Abstract: A method is disclosed, which is capable of subjecting microorganisms to sterilizing or bacteriostatic treatment with good efficiency as compared with the conventional sterilizing or bacteriostatic method using a noble metal electrode. Microorganism-containing water to be treated is electrochemically treated using an anode having conductive diamond to bring the microorganism into contact with the anode, thereby undergoing sterilization. Since the conductive diamond has a high oxidation potential as compared with other electrode substances, direct oxidation reaction due to contact between a microorganism in water to be treated, such as Legionella bacteria, and the anode surface occurs strongly as compared with other electrodes, thereby enabling effective sterilization. The conductive diamond has a high ability to generate ozone and has an excellent formation efficiency with respect to the generation of hydrogen peroxide and radicals. Accordingly, an indirect sterilizing effect can also be expected.

Abstract: An electrolytic treatment apparatus and method by simply subjecting a chemical plating waste liquor containing phosphorus components and organic compounds to electrolytic treatment, thereby reducing the amount of impurities in the waste liquor to a level at which the waste liquor can be discharged. The chemical plating waste liquor containing hypophosphorous acid, phosphorous acid and organic compounds is subjected to electrolytic treatment in an electrolytic cell having a conductive diamond electrode as an anode. The conductive diamond electrode oxidizes or oxidatively decomposes the phosphorus components and organic compounds in the waste liquor substantially simultaneously, thereby reducing the amount of impurities to a level at which the waste liquor can be discharged.

Abstract: A method is disclosed, which is capable of subjecting microorganisms to sterilizing or bacteriostatic treatment with good efficiency as compared with the conventional sterilizing or bacteriostatic method using a noble metal electrode. Microorganism-containing water to be treated is electrochemically treated using an anode having conductive diamond to bring the microorganism into contact with the anode, thereby undergoing sterilization. Since the conductive diamond has a high oxidation potential as compared with other electrode substances, direct oxidation reaction due to contact between a microorganism in water to be treated, such as Legionella bacteria, and the anode surface occurs strongly as compared with other electrodes, thereby enabling effective sterilization. The conductive diamond has a high ability to generate ozone and has an excellent formation efficiency with respect to the generation of hydrogen peroxide and radicals. Accordingly, an indirect sterilizing effect can also be expected.

Abstract: An electrolytic cell and method of electrolysis for producing hydrogen peroxide at a moderate current density while preventing metal deposition on the cathode surface. A feed water from which multivalent metal ions have been removed and in which a salt of a univalent metal, e.g., sodium sulfate, has been dissolved in a given concentration is prepared with an apparatus for removing multivalent metal ions and dissolving a salt in low concentration. The feed water is supplied to an electrolytic cell. Even when electrolysis is continued, almost no deposition of a hydroxide or carbonate occurs on the cathode because multivalent metal ions are not present in the electrolytic solution. Due to the dissolved salt, a sufficient current density is secured to prevent an excessive load from being imposed on the electrodes, etc. Thus, stable production of hydrogen peroxide is possible over a long period of time.

Abstract: An oxoacid or oxoacid salt is added from an oxoacid addition device to a liquid to be treated which contains organic compound, and a peracid is electrochemically synthesized therefrom in an electrolytic cell. The organic compound in the liquid is thus oxidatively decomposed with the peracid. The organic compound is converted to carbon dioxide and water, yielding almost no solid matter.

Abstract: A method and apparatus for water treatment. The method comprises supplying an oxygen-containing gas to cathode 6 to yield hydrogen peroxide, supplying an inorganic acid to anode 5 through an acid solution addition opening 4 to yield an oxidation product, e.g., hypochlorous acid, and using both the hydrogen peroxide and oxidation product thus generated to treat a liquid to be treated. The atmosphere around the cathode surface is kept neutral to acidic due to the acidity of the coexisting oxidation product to thereby inhibit the deposition of metal hydroxides.

