U.S. patent application number 10/239171 was filed with the patent office on 2003-09-11 for method and apparatus for generating ozone by electrolysis.
Invention is credited to Hiro, Naoki, Ikegami, Kazuo, Iseki, Masahiro, Kondo, Yasuhito, Shimizu, Yasuhiko.
Application Number | 20030168348 10/239171 |
Document ID | / |
Family ID | 18929560 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030168348 |
Kind Code |
A1 |
Kondo, Yasuhito ; et
al. |
September 11, 2003 |
Method and apparatus for generating ozone by electrolysis
Abstract
There are provided an ozone producing method and apparatus
capable of significantly increasing an amount of ozone produced in
for-treatment water. In the ozone producing method of the present
invention, a noble metal is used as a material constituting the
anode, and the for-treatment water contains halogen ions or a
compound containing halogen ions.
Inventors: |
Kondo, Yasuhito; (Gunma,
JP) ; Hiro, Naoki; (Osaka-shi, JP) ; Ikegami,
Kazuo; (Takatsuki-shi, JP) ; Shimizu, Yasuhiko;
(Gunma, JP) ; Iseki, Masahiro; (Gunma,
JP) |
Correspondence
Address: |
ARMSTRONG,WESTERMAN & HATTORI, LLP
1725 K STREET, NW
SUITE 1000
WASHINGTON
DC
20006
US
|
Family ID: |
18929560 |
Appl. No.: |
10/239171 |
Filed: |
March 4, 2003 |
PCT Filed: |
March 6, 2002 |
PCT NO: |
PCT/JP02/02094 |
Current U.S.
Class: |
205/626 |
Current CPC
Class: |
C02F 2201/46115
20130101; C02F 2201/46155 20130101; C02F 2001/46133 20130101; C02F
1/4672 20130101; C02F 2303/04 20130101; C02F 1/78 20130101; C02F
2101/305 20130101; C02F 2001/46138 20130101 |
Class at
Publication: |
205/626 |
International
Class: |
C25B 001/13 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2001 |
JP |
2001-71895 |
Claims
What is claimed is:
1. A method for producing ozone in for-treatment water through
electrolysis by passing current between an anode and a cathode,
wherein a noble metal is used as a material constituting the anode,
and the for-treatment water contains halogen ions or a compound
containing halogen ions.
2. The method of claim 1, wherein the halogen ions are chloride
ions.
3. The method of claim 1 or 2, wherein the anode is made of
platinum, platinum-coated titanium, a platinum-coated titanium
alloy, titanium coated with a platinum-iridium alloy, a titanium
alloy coated with a platinum-iridium alloy, titanium coated with a
platinum-iridium-tantalum alloy, or a titanium alloy coated with a
platinum-iridium-tantalum alloy.
4. The method of claim 1, 2 or 3, wherein a cation exchange film is
disposed between the anode and the cathode.
5. The method of claim 1, 2, 3 or 4, wherein the for-treatment
water is cooled.
6. The method of claim 1, 2, 3, 4 or 5, wherein a value of the
current passed between the anode and the cathode is controlled.
7. An ozone producing apparatus having an anode and a cathode which
are immersed in for-treatment water in an electrolysis vessel,
wherein the anode is made of a noble metal, and current is passed
between the anode and the cathode so as to electrolyze the
for-treatment water containing halogen ions or a compound
containing halogen ions, thereby producing ozone in the
for-treatment water.
8. The apparatus of claim 7, wherein the halogen ions are chloride
ions.
9. The apparatus of claim 7 or 8, wherein the anode is made of
platinum, platinum-coated titanium, a platinum-coated titanium
alloy, titanium coated with a platinum-iridium alloy, a titanium
alloy coated with a platinum-iridium alloy, titanium coated with a
platinum-iridium-tantalum alloy, or a titanium alloy coated with a
platinum-iridium-tantalum alloy.
10. The apparatus of claim 7, 8 or 9, wherein a cation exchange
film is disposed between the anode and the cathode.
11. The apparatus of claim 7, 8, 9 or 10, which has cooling means
for cooling the for-treatment water.
12. The apparatus of claim 7, 8, 9, 10 or 11, which has a
controller for controlling a value of the current passed between
the anode and the cathode.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method and apparatus for
producing ozone in water to be treated (hereinafter, "water to be
treated" will be referred to as "for-treatment water") through
electrolysis by passing current between an anode and a cathode.
