CA2479571C - Photodegradation of toxic organic contaminants - Google Patents
Photodegradation of toxic organic contaminants Download PDFInfo
- Publication number
- CA2479571C CA2479571C CA002479571A CA2479571A CA2479571C CA 2479571 C CA2479571 C CA 2479571C CA 002479571 A CA002479571 A CA 002479571A CA 2479571 A CA2479571 A CA 2479571A CA 2479571 C CA2479571 C CA 2479571C
- Authority
- CA
- Canada
- Prior art keywords
- pentachlorophenol
- polychlorinated
- photodegradation
- process according
- toxic
- 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
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
- C07C37/70—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C39/00—Compounds having at least one hydroxy or O-metal group bound to a carbon atom of a six-membered aromatic ring
- C07C39/24—Halogenated derivatives
- C07C39/26—Halogenated derivatives monocyclic monohydroxylic containing halogen bound to ring carbon atoms
- C07C39/27—Halogenated derivatives monocyclic monohydroxylic containing halogen bound to ring carbon atoms all halogen atoms being bound to ring carbon atoms
- C07C39/36—Pentachlorophenol
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D307/77—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom ortho- or peri-condensed with carbocyclic rings or ring systems
- C07D307/91—Dibenzofurans; Hydrogenated dibenzofurans
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D319/00—Heterocyclic compounds containing six-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D319/10—1,4-Dioxanes; Hydrogenated 1,4-dioxanes
- C07D319/14—1,4-Dioxanes; Hydrogenated 1,4-dioxanes condensed with carbocyclic rings or ring systems
- C07D319/24—[b,e]-condensed with two six-membered rings
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Extraction Or Liquid Replacement (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
Abstract
The present invention provides for the photodegradation of a solution of organic toxic chemicals including pentachlorophenol, polychlorinated dibenzo-p-dioxins; and polychlorinated dibenzofurans, by exposing such solution to UV or sunlight, in the presence of a photosensitizer.
Description
I) Title Photodegxadation of Toxic Organic Contaminants This application is a division of Canadian application No. 2,127,242.
~~ 8ackcLround of the Invention (i) Field of the Invention This invention relates to the degradation of toxic organic contaminants.
(ii) Background Axt Toxic organic contaminants include polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, which are large groups of chloro-organic compounds tahioh have become ubiquitous in industrial societies. Of the various possible isomers of, these compounds, the following are reportedly ~.5 extremely toxzc a 2,3,7,8-tetrachloradibenso-p-dioxin, 1,2,3,7,8-pentachlorodibenzo-p-dioxin, 2,3,7,8-tetrachloradibenzofuran, 1,2,3,7.8-pentachlorodibenzofuxan, 2,3,4,7,8=
pentachlorodibenzofuran, 1,2,3,5,7,8-'hexachloxodibenaa-p-2o dioxin, 1,2,3,7,8,9-hexachloradibenza-p-dioxin, ~,,2,3,4,7,8-hexachlarodibenzo-p-dioxin, 1,,2,3,6,7,8-hexachlorodibenzofuran, 1,2,3,7,8,9-hexachlorodibenzafuran, 1,2,3,4,3,8-hexachlorodibenzofuran, and. 2,3,4,6,7,8-hexachlorodibenzofuran.
25 Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurana are known to cause a temporary form of a skin ailment known as P'chlor-acne". Also, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzafuxans (particular7.y 2 , 3 , 7, $-tetrachlorodiberlzo-p-da.oxin) have been found to be extremely toxic to certairn animals in labdz~atory studies.
Because o~ this reported high level of toxicity in laboratory tests, there is a general concern as to the long-term effects of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans an human physiology.
Accordingly, there is an importane need to remove or substantially reduce the content of polychlorinated dibenzo-p-a.0 dioxins and polychxorinated dibenzofurans from used telephone poles, used railway ties, used fence posts, etc., prior to disposal or reuse of the waste. There is also a need for a process for treating solutions containing toxic organic contaminants, as described above, and including toxic organic ~5 contaminants which have been removed from treated wood, so that they can be disposed of safely.
Pentachlorophenol-treated utility poles contain high levels of pentach~,orophen.ol and related contaminants, and consequently can not be disposed of in landfill sites. zt has 20 been suggested to use bioremediation as a possible tnray of decontaminating ~:he~se materials. Poles removed from sex-vice have a high pentachlorophenol content, i.e., of the order of about 5,000 - 27,000 ppm in the outer 20 mm zone, This high ~.evel of pentachlorophenol is toxic to most microorganisms 25 which have been suggested for use in the biaremediation process. AcCOxdingly, it is necessary to pre-treat the pole material Go reduce the content of such contaminants before biological remedza~.ion, physical or chemical methods can k~e used for the pre-treatment process, Physical methods, e.g,, dilution, i.e., mixing the pentachlorophenol-containing sawdust with large amounts of uncontaminated sawdust or other materials, so that the pentachlorophenol concentration is low enough for the microorgan~.sms tv survive, ins not feasible economically. zt also has the problem of generating a much larger volume of contaminated waste. Therefore, any kind of dilution approach is not considered to be suitable.
Solvent extraction is probably tY~e easiest and most effective laboratory method of removz~ng pe:ntachlorophenol from contaminated wood. However, extraction using organic solvents is also not cansidexed appropriate commercially, because of env~.ronmental concerns and tha hazards involved in a large scale operation.
Chemical treatment has also been, suggested for pre-treating the pentachlorophenol-containing wood before bioremediation. Pentachlorophenol is, however, very stable and onl~r a few systems can modify and/or degrade this molecule. $ecause of the strong, relatively non-polar covalent C-C1 bonds in gentachlorophenol, removal. of the chlorine by hydrolysis i$ difficult, Pentaahlnrophenol is an 2~ electron-deficient molecule and should be more reactive towards reduction than ox~,da~ion. Potassium-graphite-intercalate has been suggested as an agent for dechlorinatiorx of a number of compounds inaxuding pentachlorophenal and actachloradibenzo-p-d~,oxin. This systEm, however, requires inert atmosphere, high temperature and absa7.ute anhydrous aanditions and is impractical .for large kale applications.
Electraahemical reduction has been xauggested for use far treating waste waters containing law ct~ncent~rations of chlorinated arganics. Such process was considered not suitable s~,nce, far electrochemical processes to work, the 1.0 electrodes must maintain clean surfaces. Moreover, the oil and Qther contaminants iz~ pentachlorophenol-treated Wood would contaminate the electrodes very quickly.
Reductive dechlari,nation of chlorinated organic compounds by photochemical reactions has also been suggested to detoxify pent,achlorophenol~cvntaining materials. Photochemical degradation of pentachlorophenol and lower chlorophenals in the presence, or absence, of rrarioua phatosensitizers az~d catalysts have furthermore been suggested. 2t is known that polychlorinated biphenyls may be dechlorirlated in the presence z0 of visible dyes and amines using visible light.
