Process for the manufacture of sodium hydroxide
AssigneeSolvay (Societe Anonyme)
InventorLouis Bourgeois
Life of this patent
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Abstract
Process for the manufacture of sodium hydroxide, according to which an electrodialysis cell is used, water or an aqueous sodium hydroxide solution (10, 10') is introduced into a chamber (6, 6') of the cell, defined between a cationic membrane (2, 2') and an anionic face (8, 8') of a bipolar membrane (3, 3'), an aqueous sodium carbonate solution (11, 11') is introduced into a chamber (7, 7') defined between a cationic face (9, 9') of the bipolar membrane (3, 3') and another cationic membrane (2', 2"), an alkaline pH is maintained in the chamber (7, 7') which is supplied with the sodium carbonate solution (11, 11') and an aqueous sodium hydroxide solution (12, 12') is drawn off from the chamber (6, 6') containing the anionic face (8, 8') of the bipolar membrane (3, 3').
Claims5
A process for the manufacture of sodium hydroxide, comprising:
- providing an electrodialysis cell comprising parallel, spaced alternating cationic and bipolar membranes defining chambers therebetween, said bipolar membranes having opposite cationic and anionic faces;
- introducing aqueous sodium carbonate solution into first chambers of said electrodialysis cell defined by a cationic face of said bipolar membrane, and a cationic membrane, and maintaining the pH of said sodium carbonate solution in said first chambers sufficiently alkaline to avoid decomposition of sodium bicarbonate;
- introducing water or an aqueous sodium hydroxide solution into second chambers of said electrodialysis cell defined by an anionic face of said bipolar membrane and a cationic membrane;
- withdrawing aqueous sodium bicarbonate solution from said first chambers and decomposing said aqueous sodium bicarbonate solution to form an aqueous sodium carbonate solution and recycling said aqueous sodium carbonate solution into said first chambers;
- and
- withdrawing aqueous sodium hydroxide from said second chambers of said electrodialysis cell.
Dependencies are inferred from the claim text.