WO2018079645A1 - Nanofeuille d'oxyde et son procédé de production - Google Patents

Nanofeuille d'oxyde et son procédé de production Download PDF

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WO2018079645A1
WO2018079645A1 PCT/JP2017/038668 JP2017038668W WO2018079645A1 WO 2018079645 A1 WO2018079645 A1 WO 2018079645A1 JP 2017038668 W JP2017038668 W JP 2017038668W WO 2018079645 A1 WO2018079645 A1 WO 2018079645A1
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oxide
oxide nanosheet
nanosheet
compound
layered
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PCT/JP2017/038668
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English (en)
Japanese (ja)
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旗 馮
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神島化学工業株式会社
国立大学法人香川大学
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Priority to JP2018547748A priority Critical patent/JP6671712B2/ja
Publication of WO2018079645A1 publication Critical patent/WO2018079645A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/06—Flat membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/10—Supported membranes; Membrane supports
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/10—Supported membranes; Membrane supports
    • B01D69/107—Organic support material
    • B01D69/1071—Woven, non-woven or net mesh
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/10—Supported membranes; Membrane supports
    • B01D69/108—Inorganic support material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B01D69/1213—Laminated layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B01D69/1216—Three or more layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/04—Oxides; Hydroxides

Definitions

  • the present invention relates to an oxide nanosheet including a two-dimensional crystal of metal oxide or a laminate thereof, an oxide nanosheet film in which the oxide nanosheet is laminated on a porous substrate, and a method for producing the oxide nanosheet and the oxide nanosheet film. This is useful as a technique for using oxide nanosheets as separation membranes.
  • Non-Patent Document 1 discloses that a layered host compound as a starting material is largely hydrated and swollen in an aqueous solution, and mechanical shearing force is applied to the layered host compound to separate it into one layer. It is disclosed that an oxide nanosheet of a two-dimensional crystal having a very thin thickness at a molecular level and having a spread in the horizontal direction is usually on the order of ⁇ m. Non-Patent Document 1 discloses that Ti-based oxide nanosheets exist as typical oxide nanosheets.
  • Patent Document 1 discloses porous crystalline mesoporous titania containing plate-like titanic acid.
  • the crystalline mesoporous titania of Patent Document 1 is a powder obtained by drying a plate-like titanic acid aqueous dispersion because it is used for a photocatalyst or the like, and is not supposed to have a structure that can be used as a separation membrane. .
  • Patent Document 2 discloses a separation membrane containing a porous matrix layer and a graphene compound.
  • Patent Document 1 it is presumed that a gap in which plate-like titanic acid is randomly stacked contributes to the pore characteristics. However, in such a plate-like titanate aggregate, the specific surface area is increased. It is presumed that the photocatalytic function can only be enhanced, and it is not possible to control pore characteristics such as forming pores in the nanosheet itself while maintaining the nanosheet shape.
  • an object of the present invention is to provide an oxide nanosheet and an oxide nanosheet film that can easily control pore characteristics and can be mass-produced at a low cost, and a method for manufacturing the oxide nanosheet and the oxide nanosheet film. There is.
  • the oxide nanosheet of the present invention includes a metal oxide two-dimensional crystal having a thickness of 0.4 to 3.0 nm or a laminate thereof, and has a through hole having a pore diameter of 0.5 to 200 nm.
  • the two-dimensional crystal corresponds to one layer which is the minimum basic structural unit constituting the layered compound
  • the laminate is a laminate of a plurality of two-dimensional crystals which are one layer.
  • the oxide nanosheet is used as a concept including not only a single-layer nanosheet composed of one layer but also a plurality of nanosheets.
  • a gap in which plate-like titanic acids are randomly stacked is assumed to contribute to pore characteristics.
  • the generated nanocrystallites are dissolved, and the spaces are pores as they are, and the size of the pore diameter can be controlled by the size of the generated nanocrystallites. Further, since nanocrystallites are formed inside the two-dimensional crystal, it can be formed as a through-hole, and the pore shape can be controlled. Furthermore, by controlling the crystal growth of the nanocrystallite, it is possible to contribute to the uniformity of the pores. That is, by controlling the nanocrystallites to be generated, the pore characteristics such as the pore size, pore shape, and pore uniformity can be easily controlled. Moreover, since pores can be formed in the nanosheet itself while maintaining the shape of the nanosheet by forming the pores using nanocrystallites, the pore characteristics can be easily controlled. Furthermore, the oxide nanosheet of the present invention can be mass-produced at a low cost. In addition, the various physical property values in the present invention are values measured by a method employed in Examples and the like.
  • an oxide nanosheet having a porosity of 1 to 75% is preferable.
  • pores can be formed in the nanosheet itself while maintaining the shape of the nanosheet, which is advantageous for easily controlling the pore characteristics.
  • the permeation rate and the like can be optimized.
  • the metal oxide is preferably an oxide nanosheet which is titanic acid or titanate. Because it is titanic acid or titanate, it is easy to form a layered compound stably and has acid resistance, so it is easy to maintain the nanosheet shape even when the nanocrystallite is dissolved, and to control the pore characteristics easily. Is advantageous. In addition, since the thickness of the nanosheet can be controlled thinly, the degree of freedom in design can be improved in any application. Furthermore, since it is hydrophilic, it is useful for passing water when used for a separation membrane or the like.
  • an oxide nanosheet having an average particle width of 0.1 to 500 ⁇ m according to an electron micrograph is preferable.
  • it although it is very thin, it can be set as the nanosheet with high two-dimensional anisotropy with the breadth in the horizontal direction.
  • the oxide nanosheet film of the present invention is characterized in that at least one oxide nanosheet is laminated so as to cover the surface of the porous substrate.
  • oxide nanosheets with controlled pore properties it is possible to easily control pore properties such as pore size, pore shape, pore uniformity, etc. Mass production is possible at low cost.
  • the oxide nanosheet film of the present invention is preferably laminated with the oxide nanosheet via a charged layer.
  • the charged layer has a charge opposite to that of the oxide nanosheet (eg, generally the oxide nanosheet is negatively charged while the charged layer is positively charged) and oxidized. It becomes possible to alternately stack the material nanosheet and the charged layer, and the degree of freedom in design when used for a separation membrane can be improved.
  • the oxide nanosheet membrane of the present invention is preferably used for a separation membrane.
  • an MF membrane microfiltration membrane
  • a UF membrane ultrafiltration membrane
  • It can be used for various membranes such as an RO membrane (reverse osmosis membrane) having pores of about 2 nm or less and an NF membrane (nanofiltration membrane) having pores of about 1 nm to about 2 nm.
  • the pore size of the oxide nanosheet of the present invention is 0.5 to 200 nm.
  • the size of the nanocrystallite can be controlled to adjust to the optimum pore size. it can.
  • the oxide nanosheet membrane of the present invention can be used as a separation membrane for seawater desalination systems.
  • the oxide nanosheet is an inorganic material, contamination such as bacteria hardly occurs.
  • the film thickness can be as high as that of graphene, and hydrophilicity and porosity can be achieved at the same time. Energy can be reduced.
  • a layered composite in which a metal compound is reacted with a layered host compound containing a metal oxide, and a plurality of product nanocrystallites are arranged inside a two-dimensional crystal of the layered host compound.
