U.S. patent application number 12/260724 was filed with the patent office on 2009-05-21 for membrane-electrode assembly, electrolytic cell employing the same, electrolytic-water sprayer, and method of sterilization.
This patent application is currently assigned to PERMELEC ELECTRODE LTD.. Invention is credited to Tsuneto FURUTA, Noriyuki KITAORI, Yoshinori NISHIKI, Kota SEKIDO, Tomoyasu SHIBATA, Tomohisa SUZUKI, Masashi TANAKA.
Application Number | 20090127128 12/260724 |
Document ID | / |
Family ID | 40084299 |
Filed Date | 2009-05-21 |
United States Patent
Application |
20090127128 |
Kind Code |
A1 |
KITAORI; Noriyuki ; et
al. |
May 21, 2009 |
MEMBRANE-ELECTRODE ASSEMBLY, ELECTROLYTIC CELL EMPLOYING THE SAME,
ELECTROLYTIC-WATER SPRAYER, AND METHOD OF STERILIZATION
Abstract
The present invention provides a membrane-electrode assembly
which comprises: at least one rod-form or tubular electrode; a
tubular diaphragm disposed around the periphery of the electrode;
and a wire-form counter electrode disposed around the periphery of
the diaphragm, the diaphragm being fixed to the rod-form or tubular
electrode with the wire-form counter electrode to thereby form an
electrode chamber having a gas/liquid passage between the diaphragm
and the rod-form or tubular electrode.
Inventors: |
KITAORI; Noriyuki;
(Hachioji-shi, JP) ; SEKIDO; Kota;
(Sagamihara-shi, JP) ; SHIBATA; Tomoyasu;
(Fujisawa-shi, JP) ; SUZUKI; Tomohisa;
(Fujisawa-shi, JP) ; TANAKA; Masashi;
(Fujisawa-shi, JP) ; FURUTA; Tsuneto;
(Fujisawa-shi, JP) ; NISHIKI; Yoshinori;
(Fujisawa-shi, JP) |
Correspondence
Address: |
SUGHRUE-265550
2100 PENNSYLVANIA AVE. NW
WASHINGTON
DC
20037-3213
US
|
Assignee: |
PERMELEC ELECTRODE LTD.
Fujisawa-shi
JP
INSTITUTE OF NATIONAL COLLEGES OF TECHNOLOGY, JAPAN
Hachioji-shi
JP
|
Family ID: |
40084299 |
Appl. No.: |
12/260724 |
Filed: |
October 29, 2008 |
Current U.S.
Class: |
205/464 ;
204/260; 204/282 |
Current CPC
Class: |
C02F 2201/46125
20130101; A61L 2202/15 20130101; C02F 2301/026 20130101; C25B 9/19
20210101; A61L 2/0088 20130101; C02F 2001/46152 20130101; C02F
2201/4611 20130101; C02F 2001/46161 20130101; C02F 2001/46142
20130101; C02F 2201/003 20130101; A61L 2/186 20130101; C02F 1/66
20130101; C02F 2201/46115 20130101; A61L 2/18 20130101; C25B 11/02
20130101; C02F 2201/46145 20130101; C02F 2305/04 20130101; C02F
1/4618 20130101; A61L 2/183 20130101; A61L 2202/11 20130101; C25B
1/13 20130101 |
Class at
Publication: |
205/464 ;
204/282; 204/260 |
International
Class: |
C25B 1/00 20060101
C25B001/00; C25B 11/02 20060101 C25B011/02; C25B 9/10 20060101
C25B009/10 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 2007 |
JP |
2007-296769 |
Oct 15, 2008 |
JP |
2008-266158 |
Claims
1. A membrane-electrode assembly which comprises: at least one
rod-form or tubular electrode; a tubular diaphragm disposed around
the periphery of the electrode; and a wire-form counter electrode
disposed around the periphery of the diaphragm, the diaphragm being
fixed to the rod-form or tubular electrode with the wire-form
counter electrode to thereby form an electrode chamber having a
gas/liquid passage between the diaphragm and the rod-form or
tubular electrode.
2. The membrane-electrode assembly of claim 1, comprising a
plurality of rod-form or tubular electrodes.
3. The membrane-electrode assembly of claim 1, wherein the
wire-form counter electrode is spirally wound at a pitch of 1-10
mm.
4. A membrane-electrode assembly which comprises: at least one
rod-form or tubular electrode; a tubular diaphragm disposed around
the periphery of the electrode; and a porous counter electrode
disposed around the periphery of the diaphragm, the diaphragm being
fixed to the rod-form or tubular electrode with the porous counter
electrode to thereby form an electrode chamber having a gas/liquid
passage between the diaphragm and the rod-form or tubular
electrode.
5. A membrane-electrode assembly which comprises: at least one
rod-form or tubular electrode having a recessed part formed
therein; a tubular diaphragm disposed around the periphery of the
electrode so as to form an electrode chamber having a gas/liquid
passage between the diaphragm and the electrode; and a platy
counter electrode disposed around the periphery of the
diaphragm.
6. The membrane-electrode assembly of any one of claims 1 to 5,
wherein the rod-form or tubular electrode comprises diamond.
7. The membrane-electrode assembly of any one of claims 1 to 5,
wherein the rod-form or tubular electrode is an anode and the
counter electrode is a cathode.
8. An electrolytic cell which comprises: the membrane-electrode
assembly of any one of claims 1 to 5; a feeder wire-fixing tube
fitted to at least one of openings of the electrode chamber of the
assembly; and a feeder wire fixed between the opening and the
feeder wire-fixing tube.
9. An electrolytic cell which comprises: the membrane-electrode
assembly of any one of claims 1 to 5; and a tube for forming a
tubular counter electrode chamber, the tube being disposed around
the electrode chamber and the counter electrode.
10. The electrolytic cell of claim 8, which yields electrolytic
water, the electrolytic water comprising ozonized water as a main
component.
11. The electrolytic cell of claim 9, which yields electrolytic
water, the electrolytic water comprising ozonized water as a main
component.
12. An electrolytic-water sprayer which comprises: the electrolytic
cell of any one of claims 8 to 11; a vessel containing raw water;
and a head, wherein the raw water is electrolyzed with the
electrolytic cell and the electrolytic water thus yielded is
ejected from the head.
13. A method of sterilization with electrolytic water which
comprises: yielding electrolytic water with the electrolytic-water
sprayer of claim 11; and ejecting the resultant electrolytic water
to a substance to be sterilized.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a membrane-electrode
assembly for yielding electrolytic water to be used for
sterilization, cleaning, etc., an electrolytic cell employing the
assembly, an electrolytic-water sprayer including any of the
electrolytic cell, and a method of sterilization using these.
BACKGROUND OF THE INVENTION
Bactericide/Disinfectant Solution:
[0002] Chlorine compound bactericides such as sodium hypochlorite,
calcium hypochlorite, and sodium dichloroisocyanurate have been
extensively used as bactericides/disinfectants in a wide range of
environments. Of these, hypochlorites including sodium hypochlorite
are in general use from the standpoints of cost and effect.
However, many proposals have been made for attaining improvements
in the bactericidal/disinfectant effect thereof which are required
in various fields including the clinical field and the food
industry (see, for example, JP-A-2001-253803, JP-A-2001-342496, and
JP-A-2002-145710).
[0003] Usually, such bactericides/disinfectants are prepared by
adding the respective ingredients for constituting the composition
to water or by mixing aqueous solutions containing the respective
ingredients.
Use of Electrolytic Water as Substitute:
[0004] However, the use of chlorine compound bactericides in large
amounts arouses troubles. For example, in factories and retail
stores where food materials are handled in large quantities,
cleaning with a sodium hypochlorite solution having a concentration
exceeding 100 ppm is conducted. This cleaning, however, is regarded
as problematic because it not only spoils the flavors of the food
materials but also arouses a hazard (increase in THM).
[0005] Mainly for the purpose of eliminating those problems,
investigations have been diligently made on the usefulness of
electrolytic water, i.e., water yielded by electrolysis, in the
agricultural, food, clinical, and other fields. The substitution of
electrolytic water or ozonized water is proceeding mainly in Japan.
Electrical energy, which is a clean energy, can be utilized to
synthesize hydrogen, oxygen, ozone, hydrogen peroxide, etc. through
chemical reactions on electrode surfaces while regulating the
reactions. It is known that oxidation reactions especially on the
anode yield oxidizing agents effective in water treatments
(effective chlorine and peroxides such as ozone) and further
generate active species such as OH radicals in some cases (Ky
sansei Denkaisui No Kiso Chishiki (Fundamental Knowledge of
Strongly Acidic Electrolytic Water), Ohm-sha, Ltd.).