[0003] 2. Description of the Related Art
[0004] Heretofore, as a method of removing bacteria, fungi and
microorganisms such as a protozoan in for-treatment water to be
used as drinking water for domestic use or in a kitchen, a method
comprising carrying out sterilization and purification by use of a
chlorine-containing agent such as sodium hypochlorite has been
used. However, chlorine-resistant bacteria, spores and protozoans
contained in the above for-treatment water are difficult to remove
by use of only hypochlorous acid. Hence, a method comprising
carrying out sterilization and purification by use of ozone is
used.
[0005] As a method of producing ozone in this case, it has been
commonly practiced to produce ozone by use of electrodes made of
lead dioxide.
[0006] However, in view of a detrimental effect of lead on a
person's health, a method as described above which uses lead
dioxide in electrodes cannot be used when the for-treatment water
directly influences a human body, i.e., when it is used for cooking
or washing vegetables or cooking utensils, and ozone-containing
for-treatment water purified by the above method has been used only
for applications in which the for-treatment water does not directly
influence a human body, e.g., for cleaning a floor in a
kitchen.
[0007] For this reason, to sterilize and purify drinking water
(for-treatment water) such as tap water in such a case as described
above where the water is used for cooking or washing cooking
utensils, sterilization and purification of the water are performed
by, for example, applying a high voltage between electrodes in an
atmosphere by means of a separate device so as to cause surface
creepage on surfaces of the electrodes, producing ozone from oxygen
by the creepage, and dissolving the produced ozone in the
for-treatment water reserved in a treatment tank or the like.
[0008] However, in the case of the foregoing method of sterilizing
and purifying for-treatment water, since an amount of ozone
dissolved in the for-treatment water is small, a sterilizing effect
of the ozone is not at a satisfactory level. Further, the method
also has a problem that since the amount of the ozone dissolved in
the for-treatment water decreases with the passage of time, the
amount of the ozone becomes already very small when the
for-treatment water is carried by means of a pipe or the like to
where the water is to be used after dissolution of the ozone, so
that the amount of the ozone remaining in the for-treatment water
is short of an amount required for sterilization.
[0009] Further, the ozone producing method in the foregoing method
has a problem that it is not suitable for practical use since its
energy consumption is significant.
[0010] Under the circumstances, the present invention has been
invented to solve the conventional technical problems. An object of
the present invention is to provide an ozone producing method and
apparatus which are capable of significantly increasing an amount
of ozone produced in for-treatment water.
SUMMARY OF THE INVENTION
[0011] A method for producing ozone by electrolysis according to
the present invention is a method for producing ozone in
for-treatment water through electrolysis by passing current between
an anode and a cathode, wherein a noble metal is used as a material
constituting the anode, and the for-treatment water contains
halogen ions or a compound containing halogen ions.
[0012] Further, in the method for producing ozone by electrolysis
according to the present invention, in addition to the above
invention, the halogen ions are chloride ions.
[0013] Further, in the method for producing ozone by electrolysis
according to the present invention, in addition to the above
inventions, the anode is made of platinum, platinum-coated
titanium, a platinum-coated titanium alloy, titanium coated with a
platinum-iridium alloy, a titanium alloy coated with a
platinum-iridium alloy, titanium coated with a
platinum-iridium-tantalum alloy, or a titanium alloy coated with a
platinum-iridium-tantalum alloy.
[0014] Further, in the method for producing ozone by electrolysis
according to the present invention, in addition to the above
inventions, a cation exchange film is disposed between the anode
and the cathode.
[0015] Further, in the method for producing ozone by electrolysis
according to the present invention, in addition to the above
inventions, the for-treatment water is cooled.
[0016] Further, in the method for producing ozone by electrolysis
according to the present invention, in addition to the above
inventions, a value of the current passed between the anode and the
cathode is controlled.
[0017] An apparatus for producing ozone according to the present
invention is an ozone producing apparatus having an anode and a
cathode which are immersed in for-treatment water in an
electrolysis vessel, wherein the anode is made of a noble metal,
and current is passed between the anode and the cathode so as to
electrolyze the for-treatment water containing halogen ions or a
compound containing halogen ions, thereby producing ozone in the
for-treatment water.