Oxidation of chlorophenols by enzymes has also been suggested. Laccases may be used tv remove chlarophenols from water through polymeri2ation. This method, however, does not provide a permanent solution to the problem. The oxidation 2~ of phenolic palzutaz~ts by lignin peroxidase, an enzyme from PhatZerac~haete ch,rysosporium, haB also been suggested. On the _.., _.,, . ~...~:,~,.~.,~ $~,.,~ .~ _ .__. __..__ ._ M ___.. _. ..
other hand, it is l~nown that chlorophenols could be converted to much more toxic polychlorodibenao-p-dioxins by peroxidase catalyzed oxidation.
Supercritical fluids have also been $uggegted to extract 5 ceZluZoaic materials, A supercritical fluid (8CF) is a fluid at a temperatur°e above its critical value. ~.n SCF has prvpert~.es which axe intermediate between these of gases and liquids. It has a viscosity which is lower than that of a liquid and a density which is higher i~hax~ that of a gays.
These properties allow SCFs to penetrate matrices easily, while reta~,ning reasonable dissolving power. Supercritical fluid extract~.on (an FE) is a technique in wh3.ch gases are compressed under supercritical conditions to form a fluid, ' which is then used to remove chemicals from a matrix. Among the various solvents suitable for SFB, carbon dioxide is the most commonly used, because it is non toxic, non-flammable, and zne~epensive. Carbon dioxide also has low critical.
temperature and pressure, thus having a minimum requirement for equipment design, SFE provides superior extraction to 2o routine sal~crent extraction in several aspects. For example, SFE lea~crc~s no solvent residue in the matxisc after extraction, since carbon dioxide is a gas at normal temperature and pressure. The extract is automatically separated from the $ohrent when the pressure i;s released (carbon dioxide under rtvn-Critical conditions can hardly dissolve any of the extracty, and since it eliminates Che solvent-extract separation step, it is very energy efficient. In addition, SFS can be done in a closed system where carbon dioxide i$
continuously recycled.
A discussion of background art relating to SFE is included in my co-pending Canadian patent application No.
2,127,242, to which the reader is directed far reference, It is thought that the degradation of pentachlorophenol, polychlorinated dibenzo~p-dioxins and polychlorinated dibenzofurans in solution and in sawdust slurry may be achieved by photochemxcals reactions. However, a commercially-viable photochemical degradation process has not been taught by the prior art.
An object of this invention is to provide a commercially viable process for the degradation of such extracted contaminants.
3 ) Summary of the Inyention fi) Statement of Invention According to a first aspect of the invention, there is provided a process for photodegrading organic toxic chemicals which process comprises the steps of:
providing a solution of said organic toxic chemicals, a solvent and a photosensitizing amount of a photosensitizes which is selected from the group consisting of a porphxrzn and a phthalocyanine; and exposing said solution to radiation which is selected from the group consisting of w and sunlight.
(ii) other Features of the Tnvention Preferably, the radiation comprises direct sunlight.
'Ihe sol~rent may be selected from the group consisting of acetonitrile, methanol, ethanol, and other water-miscible solvents.
~~ 8ackcLround of the Invention (i) Field of the Invention This invention relates to the degradation of toxic organic contaminants.
(ii) Background Axt Toxic organic contaminants include polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, which are large groups of chloro-organic compounds tahioh have become ubiquitous in industrial societies. Of the various possible isomers of, these compounds, the following are reportedly ~.5 extremely toxzc a 2,3,7,8-tetrachloradibenso-p-dioxin, 1,2,3,7,8-pentachlorodibenzo-p-dioxin, 2,3,7,8-tetrachloradibenzofuran, 1,2,3,7.8-pentachlorodibenzofuxan, 2,3,4,7,8=
pentachlorodibenzofuran, 1,2,3,5,7,8-'hexachloxodibenaa-p-2o dioxin, 1,2,3,7,8,9-hexachloradibenza-p-dioxin, ~,,2,3,4,7,8-hexachlarodibenzo-p-dioxin, 1,,2,3,6,7,8-hexachlorodibenzofuran, 1,2,3,7,8,9-hexachlorodibenzafuran, 1,2,3,4,3,8-hexachlorodibenzofuran, and. 2,3,4,6,7,8-hexachlorodibenzofuran.
25 Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurana are known to cause a temporary form of a skin ailment known as P'chlor-acne". Also, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzafuxans (particular7.y 2 , 3 , 7, $-tetrachlorodiberlzo-p-da.oxin) have been found to be extremely toxic to certairn animals in labdz~atory studies.
Because o~ this reported high level of toxicity in laboratory tests, there is a general concern as to the long-term effects of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans an human physiology.
Accordingly, there is an importane need to remove or substantially reduce the content of polychlorinated dibenzo-p-a.0 dioxins and polychxorinated dibenzofurans from used telephone poles, used railway ties, used fence posts, etc., prior to disposal or reuse of the waste. There is also a need for a process for treating solutions containing toxic organic contaminants, as described above, and including toxic organic ~5 contaminants which have been removed from treated wood, so that they can be disposed of safely.
Pentachlorophenol-treated utility poles contain high levels of pentach~,orophen.ol and related contaminants, and consequently can not be disposed of in landfill sites. zt has 20 been suggested to use bioremediation as a possible tnray of decontaminating ~:he~se materials. Poles removed from sex-vice have a high pentachlorophenol content, i.e., of the order of about 5,000 - 27,000 ppm in the outer 20 mm zone, This high ~.evel of pentachlorophenol is toxic to most microorganisms 25 which have been suggested for use in the biaremediation process. AcCOxdingly, it is necessary to pre-treat the pole material Go reduce the content of such contaminants before biological remedza~.ion, physical or chemical methods can k~e used for the pre-treatment process, Physical methods, e.g,, dilution, i.e., mixing the pentachlorophenol-containing sawdust with large amounts of uncontaminated sawdust or other materials, so that the pentachlorophenol concentration is low enough for the microorgan~.sms tv survive, ins not feasible economically. zt also has the problem of generating a much larger volume of contaminated waste. Therefore, any kind of dilution approach is not considered to be suitable.
Solvent extraction is probably tY~e easiest and most effective laboratory method of removz~ng pe:ntachlorophenol from contaminated wood. However, extraction using organic solvents is also not cansidexed appropriate commercially, because of env~.ronmental concerns and tha hazards involved in a large scale operation.
