Abstract
Electrophoretic mobility of binary mixtures of imogolite and montmorillonite, kaolinite, hydrated halloysite and allophane was measured using a microelectrophoresis technique.
In acidic media, the negative electrophoretic mobility of the crystalline clays decreased to zero by the addition of imogolite with the positive electrophoretic mobility, and these two oppositely charged clays were flocculated. Montmorillonite required a larger amount of imogolite to complete flocculation than the 1: 1 type clays. When the imogolite content exceeded a neutralization point, the mixtures dispersed in the acidic media and they showed a positive electrophoretic mobility, where imogolite behaved as a protective agent. This effect was more marked for the mixtures containing the 1: 1 type clays than montmorillonite. The allophane-imogolite mixture showed, however, an electrophoretic mobility similar to that of allophane itself.
In alkaline media, the negative electrophoretic mobility of allophane and crystalline clays was decreased by the addition of imogolite. This decrease was more marked when imogolite was subject to the ultrasonic treatment for a longer time. The flocculation of other clay minerals in alkaline media by imogolite appeared to relate with the network formation of imogolite.
