U.S. patent application number 15/065332 was filed with the patent office on 2016-06-30 for electrode unit, electrolytic cell comprising electrode unit and electrolytic device.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA. Invention is credited to Wu MEI, Katsuyuki NAITO, Hideo OOTA, Norihiro TOMIMATSU, Ryosuke YAGI, Masahiro YOKOTA, Norihiro YOSHINAGA.
Application Number | 20160186336 15/065332 |
Document ID | / |
Family ID | 55532851 |
Filed Date | 2016-06-30 |
United States Patent
Application |
20160186336 |
Kind Code |
A1 |
NAITO; Katsuyuki ; et
al. |
June 30, 2016 |
ELECTRODE UNIT, ELECTROLYTIC CELL COMPRISING ELECTRODE UNIT AND
ELECTROLYTIC DEVICE
Abstract
According to one embodiment, an electrode unit of an
electrolytic device includes a first electrode including a first
surface, a second surface located on an opposite side to the first
surface, a plurality of first pores opened in the first surface, a
plurality of second pores opened in the second surface and having
an opening area greater than that of the first pores, and a
plurality of the first pores communicating with a respective one of
the second pores, a second electrode opposing the first surface of
the first electrode, and a continuous porous membrane arranged
between the first electrode and the second electrode, so as to
cover the first surface of the first electrode.
Inventors: |
NAITO; Katsuyuki; (Tokyo,
JP) ; YOSHINAGA; Norihiro; (Kawasaki, JP) ;
MEI; Wu; (Yokohama, JP) ; TOMIMATSU; Norihiro;
(Mitaka, JP) ; YAGI; Ryosuke; (Yokohama, JP)
; YOKOTA; Masahiro; (Fukaya, JP) ; OOTA;
Hideo; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA |
Minato-ku |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Minato-ku
JP
|
Family ID: |
55532851 |
Appl. No.: |
15/065332 |
Filed: |
March 9, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2015/056547 |
Mar 5, 2015 |
|
|
|
15065332 |
|
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Current U.S.
Class: |
204/252 |
Current CPC
Class: |
C25B 13/08 20130101;
C25B 9/08 20130101; C02F 2201/46115 20130101; C25B 13/04 20130101;
C02F 1/46109 20130101; C02F 2001/46161 20130101; C25B 1/265
20130101; C25B 11/03 20130101; C02F 1/4674 20130101; C25B 13/02
20130101; C25B 1/13 20130101; C02F 2001/46157 20130101 |
International
Class: |
C25B 9/08 20060101
C25B009/08; C25B 1/13 20060101 C25B001/13; C25B 1/26 20060101
C25B001/26; C25B 13/04 20060101 C25B013/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 19, 2014 |
JP |
2014-192015 |
Claims
1: An electrode unit comprising: a first electrode including: a
first surface, a second surface located on an opposite side to the
first surface, a plurality of first pores opened in the first
surface, a plurality of second pores opened in the second surface
and having an opening area greater than that of the first pores, a
plurality of the first pores communicating with a respective one of
the second pores; a second electrode opposing the first surface of
the first electrode; and a continuous porous membrane arranged
between the first electrode and the second electrode, so as to
cover the first surface of the first electrode.
2: The electrode unit of claim 1, wherein an opening area of the
first pores opened in the first surface is 0.01 to 4 mm.sup.2.
3: The electrode unit of claim 1, wherein an opening area of the
second pores opened in the second surface is 1 to 1600
mm.sup.2.
4: The electrode unit of claim 1, wherein a number density of the
first pores per unit area is higher than that of the second pores
per unit area.
5: The electrode unit of claim 1, wherein a catalytic layer is
formed on the first surface and the second surface of the
electrode, and an amount of the catalytic layer per unit area
differs from the first surface to the second surface.
6: The electrode unit of claim 1, wherein the first pores are
formed to have a tapered surface or a curved surface which widens
towards the first surface.
7: The electrode unit of claim 1, wherein the first electrode
includes recess portions formed in the first surface, and the first
surface is formed flat except for the first pores and the recess
portions.
8: The electrode unit of claim 7, wherein an average surface
roughness of a flat portion of the first electrode is 10% or less
of an average thickness of the porous membrane.
9: The electrode unit of claim 1, wherein an opening ratio of first
pores located in a central portion of the first electrode is less
than an opening ratio of first pores located in a peripheral
portion of the first electrode.
10: The electrode unit of claim 1, further comprising: an
electrically insulating film which inhibits liquid from passing
therethrough and is provided on at least a portion of the first
surface of the first electrode.
11: The electrode unit of claim 1, wherein the second electrode has
a porous structure including a plurality of through-holes.
12: The electrode unit of claim 1, wherein the porous membrane is a
polymer membrane containing a fluorine atom or a chlorine atom in a
main chain thereof.
13: The electrode unit of claim 1, wherein the porous membrane is a
glass cloth.
14: The electrode unit of claim 1, wherein the porous membrane is a
membrane including in-planerly or three-dimensionally irregular
pores and containing inorganic oxide.
15: The electrode unit of claim 1, wherein the porous membrane is a
multi-layer film in which a plurality of porous films having
different pore diameters are stacked one on another.
16: The electrode unit of claim 1, further comprising: a diaphragm
provided between the first surface of the first electrode and the
second electrode, which allows at least one of ion and liquid to
pass therethrough, and wherein the porous membrane is interposed
between the first surface of the first electrode and the
diaphragm.
17: The electrode unit of claim 1, further comprising: two
diaphragms provided between the first electrode and the second
electrode so as to oppose each other; and an electrolyte holding
structure located between the two diaphragms to hold
electrolyte.
18: An electrolytic cell comprising: an electrolytic chamber and an
electrode unit of claim 1, provided in the electrolytic
chamber.
19: An electrolytic device comprising: an electrolytic cell
including an electrolytic chamber; an electrode unit of claim 1,
provided in the electrolytic chamber; and a power supply which
applies a voltage to the first electrode and the second electrode
of the electrode unit.
20: The electrolytic device of claim 19, wherein an electrolyte
containing chloride ions is electrolyzed by the electrode unit.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation application of PCT
Application No. PCT/JP2015/056547, filed Mar. 5, 2015 and based
upon and claiming the benefit of priority from Japanese Patent
Application No. 2014-192015, filed Sep. 19, 2014, the entire
contents of all of which are incorporated herein by reference.
FIELD
[0002] Embodiments described herein relate generally to an
electrode unit, an electrolytic cell comprising the electrode unit
and an electrolytic device.
BACKGROUND
[0003] In recent years, an electrolytic device for electrolyzing
water and producing electrolyzed water which has various functions,
such as ionized alkaline water, ozone water or aqueous hypochlorous
acid has been provided. Of the electrolyzed water, aqueous
hypochlorous acid has excellent sterilizing power and also is safe
to human health; therefore it has been approved as a food
additive.