Chemical treatment has also been, suggested for pre-treating the pentachlorophenol-containing wood before bioremediation. Pentachlorophenol is, however, very stable and onl~r a few systems can modify and/or degrade this molecule. $ecause of the strong, relatively non-polar covalent C-C1 bonds in gentachlorophenol, removal. of the chlorine by hydrolysis i$ difficult, Pentaahlnrophenol is an 2~ electron-deficient molecule and should be more reactive towards reduction than ox~,da~ion. Potassium-graphite-intercalate has been suggested as an agent for dechlorinatiorx of a number of compounds inaxuding pentachlorophenal and actachloradibenzo-p-d~,oxin. This systEm, however, requires inert atmosphere, high temperature and absa7.ute anhydrous aanditions and is impractical .for large kale applications.
Electraahemical reduction has been xauggested for use far treating waste waters containing law ct~ncent~rations of chlorinated arganics. Such process was considered not suitable s~,nce, far electrochemical processes to work, the 1.0 electrodes must maintain clean surfaces. Moreover, the oil and Qther contaminants iz~ pentachlorophenol-treated Wood would contaminate the electrodes very quickly.
Reductive dechlari,nation of chlorinated organic compounds by photochemical reactions has also been suggested to detoxify pent,achlorophenol~cvntaining materials. Photochemical degradation of pentachlorophenol and lower chlorophenals in the presence, or absence, of rrarioua phatosensitizers az~d catalysts have furthermore been suggested. 2t is known that polychlorinated biphenyls may be dechlorirlated in the presence z0 of visible dyes and amines using visible light.
Oxidation of chlorophenols by enzymes has also been suggested. Laccases may be used tv remove chlarophenols from water through polymeri2ation. This method, however, does not provide a permanent solution to the problem. The oxidation 2~ of phenolic palzutaz~ts by lignin peroxidase, an enzyme from PhatZerac~haete ch,rysosporium, haB also been suggested. On the _.., _.,, . ~...~:,~,.~.,~ $~,.,~ .~ _ .__. __..__ ._ M ___.. _. ..
other hand, it is l~nown that chlorophenols could be converted to much more toxic polychlorodibenao-p-dioxins by peroxidase catalyzed oxidation.
Supercritical fluids have also been $uggegted to extract 5 ceZluZoaic materials, A supercritical fluid (8CF) is a fluid at a temperatur°e above its critical value. ~.n SCF has prvpert~.es which axe intermediate between these of gases and liquids. It has a viscosity which is lower than that of a liquid and a density which is higher i~hax~ that of a gays.
These properties allow SCFs to penetrate matrices easily, while reta~,ning reasonable dissolving power. Supercritical fluid extract~.on (an FE) is a technique in wh3.ch gases are compressed under supercritical conditions to form a fluid, ' which is then used to remove chemicals from a matrix. Among the various solvents suitable for SFB, carbon dioxide is the most commonly used, because it is non toxic, non-flammable, and zne~epensive. Carbon dioxide also has low critical.
temperature and pressure, thus having a minimum requirement for equipment design, SFE provides superior extraction to 2o routine sal~crent extraction in several aspects. For example, SFE lea~crc~s no solvent residue in the matxisc after extraction, since carbon dioxide is a gas at normal temperature and pressure. The extract is automatically separated from the $ohrent when the pressure i;s released (carbon dioxide under rtvn-Critical conditions can hardly dissolve any of the extracty, and since it eliminates Che solvent-extract separation step, it is very energy efficient. In addition, SFS can be done in a closed system where carbon dioxide i$
continuously recycled.
A discussion of background art relating to SFE is included in my co-pending Canadian patent application No.
2,127,242, to which the reader is directed far reference, It is thought that the degradation of pentachlorophenol, polychlorinated dibenzo~p-dioxins and polychlorinated dibenzofurans in solution and in sawdust slurry may be achieved by photochemxcals reactions. However, a commercially-viable photochemical degradation process has not been taught by the prior art.
An object of this invention is to provide a commercially viable process for the degradation of such extracted contaminants.
3 ) Summary of the Inyention fi) Statement of Invention According to a first aspect of the invention, there is provided a process for photodegrading organic toxic chemicals which process comprises the steps of:
providing a solution of said organic toxic chemicals, a solvent and a photosensitizing amount of a photosensitizes which is selected from the group consisting of a porphxrzn and a phthalocyanine; and exposing said solution to radiation which is selected from the group consisting of w and sunlight.
(ii) other Features of the Tnvention Preferably, the radiation comprises direct sunlight.
'Ihe sol~rent may be selected from the group consisting of acetonitrile, methanol, ethanol, and other water-miscible solvents.
~n embodiments of the invention, the process may take place in the presence of an amine, e.g., triethanolarnine.
5 2n embodiments of the invention, the photodegradation to ~~wYfl~a H~~ ~~v:~ ~r~~r:~ ~~~~~~;r~rtc may take place i.n a slurry of wood caz5taminated with said contaminants, or the gh4t.odegradation to degrade toxic organic chemicals may take place in a liqu~.d solvent phase.
~) nescription c~f Preferred F~nbodiments Photodegxadation processes embodying the present invention may b~: employed after first e~ttracting the organic to~sic eontami,nants using a supercritical fluid extraction tSFE) disclosed and claimed in copending Canadian patent.
~fl app~.ication No. 2,127,42 to which the reader is directed far details.
~~,ICALS USED
All the chlorophenol and dihydroxychlorobenzene standards z5 were obtained from Fluka. PentachlorophenaX wa.s 99% pure from Aldrich and was used without further purification. Tecrsnical grade pentachloraphenol, manufactured by KMG, was provided by a presexwatxve treating plant. Methylene blue double zinc salt, was acquired from Mathesoxi, Coleman and dell.
20 Fhthalocyaninetetrasulfanate sodium salt was purchased from Porphyrin Products. Protoporphyrin I~ was a gift from Professor David Dolphin, Department of Chemistry, UHC.
Triethanolarnine (99.8%, certified) was purchased from Fishex-Scienta,fic. All solvents were spectral grade (4ML~IISOT,vz,",) 25 from BDH and all other chemicals were of analytical grade.
GENERAL PROCEDURE
EbUIPMEN'T USED
a The GCMS was a VG Trio-1000 system equipped with a 3 Q
meter DB-5 column. The reagent gas for chem~.cal ionization (CI) QCMS was ultra high purity methane. GG-ECD (electron-capture detector.) was carried out on a ~-~p 5890 II GC with a 30 meter DS-1 column. sample injection for the GC-ECD was 20 done by using a HP ~67o autosampler.
Several examples will be described to illustrate photodegradation of organic toxic compounds in accordance with this invention. In each Case, the compounds are placed in solution with a suitable phvtosensiti2ex~.
