(19) —
`
`Europaisches Patentamt
`
`European Patent Office
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`Office européen des brevets
`
`(11)
`
`EP 0 723 936 A2
`
`(12)
`
`EUROPEANPATENT APPLICATION
`
`(43) Date of publication:
`31.07.1996 Bulletin 1996/31
`
`(51) Intcl®: CO2F 1/46
`
`(21) Application number: 96300652.3
`
`(22) Date offiling: 30.01.1996
`
`(84) Designated Contracting States:
`DE FR GB
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`(30) Priority: 30.01.1995 JP 31848/95
`
`(71) Applicant: FIRST OCEAN CO., LTD.
`Tokyo (JP)
`
`
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`(72) Inventor: Sano, Yoichi
`Zushi-shi, Kanagawa-ken (JP)
`
`(74) Representative: Senior, Alan Murray
`J.A. KEMP & CO.,
`14 South Square,
`Gray’s Inn
`London WC1R SLX (GB)
`
`(54) Acomposite electrode construction for electrolysis of water
`
`This invention relates to a composite electrode
`(57)
`(7) for electrolysis of water, which is comprisedof a pan-
`el of which one surface (1) is made from electrically con-
`ductive material and another surface (2) is made from
`non-electrically conductive material. A plurality of holes
`
`3) are bored through said panel, and two said panels
`are arranged so as to hold a diaphragm (4) between the
`surface (2) of non-electric conductive material of each
`panel. The electrolysis reaction occurs at the outer side
`of the anode and cathode of said composite electrode
`(7).
`
`EP0723936A2
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`Printed by Jouve, 75001 PARIS (FR)
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`Figure. 1
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`Description
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`EP 0 723 936 A2
`
`This invention relates to an electrode which is used for electrolysis of water or water which includes electrolytes,
`and more particularly relates to an electrode for electrolysis to produce acid and alkaline ionized water.
`A method to produce acid and alkaline ionized water by electrolysis of water or water which includes electrolytes
`is a well-known technique. And by using this technique, a method of manufacturing healthy drinking water or sterile
`water is becoming popular. Many methods or equipments are proposedin prior arts, such as Japanese patent publi-
`cation 4-28239, 4-57394, Japanese Laid-open publication 6-47376, 6-55173 and 6-246268. Construction of an appa-
`ratus for producing ionized water is characterized as installing cathode and anodein water or water which includes
`electrolytes with a distance, separating the ionized water by a diaphragm between the two electrodes.
`Usually, to obtain a higher electrolysis efficiency, the distance between cathode and anode is designed to be as
`short as possible. As an electrolysis reaction occurs at the surface of two electrodes in water or water which includes
`electrolytes, acid and alkaline ions and gases are generated in two narrow spaces between the electrodes and a
`diaphragm. To obtain high electrolysis efficiency on the objecied water, generated ions musi be dispersed smoothly
`into water or water which includes electrolytes and generated gases mustbe diffused quickly. Consequently, the con-
`struction of apparatus becomes more complicated to satisfy these above mentioned conditions. The object of this
`invention is to provide an apparatus for electrolysis which improves an electrolysis efficiency by shortening the distance
`between two electrodes as narrow as possible on accomplishing a smooth dispersion of generated ions and quick
`diffusion of generated gases, and also to simplify a construction which holds electrodes and diaphragmsetc, to be
`attached to an apparatusfor electrolysis.
`Thereupon, since a previous apparatus for electrolysis of water has a problem with complicated construction ofit,
`the inventor has conductedintensive studies to reduce the problem, and has accomplishedthis invention.
`According to the present invention there is provided an electrode composition for electrolysis of water, comprising
`a panel of which one surface is made from electric conductive material and another surface is made from non-electric
`conductive material, plural holes are bored through said panel, two said panels are arranged so as to hold a diaphragm
`betweenthe surface of non-electric conductive material of each panel and electrolysis reaction occurs at the outer side
`of an anode and cathode of said electrode composition.
`The invention will now be described by way of example only with reference to the accompanying drawingsin which:
`
`is a perspective view of an example of the composite electrode constructionof this invention;
`Figure 1
`Figure 2 is a cross section taken online A - A’ in Figure 1; and
`Figure 3 is a schematicillustration of an electrolysis vessel in which the electrode is arranged.