[0004] As an electrolytic device, an electrolyzed-water production
device comprising, for example, a three-chamber electrolytic cell
is proposed. The inside of the electrolytic cell is divided into
three chambers, namely, an intermediate chamber, and also an anode
chamber and a cathode chamber located on both side of the
intermediate chamber. The anode chamber and the cathode chamber are
provided with an anode and a cathode, respectively. As the
electrodes, a porous-structure type is employed, in which a great
number of pores are made by processing such as expanding, etching
or punching in a metal plate matrix.
[0005] In this type of electrolytic device, for example, salt water
is supplied to the intermediate chamber, and water is supplied to
the anode and cathode chambers. The salt water in the intermediate
chamber is electrolyzed by the cathode and the anode. In this
manner, aqueous hypochlorous acid is produced from gaseous chlorine
produced by the anode. Aqueous sodium hydroxide is produced in the
cathode chamber. The produced hypochlorous acid is used as
sterilizing water. The aqueous sodium hydroxide is used as a
cleaning solution.
[0006] In the three-chamber electrolytic cell, the anion-exchange
membrane is degraded easily by chlorine or hypochlorous acid. When
the electrode having a porous configuration adheres tightly to the
ion-exchange membrane (electrolyte membrane), stress is easily
concentrated on the edge portion of the pores of the electrode.
Thus, the diaphragm formed of, for example, a thin electrolyte
membrane which is weak mechanically, is deteriorated easily. In
consideration of this factor, the following technique is suggested.
To reduce the degradation of the electrode by chlorine, nonwoven
fabric having overlaps or slits is inserted between the electrode
having a porous configuration and the electrolyte membrane.
[0007] However, if a porous membrane such as nonwoven fabric is
inserted between the electrode and the electrolytic membrane,
stress is applied to the porous membrane, causing variation in
thickness in the porous membrane. In other words, the thickness of
the porous membrane becomes uneven. The porous membrane of an
uneven thickness causes irregular electrolytic reaction, resulting
in reduction of the reactivity of the electrolytic device or
degradation of the electrolytic membrane.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a sectional view of an electrolytic device
according to a first embodiment.
[0009] FIG. 2 is a sectional view showing an electrode unit of the
electrolytic device according to the first embodiment.
[0010] FIG. 3 is an exploded perspective view of the electrode
unit.
[0011] FIG. 4 is a sectional view showing a manufacturing process
of an electrode.
[0012] FIG. 5 is a sectional view of an electrolytic device
according to a second embodiment.
[0013] FIG. 6 is a perspective view of the electrode unit according
to the second embodiment.
[0014] FIG. 7 is a sectional view of an electrode unit of an
electrolytic device according to a third embodiment.
[0015] FIG. 8 is a perspective view of an electrode unit according
to a fourth embodiment.
[0016] FIG. 9 is a sectional view of an electrolytic device
according to a fifth embodiment.
[0017] FIG. 10 is a sectional view of an electrolytic device
according to a sixth embodiment.
[0018] FIG. 11 is a sectional view of an electrode unit according
to the third embodiment.
[0019] FIG. 12 is a perspective view of a first electrode and a
second electrode according to a modification.
[0020] FIG. 13 is a sectional view schematically showing a porous
membrane containing inorganic oxide and including pores formed in a
planarly or three-dimensionally irregular manner.
[0021] FIG. 14 is a sectional view schematically showing a porous
membrane consisting of a multi-layered film.
DETAILED DESCRIPTION
[0022] Various embodiments will be described in detail with
reference to drawings. In general, according to one embodiment, an
electrolytic device comprises an electrode unit. The electrode unit
comprises: a first electrode including a first surface; a second
surface located on an opposite side to the first surface, a
plurality of first pores opened in the first surface, a plurality
of second pores opened in the second surface and having an opening
area greater than that of the first pores, and a plurality of first
pores communicating with a respective one of the second pores; a
second electrode opposing the first surface of the first electrode;
and a continuous porous membrane interposed between the first
electrode and the second electrode, so as to cover the first
surface of the first electrode.
[0023] Throughout the embodiments, common structural members are
designated by the same reference symbols, and the explanation
thereof will not be repeated. Further, the drawings are schematic
diagrams designed to assist the reader to understand the
embodiments easily. Thus, there may be sections where the shape,
dimensions, ratio, etc. are different from those of the actual
devices, but they can be re-designed as needed with reference to
the following explanations and publicly known techniques. For
example, the electrodes are illustrated in plane in these figures,
but they may be curved or formed in cylindrical according to the
shape of the respective electrode units.
First Embodiment
[0024] FIG. 1 is a diagram briefly showing an electrolytic device
according to the first embodiment. The electrolytic device 10
comprises, for example, a two-chamber electrolytic cell 11, and an
electrode unit 12 provided in the electrolytic cell 11. The
electrolytic cell 11 is formed into a flat rectangular box, the
inside of which is divided by an electrode unit into two
compartments, namely, an anode chamber 16 and a cathode chamber 18
by a dividing wall 14 and electrode unit 12.
[0025] The electrode unit 12 comprises a first electrode (anode) 20
located in the anode chamber 16, a second electrode (a
counterelectrode or a cathode) 22 located in the cathode chamber
18, and a porous membrane 24 and a diaphragm provided between the
first and second electrodes.
[0026] The electrolytic device 10 comprises a power supply 30 to
drive the first and second electrodes 20 and 22 of the electrode
unit 12, an ammeter 32, a voltmeter 34 and a control device 36 that
controls the members. A flow channel for liquid may be provided in
the anode chamber 16 and the cathode chamber 18. For example, a
pipe or a pump for supplying liquid from outside or discharging
liquid may be connected to the anode chamber 16 and the cathode
chamber 18. A porous spacer may be provided between the electrode
unit 12 and the anode chamber 16 or the cathode chamber 18.
[0027] Next, the electrode unit 12 will be described in detail.
FIG. 2 is a sectional view of the electrode unit. FIG. 3 is an
exploded perspective view of the electrode unit.
[0028] As shown in FIGS. 2 and 3, the first electrode 20 has a
porous structure in which numerous through-holes are formed in a
matrix 21 of, for example, a rectangular metal plate. The matrix 21
includes a first surface 21a and a second surface 21b opposing and
substantially parallel to the first surface 21a. The interval
between the first surface 21a and the second surface 21b, in other
words, the thickness of the matrix 21, is defined as T1. The first
surface 21a opposes the porous membrane 24 and the second surface
21b opposes the anode chamber 16.
[0029] A plurality of first pores 40 of, for example, a square
shape, are formed in the first surface 22a of the matrix 21 to open
on the first surface 22a. Moreover, a plurality of second pores 42
are formed in the second surface 22b to open on the second surface
22b. The opening area of the second pores 42 is greater than that
of the first pores 40. The first pores 40 made on the porous
membrane 24 side, have a dimension R1 of the opening, which is less
than a dimension R2 of the openings of the second pores 42 of, for
example, a square shape. Further, the first pores 40 are more in
number than the second pores 42. The depth of the first pores 40 is
T2 and the depth of the second pores 42 is T3, and T2+T3=T1. In
this embodiment, the holes are made such that T2<T3.
