High performance bipolar membranes
First Claim
1. A bipolar membrane comprising conjoined, modified anion and cation exchange membranes, said modified membranes comprising anion and cation exchange membranes modified by(a) treatment with an aqueous solution of at least one monovalent or higher oxidation state cation, excluding sodium and potassium, prior to being conjoined, and(b) treatment of at least one face of one of the anion and cation exchange membranes with an aqueous alkaline solution, at least one of said aqueous solution and of said aqueous alkaline solution being hot,said bipolar membrane when tested in an electrodialysis cell containing 2N sodium hydroxide and 2N hydrochloric acid exhibiting a potential difference across said membrane substantially lower than that exhibited by a bipolar membrane formed from unmodified anion and cation exchange membranes for a period of at least 100 hours.
0 Assignments
0 Petitions
Accused Products
Abstract
A low electrical resistance bipolar membrane formed by the conjoining of treated anion and cation exchange membranes is disclosed. The treatment comprises contacting the membranes with an aqueous solution of at least one cation prior to conjoining and contacting at least one face of the membranes with an aqueous alkaline solution.
A process for the preparation of acid and alkali using these bipolar membranes is also disclosed.
19 Citations
35 Claims
-
1. A bipolar membrane comprising conjoined, modified anion and cation exchange membranes, said modified membranes comprising anion and cation exchange membranes modified by
(a) treatment with an aqueous solution of at least one monovalent or higher oxidation state cation, excluding sodium and potassium, prior to being conjoined, and (b) treatment of at least one face of one of the anion and cation exchange membranes with an aqueous alkaline solution, at least one of said aqueous solution and of said aqueous alkaline solution being hot, said bipolar membrane when tested in an electrodialysis cell containing 2N sodium hydroxide and 2N hydrochloric acid exhibiting a potential difference across said membrane substantially lower than that exhibited by a bipolar membrane formed from unmodified anion and cation exchange membranes for a period of at least 100 hours.
-
17. A method for the preparation of a bipolar membrane from modified anion and cation exchange membranes which bipolar membrane when tested in an electrodialysis cell containing 2N hydrochloric acid and 2N hydroxide exhibits a potential difference across said membrane substantially lower than that exhibited by a bipolar membrane formed from unmodified anion and cation exchange membranes for a period of at least 100 hours, said method comprising modifying anion and cation exchange membranes by
(a) treating an anion exchange membrane and a cation exchange membrane with an aqueous solution of a salt, said salt yielding in the solution at least one monovalent or higher oxidation state cation, excluding sodium and potassium; -
(b) conjoining the treated anion and cation exchange membranes; and (c) treating at least one face of the conjoined membranes with an aqueous alkaline solution, to give said bipolar membrane, at least one of said aqueous salt solution and said aqueous alkaline solution being hot, to thereby obtain said membrane. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
-
-
28. A method for the preparation of a bipolar membrane from modified anion and cation exchange membranes which bipolar membrane when tested in an electrodialysis cell containing 2N hydrochloric acid and 2N sodium hydroxide exhibits a potential difference across said membrane substantially lower than that exhibited by a bipolar membrane formed from unmodified anion and cation exchange membranes for a period of at least 100 hours, said method comprising modifying anion and cation exchange membranes by
treating an anion exchange and a cation exchange membrane with a hot aqueous alkaline solution of a salt, said salt yielding in the solution at least one monovalent or higher oxidation state cation, excluding sodium and potassium; - and then conjoining the modified membranes to give said bipolar membrane.
- View Dependent Claims (29, 30, 31, 32, 33, 34, 35)
Specification