[0006] Attention is being directed to the excellent
bactericidal/disinfectant activity of electrolytic water, and
investigations are being made on the use of the water in clinical
activities and in the home. Examples of the uses thereof which are
being investigated include the sterilization/disinfection of
diseased parts, incised parts, percutaneous openings for stationary
catheters, etc. and the sterilization/disinfection of domestic
utensils or articles, such as kitchen utensils, baby articles, and
furniture, and house equipments such as the toilet facilities and
bathtub. Such electrolytic water is obtained by electrolyzing water
(water to be electrolyzed) to which a solute that generates ions
upon dissolution, e.g., sodium chloride, has been added optionally
together with an acid for pH regulation.
Kinds of Electrolytic Water:
[0007] Besides being used as a food additive, electrolytic water is
usable also in other applications. In an electrolytic cell
containing water only, the following anode reaction proceeds to
evolve oxygen according to formula (1). However, depending on the
catalyst and electrolysis conditions, ozone is yielded according to
formula (2) and ozonized water containing the ozone dissolved
therein can be synthesized.
2H.sub.2O=O.sub.2+4H.sup.++4e (1)
3H.sub.2O=O.sub.3+6H.sup.++6e (2)
[0008] In the case where the water contains hydrochloric acid or
chloride ions added thereto, hypochlorous acid is yielded according
to formulae (3) and (4). In the case where the water contains
sulfuric acid, the reaction represented by formula (5) proceeds to
yield persulfuric acid.
Cl.sup.-=Cl.sub.2+2e (3)
Cl.sub.2+H.sub.2O=HCl+HClO (4)
2SO.sub.4.sup.2-=S.sub.2O.sub.6.sup.2-+2e (5)
[0009] When carbonate ions are present, the reaction represented by
formula (6) proceeds to yield percarbonic acid.
2CO.sub.3.sup.2-=C.sub.2O.sub.6.sup.2-+2e (6)
[0010] Through cathode reactions, it is possible to synthesize
hydrogenous water, which is water containing excess hydrogen
dissolved therein, alkali ion waters and the like according to
formulae (7) and (8).
2H.sup.++2e=H.sub.2 (7)
2H.sub.2O+2e=H.sub.2+2OH.sup.- (8)
[0011] Furthermore, hydrogen peroxide or the like can also be
synthesized.
[0012] As shown above, electrolytic water containing two or more
peroxides can be produced with electrolytes suitably selected,
besides the acid waters which have been approved as food
additives.
[0013] Features of Electrolytic Water: (reference: Mizu No Tokusei
To Atarashii Riy Gijutsu (Characteristics of Water And Novel
Application Technology), 2004, NTS Inc.)
[0014] There are the following three kinds of electrolytic water
which have been approved as food additives.
[0015] a) Weakly alkaline electrolytic hypochlorite water (additive
name, electrolytic sodium hypochlorite water; 20-200 ppm;
pH>7.5; yielded from 0.2-2% aqueous sodium chloride solution
using no diaphragm)
[0016] b) Slightly acid electrolytic water (additive name, slightly
acid hypochlorous acid water; 10-30 ppm; pH=5-6.5; yielded from
2-6% hydrochloric acid using no diaphragm)
[0017] c) Strongly acid electrolytic water (additive name, strongly
acid hypochlorous acid water; 20-60 ppm; pH<2.7; yielded as
anolyte water from 0.2% or lower aqueous sodium chloride solution
in diaphragm type cell)
[0018] The acid waters among those kinds of electrolytic water
have, for example, the following merits.
[0019] (1) The acid waters are superior in safety because THMs are
less apt to generate under acid conditions.
[0020] (2) Resistant bacteria are less apt to generate and on-site
management is easy.
[0021] (3) The waters can be used for treatment in combination with
the alkaline electrolytic water.
[0022] (4) The waters can be utilized like tap water and impart no
remaining odor to the hands or fingers.
[0023] (5) Use of the waters just before suffices (sterilization
time is short).
[0024] In the conventional treatment with sodium hypochlorite
solutions, use of this chemical having a concentration up to 200
ppm as a food additive has been approved. However, the chemical
spoils the flavor and has a residual tendency. In contrast, the
electrolytic water of those kinds has a high bactericidal effect
even in a low concentration and is beneficial, although use thereof
necessitates an initial investment in the apparatus.
Features of Ozonized Water:
[0025] The long-term use of hypochlorites has yielded bacteria
resistant to these chemicals, and there is a doubt about the
bactericidal effect thereof. On the other hand, ozonized water has
been placed on food additive lists and has gained approval of FDA
(Food and Drug Administrations) of U.S.A. (2001) for use as a
bactericide in food storage/production steps. Ozonized water has
already come into many practical uses for sterilization in food
factories and the sterilization of foods themselves. Recently,
attention is focused on the fact that ozonized water is equal or
superior in effect to sterilizing waters heretofore in use also in
clinical fields such as dermatology, opthalmology, and dentistry
and is effective in reducing the burden to be imposed on the living
body.
[0026] Ozonized water has, for example, the following merits.
[0027] (1) The bactericidal effect of ozone (OH radicals) is based
on the oxidative destruction of cell walls and this indiscriminate
activity is thought not to generate resistant bacteria.
[0028] (2) Ozone does not have a residual tendency.
[0029] When ozonized water is used in combination with an oxidizing
agent having a residual tendency (e.g., a hypochlorite, persulfate,
or percarbonate) according to need, a more effective sterilization
treatment is possible.
Conventional Process for Producing Ozonized Water:
[0030] ozonized water has conventionally been produced generally
with a discharge type ozone gas generator. Ozonized water having a
concentration of several parts per million parts can be easily
produced by the process, and is being utilized in the fields of
water purification treatment and food cleaning. However, the
apparatus has been unsuitable for use as a handy ozonized-water
production apparatus having excellent instant-response
characteristics and yielding high-concentration ozonized water, for
the following reasons.
[0031] (1) The ozonized-water production necessitates two steps,
i.e., first generating ozone as a gas and then dissolving the gas
in water.
[0032] (2) The ozonized water has a lower concentration than that
produced by the electrolytic process which will be described later
and, hence, the water should be produced through high-pressure
injection into water and dissolution therein.
[0033] (3) The power source fox ozone generation has a high voltage
and a high frequency, making it difficult to attain a size
reduction.
[0034] (4) In the ozonized-water production apparatus based on a
discharged, a certain time period (stand-by time of several
minutes) is required for the ozone gas generation ability to become
stable and it is difficult to instantaneously prepare ozonized
water having a certain concentration.
Electrolytic Ozone Production Process:
[0035] The electrolytic process is inferior to the discharge
process in electric power consumption rate. However, a feature of
the electrolytic process resides in that high-concentration ozone
gas and ozonized water can be easily obtained. The electrolytic
process is hence in general use in special fields such as, e.g.,
the cleaning of electronic parts. Since a direct-current
low-voltage power source is employed because of the principle of
the process, the apparatus is excellent in instant-response
characteristics and safety and is expected to be used as a small
ozone gas generator or a small ozonized-water production apparatus.
According to applications, a driving mode can be selected from
battery driving, power-generator driving, and AC-DC conversion
driving.
[0036] For efficiently generating ozone gas, it is indispensable to
select a proper catalyst and electrolyte. Known electrode materials
include noble metals such as platinum, .alpha.-lead dioxide,
.beta.-lead dioxide, glassy carbon impregnated with a fluorocarbon,
and diamond. As an electrolyte, use has been made of an aqueous
solution containing sulfuric acid, phosphoric acid, fluorinated
groups, or the like. However, these electrolytes have poor
handleability and are not in extensive use. A water electrolysis
cell which employs a solid polymer electrolyte as a diaphragm and
in which pure water is used as a raw material is easy to manage in
that respect and is in general use (J. Electrochem. Soc., 132, 367
(1985)). When lead dioxide, which has been employed as a catalyst,
is used, ozone gas having a concentration as high as 12% or above
is obtained.
[0037] In the system called a direct synthesis system, the solution
located around an electrode is caused to flow at a sufficient
velocity to thereby take out the ozone as ozonized water before
gasifying (JP-A-8-134677). Furthermore, in the case where raw water
other than pure water is supplied to the electrolytic system, the
activity of the noble-metal electrode catalyst itself is influenced
by the quality of the water. Care should hence be given to the fact
that electrolytic performances such as life and efficiency
fluctuate. JP-A-9-268395 discloses that conductive diamond is
useful as an electrode for producing functional water (containing
ozone).
