Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1996-12-27
1999-02-02
Valentine, Donald R.
Chemistry: electrical and wave energy
Apparatus
Electrolytic
204279, C25B 900
Patent
active
058659668
DESCRIPTION:
BRIEF SUMMARY
This is a National Stage Application of PCT/JP95/01311, filed Jun. 30, 1995.
TECHNICAL FIELD
The present invention relates to an electrolytic cell for electrolyzing water to electrochemically produce alkaline and/or acidic water. More specifically, the present invention is concerned with a non-membrane type electrolytic cell which is capable of effectively preventing scale such as calcium carbonate from precipitating in the water path.
BACKGROUND ART
It is believed that hydroxyl ion (OH.sup.-) enriched alkaline water, which is often incorrectly referred-to as "alkaline ion water", is useful in health maintenance when served as potable water as well as in accentuating taste when used in cooking or for the preparation of beverages such as tea and coffee. Similarly, hydrogen ion (H.sup.+) enriched acidic water is known as being suitable for boiling noodles and washing the face. More importantly, highly acidic water which is obtained by electrolysis of tap water containing sodium chloride or an aqueous solution of sodium chloride and which therefore contains effective chlorine (hypochlorous acid or chlorine gas) has been noted as having a strong germicidal effect.
To produce alkaline and/or acidic water, an apparatus for electrolyzing water has been used hitherto which is often incorrectly referred-to in the art as an "ion-water generator". This apparatus, designed to subject water to electrolysis, includes an electrolytic cell having an anode and a cathode. As a direct electric potential is applied between the electrodes, the hydroxyl ions OH.sup.- being present in water due to electrolytic dissociation of water molecules will donate electrons to the anode at the anode-water interface and are thereby oxidized to form oxygen gas which is then removed away from the system. As a result, the H.sup.+ concentration is enhanced at the anode-water interface so that H.sup.+ enriched acidic water results at the anode-water interface. At the cathode-water interface, on the other hand, H.sup.+ accepts electrons from the cathode and is reduced to hydrogen to form hydrogen gas which is similarly eliminated from the system. As a result, the OH.sup.- concentration is increased whereby OH.sup.- enriched alkaline water is generated on the cathode side. When an aqueous solution of sodium chloride is subjected to electrolysis, chlorine gas is generated at the anode and is dissolved into water to form hypochlorous acid.
To preclude alkaline water and acidic water once generated by electrolysis from being mixed with each other and to remove them separately, the conventional electrolytic cells are typically provided with a water-impermeable, electrically conducting but ion-permeable membrane 3 arranged between an anode plate 1 and a cathode plate 2 as schematically shown in FIG. 1, the electrolytic chamber being divided by the membrane into a flowpath 4 for alkaline water and a flowpath 5 for acidic water. The electrolytic cell of this type will be referred-to hereinafter as the "membrane-type" electrolytic cell.
As the electrolytic cell is operated, precipitation of scale 6 comprised of calcium carbonate, calcium hydroxide, magnesium hydroxide and the like takes place in the flowpath for alkaline water. Referring to FIG. 2 wherein the apparent solubility of calcium carbonate versus pH is shown, the mechanism of scale precipitation will be described with reference to calcium hydroxide by way of an example. It will be noted from the graph that under acidic conditions, calcium carbonate is dissolved into water in the form of calcium ions. However, as the pH exceeds 8, the solubility rapidly drops so that calcium carbonate settles in the flowpath for alkaline water. The calcium ions are moved toward the cathode plate under the action of the electric field between the electrodes whereby the calcium ion concentration in the flowpath for alkaline water is increased. This in turn promotes precipitation of calcium carbonate.
In the electrolytic cell of the membrane type, the scale tends to precipitate predominantly on the membrane 3
REFERENCES:
patent: 4194961 (1980-03-01), Williams
patent: 4323444 (1982-04-01), Kawamura et al.
patent: 5041202 (1991-08-01), Friconneau et al.
patent: 5254234 (1993-10-01), Cortes et al.
Ando Shigeru
Miyahara Hidetaka
Nishi Tomohiro
Takamatsu Hiroshi
Watanabe Kazuyuki
Toto Ltd.
Valentine Donald R.
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