The zeta-potentials of natural and synthetic chrysotiles |
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| Authors: | S Chowdhury JA Kitchener |
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| Institution: | Department of Mining and Mineral Technology, Imperial College, London Great Britain |
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| Abstract: | Different specimens of the asbestos mineral chrysotile show widely different zeta-potentials. Strongly positive values are found with samples containing an excess of magnesia in the form of brucite, Mg(OH)2. Synthetic chrysotile and natural samples containing little or no brucite give moderately positive ζ-values over the pH range 3–11. Feebly positive or weakly negative natural chrysotiles are materials which have suffered weathering; and deliberate acid-leaching of any chrysotile ultimately leaves a strongly negative pseudomorph of silica gel.Since the pH and the ambient concentration of Mg2+ ions near the surface are the main factors controlling ζ, and since chrysotile is readily susceptible to leaching in practically all aqueous media and does not come to a true ionic equilibrium in any practical time, the zeta-potential of an ideal chrysotile surface is a hypothetical concept.The results also explain the temporary colloidal stability of very dilute suspensions of chrysotile in weakly acidic media and the mutual coagulation of chrysotile and amosite slurries. |
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