Development of Small Apparatus:
[0038] Portable or small electrolytic-water production/ejection
apparatus have been proposed in order to more easily conduct
sterilization/disinfection or the like in clinical activities or in
the home (see patent documents 1 to 3). Such small apparatus may be
extensively used for the deodorization, sterilization, or bleaching
of indoor facilities, water-related facilities, tableware,
garments, etc. in the home or for business purposes or for the
sterilization or disinfection of the human body, e.g., the hands or
fingers, etc.
[0039] Patent Document 1: JP-A-2000-79393
[0040] Patent Document 2: JP-A-2000-197889
[0041] Patent Document 3: JP-A-2001-276826
[0042] Besides those, the following are known: JP-A-2004-129954
(apparatus having a device which generates power necessary for
electrolysis); JP-A-2004-130263 (apparatus in which the proportion
of the capacity of the piston to the volume, sectional area, etc.
of the cell cylinder part is a specific value); JP-A-2004-130264
(apparatus in which raw water for electrolysis comprising a pH
regulator, surfactant, chlorine compound, and water is used to
obtain electrolytic water having a pH of 3-8.5); JP-A-2004-130265
(the electrolytic water according to JP-A-2004-130264 is used in a
foamed state); JP-A-2004-130266 (the direction of voltage
application to the electrodes is changed alternately);
JP-A-2004-148108 (the voltage to be applied to the electrodes is
variable); JP-A-2004-148109 (apparatus having electrodes in a
suction passage); JP-A-2003-93479, JP-A-2003-266073, and
JP-A-2002-346564 (separation type having a cylindrical electrode in
a spraying part); and JP-A-2001-47048 (gun type prevented from
being clogged during non-spraying period and equipped with a
motor).
[0043] Known techniques intended to synthesize ozonized water
include the following. JP-A-2000-169989 discloses a small
electrolytic ozone generator which has a structure including an
assembly composed of a solid cylindrical shaft and, wound on the
shaft, a metal-gauze-like anode (platinum), an ion-exchange
membrane, and a metal-gauze-like cathode and disposed in a water
channel and in which the shaft has a thin groove formed therein.
JP-A-2001-198574 discloses a module for connection to piping which
includes a solid cylindrical shaft and, fixed to the shaft, a
porous anode, a solid polymer electrolyte (ion-exchange membrane),
and a porous cathode and has a drain line capable of separately
discharging the ozonized water to be synthesized at the anode and
the hydrogen/hydrogen gas to be synthesized at the cathode.
JP-A-2002-143851 discloses a method of water treatment with a
double-pipe structure including a supporting cylindrical member
having a through-hole and, wound on the cylindrical member, a
cathode, a membrane, and an anode. In this method, hard-water
components can be inhibited from depositing from tap water as raw
water by passing a dilute aqueous solution of sodium chloride
through the cylinder serving as a cathode chamber, and an
ultraviolet treatment can also be conducted simultaneously.
JP-A-2004-60010 and JP-A-2004-60011 disclose an ozonized-water
production apparatus which is capable of separating a catholyte
with an electrolytic cell equal to that described in
JP-A-2000-169989 and of measuring the concentration of ozone with
an electromotive-force measuring device disposed in the channel.
JP-A-2006-346203 discloses use of conductive diamond as an
electrode and, in particular, discloses an electrolytic cell
including a rod-form conductive-diamond electrode, a strip-form
diaphragm member disposed around the electrode, and a wire-form
counter electrode disposed on the diaphragm member. Furthermore,
JP-A-2007-136356 discloses a structure including a cylindrical core
member having grooves extending in the cylinder direction and,
wound on the core member in the following order, a cathode, a
membrane, and an anode.
SUMMARY OF THE INVENTION
[0044] Conventional small electrode assemblies and electrolytic
cells employing the assemblies have had the following problems.
[0045] (1) Although use of an ion-exchange membrane or the like
improves ionic conductivity and this is expected to increase
electrolysis reaction efficiency, it has been difficult to join the
membrane or the like with the electrodes.
[0046] (2) The membrane usually is nonporous and is used usually in
combination with porous electrodes for facilitating the feeling of
an electrolytic solution and removal of products. The shape of the
electrode assembly is hence complicated.
[0047] (3) When the assembly is to be attached to an apparatus, the
piping membranes are frequently cylindrical and, hence, the
electrodes preferably have a shape suitable for the piping members,
i.e., a rod-form or cylindrical shape. It has been necessary to
employ an apparatus suitable for that shape.
[0048] (4) Although a platinum catalyst is excellent in the
property of accelerating ozone generation, it is unstable and apt
to be influenced by the raw water. There are cases where ozonized
water having a concentration of several parts per million, which
enables short-time sterilization, cannot be synthesized when tap
water is used as it is.
[0049] (5) In yielding ozonized water, the hydrogen which has
generated at the counter electrode is separated to increase partial
pressure and this inevitably results in an increase in solute
concentration. However, there has been no cell having a structure
suitable for that.
[0050] If those problems are overcome, it is expected that the use
of electrolytic water in the home, hospitals, nursing care
facilities, etc. expands further.
[0051] An object of the invention is to provide a
membrane-electrode assembly with which many of those problems can
be eliminated and which can be easily produced and bring about high
performance. Another object of the invention is to provide an
electrolytic cell and an electrolytic-water sprayer, each employing
the assembly, and a method of sterilization. The electrolytic-water
sprayer of the invention electrolyzes a raw aqueous solution, and
the electrolytic water thus yielded can be immediately
utilized.
[0052] The invention first provides a membrane-electrode assembly
which comprises:
[0053] at least one rod-form or tubular electrode;
[0054] a tubular diaphragm, preferably ion-exchange membrane,
disposed around the periphery of the electrode; and
[0055] a wire-form counter electrode disposed around the periphery
of the diaphragm,
[0056] the diaphragm being fixed to the rod-form or tubular
electrode with the wire-form counter electrode to thereby form an
electrode chamber having a gas/liquid passage between the diaphragm
and the rod-form or tubular electrode.
[0057] The invention secondly provides a membrane-electrode
assembly which comprises
[0058] at least one rod-form or tubular electrode;
[0059] a tubular diaphragm disposed around the periphery of the
electrode; and
[0060] a porous counter electrode disposed around the periphery of
the diaphragm,
[0061] the diaphragm being fixed to the rod-form or tubular
electrode with the porous counter electrode to thereby form an
electrode chamber having a gas/liquid passage between the diaphragm
and the rod-form or tubular electrode.
[0062] The invention thirdly provides a membrane-electrode assembly
which comprises:
[0063] at least one rod-form or tubular electrode having a recessed
part formed therein;
[0064] a tubular diaphragm disposed around the periphery of the
electrode so as to form an electrode chamber having a gas/liquid
passage between the diaphragm and the electrode; and
[0065] a platy counter electrode disposed around the periphery of
the diaphragm.
[0066] According to the invention, an electrolytic cell and an
electrolytic-water sprayer each having the membrane-electrode
assembly can be constituted. The electrolytic-water sprayer can be
used to yield electrolytic water and eject the electrolytic water
to a substance to sterilize it.
[0067] The invention will be explained below in detail.
[0068] The membrane-electrode assembly of the invention is
characterized by being produced by disposing a tubular diaphragm,
e.g., an ion-exchange membrane, around the periphery of a rod-form
or tubular electrode, usually an anode (hereinafter referred to
also as rod anode), disposing a wire-form or porous counter
electrode, usually a wire-form or porous cathode, around the
periphery of the membrane, fixing those members with the cathode so
that the membrane is in contact with at least part of the anode and
that the membrane is in contact with at least part of the cathode,
and forming an anode chamber having a gas/liquid passage between
the membrane and the anode and preferably among a plurality of
anodes.
[0069] In the invention, an anode chamber separated from a cathode
chamber by a diaphragm is formed to constitute an appropriate
gas/liquid passage. By changing a water feed rate and current
value, the concentration of an electrolytically yielded species in
the electrolytic water can be regulated to a desired value.
[0070] In the following explanations, the rod electrode and the
counter electrode are used as an anode and a cathode, respectively.
In the invention, however, the rod electrode and the counter
electrode may be conversely used as a cathode and an anode,
respectively.
