CA1334520C - Degradation of organic chemicals with metal oxide ceramic membranes of titanium - Google Patents
Degradation of organic chemicals with metal oxide ceramic membranes of titaniumInfo
- Publication number
- CA1334520C CA1334520C CA 573215 CA573215A CA1334520C CA 1334520 C CA1334520 C CA 1334520C CA 573215 CA573215 CA 573215 CA 573215 A CA573215 A CA 573215A CA 1334520 C CA1334520 C CA 1334520C
- Authority
- CA
- Canada
- Prior art keywords
- membrane
- organic molecules
- titanium
- complex organic
- ultraviolet light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
- A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
- A62D3/10—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by subjecting to electric or wave energy or particle or ionizing radiation
- A62D3/17—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by subjecting to electric or wave energy or particle or ionizing radiation to electromagnetic radiation, e.g. emitted by a laser
- A62D3/176—Ultraviolet radiations, i.e. radiation having a wavelength of about 3nm to 400nm
-
- 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
- B01J16/00—Chemical processes in general for reacting liquids with non- particulate solids, e.g. sheet material; Apparatus specially adapted therefor
- B01J16/005—Chemical processes in general for reacting liquids with non- particulate solids, e.g. sheet material; Apparatus specially adapted therefor in the presence of catalytically active bodies, e.g. porous plates
-
- 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
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
- B01J19/122—Incoherent waves
- B01J19/123—Ultra-violet light
-
- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
- A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
- A62D2101/20—Organic substances
-
- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
- A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
- A62D2101/20—Organic substances
- A62D2101/22—Organic substances containing halogen
Abstract
Complex organic molecules, such as polychlorinated biphenyls can be degraded on porous titanium ceramic membranes by photocatalysis under ultraviolet light. A process for degrading complex organic molecules includes the steps of positioning a porous titanium ceramic membrane in a liquid solution or gaseous mixture containing the complex organic molecules irradiating the membrane in the solution with ultraviolet light. In one process of the invention, the step of exposing the complex organic molecules to the membrane includes adsorbing the molecules in the membrane. A
reliable, simple and efficient use of both particulate and polymeric titanium ceramic membranes to degrade persistent organic compounds is provided.
reliable, simple and efficient use of both particulate and polymeric titanium ceramic membranes to degrade persistent organic compounds is provided.
Description
~ 334520 DEGRADATION OF ORGANIC CHEMICALS WITH
METAL OXIDE CERAMIC MEMBRANES OF TRANSITION METALS
Field of the Invention The present invention relates to the use of ceramic membranes, and, in particular, relates to the reliable and successful use of both particulate and polymeric titanium ceramic membranes and coatings to degrade persistent organic compounds. Broadly speaking, metal oxide ceramic membranes of transition metals may be used for the degradation process.
~escription of the Prior Art Ceramic membranes are used currently in industry and science for a variety of processes and purposes, the most common of which is separations. While organic membranes are most often used for separation prDcesses, ceramic membranes have had increasing popularity because of several advantages which they offer over organic membranes. Ceramic membranes have a greater chemical stability since they are resistant to organic solvents, chlorine, and extremes of pH. Ceramic membranes are also stable at very high temperatures which allows for 20 efficient sterilization of process equipment and pharmaceutical equipment often not possible with organic membranes. Because ceramic membranes are inorganic they are generally quite stable to microbial or biological degradation which can occasionally be a problem with
METAL OXIDE CERAMIC MEMBRANES OF TRANSITION METALS
Field of the Invention The present invention relates to the use of ceramic membranes, and, in particular, relates to the reliable and successful use of both particulate and polymeric titanium ceramic membranes and coatings to degrade persistent organic compounds. Broadly speaking, metal oxide ceramic membranes of transition metals may be used for the degradation process.
~escription of the Prior Art Ceramic membranes are used currently in industry and science for a variety of processes and purposes, the most common of which is separations. While organic membranes are most often used for separation prDcesses, ceramic membranes have had increasing popularity because of several advantages which they offer over organic membranes. Ceramic membranes have a greater chemical stability since they are resistant to organic solvents, chlorine, and extremes of pH. Ceramic membranes are also stable at very high temperatures which allows for 20 efficient sterilization of process equipment and pharmaceutical equipment often not possible with organic membranes. Because ceramic membranes are inorganic they are generally quite stable to microbial or biological degradation which can occasionally be a problem with
-2-organic membranes. Ceramic membranes are also mechanically very stable even under high pressures. The temperature, chemical, and mechanical stability of ceramic membranes allows them to be cleaned more effectively than other less durable membrane compositions.
