WO2012153272A1 - Photo-catalyst and its preparation - Google Patents
Photo-catalyst and its preparation Download PDFInfo
- Publication number
- WO2012153272A1 WO2012153272A1 PCT/IB2012/052291 IB2012052291W WO2012153272A1 WO 2012153272 A1 WO2012153272 A1 WO 2012153272A1 IB 2012052291 W IB2012052291 W IB 2012052291W WO 2012153272 A1 WO2012153272 A1 WO 2012153272A1
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- WIPO (PCT)
- Prior art keywords
- photo
- catalyst
- precursor
- supported
- composite
- Prior art date
Links
- 239000011941 photocatalyst Substances 0.000 title claims abstract description 66
- 238000002360 preparation method Methods 0.000 title description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000002131 composite material Substances 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 17
- 239000002243 precursor Substances 0.000 claims abstract description 17
- 229920000642 polymer Polymers 0.000 claims abstract description 15
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 239000004408 titanium dioxide Substances 0.000 claims abstract description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000000203 mixture Substances 0.000 claims abstract description 4
- 239000012299 nitrogen atmosphere Substances 0.000 claims abstract description 4
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 4
- 239000001301 oxygen Substances 0.000 claims abstract description 4
- 238000009987 spinning Methods 0.000 claims abstract description 4
- 239000012298 atmosphere Substances 0.000 claims abstract description 3
- 239000000725 suspension Substances 0.000 claims abstract description 3
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 5
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 claims description 4
- 239000004745 nonwoven fabric Substances 0.000 claims description 3
- 239000002759 woven fabric Substances 0.000 claims description 3
- 238000007598 dipping method Methods 0.000 claims description 2
- 239000010410 layer Substances 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000005507 spraying Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 230000015572 biosynthetic process Effects 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- YRKCREAYFQTBPV-UHFFFAOYSA-N acetylacetone Chemical compound CC(=O)CC(C)=O YRKCREAYFQTBPV-UHFFFAOYSA-N 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000002939 deleterious effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001523 electrospinning Methods 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 241000894007 species Species 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- DLINORNFHVEIFE-UHFFFAOYSA-N hydrogen peroxide;zinc Chemical compound [Zn].OO DLINORNFHVEIFE-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 230000001699 photocatalysis Effects 0.000 description 1
- 238000013032 photocatalytic reaction Methods 0.000 description 1
- 230000001766 physiological effect Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
- C02F1/32—Treatment of water, waste water, or sewage by irradiation with ultraviolet light
- C02F1/325—Irradiation devices or lamp constructions
-
- 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
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/39—Photocatalytic properties
-
- 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
- B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
- B01J35/58—Fabrics or filaments
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0201—Impregnation
- B01J37/0209—Impregnation involving a reaction between the support and a fluid
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
- B01J37/341—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation
- B01J37/342—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of electric, magnetic or electromagnetic fields, e.g. for magnetic separation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0215—Coating
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/32—Details relating to UV-irradiation devices
- C02F2201/322—Lamp arrangement
- C02F2201/3223—Single elongated lamp located on the central axis of a turbular reactor
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/32—Details relating to UV-irradiation devices
- C02F2201/322—Lamp arrangement
- C02F2201/3228—Units having reflectors, e.g. coatings, baffles, plates, mirrors
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/08—Nanoparticles or nanotubes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/10—Photocatalysts
Definitions
- This invention relates to a photo-catalyst and its preparation. More particularly, but not exclusively, the invention relates to a photo-catalyst that is suitable for use in water treatment apparatus in conjunction with ultraviolet (UV) radiation for the purpose of directly or indirectly killing potentially harmful biological species in the water and by destroying organic species that may be harmful.
- UV ultraviolet
- the invention is aimed, at least in part, at providing a photo-catalyst that can be used for the purpose of rendering water potable.
- a photo-catalyst such as titanium dioxide, when activated by ultraviolet light of one or more suitable wavelengths, acts to form various active species in water, and especially hydroxide radicals.
- titanium dioxide should it be ingested, make it extremely difficult, if not impossible, to use in its usual finely divided physical form in admixture with water for the purposes of purifying same. Effective separation of titanium dioxide powder from the water remains a problem.
