| Abstrakt: |
Conductimetric titrations, with NaOH, of solutions containing Al ion detect two OH-ions of Al in the acid range, with OH/Al ratios of ions such as Al(OH)2+ and A16(OH)3+15; in the alkaline range aluminate Al(OH)−14 is formed. Similar titrations of an Al-kaolin, prepared by acid washing, give results that can be adequately interpreted in terms of these three ions, i.e. by the reaction with alkali of Al3+ ions balancing the permanent isomorphous replacement charge. If there are reactions with alkali at the edge-faces of the kaolin, e.g. the neutralization of residual positive edge-charge, these edge-charges must be small in comparison with the permanent charge. Bonding by the complex ion Al6(OH)3+15, formed on the surfaces of clay particles, explains why the viscosity of Al clays is greatest at the five-sixths stage of neutralization, because the formation of the hydroxide Al(OH)3 is theoretically equivalent to the measurement of the permanent charge. [ABSTRACT FROM AUTHOR] |
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