The mechanism of operation and types of separations which can be achieved by ceramic membranes are discussed in general by Asaeda et al., Jour. of Chem. Eng. of Japan, 19:1, 72-77 (1986). At least one line of ceramic filters 10 is currently on the market marketed under the trade-mark "Ceraflo" by the Norton Company of Worcester, Massachusetts. ~
While many of these characteristics seem to favor inorganic membranes over organic membranes, the use of 15 these membranes in widespread commercial applications has been slow because of the difficulty in producing crack-free membranes which hav~ defined ~ore size and distributions in desirable ranges. Some types of prior art inorganic membranes, such as the ultra-stabilized 20 zirconia membranes made by depositing particles on a silica support are stable but have relatively large pore sizes which make them suitable only for very high molecular weight separations.
Significant effort has been extended in creating metal 25 oxide membranes using aluminium. For example, it has been demonstrated that the use of sol-gel techniques allows the reproducible preparation of alumina ceramic membranes which may be supported or unsupported. LeEnaars et al., Jour. of Membrane Science, 24, 261-270 (1985). By 30 controlling various parameters of the process, it was demonstrated that reliable procedures can ~e developed for creating alumina ceramic membranes having relatively fine pores and a reliable size distri~ution of the pores.
The teachings in the art to date about the preparation 35 of titania ceramic membranes have been limited. Most of the sol-gel teachings utilizing titanium have been aimed at preparing very thin particulate films because of their ~_ -3-optical and corrosion resistance properties. However, th~
various parameters necessary for the reproducible an~
consistent preparation of these or similar films has not previously been rigorously described in such a fashion that they are readily ~eplicable.
It has been recognized for some time that many toxic organic chemicals can be degraded on suspended hydrous oxide ~articles. Prior research has tended to focus on easy to degrade compounds, such as acetate, and on the use of suspended particles to degrade such compunds. There are, ~or example, teachings in the prior art of the use of suspensions of titanium dioxide particles for the degradation of complex organic molecules. The use of suspended particles for these processes is a serious limitation, however since solid substrates are clearly more convenient to utilize. However, completely solid substrates do not provide enough surface area for effective catalyzation in reasonable time periods.
Summary of the Invention The present invention is summarized in that a process for degrading complex organic molecules including the steps of: positioning a porous titanium ceramic membrane in a liquid solution containin~ the complex organic molecules and irradiatin~ the membrane in the solution with ultraviolet light.
Detailed Description of the Invention The present invention is directed to the use of membranes of titanium oxides for degradation of organic molecules. There are two variations in methods of preparing titanium membranes.
The first variation involves the gellation of a colloidal sol.
This first variation utilizes a type of gel that is generally particulate but which can be formed in a coherent bulk if the processin~ variables are controlled carefully and can res~lt in a consistent and uniform membrane after gellation. The second variation ~n this method involves the hydrolysis of an organometallic titanium compound to form a soluble intermediate compound whlch then condenses into the inorganic titanium polymer. Since for cataLysis, it is desired that surface area available to the substrate be maximized, a porous or particulate titanium membrane i5 pre~erred for the process of the present invention.
The process thus includes the preparation of a particulate gel which is then fired to achieve a ceramic material. In this process, there are four distinct variables which must be carefully controlled. The first lS is the ratio of water to titanium in the colloidal sol so that the gel is properly formed. The ratio is prefera~ly less than about 300:1 mole-to-mole of water to titanium atoms, the second criteria is the proper selection of an alcohol solvent. The alcohol solvent is preferably an alkyl alcohol different from the alkyl radical in the titanium alkoxide used as the starting material. The third consideration is the tight controlling of the pH of the colloidal mixture. This control on pll limits availability of free protons relative to titanium molecules. The fourth consideration is an upper limit upon the sintering temperatures to which the resultant gels are exposed during firing. Firing temperatures in excess of about 500C may introduce an unacceptable amount o cracking into the resulting ceramic.
