METHOD OF RECOVERING NONPROTON POLAR SOLVENT FROM SALT-CONTAINING AQUEOUS SOLUTION OF SAID SOLVENT

摘要

PURPOSE: To recover an aprotic polar solvent, while avoiding precipitation of metal hydroxides, by desalting an alkaline salt-contg. aq.soln. of the aprotic polar solvent by electro-dialysis while controlling pH of the soln., then distilling the desalted soln. CONSTITUTION: An alkaline salt-contg. aq.soln. of the aprotic polar solvent is desalted by electrodialysis, then the desalted soln. is distilled. During the electrodialysis, a value of pH of the soln. is kept at 1-7. When the brine is acidified as above, an alkaline soln. to be desalted is still not acidified, so precipitation of hydroxides of metals such as zinc is avoided, and don't affect no harmful influence on a resistivity of the yarn or stability of dimethyl sulfoxide(DMSO).