U.S. patent application number 15/055938 was filed with the patent office on 2016-06-23 for method for purification of substances contaminated with organic chemicals.
This patent application is currently assigned to OSAKA UNIVERSITY. The applicant listed for this patent is ESRI CO. LTD., OSAKA UNIVERSITY. Invention is credited to Kazumasa Hirata, Kazuhisa Miyamoto, Hiroyasu Nagase, Hiroshi Saito.
Application Number | 20160176726 15/055938 |
Document ID | / |
Family ID | 38217996 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160176726 |
Kind Code |
A1 |
Nagase; Hiroyasu ; et
al. |
June 23, 2016 |
METHOD FOR PURIFICATION OF SUBSTANCES CONTAMINATED WITH ORGANIC
CHEMICALS
Abstract
The present invention provides a method for purifying organic
chemical-containing contaminated substances by which various
organic chemicals (contaminants) can be readily and sufficiently
decomposed in a short time, the method comprising the steps of
adding a metal salt and a transition metal ionic compound to water
or soil that contains organic chemicals, decomposing the organic
chemicals by irradiating with light, and separating/collecting the
detoxified organic chemicals.
Inventors: |
Nagase; Hiroyasu; (Osaka,
JP) ; Miyamoto; Kazuhisa; (Osaka, JP) ;
Hirata; Kazumasa; (Osaka, JP) ; Saito; Hiroshi;
(Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OSAKA UNIVERSITY
ESRI CO. LTD. |
Osaka
Osaka |
|
JP
JP |
|
|
Assignee: |
OSAKA UNIVERSITY
Osaka
JP
ESRI CO. LTD.
Osaka
JP
|
Family ID: |
38217996 |
Appl. No.: |
15/055938 |
Filed: |
February 29, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12159497 |
Jun 1, 2010 |
9309164 |
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PCT/JP2006/325791 |
Dec 25, 2006 |
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15055938 |
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Current U.S.
Class: |
204/157.69 |
Current CPC
Class: |
C07B 63/04 20130101;
C02F 2101/36 20130101; C07B 37/06 20130101; A62D 2101/28 20130101;
B09C 1/08 20130101; C02F 2101/30 20130101; A62D 2101/08 20130101;
C02F 2305/10 20130101; A62D 2101/20 20130101; C02F 1/32 20130101;
C02F 2101/345 20130101; C07D 319/24 20130101; A62D 2101/22
20130101; Y02W 10/37 20150501; C02F 2101/305 20130101; A62D 3/176
20130101 |
International
Class: |
C02F 1/32 20060101
C02F001/32; B09C 1/08 20060101 B09C001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2005 |
JP |
2005-379246 |
Claims
1-18. (canceled)
19. A method for purifying an aromatic compound-containing
contaminated substance comprising: a first step of irradiating the
aromatic compound-containing contaminated substance with light in
the presence of (i) at least one water-soluble alkali metal
compound and/or at least one water-soluble alkaline-earth metal
compound selected from the group consisting of calcium compounds,
magnesium compounds, potassium compounds, and sodium compounds, and
(ii) iron compound, whereby the aromatic compound is polymerized,
wherein iron becomes ions in an aqueous solution, and a second step
of collecting the polymerized aromatic compound that is generated
in the first step.
20. The method according to claim 1, wherein the first step
comprises the steps of: (1) a step of adding the compound (i), and
the compound (ii); and (2) a step of irradiating a mixture obtained
in the first step with light.
21. The method according to claim 1, wherein the method further
comprises a step of separating the polymerized aromatic compound
between the first step and the second step.
22. The method according to claim 1, wherein at least one of the
compounds (i) and (ii) is adhered to a carrier.
23. The method according to claim 1, wherein a compound comprising
the compound (ii) adhered to the compound (i) is used as compounds
(i) and (ii).
24. The method according to claim 1, wherein the compound (i) is
dolomite.
25. The method according to claim 1, wherein the compound (i) is at
least one member selected from the group consisting of dolomite,
water-soluble compounds of hydroxides, inorganic-acid salts,
organic acid salts and oxides of calcium, magnesium, potassium, and
sodium.
26. The method according to claim 1, wherein the transition metal
ionic compound is at least one compound selected from the group
consisting of ferric chloride, iron nitrate, iron hydroxide, iron
phosphate, iron ethylenediaminetetraacetate, and iron sulfate.
27. The method according to claim 1, wherein the aromatic compound
is at least one member selected from the group consisting of a
polychlorinated biphenyl (PCB), dioxin, o-chlorophenol,
p-chlorophenol, 2,4-dichlorophenol, p-tert-butylphenol, 1-naphthol,
3,5-xylenol, carbendazim, 17[beta]-estradiol, and bisphenol A.
28. The method according to claim 1, wherein the light used for
light irradiation is ultraviolet.
29. The method according to claim 1, wherein the aromatic
compound-containing contaminated substance is at least one member
selected from the group consisting of factory effluents,
agricultural effluents, domestic drainage, sewage, leachate from
waste disposal sites, exhaust gases, contaminated soil, sludge, and
incinerated ash.
30. A method for purifying an aromatic compound-containing
contaminated substance wherein the method comprises the steps of:
(I) irradiating the aromatic compound-containing contaminated
substance with light in the presence of (i) at least one
water-soluble alkali metal compound and/or at least one
water-soluble alkaline-earth metal compound selected from the group
consisting of calcium compounds, magnesium compounds, potassium
compounds, and sodium compounds; and then (II) adding (ii) iron
compounds, whereby the aromatic compound is polymerized, wherein
iron becomes ions in an aqueous solution, and (III) collecting the
polymerized aromatic compound that is generated in step (II).
31. The method according to claim 12, wherein the method further
comprises (IV) separating the polymerized aromatic compound
contained in contaminated substance between (II) and (III).
32. The method according to claim 12, wherein at least one of the
compounds (i) and (ii) is adhered to a carrier.
33. The method according to claim 12, wherein the compound (i) is
dolomite.
34. The method according to claim 12, wherein the compound (i) is
at least one member selected from the group consisting of dolomite,
water-soluble compounds of hydroxides, inorganic-acid salts,
organic acid salts and oxides of calcium, magnesium, potassium, and
sodium.
35. The method according to claim 12, wherein the transition metal
ionic compound is at least one compound selected from the group
consisting of ferric chloride, iron nitrate, iron hydroxide, iron
phosphate, iron ethylenediaminetetraacetate, and iron sulfate.
36. The method according to claim 12, wherein the aromatic compound
is at least one member selected from the group consisting of a
polychlorinated biphenyl (PCB), dioxin, o-chlorophenol,
p-chlorophenol, 2,4-dichlorophenol, p-tert-butylphenol, 1-naphthol,
3,5-xylenol, carbendazim, 17[beta]-estradiol, and bisphenol A.