[0030] In this embodiment, the second pores 42 are formed into, for
example, a square shape to be arranged in a matrix on the second
surface 22b. The circumferential wall which defines each second
pore 42 may be formed to have a tapered surface 42a or curved
surface so that the hole enlarges toward the second surface 22b
side from the bottom of the hole to the opening. The interval
between adjacent second pores 42, that is, the width of a linear
portion 60a of the electrode is set to W2. Note that the second
pores 42 are not limited to a rectangular shape, but may take
various other forms. Moreover, the second pores 42 may not
necessarily be arranged regularly, but may be at random.
[0031] The opening diameter of the first pores 40 is preferably
less in order to make the pressure uniform. However, the first
pores 40 need to be large to the extent that substance diffusion
can be prevented. In case of a square, the length of each side of
the opening is preferably 0.1 to 2 mm, and is more preferably 0.3
to 1 mm. The opening may take a variety of forms such as a square,
a rectangle, a rhomboid, a circle and an ellipse, and the vertices
of a square, a rectangle or a rhomboid may be rounded. The opening
area is preferably 0.01 to 4 mm.sup.2 in the same manner as the
above-described square. The opening area is more preferably 0.1 to
1.5 mm.sup.2. The opening area is further preferably 0.2 to 1
mm.sup.2. The ratio of the opening area to the electrode area
including the opening (in other words, the opening ratio) is
preferably 0.05 to 0.5, and is more preferably 0.1 to 0.4, and is
further preferably 0.15 to 0.3. If the opening ratio is excessively
less, outgassing is difficult. If the opening ratio is excessively
great, electrode reaction is inhibited.
[0032] The first pores 40 are formed into, for example, a square
shape and are arranged in a matrix on the first surface 21a. The
circumferential wall which defines each first pore 40 may be formed
to have a tapered surface 40a or curved surface so that the
dimension enlarges from the bottom of the hole to the opening, in
other words, to the first surface 22a. In this embodiment, a
plurality, for example, nine of first pores 40 oppose a respective
second pore 42 and communicate therewith to be made all the way
through the matrix 21. An interval W1 between adjacent first pores
40 is set so as to be less than an interval W2 between second pores
42. With this structure, the number density of the first pores 40
in the first surface 21a is sufficiently greater than that of the
second pores 42 in the second surface 21b.
[0033] Various shapes may be employed for each second pore 42, such
as a square, a rectangle, a rhomboid, a circle or an ellipse. The
opening dimension of each second pore 42 is preferably great in
order to facilitate outgassing. However, if the opening dimension
is great, the electrical resistance is increased. Therefore, the
second pores 42 cannot be significantly enlarged. In the case of
the square opening, one side is preferably 1 to 40 mm, more
preferably 2 to 30 mm, and further preferably 3 to 20 mm. The
opening may take a variety of forms such as a square, a rectangle,
a rhomboid, a circle and an ellipse, while the opening area is
preferably 1 to 1600 mm.sup.2 in the same manner as the
above-described square. The opening area of the second pores 42 is
more preferably 4 to 900 mm.sup.2, and is further preferably 9 to
400 mm.sup.2. For example, the opening may be shaped as a rectangle
or an ellipse which is long in one direction so as to connect an
end and the other end of the electrode.
[0034] For the matrix 21 of the first electrode 20, a valve metal
such as titanium, chromium or aluminum, or an alloy of these, or a
conductive metal can be used. Out of these materials, titanium is
preferable. It may be desirable, depending on the electrolytic
reaction, to form an electrolytic catalyst (catalyst layer) on the
first surface and the second surface of the electrode. When used as
an anode, it is desirable to use a precious metal catalyst such as
platinum or an oxide catalyst such as iridium oxide, as the matrix
itself of the electrode. The amount of electrocatalyst per unit
area on one surface of the electrode may differ from that on the
other surface thereof. In this manner, for example, a side reaction
may be prevented.
[0035] Further, the first pores 40 may not necessarily be arranged
regularly, but may be at random. Furthermore, all the first pores
40 may not necessarily communicate with the second pores 42, but
there may be some first pores not communicating with a second pore
42. Thus, some first pores 40 may not communicate with the anode
chamber 16. For example, as shown in FIG. 12, the first pores 40
and 44 may be rectangles extending from near one end of the
electrode to near the other end, within which a plurality of
openings 41a and 45a communicating with the second pores 42 and 46
are arranged at certain interval. Only some of the first pores 40
and 44 may communicate with the second pores 42 and 44. The first
pores 40 and 44 which do not communicate with the second pores 42
and 44 can increase the electrode area.
[0036] Preferably, 85% or more of all of the first pores 40 and 44
have an opening area of 0.01 to 4 mm.sup.2. More preferably, 90% or
more, and further preferably, 95% or more of all of the first pores
40 have an opening area of 0.01 to 4 mm.sup.2.
[0037] The first electrode 20 can be manufactured by, for example,
an etching method using a mask. FIG. 4 briefly shows the
manufacturing method thereof. As shown in FIGS. 4(a) and (b), one
flat matrix 21 is prepared. Resist films 50a and 50b are applied to
the first and second surfaces 22a and 22b of the matrix 21. Then,
as shown in FIG. 4(c), the resist films 50a and 50b are exposed
using an optical mask (not shown) and thus etching masks 52a and
52b are formed, respectively. As shown in FIG. 4(d), wet etching is
applied to the first and second surfaces 22a and 22b of the matrix
21 via the masks 52a and 52b with solution. In this manner, a
plurality of first pores 40 and a plurality of second pores 42 are
formed. Subsequently, the first electrode 20 is obtained by
removing the masks 52a and 52b.
[0038] The shape of the tapered or curved surface of the first and
second pores 40 and 42 can be controlled based on the material of
the matrix 21 and etching conditions. The depth of the first pores
40 is T2, and the depth of the second pores 42 is T3. As stated
above, the first and second pores are formed such that T2<T3. In
etching, both surfaces of the matrix 21 may be etched at the same
time, or may be etched separately. The type of etching is not
limited to wet etching. For example, dry etching may be employed.
Moreover, not only etching but also processing by laser, precision
cutting or the like may be employed to manufacture the first
electrode 20.
[0039] As shown in FIGS. 1 to 3, in this embodiment, the second
electrode (counterelectrode) 22 is structured in the same manner as
the first electrode 20. More specifically, the second electrode 22
has a porous configuration in which a large number of through-holes
are formed in a matrix 23 made of, for example, a rectangular metal
plate. The matrix 23 includes a first surface 23a and a second
surface 23b opposing and substantially parallel to the first
surface 23a. The first surface 23a oppose a diaphragm 26. The
second surface 23b opposes the cathode chamber 18.
