Abstract: An electrochemical system and method are disclosed for On Site Generation (OSG) of oxidants, such as free available chlorine, mixed oxidants and persulfate. Operation at high current density, using at least a diamond anode, provides for higher current efficiency, extended lifetime operation, and improved cost efficiency. High current density operation, in either a single pass or recycle mode, provides for rapid generation of oxidants, with high current efficiency, which potentially allows for more compact systems. Beneficially, operation in reverse polarity for a short cleaning cycle manages scaling, provides for improved efficiency and electrode lifetime and allows for use of impure feedstocks without requiring water softeners. Systems have application for generation of chlorine or other oxidants, including mixed oxidants providing high disinfection rate per unit of oxidant, e.g. for water treatment to remove microorganisms or for degradation of organics in industrial waste water.

Abstract: The invention relates to a method for producing an ammonium peroxydisulfate or alkali metal peroxydisulfate, to an undivided electrolytic cell which is composed of individual components, and to an electrolytic device composed of a plurality of said electrolytic cells.

Abstract: An electrolysis apparatus comprising: an electrolytic cell in which a sulfuric acid solution is fed and discharged; a conductive anode and cathode electrode of diamond composition; a feeding unit for feeding the sulfuric acid solution to the electrolytic cell; a power supply unit for applying a voltage between the anode and cathode electrodes; and a power control unit for controlling the power supply unit such that a forward voltage is applied between the anode and cathode during normal electrolysis with the polarity applied between the anode and cathode inverted under predetermined conditions during intervals between normal operation to dissolve precipitates of sulfur generated in the electrolytic cell for stabilizing the electrolysis operation.

Abstract: The present invention provides an electrically conductive diamond electrode comprising an electrically conductive substrate and an electrically conductive diamond layer coated on the surface of the electrically conductive substrate, featuring that: 1) the thickness of the electrically conductive diamond layer is 1˜25 ?m, 2) the potential window fulfills Equation (1) and 3) the ratio (A/B) of the diamond component A and the non-diamond component B by the Raman spectroscopic analysis fulfills Equation (2). 2.1V?potential window?3.5V??(1) 1.5<A/B?6.5??(2) A: Intensity at the wave number 1300 cm?1 by the Raman spectroscopic analysis B: Intensity at the wave number 1500 cm?1 by the Raman spectroscopic analysis.

Abstract: A sulfuric acid electrolyte is produced efficiently as a functional solution and persulfuric acid produced by electrolysis is supplied efficiently to a use side while suppressing self-decomposition thereof.

Abstract: A cleaning system includes: a sulfuric acid electrolytic portion configured to electrolyze a sulfuric acid solution to generate an oxidizing substance in an anode chamber, a concentrated sulfuric acid supply portion configured to supply a concentrated sulfuric acid solution to the anode chamber, and a cleaning treatment portion configured to carry out cleaning treatment of an object to be cleaned using an oxidizing solution comprising the oxidizing substance. The sulfuric acid electrolytic portion has an anode, a cathode, a diaphragm which is provided between the anode and the cathode, the anode chamber which is demarcated between the anode and the diaphragm and a cathode chamber which is demarcated between the cathode and the diaphragm.

Abstract: An apparatus for electrolyzing sulfuric acid, the apparatus comprising an electrolytic cell comprising a cathode chamber having a cathode and an anode chamber having an anode, the cathode chamber and the anode chamber being separated by a diaphragm, a sulfuric acid tank configured to store the sulfuric acid, a supply pipe connecting the sulfuric acid tank to an inlet port of the anode chamber, a connection pipe connecting an outlet port of the cathode chamber to the inlet port of the anode chamber, a first supply pump provided on the supply pipe and configured to supply the sulfuric acid from the sulfuric acid tank to the cathode chamber through the supply pipe, and a drain pipe connected to an outlet port of the anode chamber and configured to supply to a solution tank a solution containing an oxidizing agent generated by electrolysis in the anode chamber.

Abstract: Sulfuric acid electrolysis process wherein; a temperature of electrolyte containing sulfuric acid to be supplied to an anode compartment and a cathode compartment is controlled to 30 degree Celsius or more; a flow rate F1 (L/min.) of the electrolyte containing sulfuric acid to be supplied to said anode compartment is controlled to 1.5 times or more (F1/Fa?1.5) a flow rate Fa (L/min.) of gas formed on an anode side as calculated from Equation (1) shown below and a flow rate F2(L/min.) of said electrolyte containing sulfuric acid to be supplied to said cathode compartment is controlled to 1.5 times or more (F2/Fc?1.5) a flow rate Fe (L/min.) of gas formed on a cathode side as calculated from Equation (2) shown below. Fa=(I×S×R×T)/(4×Faraday constant)??Equation (1) Fe=(I×S×R×T)/(2×Faraday constant)??Equation (2) I: Electrolytic current (A) S: Time: 60 second (Fixed) R: Gas constant (0.082 1·atm/K/mol) K: Absolute temperature (273.