37. The method according to claim 12, wherein the light used for
light irradiation is ultraviolet.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for purifying an
organic chemical-containing contaminated substance conducted in the
presence of at least one water-soluble alkali metal compound and/or
at least one alkaline-earth metal compound, and at least one
transition metal ionic compound. The present invention also relates
to a system for purifying an organic chemical-containing
contaminated substance.
BACKGROUND OF THE INVENTION
[0002] In recent years, environmental pollution caused by organic
chemicals has become a concern in many parts of the world. In
particular, many aromatic compounds possess biotoxicity,
carcinogenicity, mutagenicity, endocrine disrupting activity, etc.,
and therefore their influence on human beings and ecosystems causes
concern.
[0003] In order to prevent environmental pollution caused by
organic chemicals, various laws and regulations have been enforced,
but no satisfactory effect has yet been achieved. One of the
probable causes of such pollution is the discharge of industrial
and domestic drainage, leachate from landfills, etc., without
having been satisfactorily purified. To prevent such environmental
pollution, it is necessary to satisfactorily purify polluted
drainage, etc., before discharging it into the surroundings.
[0004] Examples of organic chemicals that may cause environmental
pollution include alkylphenols, bisphenol A, dioxin, PCBs, etc.
They are difficult to decompose, exhibit endocrine disrupting
activity, and adversely affect human beings and ecosystems even at
low concentrations.
[0005] Examples of methods for decomposing and/or removing such
organic chemicals (also referred to herein as contaminants) include
biological methods utilizing microorganisms (for example,
Non-patent Document 1), physical methods utilizing activated carbon
and like adsorbents (for example, Non-patent Document 2), chemical
methods wherein organic chemicals are decomposed by being
irradiated with ultraviolet light (for example, Non-patent Document
3), etc. However, using biological methods, it is difficult to
decompose a variety of contaminants with a single microorganism,
and therefore a microorganism suitable for each contaminant has to
be found. Moreover, even if suitable microorganisms are obtained,
it is necessary to create the conditions in which the
microorganisms can exhibit sufficient decomposition ability in
actual practice. Furthermore, since a microorganism can decompose a
contaminant only slowly, there is a problem in that the
decomposition and removal of the contaminant takes time. In
contrast, using physical methods, although various contaminants can
be adsorbed, a separate step for treating the collected
contaminants becomes necessary. Using chemical methods, organic
chemicals are decomposed only at a slow rate when using a mild
method and some organic chemicals cannot be decomposed at all
depending on the type thereof, and therefore the use of toxic
chemicals (oxidants, strong acids, etc.) is necessary to accelerate
the decomposition of such organic chemicals.
[0006] In view of such circumstances, a method for decomposing
and/or removing contaminants in which various contaminants can be
safely and readily treated in a short time is being sought. [0007]
[Non-patent Document 1] World Journal of Microbiology &
Biotechnology, 20, 517-522 (2004) [0008] [Non-patent Document 2]
Chemosphere, 58, 1535-1545 (2005) [0009] [Non-patent Document 3]
Journal of Hazardous Materials, B101, 301-314 (2003).
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0010] One of main objects of the present invention is to provide a
simple method for purifying organic chemical-containing
contaminated substances by which various organic chemicals
(contaminants) can be readily and sufficiently decomposed in a
short time, and a system for purifying organic chemical-containing
contaminated substances.
Means for Solving the Problem
[0011] The present inventors found that, by adding a specific metal
compound and a transition metal ionic compound to organic chemicals
(contaminants) and subjecting the resultant mixture to light
irradiation, contaminants can be effectively decomposed, and the
organic chemicals become insoluble to form solid matter (insoluble
matter from the decomposed organic chemicals) that can be easily
removed. Methods for decomposing contaminants by irradiating light
(ultraviolet light irradiation) are known; however, the facts that
the decomposition speed of various contaminants remarkably improves
and contaminants that cannot be decomposed by conventional
techniques can be decomposed by adding specific a metal
compound(s), and insolubilization of the decomposed organic
chemicals can be promoted by adding a transition metal ionic
compound(s) such as cobalt chloride, etc., are newly found by the
present inventors. The present invention has been accomplished
based on the above findings and by conducting further intensive
research.
[0012] The present invention provides methods for purifying organic
chemical-containing contaminated substances and a system for
purifying organic chemical-containing contaminated substances as
below.
Item 1. A method for purifying an organic chemical-containing
contaminated substance comprising a step of irradiating the organic
chemical-containing contaminated substance with light in the
presence of (i) at least one water-soluble alkali metal compound
and/or at least one alkaline-earth metal compound, and (ii) at
least one transition metal ionic compound. Item 2. The method
according to Item 1, which comprises a first step of adding (i) at
least one water-soluble alkali metal compound and/or at least one
alkaline-earth metal compound, and (ii) at least one transition
metal ionic compound to an organic chemical-containing contaminated
substance; and a second step of irradiating a mixture obtained in
the first step with light. Item 3. The method according to Item 1,
wherein said at least one water-soluble alkali metal compound
and/or said at least one alkaline-earth metal compound is at least
one member selected from the group consisting of calcium,
magnesium, potassium, and sodium. Item 4. The method according to
Item 1, wherein at least one of the compounds (i) and (ii) is
adhered to a carrier. Item 5. The method according to Item 1,
wherein a compound comprising the compound (ii) adhered to the
compound (i) is used as compounds (i) and (ii). Item 6. The method
according to Item 1, wherein the compound (ii) is at least one
compound of a transition metal selected from the group consisting
of cobalt, manganese, iron, nickel, copper, and zinc. Item 7. The
method according to Item 1, which further comprises a third step of
separating insoluble matter generated from the organic chemical
after irradiating the organic chemical-containing contaminated
substance with light. Item 8. The method according to Item 1,
wherein the compound (i) is dolomite. Item 9. The method according
to Item 1, wherein the organic chemical is an endocrine disruptor
or an agricultural chemical. Item 10. The method according to Item
1, wherein the organic chemical is an organochlorine compound or an
aromatic compound. Item 11. The method according to Item 1, wherein
the organic chemical is a polychlorinated biphenyl (PCB) or dioxin.