`
`When voltage is loaded on to a cathode and anode whichare placedin water. electrons transfer between surface
`of electrodes and electrolytic dissociated water or electrolyte. In the case of NaCl is used as an electrolyte, oxygen
`gas or chlorine gas, is generated on anode side and hydrogen ion and hydronium ion are generated simultaneously
`in fluid, thus the fluid becomesacidic On cathode side, hydrogen gas and simultaneously hydroxide ion are generated,
`and so the fluid becomesalkaline. Electrons which transferred from cathodeto fluid, migrate in the fluid and come to
`anode. Thatis, an electric current flows from anode to cathode.
`As reactions which generate ions and gases are taken place closely at the surfaces of cathode and anode. con-
`centration of ions surrounding electrodes become higher. Thatis, a gradient of ionic concentration is caused. Generally,
`it is understood that generated substances closely to electrodes such as ions or others are transferred or dispersed
`by a driving force generated by a gradient of conceniration, a gradient of electric potential and by convection offluid,
`and a diaphragm stretched between cathode and anodeacts to prevent two waters in cathode side and anode side
`from mixing.
`In the case of using a conventional face to face panel shape electrode, electrolysis is actively progressed at the
`surface of cathode and anode which faced to a diaphragm located betweentwoelectrodes, and ion and gasis generated
`at each electrode. The generated gas becomestiny bubbles and diffuses from a fluid exists between electrode and
`diaphragm, and cation and anion are dispersed by effects of gradient of concentration, gradient of electric potential
`and convectionof fluid. Mixing of two fluid can be prevented by diaphragm, however, as there is a gradient of electric
`potential, ions which exist in the fluid transfer by electrophoresis through a diaphragm to another electrode. This physical
`phenomenonis put to practical use, for example in a case of production method of NaOH byelectrolysis of NaCl. In
`this case, a generation of NAOH become possible by a transportation of sodium ion from anode side to cathode side
`by the electrophoresis phenomenon. The objectof this inventionis to produce anacid ionized water and alkaline ionized
`water, and to perform this object the generated cation and anion muststay closely to each side so as to make concen-
`tration higher. So the transferring of ion to another electrode is not desirable in this invention.
`An important point of this invention is that cathode and anodeis not arranged as face to face each other but
`arranged as back to back. As a faced side of each electrode is composed by non-electric conductive materials, and a
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`EP 0 723 936 A2
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`diaphragm is arranged between electrodes, an electrolysis reaction is taken place at each outer surface of electrode
`and generates ions and gases. At this time, as electric current flows through holes bored on each electrodes and
`through the diaphragm to the outer surface of opposite electrode, a gradient of electric potential only exists in fluid
`between holes and diaphragm, and doesnot existin fluid of outer electrode surface side. Therefore, generated ions
`disperse far from each electrode by effect of gradient of concentration and by convection, and ions that exist closely
`to holes bored on electrode partially transfer to the opposite electrode by effect of gradient of electric potential. Thus,
`generated gasesare easily diffused from the fluid far from diaphragm.
`At the electrolysis process, electron transfers through fluid between cathode and anode. A distance between elec-
`trodes, a diaphragm, and in the case of back to back electrode, holes bored on electrodes mainly causes electric
`resistance. To improveefficiency of electric power for performing electrolysis, it is desirable to make a distance between
`electrodes narrower so as to decrease electric resistance. However, in the case of face to face electrode construction,
`becauseit is necessary to consider aboutthe transferring of fluid between electrodes and diffusion of gases, there is
`a limitation of the distance. In the case of back to back electrode construction of this invention, only insulator and a
`diaphragm are existing between twoelectrodes, and soit is not necessary to consider aboutthe transferring of fluid
`anddiffusion of gases between two electrodes. Therefore, in this case, a distance between twoelectrodes is equal to
`the sum total of thickness of two electrodes, two insulators and a diaphragm.
`The surface 1 of the panel is composedby electric conductive materials such as copper, lead, nickel, chrome,
`titanium, gold, platinum, iron-oxide and graphite. Preferably it is composed by platinum.
`It is desirable to use a thin
`plate of metal of 5-100 micron thickness, and more desirably a plate oftitanium having 0.1-5 milli meter thickness on
`which surface platinum is plated. Surface 2 of the panel is composed by non-electric conductive resins, such as pol-
`yethylene resin, polypropylene resin. polystyrene resin, polyethyleneterephthalate resin, polyethylenechloride resin,
`ABSresin acrylic resin, epoxy resin, teflon resin, ceramic, natural rubber, SBR, silicon rubber, chloroprene rubber,fiber
`reinforced plastic plate and thin film of non-electric conductive paints or synthetic resins. The surfaces 1 and 2 are
`tightly stuck to each other, and form a panel for cathode and anode.
