heat treatment. By drying or heating, the solvent compound can be desorbed from the channel structure.

[0041] As an example of this embodiment, the following embodiments can be cited. First, by heating a complex in which a metal aqua complex (for example, an iron aqua complex) is contained in the channel structure of H-type magadiite, water molecules that are ligands of the metal aqua complex are decomposed, and the metal component is left in the channel structure. Subsequently, when oxygen molecules in the air flow into the channel structure from which water molecules have desorbed, the oxygen molecules react with the metal ions to form a metal oxide (for example, iron oxide). As a result, a complex in which H-type magadiite contains a metal oxide is obtained.

[0042] As another example of this embodiment, the following embodiments can be cited. First, by heating a complex in which a metal aqua complex (for example, an iron aqua complex) is contained in the channel structure of H-type magadiite, water molecules that are ligands of the metal aqua complex are decomposed, and the metal component is left in the channel structure. At this time, when placed in an inert gas such as nitrogen gas, for example, air does not flow into the channel structure, and a metal body (for example, pure iron, an iron compound, etc.) in which the metal components in the channel structure are bonded to each other is formed. As a result, a complex in which H-type magadiite contains a metal body is obtained. In the above example, at a location where a plurality of channel structures are adjacent to each other, the metal bodies contained in the adjacent channel structures can be connected to each other beyond the range of the channel structure. As a result, it is also possible to form minute wires or clusters made of a metal body in H-type magadiite.

Example

[0043] <Preparation of H-type magadiite> Using a known method described in a non-patent document (Y. Asakura, et al., Bull. Chem. Soc. Jpn., 2015, 88, 1241-1249), 2 g of powdery Na-type magadiite was obtained. 2 g of Na-type magadiite was suspended in ion-exchanged water, 200 ml of 0.2 M hydrochloric acid was added dropwise, and after stirring for a while, 1.5 g of H-type magadiite was collected by filtration. The amount of hydrochloric acid added dropwise here was set to the amount at the equivalence point in acid-base titration (about 1.92 mmol / g), and from the chemical analysis value of Na ions in the filtrate, it was confirmed that Na ions in the interlayer of magadiite were almost completely exchanged by protons.

[0044] <Test Example 1; Change in the interplanar spacing of H-type magadiite> Using an X-ray diffractometer (manufactured by Rigaku Corporation), the change in the interplanar spacing of H-type magadiite in the presence of an organic solvent was confirmed as follows for the lattice plane spacing d(001). First, the lattice plane spacing d(001) of the dried powdery H-type magadiite was 1.2 nm. Next, a small amount of acetonitrile was added dropwise to the dried powdery H-type magadiite to moisten the whole powder with acetonitrile. The lattice plane spacing d(001) of this H-type magadiite was 1.32 nm. Subsequently, the H-type magadiite moistened with acetonitrile was placed in a dryer and dried at 120 °C for 3 hours to volatilize acetonitrile. The lattice plane spacing d(001) of this dried powdery H-type magadiite was 1.27 nm. Also, the H-type magadiite moistened with acetonitrile was naturally dried at room temperature (24 °C) for 48 hours to remove acetonitrile at least on the surface. The lattice plane spacing d(001) of this dried powdery H-type magadiite was 1.23 - 1.30 nm. These XRD measurement results are shown in the graph of Figure 3.

[0045] From the XRD measurement results, it was found that the lattice plane spacing d(001) of H-type magadiite increased to 1.32 nm in the presence of acetonitrile. This plane spacing is not the interlayer distance of H-type magadiite, but the thickness of a layer (unit layer) composed of multiple sheets of SiO4 tetrahedra as a unit. Normally, silanol groups exist on the layer surface of H-type magadiite, and these form hydrogen bonds with each other, closing (narrowing) the interlayer space. On the other hand, since the lattice plane spacing d(001) increases in the presence of acetonitrile, it is considered that acetonitrile molecules enter the channel structure (structure with an eight-membered oxygen ring) within the layer rather than the interlayer distance, and the internal space of the channel structure expands, thereby increasing the layer thickness.

[0046] <Test Example 2; Adsorption of Metal Ions in the Presence of Organic Solvents> First, hydrochloric acid was dropped as described above and dried to obtain dry powder of H-type magadiite. Next, 5 ml of acetonitrile was added to 0.5 ml of an iron nitrate aqueous solution with adjusted concentration as shown in the following table, and 1.5 ml of concentrated nitric acid was further added. It was confirmed that the pH of the liquid to be treated became less than 1. 0.1 g of the dry powder of H-type magadiite was added to this liquid to be treated, and after stirring at room temperature (about 24 °C) for 24 hours, it was filtered, and the obtained sample of H-type magadiite was divided into two equal parts. One sample A was dried at room temperature for 48 hours, and the other sample B was dried at room temperature for 2 hours and then placed in a dryer and dried at 120 °C for 3 hours.

