WO2001017667A1 - Procede d'obtention de particules d'oxyde metallique - Google Patents

Procede d'obtention de particules d'oxyde metallique Download PDF

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Publication number
WO2001017667A1
WO2001017667A1 PCT/US2000/040848 US0040848W WO0117667A1 WO 2001017667 A1 WO2001017667 A1 WO 2001017667A1 US 0040848 W US0040848 W US 0040848W WO 0117667 A1 WO0117667 A1 WO 0117667A1
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iron
seed particles
coated
metal oxide
particles
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PCT/US2000/040848
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English (en)
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WO2001017667A8 (fr
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Timothy J. Barder
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Eichrom Technologies, Inc.
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Priority to AU11068/01A priority Critical patent/AU1106801A/en
Publication of WO2001017667A1 publication Critical patent/WO2001017667A1/fr
Publication of WO2001017667A8 publication Critical patent/WO2001017667A8/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C1/00—Magnetic separation
    • B03C1/005—Pretreatment specially adapted for magnetic separation
    • B03C1/01—Pretreatment specially adapted for magnetic separation by addition of magnetic adjuvants
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
    • C01B13/14—Methods for preparing oxides or hydroxides in general
    • C01B13/36—Methods for preparing oxides or hydroxides in general by precipitation reactions in aqueous solutions
    • C01B13/363—Mixtures of oxides or hydroxides by precipitation
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/22—Compounds of iron
    • C09C1/24—Oxides of iron
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/28—Compounds of silicon
    • C09C1/30—Silicic acid
    • C09C1/3045—Treatment with inorganic compounds
    • C09C1/3054—Coating
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
    • C09C3/06—Treatment with inorganic compounds
    • C09C3/063—Coating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/0036—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity
    • H01F1/0045—Zero dimensional, e.g. nanoparticles, soft nanoparticles for medical/biological use
    • H01F1/0054—Coated nanoparticles, e.g. nanoparticles coated with organic surfactant
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
    • H01F1/36—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites in the form of particles
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/50—Agglomerated particles
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
    • C01P2004/84—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases one phase coated with the other