  • nanocrystallites are generated inside the two-dimensional crystal of the layered host compound.
  • the nanocrystallite is a factor that determines pore characteristics such as pore size, pore shape, and pore uniformity.
  • pore characteristics such as pore size, pore shape, and pore uniformity.
  • a nanocrystallite is produced
  • the nanocrystallite is dissolved.
  • the space in which the nanocrystallites are dissolved becomes pores as they are, and the size of the pore diameter can be controlled by the size of the nanocrystallites, and the pore shape can be controlled. You can also In addition, controlling the crystal growth of the nanocrystallite can contribute to the uniformity of the pores.
  • the third step by removing after forming a porous layered compound, it is possible to maintain the state in which pores are formed in the nanosheet itself while maintaining the shape of the nanosheet. Controlled oxide nanosheets can be produced. Moreover, the oxide nanosheet which can be mass-produced at low cost can be manufactured by setting it as such a manufacturing method.
  • the metal compound preferably contains one or more metal compounds selected from the group consisting of a barium compound, a strontium compound, a calcium compound, a bismuth compound, and a lead compound.
  • the layered host compound is a layered titanium compound, and the metal element of the metal compound is preferably reacted at a ratio of 0.05 to 10 mol with respect to 1 mol of Ti element.
  • the metal element of the metal compound is preferably reacted at a ratio of 0.05 to 10 mol with respect to 1 mol of Ti element.
  • the reaction is preferably carried out at a temperature of 40 ° C. to 300 ° C. for 0.01 hours to 1000 hours under hydrothermal conditions.
  • the higher the temperature of the hydrothermal reaction the more the nanocrystallite grows. Therefore, the nanocrystallite size (that is, the pore size) can be increased, and the pore characteristics can be controlled more easily. Oxide nanosheets can be produced.
  • the longer the hydrothermal reaction time is, the more the growth of nanocrystallites is promoted and the size of the nanocrystallites can be increased.
  • a two-dimensional anisotropic oxide nanosheet with a large pore diameter is manufactured. can do.
  • the concentration of the acid solution is preferably 0.01 to 5.0M.
  • the concentration of the basic compound is preferably 0.01 to 5.0M.
  • At least one oxide nanosheet is laminated so as to cover the surface of a porous substrate.
  • the charged layer has a charge opposite to that of the oxide nanosheet (eg, generally the oxide nanosheet is negatively charged while the charged layer is positively charged) and oxidized. It becomes possible to alternately stack the material nanosheet and the charged layer, and it is possible to manufacture an oxide nanosheet membrane that can improve the degree of freedom of design when used for a separation membrane application or the like.
  • Example 6 It is a schematic diagram which shows the production
  • Example 6 it is a photograph which shows the TEM image in each process at the time of passing through the production
  • FIG. (B) is an enlarged view of (a). 10 is a photograph showing a TEM image of an oxide nanosheet of Example 7.
  • Example 4 is a diagram showing an X-ray diffraction of the BaTiO 3 / HTO in (b) Example 3, (c) Example 2, (d) Example 1.
  • (A) It is a figure which shows the X-ray diffraction of the oxide nanosheet precursor in Example 3, (b) Example 2.
  • FIG. (A) It is a photograph when a laser is applied to the oxide nanosheet solution in Comparative Example 1 and (b) Example 1.
  • Example 6 (a) BaTiO 3 / HTO, (b) Oxide nanosheet precursor after acid treatment, (c) X-ray diffraction after heat treatment.
  • 10 is a UV-vis spectrum in Example 8.
  • 10 is a schematic configuration diagram of an apparatus used for a semipermeable membrane test in Example 8.
  • the oxide nanosheet of the present invention includes a metal oxide two-dimensional crystal having a thickness of 0.4 to 3.0 nm or a laminate thereof, and has a through hole having a pore diameter of 0.5 to 200 nm. .
  • the oxide nanosheet of the present invention is not limited to the manufacturing method shown in FIG. 1. .
  • FIG. 1 is a schematic diagram illustrating a generation model of an oxide nanosheet and an oxide nanosheet film according to an embodiment of the present invention.
  • the manufacturing method of the oxide nanosheet of this invention is not limited to the production
  • HTO layered titanic acid
  • barium hydroxide is hydrothermally reacted with HTO to form a BaTiO 3 nanocrystallite inside the two-dimensional crystal of HTO.
  • BaTiO 3 / HTO (layered) Corresponding to the composite).
  • the oxide nanosheet of the present invention includes a metal oxide two-dimensional crystal having a thickness of 0.4 to 3.0 nm or a laminate thereof.
  • the oxide nanosheet is used as a concept including not only a single-layer nanosheet (two-dimensional crystal) composed of one layer but also a plurality of nanosheets (for example, a laminate of 2 to 3 layers).
  • the thickness of the two-dimensional crystal of the metal oxide in the present invention is 0.4 to 3.0 nm from the viewpoint of forming a two-dimensional crystal structure, although it depends on the constituent elements of the metal oxide.
  • the thickness in the present invention is, as will be described later, the thickness of one layer is a value obtained from the plane spacing calculated from the peak of X-ray diffraction, and the thickness of the plurality of layers is a transmission electron microscope (TEM). ) Is the value calculated by multiplying the number of layers by the thickness of one layer obtained by X-ray diffraction.
  • the thickness of the two-dimensional crystal of the metal oxide in the present invention is preferably 0.4 to 2.5 nm, and more preferably 0.5 to 2.0 nm.
  • the thickness of the two-dimensional crystal of titanic acid is preferably 0.4 to 2.0 nm from the viewpoint of constituting a two-dimensional crystal structure. More preferably, the thickness is 5 to 1.5 nm.
  • the two-dimensional crystal of titanic acid in the present invention has an octahedral structure in which six oxygens are coordinated around titanium as a basic unit, and this unit has a sheet-like structure spread on a two-dimensional plane. To tell.
  • Non-Patent Document 1 when the starting layered compound is K 0.80 Li 0.27 ⁇ ⁇ 0.01 Ti 1.73 O 4 , one layer of titanate nanosheets obtained (ie, Ti It is disclosed that the thickness of a two-dimensional crystal having a composition of 0.87 O 2 0.54- is 1.1 to 1.3 nm from an AFM image. In addition, it is estimated that the measured value in AFM is large by the thickness of the surface and the ion or molecule adsorbed between the particle and the substrate. Although the thickness measurement method of Non-Patent Document 1 is different from the thickness measurement method of the present invention, it is assumed that there is some difference.
  • the thickness of the two-dimensional crystal of titanic acid is In the case where no molecules are adsorbed, the thickness is in the range of about 0.4 to 0.6 nm.
  • ions or molecules When ions or molecules are adsorbed, it is preferably selected so as to increase by the size of the adsorbed ions or molecules.
  • the thickness of the oxide nanosheet of the present invention is preferably in the same range as the thickness of the two-dimensional crystal when it is a single-layer nanosheet consisting of one layer, and when it includes a plurality of nanosheets, it is laminated. Although it depends on the number of layers, it is preferably 0.4 to 20.0 nm, more preferably 0.6 to 10.0 nm from the viewpoint of constituting a nanosheet with high two-dimensional anisotropy, More preferably, it is 0.6 to 5.0 nm.