[0047]

Table 1

[0048] In Table 1, the sample name "H1.5-Fe51" indicates that, as described above, it is a sample obtained by adding the dry powder of H-type magadiite treated with 1.5 ml of concentrated nitric acid to the liquid to be treated containing 51 mg of iron nitrate nonahydrate. The same applies to other sample names, and the number after Fe represents the mass of iron nitrate nonahydrate contained in the liquid to be treated.

[0049] [FT-IR Measurement] For the above-mentioned samples A and B, FT-IR measurement was carried out to examine the presence or absence of acetonitrile. The measurement results are shown in the graphs of FIGS. 4 and 5. In the FT-IR measurement results, no peak due to the stretching vibration of the acetonitrile group was observed in the range of 2100~2300 cm -1 . Therefore, it is considered that acetonitrile was completely removed from the samples by drying at room temperature and 120 °C.

[0050] [Observation of Color Tone] For the above-mentioned sample B, the change in color tone during the drying process was visually observed. The filtrate was basically light yellow, and the color intensity of the filtrate increased according to the iron nitrate concentration. However, the color tone of the dried powder of H-type magadiite immediately after fractionation was the original white color of H-type magadiite regardless of the filtrate concentration. The color tones of all the powders after fractionation and drying at room temperature for 2 hours were also the original white color of H-type magadiite. After that, the color tones of all the powders after high-temperature drying at 120 °C for 3 hours showed a slight increase in brownish color. The increase in brownish color suggests that iron oxide or iron clusters were formed due to the removal of water molecules of iron ions in the channel structure.

[0051] [X-ray Diffraction] For the above-mentioned samples A and B, an X-ray diffractometer (manufactured by Rigaku Corporation) was used to confirm the lattice plane spacing d(001). The measurement results are shown in FIGS. 6 and 7. As shown by the XRD measurement results, since the thickness (interplanar spacing) of the unit layer of H-type magadiite stirred in the treatment liquid containing iron ions has increased, it is considered that the iron ions contained in the treatment liquid were adsorbed into the channel structure of H-type magadiite. In the measurement results, the layer of sample A dried at room temperature is thicker. This is considered to be because the channel structure of sample A contains water molecules together with iron ions, while the water molecules in the channel structure of sample B were removed by high-temperature drying. It is unnatural to consider that the iron ions and water molecules contained in the channel structure of H-type magadiite exist independently of each other, and it is considered that an iron aqua complex [Fe(H2O)6] 3+ is formed.

[0052] [Nitrogen adsorption test] For the above sample B, using a gas adsorption measuring device (manufactured by MicrotracBEL), the specific surface area of the sample was calculated from the nitrogen gas adsorption amount. The measurement results are shown in Figure 8 and Table 2 below. It is considered that reaction products (iron oxide or iron clusters) derived from iron ions are adsorbed in the channel structure of the H-type magadiite of sample B. For this reason, the specific surface area of sample B is smaller than that of H-type magadiite (H-Mag) with no adsorption, which is 42.5 m 2 g -1 . The reason why the specific surface area of the sample (H1.5-Fe305) added to the iron nitrate solution with a relatively high iron ion concentration is larger than that of the samples (H1.5-Fe101.5, H1.5-Fe152.3) added to the iron nitrate solution with a relatively low iron ion concentration remains unclear.

[0053]

Table 2

[0054] [Test Example 3; Desorption of metal ions adsorbed on H-type magadiite> [ICP analysis] The sample A obtained in Test Example 2 was added to 30 ml of a 0.2 M nitric acid aqueous solution, stirred at room temperature for 24 hours, then allowed to stand at room temperature for 5 hours to precipitate H-type magadiite, a part of the supernatant was collected, and ICP analysis was performed. The precipitated H-type magadiite was collected by filtration, and its dry mass was measured. Assuming that all the iron ions adsorbed on 0.025 g of the precipitated H-type magadiite could be desorbed and recovered in the supernatant, the mass of the adsorbed iron ions can be obtained by the product of the ICP measurement value (ppm) and 30 ml of the 0.2 M nitric acid aqueous solution (unit: mg). The calculation results are shown in Table 3 below. In addition, in Test Example 2, when the amount of iron ions contained in each liquid to be treated added with H-type magadiite was assumed to be the theoretical maximum adsorption amount, the calculation results of the ratio (unit: %) of the actually adsorbed iron ions to the maximum adsorption amount are shown in Table 3 below.

