WO2012053990A2 - Method for the preparation of carrier colloidal powder with high specific surface area - Google Patents

Method for the preparation of carrier colloidal powder with high specific surface area Download PDF

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WO2012053990A2
WO2012053990A2 PCT/SI2011/000059 SI2011000059W WO2012053990A2 WO 2012053990 A2 WO2012053990 A2 WO 2012053990A2 SI 2011000059 W SI2011000059 W SI 2011000059W WO 2012053990 A2 WO2012053990 A2 WO 2012053990A2
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powder
ain
surface area
carrier
specific surface
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PCT/SI2011/000059
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French (fr)
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WO2012053990A3 (en
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Aleš DAKSKOBLER
Andraž KOCJAN
Manca Logar
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Institut Jožef Stefan
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Priority claimed from SI201000330A external-priority patent/SI23502A/en
Priority claimed from SI201000433A external-priority patent/SI23580A/en
Application filed by Institut Jožef Stefan filed Critical Institut Jožef Stefan
Publication of WO2012053990A2 publication Critical patent/WO2012053990A2/en
Publication of WO2012053990A3 publication Critical patent/WO2012053990A3/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/063—Titanium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
    • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/39—Photocatalytic properties
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/30—Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/44—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water
    • C01F7/441—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area

Definitions

  • the subject of the invention is a method for the preparation of carrier colloidal powder with high specific surface area by hydrolysis of aluminium nitride AIN in a water suspension or in a water containing suspension, where AIN particles convert into agglomerates of aggregated porous particles from aluminium oxy-hydroxide AIOOH with high specific surface area.
  • AIOOH converts into one of transitional forms of aluminium oxide AI2O3 without any considerable change in powder morphology.
  • Carrier colloidal powder is intended to enhance the efficiency and properties of films and/or nanoparticles that exhibit specific or improved properties (e. g. optical, electric, magnetic, chemical) and can be applied onto carrier powder by chemical and/or physical synthesis techniques.
  • a need for the preparation of composite colloidal particles occurred with the research of materials of nanometre dimensions, when the particle diameter is smaller than 20 nm, which exhibit specific or enhanced properties, e. g. optical, electric, magnetic, chemical, which are function of their size, composition and structure (L. M. Liz-Marzan, M. Giersig, P. Mulvaney. Synthesis of nanosized gold-silica core-shell particles. Langmuir, 1996, 12, 4329-4335).
  • Agglomeration can be prevented in various ways, e. g. by stabilising nanoparticles in a dispersion medium, wherein we must always start from suspensions.
  • the stability of a suspension of these particles is very sensitive to the properties of the dispersion medium, as various factors, like temperature and pH of the medium can change the interaction force particle-particle from reflexive to attracting, which consequently leads to agglomeration of nanopartlcles and to the loss of the properties they had due to their small size.
  • a preparation of composite colloidal particles makes it easier to handle nanopartlcles attached to the surface of carrier colloidal particles.
  • Such composite colloidal particles exhibit the properties of attached nanopartlcles and what's more they are potentially useful and applicable on a large scale. They can be used as fundamental elements of arranged (photonic crystals) and/or complex materials for the preparation of layers or can be used as individual particles in cases like catalysis, photocatalysis, diagnosing etc. (N. Chu, J. Wang, Y. Zhang, J. Yang, J. Lu, D. Yin. Nestlike Hollow Hierarchical MCM-22 Microspheres: Synthesis and Exceptional Catalytic Properties. Chem. Mater., 2010, 120, 590).
  • the specific surface area of the carrier powder is very small, the share of nanoparticles on the surface of carrier colloidal particles compared to the whole particle is very small, so the effect of nanoparticles can be neglected, since the specific surface area of the carrier powder, for instance spherical particles of aluminium oxide with a density 4 g/cm 3 and particle size 1 to 10 ⁇ is too small and amounts merely 1.5- 0.15 m 2 /g.
