Release of ions from kaolinite dispersed in deflocculant solutions

Chemical investigations have been performed on deflocculated suspensions of kaolinite previously treated with two widely employed dispersants: sodium hexametaphosphate (NaHMP) and sodium disilicate (NaDIS). Remarkable differences in the rheological behaviour are known to exist between untreated and treated samples [Andreola, F., Castellini, E., Lusvardi, G., Menabue, L., Romagnoli, M., 2006b. Role of the surface treatment in the deflocculation of kaolinite. Journal of the American Ceramic Society, 89, 1107–1109.]. The release of ions by kaolinite dispersed in deflocculant solutions results strongly affected by the nature of the treatment. The chemical analysis of the solution phase separated from the suspensions of treated and untreated kaolinite provides relevant information about the deflocculation mechanism of HMP and DIS and gives reason of the observed differences in the rheological responses.