Definitions

  • the invention relates to a method of preparing a metal oxide particle. More particularly, the invention contemplates the preparation of metal oxide-coated particles and colloidal metal oxide particles that are more particularly a colloidal iron oxide particles.
  • the pH adjustment step is said to be very important and determines the yield of monocrystalline iron oxide particles. If the pH is not adjusted, polycrystalline particles will form.
  • the solution is then optionally sonicated in an ice bath.
  • the sample is centrifuged, then subjected to column fractionation, reverse osmosis or ultrafiltration to remove polycrystalline particles. Pooled fractions are then dialyzed.
  • Barder et al discloses a process for producing microspheres of silica having a uniform size of about 0.1 to 10 microns and a surface coating comprising a metal .
  • the process comprises combining a hydrolyzable silica precursor, such as tetraalkoxy silanes or alkyl alkoxysilances, with alcohol (such as methanol, ethanol , propanol , butanol or pentanol) , ammonia, and water to form two liquid phases.
  • Silica microspheres are formed by the hydrolysis of the silica precursor.
  • a second solution of a soluble compound of at least one metal selected from the group consisting of noble metals, transition metals, rare earth metals and representative metals is added to the solution containing the silica microspheres.
  • the silica microspheres are contacted with the second solution for a period of time sufficient to deposit a coating of soluble metal compounds on the silica microspheres .
  • the coated microspheres are then recovered.
  • Disclosed soluble metal compounds include acetates, alkoxides, carboxylates, nitrates, chlorides and acetylacetonoates of the metals Al , Ti , Cr, Co, Ni, Cu, Y, Zr, Ru, Rh, Pd, Ag, Sn, Pt , Hg, Ce, Pr, Sm, Er, La, Nd and Ta .
  • a surface-coated silica microsphere made by these processes is also disclosed.
  • United States Patent No. 5,648,124 to Sutor discloses a process for preparing magnetically responsive microparticles comprising heterocoagulating electrically charged, magnet responsive material with electrically charged core particles, wherein the electrically charged material and the electrically charged core particles are oppositely charged.
  • the disclosed processes require the use of a polymeric dispersant such as polyacrylic acid, polyethyleneimine and/or polymethacrylic acid.
  • United States Patent No. 4,339,241 to Massart discloses magnetic fluids (ferrofluids) consisting essentially of a surfactant-free aqueous solution of polyoxoanions of Fe(II) and at least one metal with an oxidation degree II selected from transition metals (iron, cobalt, manganese, copper and nickel) .
  • the patent also discloses a method of producing such a magnetic fluid, comprising a base, an amount of the appropriate metal salt to form a gel, subjecting the gel to cation exchange, and separating the thus obtained gel.
  • Paramagnetic and superparamagnetic (magnet responsive) iron oxide particles have been used to separate a variety of biological molecules using magnetic fields.
  • Martin and Mitchell [Analytical Chem . News & Features, 322A-327A (May 1, 1998)] report that superparamagnetic nanoparticles of Fe3 ⁇ 4 of 5 to 100 nm in diameter can be used to separate cells, proteins, or nucleic acid molecules (e.g., DNA or RNA) by selectively binding the biological material of interest to a magnetic particle, then using a magnetic field to separate the bound material from the surrounding matrix.
  • a common application is immunospecific cell separation. Magnetic particles are coated with a monoclonal antibody directed to a cell-specific antigen.
  • the antibody-coated particles are then mixed with a sample containing the cells of interest.
  • the antibody-coated particles bind to the cell- specific antigen, and the cells are collected by exposing the sample to a magnetic field. This technique has been used to separate lymphocytes and tumor cells. Martin and Mitchell, Analytical Chem . News & Features , 322A-327A (May 1, 1998) . Colloidal magnetic dextran iron particles have been used for negative selection of rare cell types. Thomas, T.E., Biomedical Products 10:50-52 (1998) . Tetrameric antibody complexes comprising mouse IgG monoclonal antibodies held together by two rat anti -mouse IgG monoclonal antibodies are used in the assay.
  • mouse antibodies recognizes a cell surface antigen present on most cells but absent on the cells of interest.