The preparation of a particulate titanium membrane begins with a titanium alkoxide. The titanium allcoxide is first hydrolyzed at room temperature. The typical reaction is thus:
TiR4 + 4~I20~ Ti(OH)4 + 4R + 2H2 The R radicaL may be any alkyl, but titanium tetraisopropoxide Ti(iso-OC3H7)4, has been found to be a convenient starting material.
The titanium alkoxide is first dissolved in an organic alcohol. It has been found that the hydrolysis is best facilitated by the use of an alkyl alcohol solvent where the alkyl is different from the alkyl in the titanium alkoxide, for example ethanol with titanium tetraisopropoxide. Water is then added in increments in a total volume of 200-300 times, mole-to-mole, of titanium present. The resulting titanium hydroxide, Ti(OH)4 will precipitate out of solution.
The titanium hydroxide precipitant is then peptized with HNO3, again at room temperature. This step converts the precipitant into a highly dispersed, stable, colloidal solution, or sol. This suspension is maintained by stirring and is dispersed over a time ~eriod of about 12 hours with moderate heating (85-95C) to assist the colloidal formation. When cooled to room temperature, the colloid gels. The gel may be solidified onto a support, such as glass or optical fiber, or may be deposited in molds or layered into sheets to make self-supporting structures. The gel is then sintered at a firing temperature of no more than about 500C to give a ~ard dry ceramic. Higher firing temperatures may result in cracking of the membrane. The result will be a highly porous, continuous web of sintered particles forming a rigid membrane.
The resulting titanium ceramic membrane functions as a highly desirable substrate for the photo-catalyzed degradation of organic molecules. The surface of the membranes are highly porous, there~y readily absorbing organic molecules. The titanium molecules are readily available for catalytic activity. The catalysis is actuated by UV light and broad spectrum UV radiation, even sunlight, is usable, although intense artificial UV light may tend to enhance the speed of the degradation.
Example 1 a) Preparation of Particulate Membranes Titanium tetraisopropoxide was obtained from Aldridge Chemical Company. Water used in the reactions was de-ionized using a Milli-~ water puri~ication system from Milliport Corporation.
A series of hydrolysis and particle gel formation experiments were per~ormed using a variety of pH levels and ratio between water concentration and titanium ion concentration. The results are summarized in Table 1 below.
Group A
H20/Ti H+/Ti TiO2 Stability Features *Weight Loss (mole (ratio) (wt %) of Sol of Solid in Gellation 15 No. ratio) Gel 1 300 0.08 2.0 NP good 2 200 0.2 2.0 S qood 97.66%
The mechanism of operation and types of separations which can be achieved by ceramic membranes are discussed in general by Asaeda et al., Jour. of Chem. Eng. of Japan, 19:1, 72-77 (1986). At least one line of ceramic filters 10 is currently on the market marketed under the trade-mark "Ceraflo" by the Norton Company of Worcester, Massachusetts. ~
While many of these characteristics seem to favor inorganic membranes over organic membranes, the use of 15 these membranes in widespread commercial applications has been slow because of the difficulty in producing crack-free membranes which hav~ defined ~ore size and distributions in desirable ranges. Some types of prior art inorganic membranes, such as the ultra-stabilized 20 zirconia membranes made by depositing particles on a silica support are stable but have relatively large pore sizes which make them suitable only for very high molecular weight separations.
Significant effort has been extended in creating metal 25 oxide membranes using aluminium. For example, it has been demonstrated that the use of sol-gel techniques allows the reproducible preparation of alumina ceramic membranes which may be supported or unsupported. LeEnaars et al., Jour. of Membrane Science, 24, 261-270 (1985). By 30 controlling various parameters of the process, it was demonstrated that reliable procedures can ~e developed for creating alumina ceramic membranes having relatively fine pores and a reliable size distri~ution of the pores.
The teachings in the art to date about the preparation 35 of titania ceramic membranes have been limited. Most of the sol-gel teachings utilizing titanium have been aimed at preparing very thin particulate films because of their ~_ -3-optical and corrosion resistance properties. However, th~
various parameters necessary for the reproducible an~
consistent preparation of these or similar films has not previously been rigorously described in such a fashion that they are readily ~eplicable.