[0040] A plurality of first pores 44 are formed in the first
surface 23a of the matrix 23 to open on the first surface 23a.
Further, a plurality of second pores 46 are formed in the second
surface 23b to open on the second surface 23b. The opening area of
the first pores 42 on the diaphragm 26 is less than that of the
second pores 44. Further, the first pores 44 are more in number
than the second pores 46. The depth of the first pores 44 is less
than that of the second pores 46.
[0041] A plurality, for example, nine of first pores 44 are
provided to oppose one second pore 46. Each of these first pores 44
communicates with the second pore 26 so as to be made through the
matrix 23. The interval between adjacent first pores 44 is set so
as to be less than the interval between the second pores 46. With
this structure, the number density of the first pores 44 on the
first surface 23a is sufficiently greater than that of the second
pores 46 on the second surface 23b.
[0042] The porous membrane 24 and the diaphragm 26 are interposed
between the first surface 22a of the first electrode 20 and the
first surface 23a of the second electrode 22. The continuous porous
membrane 24 is formed in, for example, a rectangular shape so as to
have dimensions substantially equal to those of the first electrode
20, and opposes the whole first surface 21a. As the porous membrane
24, for example, a nonwoven fabric, cloth or a porous membrane
which is formed by a sol-gel method can be used, and various
materials may be used for the porous membrane. The porous membrane
needs to be chemically stable. In particular, it needs stability
to, especially, chlorine, hypochlorous acid or oxygen, or
resistance to acid or alkali. Further, when used to process foods,
for example, the following requirements should be met. That is,
when it is a polymer, monomers or the like must not dissolve at
amount determined by the law or more, or when it is an inorganic
material, heavy metal ion must not dissolve at amount determined by
the law or more. Mechanically, when the porous membrane is solely
used without an undercoat member, it is important for the membrane
to be handled easily, and therefore the thickness thereof is
preferably 20 to 500 .mu.m. If the porous membrane is formed
directly on an electrode, it may be thin, but in order for the
membrane to exhibit its properties, the thickness is preferably 50
nm or greater. Of these porous membranes, a polymer membrane
containing a fluorine atom or a chlorine atom in its main chain,
glass cloth or a membrane including irregular continuous pores and
containing inorganic oxide, is especially chemically stable and
preferable. As the polymer membrane, Teflon is particularly
preferable. Hydroxide, alkoxide, oxyhalide or hydrate may be
contained in the inorganic oxide. When the inorganic oxide is
prepared by the hydrolysis of metal halide or metal alkoxide, a
composite thereof may be easily obtained though it depends on the
temperature of the subsequent treatment. The polymer membrane,
glass cloth and inorganic oxide may be combined, and for example,
the polymer membrane and glass cloth may be covered by an inorganic
oxide. As shown in FIG. 13, if an inorganic oxide film having
irregular pores in a plane or in a three-dimensional manner is used
as the porous membrane 24, it may also function as a diaphragm. In
other words, the diaphragm 26 may be omitted.
[0043] As shown in FIG. 14, for the porous membrane 24, a
multilayer film including a plurality of porous membranes 27a and
27b having different pore diameters may be used. In this case, if
the pore dimension of the porous membrane 27b located on the
diaphragm 26 side is set greater than that of the porous membrane
27b located on the first electrode 20 side, migration of ions is
more facilitated, and the stress concentration due to the pores of
the electrode can be reduced. This is because as the opening on the
diaphragm 26 side is greater, the ion migration by diffusion
becomes easier. When the first electrode 20 is used for the anode,
a positive potential is applied. Therefore, even if the pore
diameter on the first electrode 20 side is less, anions are easily
attracted to the first electrode 20. If the pore diameter on the
electrode 20 side is great, the produced chlorine or like is easily
diffused to the porous membrane 24 side.
[0044] The pore diameter on the surface of the porous membrane 24
can be measured by a high-resolution scanning electron microscope
(SEM). The pores inside the porous membrane can be measured by
cross-sectional SEM observation.
[0045] As shown in FIGS. 2 and 3, the diaphragm 26 is formed into,
for example, a rectangular shape with dimensions substantially
equal to those of the first electrode 20, and also provided between
the first surface 23a of the electrode 22 and the porous membrane
24. The diaphragm 26 is tightly attached to the entire first
surface 23a of the second electrode 22, and further to the porous
membrane 24.
[0046] The diaphragm 26 located between the first and second
electrodes 20 and 22 is a film which allows ions and/or liquid to
pass therethrough. For the diaphragm 26, various electrolyte
membranes and porous membranes having nanopores may be used. For
the electrolyte membrane, a polymer electrolyte membrane, for
example, a cation-exchange solid polymer electrolyte membrane, more
specicially, a cation-exchange membrane, an anion-exchange membrane
or a hydrocarbon-based film may be used. Examples of the
cation-exchange membrane are NAFION 112, 115 and 117 (trademark of
E. I. du Pont de Nemours & Co.), Flemion (trademark of Asahi
Glass Co., Ltd.), ACIPLEX (trademark of Asahi Chemical Co., Ltd.)
and GOA SELECT (trademark of W. L. Goa and associates co.). An
example of the anion-exchange membrane is A201 of Tokuyama, Inc.
Usable examples of the porous membranes having nanopores are porous
ceramics such as porous glass, porous alumina, porous titania and
porous zeolite, and porous polymers such as porous polyethylen,
porous propylene, porous teflon and porous polyimide.
[0047] The first electrode 20, the porous membrane 24 and the
second electrode 22 having the above-described structures are
brought into contact with each other by pressing them in a state
where the porous membrane 24 is interposed between the first
electrode 20 and the second electrode 22. In this manner, the
electrode unit 12 is obtained.
[0048] As shown in FIG. 1, the electrode unit 12 is provided in the
electrolytic cell 11 and is attached to the dividing wall 14. The
electrolytic cell 11 is divided into the anode chamber 16 and the
cathode chamber 18 by the dividing wall 14 and the electrode unit
12. Thus, the electrode unit 12 is disposed in the electrolytic
cell 11 so that the direction where the components which constitute
this are in contact with each other is, for example, horizontal.
The first electrode 20 of the electrode unit 12 faces the anode
chamber 16. The second electrode 22 faces the cathode chamber
18.
[0049] In the electrolytic device 10, both poles of the power
supply 30 are electrically connected to the first electrode 20 and
the second electrode 22. The power supply 30 applies a voltage to
the electrode unit 12 under the control of the control device 36.
The voltmeter 34 is electrically connected to the first electrode
20 and the second electrode 22 and detects the voltage applied to
the electrode unit 12. The detection data is supplied to the
control device 36. The ammeter 32 is connected to the voltage
application circuit of the electrode unit 12 and detects the
current flowing in the electrode unit 12. The detection data is
supplied to the control device 36. The control device 36 controls
the application of voltage or load for the electrode unit 12 by the
power supply 30 based on the detected data in accordance with the
program stored in the memory. The electrolytic device 10 applies a
voltage or load between the first electrode 20 and the second
electrode 22 in a state where the substance for reaction is
supplied to the anode chamber 16 and the cathode chamber 18. In
this manner, the electrochemical reaction for electrolysis is
advanced. The electrolytic device 10 of the present embodiment
should preferably electrolyze an electrolyte containing chloride
ions.