  • the other mouse antibody recognizes the dextran portion of the colloidal magnetic dextran iron particle.
  • a cell sample is admixed with the tetrameric antibody complex and magnetic dextran iron particles.
  • the treated sample is then passed through a magnetic field. Unwanted cells are bound by the magnetic field, whereas desired cells pass through to be collected.
  • Metal oxide-coated particles such as MagneSilTM paramagnetic particles (Promega Corp., Madison, WI) comprising a nearly 1:1 ratio of silicon dioxide to magnetite, are used for DNA purification.
  • the MagneSilTM particles bind nucleic acids in solution, and the bound nucleic acids can be separated from the surrounding medium by use of a magnetic field.
  • the invention contemplates a method of preparing metal oxide particles and metal oxide-coated seed particles comprising the following steps.
  • a hydroxyl group-containing solvent composition comprising a solvent-insoluble seed particle having a diameter of about 0.1 ⁇ m to about 10 ⁇ m such as a silica particle, and preferably non- porous silica spheres, and a solvent-soluble metal compound is agitated to form a dispersion of the solvent-insoluble particle in a solution of metal ions.
  • a base is admixed with the dispersion of seed solvent-insoluble particle in a solution of metal ions to provide a metal oxide coating on the particle to thereby form a metal oxide-coated aggregate seed particle suspension.
  • the aggregate particle suspension is agitiated, preferably by sonication, to form a colloid containing metal oxide particles and a precipitate containing metal oxide-coated seed particles. Where only metal oxide-coated seed particles are desired, the agitation step is omitted. These reactions and admixing steps are typically carried out at ambient room temperature and pressure.
  • the metal compound is ferric chloride, ferrous chloride, or a mixture of both. Alternatively, the metal compound is cobaltous acetate.
  • Preferred seed particles are non-porous silica spheres.
  • the base is ammonium hydroxide.
  • the base is ethanolamine .
  • the metal oxide particle is magnet responsive.
  • the metal oxide-coated particle is magnet responsive.
  • the base is admixed with the dispersion at a rate sufficient to provide a black color to the dispersion; in laboratory conditions, that addition takes place over a period of about 2 hours.
  • the base is admixed with the dispersion at a rate sufficient to provide an ochre color to the dispersion; in laboratory conditions, that addition takes place over a period of greater than about 6 hours .
  • the metal oxide-coated seed particle is separated from the metal oxide colloid.
  • a contemplated process comprises the additional step of recovering the metal oxide-coated particles.
  • a process of the invention comprises the additional step of recovering the colloid comprising metal oxide particles. More preferably, both types of particle are recovered. Alternatively, the metal oxide-coated aggregate seed particles are recovered.
  • the present invention contemplates a method for preparing an iron oxide particle and an iron oxide-coated seed particle comprising the following steps.
  • An aqueous composition comprising solvent-insoluble seed particles such as the preferred spherical silica spheres having a diameter of about 0.1 ⁇ m to about 10 ⁇ m and a solvent-soluble iron compound is agitated to form a dispersion of the solvent -insoluble seed particles in a solution of iron ions.
  • a base is admixed with the dispersion of solvent-insoluble seed particles in a solution of iron ions to provide an iron oxide coating on the seed particles to thereby form a iron oxide-coated silica aggregate seed particle suspension.
  • the aggregate seed particle suspension is then agitated, preferably by sonication, to form an aqueous colloid containing iron oxide particles and a precipitate containing iron oxide-coated silica seed particles.
  • the iron oxide-coated particle is then agitated, preferably by sonication, to form an
  • the process comprises the additional step of recovering the iron oxide-coated silica seed particles.
  • the process comprises the further step of recovering the aqueous colloid containing the iron oxide particles. More preferably, both particle types are recovered.
  • the metal oxide-coated aggregate seed particles are recovered.
  • the invention has several benefits and advantages.
  • One advantage is the use of a solid support provides a better and larger surface area for formation of the colloidal particles.
  • One benefit is that the process is simple and efficient .
