Abstract: The invention relates to a process of producing chlorine dioxide comprising the steps: Providing a reactor with an aqueous acidic reaction medium containing alkali metal chlorate and sulfate; reducing chlorate ions in said reaction medium to form chlorine dioxide; maintaining the reaction medium at subatmospheric pressure sufficient to evaporate water and precipitate alkali metal sulfate; withdrawing chlorine dioxide and evaporated water from the reactor; withdrawing reaction medium containing solid alkali metal sulfate from the reactor and separating the solid material from said reaction medium; transferring reaction medium substantially free from solid alkali metal sulfate to an electrochemical cell in which the acidity of said reaction medium is increased and the content of alkali metal ions is decreased; recycling electrochemically acidified reaction medium to the reactor for producing chlorine dioxide; and adding make up alkali metal chlorate and sulfuric acid.

Abstract: A process for production of chlorine dioxide which is substantially free of by product chlorine. Chlorine-dioxide is produced from an alkali metal chlorate, a mineral acid and a reducing agent such as methanol in a reaction medium maintained at an acid normality of less than 9 and with a high chlorate molarity. The process is carried out in the substantial absence of additional chloride ion being fed to the process. It has been found that increasing the chlorate concentration at a given acid normality reduces the amount of chloride in the reaction medium thus reducing the amount of chlorine by-product. The process is carried out in a vessel operated under subatmospheric pressure, whereby water is evaporated and withdrawn together with chlorine dioxide and the alkali metal salt of the mineral acid is crystallized within the reaction vessel and withdrawn therefrom.

Abstract: A method of disinfection of foodstuff involving the use of hydrogen peroxide in combination with anti-microbial agents selected from the group consisting of benzoic acid, and phosphoric acid, at low concentration, to substantially reduce the microbial count in food-related application.

Abstract: Sulphide-containing white liquor is treated in a continuously operating electrolytic cell having separate anode and cathode compartments separated by a partially permeable barrier. White liquor is introduced into the anode compartment of the cell, and an aqueous solution of alkali metal hydroxide is introduced into the cathode compartment of the cell so that sulphide is oxidized in the anode compartment, while at the same time alkali metal cations are transported through the barrier into the cathode compartment, where water reacts to form hydroxide ions. An electrolytic cell suited for implementing the method is also disclosed.

Abstract: Disclosed is a process of producing chlorine dioxide having the steps of providing a reactor with an aqueous acidic reaction medium containing alkali metal chlorate and phosphate; reducing chlorate ions in the reaction medium to form chlorine dioxide; withdrawing chlorine dioxide gas from the reaction medium; withdrawing reaction medium from the reactor and transferring it to an electrochemical cell; treating the reaction medium electrochemically to increase the acidity and decrease the content of alkali metal ions; recycling the acidified reaction medium to the reactor; and adding make up alkali metal chlorate to the reaction medium before or after the electrochemical cell.

Abstract: The invention relates to a process of producing chlorine dioxide using, in a first alternative atmospheric pressure and hydrogen peroxide in the reaction medium optionally with an electrolytic cell. In a second alternative, either atmospheric or subatmospheric pressure is used in the reaction medium together with an organic or inorganic reducing agent and an electrolytic cell.

Abstract: The invention relates to a method of producing chlorine dioxide, which method comprises reacting chloric acid with hydrogen peroxide as a reducing agent in such proportions that chlorine dioxide is produced.

Abstract: The invention relates to a method of producing an acidified aqueous solution containing alkali metal sulfate and chlorate comprising the steps of introducing an aqueous solution containing alkali metal sulfate and chlorate into an electrochemical cell and electrochemically increasing the acidity of said aqueous solution, wherein the current efficiency of the cell is maintained below 70%.

Abstract: Waste water effluent streams are treated with hydrogen peroxide and ultraviolet radiation. Hydroxyl ions formed by action of UV on H.sub.2 O.sub.2 reduces BOD, COD, AOX and color in effluent. In the case of pulp mill effluent, some or all of the effluent can then be recycled to the pulp mill.

Abstract: A process for continuously producing chlorine dioxide by reacting an alkali metal chlorate, sulfuric acid or another chlorine free mineral acid and hydrogen peroxide as reducing agent to produce chlorine dioxide in an aqueous reaction medium. In the process chlorine dioxide is generated in at least one reaction step comprising at least one reaction vessel, by feeding alkali metal chlorate, acid, hydrogen peroxide and inert gas to said reaction vessel, in substantial absence of added chloride ions. The aqueous reaction medium in said reaction vessel is maintained at a pressure of from about 400 mm Hg to about 900 mm Hg and at a temperature of from about 35.degree. C. to about 100.degree. C. and at an acidity within a range from about 4 to about 14 N and the chlorate concentration of between about 0.05 moles/1 to saturation. Chlorine dioxide, oxygen and inert gas and the depleted aqueous reaction medium is withdrawn from said reaction zone without substantial crystallization of alkali metal sulfate.

Abstract: A process for the production of chlorine dioxide by reacting at least one of chloric acid and an alkali metal chlorate, and hydrogen peroxide as the reducing agent in such proportions that chlorine dioxide is produced in a reaction medium. A mixture comprising chlorine dioxide and oxygen is withdrawn from the reaction medium. Urea and/or one or more phosphonic acid based complexing agents are added to the reaction medium. The stabilizer is added in an amount of 0.01-5 weight % and serves to increase the reaction rate.