[0018] Further, in the ozone producing apparatus according to the
present invention, in addition to the above invention, the halogen
ions are chloride ions.
[0019] Further, in the ozone producing apparatus according to the
present invention, in addition to the ozone producing apparatuses
of above inventions, the anode is made of platinum, platinum-coated
titanium, a platinum-coated titanium alloy, titanium coated with a
platinum-iridium alloy, a titanium alloy coated with a
platinum-iridium alloy, titanium coated with a
platinum-iridium-tantalum alloy, or a titanium alloy coated with a
platinum-iridium-tantalum alloy.
[0020] Further, in the ozone producing apparatus according to the
present invention, in addition to the ozone producing apparatuses
of above inventions, a cation exchange film is disposed between the
anode and the cathode.
[0021] Further, the ozone producing apparatus according to the
present invention, in addition to the ozone producing apparatuses
of above inventions, has cooling means for cooling the
for-treatment water.
[0022] Further, the ozone producing apparatus according to the
present invention, in addition to the ozone producing apparatuses
of above inventions, has a controller for controlling a value of
the current passed between the anode and the cathode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a schematic explanatory diagram of an ozone
producing apparatus of the present invention.
[0024] FIG. 2 is a diagram showing potentials with respect to
currents when a platinum-coated titanium electrode is used.
[0025] FIG. 3 is a diagram showing potentials with respect to
currents when an electrode made of titanium coated with platinum
and iridium is used.
[0026] FIG. 4 is a diagram showing potentials with respect to
currents when an electrode made of titanium coated with platinum,
iridium and tantalum is used.
[0027] FIG. 5 is a diagram showing amounts of contained ozone with
respect to for-treatment water temperatures.
[0028] FIG. 6 is a diagram showing effective chlorine
concentrations on the above electrodes with respect to
for-treatment water temperatures.
[0029] FIG. 7 is a diagram showing a decrease in concentration of
an endocrine disruptor by electrolysis.
BEST MODE FOR CARRYING OUT THE INVENTION
[0030] Hereinafter, an embodiment of the present invention will be
described in detail with reference to the drawings. FIG. 1 is an
explanatory diagram showing an outline of an ozone producing
apparatus 1 for implementing an ozone producing method of the
present invention. The ozone producing apparatus 1 in the present
embodiment comprises an electrolysis vessel 2 which constitutes a
treating chamber 4 having an inlet and an outlet for for-treatment
water therein, the inlet and the outlet being not shown, a pair of
electrodes, i.e., an anode 5 and a cathode 6, which are opposed to
each other such that at least portions thereof are immersed in
for-treatment water in the treating chamber 4, a power supply 7 for
energizing the electrodes 5 and 6, and a controller 8 for
controlling the electrodes 5 and 6 and an electric current value.
In FIG. 1, reference numeral 9 denotes a cation exchange film
disposed between the anode 5 and the cathode 6 in the electrolysis
vessel 2, and reference numerals 10 denote cooling devices for
cooling the for-treatment water in the electrolysis vessel 2 which
are disposed, for example, at the bottom of the electrolysis vessel
2.
[0031] The anode 5 is made of a noble metal such as platinum,
platinum-coated titanium, a platinum-coated titanium alloy,
titanium coated with a platinum-iridium alloy, a titanium alloy
coated with a platinum-iridium alloy, titanium coated with a
platinum-iridium-tantalum alloy, or a titanium alloy coated with a
platinum-iridium-tantalum alloy. Meanwhile, the cathode 6 is made
of the same noble metals as can be used in the anode 5 or an
insoluble material or carbon.
[0032] Further, as the for-treatment water in the present
embodiment, tap water containing chloride ions is used, for
example.
[0033] With the arrangement described above, for-treatment water is
reserved in the treating chamber 4 in the electrolysis vessel 2,
and the controller 8 turns on the power supply 7 so as to energize
the anode 5 and the cathode 6. Thereby, microorganisms contained in
the for-treatment water are attracted to the anode 5 which is
positively charged since the microorganisms are generally
negatively charged. Further, at the anode 5, chloride ions
contained in the for-treatment water produce chlorine by
discharging electrons. Thereafter, the chlorine dissolves in the
water so as to produce hypochlorous acid. Thus, microorganisms in
the for-treatment water which are present in the vicinity of the
anode 5 are sterilized by the chlorine or hypochlorous acid.