  • a problem that has remained unsolved is preparation of carrier powders having a dimension 1 to 10 ⁇ with a large specific surface, i. e. S > 100 m 2 /g, onto the surface of which a thin layer is applied by the so-called engineering of particle surfaces or nanoparticles of sizes d ⁇ 20 nm are attached, which will combine the advantages of attached nanoparticles on the surface of carrier colloidal particles and simplify the use of such composite colloidal powder. Due to a very large specific surface area and porosity of the carrier particles certain properties of nanoparticles that they exhibit due to their small size in comparison with the use of nanoparticles as such are preserved or even increased, which makes the handling of such composite colloidal particles very simple. We have not found any data in literature about the powders of dimensions between 1-10 ⁇ with a very large specific surface area 5 > 100 m 2 /g, onto the surface of which nanoparticles would be applied.
  • the task and goal of the invention is a simple method for the preparation of carrier powder consisting of colloidal particles of AIOOH or AI2O3 of dimensions from 0.1 to 20 ⁇ that will have a surface area exceeding 100 m 2 /g. Due to the high specific surface area and porosity of the carrier powder it will be possible to apply a large quantity of nanoparticles thereon. In this way the density of nanoparticle package is preserved or even increased with respect to their volume in comparison with the density of the package of nanoparticles themselves. The property of nanoparticles is thus preserved and due to a simple access to the surface of an individual nanoparticle the total efficiency of the composite colloidal particles could even be increased compared to nanoparticles.
  • the dimensions of used carrier colloidal particles will allow a simple use of composite colloidal particles, like dispersion in water or water containing medium and their separation after use.
  • the task of the invention is solved by a synthesis of the carrier colloidal powder with a large specific surface area by the independent claims.
  • Carrier colloidal powder of dimensions 0.5 ⁇ to 10 ⁇ with a high specific surface area (5 > 100 m 2 /g) consisting of agglomerates of aggregated porous particles of AIOOH or one of transitional forms AI2O3 ( ⁇ -, ⁇ -, ⁇ - ⁇ 2 ⁇ 3) is synthetized by a hydrolysis of AIN, wherein the AIN powder with an average particle size from 0.1 nm to 10 ⁇ is dispersed into water or a liquid water containing medium, the starting pH of which amounts to 4 to 12 in the temperature range from 70 °C to 100 °C under atmospheric pressure or increased pressures, i. e.
  • the mass share of AIN powder in the water or water containing medium is from 1 % to 10 %
  • the carrier powder is formed by a reaction of the AIN particle surface and water, where AIN decomposes and the AIOOH particles crystallize on its surface, said particles having a thickness of 3 nm, length and height from 100 nm to 300 nm and then within a period of 20 minutes to 1 hour the suspension of AIOOH powder is filtered with or without the share of non-reacted AIN.
  • the suspension is then washed, dried for 2 hours at 90 °C and the carrier powder is subsequently subjected to thermal treatment at 700 °C to 1000 °C for dehydration of AIOOH into one of transitional forms of AI2O3.
  • Example Carrier colloidal powder ⁇ - ⁇ 1 2 03 with a specific surface area of 200.4 m 2 /g was used as carrier powder.
  • 10 g of the A1N powder with an average particle size of 2 ⁇ was dispersed in 250 ml of distilled water with a temperature of 70 °C and pH value 5.5. The pH value of the suspension increased after 50 minutes to 9.5.
  • the suspension was then filtered, washed with 2-propanole and the obtained A100H carrier powder was dried for 2 hours in a drier at 100 °C. After the drying, the carrier powder was thermally treated by heating in an electric resistance oven in the air at a temperature of 700 °C with a heating rate 10 °C/min.
  • the heating time at the indicated temperature was 1 hour, wherein conversion of AIOOH to ⁇ - ⁇ 1 2 03 was carried out without any significant change in the morphology of the colloidal powder.
  • the Ti0 2 particles were applied, that have a photocatalysis capability, by way of polyelectrolyte matrix.
  • the matrix was prepared by means of self-arrangement of polyelectrolytes from a water solution having pH 3, into which the carrier powder ⁇ - AI2O3 was dispersed.