Item 12. The method according to Item 1, wherein the organic
chemical is at least one member selected from the group consisting
of o-chlorophenol, p-chlorophenol, 2,4-dichlorophenol,
p-tert-butylphenol, 1-naphthol, 3,5-xylenol, carbendazim,
17.beta.-estradiol and bisphenol A. Item 13. The method according
to Item 1, wherein Compound (i) is added to a contaminated
substance in such a manner that the concentration of Compound (i)
is 0.00005-50 wt % calculated as a metallic salt unit. Item 14. The
method according to Item 1, wherein Compound (ii) is added to a
contaminated substance in such a manner that the concentration of
Compound (ii) is 0.01 to 10 mM. Item 15. The method according to
Item 1, wherein the light used for light irradiation is
ultraviolet. Item 16. The method according to Item 1, wherein the
organic chemical-containing contaminated substance is at least one
member selected from the group consisting of factory effluents,
agricultural effluents, domestic drainage, sewage, leachate from
waste disposal sites, exhaust gases, contaminated soil, sludge and
incinerated ash. Item 17. A method for purifying an, organic
chemical-containing contaminated substance comprising the steps
of:
[0013] (I) irradiating the organic chemical-containing contaminated
substance with light in the presence of (i) at least one
water-soluble alkali metal compound and/or at least one
alkaline-earth metal compound; and then
[0014] (II) adding (ii) at least one transition metal compound.
Item 18. The method according to Item 17, which further comprises a
third step of separating and collecting insoluble matter generated
from the organic chemical after conducting steps (I) and (II). Item
19. A system for purifying an organic chemical-containing
contaminated substance comprising:
[0015] a photoreaction reactor for irradiating an organic
chemical-containing contaminated substance with light in the
presence of at least one water-soluble alkali metal compound and/or
at least one alkaline-earth metal compound, and at least one
transition metal ionic compound.
Item 20. The system according to Item 19, which further comprises
separation and collection equipment for separating and collecting
insoluble matter generated in the photoreaction reactor.
Effect of the Invention
[0016] Because a wide variety of contaminants can be treated under
the same conditions, the method for purifying organic
chemical-containing contaminated substances of the present
invention is very useful for purifying water, soil, etc.,
containing various kinds of organic chemicals. In the method for
purifying organic chemicals of the present invention, because the
decomposition speed is very fast, organic chemicals can be treated
in a short time, and therefore this method can be suitably employed
to reduce the size of a purification system, to treat large amounts
of waste water, etc. Furthermore, because decomposed organic
chemicals can be separated and collected as insoluble matter in the
method of the present invention, it can be concluded that the
method of the present invention is excellent in removing organic
chemicals, which are contamination sources of contaminated
substances, and usable as a method for purifying contaminated
substances.
[0017] The method of the present invention is different from known
methods in that it does not mineralize organic chemicals, but
polymerizes and insolubilizes the decomposed organic chemicals to
make them easily collected, and achieves an excellent collection
rate.
[0018] Furthermore, if the concentration of the organic chemicals
contained in contaminated substance is low, it is difficult or
impossible to purify the contaminated substance by known methods.
However, the method of the invention can sufficiently purify even
such a contaminated substance, and therefore it can be suitably
used for purifying various contaminated substances.
[0019] Dolomite can be used in the method of the present invention
as a mixture of (i) water-soluble alkali metal compounds and/or
alkaline-earth metal compounds. Dolomite hitherto has been used as
foodstuffs, fertilizers, etc., and its safety is confirmed.
Furthermore, because dolomite can be easily obtained at low cost,
the present invention can provide an inexpensive purification
system.
[0020] As described above, the method for purifying organic
chemical-containing contaminated substances of the present
invention is very simple, safe, highly practicable, and excellent
in purifying water, soil and like contaminated substances.
BEST MODE FOR CARRYING OUT THE INVENTION
1. Method for Purifying Organic Chemical-Containing Contaminated
Substances
[0021] The present invention encompasses the following methods. A
first method is characterized in irradiating an organic
chemical-containing contaminated substance with light in the
presence of (i) at least one water-soluble alkali metal compound
and/or at least one alkaline-earth metal compound, and (ii) at
least one transition metal ionic compound.
[0022] A second method is characterized in irradiating the organic
chemical-containing contaminated substance with light in the
presence of (i) at least one water-soluble alkali metal compound
and/or at least one alkaline-earth metal compound; and then adding
(ii) at least one transition metal compound.
[0023] The first and second methods are explained in detail
below.
[First Method]
[0024] In the First method of the present invention, light
irradiation is conducted under the presence of (i) at least one
water-soluble alkali metal compound and/or at least one
alkaline-earth metal compound, and (ii) at least one transition
metal ionic compound.
[0025] The method for purifying organic chemical-containing
contaminated substances of the present invention primarily
comprises the following two steps:
[0026] (1) a first step of adding (i) at least one water-soluble
alkali metal compound and/or at least one alkaline-earth metal
compound (this may referred to as Compound (i)), and (ii) at least
one transition metal ionic compound (this may referred to as
Compound (ii)) to an organic chemical-containing contaminated
substance, and mixing them if necessary; and
[0027] (2) a second step of irradiating the mixture obtained in the
first step with light.
[0028] A third step (3), wherein insolubilized organic chemicals
are separated and collected, may follow the above-mentioned two
steps, if necessary.
[0029] The method for purifying organic chemicals of the present
invention is described in detail below.
(1) First Step
[0030] In the first step, Compound (i) and Compound (ii) are added
to a contaminated substance, which is contaminated with at least
one organic chemical. In this step, it is preferable to mix
Compound (i) and Compound (ii) with the organic chemical-containing
contaminated substance during or before irradiation of light.
(i) Water-Soluble Alkali Metal Compound and/or at Least One
Alkaline-Earth Metal Compound
[0031] Compound (i) usable in the present invention comprises an
alkali metal or an alkali-earth metal and is water soluble.
Specifically, Compound (i) includes hydroxides, inorganic-acid
salts, organic acid salts, oxides, etc., of calcium, magnesium,
potassium, and sodium.
[0032] Specific examples of Compound (i) include calcium hydroxide,
magnesium hydroxide, potassium hydroxide, sodium hydroxide and like
hydroxides; calcium nitrate, calcium carbonate, magnesium nitrate,
magnesium carbonate, potassium nitrate, potassium carbonate, sodium
nitrate, sodium carbonate and like inorganic-acid salts; calcium
acetate, magnesium acetate, potassium acetate, sodium acetate,
calcium citrate, magnesium citrate, potassium citrate, sodium
citrate and like organic-acid salts; and calcium oxide, magnesium
oxide, potassium oxide, sodium oxide and like oxides.
[0033] Among these metal compounds, calcium hydroxide, calcium
oxide, calcium carbonat, magnesium hydroxide, magnesium oxide,
magnesium carbonate, potassium hydroxide, and sodium hydroxide are
preferable from a viewpoint of effective organic chemical
decomposition.
[0034] The above-mentioned metal compounds may be used singly or in
combination. Natural minerals may be used as Compound (i), and
dolomite is an example of such a natural mineral.
[0035] Dolomite may also be called as magnesian limestone that is a
mixture comprising calcium and magnesium as principal components.
