Porous material and method for recovering an object substance using the same

Abstract

To achieve the object, provided is a porous material including: a porous body having a co-continuous structure formed of a ceramic skeleton (1) including a mesopore (3) and a macropore (2); and a sulfonic group that modifies a surface of the ceramic skeleton (1), the amount of the sulfonic group included in the porous material being 0.7 mmol / g or more and 5.0 mmol / g or less.

Description

[0001] Technical Scope

[0002] This invention relates to porous materials and methods for recycling object materials using the porous materials. Background Technology

[0003] From the perspectives of carbon neutrality and the SDGs, technologies related to the reuse or recycling of target substances have attracted attention. Examples of such technologies include the recovery of metals or metal ions contained in liquids. As porous materials for recovering target substances such as metals and metal ions, granular porous silica with surface treatment is known, for example. For instance, Patent Document 1 describes granular porous silica having a co-continuous structure formed by a ceramic framework containing mesopores and macropores. Furthermore, Patent Document 1 describes porous silica with a surface modified with functional groups such as thiol groups as being useful for the recovery of target substances such as metals and metal ions.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2017 / 002871 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] The purpose of this invention is to provide a porous material with excellent adsorption properties and a method for recovering target substances using the porous material.

[0009] Solution for solving the problem

[0010] The inventors discovered that, in a porous material comprising a porous body having a co-continuous structure formed by a ceramic framework including mesopores and macropores, and a sulfonyl group on the surface of the ceramic framework, by adjusting the amount of sulfonyl groups contained in the porous material to 0.7 mmol / g or more and 5.0 mmol / g or less, the adsorption performance of the porous material can be improved, thus completing the present invention. That is, the present invention includes the following invention.

[0011] [1] A porous material comprising: a porous body having a co-continuous structure formed by a ceramic framework including mesopores and macropores; and a sulfonyl group modifying the surface of the ceramic framework.

[0012] The amount of the sulfonyl group contained in the porous material is more than 0.7 mmol / g and less than 5.0 mmol / g.

[0013] [2] According to the porous material of [1], wherein the amount of sulfonyl group is 3.6 mmol / g or more and 5.0 mmol / g or less.

[0014] [3] According to the porous material described in [1] or [2], wherein the modal pore diameter of the macropores of the porous body is above 200 nm and below 5000 nm.

[0015] [4] The porous material according to any one of [1] to [3], wherein the ratio of the mode diameter of the macropores of the porous body to the mode diameter of the mesopores of the porous body is 15 or more and 300 or less.

[0016] [5] The porous material according to any one of [1] to [4], wherein the ceramic framework of the porous body contains one or more elements selected from silicon, aluminum, tin, cerium, titanium and zirconium.

[0017] [6] A method for recovering a target substance, wherein the target substance is recovered from a solution containing one or more target substances selected from metals and their ions and metalloids and their ions.

[0018] The method includes a step of contacting the solution with any of the porous materials described in any one of [1] to [5].

[0019] [7] According to the method described in [6], wherein the one or more target substances are selected from transition elements containing rare earth elements and their ions, as well as typical elements of groups 1, 2 and 13-16 and their ions.

[0020] The effects of the invention

[0021] According to the present invention, a porous material with excellent adsorption properties and a method for recovering a target substance using the porous material are provided. Attached Figure Description

[0022] Figure 1 This is an enlarged view of a portion of the surface of a porous body according to one embodiment of the present invention. Detailed Implementation

[0023] Glossary of Terms

[0024] The following describes the terminology used in this specification. Unless otherwise specified, the following description applies flexibly as described in this specification.

[0025] <halogen atom>

[0026] Halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

[0027] <alkyl>

[0028] The alkyl group has, for example, 1 to 20 carbon atoms, preferably 1 to 10, more preferably 1 to 8, even more preferably 1 to 6, further preferably 1 to 5, and particularly preferably 1 to 4. The alkyl group can be linear or branched. Linear alkyl groups have 1 or more carbon atoms, while branched alkyl groups have 3 or more carbon atoms.

[0029] <Aryl>

[0030] The aryl group is, for example, a monocyclic or polycyclic aromatic hydrocarbon cyclic group (e.g., bicyclic or tricyclic). The aryl group has, for example, 6 to 14 carbon atoms, preferably 6 to 10. The polycyclic form can also be a fused ring. Examples of aryl groups include phenyl and naphthyl. Phenyl is preferred.

[0031] <Arylalkyl>

[0032] Arylalkyl is an alkyl group having one or more aryl groups, as described above regarding alkyl and aryl groups. The number of aryl groups contained in an arylalkyl group is, for example, 1 to 3, preferably 1 or 2, and more preferably 1.

[0033] <alkylaryl>

[0034] Alkyl aryl is an aryl group having one or more alkyl groups, as described above. The number of alkyl groups contained in an alkyl aryl group is, for example, 1 to 3, preferably 1 or 2, and more preferably 1.

[0035] <alkoxy>

[0036] An alkoxy group is a group represented by the formula: -O-alkyl, as explained above regarding alkyl groups.

[0037] <Aryloxy>

[0038] The aryl group is represented by the formula: -O-aryl, as explained above.

[0039] <Arylalkoxy>

[0040] Arylalkoxy groups are groups represented by the formula: -O-arylalkyl, as explained above regarding arylalkyl groups.

[0041] <alkylaryloxy>

[0042] Alkyl aryl group is a group represented by the formula: -O-alkylaryl, as explained above.

[0043] <alkylene and arylene>

[0044] Alkylene and arylene are divalent functional groups generated by removing one hydrogen atom from alkyl and aryl groups, respectively, as explained above.

[0045] <One or more substituents>

[0046] The one or more substituents are preferably one to three substituents, more preferably one or two substituents. Each or more substituents can be independently selected from, for example, hydroxyl, carboxyl, halogen atom, phosphate group, oxo group, alkoxy, aryloxy, arylalkoxy, alkylaryloxy, etc.