  • a multi-layer polyelectrolyte matrix was formed on the surface of the carrier powder that has a positive surface charge at that pH by consecutive application of oppositely charged polyelectrolytes from the water solution on the basis of electrostatic attraction.
  • PAH, M 70000 g/mol
  • PAA, M 90000 g/mol
  • the carrier powder with the negatively charged surface was first dispersed in the solution of polyanion PAA (10 2 mol/l) within a period from 10 to 20 min, centrifugated, washed well with deionized water and then dispersed in a solution of the polycation PAH (10 2 mol/l) in the same time interval. Adsorption of the polyelectrolyte and washing with deionized water was cyclically repeated for 6 times.
  • This process produces a multi-layer polymeric matrix with a thickness mostly 20 nm on the surface of ⁇ - ⁇ 1 2 03 particles.
  • the carrier colloidal powder so prepared and coated with a thin layer of polyelectrolytes was then exposed for 15 minutes to a solution of titanium 2- propoxide in 2-propanole (volume ratio 1 : 10) in inert atmosphere.
  • the composite powder was then dried for one hour at 50 °C. After one hour of thermal treatment at 500 °C with a heating rate 2 °C/min in the air a thin coating of Ti0 2 was formed that contained nanocrystalline particles of up to 10 nm on the surface of the carrier powder ⁇ - ⁇ 1 2 0 3 .
  • the absorption maximum shifts to lower wavelengths due to the synthesis of nanocrystalline Ti0 2 particles on the surface of the carrier colloidal powder ⁇ - ⁇ 1 2 03 in comparison with the volume Ti0 2 .
  • the composite colloidal powder exhibits 2.7-times better photocatalytic decomposition of organic substances as measured on the model experiment of decomposition of the colouring methylene blue.
  • the method for the preparation of carrier colloidal powder with high specific surface area of the invention is characterized in that the carrier colloidal powder is produced by exploiting hydrolysis of the aluminium nitride (AIN) powder, wherein the AIN powder having an average particle size from 20 nm to 100 ⁇ , preferably from 0.5 ⁇ to 10 ⁇ is dispersed in water or a liquid water containing medium with the initial pH value from 1 to 14, preferably from pH 4 to 12 in the temperature range between 5 °C and 374 °C, preferably between 70 °C and 100 °C, at atmospheric pressure and increased pressures, i. e.
  • AIN aluminium nitride
  • the mass share of the AIN powder in water or a water containing medium is from 0.1 % to 50 %, preferably from 1 % to 10 %, wherein the carrier powder is obtained by reacting the surface of the AIN particle and water, where AIN decomposes and on its decomposing surface porous particles crystallize that form the AIOOH lamellas of a thickness of 1 nm to 10 nm, preferably 3 nm, of length and height from 50 nm to 800 nm, preferably from 200 nm to 300 nm.
  • the suspension of the AIOOH powder with or without the share of unreacted AIN, preferably without the AIN share is filtered and dried.
  • the carrier colloidal powder is subjected to thermal treatment from 200 °C to 1200 °C, preferably from 700 °C to 1000 °C.
  • the obtained powder consists of aluminium oxyhydroxide AIOOH (or of one of transitional forms of aluminium oxide ⁇ -, ⁇ -, ⁇ - ⁇ 2 ⁇ 3) with high specific surface area and particle size from 0.1 ⁇ to 20 ⁇ , preferably from 1 ⁇ to 10 ⁇ .
  • a thin layer and/or nanoparticles are applied, preferably nanoparticles.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
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  • Inorganic Chemistry (AREA)
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Abstract

The subject of the invention is a method for the preparation of carrier colloidal powder with high specific surface area for application of a thin layer and/or nanoparticles. Due to a very large specific surface area and porosity of the carrier particles certain properties of nanoparticles that they exhibit due to their small size are preserved or even increased in comparison with the use of nanoparticles as such. Handling the so prepared composite colloidal particles with an increased specific surface area is very simple. The carrier powder is produced by exploiting hydrolysis of the AIN powder, wherein during a reaction between AIN and water the decomposed AIN particles are replaced by a number of agglomerates of porous particles from AIOOH with a high specific surface area that can be subsequently thermally treated in order to obtain the particles from one of the transitional forms of AI2O3, i. e. γ-, δ- or θ-ΑΙ2Ο3, without any significant change in the morphology of the particles.

