| 摘要 |
Silica sol is made by electrodialysis of a solelectrolyte containing an aqueous silica sol, aqueous sodium or potassium silicate, and a supplementary electrolyte such as sodium or potassium carbonate or sulfate. Temperature is maintained at 50 DEG to 100 DEG C. A source of non-siliceous anion is added as needed to maintain normality of the supplementary electrolyte between 0.01 and 0.15, and silicate is added as necessary to maintain pH between 8.0 and 9.5. After the electrodialysis, most of the sodium ions and the anions of the supplementary electrolyte are removed by treatment with ion exchange resins, then the sol is concentrated to 30 or 40 percent silica.
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