[0047] "Porous body"

[0048] Porous bodies have a co-continuous structure formed by a ceramic framework containing mesopores and macropores. The following describes porous bodies.

[0049] <Morphology and Shape of Porous Materials>

[0050] The morphology of porous bodies is not particularly limited. Examples of porous bodies include granules, blocks, and shaped bodies. Furthermore, the shape of porous bodies is not particularly limited. Examples of porous bodies include columnar, spherical (e.g., spherical, ellipsoidal), needle-like, scaly (flake-like), polyhedral, flat, fragmented, and blocky shapes. Examples of columnar shapes include cylindrical, elliptical, and polygonal prisms (e.g., square prisms, hexagonal prisms, octagonal prisms). A columnar shape can also be a cylindrical, elliptical, or polygonal shape with localized defects.

[0051] When the porous body is in the form of particles, the particle size is, for example, 0.5 μm or more and 7.0 mm or less. Particle size refers to the equivalent circle diameter, that is, the diameter of the circle in an observed image of the particle (e.g., a SEM image) that assumes an area equal to the area of ​​the particle. The particle size can be adjusted, for example, by grading.

[0052] When the porous body is cylindrical, its length is, for example, 1.0 mm or more and 500 mm or less, and its diameter is, for example, 1.5 mm or more and 20 mm or less. Length refers to the dimension along the direction in which the cylindrical body extends. Diameter refers to the diameter of the end face along the direction in which the cylindrical body extends. If the end face is circular, the diameter refers to the diameter of the circle. If the end face is a shape other than circular, the diameter refers to the diameter of the circle circumscribed around the end face.

[0053] <Structure of the porous body before modification>

[0054] The following is for reference Figure 1 The structure of the porous body before sulfonation modification is described.

[0055] like Figure 1 As shown, the porous body has a co-continuous structure formed by a ceramic framework 1 containing mesopores 3 and macropores 2.

[0056] In the porous body, the ceramic framework 1 and macropores 2 each possess a continuous three-dimensional network structure and are intertwined, thus forming a co-continuous structure. The co-continuous structure of the porous body can be confirmed by observing the surface or cross-section of the porous body using a scanning electron microscope (SEM).

[0057] From the viewpoint of improving adsorption performance, the mode pore size of macropore 2 is preferably 200 nm or more, more preferably 400 nm or more, and even more preferably 600 nm or more. From this viewpoint, the mode pore size of macropore 2 is preferably 5000 nm or less, more preferably 4500 nm or less, even more preferably 4000 nm or less, and even more preferably 3000 nm or less. These upper limits can be combined with any of the lower limits mentioned above.

[0058] "The mode pore size of macropore 2" as described in the examples described later refers to the mode pore size of the macropore measured by mercury intrusion porosimetry in the range of 50 nm to 500 μm.

[0059] From the viewpoint of improving adsorption performance, the mode pore size of mesopore 3 is preferably 2.0 nm or more, more preferably 5.0 nm or more, and even more preferably 10.0 nm or more. From the same viewpoint, the mode pore size of mesopore 3 is preferably 50.0 nm or less, more preferably 40.0 nm or less, and even more preferably 35.0 nm or less. These upper limits can be combined with any of the lower limits mentioned above.

[0060] "The mode pore size of mesopore 3" as described in the examples described later refers to the mode pore size of the mesopore determined by nitrogen adsorption-desorption isotherms using the BJH method.

[0061] From the viewpoint of improving adsorption performance, the ratio of the mode pore size of the macropore 2 to the mode pore size of the mesopore 3 is preferably 15 or more, more preferably 20 or more, even more preferably 30 or more, and even more preferably 40 or more. From the same viewpoint, this ratio is preferably 300 or less, more preferably 200 or less, even more preferably 150 or less, and even more preferably 100 or less. These upper limits can be combined with any of the lower limits mentioned above.

[0062] From the perspective of improving adsorption performance, the optimal specific surface area of ​​the porous body, determined by the BET method based on the nitrogen adsorption-desorption isotherm, is 100 m². 2 / g or more, more preferably 120m 2 / g or more, and more preferably 130m 2 / g or more. There is no specific upper limit to the specific surface area of ​​porous materials, typically 800 m². 2Approximately / g. The BET method for determining specific surface area using nitrogen adsorption-desorption isotherms is described in the examples below.

[0063] From the viewpoint of improving adsorption performance, the total pore volume of the porous material, as determined by mercury porosimetry, is preferably 1.5 mL / g or more and 4.0 mL / g or less, more preferably 1.8 mL / g or more and 3.5 mL / g or less, and even more preferably 2.5 mL / g or more and 3.5 mL / g or less. The method for determining the total pore volume using mercury porosimetry is described in the examples below.

[0064] From the viewpoint of improving adsorption performance, the porosity of the porous body, as determined by mercury porosimetry, is preferably 70% or more and 90% or less, more preferably 70% or more and 85% or less, and even more preferably 75% or more and 85% or less. The method for determining the porosity using mercury porosimetry is described in the examples below.

[0065] <Porous Materials>

[0066] The ceramic that forms the ceramic framework is, for example, an oxide ceramic containing a metalloid or a metallic element. The ceramic framework 1 may contain one element selected from metalloids and metallic elements, or it may contain two or more elements selected from metalloids and metallic elements.

[0067] Examples of metalloid elements include silicon. Examples of silicon-containing oxide ceramics include silicon dioxide (SiO2).

[0068] Examples of metallic elements include, in addition to aluminum and tin, transition metals such as cerium, titanium, zirconium, vanadium, chromium, iron, cobalt, nickel, palladium, platinum, copper, silver, gold, and zinc. From the viewpoint of easily creating porous bodies, aluminum, tin, cerium, titanium, and zirconium are preferred metallic elements. Examples of oxide ceramics containing aluminum, tin, cerium, titanium, or zirconium include alumina (Al₂O₃), tin oxide (SnO₂), cerium oxide (CeO₂), titanium dioxide (TiO₂), and zirconium oxide (ZrO₂).