[0050] According to the electrolytic device and the electrode unit
having the above-described structure, in the first electrode 20,
the diameter (opening area) of the first pores 40 formed in the
first surface 22a on the porous membrane 24 side is made less than
that of the second pores 42. Thus, the number density thereof is
increased. This structure allows the reduction in the concentration
of stress applied from the first electrode 20 side to the porous
membrane 24. As a continuous membrane, the porous membrane 24 is
brought into contact with the whole first surface 21a of the first
electrode 20. Thus, the holes of the first electrode 20 are covered
by the porous membrane 24. The distance between the first electrode
20 and the diaphragm 26 can be easily maintained equally over the
whole surface. That is, distribution in the thickness of the porous
membrane 24 can be prevented and it becomes possible to maintain
the thickness of the porous membrane 24 uniformly. This structure
enables the electrolytic reaction to occur uniformly, thereby
improving the reaction efficiency of the electrolytic device and
preventing the degradation of the electrolyte membrane.
[0051] Further, the first electrode 20 is formed to have the first
pores 40 with a tapered or curved shape which enlarges towards the
first surface side of the electrode. With this structure, the
contact angle between the first pores 40 and the porous membrane 24
is obtuse, thereby making it possible to further reduce the
concentration of stress on the porous membrane 24 from the first
electrode 20 side. Note that the first surface 22a on the porous
membrane 24 side of the first electrode 20 is preferably
substantially flat except for recess portions. The recess portions
may be the first pores described above or recessed sections which
will be described later.
[0052] When the opening area of the second pores 42 formed in the
second surface 22b of the first electrode 20 is increased and the
number density is reduced, width W2 of the linear portions between
the second pores 42 can be made sufficiently great. Thus, the
mechanical strength of the first electrode 20 can be maintained
high and the electric resistance can be reduced.
[0053] In the first embodiment having the above-described
structures, it is possible to obtain a long-life,
high-reaction-efficiency electrode unit and electrolytic
device.
[0054] Note that in the first embodiment, the second electrode 22
has a porous structure with the first and second pores with
different diameters, but it is not limited to this. For example, a
plate electrode without a through-hole may be employed. Or such an
electrode may be employed as well, that an electrode substrate is
processed to have through-holes of the same diameter on the first
surface and the second surface. The second electrode 22 and the
diaphragm 26 may be in contact with each other, or a separate
structural member may be interposed therebetween.
[0055] Next, an electrolytic cell and an electrolytic device
according to another embodiment will be described. Note that in the
other embodiments described below, the same reference symbols are
given to the same structural elements as the first embodiment
above, and the detailed explanations thereof are omitted. The
portions different from those of the first embodiment will be
mainly discussed.
Second Embodiment
[0056] FIG. 5 is a sectional view showing an electrode unit of an
electrolytic device according to the second embodiment and FIG. 6
is a perspective view of an electrode.
[0057] According to the second embodiment, in the electrode unit
12, the first surface 22a of the first electrode 20 is formed flat,
and the first pores 40 described above are formed in the first
surface 22a so as to be made through the matrix 21. A plurality of
recess portions 54 are formed in the first surface 22a of the first
electrode 20. In other words, the first electrode 20 includes
recess portions 54, which are recesses which are not made through
the matrix 21. The recess portions 54 are formed from, for example,
continuous grooves extending between the first pores 40. Or the
recess portions 54 may be a great number of independent dot-like
recesses.
[0058] The porous membrane 24 is tightly attached to the first
surface 22a of the first electrode 20 and further opposes the first
pores 40 and recess portions 54 to stop them.
[0059] The first surface 22a of the first electrode 20 is
preferably flat except for the first pores 40 and the recess
portions 54. With the recess portions 54, the electrode area can be
increased, and also, flow channels for extracting the produced gas
can be created. By forming the first surface 22a of the first
electrode 20 substantially plate-like except for the recess
portions 54, the concentration of the stress on the porous membrane
24 can be further reduced. Although it vary depending on the
thickness of the porous membrane 24, the flatness of the first
surface 22a, or the average surface roughness, is preferably 10% or
less of the average thickness of the porous membrane 24, more
preferably, 5% or less, or further preferably, 2% or less. The
average surface roughness can be examined by cross-sectional SEM
observation.
[0060] Note that not only the first electrode 20, but also the
first surface 23a of the second electrode 22 may be provided with a
plurality of recess portions.
Third Embodiment
[0061] FIG. 7 is a sectional view showing an electrode unit of an
electrolytic device according to the third embodiment. According to
the third embodiment, an electrically insulating film 56 which does
not allow liquid to pass, is formed on at least a portion of the
surface of the first electrode 20. In the first electrode 20, gas
such as chlorine produced by the reaction is not easily discharged
on the first surface 22a, which is widely in contact with the
porous membrane 24 on the diaphragm 26 side. For this reason, the
diaphragm 26 is deteriorated easily by the produced gas. Here, by
covering the region of the first surface 22a where the first pores
40 are not formed with the insulating film 56, the production of
the reactive gas is suppressed in this region, and thus the
deterioration of the diaphragm 26 can be prevented. In this
embodiment, the insulating film 56 is formed on both the surfaces
of the broad linear portion (width W2) of the first electrode
20.
[0062] However, the reactive area of the first electrode 20
decreases by forming the insulating film 56. Therefore, it is
desirable to have the reaction of the first electrode 20 occur
sufficiently in the portion where the produced gas can easily
escape. Further, an electrically insulating film 57 may be formed
for cover on the second surface 22b of the first electrode 20
located on the opposite side to the diaphragm 26. When such an
electrode unit 12 is used for a three-chamber electrolytic cell, a
side reaction on the second surface 22b side can be reduced. Note
that a portion of the insulating film may protrude in the sectional
direction of the electrode.
Fourth Embodiment
[0063] FIG. 8 is a perspective view showing an electrode unit of an
electrolytic device according to the fourth embodiment. According
to the fourth embodiment, an interval W3 between adjacent first
pores 40 formed in the central portion of the electrode is set to
be greater than an interval W1 between those formed in the
peripheral portion of the electrode. With this structure, the
opening ratio (the ratio of the opening area to the electrode area
including the opening area) of the central portion of the first
electrode 20 is smaller than that of the peripheral portion of the
first electrode 20. Therefore, the electric resistance can be made
lower in the central portion of the first electrode 20 than in the
peripheral portion, thereby making it possible to reduce the
voltage rise in the central portion of the electrode even in the
case where power is supplied from the periphery of the electrode to
the electrode. In order to reduce the opening ration, the opening
area of the first pores 40 formed in the central portion of the
first electrode 20 can be reduced by reducing the open area of
those formed in the periphery as shown in FIG. 8, or the number of
pores can be reduced in the central portion.