`Holes 3 are bored through the panel so as to be arranged onall active area for electrolysis reaction, and surface
`areaof one holeis from 1 to 500mm?. The ratio of surface areaof holesto that of electrode is 10-90%. and is preferably
`30-70%. Material of the diaphragm 4 is generally anon-woven cloth made from asbestos, glass wool. polyvinyl chloride
`fiber, polyvinylidene chloride fiber. polyester fiber or Kevlar fiber, an unglazed ceramic plate. a sheet of paper anda
`film of ion-exchange resins. The diaphragm 4 is held between surface 2 of anode and cathode. Anode, cathode and
`diaphragm can be arranged independently, or diaphragm canbe stuck tightly to surface 2 of electrode. And alsoit is
`possible to put spacer (not indicated in the drawing) made from non-electric conductive materials to have a possibility
`of existing fluid between surface 2 and diaphragm 4.
`By using the back to back electrode of this invention, because the distance between anode and cathode can be
`shortened to the sum total of thickness of the electrodes, the insulators and the diaphragm, it is possible to improve
`the efficiency of electric power for electrolysis. And, since there are not any generations of ion and gas between elec-
`trode and diaphragm, it can be ignoredthat inconsistency of electric current caused by increased electric resistance
`due to the remainder of gasin fluid or in diaphragm.
`Generated ions on the back to back surface electrode of this invention disperse far from electrode by effect of
`gradient of concentration and by convection, and the transferring power to the opposite electrode by effect of gradient
`of electric potential is not strong. Therefore, the transferring of generated anion and cation to the opposite electrode
`is less, and consequently concentration of the object ion can beraised effectively.
`In case of a conventional electrolysis method, plates of electrode and a diaphragm mustbe held independently.
`However,
`in the case ofthis invention, as it is possible to assemble them in simplified construction by sticking a dia-
`phragm tightly or through the medium of spacer to an electrode, a holder to attach the electrode to an electrolysis
`vessel can be simplified. Therefore, the possibility for modification of electrode design is extended, and it becomes
`possible to manufacture not only a flat shape electrode but also a modified shape electrode such as having curved
`surface, spherical surface or angled shape.
`This inventionis further illustrated in the following examples, however it is to be understood that the invention is
`not intendedto be limited to ihese examples.
`Fig. 1 and Fig. 2 is an illustration of the composite electrode construction 7 which is characterized as simplified by
`sticking an electrode closely to a diaphragm and arranged in a non-electric conductive frame 6 having contact points
`§ for anode and cathode. Fig. 3 is an illustration showing the electrode construction 7 which is arrangedin electrolysis
`chamber 8, and is characterized as to prevent leaking of containedfluid frorn contact portion of the chamber and the
`electrode.
`
`Example-1
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`Water solution which includes 0.03wt%of NaCl is prepared as a testing fluid to be electrolyzed. Two sheets of
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`EP 0 723 936 A2
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`is prepared as the material of the
`titanium plate of Imm thickness on which surface thin layer of platinum is plated,
`panel and polyethylene film of 0.2mm thickness is spreaded over one surface of said platinum plated titanium plates
`and forms the panel.
`Holes of 5mm diameter are bored in each panels as shownin Figure 1 and 2. The distance betweenthe center of
`each holesis 7.7mm andthe ratio of surface area of holes to whole area is 33%. Said two panels are arranged so as
`toa polyethylene side is faced, and hold 0.17mm thickness membrene filter (Yumikron MF-60B. Yuasa Co., Lid. Japan)
`as a diaphragm between them. The said membrene filter is a polyolefin coated high porous polyester film. Thus the
`electrode composition of this invention is assembled.
`100mm Xx 100mm size of the electrode composition is placed at the center of one litre capacity electrolysis chamber
`8. Said water solution which includes 0.03wt% of NaCl is poured into both separated spacesofthe electrolysis chamber
`formed by the electrode, and mixing and leaking of the water solution can be perfectly prevented by the electrode
`composition.