EXAMPLE 2- Photochemical bec~radaCion of Pentachlorophenol The photochemical degradation of pentachlorophe~aol waa first studied using 1:1 acetonitrile/water (volume) as the Rfl~ VI~51'~ Ta~'1~ d 1 ~'1r-~~ A~.Y c~nc.Ta 1~~1W raoml i-t.
xo Photochemical Dag~radation of Pentachlorophenol (2xlb'3 M? in 1:1 Acetonitrile/Water (volume) in the Presence of Triethanalamine (0.02 M) and Various Sensiti~ers (1x10'3 M) Ph4tosensitizer POTS Mix* Methylene Protoporphyrin Blue IX
lb Time (hours) PCP Con,~ent ratxor~ (fpm) 1 165 91.6 43.2 20 2 71.6 28 1.2 2 3 36 1.6 0 b 4 15 0 a 0 6 3.2 0 0 0 7 1.5 0 0 0 * : A mixture of PCTS (ghthalocyaninatetrasulfanatey , m~ethylene blue, arid protopoxphyri.n IX, each at x ~0"4 M
3.33 As can be seen from Table Z, pentachlorophenol wag rapidly degraded. only pentachlorophenoland trace amounts of tetrachldropheno7a were detested by GCMS after acetic anhydride derivatization. Protopoxphyrin IX was the mast effective photasensitiaer, with methyleneblue only slightly less effective. Over 99~ of the pentachlorophenol was destroyed within two hours using either metklylene blue or protoporphyrin IX as sensitizers.
The reaction was then repeated in 50~ (volume) aqueous ethanol which was cheaper and less toxic than aqueous acetonitrile.
Table 2 shows the results of such photochemical degradation.
T~BLF~ 2 photochemical degradation of Pentachlorophenol (2x10'' M) in 1:1 Acetonitrile/Watex (~crolume) in the Presence of Triethanolamine {0.02 M) arid various Sensitizers (1x10-9 1~) ~. 0 Photosensitizes POTS Methylene Prc~toporphyrin Blue IX
Time (minutes) PCP Concen tration (npm) 3d 229.5 17.0 ~?
60 190 5.5 1.5 90 139 0.25 0 150 75.5 0 0 As can be seen from Table 2, the photochemical destruction of pentachlorophenol in this solvent was fast.
within just ~. hour, over 99~ of the pentachlorophenol was degraded. Protopox~phyrin was again the most effective sensitizes. The differences in the efficiencies of the three 1~
sensitizexs was probably due to thezr different extinction coefficients as shown below in Table 3.
TAHL~ 3 Extinction Coefficient of ~k~ree dyes in 1:1 Ethanol/Water (volume) rye Absorption Maxima (nm) Extinction Coefficient (M'lcm'~j Methy~.ene slue X60 5.8 x ZO°
25 Phthaloeyanine-tetrasulfonate E37 4.0 x 104 3,99 x 10' 20 Proeoporphyrin 2X 378 1.48 x 10~
25 Protoporphyrin has an extinction coefficient almost four times larger than that of phthalocyaninet:etrasulfanate in 54~s ethanol. All three sensitizers absorb light at different wavelengths. ~t was thought that if the three sensitiaers were mixed tdc~ether, they would absorb light efficiently over 3a a wider range of wavelength and therefore would be more efficient in degrading pentachlorophenol than any individual sensitizers. As can be seen from Table Z, the mixture system containing three sensitizers, each at one third of their regular concentrations, was more effective than 35 phthalocyaninetetrasulfonate, but still ~.ess effective than protoporphyrin TX or methylene blue, While it is not desired to be bound by theory, ~.t is believed that this was probably due to the low extinction coefficient of phthalooyaninetetrasulfanate, The formation of by-products from the photochemical degradation of pentach7.orophenol was caz~efully studied by GCMS
analysis of a concentrated extract derivatized with.
diazomethane. Szx products including 2,3,~,6-tetrachZorophenol, tetrachlorohydroquinone, tetrachsoracatechol, tetrachlaroresorainal, and dichZoromaleic acid were detected, These are shown beT_ow.
1~
oh " off cy, cl of o cr w 'CI A 'GI CI ~ ~CI
CI
rl d 1~
1 ~ cl I
a h xHe CI Ci CI q tr OOyN
i cl ~ ''orl a ~ 'a d of 20 AZ1 these groduets were present only in trace amounts as shown below in Table 4. The identities of these product$ were confirmed by their mass spectra, and by co~paring their ~C
retention times with those of sGandarde on two different columns (DB-1 and DB-5) a O ~ r O O in ~ .~., w o O o O C; ~ O o v o a o o ~ c c c o r o r~ o 0 o e~s ~ ~ c~ o °o, ~ ~ c'~.~ ° ~ rev, ~ e'~y, o '~
N O ~-~ C C7 O O ~.-~ G ~ G ~
0 o°,oMr~c~~~ L'~~~n,~e r~ Sri o o ~ ,~., o y o ~ N '~ ' ~ o o 0 0 ~ ~ a o p, ~ef ° O O o C7 Q D O P
C ~.i ~D tP1 Y'f N ~ l'~ ~_ d O Q O O C~ C O O C?
en O C C C ,7,., O ~ e~ D O d G~i h.
OOm.~O, ~.-~aN.~..G C
N c?~DCC? ,OOCi00 __ .. .
o ~ ~ w ~ ~ ~ ~ o o ~ a c o o a Q o 0 0 ~
U
--. re o., c ~ U ~ U x ~ ~3 U O' sx f-~
0 0 ° 'M a V U ~ '~ a C~ U o C. ~ F-~ F~ H E~ k~ E~ F~ E
m a° .~ ... '°~ ~_ a ~a_9 "~s o ~~ '~0~0 ~ ~C
E~ ~-.1 C/7 b'~J
Z~J
It was also determined that photochemical degradation of pentachlorophenol under sunlight, through a regular w~.ndow glass filter, a7.lowed t~h,e accumulation of zntermediatesJproduuts in some cases. In additic~z~ to the products identified prev~.ous3.y, all three zsomers of tetrachlorophenolB, six isomers of tr:ichlorophez~ols, 3,~- .
dichloraphenol, 2,~-dichlorophenol (and/ox 2,S~dichlorophenol, 2,4- and 2,5,dichlc~rophenols have the same retention time on GC arid could not be distinguxshed7 , a dichlorodihydrt~xybenzene ~.0 and a trichlorodihydroxybenzene were detected, as shown below according to the fo:~lowing scheme.
H H YI
~ CI
a .
°' °~ (a21 ,aix ieamera) (andlor a.s-nC~>
.- ~ (aft). ' a o ch oy (a11 three isomers7.
~ H ~H OH
ZL
Q ~ O' d G n . 0H P COOH
( _ r. cv d cooH
on i ~ .
The dichlorodihydrox~rbenzene and the tx~ichlorodzhydroxybenzene were identified only based on their 2~ mass spectra, as no standards were available. All other products were positively identified by comparing their mass spectra and their retention times with those of standards on two different G~ columns (DB-1 and DB-5). The tetrachlorophenols and tetrachlorohydror~uinQne, tetrachlorocatechol, arid tetrach3.ororesoreinol were present in much larger quantities under filtered sunlight than those of the reaction under direct sunlight.
photodegradation of pentachlorophenol in a slurry of pentachlorophenol-containing sawdust in water was also studied uszng protQporphyrin I~ and methylene blue as sen$itizers.
