Abstract: A method for producing metallic silver by electro-deposition, including electrolyzing an electrolyte solution containing Ce(NO3)3 in an anode zone and an electrolyte solution containing AgNO3 in a cathode zone by using an electrolytic cell with a specific diaphragm, wherein the electrolyte solution in the anode zone is not allowed to enter the cathode zone. After the electrolyzing is complete, the metallic silver with a high purity is obtained at the cathode, and a Ce4+-containing solution is obtained in the anode zone.

Abstract: In one embodiment of the present disclosure, a process for electrochemical hydrogen production is provided. The process includes providing an electrochemical cell with an anode side including an anode, a cathode side including a cathode, and a membrane separating the anode side from the cathode side. The process further includes feeding molecules of at least one gaseous reactant to the anode, oxidizing one or more molecules of the gaseous reactant at the anode to produce a gas product and protons, passing the protons through the membrane to the cathode, and reducing the protons at the cathode to form hydrogen gas.

Abstract: The electrochemical reactors disclosed herein provide novel oxidation and reduction chemistries and employ increased mass transport rates of materials to and from the surfaces of electrodes therein.

Abstract: A hybrid sulfur (HyS) cycle process for the production of hydrogen is provided. The process uses a proton exchange membrane (PEM) SO2-depolarized electrolyzer (SDE) for the low-temperature, electrochemical reaction step and a bayonet reactor for the high-temperature decomposition step The process can be operated at lower temperature and pressure ranges while still providing an overall energy efficient cycle process.

Abstract: The present invention relates to an apparatus to produce oxidizing agent-rich sulfuric acid by electrolysis of sulfuric acid. More specifically, it relates to the apparatus by which dilute sulfuric acid of the specified temperature and concentration is formed within the electrolysis system and then, by electrolysis of the formed dilute sulfuric acid, electrolytic sulfuric acid containing richly oxidizing agent is formed at a high efficiency and safely under the temperature control.

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: An electrocatalytic process to remove organic sulfur compounds from a mixture of water containing a miscible electrolyte and a hydrocarbon feedstock involving the application of a current of electricity to cause the dissociation of the water which produces hydrogen at a catalytic cathode which reduces the organic sulfur compounds in the hydrocarbon with the evolution of H2S which is separated and collected, and the separation and collection of the treated hydrocarbon.

Abstract: A wear of an electrode is prevented as much as possible, thereby efficiently electrolyzing a sulfuric acid solution and the like. An electrolysis method includes: passing an electrolytic solution through an electrolysis cell including at least a pair of an anode and a cathode; and supplying the electrodes with an electric power, so as to electrolyze the electrolytic solution, wherein a viscosity of the electrolytic solution is set in a range in response to a current density upon the electric power supply to carry out the electrolysis. The viscosity of a sulfuric acid solution as the electrolytic solution is equal to or less than 10 cP when the current density is equal to or less than 50 A/dm2, the viscosity of the sulfuric acid solution is equal to or less than 8 cP when the current density is from more than 50 to 75 A/dm2, and the viscosity of the sulfuric acid solution is equal to or less than 6 cP when the current density is from more than 75 to 100 A/dm2.

Abstract: The cleaning method by electrolytic sulfuric acid and the manufacturing method of semiconductor device comprising: the process in which the first sulfuric acid solution is supplied from outside to the sulfuric acid electrolytic cell to form the first electrolytic sulfuric acid containing oxidizing agent in the sulfuric acid electrolytic cell; the process in which the second sulfuric acid solution, which is higher in concentration than said the first sulfuric acid solution previously supplied, is supplied from outside to said sulfuric acid electrolytic cell; said the second sulfuric acid solution and the first electrolytic sulfuric acid are mixed in said sulfuric acid electrolytic cell; and electrolysis is performed to form the cleaning solution comprising the second electrolytic sulfuric acid containing sulfuric acid and oxidation agent in said sulfuric acid electrolytic cell and the process in which cleaning treatment is performed for the cleaning object with said cleaning solution.

Abstract: Absorption of ethylene oxide is one of the methods commonly used to reduce air emissions from sterilization operations. Unlike prior art abators, the present method provides a means to regenerate the absorption medium within the abator and thus avoid the need to remove spent medium and load new medium every time the medium substantially consumed by the absorption process. Regeneration of the absorption medium is achieved through aqueous wash and air dry under ambient conditions and the regeneration cycle can be timed or automated as a function of medium consumption and regeneration of the liquid medium is achieved through electrochemical oxidation of the ethylene oxide reaction products.