It has been recognized for some time that many toxic organic chemicals can be degraded on suspended hydrous oxide ~articles. Prior research has tended to focus on easy to degrade compounds, such as acetate, and on the use of suspended particles to degrade such compunds. There are, ~or example, teachings in the prior art of the use of suspensions of titanium dioxide particles for the degradation of complex organic molecules. The use of suspended particles for these processes is a serious limitation, however since solid substrates are clearly more convenient to utilize. However, completely solid substrates do not provide enough surface area for effective catalyzation in reasonable time periods.
Summary of the Invention The present invention is summarized in that a process for degrading complex organic molecules including the steps of: positioning a porous titanium ceramic membrane in a liquid solution containin~ the complex organic molecules and irradiatin~ the membrane in the solution with ultraviolet light.
Detailed Description of the Invention The present invention is directed to the use of membranes of titanium oxides for degradation of organic molecules. There are two variations in methods of preparing titanium membranes.
The first variation involves the gellation of a colloidal sol.
This first variation utilizes a type of gel that is generally particulate but which can be formed in a coherent bulk if the processin~ variables are controlled carefully and can res~lt in a consistent and uniform membrane after gellation. The second variation ~n this method involves the hydrolysis of an organometallic titanium compound to form a soluble intermediate compound whlch then condenses into the inorganic titanium polymer. Since for cataLysis, it is desired that surface area available to the substrate be maximized, a porous or particulate titanium membrane i5 pre~erred for the process of the present invention.
The process thus includes the preparation of a particulate gel which is then fired to achieve a ceramic material. In this process, there are four distinct variables which must be carefully controlled. The first lS is the ratio of water to titanium in the colloidal sol so that the gel is properly formed. The ratio is prefera~ly less than about 300:1 mole-to-mole of water to titanium atoms, the second criteria is the proper selection of an alcohol solvent. The alcohol solvent is preferably an alkyl alcohol different from the alkyl radical in the titanium alkoxide used as the starting material. The third consideration is the tight controlling of the pH of the colloidal mixture. This control on pll limits availability of free protons relative to titanium molecules. The fourth consideration is an upper limit upon the sintering temperatures to which the resultant gels are exposed during firing. Firing temperatures in excess of about 500C may introduce an unacceptable amount o cracking into the resulting ceramic.
The preparation of a particulate titanium membrane begins with a titanium alkoxide. The titanium allcoxide is first hydrolyzed at room temperature. The typical reaction is thus:
TiR4 + 4~I20~ Ti(OH)4 + 4R + 2H2 The R radicaL may be any alkyl, but titanium tetraisopropoxide Ti(iso-OC3H7)4, has been found to be a convenient starting material.
The titanium alkoxide is first dissolved in an organic alcohol. It has been found that the hydrolysis is best facilitated by the use of an alkyl alcohol solvent where the alkyl is different from the alkyl in the titanium alkoxide, for example ethanol with titanium tetraisopropoxide. Water is then added in increments in a total volume of 200-300 times, mole-to-mole, of titanium present. The resulting titanium hydroxide, Ti(OH)4 will precipitate out of solution.
The titanium hydroxide precipitant is then peptized with HNO3, again at room temperature. This step converts the precipitant into a highly dispersed, stable, colloidal solution, or sol. This suspension is maintained by stirring and is dispersed over a time ~eriod of about 12 hours with moderate heating (85-95C) to assist the colloidal formation. When cooled to room temperature, the colloid gels. The gel may be solidified onto a support, such as glass or optical fiber, or may be deposited in molds or layered into sheets to make self-supporting structures. The gel is then sintered at a firing temperature of no more than about 500C to give a ~ard dry ceramic. Higher firing temperatures may result in cracking of the membrane. The result will be a highly porous, continuous web of sintered particles forming a rigid membrane.
The resulting titanium ceramic membrane functions as a highly desirable substrate for the photo-catalyzed degradation of organic molecules. The surface of the membranes are highly porous, there~y readily absorbing organic molecules. The titanium molecules are readily available for catalytic activity. The catalysis is actuated by UV light and broad spectrum UV radiation, even sunlight, is usable, although intense artificial UV light may tend to enhance the speed of the degradation.
