| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for carrying out electrodialysis stably for a long time without generating scales consisting essentially of silica on the surface of an ion exchange membrane during the electrodialysis when desalted acid silica sol which can be used suitably as a ground improving material is manufactured by desalting salt-containing acid silica hydrosol by an ion exchange membrane electrodialysis method. SOLUTION: The desalted acid silica sol is manufactured by using an electrodialyzer prepared by forming alternately a desalting chamber, in which a cation exchange membrane and an anion exchange membrane are arranged alternately between the anode and the cathode so that the anode side and the cathode side are partitioned respectively with the anion exchange membrane and the cation exchange membrane, and a concentrating chamber, in which the anode side and the cathode side are partitioned respectively with the cation exchange membrane and the anion exchange membrane, and supplying the acid silica hydrosol containing alkali metal salt to the desalting chamber to carry out the electrodialysis. At that time, the pH of the aqueous solution in the concentrating chamber is made to be equal to or smaller than that of the solution in the desalting chamber by adding an acid or the like to carry out the electrodialysis.
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