Solvay (Societe Anonyme)

Luc Botte

Edgard Nicolas

Francesco Posar

Alessandra Pastacaldi

Ellenio Mischi

Stefano Bigini

Davide Mantione

A process for producing a bipolar membrane is described in which a cationic membrane undergoes a treatment with a salt from a group 8 metal, an anionic membrane undergoes a treatment with a salt of a transition metal not belonging to group 8, and then the two membranes are conjoined and, before and/or after having been conjoined, the membranes are brought into contact with a treatment solution selected from alkaline aqueous solutions, aqueous metal sulphate solutions and aqueous metal sulphite solutions.

Method for making a bipolar membrane and use of resulting bipolar membrane

Process for the manufacture of alkali metal hydroxide, according to which an electrodialysis cell containing three compartments is used, an aqueous alkali metal halide solution is circulated in a saline compartment of the cell, delimited between an anionic membrane and a cationic membrane, an alkali metal halide is introduced into an acidic compartment of the cell, delimited between the anionic membrane and a cationic face of a bipolar membrane and an aqueous alkali metal hydroxide solution is extracted from an alkaline compartment of the cell, delimited between the cationic membrane and an anionic face of the bipolar membrane.

Process for the manufacture of alkali metal hydroxide

Electrolyser for the production of a gas, comprising a battery (1) of electrolysis cells with membranes, in which the separation between the anode (8) and the cathode (28) is greater than the thickness of the membrane (4), an electrolyte degassing chamber (15), in communication with the upper part of the anodic (or cathodic) chambers (3), and an electrolyte recycling pipe (20, 21) joining the degassing chamber (15) to electrolyte distributors (10, 11, 12, 13) which are in communication with the anodic (cathodic) chambers (3) of the cells, the recycling pipe (20, 21) having a head loss coefficient which is equal, at most, to the overall coefficient of the head losses of the anodic (cathodic) chambers (3), of the distributors (10, 11, 12, 13) and of the degassing chamber (15).

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Rosignano Solvay, Italy

Luc Botte