  • the average particle width of the oxide nanosheet of the present invention is preferably 0.1 to 500 ⁇ m from the viewpoint of constituting a nanosheet having high two-dimensional anisotropy.
  • the average particle width of the nanosheet in the present invention is, as will be described later, a diameter (longest diameter) in which five particles in a transmission electron microscope (TEM) photograph are randomly selected and the diameter is the longest. ) Is the particle width, and the average value is the average particle width in the present invention.
  • the average particle width in the present invention is more preferably from 0.5 to 300 ⁇ m, still more preferably from 1.0 to 200 ⁇ m, from the viewpoint of production efficiency.
  • the thickness direction is extremely thin, 0.4 to 3.0 nm, while the lateral direction has a size that is several hundred times larger (for example, ⁇ m size).
  • Nanosheets with high dimensional anisotropy can be constructed.
  • the average particle width can be controlled by various methods. For example, by using a synthesis method such as a flux method, an oxide nanosheet having a relatively large average particle width can be formed.
  • the metal oxide in the present invention is not particularly limited as long as it is a metal oxide or a salt thereof that can form a two-dimensional crystal structure, but Ti-based, Nb, Ta, Ti / Nb-based, perovskite-based, Mn, Co-based , Mo, W-based, Ru-based, and salts thereof. Since oxide nanosheets are generally negatively charged, positively charged compounds such as amines are intercalated between oxide nanosheets (in some cases, amines It is estimated that the compound is bonded to a positively charged compound such as Therefore, the oxide nanosheet of the present invention may contain not only a metal oxide but also a salt thereof. Examples of the compound constituting the salt (bonded in some cases) include amines, ammonium hydroxide, phosphonium hydroxide and the like as basic compounds described later.
  • Ti-based oxide or a salt thereof as the metal oxide in the present invention.
  • the Ti-based oxide include Ti-based oxides containing other elements such as titanic acid, Mg, Ni, Co, Fe, Al, Mn, and Zr.
  • the titanic acid is not particularly limited as long as the above-mentioned octahedral structure basic unit spreads on a two-dimensional plane, but more specifically, for example, Ti 0.91 O 2 , Ti 0.
  • Ti-based oxides containing other elements include Ti 0.8 Co 0.2 O 2 and Ti 0.6 Fe 0.4 O 2 . From the viewpoint of easily controlling the pore characteristics, the Ti-based oxide is preferably titanic acid or a salt thereof.
  • metal oxides include, for example, Nb, Ta, Ti / Nb-based oxides, Nb-based oxides such as Nb 6 O 17 and Nb 3 O 8 , Ta-based materials such as TaO 3 , and Ti 2 NbO 7.
  • Ti / Nb system such as TiNbO 5 .
  • examples of the perovskite oxide include Ca 2 Nb 3 O 10 , La 2 Nb 2 O 7 , SrTa 2 O 7 , Bi 4 Ti 3 O 12 and the like.
  • Mn and Co-based oxides include Mn-based materials such as MnO 2 and Co-based materials such as CoO 2 .
  • Mo and W-based oxides include Mo-based such as MoO 2 and W-based such as W 2 O 7 .
  • examples of the Ru-based oxide include Ru-based materials such as RuO 2 .
  • the oxide nanosheet of the present invention has a pore size of 0.5 to 200 nm.
  • the pore diameter in this invention as mentioned later, ten pores in the photograph of a transmission electron microscope (TEM) were selected at random, and the average value was made into the pore diameter in this invention.
  • the pore diameter is preferably 0.7 to 150 nm, more preferably 1.0 to 100 nm, from the viewpoint of controlling the pore diameter by the size of the nanocrystallite.
  • the size of the pore diameter can be selected from the above range depending on the intended use. For example, in the case of RO membrane use, it is preferably 2.0 nm or less, and preferably 0.5 to 2.0 nm. It is more preferable. Further, for example, in the case of UF membrane use, the thickness is preferably 1.0 to 10 nm, and in the case of MF membrane use, it is preferably 50 to 200 nm, and more preferably 70 to 120 nm.
  • the oxide nanosheet of the present invention has a through hole.
  • the through hole in the present invention means a hole penetrating in the thickness direction of the oxide nanosheet.
  • the through holes formed in the oxide nanosheet contribute as pores.
  • the shape of the through hole is not particularly limited, for example, it has a cylindrical shape and depends on the shape of the nanocrystallite.
  • the oxide nanosheet of the present invention may have pores that do not penetrate due to the property that the space in which the nanocrystallites are dissolved becomes pores as it is.
  • the oxide nanosheet of the present invention preferably has a porosity of 1 to 75%.
  • porosity (%) (total pore area in TEM image) / (particle area in TEM image) ⁇ 100.
  • the porosity in the present invention is preferably 5 to 50%, more preferably 10 to 40% from the viewpoint of use in a separation membrane or the like.
  • the oxide nanosheet of the present invention can be in various forms such as powder, granule, glass, gel, and dispersed liquid, but from the viewpoint of ease of use and manufacturability, it is a dispersed liquid. Is preferred.
  • the oxide nanosheet of the present invention can be doped with an element other than the element constituting the layered compound (for example, a magnetic element or a rare earth element).
  • an element other than the element constituting the layered compound for example, a magnetic element or a rare earth element.
  • ⁇ Oxide nanosheet film> In the oxide nanosheet film of the present invention, at least one layer of the oxide nanosheet is laminated so as to cover the surface of the porous substrate.
  • a porous HTO nanosheet corresponding to an oxide nanosheet
  • porous HTO A nanosheet film corresponding to an oxide nanosheet film
  • “at least one layer is laminated so as to cover the surface of the porous substrate” only means that the oxide nanosheet spreads so as to cover the surface of the porous substrate in a single layer.
  • the layer of oxide nanosheets spreading to cover the surface of the porous substrate, or the portion existing on the porous substrate as a single layer and the layered product on the porous substrate It also includes the case where it spreads so as to cover the surface of the porous substrate while being mixed with the portion existing in the substrate. Note that, depending on the portion, the number of stacked layers of oxide nanosheets may be different. Hereinafter, descriptions of points similar to those described for the oxide nanosheet may be omitted as appropriate.
  • At least one layer of the oxide nanosheet is laminated so as to cover the surface of the porous substrate, but in the case of a separation membrane, etc., from the viewpoint of pressure loss, 1 to 10 layers are laminated. Preferably it is.
  • the distance between the layers when the oxide nanosheets are laminated depends on the basic compound used for peeling, but is preferably 2.0 nm or less, for example, 0.5 to 2.0 nm. More preferably.
  • the porous substrate in the present invention is not particularly limited as long as it is a porous substrate that supports the oxide nanosheet, and is a known porous substrate that has already been used as a filter medium or a carrier. Can be used.
  • the material, shape, and size of the porous substrate can be selected as appropriate according to the application.
  • the material of the porous substrate is preferably hydrophilic because the oxide nanosheet is hydrophilic.
  • Examples of the material constituting the porous substrate include inorganic materials, organic materials, and inorganic / organic hybrid materials, but inorganic materials are preferably used from the viewpoint of preventing contamination of bacteria and the like.