Abstract: An electrolytic cell and method of electrolysis for producing hydrogen peroxide at a moderate current density while preventing metal deposition on the cathode surface. A feed water from which multivalent metal ions have been removed and in which a salt of a univalent metal, e.g., sodium sulfate, has been dissolved in a given concentration is prepared with an apparatus for removing multivalent metal ions and dissolving a salt in low concentration. The feed water is supplied to an electrolytic cell. Even when electrolysis is continued, almost no deposition of a hydroxide or carbonate occurs on the cathode because multivalent metal ions are not present in the electrolytic solution. Due to the dissolved salt, a sufficient current density is secured to prevent an excessive load from being imposed on the electrodes, etc. Thus, stable production of hydrogen peroxide is possible over a long period of time.

Abstract: An electrochemical treating apparatus comprising an electrolytic cell comprising an anode and a cathode spaced apart from the anode, the anode including an electrode material made of diamond and the cathode including an electrode material made of diamond. Also disclosed is an electrochemical treating method for electrochemically decomposing a substance contained in a gas or solution, which comprises introducing a gas or solution containing a substance to be treated into the electrolytic cell, passing an electric current through the electrolytic cell, and recovering a treated gas or solution. In a preferred embodiment, the electrolytic cell comprises an anode including an electrode material made of diamond, a cathode including an electrode material made of diamond and an ion exchange resin or an ion exchange membrane as an electrolyte disposed between the anode and the cathode.

Abstract: A process and apparatuses for producing hydrogen peroxide which provides good current density and production efficiency from an electrolytic liquid having an exceedingly low conductivity, such as ultrapure water. An electrolytic cell main body containing an anode 5 and a cathode 6 which are electrically connected to each other via ion-exchange resin particles 9 is used to conduct electrolysis while maintaining the electrical connection. High-purity, high-concentration hydrogen peroxide is produced at a high current efficiency even when the electrolytic liquid has an exceedingly low conductivity.

Abstract: An electrolytic cell for producing a brine containing hydrogen peroxide is disclosed. Units for hydrogen peroxide production 3 and units for water electrolysis 2 are alternately arranged in the same electrolytic cell 1. Electrolysis is conducted while supplying hydrogen gas and oxygen gas generating in the respective water electrolysis units to a gas diffusion anode 11 and a gas diffusion cathode 13 of each unit for hydrogen peroxide production, to thereby obtain a brine containing hydrogen peroxide in a high concentration. Furthermore, because the anode of the hydrogen peroxide production units is a hydrogen gas diffusion anode having a reduced oxidizing ability, halogen ions contained in the seawater do not yield harmful halogenated organic substances.

Abstract: An electrolytic cell for producing an alkali hydroxide using a gas diffusion cathode. A moistened oxygen-containing gas is uniformly supplied to the surface of the gas diffusion cathode by means of a gas distributing mechanism, such as at least one gas diffuser pipe having a plurality of openings facing the cathode surface.

Abstract: An on-site process and apparatus for producing hydrogen peroxide at a high efficiency substantially from brine and oxygen-containing gas alone as raw materials while removing alkaline earth metals. Sea water concentrated by an electrodialytic apparatus 2 or the like as a raw material is supplied to an impurity removing apparatus 10 where caustic soda produced in an acid-alkali producing apparatus 11 at a subsequent stage and/or carbon dioxide gas is added to remove alkaline earth metals contained in sea water in the form of a hydroxide or carbonate precipitate. Separately, the acid-alkali producing apparatus 11 performs a salt separating operation to produce caustic soda which is then supplied to a hydrogen peroxide generator 28 to produce an alkaline aqueous solution of hydrogen peroxide.

Abstract: A gas-diffusion electrode (cathode) in contact with an ion-exchange membrane partitioning an electrolytic cell for producing caustic soda, etc., by electrolysis into an anode chamber and a cathode chamber (gas chamber). The gas-diffusion electrode is divided into plural electrode members in the horizontal direction with an interval provided between adjacent electrode members. Electrolyte guide plates may be disposed on the electrode members or between the adjacent electrode members. An aqueous caustic soda solution formed in the electrolysis smoothly is removed from the gas-diffusion electrode without clogging the electrode.