  • colloidal product particles can be selectively made to be magnet-responsive or non-magnet-responsive .
  • colloidal particles can have different colorific properties.
  • metal oxide particles comprise readily functionalizable surfaces, are highly hydrophilic, contain no organic matrix components, and can bind a variety of molecules using electrostatic forces as well as traditional covalent binding. Still further benefits and advantages of the invention will be apparent to a person of ordinary skill in the art from the description that follows .
  • the invention provides a method of preparing a colloidal metal oxide particle and a metal oxide-coated seed particle.
  • metal oxides include iron oxide (Fe II or Fe III) , cobalt oxide, zirconium oxide, tin oxide, nickel oxide, chromium oxide, platinum oxide, silver oxide, antimony oxide, molybdenum oxide, erbium oxide and manganese oxide.
  • iron oxide particles display magnetic, paramagnetic, or superparamagnetic; i.e., magnet responsive, properties. Conversely, iron oxide can be devoid of magnetic properties.
  • Metal oxide particles can also have a distinctive color.
  • magnet- responsive iron oxides are very dark green-black or brown-black in color
  • magnet -non-responsive iron oxide particles have a reddish ochre color. Nuances of hue aside, those two colors are usually referred to herein as black and ochre, respectively.
  • Cobalt oxide particles have a blue-purple color.
  • Metal oxide particles such as black or ochre iron oxide particles or blue-purple cobalt- containing particles, and metal oxide-coated silica particles can be used as discussed hereinbefore and can also be used as colorific markers for a lateral flow device. Magnetic particles can also be used where ferrofluids are used.
  • colorific metal oxide particles can be bound as by adsorption to an antibody and used in a sandwich-type assay for detection of an analyte antigen bound by the antibody as a complex. The presence of the bound analyte antigen (complex) is confirmed by visualization of the colorific metal oxide particle at a receptor region comprising bound capture moieties that specifically react with the complex.
  • One method of the invention utilizes a hydroxyl -containing solvent composition
  • a hydroxyl -containing solvent composition comprising solvent-insoluble seed particles having a diameter of about 0.1 ⁇ m to about 10 ⁇ m, preferably about 0.5 ⁇ m to about 1.5 ⁇ m, and a solvent-soluble metal compound.
  • a hydroxyl -containing solvent includes water and C1-C3 monohydric alcohols.
  • a preferred hydroxyl -containing solvent is water.
  • Further preferred hydroxyl -containing solvents include ethanol , methanol, n-propanol and isopropanol .
  • Exemplary solvent-insoluble particles include porous and non-porous silica and alumina as well as colloidal metal powders such as powdered iron.
  • Spherical silica particles having a diameter of about 0.1 to about 10 ⁇ m are particularly preferred. Those particles are preferably non-porous. Hydroxyl -containing solvent -insoluble non- porous silica having a diameter of about 0.1 ⁇ m to about 10 ⁇ m useful as seed particles is available from Eichrom Industries, Inc. of Darien, IL and can be prepared as discussed in United States Patent No. 5,196,267 to Barder et al .
  • a solvent-soluble metal compound is typically in the form of a metal salt, such as a metal chloride, metal acetate, metal nitrate, metal carbonate, metal oxalate, metal acetylacetonate and the like.
  • Preferred solvent- soluble metal compounds are ferric chloride, ferrous chloride and cobaltous acetate.
  • the hydroxyl -containing solvent composition comprising solvent-insoluble seed particles and a solvent-soluble metal compound is agitated to form a dispersion of the solvent- insoluble seed particles in a solution of the metal compound. Agitation can be by sonication, shaking, stirring or the like. The agitation is conducted so as to homogeneously disperse the particles and the solvent-soluble metal compound throughout the admixture .
  • a base is then admixed with the dispersion of solvent -insoluble seed particles in a solution of metal compound to provide a metal oxide coating on the seed particles to thereby form a metal oxide- coated aggregate seed particle suspension (dispersion) .
  • a base can be defined as a substance that accepts hydrogen ions, and raises the pH value of the dispersion above pH 7.0, and preferably to about 9 to about 10.