[0055]

Table 3

[0056] Regarding the measurement of the above ICP analysis, the adsorption isotherm of [Fe(H2O)6] on H-type magadiite created by applying the Langmuir-type adsorption isotherm formula (Figure 9) and the Langmuir plot are shown in Figures 10 and 11. 3+ Here, the equilibrium concentration C and the adsorption amount of Fe per gram of H-type magadiite were calculated by the following Formula 1 and Formula 2, respectively. Here, the equilibrium concentration C and the adsorption amount of Fe per gram of H-type magadiite 3+ were calculated by the following Formula 1 and Formula 2, respectively.

[0057] <Formula 1> Equilibrium concentration C (mmol / L) = Number of moles of Fe(NO3)3·9H2O / Volume (L) of CH3CN + H2O + HNO3 <Formula 2> Adsorption amount of Fe per gram of H-type magadiite 3+ (mmol / g) = Adsorbed Fe 3+ (mmol) / [0.1 g × Mass of H-type magadiite used in ICP analysis 0.025 g / Mass (mg) of the sample of H-type magadiite adsorbed with iron ions]

[0058] From these results, it can be concluded that the adsorption of [Fe(H2O)6] on H-type magadiite reached saturation under the adsorption conditions of Test Example 2, and the amount was 0.35 mmol / g from the Langmuir-type adsorption isotherm formula. 3+ The amount was 0.35 mmol / g from the Langmuir-type adsorption isotherm formula.

[0059] [X-ray diffraction] The H-type magadiite precipitated in the above nitric acid aqueous solution was recovered by filtration, and X-ray diffraction measurement of the lattice plane spacing d(001) was performed on the powder sample dried at room temperature for 48 hours. The measurement results are shown in Fig. 12. As shown by the XRD measurement results, the lattice plane spacing d(001) of each sample decreased compared with 1.34 - 1.36 nm before being added to the nitric acid aqueous solution. From this result, it was also found that the iron ions contained in the channel structure were desorbed by the acid treatment. The reason why the lattice plane spacing d(001) of the sample (H1.5-Fe51) did not decrease even after the acid treatment remains unclear.

[0060] <Test Example 4; Change in the plane spacing of H-type magadiite> To 37 mg of H-type magadiite (H-mag) dried at room temperature in a desiccator, about 0.1 mL of isopropanol (IPA), propylene glycol 1-methyl ether (PGME), or propylene glycol 1-methyl ether 2-acetate (PGMEA) was dropped, and using a powder X-ray diffraction (XRD) apparatus, the change in the fundamental plane spacing of H-mag was measured in the same manner as in Test Example 1. Also, for comparison, the fundamental plane spacing of Na-type magadiite (Na-Mag) was measured. The diffraction patterns, which are these measurement results, are shown in Fig. 13. In the measurement results of Fig. 13, the fundamental plane spacing of H-mag before dropping the organic solvent was 1.20 nm, the fundamental plane spacing of the diffraction pattern (IPA H-mag) after dropping IPA increased to 1.52 nm, and the fundamental plane spacing of the diffraction pattern (PGME H-mag) after dropping PGME increased to 1.57 nm. On the other hand, the fundamental plane spacing of the diffraction pattern (PGMEA H-mag) after dropping PGMEA hardly changed. From the above, it was found that PGMEA exceptionally does not contribute to expanding the channel structure of H-mag.

[0061] <Test Example 5; Adsorption of silver ions> To 1.26 ml of an aqueous AgNO3 solution, 5.74 ml of IPA or PGME was added to obtain a solution adjusted to an Ag concentration of 18 mmol / L. To this, 0.10 g of H-Mag dried at room temperature in a desiccator was added, and the mixture was stirred at room temperature for 24 hours. Then, it was filtered to recover H-Mag, which was dried at room temperature for 48 hours to obtain a sample for measurement. Using a powder X-ray diffractometer, the basal plane spacing of the sample was measured. The results are shown in Fig. 14. The basal plane spacing of the diffraction pattern using IPA (H-Mag_IPA_Ag) increased to 1.38 nm, and the basal plane spacing of the diffraction pattern using PGME (H-Mag_PGME_Ag) increased to 1.40 nm. For comparison, the diffraction pattern of H-Mag in the dry state is also shown, and its basal plane spacing was 1.20 nm. Next, the FT-IR measurement results of the sample are shown in Fig. 15. In both the sample using IPA and the sample using PGME, the absorption band of the C-H stretching vibration derived from the solvent was not observed, and the presence of nitrate ions was not confirmed. From the above, it was found that the basal plane spacing increased due to the adsorption of silver ions within the channel structure of H-Mag. It was also found that the solvent (IPA, PGME) was not contained within the channel structure.