  • Inorganic materials include alumina ( ⁇ -alumina, ⁇ -alumina, anodized alumina, etc.), zirconia, zeolite, ceria, zirconia-ceria, silica, ceramics such as titanium oxide, stainless steel, hastelloy alloy, inconel alloy, nickel, nickel Examples thereof include metals such as alloys, titanium and titanium alloys, metal meshes, and the like, and alumina is preferred from the viewpoints of preparation and availability of porous substrates.
  • organic material examples include cellulose fiber, cellulose triacetate fiber, polyester fiber, polyolefin-based nonwoven fabric (for example, polypropylene fiber, polyethylene fiber, etc.), polyamide-based nonwoven fabric, and multilayer nonwoven fabric including these as a part of the nonwoven fabric.
  • a hybrid material of the inorganic material and the organic material can be used as the porous substrate.
  • the shape of the porous substrate may be any shape such as a plate shape, a cylindrical shape, a tubular shape having a polygonal cross section, a monolith shape, and a spiral shape.
  • the porous substrate has a large number of fine pores that are continuous in three dimensions.
  • the pore diameter varies depending on the use of the separation membrane, it is preferably 0.003 to 2 ⁇ m, and more preferably 0.05 to 1 ⁇ m.
  • the thickness of the porous substrate is not particularly limited as long as the structure can be stably maintained, but is usually 0.3 to 2 mm.
  • the oxide nanosheet film of the present invention is preferably laminated with the oxide nanosheet via a charged layer.
  • the charged layer in this invention is a layer which has an electric charge for laminating
  • the charged layer is not particularly limited as long as it has a charge opposite to that of the oxide nanosheet. However, since the oxide nanosheet is normally negatively charged, the charged layer is preferably charged positively.
  • polycation constituting the positively charged layer those having a positively charged functional group such as a quaternary ammonium group and an amino group are generally preferred.
  • a positively charged functional group such as a quaternary ammonium group and an amino group
  • poly (diallyldimethylammonium chloride) (PDDA) and polyethyleneimine (PEI) are preferable.
  • polystyrene sulfonic acid PSS
  • Polyvinyl sulfate PVS
  • dextran sulfate chondroitin sulfate
  • PAA polyacrylic acid
  • PMA polymethacrylic acid
  • polymaleic acid polyfumaric acid
  • organic molecular ions are both water-soluble or soluble in a mixed solution of water and an organic solvent, but are preferably used as an aqueous solution from the viewpoint of production efficiency.
  • conductive polymers and functional polymer ions such as poly (aniline-N-propanesulfonic acid) (PAN), various deoxyribonucleic acids (DNA), ribonucleic acids (RNA), and pectin
  • PAN poly (aniline-N-propanesulfonic acid)
  • DNA deoxyribonucleic acids
  • RNA ribonucleic acids
  • pectin pectin
  • the concentration of the polycation or polyanion constituting the charged layer varies depending on the polycation or polyanion used, it is generally 0.1 to 100 g / L.
  • the oxide nanosheet membrane of the present invention has controlled pore characteristics, it can be used for various separation membranes.
  • the separation membrane include a reverse osmosis membrane (RO membrane), a nanofiltration membrane (NF membrane), a microfiltration membrane (MF membrane), and an ultrafiltration membrane (UF membrane).
  • the separation membrane in the present invention can be used, for example, as a separation membrane for seawater desalination. From the viewpoint of easy control of pore characteristics, it is preferably used for RO membranes, UF membranes, MF membranes, etc., and more preferably used for RO membranes.
  • FIG. 2 shows a schematic diagram when the oxide nanosheet membrane of the present invention is used as a separation membrane (RO membrane).
  • RO membrane separation membrane
  • a separation membrane it is possible to use as a liquid separation membrane of organic molecules (for example, ethanol), a gas separation membrane of gas molecules (for example, hydrogen, oxygen, etc.), and the like.
  • organic molecules for example, ethanol
  • gas separation membrane of gas molecules for example, hydrogen, oxygen, etc.
  • the oxide nanosheet film of the present invention can also be used for ion conductive films (for example, hydrogen ion conductive films for fuel cells).
  • a layered composite in which a metal compound is reacted with a layered host compound containing a metal oxide, and a plurality of product nanocrystallites are arranged inside a two-dimensional crystal of the layered host compound.
  • a layered composite in which a metal compound is reacted with a layered host compound containing a metal oxide, and a plurality of product nanocrystallites are arranged inside a two-dimensional crystal of the layered host compound.
  • the layered composite refers to a layered composite in which a plurality of nanocrystallites formed inside the two-dimensional crystal are arranged using a two-dimensional crystal of a layered host compound as a base material.
  • the layered host compound is not particularly limited as long as it is a layered compound.
  • a layered metal chalcogenide, a layered metal oxide for example, a layered titanium compound, a layered perovskite compound, a layered manganese compound, titanium / niobate, molybdate) Etc.
  • layered metal oxyhalides for example, a layered metal phosphates (eg layered antimony phosphates), clay minerals or layered silicates (eg mica, smectite family (montmorillonite, saponite, hectorite, fluorohectorite) Etc.), kaolin family (kaolinite etc.), magadiite, kanemite etc.), layered double hydroxide and the like.
  • the layered host compound preferably includes a layered metal oxide because it preferably includes the same metal oxide as described above.
  • the layered metal oxide is preferably a layered titanium compound, a layered manganese compound, a layered perovskite compound, or the like, and more preferably a layered titanium compound.
  • the layered titanium compound is preferably a layered titanic acid hydrate.
  • the composition of layered titanic acid hydrate has the general formula H 4x / 3 Ti 2-x / 3 O 4 .nH 2 O (where x is a positive number 0 ⁇ x ⁇ 1.0, n Is a positive number).
  • the layered titanic acid hydrate has an average particle size in the radial direction of 0.5 to 100 ⁇ m, an average particle size in the width direction of 0.1 to 100 ⁇ m, and an average particle size in the thickness direction of 0.01 to 1 ⁇ m. preferable.
  • the layered titanic acid hydrate is, for example, a layered titanate represented by the general formula AxMy ⁇ zTi (2- (x / 4 + ky / 4 + z)) O 4 (where A is from Na, K, Rb, Cs). And at least one member of the group consisting of Li, Mg, Co, Ni, Zn, Mn (III), Fe (III), and k represents the valence of the M element.
  • ⁇ indicates a defect site of Ti
  • x is a positive number of 0 ⁇ x ⁇ 1.0
  • y is a positive number
  • z is 0 or a positive number
  • an acid such as nitric acid or hydrochloric acid.
  • it can be produced by the method described in JP-A-2007-022857 and the like, but can be produced by other known methods.
  • Specific examples of the layered titanate include K 0.80 Li 0.266 Ti 1.733 O 4 , K 0.80 Mg 0.40 Ti 1.60 O 4 , K 0.575 Fe 0.575 Ti.
  • a metal ion source of a metal compound for substituting ions existing between layers of the layered host compound for example, H 3 O + in the case of HTO
  • Ba 2+ , Sr 2+ , Ca examples thereof include ions of alkaline earth metals such as 2+ , Pb 2+ ions, and Bi 3+ ions.