[0069] In addition to silicon, aluminum, tin, or transition metals, oxide ceramics may also contain elements selected from alkali metals such as lithium and sodium, alkaline earth metals such as magnesium and calcium, and rare earth elements such as lanthanum, scandium, yttrium, and gadolinium.

[0070] <Methods for manufacturing porous materials>

[0071] Porous bodies can be manufactured by methods described, for example, in International Publication No. 2022 / 163834, specifically by methods including the following steps:

[0072] Step (a) involves manufacturing polyoxometalate gels via a sol-gel method;

[0073] Step (b) involves forming pores in the framework of the polyoxometalate gel manufactured in step (a); and

[0074] In step (c), the polyoxometalate gel supplied to step (b) is cleaned and / or dried as needed, and then fired to produce a ceramic block (monolithic) (porous body).

[0075] In one embodiment, the ceramic bulk body is preferably a silica bulk body. The silica bulk body has a co-continuous structure formed by a silica framework containing mesopores and macropores.

[0076] In another embodiment, the ceramic bulk material can be a bulk material of alumina, tin oxide, cerium oxide, titanium dioxide, or zirconium oxide. Similarly, in this case, the bulk material has a co-continuous structure formed by a framework of mesoporous alumina, tin oxide, cerium oxide, titanium dioxide, or zirconium oxide and macropores.

[0077] The manufactured ceramic blocks can be shaped and used as porous bodies, or they can be shaped using molds or similar methods, directly or as needed, and used as porous bodies. For example, in the gel manufacturing process, a molded ceramic block can be manufactured by using a molding mold to shape the gel into the desired form. Furthermore, the average diameter of the molded ceramic block is smaller than the average diameter of the mold.

[0078] The manufactured ceramic block can also be pulverized and used as a porous body. Pulverization can be carried out using conventional methods. For example, pulverization can be performed using a mortar and pestle, hammer mill, ball mill, bead mill, jet mill, roller mill, etc. The particle size of the pulverized porous body is preferably 0.5 μm or more and 7.0 mm or less, more preferably 2.0 μm or more and 5.0 mm or less, and even more preferably 5.0 μm or more and 3.0 mm or less. It should be noted that "particle size" refers to the equivalent circle diameter, that is, the diameter of the circle in the observed image (e.g., SEM image) of the pulverized porous body, assuming it has a circle with an area equal to that of the pulverized porous body.

[0079] Porous Materials

[0080] The porous material of the present invention comprises: a porous body having a co-continuous structure formed by a ceramic framework including mesopores and macropores; and a sulfonyl group modified on the surface of the ceramic framework. The sulfonyl group is a monovalent group represented by the formula: -SO3H. The porous material of the present invention will be described below.

[0081] <Surface Modification>

[0082] The surface of the ceramic framework is modified with sulfonyl groups. The surface of the ceramic framework can be modified with only sulfonyl groups, or it can be modified with one or more functional groups other than sulfonyl groups. Sulfonyl groups can be directly bonded to the surface of the ceramic framework, or they can be bonded to the surface of the ceramic framework through a linker.

[0083] The surface of the ceramic skeleton includes an inner surface and an outer surface. The inner surface of the ceramic skeleton includes macropores and mesopores existing inside the ceramic skeleton (i.e., not exposed on the outer surface of the ceramic skeleton), and the outer surface of the ceramic skeleton includes the inner surfaces of macropores and mesopores exposed on the outer surface of the ceramic skeleton. Preferably, at least the inner surface of the ceramic skeleton is modified with sulfonyl groups.

[0084] In one embodiment, the surface of a ceramic framework is modified with sulfonyl groups by fixing a sulfonated compound (hereinafter referred to as the "first compound") onto the surface of the ceramic framework. Methods for introducing the first compound onto the surface of the ceramic framework include, for example, chemically fixing the first compound onto the surface of the ceramic framework by means of covalent bonds; and physically fixing the first compound onto the surface of the ceramic framework by means of physical interactions such as ionic bonds and hydrophobic interactions. Methods for chemically introducing the first compound onto the surface of the ceramic framework include, for example, reacting a functional group (e.g., hydroxyl group) on the surface of the ceramic framework with the first compound to chemically fix the first compound onto the surface of the ceramic framework. The first compound can be fixed onto the surface of the ceramic framework by means of a linker. For example, a functional group that reacts with the first compound can be introduced onto the surface of the ceramic framework, and then the introduced functional group can react with the first compound to chemically fix the first compound onto the surface of the ceramic framework. Methods for introducing a functional group that reacts with the first compound onto the surface of the ceramic framework include reacting a functional group (e.g., hydroxyl group) on the surface of the ceramic framework with a silane coupling agent having a functional group that reacts with the first compound to chemically fix the silane coupling agent onto the surface of the ceramic framework. Examples of silane coupling agents having functional groups that react with the first compound include silane coupling agents having epoxy groups and / or alkyl halogens. Examples of silane coupling agents having epoxy groups include 3-glycidoxypropyltrimethoxysilane. Examples of silane coupling agents having alkyl halogens include 3-chloropropyltrimethoxysilane.

[0085] As a method for modifying the surface of a ceramic framework with sulfonation, the following approach can be used: After fixing a compound containing a thiol group (-SH) (hereinafter referred to as the "second compound") onto the surface of the ceramic framework, the thiol group contained in the second compound is converted to a sulfonation group. The second compound can be fixed onto the surface of the ceramic framework in the same way as the first compound. The conversion of the thiol group to the sulfonation group can be carried out using conventional methods. As in the case where the thiol group contained in the second compound is converted to a sulfonation group after fixing the second compound onto the surface of the ceramic framework, even if the compound initially does not contain a sulfonation group, the case where the compound eventually contains a sulfonation group through derivatization is also included in the category of "the surface of the ceramic framework is modified with sulfonation by fixing a compound containing a sulfonation group onto the surface of the ceramic framework."

