DESALINATION METHOD BY ELECTRIC DIALYSIS OF ELECTROLYTE LIQUID WITH SOLVENT

PURPOSE: To efficiently desalt a mixture which is composed of water and a water-soluble highly active org. solvent and contains a metal salt by subjecting the mixture to electrodialysis by using a commercially marketed ion exchange membrane in a process for desalting the mixture composed of the water and the org. solvent. CONSTITUTION: In the process for desalting the mixture which is composed of the water and the water-soluble highly active org. solvent (e.g. N-methyl pyrrolidone) and contains the metal salt egg CaCl2 ), the mixture is subjected to the electrodialysis by using an electrodialysis apparatus equipped with a cathode 1, an anode 2, the cation exchange membrane on the anion exchange membrane and an electrodialysis chamber 3 formed between the membranes. Further, the stop of the electrodialysis may be overcome if an aq. electrolyte soln. free from sulfate ions is used as an electrode washing liquid. The process is particularly suitable for the desalting of the mixture which is composed of the water and the org. solvent and contains up to 80 wt.% solvent and up to 10 wt.% water-soluble metal salt and, therefore, the process is particularly suitable for desalting as a preparatory step of the treatment for distillation of a solidification spinning bath.