Dolomite contains calcium carbonate, magnesium carbonate, calcium
oxide, magnesium oxide, calcium hydroxide, magnesium hydroxide,
etc. The proportions of these constitutional components in the
present invention are not limited, and any natural dolomite can be
used without modification. Natural dolomite generally contains
about 30 wt % calcium, and about 15 wt % magnesium, and the amount
of dolomite used is suitably selected based on the contents of
these metals.
[0036] It is also possible to use processed dolomite obtained by
calcining, hydrating and/or aging natural dolomite. Examples of
such processed dolomite include soft-burned dolomite, digested
dolomite, dolomite clinker, dolomite plaster, magnesium calcium
carbonate, etc.
[0037] The content of Compound (i) used in the present invention
may be suitably adjusted so that the effects of the present
invention may be attained, but it is preferable that Compound (i)
be added in such a manner that the content of the metal compound(s)
during the purification process, i.e., when Compound (i) and
Compound (ii) are added to a contaminated substance, is generally
about 0.00005-50 wt %, and preferably about 0.001-30 wt %
calculated as a metallic compound unit. If the content of Compound
(i) falls within an above range, all of Compound (i) does not have
to be dissolved in water and a portion thereof may exist in a form
of solid matter or particles that are insoluble in water. In the
case of dolomite, it is preferable that the dolomite be mixed with
organic chemicals in such a manner that the content of dolomite
while irradiating with light is generally about 0.0005-10 wt %, and
preferably about 0.01-1 wt %. If the content of Compound (i) or
dolomite falls within an above range, wide variety of organic
chemicals can be efficiently decomposed.
(ii) Transition Metal Ionic Compound
[0038] In the present invention, "transition metal ionic compounds"
means metal compounds in which a transition metal becomes ions in
an aqueous solution or an aqueous solution of Compound (i).
[0039] Various known transition metal ionic compounds can be used
in the present invention including manganese, iron, cobalt, nickel,
copper, zinc, etc. Among these, cobalt and iron are preferable.
Examples of compounds of these metals include cobalt chloride,
cobalt bromide, cobalt sulfate, cobalt nitrate, cobalt hydroxide,
cobalt carbonate, cobalt phosphorate, cobalt acetate, cobalt
ethylenediaminetetraacetate, ferric chloride, iron sulfate, iron
nitrate, iron hydroxide, iron phosphorate, iron
ethylenediaminetetraacetate, etc. Among these compounds, cobalt
chloride, cobalt sulfate, cobalt nitrate, ferric chloride, iron
sulfate, and iron nitrate are preferable.
[0040] The content of the transition metal ionic compound used in
the present invention may be suitably adjusted so that the effects
of the present invention can be attained, but it is preferable that
the transition metal ionic compound be added in such a manner that
the content of transition metal ionic compound during the
purification process, i.e., when Compound (i) and Compound (ii) are
added to a contaminated substance, is generally about 0.01-10 mM,
and preferably about 0.1-1 mM. If the content of transition metal
ionic compound falls within an above range, a variety of organic
chemicals can be efficiently decomposed.
[0041] In the present invention, either or both of Compound (i) and
Compound (ii) may be adhered to a carrier such as ceramics,
activated carbon, etc.
[0042] Instead of using Compound (i) with Compound (ii), it is also
possible to use a compound wherein Compound (ii) is adhered to
Compound (i).
Organic Chemical-Containing Contaminated Substance
[0043] The organic chemicals to be decomposed by the method of the
present invention are organic chemicals that cause environmental
pollution. Examples of such organic chemicals include endocrine
disruptors, agricultural chemicals, etc. Specific examples of
endocrine disruptors include polychlorinated dibenzo-p-dioxin
(PCDD), polychlorinated dibenzofuran (PCDF) and like dioxins;
coplanar polychlorinated biphenyl and like polychlorinated
biphenyls (PCBs); organochlorine compounds such as o-chlorophenol,
p-chlorophenol, 2,4-dichlorophenol and like chlorophenols;
p-tert-butylphenol, 3,5-xylenol and like alkylphenols; bisphenol A,
1-naphthol and like aromatic compounds; 17.beta.-estradiol and like
natural female hormones, etc. Examples of agricultural chemicals
include 2,4-dichlorophenoxyacetic acid (2,4-D), carbendazim,
etc.
[0044] In particular, o-chlorophenol, 2,4-dichlorophenol,
p-tert-butylphenol, 1-naphthol, 3,5-xylenol, bisphenol A,
17.beta.-estradiol, carbendazim, etc., have extremely low
decomposition rate when only conventional ultraviolet light
irradiation is employed. However, by conducting light irradiation
after adding Compound (i), the decomposition efficiency is
significantly improved and the decomposition rate is therefore
increased. Furthermore, in the method of the present invention, by
adding a transition metal ionic compound as well as Compound (i),
insolubilization of the decomposed organic chemicals is
facilitated, and insoluble matter having a size easily filtered out
is generated. In the present invention, insoluble matter means
solid matter that is insoluble in water formed from insolubilized
organic chemicals by being irradiated with light, and includes
flotage, precipitates, etc.
[0045] There is no limitation to the form of the above-mentioned
organic chemicals, and they may be contained in, for example,
soils; sludge, incinerated ashes; waters such as industrial and
domestic drainage, sewage, rivers, leachate from landfills (water
that has seeped from soil in waste disposal sites), etc.;
agricultural products and like foodstuffs; exhaust gases; waste
generated in a space station, etc.
[0046] The organic chemical is mixed with Compound (i) (and a
transition metal ionic compound), and, preferably, agitated to make
a homogeneous mixture. Water may be added to the mixture, if
necessary. The amount of water added is not limited and can be
suitably selected depending on the amount and state of the
contaminated substance that contains organic chemicals, and the
amounts of Compound (i) (and the transition metal ionic
compound).
[0047] The method of the present invention can sufficiently purify
the contaminated substance in wide concentration range of the
organic chemicals between about 0.1 nM and about 1 M.
[0048] It is difficult or impossible to purify a contaminated
substance by known methods if the concentration of the organic
chemicals contained therein is unduly low. However, the method of
the present invention is also effective even if the concentration
of the organic chemicals is very low.
(2) Second Step
[0049] In the second step, the mixture obtained in the first step
is irradiated with light.
Light Irradiation
[0050] A mixture such as an aqueous solution, slurry, etc.,
obtained in the (1) first step is irradiated with light. The light
used is not limited as long as it can irradiate the mixture. There
is no limitation to the irradiation area, etc., but total
irradiation is more advantageous as this makes the decomposition
reaction progress more efficiently. In order to uniformly irradiate
the mixture with light, the mixture may be agitated while
irradiating with light, or the light irradiation may be conducted
in a reactor, etc. The light irradiation may be conducted at room
temperature or ambient temperature for about 0.1 second to about 24
hours, preferably about 1 second to about 10 hours, more preferably
about 10 seconds to about 3 hours.