  • Bases are well known in the art, and include sodium hydroxide, potassium hydroxide, calcium hydroxide, methylamine, ethanolamine and the like. Admixture of the base with the suspension provides a metal oxide coating on the particles.
  • a metal oxide-coated aggregate seed particle has a size of about 0.1 ⁇ m to about 10 ⁇ m when the preferred non-porous silica spheres are used.
  • the metal oxide-coated aggregate seed particles are thus present in suspension, and settle when agitation is stopped. It has been surprisingly found that the magnet-responsiveness of iron oxide particles and iron oxide-coated particles can be predicted from the size of the particles and the rate at which the base is added.
  • particles of about 1 ⁇ m to about 10 ⁇ m in size, or larger such as preferred 1.5 ⁇ m to about 10 ⁇ m particles are used and the base is admixed with the dispersion at a rate sufficient to provide a black color to the dispersion.
  • that addition typically takes place over a period of about 2 hours.
  • the total amount of base is added in drop-wise manner so that the entire amount is delivered to the dispersion over a period of about 1.5 to 2.5 hours .
  • the base is admixed with the dispersion at a rate sufficient to provide an ochre color to the dispersion.
  • that addition is typically carried out in a drop-wise manner and takes place over a period of greater than about 6 hours.
  • particles of less than about 1 ⁇ m, and particularly at about 0.5 ⁇ m to about 0.2 ⁇ m, or less, are used, irrespective of the rate of addition of the base, non-magnet-responsive iron oxide particles are produced.
  • This particle suspension is then agitated to form a colloid containing metal oxide particles and a precipitate containing metal oxide-coated seed particles.
  • the admixing can be by sonnication, shaking, or both. Preferably, the admixing is by sonnication. Because of the nanoparticulate nature of the metal oxide particles, those particles are present as a colloid whose particles do not settle out when agitation is stopped, rather than as a settling suspension or dispersion. The metal oxide- coated seed particles, being of larger size, settle out of solution over time, and can be easily recovered upon decanting of the metal oxide particle colloid. The remaining recovered colloid comprises metal oxide particles.
  • metal oxide-coated aggregate seed particles themselves, particularly when seed particles of less than about 1.0 ⁇ m, such as those of about 0.5 ⁇ m to about 0.2 ⁇ m are used.
  • the metal oxide-coated aggregate seed particles are not agitated, but are typically recovered, although they can also be utilized without further recovery as where they are used to adsorb antibodies for use as indicators in assays .
  • Aggregate and metal oxide-coated seed particles are different entities. Aggregate metal oxide-coated seed particles exhibit a rough surface of metal oxide agglomerates, whereas metal oxide- coated seed particles exhibit a smooth surface of metal oxide .
  • a process of the invention is believed to require an excess of solvent-soluble metal compound such that an agglomeration of precipitated metal oxide and metal oxide-coated aggregate seed particles are formed.
  • the agglomeration is then disrupted by agitation, such as by ultrasonication, to release metal oxide- coated particles and a finely dispersed (colloidal) suspension of metal oxide particles.
  • the above process can be conducted using as a starting material a metal oxide- coated seed particle rather than solvent-insoluble uncoated seed particles.
  • the metal oxide-coated seed particles can be coated with a coating of the same metal oxide, or another metal oxide.
  • Such a process can be repeated for multiple rounds, thus adding multiple layers of one or more metal oxides to the surface of the solvent-insoluble seed particles such as silica spheres.
  • the invention further contemplates an in si tu method of preparing metal oxide particles and metal oxide-coated particles.
  • a hydrolyzable silica precursor is admixed with one or more hydroxyl -containing solvents (as discussed before) and a base.
  • a hydrolyzable silica precursor is represented by the formula
  • R ( 4_ n) Si (OR ' ) n where R and R' are each independently a C1-C4 (lower) alkyl group, and n is 2, 3 or 4.
  • Representative hydrolyzable silica precursors include methyltrimethoxysilane, ethyltrimethoxysilane, tetramethoxysilane , tetraethoxysilane , tetrapropoxysilane , tetrabutoxysilane , tetraisopropoxysilane, tetraisobutoxysilane, and tetrasecbutoxysilane .
  • a preferred hydrolyzable silica precursor is tetraethoxysilane.
