WO2001027037A1

WO2001027037A1 - Apparatus for producing high-concentration electrolytic water

Info

Publication number: WO2001027037A1
Application number: PCT/KR2000/000004
Authority: WO
Inventors: Jae Duk Moon
Original assignee: Ecoaid Corp.
Priority date: 1999-10-14
Filing date: 2000-01-06
Publication date: 2001-04-19
Also published as: KR100346824B1; CN1379737A; KR20010037187A; AU3078900A; JP2003516216A; EP1235751A1

Abstract

An apparatus for producing high-concentration electrolytic water is provided. Forming a pair of electrodes facing each other using a platinum (Pt) alloy containing palladium (Pd) prolongs the electrode life. Forming slits on the facing electrodes to make the apparatus highly efficient, thereby generating high-concentration electrolytic water, reduces a water flow rate and a space charge effect. Applying square-wave pulse power voltages can facilitate electrophysicochemical reaction and electrolysis. The polarities of applied pulse power voltages are alternated to suppress the electrodes from being scaled due to impurities. Strong alkaline water and strong acid water can be obtained by adding salt to service water. Further, neutral water can be obtained and hydrogen ion concentration (pH) can be controlled, by removing a separating membrane.

Description

APPARATUS FOR PRODUCING HIGH-CONCENTRATION ELECTROLYTIC

WATER

Technical Field

The present invention relates to an apparatus for producing strong electrolytic water by installing a pair of electrodes facing each other, in opposite sides of a separating membrane installed in water to prevent the electrodes from being precipitated in water, and by forming the facing electrodes using platinum (Pt) alloy containing palladium (Pd), thereby greatly extending the electrode life. Also, the present invention relates to an apparatus for producing strong electrolytic water, by forming slits on the facing electrodes or additionally installing another pair of electrodes facing each other in inner or outer portions of the initially installed facing electrodes, thereby making the apparatus highly efficient with a reduced power consumption, while reducing a water flow rate and a space charge effect. Furthermore, the present invention relates to an apparatus for producing strong electrolytic water and functional neutral water, by applying a predetermined pulse voltage to the facing electrodes to effectively arouse a high- voltage discharge and electrolysis in water, thereby making high-concentration ions and strong oxidants included in water.

Background Art

In general, in order to produce an electrolytic water, a pair of electrodes in water, which face each other and which are made of titanium (Ti) plates coated with platinum (Pt) or flat-panel type ferrite electrodes, are installed in parallel in opposite sides of a separating membrane installed in the center. Then a direct-current (DC) voltage is applied in- between the facing electrodes to produce acidic water and alkaline water at outlet passages. However, in this case, the electrode life is short, and it is difficult to apply a high voltage of over several tenth to the electrodes. That is to say, since the efficiency is poor, producing strong acidic water and alkaline water containing oxidants is hard to achieve.

Producing a functional and electrolytic water in the above-described manner is effective and economical because rich ions and strong oxidants are produced effectively in water. That is to say, with this manner, positive ions such as metal mineral ions including Ca⁺⁺, Fe^"^, Mg^"^ and Cu* ^" or negative ions including Cl^~, SiO ^~ and SiO₃ ^", and strong oxidants such as O, O₃, H₂O and HC1O are separated and produced in water. Also, by the actions of strong oxidation, including sterilization, deodorization, decolorization and the like, the above-described electrolytic water producing manner can be widely applied to various fields: drinking water treatment, food processing, food reservation and sterilization, bactericidal treatment of agricultural products or raw fish, disposal of industrial waste water, removal of ill-odored or volatile organic compounds (NOCs), substitution of agricultural chemicals, sterilization in the course of food preparing and processing pharmaceuticals, or rinsing and sterilization in the medical fields, such as doctor's hands to be disinfected and medical instruments and tools such as knives, scissors and stomach or vaginal or intestines endoscope.

However, in order to obtain the ozonated water with the conventional apparatus in which ozone is generated using an electric discharge, an ozone gas is impregnated into water to meet for these various practical uses, and a diffuser and a blower must be used. Thus, there may be met some technical problems such as very poor diffusing efficiency, leakage of ozone to living space, clogging or noise of the system, and higher cost problem.

FIG. 1 shows a conventional electrolytic water producing apparatus (I) for producing electrolytic water having a relatively low concentration. Referring to FIG. 1, a water inlet channel 4, and electrolytic water outlet channels 6 and 8 are provided. Also, a pair of plate electrodes 1 and 3 facing each other are spaced apart a predetermined spacing from a separating membrane 2, in an insulating case 9. Tap water supplied through the water inlet channel 4 is electrolyzed by a direct-current (DC) voltage N _C applied when the tap water passes between the plate electrodes 1 and 3, thereby producing acidic water and alkaline water to then be drained out via the outlet channels 6 and 8. In the above-described conventional electrolytic water producing apparatus (I), the tap water is electrolyzed in the plate electrodes 1 and 3 to which the DC voltage V_αc shown in FIG. 2 is applied to then produce weak acidic water and weak alkaline water. Also, in order to operate efficiently the plate electrodes 1 and 3 at as lower the DC voltage V_dC as possible, the distance therebetween is set to be very narrow, that is, 0.01 to 2 mm. In the conventional electrolytic water producing apparatus (I), since a high DC voltage of over several tenth voltage is hard to apply to the electrodes because of shortening the electrode life, that is known as Faraday's Law, the efficiency of producing electrolytic water is relatively lower. Also, even if the amount of supplied tap water is relatively reduced and a relatively high DC voltage is applied, a large amount of ions and oxidants cannot be precipitated and generated. Further, a large amount of current that flows along the narrow space between the plate electrodes 1 and 3, generates a large amount of heat proportional to the square of the current, that is, Joule heat is caused by the current, thereby promoting pyrolysis of the strong oxidants generated, as indicated as Formula 1. In other words, the concentration of oxidants of the produced electrolytic water cannot be considerably increased. [Formula 1]