[0051] Ultraviolet light is the most appropriate for use in light
irradiation. There is no limitation to such types of light source
as long as they emit ultraviolet light. Examples of the light
sources include sunlight and like natural lights; and fluorescent
light, germicidal lamp, mercury lamp, deuterium lamp, xenon lamp,
halogen lamp, tungsten lamp, LED and like artificial lights.
[0052] The intensity of irradiation light varies depending on the
type of the light. There is no particular limit to the intensity of
irradiation light; however it is generally about 0.1 mWcm.sup.-2 or
more. The more intense the light would be the better. For example,
when ultraviolet light is used, generally about 0.1 mWcm.sup.-2 or
more, preferably about 0.1 to about 1000000 mWcm.sup.-2, more
preferably about 1 to about 1000000 mWcm.sup.-2.
(3) Third Step
[0053] The insoluble matter generated in the second step may be
separated and collected in a third step.
Separation/Collection
[0054] In the present invention, by adding an ionic transition
metal, organic chemicals can be insolubilized to form insoluble
matter from the detoxified organic chemicals, and therefore it is
also possible to separate and collect the thus-formed insoluble
matter.
[0055] Known apparatuses and methods can be used for
separating/collecting such insoluble matter, and a dust collector,
column, filtration apparatus, cyclone, centrifugal separator, etc.,
can be suitably selected depending on the status of the
contaminated substance.
[Second Method]
[0056] Furthermore, the present invention also provides a
purification method comprising the following steps:
[0057] (i) irradiating the organic chemical-containing contaminated
substance with light in the presence of at least one water-soluble
alkali metal compound and/or at least one alkaline-earth metal
compound (this step may be referred to as Step (I)); and
[0058] (ii) adding at least one transition metal ionic compound
after conducting Step (I) (this step may be referred to as Step
(II)).
[0059] The types of Compound (i) used in Step (I), types of
contaminated substance, types of organic chemical, conditions for
light irradiation, etc., are the same as those in the
above-explained First method. The amount of Compound (i) are the
same as the amount of Compound (i) added to contaminated substance
as described in First method above.
[0060] The amounts and types of Compound (ii) used in Step (II) are
the same as those in the above-explained First method.
[0061] In Step (II) of the second method, Compound (ii) is added to
Compound (i) and an organic chemical-containing contaminated
substance after irradiation. These components are mixed if
necessary, and then treated at room temperature or ambient
temperature for about 0.1 second to about 24 hours, preferably
about 1 second to about 10 hours, more preferably about 10 seconds
to about 3 hours. The mixture may be agitated or heated to
accelerate the reaction, if necessary during the treatment thereby
the organic chemicals is insolubilized.
[0062] Likewise the First method described above, a third step of
separating/collecting the insolubilized organic chemicals may be
added in the Second method after conducting step II.
Application
[0063] The first and second purification methods of the present
invention can be applied to various contaminated substances such as
water, incinerated ash, soil, sludge, foodstuffs, organic solvents,
oils, exhaust gases, etc.
[0064] For example, in the case of purifying contaminated water,
the contaminated water is stored in a reactor, reservoir, etc., and
Compound (i) (and a transition metal ionic compound) is added
thereto, followed by light irradiation so that the organic
chemicals contained can be decomposed. In the method of the present
invention, insolubilization of the organic chemicals is facilitated
by adding at least one transition metal ionic compound, forming
detoxified insoluble matter. By filtering (separating) this
insoluble matter, organic chemicals can be removed from waste
water. Neutralization of the treated waste water can be readily
conducted by known methods (for example, adding acid, etc.).
[0065] Alternatively, it is possible to decompose the organic
chemicals contained in the contaminated water by passing the
contaminated water through a column filed with Compound (i) (and a
transition metal ionic compound) to obtain an aqueous solution
containing Compound (i) (and the transition metal ionic compound),
and then conducting light irradiation.
[0066] One example of a method for purifying contaminated soil
and/or incinerated ash is that Compound (i) (and a transition metal
ionic compound), and water if necessary, are added to the soil,
etc., to form a slurry, and the thus-formed slurry is irradiated
with light while being agitated in a reactor. In this case, the
decomposed organic chemicals are detoxified and insolubilized,
forming solid matter (insoluble matter). Therefore, insoluble
matter of the decomposed organic chemicals remains in the
post-treated soil but separation is unnecessary.
[0067] In the case of purifying exhaust gases, a solution
containing Compound (i) and a transition metal ionic compound can
be sprayed into the space containing exhaust gas in the presence of
water vapor, and light irradiation is then conducted. It is also
possible to purify exhaust gases by spraying small particles
containing Compound (i) and a transition metal ionic compound into
the space containing the exhausted gas, while agitating air if
necessary, and then conducting light irradiation in the presence of
water vapor. In this case, insoluble matter can be removed using a
dust collector, etc., if necessary. Alternatively, it is possible
to purify the exhausted gas by bubbling it through a solution
containing Compound (i) and a transition metal ionic compound, and
then conducting light irradiation. Insoluble matter is
separated/collected, if necessary.
[0068] Alternatively, it is possible to contact organic
chemical-containing contaminated substance with Compound (i) or
(ii) by, for example, passing an exhausted gas through carriers
supporting either or both Compounds (i) and (ii).
[0069] When the contaminant is a water-insoluble liquid such as
oil, etc., the organic chemical-containing oil can be purified by
emulsifying them with an aqueous solution containing Compound (i)
and a transition metal ionic compound by using a known emulsifier,
emulsification equipment, etc., conducting light irradiation, and
then separating/collecting insoluble matter if necessary.
[0070] An object of applying the technique of the present invention
to agricultural products and like foodstuffs is to remove or
detoxify agricultural chemicals remaining on leaves of vegetables,
fruits, etc. For example, in the case of vegetables grown in
fields, a mixture of Compound (i) and a transition metal ionic
compound is sprayed onto the vegetables. This makes it possible to
decompose the organic chemicals to form insoluble particles when
exposed to sunlight. In this case, insoluble matter from the
organic chemicals can be removed by washing the vegetables.
[0071] By employing the technique of the present invention, the
waste generated in a space station or like space facility can be
handled in space, particularly by using sun light containing ultra
violet light. In many cases, conditions suitable for growing
microorganisms cannot be maintained in space, and therefore it is
difficult to treat organic chemicals by known biological methods.
In contrast, the method of the present invention can effectively
decompose organic chemicals by very simple steps without using
microorganisms.
[0072] The temperature for treating organic chemicals in the
present invention is not limited, and it may be an ambient
temperature (room temperature).