Abstract: A method of treating hydrogen sulfide or producing hydrogen which comprises disposing a liquid tank having a photocatalyst electrode comprising a photocatalyst and a liquid tank having a metal electrode so that the two liquid tanks are separated from each other by a cation-exchange membrane, placing a liquid containing either hydrogen sulfide or an organic substance in the liquid tank having the photocatalyst electrode, electrically connecting the photocatalyst electrode to the metal electrode, and exposing the photocatalyst to a light. The liquid to be placed in the liquid tank having the metal electrode preferably is an acidic solution. The photocatalyst preferably comprises a metal sulfide, and preferably is fine particles having a layered nanocapsule structure.

Abstract: A multi-pressure hybrid sulfur process (2) contains at least one electrolyzer unit (16) which provides liquid H2SO4 to a preheater/vaporizer reactor (20) operating at a pressure of from 1 MPa to 9 MPa to form gaseous H2SO4 which is passed to a decomposition reactor (14) operating at a pressure of from 7 MPa to 9 MPa, where decomposed H2SO4 is passed to at least one scrubber unit (14) and at least one electrolyzer unit (16) both preferably operating at a pressure of 0.1 MPa to 7 MPa, where an associated Rankine Cycle power conversion unit (50) supplies electricity.

Abstract: Methods and systems for generating sulfuric acid are disclosed. In some embodiments, the method includes combusting a sulfur-containing material with a gas including oxygen to produce a first stream of sulfur dioxide, mixing water with the first stream of sulfur dioxide to produce a mixed stream, using an energy, electrolytically converting the mixed stream of sulfur dioxide and water into sulfuric acid and hydrogen, generating a source of energy from the hydrogen, and providing the source of energy as at least a portion of the energy for electrolytically converting the first stream of sulfur dioxide and water into sulfuric acid and hydrogen. In some embodiments, the system includes a first chamber for combusting a sulfur-containing material to produce a first stream of sulfur dioxide, an electrolytic cell for converting the first stream into sulfuric acid and hydrogen, and a fuel cell for generating an energy source from the hydrogen.

Abstract: An electrochemical process for the recovery of metallic iron or an iron-rich alloy, oxygen and sulfuric acid from iron-rich metal sulfate wastes is described. Broadly, the electrochemical process comprises providing an iron-rich metal sulfate solution; electrolyzing the iron-rich metal sulfate solution in an electrolyzer comprising a cathodic compartment equipped with a cathode having a hydrogen over-potential equal or higher than that of iron and containing a catholyte having a pH below about 6.0; an anodic compartment equipped with an anode and containing an anolyte; and a separator allowing for anion passage; and recovering electrodeposited iron or iron-rich alloy, sulfuric acid and oxygen gas. Electrolyzing the iron-rich metal sulfate solution causes iron or an iron-rich alloy to be electrodeposited at the cathode, nascent oxygen gas to evolve at the anode, sulfuric acid to accumulate in the anodic compartment and an iron depleted solution to be produced.

Abstract: A cell having an anode compartment and a cathode compartment is used to electrolyze an alkali metal polysulfide into an alkali metal. The cell includes an anode, wherein at least part of the anode is housed in the anode compartment. The cell also includes a quantity of anolyte housed within the anode compartment, the anolyte comprising an alkali metal polysulfide and a solvent. The cell includes a cathode, wherein at least part of the cathode is housed in the cathode compartment. A quantity of catholyte is housed within the cathode compartment. The cell operates at a temperature below the melting temperature of the alkali metal.

Abstract: A membrane electrolysis cell comprising an anodic compartment and a cathodic compartment is described, wherein at least one of the two compartments contains an electrode fed with gas and a porous planar element is interposed between the membrane and the gas-fed electrode. A flow of chemically aggressive electrolyte crosses the porous planar element downwards under the effect of the gravity force. The planar element consists in a plastic element withstanding the aggressive operative conditions: The use of perfluorinated plastics such as ECTFE, PTEFE, FEP, PFA is preferred, even though they are strongly hydrophobic. When the gas-fed electrode is a cathode and the gas contains oxygen, the gas crosses the cathodic compartment upwardly so as to minimize the risk of hydrogen build up. The cell equipped with the oxygen cathode is particularly advantageous for the sodium chloride electrolysis.