[0034] Further, since the anode 5 is made of platinum,
platinum-coated titanium, a platinum-coated titanium alloy,
titanium coated with a platinum-iridium alloy, a titanium alloy
coated with a platinum-iridium alloy, titanium coated with a
platinum-iridium-tantalum alloy, or a titanium alloy coated with a
platinum-iridium-tantalum alloy as described above and the
for-treatment water contains the chloride ions, the potential
increases and ozone is produced.
[0035] Next, an increase in the potential with or without the above
chloride ions will be described with reference to FIG. 2. FIG. 2
shows potentials with respect to currents when the chloride ions
are contained and not contained, with a platinum-coated titanium
electrode being used as the electrode. As the for-treatment water,
1M sulfuric acid containing 10% of potassium chloride is used when
the chloride ions are contained, and 1M sulfuric acid is used when
the chloride ions are not contained.
[0036] Referring to FIG. 2, in the case of for-treatment water
containing the chloride ions, the potential sharply increases from
1.2 V to 1.5 V when a current of 6 to 8 mA is passed, and the
potential increases to 2.1 V with a current of 60 mA. Meanwhile, in
the case of for-treatment water containing no chloride ions, the
potential is gently increased from 0.8 V to 1.8 V as current is
gradually increased from 0.1 mA to 60 mA. Thereby, it is understood
that when the chloride ions are contained in the for-treatment
water, the potential is significantly increased, as compared with
when the chloride ions are not contained in the for-treatment
water.
[0037] FIG. 3 is a diagram for illustrating an increase in
potential with or without the chloride ions when a titanium
electrode coated with platinum and iridium is used. FIG. 3 shows
potentials with respect to currents when the chloride ions are
contained and not contained, with titanium coated with platinum and
iridium being used as the electrode. As the for-treatment water, 1M
sulfuric acid containing 10% of potassium chloride is used when the
chloride ions are contained, and 1M sulfuric acid is used when the
chloride ions are not contained.
[0038] Referring to FIG. 3, in the case of for-treatment water
containing the chloride ions, the potential increases to about 1.48
V when a current of 60 mA is passed, while in the case of
for-treatment water containing no chloride ions, the potential is
increased to about 1.4 V when a current of 60 mA is passed. In this
case as well, it is understood that when the chloride ions are
contained in the for-treatment water, the potential is increased,
as compared with when the chloride ions are not contained in the
for-treatment water.
[0039] FIG. 4 is a diagram for illustrating an increase in
potential with or without the chloride ions when a titanium
electrode coated with platinum, iridium and tantalum is used. FIG.
4 shows potentials with respect to currents when the chloride ions
are contained and not contained, with titanium coated with
platinum, iridium and tantalum being used as the electrode. As the
for-treatment water, 1M sulfuric acid containing 10% of potassium
chloride is used when the chloride ions are contained, and 1M
sulfuric acid is used when the chloride ions are not contained.
[0040] Referring to FIG. 4, in the case of for-treatment water
containing the chloride ions, the potential increases to about 1.7
V when a current of 60 mA is passed, while in the case of
for-treatment water containing no chloride ions, the potential is
increased to about 1.6 V when a current of 60 mA is passed. In this
case, a difference in potential between when the chloride ions are
contained and when the chloride ions are not contained is not so
significant. In this case as well, it is understood that when the
chloride ions are contained in the for-treatment water, the
potential is increased, as compared with when the chloride ions are
not contained in the for-treatment water.
[0041] Although the present embodiment has been described by using
the chloride ions contained in tap water in particular as an
example, other halogen ions may be taken as examples, in addition
to the chloride ions.
[0042] As is understood from the above description, when
for-treatment water containing the chloride ions is electrolyzed by
means of a titanium electrode coated with platinum, a titanium
electrode coated with platinum and iridium or a titanium electrode
coated with platinum, iridium and tantalum, ozone can be produced
with ease by an increase in potential. Thereby, since ozone can be
produced with a relatively small current, microorganisms,
chlorine-resistant bacteria, spores and protozoans contained in
for-treatment water can be eliminated by ozone which exhibits a
very powerful sterilizing effect.
[0043] Further, since the electrode used in the present invention
is a platinum-coated titanium electrode, chlorine or hypochlorous
acid and ozone which exhibit an excellent sterilizing effect can be
produced in the same electrolysis vessel 2, thereby making it
possible to sterilize and purify for-treatment water
efficiently.