The results are summarized in Table 5 below.
photochemical treatment of sawdust (1 g~, 27,0100 ppm FCp) in mL 1:1 ethanol/water (volume) in the presence of a sensitizer (l~lOw M) and triethanolarnine (0.02 M) 15 _ PCP Concentration (ppm) Methylene Hlue Protoporphyrin 20 La.guid Phase Sawdust Liquid Phase Sawdust Timethrs) 0 540 27,000 6&7 27,000 ~5 (l, 500 (l, 500) W
2 702 -~ 237 3 170 -- 107 ~ --4 53.5 948 23.2 791 (5I7) f161) 5 12.'7 -- g.3 __ 6 6.0 -- 4.7 __ 7 5.5 -- 6.1 __ 8 4.I 145 4.4 115 (0) (0) *: Data in brackets concentratianof 2,3,4,6-tags the tetrachlorophenol in ppm i~
As can be seen from Table S, pentachlorophenol concentration in both. liquid and solid phase decrease rapid~.y.
lifter eight hours' of irradiation,, only 4 ppm of pentaChlvraphenol remained in the liquid phase, and 115-145 ppm of pentachlorophenol remained in the solid phase.
EXAMPLE 2- PhotodeQradation of Dioxins and ~uran5 The change ix~ the concentration of polychlorinated lp dibenao-p-dioxins and polychlorinated dibenzofurans due to photochemical degradation of pentachlorophenol eras i ryvczsz~ i araf pry T~ho rr~aml t-Q err nx,r,n~n 'hAl r,s.r v r~ T~i,l a ~
z'.
~H
~ d M G ~ O
,.
M
O O
ro ~ ~ a V ~ °M°
. '~ ~ D . _ V
ro U ~ ~y~o~~s°a ° ~ ~'~ ~"~ ~"~
o v°c ,~ ~y, a.
V .°c ~' M oa o 'o ~ ~ ~ ° a w ~ ~d ~ ~ ~ oNO ~ '$ a~ .o ~y ».. .fl °' °~.~'~~°
~'~,~~ ~~,~.~ ~
c: ~ ~ ~" at ,.., x U,~° w°~s.oaa~'a °o.Q
o y ~~ A ~ II ~~ u, W
~ ~ ~ N q 0~., (,~~C,4")q~~~V 0.,~
V ~ r~ et N L~i 5Y q,a «~1 ~ ~ P., O ~r v~
'_~
.
A
o x x o z~ can bP seen from Table 6 that the levels of polychlorinated ciibenzo-p-dioxin$ and polychlorinated dibenzofurans decreased in technical pentach~,oraphenal dramatically after photochemical oxa.dation, with octachlaradibenzo-p-dioxin reduced by over 70~. After photochemical oxidation of pure pentachlorophenol, the levels of octachlorodibenzo-p-dioxin also decreased as shown in Table 6.
Photochemical treatment of toxic wastes is attractive, ZO in that it uses a free energy source, sunlight. A
disadvantage of this pxocess is that the reartians are ofter~
slow, because only a few contaminants can strongly absorb sunlight. L~entaehworophenol has a wea7c absorption peak at around 33p nm, which is a~ the high energy end of sunlight spectrum and is degraded slowly. The use of photosensitiaers and amines has been proved successful . Death pentachloraphenol and polychlorinated dibenzo-p-dioxin/palychlorinated dibenzofuran contaminants are degraded rapidly without the formation of more toxic or more recalcitrant by-products . The:
trace amounts of products/intermed3,ates axe more easily mineralized chemically ar biologically th;~n pentachloraphenal.
Dichlaromaleic acid, tetrachlorocatechQ7,, tetrachlororesorcinol, tetrachloraquinone, and lower chloraphenols have been identified a.s pentachlorophenol photodegradation prad.ucts. Tetrachlorohydroquinone was a~.so detected. The formation of a number of dimeric and trimeric products during photodegradation of aqueous sodium pentachlorophenate solutions have previously been reported by others. However, no such compounds were formed under the reactions descx~.bed above. In the present examples, it was found that the presence of phr~tosensitizers and triethanolamine did not result in an increase in polychlorinated dibenzo-p-diox~.n/polychlorinated dibenzofuran concentration. While it is not desired to be limited by theory, it is thought that this was probably because polychlorinated dibenao,p-dioxins arid pol.ychloradibenzofurara.s were degraded at a rate faster than their formation. f~hile it is not desired to be limited by theory, it is thought that the photasensitizers and triethanolamine apparently xemained unchanged after the photochem~,cal reaction. As a result, when pentachlorophenol-containing sawdust is treated as a slurry, the majority of the sensitizer az~d triethanolamine remains in the liquid phase and thus can be reused.
It was previously found that in the use of solar irradiation for treating soil. contaminated with wood preser~rative wastes in solid phase, both pentachlarophenol and polycyclic aromatic hydrocarbons were degraded. Th,e presenoe of anthracene, a polycyclic aromatic hydrocarbon component of the oil, enhanced the degradation of other coxttponents.
Operation of Preferred Embodime ~s tn embodimezlts of the invention, photodegradation rnay be used to degrade toxic organic chemicals from saZutions thereof, regardless of the source of the contaminanted solutions. Based upon current knowledge, bioremediation alane is not expected to be able to detoxify all the polycyclic aromatic hydrocarbons, pqlyck~lorinated dibenzo-p-dioxins and polychlorinated dibenzofurans from treated poles.
Substantially-complete decox~.tamination of pentachlorophenol-treated poles, by SfE treatment followed by photodegradation can be achieved by using techniques as described in the present application.
Thus, embodiments of this invention provide a process for the photodegradatian of contaminants, especially following e~ctractiøn from wood by the SfE process.
Moreover, embod~.ntenta of this invention provide a process for the photodegradation of chlorinated oxganics without separation from the eontamiz~ated material.
6? Conclusion From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this ixa~rentiow, and without departing from the spirit and scope thereof, can make ~rarious changes and modifications of the invention to adapt it to various usages and conditians.
Consequently, such changes and modifications are properly, equitably, and ~'inte~ded" to ba, within the full range of equivalence of the following claims.
5 2n embodiments of the invention, the photodegradation to ~~wYfl~a H~~ ~~v:~ ~r~~r:~ ~~~~~~;r~rtc may take place i.n a slurry of wood caz5taminated with said contaminants, or the gh4t.odegradation to degrade toxic organic chemicals may take place in a liqu~.d solvent phase.