Abstract: The cleaning method by electrolytic sulfuric acid and the manufacturing method of semiconductor device comprising: the process in which the first sulfuric acid solution is supplied from outside to the sulfuric acid electrolytic cell to form the first electrolytic sulfuric acid containing oxidizing agent in the sulfuric acid electrolytic cell; the process in which the second sulfuric acid solution, which is higher in concentration than said the first sulfuric acid solution previously supplied, is supplied from outside to said sulfuric acid electrolytic cell; said the second sulfuric acid solution and the first electrolytic sulfuric acid are mixed in said sulfuric acid electrolytic cell; and electrolysis is performed to form the cleaning solution comprising the second electrolytic sulfuric acid containing sulfuric acid and oxidation agent in said sulfuric acid electrolytic cell and the process in which cleaning treatment is performed for the cleaning object with said cleaning solution.

Abstract: In an electrolyzer comprising an anode compartment provided with porous anodes, a cathode compartment, and a membrane providing a partition between the anode compartment and the cathode compartment, wherein a solution containing sulfide ions is introduced into the anode compartment, and an aqueous solution containing caustic soda is introduced into the cathode compartment, thereby producing a polysulfide containing polysulfide sulfur through electrolytic oxidation, wherein the anode compartment of the electrolyzer is cleaned with the use, of an aqueous solution containing at least either one of an inorganic acid, a chelating agent, and a scale-cleaning agent, thereby recovering performance of the electrolyzer. Further, when the contents of the anode compartment are replaced with an alkaline aqueous solution containing not more than 0.1 mass % of sulfide ions and not more than 0.1 mass % of carbonate ions upon stopping the electrolytic oxidation, thereby maintaining the performance of the electrolyzer.

Abstract: Methods and systems for generating sulfuric acid (102) are disclosed. In some embodiments, the method includes combusting a sulfur-containing material (114) with a gas including oxygen (116) to produce a first stream of sulfur dioxide (118), mixing water with the first stream of sulfur dioxide to produce a mixed stream, using an energy, electrolytically converting (108) the mixed stream of sulfur dioxide and water into sulfuric acid (102) and hydrogen (122), generating a source of energy (126) from the hydrogen, and providing the source of energy as at least a portion of the energy for electrolytically converting the first stream of sulfur dioxide and water into sulfuric acid and hydrogen. In some embodiments, the system includes a first chamber for combusting a sulfur-containing material to produce a first stream of sulfur dioxide, an electrolytic cell (108) for converting the first stream into sulfuric acid and hydrogen, and a fuel cell (112) for generating an energy source from the hydrogen.

Abstract: There is provided a method for thermochemically producing hydrogen from water by using sulfuric acid as a kind of reactant, combining a plurality of chemical reactions inclusive of sulfuric acid decomposition reaction and circulating reactants. The sulfuric acid decomposition reaction is carried out at a temperature of 600° C. or less by electrolysis using a partition wall of oxygen ion-permeable solid electrolyte and oxygen is separated simultaneously with the electrolysis to thereby carry out the method for producing hydrogen by chemical process using heat with electricity.

Abstract: The present invention provides a process for producing fine particles of a salt, hydroxide or oxide, wherein when producing the salt, hydroxide or oxide by electrodialysis using anion exchange membranes and cation exchange membranes, a conductive liquid acting as a poor solvent for the salt, hydroxide or oxide which is produced in a concentration chamber is used as a concentration chamber solution, as well as the fine particles of the salt, hydroxide or oxide which are produced by the above process.

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: A multi-pressure hybrid sulfur process (2) contains at least one electrolyzer unit (16)which provides liquid H2SO4 to a preheater/vaporizer reactor (20) operating at a pressure of from 1 MPa to 9 MPa to form gaseous H2SO4 which is passed to a decomposition reactor (14) operating at a pressure of from 7 MPa to 9 MPa, where decomposed H2SO4 is passed to at least one scrubber unit (14) and at least one electrolyzer unit (16) both preferably operating at a pressure of 0.1 MPa to 7 MPa, where an associated Rankine Cycle power conversion unit (50) supplies electricity.