2O₃ → 3O₂ (1)

4HC1O → 2 H₂O₂ + 2C1₂ (2)

2H₂O₂ → 2H₂O + O₂ (3)

Also, since ferrite, pure platinum (Pt) or Pt-coated Ti electrode is used as the electrode material of the electrolytic water producing apparatus, the electrode life is short when it is used in a medium-sized or large-sized electrolytic water producing apparatus to which a high DC current must be applied. As a result, according to the above-described electrolytic water producing apparatus (I), it is hard to produce a strong electrolytic water.

Disclosure of the Invention To solve the above problems, it is an objective of the present invention to provide a novel apparatus for producing an electrolytic water containing a large amount of ions and strong oxidants, and a functional neutral water, by improving the structure and configuration of electrodes, the types, duty and amplitude of applied voltages and the electrode material. To accomplish the above objective, an electrode by which strong oxidants are generated, that is, an anode, is made of an alloy of Pt and Pd, which is scarcely precipitated in water, thereby greatly extending the electrode life. Alternatively, a ferroelectric thin layer may be formed on a metal having a similar thermal expansion coefficient, such as dumet or aluminum, to extend the life of the strong-oxidant-generating electrode. Also, the novel apparatus operating with a low power consumption can be achieved without reducing the fed tap water flowing between inner electrodes and the electrode spacing. For this purpose, the outer electrodes are formed of plate type electrodes while the inner electrodes are formed of plate type electrodes having many slits through which the water leaks out, or thin-strip, fine-wire or mesh type plate electrodes. A square-wave pulse high voltage or any other similar kind of pulse high voltage which is sequence-controlled is applied between the electrodes in an appropriate duty, thereby facilitating the oxygen gas discharge and electrolysis on the surface of the electrodes in the tap water. Further, the pulse voltages are alternately applied to the electrodes, thereby being no scaling on the electrodes due to solid impurities dissolved in the tap water. As a result of these means, effective and strong electrolytic water can be produced in the tap water to be used as many fields of applications. In addition, a powerful acidic water having high-concentration oxidants dissolved therein, a strong alkaline water, and a functional neutral water can also be obtained by adding a Cl-containing additive such as NaCl or KC1 etc., which is necessary for producing a powerful oxidant of HC1O. In order to increase the amount of produced electrolytic water, the plural number of the apparatuses according to the present invention may be installed in parallel connection. Alternatively, in order to increase the power of electrolytic water, the plural number of the apparatuses according to the present invention may be installed in series connection. However, an explanation of detailed examples thereof will be abbreviated.

Brief Description of Drawings

FIG. 1 is a schematic diagram of a conventional electrolytic water producing apparatus;

FIG. 2 is a waveform of a power applied to the conventional electrolytic water producing apparatus shown in FIG. 1 ; FIG. 3 is a schematic diagram of an electrolytic water producing apparatus according to an embodiment of the present invention;

FIG. 4 is a waveform of a square-wave pulse power applied to the electrolytic water producing apparatus shown in FIG. 3;

FIG. 5 is a waveform of a half-wave pulse power applied to the electrolytic water producing apparatus shown in FIG. 3; FIG. 6 is a schematic diagram of an electrolytic water producing apparatus according to another embodiment of the present invention;

FIG. 7 is a circuit diagram of a pulse power generating circuit of the electrolytic water producing apparatus shown in FIG. 3; FIG. 8 is a waveform of a three-pulse power applied to the electrolytic water producing apparatus shown in FIG. 6;

FIG. 9 is a waveform of a sequence-controlled three-pulse power applied to the electrolytic water producing apparatus shown in FIG. 6;

FIG. 10 is another waveform of a sequence-controlled three-pulse power applied to the electrolytic water producing apparatus shown in FIG. 6;

FIG. 11 is a circuit diagram of a sequence-controlled three-pulse power generating circuit of the electrolytic water producing apparatus shown in FIG. 6;

FIG. 12 is a schematic diagram of an electrolytic water producing apparatus according to another embodiment of the present invention; FIG. 13 is a graph showing the ozone concentration of electrolytic water produced from the normal tap water;

FIG. 14 is a graph showing the oxidants concentration of electrolytic water produced from the tap water in which a small amount of salt is dissolved;

FIG. 15 is a graph showing the pH level of electrolytic water produced from the normal tap water; and

FIG. 16 is a graph showing the pH level of electrolytic water produced from the tap water in which a small amount of salt is dissolved.

