pH dependent changes in the rates and stoichiometry of dissolution of an alkali feldspar at room temperature.

Abstract

Experimental investigation of the rates and stoichiometry of dissolution of a Na-rich alkali feldspar shows that the dissolution reaction is non-stoichiometric over a range of pH values, and that a leached layer enriched in silica develops at reaction sites under mildly acidic conditions. The reaction stoichiometry is apparently controlled by the pH. The experimental results suggest that the dissolution mechanism is a two-step process involving the hydrolysis of Al and the creation of sites within the feldspar framework in which silicon hydrolysis subsequently occurs. -M.S.