2. System for Purifying Organic Chemical-Containing Contaminated
Substance
[0073] The present invention also provides a system (apparatus) for
purifying organic chemicals used in the above-mentioned method for
decomposing organic chemicals.
[0074] The system of the present invention comprises a
photoreaction reactor and, if necessary, an insoluble matter
separation/collection apparatus. The photoreaction reactor is
provided with a supply port(s) and an outlet(s), whereby the
contaminated substance containing organic chemicals, Compound (i),
and a transition metal ionic compound are supplied into the
photoreaction reactor through the supply port(s), and they are
exhausted from the outlet(s) after being treated. The supply
port(s) and the outlet(s) may be provided separately or one opening
may serve both functions.
[0075] There is no limitation on the form of the photoreaction
reactor and it may be a bath, tank, etc. It is also possible to use
a tube (pipe) as the photoreaction reactor that can mix a
contaminated substance containing organic chemicals, Compound (i),
a transition metal ionic compound, and water, if necessary, and
flow the mixture from the supply port(s) to the outlet(s). Lakes or
lagoons may also be used.
[0076] The photoreaction reactor is provided with a mixer for
obtaining a mixture of organic chemicals and Compound (i) and a
transition metal ionic compound, and a light irradiator for
irradiating the mixture with light. There is no limitation to the
mixer and a conventionally known mixing means, such as a stirrer,
can be employed. There is no limitation to the light irradiator as
long as it can conduct light irradiation under the conditions as
described above. Examples of usable light irradiators include
fluorescent lights, germicidal lamps, mercury lamps, deuterium
lamps, xenon lamps, halogen lamps, tungsten lamps, LEDs, etc., but
are not limited those. Natural light such as sun light may also be
used as light irradiators. As described above, (ii) a transition
metal ionic compound may be supplied to a photoreaction reactor
together with Compound (i) and an organic chemical-containing
contaminated substance, or supplied to the mixture of Compound (i)
and an organic chemical-containing contaminated substance after
irradiation of light. In the photoreaction reactor, organic
chemicals are detoxified by being irradiated with light, and
insolubilized by the transition metal ionic compound, forming solid
matter.
[0077] The system of the present invention may comprise an
apparatus for separating/collecting insoluble matter, if necessary,
to separate/collect insoluble matter generated in the photoreaction
reactor. The separation/collection apparatus is connected to the
photoreaction reactor in such a manner that the mixture irradiated
with light in the photoreaction reactor is transferred from the
outlet of the photoreaction reactor to the separation/collection
apparatus. Insoluble matter generated in the mixture in the
photoreaction reactor is separated/collected by the
separation/collection apparatus. The thus-obtained processed
substance does not contain organic chemicals and is therefore
purified.
[0078] Examples of usable separation/collection apparatuses include
dust collectors, filtration apparatuses, columns, cyclone
separators, centrifugal separators, etc., but are not limited to
those. The construction of the system of the present invention is
shown in FIG. 1.
EXAMPLES
[0079] The present invention is explained in detail by showing
Examples. However, the present invention is not limited to Examples
below.
Example 1
Decomposition and Separation/Collection of 2,4-Dichlorophenol
[0080] 2,4-dichlorophenol was added to 20 ml of purified water
placed in a 100 ml beaker in such a manner that the concentration
of the 2,4-dichlorophenol became 1 mM. Subsequently, calcium
hydroxide and cobalt chloride were added to the mixture in such a
manner that the concentration of calcium hydroxide became 2 mM and
that of cobalt chloride became 1 mM followed by stirring
sufficiently. A 15 W germicidal lamp (GL-15, product of Matsushita
Electric Industrial Co., Ltd.) was placed 14 cm away from the water
surface of the beaker, and the aqueous solution containing
2,4-dichlorophenol was irradiated with ultraviolet light while
stirring using a stirrer. Samples were collected before and after
irradiation of ultraviolet light. The samples subjected to 60
minutes irradiation became brown suspensions. These suspensions
were subjected to filtration using two types of filter papers No. 2
and No. 5C (product of Advantec), and the optical densities of the
thus-obtained filtrates at 400 nm were measured using an
absorptiometer U-2000 (product of Hitachi). The concentration of
2,4-dichorolophenol in the filtrate was measured by using a
high-performance liquid chromatography (product of Hitachi).
[0081] As a result, 90% or more of 2,4-dichrolophenol was reduced.
As shown in FIG. 2, solid matter (insoluble matter from the
decomposed organic chemicals) were separated/collected on the
filter papers by adding cobalt chloride. Optical densities of the
filtrates were measured, revealing that those filtrates to which
cobalt chloride was not added had an optical density almost the
same as that of the suspension, but that filtrate to which cobalt
chloride (CoCl.sub.2) was added had optical densities about
1/4.sup.th that of the suspension respectively (see FIG. 3). From
the fact that the filter papers No. 2 and No. 5C have particle
holding sizes (minimum particle diameter of the particles retained
by the filter paper and which do not flow into the filtrate) were
about 5 .mu.m and about 1 .mu.m respectively, it became clear that
solid matter larger than 5 .mu.m is formed by adding cobalt
chloride and such solid matter can be removed by filtration.
[0082] Instead of using a filter paper, the brown suspensions could
be passed through a glass column (diameter: 5 cm, length: 10 cm)
filled with 30-50 mesh sea sand (product of Nacalai Tesque, Inc.)
to the height of 5 cm. As a result, solid matter in the suspensions
was completely separated/collected, giving transparent
filtrates.
Example 2
Decomposition of Various Organic Chemicals
[0083] Bisphenol A was added to 50 ml of purified water placed in a
100 ml beaker in such a manner that the concentration of the
bisphenol A became 100 .mu.M. Subsequently, 0.20 g of dolomite was
added to the mixture and stirred. A 15 W germicidal lamp (GL-15,
product of Matsushita Electric Industrial Co., Ltd.) was placed cm
away from the water surface of the beaker, and the resultant
aqueous solution was irradiated with ultraviolet light while
stirring using a stirrer. Samples were collected before and after
irradiation of ultraviolet light.
(a) Measurement of a Decomposition Rate
[0084] The collected samples were subjected to centrifugal
separation (10000 rmp, 5 minutes) to collect the supernatants. To
135 .mu.l of supernatant was added 15 .mu.l of HCl (6 N). The
concentration of bisphenol A was measured using high performance
liquid chromatography (HPLC). The extent of decomposition was
determined from measurement at 280 nm using a reversed phase column
(5C18-AR-II, product of Nacalai Tesque, Inc.) through which
methanol/water=50/50 (v/v) was eluted as the mobile phase at 1
ml/min, and 10 .mu.l of each sample was injected.