  • Various ion sources can be used, but when a plurality of ion sources are used, a Ba source is first introduced and a Ba-based nanocrystallite (for example, BaTiO 3 when a barium compound is reacted with a layered titanium compound).
  • BaTiO 3 nanocrystallites are more stable than titanic acid hydrate, and even if the generated BaTiO 3 nanocrystallites and other ions such as K + and Na + come into contact with each other, BaBa 3 nanocrystallites are formed. Since the 2+ ions are difficult to replace with other ions, it is preferable to introduce the Ba source first.
  • the metal compound contains at least one metal compound selected from the group consisting of a barium compound, a strontium compound, a calcium compound, a bismuth compound, and a lead compound from the viewpoint of easily controlling the pore characteristics. Is preferred.
  • the barium compound that can be used as the Ba source is not particularly limited, but is preferably one or more barium compounds selected from the group consisting of barium hydroxide, barium oxide, barium carbonate, barium chloride, barium nitrate, and barium acetate. From the viewpoint of easy availability and availability, barium hydroxide is more preferable. Other organic acid barium can also be adopted as an optional component.
  • the strontium compound that can be used as the Sr source is preferably one or more strontium compounds selected from the group consisting of strontium hydroxide, strontium oxide, strontium carbonate, strontium chloride, strontium nitrate, strontium sulfate, and strontium acetate. From the viewpoint of availability and availability, strontium hydroxide is more preferable. Other organic acid strontium can also be adopted as an optional component.
  • the calcium compound that can be used as the Ca source is preferably one or more calcium compounds selected from the group consisting of calcium hydroxide, calcium oxide, calcium carbonate, calcium chloride, calcium nitrate, calcium sulfate, and calcium acetate. From the viewpoint of availability and availability, calcium hydroxide is more preferable. Other organic acid calcium can also be adopted as an optional component.
  • the bismuth compound that can be used as the Bi source is preferably one or more bismuth compounds selected from the group consisting of bismuth hydroxide, bismuth oxide, bismuth carbonate, bismuth chloride, bismuth nitrate, bismuth sulfate, and bismuth acetate.
  • Bismuth oxide is more preferable from the viewpoint of availability as a raw material.
  • Other organic acid bismuth can also be adopted as an optional component.
  • the lead compound that can be used as the Pb source is preferably one or more lead compounds selected from the group consisting of lead hydroxide, lead oxide, lead carbonate, lead chloride, lead nitrate, lead sulfate, and lead acetate. From the viewpoint of availability and availability, lead hydroxide is more preferable. Other organic acid lead can also be adopted as an optional component.
  • the metal element of the metal compound is preferably reacted at a rate of 0.05 to 10 mol, more preferably at a rate of 0.1 to 5 mol, with respect to 1 mol of the main element constituting the layered host compound. More preferably, the reaction is carried out at a ratio of 2 to 1 mol.
  • the metal element of the metal compound is preferably reacted at a ratio of 0.05 to 10 mol with respect to 1 mol of Ti element, and reacted at a ratio of 0.1 to 5 mol. It is more preferable to carry out the reaction at a ratio of 0.2 to 1 mol.
  • the first step of the present invention it is preferable to grow a nanocrystallite by hydrothermally reacting a metal compound with a layered host compound.
  • a layered composite in which a plurality of nanocrystallites are arranged inside the two-dimensional crystal of the layered host compound can be obtained.
  • the temperature during the hydrothermal treatment is preferably 40 ° C. to 300 ° C., more preferably 60 ° C. to 250 ° C. from the viewpoint of obtaining an optimum pore diameter, since the nanocrystallite grows as the temperature of the hydrothermal reaction increases. 80 to 200 ° C is more preferable.
  • the longer the hydrothermal reaction time the more the growth of nanocrystallites is promoted. Therefore, from the viewpoint of obtaining an optimum pore diameter, 0.01 hours to 1000 hours are preferable, and 0.1 Time to 100 hours is more preferable, and 1 hour to 48 hours is still more preferable.
  • the size of the nanocrystallite of the product is almost the same as the size of the obtained pore diameter, it is preferable to control the size of the nanocrystallite so as to obtain a desired pore diameter.
  • the size of the nanocrystallite is also 0.5 to 200 nm.
  • the size of the nanocrystallite also contributes to the through hole. Therefore, for example, when the obtained pores are to be through-holes, it is preferable to control the size of the nanocrystallite in the two-dimensional crystal thickness direction so as to be larger than the thickness of each layer (single layer) of the layered composite. .
  • the thickness of each layer (single layer) of the layered composite depends on the composition to be formed, in the case of layered titanic acid hydrate, one layer of titanate nanosheet obtained from Non-Patent Document 1 (that is, It is disclosed that the thickness of a two-dimensional crystal having a composition of Ti 0.87 O 2 0.54- is 1.1 to 1.3 nm from an AFM image. Therefore, it is preferable to set the reaction conditions so that the size of the nanocrystallite in the two-dimensional crystal thickness direction is larger than this range.
  • the obtained nanocrystallite depends on the layered host compound and the metal compound, and can be obtained as a nanocrystallite containing a metal ion of the metal compound.
  • the obtained layered composite can be obtained as a layer containing a nanocrystallite containing a metal ion of a metal compound using the layer structure of the layered host compound as a base material.
  • the resulting nanocrystallite is a BaTiO 3 nanocrystallite
  • the resulting layered composite is a layered composite composed of BaTiO 3 nanocrystallite / layered titanium compound. You can get a body.
  • a barium compound is hydrothermally reacted with a layered titanium compound, and a plurality of product BaTiO 3 nanocrystallites are arranged inside the two-dimensional crystal of the layered titanium compound.
  • a layered composite (BaTiO 3 nanocrystallite / layered titanium compound) can be formed. More specifically, for example, as shown in FIG.
  • layered titanic acid H 1.07 Ti 1.73 O 4 .xH 2 O (HTO)
  • HTO barium hydroxide
  • BaTiO 3 nanocrystallites can be formed inside the two-dimensional crystal of HTO
  • BaTiO 3 / HTO corresponding to a layered composite
  • the solvent used in the reaction is preferably a hydrophilic solvent from the viewpoint of controlling the solubility and generating topotactic.
  • the hydrophilic solvent is not particularly limited as long as it has hydrophilicity, for example, water, alcohol such as ethanol, methanol, isopropanol, etc., glycerin, acetone, amines and other solvents that are freely miscible with water,
  • a mixed solution containing two or more of these hydrophilic solvents may be used, such as a mixed solution of water and alcohol.
  • impurities may be included to such an extent that the effects of the present invention are not impaired.
  • water or a mixed solution of water and alcohol is preferable, and water is more preferable.
  • the volume ratio of water and alcohol is preferably 100: 0 to 0: 100, more preferably 95: 5 to 5:95, from the viewpoint of controlling the solubility. 90:10 to 10:90 are more preferable.
  • the method for producing an oxide nanosheet according to the present invention includes forming an through-hole in each layer of the layered composite by dissolving the nanocrystallites using an acid solution in the layered composite, whereby the oxide nanosheet precursor Including a second step of obtaining a body.
  • the oxide nanosheet precursor in this invention is a porous nanosheet which has a pore, it is a thing before peeling between layers, and means the nanosheet of the state by which the several layer was laminated
  • description of points similar to those described elsewhere may be omitted as appropriate.