Abstract: The present invention includes a process for the removal of hydrogen sulfide from hydrogen sulfide gas containing gaseous streams. In one embodiment, the process comprises feeding a sulfide ion containing solution to an oxidation unit. The method further comprises feeding an oxidizing gas to the oxidation unit and contacting the sulfide ion containing solution with the oxidizing gas under sufficient conditions to form a polysulfide solution comprising polysulfide and hydroxide ions. In addition, the process comprises mixing the polysulfide containing solution with a hydrogen sulfide gas under conditions sufficient for absorption of hydrogen sulfide and precipitation of sulfur from the polysulfide containing solution. In some embodiments, the process comprises separating the precipitated sulfur from liquid.

Abstract: A process for the production of a vanadium compound from carbonaceous residues containing vanadium, which includes the steps of: (a) combusting the carbonaceous residues at a temperature of 500-690° C. in an oxygen-containing gas to form vanadium-containing combustion residues; (b) heating the vanadium-containing combustion residues at a temperature T in ° C. under an oxygen partial pressure of at most T in kPa wherein T and P meet with the following conditions: log10(P)=−3.45×10−3×T+2.21 500≦T≦1300 to obtain a solid product containing less than 5% by weight of carbon and vanadium at least 80% of which is tetravalent vanadium oxide; (c) selectively leach tetravalent vanadium ion with sulfuring acid at pH in the range of 1.5-4; (d) separating a liquid phase from the leached mixture; (e) adding an alkaline substance to the liquid phase to adjust the pH thereof in the range of 4.5-7.

Abstract: In a process for producing kraft pulp, the process is made closed, the yield of pulp is improved and environmental problems are minimized. An alkaline solution containing Na2S which flows in a process of producing kraft pulp, is electrolyzed by an electrolytic oxidation method; a liquid which is formed at an anode side and contains a polysulfide type sulfur in an amount of 6 g/l or more, is added, as it is or after being causticized, to the process before a chip has the maximum temperature, and a NaOH solution formed at a cathode side, is added to at least one step of the process after the chip has the maximum temperature till a final bleaching stage; and at least chemicals in the step wherein NaOH is added, among chemicals discharged in all steps from a cooking step till the final bleaching stage, are recovered and reused.

Abstract: The present invention has an object to obtain a cooking liquor containing polysulfide-sulfur at a high concentration by minimizing by-production of thiosulfate ions. The present invention is a method for producing polysulfides, which comprises introducing a solution containing sulfide ions into an anode compartment of an electrolytic cell comprising the anode compartment provided with a porous anode, a cathode compartment provided with a cathode, and a diaphragm partitioning the anode compartment and the cathode compartment, for electrolytic oxidation to obtain polysulfide ions, characterized in that the porous anode is disposed so that a space is provided at least partly between the porous anode and the diaphragm, and the apparent volume of the porous anode is from 60% to 99% based on the volume of the anode compartment.

Abstract: An electrolytic production of sodium persulfate in a decreased number of steps with low unit power cost is described. Sodium persulfate is caused to crystallize by the reaction between an anode product and sodium hydroxide. The resulting sodium persulfate slurry is separated into a mother liquor and sodium persulfate crystals which are recovered and dried to obtain product sodium persulfate. In the process of the invention, ammonia liberated in the reaction-type crystallization of sodium persulfate is recovered into a cathode product, which is then neutralized by sodium hydroxide and/or ammonia. The neutralized solution is combined with sodium sulfate recovered from the mother liquor after recovering the sodium persulfate crystals and reused as a part of the starting material for an anolyte feed solution.

Abstract: There is disclosed a process for producing a potassium sulfate electrochemically. The process involves the use of sodium sulfate which is electrolyzed in an electrolytic cell and which results in the production of sodium hydroxide and ammonium sulfate. The process carried out in a two or three-compartment electrolytic cell and the ammonium sulfate is converted by ammoniation and treatment of the ammoniated mixture with potassium chloride to produce potassium sulfate. Potassium sulfate may then also undergo electrochemical treatment to produce potassium hydroxide and ammonium sulfate.

Abstract: A bipolar electrolytic cell can include, as a manifold, a spiral manifold assembly. This spiral manifold assembly will comprise a first outer assembly member, a second outer assembly member and a center assembly member. The overall structure can provide reduced loss of metal or gas and minimal loss of electrical current during an electrolytic process.

Abstract: The invention provides methods and devices that enable the nesting of metal units. One method generally identifies a nesting location on the metal unit, and applies a force at the nesting location to create a nesting feature. In another embodiment, the invention is a nestable metal sheet. The nestable metal sheet is generally a metal sheet, such as a copper cathode, having a nesting feature.