Modes for Carrying out the Invention

Now, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

In order to solve the problems of the conventional electrolytic water producing apparatus (I), that is, production of a little powerful electrolytic water, it is necessary to apply a high voltage to the facing electrodes, by which more powerful electrolytic water is produced, to make a large amount of current flow therebetween. In an electrolytic water producing apparatus (II) according to the present invention, shown in FIG. 3A, a square-wave pulse voltage Vp (FIG. 4) or a half-wave pulse voltage

V_pac (FIG. 5) may be employed.

In this case, however, the facing electrodes 11 and 13 may be severely scaled due to a large amount of impurities contained in the tap water, so that the current is sharply decreased within several tens of hours to then stop generating the electrolytic water further more. To solve this problem, it is necessary to alternate the polarity of the applied voltage of the facing electrodes 11 and 13.

In other words, a negative voltage is applied to the anode 13 and a positive voltage is applied to the cathode 11 and then alternates each other. Here, it is necessary to install a means for alternating the polarity of voltage applied between both electrodes 11 and 13 at appropriate time periods, that is, between several tens of seconds and several tens of minutes. Concurrently, the configuration of electrolytic water drain channels is also changed each other. Thus, a means suitable for the changed electrolytic water drain channels, for example, an automatic converter using an electromagnetic valve, is also necessary.

In the electrolytic water producing apparatus (II) according to the present invention, shown in FIG. 3, the anode 13 and the cathode 11, which are mesh-typed, are opposed to and spaced apart from each other at opposite sides of a separating membrane 12.

Here, the plate areas of the both electrodes 1 ! and 13 are made to be as wide as possible, and the spacing d between both electrodes 11 and 13 is made to be as narrow as possible, thereby reducing electric resistance therebetween, resulting in effective electrolysis at as low a voltage as possible.

However, since the spacing d between two electrodes 11 and 13 is short, the water flowing therebetween is turbulent. Thus, the electric current flowing vertically around both electrodes 11 and 13 is made to flow turbulently, which causes the produced strong oxidants decomposed, thereby lowering an electrolysis efficiency. Also, ions having opposite polarities, which drift toward opposite sides of the electrodes 11 and 13, act as the space charges and are subjected to space charge limiting action, which further reduces the electrolysis efficiency. These problems can be solved by reducing a water flow rate between the electrodes and a turbulent water current, such that the electrolytic water produced between the electrodes 11 and 13 are drained through the slits to a wider out side by increasing the water flow width D while reducing the electrode spacing d, by means of the electrodes 11 and 13 meshed or having slits, as shown in FIG. 3. In this case, since the electrode spacing d can be further reduced, the apparatus can be driven to a relatively higher voltage and current state, thereby effectively taking place the oxygen gases discharges and the electrolysis actions in water at the lower power consumption. Consequently, the electrolysis efficiency can be greatly enhanced.

The electrode spacing d can be arbitrarily determined according to the desired concentration and amount of the electrolytic water for the various applications, by reducing or enlarging the electrode spacing d from the membrane 12.

The electrolytic water producing apparatus (II) according to the present invention, shown in FIG. 3, has been described that it is constructed of plate type electrodes having slits. However, the construction of the electrolytic water producing apparatus may be modified such that a cylindrical electrode of a wire, wire type or thin-strip type forms the anode 13, and a concentric-cylindrical electrode of a mesh, strip type or wire type forms the cathode 11. However, an explanation of detailed embodiments thereof will be abridged.

In the electrolytic water producing apparatus (II) according to the present invention, shown in FIG. 3, higher-concentration electrolytic water can be obtained, compared to the case in the conventional electrolytic water producing apparatus (I). However, if the electrode spacing d is reduced greatly, then, as a result, the electrical field (N_P/d) is concurrently increased, which makes the current density, i.e., the ion concentration, increase, which acts as the space charge limiting in the electrolytic region. Thus, the effective production of electrolytic water cannot be achieved.

In other words, in the electrolytic water producing apparatus (TI) according to the present invention, if the square-wave pulse voltage N_P is applied to the electrodes 11 and 13, charges having opposite polarities converged by electrostatic force, that is Coulomb's Force, the charges including ions generated by discharge or electrolysis or ions present in water, are crowded in a space around the electrodes 11 and 13. The crowded space charges in the space around the electrodes 11 and 13 repulse the charges having the same polarity to migrate in a subsequent stage, so as to impede further migration of the charges, which is referred to a space charge limiting action, thereby reducing the amount of current. Thus, the efficiency of precipitating ions and producing strong oxidants is considerably decreased.