- a method of producing a supported photo-catalyst comprising causing a photo-catalyst, or photo- catalyst precursor to become entrained in a carbonaceous support having an extended surface area; initially heating the supported photo-catalyst at a temperature in the region of from 250 to 350 °C in air or other oxygen containing atmosphere in order to stabilize the supported photo-catalyst and, as may be necessary, form the photo-catalyst from its precursor; and thereafter heating the supported photo-catalyst in a nitrogen atmosphere at a temperature in the region of from 800 °C to 1000°C or higher in order to form a composite having an extensive surface in which areas of photo-catalyst are exposed.
- a photo-catalyst precursor or a finely subdivided photo-catalyst is admixed with a suitable polymer spinning solution to form a solution or suspension thereof and the mixture is spun into a fibrous form preparatory to carrying out the two heating stages.
- the fibres are preferably electrostatically spun onto an electrically conductive mesh electrode, such as one of copper, that acts as a support structure for the final composite that may tend to be rather brittle.
- the fibres could be nanofibres
- the photo-catalyst is preferably titanium dioxide that is generally initially in the form of its precursor titanium tetrachloride and the polymer may be any suitable polymer that will decompose adequately during the heat treatment stages and form a suitable composite with the photo-catalyst.
- the polymer can conveniently be polyacrylonitrile.
- a support layer in the form of a mesh or an area of woven or nonwoven fabric, or layers of both could have a layer of liquid polymer solution containing a photo-catalyst or a photo-catalyst precursor applied to it such as by dipping, or spraying. Processing of the mesh or area of woven or nonwoven fabric would then follow the heating procedures defined above in order to form a suitable composite having an extensive surface in which areas of photo-catalyst are exposed.
- the mesh may form a support structure for the final photo-catalyst composite.
- the fabric could be a synthetic fabric having polymer fibres or, it could be one of natural origin and include cellulosic fibres. Such fabrics have yet to be tested.
- a photo-catalyst produced utilizing the method defined above can have any support structure for supporting the final composite formed into any suitable shape either before or after the heating procedures, as may be appropriate.
- a support structure in the form of a mesh that is used as an electrode in the production process is formed into a tubular shape so that it can encircle a tubular source of ultraviolet light, in use.
- the photo-catalyst may be used in water purification apparatus, as will be quite apparent to those skilled in the art.
- a titanium mesh could be used as a support in which instance differential expansion rates and any deleterious effects thereof may be avoided.
- Figure 1 is a diagram illustrating the formation of fibres as an intermediate in the formation of a photo-catalyst according to the invention.
- Figure 2 is a schematic sectional elevation illustrating one application of a photo-catalyst produced according to the invention.
- a method of producing a supported photo-catalyst comprises an initial step of causing a photo-catalyst precursor, in this instance titanium tetrachloride, to be admixed with a suitable polymer spinning solution, in this instance one of polyacrylonitrile in dimethylformamide and acetylacetone, to form a solution thereof.
- a photo-catalyst precursor in this instance titanium tetrachloride
- a suitable polymer spinning solution in this instance one of polyacrylonitrile in dimethylformamide and acetylacetone
- this mixture was subjected to electro-spinning of a non-woven fibrous mat [2], typically of nano fibres, on a support surface in the form of an electrically conductive mesh [3] that serves as one electrode during formation of the fibres.
- the fibres are formed by applying a high voltage to the electrically conductive mesh that is typically of copper as one electrode, with the other electrode being attached to a solution dispensing unit [4] in well-established manner. In this instance the voltage applied to the electrodes was 15 kV and the distance between the electrodes was about 100 mm.
- the photo-catalyst precursor thereby became entrained in a fibrous carbonaceous polymeric support having an extended surface area. Fibre formation was followed by heating the fibres in air [for the purpose of providing available oxygen] at a temperature of about 280 °C in order to allow titanium dioxide to form and stabilize and for the purpose of calcination of the polymer.
- Titanium dioxide/carbon composite nanofibres were thus successfully prepared by an electrospinning technique using polyacrylonitrile as polymer supporting material.
