Vdović, Neda; Jurina, Irena; Škapin, Srečo D.; Sondi, Ivan
(2010)
The surface properties of clay minerals modified by intensive dry milling — revisited.
Applied clay science, 48
(4).
pp. 575-580.
ISSN 0169-1317
Abstract
The present study broadens the research on the effect of the intensive physical disintegration of clays (kaolinite and “Otay” montmorillonite) and mica (ripidolite) minerals, carried out by high-energy ball milling (HEBM), on their surface physico-chemical characteristics, i.e., the specific surface area (SSA), the cation exchange capacity (CEC), and the electrokinetic properties. It has been shown that the mechanical disintegration of clays occurs in two consecutive processes: in significant changes to the size, morphology and structure of the phyllosilicate solids, followed by the alteration of their physico-chemical properties. The initial particle size diminution of clays resulted in significant increases in the SSA and CEC values, and in the exposure of new, amphoteric surfaces to the experimental environment, significantly changing their electrophoretic mobilities (EPM). Prolonged milling produces amorphous alumina-silicate aggregates. These solids exhibited the same morphological properties, SSA and CEC, despite the fact that they were formed from initially different clay minerals, in the sense of their structural, chemical, and surface physico-chemical characteristics. In contrast, the electrophoretic mobilities of these samples have shown altered characteristics, exemplifying the significance of the initial chemical composition and the formation of different types of surface structures on the physico-chemical processes at amorphous solid-surface–liquid interfaces.
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