To solve the above problem, an improvement of the electrolytic water producing apparatus (II) according to a preferred embodiment of the present invention is shown in FIG. 6. In detail, an outer cathode 21 is additionally installed at an outer side of the cathode 11 and an outer anode 23 is additionally installed at an outer side of the anode 13. This allows the concentrated charges between the anode 13 and the separating membrane 12, and between the cathode 11 and the separating membrane 12, to rapidly move outside an anode water area Bp and a cathode water areas Ap, that is, areas B and A, by the action of electrostatic force (Coulomb's Force). The electrostatic force is produced due to a B- side pulse voltage V_PB, and an A-side pulse voltage V_PA to greatly reduce charges between both electrodes 11 and 13, which considerably lessens the space charge limiting action. Thus, with the same square-wave pulse voltage Np, a relatively larger electric field (E= Np/d) can be obtained, thereby greatly improving the capability and efficiency of precipitating ions and producing strong oxidants. Thus, the crowded charges between the electrodes 11 and 13 and the electrolytic water having rich ions and strong oxidants dissolved therein are easily moved out toward the outer cathode 21 and the outer anode 23, that is, the cathode water area A and the anode water area B. As a result, the pyrolysis defined in formula (1) as well as the turbulence and the space charge limiting action are considerably moderated, thereby more effectively producing the electrolytic water having much ions and strong oxidants dissolved therein. The reason why the electrodes 11 and 13 are formed of a mesh, fine-wire or slit type and the electrode spacing d is made to be narrow is to effectively take place an oxygen gas discharge on the electrodes 11 and 13. In other words, a discharge is easily occurred on a sharp tip and a fine wire or slit, for example, even under a relatively low electric field. In particular, if a high- voltage pulse is applied, an oxygen molecule (O ) is generated in the anode 13 in water, by the electrolysis as defined as Formula (2): [Formula 2]

2H₂O → 2H₂ (cathode) + O₂ (anode) Since the oxygen molecule is in a gaseous state, the dielectric constant thereof is far smaller than that of water, that is, the dielectric constant ratio of water to oxygen molecule is 80:1, voltages are mostly applied to the oxygen molecule so that the oxygen molecule is decomposed due to discharge. Thus, oxygen atoms (20) or activated species such as OH radicals are produced, as expressed in Formula (3):

[Formula 3] O₂ → O + O ...(1)

H₂O → OH + H ...(2)

The oxygen atoms (20) and OH radicals are bonded each other and/or with another neighboring molecules to produce strong oxidants such as O₃, HC1O, H O or O, as defined as Formula (4): [Formula 4]

O + O₂ → O₃ ...(1)

OH + C1 → HCIO ...(2)

OH + OH → H₂O₂ ...(3)

Here, in comparison with a direct-current (DC) power, an alternate-current (AC) power or any other type of power, or a pulse power can occur the gas discharges effectively and it can economically produce strong oxidants such as O₃, HC1O, H₂O or O, which will later be described in more detail.

Here, if the electrodes 11 and 13 are formed of a mesh, fine-wire or thin-strip type, the dimensions of the electrodes, such as wire diameter, mesh and thickness or width of the strip, are determined by the types or amplitudes of applied voltages, the oxidants concentration or needing quantity of generated electrolytic water, the electrode life time, the purpose and application fields, the size or price of the apparatus, and so on. This is because the Pt group alloy, e.g., Pt+Pd, which is used as the electrode material is expensive.

However, in the case of a small-scale apparatus, whose electrode life time is not necessarily so long, and the worn-out one may be often replaced, another type of cheap metal such as stainless steel (SUS) or an alloy thereof, or another metal coated with Pt alloy (Pt+Pd), may be used as the electrode material.

Also, the separating membrane 12 preferably has good ion-permeability between the two areas Ap and Bp, and poor miscibility with water. As the separating membrane 12, a general ion-exchange resin membrane may be used. Also, the other ones, such as fabric, resin or ceramic could be used. Now, the type and period of the pulse power and means for applying the same will be described. It has been experimentally verified that the square-wave pulse power shown in FIG. 4 or 5 could be used to the conventional electrolytic water producing apparatus (I). However, the efficiency of the conventional electrolytic water producing apparatus (I) is poor, since the facing electrodes of the conventional electrolytic water producing apparatus (I) are flat-panel type electrodes.

Referring to FIG. 6, showing an improved electrolytic water producing apparatus (III) according to the present invention, which is fabricated from the electrolytic water producing apparatus (II), an outer cathode 21 and an outer anode 23 are further installed at outer sides of the cathode 11 and the anode 13, respectively. Also, it is possible to reduce the electrode spacing d, which corresponds to the sum of the distance between the anode 13 and the separating membrane 12 and the distance between the cathode 11 and the separating membrane 12. Otherwise, the electrodes 11 and 13 are sharply formed or are formed of a mesh, fine-wire or small-strip type. Then, a very high electrical field E is formed on the surfaces of the electrodes 11 and 13 when the square-wave pulse power shown in FIG. 4 or 5 is applied thereto. Thus, a discharge in water and electrolysis are more effectively generated and a large amount of current can be obtained, thereby greatly improving the capability and efficiency of precipitating ions and producing strong oxidants.

In other words, the spacing d between the electrodes 11 and 13 is reduced to be narrow, and the square-wave pulse power shown in FIG. 4 or 5 by which an amplitude of several times higher than the conventional DC voltage can be instantaneously supplied, is applied thereto, thereby increasing powerful and effective electrolysis. Therefore, the overall power consumption becomes, on the average, lower than in the case of applying the DC power, while enhancing the efficiency. Also, the electrodes 11 and 13 may be sharply formed or may be formed of a small-sized mesh, fine-wire or thin-strip type. Then, if the square-wave pulse power shown in FIG. 4 or 5 is applied thereto, more effective discharge and electrolysis, as defined as formulas 3 and 4, are generated, thereby further improving the electrolysis efficiency.