- the mesh forms a support structure for supporting the final composite formed and the mesh can be formed into any suitable shape, either before or after the heating procedures, as may be appropriate, in order to form a suitable configuration for use in a photo-catalytic application.
- the mesh in one application of the composite photo-catalyst, is formed into a tubular shape, as indicated by numeral [1 1 ] so that it can encircle a tubular UV light source [12], in use.
- the tubular mesh and concentric tubular UV light source are located axially within a tubular housing [13] having a water inlet [14] and a water outlet [15] at opposite ends of the tubular housing.
- the photo-catalyst may be used in water purification apparatus, as will be quite apparent to those skilled in the art.
- the housing may be made of a UV transparent glass such as a quartz glass and the outer surface [16] of the glass may be provided a mirror reflective surface so that UV light does not escape the apparatus and is reflected inwards to enhance the effect of the apparatus.
- the shape of the support structure could vary widely and, in the instance of a photocatalyst composite being formed on the surface of a mesh, water could be flowed through the mesh whilst it is illuminated with ultraviolet radiation.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Toxicology (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Electromagnetism (AREA)
- Catalysts (AREA)
Abstract
A method of producing a supported photo-catalyst is provided in which a photo-catalyst, or photo-catalyst precursor, is entrained in a carbonaceous support having an extended surface area. The supported photo-catalyst or precursor is then heated at a temperature in the region of from 250 to 350 °C in air or other oxygen containing atmosphere in order to stabilize the supported photo-catalyst and, as may be necessary, form the photo-catalyst from its precursor. The supported photo-catalyst is then heated in a nitrogen atmosphere at a temperature in the region of from 800 °C to 1000°C or higher in order to form a composite having an extensive surface in which areas of photo-catalyst are exposed. The photo-catalyst precursor or a finely subdivided photo-catalyst may be admixed with a suitable polymer spinning solution to form a solution or suspension thereof and the mixture may be spun into a fibrous form preparatory to heating thereof. The photo-catalyst may be titanium dioxide.
Description
PHOTO-CATALYST AND ITS PREPARATION
FIELD OF THE INVENTION
This invention relates to a photo-catalyst and its preparation. More particularly, but not exclusively, the invention relates to a photo-catalyst that is suitable for use in water treatment apparatus in conjunction with ultraviolet (UV) radiation for the purpose of directly or indirectly killing potentially harmful biological species in the water and by destroying organic species that may be harmful.
The invention is aimed, at least in part, at providing a photo-catalyst that can be used for the purpose of rendering water potable.
BACKGROUND TO THE INVENTION
It is known that a photo-catalyst such as titanium dioxide, when activated by ultraviolet light of one or more suitable wavelengths, acts to form various active species in water, and especially hydroxide radicals.
However, the potentially deleterious physiological properties of titanium dioxide, should it be ingested, make it extremely difficult, if not impossible, to use in its usual finely divided physical form in admixture with water for the purposes of purifying same. Effective separation of titanium dioxide powder from the water remains a problem.
There is a need for an effective photo-catalyst such as titanium dioxide in a form in which it may be retained within water treatment apparatus without becoming contained in a flow of water past it.
SUMMARY OF THE INVENTION
In accordance with this invention there is provided a method of producing a supported photo-catalyst comprising causing a photo-catalyst, or photo- catalyst precursor to become entrained in a carbonaceous support having an extended surface area; initially heating the supported photo-catalyst at a temperature in the region of from 250 to 350 °C in air or other oxygen containing atmosphere in order to stabilize the supported photo-catalyst and, as may be necessary, form the photo-catalyst from its precursor; and thereafter heating the supported photo-catalyst in a nitrogen atmosphere at a temperature in the region of from 800 °C to 1000°C or higher in order to form a composite having an extensive surface in which areas of photo-catalyst are exposed.