~) nescription c~f Preferred F~nbodiments Photodegxadation processes embodying the present invention may b~: employed after first e~ttracting the organic to~sic eontami,nants using a supercritical fluid extraction tSFE) disclosed and claimed in copending Canadian patent.
~fl app~.ication No. 2,127,42 to which the reader is directed far details.
~~,ICALS USED
All the chlorophenol and dihydroxychlorobenzene standards z5 were obtained from Fluka. PentachlorophenaX wa.s 99% pure from Aldrich and was used without further purification. Tecrsnical grade pentachloraphenol, manufactured by KMG, was provided by a presexwatxve treating plant. Methylene blue double zinc salt, was acquired from Mathesoxi, Coleman and dell.
20 Fhthalocyaninetetrasulfanate sodium salt was purchased from Porphyrin Products. Protoporphyrin I~ was a gift from Professor David Dolphin, Department of Chemistry, UHC.
Triethanolarnine (99.8%, certified) was purchased from Fishex-Scienta,fic. All solvents were spectral grade (4ML~IISOT,vz,",) 25 from BDH and all other chemicals were of analytical grade.
GENERAL PROCEDURE
EbUIPMEN'T USED
a The GCMS was a VG Trio-1000 system equipped with a 3 Q
meter DB-5 column. The reagent gas for chem~.cal ionization (CI) QCMS was ultra high purity methane. GG-ECD (electron-capture detector.) was carried out on a ~-~p 5890 II GC with a 30 meter DS-1 column. sample injection for the GC-ECD was 20 done by using a HP ~67o autosampler.
Several examples will be described to illustrate photodegradation of organic toxic compounds in accordance with this invention. In each Case, the compounds are placed in solution with a suitable phvtosensiti2ex~.
EXAMPLE 2- Photochemical bec~radaCion of Pentachlorophenol The photochemical degradation of pentachlorophe~aol waa first studied using 1:1 acetonitrile/water (volume) as the Rfl~ VI~51'~ Ta~'1~ d 1 ~'1r-~~ A~.Y c~nc.Ta 1~~1W raoml i-t.
xo Photochemical Dag~radation of Pentachlorophenol (2xlb'3 M? in 1:1 Acetonitrile/Water (volume) in the Presence of Triethanalamine (0.02 M) and Various Sensiti~ers (1x10'3 M) Ph4tosensitizer POTS Mix* Methylene Protoporphyrin Blue IX
lb Time (hours) PCP Con,~ent ratxor~ (fpm) 1 165 91.6 43.2 20 2 71.6 28 1.2 2 3 36 1.6 0 b 4 15 0 a 0 6 3.2 0 0 0 7 1.5 0 0 0 * : A mixture of PCTS (ghthalocyaninatetrasulfanatey , m~ethylene blue, arid protopoxphyri.n IX, each at x ~0"4 M
3.33 As can be seen from Table Z, pentachlorophenol wag rapidly degraded. only pentachlorophenoland trace amounts of tetrachldropheno7a were detested by GCMS after acetic anhydride derivatization. Protopoxphyrin IX was the mast effective photasensitiaer, with methyleneblue only slightly less effective. Over 99~ of the pentachlorophenol was destroyed within two hours using either metklylene blue or protoporphyrin IX as sensitizers.
The reaction was then repeated in 50~ (volume) aqueous ethanol which was cheaper and less toxic than aqueous acetonitrile.
Table 2 shows the results of such photochemical degradation.
T~BLF~ 2 photochemical degradation of Pentachlorophenol (2x10'' M) in 1:1 Acetonitrile/Watex (~crolume) in the Presence of Triethanolamine {0.02 M) arid various Sensitizers (1x10-9 1~) ~. 0 Photosensitizes POTS Methylene Prc~toporphyrin Blue IX
Time (minutes) PCP Concen tration (npm) 3d 229.5 17.0 ~?
60 190 5.5 1.5 90 139 0.25 0 150 75.5 0 0 As can be seen from Table 2, the photochemical destruction of pentachlorophenol in this solvent was fast.
within just ~. hour, over 99~ of the pentachlorophenol was degraded. Protopox~phyrin was again the most effective sensitizes. The differences in the efficiencies of the three 1~
sensitizexs was probably due to thezr different extinction coefficients as shown below in Table 3.
TAHL~ 3 Extinction Coefficient of ~k~ree dyes in 1:1 Ethanol/Water (volume) rye Absorption Maxima (nm) Extinction Coefficient (M'lcm'~j Methy~.ene slue X60 5.8 x ZO°
25 Phthaloeyanine-tetrasulfonate E37 4.0 x 104 3,99 x 10' 20 Proeoporphyrin 2X 378 1.48 x 10~
25 Protoporphyrin has an extinction coefficient almost four times larger than that of phthalocyaninet:etrasulfanate in 54~s ethanol. All three sensitizers absorb light at different wavelengths. ~t was thought that if the three sensitiaers were mixed tdc~ether, they would absorb light efficiently over 3a a wider range of wavelength and therefore would be more efficient in degrading pentachlorophenol than any individual sensitizers. As can be seen from Table Z, the mixture system containing three sensitizers, each at one third of their regular concentrations, was more effective than 35 phthalocyaninetetrasulfonate, but still ~.ess effective than protoporphyrin TX or methylene blue, While it is not desired to be bound by theory, ~.t is believed that this was probably due to the low extinction coefficient of phthalooyaninetetrasulfanate, The formation of by-products from the photochemical degradation of pentach7.orophenol was caz~efully studied by GCMS
analysis of a concentrated extract derivatized with.
diazomethane. Szx products including 2,3,~,6-tetrachZorophenol, tetrachlorohydroquinone, tetrachsoracatechol, tetrachlaroresorainal, and dichZoromaleic acid were detected, These are shown beT_ow.
1~
oh " off cy, cl of o cr w 'CI A 'GI CI ~ ~CI
CI
rl d 1~
1 ~ cl I
a h xHe CI Ci CI q tr OOyN
i cl ~ ''orl a ~ 'a d of 20 AZ1 these groduets were present only in trace amounts as shown below in Table 4. The identities of these product$ were confirmed by their mass spectra, and by co~paring their ~C
retention times with those of sGandarde on two different columns (DB-1 and DB-5) a O ~ r O O in ~ .~., w o O o O C; ~ O o v o a o o ~ c c c o r o r~ o 0 o e~s ~ ~ c~ o °o, ~ ~ c'~.~ ° ~ rev, ~ e'~y, o '~
N O ~-~ C C7 O O ~.-~ G ~ G ~
0 o°,oMr~c~~~ L'~~~n,~e r~ Sri o o ~ ,~., o y o ~ N '~ ' ~ o o 0 0 ~ ~ a o p, ~ef ° O O o C7 Q D O P
C ~.i ~D tP1 Y'f N ~ l'~ ~_ d O Q O O C~ C O O C?
en O C C C ,7,., O ~ e~ D O d G~i h.
