HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Shainberg, I. Articles by Kaiserman, A. Search for Related Content PubMed Articles by Shainberg, I. Articles by Kaiserman, A. GeoRef GeoRef Citation Agricola Articles by Shainberg, I. Articles by Kaiserman, A.

Kinetics of the Formation and Breakdown of Ca-Montmorillonite Tactoids¹

ABSTRACT

The kinetics of Ca-montmorillonite tactoid formation and breakdown was followed by recording the changes in light transmission as a function of time when Ca-montmorillonite suspensions of 0.05% (w/v) concentration were added to Na-montmorillonite suspensions of the same concentration in a titrating vessel placed in the light path of a spectrophotometer. Tactoid formation was found to be instantaneous whereas the breakdown of Ca tactoids took about 10 min. It was suggested that the initial step upon mixing sodium and calcium montmorillonite was the redistribution of adsorbed ions. For tactoids to break, ions have to interdiffuse into the tactoids. Since the mobility of ions adsorbed on the internal surfaces is low, tactoid breakdown is slow. Ion diffusion on the single platelets of Na clay and the external surfaces of the tactoids is high; thus the formation of tactoids is instantaneous.

¹ Contribution from the Department of Soil Mechanics, Negev Institute for Arid Zone Research, Beer-Sheva, Israel.

² Senior Soil Scientist and Soil Scientist, respectively, Negev Institute for Arid Zone Research.

Received for publication December 27, 1968. Accepted for publication February 11, 1969.