[0062] <Test Example 6; Adsorption of Iron Ions and Aluminum Ions> To Fe(NO3)3·9H2O and Al(NO3)3·9H2O, 7.0 ml of IPA or PGME was added respectively to obtain a solution adjusted so that the Fe concentration and the Al concentration were each 18 mmol / L. To this, 0.10 g of H-Mag dried at room temperature in a desiccator was added, and the mixture was stirred at room temperature for 24 hours. Then, it was filtered to recover H-Mag, which was dried at room temperature for 48 hours to obtain a sample for measurement. The basal plane spacing of the sample was measured using a powder X-ray diffractometer. The results are shown in Fig. 16. The basal plane spacing of the diffraction pattern (H-Mag_IPA_Fe) using IPA containing iron ions increased to 1.37 nm, and the basal plane spacing of the diffraction pattern (H-Mag_PGME_Fe) using PGME containing iron ions increased to 1.42 nm. The basal plane spacing of the diffraction pattern (H-Mag_IPA_Al) using IPA containing Al ions increased to 1.38 nm, and the basal plane spacing of the diffraction pattern (H-Mag_PGME_Al) using PGME containing Al ions increased to 1.44 nm. For comparison, the diffraction pattern of H-Mag in the dry state is also shown, and its basal plane spacing was 1.20 nm. Next, the FT-IR measurement results of the sample are shown in Fig. 17. In none of the above five samples was an absorption band of C-H stretching vibration derived from the solvent observed, nor was the presence of nitrate ions confirmed. From the above, it was found that the basal plane spacing increased due to the adsorption of iron ions or Al ions within the channel structure of H-Mag. It was also found that the solvent (IPA, PGME) was not contained within the channel structure.

[0063] Also, for each sample obtained in Test Example 6, a gas adsorption measuring device (manufactured by MicrotracBEL) was used to calculate the specific surface area of the sample from the nitrogen gas adsorption amount. The measurement results are shown in Fig. 18 and Table 4 below. In the results of Table 4, the BET specific surface area of the sample with no adsorption is the largest, and the BET specific surface area decreases in the order of the sample adsorbed with iron ions and the sample adsorbed with Al ions. The decrease in these specific surface areas indicates that each metal ion is adsorbed within the pores (channel structure) of the sample.

[0064]

Table 4

[0065] Also, the results of ICP analysis after desorbing metal ions from each sample obtained in Test Example 6 are shown in Table 5. The procedure for this ICP analysis is the same as in Test Example 3. In the results of Table 5, the adsorption amount is the number of moles of each metal ion adsorbed per 1 g of H-Mag. It was found that more Al ions were adsorbed than iron ions.

[0066]

Table 5

[0067] Furthermore, Fig. 19 shows the results of measuring the UV-Vis absorption spectrum of the sample adsorbed with iron obtained in Test Example 6. In the measurement results, the peak near 270 nm is considered to indicate the presence of [Fe(H2O) 6-x (OH) x (3―x)+ , where x is 1 or 2. Also, the peak at 400 nm or more is considered to indicate the presence of a Fe dimer or a Fe(III) cluster, that is, iron oxide.

[0068] Finally, for the sample adsorbed with Al obtained in Test Example 6 27 the results of measuring the Al MAS NMR are shown in Fig. 20. In the measurement results, the peak at 0 ppm indicates the presence of 6-coordinate Al, and the fact that this signal is broad is considered to indicate the presence of polycondensates such as Al13 oligomers.

[0069] From the above UV-Vis absorption spectrum and 27 the results of Al solid NMR, it is considered that the water dissolved in the liquid to be treated coordinates with the metal ions, and part of it is adsorbed as an aqua complex in the channels of H-Mag, and the rest is adsorbed on the surface of H-Mag (outside the channels) in a state where the aqua complexes are polycondensed. Also, it is speculated that the adsorption rate of the aqua complex is faster than the rate of the polycondensation reaction of the aqua complex.

