Abstract: Methods and systems for electrochemical conversion of carbon dioxide to organic products including formate and formic acid are provided. A method may include, but is not limited to, steps (A) to (C). Step (A) may introduce an acidic anolyte to a first compartment of an electrochemical cell. The first compartment may include an anode. Step (B) may introduce a bicarbonate-based catholyte saturated with carbon dioxide to a second compartment of the electrochemical cell. The second compartment may include a high surface area cathode including indium and having a void volume of between about 30% to 98%. At least a portion of the bicarbonate-based catholyte is recycled. Step (C) may apply an electrical potential between the anode and the cathode sufficient to reduce the carbon dioxide to at least one of a single-carbon based product or a multi-carbon based product.

Abstract: The present disclosure is a method and system for production of oxalic acid and oxalic acid reduction products. The production of oxalic acid and oxalic acid reduction products may include the electrochemical conversion of CO2 to oxalate and oxalic acid. The method and system for production of oxalic acid and oxalic acid reduction products may further include the acidification of oxalate to oxalic acid, the purification of oxalic acid and the hydrogenation of oxalic acid to produce oxalic acid reduction products.

Abstract: Methods and systems for electrochemical conversion of carbon dioxide to organic products including formate and formic acid are provided. A method may include, but is not limited to, steps (A) to (C). Step (A) may introduce an acidic anolyte to a first compartment of an electrochemical cell. The first compartment may include an anode. Step (B) may introduce a bicarbonate-based catholyte saturated with carbon dioxide to a second compartment of the electrochemical cell. The second compartment may include a high surface area cathode including indium and having a void volume of between about 30% to 98%. At least a portion of the bicarbonate-based catholyte is recycled. Step (C) may apply an electrical potential between the anode and the cathode sufficient to reduce the carbon dioxide to at least one of a single-carbon based product or a multi-carbon based product.

Abstract: Methods and systems for electrochemical conversion of carbon dioxide to organic products including formate and formic acid are provided. A method may include, but is not limited to, steps (A) to (C). Step (A) may introduce an acidic anolyte to a first compartment of an electrochemical cell. The first compartment may include an anode. Step (B) may introduce a bicarbonate-based catholyte saturated with carbon dioxide to a second compartment of the electrochemical cell. The second compartment may include a high surface area cathode including indium and having a void volume of between about 30% to 98%. At least a portion of the bicarbonate-based catholyte is recycled. Step (C) may apply an electrical potential between the anode and the cathode sufficient to reduce the carbon dioxide to at least one of a single-carbon based product or a multi-carbon based product.

Abstract: The present disclosure is a method and system for production of oxalic acid and oxalic acid reduction products. The production of oxalic acid and oxalic acid reduction products may include the electrochemical conversion of CO2 to oxalate and oxalic acid. The method and system for production of oxalic acid and oxalic acid reduction products may further include the acidification of oxalate to oxalic acid, the purification of oxalic acid and the hydrogenation of oxalic acid to produce oxalic acid reduction products.

Abstract: A method of enhancing the concentration of a first inorganic compound in a first aqueous solution of a first process of a heavy chemical plant, the method comprising (a) feeding the first solution having the first compound at a first concentration and a first water vapor pressure to an osmotic membrane distillation means comprising a hydrophobic, gas and water vapor permeable membrane separating (i) a first chamber for receiving the first solution, from (ii) a second chamber for receiving a receiver feed aqueous solution having a second water vapor pressure lower than the first water vapor pressure; (b) feeding the receiver aqueous feed solution to the second chamber as to effect transfer of water vapor through the membrane from the first chamber to the second chamber, and to produce (i) a resultant first solution having a second concentration of the first compound greater than the first concentration and (ii) a diluted receiver feed aqueous solution; and (c) collecting the resultant first solution.