[0071] This membrane-electrode assembly can have a constitution
including a rod anode, a sheet-form membrane disposed, in a
tube-forming manner, around the periphery of the anode, and a wire
cathode spirally wound thereon at an appropriate pitch. In this
constitution, not only the rod anode, membrane, and wire cathode
can be kept in partial contact with each other but also an anode
chamber through which the liquid and the gas generated can move
spirally can be formed between the rod anode and the membrane or
among a plurality of rod anodes.
[0072] A membrane-electrode assembly having an ideal passage is
obtained by suitably selecting the diameter and number of the rod
anode, diameter of the tubular membrane, and material, thickness,
and winding pitch of the wire cathode. In particular, by spirally
winding the wire cathode at a pitch of 1-10 mm, an assembly having
a suitable structure is obtained. It is especially preferred that
the anode should be diamond, because this assembly can efficiently
generate ozone, etc.
[0073] This membrane-electrode assembly can be used to constitute
an electrolytic cell which includes a tube fixed to at least one of
the openings of the anode chamber and one or two feeder terminals
connected to the anode and/or the cathode.
[0074] Furthermore, by fixing a tube to the two openings of the
anode chamber formed between the anode and the diaphragm and fixing
the resultant member in a second tube having at least two openings,
a cathode chamber can be formed between the cathode and the
diaphragm. One or two feeder terminals are connected to the anode
and/or cathode. Thus, an electrolytic cell can be constituted in
which electrolysis is conducted while feeding raw water to one of
the openings of the anode chamber and feeding raw water also to one
of the openings of the cathode chamber according to need. Since the
diaphragm has been deformed so as to spirally form the anode
chamber between the diaphragm and the anode, the cathode chamber
also has been spirally formed. Because of this, the gas and liquid
present near the cathode in the cathode chamber can be caused to
flow spirally. In this cell, acid water and alkaline water can be
simultaneously synthesized in the anode chamber and the cathode
chamber, respectively.
[0075] When the raw water is passed through the electrolytic cell
and a voltage is applied to the cell, then the raw water comes into
contact with the rod electrode and counter electrode in the
electrolytic cell and is electrolyzed to yield electrolytic
water.
[0076] This electrolytic cell is mounted in an electrolytic-water
ejection apparatus including a vessel containing raw water and a
head. When the raw water is sucked up and passed through the tube
and a voltage is applied to the electrolytic cell, then the raw
water comes into contact with the rod anode and the cathode in the
electrolytic cell and is electrolyzed to yield electrolytic water.
This electrolytic water is discharged outside in an atomized or
liquid state through the nozzle of the head optionally with a power
assist such as, e.g., a pump.
[0077] Alternatively, the electrolytic cell may be directly
connected to a water supply line. When raw water is fed from the
water supply line to the anode chamber or cathode chamber and
electrolyzed while being fed, then the same active electrolytic
water is yielded.
[0078] In those electrolytic cells, an active species such as ozone
is efficiently synthesized in a high concentration to yield
electrolytic water having a sterilizing/bleaching ability. The
concentration of ozone or another species in the electrolytic water
depends on the amount of raw water flowing through each chamber per
unit time period. The area of the section through which raw water
flows can be regulated by regulating the diameter and number of the
rod anode, diameter of the tubular membrane, and winding pitch of
the wire cathode. Thus, electrolytic water can be efficiently
produced.
[0079] The method of the invention and the electrolytic-water
sprayer of the invention can be extensively used for the
deodorization, sterilization, or bleaching of indoor facilities,
water-related facilities, tableware, garments, etc. in the home or
for business purposes or for the sterilization or disinfection of
the human body, e.g., the hands or fingers, etc. As apparent from
the explanations given above, the term "sterilization" in the
method of sterilization of the invention means any of acts such as
deodorization, bleaching, and disinfection, besides
sterilization.
[0080] In the invention, highly active electrolytic water such as
the following can be yielded by regulating conditions.
[0081] (1) Alkaline electrolytic water (alkaline water containing
hydrogen gas dissolved therein)
[0082] (2) Acid electrolytic water (electrolytic water containing
two or more peroxides yielded by electrolyte selection; sulfuric
acid salts, carbonic acid salts, and the like are usable besides
chlorides)
[0083] (3) High-concentration ozonized water (this water has no
residual tendency, has bactericidal activity at least 10 times the
bactericidal activity of hypochlorite systems, and further has a
bleaching effect; the ozone half-life is prolonged by some
coexistent substances to attain improved persistency)
[0084] (4) Novel composite electrolytic water (having a novel
sterilizing effect brought about by adding an organic acid or
surfactant for pH regulation for the purpose of improving
bactericidal activity or by adding an alcohol or the like for the
purpose of, e.g., improving bactericidal activity or refreshing
feeling)
[0085] In the membrane-electrode assembly produced by disposing, in
a tube-forming manner, a sheet-form ion-exchange membrane or the
like around the periphery of at least one rod electrode and
disposing a wire-form counter electrode or a porous counter
electrode therearound, the rod electrode, membrane, and counter
electrode have been united together. Because of this, the assembly
once produced can be easily handled. This assembly can be easily
produced.
[0086] Gas/liquid passages suitable for use as an electrode chamber
(or as an electrode chamber and a counter electrode chamber) are
formed by regulating the diameter of the rod electrode, sectional
shape of the electrode, diameter of the tubular membrane and
winding pitch in the case of a wire-form counter electrode, or by
selecting the diameter of the tube in which those members are
disposed to form a counter electrode chamber, and further
appropriately deciding the number of the rod electrode to be used.
By changing the water feed rate and current value, the
concentration of an electrolytically yielded species in the
electrolytic water can be regulated to a desired value.
[0087] The electrolytic water obtained is ejected to or sprayed
over a substance to be sterilized, whereby the substance can be
sterilized with the electrolytically yielded species contained in
the desired concentration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0088] FIG. 1 is a front view illustrating an electrolytic-water
sprayer as one embodiment of the invention.
[0089] FIG. 2 is an exploded enlarged view of an important part of
the sprayer shown in FIG. 1.
[0090] FIG. 3 is a slant view of the electrolytic cell shown in
FIGS. 1 and 2.
[0091] FIG. 4 is a partial sectional view illustrating another
embodiment of the electrolytic cell of the invention.
[0092] FIG. 5 is a plan view of another rod anode.
[0093] FIG. 6 is a plan view of a tubular anode.
[0094] FIG. 7 is a partial slant view illustrating a still other
embodiment of the electrolytic cell of the invention.
[0095] FIG. 8 is a transverse sectional view of the electrolytic
cell of FIG. 7.
[0096] The reference numerals used in the drawings denote the
following, respectively. [0097] 1: Electrolytic-water sprayer
[0098] 2: Raw water [0099] 3: Vessel [0100] 4: Head [0101] 6, 6a:
Electrolytic cell [0102] 7, 7a: Anode [0103] 8, 8a: Diaphragm
[0104] 9, 9a: Wire cathode [0105] 10, 10a: Anode chamber [0106] 15:
Vertical pipeline [0107] 17: Spray nozzle [0108] 18: Trigger arm
[0109] 22: Trigger-engaged switch [0110] 32: Electrolytic cell
[0111] 33: Groove [0112] 34: Anode [0113] 35: Diaphragm [0114] 36:
Porous cathode [0115] 37: Anode chamber [0116] 41: Diaphragm [0117]
43: Rod anode [0118] 44: Protrudent part [0119] 45: Anode chamber
[0120] 46: Diaphragm [0121] 48: Tubular anode [0122] 49: Recessed
part [0123] 50: Anode chamber
DETAILED DESCRIPTION OF THE INVENTION
[0124] The constituent elements of the invention will be explained
below. However, the invention should not be construed as being
limited to the following.
Anode and Anode Material:
[0125] Examples of anode catalysts for oxidation include lead
oxide, tin oxide, noble metals such as platinum, DSAs (electrodes
consisting mainly of a noble-metal oxide), carbon, and conductive
diamond. From the standpoint of corrosion resistance, it is
desirable to use as the electrode catalyst a noble metal such as
platinum or iridium, an oxide of such a noble metal, or conductive
diamond. The material to be used as an electrode base preferably
has corrosion resistance from the standpoints of attaining a long
life and preventing the surface to be treated from being fouled. It
is desirable to use as the anode base a valve metal such as
titanium or niobium or an alloy thereof. The anode material can be
deposited on the surface of such a base having a shape heretofore
in general use, such as a pipe or rod. Although the sectional shape
thereof is desirably selected from circle, quadrangles, ellipses,
and the like or from hollow cylinders, hollow prisms, and the like,
it is not limited to these. To process the surface of a rod-form or
cylindrical anode to impart recesses and protrusions thereto or, in
the case of a hollow material, to form openings in the electrode
surface is effective in enhancing gas/liquid permeability. A base
obtained by rolling a metal gauze into a tubular form is also
usable. The height of the recesses and protrusions is preferably
0.1-5 mm. Also usable is a base having a spiral groove extending in
the cylinder direction.