In the case of a rectified voltage P_c, P_c=V-I t with ripples, and in the case of a pulse power Pp, as shown in FIG. 4, Pp= Vp • Ip -tp. Here, tp,= t_on+ t_orr where tp is a one- period operation time of a pulse voltage, t_on is an operation (on) time of a pulse power and tj_ff is a non-operation (off) time of a pulse power.

In the case of the rectified voltage P_c, the operation time t is fixed and only the applied voltage V is varied so that the applied current I is concurrently dependent thereon. However, in the case of the pulse power Pp, the pulse voltage Vp and the pulse current Ip are maximally set to about two times of N and I of DC power, respectively, and the one- period operation time of a pulse voltage, i.e., tp, is appropriately varied. As a result, it can be achieved to obtain high temporary power and easily vary applied power according to the operation time of a pulse voltage, i.e., Therefore, the concentration of the produced electrolytic water can be arbitrarily controlled. In order to generate the effective waveform of the pulse voltage N_p, an electronic circuit shown in FIG. 7 can be used. Then, an alternate-current (ac) power is converted into an appropriate voltage using a low-voltage transformer (LT), rectified by a rectifier R and then smoothed by a smoothing capacitor C_f. The DC voltage is converted to the pulse voltage by a semiconductor switching power control element such as an insulator gate bipolar transistor (IGBT) or a general transistor, triggered by a trigger circuit (not shown) capable of triggering the same, in an appropriate time period t_p, ton or t_0ff, thereby producing the square-wave pulse voltage V_p shown in FIG. 4. Here, if the smoothing capacitor C_f that is large in size and expensive, is removed, the waveform of the pulse voltage N_pac shown in FIG. 5 is generated. These waveforms of the voltages can be used as the power source of the electrolytic water producing apparatus (II) according to the present invention.

Referring back to FIG. 6, the electrolytic water producing apparatus (III) according to another embodiment of the present invention requires three kinds of pulse voltages, No,

V_PA and N_PB. The pulse voltages, VQ, V_PA and V_PB have waveform diagrams shown in

FIG. 8. However, in order to attain more effective high- voltage discharge and electrolysis, the pulse voltages, No, V_PA and V_PB are alternately applied to the apparatus, as shown in FIG. 9. Alternatively, as shown in FIG. 10, while the voltage V_G is continuously applied, the voltages V_PA and V_PB are alternately applied by sequence control.

FIG. 11 shows an example of a pulse power generating circuit for the voltages, V_G, Vp_A and V_PB, which operates in the same principle as that shown in FIG. 7, except that a single low-voltage transformer (LT) is used and three pulse power generating circuits are installed in series, thereby sequence-controlling a trigger circuit (T) to generate pulse voltages shown in FIGs. 8, 9 and 10.

Also, according to the present invention, the power of the electrolytic water can be easily and effectively changed by appropriately controlling signals of the trigger circuit T to adjust the widths of waveforms of the pulse power voltages, that is, a duty rate of a waveform; a ratio of t_on to t_p in Expression t_p = t_on + t_off.

Here, the voltage V_G applied to inner electrodes 11 and 13 and the voltage V_PA or V_PB applied between outer electrodes 21 and 23 and the sizes of the electrodes 11, 13, 21 and 23 and electrode distances D and spacing d may be appropriately set, according to the wanted amount and concentration of produced electrolytic water,. The amplitudes of the voltages V_G, V_PA and V_PB are generally in the range of 20 to 1000 V, and may be increased or decreased for specific purposes. In other words, in the case of a high-purity deionized water, a higher voltage may be needed. In the case of a very small-sized apparatus, a lower voltage may be enough.

Although FIGs. 8 and 10 show square- wave pulse voltages by way of example, pulses generated in practical semiconductor power generating circuits have waveforms exhibiting damping oscillation, exponential rising or falling and over- and/or under-shoots. The duty rate of pulses may optimally vary according to the configuration and size of electrodes, and the amount of produced electrolytic water. Experimental results showed that the effective ranges of t_on and t_off were 10^"2 to 10⁴ seconds and 10^"4 to 10² seconds, respectively. However, the effective range of the duty rate may be varied, according to necessity and purpose.

Now, determination of electrode materials will be described.

The conventional electrolytic water producing apparatus (I) uses ferrite or Ti plated with Pt as a material of an anode 3. Thus, when a large amount of current is supplied, the electrode material may be precipitated in water to then be consumed in accordance with Faraday's Law, which results in reduction in the life time of the anode 3.

This problem can be overcome by using a Pt alloy, e.g., an alloy of Pt and Pd, produced in an appropriate mixture ratio (preferably in the range of 0.05 to 30 wt %, and more preferably in the range of 0.5 to 8 wt %). In this case, even if a voltage higher than 100 V, comparably to 20 V in the case of the conventional electrolytic water producing apparatus (I), is applied to the electrolytic water producing apparatus, the precipitation of the electrode material is considerably reduced. As a result, it can be achieved to prolong the life time of the electrode by over 4,000 hours, which was experimentally verified.