Abstract: A method of enhancing the concentration of a first inorganic compound in a first aqueous solution of a first process of a heavy chemical plant, the method comprising (a) feeding the first solution having the first compound at a first concentration and a first water vapor pressure to an osmotic membrane distillation means comprising a hydrophobic, gas and water vapor permeable membrane separating (i) a first chamber for receiving the first solution, from (ii) a second chamber for receiving a receiver feed aqueous solution having a second water vapor pressure lower than the first water vapor pressure; (b) feeding the receiver aqueous feed solution to the second chamber as to effect transfer of water vapor through the membrane from the first chamber to the second chamber, and to produce (i) a resultant first solution having a second concentration of the first compound greater than the first concentration and (ii) a diluted receiver feed aqueous solution; and (c) collecting the resultant first solution.

Abstract: Chlorine is produced by electrolysis of aqueous HCl, in a membrane electrolyzer, using cathodic mediators such as Fe(III) and/or Cu(II) chlorides and a non-catalysed 3-dimensional cathode, with the real surface area at least ten times higher than its projected area. The HCl electrolysis section is combined with an oxidizer for regeneration of the mediator, product water removal step and optional HCl recovery step. Under optimized conditions chlorine can be produced at very high current densities of 30 kA/m2, without initiating undesired H2 evolution reaction at the cathode.

Abstract: A method of enhancing the concentration of a first inorganic compound in a first aqueous solution of a first process of a heavy chemical plant, the method comprising (a) feeding the first solution having the first compound at a first concentration and a first water vapor pressure to an osmotic membrane distillation means comprising a hydrophobic, gas and water vapor permeable membrane separating (i) a first chamber for receiving the first solution, from (ii) a second chamber for receiving a receiver feed aqueous solution having a second water vapor pressure lower than the first water vapor pressure; (b) feeding the receiver aqueous feed solution to the second chamber as to effect transfer of water vapor through the membrane from the first chamber to the second chamber, and to produce (i) a resultant first solution having a second concentration of the first compound greater than the first concentration and (ii) a diluted receiver feed aqueous solution; and (c) collecting the resultant first solution.

Abstract: Chlorine is produced by electrolysis of aqueous HCl, in a membrane electrolyzer, using cathodic mediators such as Fe(III) and/or Cu(II) chlorides and a non-catalysed 3-dimensional cathode, with the real surface area at least ten times higher than its projected area. The HCl electrolysis section is combined with an oxidiser for regeneration of the mediator, product water removal step and optional HCl recovery step. Under optimised conditions chlorine can be produced at very high current densities of 30 kA/m2, without initiating undesired H2 evolution reaction at the cathode.

Abstract: Nanofiltration processes using one or more conventional nanofiltration membrane modules under a positive applied pressure is used to selectively change the concentration of one solute, such as sodium chloride or sodium chlorate providing monovalent ions, from another solute such as sodium sulfate or sodium dichromate to provide multivalent ions in high salt aqueous concentrations. The process is particularly useful in favourably lowering the concentration of undesirable ions, particularly, of silica and dichromate ions in chloralkali and chlorate brine containing solutions and favourably raising the sodium sulphate level relative to sodium chloride in chloralkali liquor.

Abstract: A nanofiltration process using a conventional nanofiltration membrane module under a positive applied pressure is used to selectively change the concentration of one solute, such as sodium chloride or sodium chlorate providing monovalent ions, from another solute such as sodium sulfate or sodium dichromate providing multivalent ions in high salt aqueous concentrations. The process is particularly useful in favourably lowering the concentration of silica and dichromate ions in chloral kali and chlorate brine containing solutions and favourably raising the sodium sulphate level relative to sodium chloride in chloraldhali liquor. The relatively high salt concentration, surprisingly, effects little or no monovalent, particularly, Cl.sup.- rejection.

Abstract: Chlorine dioxide, useful as a pulp mill chemical, is produced without producing sodium sulfate effluent for disposal, by effecting reduction of chloric acid in an aqueous reaction medium in a reaction zone at a total acid normality of up to about 7 normal in the substantial absence of sulfate ion and in the promence of a dead load of sodium chlorate added to and subsequently removed from the reaction medium. Chloric acid for the process is produced electrolytically from an aqueous solution of the deadload sodium chlorate and make-up quantities of sodium chlorate. The chloric acid reduction to produce chlorine dioxide may be effected using methanol or electrolytically.