[0044] Further, in the same electrolysis vessel 2, for-treatment
water can be sterilized and purified while ozone is produced.
Therefore, there is no longer need to carry out the step of
dissolving ozone produced in a separate device into for-treatment
water, and ozone can be contained in the for-treatment water in a
significantly larger amount than a conventional amount of dissolved
ozone. Thereby, sterilization and purification of for-treatment
water can be carried out more securely and more efficiently.
[0045] Further, in the present invention, ozone is produced without
use of lead dioxide. Therefore, sterilized and purified
for-treatment water can be directly used for drinking or
sterilization of cooking utensils without affecting human
bodies.
[0046] In addition, in the present embodiment, since the cation
exchange film 9 is disposed between the anode 5 and the cathode 6
in the electrolysis vessel 2. Thus, hydrogen ions produced by
electrolysis are transferred from the anode 5 side to the cathode 6
side so as to promote production of hydrogen at the cathode 6.
Thereby, the potential can be increased, and the amount of ozone
produced can also be increased along with an increase in the
potential.
[0047] Meanwhile, in the present embodiment, the electrolysis
vessel 2 electrolyzes for-treatment water while cooling the
for-treatment water by means of the conventional cooling devices
10. The results of experiments showing an effect resulting from
carrying out electrolysis while for-treatment water is being
cooled.
[0048] FIG. 5 is a diagram showing amounts of contained ozone with
respect to a for-treatment water temperature, and electrolysis was
carried out with a current of 400 mA by use of a platinum-coated
titanium electrode, a titanium electrode coated with platinum and
iridium, or a titanium electrode coated with platinum, iridium and
tantalum.
[0049] According to FIG. 5, when the for-treatment water
temperature is +3.degree. C., the concentration of ozone is about
0.48 mg/dm.sup.3 for the platinum-coated titanium electrode, about
0.10 mg/dm.sup.3 for the titanium electrode coated with platinum
and iridium, and about 0.18 mg/dm.sup.3 for the titanium electrode
coated with platinum, iridium and tantalum. Then, as the
for-treatment water temperature is increased for each of the
electrodes, the concentration of ozone is about 0.12 mg/dm.sup.3
for the platinum-coated titanium electrode, about 0.01 mg/dm.sup.3
for the titanium electrode coated with platinum and iridium, and
about 0.05 mg/dm.sup.3 for the titanium electrode coated with
platinum, iridium and tantalum, at the for-treatment temperature of
+22.degree. C. Further, it is observed that as the for-treatment
water temperature is further increased for each of the electrodes,
ozone hardly exists for any of the electrodes at the for-treatment
water temperature of +60.degree. C.
[0050] Thus, when electrolysis is carried out while the
electrolysis vessel 2 is cooled at, for example, +3.degree. C., the
concentration of ozone in for-treatment water is significantly
increased, thereby making it possible to further improve the
sterilizing/purifying effect.
[0051] FIG. 6 is a diagram showing effective chlorine
concentrations on the above electrodes with respect to
for-treatment water temperatures and shows the results of
experiments conducted under the same conditions as those for the
experiments whose results are shown in FIG. 5. Referring to FIG. 6,
with respect to for-treatment water temperatures, effective
chlorine concentration for the platinum-coated titanium electrode
is significantly lower than effective chlorine concentrations for
other electrodes. This is assumed to be because a reaction of
producing ozone occurs preferentially.
[0052] FIG. 7 is a diagram showing a decrease in concentration of
an endocrine disrupter by electrolysis, which is currently
considered as a problem. It is seen that when an endocrine
disruptor such as di-2-ethylhexyl phthalate is contained in the
foregoing for-treatment water, di-2-ethylhexyl phthalate is
decreased with the passage of electrolysis time by ozone produced
as described above. Thus, even if an endocrine disruptor such as
di-2-ethylhexyl phthalate is contained in for-treatment water, the
endocrine disrupter can be decomposed efficiently by ozone, thereby
improving efficiency of purification of the for-treatment
water.
[0053] Further, in the present embodiment, an electric current
value can be controlled by the controller 8. Accordingly, an
electric current value is controlled according to quality of
for-treatment water, thereby making it possible to produce required
ozone.