[0126] By using a plural number of the anodes, instead of forming
the recesses and protrusions on the surface of the anode, it is
possible to easily and assuredly form liquid passages and enhance
the gas/liquid permeability. Specifically, when rod-form or
cylindrical anodes are lined up in rows, adjacent anodes are
brought into close contact at one point and further the contact
area of the anodes and the diaphragm decreases, thereby forming a
large space among the anodes and between the anodes and the
diaphragm. Therefore, liquid passages (anode chamber) can be formed
without requiring troublesome operations such as surface processing
of the anode.
[0127] The plural rod-form electrodes may be partly replaced with a
member consisting of a base having no catalyst formed thereon. In
this case, the member plays roles of forming a liquid passage and
conducting a current to the other rod-form electrode(s).
[0128] The presence of a catalyst as part of the anode suffices,
and the base may be partly exposed.
[0129] Diamond is regarded as a promising electrode material partly
because the electrical conductivity thereof can be regulated by
doping. Diamond electrodes are inert in water decomposition
reaction. It has been reported that a diamond electrode in
oxidation reactions yields ozone and hydrogen peroxide besides
oxygen. When conductive diamond is used, electrolysis reactions
proceed more readily and those peroxides as products of
electrolysis are produced exceedingly efficiently. Furthermore, on
the diamond electrode, OH radicals and oxidized forms of
electrolytes are yielded besides the electrolytically yielded
species shown above. Consequently, the sterilizing/bleaching
effects of the OH radicals or oxidized forms and of the
electrolytically yielded species can be synergistically
utilized.
[0130] In the case where conductive diamond is used, examples of
usable bases include Nb, Ta, Zr, Ti, Mo, W, graphite, and various
carbides as well as Si (monocrystalline and polycrystalline). A
suitable one can be selected according to applications.
Cathode Material, Cathode Feeder Wire:
[0131] Cathode reactions include hydrogen evolution as the main
reaction. It is therefore preferred to use an electrode catalyst
which is not embrittled by hydrogen. Examples of such preferred
electrode catalysts include platinum group metals, nickel,
stainless steel, titanium, zirconium, gold, silver, carbon, and
diamond. As the cathode base, it is desirable to use stainless
steel, zirconium, carbon, nickel, titanium, or the like.
[0132] The shape thereof preferably is a wire form. Besides being
in a wire form, the cathode may be a metal gauze or foil which has
been cut thinly. In the case of a wire form, the cathode may be a
winding obtained by twisting plural thin filaments. This form is
also preferred. In the case of using a wire cathode, there are
cases where this wire cathode functions as a feeder. In the
invention, this feeder is included in the wire cathode.
[0133] A porous metal gauze cathode may be rolled into a tubular
form and deposited around the periphery of the ion-exchange
membrane or the like. Examples of the porous cathode include
expanded meshes and punching metals, besides metal gauzes. In the
case of using these materials, it is desirable to form recesses and
protrusions on the surface of the anode to thereby form an anode
chamber between the ion-exchange membrane and the anode. However,
an anode chamber may be formed by modifying such a porous cathode
only and partly protruding the diaphragm toward the anode.
[0134] A diaphragm, e.g., an ion-exchange membrane, in which a
catalyst layer has been formed beforehand on one side thereof may
be disposed so that the side having the catalyst faces outward.
This constitution is preferred because the electrolytic cell can
have an even current distribution and a reduction in cell voltage
can hence be attained. For forming the catalyst layer, existing
techniques can be used, such as electroless plating and PVD. In
this case, a metal wire serving also as a feeder is wound thereon.
Preferred examples of feeder wire materials include platinum group
metals, nickel, iron, copper, silver, gold, stainless steel,
titanium, and zirconium.
Diaphragm Material:
[0135] As the diaphragm can be used an ion-exchange membrane or a
neutral membrane. Usually, an ion-exchange membrane is used.
[0136] A diaphragm not only prevents substances yielded at the
anode or cathode from being consumed at the opposed electrode, but
also has the function of enabling electrolysis to proceed speedily
even when a liquid having a low conductivity is used. Use of a
diaphragm is therefore preferred when a raw material having poor
conductivity, such as pure water, is used. In the case of using an
ion-exchange membrane, it may be either a fluororesin membrane or a
hydrocarbon resin membrane. However, the former membrane is
preferred from the standpoint of resistance to corrosion by ozone
and peroxides. The thickness of the membrane is preferably 0.1-1
mm.
[0137] In the case where a wire cathode is wound on the membrane to
form a spiral passage, it is preferred to use as the membrane a
commercial membrane containing reinforcing fibers and having high
mechanical strength.
[0138] It is preferred to form the diaphragm into a tubular shape
beforehand. This can be easily accomplished with a precursor resin
having thermoplasticity by a known tube-forming processing
technique. With respect to the diaphragm, one containing
reinforcing fibers is preferred. Use may be made of a method in
which a membrane in a sheet form is rolled into a tube and then
bonded. In the case of a fluororesin ion-exchange membrane, use can
be made of a method in which edge parts of the membrane are
superposed and then thermally fusion-bonded together or fixed to
each other with an adhesive. In the thermal fusion bonding,
appropriate ranges of the processing temperature and the areal
pressure are 200-350.degree. C. and 2-20 kg/cm.sup.2, respectively.
An appropriate range of the processing time period is from 1 second
to 1 minute. For increasing bonding strength and attaining more
complete bonding, it is preferred that a narrow strip of a
fluororesin membrane containing no reinforcing fibers be interposed
in bonding the ion-exchange membrane.
[0139] To form recesses and protrusions on the membrane surface is
preferred because this can enhance gas/liquid permeability.
Membrane-Electrode Assembly:
[0140] The length and diameter of the rod anode in the
membrane-electrode assembly are selected according to desired
amounts. Usually, the length thereof is preferably 10-300 mm, and
the diameter thereof is preferably 0.5-10 mm. The diameter of the
diaphragm in the assembly is regulated so as to be larger by about
0.1-5 mm than the diameter of the rod anode (typically supposed to
be a cylinder) disposed in the diaphragm.
[0141] The percentage of openings of the porous cathode is
preferably 20-80%, and the thickness thereof is preferably 0.1-2
mm.
[0142] In the case of using a wire cathode (feeder wire), the
diameter thereof is preferably in the range of 0.1-2 mm.
[0143] In case where the wire cathode is thinner than that, a
voltage loss becomes not negligible due to electrical resistance.
Furthermore, such a thin cathode is apt to break in a winding
operation because the physical strength thereof is insufficient. In
case where the wire cathode is too thick, the movement of the raw
material for electrolysis and products of electrolysis from the
anode chamber is inhibited, leading to an increase in voltage and a
decrease in current efficiency. In addition, such a thick cathode
is difficult to wind.
[0144] In the case where a wire cathode or a feeder wire is
spirally wound on the outer side of the anode and membrane, the
wire cathode pitch is preferably about 0.1-10 mm.
[0145] When the wire cathode is spirally wound, the angle of
winding is governed by the diameter and number of the rod
electrode, width of the diaphragm, and diaphragm gap.
[0146] The dimensions described above are selected/designed from
the standpoints that even when raw water having low conductivity is
used, the electrode is in spiral contact with at least part of the
membrane to enable electrolysis to proceed smoothly and that the
anode chamber formed by the anode and the membrane needs to have a
capacity which enables the raw water fed and the gas ingredient
evolved to flow smoothly through the anode chamber.
Electrolytic Cell:
[0147] At least one of the openings of the anode chamber formed by
the anode and the diaphragm in the membrane-electrode assembly has
been fixed to a tube connected to a raw-water channel. This tube
has almost the same diameter as the tubular diaphragm. The
diaphragm and the tube are fixed to each other with an adhesive,
and a feeder terminal for the rod anode is connected to the anode
in the tube.
[0148] Furthermore, a member obtained by fixing tubes respectively
to the two anode chamber openings of the assembly may be disposed
in a second tube which has at least two openings and is separated
from the member. Thus, a cathode chamber can be newly formed
between the second tube and the membrane. A feeder terminal for the
wire cathode is connected to the cathode in the second tube.