Abstract: In a sulfuric acid electrolytic cell to electrolyze sulfuric acid supplied to an anode compartment and a cathode compartment comprising a diaphragm, said anode compartment and said cathode compartment separated by said diaphragm, a cathode provided in said cathode compartment and a conductive diamond anode provided in said anode compartment, as said conductive diamond anode, a conductive diamond film is formed on the surface of said conductive substrate, the rear face of said conductive substrate is pasted, with conductive paste, on an current collector comprising a rigid body with size equal to, or larger than, said conductive substrate, an anode compartment frame constituting said anode compartment is contacted via gasket with the periphery on the side of the conductive diamond film of said diamond anode, said diaphragm is contacted with the front face of said anode compartment, further, with the front face of said diaphragm, the cathode compartment frame constituting said cathode compartment, a gasket, and

Abstract: A process for preparing or regenerating peroxodisulfuric acid and its salts by electrolysis of an aqueous solution containing sulfuric acid and/or metal sulfates at diamond-coated electrodes without addition of promoters is described, with bipolar silicon electrodes which are coated with diamond on one side and whose uncoated silicon rear side serves as cathode being used.

Abstract: A cleaning system includes: a sulfuric acid electrolytic portion configured to electrolyze a sulfuric acid solution to generate an oxidizing substance in an anode chamber, a concentrated sulfuric acid supply portion configured to supply a concentrated sulfuric acid solution to the anode chamber, and a cleaning treatment portion configured to carry out cleaning treatment of an object to be cleaned using an oxidizing solution comprising the oxidizing substance. The sulfuric acid electrolytic portion has an anode, a cathode, a diaphragm which is provided between the anode and the cathode, the anode chamber which is demarcated between the anode and the diaphragm and a cathode chamber which is demarcated between the cathode and the diaphragm.

Abstract: A process for the electrochemical production of peroxo-disulfuric acid and peroxo-disulfates is provided. In the process, an anode having a partially pre-polarized electrode which has been provided with a doped diamond layer is used.

Abstract: The invention relates to a process for the production of a peroxodisulfate, such as ammonium-, sodium- and potassium peroxodisulfate by anodic oxidation of an electrolyte containing a sulfate and/or hydrogen sulfate. The disadvantages of the conventional platinum anodes used for this hitherto can be avoided by using as the anode a diamond film mounted on a conductive carrier and made conductive by doping with a tri- or pentavalent element and by not adding a promoter to the anolyte.

Abstract: A process for the simultaneous preparation of sodium peroxodisulfate and sodium dithionite in an electrolysis cell divided into two by a cation exchanger membrane, wherein sodium dithionite is produced at the cathode and sodium peroxodisulfate is produced at the anode.

Abstract: An electrode (10, 112) containing platinum has its surface modified with sulfur, tellurium, or selenium, or compounds thereof, which renders the surface highly selective for the conversion of oxygen to hydrogen peroxide. The high selectivity of the electrode, and its ability to function in acidic electrolytes make it suitable to a variety of electrochemical processes. In a preferred embodiment, an oxygen concentration device (A) incorporating the electrode as a cathode (10) also includes an anode (12) and a selective membrane (14), formed from a solid polymer electrolyte material, between the anode and the cathode. An oxygen-containing atmosphere is brought into contact with the cathode where it is converted to hydrogen peroxide. The hydrogen peroxide passes through the membrane to the anode where it is reconverted to purified oxygen.

Abstract: The invention relates to a process for the production of a peroxodisulfate, such as ammonium-, sodium- and potassium peroxodisulfate by anodic oxidation of an electrolyte containing a sulfate and/or hydrogen sulfate. The disadvantages of the conventional platinum anodes used for this hitherto can be avoided by using as the anode a diamond film mounted on a conductive carrier and made conductive by doping with a tri- or pentavalent element and by not adding a promoter to the anolyte.

Abstract: There are disclosed (1) a process for producing ammonium persulfate which comprises electrolyzing, as the starting raw material for an anode, an aqueous solution containing ammonium sulfate wherein ammonium ions are present in an amount of at least one equivalent based on sulfate ions; (2) a process for producing sodium persulfate which comprises the step (A) of electrolyzing an aqueous solution containing ammonium sulfate at an anode, the step (B) of producing sodium persulfate, the step (C) of crystallizing and separating the sodium persulfate and the step (D) of recycling the liquid produced at a cathode together with ammonia for use as the starting raw material for an anode in the step (A); and (3) a process for producing potassium persulfate which comprises the step (A′) of electrolyzing an aqueous solution containing ammonium sulfate at an anode; and the step (B′) of producing potassium persulfate.