Example 1 a) Preparation of Particulate Membranes Titanium tetraisopropoxide was obtained from Aldridge Chemical Company. Water used in the reactions was de-ionized using a Milli-~ water puri~ication system from Milliport Corporation.
A series of hydrolysis and particle gel formation experiments were per~ormed using a variety of pH levels and ratio between water concentration and titanium ion concentration. The results are summarized in Table 1 below.
Group A
H20/Ti H+/Ti TiO2 Stability Features *Weight Loss (mole (ratio) (wt %) of Sol of Solid in Gellation 15 No. ratio) Gel 1 300 0.08 2.0 NP good 2 200 0.2 2.0 S qood 97.66%
3 200 0.4 2.0 S good 97.62%
4 200 0.7 2.0 S good 97.61%
200 1.0 2.0 S cracks 97.60%
present 6 200 1.2 2.0 NS cracks present Group B
1 300 0.1 1.3 S good 2 300 0.5 1.3 S good 3 300 1.0 1.3 S good 4 300 1.2 1.3 S good S = Stable NS = not stable, floccus appearance NP = not peptized completely *Weight loss from original sol to solid gel, given as a percentage of the original qol weight.
From the above data it is evident that the stable *Trade-Mark _ -7-titanium sols can be best achieved if the mole ratio of free hydrogen ions (from the acid) to titanium molecules is between 0.1 and 1Ø This range can be expanded only in relatively dilute sol solutions such as those of Group B on the table. The reason for this is not completely understood but may relate to the increased interparticle distance in the more dilute solutions making aggregation more dif~icult than in concentrated sols. Only stable sols could be properly then transformed by peptization into coherent transparent gels and thereafter into coherent oxide membranes by protolysis.
The concentration of the acid was found to effect the gelling volume. The gelling volume goes through a minimum when the acid concentration is about 0.4 moles of free lS proton~ per mole of titanium. The sols need to loose at least 4.5% of their ori~inal weight, depending upon the electrolyte concentration, to arrive at the gelling point. The sols must loose some ad~itional 97.6% of their ori~inal weight in order to form a final solid gel.
Heating the final gels in the sintering process results in a further weight loss of about 13.5~ without destroying the internal gel structure.
b) Degradation of PCB's An aliquot of a PCB, 3,4 ~ichloro biphenyl, was dissolved in a non-polar solvent, alcohol or acetone. A
sintered particulate titanium ceramic membrane was then inserted into the dissolved PC~, and allowed to absorb the solution overnight. The membrane was then removed from the solution and placed in distilled de-ionized water in a Pyrex vessel in a water bath set to 50C.
The vessel was irradiated with a hiqh intensitv t~l light source, a Xe-Hg lamp such as an LPS 200 from Photo Technology International. Periodic samples of the water were removed and analyzed by gas chromotography At start of the reaction, a strong chlorine peak was apparent in the chromotograph. The peak diminished in minutes. After *Trade-Mark four hours, no chlorine peak could be detected indicating that the dechlorination of PCB's in the membrane was completed.
SUPPI.~:.~;N'l'ARY DISCLOSURE
This invention also encompasses a method of degrading complex organic molecules comprising the steps of exposing the organic molecules in solution to a ceramic porous membrane of titanium, and irradiating the titanium membrane with ultraviolet light wherein the step of exposing the complex organic molecules to the membrane includes adsorbing the molecules in the membrane.
The method of degrading the complex organic molecules may include exposing the complex organic molecules, preferably polychlorinated biphenyls to a porous titanium oxide ceramic membrane by adsorbing the molecules in the membrane and irradiating the membrane with ultraviolet light.
The method may involve adsorbing the organic molecules in the gaseous phase into a porous titanium oxide ceramic membrane and irradiating the membrane with ultraviolet light. The membrane may be coated onto the exterior of the light source specifically onto the exterior of an optical fiber carrying the ultraviolet light. Alternatively, the molecules may be adsorbed in the body of the porous titanium dioxide ceramic body which body may then be irradiated.
200 1.0 2.0 S cracks 97.60%
present 6 200 1.2 2.0 NS cracks present Group B
1 300 0.1 1.3 S good 2 300 0.5 1.3 S good 3 300 1.0 1.3 S good 4 300 1.2 1.3 S good S = Stable NS = not stable, floccus appearance NP = not peptized completely *Weight loss from original sol to solid gel, given as a percentage of the original qol weight.