Abstract: An electrode for electrolysis comprising an electrode base material and an electrode substance having an electrically conductive diamond structure covering the surface of the electrode base material. The electrode substance having an electrically conductive diamond structure may be a diamond containing an impurity selected from boron, phosphorus and graphite. Alternatively, the electrode substance having an electrically conductive diamond structure may comprise a composite of a diamond and an electrically conductive material. In a preferred embodiment, the electrode further comprises an interlayer comprising at least one of the carbide of a valve metal and silicon carbide disposed between the electrode base material and the electrode substance having an electrically conductive diamond structure. Also disclosed is an electrolytic cell having two chambers including an anode chamber and a cathode chamber partitioned by an ion-exchange membrane.

Abstract: A gas-diffusion cathode disposed in contact with an ion-exchange membrane partitioning an electrolytic cell into an anode chamber and a cathode chamber, wherein at least one guide piece is disposed in the gas-diffusion cathode and a salt water electrolytic cell using the above-described gas-diffusion cathode. By using the above-described gas-diffusion cathode for salt water electrolysis, an aqueous caustic alkali solution formed descending in the direction of gravity in the cathode changes direction of movement by contact with a guide piece, whereby the decreased electrode performance resulting from the hindrance of the supply of raw material gas and the discharge of the gas formed caused by the retention of the descending caustic alkali solution is prevented and a large-sized electrolytic cell can be used without problems generally encountered in conventional electrolytic systems.

Abstract: A liquid-permeable gas-diffusion cathode adapted for caustic soda electrolysis in contact with an ion-exchange membrane partitioning an electrolytic cell into an anode chamber and a cathode gas chamber. Plural horizontal concave grooves and/or convex portions are provided in an interval with one another on the surface of the gas-diffusion cathode facing the gas chamber. Plural vertical concave grooves may also be provided in an interval on the surface of the cathode crossing the horizontal grooves and/or convex portions. Aqueous caustic soda solution thus formed flows downward along the grooves, etc., without covering other portions of the cathode surface, and is easily released therefrom without clogging perforations in the gas-diffusion layer of the cathode.

Abstract: A process for producing a gas electrode is disclosed, comprising sintering a mixture of carbon powder and a fluorine resin powder to form a sheet as a gas electrode base, coating one side of the sheet base with an organic solution prepared by dissolving a platinum group metal salt in an organic solvent capable of forming an organic complex with the metal salt, drying the coating layer, and calcining the coating layer at a temperature of from 250.degree. to 380.degree. C. in an inert atmosphere to reduce the platinum group metal oxide thereby forming a catalyst layer on the sheet base. Reduction (calcination) of the platinum group metal salt can be effected without using dangerous hydrogen gas and without being accompanied by decomposition of the fluorine resin and provides a uniform catalyst layer comprising fine platinum particles having a large surface area with a minimized thickness.

Abstract: A gas diffusion electrode comprising a water permeable gas diffusion and reaction layer and a porous and electrically conductive electrode current collector having a water repellency bonded to the gas diffusion and reaction layer.

Abstract: The electrolytic cell 1 for producing alkali hydroxide or hydrogen peroxide is divided into the anode compartment 3 and the cathode compartment 4 by the cation exchange membrane 2. The cathode compartment 4 is further divided by the anion exchange membrane 6 into the solution compartment 7 containing a concentrated aqueous solution of alkali hydroxide and the gas compartment accommodating the gas cathode 8. The anion exchange membrane 6 prevents the gas cathode 8 from coming into direct or indirect contact with the aqueous solution of alkali hydroxide. This leads to the extended life of the gas cathode. The above-mentioned arrangement is effective in large-sized electrolytic cells. Thus, the present invention can be applied to industrial electrolysis which has never been achieved with the conventional gas electrode.