OOm.~O, ~.-~aN.~..G C
N c?~DCC? ,OOCi00 __ .. .
o ~ ~ w ~ ~ ~ ~ o o ~ a c o o a Q o 0 0 ~
U
--. re o., c ~ U ~ U x ~ ~3 U O' sx f-~
0 0 ° 'M a V U ~ '~ a C~ U o C. ~ F-~ F~ H E~ k~ E~ F~ E
m a° .~ ... '°~ ~_ a ~a_9 "~s o ~~ '~0~0 ~ ~C
E~ ~-.1 C/7 b'~J
Z~J
It was also determined that photochemical degradation of pentachlorophenol under sunlight, through a regular w~.ndow glass filter, a7.lowed t~h,e accumulation of zntermediatesJproduuts in some cases. In additic~z~ to the products identified prev~.ous3.y, all three zsomers of tetrachlorophenolB, six isomers of tr:ichlorophez~ols, 3,~- .
dichloraphenol, 2,~-dichlorophenol (and/ox 2,S~dichlorophenol, 2,4- and 2,5,dichlc~rophenols have the same retention time on GC arid could not be distinguxshed7 , a dichlorodihydrt~xybenzene ~.0 and a trichlorodihydroxybenzene were detected, as shown below according to the fo:~lowing scheme.
H H YI
~ CI
a .
°' °~ (a21 ,aix ieamera) (andlor a.s-nC~>
.- ~ (aft). ' a o ch oy (a11 three isomers7.
~ H ~H OH
ZL
Q ~ O' d G n . 0H P COOH
( _ r. cv d cooH
on i ~ .
The dichlorodihydrox~rbenzene and the tx~ichlorodzhydroxybenzene were identified only based on their 2~ mass spectra, as no standards were available. All other products were positively identified by comparing their mass spectra and their retention times with those of standards on two different G~ columns (DB-1 and DB-5). The tetrachlorophenols and tetrachlorohydror~uinQne, tetrachlorocatechol, arid tetrach3.ororesoreinol were present in much larger quantities under filtered sunlight than those of the reaction under direct sunlight.
photodegradation of pentachlorophenol in a slurry of pentachlorophenol-containing sawdust in water was also studied uszng protQporphyrin I~ and methylene blue as sen$itizers.
The results are summarized in Table 5 below.
photochemical treatment of sawdust (1 g~, 27,0100 ppm FCp) in mL 1:1 ethanol/water (volume) in the presence of a sensitizer (l~lOw M) and triethanolarnine (0.02 M) 15 _ PCP Concentration (ppm) Methylene Hlue Protoporphyrin 20 La.guid Phase Sawdust Liquid Phase Sawdust Timethrs) 0 540 27,000 6&7 27,000 ~5 (l, 500 (l, 500) W
2 702 -~ 237 3 170 -- 107 ~ --4 53.5 948 23.2 791 (5I7) f161) 5 12.'7 -- g.3 __ 6 6.0 -- 4.7 __ 7 5.5 -- 6.1 __ 8 4.I 145 4.4 115 (0) (0) *: Data in brackets concentratianof 2,3,4,6-tags the tetrachlorophenol in ppm i~
As can be seen from Table S, pentachlorophenol concentration in both. liquid and solid phase decrease rapid~.y.
lifter eight hours' of irradiation,, only 4 ppm of pentaChlvraphenol remained in the liquid phase, and 115-145 ppm of pentachlorophenol remained in the solid phase.
EXAMPLE 2- PhotodeQradation of Dioxins and ~uran5 The change ix~ the concentration of polychlorinated lp dibenao-p-dioxins and polychlorinated dibenzofurans due to photochemical degradation of pentachlorophenol eras i ryvczsz~ i araf pry T~ho rr~aml t-Q err nx,r,n~n 'hAl r,s.r v r~ T~i,l a ~
z'.
~H
~ d M G ~ O
,.
M
O O
ro ~ ~ a V ~ °M°
. '~ ~ D . _ V
ro U ~ ~y~o~~s°a ° ~ ~'~ ~"~ ~"~
o v°c ,~ ~y, a.
V .°c ~' M oa o 'o ~ ~ ~ ° a w ~ ~d ~ ~ ~ oNO ~ '$ a~ .o ~y ».. .fl °' °~.~'~~°
~'~,~~ ~~,~.~ ~
c: ~ ~ ~" at ,.., x U,~° w°~s.oaa~'a °o.Q
o y ~~ A ~ II ~~ u, W
~ ~ ~ N q 0~., (,~~C,4")q~~~V 0.,~
V ~ r~ et N L~i 5Y q,a «~1 ~ ~ P., O ~r v~
'_~
.
A
o x x o z~ can bP seen from Table 6 that the levels of polychlorinated ciibenzo-p-dioxin$ and polychlorinated dibenzofurans decreased in technical pentach~,oraphenal dramatically after photochemical oxa.dation, with octachlaradibenzo-p-dioxin reduced by over 70~. After photochemical oxidation of pure pentachlorophenol, the levels of octachlorodibenzo-p-dioxin also decreased as shown in Table 6.
Photochemical treatment of toxic wastes is attractive, ZO in that it uses a free energy source, sunlight. A
disadvantage of this pxocess is that the reartians are ofter~
slow, because only a few contaminants can strongly absorb sunlight. L~entaehworophenol has a wea7c absorption peak at around 33p nm, which is a~ the high energy end of sunlight spectrum and is degraded slowly. The use of photosensitiaers and amines has been proved successful . Death pentachloraphenol and polychlorinated dibenzo-p-dioxin/palychlorinated dibenzofuran contaminants are degraded rapidly without the formation of more toxic or more recalcitrant by-products . The:
trace amounts of products/intermed3,ates axe more easily mineralized chemically ar biologically th;~n pentachloraphenal.
Dichlaromaleic acid, tetrachlorocatechQ7,, tetrachlororesorcinol, tetrachloraquinone, and lower chloraphenols have been identified a.s pentachlorophenol photodegradation prad.ucts. Tetrachlorohydroquinone was a~.so detected. The formation of a number of dimeric and trimeric products during photodegradation of aqueous sodium pentachlorophenate solutions have previously been reported by others. However, no such compounds were formed under the reactions descx~.bed above. In the present examples, it was found that the presence of phr~tosensitizers and triethanolamine did not result in an increase in polychlorinated dibenzo-p-diox~.n/polychlorinated dibenzofuran concentration. While it is not desired to be limited by theory, it is thought that this was probably because polychlorinated dibenao,p-dioxins arid pol.ychloradibenzofurara.s were degraded at a rate faster than their formation. f~hile it is not desired to be limited by theory, it is thought that the photasensitizers and triethanolamine apparently xemained unchanged after the photochem~,cal reaction. As a result, when pentachlorophenol-containing sawdust is treated as a slurry, the majority of the sensitizer az~d triethanolamine remains in the liquid phase and thus can be reused.