Description

METHOD FOR THE PREPARATION OF CARRIER COLLOIDAL POWDER WITH HIGH SPECIFIC SURFACE AREA
The subject of the invention is a method for the preparation of carrier colloidal powder with high specific surface area by hydrolysis of aluminium nitride AIN in a water suspension or in a water containing suspension, where AIN particles convert into agglomerates of aggregated porous particles from aluminium oxy-hydroxide AIOOH with high specific surface area. When the powder so prepared is subsequently thermally treated, AIOOH converts into one of transitional forms of aluminium oxide AI2O3 without any considerable change in powder morphology. Carrier colloidal powder is intended to enhance the efficiency and properties of films and/or nanoparticles that exhibit specific or improved properties (e. g. optical, electric, magnetic, chemical) and can be applied onto carrier powder by chemical and/or physical synthesis techniques.
Much research work has lately been aimed at the preparation of composite colloidal particles, the so-called »core-shell« particles, or the engineering of particle surfaces [R. Davies, G. A. Schurr, P. Meenan, R. D. Nelson, H. E. Bergna, C. A. S. Brevett and R. H. Goldbaum. Engineered particle surfaces. Adv. Mater., 1998, 10, 1264-1270). Engineering of particle surfaces normally comprises planning of the properties of the surface of carrier colloidal particles, which is achieved by applying coatings and/or particles of a desired material onto the surface of the carrier colloidal particles.
A need for the preparation of composite colloidal particles occurred with the research of materials of nanometre dimensions, when the particle diameter is smaller than 20 nm, which exhibit specific or enhanced properties, e. g. optical, electric, magnetic, chemical, which are function of their size, composition and structure (L. M. Liz-Marzan, M. Giersig, P. Mulvaney. Synthesis of nanosized gold-silica core-shell particles. Langmuir, 1996, 12, 4329-4335).
A high ratio between the surface and the volume of nanoparticles leads to agglomeration. Agglomeration can be prevented in various ways, e. g. by stabilising nanoparticles in a dispersion medium, wherein we must always start from suspensions. The stability of a suspension of these particles is very sensitive to the properties of the dispersion medium, as various factors, like temperature and pH of the medium can change the interaction force particle-particle from reflexive to attracting, which consequently leads to agglomeration of nanopartlcles and to the loss of the properties they had due to their small size. Handling of such particles is at the same time limited only to stable suspensions, wherein interaction forces among the particles in the medium are reflexive, as handling the nanopartlcles is difficult and their re-dispersion is very demanding and even impossible in a majority of cases (S. Vesaratchanon, A. Nikolov, D. T. Wasan. Sedimentation in nano-colloidal dispersions: Effects of collective interactions and particle charge. Adv. colloid interface sci., 2007, 134-135, 268-278).
A preparation of composite colloidal particles makes it easier to handle nanopartlcles attached to the surface of carrier colloidal particles. Such composite colloidal particles exhibit the properties of attached nanopartlcles and what's more they are potentially useful and applicable on a large scale. They can be used as fundamental elements of arranged (photonic crystals) and/or complex materials for the preparation of layers or can be used as individual particles in cases like catalysis, photocatalysis, diagnosing etc. (N. Chu, J. Wang, Y. Zhang, J. Yang, J. Lu, D. Yin. Nestlike Hollow Hierarchical MCM-22 Microspheres: Synthesis and Exceptional Catalytic Properties. Chem. Mater., 2010, 120, 590).