  • a solution comprising one or more hydroxyl - containing solvents and a base is provided.
  • the hydroxyl -containing solvent comprises a C1-C4 monohydric alcohol and water.
  • a preferred C1-C4 monohydric alcohol is methanol .
  • a preferred base is ammonium hydroxide.
  • the solution is then heated to about 30°C to about 60°C, preferably about 30°C to about 50°C, and more preferably to about 40°C.
  • the hydrolyzable silane is then admixed with the heated solution to form a hydrolysis reaction solution.
  • the hydrolysis reaction solution is agitated for a time period and under temperature and pH conditions sufficient to form a solvent -insoluble spherical silica particle- containing solution.
  • the time period is preferably about 1 to about 3 hours, and more preferably about 1 hour.
  • the temperature conditions are preferably from about 40°C to about 100°C, and more preferably from about 45°C to about 55°C.
  • the pH conditions provide a solution with a pH value of about 5 to about 8, and more preferably a pH value of about 7.
  • the spherical silica particle-containing solution is then admixed with a solvent-soluble metal compound to provide a metal oxide coating on the spherical silica to thereby form a metal oxide-coated aggregate particle suspension.
  • the solvent-soluble metal compound is admixed with water to form a metal ion solution.
  • the metal ion solution is admixed in a drop-wise manner into the silica-containing solution.
  • the metal ion solution is preferably admixed with the silica-containing solution over a time period of about 15 minutes to about 3 hours, and more preferably over a time period of about 30 minutes.
  • additional base is added to the dispersion of silica and metal ions.
  • the metal oxide-coated aggregate particles are themselves typically recovered. Where larger seed particles such as those having diameters of about 1.0 ⁇ m up to about 10 ⁇ m are used, the metal oxide-coated aggregate particles can be recovered and used as such, or those particles can be agitated to form colloidal metal oxide particles and metal oxide- coated seed particles. In that latter instance, the metal oxide-coated aggregate particle suspension discussed before is then agitated as by sonication to provide metal oxide-coated seed particles and a colloid of metal oxide particles.
  • United States Patent No. 5,196,267 does not disclose the use of iron oxide in the processes described, nor is the preparation of a colloid comprising a metal oxide described. Moreover, the method described therein does not disclose admixing a base with a dispersion of solvent -insoluble porous or non-porous spherical silica particles in a solution of metal ions to provide a metal oxide coating on the spherical silica to form a metal oxide-coated aggregate particle suspension, and thereafter, a metal oxide-coated particle suspension and a metal oxide particle-containing colloid. Still further, those disclosed processes do not teach the preparation of a magnet responsive metal oxide particles .
  • the present invention provides a method of preparing metal oxide particles and metal oxide-coated particles by admixing solvent- insoluble seed particles such as silica spheres with a solvent-soluble metal compound.
  • a base is added at ambient room temperature.
  • the rate of addition of the base determines whether the resulting metal oxide particle metal oxide-coated seed particle is magnet-responsive or non-magnet -responsive .
  • Metal oxide-coated aggregate particles are recovered, and the metal oxide-coated aggregate particles are agitated to form a colloid of metal oxide particles and metal oxide-coated silica seed particles.
  • the method does not require excess heat, excess cooling, ultracentrifugation, column separation, ultraconcentration, reverse osmosis, diafiltration, ultrafiltration, dialysis or the use of dispersants.
  • the present invention provides a method that is efficient and economical. The following examples are offered to further illustrate, but not limit, the present invention.
  • Example 1 Preparation of Colloidal Iron Particles
  • Ten grams of processed non-porous silica, 1.5 ⁇ 0.5 ⁇ m in size (Eichrom Industries Inc., Darien, IL) were suspended in 250 mL distilled water.
  • Ferric chloride FeCl3-6H2 ⁇ ; 2.9 grams
  • the dispersion was poured into a 5 L beaker and the volume increased to 2 L with distilled water.
  • Ferrous chloride (FeCl2-4H2 ⁇ ; 4.3 grams) was dissolved in 250 mL distilled water and added to the ferric ion/non- porous silica dispersion.