[0086] The portion of the first compound excluding the sulfonyl group and the portion of the second compound excluding the thiol group can be composed of hydrogen atoms and carbon atoms, respectively. In addition to hydrogen and carbon atoms, they can also contain one or more other elements (e.g., oxygen atoms, nitrogen atoms, halogen atoms, silicon atoms, etc.). One or more compounds can be used as the first compound and the second compound, or two or more compounds can be used. The first compound and the second compound can also be used in combination. Silane coupling agents can be used as the first compound and the second compound, respectively.

[0087] The sulfonyl groups introduced onto the surface of the ceramic framework are preferably fixed to the surface of the ceramic framework using a linker such as a silane coupling agent. When the linker is, for example, a silane coupling agent, the sulfonyl groups can move flexibly while fixed to the surface of the ceramic framework due to the carbon skeleton of the silane coupling agent. Therefore, each sulfonyl group readily acts on the target substance, and multiple sulfonyl groups readily act synergistically on the target substance, further improving the adsorption performance compared to directly introducing sulfonyl groups onto the surface of the ceramic framework.

[0088] Examples of silane coupling agents containing sulfonyl groups include those represented by formula A or B.

[0089] Formula A: R a -R d -Si(-R b ) n (-R c ) 3-n

[0090] Formula B: R a -R d -Si(-O-(R e -O) m -R f ) n (-R c ) 3-n

[0091] As silane coupling agents containing thiol groups, examples of silane coupling agents represented by formula C or D can be listed.

[0092] Formula C: R g -R d -Si(-R b ) n (-R c ) 3-n

[0093] Formula D: R g -R d -Si(-O-(R e -O) m -R f ) n (-R c ) 3-n

[0094] In formula A, R a R represents sulfonyl. b Each independently represents an alkyl group, R c Each independently represents an alkoxy or halogen atom, R d It represents alkylene, arylene, or combinations thereof, and n represents an integer from 0 to 2.

[0095] In formula B, R a R c R d And n has the same meaning as equation A, R e Each independently represents an alkylene group, R f Each alkyl group is represented independently, and m represents an integer from 1 to 5, preferably an integer from 1 to 3, and more preferably an integer from 1 to 2.

[0096] In formula C, R b R c R d And n has the same meaning as equation A, R g It represents a thiol group.

[0097] In formula D, R c R d And n has the same meaning as equation A, R e R f And m has the same meaning as formula B, R g It has the same meaning as formula C.

[0098] As R b Or R f Alkyl groups, for example, include methyl, ethyl, propyl, butyl, etc.

[0099] As R cThe alkoxy or halogen atom shown can be, for example, methoxy, ethoxy, propoxy, butoxy, chlorine, bromine, iodine, etc. R c The alkoxy group shown is preferably methoxy or ethoxy. c The halogen group shown is preferably a chlorine atom.

[0100] As R d Or R e Examples of alkylene derivatives include methylene, ethylene, propylene, and butylene.

[0101] As R d Examples of arylene groups include phenylene, naphthylene, and biphenylene.

[0102] As R d The combinations of alkylene and aryl groups shown can be exemplified by groups represented by the formulas -XY-, -YX-, -XYX-, or -YXY-. In these formulas, X represents an alkylene group and Y represents an aryl group.

[0103] R d The alkylene, arylene, or combinations thereof shown may have more than one substituent.

[0104] Examples of silane coupling agents represented by Formula A include 3-(trimethoxysilyl)-1-propanesulfonic acid.

[0105] Examples of silane coupling agents as shown in Formula B include 3-(dimethoxy(2-methoxyethoxy)silyl)-1-propanesulfonic acid.

[0106] Examples of silane coupling agents represented by Formula C include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltriethoxysilane.

[0107] Examples of silane coupling agents represented by Formula D include ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctadecane-1-yloxy)silane.

[0108] The greater the amount of sulfonyl groups introduced onto the surface of the ceramic framework, the higher the adsorption performance. Therefore, from the viewpoint of effectively improving the adsorption performance of porous materials, the amount of sulfonyl groups contained in the porous material is 0.7 mmol / g or more based on the mass of the porous material, preferably 1.0 mmol / g or more, more preferably 1.3 mmol / g or more, even more preferably 1.7 mmol / g or more, and even more preferably 3.6 mmol / g or more. However, when sulfonyl groups are introduced via a linker, if the amount of sulfonyl groups introduced onto the surface of the ceramic framework increases, the amount of hydrocarbon groups (e.g., alkyl, alkylene, aryl, etc.) present in the compound introduced as the linker, such as a silane coupling agent, also increases, and the hydrophobicity of the porous material increases. If the hydrophobicity of the porous material increases, the solution containing the target substance has difficulty reaching the pores, and the sulfonyl groups introduced onto the surface of the ceramic framework cannot be effectively utilized, thus reducing the adsorption performance. In addition, when sulfonyl groups are directly introduced onto the surface of the ceramic framework, the amount of introduced sulfonyl groups is affected by the framework structure of the porous material, and therefore there is an upper limit. Therefore, from the viewpoint of effectively improving the adsorption performance of porous materials, the amount of sulfonyl groups contained in the porous material is 5.0 mmol / g or less, preferably 4.5 mmol / g or less, and more preferably 4.0 mmol / g or less, based on the mass of the porous material. These upper limits can be combined with any of the lower limits mentioned above.

[0109] The above-mentioned ranges related to the amount of sulfonyl groups contained in the porous material mainly apply to the case where the porous material is used as an adsorbent. For example, when using the porous material as an ion exchange material, the amount of sulfonyl groups contained in the porous material can be adjusted to within the above-mentioned range or outside the above-mentioned range.

[0110] "Amount of sulfonyl groups" refers to the amount of sulfur atoms originating from sulfonyl groups contained in the porous material. When all sulfur atoms contained in the porous material are sulfur atoms originating from sulfonyl groups, "amount of sulfonyl groups" refers to the total amount of sulfur atoms contained in the porous material. The amount of sulfonyl groups can be determined using conventional methods. For example, the amount of sulfonyl groups can be determined using the methods described in the examples below.