In one application of the invention a photo-catalyst precursor or a finely subdivided photo-catalyst is admixed with a suitable polymer spinning solution to form a solution or suspension thereof and the mixture is spun into a fibrous form preparatory to carrying out the two heating stages. The fibres are preferably electrostatically spun onto an electrically conductive mesh electrode, such as one of copper, that acts as a support structure for the final composite that may tend to be rather brittle. The fibres could be nanofibres
The photo-catalyst is preferably titanium dioxide that is generally initially in the form of its precursor titanium tetrachloride and the polymer may be any suitable polymer that will decompose adequately during the heat treatment stages and form a suitable composite with the photo-catalyst. The polymer can conveniently be polyacrylonitrile.
It is envisaged that zinc dioxide could also be made into a suitable photo- catalyst utilizing the method of the invention.
In another application of the invention a support layer in the form of a mesh or an area of woven or nonwoven fabric, or layers of both, could have a layer of liquid polymer solution containing a photo-catalyst or a photo-catalyst precursor applied to it such as by dipping, or spraying. Processing of the mesh or area of woven or nonwoven fabric would then follow the heating procedures defined above in order to form a suitable composite having an extensive surface in which areas of photo-catalyst are exposed.
In the instance of a mesh, the mesh may form a support structure for the final photo-catalyst composite. It is envisaged that the fabric could be a synthetic fabric having polymer fibres or, it could be one of natural origin and include cellulosic fibres. Such fabrics have yet to be tested.
A photo-catalyst produced utilizing the method defined above can have any support structure for supporting the final composite formed into any suitable shape either before or after the heating procedures, as may be appropriate.
In one application of the invention a support structure in the form of a mesh that is used as an electrode in the production process is formed into a tubular shape so that it can encircle a tubular source of ultraviolet light, in use. In such a configuration, the photo-catalyst may be used in water purification apparatus, as will be quite apparent to those skilled in the art. In the instance of titanium dioxide as the photo-catalyst, a titanium mesh could be used as a support in which instance differential expansion rates and any deleterious effects thereof may be avoided.
In order that the invention may be more fully understood an expanded description thereof as well as a description of various embodiments of the invention follows with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:-
Figure 1 is a diagram illustrating the formation of fibres as an intermediate in the formation of a photo-catalyst according to the invention; and,
Figure 2 is a schematic sectional elevation illustrating one application of a photo-catalyst produced according to the invention.
DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS
In one embodiment of the invention a method of producing a supported photo-catalyst comprises an initial step of causing a photo-catalyst precursor, in this instance titanium tetrachloride, to be admixed with a suitable polymer spinning solution, in this instance one of polyacrylonitrile in dimethylformamide and acetylacetone, to form a solution thereof. The titanium tetrachloride may be present in an amount of from 4 % by weight to 12% by weight and preferably about 8% by weight based on the weight of polyacrylonitrile present in the solution.
As illustrated in Figure 1 , this mixture was subjected to electro-spinning of a non-woven fibrous mat [2], typically of nano fibres, on a support surface in the form of an electrically conductive mesh [3] that serves as one electrode during formation of the fibres. The fibres are formed by applying a high voltage to the electrically conductive mesh that is typically of copper as one electrode, with the other electrode being attached to a solution dispensing unit [4] in well-established manner. In this instance the voltage applied to the electrodes was 15 kV and the distance between the electrodes was about 100 mm. The photo-catalyst precursor thereby became entrained in a fibrous carbonaceous polymeric support having an extended surface area.
Fibre formation was followed by heating the fibres in air [for the purpose of providing available oxygen] at a temperature of about 280 °C in order to allow titanium dioxide to form and stabilize and for the purpose of calcination of the polymer.
Thereafter the fibre and its mesh support were heated at a temperature of about 900° C in a nitrogen atmosphere in order to form and stabilize the final photo-catalyst carbon composite. The mesh together with the titanium dioxide/carbon composite on it was then capable of being used as a photo- catalyst, as will be quite apparent to those skilled in the art.
Titanium dioxide/carbon composite nanofibres were thus successfully prepared by an electrospinning technique using polyacrylonitrile as polymer supporting material.
It will be understood that the mesh forms a support structure for supporting the final composite formed and the mesh can be formed into any suitable shape, either before or after the heating procedures, as may be appropriate, in order to form a suitable configuration for use in a photo-catalytic application.