It was previously found that in the use of solar irradiation for treating soil. contaminated with wood preser~rative wastes in solid phase, both pentachlarophenol and polycyclic aromatic hydrocarbons were degraded. Th,e presenoe of anthracene, a polycyclic aromatic hydrocarbon component of the oil, enhanced the degradation of other coxttponents.
Operation of Preferred Embodime ~s tn embodimezlts of the invention, photodegradation rnay be used to degrade toxic organic chemicals from saZutions thereof, regardless of the source of the contaminanted solutions. Based upon current knowledge, bioremediation alane is not expected to be able to detoxify all the polycyclic aromatic hydrocarbons, pqlyck~lorinated dibenzo-p-dioxins and polychlorinated dibenzofurans from treated poles.
Substantially-complete decox~.tamination of pentachlorophenol-treated poles, by SfE treatment followed by photodegradation can be achieved by using techniques as described in the present application.
Thus, embodiments of this invention provide a process for the photodegradatian of contaminants, especially following e~ctractiøn from wood by the SfE process.
Moreover, embod~.ntenta of this invention provide a process for the photodegradation of chlorinated oxganics without separation from the eontamiz~ated material.
6? Conclusion From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this ixa~rentiow, and without departing from the spirit and scope thereof, can make ~rarious changes and modifications of the invention to adapt it to various usages and conditians.
Consequently, such changes and modifications are properly, equitably, and ~'inte~ded" to ba, within the full range of equivalence of the following claims.
Claims (8)
1. A process for photodegrading organic toxic chemicals which process comprises the steps of:
providing a solution of said organic toxic chemicals, a solvent and a photosensitizing amount of a photosensitizer which is selected from the group consisting of a porphyrin, a phthalocyanine and mixtures thereof; and exposing said solution to radiation which is selected from the group consisting of UV and sunlight.
providing a solution of said organic toxic chemicals, a solvent and a photosensitizing amount of a photosensitizer which is selected from the group consisting of a porphyrin, a phthalocyanine and mixtures thereof; and exposing said solution to radiation which is selected from the group consisting of UV and sunlight.
2. The process according to claim 1, wherein said organic toxic chemicals are selected from a group consisting of pentachlrophenol, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and combinations thereof.
3. The process according to claim 1 or claim 2, wherein said porphyrin is protoporphyrin IX,
4. The process according to claim 1 or claim 2, wherein said phthalocyanine is phthalocyaninetetrasulfonate.
5. The process according to any one of claims 1 to 4, wherein said photodegradation takes place in the presence of an amine.
6. The process according to claim 5, wherein said amine is triethanolamine.
7. The process according to any one of claims 1 to 6, wherein said solvent. is a water-miscible solvent.
8. The process of according to claim 7, wherein said water-miscible solvent is selected from the group consisting of acetonitrile, methanol and ethanol.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002127242A CA2127242C (en) | 1994-06-30 | 1994-06-30 | Extraction of toxic organic contaminants from wood |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002127242A Division CA2127242C (en) | 1994-06-30 | 1994-06-30 | Extraction of toxic organic contaminants from wood |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2479571A1 CA2479571A1 (en) | 1995-12-31 |
| CA2479571C true CA2479571C (en) | 2006-08-01 |
Family
ID=4153940
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002127242A Expired - Lifetime CA2127242C (en) | 1994-06-30 | 1994-06-30 | Extraction of toxic organic contaminants from wood |
| CA002479571A Expired - Lifetime CA2479571C (en) | 1994-06-30 | 1994-06-30 | Photodegradation of toxic organic contaminants |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002127242A Expired - Lifetime CA2127242C (en) | 1994-06-30 | 1994-06-30 | Extraction of toxic organic contaminants from wood |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA2127242C (en) |
-
1994
- 1994-06-30 CA CA002127242A patent/CA2127242C/en not_active Expired - Lifetime
- 1994-06-30 CA CA002479571A patent/CA2479571C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2479571A1 (en) | 1995-12-31 |
| CA2127242A1 (en) | 1995-12-31 |
| CA2127242C (en) | 2006-12-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5698829A (en) | Photodegradation of toxic contaminants | |
| Vallejo et al. | Overview of the PCDD/Fs degradation potential and formation risk in the application of advanced oxidation processes (AOPs) to wastewater treatment | |
| CA1150309A (en) | Reagent and method for decomposing halogenated organic compounds | |
| Glaze | Reaction products of ozone: a review. | |
| EP0373268B1 (en) | Oxidation of organic compounds in water | |
| EP0480474B1 (en) | Method for removing polyclorinated dibenzodioxins and polychlorinated dibenzofurans from paper mill sludge | |
| Kearney et al. | UV-ozonation of eleven major pesticides as a waste disposal pretreatment | |
| Freshour et al. | Two-phase ozonation of hazardous organics in single and multicomponent systems | |
| Taylor Jr et al. | Dissolved organic matter inhibition of sonochemical degradation of aqueous polycyclic aromatic hydrocarbons | |
| US4602994A (en) | Removal of PCBs and other halogenated organic compounds from organic fluids | |
| Isosaari et al. | Use of olive oil for soil extraction and ultraviolet degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans | |
| CA2006825C (en) | Method for the destruction of halogenated organic compounds in a contaminated medium | |
| EP1980296B1 (en) | Method for purification of substances contaminated with organic chemicals | |
| EP0733594A1 (en) | Process for removing noxious compounds | |
| US5196617A (en) | Method of hydrodehalogenating halogenated organic compounds in aqueous environmental sources | |
| CA2479571C (en) | Photodegradation of toxic organic contaminants | |
| EP0732156A1 (en) | A process to decontaminate soil containing chlorophenols | |
| Tiernan et al. | Laboratory and field tests to demonstrate the efficacy of KPEG reagent for detoxification of hazardous wastes containing polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) and soils contaminated with such chemical wastes | |
| JP4224597B2 (en) | Purification method of waste water containing harmful organic substances | |
| EP1123720B1 (en) | Organic compound decomposing method | |
| JP2778715B2 (en) | Method of oxidizing organic compounds in water | |
| Montemagno et al. | Investigations involving oxidation-reduction (REDOX) pretreatment in conjunction with biological remediation of contaminated soils | |
| Higarashi et al. | Photocatalytic treatment of pesticide-contaminated soil using solar light and titanium dioxide | |
| Lebedeva et al. | Degradation of several chlorophenols using advanced oxidative processes: Major and minor products | |
| Benitez et al. | UV photodegradation of phenolic aldehydes present in industrial wastewaters. II. Simultaneous degradation of a mixture |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20140630 |