[0149] Raw water is fed to one of the openings of the anode chamber
and raw water is fed also to one of the openings of the cathode
chamber according to need to conduct electrolysis. By conducting
electrolysis while feeding raw water to the anode-chamber opening
and optionally feeding water also to the cathode-chamber opening,
electrolytic water is yielded. Thus, alkaline water and acid water
can be simultaneously yielded according to need.
[0150] The inner diameter of the second tube forming the cathode
chamber is regulated so as to be larger by about 0.1-5 mm than the
diameter of the membrane of the assembly. In case where the second
tube is thinner than that, substance movement in the catholyte is
inhibited and, in particular, there is a possibility that the
deposition of hard-water components from, e.g., tap water might be
accelerated. On the other hand, in case where the second tube is
too thick, the catholyte has a reduced flow rate and the separation
and removal of hard-water components by means of a liquid flow rate
becomes impossible. This leads to an increase in voltage and a
decrease in current efficiency. In addition, the amount of water
stored in the cell increases, making it impossible to
instantaneously obtain alkaline water.
[0151] The material of the second tube preferably is a hydrocarbon
resin such as PP, PVC, or PE, a fluororesin, a metal tube, or the
like. A tube having heat shrinkability is preferred because the
capacity of the electrolytic-cell part can be regulated. The wall
thickness of the second tube is preferably smaller from the
standpoint of rapidly removing the heat generated in the
electrolytic cell. However, the wall thickness thereof is
preferably 0.05-2 mm because mechanical strength also is
necessary.
[0152] The water which is discharged first from the electrolytic
cell includes the raw water which has not been sufficiently
electrolyzed. In view of this, the amount of the water present in
the electrolytic cell and the capacity of the other parts of the
piping preferably are smaller.
[0153] It is preferred that the two feeder wires extending from the
electrodes should be covered with an insulating material in order
to prevent the wires from coming into contact with each other. It
is preferred that each feeder wire led out of the second tube
should be inserted into a covering tube having heat shrinkability
and the covering tube be fusion-bonded to the wire to thereby
isolate the wire from the electrolytic-water channel in the
unit.
[0154] In the case of synthesizing ozonized water, too small
lengths of the second tube extending from the electrolytic cell to
the apparatus outlet are undesirable because the raw water in which
the ozone has not sufficiently dissolved is ejected in this case.
The longer the gas/liquid contact time, the more the dissolution of
the gaseous ozone in the raw water proceeds and the more the
efficiency of the synthesis thereof can be increased. It is
therefore preferred that the optimal length be regulated so as to
result in a contact time in the range of 0.1-10 seconds.
[0155] The material of the vessel for storing raw water therein and
the material of the piping are selected from ones which are not
attacked by raw water. The materials may be a PE resin when there
is no particular problem.
[0156] With respect to electrolysis conditions, the temperature and
the current density preferably are 5-40.degree. C. and 0.01-1
A/cm.sup.2, respectively, from the standpoints of the stability and
activity of substances yielded.
Raw Water and Electrolytic Water Yielded:
[0157] Tap water, well water, or the like can be used as raw water.
In this case, it is preferred to pass water through the cathode
chamber in order to inhibit the deposition of Ca and Mg. It is also
preferred to make the raw water weakly acidic.
[0158] Because such water has a low conductivity, there are cases
where the resistance loss in the cell voltage is not negligible and
it is preferred to increase the conductivity. In this case, it is
preferred to dissolve a salt such as Na.sub.2SO.sub.4,
K.sub.2SO.sub.4, NaCl, KCl, or Na.sub.2CO.sub.3 as an electrolyte.
There are cases where these salts yield a peroxide upon
electrolysis and thereby impart the persistence of a sterilizing
effect. The concentration thereof is preferably in the range of
0.01-10 g/L. Since an electrode such as, e.g., platinum has the
property of increasing in ozone generation efficiency when chloride
ions are present, it is preferred to prepare raw water while taking
account of that property.
[0159] When raw water containing metal ions in a large amount, such
as tap water, well water, or seawater, is used, there is a
possibility that hydroxides or carbonates might deposit on the
surface of the cathode to inhibit reactions. Furthermore, oxides,
such as silica, deposit on the anode surface. For eliminating this
problem, a reverse current is caused to flow at an appropriate time
internal (from 1 minute to 1 hour), whereby acidification and
alkalifying occur at the cathode and the anode, respectively. As a
result, reactions for removing the deposits readily proceed while
being accelerated by gas evolution and the flow of the feed
water.
[0160] The composition and concentration of the electrolytic water
to be yielded can be regulated according to purposes. In the case
where the electrolytic water is intended to be used for food
treatment, it should be produced as alkaline electrolytic
hypochlorite water, slightly acid electrolytic water, or ozonized
water. However, in the case where the electrolytic water is
intended to be used for sterilization/bleaching, a peroxide may be
suitably selected according to the substance to be treated. In the
case of hypochlorous acid, the concentration thereof may be 1-100
ppm. Ozonized water may have a concentration of 1-20 ppm. The
concentrations of persulfuric acid and percarbonic acid may be
1-100 ppm and 1-100 ppm, respectively.
[0161] In the case where hypochlorous acid is to be
electrolytically yielded, electrolysis of an acid solution yields
hypochlorous acid in a larger amount than a hypochlorite, while use
of an alkaline solution yields a hypochlorite in a larger amount
than hypochlorous acid. Bactericidal activity varies depending on
the nature of the solution. In general, acid solutions often have
higher bactericidal activity than alkaline solutions. In the
control of, in particular, spores and the like, acid solutions have
higher sporicidal activity than alkaline solutions. In contrast,
with respect to fungicidal activity, alkaline solutions are more
active than acid solutions. It is therefore preferred that the
nature of the solution should be suitably regulated so as to be
acid or alkaline according to the substance to be treated to
thereby impart improved bactericidal or fungicidal activity
thereto.
[0162] In case where the solution is acidified by adding a strong
acid to the solution to excessively enhance acidity, the
hypochlorous acid decomposes to generate chlorine gas and, as a
result, the oxidizing ability which brings about the bactericidal
activity of hypochlorous acid is impaired. For enhancing the
bactericidal activity while maintaining the oxidizing ability of
the hypochlorous acid, it is preferred to regulate the solution so
as to have a pH of 3-7 at 20.degree. C. For regulating the solution
so as to have such a pH, it is preferred to use a water-soluble
organic weak acid having a low degree of dissociation from the
standpoint of ease of pH regulation of the solution. Examples of
the water-soluble organic acid include succinic acid, lactic acid,
acetic acid, citric acid, and tartaric acid.
[0163] For alkalifying the solution, it is preferred to use sodium
carbonate, sodium hydrogen carbonate, ammonium carbonate, or the
like. Such carbonates are oxidized to percarbonic acid by
electrolysis.
[0164] A surfactant may be added to the solution in order to
further improve bactericidal activity. Addition of a surfactant to
the solution not only improves the ability of the solution after
electrolysis to wet the substance to be treated therewith, but also
improves the affinity of the solution for the cell membranes of
mold and germs. Thus, the bactericidal or fungicidal effect further
improves.
[0165] Usable examples of the surfactant include anionic
surfactants such as alkylbenzenesulfonic acid salts and
polyoxyethylene alkyl ether sulfuric acid salts, cationic
surfactants such as benzalkonium chlorides, amphoteric surfactants
such as amine oxides (e.g., alkyldimethylamine oxides), and
nonionic surfactants such as polyglycerol fatty acid esters and
alkylglycosides. The concentration of the surfactant in the
solution is preferably 0.01-10% by weight.
[0166] Besides those ingredients, an alcohol may be added to the
solution for the purpose of, e.g., improving bactericidal or
fungicidal activity and refreshing feeling. Furthermore, additives
such as, e.g., a perfume, colorant, bactericide other than
surfactants, thickener, enzyme, bleaching agent, chelating agent,
electrolyte other than chlorine compounds, builder, antiseptic, and
rust preventive may be added according to need. It is especially
preferred from the standpoint of storage stability that the water
to be electrolyzed should contain an antiseptic.
Electrolytic-Water Sprayer (Trigger Spray):
[0167] The electrolytic-water sprayer includes a vessel for
containing raw water therein and a head connected to the upper
opening of the vessel. Although the vessel may be either rigid or
flexible, it is preferred that the vessel should be made of a rigid
material selected from, e.g., various rigid resins, metals,
glasses, and ceramics. The capacity of the vessel is preferably
about 10-1,000 mL, more preferably 200-500 mL.