(b) Decomposition of Various Organic Chemicals
[0085] In the same manner, the extents of decomposition of
tetrachlorobisphenol A; o-chlorophenol; p-chlorophenol;
2,4-dichlorophenol; p-tert-butylphenol; 2, 4-dichlorophenoxy acetic
acid (2,4-D); carbendazim; 17-.beta.-estradiol; 1-naphthol and
3,5-xylenol were determined (irradiation with UV, dolomite added).
For comparison, the extents of decomposition of the same organic
chemicals were determined without adding dolomite (only irradiation
of ultraviolet light). The extent of decomposition is expressed as
the percentage reduction after 60 minutes of reaction from the
initial concentration of each organic chemical.
[0086] Table 1 shows the results. As shown in Table 1, various
endocrine disruptor compounds were decomposed satisfactory.
Furthermore, from the fact that decomposition of 2,4-dichlorophenol
and tetrachlorobisphenol A both having a plurality of chlorine
substituents were also accelerated, it can be concluded that
decomposition of various other photodegradable chlorinated
compounds with a plurality of chlorine substituents, such as
dioxins and PCBs, can also be accelerated.
TABLE-US-00001 TABLE 1 Initital concentration 60 minutes of
decomposition Organic Chemicals (.mu.M) UV + Dolomite UV only
Bisphenol A 100 70 0 Tetrachrolobisphenol A 50 100 31
o-Chlorophenol 100 100 28 p-Chlorophenol 100 100 52
2,4-Dichlorophenol 100 100 0 p-tert-Butylphenol 100 94 18 2,4-D 100
13 6 Carbendazim 40 88 8 17-.beta.-Estradiol 10 100 0 1-Naphthol
100 94 32 3,5-Xylenol 100 51 7
Example 3
Decomposition Using Various Compound (i)
[0087] To 50 ml of pure water placed in a 100 ml beaker was added
bisphenol A (BPA) to a concentration of 100 .mu.M. Subsequently, 44
mg of calcium oxide, 58 mg of calcium hydroxide, 25 mg of magnesium
oxide, 36 mg of magnesium hydroxide, 52 mg of magnesium carbonate
or 63 mg of sodium hydroxide was added to a beaker. A 15 W
germicidal lamp (GL-15, product of Matsushita Electric Industrial
Co., Ltd.) was placed 12 cm away from the water surface of the
beaker, and the resultant aqueous solution was irradiated with
ultraviolet light while stirring using a stirrer. Samples were
collected every 20 minutes.
[0088] As a result, as shown in FIG. 4, it became clear that
bisphenol A can be decomposed by using alkali metal compounds
and/or alkaline-earth metal compounds.
Example 4
Decomposition and Separation/Collection Using Various Compound
(i)
[0089] Cobalt chloride was added to 20 ml of 1 mM
2,4-dichlorophenol in the same manner as in Example 1 in such a
manner that the concentration of the cobalt chloride became 1 mM.
Instead of calcium hydroxide, one member selected from calcium
oxide, calcium carbonate, magnesium hydroxide, magnesium oxide,
magnesium carbonate, potassium hydroxide, and sodium hydroxide was
added to the resultant mixture in such a manner that its
concentration became 2 mM. Alternatively, 4 mg of dolomite may be
added to the mixture. The mixtures were irradiated with ultraviolet
light for 60 minutes, and then subjected to filtration using two
types of filter papers No. 2 and No. 5C. Optical densities of the
thus-obtained filtrates at 400 nm were measured.
[0090] As a result, all samples to which a metallic compound of
calcium, magnesium, potassium or sodium, or dolomite was added
became brown suspensions. Optical densities of the filtrates
obtained by subjecting the resultant suspensions to filtration were
measured, revealing that, as shown in FIG. 5, formation of solid
matter was also facilitated when one of these metallic compounds or
dolomite was added as when a calcium hydroxide (Ca(OH)2) was added.
Therefore, it is believed that metallic compounds of calcium,
magnesium, potassium, and sodium, and various minerals containing
such metallic compound(s) can achieve such effects.
Example 5
Decomposition and Separation/Collection Using Various Transition
Metals
[0091] Calcium hydroxide was added to 1 mM 2,4-dichlorophenol in
the same manner as in Example 1 in such a manner that the
concentration of the calcium hydroxide became 2 mM. Instead of
cobalt chloride, one member selected from cobalt nitrate, manganese
chloride, manganese nitrate, ferric chloride, iron ferric nitrate,
nickel chloride, nickel nitrate, copper chloride, copper nitrate,
zinc chloride, zinc nitrate, titanium oxide, and ferric oxide was
added to the resultant mixture so that its concentration became 1
mM. The resultant mixtures were subjected to 60 minutes irradiation
and the resultant suspensions were then filtered using two types of
filter papers No. 2 and No. 5C. The optical densities of the
thus-obtained filtrates at 400 nm were measured using.
[0092] As a result, all samples to which a chloride salt or a
nitrate salt of transition metal was added became brown
suspensions. Optical densities of the filtrates obtained by
subjecting the resultant suspensions to filtration were measured.
As shown in FIG. 6, in all samples to which a chloride salt or a
nitrate salt of transition metal was added, the optical densities
of the filtrates obtained by using filter papers No. 2 and No. 5C
were significantly reduced compared to that of the suspension.
However, when the same experiments were conducted using a titanium
oxide and an ferric oxide, which are often used as photocatalysts
and/or oxidation catalysts, any facilitatory effects for forming
solid matter were not observed. Titanium oxides and ferric oxides
do not achieve such effect presumably because they axe insoluble in
water. The effects of addition of a chloride salt or a nitrate salt
are described in this example; however, it can be easily concluded
that formation of solid matter can be facilitated by adding any
transition metal compounds that form ions when dissolved in
water.
Example 6
Decomposition and Separation/Collection of Various Organic
Chemicals
[0093] In the same manner as in Example 1, bisphenol A instead of
2,4-dichlorophenol was added so as to have a concentration of 0.5
mM. Subsequently, calcium hydroxide and cobalt chloride were added
to have a concentration of 2 mm and 1 mM respectively. After
conducting 60 minutes ultraviolet light irradiation, the resultant
suspensions were subjected to filtration using two types of filter
papers No. 2 and No. 5C, and the optical densities of the thus
obtained filtrates at 400 nm were measured.
[0094] In the same manner, each of o-chlorophenol; p-chlorophenol;
p-tert-butyl phenol; 1-naphthol; 3,5-xylenol; and 2,
4-dichlorophenoxy acetic acid (2,4-D) were added so as to have a
concentration of 1 mM. After irradiation of ultraviolet light, the
optical densities of the resultant suspensions were measured.
