The Solubility of Silica in Hydrogen Beidellite1

C. M. Woodruff
University of Missouri, Columbia, Missouri
1 Contribution from Department of Soils, Missouri Agricultural Experiment Station, Journal Series No. 1400.

Abstract: Electrodialyzed suspensions of clay minerals are viewed generally as insoluble silicates in which the exchange complex is saturated with hydrogen. An investigation of the relative activities of different exchangeable ions on beidellite clay brought to light the fact that a freshly prepared hydrogen clay containing a trace of the non-adsorbed chloride ion, when filtered, yielded a solution containing the chloride ion in association with silica rather than with hydrogen.

The filtrate from the freshly prepared suspension was clear and had a pH value of 5.5. After standing 24 hours the filtrate became cloudy and the pH value dropped to 3.5 corresponding to the concentration of acid produced by the chlorides in association with hydrogen. Analysis of the clear filtrate revealed that the chlorides were associated with silica. The amount of soluble silica in the filtrate from the clay suspension was related directly to the amount of exchangeable hydrogen in the clay. No soluble silica was present in the filtrate from clay which had been neutralized with either potassium or calcium hydroxide.

Clays and Clay Minerals; 1953 v. 2; no. 1; p. 120-123; DOI: 10.1346/CCMN.1953.0020110
© 1953, The Clay Minerals Society
Clay Minerals Society (www.clays.org)