[0111] <Manufacturing Methods of Porous Materials>

[0112] In one embodiment, the porous material of the present invention can be manufactured by a method comprising the following steps:

[0113] Step (1) involves modifying the surface of the porous ceramic framework with thiol groups; and

[0114] Step (2) converts the thiol group into the sulfonate group.

[0115] This method is advantageous in that it allows for easy adjustment of the amount of sulfonyl groups contained in porous materials.

[0116] Step (1) can be carried out by contacting the porous body with a reagent (hereinafter referred to as the "first reagent") used to modify the surface of the ceramic framework of the porous body with thiol groups in a first solvent.

[0117] As a first reagent, for example, a compound having a thiol group can be used, preferably a silane coupling agent having a thiol group, more preferably a silane coupling agent represented by formula C or D.

[0118] As a primary solvent, for example, water, aqueous solutions, organic solvents and aqueous solutions, or mixtures of water can be used.

[0119] Aqueous solutions can be prepared by adding an acid to water. The acid can be selected from, for example, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, etc. Acetic acid is preferred. The concentration of acetic acid in the aqueous solution is, for example, 0.01% by mass or more and 5.0% by mass or less.

[0120] As organic solvents, they can be used for example, alcohol solvents such as methanol, ethanol, and propanol; ether solvents such as tetrahydrofuran and 2-methyl-tetrahydrofuran; ketone solvents such as acetone and methyl ethyl ketone; ester solvents such as methyl acetate and ethyl acetate; halogenated hydrocarbon solvents such as dichloromethane and chloroform; aromatic hydrocarbon solvents such as toluene and xylene; and aliphatic hydrocarbon solvents such as hexane and heptane.

[0121] The temperature at which the porous body contacts the first reagent in the first solvent is, for example, 60°C or higher and 100°C or lower. The contact time between the porous body and the first reagent in the first solvent is, for example, 2 hours or higher and 24 hours or lower.

[0122] After modifying the surface of the porous ceramic framework with thiol groups, the thiol-modified porous body is separated from the reaction mixture using solid-liquid separation methods such as filtration. The separated porous body is then washed with a cleaning solution such as pure water, dried, and used in step (2).

[0123] Step (2) can be carried out by contacting the thiol-modified porous body obtained in step (1) with a reagent for converting the thiol group to a sulfonate group (hereinafter referred to as the "second reagent") in a second solvent.

[0124] As a second reagent, oxidizing agents such as hydrogen peroxide, nitric acid, and m-chloroperbenzoic acid can be used. An aqueous solution containing an oxidizing agent can also be used as the second reagent. An aqueous solution containing an oxidizing agent can be prepared by adding the oxidizing agent to water. When using an aqueous solution containing hydrogen peroxide as the second reagent, the concentration of hydrogen peroxide in the aqueous solution is, for example, 10.0% by mass or more and 60.0% by mass or less.

[0125] Water can be used as a second solvent, for example. When hydrogen peroxide or an aqueous solution containing hydrogen peroxide is used as the second reagent, the concentration of hydrogen peroxide in the second solvent is, for example, 5.0% by mass or more and 30.0% by mass or less.

[0126] The temperature at which the thiol-modified porous body contacts the second reagent in the second solvent is, for example, 40°C or higher and 80°C or lower. The contact time between the thiol-modified porous body and the second reagent in the solvent is, for example, 0.5 hours or higher and 12 hours or lower.

[0127] After converting the thiol groups in the thiol-modified porous body to sulfonyl groups, the sulfonyl-modified porous body is separated from the reaction mixture using solid-liquid separation methods such as filtration. The separated porous body is then washed with a cleaning solution such as pure water and dried. This yields the porous material of the present invention.

[0128] In another embodiment, the porous material of the present invention can be manufactured by a method including a step of directly modifying the surface of the ceramic framework of the porous body with sulfonyl groups. As such a method, for example, the method described in RSC Adv. 2017, 7, pp. 56559-56565 can be used. According to the method described in that document, by adding chlorosulfonic acid to the porous body and stirring, the surface of the ceramic framework of the porous body can be directly modified with sulfonyl groups.

[0129] <Application>

[0130] The porous material of the present invention can be used for applications utilizing the effects of sulfonyl groups.

[0131] In one embodiment, the porous material of the present invention can be used as an ion exchange material.

[0132] Sulfonyl groups can adsorb one or more target substances selected from the group consisting of metals and their ions and metalloids and their ions. Therefore, in one embodiment, the porous material of the present invention is useful as an adsorbent material for adsorbing one or more target substances selected from the above group, and can be used to recover one or more target substances selected from the above group.

[0133] Examples of metals and their ions, as well as metalloids and their ions, include transition elements and their ions, and typical elements and their ions from groups 1, 2, and 13–16.

[0134] Transition elements include Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt, Au, Zn, Cd, Hg, and rare earth elements.

[0135] Rare earth elements include Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0136] Typical elements in groups 1, 2, and 13–16 include Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, B, Al, Si, Ga, Ge, As, Se, In, Sn, Sb, Te, Tl, Pb, Bi, Po, and At. Among them, B, Si, Ge, As, Se, Po, At, Sb, and Te are metalloids.

[0137] The adsorption performance of sulfonyl transition elements Co, Fe, and Ni, rare earth elements Y and La, and typical elements Sr and Zn is particularly high. Therefore, the porous material of the present invention is particularly useful as an adsorbent for adsorbing one or more target substances selected from these elements.

[0138] Examples of metals and metalloids adsorbed by sulfonyl groups include metal nanoparticles and metalloid nanoparticles. The metals and their ions, as well as the metalloids and their ions, adsorbed by sulfonyl groups may or may not have ligands.

[0139] Methods for recycling target materials

[0140] The method for recovering the target substance of the present invention is a method for recovering one or more target substances from a solution (hereinafter referred to as "processing target liquid") containing one or more target substances selected from metals and their ions and quasi-metals and their ions, including a step of contacting the processing target liquid with the porous material of the present invention.