[0168] The trigger spray has been fixed to a head in which a
battery can be housed. The apparatus may be equipped with a device
which generates power for electrolysis upon trigger operation,
without employing a battery as a power source. In place of using a
simple primary battery, use may be made of a secondary battery or
capacitor, which is rechargeable. It is also possible to operate
the apparatus with an adapter capable of supplying DC power from an
AC power source.
[0169] The values of the voltage and current to be applied are
suitably determined according to the concentration suitable for
obtaining given bactericidal activity suitable for the substance to
be deodorized, sterilized, or otherwise treated and to the volume
of the solution to be electrolyzed. One trigger operation results
in the ejection of 0.1-1 cc, and a voltage of about 3-40 V is
applied between the electrodes. A device for changing the voltage
to be applied to the electrodes may be disposed in the circuit.
[0170] A switch for initiating/terminating voltage application to
the electrodes has been disposed in the trigger spray so that a
voltage is applied only when the apparatus is in use, i.e., pulling
the trigger automatically results in switching on and returning the
trigger results in switching off.
[0171] The electrolytic-water sprayer may have a device which
generates power for electrolysis upon a production operation.
Examples of this device include a motor which interlocks with the
trigger. This motor is usually disposed in the trigger spray.
[0172] The electrolytic-water sprayer can have means for indicating
that electrolysis is being conducted. Examples of the means include
an LED lamp which is made on during voltage application by a
trigger operation. A function may be added which switches off the
LED lamp when a specified current does not flow due to, e.g.,
battery exhaustion.
[0173] The electrolytic-water sprayer works by the following
mechanism. The sprayer is switched on by a trigger operation to
cause a current to flow through the circuit. As a result, the
current flows through the electrodes. In this operation, the raw
water present in the tube is electrolyzed almost instantaneously
and ejected or sprayed outward through the nozzle of the head by a
piston/cylinder mechanism. Namely, in this sprayer of the
invention, electrolysis is conducted simultaneously with a
production operation (e.g., trigger operation). It is preferred
that electrolytic water should begin to be yielded by electrolysis
within 1 second after the initiation of a trigger operation.
[0174] Besides the embodiment shown in figures, there are various
embodiments of the electrolytic-water sprayer equipped with a
trigger spray. Furthermore, there are trigger sprays having various
mechanisms. The trigger sprays differ in the liquid passage
therein, the position of the fulcrum of the trigger, etc. according
to the mechanisms. However, any desired trigger spray can be
employed in the sprayer of the invention.
[0175] Next, the electrolytic-water sprayer of the invention is
explained with respect to the embodiment shown in figures. FIG. 1
is a front view illustrating an electrolytic-water sprayer as one
embodiment of the invention. FIG. 2 is an exploded enlarged view of
an important part of the sprayer shown in FIG. 1. FIG. 3 is a slant
view of the electrolytic cell shown in FIGS. 1 and 2.
[0176] The electrolytic-water sprayer (trigger spray) 1 shown in
FIG. 1 includes a vessel 3 for containing raw water 2 and a head 4
connected to the upper opening of this vessel 3. The raw water 2
may be pure water or may be one containing one or more electrolytes
dissolved therein, such as, e.g., sodium chloride, potassium
chloride, and magnesium chloride.
[0177] In the vessel 3 has been disposed an electrolytic cell 6
composed of an anode, a cathode, and a diaphragm. As shown in FIG.
2, this electrolysis cell 6 is constituted of; an anode 7 which is
a metallic rod electrode on which a catalyst has been deposited; a
diaphragm 8 which is a tubular ion-exchange membrane wound around
the anode 7; and a wire cathode 9 which is a metallic wire wound
around the diaphragm 8. This diaphragm 8 is obtained by rolling a
square sheet so as to have a circular shape when viewed from above
and bonding two end parts along the lengthwise direction.
[0178] The diaphragm 8 intrinsically has no recesses/protrusions.
However, by winding the wire cathode 9 on the diaphragm 8, that
part of the diaphragm 8 which is in contact with the wire cathode 9
is strongly pushed against the anode 7, and that part of the
diaphragm 8 which is not in contact with the wire cathode 9 is bent
outward to form a spiral anode chamber 10 between the anode 7 and
the diaphragm 8.
[0179] Furthermore, that space in the vessel 3 which is on the
outer side of the diaphragm 8 constitutes a cathode chamber.
[0180] A tube for feeder wire holding 13 has been connected to the
upper end of the rod anode 7 through a cylindrical connecting tube
12 having a short length. A feeder wire 14 is held between the
inner surface of the connecting tube 12 and the outer surface of
the tube for feeder wire holding 13, and an end of the feeder wire
14 has been connected to an upper end part of the anode 7.
[0181] The upper end of the tube for feeder wire holding 13 has
been fitted into a vertical pipeline 15 in the head 4, and the
upper end of the vertical pipeline 15 is communicatively connected
to a horizontal pipeline 16 in the head 4.
[0182] At the other end of the horizontal pipeline 16 has been
disposed a spray nozzle 17. A fulcrum 19 of a trigger arm 18 has
been disposed on the slightly inner side of the spray nozzle 17 so
that the trigger arm is swingably movable around the fulcrum 19.
The trigger arm 18 has been connected to a piston rod 20 extending
inward so that the piston rod 20 travels in a cylinder 21 according
to the movement of the trigger arm 18.
[0183] Numeral 22 denotes a trigger-engaged switch disposed so as
to be in contact with the trigger arm 18; 23 denotes a power source
battery disposed in the head 4; and 24 denotes an LED which is on
only when electrolysis is proceeding.
[0184] The electrolytic-water sprayer 1 having such constitution is
held in a hand, and an inward force is applied to the trigger arm
18 with the forefinger and middle finger. As a result, the trigger
arm 18 moves around the fulcrum 19, whereby the trigger-engaged
switch 22 becomes on and a voltage is applied to the electrolytic
cell 6. Simultaneously therewith, the piston in the cylinder 21
moves to bring the raw water 2 present in the vessel 3 into contact
with the electrolytic cell 6, where this raw water 2 is
electrolyzed to yield electrolytic water. The anode 7 in this
electrolytic cell 6 has a catalyst, such as, e.g., a layer of
conductive diamond, deposited on the surface thereof. Thus,
electrolytic water containing ozone or other active species
dissolved therein in a high concentration is obtained. Since a
spiral anode chamber 10 has been formed inside the diaphragm 8 in
this electrolytic cell 6, an appropriate gas/liquid passage is
formed in the anode chamber. Consequently, the concentration of an
electrolytically yielded species in the electrolytic water can be
regulated to a desired value by changing the water feed rate and
current value.
[0185] The electrolytic water yielded passes instantaneously
through the vertical pipeline 15 and horizontal pipeline 16 and is
sprayed through the spray nozzle 17 on a substance to be
sterilized, together with air introduced through an outside-air
intake opening not shown.
[0186] FIG. 4 is a partial sectional view illustrating another
electrolytic cell according to the invention. This figure shows an
embodiment employing a porous cathode and an anode to which
recesses and protrusions have been imparted.
[0187] The electrolytic cell 32 is constituted of an anode (rod
electrode), a cathode (counter electrode), and a diaphragm. This
electrolytic cell 32 is composed of: an anode 34 which is a
metallic rod electrode having a spiral groove 33 formed in the
periphery thereof; a diaphragm 35 which is an ion-exchange membrane
formed into a tubular shape and disposed around the periphery of
the anode 34; and a porous cathode 36 having the shape of a metal
gauze, expanded mesh, or punching metal and disposed around the
periphery of the diaphragm 35.
[0188] Unlike the embodiment shown in FIGS. 1 to 3, this embodiment
is substantially free from deformation of the diaphragm 35 toward
the anode 34 by the porous cathode 36. However, since the anode 34
has a groove 33 formed in the periphery thereof, this embodiment
has an anode chamber 37 formed between that part of the diaphragm
35 which corresponds to the groove 33 and the anode 34.
[0189] In this embodiment also, an appropriate gas/liquid passage
is formed in the anode chamber, and the concentration of an
electrolytically yielded species in the electrolytic water can be
regulated to a desired value by changing the water feed rate and
current value.
[0190] The embodiment in which the anode has recesses and
protrusions should not be construed as being limited to that having
the groove. Although the embodiment explained above employs a
rod-form or tubular anode having a circular shape when viewed from
above, the shape of the anode is not limited thereto. For example,
the anode may have shapes such as those shown by the plan views in
FIGS. 5 and 6.