Abstract: In a method of producing reduced sulfur dyes, the improvement comprising cathodically reducing a sulfur dye to produce at least 150 Ah.kg−1 of reduction equivalents with respect to the solid dye, wherein at least 50 Ah.kg−1 is introduced by cathodic reduction.

Abstract: It is an object of the present invention to produce a cooking liquor containing polysulfide sulfur at a high concentration from white liquor in a pulp production process with a high selectivity at a low electric power with very little production of thiosulfate ions as by-product. The present invention provides a method for producing polysulfides, which comprises introducing a solution containing sulfide ions into an anode compartment of an electrolytic cell comprising the anode compartment provided with a porous anode, a cathode compartment provided with a cathode and a diaphragm partitioning the anode compartment and the cathode compartment, for electrolytic oxidation to obtain polysulfide ions, wherein at least the surface of said anode is made of nickel, and the porous anode has a physically continuous three-dimensional network structure.

Abstract: There is disclosed a process for producing sodium persulfate which comprises the step (1) of electrolyzing, at an anode, a solution containing ammonium sulfate, and the step (2) of producing sodium persulfate from the resultant liquid produced at the anode and sodium hydroxide and, as desired, the step of removing sodium sulfate, and further as desired, the step (3) of performing crystallization on the reaction liquid as produced in the step (2). According to the above process, it is made possible to efficiently produce sodium persulfate having a markedly high purity substantially free from nitrogen components at a high yield at a high current efficiency in electrolysis.

Abstract: The invention proposes a process and waste treatment plant for regenerating alkali metal hydroxide (3) from an alkaline aqueous waste stream (5) that contains alkali metal C3+ carboxylate byproduct. The waste stream (5) is acidified and the resulting liquour (9) is fed to a first distillation zone (12) to distil carboxylic acid and water. Alternatively, it is fed to a settling zone (14) from which an upper organic layer (16) is recovered as well as a lower aqueous phase (17; 104) which is fed to the first distillation zone. The overhead product (20) from the first distillation zone is condensed and separated into a carboxylic acid layer which is either purged (28) or fed (101) to the settling zone (25). The lower layer (32) of the condensate is redistilled and the water bottoms stream (47) is fed to the cathode compartment (60) of an electrolytic cell (58), while the bottoms stream (52) from the first distillation zone is supplied to the anode compartment (59).

Abstract: In removal of sulfate groups and chlorate groups from brine used for electrolysis, concentrated brine used in an electrolysis process or dilute brine whose concentration is decreased by electrolysis is fed to an anode chamber divided by a cation exchange membrane in a brine treating electrolyzer, where the concentrated or dilute brine is electrolyzed to recover chloride ions therein. The concentrated brine is electrolyzed at a rate of decomposition of salt higher than that in the ion exchange membrane electrolysis process of brine. Thereafter, the concentrated or dilute brine is discharged out of the electrolysis process.

Abstract: A method for producing polysulfides, which comprises introducing a solution containing sulfide ions into an anode compartment of an electrolytic cell comprising the anode compartment provided with a porous anode, of which at least the surface is made of carbon, a cathode compartment provided with a cathode, and a diaphragm partitioning the anode compartment and the cathode compartment, and carrying out electrolytic oxidation to obtain polysulfide ions.

Abstract: The invention relates to an electrochemical process for the production of sodium hydroxide and sulfuric acid from aqueous sodium sulfate solutions, said process comprising the feeding of an aqueous sodium sulfate solution into a salt splitter device comprising at least three compartments including a middle feed compartment which is between an anode compartment and a cathode compartment, wherein the feed compartment is separated from the anode compartment by a chemically-functionalized anion exchange membrane, and wherein the feed compartment is separated from the cathode compartment by a chemically-functionalized cation exchange membrane. Specifically, the chemically-functionalized anion exchange membrane of the present invention is a perfluorohydrocarbon polymer material to which has been grafted a plurality of benzo-crown ether groups which have been complexed with a metal ion selected from sodium, potassium and lithium.