  • the acid solution in the present invention is not particularly limited as long as it can dissolve nanocrystallites.
  • inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid, lactic acid And organic acids such as From the viewpoint of production efficiency, an inorganic acid is preferable, and specifically, hydrochloric acid is preferably used.
  • the concentration of the acid solution in the present invention is preferably 0.01 to 5.0 M from the viewpoint of maintaining the nanosheet shape without dissolving the base material while dissolving the nanocrystallites, 4.0M is more preferable, and 1.0 to 3.0M is even more preferable.
  • the temperature during the acid treatment in the present invention is preferably 10 ° C. to 80 ° C., more preferably 15 ° C. to 50 ° C., from the viewpoint of dissolving the nanocrystallites.
  • the time for the acid treatment is preferably 0.01 hours to 1000 hours, more preferably 0.1 hours to 100 hours, and even more preferably 1 hour to 48 hours from the viewpoint of dissolving the nanocrystallites.
  • the solvent used at the time of an acid treatment is water.
  • the nanocrystallite is dissolved by acid treatment, so that the space becomes pores.
  • the shape of the space contributes to the size of the pore diameter and the through hole.
  • a preferred embodiment for example, as shown in FIG. 1, with an acid solution (b) BaTiO 3 / HTO, by dissolving BaTiO 3 nanocrystallites, BaTiO 3 / HTO (C) Porous HTO (corresponding to an oxide nanosheet precursor) can be formed by forming a through hole in each layer.
  • the method for producing an oxide nanosheet according to the present invention includes a third step in which a basic compound is allowed to act on the oxide nanosheet precursor to separate the layers.
  • peeling between layers in the present invention is intended to peel so as to be a single-layer nanosheet consisting of one layer, but depending on the peeling conditions, a plurality of nanosheets may be included. Therefore, it is used as a concept including not only a single-layer nanosheet (two-dimensional crystal) but also a plurality of layers of nanosheets (laminate).
  • description of points similar to those described elsewhere may be omitted as appropriate.
  • the mechanism of peeling is presumed as follows.
  • the basic compound When a basic compound is allowed to act on the oxide nanosheet precursor, the basic compound enters between the layers of the oxide nanosheet precursor, and the layers swell. Due to the swelling between the layers, the layers are greatly expanded about 100 times. As a result, the interaction acting between the layers is extremely lowered, and when mechanical shearing such as shaking the whole solution is applied, it is presumed that the layers are separated to a state close to one layer.
  • the basic compound used at the time of the peeling treatment is preferably a compound that induces a high swelling state by introducing it between the layers, reduces the strong electrostatic interaction acting between the host layers, and can lead to peeling.
  • Amine, ammonium hydroxide, phosphonium hydroxide and the like are preferable.
  • amines one or more selected from primary amines, secondary amines, and tertiary amines are preferably used, but amines having an alkyl group or alkenyl group having 1 to 10 carbon atoms are more preferable. .
  • substituted amines such as monoethanolamine, diethanolamine, and triethanolamine can also be used. These can be used alone or in admixture of two or more. From the viewpoint of low cost, propylamine is preferable.
  • the ammonium hydroxide is preferably a quaternary ammonium hydroxide such as a tetraalkylammonium hydroxide having an alkyl group having 2 to 6 carbon atoms, specifically, tetramethylammonium hydroxide, tetraethylammonium hydroxide, One or more selected from tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and tetrapentylammonium hydroxide are particularly preferable.
  • a quaternary ammonium hydroxide such as a tetraalkylammonium hydroxide having an alkyl group having 2 to 6 carbon atoms, specifically, tetramethylammonium hydroxide, tetraethylammonium hydroxide, One or more selected from tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and tetrapentylammonium
  • a quaternary phosphonium hydroxide for example, a quaternary phosphonium hydroxide is preferable, and as the quaternary phosphonium hydroxide, tetraethylphosphonium hydroxide, tetrapropylphosphonium hydroxide, tetrabutylphosphonium hydroxide, tetrapentylphosphonium hydroxy are used.
  • tetraalkylphosphonium hydroxide having an alkyl group having 2 to 8 carbon atoms such as tetrahexylphosphonium hydroxide; tetraphenylphosphonium hydroxide; ethyltriphenylphosphonium hydroxide, butyltriphenylphosphonium hydroxide, pentyltriphenylphosphonium Hydroxide, 2-dimethylaminoethyltriphenylphosphonium hydroxide, methoxymethyltriphenylphosphonium hydride Triphenylphosphonium hydroxides, such as Kishido like.
  • the concentration of the basic compound in the present invention is preferably 0.01 to 5.0 M, more preferably 0.05 to 4.0 M, and more preferably 0.1 to 3. More preferably, it is 0M.
  • the temperature during the peeling treatment is preferably 10 ° C. to 80 ° C., more preferably 15 ° C. to 50 ° C. from the viewpoint of peeling the layers.
  • the time for the peeling treatment is preferably 0.01 hours to 1000 hours, more preferably 0.1 hours to 100 hours, and even more preferably 1 hour to 48 hours from the viewpoint of peeling the layers.
  • the solvent used at the time of a peeling process is water.
  • the oxide nanosheet in order to obtain an oxide nanosheet after the peeling treatment, the oxide nanosheet becomes a salt and may be bonded to a basic compound used during the peeling treatment.
  • a basic compound used during the peeling treatment For example, when an amine is used as the basic compound, it may exist as an oxide salt nanosheet bonded to the amine. More specifically, when the oxide nanosheet is a titanate nanosheet and the basic compound is an amine, the titanate nanosheet may exist as a titanate nanosheet bonded to an amine.
  • the obtained oxide nanosheet can be in various forms such as powder, granule, glass, gel, and dispersed liquid depending on the use to be used. From the viewpoint of ease of use and ease of production, the dispersed oxide liquid sheet can be used. It is preferable that When the oxide nanosheet dispersion liquid is used, the oxide nanosheet can be dispersed in water and can contain any component such as a dispersion improver. The concentration of the oxide nanosheet dispersion is preferably in the range of 0.01 to 0.5M. Further, the dispersion liquid can be powdered by removing the dispersion medium by heating or the like.
  • a basic compound is allowed to act on porous HTO, and each layer of porous HTO is peeled off.
  • a porous HTO nanosheet (corresponding to an oxide nanosheet) can be obtained.
  • the oxide nanosheet of the present invention that is, a metal oxide two-dimensional crystal having a thickness of 0.4 to 3.0 nm or a laminate thereof is obtained.
  • An oxide nanosheet having a through hole with a pore diameter of 0.5 to 200 nm can be obtained.
  • the present invention is characterized in that an oxide nanosheet film is produced by laminating at least one oxide nanosheet obtained by the production method so as to cover the surface of a porous substrate.
  • a layer-by-layer method can be used for producing the film.
  • the porous substrate to be used is as described above, but before laminating the oxide nanosheet, the surface of the porous substrate can be dedusted and cleaned by solvent washing, acid washing, ultrasonic washing, etc. as necessary. Good. From the viewpoint of decomposing organic substances on the surface of the porous substrate, it is preferable to perform acid cleaning.