Therefore, in the case of the anode 13 in which ions and strong oxidants are directly produced and the outer anode 23, an alloy of Pt and Pd or a material coated with Pt or Pt alloy is advantageously used as the electrode material. However, in a small-sized electrolytic water producing apparatus whose fabrication cost is low and the life of which is not necessarily long, cheap SUS or any other kind of metal or alloy can be used as the materials of the anodes 13 and 23. In this case, the anodes 13 and 23 must be often replaced with new ones. However, in the case of cathodes 11 and 21, a material such as stainless steel may be used.

Meanwhile, in the case where pulse voltages are applied to the electrodes, in order to reduce the consumption of the electrode material due to its precipitation, a ferroelectric material having a very high specific dielectric constant (ε_r) may be coated on a metal electrode. Since the current is directly proportional to the portion of DC current (I), the consumption of the electrode material can be reduced by markedly reducing the portion of DC current (I). This effect becomes more evident at a relatively high frequency in which the duty rate of pulse voltages is low. As the specific dielectric constant of a ferroelectric material is much higher than that of water, that is, ε_r = 80, and a thinner ferroelectrics layer coated electrode and an electrode with enlarged surface act effectively on generation of a discharge and electrolysis. Further, the electrolysis can be facilitated by partially or entirely embedding an electrical insulation such as a ferroelectric pellet or bead between inner/outer electrodes.

Next, the controlling the characteristics and additives of the electrolytic water producing apparatus according to the present invention will be described. If the electrolytic water producing apparatus (III) according to the present invention is driven by applying a pulse power having an appropriate amplitude, shown in FIG. 8, 9 or 10, the electrolytic water is output from an anode outlet passage 18 in the area B, and some of the fed water is output from a cathode outlet passage 16 in the area A. Since the cathode 11 and the anode 13 are of a mesh type and the water flow width D is wider than the narrow electrode spacing d, a strong electric field (E=Vo/d) is produced in the inner anode water area Bp and the inner cathode water areas Ap, so that a powerful partial electric discharge and electrolysis occur in the cathode 11 and the anode 13. Thus, a powerful electrophysicohemical reaction is taken place to arouse electrolysis, which can be represented by the following Formulas 5 and 6, thereby effectively generating ozone (O₃), oxygen (O ) and oxygen atom (O) and secondarily generating strong oxidants such as hydroperoxide (H₂O ). [Formula 5]

6 H₂O → 6H₂ + O₂ + O₃ +O [Formula 6]

H₂O + O → H₂O₂ Here, negative ions contained in water, such as CL, SiO ^~ or SiO₃ ^~, migrate from the inner cathode water area Ap to the inner anode water area Bp by the force of Coulomb attraction. Likewise, positive ions contained in water, such as Ca^"1-1", Fe^""^", Mg^"1"4" and Cu^1"1", migrate from the inner anode water area Bp to the inner cathode water area Ap. Thus, separation and precipitation of ions also occurs. If appropriate voltages are applied to the outer cathode 21 and the outer anode 23, the ions of the inner cathode water area Ap and the inner anode water area Bp are migrated out to the cathode water area A and the anode water area B, respectively, to then be drained away through the cathode outlet passage 16 and the anode outlet passage 18.

Therefore, the anode electrolytic water produced at the anode outlet passage 18 is acidic water abundantly containing oxidants including a large amount of O₃ and negative ions, and a small amount of O , O or H O , and the cathode electrolytic water produced at the cathode outlet passage 16 is alkaline water containing a large amount of positive mineral ions.

The amount and concentration of the oxidants and ions contained in the produced electrolytic water can be easily controlled by manually or automatically varying the duty and/or amplitudes of applied pulse voltages V_G, V_PA and V_PB. Also, the amount and concentration of the ions and oxidants contained in the produced electrolytic water can be easily changed by appropriately varying the sizes of the electrodes 11, 13, 21 and 23, the electrode spacing d, the water flow width D and/or the fed water flow rate. Furthermore, the concentration of strong oxidants and ions can be further increased in the case where a Cl^~ containing water or a chemical capable of generating Cl^~, e.g., tap water, NaCl and/or KC1, is present in the fed water, as defined as: [Formula 7]

In other words, NaCl and/or KC1 present in water becomes weak in its ionic bonding force, that is, 1/80 times in water. Thus, even at a low voltage, NaCl and/or KC1 are easily dissolved into Na⁺ or K⁺ and Cl^~ so that Na⁺ or K⁺ ions move to the cathodes 1 1 and 21 and Cl^" ions move the anodes 13 and 23, thereby greatly increasing the amount of the ion concentration. In this case, Cl^" ions are abundantly contained in the anode water area B and the inner anode water area Bp. Also, as defined in Formula 8, OH and Cl produced by electrolysis of H O are bonded to each other to produce an oxidant such as HCIO defined in Formula 10, thereby containing abundantly HCIO and a small amount of O , O₃, H₂O₂ or O in the anode water area B. [Formula 8] H₂O → OH + H ...(1)

[Formula 9]

OH + Cl → HCIO ...(2)

If a powerful oxidant such as HCIO is abundantly contained in the acidic or alkaline water, the sterilizing power lasts about 6 hours. However, if a powerful oxidant such as O₃ is abundantly contained in the acidic or alkaline water, the sterilizing power lasts only 15 minutes or so. Thus, the produced electrolytic water can be widely used in various fields according to its purpose of use. In other words, the electrolytic water containing a large amount of O₃ is mainly used as a rinsing or disinfectant solution of food. Also, the electrolytic water containing a large amount of HCIO is mainly used as a substitute for agricultural chemicals.