Abstract: Scale is removed from within cation-exchange membranes by operating the cathode compartment of a cell divided by the cation-exchange membrane with a mildly-acid catholyte while effecting transfer of cationic species from the anode compartment to the cathode compartment.

Abstract: The formation of sodium sulfate by-product in sulfuric acid-based chlorine dioxide generating processes is decreased and preferably eliminated entirely, by effecting electrochemical treatment of sodium ion-containing feed materials for the generator to remove sodium ions and to add hydrogen ions. Sodium hydroxide may be produced as a by-product. The process is generally applicable to the electrochemical treatment of alkali metal chlorates, alkali metal sulfates and mixtures thereof to produce acidified solutions useful in providing chlorate ion-containing feeds to such chlorine dioxide generating processes or for other purposes.

Abstract: Chlorine dioxide, useful as a pulp mill chemical, is produced without producing sodium sulfate effluent for disposal, by effecting reduction of chloric acid in an aqueous reaction medium in a reaction zone at a total acid normality of up to about 7 normal in the substantial absence of sulfate ion and in the presence of a dead load of sodium chlorate added to and subsequently removed from the reaction medium. Chloric acid for the process is produced electrolytically from an aqueous solution of the deadload sodium chlorate and make-up quantities of sodium chlorate. The chloric acid reduction to produce chlorine dioxide may be effected using methanol or electrolytically.

Abstract: The formation of sodium sulfate by-product in sulfuric acid-based chlorine dioxide generating processes is decreased and preferably eliminated entirely, by effecting electrochemical treatment of sodium ion-containing feed materials for the generator to remove sodium ions and add hydrogen ions. Sodium hydroxide is produced as a by-product. The process is generally applicable to the electrochemical treatment of alkali metal chlorates, alkali metal sulfates and mixtures thereof to produce acidified solutions useful in providing chlorate ion-containing feeds to such chlorine dioxide generating processes.

Abstract: Chloric acid is produced in an electrolytic-electrodialytic process in which chlorate ions from a sodium chlorate solution are transferred through an anion-exchange membrane to combine with electrolytically-produced hydrogen ions in a compartment of a cell, from which the resulting chloric acid is recovered. The sodium ions are transferred through a cation-exchange membrane to combine with electrolytically-produced hydroxyl ions in another compartment of the cell, from which the resulting sodium hydroxide is recovered.

Abstract: Chlorine dioxide is produced electrolytically in the cathode compartment of an electrolytic cell using a three-dimensional high surface-area cathode. The cathode compartment is separated from an anode compartment by a cation-exchange membrane. Sodium chlorate is reacted with hydrogen ions and chloride ions in the cathode compartment and chlorine dioxide is vented from the cathode compartments. Chlorine co-produced with the chlorine dioxide is reduced at the cathode to provide chloride ions for the reaction while electrolytically-produced hydrogen ions are transferred across the membrane from the anode compartment to the cathode compartment to provide hydrogen ions for the reaction.

Abstract: A hydrochloric acid-based chlorine dioxide generating process is integrated with an electrolytic process for sodium hydroxide production. Generator liquor in the form of a sodium chloride-enriched solution from the chlorine dioxide generator is passed to the central compartment of a three-compartment cell. Hydrogen ions formed in the anode compartment of the three-compartment cell migrate through a cation-exchange membrane to the central compartment to form hydrochloric acid with the sodium chloride solution while sodium ions migrate through a further cation-exchange membrane to form sodium hydroxide with hydroxyl ions produced in the cathode compartment of the three-compartment cell. The acidified generator liquor containing the hydrochloric acid formed in the central compartment is forwarded to the chlorine dioxide generator to provide half the acid requirement therefor.