  • As conditions for the acid washing for example, washing in a mixed solvent of alcohol / inorganic acid (for example, methanol / hydrochloric acid) can be performed for about 1 minute to 1 hour.
  • the mixing ratio of the alcohol / inorganic acid is not particularly limited, and examples thereof include about 2: 1 to 0.1: 1.
  • oxide nanosheets As an actual operation of laminating oxide nanosheets, (1) In order to make the oxide nanosheets easily adhere, surface treatment of the porous substrate is performed. (2) The porous substrate is immersed in the oxide nanosheet dispersion. (3) Wash with distilled water. (4) It is immersed in an aqueous solution containing a basic compound. (5) Wash with distilled water. (6) It is immersed in an aqueous solution containing a polycation constituting the charged layer. (7) One layer of oxide nanosheets can be laminated on the porous substrate by washing with distilled water. That is, since the series of operations from (2) to (7) is one cycle and one cycle corresponds to one layer, the number of cycles can be determined according to the number of layers to be stacked. For example, when six layers of oxide nanosheets are to be laminated on a porous substrate, six cycles are performed. The number of layers to be stacked can be appropriately determined depending on various applications.
  • a charge layer on the surface of the porous substrate.
  • Such a layer can be selected from the aforementioned charged layers.
  • the oxide nanosheet is negatively charged, it is preferable to select from a positively charged charged layer.
  • the layer between the porous substrate and the oxide nanosheet (charged layer used in (1)) and the layer between the oxide nanosheet and the oxide nanosheet (charged layer used in (6)) ) May be the same charged layer or may be selected from different charged layers.
  • the surface of the porous substrate (if necessary, the surface was acid-washed in the polycation solution constituting the charged layer).
  • a positively charged layer can be formed on the porous substrate.
  • conditions for such immersion treatment for example, it is preferable to immerse in an aqueous polycation solution under conditions of a time of about 1 minute to 1 hour and a temperature of about 15 ° C. to 50 ° C.
  • a plurality of negatively charged oxide nanosheets solidified on the positively charged charged layer It can be laminated in a state.
  • the immersion can be performed in an aqueous oxide nanosheet solution at a time of about 1 minute to 1 hour and at a temperature of about 15 ° C. to 50 ° C. .
  • excess oxide nanosheets can be removed by washing with distilled water.
  • the oxide nanosheet is obtained by immersing the oxide nanosheet (assuming a plurality of layers) / charged layer / porous substrate in an aqueous solution containing the above basic compound.
  • the basic compound may enter between the multiple layers, the layers may swell, the interaction acting between the layers may be reduced, and the layers may be separated.
  • One layer. The conditions during the immersion treatment are as described above.
  • the excess oxide nanosheet peeled off can be removed by washing with distilled water.
  • the oxide nanosheet (assuming a single layer) / charged layer / porous substrate is immersed in an aqueous solution containing the polycation constituting the above-mentioned charged layer, thereby negatively charged oxide
  • a charged layer comprising a polycation can be formed on the surface of the nanosheet, and a layer structure of charged layer / oxide nanosheet (assuming a single layer) / charged layer / porous substrate can be obtained.
  • the conditions during the immersion treatment are as described above.
  • the excess polycation can be removed by washing with distilled water.
  • the series of operations from (2) to (7) is regarded as one cycle, and one layer can be laminated by passing through one cycle.
  • the thickness was obtained from the number of layers from the particles in the TEM photograph, and the thickness of one layer was obtained from the interplanar spacing obtained by X-ray diffraction of the oxide nanosheet.
  • the average particle width For the average particle width, five oxide nanosheets in the TEM photograph were randomly selected, the diameter (longest diameter) having the longest diameter was defined as the particle width, and the average value was defined as the average particle width.
  • pore diameter 10 pores in the TEM photograph were randomly selected, and the average value was taken as the pore diameter.
  • the cross-sectional shape of the pore is circular
  • the diameter when replaced with a perfect circle having the same cross-sectional area is the pore diameter, and when it cannot be replaced with a perfect circle like an ellipse, The diameter (longest diameter) with the longest pore diameter was defined as the pore diameter.
  • the hole area ratio was calculated by the following calculation formula.
  • Opening ratio (%) (total pore area in TEM image) / (particle area in TEM image) ⁇ 100
  • the cross-sectional shape of the pore is circular, assuming that it is a perfect circle having the same cross-sectional area, the diameter of the pore is the largest when it cannot be replaced with a perfect circle such as an ellipse.
  • the total pore area was calculated assuming that the longer diameter (longest diameter) was the diameter of a perfect circle.
  • UV-vis Ultraviolet / visible absorption spectrum
  • Example 1 (Preparation of layered titanic acid hydrate)
  • Ti titanium oxide
  • potassium hydroxide sodium hydroxide
  • Yaku Kogyo Co., Ltd. lithium hydroxide monohydrate 0.37 g
  • the reaction was performed under hot conditions. The temperature rising rate at this time was 300 ° C./hour.
  • the obtained particles were layered particles of K 0.80 Li 0.27 ⁇ ⁇ 0.01 Ti 1.73 O 4 . Note that ⁇ indicating a defective portion of Ti is a small positive number generally less than 0.01.
  • the composition of the layered particles was determined by atomic absorption analysis, and confirmed to be potassium lithium titanate by X-ray diffraction measurement (XRD).
  • Porous HTO nanosheets (oxide nanosheets) were prepared by adding 0.1 g of porous HTO to 100 mL of 0.1 M n-propylamine (PA) aqueous solution and stirring the mixture at 300 rpm for 24 hours.
  • PA n-propylamine
  • Example 2 a porous HTO nanosheet (oxide nanosheet) was produced in the same manner as in Example 1 except that the conditions were changed as shown in Table 1.
  • Example 1 In Example 1, peeling treatment was not performed (see Table 1), and the obtained porous HTO (oxide nanosheet precursor) was used as an evaluation sample.
  • Example 8 (Production of oxide nanosheet film) A layer-by-layer method was used for producing the oxide nanosheet film.
  • the filter was immersed in the oxide nanosheet dispersion obtained in Example 1 for 5 minutes. (3) Thereafter, it was washed with distilled water. Next, (4) the substrate was immersed in a 0.1 M n-propylamine (PA) aqueous solution for 5 minutes to separate the layers. (5) Thereafter, it was washed with distilled water. Next, (6) the filter was immersed in a 20 g / L polydiallyldimethylammonium (PDDA, Polysciences, Inc. weight average molecular weight (Mw) 240,000) aqueous solution for 5 minutes. (7) Thereafter, it was washed with distilled water.
  • PDDA polydiallyldimethylammonium
  • the series of operations (2) to (7) described above is defined as one cycle, and six cycles are repeated to form a six-layer film on the porous substrate, and the film is formed from the UV-vis spectrum. confirmed.
  • the semipermeable membrane test was conducted using a glass apparatus as shown in FIG.
  • the apparatus used was previously cleaned and dried with a dryer at 60 ° C.
  • a filter in which the oxide nanosheet prepared in Example 8 was laminated between a cell on the ionic water side and a cell on the pure water side of this device was sandwiched so that the cell would not tilt.
  • 25 mL of 25 wt% NaCl aqueous solution was put in the cell on the ion water side, and 25 mL of pure water was put in the cell on the pure water side.