Fifth Embodiment
[0064] FIG. 9 is a sectional view showing an electrolytic device
according to the fifth embodiment. In the fifth embodiment, an
electrolytic cell 11 of an electrolytic device 10 is structured as
a one-chamber electrolytic cell comprising only one electrolytic
chamber 17. An electrode unit 12 is provided in the electrolytic
chamber 17. For example, a pipe or a pump for supplying an
electrolyte from outside or discharging an electrolyte may be
connected to the electrolytic chamber 17.
[0065] In the one-chamber electrolytic cell 11, a second electrode
(counterelectrode) 22 of the electrode unit 12 preferably has a
porous configuration in a manner similar to that of the first
electrode 20. The porous configuration enables the electrode area
to be increased.
Sixth Embodiment
[0066] FIG. 10 is a sectional view showing an electrolytic device
according to the sixth embodiment and FIG. 11 is a sectional view
of an electrode unit in the electrolytic device.
[0067] As shown in FIG. 10, an electrolytic device 10 comprises a
three-chamber electrolytic cell 11 including an electrode unit 12.
The electrolytic cell 11 is formed into a flat rectangular box
shape, the inside of which is divided into three chambers,
specifically, an anode chamber 16, a cathode chamber 18 and an
intermediate chamber 19 formed between the electrodes, by a
dividing wall 14 and the electrode unit 12.
[0068] The electrode unit 12 comprises a first electrode (anode) 20
disposed in the anode chamber 16, a second electrode
(counterelectrode or cathode) 22 disposed in the cathode chamber
18, two diaphragms 26a and 26b provided between the first and
second electrodes, a porous membrane 24a interposed between the
first electrode 20 and the diaphragm 26a, and a porous membrane 24b
interposed between the second electrode 22 and the diaphragm 26b.
The diaphragms 26a and 26b oppose each other with an intervening
space such that they are parallel to each other. The intermediate
chamber (electrolyte chamber) 19 which holds an electrolyte is
formed between the diaphragms 26a and 26b. A holder 25 which holds
an electrolyte may be provided in the intermediate chamber 19. The
first and second electrodes 20 and 22 may be connected to each
other by a plurality of insulating bridges 60.
[0069] The electrolytic device 10 comprises a power supply 30 which
applies a voltage to the first and second electrodes 20 and 22 of
the electrode unit 12, an ammeter 32, a voltmeter 34 and a control
device 36 which controls these elements. A flow channel for liquid
may be provided in the anode chamber 16 and the cathode chamber 18.
For example, a pipe or a pump for supplying liquid from outside or
discharging liquid may be connected to the anode chamber 16 and the
cathode chamber 18. A porous spacer may be provided between the
electrode unit 12 and the anode chamber 16 or the cathode chamber
18 depending on the case.
[0070] As shown in FIGS. 10 and 11, in the electrode unit 12, the
first and second electrodes 20 and 22 are formed to have a porous
configuration similar to that of the first embodiment discussed
above. The continuous porous membrane 24 is formed in, for example,
a rectangular shape so as to have dimensions substantially equal to
those of the first electrode 20, and opposes the whole first
surface 21a. As the porous membranes 24a and 24b, for example, a
nonwoven fabric, cloth or a porous membrane which is formed by a
sol-gel method can be used, and various materials may be used for
the porous membranes. Of these porous membranes, a polymer membrane
containing a fluorine atom or a chlorine atom in its main chain,
glass cloth or a membrane including irregular continuous pores and
containing inorganic oxide, is especially chemically stable and
preferable. If an inorganic oxide film having irregular pores is
used as the porous membranes 24a and 24b, they can also function as
diaphragms. The porous membranes 24 and 27 may be multilayer films
of a plurality of porous membranes having different
pore-diameters.
[0071] The diaphragm 26a is formed in, for example, a rectangular
shape so as to have dimensions substantially similar to those of
the first electrode 20, and opposes the first surface 22a of the
first electrode 20. The porous membrane 24a is interposed between
the first surface 22a of the first electrode 20 and the diaphragm
26a, and adheres tightly to the first electrode 20 and the
diaphragm 26a.
[0072] The diaphragm 26b is formed in, for example, a rectangular
shape so as to have dimensions substantially equal to those of the
second electrode 22, and opposes the first surface 23a of the
second electrode 22. The porous membrane 24b is interposed between
the first surface 23a of the second electrode 22 and the diaphragm
26b, and adheres tightly to the second electrode 22 and the
diaphragm 26b.
[0073] The diaphragms 26a and 26b are films which allow ions and/or
liquid to pass therethrough. For the diaphragm 26, various
electrolyte membranes and porous membranes having nanopores may be
used.
[0074] In the sixth embodiment having the above-described
structure, effects similar to those of the first embodiment can be
obtained. It is possible to obtain a long-life,
high-reaction-efficiency electrode unit and electrolytic
device.
[0075] Next, various examples and comparative example will be
described.
Example 1
[0076] For the electrode matrix 21, a flat titanium plate having a
thickness (T1) of 0.5 mm is employed. This titanium plate is etched
as shown in FIG. 4. In this manner, an electrode is manufactured.
In this electrode, a thickness T2 of a region including the
smaller-dimension first pores 40 (depth of the first pores) is 0.15
mm, and a thickness T3 of a region including the larger-dimension
second pores 42 (depth of the second pores) is 0.35 mm. The first
pores 40 have a square shape whose vertices are rounded, and one
side R1 of the square obtained by extrapolating the straight line
part is 0.57 mm. The second pores 42 have a square shape, and one
side R2 thereof is 2 mm. A width W1 of a linear portion formed
between adjacent first pores 40 is 0.1 mm and a width W2 of a wide
linear portion formed between adjacent second pores 42 is 1.0
mm.
[0077] The electrode matrix 21 is processed in advance in a 10-wt %
oxalic acid aqueous solution at 80.degree. C. for an hour.
1-butanol is added to iridium chloride (IrCl.sub.3.nH.sub.2O) to be
adjusted to 0.25M (Ir) and the mixture is applied to the surface
(first surface) of the electrode matrix 21 in which the first pores
40 are formed, followed by drying and burning. In this case, drying
is performed at 80.degree. C. for 10 minutes, and the burning is
performed at 450.degree. C. for 10 minutes. The above-described
application, drying and burning are repeated five times. The
electrode matrix made through this process is cut out such that the
reactive electrode area can be 3 cm.times.4 cm. In this manner, the
first electrode (anode) 20 is manufactured. The average coarseness
of the flat portion of the first electrode 20 except for the recess
portions is measured by AFM to be 1 .mu.m.
[0078] Further, the second electrode (a counterelectrode, a
cathode) 22 is produced by sputtering platinum onto the first
surface of the electrode matrix in which the first pores are
formed.