One of disadvantages of use of composite colloidal particles in photocatalysis for instance is low specific surface area of carrier colloidal particles. Particles of simple, especially isometric shapes are normally used (particles of round and oblong shapes), the specific surface area of which depends on their size (M. Ohmori, E. Matijevic. Preparation and properties of uniform coated inorganic colloidal particles. J. Colloid Interface Sci., 1993, 160, 288-292). By reducing the size of carrier colloidal particles, which are covered with nanopartlcles, their specific surface area is extended, yet they become even more demanding for handling and they are difficult to recycle after the completed use. So there is a tendency for larger particles (d > 0.1 μπι), which make handling easier in comparison with nanometre sized particles [d < 20 nm). The increased dimension of carrier colloidal particles makes handling the suspensions of these particles easier. In case of particles sized 1 to 10 μηι, separation of composite colloidal particles from the dispersion medium after use is very simple, as electrostatic interactions among the particles in the suspension get negligible, because these particles are at the upper limit of colloidal particles. In this way a colloidal powder is obtained that is simple to handle and exhibits the properties of nanoparticles on the surface (the so- called shell material). As the specific surface area of the carrier powder is very small, the share of nanoparticles on the surface of carrier colloidal particles compared to the whole particle is very small, so the effect of nanoparticles can be neglected, since the specific surface area of the carrier powder, for instance spherical particles of aluminium oxide with a density 4 g/cm3 and particle size 1 to 10 μηι is too small and amounts merely 1.5- 0.15 m2/g.
A problem that has remained unsolved is preparation of carrier powders having a dimension 1 to 10 μπι with a large specific surface, i. e. S > 100 m2/g, onto the surface of which a thin layer is applied by the so-called engineering of particle surfaces or nanoparticles of sizes d < 20 nm are attached, which will combine the advantages of attached nanoparticles on the surface of carrier colloidal particles and simplify the use of such composite colloidal powder. Due to a very large specific surface area and porosity of the carrier particles certain properties of nanoparticles that they exhibit due to their small size in comparison with the use of nanoparticles as such are preserved or even increased, which makes the handling of such composite colloidal particles very simple. We have not found any data in literature about the powders of dimensions between 1-10 μπι with a very large specific surface area 5 > 100 m2/g, onto the surface of which nanoparticles would be applied.
The task and goal of the invention is a simple method for the preparation of carrier powder consisting of colloidal particles of AIOOH or AI2O3 of dimensions from 0.1 to 20 μπι that will have a surface area exceeding 100 m2/g. Due to the high specific surface area and porosity of the carrier powder it will be possible to apply a large quantity of nanoparticles thereon. In this way the density of nanoparticle package is preserved or even increased with respect to their volume in comparison with the density of the package of nanoparticles themselves. The property of nanoparticles is thus preserved and due to a simple access to the surface of an individual nanoparticle the total efficiency of the composite colloidal particles could even be increased compared to nanoparticles. The dimensions of used carrier colloidal particles will allow a simple use of composite colloidal particles, like dispersion in water or water containing medium and their separation after use.
The task of the invention is solved by a synthesis of the carrier colloidal powder with a large specific surface area by the independent claims.
Carrier colloidal powder of dimensions 0.5 μπι to 10 μπι with a high specific surface area (5 > 100 m2/g) consisting of agglomerates of aggregated porous particles of AIOOH or one of transitional forms AI2O3 (γ-, δ-, Θ-ΑΙ2Ο3) is synthetized by a hydrolysis of AIN, wherein the AIN powder with an average particle size from 0.1 nm to 10 μπι is dispersed into water or a liquid water containing medium, the starting pH of which amounts to 4 to 12 in the temperature range from 70 °C to 100 °C under atmospheric pressure or increased pressures, i. e. hydrothermally until supercritical water conditions, wherein the mass share of AIN powder in the water or water containing medium is from 1 % to 10 %, wherein the carrier powder is formed by a reaction of the AIN particle surface and water, where AIN decomposes and the AIOOH particles crystallize on its surface, said particles having a thickness of 3 nm, length and height from 100 nm to 300 nm and then within a period of 20 minutes to 1 hour the suspension of AIOOH powder is filtered with or without the share of non-reacted AIN. The suspension is then washed, dried for 2 hours at 90 °C and the carrier powder is subsequently subjected to thermal treatment at 700 °C to 1000 °C for dehydration of AIOOH into one of transitional forms of AI2O3.