  • the change in the water level of the cell after a predetermined time was recorded. The results are shown in Table 2.
  • the obtained particles were layered particles of K 0.80 Li 0.27 ⁇ ⁇ 0.01 Ti 1.73 O 4 . Note that ⁇ indicating a defective portion of Ti is a small positive number generally less than 0.01.
  • the composition of the layered particles was determined by atomic absorption analysis, and confirmed to be potassium lithium titanate by X-ray diffraction measurement (XRD).
  • Porous HTO nanosheets (oxide nanosheets) were prepared by adding 0.1 g of porous HTO to 100 mL of 0.1 M n-propylamine (PA) aqueous solution and stirring the mixture at 300 rpm for 24 hours.
  • PA n-propylamine
  • FIG. 3 is a photograph showing a TEM image in each step in Example 6 when the same generation step as in FIG. 1 was performed.
  • Figure 3 (a) is a photograph showing a TEM image of the layered titanic acid hydrate (H 1.07 Ti 1.73 O 4 ⁇ xH 2 O (HTO)).
  • FIG. 3B is a photograph showing a TEM image of the BaTiO 3 / HTO layered composite. Those black particulate in the TEM photograph shown in FIG. 3 (b) is a BaTiO 3 nanocrystallites.
  • FIG.3 (c) is a photograph which shows the TEM image of porous HTO (equivalent to an oxide nanosheet precursor). The TEM photograph in FIG.
  • FIG.3 (d) is a photograph which shows the TEM image of a porous HTO nanosheet (equivalent to an oxide nanosheet). Gray ovals to circles in the TEM photograph in FIG. 3D are pores, and these correspond to each of the pores formed in the nanosheet itself.
  • FIG. 4A is a photograph showing a TEM image of the oxide nanosheet of Example 1.
  • FIG. 4 (a) it was observed that the obtained oxide nanosheet (gray portion in the center of the photograph) was a sheet shape that was two-dimensionally expanded from a circular shape to an elliptical shape.
  • the average particle width was determined from several photographs with the scale shown in FIG.
  • the oxide nanosheet of Example 1 was not a single layer but two layers. It was found that the thickness of the oxide nanosheet was about 1.8 nm from the thickness (0.9 nm) of the single oxide nanosheet obtained from the result of X-ray diffraction.
  • FIG. 4 (b) is an enlarged view of FIG. 4 (a).
  • the gray circular thing in the TEM photograph of FIG.4 (b) is a pore.
  • the pore diameter and the open area ratio were calculated from FIG.
  • FIG. 5 is a photograph showing a TEM image of the oxide nanosheet of Example 7.
  • the gray ellipsoidal thing in the TEM photograph of FIG. 5 was a pore, and the pore diameter was 80 nm.
  • FIG. 6 is a diagram showing X-ray diffraction of a BaTiO 3 / HTO layered composite in (a) Example 4, (b) Example 3, (c) Example 2, and (d) Example 1.
  • FIG. A peak derived from layered titanic acid was observed, and a peak derived from BaTiO 3 was too small to be observed.
  • Example 3 Example 3,
  • Example 2 Example 1 were compared, the peak derived from layered titanic acid tended to decrease as the Ba / Ti molar ratio increased. This is presumed to be because the amount of BaTiO 3 nanocrystallites generated increases.
  • FIG. 7 is a diagram showing X-ray diffraction of the oxide nanosheet precursor in (a) Example 3 and (b) Example 2. That is a diagram showing an X-ray diffraction of the porous HTO by acid treatment of BaTiO 3 / HTO layered composite. Peaks derived from layered titanic acid and peaks derived from anatase (TiO 2 ) were observed, indicating that the two-dimensional crystal structure was maintained. It is thought that anatase was produced by the dissolution reaction of BaTiO 3 .
  • FIG. 8 is a photograph when laser light is applied to the oxide nanosheet dispersion liquid in (a) Comparative Example 1 and (b) Example 1.
  • Comparative Example 1 in FIG. 8A the porous HTO particle size before the peeling treatment was large, so even when the laser beam was applied, the light was reflected and scattered and could not pass through the solution.
  • Example 1 of FIG. 8B since it is a colloidal solution of HTO nanosheets obtained by peeling treatment, a Tyndall phenomenon peculiar to colloid was observed when laser light was applied. From this, it was found that the porous HTO particles were separated from the nanosheet.
  • FIG. 9 is a BaTiO 3 nano crystallites in the porous HTO particles went absence (i.e., that they are all dissolved BaTiO 3 nano crystallite acid) to confirm the.
  • FIG. 9 shows, in Example 6, (a) BaTiO 3 / HTO layered composite, (b) oxide nanosheet precursor after acid treatment, (c) oxide nanosheet precursor after acid treatment at 2 ° C. It is a figure which shows the X-ray diffraction after heat-processing for time.
  • FIG. 9A a BaTiO 3 / HTO layered composite was observed, and a peak derived from BaTiO 3 was observed. However, the peak derived from BaTiO 3 was not observed in the oxide nanosheet precursor after acid treatment in FIG.
  • FIG.9 (c) the sample of FIG.9 (b) was baked at 900 degreeC for 2 hours. Since only TiO 2 (anatase and rutile) was produced, it was found that all BaTiO 3 nanocrystallites were removed. If BaTiO 3 nanocrystallites remain but are too small to observe a peak derived from BaTiO 3 , firing should produce a compound of Ba and Ti, but it was not observed, All was removed by acid treatment.
  • FIG. 10 shows a UV-vis spectrum of an oxide nanosheet film prepared by using a layer-by-layer method.
  • the HTO nanosheet exhibits light absorption in the wavelength range of 300 to 400 nm. As the number of laminations increased, the light absorption in the wavelength range of 300 to 400 nm increased. From this, it can be confirmed that a film in which the HTO nanosheet is laminated on the porous substrate surface is formed.
  • the filter (oxide nanosheet film) on which the oxide nanosheet obtained in Example 8 is laminated has a function of permeating water molecules and a function of blocking ions, and a semipermeable membrane (reverse osmosis membrane). It was confirmed that it could be used as

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  • Inorganic Compounds Of Heavy Metals (AREA)

Abstract

L'invention concerne une nanofeuille d'oxyde et un film de nanofeuille d'oxyde pouvant être produits en série à faible coût et dont les caractéristiques de pores peuvent être maîtrisées ; et des procédés de production d'une nanofeuille d'oxyde et d'un film de nanofeuille d'oxyde. Cette nanofeuille d'oxyde comprend des cristaux bidimensionnels d'un oxyde métallique qui sont d'une épaisseur de 0,4 à 3,0 nm ou un stratifié de ceux-ci, et a des trous traversants ayant un diamètre de pore de 0,5 à 200 nm. De plus, ce film de nanofeuille d'oxyde comprend au moins une couche de la nanofeuille d'oxyde stratifiée de manière à recouvrir la surface d'un matériau de base poreux.
PCT/JP2017/038668 2016-10-28 2017-10-26 Nanofeuille d'oxyde et son procédé de production WO2018079645A1 (fr)

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CN114405288A (zh) * 2022-02-07 2022-04-29 明士新材料有限公司 一种新型高性能聚硫酸盐超滤膜的制备方法
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