Abstract: The present invention relates to an electrochemical cell and a process for producing a hydroxide solution, sulfuric acid and a halogen gas from a hydrogen halide and a sulfate solution. In particular, the sulfate solution may be an alkali metal sulfate solution, such as sodium or potassium sulfate solution, an alkaline earth metal sulfate solution or an ammonium sulfate solution. The cell and the process may use either an anhydrous or an aqueous hydrogen halide, namely, hydrogen chloride, hydrogen fluoride, hydrogen bromide and hydrogen iodide, to a respective dry halogen gas, such as chlorine, fluorine, bromine, or iodine, to produce hydrogen ions in order to split the alkali metal solution and form the sulfuric acid. The cell has two membrane-electrode assemblies, where an anode is disposed in contact with one membrane, and a cathode is disposed in contact with another membrane. The sulfate solution is fed in between the membrane-electrode assemblies.

Abstract: The present invention is directed to an apparatus and methods for preparing sulfur hexafluoride within an electrolytic cell by reacting elemental sulfur with fluorine electrolytically generated from substantially anhydrous hydrogen fluoride in the presence of a conductivity-enhancing solute. The reaction occurs at the anode of the electrolytic cell in a liquid electrolyte comprising substantially anhydrous hydrogen fluoride and an alkali fluoride wherein the concentration of hydrogen fluoride is maintained between about 64 and about 88 mole percent. The electrolytic cell is preferably divided into a cathodic half-cell and an anodic half-cell by a non-conductive diaphragm which permits passage of the electrolyte and current to provide communication between the half-cells while being impervious to fluid communication above the electrolyte to keep the generated gases separate. When so divided, substantially pure sulfur hexafluoride may be recovered from the space above the electrolyte in the anodic half-cell.

Abstract: The present invention is directed towards a method that makes sulfuric acid from a dry flue gas desulfurization process which utilizes a low temperature regeneration of the carbon adsorbent in the flue gas process. The sulfuric acid is generated in an electrolytic reactor. This invention is also directed towards a system that regenerates the carbon used in dry flue gas desulfurization at a temperature below 120.degree. C.

Abstract: The ammonium polysulfide is produced in at least one electrochemical cell, to which an aqueous ammonium sulfide solution is supplied as electrolyte. The cell comprises an anode, a gas diffusion cathode, and between the anode and the cathode an electrolyte chamber, where the cell voltage is 0.01 to 5V. The cathode has an electrically conductive, gas-permeable carbon layer, over which flows gas containing free oxygen, and which is in contact with the electrolyte. O.sub.2 -containing gas is introduced into the electrolyte chamber, thereby forming hydroperoxide anions (OOH.sup.-) in the electrolyte chamber. From the electrolyte chamber a solution containing ammonium polysulfide and a residual gas are withdrawn.

Abstract: The present invention relates to an electrochemical cell and a process for using a halogen halide and splitting a sulfate solution and producing a hydroxide solution, sulfuric acid and a halogen gas. In particular, the sulfate solution may be an alkali metal sulfate solution, such as sodium or potassium sulfate solution, an alkaline earth metal sulfate solution or an ammonium sulfate solution. The cell and the process may use either an anhydrous or an aqueous hydrogen halide, namely, hydrogen chloride, hydrogen fluoride, hydrogen bromide and hydrogen iodide, to a respective dry halogen gas, such as chlorine, fluorine, bromine, or iodine, to produce hydrogen ions in order to split the sulfate solution and form the sulfuric acid. The cell has two membrane-electrode assemblies, where an anode is disposed in contact with one membrane, and a cathode is disposed in contact with another membrane. The sulfate solution is fed in between the membrane-electrode assemblies.

Abstract: Electrolyzer comprising at least one elementary cell divided into electrolyte compartments by cation-exchange membranes, said compartments are provided with a circuit for feeding electrolytic solutions and a circuit for withdrawing electrolysis products, said cell is equipped with a cathode and a hydrogen-depolarized anode assembly forming a hydrogen gas chamber fed with a hydrogen-containing gaseous stream, characterized in that said assembly comprises a cation-exchange membrane, a porous, flexible electrocatalytic sheet, a porous rigid current collector having a multiplicity of contact points with said electrocatalytic sheet, said membrane, sheet and current collector are held in contact together by means of pressure without bonding.

Abstract: A process is provided for removing sulfur dioxide (SO.sub.2) from a waste gas stream by electrolysis using a pulsed electric current and recovering the sulfur values as sulfuric acid. The sources of the waste gas stream include effluent vent, flue or exhaust gases from power plants, sulfuric acid plants, ore roasters, and solid waste incnierators. The purpose of the process is to achieve economies of operation, provide a useful byproduct, and minimize environmental pollution.