[0079] The electrode unit 12 shown in FIG. 11 is manufactured,
using the first and second electrodes thus obtained. For the
diaphragm 26a, an anion-exchange membrane, A201 of Tokuyama, Inc is
employed, and for the diaphragm 26b, NAFION (trademark) 117 is
employed. A glass cloth (75-.mu.m-thick) is used for the porous
membranes 24a and 24b. As the holder 25 which holds the
electrolyte, porous polystyrene having a thickness of 5 mm is
provided in the intermediate chamber (electrolyte chamber) 19. The
first and second electrodes, the porous membrane, the dividing wall
and porous polystyrene are put and fixed together using silicone
seal adhesive and a screw, to form the electrode unit 12. Using
this electrode unit 12, the electrode unit 12 and the electrolyte
device 10 shown in FIG. 10 are manufactured.
[0080] The anode chamber 16 and the cathode chamber 18 of the
electrolytic cell 11 are each formed from a vinyl-chloride
container in which a straight pathway is formed. The control device
36, the power supply 30, the voltmeter 34 and the ammeter 32 are
provided. A pipe and a pump for supplying water to the anode and
cathode chambers 16 and 18 are connected to the electrolytic cell
11. Further, a saturated salt water tank, a pipe and a pump for
circulating a saturated salt water to the holder (porous
polystyrene) 25 of the electrode unit 12 are connected to the
electrode unit. The electrolytic device 10 is operated for
electrolysis at a voltage of 5V and a current of 1.5 A. Aqueous
hypochlorous acid is produced on the anode 20 side, and aqueous
sodium hydroxide is produced on the cathode 22 side. Even after
continuous operation for 1000 hours, no substantial rise in voltage
or change in product concentration is observed. Thus, a stable
electrolytic treatment can be carried out.
Example 2
[0081] With a different mask used in the etching, a first electrode
20 is manufactured from an electrode matrix of 3.times.4 cm, having
a central portion of 1.times.1.4 cm, where first pores 40 each
having a square shape whose one side R1 has a length of 0.7 mm are
formed and a width W1 of a linear portion is 0.2 mm. The second
pores 42 have a square shape whose one side has a length of 2 mm.
The second pore formed in the central portion included the first
pores in an arrangement of 2.times.2. The other structures are the
same as those of Example 1. On these conditions, the electrode unit
12 and the electrolytic device 10 are manufactured.
[0082] The electrolytic device 10 is operated for electrolysis at a
voltage of 4.8 V and a current of 1.5 A. Aqueous hypochlorous acid
is produced on the anode 20 side, and aqueous sodium hydroxide is
produced on the cathode 22 side. Even after continuous operation
for 1000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 3
[0083] As the porous membrane, a nonwoven fabric made from
polyvinylidene chloride is used instead of the glass cloth. The
other structures are the same as those of Example 1. On these
conditions, the electrode unit 12 and the electrolytic device 10
are manufactured.
[0084] The electrolytic device 10 is operated for electrolysis at a
voltage of 5.1 V and a current of 1.5 A. Aqueous hypochlorous acid
is produced on the anode 20 side, and aqueous sodium hydroxide is
produced on the cathode 22 side. Even after continuous operation
for 1000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 4
[0085] As the porous membrane, a porous titanium oxide membrane
including irregular pores is used instead of the glass cloth. The
other structures are the same as those of Example 1. On these
conditions, the electrode unit 12 and the electrolytic device 10
are manufactured.
[0086] The electrolytic device 10 is operated for electrolysis at a
voltage of 5.2 V and a current of 1.5 A. Aqueous hypochlorous acid
is produced on the anode 20 side, and aqueous sodium hydroxide is
produced on the cathode 22 side. Even after continuous operation
for 1000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 5
[0087] As the porous membrane, a nonwoven fabric made from Teflon
is used instead of the glass cloth. The other structures are the
same as those of Example 1. On these conditions, the electrode unit
12 and the electrolytic device 10 are manufactured.
[0088] The electrolytic device 10 is operated for electrolysis at a
voltage of 5.0 V and a current of 1.5 A. Aqueous hypochlorous acid
is produced on the anode 20 side, and aqueous sodium hydroxide is
produced on the cathode 22 side. Even after continuous operation
for 1000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 6
[0089] A first electrode 20 is manufactured as in Example 1 and
electric-insulating polyvinyl chloride is applied selectively on a
wide linear portion (having a width of W2) to form an insulating
film by screen printing. The other structures are the same as those
of Example 1. On these conditions, the electrode unit 12 and the
electrolytic device 10 are manufactured.
[0090] The electrolytic device 10 is operated for electrolysis at a
voltage of 5.3 V and a current of 1.5 A. Aqueous hypochlorous acid
is produced on the anode 20 side, and aqueous sodium hydroxide is
produced on the cathode 22 side. Even after continuous operation
for 1000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 7
[0091] A second electrode (counterelectrode) 22 of a porous
structure is manufactured as in Example 1. As the diaphragm 26, a
porous glass film (50-.mu.m-thick) is employed. As the porous
membrane 24, a glass cloth (75-.mu.m-thick) is employed. They are
then put together using a silicone sealing material and screws to
form an electrode unit 12.
[0092] Using the electrode unit 12, a one-chamber electrolytic cell
11 and an electrolyte device 10 shown in FIG. 9 are manufactured. A
control device 36, a power supply 30, a voltmeter 34 and an ammeter
32 are provided. A pipe and a pump for supplying salt water to an
electrolytic chamber 17 are provided. The electrolytic device 10 is
operated for electrolysis at a voltage of 4.3 V and a current of
1.5 A to produce aqueous hypochlorous acid. Even after continuous
operation for 1000 hours, no substantial rise in voltage or change
in product concentration is observed. Thus, a stable electrolytic
treatment can be carried out.
Example 8
[0093] As the porous membrane, a polyphenylene sulfide porous
membrane coated with a film containing titanium oxide is employed
instead of the glass cloth. The polyphenylene sulfide porous
membrane coated with a film containing titanium oxide is used to
also serve as the diaphragms 26a and 26b. The other structures are
the same as those of Example 1. On these conditions, the electrode
unit 12 and the electrolytic device 10 are manufactured.
[0094] The electrolytic device 10 is operated for electrolysis at a
voltage of 4.8 V and a current of 1.5 A. Aqueous hypochlorous acid
is produced on the anode 20 side, and aqueous sodium hydroxide is
produced on the cathode 22 side. Even after continuous operation
for 2000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 9
[0095] As the porous membrane, a glass-made nonwoven fabric (filter
paper) coated with a film containing titanium oxide is employed
instead of the polyphenylene sulfide porous membrane coated with a
film containing titanium oxide. The other structures are the same
as those of Example 8. On these conditions, the electrode unit 12
and the electrolytic device 10 are manufactured.