[0141] When the treatment liquid is brought into contact with the porous material of the present invention, one or more target substances contained in the treatment liquid are adsorbed onto the porous material of the present invention. Thus, one or more target substances can be recovered from the treatment liquid.

[0142] Examples of liquids to be treated include wastewater discharged from factories and wastewater containing valuable metals discharged during metal refining processes. These liquids typically contain water. Wastewater or wastewater may be pretreated as needed before contacting the porous material of this invention.

[0143] The target substance contained in the treatment solution can be selected from, for example, transition metals containing rare earth metals and their ions, as well as typical elements and their ions from groups 1, 2, and 13-16. The adsorption performance of sulfonyl transition elements Co, Fe, and Ni, rare earth elements Y and La, and typical elements Sr and Zn is particularly high. Therefore, the target substance contained in the treatment solution is preferably selected from these elements.

[0144] As a method for contacting the treatment liquid with the porous material of the present invention, examples include impregnating the porous material of the present invention in the treatment liquid, and passing the treatment liquid through a column filled with the porous material of the present invention. The liquid passage can be performed, for example, using a liquid pump.

[0145] The porous material of the present invention is particularly useful in cases where the concentration of each target substance is low (for example, the concentration of each target substance is 0.1 ppm or more and 5000 ppm or less, especially 0.1 ppm or more and 100 ppm or less).

[0146] Example

[0147] The present invention will now be described in more detail based on embodiments and comparative examples, but the scope of the present invention is not limited by the embodiments and comparative examples.

[0148] [Example 1]

[0149] (1) Fabrication of silica bulk

[0150] Add 8.67 g of polyethylene glycol 10000 (manufactured by SIGMA-ALDRICH), 7.80 g of urea, and 86.7 g of aqueous acetic acid solution (acetic acid concentration: 6.06% by mass) to a 150 mL reaction vessel and stir at room temperature for 10 minutes. Place the reaction vessel in an ice bath and cool the reaction solution while stirring for 15 minutes. Add 44.7 g of tetramethoxysilane to the cooled reaction solution and stir while cooling in an ice bath for 30 minutes. After warming the reaction solution in a 30°C bath, incubate it overnight in a 30°C incubator to prepare a polysiloxane gel.

[0151] Next, the obtained polysiloxane gel was added to another reaction vessel containing 30 mL of 3 mol / L urea solution, and the mixture was heated under reflux for 12 hours. After the reaction was completed, the obtained polysiloxane gel was washed with water and dried in a dryer set to 60°C for 12 hours. After drying, it was calcined at 600°C for 5 hours in air to produce silica blocks. The prepared silica blocks were then pulverized and classified to obtain silica blocks with a particle size of 100 μm or more and 300 μm or less.

[0152] (2) Observation using a scanning electron microscope (SEM)

[0153] The surface structure of the silica bulk obtained in (1) was observed using SEM (JEOL JSM-7900F). The results confirmed that the silica bulk has a co-continuous structure formed by the silica framework and macropores.

[0154] (3) Determination of specific surface area and mode pore size of mesopores

[0155] The specific surface area and the mode pore size of the silica bulk obtained in (1) above were determined using a specific surface area / pore distribution measuring device (BELSORP-miniX manufactured by MicrotracBEL). For the silica bulk that was degassed under reduced pressure at 400°C for 3 hours, the amount of nitrogen adsorption and desorption at 77K was determined using liquid nitrogen and a multi-point method to obtain the adsorption-desorption isotherm. Based on the adsorption-desorption isotherm, the specific surface area and the mode pore size were calculated. The specific surface area was calculated using the BET method, and the mode pore size was calculated using the BJH method.

[0156] The BJH method is a method for analyzing the distribution of pore volume relative to diameter of assumed cylindrical pores according to the Barrett-Joyner-Halenda standard model (see J. Amer. Chem. Soc., 73, 373, 1951, etc. for details). In this invention, the analysis is performed in the range of pores with diameters of 2 to 200 nm.

[0157] (4) Determination of total pore volume, mode pore size of macropores and porosity

[0158] The total pore volume, mode pore diameter, and porosity of the silica bulk obtained in (1) above were determined using a mercury porosimeter (AutoPore IV 9520, Micromeritics). In the mercury porosimeter method, pressure is applied to the pores of the silica bulk to allow mercury to penetrate. The pore volume and specific surface area are determined from the pressure and the amount of mercury injected. The pore diameter is calculated from the relationship between the pore volume and specific surface area when the pores are assumed to be cylindrical. In this invention, the analysis was performed using the mercury porosimeter method within the pore diameter range of 50 nm to 500 μm. The determinations were performed under the following conditions and procedures.

[0159] (Measurement conditions)

[0160] Mercury parameters

[0161] Forward contact angle: 130.0°

[0162] Retreating contact angle: 130.0°

[0163] Surface tension: 485.0 mN / m (485.0 dynes / cm)

[0164] Mercury density: 13.5335 g / mL

[0165] Low-pressure parameters

[0166] Exhaust pressure: 50 μmHg

[0167] Exhaust time: 5.0 minutes

[0168] Mercury injection pressure: 0.0035 MPa

[0169] Balance time: 10 seconds

[0170] High pressure parameters

[0171] Balance time: 10 seconds

[0172] • Press-in volume: Adjust to 25% or more but less than 90%

[0173] • Measurement environment: 20℃

[0174] (Measurement Procedure)

[0175] (i) Weigh approximately 0.5g of sample, place it in the sample cell, and enter the weighing value.

[0176] (ii) Measure the range of 0.0048 to 0.2068 MPa in the low-pressure section.

[0177] (iii) The range of 0.2068 to 255.1060 MPa was measured in the high-pressure section.

[0178] (ii) and (iii) are performed automatically using the software attached to the device.

[0179] The results of (3) and (4) above are shown in Table 1.

