Abstract: A process and apparatus for producing chlorine dioxide comprising chemically reducing chloric acid with water in the presence of any oxygen-evolving catalyst and in the absence of another acid or an added reducing agent, thereby producing chlorine dioxide and oxygen.

Abstract: A process for gas phase delignifying wood pulp comprising: contacting wood pulp in the first stage of pulp bleaching with chlorine dioxide-containing gas to delignify said wood pulp; wherein(a) said wood pulp has a consistency of at least about 15 percent;(b) said chlorine dioxide-containing gas contains less than about 3% by weight chlorine gas, based on the weight of chlorine dioxide in said gas; and(c) said contacting is conducted at a subatmospheric pressure from about 15 to about 750 mm Hg. This process reduces the formation of chloroform and significantly reduces the amounts of toxic by-products such as dioxin and other organic chlorides. These undesirable by-products, collectively identified as absorbable organic halides (AOX), require effluents from pulp bleaching processes to undergo expensive treatment methods to eliminate AOX's prior to discharges to sewers. The effluent discharge from this process generally has less than 2.0 kg adsorbed organic halides (AOX) per ton of wood pulp.

Abstract: The novel process of the invention produces chlorine dioxide by feeding an aqueous solution of chloric acid to a chlorine dioxide generator. The aqueous solution of chloric acid is reacted with a reducing agent in the chlorine dioxide generator to produce chlorine dioxide and a spent chloric acid solution containing metallic impurities. A portion of the spent chloric acid solution containing metallic impurities is reacted with a basic compound selected from the group consisting of alkali metal hydroxides, and alkali metal carbonates in a neutralizing zone to form a precipitate of the metallic impurities and an alkali metal chlorate solution. The precipitate of the metallic impurities is separated from the alkali metal chlorate solution and the alkali metal chlorate solution fed to an ion exchange compartment of an electrolytic cell having an anode compartment, a cathode compartment, and at least one ion exchange compartment between the anode compartment and the cathode compartment.

Abstract: A process which comprises heating a reaction mixture comprised of an aqueous solution containing perchlorate ions, chlorate ions and hydrogen ions to produce chlorine dioxide and oxygen gas.The novel process of the present invention provides a commercially viable process for producing chlorine dioxide from mixtures of oxy-chlorine species in the absence of a reducing agent. The process can be operated without producing an acidic salt by-product while producing a chlorine dioxide product which is substantially free of chlorine. In addition, the process of the invention permits a reduction in the amount of acid fed to the chlorine dioxide generator.

Abstract: A process for producing chlorine dioxide is provided which reacts an aqueous solution of chloric acid and an alkali metal chlorate with a solution of a non-oxidizable acid in the presence of an oxygen-evolving catalyst in a reaction zone to produce a gaseous mixture of chlorine dioxide gas, oxygen, water vapor and an aqueous solution of the non-oxidizable acid and an alkali metal salt of the non-oxidizable acid. The gaseous mixture of chlorine dioxide gas and oxygen are separated from the aqueous solution of the non-oxidizable acid and alkali metal salt of the non-oxidizable acid, while the aqueous solution of the non-oxidizable acid and alkali metal salt of the non-oxidizable acid is fed to the anode compartment of three compartment electrolytic cell having at least one ion exchange compartment between an anode and a cathode compartment.

Abstract: An aqueous solution of chloric acid and alkali metal chlorate is produced in an electrolytic cell having an anode compartment, a cathode compartment, and at least one ion exchange compartment between the anode compartment and the cathode compartment, in a process which comprises:a) feeding an aqueous solution of an alkali metal chlorate to the ion exchange compartment,b) passing hydrogen and alkali metal ions from the anode compartment through a cation exchange membrane into the ion exchange compartment, wherein the hydrogen ions displace alkali metal ions to produce an aqueous solution of chloric acid and alkali metal chlorate,c) passing alkali metal ions from the ion exchange compartment into the cathode compartment,d) electrolyzing the aqueous solution of chloric acid and alkali metal chlorate in the anode compartment to produce an aqueous solution of chloric acid, alkali metal chlorate, hydrogen ions and perchlorate ions as a minor constituent.

Abstract: A process which comprises heating a reaction mixture comprised of an aqueous solution containing perchlorate ions, chlorate ions and hydrogen ions to produce chlorine dioxide and oxygen gas.The novel process of the present invention provides a commercially viable process for producing chlorine dioxide from mixtures of oxy-chlorine species in the absence of a reducing agent. The process can be operated without producing an acidic salt by-product while producing a chlorine dioxide product which is substantially free of chlorine. In addition, the process of the invention permits a reduction in the amount of acid fed to the chlorine dioxide generator.