The water supplied through a water supply channel may take the form of tap (service) water or underground water. However, according to necessity and purpose of use, a variety of aqueous solutions such as distilled water or a reagent dissolved solution may be used. Also, additives, such as NaCl and/or KC1, mixed with the aqueous solution or water may differ according to the kinds, desired ion concentrations or application conditions. Experimental results showed that it is effective and economical to add an additive to the aqueous solution or water in a mixing ratio of 0.01 to 1 % by weight.

According to the conventional electrolytic water producing apparatus, acidic water having a pH value of 4 to 6 and alkaline water having a pH value of 8 to 10 are produced in the anode outlet passage and the cathode outlet passage, respectively. Mild alkaline water is mainly used for drinking purpose.

Recently, there has been developed a high-concentration acidic electrolytic water producing apparatus. According to this apparatus, an anode formed of a flat-type electrode made by coating or plating Pt on Ti and facing electrodes are installed in opposite sides of a separating membrane, i.e., ion exchange resin. Also, a DC voltage of 10 to 20 V is applied to both electrodes, thereby producing electrolysis, which occurs at a voltage higher than or equal to 3 V, like in the conventional electrolytic water producing apparatus. Here, a voltage greater than 20 V may sharply shorten the life time of an anode electrode. Then, high-concentration ionic water having pH values of 2 to 4 and 10 to 12 is produced at an anode outlet passage and a cathode outlet passage, respectively. Specifically, research and development of the apparatuses for producing acidic water having a pH value of 2 to 4 are under way for sterilizing purpose. However, it is quite difficult to control the pH of produced electrolytic water and the quality of strong oxidants. Also, since the strong oxidants mainly include HCIO, there are limitations in various practical applications.

According to another aspect of the present invention, there is provided an apparatus for producing a functional neutral water containing much oxidants as well as weak alkaline water and weak acidic water, which will now be described in more detail.

In general, known electrolysis apparatuses for generating electrolytic water cannot produce neutral water having a pH value of 6 to 8. In other words, the conventional electrolytic water producing apparatus (I) produces electrolytic water having a pH value of 4 to 6 and the electrolytic water producing apparatus (III) according to the present invention produces an electrolytic water having a pH value of 2 to 4.

To solve this problem, the electrolytic water producing apparatus (III) according to the present invention may be further provided with a means (M) for mixing and neutralizing the cathode water (strong alkaline water) W_A of the area A and the anode water (strong acidic water) W_B of the area B in the cathode outlet passage 16 and the anode outlet passage 18. As a result, it can be achieved to produce the weak alkaline and acidic water and the neutral water Wc having a pH value of 7, which is the same level of pH of the water initially fed from the water inlet channel 4.

As described above, in the jieutral water having a pH value of 7, a large amount of strong oxidants such as O₃ and O₂ and a small amount of HCIO, H O₂ and O generated by discharge and electrolysis are still contained. Although slightly reduced as the mixing proceeds, as shown in FIG. 15, a considerable amount of the oxidants still remain in the neutral water, thereby conferring to the neutral water sterilizing power strong enough to disinfect 99.9% of bacteria and virus within 10 seconds in a concentration of 0.3 ppm and up. Thus, the functional neutral water can be advantageously used in various fields including water sterilizing for use in home, business places such as restaurants, hotels, hairdressers' shops, hospitals or schools, industrial organizations or livestock.

In this case, the means M for generating the functional neutral water may be implemented just by installing a mixing tank in the electrolytic water producing apparatus (III) or (IV) according to the present invention, shown in FIG. 6 or 12. However, according to the necessity and purpose of use, appropriate methods and devices may be employed. Further, the functional neutral water Wc can be made weak acidic water or weak alkaline water by arbitrarily controlling the mixture ratio or pH value of the strong alkaline water W_A and the strong acidic water W_B .

The thus-obtained functional neutral water Wc can also be attained by removing the separating membrane 12 from the electrolytic water producing apparatus (II) or (III) according to the present invention, and combining the outlet passages 16 and 18 into one. In this case, the ion rich water can not be obtained but the electrolysis efficiency can be greatly enhanced, and further more several problems associated with the separating membrane 12, that is, the shortened life of the apparatus due to the membrane, clogging of the membrane, increased power consumption due to the high electrical resistance of the membrane, and the cost, can be greatly improved.

Therefore, the electrolytic water producing apparatuses (II), (III) and (IN) according to the present invention can be very advantageously applied in various application fields and for various purposes. Also, in view of characteristics of the produced electrolytic water, it is possible to obtain higher-concentration electrolytic water containing a large amount of minerals, and water having high-concentration powerful oxidants dissolved therein. Here, the water may contain a large amount of HCIO and a small amount of H₂O , O and O , or may contain a large amount of O₃ and a small amount of HCIO, H₂O , O and O . Further, the ion concentration of the produced electrolytic water can be controlled to an arbitrary level in the range of pH values of the strong acidic water and the strong alkaline water, that is, any pH values ranging between 2 and 12, even of pH 7.