[0054] Thus, in the ozone producing method and apparatus 1 of the
present invention, purification of for-treatment water by ozone can
be carried out efficiently while power consumption is kept low.
[0055] According to the method of the present invention for
producing ozone by means of electrolysis, it is a method for
producing ozone in for-treatment water through electrolysis by
passing current between an anode and a cathode, wherein a noble
metal is used as a material constituting the anode, and the
for-treatment water contains halogen ions or a compound containing
halogen ions. Thereby, ozone can be produced efficiently. As for
for-treatment water, even one containing chlorine-resistant
bacteria which have heretofore been difficult to be sterilized can
be sterilized efficiently by ozone, and in particular, the
resulting sterilized water can be used as drinking water.
[0056] Further, according to the present invention, the above
halogen ions are chloride ions. Thus, hypochlorous acid can be
produced along with production of ozone, and the for-treatment
water can be sterilized effectively by ozone and hypochlorous
acid.
[0057] Further, the above anode is made of platinum,
platinum-coated titanium, a platinum-coated titanium alloy,
titanium coated with a platinum-iridium alloy, a titanium alloy
coated with a platinum-iridium alloy, titanium coated with a
platinum-iridium-tantalum alloy, or a titanium alloy coated with a
platinum-iridium-tantalum alloy. Thereby, ozone can be produced
more efficiently. In addition, unlike the prior art, lead dioxide
is not used in the anode. Therefore, the treated water can be used
for drinking or sterilizing cooking utensils or the like.
[0058] Further, since a cation exchange film is disposed between
the above anode and cathode, hydrogen ions present on the anode
side can be transferred to the cathode side efficiently so as to
facilitate flow of current. Thereby, an increased amount of ozone
can be produced.
[0059] Further, since the above for-treatment water is cooled,
ozone produced as described above can be present in the
for-treatment water over a relatively longer time period, so that
more ozone can be present in the for-treatment water.
[0060] Further, a value of the current passed between the above
anode and cathode is controlled. Thereby, the amount of ozone
contained in the for-treatment water can be controlled.
[0061] According to the apparatus of the present invention for
producing ozone by electrolysis, it is an ozone producing apparatus
having an anode and a cathode which are immersed in for-treatment
water in an electrolysis vessel, wherein the anode is made of a
noble metal, and current is passed between the anode and the
cathode so as to electrolyze the for-treatment water containing
halogen ions or a compound containing halogen ions, thereby
producing ozone in the for-treatment water. Thereby, ozone can be
produced in an electrolysis vessel efficiently so as to sterilize
the for-treatment water efficiently. Further, chlorine-resistant
bacteria and the like which are conventionally contained in the
for-treatment water can be eliminated efficiently, and the
resulting treated water can be used also as drinking water or the
like.
[0062] Further, in the above ozone producing apparatus, the halogen
ions are chloride ions. Therefore, hypochlorous acid can be
produced along with production of ozone, and the for-treatment
water can be sterilized effectively by ozone and hypochlorous acid
contained in the for-treatment water.
[0063] Further, in the above ozone producing apparatus, the above
anode is made of platinum, platinum-coated titanium, a
platinum-coated titanium alloy, titanium coated with a
platinum-iridium alloy, a titanium alloy coated with a
platinum-iridium alloy, titanium coated with a
platinum-iridium-tantalum alloy, or a titanium alloy coated with a
platinum-iridium-tantalum alloy. Thereby, ozone can be produced
more efficiently. In addition, unlike the prior art, lead dioxide
is not used in the anode. Therefore, the treated water can be used
for drinking or sterilizing cooking utensils or the like.
[0064] Further, in the above ozone producing apparatus, since a
cation exchange film is disposed between the anode and the cathode,
hydrogen ions present on the anode side can be transferred to the
cathode side efficiently so as to facilitate flow of current.
Thereby, an increased amount of ozone can be produced.
[0065] Further, in the above ozone producing apparatus, since
cooling means for cooling the for-treatment water are provided,
ozone produced as described above can be present in the
for-treatment water over a relatively longer time period, so that
more ozone can be present in the for-treatment water.
[0066] Further, in the above ozone producing apparatus, since a
controller for controlling a value of the current passed between
the anode and the cathode is provided, the amount of ozone
contained in the for-treatment water can be controlled with
ease.
* * * * *