The invention will be described in more detail in the continuation on the basis of an example.
Example Carrier colloidal powder γ-Α1203 with a specific surface area of 200.4 m2/g was used as carrier powder. 10 g of the A1N powder with an average particle size of 2 μηι was dispersed in 250 ml of distilled water with a temperature of 70 °C and pH value 5.5. The pH value of the suspension increased after 50 minutes to 9.5. The suspension was then filtered, washed with 2-propanole and the obtained A100H carrier powder was dried for 2 hours in a drier at 100 °C. After the drying, the carrier powder was thermally treated by heating in an electric resistance oven in the air at a temperature of 700 °C with a heating rate 10 °C/min. The heating time at the indicated temperature was 1 hour, wherein conversion of AIOOH to γ-Α1203 was carried out without any significant change in the morphology of the colloidal powder. Onto the carrier colloidal powder so prepared the Ti02 particles were applied, that have a photocatalysis capability, by way of polyelectrolyte matrix. The matrix was prepared by means of self-arrangement of polyelectrolytes from a water solution having pH 3, into which the carrier powder γ- AI2O3 was dispersed. A multi-layer polyelectrolyte matrix was formed on the surface of the carrier powder that has a positive surface charge at that pH by consecutive application of oppositely charged polyelectrolytes from the water solution on the basis of electrostatic attraction. In the formation of the multi-layer polyelectrolyte matrix on the surface of carrier particles γ-Α1203 polyallylaminehydrochloride (PAH, M = 70000 g/mol) was used as polycation and polyacrylic acid (PAA, M = 90000 g/mol) was used as polyanion. The carrier powder with the negatively charged surface was first dispersed in the solution of polyanion PAA (10 2 mol/l) within a period from 10 to 20 min, centrifugated, washed well with deionized water and then dispersed in a solution of the polycation PAH (10 2 mol/l) in the same time interval. Adsorption of the polyelectrolyte and washing with deionized water was cyclically repeated for 6 times. This process produces a multi-layer polymeric matrix with a thickness mostly 20 nm on the surface of γ-Α1203 particles. The carrier colloidal powder so prepared and coated with a thin layer of polyelectrolytes was then exposed for 15 minutes to a solution of titanium 2- propoxide in 2-propanole (volume ratio 1 : 10) in inert atmosphere. The composite powder was then dried for one hour at 50 °C. After one hour of thermal treatment at 500 °C with a heating rate 2 °C/min in the air a thin coating of Ti02 was formed that contained nanocrystalline particles of up to 10 nm on the surface of the carrier powder γ-Α1203. Based on the quantum efficiency the absorption maximum shifts to lower wavelengths due to the synthesis of nanocrystalline Ti02 particles on the surface of the carrier colloidal powder γ-Α1203 in comparison with the volume Ti02. In comparison with the volume Ti02 (equal quantity of powder sized 10 nm), the composite colloidal powder exhibits 2.7-times better photocatalytic decomposition of organic substances as measured on the model experiment of decomposition of the colouring methylene blue.