Here, in the case where the strong oxidant HCIO is abundantly contained in the electrolytic water, the sterilizing power lasts long for about 6 hours. However, in the case where the strong oxidant O₃ is abundantly contained in the electrolytic water, the sterilizing power lasts relatively short for only about 15 minutes. Therefore, according to the necessity, the electrolytic water can be used in various ways to applications.

Industrial Applicability

As described above, according to the improved electrolytic water producing apparatus (III) of the present invention, when it is applied to the tap water, the electrolytic characteristics shown in FIG. 13 are exhibited. If a small amount salt, NaCl is mixed with the tap water fed, as shown in FIG. 14, the oxidant containing water whose oxidant concentration is very high is produced. As seen in both cases, the electrolytic water producing apparatus (III) according to the present invention can produce the electrolytic water having concentrations of 3 and 15 times higher than the concentration of the electrolytic water produced by the conventional electrolytic water producing apparatus (I). Also, as shown in FIG. 16, very powerful electrolytic water, that is, strong acidic water W_A having a pH value of 2 to 4 and strong acidic water W_B having a pH value of 10 to 12, and functional neutral water Wc can be separately obtained.

Since the-thus obtained electrolytic water contains strong oxidants, using the actions of powerful oxidation including sterilization, deodorization, decolorization and the like, the electrolytic water can be widely used in various fields, that is, sterilizing water, purification of drinking water, the processing, reservation and sterilization of meat and fish and food, bactericidal treatment of agricultural products, disposal of industrial waste water, disposal of ill-odored and harmful volatile organic chemicals (NOCs), substitutions of agricultural chemicals, sterilization in the course of preparing or processing pharmaceuticals and food, and rinsing and sterilization in the medical fields, such as doctor's hands and clothes to be disinfected, medical instruments and tools such as knives, scissors, stomach and vaginal endoscope, dental disinfectant and rinsing solution.

Also, a small amount of additives such as KC1 and/or NaCl initially induced to the fed tap water are decomposed or electrolyzed to then be removed by the high-voltage discharge, the problems caused by the additives, such as damage from the remained salt, can be avoided.

Further, the strong acidic water W_B can be used for extermination of fungi, moss, algae or vermin as well as bactericidal treatment. Thus, the strong acidic water W_B can be used for substitutes for agricultural chemicals, not causing secondary damages. Also, it can be applied in wider fields for multiple purposes: waste water treatment in stockbreeding, deodorization, medical applications such as dental disinfectant and rinsing systems, stomach or intestines or vaginal endoscope sterilization systems, or sterilization of hospital walls infected with bacteria. Meanwhile, the strong alkaline water W_A can be used for special purposes, that is, drinking water of people or livestock, or cultivation water for special plant, e.g., hydroponics or irrigation water. Also, the strong alkaline water W_A can be used for controlling a pH value, for the purpose of neutralization of unwanted acidic water, acidic soil or acidic cultivation water. Furthermore, the strong alkaline water W_A can be used for accelerating germination of seed and growth of plant seedlings.

In the electrolytic water producing apparatus (II) and (III) according to the present invention, as shown in FIGs. 13 and 14, a small amount of oxidants such as O₃, HCIO or H O are even contained in the strong alkaline water WA, and are further more applicable for multiple purposes.

Claims

What is claimed is:

1. An apparatus for producing powerful electrolytic water, comprising: a pair of plate anode and cathode installed in opposite side of a separating membrane to face parallel each other, each of the facing electrodes having slits or being formed of a fine-wire, thin-strip or mesh type, the anode being made of a platinum (Pt) alloy containing palladium (Pd), in an insulating case having water inlet and outlet channels; and a first means for applying a direct-current (DC) voltage or a pulse power voltage between the anode and the cathode.

2. The apparatus for producing powerful electrolytic water according to claim 1, wherein the facing electrodes and the separating membrane are cylindrically formed.

3. The apparatus for producing powerful electrolytic water according to one of claims 1 and 2, further comprising: outer electrodes additionally installed in the outer sides of the facing electrodes; and a second means for applying a voltage between the additionally installed electrodes and the facing electrodes.

4. The apparatus for producing powerful electrolytic water according to one of claims 1, 2 and 3, wherein each of said first and second voltage applying means comprises: means for applying a pulse voltage having a short voltage rising time between the anode and the cathode; and means for alternately applying the pulse voltage whose period is sequence- controlled.

5. The apparatus for producing powerful electrolytic water according to one of claims 1 , 2 and 3, wherein the facing electrodes are formed of an alloy of Pt and Pd, or the facing electrodes are coated with the alloy.

6. The apparatus for producing powerful electrolytic water according to one of claims 1, 2 and 3, wherein the facing electrodes are partially or entirely coated with a ferroelectric material, or a ferroelectric material is partially or entirely embedded between the facing electrodes and between the outer electrodes.

7. The apparatus for producing powerful electrolytic water according to one of claims 1 through 6, wherein the separating membrane installed between the facing electrodes is removed to allow a functional neutral water having strong oxidants contained therein to be drained out to the water outlet channel.

8. The apparatus for producing powerful electrolytic water according to one of claims 1 through 6, further comprising means for mixing strong alkaline water and strong acidic water drained out to the water outlet channel to produce the functional neutral water and controlling a pH value.