`Direct current of 13volt constant voltage is loaded, and pH and oxidation-reduction potential are measured accord-
`ing to the progressof time at anode and cathode side by using pH meter and ORP meter. And also the electric current
`is measured by ammeter. And an electric power efficiency until pH of anode side water becomes2.7 is calculated. The
`electric power efficiency obtained by this experimentis 5.1watt-hour/L, and other results are shownin Table. 1.
`
`Example-2
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`Diameter of holes on the panels is changed to 7mm and the distance between centers of holes is set up to 10mm.
`In this case, the ratio of surface area of holes to whole area is 44%. Using same electrolysis equipment and same
`condition, electrolysis experimentis carried on. The obtained results are shownin Table.2.
`In this case, the electric power efficiency to obtain pH 2.7 acid ionized water is 3.4watt-hour/L, and it excels to the
`result obtained in example-1. The effect of wider hole surface area is obvious.
`
`Example-3
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`0.17mm thickness of membrene filter(Yumicron-60B) is used as a diaphragm, and same panel to example-2 is
`used to assemble the electrode composition. 360mm X 500mm size of said electrode composition is prepared and
`placed at the center of 100 litre capacity electrolysis chamber. Same water solution to example-1 is poured into the
`chamber, and direct current of constant 15ampare is loaded. The obtained results are shownin Table. 3.
`This experiment aims an actual application of the invention. Andas the good electrical power efficiency is obtained,
`it seemsthat this invention has a good possibility of an actual use.
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`ina[aa [cao
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`Table. 1
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`ORP(mV)
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`ORP(mv)
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`5.1 Watt-Hour/L
`ORP(mV)
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`Electric power efficiency (pH2.7)
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`in | a ao
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`Table.2
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`ORP(mV)
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`EP 0 723 936 A2
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`Table.2 (continued)
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`
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`te ORP(mV)|Pe| ORP(mV)
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`40
`60
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`80 Electric power efficiency (pH2.7)
`4.4 Watt-Hour/L
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`3.4 Watt-Hour/L
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`er
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`Table. 3
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`ORP(mV)
`ORP(mV)
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`Electric power efficiency (pH2.7)
`
`When water or water which includes electrolytes is ionized to the lower level than pH 2.7, it is almost perfectly
`sterilized and can be used as germ-free water. And the electric power efficiency to obtain water of lower than pH 2.7
`is better than that of a previous electrolysis method which is assumable as around 8-10 watt.hour/L. By using the
`electrode composition of this invention, germ-free water can be easily and economically obtained, which can be used
`for mass consumption in a hospital or elsewhere.
`While the preferred form of the present invention has been described, it is to be understood that modifications will
`be apparent to theseskilled in the art.
`The scopeof the invention, therefore, is to be determined solely by the following claims.
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`1. Acomposite electrode (7) for use in ihe electrolysis of water, the composite electrode comprising:
`two panels anda diaphragm (4), each panel comprising a first surface (1) made from anelectrically conductive
`material and a second surface (2) made from a non-electrically conductive material, a plurality of holes (3) being
`bored through each panel, and the diaphragm (4) being arranged between the second surface (2) of one panel
`and the second surface (2) of the other panel.
`
`2. Acomposite electrode according to claim 1, wherein the first surface (1) of at least one panel comprises platinum
`plated metal.
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`3. Acomposite electrode according to claim 1 or 2, wherein the second surface (2) of at least one panel comprises
`a polyethylene film.
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`EP 0 723 936 A2
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`A composite electrode according to claim 1, 2 or 3, wherein the area of holes (3) in at least one of said panels
`(1,2) comprises between 10% and 90% ofthe total area of said panel.
`
`A composite electrode according to claim 4, wherein the area of holes (3) in at least one of said panels (1,2)
`comprises between 30%and 90%of the total area of said panel, and preferably between 30%and 70%.
`
`A method of electrolysing water, comprising arranging the composite electrode (7) according to any preceding
`claim in an electrolysis chamber (8) to partition the chamber, and passing a direct current between anode and
`cathode of said composite electrode (7).
`
`Amethod according to claim 6, wherein the composite electrode (7) is arranged approximately in the centre of the
`electrolysis chamber (8) to divide the chamber into two halves.
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`EP 0 723 936 A2
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`Figure. l
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`EP 0 723 936 A2
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`Figure. 2
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`A-3'
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`cross section
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`EP 0 723 936 A2
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`Figure. 3
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