The method for the preparation of carrier colloidal powder with high specific surface area of the invention is characterized in that the carrier colloidal powder is produced by exploiting hydrolysis of the aluminium nitride (AIN) powder, wherein the AIN powder having an average particle size from 20 nm to 100 μπι, preferably from 0.5 μπι to 10 μη is dispersed in water or a liquid water containing medium with the initial pH value from 1 to 14, preferably from pH 4 to 12 in the temperature range between 5 °C and 374 °C, preferably between 70 °C and 100 °C, at atmospheric pressure and increased pressures, i. e. hydrothermal to supercritical water conditions, preferably at atmospheric pressure, wherein the mass share of the AIN powder in water or a water containing medium is from 0.1 % to 50 %, preferably from 1 % to 10 %, wherein the carrier powder is obtained by reacting the surface of the AIN particle and water, where AIN decomposes and on its decomposing surface porous particles crystallize that form the AIOOH lamellas of a thickness of 1 nm to 10 nm, preferably 3 nm, of length and height from 50 nm to 800 nm, preferably from 200 nm to 300 nm. The suspension of the AIOOH powder with or without the share of unreacted AIN, preferably without the AIN share, is filtered and dried. To achieve dehydration of AIOOH into one of transitional forms of Α12θ3 γ-, δ-, θ- Α12θ3 the carrier colloidal powder is subjected to thermal treatment from 200 °C to 1200 °C, preferably from 700 °C to 1000 °C. The obtained powder consists of aluminium oxyhydroxide AIOOH (or of one of transitional forms of aluminium oxide γ-, δ-, Θ-ΑΙ2Ο3) with high specific surface area and particle size from 0.1 μπι to 20 μπι, preferably from 1 μηι to 10 μπι. Onto the surface of this powder a thin layer and/or nanoparticles are applied, preferably nanoparticles.

Claims

CLAI S
1. Method for the preparation of carrier colloidal powder with high specific surface area characterized in that the carrier colloidal powder is produced by exploiting hydrolysis of the aluminium nitride (AIN) powder, wherein the AIN powder having an average particle size from 20 nm to 100 μπι, preferably from 0.5 μηι to 10 μπι is dispersed in water or a liquid water containing medium with the initial pH value from 1 to 14, preferably from pH 4 to 12 in the temperature range between 5 °C and 374 °C, preferably between 70 °C and 100 °C, at atmospheric pressure and increased pressures,
1. e. hydrothermal to supercritical water conditions, preferably at atmospheric pressure, wherein the mass share of the AIN powder in water or a water containing medium is from 0.1 % to 50 %, preferably from 1 % to 10 %, wherein the carrier powder is obtained by reacting the surface of the AIN particle and water, where AIN decomposes and on its decomposing surface porous particles crystallize that form the AIOOH lamellas of a thickness of 1 nm to 10 nm, preferably 3 nm, of length and height from 50 nm to 800 nm, preferably from 200 nm to 300 nm, whereafter the suspension of the AIOOH powder with or without the share of unreacted AIN, preferably without the AIN share, is filtered and dried.
2. Method for the preparation of carrier colloidal powder with high specific surface area obtained by the method of claim 1, characterized in that to achieve dehydration of AIOOH into one of transitional forms of AI2O3 γ-, δ-, Θ-ΑΙ2Ο3 the carrier colloidal powder is subjected to thermal treatment from 200 °C to 1200 °C, preferably from 700 °C to 1000 °C.
3. Method for the preparation of carrier colloidal powder with high specific surface area obtained by the method of claims 1 and 2, characterized in that the obtained powder consists of aluminium oxyhydroxide AIOOH (or of one of transitional forms of aluminium oxide γ-, δ-, Θ-ΑΙ2Ο3) with high specific surface area and particle size from 0.1 μηι to 20 μπι, preferably from 1 μηι to 10 μηι.
4. Method for the preparation of carrier colloidal powder with high specific surface area obtained by the method of claims 1 and 2, characterized in that a thin layer and/or nanoparticles, preferably nanoparticles, are applied onto the surface of this powder.
PCT/SI2011/000059 2010-10-20 2011-10-19 Method for the preparation of carrier colloidal powder with high specific surface area WO2012053990A2 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
SI201000330A SI23502A (en) 2010-10-20 2010-10-20 Method for the preparation of carrier colloidal powder with specific surface area
SI201000330 2010-10-20
SI201000433 2010-12-09
SI201000433A SI23580A (en) 2010-12-09 2010-12-09 Method for the preparation of carrier colloidal powder with high specific surface area

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WO2019127436A1 (en) * 2017-12-29 2019-07-04 深圳前海小有技术有限公司 Flowing water sterilization device
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