Various silicas (silica gel, silochrome, alumosilica, Aerosil and quartz) were modified by dehydroxylation, calcium hydroxide, aluminium chloride and organosilanes with hydrophobic and aminopropyl groups. The surface characteristics of the modified materials were evaluated by means of basic and acid dye adsorption from aqueous solution. The degree of modification, the hydrolytic stability of the organosilyl silicas and the rehydroxylation rate of the dehydroxylated silicas were determined via the kinetics of dye adsorption and their respective isotherms.
