Abstract
Allophane and imogolite were synthesized from two kinds of monosilicic acid and aluminium trichloride, to study the influence of co-existing ion concentration and titration rate of NaOH on the interaction of aluminium ions with monosilicic acid on the synthetic formation of allophane and imogolite. Following results were obtained;
1) Imogolite was synthesized from 5mmol/l monosilicic acid or less, and allophane was synthesized from 10mmol/l monosilicic acid or more. Allophane was synthesized in the condition of high ion concentration, and imogolite was synthesized in the condition of low ion concentration.
2) The formation of allophane and imogolite were more influenced by the concentration of chloride ion than that of monosilicic acid, aluminum ion and sodium ion. The boundary condition of forming them was chloride ion of about 26 millimolar.
3) In the synthesis from sodium orthosilicate, titration rate of NaOH did not influence the formation of allophane and imogolite. But in the synthesis from 5mmol/l tetraethyl orthosilicate or more, as titration rate of NaOH grew faster, the formation of boemite increased in volume. Ethanol may influence the formation of proto-imogolite, thus hinder the subsequent formation of allophane and imogolite.
