| 摘要 |
A salt is double decomposed using an electrodialysis cell comprising an anode and a cathode with a membrane unit between them. The membrane unit comprises, in order from the anode to cathode, a high cation exchange group bipolar membrane, a neutral bipolar membrane and an anion exchange resin membrane. The cation exchange bipolar membrane comprises a layer (a) of a resin having an anion exchange group bonded thereto and a layer of a resin having a cation exchange group bonded thereto. The anion exchange layer is from 100A thick to half the thickness of the membrane. The equiv. ratio of anion exchange groups to cation exchange groups in the membrane is0.01-0.5:1. The neutral bipolar membrane is composed of anion exchange resin layer and a cation exchange resin layer and has a fixed ion concn of at least 10 meq/g H2O. The equiv. ratio of anion exchange gps to cation exchange gps in the membrane is 0.6-2:1. The anion exchange resin has an amino group with a long hydrocarbon chain as an anion exchange group. The compartments between the electrodes and membranes are successively a salt compartment, a base compartment, an acid compartment, and a salt compartment. A base, an acid and a salt, are introduced to the base compartment, acid compartment and salt compartments resp. and a direct current is applied across the anode and cathode.
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