[0180] [Table 1]

[0181]

[0182] (5) Preparation of thiol-modified silica bulk

[0183] 2.04 g of 3-mercaptopropyltrimethoxysilane, stirred at room temperature for 1 hour, 35 mL of aqueous acetic acid solution (acetic acid concentration: 0.1% by mass), and 5.0 g of the silica block obtained in (1) above were added to a reaction vessel. After standing at room temperature for 30 minutes, the mixture was heated at 80°C for 4 hours to prepare a thiol-modified silica block. The thiol-modified silica block was separated from the solution by filtration, washed with 500 mL of pure water, and dried to obtain 5.91 g of thiol-modified silica block.

[0184] (6) Fabrication of sulfonyl-modified silica bulk

[0185] 3.0 g of the thiol-modified silica block obtained in (5) above, 15 mL of hydrogen peroxide (hydrogen peroxide concentration: 30% by mass) and 15 mL of pure water were added to a reaction vessel and heated at 60 °C for 1 hour to convert the thiol group to a sulfonyl group, thus preparing a sulfonyl-modified silica block. After separating the sulfonyl-modified silica block from the solution by filtration, it was washed with 500 mL of pure water and dried to obtain 3.09 g of sulfonyl-modified silica block.

[0186] (7) Determination of sulfonium content

[0187] The amount of sulfur atoms contained in the sulfonated silica bulk obtained in (6) above was determined using a carbon / sulfur analysis apparatus (EMIA-Expert manufactured by Horiba Corporation). The amount of sulfur atoms determined was taken as the amount of sulfonates contained in the sulfonated silica bulk. The results are shown in Table 2.

[0188] (8) Metal adsorption test using solution immersion

[0189] 120 mg of the sulfonated silica block obtained in (6) above was immersed in 30 mL of an aqueous solution (Co concentration: 100 ppm, pH: 2) prepared by diluting the cobalt standard solution (Co1000, manufactured by Kanto Chemical Co., Ltd.) 10 times with pure water. The solution was stirred at 400 rpm for 30 minutes at 25°C. After the reaction was completed, the sulfonated silica block was separated by filtration, and the amount of Co in the filtrate was analyzed using an ICP-based luminescence analyzer (SPECTROGREEN FMD46 manufactured by Hitachi High Technology Co., Ltd.). The percentage of Co adsorbed on the sulfonated silica block relative to the initial amount of Co in the aqueous solution was calculated (hereinafter referred to as "Co adsorption rate"). The Co adsorption rate is shown in Table 2.

[0190] 120 mg of the sulfonated silica block obtained in (6) above was immersed in 30 mL of an aqueous solution (Fe concentration: 100 ppm, pH: 2) prepared by diluting the iron standard solution (Fe1000, manufactured by Kanto Chemical Co., Ltd.) 10 times with pure water. The solution was stirred at 400 rpm for 30 minutes at 25°C. After the reaction was completed, the sulfonated silica block was separated by filtration, and the amount of Fe in the filtrate was analyzed using an ICP-based luminescence analyzer (SPECTROGREEN FMD46 manufactured by Hitachi High Technology Co., Ltd.). The percentage of Fe adsorbed on the sulfonated silica block relative to the amount of Fe initially present in the aqueous solution was calculated (hereinafter referred to as "Fe adsorption rate"). The Fe adsorption rate is shown in Table 2.

[0191] 120 mg of the sulfonated silica block obtained in (6) above was immersed in 30 mL of an aqueous solution (Zn concentration: 100 ppm, pH: 2) prepared by diluting zinc standard solution (Zn1000, manufactured by Kanto Chemical Co., Ltd.) 10 times with pure water. The solution was stirred at 400 rpm for 30 minutes at 25°C. After the reaction was completed, the sulfonated silica block was separated by filtration, and the amount of Zn in the filtrate was analyzed using an ICP-based luminescence analyzer (SPECTROGREEN FMD46 manufactured by Hitachi High Technology Co., Ltd.). The percentage of Zn adsorbed on the sulfonated silica block relative to the amount of Zn initially present in the aqueous solution was calculated (hereinafter referred to as "Zn adsorption rate"). The Zn adsorption rate is shown in Table 2.

[0192] 120 mg of the sulfonated silica block obtained in (6) above was immersed in 30 mL of an aqueous solution (Ni concentration: 100 ppm, pH: 2) prepared by diluting the nickel standard solution (Ni1000, manufactured by Kanto Chemical Co., Ltd.) 10 times with pure water. The solution was stirred at 400 rpm for 30 minutes at 25°C. After the reaction was completed, the sulfonated silica block was separated by filtration, and the amount of Ni in the filtrate was analyzed using an ICP-based luminescence analyzer (SPECTROGREEN FMD46 manufactured by Hitachi High Technology Co., Ltd.). The percentage of Ni adsorbed on the sulfonated silica block relative to the initial amount of Ni in the aqueous solution was calculated (hereinafter referred to as "Ni adsorption rate"). The Ni adsorption rate is shown in Table 2.

[0193] 120 mg of the sulfonated silica block obtained in (6) above was immersed in 30 mL of an aqueous solution (Sr concentration: 100 ppm, pH: 2) prepared by diluting the strontium standard solution (Sr1000, manufactured by Kanto Chemical Co., Ltd.) 10 times with pure water. The solution was stirred at 400 rpm for 30 minutes at 25°C. After the reaction was completed, the sulfonated silica block was separated by filtration, and the amount of Sr in the filtrate was analyzed using an ICP-based luminescence analyzer (SPECTROGREEN FMD46 manufactured by Hitachi High Technology Co., Ltd.). The percentage of Sr adsorbed on the sulfonated silica block relative to the initial amount of Sr in the aqueous solution was calculated (hereinafter referred to as "Sr adsorption rate"). The Sr adsorption rate is shown in Table 2.