  • the dispersion was stirred at 300 revolutions per minute using an A-310 impeller blade and a Cole-Parmer overhead stirrer.
  • the final wash was permitted to settle overnight (16 hours) , and the water decanted.
  • the precipitated metal oxide-coated aggregate silica particles were placed in a 500 mL polypropylene bottle along with 200 mL of distilled water and sonicated for 40 to 60 minutes with intermittent shaking. The resulting suspension was permitted to settle over several days.
  • a dark magnet -responsive mother liquor containing colloidal iron oxide particles was decanted from light brown magnet- responsive iron oxide-coated non-porous silica particles. The iron oxide-coated particles were washed three times in 250 mL distilled water.
  • Example 2 Preparation of Colloidal Iron Particles Ten grams of processed non-porous silica,
  • the suspension was decanted and the precipitated, solid, metal oxide-coated aggregate silica particles were washed three times with 2 L distilled water.
  • the final wash-containing solid was permitted to settle overnight (16 hours) , and the water decanted.
  • the precipitated solid was placed in a 500 mL polypropylene bottle along with 200 mL of distilled water and sonicated for 40 to 60 minutes with intermittent shaking.
  • the resulting suspension was permitted to settle over several days.
  • An ochre colored mother liquor containing colloidal iron oxide particles was decanted from yellow, iron oxide-coated non-porous silica particles.
  • the yellow iron oxide- coated particles were washed three times in 250 mL distilled water and were not magnet-responsive .
  • the stirring rate was then increased to 300 revolutions per minute, and a solution of 2.0 grams of cobaltous (Co (II)) acetate -4 H2O dissolved in 200 mL distilled water was prepared. This cobaltous acetate solution was then added to the suspension in drop-wise manner over a period of about 30 minutes.
  • 5.0 mL ethanolamine dissolved in 50 mL distilled water was also added to the suspension. The resulting blue- purple suspension was removed from the heat and permitted to settle. The supernate was decanted and discarded, and the cobalt oxide-coated aggregate silica particles were washed three times in 2L distilled water.
  • Example 4 Preparation of Magnet-non-responsive Iron Oxide-coated Silica Particles Methanol (1.5 L) , 250 mL distilled water and 230 mL concentrated ammonium hydroxide were mixed in a 4 L glass beaker. Using an A-310 impeller blade and a Cole-Parmer overhead stirrer, the mixture was stirred at 150 revolutions per minute. The mixture was then heated to 40°C, and 100 mL of tetraethoxide silane (TEOS) were added. The solution was permitted to stir for 1 hour at room temperature (about 22°C) . The composition was sampled, and the silica particles produced were found to have diameters of about 200 nm.
  • TEOS tetraethoxide silane
  • the stirring rate was then increased to 300 revolutions per minute, and the solution heated to 90°C with intermittent addition of distilled water to maintain a total volume of between 2.0 and 2.5 L.
  • the pH value of the solution was monitored and the suspension was permitted to cool to 40°C when the pH value was about 7.0.
  • About one-third of the volume of the composition was removed and placed into a 5 L flask and the volume brought to about 2 L with distilled water.
  • Ferric chloride FeCl3"6H2 ⁇ ; 2.9 grams
  • Ferrous chloride (FeCl2 • 4H2O ; 4.3 grams) was dissolved in 250 mL distilled water and added to the ferric chloride/ spherical silica dispersion. The dispersion was stirred at 300 revolutions per minute using an A-310 impeller blade and a Cole-Parmer overhead stirrer.
  • the suspension was decanted and the precipitated solid of metal oxide-coated aggregate silica particles was washed three times with 2 L distilled water. The final wash was permitted to settle overnight (16 hours) , and the water decanted. Reddish-ochre non-magnet -responsive iron oxide-coated spherical silica particles were recovered. The iron oxide-coated particles were washed three times in 250 mL distilled water.
  • Example 5 Procedure for making Colloidal and Coated Composite Particles 1. Suspend 10 g of processed 1.5 ⁇ 0.1 ⁇ m non-porous silica (NPS) particles in 250 ml of distilled water.
  • NPS non-porous silica
  • the suspension progresses in color from yellow to orange-brown to dark green-black.
  • the suspension is stirred at 150 rpm for 30 minutes after complete NH 4 OH addition.
  • the resulting 1.5 ⁇ m diameter particles are a composite of a solid silica core with a metal (iron) oxide coating.