From the above data it is evident that the stable *Trade-Mark _ -7-titanium sols can be best achieved if the mole ratio of free hydrogen ions (from the acid) to titanium molecules is between 0.1 and 1Ø This range can be expanded only in relatively dilute sol solutions such as those of Group B on the table. The reason for this is not completely understood but may relate to the increased interparticle distance in the more dilute solutions making aggregation more dif~icult than in concentrated sols. Only stable sols could be properly then transformed by peptization into coherent transparent gels and thereafter into coherent oxide membranes by protolysis.
The concentration of the acid was found to effect the gelling volume. The gelling volume goes through a minimum when the acid concentration is about 0.4 moles of free lS proton~ per mole of titanium. The sols need to loose at least 4.5% of their ori~inal weight, depending upon the electrolyte concentration, to arrive at the gelling point. The sols must loose some ad~itional 97.6% of their ori~inal weight in order to form a final solid gel.
Heating the final gels in the sintering process results in a further weight loss of about 13.5~ without destroying the internal gel structure.
b) Degradation of PCB's An aliquot of a PCB, 3,4 ~ichloro biphenyl, was dissolved in a non-polar solvent, alcohol or acetone. A
sintered particulate titanium ceramic membrane was then inserted into the dissolved PC~, and allowed to absorb the solution overnight. The membrane was then removed from the solution and placed in distilled de-ionized water in a Pyrex vessel in a water bath set to 50C.
The vessel was irradiated with a hiqh intensitv t~l light source, a Xe-Hg lamp such as an LPS 200 from Photo Technology International. Periodic samples of the water were removed and analyzed by gas chromotography At start of the reaction, a strong chlorine peak was apparent in the chromotograph. The peak diminished in minutes. After *Trade-Mark four hours, no chlorine peak could be detected indicating that the dechlorination of PCB's in the membrane was completed.
SUPPI.~:.~;N'l'ARY DISCLOSURE
This invention also encompasses a method of degrading complex organic molecules comprising the steps of exposing the organic molecules in solution to a ceramic porous membrane of titanium, and irradiating the titanium membrane with ultraviolet light wherein the step of exposing the complex organic molecules to the membrane includes adsorbing the molecules in the membrane.
The method of degrading the complex organic molecules may include exposing the complex organic molecules, preferably polychlorinated biphenyls to a porous titanium oxide ceramic membrane by adsorbing the molecules in the membrane and irradiating the membrane with ultraviolet light.
The method may involve adsorbing the organic molecules in the gaseous phase into a porous titanium oxide ceramic membrane and irradiating the membrane with ultraviolet light. The membrane may be coated onto the exterior of the light source specifically onto the exterior of an optical fiber carrying the ultraviolet light. Alternatively, the molecules may be adsorbed in the body of the porous titanium dioxide ceramic body which body may then be irradiated.
Claims (9)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of degrading complex organic molecules comprising the steps of exposing the organic molecules in solution to a ceramic porous membrane of titanium; and irradiating the titanium membrane with ultraviolet light.
2. A method as claimed in claim 1 wherein the complex organic molecules are polychlorinated biphenyls.
3. A method of degrading complex organic molecules comprising the steps of exposing the organic molecules in solution to a ceramic porous membrane of titanium, and irradiating the titanium membrane with ultraviolet light wherein the step of exposing the complex organic molecules to the membrane includes adsorbing the molecules in the membrane.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
4. A method of degrading complex organic molecules comprising the steps of exposing the complex organic molecules to a porous titanium oxide ceramic membrane by adsorbing the molecules in the membrane and irradiating the membrane with ultraviolet light.
5. A method as claimed in claim 4 wherein the complex organic molecules are polychlorinated biphenyls.
6. A method of degrading complex organic molecules comprising the steps of adsorbing the organic molecules in the gaseous phase into a porous titanium oxide ceramic membrane and irradiating the membrane with ultraviolet light.
7. A method of degrading complex organic molecules comprising the steps of exposing the organic molecules in the gaseous phase to a porous titanium oxide ceramic membrane and irradiating the membrane with ultraviolet light wherein the membrane is coated onto the exterior of a light source supplying the ultraviolet light.
