A method of producing potassium sulfate by employing sodium sulfate and potassium chloride sources is disclosed. The method includes a crystallization process that yields a mother liquor containing sulfate, sodium and chloride. The mother liquor is directed to an anion segregation unit that produces a reject or retentate rich in sulfate which is recycled and employed in the production of the potassium sulfate. Further, the anion segregation unit produces a permeate that is depleted in sulfate but includes sodium and chloride and is directed to a sodium chloride crystallizer for producing sodium chloride.

A method of producing potassium sulfate by employing sodium sulfate and potassium chloride sources is disclosed. The method includes a crystallization process that yields a mother liquor containing sulfate, sodium and chloride. The mother liquor is directed to an anion segregation unit that produces a reject or retentate rich in sulfate which is recycled and employed in the production of the potassium sulfate. Further, the anion segregation unit produces a permeate that is depleted in sulfate but includes sodium and chloride and is directed to a sodium chloride crystallizer for producing sodium chloride.

The disclosure provides seven integrated methods for the chemical sequestration of carbon dioxide (CO.sub.2), nitric oxide (NO), nitrogen dioxide (NO.sub.2) (collectively NO.sub.x, where x=1, 2) and sulfur dioxide (SO.sub.2) using closed loop technology. The methods recycle process reagents and mass balance consumable reagents that can be made using electrochemical separation of sodium chloride (NaCl) or potassium chloride (KCl). The technology applies to marine and terrestrial exhaust gas sources for CO.sub.2, NOx and SO.sub.2. The integrated technology combines compatible and green processes that capture and/or convert CO.sub.2, NOx and SO.sub.2 into compounds that enhance the environment, many with commercial value.

A method includes contacting a metallic compound comprising a first metallic cation, with a melt comprising a metallic polysulfide comprising a second metallic cation, thereby forming a molten metallic polysulfide of the first metallic cation. The method also includes cooling the melt to form a sulfur phase and a solid phase comprising the molten metallic polysulfide of the first metallic cation.

A method includes contacting a metallic compound comprising a first metallic cation, with a melt comprising a metallic polysulfide comprising a second metallic cation, thereby forming a molten metallic polysulfide of the first metallic cation. The method also includes cooling the melt to form a sulfur phase and a solid phase comprising the molten metallic polysulfide of the first metallic cation.

Some embodiments of the invention include inventive catalysts (e.g., compounds of Formula (I) or (Ia)). Other embodiments include compositions comprising the inventive catalysts. Some embodiments include methods of using the inventive catalysts (e.g., in hydrofluorination of an organic compound). Further embodiments include methods for making the inventive catalysts. Additional embodiments of the invention are also discussed herein.

Some embodiments of the invention include inventive catalysts (e.g., compounds of Formula (I) or (Ia)). Other embodiments include compositions comprising the inventive catalysts. Some embodiments include methods of using the inventive catalysts (e.g., in hydrofluorination of an organic compound). Further embodiments include methods for making the inventive catalysts. Additional embodiments of the invention are also discussed herein.

The present invention relates to a process for producing sodium sulphate from phosphogypsum, comprising: a step (101) of lixiviation of phosphogypsum by means of a basic solution so as to obtain a sodium sulphate solution (S) containing metal impurities, said basic solution comprising a chelating agent suitable for forming complexes with at least one part of said metal impurities, at least one first step (103, 104) of filtration of the sodium sulphate solution by a nanofiltration membrane (NF1, NF2), so as to form a concentrate (C1, C2) containing said complexes and a permeate (P1, P2), a step (105) of evaporation of the permeate (P1, P2) so as to form anhydrous sodium sulphate.

The present invention relates to a process for producing sodium sulphate from phosphogypsum, comprising: a step (101) of lixiviation of phosphogypsum by means of a basic solution so as to obtain a sodium sulphate solution (S) containing metal impurities, said basic solution comprising a chelating agent suitable for forming complexes with at least one part of said metal impurities, at least one first step (103, 104) of filtration of the sodium sulphate solution by a nanofiltration membrane (NF1, NF2), so as to form a concentrate (C1, C2) containing said complexes and a permeate (P1, P2), a step (105) of evaporation of the permeate (P1, P2) so as to form anhydrous sodium sulphate.

A method of treating fly ash containing sodium sulfate from a recovery boiler of a chemical pulp mill. This method includes at least the following steps: a) ash is dissolved in an aqueous solution and the pH of the solution is adjusted with alkali for precipitating impurities, b) the solution is filtered for removing the impurities containing precipitate, c) sodium sulfate is crystallized from the solution and the crystals are separated from the solution by filtering or by centrifugation, and d) the crystallized sodium sulfate is used as initial material for producing sodium and sulfur containing chemicals or as process chemical.