[0096] The electrolytic device 10 is operated for electrolysis at a
voltage of 4.7 V and a current of 1.5 A. Aqueous hypochlorous acid
is produced on the anode 20 side, and aqueous sodium hydroxide is
produced on the cathode 22 side. Even after continuous operation
for 2000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 10
[0097] As the porous membrane, a glass-made nonwoven fabric (filter
paper) coated with a film containing zirconium oxide is employed
instead of the polyphenylene sulfide porous membrane coated with a
film containing titanium oxide. The other structures are the same
as those of Example 8. On these conditions, the electrode unit 12
and the electrolytic device 10 are manufactured.
[0098] The electrolytic device 10 is operated for electrolysis at a
voltage of 4.8 V and a current of 1.5 A. Aqueous hypochlorous acid
is produced on the anode 20 side, and aqueous sodium hydroxide is
produced on the cathode 22 side. Even after continuous operation
for 2000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 11
[0099] As the porous membrane, a membrane further coated with a
more precise film containing zirconium oxide on an electrode-side
surface of the porous membrane is employed instead of the
polyphenylene sulfide porous membrane coated with a film containing
titanium oxide. The other structures are the same as those of
Example 8. On these conditions, the electrode unit 12 and the
electrolytic device 10 are manufactured.
[0100] This electrolytic device 10 is operated for electrolysis at
a voltage of 4.9 V and a current of 1.5 A. Aqueous hypochlorous
acid is produced on the anode 20 side, and aqueous sodium hydroxide
is produced on the cathode 22 side. Even after continuous operation
for 2000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 12
[0101] As the porous membrane, a membrane coated with a Teflon
porous membrane further coated with a film containing zirconium
oxide is employed instead of the polyphenylene sulfide porous
membrane coated with a film containing titanium oxide. The other
structures are the same as those of Example 8. On these conditions,
the electrode unit 12 and the electrolytic device 10 are
manufactured.
[0102] This electrolytic device 10 is operated for electrolysis at
a voltage of 4.9 V and a current of 1.5 A. Aqueous hypochlorous
acid is produced on the anode 20 side, and aqueous sodium hydroxide
is produced on the cathode 22 side. Even after continuous operation
for 2000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 13
[0103] For the electrode matrix 21, a flat titanium plate having a
thickness T1 of 0.5 mm is employed. This titanium plate is etched
as shown in FIG. 4 to manufacture an electrode. In this electrode,
a thickness T2 of a region including the smaller-dimension first
pores 40 (depth of the first pores) is 0.15 mm, and a thickness T3
of a region including the larger-dimension second pores 42 (depth
of the second pores) is 0.35 mm. The first pores 40 have a rhomboid
shape whose long diagonal is 0.69 mm and short diagonal is 0.4 mm.
The second pores 42 have a rhomboid shape whose long diagonal line
has a length of 6.1 mm and short diagonal line has a length of 3.5
mm. A width W1 of a linear portion formed between adjacent first
pores 40 is 0.15 mm and a width W2 of a wide linear portion formed
between adjacent second pores 42 is 1 mm. The other structures are
the same as those of Example 1. On these conditions, the electrode
unit 12 and the electrolytic device 10 are manufactured.
[0104] This electrolytic device 10 is operated for electrolysis at
a voltage of 5.3 V and a current of 1.5 A. Aqueous hypochlorous
acid is produced on the anode 20 side, and aqueous sodium hydroxide
is produced on the cathode 22 side. Even after continuous operation
for 1000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Example 14
[0105] For the electrode matrix 21, a flat titanium plate having a
thickness T1 of 0.5 mm is employed. This titanium plate is etched
as shown in FIG. 4 to manufacture an electrode. In this electrode,
a thickness T2 of a region including the smaller-dimension first
pores 40 (depth of the first pores) is 0.15 mm, and a thickness T3
of a region including the larger-dimension second pores 42 (depth
of the second pores) is 0.35 mm. The first pores 40 have a square
shape whose one side R1 has a length of 0.57 mm. The second pores
42 have a rectangular shape whose long side has a length of 40 mm
and short side has a length of 4 mm. A width W1 of a linear portion
formed between adjacent first pores 40 is 0.1 mm and a width W2 of
a wide linear portion formed between adjacent second pores 42 is
1.0 rum. The other structures are the same as those of Example 1.
On these conditions, the electrode unit 12 and the electrolytic
device 10 are manufactured.
[0106] This electrolytic device 10 is operated for electrolysis at
a voltage of 5.8 V and a current of 1.5 A. Aqueous hypochlorous
acid is produced on the anode 20 side, and aqueous sodium hydroxide
is produced on the cathode 22 side. Even after continuous operation
for 1000 hours, no substantial rise in voltage or change in product
concentration is observed. Thus, a stable electrolytic treatment
can be carried out.
Comparative Example 1
[0107] An electrolytic device is manufactured in a similar manner
to that of Example 1 except that the continuous porous membrane is
not employed in this example. This electrolytic device is operated
for electrolysis at a voltage of 5 V and a current of 1.5 A.
Aqueous hypochlorous acid is produced on the anode side, and
aqueous sodium hydroxide is produced on the cathode side. After
continuous operation for 1000 hours, a significant rise in voltage
and a decrease in product concentration are observed. Thus, this
device did not exhibit a long-term stability.
Comparative Example 2
[0108] An electrolytic device is manufactured by forming
through-holes having a diameter of 1 mm in an electrode matrix by
punching to have the same opening ratio as that of the electrode of
Example 1. The other structures are the same as those of Example 1.
On these conditions, the electrode unit and the electrolytic device
are manufactured.
[0109] This electrolytic device is operated for electrolysis at a
voltage of 5.2 V and a current of 1.5 A. Aqueous hypochlorous acid
is produced on the anode side, and aqueous sodium hydroxide is
produced on the cathode side. After continuous operation for 1000
hours, a significant rise in voltage and a decrease in product
concentration are observed. Thus, this device did not exhibit a
long-term stability.
[0110] The present invention is not limited to the embodiments and
modifications described above but the constituent elements of the
invention can be modified in various manners without departing from
the spirit and scope of the invention. Various aspects of the
invention can also be extracted from any appropriate combination of
a plurality of constituent elements disclosed in the embodiments.
For example, some constituent elements may be deleted in all of the
constituent elements disclosed in the embodiments. Further, the
constituent elements described in different embodiments may be
combined arbitrarily.
[0111] For example, the first electrode and the second electrode
are not limited to rectangular shapes, but various other forms may
be selected. The first and second pores of the first electrode are
not limited to square shapes, and may have various other shapes
such as a rectangular, rhomboid, circular or elliptical shape.
Further, the material of each structural component is not limited
to that employed in the embodiments or examples discussed, but
various other materials may be selected as needed. The electrolytic
cell of the electrode device is not limited to a three-chamber
type, but it may as well be applied to a two-chamber- or
single-chamber type or any electrolytic cells with electrodes in
general. The electrolytes and product are not limited to salt or
hypochlorous acid, but may be developed into various electrolytes
and products.
* * * * *