[0095] FIG. 7 shows the results. These organic chemicals were
satisfactory decomposed and solid matter was formed. Therefore, it
became clear that this method is applicable to decompose organic
chemicals. Furthermore, because all these organic chemicals are
endocrine disruptors, it can be concluded that this method is also
effective for decomposing aromatic compounds comprising other
endocrine disruptors having a similar construction. Furthermore,
considering the fact that decomposition of chlorophenols having at
least one chloro-substituent, decomposition of 2,4-D, and formation
of solid matter can be facilitated, this method is also applicable
to treat various photodegradable organic chemicals having
chloro-substituent.
Example 7
Treatment of Solid Contaminated-Substance Containing Organic
Chemicals
[0096] An example of evaluation of treatment of solid
contaminated-substance containing organic chemicals, such as
contaminated soil, sludge, and incinerated ash, was explained
below. To 20 g of sea sand (30-50 mesh, product of Nacalai Tesque,
Inc.) was added 10 ml of 1 mM 2,4-dichlorophenol solution, followed
by sufficient stirring. Water (10 ml) containing 4 mM calcium
hydroxide and 2 mM cobalt chloride was added to the resultant
mixture to give slurry, and the obtained slurry was placed in a
cylindrical quartz tube. The slurry was irradiated with ultraviolet
light for 60 minutes using a germicidal lamp placed 10 cm away
therefrom while agitating by rotation. After the reaction, the
slurry was subjected to 2,4-dichlorophenol extraction using
methanol, and the 2,4-dichlorophenol concentration was then
measured using a high-performance liquid chromatography.
[0097] After 60 minutes irradiation of ultraviolet light, the
concentration of 2,4-dichlorophenol was reduced to 1/10.sup.th.
Photographs before and after irradiation of ultraviolet light are
shown in FIG. 8. The sea sand was white before ultraviolet light
irradiation but it became brown after the irradiation. This
indicates that insoluble solid matter was formed from
2,4-dichlorophenol. This result made it clear that solid
contaminated-substance containing organic chemicals can be purified
by irradiating it with ultraviolet light after forming it into
slurry.
Example 8
Verification of Polymerization
[0098] In order to verify the occurrence of polymerization, a
solution irradiated with ultraviolet light after adding calcium
hydroxide and cobalt chloride to bisphenol A was inspected using a
high-performance liquid chromatograph mass spectrometer
(NanoFrontier LD, product of Hitachi).
[0099] FIG. 9 shows the results. Peaks at mass numbers of 453 and
679, which are presumably attributable to a dimer and a trimer of
bisphenol A, are observed. This confirms the occurrence of
polymerization of bisphenol A. The structural formulae shown at the
right of the figure are examples of the expected dimer and trimer.
Peaks attributable to higher than tetramer were not observed.
Presumably, this is because such substances have high molecular
weights and are insoluble in solvent. From these results, it can be
concluded that insoluble matter is formed in this reaction due to
polymerization of organic chemicals.
Example 9
Timing for Adding Transition Metal Compound
[0100] Calcium hydroxide was added to 20 ml of 1 mM
2,4-dichlorophenol in the same manner as in Example 1 to have a
concentration of 2 mM. Cobalt chloride was added to the resultant
mixture to have a concentration of 1 mM, and then the solution was
irradiated with ultraviolet light while stirring for 60 minutes.
After irradiation of ultraviolet light, the solution was stirred
for 60 minutes (this sample is referred to as Before UV).
Alternatively, the mixture of calcium hydroxide and
2,4-dichlorophenol was irradiated with ultraviolet light for 60
minutes and cobalt chloride was then added thereto so that the
concentration thereof became 1 mM, and then was stirred for 60
minutes (this sample is referred to as After UV). Another sample
was obtained by irradiating ultraviolet light for 60 minutes
without adding cobalt chloride, and then the resultant suspension
was stirred for 60 minutes (this sample is referred to as Nothing).
These samples were subjected to filtration using two types of
filter papers No. 2 and No. 5C, and the optical densities of the
thus obtained filtrates at 400 nm were measured.
[0101] The result reveals that even a case when cobalt chloride was
added after irradiation of ultraviolet light (After UV), formation
of insoluble matter was also facilitated (FIG. 10). Therefore, it
can be concluded that the preferable timing for adding a transition
metal compound is before irradiation of ultraviolet light but it is
still effective even after irradiation of ultraviolet light.
Example 10
Treatment of Dioxin and PCB
[0102] In the same manner as in Example 1, to 50 ml of purified
water placed in a 100 ml beaker, a PCB mixture (KC-400, product of
Kaneka Corporation) was added so as to have a concentration of 0.02
mg/L, or 2,3-dichlorodibenzo-p-dioxin (product of Supelco, Inc.)
was added so as to have a concentration of 0.01 mg/L instead of
2,4-dichlorophenol. Subsequently, calcium hydroxide and cobalt
chloride were added to have a concentration of 2 mM and 1 mM
respectively. A 15 W germicidal lamp was placed 12 cm away from the
water surface of the glass beaker, and the resultant aqueous
solution was irradiated with ultraviolet light while stirring using
a stirrer for 20 minutes. After ultraviolet light irradiation,
samples were collected and concentrated by solid phase extraction.
Concentrations of dioxin and PCB were measured with a gas
chromatograph mass spectrometer (GC-MS).
[0103] With regard to the samples subjected to only ultraviolet
light irradiation, the extent of removal of PCBs having 1 to 5
chlorines was 34-64%, and that of 2,3-dichlorodibenzo-p-dioxin was
about 87%. In contrast, by irradiating the samples with ultraviolet
light after adding calcium hydroxide and cobalt chloride, the
extents of removal of the PCBs and dioxin were increased to
98-100%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0104] FIG. 1 is a diagram showing a treatment system of the
present invention.
[0105] FIG. 2 is a photograph of filtered insoluble matter
generated by decomposition of 2,4-dichlorophenol.
[0106] FIG. 3 is a graph showing that insolubilization of
decomposed organic chemical is accelerated by addition of cobalt
chloride.
[0107] FIG. 4 is a graph showing that bisphenol A can be decomposed
by addition of various metal compounds (i).
[0108] FIG. 5 is a graph showing that insolubilization of
2,4-dichlorophenol is accelerated by addition of various metal
compounds (1).
[0109] FIG. 6 is a graph showing that insolubilization of
2,4-dichlorophenol is accelerated by addition of various transition
metal salts.
[0110] FIG. 7 is a graph showing that insolubilization of various
organic chemicals can be accelerated.
[0111] FIG. 8 is a picture showing that a solid contaminated
substance containing organic chemicals can be treated.
[0112] FIG. 9 shows formation of polymerization products of
bisphenol A.
[0113] FIG. 10 is a graph showing formation of insoluble matter
when a cobalt salt is added after irradiation of ultraviolet light
(After UV).
* * * * *