Abstract: An electrolytic filter press membrane cell and a method of operating the cell to produce concentrated perchloric acid are disclosed. The cell employs concentrated hypochlorous acid as the anolyte and operates with a two-stage single oxidation process at high current density.

Abstract: A process for treating wastewater the improvement which comprises admixing with the wastewater at least 0.5 percent by weight of a solution consisting of hypochlorous acid having a pH of less than 3 to prepare disinfected wastewater having substantially no available chlorine residual.The novel process of the present invention provides rapid, intimate mixing of the highly pure, highly acidic hypochlorous acid solution with the wastewater stream to disinfect wastewater bodies while minimizing unwanted side effects. The process eliminates the need for storing and handling pressurized gaseous or liquid chlorine.

Abstract: A process for sanitizing impotable water the improvement which comprises admixing with the impotable water a solution consisting of hypochlorous acid containing at least 0.5 percent by weight of HOCl and having a pH of less than 3 to prepare potable water having an available chlorine residual.

Abstract: A process for producing chloric acid in an electrolytic cell having an anode and a cathode which includes feeding an aqueous solution of hypochlorous acid to the electrolytic cell, and electrolyzing the aqueous solution of hypochlorous solution to produce a chloric acid solution. Using the process of the invention, chloric acid can be produced efficiently at substantially reduced production costs using a process which can be operated commercially. In addition, the chloric acid solutions produced are of high purity and are stable at ambient conditions.

Abstract: A process for producing chlorine dioxide by oxidizing a hypochlorous acid solution to produce a chloric acid solution, and, electrolyzing the chloric acid solution to produce chlorine dioxide.The novel process of the present invention provides a commercially viable process for producing the chloric acid and eliminates the formation of an acidic salt solution in the production of chlorine dioxide which requires disposal. Further, the process permits a reduction in the amount of acid required in the generation of chlorine dioxide.

Abstract: A current conductor assembly for conducting electric current to electrodes in cells for the electrolysis of a salt solution is comprised of a conductor and a nonconductive casing for the conductor. There is a space between the conductor and the casing with an inlet in the casing for receiving a fluid. The conductor assembly has means for supplying a pressurized fluid to the space between the conductor and the casing; means for sealingly attaching one end of the conductor assembly to the electrodes, where this end is immersed in the salt solution; and a compressible sealing assembly for the opposite end of the conductor assembly comprised of a compression means and a sealing means.The conductor assembly employs the pressurized fluid to prevent corrosive attack of the conductor metal should a leak develop in the conductor assembly.

Abstract: A novel process for purifying an alkaline solution of a lower alkyl alcohol containing as an impurity an alkali metal alkoxide, an alkali metal hydroxide, and water is disclosed. The process comprises treating the alkaline solution of a lower alkyl alcohol with an anhydrous hydrogen halide to react with the alkali metal alkoxide and the alkali metal hydroxide to provide a neutral solution comprised of the lower alkyl alcohol, an alkali metal halide and water. The alkali metal halide is removed from the neutral solution to obtain a substantially salt-free solution comprised of the lower alkyl alcohol and water. A zeolite molecular sieve is contacted with the solution to remove the water and to recover a substantially anhydrous solution of a lower alkyl alcohol. The process produces purified substantially anhydrous alcohol solutions suitable for the use in the production of alkali metal alkoxides such as sodium methoxide without introducing undesired amounts of alkaline impurities into the product.

Abstract: A method has been devised for removing hexavalent chromium from concentrated aqueous alkali metal chlorate solution by reacting the solution with an inorganic sulfur containing compound and separating divalent and trivalent chromium compounds from the solution. Alkali metal hypohalites may be simultaneously removed from the chlorate solution by reaction with excess inorganic sulfur containing compound.

Abstract: An improvement is disclosed in the preparation of pentachloronitrobenzene by the nitration of pentachlorobenzene. The improvement, which is primarily aimed at reducing the residual level of the undesirable starting material, pentachlorobenzene, in the product, includes a two-stage reactant mixing step wherein the pentachlorobenzene is first mixed with sulfuric acid and then concentrated nitric acid is added to this mixture.

Abstract: Hydrogen halide levels of halogenated aliphatic nitriles are unexpectedly reduced by condensing a vapor comprising hydrogen halide and halogenated aliphatic nitrile at selected elevated temperatures, thus producing a product having reduced hydrogen halide levels and improved storage stability.