Referring to Figure 2 of the drawings, in one application of the composite photo-catalyst, the mesh is formed into a tubular shape, as indicated by numeral [1 1 ] so that it can encircle a tubular UV light source [12], in use. The tubular mesh and concentric tubular UV light source are located axially within a tubular housing [13] having a water inlet [14] and a water outlet [15] at opposite ends of the tubular housing. In this way, the photo-catalyst may be used in water purification apparatus, as will be quite apparent to those skilled in the art.
UV radiation emanating from the UV light source will therefore impinge on the photo-catalyst, in use, to activate it and cause it to promote photo-catalytic
reactions within the water that can promote and enhance the formation of OH radicals that attack organic pollutants to break them down into water and carbon dioxide and also attack microorganisms that may be present. In order to enhance this activity, the housing may be made of a UV transparent glass such as a quartz glass and the outer surface [16] of the glass may be provided a mirror reflective surface so that UV light does not escape the apparatus and is reflected inwards to enhance the effect of the apparatus.
Of course, the shape of the support structure could vary widely and, in the instance of a photocatalyst composite being formed on the surface of a mesh, water could be flowed through the mesh whilst it is illuminated with ultraviolet radiation.
It will be understood that numerous variations may be made to the embodiments of the invention described above without departing from the scope hereof.
Claims
1 . A method of producing a supported photo-catalyst comprising causing a photo-catalyst, or photo-catalyst precursor, to become entrained in a carbonaceous support having an extended surface area; initially heating the supported photo-catalyst or precursor at a temperature in the region of from 250 to 350 °C in air or other oxygen containing atmosphere in order to stabilize the supported photo-catalyst and, as may be necessary, form the photo-catalyst from its precursor; and thereafter heating the supported photo-catalyst in a nitrogen atmosphere at a temperature in the region of from 800 °C to 1000°C or higher in order to form a composite having an extensive surface in which areas of photo-catalyst are exposed.
2. A method as claimed in claim 1 in which a photo-catalyst precursor or a finely subdivided photo-catalyst is admixed with a suitable polymer spinning solution to form a solution or suspension thereof and the mixture is spun into a fibrous form preparatory to carrying out the two heating stages.
3. A method as claimed in claim 2 in which the fibres are electrostatically spun onto an electrically conductive mesh electrode that acts as a support structure for the final composite.
4. A method as claimed in either one of claims 2 or 3 in which the fibres are nanofibres.
5. A method as claimed in any one of the preceding claims in which the photo-catalyst is titanium dioxide that is initially in the form of its precursor titanium tetrachloride and the polymer is any suitable polymer that will decompose adequately during the heat treatment stages and form a suitable composite with the photo-catalyst.
6. A method as claimed in claim 5 in which the polymer is polyacrylonitrile.
7. A method as claimed in claim 1 in which a support layer in the form of a mesh or an area of woven or nonwoven fabric, or layers of both, has a layer of liquid polymer solution containing a photo-catalyst or a photo-catalyst precursor applied to it by dipping, or spraying.
8. A photo-catalyst composite whenever prepared by a method as claimed in any one of the preceding claims.
9. A photo-catalyst composite as claimed in claim 8 in which the support structure is in the form of a mesh that is used as an electrode in the production process.
10. A photo-catalyst as claimed in claim 9 in which the mesh is formed into a tubular shape such that it can encircle a tubular source of ultraviolet light, in use.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA201103468 | 2011-05-12 | ||
| ZA2011/03468 | 2011-05-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2012153272A1 true WO2012153272A1 (en) | 2012-11-15 |
Family
ID=47138854
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IB2012/052291 WO2012153272A1 (en) | 2011-05-12 | 2012-05-09 | Photo-catalyst and its preparation |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO2012153272A1 (en) |
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| EP3524572A1 (en) * | 2014-05-05 | 2019-08-14 | Synexis LLC | Air permeable substrate structure |
| US10967094B2 (en) | 2014-05-05 | 2021-04-06 | Synexis Llc | Purified hydrogen peroxide gas generation methods and devices |
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