[0191] The diaphragm 41 in FIG. 5 has a vertically tubular form
obtained by rolling a square sheet and bonding overlap parts 42 of
the two ends to each other. The rod anode 43 has protrudent parts
44 projected outward respectively in six parts of the base in a
solid cylinder form. The tubular diaphragm 41 has been stretched on
and around the six protrudent parts 44. Six anode chambers 45 in
total have been thus formed between the diaphragm 41 and the anode
43.
[0192] In the case of FIG. 6 also, the diaphragm 46 has a
vertically tubular form obtained by rolling a square sheet and
bonding overlap parts 47 of the two ends to each other. The tubular
anode 48 has a shape obtained from a prismatic base by forming a
recessed part 49 depressed inward at each of the four corners. The
tubular diaphragm 46 has been stretched on and around a total of
eight base parts of the four recessed parts 49. Anode chambers 50
corresponding to the shapes of the recessed parts 49 are formed
between the diaphragm 46 and the anode 48.
[0193] FIG. 7 is a partial slant view illustrating a still other
embodiment of the electrolytic cell of the invention, and FIG. 8 is
a transverse sectional view of the electrolytic cell of FIG. 7.
This embodiment relates to an improvement of the embodiment shown
in FIGS. 1 to 3, and explanation of common members will be omitted
by assigning the same reference numerals.
[0194] In the electrolytic cell 6a shown in FIGS. 7 and 8, two rods
of anodes made of niobium and covered with a conductive-diamond
catalyst on the surface thereof are wrapped by an ion-exchange
membrane 8a so as to form two layers of the membrane in tubular
form, and a stainless wire serving as a cathode 9a is spirally
wound on the membrane to thereby form an anodes-membrane-cathode
assembly (electrolytic cell).
[0195] According to this embodiment, as shown in FIG. 8, the anodes
7a are in rod-form, and a relatively large space is formed between
the two anodes 7a each having a curved surface. In addition, a
relatively large space is also formed between the anodes 7a and the
ion-exchange membrane 8a. These spaces function as an anode chamber
10a, and electrolytic water passes through this anode chamber
10a.
[0196] According to this embodiment, cost- and time-consuming
processing of the anode per se is not required unlike the
embodiment as shown in FIGS. 4 to 6. Despite that, this embodiment
provides an anode chamber having a volume equal to or rather larger
than that in the embodiment of FIGS. 4 to 6.
EXAMPLES
[0197] Examples concerning the production of electrolytic water
according to the invention will be given below. However, the
invention should not be construed as being limited to the following
Examples. The ozone concentration, hypochlorous acid concentration,
persulfuric acid concentration, and percarbonic acid concentration
in each Example were determined with an ultraviolet
spectrophotometer and by iodometry using potassium iodide.
Example 1
[0198] A rod made of niobium (diameter, 2 mm) on which a
conductive-diamond catalyst (dopant boron concentration, 2,500 ppm)
had been deposited was placed as an anode in a tubular ion-exchange
membrane (Nafion 350, manufactured by DuPont; thickness, 0.35 mm;
diameter, 3 mm). A commercial platinum wire (diameter, 0.4 mm) was
spirally wound as a cathode on the diaphragm to obtain an
anode-membrane-cathode assembly. The winding pitch was 4 mm. Tubes
(diameter, 4 mm) were bonded to upper and lower parts of the
assembly, and feeder wires from a DC power source were connected to
the respective electrodes to obtain an electrolytic cell. Pure
water was passed upward through the anode chamber at a rate of 40
cc/min. Currents of 0.5 A and 1 A were separately caused to flow.
As a result, the cell voltages were 13 V and 19 V, respectively,
the ozonized water concentrations were 8 ppm and 21 ppm,
respectively, and the ozone generation efficiencies were 13% and
12%, respectively, in these operations. The temperature of the
water at the outlet was about 30.degree. C.
[0199] This electrolytic cell was connected in a trigger type
sprayer shown in FIG. 1 to a PE resin tube attached to the intake.
A battery was mounted in the head of the trigger type sprayer. In a
circuit part, the electrode terminals were connected to a variable
resistor and a switch with a wiring. The vessel was filled with 500
cc of pure water.
[0200] The trigger was pulled, upon which the circuit was switched
on and a current flowed between the battery and the cell.
Simultaneously therewith, pure water was ejected. The amount of the
pure water ejected was about 0.5 cc, and the quantity of
electricity which flowed during this operation was 0.25 C (0.5
s.times.0.5 A). The terminal voltage of the cell was 13 V. The
operation was repeatedly conducted 100 times. As a result, the
ozone concentration in the solution ejected, which amounted to
about 50 cc, was 8 ppm. The trigger operation was repeated 2,000
times, and the concentration of the ozonized water obtained
thereafter remained at about 8 ppm.
Comparative Example 1
[0201] The same materials as in Example 1 were used. A strip of the
ion-exchange membrane was spirally wound on the anode, and the
platinum wire was wound on the diaphragm to obtain an
anode-membrane-cathode assembly. Pure water was passed upward at a
rate of 40 cc/min through an electrolytic cell in which the
membrane-electrode assembly had been mounted. Currents of 0.5 A and
1 A were separately caused to flow. As a result, the oxygen and
ozone generated at the anode were mixed with the hydrogen gas
generated at the cathode because the diaphragm had been disposed
spirally, and electrolytic water containing these gases dissolved
therein was yielded. In these operations, the cell voltages were 10
V and 13 V, respectively, the ozonized water concentrations were 5
ppm and 9 ppm, respectively, and the ozone generation efficiencies
were 8% and 5%, respectively.
Example 2
[0202] Those parts of the membrane in the assembly of Example 1
which constituted the two openings of the anode chamber were fixed
to tubes having a diameter of 4 mm. The resultant member was
disposed in a second tube having an inner diameter of 5 mm to form
a cathode chamber between the second tube and the membrane. A
feeder terminal for the wire cathode was connected to the cathode
in the second tube. A 2 g/L aqueous solution of sodium chloride was
fed to the anode chamber at a rate of 40 cc/min, and water was fed
also to the cathode chamber in the same manner. A current of 1 A
was caused to flow. As a result, alkaline water containing hydrogen
and having a pH of 11 and acid water containing hypochlorite ions
in an amount of 40 ppm could be simultaneously yielded.
Example 3
[0203] The same test as in Example 2 was conducted, except that tap
water was fed to the anode chamber and the cathode chamber. As a
result, the ozonized water yielded at 0.5 A had a concentration of
4.5 ppm (current efficiency, 7.3%).
Comparative Example 2
[0204] The same test as in Comparative Example 1 was conducted,
except that tap water was used as a raw material. As a result, the
ozonized water yielded at 0.5 A had a concentration of 1.5 ppm
(current efficiency, 2.4%).
Example 4
[0205] A round rod made of titanium which had a platinum layer
formed thereon (20 g/m.sup.2) was used as an anode to produce the
same assembly as in Example 1. Using tap water as a raw material,
the same test as in Example 3 was conducted. As a result, the cell
voltage at 0.5 A was 12 V, and the ozonized water had a
concentration of 0.5 ppm.
Example 5
[0206] Two rods made of niobium (diameter, 2 mm) on which a
conductive-diamond catalyst had been deposited (dopant boron
concentration, 1,000 ppm) as anodes were wrapped by an ion-exchange
membrane (Nation 324, manufactured by DuPont; thickness, 0.35 mm;
diameter, 3 mm) so as to form two layers of the membrane in tubular
form, and a stainless wire (diameter, 0.5 mm) serving as a cathode
is spirally wound on the membrane to thereby obtain an
anodes-membrane-cathode assembly as shown in FIGS. 7 and 8. The
winding pitch was 2 mm.
[0207] Tubes (diameter, 4 mm) were bonded to upper and lower parts
of the assembly, and feeder wires from a DC power source were
connected to the respective electrodes to obtain an electrolytic
cell. Pure water was passed upward through the anode chamber at a
rate of 40 cc/min. Currents of 0.5 A and 1 A were separately caused
to flow. As a result, the cell voltages were 13 V and 19 V,
respectively, the ozonized water concentrations were 15 ppm and 17
ppm, respectively, and the ozone generation efficiencies were 13%
and 15%, respectively, in these operations. The temperature of the
water at the outlet was about 30.degree. C. Water leakage from the
tubular membrane scarcely occurred.
[0208] While the present invention has been described in detail and
with reference to specific embodiments thereof, it will be apparent
to one skilled in the art that various changes and modifications
can be made therein without departing from the spirit and scope
thereof.
[0209] This application is based on Japanese Patent Application
Nos. 2007-296769 (filed Nov. 15, 2007) and (filed Oct. 15, 2008),
and the contents thereof are herein incorporated by reference.
* * * * *