8. A method of degrading complex organic molecules comprising the steps of exposing the organic molecules in the gaseous phase to a porous titanium oxide ceramic membrane and irradiating the membrane with ultraviolet light wherein the membrane is coated onto the exterior of an optical fiber carrying the ultraviolet light.
9. A method of degrading complex organic molecules comprising the steps of exposing the complex organic molecules to a porous titanium oxide ceramic body of titanium by adsorbing the molecules in the body and irradiating the adsorbed molecules with ultraviolet light.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US7804387A | 1987-07-27 | 1987-07-27 | |
| US078,043 | 1987-07-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1334520C true CA1334520C (en) | 1995-02-21 |
Family
ID=22141566
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 573215 Expired - Lifetime CA1334520C (en) | 1987-07-27 | 1988-07-27 | Degradation of organic chemicals with metal oxide ceramic membranes of titanium |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JP2739128B2 (en) |
| CA (1) | CA1334520C (en) |
| DE (1) | DE3890597C2 (en) |
| GB (1) | GB2217321B (en) |
| WO (1) | WO1989000985A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4002437A1 (en) * | 1990-01-27 | 1991-08-01 | Man Technologie Gmbh | Catalytic gas phase decomposition of organic halogen cpds. |
| US5137607A (en) * | 1990-04-27 | 1992-08-11 | Wisconsin Alumni Research Foundation | Reactor vessel using metal oxide ceramic membranes |
| GB9102766D0 (en) * | 1991-02-09 | 1991-03-27 | Tioxide Group Services Ltd | Destruction process |
| GB9102767D0 (en) * | 1991-02-09 | 1991-03-27 | Tioxide Group Services Ltd | Destruction process |
| US5468699A (en) * | 1992-07-30 | 1995-11-21 | Inrad | Molecular sieve - photoactive semiconductor membranes and reactions employing the membranes |
| US6284314B1 (en) | 1993-12-09 | 2001-09-04 | Agency Of Industrial Science & Technology, Ministry Of International Trade & Industry | Porous ceramic thin film and method for production thereof |
| JP2636158B2 (en) * | 1993-12-09 | 1997-07-30 | 工業技術院長 | Titanium oxide porous thin film photocatalyst and method for producing the same |
| US10471289B2 (en) | 2017-01-04 | 2019-11-12 | King Abdulaziz University | Carbon-modified titanium dioxide nanoparticles and the photocatalytic remediation of aqueous sources systems and methods thereof |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4072596A (en) * | 1975-04-30 | 1978-02-07 | Westinghouse Electric Corporation | Apparatus for removal of contaminants from water |
| JPS594436A (en) * | 1982-06-29 | 1984-01-11 | Toshiba Corp | Photochemical reaction method using solar light |
| JPS60118289A (en) * | 1983-11-30 | 1985-06-25 | Giken Kogyo Kk | Water purifying method |
| US4659443A (en) * | 1984-08-22 | 1987-04-21 | Pcb Sandpiper, Inc. | Halogenated aromatic compound removal and destruction process |
| US4585533A (en) * | 1985-04-19 | 1986-04-29 | Exxon Research And Engineering Co. | Removal of halogen from polyhalogenated compounds by electrolysis |
-
1988
- 1988-07-26 DE DE3890597A patent/DE3890597C2/en not_active Expired - Lifetime
- 1988-07-26 WO PCT/US1988/002539 patent/WO1989000985A1/en active Application Filing
- 1988-07-26 GB GB8906707A patent/GB2217321B/en not_active Expired - Lifetime
- 1988-07-26 JP JP63506624A patent/JP2739128B2/en not_active Expired - Lifetime
- 1988-07-27 CA CA 573215 patent/CA1334520C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE3890597C2 (en) | 1996-11-07 |
| GB2217321B (en) | 1991-11-27 |
| JPH02500258A (en) | 1990-02-01 |
| JP2739128B2 (en) | 1998-04-08 |
| WO1989000985A1 (en) | 1989-02-09 |
| GB2217321A (en) | 1989-10-25 |
| GB8906707D0 (en) | 1989-05-24 |
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