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  • Crystallography & Structural Chemistry (AREA)
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  • Oxygen, Ozone, And Oxides In General (AREA)
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Abstract

Cette invention concerne un procédé d'obtention de particules d'oxyde métallique colloïdal et de particules de silice recouvertes d'oxyde métallique. Ce procédé consiste à agiter une composition aqueuse comprenant un matériau de particules germes insolubles par solvant d'un diamètre compris entre 0,1 νm et 10 νm environ et un composé métallique soluble par solvant pour obtenir une dispersion du matériau de particules germes insoluble par solvant et des ions métalliques solubles par solvant. On ajoute une base à la dispersion de manière déposer un revêtement d'oxyde métallique sur le matériau de particules germes insoluble par solvant et, par là même, former une suspension de particules germes agrégées à revêtement d'oxyde métallique. En général, on agite la suspension de particules de manière à former des particules germes à revêtement d'oxyde métallique et des particules d'oxyde métallique renfermant un colloïde, récupérées sans agitation ou utilisées telles quelles.
PCT/US2000/040848 1999-09-09 2000-09-08 Procede d'obtention de particules d'oxyde metallique WO2001017667A1 (fr)

Priority Applications (1)

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AU11068/01A AU1106801A (en) 1999-09-09 2000-09-08 Method of preparing metal oxide particles

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US15297599P 1999-09-09 1999-09-09
US60/152,975 1999-09-09
US65677300A 2000-09-07 2000-09-07
US09/656,773 2000-09-07

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8674163B2 (en) 2003-05-29 2014-03-18 Canon Kabushiki Kaisha DNA hybrids and environment cleaning system employing DNA hybrids
US10350933B2 (en) 2007-06-05 2019-07-16 Bank Of Canada Ink or toner compositions, methods of use, and products derived therefrom
CN113800476A (zh) * 2021-08-30 2021-12-17 宁波工程学院 一种纳米金属氧化物的超声制备方法

Citations (7)

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Publication number Priority date Publication date Assignee Title
US3005724A (en) * 1959-02-16 1961-10-24 Harshaw Chem Corp Iron-silica ceramic stain
US3042543A (en) * 1960-11-07 1962-07-03 Franklin Inst Of The State Of Magnetic particles and method of making same
US4613454A (en) * 1983-06-30 1986-09-23 Nalco Chemical Company Metal oxide/silica sols
US4675251A (en) * 1985-02-20 1987-06-23 Montedison S.P.A. Spherical particles of titanium dioxide coated with a uniform layer of iron oxides having a narrow size distribution, and process for preparing the same
JPS6320367A (ja) * 1986-07-11 1988-01-28 Ube Ind Ltd 赤色複合顔料
US5196267A (en) * 1991-06-21 1993-03-23 Allied-Signal Inc. Process for coating silica spheres
JPH05294626A (ja) * 1992-04-17 1993-11-09 Kanto Denka Kogyo Co Ltd 白色磁性粉末及びその製造方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3005724A (en) * 1959-02-16 1961-10-24 Harshaw Chem Corp Iron-silica ceramic stain
US3042543A (en) * 1960-11-07 1962-07-03 Franklin Inst Of The State Of Magnetic particles and method of making same
US4613454A (en) * 1983-06-30 1986-09-23 Nalco Chemical Company Metal oxide/silica sols
US4675251A (en) * 1985-02-20 1987-06-23 Montedison S.P.A. Spherical particles of titanium dioxide coated with a uniform layer of iron oxides having a narrow size distribution, and process for preparing the same
JPS6320367A (ja) * 1986-07-11 1988-01-28 Ube Ind Ltd 赤色複合顔料
US5196267A (en) * 1991-06-21 1993-03-23 Allied-Signal Inc. Process for coating silica spheres
JPH05294626A (ja) * 1992-04-17 1993-11-09 Kanto Denka Kogyo Co Ltd 白色磁性粉末及びその製造方法

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8674163B2 (en) 2003-05-29 2014-03-18 Canon Kabushiki Kaisha DNA hybrids and environment cleaning system employing DNA hybrids
US10350933B2 (en) 2007-06-05 2019-07-16 Bank Of Canada Ink or toner compositions, methods of use, and products derived therefrom
CN113800476A (zh) * 2021-08-30 2021-12-17 宁波工程学院 一种纳米金属氧化物的超声制备方法
CN113800476B (zh) * 2021-08-30 2023-09-12 宁波工程学院 一种纳米金属氧化物的超声制备方法

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AU1106801A (en) 2001-04-10

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