[0070] <Test Example 7; Adsorption of Mixed Metal Ions> IPA or PGME was added to a commercially available ICP standard aqueous solution and diluted to the concentrations shown in Table 6 to prepare a liquid to be treated containing three metal ions (Fe, Al, Ag).​ As a first treatment method, pre-dried H-Mag was added to the liquid to be treated in the amounts shown in Table 6, stirred at room temperature for 2 hours, then H-Mag was removed by filtration, and the amount of each metal ion contained in the obtained treated liquid was quantified by ICP analysis. As a second treatment method, pre-dried H-Mag was dispersed in IPA, and this was passed through a membrane filter with a diameter of 25 mm and a pore size of 1 μm, thereby forming an adsorption layer (with a thickness of about 1 μm to 100 μm) composed of H-Mag on the membrane filter. The liquid to be treated was passed once through the membrane filter equipped with this adsorption layer, and the amount of each metal ion contained in the obtained treated liquid was quantified by ICP analysis. These results are also shown in Table 6. Note that the notation "~% or more" in the table means that the ion concentration contained in the treatment liquid is below the detection limit of the analytical instrument. The detection limits of iron ions and silver ions in this test example are 0.02 ppm, and the detection limit of Al ions is 0.01 ppm.

[0071]

Table 6

[0072] From the above results, the following was found. First, the removal rate of metal ions contained in IPA is higher than that of metal ions contained in PGME. Also, the removal rates of iron ions and Al ions are equivalent in IPA, and the removal rate of iron ions is higher in PGME. The removal rate of Al ions is higher than that of silver ions in both IPA and PGME. Also, it was found that by simply passing through a thin adsorption layer composed of H-Mag once, metal ions can be surely captured, and it shows excellent efficiency particularly in the removal of iron ions.

[0073] <Summary> From the above test results, at least the following is understood. 1. The thickness of the unit layer of H - type magadiite increases in the presence of an organic solvent. That is, the channel structure of H - type magadiite expands in the presence of an organic solvent. (Basis: Test Example 1, Test Example 4) 2. An organic solvent can enter the channel structure of H - type magadiite, and the organic solvent in the channel structure can be removed by subsequent drying. (Basis: Test Examples 1 - 2, Test Examples 5 - 6) 3. In the presence of an organic solvent, by bringing H - type magadiite into contact with a liquid to be treated containing metal ions, metal ions can be adsorbed into the channel structure of H - type magadiite. (Basis: Test Examples 2 - 3, Test Examples 5 - 7) 4. When metal ions are adsorbed onto H - type magadiite, the layer thickness (lattice plane spacing d(001)) increases due to the expansion of the channel structure. (Basis: Test Example 2, Test Examples 5 - 6) 5. It is considered that the iron ions adsorbed on H - type magadiite form iron - aco complexes. (Basis: Test Example 2, Test Example 6) 6. By heating H - type magadiite adsorbed with iron - aco complexes, water molecules in the channel structure can desorb, and the iron ions can become iron oxide or iron clusters. (Basis: Test Example 2, Test Example 6) 7. By bringing H - type magadiite adsorbed with metal ions into contact with an acidic aqueous solution, the metal ions can be eluted into the acidic aqueous solution. That is, the metal ions in the channel structure of H - type magadiite can be desorbed. (Basis: Test Example 3, Test Example 6)

Claims

1. In the presence of an organic solvent, bringing a liquid to be treated containing metal ions into contact with H-type magadiite, and adsorbing the metal ions onto the H-type magadiite, whereby a treated liquid in which at least a part of the metal ions has been removed from the liquid to be treated is obtained (except when the organic solvent is PGMEA), and the metal ions are iron ions, aluminum ions or silver ions, a method for treating a metal-containing liquid.

2. The H-type magadiite has a channel structure, and the metal ions are adsorbed into the channel structure, the method for treating a metal-containing liquid according to Claim 1.

3. The channel structure has an oxygen eight-membered ring skeleton, the method for treating a metal-containing liquid according to Claim 2.

4. By adding an acid to the liquid to be treated, the interlayer of the H-type magadiite is maintained in a closed state, and the metal ions are preferentially adsorbed onto the channel structure, the method for treating a metal-containing liquid according to Claim 2 or 3.

5. The metal ions contained in the liquid to be treated form a complex, the method for treating a metal-containing liquid according to any one of Claims 1 to 4.

6. The complex contains water molecules, the method for treating a metal-containing liquid according to Claim 5.

7. The organic solvent is a polar organic solvent, the method for treating a metal-containing liquid according to any one of Claims 1 to 6.

8. By the treatment method according to any one of Claims 1 to 7, obtaining the treated liquid containing the organic solvent, and separating the treated liquid from the H-type magadiite that has come into contact with the treated liquid, obtaining an organic solvent with a reduced metal ion content, a method for producing an organic solvent.

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