[0194] 120 mg of the sulfonated silica block obtained in (6) above was immersed in 30 mL of an aqueous solution (Fe1000, manufactured by Kanto Chemical Co., Ltd.) diluted 10 times with pure water and then adjusted to pH 2 with sodium carbonate (Fe and Pd concentrations: 100 ppm, pH: 2). The mixture was stirred at 400 rpm for 30 minutes at 25°C. After the reaction was completed, the sulfonated silica block was separated by filtration, and the amount of Fe and Pd in ​​the filtrate was analyzed using an ICP-based luminescence analyzer (SPECTROGREEN FMD46 manufactured by Hitachi High Technology Co., Ltd.). The Fe selectivity calculated according to the following formula is shown in Table 2.

[0195] Fe selectivity = (Amount of Fe adsorbed by sulfonyl-modified silica bulk) / (Total amount of Fe and Pd adsorbed by sulfonyl-modified silica bulk)

[0196] [Table 2]

[0197]

[0198] It should be noted that in the sulfonated modified silica block of the present invention, if the Fe selectivity is 0.7 or higher, it can be determined that no thiol groups remain in the sulfonated modified silica block (that is, the thiol groups contained in the thiol-modified silica block are completely converted into sulfon groups).

[0199] [Example 2]

[0200] In the preparation of the thiol-modified silica bulk, the amount of 3-mercaptopropyltrimethoxysilane was changed to 3.06 g. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were carried out in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0201] [Example 3]

[0202] In the preparation of the thiol-modified silica bulk, the amount of 3-mercaptopropyltrimethoxysilane was changed to 4.08 g. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were carried out in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0203] [Example 4]

[0204] In the preparation of the thiol-modified silica bulk, the amount of 3-mercaptopropyltrimethoxysilane was changed to 5.11 g. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were carried out in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0205] [Example 5]

[0206] In the preparation of the thiol-modified silica bulk, the amount of 3-mercaptopropyltrimethoxysilane was changed to 6.13 g. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were carried out in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0207] [Example 6]

[0208] In the preparation of the thiol-modified silica bulk, the amount of 3-mercaptopropyltrimethoxysilane was changed to 16.4 g. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were carried out in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0209] [Example 7]

[0210] In the preparation of the silica bulk, the amount of polyethylene glycol 10000 (manufactured by SIGMA-ALDRICH) was changed to 9.97 g. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were performed in the same manner as in Example 1. The results are shown in Tables 1 and 2. It should be noted that the prepared silica bulk exhibited a co-continuous structure, as confirmed by SEM observation in the same manner as in Example 1.

[0211] [Example 8]

[0212] In the preparation of the silica bulk, the amount of polyethylene glycol 10000 (manufactured by SIGMA-ALDRICH) was changed to 7.08 g. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were performed in the same manner as in Example 1. The results are shown in Tables 1 and 2. It should be noted that the prepared silica bulk exhibited a co-continuous structure, as confirmed by SEM observation in the same manner as in Example 1.

[0213] [Example 9]

[0214] In the preparation of the silica bulk, the reflux time in 3 mol / L urea solution was changed to 5 hours. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were performed in the same manner as in Example 1. The results are shown in Tables 1 and 2. It should be noted that the prepared silica bulk exhibited a co-continuous structure, as confirmed by SEM observation in the same manner as in Example 1.

[0215] [Example 10]

[0216] In the preparation of the silica bulk, the heating reflux time in 3 mol / L urea solution was changed to 24 hours. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were performed in the same manner as in Example 1. The results are shown in Tables 1 and 2. It should be noted that the prepared silica bulk exhibited a co-continuous structure, as confirmed by SEM observation in the same manner as in Example 1.

[0217] [Comparative Example 1]

[0218] In the preparation of the thiol-modified silica bulk, the amount of 3-mercaptopropyltrimethoxysilane was changed to 1.02 g. Otherwise, the preparation and evaluation of the sulfonyl-modified silica bulk were carried out in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0219] Comparative Example 2

[0220] The same evaluation as in Example 1 was performed using commercially available sulfonated silica (manufactured by Aldrich). The results are shown in Table 2. Additionally, the commercially available sulfonated silica used did not have a co-continuous structure. Specific surface area, macropore mode diameter, mesopore mode diameter, total pore volume, and porosity were not measured and are therefore recorded as "-" in Table 1.

[0221] [Comparative Example 3]

[0222] In the preparation of the thiol-modified silica bulk, the amount of 3-mercaptopropyltrimethoxysilane was changed to 4.08 g. Otherwise, the thiol-modified silica bulk was prepared in the same manner as in Example 1, and the same evaluation was performed using the prepared thiol-modified silica bulk. The results are shown in Tables 1 and 2.

[0223] Explanation of reference numerals in the attached figures

[0224] 1. Ceramic skeleton

[0225] 2 large holes

[0226] 3 Mesoporous

Claims

1. A porous material comprising: a porous body having a co-continuous structure formed by a ceramic framework including mesopores and macropores; and a sulfonyl group modified on the surface of the ceramic framework. The amount of the sulfonyl group contained in the porous material is more than 0.7 mmol / g and less than 5.0 mmol / g.

2. The porous material according to claim 1, wherein, The amount of the sulfonium group is 3.6 mmol / g or more and 5.0 mmol / g or less.

3. The porous material according to claim 1 or 2, wherein, The macropores of the porous body have a modal pore size of 200 nm or more and 5000 nm or less.

4. The porous material according to claim 1 or 2, wherein, The ratio of the mode diameter of the macropores of the porous body to the mode diameter of the mesopores of the porous body is 15 or more and 300 or less.

5. The porous material according to claim 1 or 2, wherein, The ceramic framework of the porous body contains one or more elements selected from silicon, aluminum, tin, cerium, titanium and zirconium.

6. A method for recovering a target substance, comprising recovering said target substance from a solution containing one or more target substances selected from metals and their ions and metalloids and their ions. The method includes the step of contacting the solution with the porous material according to claim 1 or 2.

7. The method according to claim 6, wherein, The one or more target substances are selected from transition elements containing rare earth elements and their ions, as well as typical elements and their ions from groups 1, 2, and 13-16.

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